UNEP
Cleaner Production~
Energy Efficiency
MANUAL
About the CP-EE Manual
Contents listing
Part 1
CP-EE methodology
Part 2
Technical modules
Part 3
Tools and resources
Guidelines for the Integration of
Cleaner Production and Energy Efficiency
United Nations Environment Programme
Division of Technology, Industry and Economics
Cleaner Production–Energy Efficiency (CP-EE) Manual
© Copyright 2004 UNEP
This publication may be reproduced in whole or in part and in any
form for educational or non-profit purposes without special permission
from the copyright holder, provided acknowledgement of the source
is made. UNEP would appreciate receiving a copy of any publication
that uses this publication as a source.
No use of this publication may be made for resale or for any other
commercial purpose whatsoever without prior permission in writing
from UNEP.
First edition 2004
The designations employed and the presentation of the material in this
publication do not imply the expression of any opinion whatsoever on
the part of the United Nations Environment Programme concerning
the legal status of any country, territory, city or area or of its
authorities, or concerning delimitation of its frontiers or boundaries.
Moreover, the views expressed do not necessarily represent the
decision or the stated policy of the United Nations Environment
Programme, nor does citing of individual companies, trade names or
commercial processes constitute endorsement.
UNITED NATIONS PUBLICATION
ISBN: 92-807-2444-4
Designed and produced by Words and Publications, Oxford, UK
Cover photographs courtesy of Photodisc Inc.
Cleaner Production – Energy Efficiency Manual
page b
Preface
These Guidelines for the Integration of Cleaner Production and Energy Efficiency are part of a UNEP
effort to link the professional disciplines of Cleaner Production and Energy Efficiency in a more
systematic manner. They were developed during a project that saw National Cleaner Production
Centres (NCPCs) in six countries pull energy management principles into the resource efficiency
approach that lies at the heart of Cleaner Production.
The National Productivity Council of India prepared the draft manual, which was then used by NCPC
staff in China, the Czech Republic, Hungary, India, the Slovak Republic and Vietnam. Together these
NCPCs then tested the Cleaner Production–Energy Efficiency methodology in almost 100 companies.
Their experiences in applying the Guidelines helped improve the working draft, as did the editorial
skill of Geoffrey Bird.
The manual has also benefited from comments and suggestions provided by external reviewers, most
notably Thomas Bürki.
Preparation of the manual was coordinated at UNEP by Amr Abdel Hai. Surya Chandak and Mark
Radka also contributed to the effort, which was conducted as a joint activity between UNEP’s Cleaner
Production and Energy programmes.
Cleaner Production – Energy Efficiency Manual
page i
About the CP-EE Manual
Objectives of the Manual
This electronic manual is part of UNEP DTIE's broad effort to strengthen the energy component of
Cleaner Production (CP) assessments carried out by National Cleaner Production Centres (NCPC).
The Manual presents an integrated Cleaner Production–Energy Efficiency (CP-EE) methodology
based on the proven CP methodology and combines this with factual information, technical data,
worksheets, and tools and resources that will allow both technical specialists and managers to take
direct and effective action.
The guidance provided in the manual can be used by facility personnel conducting in-house
assessments and by consultants interested in providing industrial assessments. CP professionals (who
are not energy specialists) will find guidance on how to better incorporate energy issues into their CP
assessments at industrial or other facilities. Managers will gain insight into the role they can play in
instigating and supporting an ongoing, cost-effective process that has both economic and
environmental advantages.
Structure of the Manual
The CP-EE Manual makes full use of the advantages of its electronic format, providing readers with
‘hyperlinks’ to the sections that are most relevant to their needs. This aspect is explained further in
‘Navigating the Manual’ on the following page.
Part 1 CP-EE methodology
The first two chapters lay the foundations of the CP-EE assessment methodology for all readers.
Chapter 1 introduces the benefits of integrating CP and EE and of producing a CP-EE methodology.
This is followed, in Chapter 2, by a full explanation of the five steps that make up the methodology.
Readers are then ‘walked through’ the tasks that comprise each step. These simple and easy to follow
explanations are accompanied by a ‘Running Example’ in the form of Completed Worksheets taken
from the actual CP-EE assessment of a textile processing house in India.
Worksheets are an important tool for CP-EE assessment and blank versions of those used for the
Running Example are provided on the CP-EE CD-ROM in editable, printable form, allowing users to
adapt them to their own purposes (see Navigating the Manual on the following page).
The third and final chapter of Part 1 presents the full Case Study of the textile firm used for the
Running Example in Chapter 2.
Cleaner Production – Energy Efficiency Manual
page ii
… About the CP-EE Manual (continued)
Part 2 Technical modules
Module 1 provides background information on different energy-using systems (thermal and
electrical), information that will be helpful in identifying areas of focus for CP-EE assessments.
Module 2 presents Energy Efficient Technologies. Module 1 includes further worksheets that can be
used during assessment.
Part 3 Tools and resources
Part 3 provides tools and resources for everyday use, including: checklists (of procedures that improve
energy efficiency and safety in energy-using equipment); thumb rules (for rapid assessment of the
efficiency of major energy systems); a summary of different types of measuring instruments; links to
sources of information on the Internet; conversion tables (equating SI, metric and other units); and a
summary of acronyms and abbreviations used throughout the Manual.
An additional feature of Part 3 is UNEP’s ‘GHG Indicator’—a spreadsheet based calculator that
allows users to compute the greenhouse gas (GHG) emissions from their facilities. Hyperlinks provide
access to the GHG Indicator either on UNEP’s website or on the CP-EE CD-ROM.
Navigating the Manual
Hyperlinks are provided throughout the three Parts of the Manual, allowing readers to navigate within
the document and to access Internet based and additional resources with ease. For example:
• Hyperlinks in the contents pages and at the beginning of each main Part enable readers to jump
directly to the topics of their choice.
• Blank versions of the sample Worksheets presented in Parts 1 and 2 are included on the CP-EE CD-ROM
in editable (Microsoft® Word™) format. These can be opened individually by clicking on the
‘Open File’ button at the top right hand corner of the Worksheets displayed in the Manual.
• UNEP’s GHG Indicator is included on the CD-ROM and can be opened directly via the hyperlinks
on the contents page and in Part 3 of the Manual.
• Part 3 includes a comprehensive list of information resources on the Internet. Hyperlinks are
included to provide the reader with direct access to the Internet sites listed. (Note: please read
the disclaimer at the beginning of this section of the Manual before using these resources).
Cleaner Production – Energy Efficiency Manual
page iii
Cleaner Production ~ Energy Efficiency (CP-EE)
Guidelines for the Integration of Cleaner Production and Energy Efficiency
MANUAL
Contents
Preface
i
About the CP-EE manual
ii
Part 1 CP-EE methodology
Chapter 1: Introduction
1
2
1.0 Building on established strategies
2
1.1 Cleaner Production (CP)—a focus on material flows
2
1.2 Energy Efficiency (EE)—a focus on cost reduction
2
1.3 Integrating CP and EE
3
1.4 Areas requiring particular attention when integrating CP-EE
4
Chapter 2: CP-EE assessment methodology
7
2.1 Introduction
7
2.2 CP assessment—an established methodology
8
2.3 EE assessment—towards a methodology
10
2.4 Integrated CP-EE assessment methodology—combining for synergy
10
2.5 Description of a CP-EE methodology
12
2.6 The CP-EE process (incorporating the Running Example)
14
2.7 Worksheets for a CP-EE assessment methodology
61
Chapter 3: Case study
87
3.1 About the company
87
3.2 Process description and process flow chart
88
3.3 Baseline information
91
3.4 Identification of waste streams, cause analysis and CP-EE opportunities
95
3.5 Feasibility analysis of CP-EE options
98
3.6 Benefits and achievements
105
3.7 CP-EE assessment barriers
108
3.8 Conclusions
109
Cleaner Production – Energy Efficiency Manual
page iv
… Contents (continued)
Part 2 Technical modules
Module 1: Energy use in industrial production
Thermal systems
111
112
112
M1.1 Fuels—storage, preparation and handling
112
M1.2 Combustion
116
M1.3 Boilers
121
M1.4 Thermic fluid heaters
135
M1.5 Steam distribution and utilization
137
M1.6 Furnaces
154
M1.7 Waste heat recovery
163
Electrical systems
176
M1.8 Electricity management systems
176
M1.9 Electric drives and electrical end-use equipment
189
M1.10 Cooling towers
222
M1.11 Refrigeration and air-conditioning
227
M1.12 Lighting systems basics
234
Module 2: Energy efficient technologies
240
M2.1 New electrical technologies
240
M2.2 Boiler and furnace technologies
242
M2.3 Heat upgrading systems
244
M2.4 Other utilities
245
Part 3 Tools and resources
247
A: Checklists for enhancing efficiency and safety
248
B: Thumb rules for quick efficiency assessment
260
C: List of energy measuring instruments
262
D: Greenhouse Gas Emissions Indicator
267
E: Information resources
276
F: Conversion tables
287
G: Acronyms and abbreviations
293
Cleaner Production – Energy Efficiency Manual
page v
ENERGY
EFFICIENCY
Cleaner Production – Energy Efficiency Manual
page vi
Part 1
CP-EE methodology
Cleaner Production (CP) and Energy Efficiency (EE)
are established and powerful strategies that reduce costs
and generate profits by reducing waste. Their integration
can provide synergies that broaden the scope of their
application and give more effective results—both
environmental and economic. Integration of these two
powerful strategies is the subject of this manual.
Contents listing
Part 2 Technical modules
Part 3 Tools and resources
Cleaner Production – Energy Efficiency Manual
page 1
Part 1 CP-EE methodology
Chapter 1: Introduction
CP-EE
1.0 Building on established strategies
Both Cleaner Production (CP) and Energy Efficiency (EE) are established and powerful
strategies that reduce costs and generate profits by reducing waste. They are, however,
generally practiced separately, with little or no search for common ground. This is
unfortunate, since CP and EE are often highly complementary and their integration can
provide synergies that broaden the scope of their application and give more effective
results—both environmental and economic. Integration of these two powerful
strategies is the subject of this manual.
1.1 Cleaner Production—a focus on material flows
CP was developed as a preventive strategy to reduce environmental pollution and
simultaneously reduce consumption of material resources. Its main focus is on
processes and on reduction of the resources they use. CP is a new and creative way of
thinking about products and processes that implies continuous application of strategies
to prevent and/or reduce the occurrence of waste. Practitioners of CP call on an
established CP methodology to identify and implement solutions.
As the example below right illustrates, the CP concept can combine real opportunities
for growth with maximum efficiency in use of materials. However, because CP evolved
from environmental concerns about physical pollution arising from material waste
streams and emissions, its proponents and practitioners have focused on material
resource conservation. CP does not, generally, address issues of total resource
productivity holistically, and other avenues of productivity—such as energy
conservation, industrial engineering, value engineering, etc.—have not been well
integrated into the concept. In addition, CP—by definition—does not cover ‘end-ofpipe’ solutions.
1.2 Energy Efficiency—a focus on cost reduction
Efforts to improve energy efficiency in industry began in the early 1970s, driven
primarily by the need to reduce production costs. Although energy is a vital input to
many processes, it is not necessarily a critical cost component. This may explain why
EE practitioners have tended to focus on energy conversion equipment (involving less
risk in terms of process disruption) and have avoided process-related EE options (a
riskier proposition).
There is no universal, systematic methodology characterizing an EE approach and to
which EE practitioners can refer. Individual countries have accordingly adopted their
own strategies to address energy efficiency and energy input costs. Currently, EE is
Cleaner Production – Energy Efficiency Manual
snapshot
A seasoned CP practitioner,
was asked to look into a
large educational institution’s
pumping system to improve
water use. Having recently
acquired EE skills, he was not
only able to reduce wasteful
water consumption by 30
per cent but also to reduce
the energy used for
pumping by 37 per cent
(through reduced use,
optimum pipe size,
simplified distribution
network and reduced head
requirements).
CP-EE
snapshot
A small-scale textileprocessing unit used
winches (heated by direct
firing of solid fuel) for
bleaching and dyeing of
cotton fabric. A CP study
revealed that the unit was
wasting large amounts of
water, dyes and other
chemicals. CP solutions,
including reducing the
material-to-liquor ratio
from 1:20 to 1:15 and
optimizing the chemicals
and dyes, reduced the
consumption of water and
chemicals used and
resulted in annual savings
of US$3 600.
page 2
Part 1 CP-EE methodology
Chapter 1: Introduction
EE
viewed as being highly compartmentalized and, in the absence of an established
methodology, is generally prescriptive and sporadic.
Very few EE practitioners are concerned about the environmental results of
implementation of EE and—even though a fair proportion of EE options lead to benefits
for the environment—these are almost never highlighted. For EE practitioners, cost
reduction is the overriding concern and they will favour economically attractive options
even when these may have negative environmental impacts.
1.3 Integrating CP and EE
1.3.1 Benefits of integrating CP and EE
The numerous, tangible benefits of an integrated CP-EE approach, illustrated succinctly
by the snapshots, are outlined below. Once the benefits have been described, some
consideration is given to important aspects of integration, highlighting differences in
assessing material and energy flows and identifying skills needed for successful CP-EE
integration.
An integrated CP-EE approach offers the following benefits:
I. Expanded service package with greater benefits (synergy)
When resources are low priced (or perhaps subsidized) and/or environmental issues are
not considered significant, a CP solution alone may not be attractive. By combining it
with EE benefits, a more attractive package can be proposed. Similarly, the
attractiveness of reduced energy consumption in a situation where energy prices are
not significant may be enhanced by combining it with CP. An integrated CP-EE
approach draws from a much wider repertoire of best practices, yielding
comprehensive business solutions and more attractive cost benefits.
II. Greater market share for products
CP-EE can lead to products that can genuinely be described as ‘eco-friendly’. ‘Green’
products that warrant both eco and energy rating labels have an additional
competitive edge—they can gain a better market share.
III. Integration ensures sustainability of EE options
To date, the prevailing approach to EE has been task oriented and prescriptive in nature
and EE has not been viewed as part of day-to-day management. EE improvement
programmes have therefore often ended as soon as advisors have left the plants,
resulting in programmes that are sporadic and short-lived.
Cleaner Production – Energy Efficiency Manual
snapshot
A small-scale textileprocessing unit used an
open winch for bleaching
and dyeing of cotton
fabric. The winch was
heated by direct firing of
solid fuel under the tank.
An energy audit indicated
inefficiency in the heating
system resulting in heavy
fuel consumption and less
than optimum bath
temperatures. When, on
the EE professional's advice,
changes were made to the
design of the furnace, the
bath temperature was
increased from 55 °C to
60 °C, and fuel
consumption was reduced.
This brought an annual
saving of US$1 200.
CP-EE
snapshot
An acclaimed EE expert,
was asked by the managers
of a Vietnamese steel plant
to help reduce energy bills.
Using integrated CP-EE
techniques, he not only
brought down oil
consumption and costs by
20 per cent (by fine tuning
excess air in burners of heat
treatment furnaces) but also
reduced scale losses (due to
oxidation) from 3 per cent
to less than 0.5 per cent—
equivalent to an additional
10 per cent of oil savings.
page 3
Part 1 CP-EE methodology
Chapter 1: Introduction
Conversely, continuous application is a key aspect of CP. When CP and EE are
integrated, the notion of continuity becomes extended to EE thereby ensuring its long
term sustainability.
IV. Facilitating implementation of global agreements and protocols
In recent years a number of global and regional agreements and protocols have been
developed covering both environmental and energy issues.
CP-EE can help to mainstream these more easily than CP or EE alone. Some countries
have introduced laws on CP others on EE; a combination of both can help to enforce
material and energy conservation measures simultaneously. A CP-EE group could play
a pivotal role in helping a country’s government towards this end.
V. Less duplication of tasks and synergy between CP and EE objectives
CP and EE professionals spend a lot of time collecting and analysing data separately,
and then generating material and energy savings options, once again separately. An
integrated and simultaneous effort would save a lot of collection and analysis time and
would also lead to simpler ways of addressing interdependent issues of material and
energy waste.
VI. Improving access to a wider range of funding sources
There are global and regional sources of funds available exclusively for CP or exclusively
for EE. These could be accessed jointly by CP-EE.
VII. CP-EE paves the way for implementation of Environmental Management Systems (EMS)
An integrated CP-EE approach, by virtue of its methodology, makes it easier to implement
and sustain a more comprehensive Environmental Management System (EMS).
1.4 Areas requiring particular attention when integrating
CP-EE: hidden wastes and inefficiencies in energy systems
Because CP is generally applied to visible (i.e. material) resource wastes, it leaves little to
chance. Material inputs to a given operation can generally be traced through to
perceivable and quantifiable outputs. This is not always the case when considering
energy streams. While the same basic rule must hold true for energy inputs (i.e. amount
of energy ‘in’ must, ultimately, be equal to the amount of energy ‘out’) output energy
streams are often less easy to perceive than material ones. Identification and evaluation
of hidden waste streams and inefficiencies can therefore be a difficult proposition.
Cleaner Production – Energy Efficiency Manual
page 4
Part 1 CP-EE methodology
Chapter 1: Introduction
This is particularly true for electrically driven equipment such as pumps, fans, air
compressors, etc. where input energy, in the form of electricity, is easily measurable but
the degree to which this is efficiently converted into useful output (e.g. pumped water,
compressed air, etc.) is not directly quantifiable.
The following are examples of typical situations where only looking for visible/perceivable
energy streams can lead to overlooking of energy loss in output streams:
• Loss due to part load operation of energy-using equipment.
• Loss due to (low-efficiency) banking/idling operations of energy using equipment.
• Losses due to resistance to flow (high but avoidable resistance in electricity
conductors and fluid pipelines).
• Loss due to equipment degradation (pump impellers, pump bearings, etc.)
leading to increased losses.
1.4.1 Additional parameters and skills
In order to ascertain the outputs (both perceivable and non-perceivable) from energy
systems, some EE parameters have to be measured/monitored during a CP assessment
in addition to the essential ones—such as temperature, flow, humidity, concentration,
percentage compositions, etc.—already measured as part of CP.
Additional EE parameters that need to be measured/monitored could include:
kW (kilowatt power input); kV (kilovolts—impressed voltage); I (amperes—electrical
current); PF (power factor of induction electric equipment); Hz (frequency of
alternating current); N (rpm or speed of rotating equipment); P (pressure of
liquid/gaseous streams); DP (pressure drops in input/output liquid and gaseous
streams); Lux (light intensity); GCV, NCV (gross and net calorific value of fuels); etc.
CP professionals will need some additional skills to be able to integrate EE during
assessments effectively. They should:
• have a basic understanding of electrical circuits, to be able to measure input
power to motor drives correctly;
• be able to evaluate enthalpy (heat content) in each stream by measuring
temperature, pressure and flow;
• be able to quantify non-perceivable (invisible) streams using known streams. For
example, given pump output parameters (such as pressure developed, flow and
density) they should be able to evaluate work done and thus estimate energy output;
Cleaner Production – Energy Efficiency Manual
page 5
Part 1 CP-EE methodology
Chapter 1: Introduction
CP-EE
• be familiar with and able to convert between various energy, pressure and heat
content units;
• be able to control waste energy streams and learn to correlate the effect of
control measures with conversion efficiency of equipment.
Differences between material and energy flows are considered further when the
methodology for carrying out a CP-EE assessment is presented in Chapter 2.
1.4.2 Possible contradictions
CP and EE are highly complementary, with synergies between the individual benefits
of each delivering a more effective overall outcome. However, there are some situations
where the beneficial results of one methodology (say CP) can be perceived as being in
contradiction with the other methodology (EE). A few simple examples will illustrate
this:
• Recycling is a very profitable CP technique, but recycling of oils, and lubricants,
and reuse of reconditioned bearings or rewinding of burned out motors
(especially when not done properly) often lead to higher energy consumption.
• Refrigeration by vapour absorption is an eco friendly and pro-CP option in
comparison with the prevalent vapour compression machines. However, in terms
of energy use, vapour absorption systems are less efficient.
• Slim fluorescent tube lights are far more energy efficient than incandescent lamps,
but from the environmental (CP) point of view, their mercury coating makes them
less eco-friendly.
Cleaner Production – Energy Efficiency Manual
snapshot
‘EA’, a medium scale edible
oil processing unit in India,
was experiencing high
hexane losses of 4.93 litres
per ton of seeds processed.
CP-EE studies in the plant
revealed that the losses
were primarily due to
inadequate steam supply at
the desired pressure,
inadequate heating surface
area of the reactor vessel,
low vacuum, and
inadequate condenser size.
Further detailed studies of
the boiler revealed that it
did not have the capacity
to supply the required
quantity of steam at
optimum pressure. The
company changed the
boiler and—after necessary
modification of the reactor
vessel to increase the
heating surface area—
reduced hexane losses by
12.2 per cent. Besides
improving its
environmental
performance, the company
improved the quality of the
de-oiled cake. A total
investment of US$255 500
resulted in annual savings
of US$270 000.
page 6
Part 1 CP-EE methodology
Chapter 2:
CP-EE assessment methodology
2.1 Introduction
From the arguments presented in Chapter 1, the benefits, and the possible
importance, of integrating CP and EE should now be clear. This second section looks
at methodology, and shows how the proven method of carrying out a CP assessment
can be expanded to ensure a systematic approach to EE.
Traditionally, EE assessments have been driven by a need for quick solutions, to be
implemented quickly, and for quick profits. EE assessments and projects have therefore
tended to be needs-based, arising from situational demands, and have generally relied
on external EE expertise. There has been no perceived need to develop in-house
capacities to foster continuous improvement programmes. As a consequence, EE
assessments and implementation of the resulting projects have tended to be ad hoc,
piecemeal, and less logically structured than CP assessments.
If CP-EE coverage is to be comprehensive, a CP-EE assessment—like a CP assessment—
must be conducted systematically. A structured approach is essential to get the best
results and to ensure that the outcomes are consistent with those identified in the
enterprise's broader planning process. A step-by-step procedure based on a sound
methodology will ensure maximum benefit from CP-EE opportunities.
The assessment method should be flexible enough to accommodate unforeseen
circumstances and problems, and to allow solutions to be identified. How formal the
method needs to be will depend on the size and composition of the company, on its
material and energy use, and on specific aspects of its waste production.
The CP-EE assessment method should also ensure better use of available resources
(manpower, machinery, material, money) and should foster logical and sequential
thinking.
A CP-EE assessment is an excellent way of building a waste avoidance culture and of
creating competence within the company that is crucial for long-term sustainability.
And finally, if the CP-EE programme is to be effective and continuous, it is essential to
involve people from the different sectors of the company in its implementation.
Cleaner Production – Energy Efficiency Manual
page 7
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
2.2 CP assessment—an established methodology
Assessment, involving analysis of the material and energy flows entering and leaving a
process, is a central element of CP. Conducting a CP style assessment relies on a logical
and methodical approach that makes it possible to identify opportunities for CP, to
solve waste and emission problems at source, and to ensure continuity of CP activities
in a company. This analytical assessment approach is embedded in the CP
methodology, shown in Figure 1.1.
The basic CP methodology consists of the following principal elements:
• Planning and Organization
• Pre-assessment
• Assessment
• Feasibility Analysis
• Implementation and Continuation.
Figure 1.1 CP methodology
prepare a cleaner production implementation plan
sustain cleaner production assessments
Implementation
and Continuation
select feasible options
Planning and
Organization
obtain commitment of top management
conduct economic and
environmental evaluation
involve employees
Feasibility
Analysis
organize a team
screen options
compile existing basic information
identify barriers and solutions to the CPA process
generate options
conduct cause diagnosis
decide the focus of the CPA
prepare a detailed material
and energy balance
Pre-assessment
compile and prepare basic information
Assessment
conduct a walkthrough
prepare an eco-map
prepare a preliminary material and energy balance
Cleaner Production – Energy Efficiency Manual
page 8
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Figure 1.1 shows the generic CP methodology. However, in practice, different
institutions and practitioners have expanded and/or modified the steps in this basic
methodology and have developed specific tasks at each step that suit local conditions
and specific requirements. A typical empirical CP methodology is presented in Figure
1.2. This is used later (in Section 2.5) to develop a CP-EE assessment methodology that
adheres strictly to the steps presented here but also includes specific features that need
to be covered to integrate energy efficiency aspects.
Figure 1.2 Steps of the CP methodology
STEP 1: Planning and Organization
Task 1:
Task 2:
Task 3:
Task 4:
Task 5:
Task 6:
Obtaining commitment and involvement of top management
Involving employees
Organizing a CP team
Compiling existing basic information
Identifying barriers and solutions to the CP assessment process
Deciding the focus of the CP assessment
Task 7:
Task 8:
Task 9:
Task 10:
Preparing a process flow diagram
Conducting a walkthrough
Preparing material input-output quantification and characterization
Generating and finalizing base data
STEP 2: Pre-assessment
STEP 3: Assessment
Task 11:
Task 12:
Task 13:
Task 14:
Preparing a detailed material balance with losses
Conducting cause diagnosis
Generating options
Screening options
STEP 4: Feasibility Analysis
Task 15: Conducting technical, economic and environmental evaluation
Task 16: Selecting feasible options
STEP 5: Implementation and Continuation
Task 17: Preparing CP implementation plan
Task 18: Sustaining CP assessments
Cleaner Production – Energy Efficiency Manual
page 9
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
2.3 EE assessment—towards a methodology
For most companies, it is the absence or disruption of energy supply that is perceived
as having a dramatic impact on the process, not day-to-day energy consumption.
Energy is viewed as a crucial input but not always as an important cost intensive one.
There has therefore been little motivation and incentive to develop riskier but more
rewarding energy reduction initiatives in manufacturing process.
EE improvements have generally been made to standard energy converting
equipment—such as boilers, furnaces, heaters, dryers, ovens and kilns, and electrically
driven equipment such as pumps, fans, air compressors, refrigeration compressors,
etc.—with little effort on process and production related equipment and technology.
All industrial and commercial facilities have some energy conversion equipment, and
nearly all of this has well standardized performance assessment procedures and
reference performance indicators. The existence of these procedures and indicators is
seen as making a logical, structured and comprehensive methodology unnecessary and
gives little incentive for innovation and creativity in approach and methodology.
Over a period of time, this has led to development of very mature, proven, costeffective and standardized prescriptive solutions, with very little effort going into the
development of creative alternatives.
2.4 Integrated CP-EE assessment methodology—
combining for synergy
Section 1.4 outlined important differences between CP and EE assessments,
underscoring the differences between material and energy flows and some of the
difficulties of quantifying the latter. The material below builds on that information,
going into greater detail on how energy flows can be quantified.
a) In a CP assessment, material streams are identifiable and quantifiable at both input
and output stages, since the material streams do not generally change form. In a
CP-EE assessment, however, care must be exercised when accounting for energy,
since energy is largely invisible at input and changes form within the process.
Electricity, for example, is used to drive motors but also to compress air as well as
for lighting, heating, etc. It may be identifiable and quantifiable at the input stage,
but it is much more difficult to identify and quantify at output.
Cleaner Production – Energy Efficiency Manual
page 10
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
b) Whenever energy changes form there are some inevitable losses. For CP, these
losses are not considered as important because they do not have a significant direct
impact on the environment. For EE, on the other hand, identification of the areas
where these losses occur is of great importance.
c) To identify losses, CP-EE studies have to include measurement of parameters not
measured for CP (e.g. temperature, tension in belts, lumens for lighting, etc.).
There are also parameters such as friction, surface tension, etc. which cannot be
perceived directly and which cannot therefore be measured directly. In these
cases estimates have to be made using empirical equations.
d) CP does not identify waste streams unless they are in the form of material waste.
For instance, in a combustion process, a CP study will measure the airflow before
and after combustion (in stack). If the quantities match, little or no further
attention will be paid to this stream. For EE studies, however, excess air levels in
the flue gas (in stack) are of great importance. Similarly a stream of hot
wastewater is a material waste for CP, for EE it is a heat loss.
e) In a CP assessment it is relatively easy to produce a material and mass balance for
a process because, as already explained, material streams do not generally change form1.
It is more difficult for a CP-EE assessment to produce an exact energy balance right across
a process since energy is invisible and changes its form. Even perceivable losses, such
as iron or copper losses, eddy current loss in motors, friction losses etc., are difficult to
measure and quantify. A different approach has to be adopted to obtain energy balances.
Some options for producing an energy balance are:
i) System efficiency based on measurable energy input and work output
For example, fan delivery air can be measured (in m3) against power consumed (in
kW), giving an indication of efficiency as kW/m3. A similar indication could be given for
a refrigeration system, as kW/TR.
ii) Measurement of major loss only
Sometimes input and output energy streams are difficult to measure. This would be the
case, for example, for steam flowing in a pipeline over a long distance and where it is
possible to measure neither input steam, owing to lack of flow meters, nor output heat
effect, because of the very narrow temperature difference. However, parameters such
as surface losses or radiation losses can be measured.
1
Even when some of the materials do change form (e.g. vapour loss from water during
heating) the changes are usually very small.
Cleaner Production – Energy Efficiency Manual
page 11
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
iii) Single parameter measurement and benchmark comparison
For systems like agitators, where even measuring of losses is not practicable,
comparative efficiency levels can be obtained by measuring the electricity input and
comparing it with input for similar systems elsewhere.
The causes of energy waste are well known, relatively uniform and standard and, at
times, making an exhaustive cause analysis may seem superfluous (e.g. Waste = excess
air in flue gas. Cause = air fan supplying too much air or air ingress). However, until the
CP-EE team becomes fully conversant with the normal/standard causes, it may still be
advisable to conduct an exhaustive cause analysis, to avoid overlooking possible causes.
2.5 Description of a CP-EE methodology
The CP-EE methodology (shown in Figure 1.3) follows the same generic, systematic
and step-by-step approach as the CP methodology, and is characterized by the same
five steps. For a CP practitioner, the basic assessment methodology remains the same,
the difference lying in some of the specific tasks, in particular those in Step 2, and in
the details of the material and energy balance, in Step 3.
Figure 1.3 CP-EE methodology
START HERE
Planning and
Organization
STEP 1
Implementation
and Continuation
STEP 5
Feasibility
Analysis
STEP 4
Cleaner Production – Energy Efficiency Manual
Pre-assessment
STEP 2
Assessment
STEP 3
page 12
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Figure 1.4 CP-EE assessment methodology
STEP 1: Planning and Organization
Task 1:
Task 2:
! Task 3:
! Task 4:
Task 5:
! Task 6:
Obtaining commitment and involvement of top management
Involving employees
Organizing a CP-EE team
Compiling existing basic information
Identifying barriers and solutions to the CP-EE assessment process
Deciding the focus of the CP-EE assessment
Note: the ! next to the
Tasks in Figure 1.4 indicate
Tasks which require additional
skills, expertise, data
collection and work; these
Tasks are similarly indicated
where they occur in the text.
STEP 2: Pre-assessment
! Task 7:
Task 8:
! Task 9:
Preparing a process flow diagram
Conducting a walkthrough
Preparing material and energy input-output quantification
and characterization
! Task 10: Generating and finalizing base data
STEP 3: Assessment
! Task 11: Preparing a detailed material and energy balance with losses
! Task 12: Conducting cause diagnosis
! Task 13: Generating options
Task 14: Screening options
STEP 4: Feasibility Analysis
Task 15: Conducting technical, economic and environmental evaluation
Task 16: Selecting feasible options
STEP 5: Implementation and Continuation
Task 17: Preparing CP-EE implementation plan
Task 18: Sustaining CP-EE assessments
Cleaner Production – Energy Efficiency Manual
page 13
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
2.6 The CP-EE process
Introduction
This section describes the CP-EE process. It gives detailed comments on each of the 18
tasks that make up the 5 steps of the process, and presents a set of Worksheets—the
tools for conducting an assessment—at the end of the section*.
To better illustrate the steps of the CP-EE assessment methodology, a ‘Running
Example’ is presented in this section of the manual. It is described as a ‘running’
example because it recurs throughout the section presenting relevant data and values,
in the form of Completed Worksheets, as each task of the five steps of the CP-EE
methodology is explained.
The data and values used in the Completed Worksheets are taken from an actual CP-EE
assessment carried out in 2002 at M/s Luthra Dyeing and Printing Mills (LDPM), Surat,
India. LDPM is a well-equipped textile processing house that is representative of the
synthetic fabric processing sector in India. A full description of the step by step CP-EE
assessment of LDPM is presented as a ‘Case Study’ contained in Chapter 3.
STEP 1
* The Worksheets
presented in Section 2.7
are included on the
CD-ROM in Microsoft®
Word™ format. These
editable files can be
opened by clicking on the
‘Open File’ button in the
top right corner of each
Worksheet displayed in the
Manual.
Planning and Organization
The planning and organization step is one of the most important for a successful CP-EE
assessment. It consists of the following six tasks:
•
•
•
•
•
•
Obtaining commitment and involvement of top management
Involving employees
Organizing a CP-EE team
Compiling existing basic information
Identifying barriers and solutions to the CP-EE assessment process
Deciding the focus of the CP-EE assessment.
Planning can begin once the members of the CP-EE team are identified and once the
interest of management in CP-EE has been obtained—often as a result of awareness
raising. However, a CP-EE assessment can only be initiated after a decision has been
made by the management to take action.
Cleaner Production – Energy Efficiency Manual
page 14
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
The CP-EE assessment may be conducted by an internal company team or by hiring
external CP-EE professionals.
Task 1
Obtaining commitment and involvement
of top management
If the company decides to involve external CP-EE professionals (consultants) a
meeting is generally organized between the consultants and top management
to formalize this decision.
Typically, a memorandum of understanding (MoU) is drawn up between the
consultants and the company to define the CP-EE objectives; establish a work
plan that will indicate a time frame, sharing of responsibilities and outcomes;
and to set fees.
The management of the company has to set the stage for the CP-EE assessment
in order to ensure cooperation and participation of the staff members. In addition
to signing the MoU, top management's commitment should take the form of:
• management of formation of a CP-EE team;
• ensuring availability of required resources;
• provision of necessary training, awareness-raising meetings for employees;
and
• responsiveness to the CP-EE results.
It is also important to assess the following:
• Where does the company stand in relation to environmental and energy
policies and to what extent have these been implemented?
• What is the status of environmental and energy management in the
company?
• What is the status of internal communications at different levels in the
company, of information flow, and of initiatives to raise awareness of energy
and environmental management issues amongst employees?
The Completed Worksheet 1 in the Running Example on the following page
shows how a matrix can facilitate assessment of managerial aspects.
Cleaner Production – Energy Efficiency Manual
page 15
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Running Example: Task 1
Obtaining commitment and involvement of top management
CP-EE is not just a matter of finding technical solutions, numerous other factors influence
energy management and the identification and implementation of CP-EE options both
directly and indirectly. Commitment and involvement of a firm's top management are
therefore essential—CP-EE can only be initiated after management has made the
decision to act.
An Environmental Management Matrix like the one shown below2 (as the first
Completed Worksheet) can be used to foster management involvement and assist in
making decisions and identifying potential CP-EE solutions. Completing the matrix
indicates where the company stands in relation to six energy/environmental
management areas: policy and systems, organization, motivation, information systems,
awareness and investment.
The matrix presented below is the one used at M/s Luthra Dyeing and Printing Mills
(LDPM), Surat, India, the information being based on interviews with management and
presentations during an initial meeting on energy and environmental management
activities.
Based on interview outcomes, bullet points are inserted in the matrix, and these are
connected to give a curve (as shown in the matrix below). The peaks indicate where
current efforts are most advanced; the troughs indicate where the company is least
advanced. It is not unusual for the 'curve' to be uneven, this is the case for most
organizations.
The matrix helps to identify aspects where further attention is required to ensure energy
and environmental management is developed in a rounded and effective way. It will also
assist in organizing an energy and environmental management system.
How to use the matrix
• Senior management staff and the CP-EE Team Leader are given a blank version of
the matrix. Ask them to indicate on it what they believe to be their company’s
present situation. A score of ‘4’ for a specific category means that all initiatives
mentioned in categories 0 to 4 must be present.
• Hold a 1-hour interview with senior management to check the real position.
• Based on interview outcomes, insert the bullets in the matrix and connect them up.
2
Modified from the Energy Management Matrix provided by the Sustainable Energy Authority
of Victoria, Australia, www.seav.vic.gov.au
Cleaner Production – Energy Efficiency Manual
page 16
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
… Running Example: Task 1 (continued)
Completed Worksheet 1
Level
Policy and systems
Organization
Motivation
Information
systems
Awareness
Investment
4
Formal energy/
environmental policy
and management
system, action plan and
regular review with
commitment of senior
management or part of
corporate strategy
Energy/environmental
management fully
integrated into
management structure.
Clear delegation of
responsibility for energy
use
Formal and informal
channels of
communication
regularly used by
energy/environmental
manager and staff at all
levels
Comprehensive system
sets targets; monitors
materials and energy
consumption, wastes
and emissions;
identifies faults;
quantifies costs and
savings; and provides
budget tracking
Marketing the value of
material and energy
efficiency and the
performance of
energy/environmental
management
Positive discrimination
in favour of energy/
environmental saving
schemes with detailed
investment appraisal
of all new building
and plant
improvement
opportunities
3
Formal energy/
environmental policy
but no formal
management system,
and with no active
commitment from top
management
Energy/environmental
manager accountable
to energy committee,
chaired by a member of
the management board
Energy/environment
committee used as
main channel together
with direct contact with
major users
Programme of staff
Monitoring and
awareness and training
targeting reports for
individual premises
based on submetering/monitoring,
but savings not reported
effectively to users
Same pay-back criteria
as for all other
investments. Cursory
appraisal of new
building and plant
improvement
opportunities.
2
Unadopted/informal
energy/environmental
policy set by
energy/environmental
manager
Energy/environmental
manager in post
reporting to ad hoc
committee but line
management and
authority unclear
Contact with major
users through ad hoc
committee chaired by
senior departmental
manager
Monitoring and
targeting reports based
on supply
meter/measurement
data and invoices.
Env./energy staff have
ad hoc involvement in
budget setting
Some ad hoc staff
awareness and training
Investment using
mostly short-term
pay-back critera
1
Unwritten guidelines
Energy and environmental Informal contacts
management are part- between engineer and
time responsibility of
a few users
someone with only
limited influence
or authority
Cost reporting based
on invoice data.
Engineer compiles
reports for internal use
within technical
department
Informal contacts used
to promote energy
efficiency and resource
conservation
Only low-cost
measures taken
0
No explicit policy
No energy/env.
manager or formal
delegation of
responsibility for
env./energy use
No contact with users
Cleaner Production – Energy Efficiency Manual
No information system. No promotion of
energy efficiency and
No accounting for
resource conservation
materials and energy
consumption
and waste
No investment in
increasing
environmental/energy
efficiency in premises
page 17
Part 1 CP-EE methodology
Task 2
Chapter 2: CP-EE assessment methodology
Involving employees
Success of a CP-EE assessment depends heavily on staff involvement. It is
important to remember that successful CP-EE assessments are not carried out
by people external to the company, such as consultants, but by the staff of the
company itself supported, if and where necessary, by people from outside.
Staff in this context means everyone, from senior management to employees on
the shop-floor. In fact, shop-floor staff often have a better understanding of
processes and are able to suggest improvements. Other departments such as
purchasing, marketing, finance, and administration can also play an important role.
Staff members provide useful data, especially on process ‘inputs’ and ‘outputs’, and
assist with assessment of the economic and financial feasibility of CP-EE options.
Group meetings should be organized to involve them. Well managed meetings will
gain the goodwill and confidence of employees and also inform them about the
benefits of a CP-EE assessment. This rapport with employees will help to motivate
them and ensure their involvement in the studies. Completed Worksheet 2 shows
a checklist of various activities that can be undertaken to involve employees.
Task 3
Organizing a CP-EE Team
!
Setting up one or more CP-EE teams is an important aspect of the initiation,
coordination and supervision of the CP-EE studies. Teams should consist of company
staff supported and assisted where necessary by CP-EE professionals. Getting the
right mix of team members is crucial, otherwise teams may face hindrance from
within (e.g. from other company staff members) as well as from outside.
For large organizations, teams could comprise a core group ensuring a
favourable response to CP-EE options (made up of representatives of different
departments, especially finance/accounts and projects departments) and subgroups addressing specific tasks.
For small and medium size firms, a single team comprising the owner or proprietor
and supervisors or managers overseeing day-to-day operations may well be
sufficient. To be effective, the team should have enough collective knowledge to
analyse and review current production practices and energy systems and to
explore, develop and evaluate CP-EE measures. (See Completed Worksheet 3).
Cleaner Production – Energy Efficiency Manual
page 18
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Running Example: Task 2
LDPM employees were given formal training and were informed about CP-EE
Completed Worksheet 2
Section no.
1)
Yes ✓
Tasks
No ✗
CP-EE introduction
Workshop
• Middle manager
✓
• Shop floor workers
✓
• Utilities workers
✓
✗
• Administration staff
2)
Group meetings
✗
• Administration staff
• Various sections in the process house
✓
• Utilities staff
✓
✗
• Maintenance staff
✗
• Purchase department staff
✓
3)
Display of CP-EE posters
4)
Showing of short films on CP-EE success stories
✗
5)
Organizing of slogan campaign on environmental and energy themes
✗
Running Example: Task 3
A CP-EE Team was organized in consultation with the management
Completed Worksheet 3
Section no. Name
Designation
Department
Role
1)
Girish Luthra
Director
Overall
Team leader
2)
Bimal Kumar
Operation In-charge
Equipment and utilities
Team member
3)
Nikun Nanavati
Maintenance Engineer
Plant maintenance
Team member
4)
Dadaram Gohdsware
Dyeing In-charge
Dyeing section
Team member
5)
Rajiv Garg
External Consultant
Cleaner Production – Energy Efficiency Manual
–
Team member
page 19
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
CP-EE
Task 4
Compiling existing basic information
!
snapshot
In this task, the CP-EE team generates four important outputs:
General company information
This involves obtaining general details about the company including details of
key contact people, main products, turnover, employees, working hours and
production days in a year. (See Completed Worksheet 4a).
General production flow chart
A general production flow chart includes major energy conversion equipment
supplying utilities such as steam (boilers), compressed air (air compressors),
chilled water (refrigeration compressors), etc. (See Completed Worksheet 4b).
Data on consumption and cost of input raw materials, chemicals and energy
resources (electricity and fuels) must be collected and compiled, together with
data on consumption by utilities and details of production for both the entire
plant and for each process department. These data should be compiled in three
forms, namely: daily or batch average; monthly average (daily data over a
period of three to four representative months); and yearly average (twelvemonth data for preceding three years) (see Completed Worksheets 4c and 4d).
Information obtained
during the first meetings
with top management and
staff, prior to the
assessment, will allow the
team to analyse and review
the information and be
better prepared for the
‘conducting a walkthrough’
task. Such information
could be obtained, for
example, from an analysis
of electricity bills. It may
lead to recommendations,
before assessment, on
things like energy demand
rescheduling and power
factor penalties.
CP-EE
snapshot
Graphical representation of the data will help the team to analyse work
practices and trends within the facility and may also highlight unusual practices
that are worthy of investigation.
Details of technical specifications
Details of technical specifications for equipment used in the production process and
supply of process utilities must also be collected. (See Completed Worksheet 4e).
A status list of readily available information
A status list of readily available information about the plant should be made. This
will include process flow diagrams, plant layouts, inventory and dispatch data
sheets, raw material consumption and cost data, production data, production
log sheets, material balance, water balance and conservation details, energy
consumption details, emissions records, waste analysis records, waste
generation and disposal records, maintenance log sheets and other relevant
data. (See Completed Worksheet 4f).
Cleaner Production – Energy Efficiency Manual
A typical textile processing
unit in Thailand processes
cloth which can be
divided into two
categories: dyed cloth and
printed cloth. The cloth
that is printed is initially
dyed or whitened.
Total production from the
unit was normalized in
terms of the total cloth
processed, the resources
used during the
production forming the
basis for normalization.
Total (normalized)
production =
total cloth printed +
total cloth dyed.
page 20
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Running Example: Task 4
General information about the company was collected, presented in Completed Worksheets 4a to 4f
Completed Worksheet 4a
Section no.
1)
Name and address of company
Luthra Dyeing and Printing Mills, 252/2, Luthra Mill Compound, GIDC, Pandersara, India
2)
Contact person
• designation
• telephone/e-mail
Girish Luthra
Director
+91 261 28690606 8 / mail@luthraindia.com
4)
Employee strength
550
5)
No. of working hours per year
3 shifts/day, 300 days/yr
6)
No. of batches per year
Approximately 300–400 batches
Completed Worksheet 4b: General production flowchart
coal
grey cloth
coal yard
fines
crusher
house
water
chemicals
water
steam
chemicals
water
steam
fines
chemicals
waste gases
boiler
house
water
steam
blowdown
pre-treatment
wastewater
bleaching
and dyeing
wastewater
printing
wastewater
finishing
emissions
ETP
sludge
chemicals
steam
gas
steam
Utilities
• DG sets
• gas storage and handling
treated water
to drain + recycling
chemicals
product
Completed Worksheet 4c: Monthly variation
300
production
250
200
150
100
50
month
0
1
2
3
4
5
6
7
8
9
10
11
12
51
30
65
48
62
44
42
63
80
126
83
104
cloth printed (tons)
87
108
112
155
157
92
148
168
162
148
101
151
total dyed + printed (tons)
138
138
177
203
219
136
191
231
242
274
184
256
total cloth normalized (tons)
112
123
145
179
188
114
170
199
202
211
143
203
cloth dyed (tons)
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
… Running Example: Task 4 (continued)
Completed Worksheet 4d: Resource consumption
On average, the unit processes 8.0 tons of cloth per day. As is typical of textile processing units, the process requires steam, water,
gas, compressed air, dyes and printing chemicals, etc. Consumption of major resources per ton of cloth processed in the year 2002 is
tabulated below.
Resources
Months
Unit
1
2
3
4
5
6
7
8
9
10
11
12
Total average
Purchased water
m3/ton cloth
115
122
136
148
136
172
143
133
123
136
135
125
135
Total water
m3/ton cloth
201
208
222
234
222
258
229
219
209
222
221
211
221
Coal
t/ton cloth
4
4
3
3
4
4
4
4
4
3
3
Gas
m3/ton cloth
772
846
697
625
611
804
629
656
582
576
623
553
664
Grid electricity
kWh/ton cloth
698
663
345
1 587
234
294
225
234
208
1 469
1 641
1 356
746
Diesel
litre/ton cloth
247
256
363
0
608
417
421
366
361
0
0
0
253
Eqivalent
electricity
from diesel
kWh/ton cloth
827
858
1 216
0
2 037
1 395
1 410
1 227
1 209
0
0
0
848
Total kWh
electricity
kWh/ton cloth
1 525
1 521
1 561
1 587
2 272
1 690
1 636
1 461
1 417
1 469
1 641
1 356
1 595
Dyes
kgs/ton cloth
61
65.4
60.5
65.1
60.1
74.2
61
61.4
61.8
61.3
64
63.5
63.2
Gums
kWh/ton cloth
82
80
88
93
85
110
100
93
87
90
99
85
91
3
Completed Worksheet 4e: Existing utilities and energy-intensive equipment
Section no.
Name of utility
Capacity
Quantity
Specifications
Make
Type
Specific design parameters
6 t/hr
1
IBL
Smoke tube
6 t/hr, 10.98 kg/cm2,
at 75% eff.
-
2
-
Screw compressor
250 cfm at 6 kg/cm2
DG set
380 kVA
125 kVA
2
1
Kirloskar
Cummins
4)
Motors
>50 HP
50 – 10
<10
8
16
36
several
3-phase
5)
Fans
3 280 m3/hr
1
1
-
ID
FD
6)
Pumps
5 m3/hr
2
-
1)
Boiler
2)
Compressed air system
3)
Cleaner Production – Energy Efficiency Manual
3 280 m3 hr at 600 mm WC
4 kg/cm2 at 30°, 5 m3/hr
page 22
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
… Running Example: Task 4 (continued)
Completed Worksheet 4f: Information available within the unit
Section no.
1)
Information required
Available
Not available
Remarks
Layout
• Factory
_
• Steam and condensate distribution network
_
• Compressed air distribution network
_
2)
Production details
_
3)
Process flow diagram
_
4)
Material balance
_
5)
Energy balance
6)
Design specification of utilities
_
Partially
7)
Raw material consumption and cost
_
Partially
8)
Energy, water consumption and cost
_
Partially
9)
Waste generation and disposal records
_
10)
Waste treatment records
_
11)
Maintenance records
Task 5
Partially
_
Partially
_
Identifying barriers and solutions to the CP-EE
assessment process
In order to develop workable solutions, the CP-EE team must identify
impediments to the CP-EE process—for example difficulties in obtaining
information from certain departments. The team should highlight such
difficulties right away, so that corrective measures can be taken by
management to resolve the issue before the start of the CP-EE assessment itself.
Lack of measuring instruments and lack of provision for measurements could
also be a major barrier. Adequate steps must be taken to overcome such
barriers (e.g. purchasing or hiring of measuring equipment and making of
provision for measurement).
Lack of awareness of CP-EE on the part of staff and lack of relevant skills are
further possible barriers. These barriers are typically overcome by conducting
in-plant awareness-raising sessions, through training activities or through
provision and explanation of relevant case studies and similar measures. (See
Completed Worksheet 5).
Cleaner Production – Energy Efficiency Manual
page 23
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Running Example: Task 5
Completed Worksheet 5: Barriers and solutions
No.
1
Barrier
Yes ✓
No ✗
Enabling measures suggested
Yes ✓
Lack of awareness of energy and environmental issues
Emphasis on maximum production rather than
productivity
Complacent attitude towards existing
process/production conditions
✓
✓
Increase awareness
✓
Acknowledge workers’ efforts
Low participation of workers in CP-EE programme
Belief that ‘I am doing the best’
✓
✗
Involve workers in decision making
✗
Hesitant about risks involved
✓
✓
✓
✗
Formulate incentive schemes for workers
Encourage experimentation for CP-EE options
Review CP-EE measures on regular basis using
simple indicators
✓
✓
✗
Increase interaction among similar kinds of industries
2
Organizational barriers
One man show; middle (supervisory) level missing
Delegation of authority
Loose management structure
Production on ad-hoc basis
Induction of technically sound person
✓
Inadequate documentation of inventory and
production data
Right wage for the right person
✗
Labour intensive: workers employed on contract basis
3
Recruitment of permanent skilled workforce
✓
✓
Trade barriers
Production on job-order basis
Poor quality of input raw material
✓
✓
✗
Setting up of integrated plants
Ensuring good quality of raw materials from supplier
✗
Industry mainly catering to local markets
✓
✗
✗
Standardization of product
Promotion of marketing in the international market
4
Technical barriers
Lack of:
• proper guidance on CP-EE
• technically sound professionals
• skilled workers
• laboratory analysis facility
• adequate in-plant waste usage
opportunities
Training and awareness workshops on CP-EE
✓
✗
Provision of regular power supply through captive
power generation
Relevant technical literature not readily available
✓
Promotion of relevant technical literature through inhouse circulation
✓
Highly water-intensive process steps
✓
✓
Development of indigenous CP-EE measures
✓
✓
✓
✓
Soft loans
✓
Training of workforce for specific job and formulation of
long-term industrial policy
Technology developed abroad not applicable in
Indian conditions
✗
Encouraging waste exchange among industrial units
Economic barriers
Adequate funds not available
Low financial returns on certain CP-EE measures
Availability of cheap un-skilled labour, making
automation less attractive
Changing excise and tax liabilities
6
✓
Setting up of laboratory with basic facilities
Erratic power supply
5
No ✗
Attitude barriers
Planned investment
Incentive schemes for industries going in for CP-EE
✓
✓
✓
✓
Other barriers
Abundant supply of resources such as water, making
water conservation less financially attractive
Lack of available space
Lack of regulation on environmental and energy
management systems
Imposition of water levy on industries to restrict water
use and encouraging of modernization of existing plants
✗
✓
✓
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Chapter 2: CP-EE assessment methodology
CP-EE
Task 6
!
Deciding the focus of the CP-EE assessment
snapshot
Deciding the focus of the CP-EE involves making decisions in two areas:
• scope: deciding whether to include the entire plant or limit CP-EE to certain
units/departments/processes; and
• emphasis: deciding which materials and energy resources to include (e.g.
raw material, products, fuel, electricity, steam, compressed air and
refrigeration, etc.).
The focus of the CP-EE assessment can be decided by using a set of weighted
criteria applied to the different sections and allocating a score to those sections
of a plant or facility that could be the focus of assessment. An example is given
in Completed Worksheet 6. The weight given to any particular criterion
depends on many factors and will probably need to be adapted to suit the
nature of the particular industry, location, etc.
In the textile industry, the
garment section is often
overlooked, as it is not a
major consumer of
resources or generator of
wastes or emissions. In
the cement industry,
water is not given much
emphasis for CP-EE, as
the focus is on energy
and materials.
Focus areas need to be
fixed on the basis of
information on
departments, utilities
and/or sections, taking
account of barriers and
the solutions to
overcome them.
Running Example: Task 6
Different sections of the plant were analysed in accordance with the matrix and the boiler house was chosen as
an audit focus for detailed CP-EE assessment.
Completed Worksheet 6: Audit focus for detailed CP-EE assessment
Section no. Criteria
Weight
SECTION
Scores obtained
Boiler house
Dye house
Printing
Pre-treatment
1
Probability of pay-back for CP-EE options from section
10
7
4
5
5
2
Section/area consuming maximum resources
5
2
3
3
4
3
Multiplier effects
5
2
1
2
1
4
Increase in product quality/production rate
5
3
3
3
2
5
Barriers
5
3
1
3
2
6
Management preference
10
8
3
5
4
7
External pressure (govt. NGO, etc.)
10
8
4
6
5
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Part 1 CP-EE methodology
STEP 2
Chapter 2: CP-EE assessment methodology
Pre-assessment
Pre-assessment, Step 2 in the CP-EE assessment methodology, gives the CP-EE
practitioner an initial ‘hands on’ feel for the company’s operations. It consists of the
following four important tasks:
• Preparing process flow diagrams of CP-EE focus areas, using available information
and data
• Conducting a walkthrough
• Preparing material and energy input and output quantification and
characterization
• Generating and finalizing baseline data
Task 7
!
Preparing process flow diagrams
Preparing a process flow diagram (PFD) is an important step in the CP-EE
assessment. PFDs are prepared on the basis of discussions with plant personnel,
using readily available data, and for the audit focus areas only.
The best way for the CP-EE team to start is by listing the important process/unit
operations and the associated utility supply equipment/systems. At each
operation the team should list: (a) major input resources i.e. energy (electricity,
fuels, etc.), raw materials and chemicals, and utilities (water, steam, etc.); (b)
intermediate and final products; and (c) waste streams (wastewater, exhaust
air, exhaust gases, heat radiation emissions, solid wastes, etc.).
Figure 1.5: Process block diagram
Input resources
material resource 1
material resource 2
catalyst
energy resource 1
energy resource 2
material resource 1
energy resource 1
catalyst
material resource 2
energy resource 2
main raw material
PROCESS 1
or
UNIT OPERATION 1
PROCESS 2
or
UNIT OPERATION 2
Waste stream
gaseous waste
liquid waste
solid waste
energy waste
reusable waste
gaseous waste
liquid waste
solid waste
energy waste
product
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Next, each of the process/unit operations can be presented as a block diagram
showing relevant material and energy inputs, resources, intermediate products,
products, by-products, and output waste material and waste energy streams.
Operating process parameters (flow rates, pressures, temperatures,
water/moisture content, humidity, etc.) should also be indicated in so far as
possible. An example of a block diagram is given in Figure 1.5. The way in
which this is expanded into the PFD is illustrated by Completed Worksheet 7
and explained in the accompanying text.
Running Example: Task 7
Completed Worksheet 7: An example of a process flow diagram (PFD)
coal (lignite)
water spray
coal fines
(carpet loss)
fugitive emissions
coal yard
coal (lignite)
electricity
water
electricity
conditioning
chemical
manual screening
and crushing
standard parameters:
8 t/hr at 12 kg/cm2
steam generation boiler
Standard
Pr.
FD fan
ID fan
coal (lignite) 1.1 t/hr
BFW pump
rating
15 kW at
100 mmWC; 30°C
standard parameters:
20 kW at
250 mmWC; 200° C
flue gas
Operating
12 kg/cm2 10 kg/cm2
6 t/hr
6 t/hr
radiation loss
wet stream
steam separation
hot condensate (3%)
dry stream (97%)
electricity
9 kW (actual)
air
The process flow diagram (PFD) is constructed by connecting the block diagrams of individual unit operations.
Sometimes, the best way to create and refine a PFD is to conduct a number of walkthroughs. While preparing a
PFD, the team should keep the following points in mind:
• Use blocks to denote the operations. For each block, write the name of the operation and any special
continued over page …
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
… Running Example: Task 7 (continued)
•
•
•
•
operating conditions that need to be highlighted (e.g. for a dyeing operation, it may be pertinent to
indicate a temperature of 90° C and pressure of 12 kg/cm2).
All data should be based on the same time unit (e.g. annual, quarterly etc.).
Wherever required, supplement the process flow diagram with chemical equations to facilitate
understanding of the process.
The PFD may use symbols to add more information about the process. For instance, indicate clearly whether
the operations are batch or continuous. Also, solid and dotted lines can be used to show continuous or
intermittent release of emissions, respectively. Colour codes may also be useful (e.g. green lines to indicate
recycled streams and red lines to indicate release of wastes).
Wherever data is easily available, characterize the input and output streams.
Task 8
Conducting a walkthrough
A walkthrough is one of the most effective techniques for getting first-hand
information on production and processes. A walkthrough usually follows the
PFD. This task generates two important outputs for the CP-EE team:
• A record of obvious housekeeping lapses and observations, in the form of a
table (see Completed Worksheet 8) or Eco-map (explained below).
• Simple line diagrams of major utilities (see Completed Worksheet 8).
CP-EE
snapshot
The CP-EE team should
not conduct a
walkthrough when the
operations are closed (e.g.
at weekends, during low
production cycles, or
during night shifts).
Recording obvious housekeeping lapses
While conducting a walkthrough in the different sections of a plant, the CP-EE
team will record housekeeping lapses such as leaks of steam or water, leaks
from processes or of condensate, fuel oil leaks, compressed air leaks or any
obvious wastage going to the drain. These housekeeping lapses must be
recorded.
Notes should be taken relating to process operations, recording things like
specific duty conditions, problems faced by the operators and operators' views
on existing process conditions and parameters. Points picked up from the shop
floor often lead to potential energy and material saving measures.
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Running Example: Task 8
Completed Worksheet 8: Obvious housekeeping lapses
Section
no.
Name of section
Area
Obvious lapses
Categorization of lapse
Solid
1)
Coal handling
Coal storage
Carpet losses
Liquid
Gas
Fuel
✓
✓
Unsuitable water spray
2)
Crusher house
Manual crushing
Dusty atmosphere
✓
3)
Boiler house
Coal
Coal quantity use measurement
not provided
✓
Feed water
Water flow measurement
Boiler
Radiation loss high
Boiler
Manual fuel firing
✓
Boiler
Fuel firing door open regularly
✓
Boiler
Ash cleaning done manually
Boiler
High unburned coal in ash
Boiler
Cold air + water supplied to
boiler drum
Boiler
Major instrument absent
1) Steam temp.
2) Flue gas temp.
3) O2 in flue gas analyser
ETP
Others
✓
Spontaneous combustion
4)
Electrical
✓
✓
✓
✓
✓
✓
✓
✓
Boiler
Continuous blowdown without
any B/D WHR system
Boiler
No WHR from flue gases
Boiler
Frequent boiler steam load
fluctuation
✓
Boiler
No damper control of FD and ID
fan at any load
✓
Steam distribution
Steam pipe line flanges and
valves not insulated
✓
Steam distribution
Main steam line steam traps
blowing steam
✓
Steam distribution
Traps in process equipment not
working properly
✓
Steam distribution
Condensate from process
equipment traps being drained
✓
ETP
Average ETP inlet feed water
temp. high (45 °C)
✓
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Chapter 2: CP-EE assessment methodology
Preparing and collecting simple line diagrams
Simple line diagrams should be collected or prepared for the following:
•
•
•
•
•
Water supply and drainage networks
Electricity distribution
Refrigeration circuit
Steam and condensate distribution
Compressed air distribution system
These are simple single line diagrams depicting the supply and distribution
network of the above utilities. They may also contain helpful information on
operational parameters.
Eco-mapping
Eco-mapping is a simple and practical tool providing visual representation of
areas of concern as well as indicating instances of good practice.
Eco-maps can be developed for specific themes. They are made using the
layout maps of the site. Themes for which eco-maps can be made include:
•
•
•
•
•
Water consumption and wastewater discharge
Energy use
Solid waste generation
Odours, noise and dust
Safety and environmental risks
For each eco-map, the team must be sure to include everything related to the
particular problem being studied. For instance, an eco-map for water
consumption and wastewater discharge must pinpoint the location of
overflows, spills or excessive use of water, etc. These areas can be highlighted
using colour codes or distinct symbols to distinguish between areas that should
be monitored or areas where problems need to be dealt with as soon as
possible. Figure 1.6 shows a typical eco-map.
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Chapter 2: CP-EE assessment methodology
Figure 1.6: Eco-map for water in the printing section of a textile factory
energy
solid waste
water
bad practice
processed ETP
finished
products storage
no
drains
drains
raw material
storage solutions,
metal
high water
consumption
dyeing
drain piping
printing
spillage
MC panel
office
bad practice
Dos and don’ts for housekeeping lapse identification
• Don’t find faults—this is not a fault-finding mission. The purpose is to better understand material and
energy flows and to generate ideas for efficiency gains, higher profitability and overall environmental
improvement. It is also to ‘make friends’ for future contacts and possible partnerships. So, don’t be critical—
be constructive and make suggestions.
• Don’t dominate the conversation. Give the responsible staff the opportunity to speak and explain—be a
good listener.
• Don’t ask questions to show your knowledge about the process and don’t digress by sharing information
that you have but that is not relevant.
• Ask questions only when you must but, if you don’t understand explanations and feel that they are critical,
do ask for further explanation. Don’t be shy about admitting what you don’t understand.
• Don’t leave the group—it can appear impolite.
• Do ensure that you meet timelines agreed earlier.
• Do always keep track of the outputs you are expected to produce. Observations should be made to allow
for corrective action and notes should be taken to allow for computation of preliminary material balances. It
is also important to obtain information on individual operations and key /major operational sequences.
• Do take along a camera—photographs can be very helpful. Don’t forget that, if outsiders are involved in the
team, it is essential to get permission from the management to use the camera.
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Part 1 CP-EE methodology
Task 9
Chapter 2: CP-EE assessment methodology
!
Preparing material and energy input-output
quantification and characterization
Each input and output (including wastes)—whether resources, materials or
energy—must be quantified, characterized and noted on the PFD prepared in
Task 7.
Measurements or estimates of quantities will have to be made in the field when
relevant data are not readily available.
Data on other parameters necessary to characterize these streams must also be
compiled. Involving operating staff in data collection and verification is
strongly recommended.
Material and energy inputs and outputs will often not balance as many of the
loss streams—especially energy streams—have not yet been identified and
quantified. This will require further field visits and measurements.
Running Example: Task 9
Completed Worksheet 9: Input-output quantification and characterization
Process
Inputs
steps or unit
operations
Water
Characteristics
Quantity
Temperature
Pressure
Total
solids
12 kg/cm2 85.24 kg
106.56 m3/d
30 oC
Air
302.6 t/d
30 oC
–
Coal
26.4 t/d
–
–
Output Quantity
Others
Characteristics
Temperature
Pressure
Total
solids
Others
_
Blow down
losses
10.56 m3
179 oC
10 kg/ cm2
61.3 kg
_
–
_
Flue gas
329 t/d
200 oC
–
–
O2 =
8.5%
–
GCV =
15 459.8 kJ/kg
Ash
1.67 t/d
–
–
–
_
Unburnt
1.28 t/d
–
–
–
_
Boiler
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Part 1 CP-EE methodology
Task 10
Chapter 2: CP-EE assessment methodology
!
Generating and finalizing baseline data
Baseline information comprises historical consumption and cost data for all
input material and energy resources and output products (see Completed
Worksheet 10). The CP-EE team will need to collect all this information using
different time frames, i.e.:
• Annual: monthly average data for each year over the past three years.
• Monthly: daily average data for 30 days for three representative seasonal
months of the year.
• Daily: average batch data or hourly average data for a day.
The types of information to be gathered are:
• Material and energy resource inputs, consumption and cost (electricity use, energy
charges, peak demand charges, electricity unit cost, penalties and other costs).
• Products, actual production, capacity utilization.
• Energy conversion equipment, specifications and actual average parameters
for each piece of equipment.
Running Example: Task 10
Completed Worksheet 10: Baseline data
Section/
utility
equipment
Boiler House
Resource used/
parameters
Quantity
Specific
consumption/
ton of cloth
Savings
potential
Targets
Coal
26.712 t
3.33 t
High
2.0 tons/ton of cloth
Water
108.86 m3
13.6 m3
High
6.0 m3/ton of cloth
600 kWh
75 kWh
Medium
65 kWh/ton of cloth
Electricity
Cloth production
8 t/d
Steam
96 t
12 t
Evaporation ratio of boiler—3.63 ton of steam/ton of coal
High
Boiler efficiency = 65 %
High
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Performance indicators need to be developed based on this information. For
example for:
• Specific material consumption for each material input, or at least for
important input materials (tons of input material/ton of product).
• Specific energy consumption for electricity and fuels (kWh per ton of product,
kg or litre of fuel per ton of product).
• Specific energy utility consumption (TR/ton product, steam/ton product).
• Equipment-related energy performance indicators (ton steam/ton coal,
kW/cfm of fan air).
• Production cost (per ton of product).
• Electricity, fuel, water, chemicals, transport, manpower as a percentage of
production cost.
These performance indicators need to be compared with targets or
benchmarks to assess improvement potential. These targets could be based on:
own best performance norms; local/national/regional/international industry best
performance norms
STEP 3
Assessment
Assessment comprises four critical tasks constituting the CP-EE assessment process.
Much of the entire CP-EE process depends on these four tasks:
•
•
•
•
Preparing a detailed material and energy balance including losses
Cause diagnosis
Generating options
Screening options
Task 11
Preparing a detailed material and energy
balance including losses
!
The physical laws of conservation of energy and mass tell us that, in any
process/unit operation in a steady state, the sum of all of the inputs must
equal the sum of all of the outputs (including losses and wastes). When
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
making a material and energy (M&E) balance an essential objective is
therefore to check that ‘what goes in, comes out’. All inputs, whether
material or energy, should have related outputs.
Input and output streams were quantified and characterized in Task 10, when
a balance was drawn up of material and energy inputs and outputs.
Only one or two of the output streams will constitute ‘useful’ output. It is the
proportion of input that can be traced through to useful output that reflects the
efficiency of the process. There are non-useful output streams in addition to the
useful output.
Unlike material streams, energy streams are characterized by a single useful output
stream, all of the others constituting ‘loss’ streams which need to be minimized.
Figure 1.7: Typical components of a material and energy balance
gaseous emissions
water/air
PROCESS
power
or
catalyst
UNIT OPERATION
reusable waste in
another operation
product
wastewater
liquid wastes for storage and/or disposal
solid wastes for storage and/or disposal
As explained earlier, in energy streams, both the ‘useful’ and the ‘loss’ output
streams are quite often invisible or, at least, not easily detectable. Methods
other than direct measurement have to be employed to evaluate and quantify
energy content in these streams. The typical components of a material and
energy balance are shown in Figure 1.7. Completed Worksheets 11a, 11b and
11c give empirical examples.
M&E balances are normally prepared using proxy data supported by information
recorded during the walkthrough. For instance, monthly or annual water and
energy bills give an idea of consumption levels. On the output side, production
figures or orders filled (monthly or annual) can provide an estimate of average
production. Obtaining figures on wastes and emissions is generally more difficult.
Sometimes, concentration data for water pollutants and air pollutants exist and
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Chapter 2: CP-EE assessment methodology
Running Example: Task 11
Completed Worksheet 11a: Boiler material balance
1.113 t/hr (actual)
water spray (50 l/hr)
coal fines (carpet loss)
coal yard
1.102 t/hr
fugitive emissions
losses:
0.011 t/hr
coal (lignite)
manual screening
and crushing
water: 4.44 t/hr
electricity
coal (lignite)
rejects:
0.002 t/hr
electricity
conditioning
chemical
coal (lignite) 1.1 t/hr
ID fan
4.44 t/h
BFW pump
standard parameters:
8 t/hr at 12 kg/cm2
PROCESS STEP REFERENCE
process
step
steam generation boiler
Standard
FD fan
standard parameters:
100 mmWC;
30°C & 15 kW
standard parameters:
250 mmWC;
head developed
200° C & 20 kW
hot flue gases
Operating
2
process pressure 12 kg/cm
parameter
10 kg/cm2
rating
6 t/hr
6 t/hr
blow down loss: 0.44 t/hr
unburnts: 0.05333 t/hr
ash: 0.0695 t/hr
4 t/hr (actual)
wet stream
electricity
air: 12.61 t/hr (actual)
6 t/hr (standard)
steam separation
hot condensate (3%)
0.12 t/hr (actual)
dry steam (97%)
3.88 t/hr (actual)
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… Running Example: Task 11 (continued)
Completed Worksheet 11b: Boiler energy balance
coal (lignite)
water spray
coal fines (carpet loss)
coal yard
fugitive emissions
coal (lignite)
electricity
electricity
manual screening
and crushing
water
conditioning
chemical
17.0 MkJ/hr (actual)
coal (lignite) 1.1 t/hr (actual)
ID fan
BFW pump
0.5 MkJ/hr
(actual)
standard parameters:
8 t/hr at 13 kg/cm2
PROCESS STEP REFERENCE
process
step
steam generation
Standard
FD fan
standard parameters:
100 mmWC;
30°C & 15 kW at
electricity
9 kW (actual)
air:
12.61 t/hr (actual)
14.34 t/hr (standard)
flue gases
loss: 13.2% (actual)
2.25 MkJ/hr (actual)
Operating
2
process pressure 12 kg/cm
parameter
10 kg/cm2
rating
4 t/hr
equipment
standard parameters:
250 mmWC
head developed
200° C & 20 kW
6 t/hr
blow down loss: 1.4%
0.24 MkJ/hr (actual)
unburnt in ash: 4.85%
0.83 MkJ/hr (actual)
boiler
11.40 MkJ/hr (actual)
wet stream
Hidden losses:
steam separation
hot condensate (3%)
0.09 MkJ/hr (actual)
• H2 & moisture:
2.5 MkJ/hour (actual) 14.4%
• Radiation:
0.17 MkJ/hr (actual) 1%
• Moisture in air:
0.03 MkJ/hr (actual) 0.15%
dry steam (97%)
11.31 MkJ/hr (actual)
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* The unit rate is fixed at
… Running Example: Task 11 (continued)
Completed Worksheet 11c: Cost of waste stream
Section no.
Section/
process
Waste
stream
* Equivalent
coal quantity
(t/day)
* Total cost
of waste
component
1)
Coal yard
Coal
Coal
0.264
418.97
2)
Manual
crushing
Reject
Stones
0.048
76.176
3)
Boiler
Thermal
Flue gas
3.492
5 541.804
Blow down
0.373
551.95
Unburnt
1.288
2 044.05
H2 and
moisture
3.881
6 159.15
Radiation
0.264
418.97
Moisture in air
0.46
73.00
Components
of
waste stream
US$35 per tonne. The total
cost of the waste component is
the product of the unit rate and
the equivalent coal quantity.
these can be used to estimate (back calculate) mass emissions. Data on mass or
volumes of solid waste are also sometimes available. Often, approximate
calculations will need to be used, based on ‘typical’ values available locally.
The following guidelines will help:
• For extensive and complex production systems, it is better to start by
drawing up the M&E balance for the whole system.
• When dividing up a system, choose the simplest sub-systems. Division could
be along the lines of the material and energy flow. The PFD should come in
handy here.
• Choose the material and energy flows envelope in such a way that the
number of streams entering and leaving the process is the smallest possible.
• Always choose recycle streams within the envelope to start with.
• When determining the time factor, always choose a minimum but
representative time span.
• For batch production, consider one full batch. It is important to include start
up and cleaning operations.
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Energy balances are usually more difficult to make because energy waste is
relatively difficult to identify and quantify. Alternative options for drawing up
energy balances are:
• System efficiency based on measurable output work and input energy.
• Measurement of major losses only.
• Single parameter measurement and benchmark comparison.
The CP-EE team will very probably find substantial discrepancies in the M&E
balance. This may require further discussion of the assumptions behind the data,
making of more measurements and revision of the input and output data, as
necessary. The next task for the team is therefore to prepare detailed M&E balances
for certain parts of the PFD. However, developing a detailed material balance for
every operation is neither practical nor relevant. Instead, critical operations are
usually chosen, based on the focus of the CP-EE study and results of the M&E
balance arrived at in the earlier steps, and on the types of materials and processes
used and energy use intensity. This means selecting operations where hazardous
materials are used or where material and energy losses are obvious. Detailed M&E
balances are often made when processes have long operational sequences.
Note:
A material balance
normally requires a tie
compound*, which forms
the basis for measuring the
efficiency of the processes.
The selection of the tie
compound is a function of
several possible
parameters; it could be:
• A parameter which is
easy to measure/record
• An expensive resource
• A toxic or hazardous
compound
• A resource common to
most of the processes
(* E.g. nickel or zinc in
electroplating shops
or chromium in
leather tanning.)
To conclude the M&E balance, it can be extremely useful to assign costs to the
material and energy loss streams (the waste streams) identified in the balance.
Experience has shown that this is the type of information that can have the
greatest weight in convincing company management of the value of CP-EE and
in securing management commitment to the subsequent steps. When assigning
monetary values to materials and energy waste streams, the CP-EE team should
consider the following:
• The cost of raw materials, input energy, intermediate products, and final
products lost in waste streams (e.g. the costs of unexhausted dye in waste
dye liquor or unburned fuel in exhaust gases).
• The cost of energy in waste streams, in terms of heat content exhausted.
• The cost of treatment, handling and disposal of waste material streams
including tipping or discharge fees, if any.
• Costs, if any, incurred in protecting workers and maintaining safe working
conditions (e.g. exhaust system venting shop floor air).
• The potential liability costs of an accidental spill or discharge or penalties
and fines for leakages.
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Costs should be determined for at least each major waste stream and energy
source. Specific costs (i.e. cost per kWh, per unit mass/volume of a waste
material or energy stream) should also be determined, in order to be able to
calculate the savings that would be made by reducing or avoiding waste
streams. Obviously, the high-cost waste streams are the most interesting to
focus on from the economic point of view.
A detailed M&E balance provides the team with information to identify causes
of waste generation or low productivity. Cause diagnosis is dealt with in the
next sub-section.
Task 12
Cause diagnosis
!
Remember!
Don’t get ‘bogged
down’ in trying to
make a perfect M&E
balance. Do the best
you can. You’ll soon
see that even a
preliminary M&E
balance can open
opportunities for
material and energy
savings which can be
profitably exploited.
Having identified, quantified and characterized various streams, and having
drawn up an M&E balance, the CP-EE team must now carry out cause diagnosis
to find out why waste is being generated. The cause diagnosis exercise involves
asking the question: ‘Why did such a problem or outcome occur?’ Essentially,
cause diagnosis is an exercise in finding the root causes of a problem.
The fishbone diagram (see Figure 1.8) is an excellent tool for cause diagnosis
in complex situations where a number of factors are involved. Once the
diagram has been prepared, the team can use it to help generate CP-EE
options. Below, we present an example from the textile dyeing process to
illustrate the technique used to prepare a fishbone diagram.
To construct the diagram in Figure 1.8, we took the example of a winch used in
the dyeing process. The winch is an open-top machine with a drum around
which a ‘rope’ of fabric is wound, pulling the fabric through a dye liquor over a
fixed period. It is one of the cheapest pieces of equipment used in dyeing and
is therefore used extensively by SMEs.
The first step is to define the principal problem to be diagnosed, and to write
it next to the ‘head’ of the fish (right-hand side). Our example has identified
low ‘Right First Time’ (RFT), a common problem encountered in textile dyeing:
the shade of the dyed fabric does not match the shade specified by the client.
This causes excessive product reject, lowering productivity and generating
waste (improperly dyed cloth).
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
The next step is to identify the primary causes of the problem. Once identified,
these are placed in generic categories: ‘Man’, ‘Method’, ‘Material’ and
‘Energy/Energy Eqpt.’ For instance, primary causes of the low RFT problem
could be:
a)
b)
c)
d)
Lack of supervision (category = Man).
Dyeing operation not properly carried out (category = Method).
Poor quality of input materials (category = Material).
Optimum temperature of dye bath liquor not maintained (category = Energy).
As can be seen from our specimen diagram, these primary causes are listed on
the ‘primary fish bones’. Primary causes can then be further broken down into
one or more secondary causes. For example, pursuing point b) above, the
dyeing operation may not have been properly carried out due to:
• excessive use of salt in the dyeing operation; or
• incorrect procedure followed while dosing the chemicals.
Figure 1.8: Fishbone diagram to facilitate cause diagnosis in the dyeing process
MAN
METHOD
dyeing operation not
carried out properly
lack of supervision
absence of clear
work instructions
incorrect procedure followed
while dosing chemicals
excessive use of
salt in dosing
lack of training
Right First Time (RFT)
in dyeing is low
poor contact between
fabric and dye liquor
poor water quality
high impurities
in dyes
dyeing input materials
of poor quality
shelf life of auxiliaries
exceeded
improper storage
of fabric
poor process control
resulting in inconsistent
performance
MATERIAL
Cleaner Production – Energy Efficiency Manual
optimum temperature
not maintained in dye
bath liquor
ENERGY/ENERGY EQUIPMENT
Primary causes in bold type
Secondary causes in normal type
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Similarly, for point c), the poor quality of input materials may be the result of:
•
•
•
•
impurities in the dyes used for the dyeing operation;
auxiliaries for the dyeing operation having exceeded their shelf-life;
improper storage of fabric used in the dyeing operation; or
poor quality of water used in the dyeing operation.
These secondary causes are listed on the ‘secondary fish bones’. Certain causes
appear several times in the diagnosis of primary (or perhaps even secondary)
causes. Common examples of this include ‘poor water quality used in the
dyeing operation’ and ‘lack of clear and concise work instructions’. This makes
it possible to identify common causes which, when corrected, could resolve
several productivity- and environment-related problems. Options that allow
correction of common causes naturally become priority options when drawing
up the implementation plan.
It is possible to pursue this logic (i.e. to continue to ask ‘Why?’)—secondary
causes may break down further into tertiary causes.
The causes identified in the fishbone diagram are only ‘probable’ causes and
the next step is to ascertain the extent to which each of them contributes to
the principal problem. In our example, the CP-EE team has to analyse the
extent to which each probable cause contributes to the unsatisfactory dyeing
operation. This analysis can be carried out on the basis of observations, record
keeping, and by setting up well-planned, controlled experiments to isolate a
specific secondary cause. These efforts will assist the team in validating the
primary and secondary causes and in prioritizing cause elimination.
Tools such as Pareto analysis may also be used if several primary and secondary
causes are to be analysed. Pareto analysis separates the most important causes
of a problem from trivial ones, and thereby indicates the most important
problems on which the team should concentrate.
Completed Worksheet 12 presents cause diagnosis in table form.
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Running Example: Task 12
Completed Worksheet 12: Cause analysis
Section no.
Section
Waste stream
Probable cause
1)
Coal yard
Loss of coal
Unsuitable storage area
Manual handling of coal
Excessive air circulation
Spontaneous combustion of coal
Soil is soft
2)
Screening and crushing
Stones as rejects
Poor quality of incoming lignite (coal)
with extraneous material
3)
ID and FD fan motors
Electrical energy loss
Varying load on motors but power draw is
nearly same
Oversize motors
4)
Flue gases
Air-fuel ratio is not maintained
No monitoring of relevant parameters
(O2 or CO2)
No device/method for heat recovery
Air ingress at various points
Air quantity and pressure is not sufficient
Distribution of primary air through grate
5)
Unburnts in ash
Sizing of coal not correct
Design of grate not appropriate
Boiler
Firing rate is not uniform
Manual ash removal
Poor fuel quality and
incorrect combustion
6)
Blow down
Bad boiler feed water quality
Condensate not recovered
Boiler drum TDS is not maintained as
required
7)
Radiation loss
Un-insulated portions of boiler
Openings
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Task 13
Chapter 2: CP-EE assessment methodology
!
Generating options
Generating options is a creative process. Like cause diagnosis, it is best
performed by the team in collaboration with other associated members of staff.
Involving colleagues in this activity will help them to develop a sense of
ownership of the options generated and to gain insight into why a particular
option is recommended for implementation.
Options are generated by brainstorming, a commonly used tool for generating
ideas. Faced with a particular problem, the team and relevant company staff
have to think their way through to a solution—they have to ask the question
‘How?’, i.e. ‘How do we solve this problem effectively?’. The cause diagnosis
described above (where we asked ‘Why?’) will provide a starting framework for
the brainstorming exercise.
In a typical brainstorming session, one person will propose an idea which
may be supported and/or expanded on by others. Further discussion then
yields new, transformed, opposing and/or supporting ideas, paving the way
for the generation of CP-EE options. This process is illustrated in Figure 1.9.
Examples of options generated are shown in Completed Worksheet 13 of the
Running Example.
Figure 1.9: Generating options through brainstorming
opposing
idea 1
idea 1
idea 4
supporting
idea 1
extension
to idea 1
idea 2
idea 3
based on
1 and 2
supporting
idea 3
supporting
idea 3
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
CP-EE
CP-EE options may fall into one of the following categories:
snapshot
• Housekeeping: improvements to work practices and methods, proper
maintenance of equipment, etc., come into this category. Good
housekeeping can provide significant benefits in terms of resource savings.
These options are typically low cost and provide low to moderate benefits.
• Management and personnel practices: management and personnel
practices include effective supervision, employee training, enhancing
operator skills, and the provision of incentives and bonuses to encourage
employees to strive conscientiously to reduce material and energy wastes
and emissions. These options are typically low cost; they can provide
moderate to high benefits.
• Process optimization: process optimization involves rationalization of the
process sequences, combining or modifying process operations to save on
material and energy resources and time, and improving process efficiency.
For instance, some washing operations may be made unnecessary by
changes in raw materials or product specifications.
• New technology: new technologies are often more resource efficient and
help in reducing energy and material wastes, as well as increasing
throughput or productivity. These options are often capital intensive but
can lead to potentially high benefits. Modifications in equipment design
may be another option. They tend to be less capital intensive and can lead
to potentially high benefits.
• Raw material substitution: there may be better options for primary and
auxiliary raw materials in terms of cost, process efficiency or reduced health
and safety related hazards, and these options can be substituted for the
current materials. Substitution may be necessary if materials become difficult
to source or become expensive, or if they come under new environmental or
health and safety regulations. Whenever materials are substituted, it is crucial
to test the appropriateness of the new material in terms of environmental and
economic benefits, optimum concentration, product quality, productivity,
and improved working conditions. An example of raw material substitution is
the replacement of chemical dyes with natural ones. Where energy is
concerned, it may be useful to evaluate the use of cleaner/renewable sources.
Use of renewable or non conventional energy sources is beneficial because it
has the global benefit of reducing greenhouse gas (GHG) emissions.
• New product design: changing product design can have impacts on both
the ‘upstream’ and ‘downstream’ sides of the product life-cycle. For
Cleaner Production – Energy Efficiency Manual
A simple example of good
housekeeping in a dyeing
operation is to clean the
floors and machines of
dirt, grease, rust, etc.
regularly. This will reduce
the possibility of
accidentally soiling the
fabric, and thus minimize
the need for extra
washing.
CP-EE
snapshot
In the case of a textile
dyeing unit, instead of
draining off the last cold
washes, they can be
collected in an
underground tank,
adjusted for pH, and then
filtered prior to reuse in
subsequent washing
operations. These options
are typically low to
medium cost and can
provide moderate to high
benefits.
page 45
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
CP-EE
example, re-designing a product may reduce the quantity or toxicity of
materials in the product; reduce the use of energy, water and other
materials consumed during the product's use; reduce packaging
requirements; or increase the ‘recyclability’ of used components. Benefits of
this can include reduced consumption of natural resources, increased
productivity, and reduced environmental risks. Product re-design can also
help to establish new markets or expand existing ones. It is, however, a
major business strategy decision, and may require feasibility studies and
market surveys, especially if the supply-chain for the product is already
established and is complex.
• Recovery of useful by-products, materials and energy: this category of CPEE option entails recovery of wastes (in the form of by-products from the
process or from resources) which may have useful applications within the
industry itself or outside of it. As the wastes or by-products are produced
anyway, this type of option can generate additional revenue with little or no
extra effort.
• On-site recycling and reuse: on-site recycling and reuse involves returning
of waste energy or material to the original process or using these as inputs
to another process. It should, however, be borne in mind that it is better not
to generate waste in the first place, rather than to generate it and then
recycle, recover or reuse it. The team should therefore only consider the
latter type of options once all options that could prevent generation of
waste have been examined. It is also important to remember that some of
the chosen options may require major changes in the processes or
equipment or product. While these may well dramatically reduce waste
generation or increase productivity, they also often imply considerable
investment.
snapshot
A textile-processing unit in
Thailand used sodium
sulphide and acidified
dichromate as auxiliary
agents in the sulphur
black, textile dyeing
process. However, both of
these agents are toxic and
hazardous to handle and
their use leaves harmful
residues in the finished
fabric and generates
effluents that are difficult
to treat and damaging to
the environment.
CP-EE studies conducted at
the unit indicated that
both of these agents could
safely be replaced with no
loss of fabric quality, thus
eliminating adverse health
and environmental
impacts. Glucose or
dextrose can be substituted
for sodium sulphide and
acidified dichromate can
be replaced by sodium
perborate or ammonium
persulphate.
CP-EE
Finally, it is important to bear in mind that certain options may require
laboratory, bench-scale or pilot studies to ensure that product quality is not lost
as a result of their application, and that they are acceptable to the market.
We round off this section by combining our example of cause diagnosis using
the fishbone diagram with the identification of possible options for cleaner
production. This is presented in Table 1.1.
Cleaner Production – Energy Efficiency Manual
snapshot
A common example of
recovery from a waste
stream for many industries
is heat recovery through
the use of heat
exchangers. Such options
are typically medium cost
and can provide moderate
to high benefits.
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Running Example: Task 13
Completed Worksheet 13: CP-EE options
Section
Waste
stream
Coal yard
Loss of coal
Option
ref. no.
CP-EE Options
GHK
OP
PO
RMS
NT
1
Store the coal on a concrete/brick lined
level floor
✓
2
Optimize the stack height and width of coal
heaps
✓
3
Use FIFO basis for coal usage
4
Construction of shed for coal storage
5
Optimize the use of water by installing
efficient showers/sprinklers/spray/nozzles
6
Procure better quality coal from different
sources
7
Install mechanical coal crusher
✓
NPD
ORR
✓
✓
✓
✓
ID and FD
fan motors
Electrical
energy loss
8
Installation of variable speed drives in ID and
FD fan motors
✓
Boiler
Heat loss due
to flue gas
9
Installation of damper to control air flow
✓
10
Install on-line O2 measuring sensor
✓
11
Install economizer for recovery of waste heat
✓
12
Install air heater for recovery of waste heat
✓
13
Plug all the air leakages into boiler furnace
14
Conversion of existing boiler to FBC boiler
15
Replace existing boiler with FBC Boiler
16
Optimize coal sizing by proper crushing and
sieving
✓
17
Modify existing grate by reducing gaps
between rods
✓
18
Optimize the firing rate by use of stoker
firing
✓
19
Install water treatment system (RO) plant
20
Change the water used in the boiler from
tanker water to municipal supply water
21
Install conductivity meter to check boiler
drum water quality and therefore optimize
blow down rate
22
Recover flash steam from boiler blow down
✓
23
Re-circulate condensate from steam
separator wherever possible
✓
Radiation loss
24
Insulate all the bare and damaged portions
✓
Radiation loss
25
Insulate flanges (125 flanges)
✓
26
Installation of steam traps (thermodynamic
traps) of rated capacity to be provided in
the steam main pipe within a gap of 25 m
Heat loss due
to flue gas
Unburnt in ash
Blow down loss
Steam
distribution
✓
✓
✓
✓
✓
✓
GHK: Good House Keeping
OP: Operational Practices
PO: Process Optimization
NT: New Technology
NPD: New Product Design
ORR: On-site Recycle & Reuse
Cleaner Production – Energy Efficiency Manual
EM
✓
RMS: Raw Material Substitution
EM: Equipment Modification
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Table 1.1: Matching the problems diagnosed using the fishbone diagram with possible CP–EE options
Categories Primary causes
Secondary causes
Possible CP-EE options
Category of CP-EE option
Man
Absence of clear work
instructions
Develop work instructions as Standard Operating
Practices (SOPs). Have the SOPs reviewed by external
experts. Closely monitor improvements or identify
problems faced, if any, in the implementation of the
SOPs. Build a record keeping system to monitor SOP
related compliance.
Management and personnel
practices
Lack of training
Organize shop floor based training programmes for
workers and supervisors.
Management and personnel
practices
Excessive use of salt in
dosing
Improve worker instruction and supervision.
Redesign the dyeing recipe by changing
composition and materials e.g. use of low salt dyes.
Management and personnel
practices, process optimization,
raw material substitution
Incorrect procedure
while dosing chemicals
Improve worker instruction and supervision.
Management and personnel
practices
High impurities
in dyes
Have the dye purity checked by independent
institutions over a number of samples and across
commonly used shades; change the supplier if
necessary.
Raw material substitution
Shelf-life of auxiliaries
exceeded
Improve the inspection at the receiving unit. Check
the container labelling, storage and supply systems.
Management and personnel
practices
Improper storage
of fabric
Ensure proper storage of scoured/bleached materials
e.g. on wooden blocks, wrapping to avoid soiling
Management and personnel
practices, housekeeping
Poor water quality
Analyse the water for hardness, total dissolved
solids, pH and iron/manganese content, etc. and
compare the measured levels with recommended
standards. Treat water to ensure that the
parameters are within the recommended standards.
Raw material substitution
Optimum
temperature not
maintained in the dye
bath liquor
Check the steam inlet position and steam pressure
to ensure that heating is optimum. Take readings of
temperature of the liquor before and after requisite
modifications.
Process optimization, new
technology
Poor contact between
fabric and dye liquor
Explore changing from a winch to a jet dyeing
machine that is enclosed, operates under pressure
and gives better contact between fabric and dye
liquor.
New equipment
Method
Material
Lack of
supervision
Dyeing
operation not
carried out
properly
Input materials
are of poor
quality
Energy
Poor process
and energy control
equipment resulting in
inconsistent
performance
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Task 14
Chapter 2: CP-EE assessment methodology
Screening options
Preliminary screening of options
Once brainstorming has helped to identify CP-EE options, preliminary and
rapid screening should be carried out to decide on implementation priorities.
This screening exercise will place options in two categories:
• Options that can be implemented directly
Simple and obvious options can be implemented straightaway. In general,
housekeeping (e.g. plugging leaks and avoiding spills) or simple process
optimization (e.g. control of excess air in combustion systems) options fall into
this category. No further detailed feasibility analysis is required for these
options. Moreover, their immediate implementation results in real and tangible
benefits in a short period, increasing management’s confidence in the CP-EE
assessment process.
• Options requiring further analysis
Some options are technically and/or economically more complex and a
decision to implement them would require examination of their technoeconomic and environmental feasibility. Most management improvement, raw
material substitution, and equipment or technology change options fall into
this category.
Decision on options that require much more information collection or are
difficult to implement (e.g. for reasons of very high costs or lack of technology)
can be considered at a later time. Completed Worksheet 14 on the following
page shows how this works in practice.
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Running Example: Task 14
Completed Worksheet 14: Screeening of CP-EE options
CP-EE option
ref. no.
Directly
implementable
Require further
analysis
Pending later
consideration
✓
1
2
✓
3
✓
✓
4
✓
5
6
✓
7
✓
8
✓
9
✓
10
✓
11
✓
12
✓
13
✓
✓
14
✓
15
16
✓
✓
17
✓
18
✓
19
✓
20
21
✓
✓
22
✓
23
24
✓
25
✓
26
✓
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
STEP 4
Chapter 2: CP-EE assessment methodology
Feasibility analysis
• Technical, economic and environmental evaluation
• Selecting feasible options
Task 15
Technical, economic and environmental evaluation
Detailed screening of options
The team can now undertake detailed screening of those options that require
further analysis, to determine which options are technically feasible and
ascertain both the economic and environmental benefits of their
implementation. These aspects are described below.
Technical evaluation
Technical evaluation should cover the following aspects (see also Completed
Worksheet 15a):
• Consumption of materials and energy: it is important to establish M&E
balances for each option before and after implementation conditions, in
order to quantify the materials and energy savings that would result.
• Product/by-product quality: quality of the product should be assessed before
and after implementation of the option.
• Right First Time (RFT): estimate must be made of the possible improvement
in RFT that would result from implementation of the option.
It is important to examine the following aspects when considering implementation:
• Human resources required: a decision must be made as to whether the option
can be implemented by in-house staff or whether external expertise or
collaboration with partner organization is required.
• Risks in implementing the option: some options may not be fully proven and
may require laboratory-scale experiments or pilot studies to assess their
outcomes before full-scale implementation. When options affect key
production processes or product features, the potential impact on business
if they do not work as planned can be very high.
• Ease of implementation: the ease with which an option can be implemented
will depend on such things as the layout of the production processes and of
the auxiliary services (e.g. steam lines, water lines, inert gas lines, etc.); the
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
physical space available; the maintenance requirements; training
requirements; etc. In addition, when options require work on key production
processes, the timing of their implementation becomes critical. If major
changes or interruptions to production patterns are required, any loss in
production needs to be factored into the economic analysis of the option.
• Time required for implementation: the time which implementation of an
option may require for procurement, installation or commissioning of
equipment or material must be considered. This must include consideration
of any shut-down time necessary for implementation.
• Cross-linkages with other options: a particular option may be linked to
implementation of other options; the decision must be made as to whether
it should be implemented on its own or with other options.
Environmental evaluation
Whenever practically possible, the environmental evaluation of an option
should take account of its impacts throughout the entire life cycle of a product
or service. In practice, however, evaluation is often restricted to on-site and offsite (neighbourhood) environmental improvements.
The environmental evaluation should include estimates of the following
benefits that each option may bring about (where relevant):
• Likely reduction in the quantity of waste or emissions generated (expressed
as mass).
• Likely reduction in GHG emissions.
• Likely reduction in the release of hazardous, toxic, or non-biodegradable
wastes or emissions (expressed as mass).
• Likely reduction in consumption of non-renewable natural resources, e.g.
fossil fuels consumed (expressed as mass).
• Likely reduction in noise levels.
• Likely reduction in odour nuisance (by elimination of a substance causing
odour).
• Likely reduction in on-site risk levels (from the point of view of process
safety).
• Likely reduction in release of globally important pollutants, e.g. ozonedepleting substances, persistent pollutants, etc.
Completed Worksheet 15b gives an example of environmental evaluation in practice.
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Running Example: Task 15
Completed Worksheet 15a: Technical feasibility analysis
Option ref. no.
Technical requirement
Impact (+/0/-)
Technology Production Production Operation
availability
rate
quality
flexibility
Maintenance
Safety
+
+
+
+
-
+
+
+
-
+
Equipment
requirement
Instrument or
accessories
Manpower
Space
availability
1
Floor to be made
-
-
-
-
0
0
5
Water efficient
nozzles
-
-
-
Yes
0
+
8
Variable speed
drive
-
-
Yes
Yes
0
9
Damper
10
O2 sensor
11
12
-
-
Yes
Yes
0
+
+
-
+
Electrical
fittings
-
Yes
Yes
+
+
+
0
+
Economizer
-
-
Yes
Yes
+
+
+
-
+
Air preheater
-
-
Yes
Yes
+
+
+
-
+
Water
treatment
facility
-
Yes
Yes
+
+
0
-
+
+
+
0
0
+
0
+
0
+
+
15
FBC boiler
17
Modification of
existing grate
-
-
19
Reverse osmosis
plant
-
-
20
Change of water
from tankers to
municipal supply
-
-
0
+
+
+
+
23
Recover
condensate
Piping
work
-
+
0
+
-
0
26
Thermodynamic
steam traps
-
-
+
+
0
-
+
Yes
Yes
Yes
Yes
Completed Worksheet 15b: Environmental aspect analysis
Option ref. no.
Impact (+/0/-)
Air
Solid waste
Overall impact*
-
Resource conserved
L
-
Water conserved
-
L
-
-
-
L
-
-
-
-
L
-
-
-
-
-
M
Reduced
-
-
-
-
-
M
Reduced
Reduced
-
-
-
-
-
M
Reduced
Reduced
-
-
-
-
-
H
17
Reduced
-
-
-
-
-
Reduced
L
19
Reduced
-
-
-
-
-
-
M
20
Reduced
-
-
-
-
-
-
M
23
Reduced
Reduced
-
-
-
Water conserved
Reduced
H
26
Reduced
-
-
-
-
Water conserved
-
L
gaseous emission
including GHG
Water
particulates
others
organics
(COD)
Total
solids
others
-
-
-
-
-
5
-
Reduced
-
-
8
Reduced
-
-
-
9
Reduced
-
-
10
Reduced
Reduced
11
Reduced
12
15
1
* H = heavy
M = medium
L = light
N = negligible
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
… Running Example: Task 15 (continued)
Completed Worksheet 15c: Economic viability analysis
CP-EE option no.
Annual savings (US$)
Payback period
1
1 063.8
3 191.5
5
425.5
NQ†
8,9
7 446.8
6 382.9
10
1 063.8
NQ†
17 021.2
26 595.7
8 months
15
170 212.7
143 404.2
15 months
17
1 063.8
NQ†
-
19
2 127.6
NQ†
-
20
Nil
11 489.36
Immediate
23
6 382.9
4 255.3
18 months
26
851.0
NQ
204 042
196 318.96
11,12
†
Investment (US$)
4 months
10 months
-
-
NQ = not quantified
Economic evaluation
The team must evaluate the economic benefits of all reductions in waste generated and
in consumption of resources that would be brought about by each option (see
Completed Worksheet 15c). It must estimate the immediately obvious savings in
purchase of materials and fuels, the costs of treatment and disposal avoided, and
material and waste stream costs (identified in M&E balance).
However, the team must also estimate less obvious financial benefits such as reduced
sick days for workers or generally higher worker productivity; lower personnel costs
from reducing the burden of special management and reporting of hazardous
materials, wastes and pollution; reduced worker and environmental liability; and
potential profits from sale of waste as a by-product or from carbon credits; etc.
Experience has shown that expanding financial assessments to the less obvious benefits
often helps considerably by throwing additional light on the economic feasibility of an
option. The team must also estimate the economic costs of each option, in terms of
investments in new technology or equipment as well as in terms of training and other
costs associated with implementation.
Benefits and costs are then analysed and calculated using various evaluation criteria
(e.g. pay back period, Net Present Value (NPV) or Internal Rate of Return (IRR),
etc.). These terms are explained in the box on the following page.
Cleaner Production – Energy Efficiency Manual
page 54
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Payback period
A simple payback period is evaluated from comparison of the annual savings resulting from implementation and
initial investment. This simply indicates the time needed to recoup the initial investment. It is calculated as:
Payback period (in years) = (Capital Investment/Annual Net Savings)
NPV and IRR
The simple payback period should, generally, be considered as an approximate or ‘ballpark’ assessment, as it
ignores depreciation of the investment made and the time value of money. Investment decisions are usually made
solely on the basis of payback period when the investment required is low and/or the returns are high enough for
the payback period to be less than two years.
If these conditions are not met, it is advisable to consider NPV or IRR. These take account of the time value of cash
inflows and outflows during the useful life of the investment made. This kind of economic evaluation requires
information on:
• The capital costs associated with any investments required.
• Net revenue, calculated as the difference between total revenue (could be higher than without
implementation) and operating costs (typically lower after implementation).
• Rates of interest and depreciation, to allow calculation of the present value.
NPV can be calculated using the following equation:
NPV = - (CF0 ) + ∑
i=n
i=0
Net Cashflow i
_____________
(1 + r) i
• CF0 = cash outflow in the first year (capital investment)
• r = opportunity cost of capital (for a rate of 10 per cent, ‘r’ would be 0.1)
• n = useful life of the investment in years
For an investment to be financially viable NPV must be greater than zero. Another indicator commonly used along
with NPV is the Profitability Index (PI). PI is the ratio of the present value of the total cash inflows to the present
value of the total cash outflows. For an investment to be financially viable, PI must be greater than 1.
IRR
IRR is essentially the rate of return on an investment that ensures that, during the investment’s lifetime, the net
cash flows (i.e. inflows – outflows) are equal to zero. In other words, IRR is the value of ‘r ’ that gives an NPV of
zero. It can be calculated using:
NPV = - (CF0 ) + ∑
i=n
i=0
Net Cashflow i
_____________
=0
(1 + r) i
This problem is solved by assuming a value for ‘r’, and then interpolating. The IRR obtained is then compared with
the rate of interest the market would demand for any borrowing that may be needed. Typically, if IRR is lower
than the market-borrowing rate, the investment is not considered financially viable. Completed Worksheet 15C
shows some actual data for economic viability analysis.
Cleaner Production – Energy Efficiency Manual
page 55
Part 1 CP-EE methodology
Task 16
Chapter 2: CP-EE assessment methodology
Selecting feasible options
The evaluations described above help to eliminate options that are not viable.
The remaining options now need to be prioritized and a few will then be
selected for implementation.
Prioritizing CP-EE options
In most cases, the feasibility analyses will indicate that different options have
differing levels of technical feasibility, economic viability, and environmental
performance. Since it may well not be possible to implement all options at the
same time, the team will have to prioritize the options. A common evaluation
framework will be necessary to assist with prioritization. A weighted-sum
method could be considered for this purpose (see Completed Worksheet 16).
Using this method, the team assigns a weight to each of the three aspects of the
feasibility analysis (technical feasibility, economical viability and environmental
performance). Weighting could be decided in a brainstorming session involving
top management. The weights will vary from company to company depending
on technical competence, financial conditions, environmental sensitivity, etc.
For example, a financially healthy, small company facing considerable
environmental pressures may decide to give the greatest weight to
environmental performance (say 50 per cent), less to technical feasibility (say 30
per cent) and least to financial viability (the remaining 20 per cent). This
indicates that the company is most keen to reduce the pollution load but does
not have high levels of capability to undertake technically complex options.
Once weights are assigned, simple indicators such as ‘scores’ can be developed
to assess the relative performance of each option. For example, economic
viability could be assessed based on payback period, NPV or IRR. Environmental
performance could be assessed based on a percentage reduction in pollution
load. Technical feasibility could be assessed based on technical complexity, new
equipment or technology required, or additional technical skills needed, etc.
Each option is then evaluated subjectively and scores are assigned for each of the
three aspects. Scores could range from 0 to 10, with the lower score implying
poor performance. For example, if two options have IRRs of 15 per cent and 33
per cent respectively, they could be assigned scores of 8 and 5 for this aspect of
economic viability.
Cleaner Production – Energy Efficiency Manual
page 56
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Running Example: Task 16
Completed Worksheet 16: Selection of CP-EE measures for implementation
Option
ref. no.
Options
30
25
45
10
1
Storing of coal on a concrete/ brick
lined, level floor
7
5
5
5.6
3
5
Optimize the use of water by
installing efficient showers /
sprinklers/spray/nozzles
5
7
5
5.5
4
8
Installation of variable speed drives
in ID and FD fan motors
7
2
6
5.3
5
9
Installation of damper to control air
flow
7
4
6
5.8
2
10
Install on-line O2 measuring sensor
3
5
5
4.4
7
11
Install economizer for waste heat
recovery
3
3
4
3.45
10
12
Install air preheater for recovery of
waste heat
2
3
4
3.15
11
15
Replace existing boiler with FBC
boiler
2
5
2
2.75
12
17
Modify the existing grate by
reducing the gaps between the rods
6
5
5
4.25
8
19
Install water treatment (RO) plant
2
3
3
2.7
13
20
Change the water used in the
boiler from tanker water to
municipal supply water
8
8
9
8.45
1
23
Re-circulate condensate from steam
separator wherever possible
5
4
6
5.2
6
26
Installation of steam taps (TD traps)
of rated capacity to be provided in
the steam main pipe within a gap
of 25 m
3
3
5
3.9
9
Weight (%)
Technical Environmental Economic Total Rank
feasibility
impact
feasibility
The weighted sum of the scores gives an index for each option and this can be used as
a basis to rank options in terms of their level of priority. The intention is not to prioritize
each option individually but to group options into categories such as ‘top’, ‘medium’
and ‘low’ priority. Prioritizing options in this way provides a basis for preparation of the
implementation plan.
Cleaner Production – Energy Efficiency Manual
page 57
Part 1 CP-EE methodology
STEP 5
Chapter 2: CP-EE assessment methodology
Implementation and continuation
• Preparing the CP-EE implementation plan
• Sustaining the CP-EE assessment
Task 17
Preparing the CP-EE implementation plan
A completed CP-EE implementation plan indicates how the projects required to
implement the options are to be organized, as well as the necessary funds and
human resources to be mobilized, and the associated logistics. Training,
monitoring and establishment of a management system such as EMS are also
often important components of an implementation plan (see Completed
Worksheet 17).
The implementation plan should clearly define the timing, tasks and
responsibilities. This involves:
• prioritizing implementation of options in accordance with available
resources;
• preparing the required technical specifications; site preparation; preparing
bidding documentation; short-listing submissions; etc.;
• allocating responsibilities and drawing up monitoring and review schedules.
The CP-EE team should give top priority to implementing options that are low
in cost, that are easy to implement and/or a pre-requisite for the
implementation of other options. This should be followed by options that
require further investment, laboratory or pilot trials, or interruption in
production schedules.
Options are often implemented during or immediately after the CP-EE studies.
In such cases, the very fact of conducting CP-EE according to this methodology
provides an example for others to follow.
Cleaner Production – Energy Efficiency Manual
page 58
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Running Example: Task 17
Completed Worksheet 17: Implementation plan for CP-EE measures
Option
no.
Selected
CP-EE measure
Classification Proposed date
(S/M/L)
of start
Person
responsible
1
Storing the coal on a concrete/brick
lined level floor
S
23-9-2002
Nikun Nanavati
Maintenance Engineer
2
Optimize the stack height and width
of coal heaps
S
30-9-2002
Nikun Nanavati
Maintenance Engineer
3
Use FIFO basis for coal usage
S
23-9-2002
Nikun Nanavati
Maintenance Engineer
5
Optimize the use of water by installing
efficient showers/sprinklers/spray/
nozzles
S
7-10-2002
Nikun Nanavati
Maintenance Engineer
8
Installation of Variable speed drives in
ID and FD fan motors
M
3-4-2003
Bimal Kumar
Operation In-Charge
9
Installation of damper to control air
flow
S
14-10-2002
Bimal Kumar
Operation In-Charge
10
Install on-line O2 measuring sensor
S
14-10-2002
Nikun Nanavati
Maintenance Engineer
11
Install economizer for waste heat
recovery
S
28-10-2002
Bimal Kumar
Operation In-Charge
12
Install air preheater for recovery of
waste heat
S
4-11-2002
Bimal Kumar
Operation In-Charge
13
Plug all the air leaks into boiler furnace
S
21-10-2002
Nikun Nanavati
Maintenance Engineer
15
Replace existing boiler with
FBC boiler
M
16-5-2003
Bimal Kumar
Operation In-Charge
16
Optimize the coal sizing by proper
crushing and sieving
S
11-11-2002
Bimal Kumar
Operation In-Charge
17
Modify the existing grate by reducing
the gaps between the rods
S
28-10-2002
Nikun Nanavati
Maintenance Engineer
19
Install water treatment (RO) plant
M
3-4-2003
Bimal Kumar
Operation In-Charge
20
Change the water used in the boiler
from tanker water to municipal supply
water
S
18-11-2002
Bimal Kumar
Operation In-Charge
21
Install conductivity meter to check
boiler drum
S
25-11-2002
Bimal Kumar
Operation In-Charge
23
Re-circulate condensate from steam
separator wherever possible
M
4-11-2002
Nikun Nanavati
Maintenance Engineer
24
Insulate all bare and damaged
portions
S
11-11-2002
Nikun Nanavati
Maintenance Engineer
25
Insulate the flanges (125 flanges)
S
18-11-2002
Nikun Nanavati
Maintenance Engineer
26
Installation of steam traps (TD traps)
of rated capacity to be provided in the
steam main pipe within a gap of 25 m
S
2-12-2002
Bimal Kumar
Operation In-Charge
S = small
M = medium
L = large
Cleaner Production – Energy Efficiency Manual
page 59
Part 1 CP-EE methodology
Task 18
Chapter 2: CP-EE assessment methodology
Sustaining the CP-EE assessment
The application of CP-EE and implementation of CP options often requires
changes in the organization and management system of the company.
The key aspects that may require change are: integration of new technical
knowledge; understanding new operating practices; revising of procedures;
installing and operating new equipment; or changing the packaging and
marketing of products/by-products. Changes will include modified preventive
maintenance schedules, waste segregation and recycling practices, etc. It is
therefore important to integrate the concept of CP into the company’s
management system in order to ensure that CP-EE is implemented as an ongoing activity.
Cleaner Production – Energy Efficiency Manual
page 60
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
2.7 Worksheets for a CP-EE assessment methodology
This section contains worksheets that will be helpful to CP-EE professionals conducting
CP-EE assessments. These worksheets are also included on the CD-ROM in editable,
printable format (Microsoft® Word™) allowing adaptation to any particular facility.
Click on the button in the top right corner of each worksheet to open the individual files.
List of worksheets (click to jump directly to any of the examples in this section):
• Worksheet 1:
CP-EE matrix
• Worksheet 2:
Involving employees
• Worksheet 3:
CP-EE team
• Worksheet 4a:
General information about the unit
• Worksheet 4b:
Department/section process flow
• Worksheet 4c:
Production details
• Worksheet 4d:
Inputs for production
• Worksheet 4e:
Existing utilities and energy intensive equipment
• Worksheet 4f:
Information available within the unit
• Worksheet 5:
Barriers and solutions
• Worksheet 6:
Weighting chart
• Worksheet 7:
Process flow diagram
• Worksheet 8:
Obvious housekeeping lapses
• Worksheet 9:
Input-output quantification and characterization
• Worksheet 10:
Baseline data
• Worksheet 11a: Material and energy balance
• Worksheet 11b: Cost of waste stream
• Worksheet 12:
Cause analysis
• Worksheet 13:
CP-EE options, generation and categorization
• Worksheet 14:
Screening of CP-EE options
• Worksheet 15a: Technical feasibility analysis
• Worksheet 15b: Environmental analysis
• Worksheet 15c: Economic viability analysis
• Worksheet 16:
Selection of CP-EE measures for implementation
• Worksheet 17:
Implementation plan for CP-EE measures
Cleaner Production – Energy Efficiency Manual
page 61
Organizing
Energy/environmental
management fully
integrated into
management structure.
Clear delegation of
responsibility for energy
use
Energy/environmental
manager accountable to
energy committee,
chaired by a member of
the management board
Energy/environmental
manager in post
reporting to ad hoc
committee but line
management and
authority unclear
Energy and environmental
management are parttime responsibility of
someone with only
limited influence
or authority
No energy/env.
manager or formal
delegation of
responsibility for
env./energy use
Policy and systems
Formal energy/
environmental policy
and management
system, action plan and
regular review with
commitment of senior
management or part of
corporate strategy
Formal energy/
environmental policy
but no formal
management system,
and with no active
commitment from top
management
Unadopted/informal
energy/environmental
policy set by
energy/environmental
manager
Cleaner Production – Energy Efficiency Manual
Unwritten guidelines
No explicit policy
Monitoring and
targeting reports based
on supply
meter/measurement
data and invoices.
Env./energy staff have
ad hoc involvement in
budget setting
Monitoring and
targeting reports for
individual premises
based on sub-metering/
monitoring, but savings
not reported effectively
to users
Comprehensive system
sets targets; monitors
materials and energy
consumption, wastes
and emissions; identifies
faults; quantifies costs
and savings; and
provides budget
tracking
Information systems
No contact with users
No information system.
No accounting for
materials and energy
consumption
and waste
Informal contacts
Cost reporting based on
between engineer and a invoice data. Engineer
few users
compiles reports for
internal use within
technical department
Contact with major
users through ad hoc
committee chaired by
senior departmental
manager
Energy/environment
committee used as main
channel together with
direct contact with
major users
Formal and informal
channels of
communication
regularly used by
energy/environmental
manager and staff at all
levels
Motivation
No promotion of
energy efficiency and
resource conservation
Informal contacts used
to promote energy
efficiency and resource
conservation
Some ad hoc staff
awareness and training
Programme of staff
awareness and training
Marketing the value of
material and energy
efficiency and the
performance of
energy/environmental
management
Awareness
No investment in
increasing
environmental/energy
efficiency in premises
Only low-cost measures
taken
Investment using
mostly short-term
pay-back critera
Same pay-back criteria
as for all other
investments. Cursory
appraisal of new
building and plant
improvement
opportunities
Positive discrimination
in favour of energy/
environmental saving
schemes with detailed
investment appraisal of
all new building and
plant improvement
opportunities
Investment
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 1: CP-EE matrix
OPEN FILE
page 62
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 2: Involving employees
Section no.
1
Tasks
OPEN FILE
Yes (✓)
No (✗)
CP-EE introduction
Workshop
• Middle manager
• Shop floor workers
• Utilities workers
• Adminstration staff
• Any other
2
Group meetings
Adminstration staff
Various sections in the process house
Utilities staff
Maintenance staff
Purchase department staff
Any other
3
Display of CP-EE posters
4
Display of short films on CP-EE success stories
5
Organizing of slogan campaign on environmental and energy themes
Cleaner Production – Energy Efficiency Manual
page 63
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 3: CP-EE Team
Section no.
1
OPEN FILE
Name
Mr XYZ
Designation
MD/GM/
Department
Operation/eng./utility
Role
Team leader
2
3
4
5
6
Worksheet 4a: General information about the unit
OPEN FILE
Section no.
1
Name and address of company
2
Contact Person
• Designation:
• Phone/e-mail:
3
Annual turnover
• 2001–02:
• 2002–03:
4
Employee strength
5
No. of working hours/year
6
No. of batches/year
Cleaner Production – Energy Efficiency Manual
page 64
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 4b: Department/section process flow
Major inputs
OPEN FILE
Department / Section
Major outputs
raw materials
product
Utilities Section
water treatment
refrigeration and a/c
boiler system
wastewater treatment
compressed air systems
Cleaner Production – Energy Efficiency Manual
page 65
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 4c: Production details
Section no.
1
Product name
XYZ
OPEN FILE
Installed capacity
Actual production
tons/yr
tons/yr
tons/yr
tons/yr
Comparision
%
a) Bleached cloth
b) Cotton
c) Rayon
d) Polyester
2
Printed cloth
3
Cleaner Production – Energy Efficiency Manual
page 66
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 4d: Inputs for production
8
7
Cleaner Production – Energy Efficiency Manual
Total kWh electricity
Eqivalent electricity
from diesel
Diesel
Grid electricity
Gas
Coal
Total water
Purchased water
Resources
Unit
1
2
3
4
5
6
months
9
10
11
12
Total average
OPEN FILE
page 67
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 4e: Existing utilities and energy intensive equipment
Section
Name of
Capacity
no.
utility
(TPH)
1
Boiler
2
Compressed air system
3
Thermic fluid heater
4
Furnaces
5
Cooling towers
6
DG set
7
R & A/C plants
8
Transformers
9
Motors
10
Fans
11
Pumps
Nos.
Cleaner Production – Energy Efficiency Manual
OPEN FILE
Specifications
Make
Type
Specific
design parameters
Specific operating
parameters
page 68
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 4f: Information available within the unit
Section
no.
1
Information required
Available/
not available
OPEN FILE
Available
since
Remarks
Layout
• Factory
• Steam and condensate
distribution network
• Compressed air distribution
network
• Refrigeration system network
• Cooling water circuit
2
Production details
3
Process flow diagram
4
Material balance
5
Energy balance
6
Design specification of utilities
7
Raw material consumption and cost
8
Energy, water consumption and cost
9
Waste generation and disposal records
10
Waste treatment records
11
Maintenance records
12
Any other
Cleaner Production – Energy Efficiency Manual
page 69
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 5: Barriers and solutions
Section
no.
1
Barriers
Yes
(✓)
No
(✗)
OPEN FILE
Enabling measures
suggested
Yes
(✓)
No
(✗)
Remarks
Attitude barriers
Lack of awareness on energy
and environment issues
Increase awareness
Emphasis on maximum
production rather than
productivity
Involve workers in decision
making
Complacent attitude towards
existing process/production
conditions
Acknowledge workers efforts
Hesitant about risks involved
Formulate incentive schemes for
workers
Low participation of workers
in CP-EE programme
Encourage experimentation for
CP-EE options
Belief that ‘I am doing
the best’
Review CP-EE measures on regular
basis using simple indicators
Increase interaction among similar
kind of industries
2
Organizational barriers
One-man show; middle
(supervisory) level missing
Delegation of authority
Loose management structure
Induction of technically sound
person
Production on ad-hoc basis
Right wage for the right person
Labour intensive: workers
employed on contract basis
Recruitment of permanent skilled
workforce
Inappropriate: profit sharing
Inadequate documentation of
inventory and production data
3
Trade barriers
Production on job-order basis
Setting up of integrated plants
Poor quality of input raw
material
Ensuring good quality of raw
materials from supplier
Industry mainly catering to
local markets
Standardization of product
Promotion of marketing in the
international market
Cleaner Production – Energy Efficiency Manual
page 70
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 5: Barriers and solutions (continued)
Section
no.
4
Barriers
Yes
(✓)
OPEN FILE
No
(✗)
6
Yes
(✓)
No
(✗)
Remarks
Technical barriers
Lack of:
• proper guidance on CP-EE
• technically sound professionals
• skilled workers
• laboratory analysis facility
• adequate in-plant waste usage
opportunities not available
5
Enabling measures
suggested
Training and awareness
workshops on CP-EE
Setting up of laboratory with
basic facilities
Erratic power supply
Provision of regular power supply
through captive power
generation
Relevant technical literature not
readily available
Promotion of relevant technical
literature through in-house
circulation
Highly water-intensive process
steps
Development of indigenous CP-EE
measures
Technology developed abroad
not applicable in Indian
conditions
Encouraging waste exchange
among industrial units
Economic barriers
Adequate funds not
available
Soft loans
Low financial returns on certain
CP-EE measures
Planned investment
Availability of cheap unskilled
labour making automation less
attractive
Incentive schemes for industries
going in for CP-EE
Changing excise and tax
liabilities
Training of workforce for specific
job and formulation of long-term
industrial policy
Other barriers
Abundant supply of resources
(e.g. water, making water
conservation less financially
attractive)
Imposition of water levy on
industries to restrict use, and
encourage modernization of
existing plants
Lack of available space
Lack of regulation on
environmental and energy
management systems
Cleaner Production – Energy Efficiency Manual
page 71
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 6: Weighting chart
Section no.
Criteria
OPEN FILE
Weight
1
Probability of payback CP-EE options from
section
10
2
Section/area consuming maximum
resources
5
3
Multiplier effects
5
4
Increase in product quality/production rate
5
5
Barriers
5
6
Management preference
10
7
External pressure (government, NGO, etc.)
10
TOTAL
50
Cleaner Production – Energy Efficiency Manual
Scores obtained
page 72
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 7: Process flow diagram
Input
stream
parameters
Input
stream
reference
OPEN FILE
Process step reference
Input raw
materials
Output
stream
reference
Output
stream
parameters
Remarks
Process step
Actual
Standard
Actual
Standard
Actual
Process
parameter
Standard
Equipment
Process
parameter
Process step
Equipment
Process
parameter
Process step
Equipment
Product
Cleaner Production – Energy Efficiency Manual
page 73
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 8: Obvious housekeeping lapses
Section
Name of
No.
section
Area
Obvious
lapses
OPEN FILE
Categorization of lapse
Solid
Liquid
Gas
Fuel
Electricity
Remarks
Other
1
2
3
4
5
6
Cleaner Production – Energy Efficiency Manual
page 74
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 9: Input-output quantification and characterization
OPEN FILE
Others
Characteristics
BOD
COD
pH
Total solids
Pressure
Outputs
Quantity
Temperature
Characteristics
Others
Moisture
content
Total solids
Pressure
S.No
Process
steps
or
unit
operations
Inputs
Quantity
Temperature
Cleaner Production – Energy Efficiency Manual
page 75
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 10: Baseline data
Section
Section/utility
Resource
no.
equipment
used
OPEN FILE
Quantity
Cleaner Production – Energy Efficiency Manual
Potential of CP-EE
Low
Medium
Targets
High
page 76
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 11a: Material and energy balance
Section
no.
Input
Name
Unit operation/
Quantity
unit process
Cleaner Production – Energy Efficiency Manual
OPEN FILE
Output
Name
Quantity
Waste stream
Liquid
Solid/gas
Energy
page 77
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 11b: Cost of waste stream
Section
no.
Section/process
Waste
stream
Components of
of waste stream
Cleaner Production – Energy Efficiency Manual
OPEN FILE
Quantity
Unit rate
Total cost of
waste component
page 78
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 12: Cause analysis
Section no.
Section
Cleaner Production – Energy Efficiency Manual
OPEN FILE
Waste stream
Probable cause
page 79
Section Section Waste CP-EE
no.
stream options
Good
housekeeping
Operating
Process
Raw
practices/
optimization
material
management
substitution
New
technology
New
Recovery
On-site
product
of useful
recycle
design by-products and reuse
Part 1 CP-EE methodology
Cleaner Production – Energy Efficiency Manual
Chapter 2: CP-EE assessment methodology
Worksheet 13: CP-EE options, generation and categorization
OPEN FILE
page 80
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 14: Screening of CP-EE options
Section
no.
CP-EE options
Directly
implementable
Cleaner Production – Energy Efficiency Manual
OPEN FILE
Require further
analysis
Pending later
consideration
page 81
requirement
measure Equipment
CP-EE
Instrument or Manpower
Space
Technology Production
accessories
availability availability
rate
Technical requirement
Product
quality
Operation
flexibility
Maintenance
Impact (+/0/-)
Safety
Worksheet 15a: Technical feasibility analysis
Cleaner Production – Energy Efficiency Manual
Note: Prepare detailed evaluation of individual workable option
No.
Option
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
OPEN FILE
page 82
measure
No.
Gaseous emission
including GHG
Cleaner Production – Energy Efficiency Manual
Others
Organics
(COD)
Total
solids
Water
H = High, M = Medium, L = Low, N = Negative
Particulates
Air
Impact (+/0/-)
Others
Solid
waste
Overall impact*
(H, M, L, N)
Worksheet 15b: Environmental analysis
* Note: Wherever possible quantitative impact is to be recorded
CP-EE
Option
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
OPEN FILE
page 83
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 15c: Economic viability analysis
Option
no.
CP-EE
options
Investment
(US$)
Operational
(US$)
Cleaner Production – Energy Efficiency Manual
OPEN FILE
Annual
saving (US$)
Payback
period
Remarks
page 84
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
Worksheet 16: Selection of CP-EE measures for implementation
Options
Options
ref. no.
Weighting (%)
Technical
Environmental
Economic
feasibility
impact
feasibility
30
25
45
Cleaner Production – Energy Efficiency Manual
OPEN FILE
Total
Rank
10
page 85
Part 1 CP-EE methodology
Chapter 2: CP-EE assessment methodology
expected
actual
expected
actual
OPEN FILE
(short, medium
or long term)
CP-EE
measure
no.
Classification
Selected
Option
proposed
Date
actual
responsible
Person
Economic
Results
Environmental
Worksheet 17: Implementation plan for CP-EE measures
Cleaner Production – Energy Efficiency Manual
page 86
Part 1 CP-EE methodology
Chapter 3: Case study
Cleaner Production and
Energy Efficiency Assessment
at
Luthra Dyeing and Printing Mills
Gidc, Pandesera, Surat, India (July 2002)
3.1 About the company
M/s Luthra Dyeing and Printing Mills (LDPM)—located in Surat, a city which accounts
for 40 per cent of textile dyeing and processing houses in India—is a leading and well
equipped textile processing house. The company started operations in 1980 and has
grown continuously since. It processes various types of synthetic polyester cloths from
grey to finished stage, with an installed processing capacity of around 3 200 tons of
fabric per year. By 2002, the company was processing around 2 400 tons of fabric per
year with a workforce of around 550 people. LDPM operates around 300 days per year,
on three shifts a day.
The company has recently acquired ISO 14001 certification. In order to continue on its
path to excellence in resource and energy conservation, it volunteered to undertake
CP-EE studies implemented by India's National Cleaner Production Centre. LDPM was
also selected for CP-EE studies for the following reasons:
• It is representative of the synthetic fabric processing sector in India.
• It has significant potential for CP-EE interventions, especially regarding water and
energy conservation.
• There is potential for technology upgrade.
• There is a possible multiplier effect.
• Management was committed to CP-EE studies and ready to cooperate.
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Chapter 3: Case study
3.2 Process description and process flow chart
As for any typical textile firm, the demand for fabric processing at LDPM is largely
dependent on customer requirements which are basically governed by existing market
trends and fashion. There are variations in the use of chemicals, in process operating
sequences and even in the equipment used for processing. A general description of the
process is given below, and the process is summarized in Figures 1.10 and 1.11.
The main activities carried out at LDPM for textile processing are as follows:
• Pre-treatment, which comprises drumming and scouring, weight reduction
and bleaching
• Dyeing
• Printing
• Finishing
• Ageing
• Washing (washing is carried out after every operation)
Pre-treatment
The pre-treatment process prepares the textile material for subsequent processing.
a) Drumming
The grey fabric received is treated in the drumming machine to obtain the desired grain
texture. The cloth is wetted and rotated in drums, both clockwise and anti-clockwise.
The operation is done four times—with plain water, then with swelling chemicals,
followed by two washes. The drummed fabric is dewatered in a hydro extractor.
b) Scouring, weight reduction and bleaching
Scouring is the main operation carried out to remove foreign substances such as oils,
fats and other impurities. It is an alkaline extraction process involving heat (80–130 °C)
and pressure (2–3 kg/cm2). Additional swelling of fibres takes place during scouring,
improving the dye-uptake rate.
If necessary, the fabric is treated in the same bath to reduce its weight to give it a light
feel. Whiteness of the fabric needs to be improved and bleaching is also carried out in
this bath (by oxidative or reductive decomposition).
The scoured fabric is subjected to hot wash, followed by neutralization of residual alkali.
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Part 1 CP-EE methodology
Chapter 3: Case study
Figure 1.10: Process sequence
GREY FABRIC
wetting (in drums)
dyeing
chemical treatment
hot washing
printing
dyeing
washings
reduction clearing
colour developing
• Operations in the
orange shaded area are
carried out in drums.
• Operations in the blue
area are carried out in
jet dyeing machines.
hydro extraction
cold washing
washings
scouring
drying
neutralization
stentoring
cold washing
shrinking
stentoring
DYED FINISHED FABRIC
PRINTED FINISHED FABRIC
Dyeing
Fabric is dyed to give it its desired colour. The fabric to be dyed is treated with dyes
and auxiliary chemicals at 120–130 °C and under pressure. Polyester fibre is usually
dyed by an exhaustion process. A dispersing agent is added and the pH is adjusted.
Accelerants and other auxiliaries (wetting agents, levelling agent, etc.) are also added
as required. Vat dyes are also occasionally used for dyeing.
In the post-dyeing stage, the material is rinsed thoroughly or soaped. For dark finishes,
the fabric is subjected to reductive alkaline cleaning after dyeing. It is then subjected
to pH balance and, if no printing is required, is subjected to a heat setting operation.
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Chapter 3: Case study
Figure 1.11: Pretreatment operations—inputs and outputs
GREY OR DRUM TREATED FABRIC
water
washing
wastewater
water
soda
caustic washing
wastewater
water
steam
scouring
wastewater
water
steam
hot washing
wastewater
water
HCI
neutralization
wastewater
water
washing
wastewater
scouring chemicals
heat by steam
heat setting
fumes
PRE-TREATED FABRIC
Printing
Printing is the process by which coloured patterns are produced on the fabric. The fabric
is printed on programmed, flat-bed or rotary screen-printing machines. It is then passed
through an attached dryer to remove moisture. Temperature in the dryer is varied
depending on the nature of fabric processed and the types of dyes used for printing. For
pigment printing, the temperature is maintained in the 160–170 °C range.
After printing, the printing screens are washed with water.
Finishing
Finishing comprises the final processes that make the fabric into an end-product. It
improves the feel and volume of the fabric.
Ageing
After printing the colours are not permanently fixed in the fabric. The ageing treatment
fixes the colour in the fabric permanently. This treatment is done in a Steam Ager or a
Loop Ager machine, at a temperature of 180–190 °C.
Washing
The fabric is washed to remove excess chemicals and dyes after every operation, or as
required. It is washed in several cold and hot washes, either in machines or in a series
of baths called washing ‘kundis’ (tanks). Excess wash water is removed by centrifuging.
Cleaner Production – Energy Efficiency Manual
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Part 1 CP-EE methodology
Chapter 3: Case study
3.3 Baseline information
The CP-EE team observed wide variations in the production process and the product
at LDPM. Initially, it was planned to study one complete batch to provide the basis for
a detailed material and energy balance, and to extrapolate from this to obtain an
overall scenario for the year. However, when values were compared it was found that,
for this type of industry, using just one batch as a unit is neither representative nor
useful in obtaining the desired information for a CP-EE assessment.
Data was collected for the year 2002, which was then considered as the baseline for
further comparison.
Production
The unit's products divide easily into two categories: dyed cloth and printed cloth, with
printed cloth being initially dyed or whitened. The total production is normalized in
terms of the total cloth produced on the basis of the resources used during the
production of the cloth. As inferred from production data (see Figure 1.12), the total
output from the unit is equal to the total cloth printed plus half of the total dyed
production. On average, the unit produces 100–210 tons of cloth per month
(normalized basis), depending on orders and market situation.
Figure 1.12: Production data
300
production
250
200
150
100
50
0
month
1
2
3
4
5
6
7
8
9
10
11
12
cloth dyed (tons)
51
30
65
48
62
44
42
63
80
126
83
104
cloth printed (tons)
87
108
112
155
157
92
148
168
162
148
101
151
total dyed + printed (tons)
138
138
177
203
219
136
191
231
242
274
184
256
total cloth normalized (tons)
112
123
145
179
188
114
170
199
202
211
143
203
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Part 1 CP-EE methodology
Chapter 3: Case study
Resource consumption
On average, the unit processes 8.0 tons of cloth per day. Like any textile processing
unit, the process requires steam, water, gas, compressed air, dyes and printing
chemicals, etc. The consumption of major resources for the year 2002 per ton of cloth
processed is shown in Table 1.2
Table 1.2: Major resource consumption at LDPM in 2002
Resources
Unit/ton
fabric
Months
Average
Purchased
water
(tanker or
municipal
supply)
m3
115
122
136
148
136
172
143
133
123
136
135
125
135
Bore well
water
m3
36
30
24
20
40
48
42
50
46
30
34
32
36
Recycled
water
(from ETP)
m3
50
56
62
66
46
38
44
36
40
56
52
54
50
Total water
m3
201
208
222
234
222
258
229
219
209
222
221
211
221
Coal (lignite)
ton
3
4
4
4
3
3
4
4
4
4
4
3
3
Gas
m3
772
846
697
625
611
804
629
656
582
576
623
553
664
kWh
698
663
345
1 587
234
294
225
234
208
1 469
1 641
1 356
746
Diesel
litre
247
256
363
0
608
417
421
366
361
0
0
0
253
Equivalent
electricity
from diesel
kWh
827
858
1 216
0
2 037
1 395
1 410
1 227
1 209
0
0
0
848
Total kWh
electricity
kWh
1 525
1 521
1 561
1 587
2 272
1 690
1 636
1 461
1 417
1 469
1 641
1 356
1 595
Grid
electricity
Dyes
kg
61
65.4
60.5
65.1
60.1
74.2
61
61.4
61.8
61.3
64
63.5
63.2
Gums
kg
82
80
88
93
85
110
100
93
87
90
99
85
91
Quantifying and characterizing wastewater
Monitoring in order to quantify and characterize wastewater in pre-treatment and
dyeing operations was carried out for a single batch of 2 400 metres of polyester fabric,
equivalent to 168 kg of fabric. Values were extrapolated for the day, assuming 48
batches per day, equivalent to 8.0 tons of cloth processed per day. For printing and
post-printing operations, monitoring was carried out for a 24-hour cycle.
The composite wastewater sample collected during the monitoring gave the results
shown in Table 1.3.
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Part 1 CP-EE methodology
Chapter 3: Case study
Table 1.3: Composite wastewater characteristics
Parameter
Range of values
1
Volume
130 m3/d to 140 m3/d
2
pH
6.75–8.5
3
Total solids (TS)*
9 000–11 500 mg/l
4
COD
900–1 200 mg/l
5
BOD
275–325 mg/l
Section no.
* TS values are relatively
high in relation to those
for typical textile
processing companies
because the groundwater
(bore well) used for
processing had a very
high total dissolved solids
concentration.
Table 1.4 shows quantification and characterization data for individual wastewater
streams.
Table 1.4: Wastewater quantification and characterization for individual streams
Section
no.
Waste stream
Quantity
(litres/batch)
Quantity
(litres/day)
Characteristics
pH
TS (mg/l)
COD (mg/l)
BOD (mg/l)
1
Wastewater from drum wash
800
38 400
8.11
20 608
1 362
654
2
Wastewater from washing of grey fabric
700
33 600
7.7
14 923
1 515
353
3
Wastewater from scouring
700
33 600
9.5
13 856
2 210
380
4
Wastewater after cold wash of scouring
900
43 200
7.12
4 500
1 532
243
5
Wastewater from bleaching
(bleaching liquor)
700
33 600
7.27
6 500
1 224
308
6
Wastewater from cold wash
of bleaching
720
34 560
8.35
4 300
890
150
7
Wastewater from dyeing only
(exhausted dye bath).
800
38 400
4
4 480
2 020
1 216
8
Wastewater from dyeing wash
770
36 960
8.85
4 350
800
250
9
Wastewater from neutralization
720
34 560
7.59
4 840
1 510
389
10
Wastewater from neutralization wash
11
Wastewater from washing of stirrer
blades in print paste cooking
12
Wastewater from washing of buckets
and drums used for print paste
preparation and storage
13
Wastewater from screen washing
14
Wastewater from squeeze wash
15
Wastewater from screen preparation
3.0 kl/d
3 000
16
Wastewater from print blanket washing
94 kl/d
94 000
17
Wastewater from washing of printed
fabric
100 kl/d
100 000
8.48
18
Steam condensate from dyeing
19
Cooling water (not to ETP)
720
34 560
-
4 800
980
316
30 kl/d
30 000
-
8 000
1 600
450
715 kl/d
71 500
-
8 500
770
230
1.1 l/s
31 680
5.81
27 048
1 980
204
-
8 000
1 700
170
5.69
25 688
745
238
11 712
1 750
360
Cleaner Production – Energy Efficiency Manual
600
28 800
150 000
0
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Part 1 CP-EE methodology
Chapter 3: Case study
CP-EE potential, targets and selection of audit focus
Based on the resource consumption and waste water generation data, it was surmised
that there was wide scope for resource reduction at LDPM, including energy and water.
Table 1.5 indicates the existing conditions, the potential for improvements and
probable targets to be achieved in the future.
Audit focus
It can be seen from Table 1.5, that the company has great potential for reduction of all
resources used. After discussions between the CP-EE team and management, it was
decided that the CP-EE studies should cover the entire plant and utilities. The aim was
to minimize resource wastage as far as possible so as to maximize reductions in GHG
emissions and increase profits.
Table 1.5: Potential for resource reduction at LDPM
Section no.
1
Parameter
Water (m3/t fabric)
Purchased
Bore well
Recycled
Total
Existing values
135
36
50
221
Cost (US$)
Potential
0.45/m3
0.02/m3
High
Low
Low
Moderate
0.11
High
Target 2004
90
30
45
165
2
Electrical power
(kWh/t fabric)
3
Thermal
Lignite (t/t fabric)
Natural gas (m3/t fabric)
3.0
664
35.48/t
0.20/m3
High
Moderate
2.0
500
Chemicals
Dyes (kg/t fabric)
Gum (kg/t fabric)
63.2
91
9.03/kg
0.41/kg
Low
Moderate
57.1
70
Pollution load
COD (kg/t fabric)
GHG (t/t fabric)
Wastewater (m3/t fabric)
150
7.6
161
High
High
High
120
6.0
120
4
5
1 595
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Part 1 CP-EE methodology
Chapter 3: Case study
3.4 Identification of waste streams, cause analysis and
CP-EE opportunities
Based on the information collected and compiled by the CP-EE team, a detailed cause
analysis was made of the various waste streams. Cause analysis and the observations
made during company visits were used as a basis to identify CP-EE options to reduce
resource consumption. Some of the major CP-EE options are given in Table 1.6.
Table 1.6: Cause analysis and generating CP-EE options
Waste streams
Probable cause
CP-EE options
Wastewater from washing
of grey cloth in drums
before pre-treatment
operations
•
Presence of foreign material (e.g. dust sticking to
fabric, inks, markings, etc.)
Removal of sizing material, oils and additional
impurities, etc. used during weaving operations
Use of excess water for drum soaking and washing
due to less than optimum capacity utilization
Use of large quantities of water for direct cooling of
the fabric (when the drum is opened, the fabric is
cooled before removal; this is done by placing a
hose into the drum and allowing the excess water to
flow out continuously)
Use of swelling agents during drum washing
operations
1
•
•
•
•
2
3
Optimization of cloth to liquor ratio from 1:6 to
1:4, by installation of water measurement device
or drum calibration and proper worker training
Installation of large capacity drum washer with
indirect cooling mechanism for improved
productivity and quality
Optimization of production planning for higher
capacity utilization of the existing drum washers
Low power factor in drum
motors
•
Variable loading of drums and sudden load during
start up operations
4
Installation of soft starter and variable
speed/frequency drives in motors
Wastewater from scouring
and weight reduction
operations and
subsequent washings
•
Use of excess scouring chemicals (caustic) in the
operation
5
Reuse of wastewater from scouring by adding
make up chemicals
Recovery of caustic by installing caustic recovery
system
Wastewater from
(bleaching) whitening
operations and
subsequent washings
•
Numerous steps for every small operation, with
washing after every operation.
7
Combining weight reduction, scouring and
whitening operations into a single operation
Wastewater from dyeing
operations
•
•
•
Use of high cloth to liquor ratio
Unexhausted dyes in the wastewater
Use of direct steam injection in jet machine to
maintain temperature and increase production rate
Small batches for dyeing in large jet dyeing machine
(i.e. unoptimized capacity utilization)
8
Markings on the jet machine so as to ensure
proper cloth to liquor ratio
Reduction in dye consumption from 5.5% to
4.25% by change in process parameters, e.g.
temperature from 130 °C to 135 °C and
retention time from 30 minutes to 60 minutes
6
•
9
continued …
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Part 1 CP-EE methodology
Chapter 3: Case study
Table 1.6: Cause analysis and generating CP-EE options (continued)
Probable cause
CP-EE options
•
Use of organic acids causing high COD load
10 Use of indirect steam instead of direct steam for
heating and recovery of condensate for reuse as
boiler feed water
11 Optimizing capacity utilization of jet dyeing
machine by production planning and
procurement of new, small jet dyeing machine
12 Replace acetic acid by tartaric acid
13 Eliminate usage of Citric W
14 Reduce usage of levelling agents by 10%
15 Use inorganic mineral acids in place of organic
acids
16 Replace the bottom basket in jet dyeing machine
by Teflon rods so as to increase the area and
enhance the capacity of the machine by 70 kg
17 Enhance capacity of the jet machines by
increasing the height of the machine
18 Use of spent dye bath from polyester dyeing
by adding make-up chemicals
19 Replacing ordinary water used for dyeing by
RO/DM water for higher dye exhaustion rate
Low power factor for
dyeing machine motor
•
Variable load pattern due to different batch sizes
and weight of cloth
20 Install soft starters and variable speed drives on
jet machine motors
Wastewater from
neutralization operation
and subsequent washing
•
•
Increase in peak demand
Improper removal of dyeing chemicals in washing
after dyeing
21 Optimizing the washing operations after dyeing
22 Reuse of neutralization waste liquor after adding
make up chemicals
Wastewater from washing
of stirrer blades after
cooking, print paste
preparation buckets and
drums
•
Excess print paste sticking to the stirrer blades,
buckets and drums
23 Scraping of print paste before washing
24 Use of dedicated buckets/drums and stirrer for
print paste preparation
25 Wiping of print paste from buckets with waste
tissue paper, rags, etc. before washing
Wastewater from washing
of screens after printing
•
Excess print paste sticking to the screens and on the
edges of the screen frames
26 Scraping and reuse of print paste from the
screens before washing
27 Washing of screens by high pressure, manually
actuated showers
28 Dipping of screens in a tank full of water before
final washing with fresh water
Wastewater and solvent
waste from blanket of flat
bed printing machine
•
Excess print paste seeping from screen through
cloth and onto the blanket
Printing on portions of blanket not covered by cloth
29 Reduce mesh size of the printing screens
30 Cover un-used side strip of blanket by waste
cloth strip
31 Provision of scraping mechanism using doctor
blade and squeeze end brush half dipped in
water to recover and reuse print paste from the
blanket
32 Recovery of solvent used for blanket washing by
installing solvent recovery plant
33 Use of non-organic liquid in place of solvent
Waste streams
•
continued …
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Part 1 CP-EE methodology
Chapter 3: Case study
Table 1.6: Cause analysis and generating CP-EE options (continued)
Waste streams
Probable cause
CP-EE options
Waste thermal energy
(gas) in printing machine
•
Idle running of burner on printing machine
34 Operating the machine on continuous drive by
installing auto cut off photovoltaic cell
Waste thermal energy
(gas) in padding mangle
•
Idle running of dryer even if there is no fabric
35 Installing photovoltaic cut off switch in padding
mangle
Wastewater from post
print washing in tanks
(kundi)
•
Unoptimized water usage in washing
36 Use of counter-current washing technique
37 Passing the cloth through roller squeezes
between each wash
Wastewater from cooking
pan, ageing machine and
zero-zero machine
•
Condensate from steam drained to ETP
38 Reuse condensate to boiler
Electrical and thermal
energy loss in loop ager
machine
•
Low efficiency of heat transfer from steam heated
tubes in loop ager machine
Feeding of single layer of cloth in loop ager even for
lighter quality of cloth
39 REPLACEMENT OF EXISTING LOOP AGER WITH
DIRECT GAS FIRED LOOP AGER SYSTEM (AN
INNOVATIVE SYSTEM DEVELOPED AT THE
PLANT AND NOW PATENTED)
40 Two end overlapped feeding of cloth to the loop
ager for light weight fabric
Thermal energy loss in
sanforizing drum
•
Inefficient heat transfer from steam to the drum
41 Direct gas firing in sanforizing drum by slit type
burner
Thermal energy loss in
existing boiler
•
•
No Excess air control
No waste heat recovery system from the boiler flue
gases
Higher blow down from boiler drum due to high
TDS in feed water
High level of unburnts in ash
Old and obsolete technology with efficiency of
around 65%
42 Installation of damper and variable speed drives
for ID and FD fans
43 Preheat the feed water to boiler by exit flue gases
44 Use low TDS municipal water in place of tanker
water
45 Reduce the coal size (lower mesh size) to be
used in boiler
46 Replace existing boiler system with a new FBC
boiler of 32 kg/cm2 pressure, coupled with back
pressure turbine for cogeneration of 2 MW
electrical power
•
•
•
•
Thermal energy losses in
steam distribution system
•
•
Uninsulated flanges
Condensation of steam forming pools of water in
the steam carrying pipes
47 Insulate all 125 existing flanges
48 Install thermodynamic steam traps in the main
header with a gap of 25 metres
Electrical energy loss in
compressed air supply
system
•
•
Leakages in the compressed air supply lines
Compressed air used at a higher pressure than
required
49 Conduct regular air leak detection tests
50 Reduce the air pressure to optimum limit
Electrical energy loss in
motors
•
Unoptimized motor loading
51 Conduct load analysis on motors and
reshuffle/replace optimum rating motors
Energy loss in electrical
lighting system
•
Use of old, energy-inefficient lighting fixtures
52 Replace 40 W tube light fixtures with energy
efficient 30 W fixtures
53 Provision of skylight windows overhead to
reduce lighting required during day time
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Part 1 CP-EE methodology
Chapter 3: Case study
3.5 Feasibility analysis of CP-EE options
To decide on implementation priorities, the CP-EE options developed were divided, by
preliminary screening, into ‘Directly Implementable’, ‘Requiring Further Analysis’ and
‘Pending, for Later Consideration’. Table 1.7 gives the detailed analysis.
Table 1.7: Prioritizing CP-EE options
CP-EE
option no.
CP-EE options
Directly
Pending, for later Remarks
Requiring
implementable further analysis consideration
✓
1
Optimization of cloth to liquor ratio from 1:6 to
1:4, by installation of water measurement device
or drum calibration and proper worker training
Change in operating
practice—workers fill drums
based on their experience,
and generally overfill them
2
Installation of large capacity drum washer with
indirect cooling mechanism for improved
productivity and quality
✓
3
Optimization of production planning for
capacity utilization of the existing drum washers
✓
4
Installation of soft starter and variable
speed/frequency drives in motors
✓
5
Reuse of wastewater from scouring by adding
make-up chemicals
6
Recovery of caustic by installing caustic recovery
system
✓
7
Combining weight reduction, scouring and
whitening operations into a single operation
✓
8
Markings on the jet machine so as to ensure
proper cloth to liquor ratio
9
Reduction in dye consumption from 5.5% to
4.25% by change in process parameters (e.g.
temperature from 130 °C to 135 °C and
retention time from 30 minutes to 60 minutes)
✓
✓
Discharged wastewater with
very high impurities, hence
cannot be reused
Change in operating
practice—workers fill drums
based on their experience,
and generally overfill them
✓
continued …
Cleaner Production – Energy Efficiency Manual
page 98
Part 1 CP-EE methodology
Chapter 3: Case study
Table 1.7: Prioritizing CP-EE options (continued)
CP-EE
option no.
CP-EE options
Directly
Pending, for later Remarks
Requiring
implementable further analysis consideration
10
Use of indirect steam to direct steam for heating
and recovery of condensate for reuse as boiler
feed water
✓
11
Optimizing the capacity utilization of jet dyeing
machine by production planning and
procurement of new, small jet dyeing machine
✓
12
Replace acetic acid by tartaric acid
✓
13
Eliminate usage of Citric W
✓
14
Reduce usage of levelling agents by 10%
15
Use inorganic mineral acids in place of organic
acids
16
Replace the bottom basket in jet dyeing
machine by Teflon rods so as to increase the
area and enhance the capacity of the machine
by 70 kg
✓
17
Enhance capacity of the jet machines by
increasing the height of the machine
✓
18
Use of spent dye bath from polyester dyeing by
adding make-up chemicals
✓
19
Replacing ordinary water used for dyeing by
RO/ DM water for increase dye exhaustion rate
✓
20
Install soft starters and variable speed drives on
jet machine motors
✓
21
Optimizing the washing operations after dyeing
✓
22
Reuse of neutralization waste liquor after adding
make up chemicals
23
Scraping of print paste from buckets /drums
before washing
24
Use of dedicated buckets/drums and stirrer for
print paste preparation
✓
Will cause quality problems
with the fabric and is difficult
to handle and use in small
quantities
✓
Will effect the quality of the
fabric as the discharged
wastewater will be coloured
✓
Change in operating practice
leading to recovery of print
paste
✓
Number of variations and
keeping dedicated buckets
etc. is not feasible
continued …
Cleaner Production – Energy Efficiency Manual
page 99
Part 1 CP-EE methodology
Chapter 3: Case study
Table 1.7: Prioritizing CP-EE options (continued)
CP-EE
option no.
CP-EE options
Directly
Pending, for later Remarks
Requires
implementable further analysis consideration
✓
25
Wiping of print paste from buckets with waste
tissue paper, rags etc before washing
26
Scraping and reuse of print paste from the
screens before washing
✓
Change in operating practice
leading to recovery of print
paste
27
Washing of screens by high pressure, manually
actuated showers
✓
Very low-investment solution
leading to water savings and
increased washing efficiency
28
Dipping of screens in a tank full of water before
final washing with fresh water
✓
Change in operating practice
with very small investment
29
Reduce mesh size of the printing screens
30
Cover unused side strip of blanket by waste
cloth strip
✓
Small investment resulting in
savings of print paste
31
Provision for scraping mechanism using doctor
blade and squeeze end brush half dipped in
water to recover and reuse print paste from the
blanket
✓
Small investment leading to
very high recovery of print
paste
✓
Will lead to increase of
solid/hazardous waste
Reducing mesh size means
that consistency of the print
paste will have to be
reduced, making dyes spread
on the cloth
✓
32
Recovery of solvent used for blanket washing by
installing solvent recovery plant
✓
The quantity of solvent is too
small to be recovered
33
Use of non-organic liquid in place of solvent
✓
Blanket washing efficiency
will reduce and may lead to
colour sticking on the
blanket causing problems for
further printing of fabric
34
Operating the machine on continuous drive by
installing auto cut off photovoltaic cell
✓
35
Installing photovoltaic cut off switch in padding
mangle
✓
36
Use of counter-current washing technique
✓
37
Passing the cloth through roller squeezes
between each wash
✓
38
Reuse condensate to boiler
✓
Obvious option resulting in
very high energy savings
continued …
Cleaner Production – Energy Efficiency Manual
page 100
Part 1 CP-EE methodology
Chapter 3: Case study
Table 1.7: Prioritizing CP-EE options (continued)
CP-EE
option no.
CP-EE options
Directly
Pending, for later Remarks
Requires
implementable further analysis consideration
✓
39
REPLACEMENT OF EXISTING LOOP AGER WITH
DIRECT GAS FIRED LOOP AGER SYSTEM (AN
INNOVATIVE SYSTEM DEVELOPED AT THE
PLANT ITSELF AND NOW PATENTED)
40
Two end overlapped feeding of cloth to the
loop ager for light weight fabric
41
Direct gas firing in sanforizing drum by slit type
of burner
✓
42
Installation of damper and variable speed drives
for ID and FD fans
✓
43
Preheat the feed water to boiler by exit flue gases
✓
44
Use low TDS municipal water in place of tanker
water
✓
45
Reduce the coal size (lower mesh size) to be
used in boiler
✓
46
Replace existing boiler system with a new FBC
boiler of 32 kg/cm2 pressure coupled with back
pressure turbine for cogeneration of 2 MW
electrical power
✓
47
Insulate all 125 existing flanges
✓
Obvious solution leading to
energy savings and better
quality of steam to be
supplied at the user end
48
Install thermodynamic steam traps in the main
header with a gap of 25 metres
✓
Obvious solution leading to
energy savings and better
quality of steam to be
supplied at the user end
49
Conduct regular air leak detection tests
✓
Good operation and
management practice
leading to energy savings
50
Reduce the air pressure to optimum limit
✓
Change in operating practice
leading to energy savings
51
Conduct load analysis on motors and
reshuffle/replace optimum rating motors
52
Replace 40 W tube light fixtures with energyefficient 30 W fixtures
✓
Obvious solution leading to
electrical energy savings
53
Provision of skylight windows overhead to
reduce lighting required during day time
✓
Obvious solution leading to
electrical energy savings
Cleaner Production – Energy Efficiency Manual
✓
Change in operating practice
for lighter fabric resulting in
energy savings
✓
page 101
Part 1 CP-EE methodology
Chapter 3: Case study
Techno-economic and environmental analysis
Before implementing CP-EE options it is necessary to verify their techno-economic and
environmental feasibility. This provides a basis to prioritize implementation of the
options. The team identified 53 CP-EE options at LDPM. Of the 53 options, 8 (15%)
were rejected at the outset as they were evidently unfeasible. Sixteen options were
considered for direct implementation, as their financial and technical implications were
fairly minor and quite evident. The remaining 29 options were subjected to testing of
their technical feasibility and the viability of those found to be technically feasible was
then subjected to environmental and economic analysis. Table 1.8 summarizes the
results of the analyses.
Table 1.8: Techno-economic and environmental feasibility of CP-EE options
CP-EE CP-EE options
option
no.
Technical feasibility
Technology
Space
Production
availability availability quality*
(+/0/-)
Environmental
benefits
Investment
(US$)
Annual
saving
(US$)
Payback
period
2
Installation of large capacity
drum washer with indirect
cooling mechanism for improved
productivity and quality
Yes
Yes
+
Reduced
wastewater volume
and pollution load
1 1361
NQ
NQ
3
Optimization of production
planning for capacity utilization
of the existing drum washers
Yes
Yes
+
Reduced
wastewater volume
and pollution load
NQ
NQ
NQ
4
Installation of soft starter and
variable speed/frequency drives
in drum motors
Yes
Yes
+
Increase power
factor and reduced
GHG emission
(accounted for in
option 42)
909 per
machine
682
18 months
6
Recovery of caustic by installing
caustic recovery system
Not
available
(reject)
Yes
+
7
Combining weight reduction,
scouring and whitening
operations into a single operation
Yes
Yes
+
Reduced waste
water volume and
pollution load
NIL
NQ
Immediate
9
Reduction in dye consumption
from 5.5% to 4.25% by change
in process parameters (e.g.
temperature from 130 ° to
135 ° and retention time from
30 minutes to 60 minutes)
Yes
Yes
+
Reduction in dye
consumption and
pollution load
NIL
NQ
NQ
continued …
Cleaner Production – Energy Efficiency Manual
page 102
Part 1 CP-EE methodology
Chapter 3: Case study
Table 1.8: Techno-economic and environmental feasibility of CP-EE options (continued)
CP-EE CP-EE options
option
no.
Technical feasibility
Technology
Space
Production
availability availability quality*
(+/0/-)
Environmental
benefits
Investment
(US$)
Annual
saving
(US$)
Payback
period
10
Use of indirect steam to direct
steam for heating and recovery
of condensate for reuse as
boiler feed water
Yes
Yes
+
Reduced
wastewater volume,
and 230 t/yr GHG
(by 150 t/yr coal)
795
5 453
15 months
11
Optimizing capacity utilization
of jet dyeing machine by
production planning and
procurement of new small jet
dyeing machine
Yes
Yes
+
Reduced
reprocessing and
reduced
wastewater volume
and pollution load
13 633
NQ
NQ
12
Replace acetic acid by tartaric
acid
Yes
Yes
+
Low pollution load
Nil
NQ
NQ
13
Eliminate usage of Citric W
Yes
Yes
+
Reduced pollution
load
Nil
NQ
Immediate
14
Reduce usage of levelling
agents by 10%
Yes
Yes
+
Reduced pollution
load
Nil
NQ
Immediate
16
Replace the bottom basket in
jet dyeing machine by Teflon
rods so as to increase the area
and enhance the capacity of
the machine by 70 kg
Yes
Yes
0
Increased
throughput from
the machine and
reduced specific
pollution load
23 per
machine
NQ
Less than 3
months
17
Enhance capacity of the jet
machines by increasing the
height of the machine
Yes
Yes
0
Increased
throughput from
the machine and
reduced specific
pollution load
909
NQ
NQ
18
Use of spent dye bath from
polyester dyeing by adding
make-up chemicals
Yes
Yes
+
Reduced pollution
load
2 272
1 818
14 months
19
Replacing ordinary water used
for dyeing by RO/ DM water
for high dye exhaustion rate
Yes
Yes
+
Reduced pollution
load (dye
exhaustion
increased by 8% in
trials)
20
Install soft starters and variable
speed drives on jet machine
motors
Yes
Yes
+
Reduced GHG
emissions
909 per
machine
568 per
machine
20 months
21
Optimizing the washing
operations after dyeing
Yes
Yes
+
Lower wastewater
and GHG emissions
NQ
NQ
Immediate
continued …
Cleaner Production – Energy Efficiency Manual
page 103
Part 1 CP-EE methodology
Chapter 3: Case study
Table 1.8: Techno-economic and environmental feasibility of CP-EE options (continued)
CP-EE CP-EE options
option
no.
Technical feasibility
Technology
Space
Production
availability availability quality*
(+/0/-)
Environmental
benefits
Investment
(US$)
Annual
saving
(US$)
Payback
period
34
Operating the machine on
continuous drive by installing
auto cut off photovoltaic cell
Yes
Yes
0
Reduced GHG
emission due to
savings of 6 300
m3 gas/ year
227
1 432
6 months
35
Installing photovoltaic cut off
switch in padding mangle
Yes
Yes
0
Reduced GHG
emission due to
savings of 6 000
m3 gas/ year
227
1 363
6 months
36
Use of counter-current washing
technique
Yes
Space not
available
(reject)
0
37
Passing the cloth through roller
squeezes between each wash
Yes
Yes
Trial failed
(reject)
39
REPLACEMENT OF EXISTING
LOOP AGER WITH DIRECT GAS
FIRED LOOP AGER SYSTEM
(INNOVATIVE SYSTEM
DEVELOPED AT THE PLANT
AND NOW PATENTED)
Yes
Yes
+
Reduced GHG by
2 300 t/year
through gas
savings of 108 000
m3/yr and coal
1 270 t/yr
45 445
73 598
7 months
41
Direct gas firing in sanforizing
drum by slit type of burner
Yes
Yes
+
Reduced GHG
emissions by fuel
savings of 7 tons
lignite
1 136
3 749
3 months
42
Installation of damper and
variable speed drives for ID and
FD fans
Yes
Yes
0
Reduced GHG
emission due to
electrical savings of
75 000 kWh (all
electrical options)
7 953
6 817
10 months
43
Preheat the feed water to boiler
by exit flue gases
Yes
Yes
0
Reduced GHG
emissions due to
lignite savings of
784 t/yr
2 272
28 403
2 months
44
Use low TDS municipal water in
place of tanker water
Yes
Yes
0
Reduced GHG
emissions due to
lignite savings of
337 t/yr
NIL
12 270
Immediate
45
Reduce the coal size (lower
mesh size) to be used in boiler
Yes
Yes
0
Reduced GHG
emissions
Combined with option 43
continued …
Cleaner Production – Energy Efficiency Manual
page 104
Part 1 CP-EE methodology
Chapter 3: Case study
Table 1.8: Techno-economic and environmental feasibility of CP-EE options (continued)
CP-EE CP-EE options
option
no.
Technical feasibility
Environmental
benefits
Technology
Space
Production
availability availability quality*
(+/0/-)
46
Replace existing boiler system
with a new FBC boiler of
32 kg/cm2 pressure coupled
with back pressure turbine for
cogeneration of 2 MW
electrical power
Yes
Yes
0
Reduced GHG
emissions (about
3 200 t/yr)
51
Conduct load analysis on
motors and reshuffle/replace
optimum rating motors
Yes
Yes
0
Reduced GHG
emissions
* Production quality: 0 = no effect
+ = positive
Investment
(US$)
Annual
saving
(US$)
181 779
153 149
NQ
NQ
Payback
period
NQ
- = negative effect
Values marked ‘NQ’ cannot be quantified at present because data were missing; they would be quantified after implementation of
the CP-EE solution.
Three CP-EE options were rejected on the basis of their technical feasibility analysis—one
because of non-availability of space in the company, another because trials were not
successful, and a third because of non-availability of proven technology at small scale.
The company has already implemented a number of low-cost options and has also
invested in at least one large, capital-intensive CP-EE option: conversion of the loop
ager system to combined direct gas firing and steam. Since implementation of this
system, the company has obtained a patent for it. Demonstration of the system at
LDPM's premises could persuade other companies to adopt this technology.
3.6 Benefits and achievements
The LDPM unit has already implemented 27 CP-EE options fully and 12 more options
have either been partially implemented or are in the advanced stages of planning. No
consensus was arrived at for three options, which were left to be followed up later.
Since one of the objectives of the project is to reduce GHG emissions, special emphasis
was given to the GHG emission reduction potential of the CP-EE options. Table 1.9
indicates the GHG saving from various CP-EE options
Cleaner Production – Energy Efficiency Manual
page 105
Part 1 CP-EE methodology
Chapter 3: Case study
Table 1.9: GHG savings potential of CP-EE options
CP-EE
option no.
CP-EE options
Savings
(coal/gas/electricity)
GHG reduction
(tons/year)
4
Installation of soft starter and variable speed/frequency drives
in drum motors
Increase power factor and reduced GHG
emission (accounted for in option 42)
10
Use of indirect steam to direct steam for heating and recovery
of condensate for reuse as boiler feed water
150 t/yr coal
230
20
Install soft starters and variable speed drives on jet
machine motors
Reduced GHG emissions
NQ
34
Operating the machine on continuous drive by installing auto
cut off photovoltaic cell
Reduced GHG emission due to savings of
6 300 m3 gas/ year
15
35
Installing photovoltaic cut off switch in padding mangle
Reduced GHG emission due to savings of
6 000 m3 gas/ year
15
38
Reuse the condensate (from cooking pan) to boiler
Reduced GHG emissions
NQ
39
REPLACEMENT OF EXISTING LOOP AGER WITH DIRECT GAS
FIRED LOOP AGER (AN INNOVATIVE SYSTEM DEVELOPED AT
THE PLANT AND NOW PATENTED)
Reduced GHG by 2 206 t/year through gas
savings of 108 000 m3/yr and coal 1 270 t/yr
40
Two end overlapped feeding of cloth to the loop ager for
light weight fabric
Reduced GHG emissions
NQ
41
Direct gas firing in sanforizing drum by slit type burner
Reduced GHG emissions by fuel savings of
7 tons lignite
10.7
42
Installation of damper and variable speed drives for
ID and FD fans
Reduced GHG emission due to electrical
savings of 75 000 kWh (all electrical options)
43
Preheat the feed water to boiler by exit flue gases
Reduced GHG emissions due to lignite
savings of 784 t/yr
1 200
44
Use low TDS municipal water in place of tanker water
Reduced GHG emissions due to lignite
savings of 337 t/yr
516
45
Reduce the coal size (lower mesh size) to be used in boiler
Reduced GHG emissions
NQ
46
Replace existing boiler system with a new FBC boiler of
32 kg/cm2 pressure coupled with back pressure turbine for
cogeneration of 2 MW electrical power
Reduced GHG emissions by about 3 200 t/yr
47
Insulate all 125 existing flanges
Reduced GHG emissions due to savings of
30 t lignite/yr
46
48
Install thermodynamic steam traps in the main header with
gap of 25 metres
Reduced GHG emissions
NQ
49
Conduct regular air leak detection tests
Reduced GHG emissions
NQ
50
Reduce compressed air pressure to optimum limit
Reduced GHG emissions due to savings of
8 125 kWh/yr electrical power
7.2
51
Reshuffle and replace optimum rating motors
Reduced GHG emissions
NQ
52
Replace 40W tube light fixtures with energy efficient
30W fixtures
Reduced GHG emissions by electrical power
savings of 70 664 kWh/year
63
53
Provision of skylight windows overhead to reduce lighting
required during day time
Reduced GHG emissions
NQ
TOTAL
Cleaner Production – Energy Efficiency Manual
-
2 206
67
3 200
7 756 t/yr
page 106
Part 1 CP-EE methodology
Chapter 3: Case study
The CP-EE team collected the data from the unit for the month of April 2003 and
compared this with the baseline data (i.e. before implementation of the CP-EE options).
Table 1.10 shows the comparison of various parameters before and after the
implementation of CP-EE options.
Table 1.10: LDPM before and after CP-EE
Section
no.
1
Parameters
Values
before CP-EE
Value
after CP-EE
implementation
monthly
average 2002
monthly
average 2002
average
change
(%)
Remarks
Average cost1
(US$)
Annual economic
benefit (basis =
2 400 tons
production/year)1
(US$)
Production
(tons of fabric)
153.4
145
Purchased
135
102
24.4
0.46/m3
Bore well
36
36
0
0.017/m3
Normalized
2
3
Water (m3/t fabric)
Recycled
50
30
40
Total
221
168
24
1 595
1 268
20.5
Lignite (t/t fabric)
3.0
2.15
Natural gas (m3/t fabric)
664
482
Dyes (kg/t fabric)
63.2
Gum (kg/t fabric)
Electrical power
(kWh/t fabric)
4
5
6
364 240
0.11/kWh
85 595
28.3
36/t
73 552
9.9
0.20/m3
31 879
43
32.02
9.18/kg
91
70
23.1
0.42/kg
COD (kg/t fabric)
150
140
6.7
GHG (t/t fabric)
7.6
5.6
22.8
O&M cost
Wastewater (m3/t fabric)
161
130
19.3
of ETP
Thermal
Chemicals
21 232
Pollution load
NQ, reduced
1
Original figures were given in Indian rupees, slight discrepancies between savings per unit price and total savings are due to
rounding after conversion to dollars. The figures indicate the magnitude of possible savings.
2
The reduction in dyes used cannot be attributed wholly to the improvement due to implementation of CP-EE solutions. Changes
in market conditions, prevalent fashion requiring lighter shade, etc. would also result in reduction in dyes used.
Cleaner Production – Energy Efficiency Manual
page 107
Part 1 CP-EE methodology
Chapter 3: Case study
3.7 CP-EE assessment barriers
Project progress was hampered by barriers from the CP-EE assessment phase through
to the implementation phase. CP-EE implementation started very well but suffered
later, particularly because of market conditions and increasing competition.
Table 1.11 shows the major constraints encountered and indicates actions taken to
overcome them.
Table 1.11: Major barriers to the CP-EE process
Category
a) Technical
b) Organizational
c) Financial
Barrier
Consequences
Actions undertaken to
overcome barriers
Inadequate in-house facility for
laboratory analysis
Some of the analyses, (such as dye
exhaustion) could not be carried out
initially and the results of trial were
not reflected immediately
Initially samples were analysed by an
external agency, later a small
laboratory was set up in the plant itself
Lack of Instrumentation for
measurement of resources used in the
process (e.g. steam and water)
Resources could not be quantified
directly and accurately
Estimated on the basis of indirect
measurements
Specifications of motors and pumps
not available
Motor load analysis for replacing/
reshuffling motors of optimum ratings
could not be conducted in detail
Technical specifications of similar type
and make of motors were collected
from manufacturer and the relevant
parameters were compared.
Production is on ad hoc basis
Frequent changes in the production
pattern made monitoring difficult
Monitoring scheduled per batches
processed
Records for dye consumption in
dyeing and printing section not
maintained
Accurate analysis for dye usage and
waste in different sections not
possible
Analysis done on the basis of the
records of 12 days (study period for
1st phase)
Availability of cheap unskilled workers
making automation less attractive
Payback period for the CP-EE options
increases
–
Cleaner Production – Energy Efficiency Manual
page 108
Part 1 CP-EE methodology
Chapter 3: Case study
3.8 Conclusions
The CP-EE demonstration provided a number of valuable lessons, the most important
of which is that, when resources (e.g. groundwater) are low-priced, a CP solution alone
may not be attractive. However, when combined with EE benefits in terms of electricity
savings (e.g. per litre of water saved), a more attractive package can be proposed.
Energy audit studies were conducted in the past by external agencies which made
suggestions for improvements. However, subsequent change was neither continuous
nor regular. The CP-EE studies have enabled the management to build a system of energy
auditing and conservation into the day-to-day work pattern, thereby making the concept
sustainable. The case study reaffirms that appropriate monitoring is crucial in identifying,
assessing and driving CP-EE implementation. The results are summarized in Table 1.12.
Finally, due to an economic slowdown in the textile industry in India, the management
was restricted from implementing some feasible CP-EE measures. However, as the
CP-EE options adopted demonstrate, implementing CP-EE does not necessarily need
significant up-front investment. In fact, CP-EE can be an effective tool to sustain a unit
in tough economic conditions.
Table 1.12: Results of the CP-EE studies at LDPM at a glance
Item
No. or value
1
Total no. of CP-EE options identified
53
2
Number of CP-EE solutions implemented so far
27
3
Number of CP-EE solutions under implementation
12
4
Total of options rejected, including for techno-economic feasibility
11
5
Savings in resource consumption/year
Section no.
a) Water consumption (m3)
b) Natural gas
(m3)
c) Electricity consumption (kWh)
d) Coal (lignite) (tons)
6
127 200
158 400
784 800
2 040
Reduction in pollution load/year
a) Wastewater volume (m3)
b) Water pollution load COD (tons)
c) Gaseous emissions (GHG) (tons)
7
Improved quality of the product
8
Total investment made
9
Direct savings
10
Payback period
Cleaner Production – Energy Efficiency Manual
78 000
24
4 152
Positive
US$73 393
US$227 490
4 months
page 109
ENERGY
EFFICIENCY
Cleaner Production – Energy Efficiency Manual
page 110
Part 2
Technical modules
Module 1 provides background information on different
energy-using systems and information that will be helpful
in identifying areas of focus for CP-EE assessments. The
module covers:
• Thermal systems
• Electrical systems
Module 2 presents Energy Efficient Technologies.
Both modules include worksheets that can be used
during assesment.
Contents listing
Part 1 CP-EE methodology
Part 3 Tools and resources
Cleaner Production – Energy Efficiency Manual
page 111
Part 2 Technical modules
Module 1:
Energy use in industrial production
Thermal systems
M1.1 Fuels—storage, preparation and handling
M1.1.1 Fuel oils
Fuel storage tanks are generally made from welded mild steel. Overhead tanks should
be mounted on concrete blocks and should be equipped with vent and drain pipes.
The drainpipe is used for periodic removal of accumulated water. Care should be taken
when oil is being decanted from tankers to storage tanks. All leaks from joints, flanges
and pipelines must be attended to as a matter of urgency.
CP-EE
spotlight
Loss of even one drop
of oil every second can
cost you more than
4 000 litres a year.
Fuel oil should be free from contaminants such as dirt, sludge and water before it is fed
to the combustion system. A filtering system may be provided for optimum
combustion efficiency. It is desirable to preheat fuel oil to lower the viscosity
appreciably in order to light the burner.
Storage and pumping temperature
The temperature at which oil can readily be pumped depends on the grade of oil.
Table M.1 can be used as a guide for the most common grades of fuel oil.
Table M.1: Viscosity vs. temperature
Viscosity (centistokes)
Pumping temperature (°C)
50
7
230
27
900
38
1 500
49
Oil should never be stored at a temperature above that necessary for pumping, as this
leads to higher energy consumption. The energy use snapshot (right) illustrates this.
Cleaner Production – Energy Efficiency Manual
CP-EE
spotlight
At only 6 °C above the
required minimum
temperature, a lagged fuel
oil tank with a diameter of
1.8 m and length of 4.6 m
would waste
approximately 6 800 kg of
steam in a year.
page 112
Part 2 Technical modules
Module 1: Energy use in industrial production
Oil preheating
Line heaters are used to raise the oil from pumping temperature to burning
temperature. Table M.2 gives a rough guide to the heating required, but optimum
conditions can only be obtained by trial and error.
Table M.2: Preheating guide
Viscosity (centistokes)
Burning temperature (°C)
50
60
230
104
900
121
It is advisable to use a positive displacement pump such as a gear pump to pump fuel
oil. Sometimes no oil is transferred through the pipes because of excessive pressure
drop and cavitation at the pump.
A centrifugal pump is not recommended because, as oil viscosity increases, the
efficiency of the pump drops sharply and the horsepower required increases.
M1.1.2 Coal
Uncertainty in the availability and transportation of fuel necessitates storage and
subsequent handling. Stocking of coal has disadvantages including build-up of
inventory, space constraints, deterioration in quality and potential fire hazards. Other
minor losses associated with the storage of coal include oxidation, wind and carpet loss
(formation of a soft ‘carpet’ of coal dust and soil). One per cent oxidation of coal is
equivalent to 1 per cent ash in coal and wind losses may account for 0.5–1.0 per cent
of total losses.
The main aim of good coal storage is to minimize carpet loss and losses due to
spontaneous combustion. Spontaneous combustion in coal heaps can be caused by
the gradual increase in temperature resulting from oxidation.
Measures that can help to reduce carpet losses are as follows:
• Preparing a hard ground for coal to be stacked.
• Preparing standard storage bays in concrete and brick.
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In process industries, modes of coal handling range from manual to conveyor systems.
It is advisable to minimize the handling of coal to avoid further generation of fines and
segregation effects.
Preparation of coal
Preparation of coal prior to feeding into the boiler is important for achieving good
combustion. Large and irregular lumps of coal may cause the following problems:
•
•
•
•
Poor combustion and inadequate furnace temperature.
Higher excess air resulting in higher stack loss.
Increase of unburnts in the ash.
Low thermal efficiency.
Sizing of coal
Proper coal sizing is one of the key measures in ensuring efficient combustion. Proper
coal sizing, specific to the type of firing system, helps towards even burning, reduced
ash losses, and better combustion efficiency.
Coal is reduced in size by crushing and pulverizing. Pre-crushed coal can be
economical for smaller units, especially those which are stoker fired. In a coal handling
system, crushing is limited to a maximum size of 6 or 4 mm. Table M.3 shows suitable
sizes of coal for different firing systems. The most commonly used devices for crushing
are the rotary breaker, the roll crusher and the hammer mill.
Table M.3: Sizes of coal for different types of firing systems
Section no.
1
2
Type of firing system
Size (mm)
Hand firing
a) Natural draught
25–75
b) Forced draught
25–40
Stoker firing
a) Chain grate
1
i. Natural draught
25–40
ii. Forced draught
15–25
b) Spreader stoker
15–25
3
Pulverized fuel fired
75% below 75 micron1
4
Fluidized bed boiler
< 10 mm
micron = 1/1000 mm
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Coal must be screened before crushing so that only oversized coal is fed to the crusher.
This helps to reduce power consumption in the crusher. Recommended practices in
coal crushing are:
• Incorporation of a screen to separate fines and small particles, to avoid extra fine
generation in crushing.
• Incorporation of a magnetic separator to separate iron pieces in coal, which may
damage the crusher.
Conditioning of coal
The fines in coal present problems in combustion, owing to segregation effects.
Segregation of fines from larger coal pieces can be greatly reduced by conditioning
coal with water. Water helps fine particles to stick to the bigger lumps (due to surface
tension of the moisture) and stops fines from falling through grate bars or being carried
away by the furnace draught. While tempering the coal, care should be taken to ensure
that moisture addition is uniform. It is preferable to do this in a moving or falling
stream of coal.
If the percentage of fines in the coal is very high, wetting of coal can decrease the
percentage of unburned carbon and the excess air level required for combustion.
Table M.4 shows the extent of wetting, depending on the percentage of fines in coal.
Table M.4: extent of wetting, fines vs surface moisture in coal
Fines (%)
Surface moisture (%)
10–15
4–5
15–20
5–6
20–25
6–7
25–30
7–8
Blending of coal
When coal lots have excessive fines, it is advisable to blend predominantly lumped coal
with lots containing excessive fines. Blending coal in this way can help to limit the
extent of fines in coal being fired to no more than 25 per cent. Blending of different
qualities of coal may also help to provide uniform coal feed to the boiler.
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M1.2 Combustion
Fossil fuels (coal, oil, gases) are combinations of carbon, hydrogen, undesired elements
(e.g. sulphur, oxygen, nitrogen etc.), and ash constituents. These elements are burned
in the presence of the oxygen in the combustion air. The efficiency of a boiler or
furnace depends on the efficiency of the combustion system. For example, combustion
of oil is effected by a burner which mixes fuel and air in the correct proportions for
complete combustion, with consequent release of heat.
Basic combustion reactions—ideal or stoichiometric combustion
The amount of air to be supplied for combustion of the fuel depends on the elemental
constitution of the fuel, i.e. the proportions of carbon, hydrogen, sulphur, etc. in the fuel.
Analyses of the compositions of some typical coals are shown in Tables M.5 and M.6. The
amount of air required, based on the chemical make-up of the fuel, is called the ideal or
stoichiometric amount. This is the minimum amount of air required if mixing of fuel and
air by the burner and combustion are to be perfect. For example, for ideal combustion
of 1 kg of a typical fuel oil containing 86 per cent carbon, 12 per cent hydrogen and 2
per cent sulphur, the theoretical minimum amount of air required is 14.1 kg.
Table M.5: Proximate analysis of typical coal
Lignite
Moisture (%)
1
Bituminous coal
(Sample 1)
Bituminous coal
(Sample 2)
Indonesian coal
50
5.98
4.39
9.43
Ash (%)
10.411
38.65
47.86
13.99
Volatile matter (%)
47.761
20.70
17.97
29.79
Fixed carbon (%)
41.831
34.69
29.78
46.79
dry basis
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Table M.6: Ultimate analysis of typical coal
Lignite
Moisture (%)
Bituminous coal
(Sample 1)
Bituminous coal
(Sample 2)
Indonesian coal
Dry basis
5.98
4.39
9.43
Mineral matter (%)
10.41
38.63
47.86
13.99
Carbon (%)
62.01
42.11
36.22
58.96
Hydrogen (%)
6.66
2.76
2.64
4.16
Nitrogen (%)
0.60
1.22
1.09
1.02
Sulphur (%)
0.59
0.41
0.55
0.56
Oxygen (%)
19.73
9.89
7.25
11.88
GCV (kcal/kg)
6 301
4 000
3 500
5 500
The main products of combustion are carbon dioxide (CO2), water vapour (H2O),
sulphur dioxide (SO2) and nitrogen oxides (NOx). Figure M.1 shows the different
constituents of flue gas after complete, i.e. stoichiometric, combustion.
Figure M.1 Combustion products
AIR
21% oxygen (O2) by vol.
79% nitrogen (N2) by vol.
carbon dioxide (CO2)
COMBUSTION
water vapour (H2O)
CHAMBER
FUEL
1 100–1 400 °C
sulphur dioxide (SO2)
86% carbon (C)
12% hydrogen (H2)
nitrogen oxides (NOx)
2% sulphur (S)
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Table M.7 shows the heat of reaction from different constituents from fuel.
Table M.7: Heat from different fuel constituents
2C+O2
2CO + 2 430 kcal/kg of carbon
C + O2
CO2 + 8 084 kcal/kg of carbon
2H2 + O2
2H2O + 28 922 kcal/kg of hydrogen
S + O2
SO2 + 2 224 kcal/kg of sulphur
In normal operating conditions it is not possible to achieve complete combustion by
supplying just the theoretical amount of air required. A certain amount of excess air is
needed to achieve complete combustion and ensure release of all of the heat contained
in fuel. Too much excess air, however, leads to heat loss via the chimney; less air leads
to incomplete combustion and black smoke. Hence, there is an optimum level of
excess air that gives optimum combustion conditions—this varies from one fuel to
another. If excess air is used in combustion, sulphur trioxide (SO3) may also be formed.
When using liquid fuels (especially heavy fuel oil) there is a permanent danger that the
fuels will contain water. Water is put into the boiler (together with the useful fuel)
where the water is heated, evaporated and exhausted through the stack. Water cannot
be burned and is ballast, i.e. all of the heat used to heat and evaporate it is lost. When
using coal, part of the solid carbon put into the boiler leaves (without being burned)
directly in the ash.
The heat produced in a boiler by fuel combustion is used to heat water (fresh water or
preferably recovered condensate) to boiling point (which depends on the pressure of
the water); to evaporate the water (at constant temperature); and then, eventually, to
superheat the steam.
Air supply
Since combustion is not instantaneous but takes place in stages, the fuel needs time to
burn in the hot furnace, with sufficient air to complete combustion. Air is therefore
admitted in two ways (i) as Primary Air entering the furnace with the fuel or, in the case
of solid fuel burning on a grate, through the fuel bed and (ii) as Secondary Air admitted
turbulently to complete combustion.
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There are three usual mechanisms by which combustion air can be supplied, these are
listed below. Sometimes a combination of the three is employed.
i. Natural draught, created when the hot gases pass up the chimney, causing
suction in the furnace.
ii. Induced draught (ID), caused by a fan located at the boiler outlet sucking air
through the system and augmenting the suction of the chimney.
iii. Forced draught (FD), caused by a fan located before the furnace and blowing air
through.
A combination of induced draught and forced draught is known as balanced draught.
Control of air and analysis of flue gas
For optimum combustion, the real amount of combustion air must be greater than
that required theoretically. Part of the stack gas consists of pure air, i.e. air that is
simply heated to stack gas temperature and leaves the boiler through the stack.
Chemical analysis of the gases is an objective method that helps to achieve finer air
control. By measuring CO2 (see Figure M.2) or O2 (see Figure M.3) in flue gases (by
continuous recording instruments or Orsat apparatus or some cheaper portable
instruments) the excess air level and stack losses can be estimated (using graphs like
those shown in the figures). The excess air to be supplied depends on the type of fuel
and the firing system.
Figure M.2 Analysis of stack gases
100
90
80
excess air (%)
70
60
50
40
30
20
10
0
8.4
9
10
11
12
13
14
carbon dioxide (%)
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For optimum combustion of fuel oil the CO2 or O2 in flue gases should be maintained
as follows:
• CO2 = 14.5–15 %
• O2 = 2–3 %
Figure M.3 Relationship between residual oxygen and excess air
250
excess air (%)
200
150
100
50
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
residual oxygen (%)
Reasons for incomplete combustion
Combustion should be complete within the furnace and this can only happen when
the ‘rule of the three Ts’ (i.e. TIME, TEMPERATURE, TURBULENCE) is strictly observed.
This means:
1. Allowing sufficient time for the fuel to burn in the hot furnace.
2. Having the fuel at a sufficiently high temperature to burn.
3. Mixing the fuel turbulently with sufficient air in the combustion chamber.
The following are a few possible reasons for incomplete combustion of fuel:
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• Air pressure is not sufficient and air passes through the furnace without mixing
thoroughly with fuel.
• The fuel has not reached the ignition temperature to react with air.
• Fuel and air have not had time to react before the combustion products are cooled.
• Air ingress through peepholes, leakages at dampers and other places.
• Late combustion due to change in fuel properties, e.g. more moisture in fuel,
high ash content of coal.
M1.3 Boilers
A boiler is a vessel that uses heat liberated by combustion of a fuel to produce hot water
or steam. Boilers are pressure vessels, designed to withstand the steam pressures needed
in processes. They can be very dangerous if not correctly operated and maintained. An
economizer, air heater, or super heater fitted to a boiler will enable most of the heat
liberated from the fuel to be used. Super heaters increase the temperature of steam and
are necessary to render the steam suitable for use in steam turbines or steam engines.
Types of boilers
Boilers can be categorized broadly as follows:
• Water tube
• Smoke tube
• Fluidized bed boiler
Water tube boiler
Water tube boilers are designed for higher pressures and steam generation rates, normally
above 4 tons per hour. They are generally characterized by the following features:
• Mechanical stokers giving better stoking efficiency for solid fuels.
• Forced, induced and balanced draught systems helping to improve combustion
efficiency.
• Lower tolerance for water quality making water treatment plant necessary.
• Higher thermal efficiency levels are possible than for Lancashire boilers.
A water tube boiler is shown in Figure M.4.
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Figure M.4 Water tube boiler
Smoke tube boiler
Two examples of smoke tube boilers are the package boiler and the Lancashire boiler:
Package boiler
Package boilers (see Figure M.5) are shell type boilers with smoke tube design. They
achieve high heat transfer rates by both radiation and convection. Package boilers are
characterized by the following features:
• Small combustion space and high heat release rate, resulting in faster
evaporation.
• Large number of small diameter tubes leading to good convective heat transfer.
• Forced or induced draught systems, resulting in good combustion efficiency.
• Several ‘passes’ resulting in better overall heat transfer.
• Higher thermal efficiency than other boilers.
Lancashire boiler
Lancashire boilers are characterized by the following features:
•
•
•
•
Large thermal storage capacity permitting smooth handling of load fluctuations.
Able to tolerate poor feed water quality.
High thermal inertia (due to thermal storage) resulting in sluggish start up response.
Poor convective heat transfer contributing to low thermal efficiency.
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Figure M.5 Package boiler
Fluidized bed boiler
Developments in combustion technology for solid fuels such as coal, rice husks, etc.
have heralded the introduction of fluidized bed combustion (FBC) boilers, which can
burn a wide variety of fuels including low-grade coals effectively. A typical FBC system
consists of a cylindrical vessel with air ducts connected to the bottom of the vessel. The
fire bed—consisting of sand particles, coal ash or alumina—rests on a distribution plate
near the bottom and is ‘fluidized’ by the passage of combustion air upwards through
it. A start-up system, using gas or oil burners, heats the bed to a temperature at which
coal can be burned. Coal is then fed (pneumatically) into the bed where it is distributed
and burns rapidly. The heat liberated by combustion is transferred to water tubes,
some of which may be immersed in the bed, to generate hot water or steam. Ash is
removed continuously to maintain a constant bed depth. Thermal efficiencies in excess
of 80 per cent can be expected of FBC boilers.
Types of FBC boilers
FBC technology is, at present, divided into two distinct spheres:
• atmospheric FBC boilers; and
• pressurized FBC boilers.
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There are two types of atmospheric FBC boilers: bubbling fluidized bed (BFB) boilers
and circulating fluidized bed boilers.
Pressurized FBC boilers were mainly designed to operate gas turbines. Research work
into this technology is under way all over the world. In developing countries, BFB
technology has been developed and commercialized successfully, as it meets present
industrial requirements.
FBC technology and CP
It should be borne in mind that going in for these advanced technology boilers not
only means saving on operating costs, it also means helping to save the environment.
The environmental aspects of production of steam and power are an inseparable part
of the energy scene and, today, production still relies predominantly on the burning of
fossil fuels. The penalty for this is to load the life-giving environment—our air, water
and soil—with pollutants such as dust particles, oxides of carbon, nitrogen and sulphur
and other substances which are dangerous to human beings.
FBC technology has been developed to cater for a variety of requirements all over the
world. In the United Kingdom it was developed for British coals with high sulphur
content. These could be burned successfully with low pollution when limestone was
added to the bed to absorb the sulphur during combustion. Adding the limestone
avoided the use of very extensive and costly filtering/washing system for the flue gases.
In India, FBC technology was developed to burn bituminous Indian coal with low
calorific value and high ash content but containing little or no sulphur. It was not
therefore necessary to add limestone.
Another important advantage of FBC systems is that low combustion temperatures—
in the region of 700–900 °C—lead to the formation of relatively little NOX. Nitrogen
oxides include dangerous gases that affect the human respiratory tract and form acids
when they mix with humidity in air.
Performance evaluation of boilers
The efficiency of a boiler depends on several aspects of construction, operation and
maintenance. The temperature of a boiler with optimum operation and maintenance
depends on its construction—above all on the number of passes (i.e. the number of
times the gas flows through the boiler, see Figure M.6).
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Figure M.6 Boiler design affects performance
3 pass boiler
4 pass boiler
Heat balance
The combustion process in a boiler can be described in the form of an energy flow
diagram (see Figure M.7). This shows graphically how the input energy from the fuel
is transformed into the various useful energy flows and into heat and energy loss flows.
The thickness of the arrows indicates the amount of energy contained in the respective
flows.
stack gas
stack
gas
losses
Figure M.7 Boiler energy flow diagram
stoichiom.
excess air
unburnt
steam output
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ash, and unburnt
parts of fuel in ash
blow down
convection
and radiation
fuel input
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Essentially, a heat balance is an attempt to balance the total energy entering a boiler
against that leaving it in different forms. The following example (Figure M.8) illustrates
the different losses occurring when generating steam.
Figure M.8 Example of losses in steam generation
12.7% heat loss due to dry flue gas
8.1% heat loss due to steam in flue gas
100% fuel
BOILER
1.7% heat loss due to moisture in fuel
0.3% heat loss due to moisture in air
2.4% heat loss due to unburnts in residue
1.0% heat loss due to radiation and other unnacounted loss
73.8% heat in steam
The energy losses can be divided into avoidable and unavoidable losses. The aim of CP
must be to reduce the avoidable losses, i.e. to improve energy efficiency. The following
losses can be avoided or reduced:
• Stack gas losses:
° Excess air
(reduce to the necessary minimum which depends on burner technology,
operation (i.e. control) and maintenance).
° Stack gas temperature
(reduce by optimizing maintenance (cleaning); load; better burner and boiler
technology).
• Losses as un-burned fuel in stack and ash
(optimize operation and maintenance; better burner technology).
• Blow down losses
(treat fresh water; recycle condensate).
• Losses with condensate
(recover the largest possible amount of condensate).
• Losses by convection and radiation
(better boiler insulation).
The methodology for assessment of boiler efficiency and losses is given below.
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Evaporation ratio
The evaporation ratio is the quantity of steam generated per unit of fuel consumed (see
energy use snapshot, right).
Boiler efficiency
Thermal efficiency of a boiler is defined as the percentage of (heat) energy input that
is effectively useful in the generated steam. As shown below, there are two ways of
calculating this.
Indirect method
(a) coal fired boiler
producing saturated
steam at a pressure of
10 bar, evaporation
ratio = 6
For (a):
1 kg of coal can generate
6 kg of steam
For (b):
1 kg of oil can generate
13 kg of steam
a. Direct method
Parameters to be monitored for the calculation:
•
•
•
•
•
Typical evaporation
ratio for:
(b) oil fired boiler
producing saturated
steam at a pressure of
10 bar, evaporation
ratio = 13
Boiler efficiency calculation
Direct method
CP-EE
spotlight
Quantity of steam generated per hour (Q).
Quantity of fuel used per hour (q).
The working pressure and superheat temperature (if any).
Temperature of feed water.
Type of fuel and gross calorific value (GCV) of the fuel.
Boiler efficiency (η) =
Q x (H – h)
q x GCV
(where H = Enthalpy of steam, h = Enthalpy of feed water)
(examples follow …)
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Example 1
•
Type of boiler:
Coal fired
•
Quantity of steam generated:
8 TPH
•
Steam pressure:
10 kg/cm2
•
Steam temperature:
180 °C
•
Quantity of coal consumed:
1.8 TPH
•
Feed water temperature:
85 °C
•
GCV of coal:
4 000 kcal/kg
•
Enthalpy of steam at 10 kg/cm2 pressure:
665 kcal/kg
•
Enthalpy of feed water:
85 kcal/kg
Boiler efficiency (η) =
8 x 1 000 x (665 – 85) x 100
= 64.4%
1.8 x 1 000 x 4 000
Example 2
•
Type of boiler:
Furnace, oil fired
•
Quantity of steam generated:
35 TPH
•
Steam pressure:
20 kg/cm2
•
Steam temperature:
300 °C
•
Quantity of F.O. consumed:
2.9 TPH
•
Feed water temperature:
95 °C
•
GCV of F.O.:
10 200 kcal/kg
•
Enthalpy of steam at 20 kg/cm2 pressure and 300 °C:
723.5 kcal/kg
•
Enthalpy of feed water:
95 kcal/kg
Boiler efficiency (η) =
35 x 1 000 x (723.5 – 95) x 100
= 74.4%
2.9 x 1 000 x 10 200
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b. Indirect method
In this method thermal efficiency is found by subtracting the percentages of all
the heat losses from 100. The following parameters have to be known for the
calculation:
•
•
•
•
•
•
•
Ultimate analysis of fuel (H2, O2, S, C, moisture content, ash content).
Percentage of oxygen or CO2 in the flue gas.
Flue gas temperature, in °C (Tf).
Ambient temperature, in °C (Ta), and humidity of air, in kg/kg of dry air.
GCV of fuel, in kcal/kg.
Percentage combustible in ash (in case of solid fuels).
GCV of ash, in kcal/kg (in case of solid fuels).
O2 x 100
Excess air supplied (EA) =
21 – O2
⇒ Theoretical Air Requirement (TAR)
=
(11 x C) + { 34.5 x (H2 – (O2 /8)) } + 4.32 x S)
100
kg/kg fuel
⇒ Actual mass of air supplied/ kg of fuel (AAS)
=
1 + (EA/100)
x Theoretical Air
i. Percentage heat loss due to dry flue gas:
=
k x ( Tf – Ta )
% CO2
Where k (Seigert const.)
=
=
=
0.65 for coal
0.56 for oil
0.40 for NG
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ii. Percentage heat loss due to evaporation of water formed due to H2 in fuel:
=
9 x H2 x { 584 + 0.45(Tf – Ta ) }
GCV of fuel
Where H2 = the percentage of H2 in fuel
iii. Percentage heat loss due to evaporation of moisture present in fuel:
=
M { 584 + 0.45(Tf – Ta ) }
GCV of fuel
Where M = the percentage of moisture in fuel
iv. Percentage heat loss due to moisture present in air:
=
AAS x Humidity x 0.45 x (Tf – Ta ) x 100
GCV of fuel
v. Percentage heat loss due to combustibles in ash:
Ash x (100 – Comb. in Ash) x GCV of Ash x 100
=
GCV of fuel
vi. Percentage heat loss due to radiation and other unaccounted loss:
Actual radiation and convection losses are difficult to assess because of the
specific emissivity of various surfaces, their inclination and air flow pattern, etc.
Loss may be estimated appropriately depending on the surface condition.
Boiler efficiency (h) = 100 – (i + ii + iii + iv + v + vi )
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Example 3
•
Type of boiler:
Oil fired
•
Ultimate analysis of oil:
C
H2
S
O2
•
GCV of oil:
10 200 kcal/kg
•
Percentage of oxygen:
7%
•
Percentage of CO2:
11%
•
Flue gas temperature (Tf ):
220 °C
•
Ambient temperature (Ta ):
27 °C
•
Humidity of air:
0.018 kg/kg of d.a.
⇒ Excess air supplied (EA)
= 84%
= 12%
= 3%
= 1%
= 50%
⇒ Theoretical air requirement (TAR)
= 13.46 kg/kg of fuel
⇒ Actual mass of air supplied (AAS)
= 20.19 kg/kg of fuel
i.
Heat loss due to dry flue gas = 9.1%
ii.
Heat loss due to evaporation of water formed due to H2 in fuel = 7.1%
iii. Heat loss due to moisture present in air = 0.30%
iv. Heat loss due to radiation and other unaccounted loss = 2.0%
Boiler efficiency (η) = 81.5%
Boiler feed water treatment
Water treatment and conditioning are important for boilers. Treating the water helps
to prevent formation of scale on heat transfer surfaces. Control of total dissolved solids
and alkalinity inhibits corrosion and deposits on superheater tubes, turbine blades, etc.
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The water treatment processes are selected on the basis of the quality of available raw
water and boiler requirements. Boiler feed water treatment can be either internal or
external, or both. Internal treatment involves dosing of chemicals (sodium carbonate,
sodium phosphate, etc.) that help in the precipitation and coagulation of precipitated
scale-forming compounds (carbonate hardness) and help them settle in the boiler
drum. Hydrazine is also used internally to reduce dissolved oxygen in high pressure
boilers. External treatment may use a cold- or hot-lime process as pre-treatment,
followed by a base-exchange or demineralization process for further treatment.
At very low pressure, straight forward softening is still used. Sometimes a cation
exchanger, regenerated with sodium chloride, is also used. Demineralization is the only
process used for high pressures. At intermediate pressures, the removal of carbonates
(and if necessary of silica) is combined with softening by various methods. The main
processes used comprise:
• Cold lime process for removing carbonates, followed by softening.
• Hot lime and magnesia process for condensate removal, followed by softening.
• Removal of carbonates by carboxyl cation exchanger, followed by softening and
physical elimination of carbon dioxide.
All these processes must be followed by physical (deaeration) and/or chemical removal
of oxygen and conditioning treatment.
In most processes, steam condensate is collected from all indirect heating systems.
There is a danger of corrosion products (e.g. iron picked up from the equipment, steel
piping, copper oxides etc.); dissolved salts from condenser leaks; or accidental
pollution from black liquor heaters/evaporators; etc. becoming mixed with
condensate. Treatment of condensate, together with boiler water treatment, is
therefore important given the purity standards demanded for modern boilers.
Condensate treatment may consist of one or a combination of the following:
• Filtration through finely divided (fibrous or granular) materials such as cellulose
fibre filters, diatoms (which in addition to their filling properties have a specific
adsorbent effect for water only).
• De-ionization through cation/anion beds.
• Filtration through magnetic filters.
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Tables M.8 and M.9 give the recommended feed water quality and boiler water limits
for low-, medium- and high-pressure boilers:
Table M.8: Recommended feed water limits
Factor
Up to 20 ata
21–40 ata
41–60 ata
Total iron (max), ppm
0.05
0.02
0.01
Total copper (max), ppm
0.01
0.01
0.01
1.0
0.3
0.1
0.02
0.02
0.01
-
-
0.02–0.04
8.8–9.2
8.8–9.2
8.2–9.2
1.0
0.5
-
Total silica (max), ppm
Oxygen (max), ppm
Hydrazine residual, ppm
pH at 25 °C
Hardness
Table M.9: Recommended boiler water limits
Factor
Up to 20 ata
21–40 ata
41–60 ata
Total dissolved solids (TDS)
3 000–3 500
1 500–2 000
500–750
500
200
150
1000
400
300
20–40
20–40
15–25
10–10.5
10–10.5
9.8–10.2
25
15
10
Total iron dissolved solids, ppm
Specific electrical conductivity
at 25 °C (mho)
Phosphate residual, ppm
pH at 25 °C
Silica (max), ppm
Blow down
The water fed into the boiler contains dissolved materials and, as the water is
evaporated into steam, these are left to concentrate in the boiler in either a dissolved
or suspended state. Above a certain level of concentration, these solids encourage
foaming and cause carry over of water into the steam, leading to scale formation inside
the boiler. This can cause localized overheating which may result in tube failure, etc.
It is therefore necessary to control the level of concentration of solids. This is achieved
by the process of ‘blowing down’, where a certain volume of water is blown off and is
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automatically replaced by feed water, thus maintaining the optimum level of total
dissolved solids (TDS) in the water. Blow down is necessary to protect the surfaces of
the heat exchanger in the boiler. It is important to recognize that blow down can, if
incorrectly carried out, be a significant source of heat loss.
This problem calls for careful monitoring and supervision of the water conditions in all
boilers, particularly modern, shell-type packaged units which are even more vulnerable
than earlier types because of their small water capacity and limited steam space in
relation to their output.
Table M.10 shows the maximum TDS concentration permissible in various types of
boilers.
Table M.10: Permissible TDS concentrations in boilers
1
Lancashire
2
Smoke and water tube boilers (12 kg/cm2 )
3
H.P. Water tube boiler with superheater, etc.
4
Package and economic boilers
10 000 ppm
5 000 ppm
3 000–3 500 ppm
3 000 ppm
Further to the above, manufacturers' guidelines must also be consulted. The following
formula gives the quantity of blow down required:
Blow down (%) =
Feed water x % make up
(Permissible TDS in boiler – Feed water TDS)
If the maximum permissible limit of TDS is 3 000 ppm (as in a package boiler),
percentage make up water is 10 per cent and TDS in feed water is 300 ppm, then the
percentage blow down is given as:
=
300 x 10
= 1.11%
3 000 – 300
If the boiler evaporation rate is 3 000 kg/hr then required blow down rate is:
=
3 000 x 1.110
= 33 kg/hr
100
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M1.4 Thermic fluid heaters
Like boilers, thermic fluid heaters (TFH) or fired heaters (FH) are units designed to
transfer heat from combustion to a 'working' or 'thermic' fluid. However, a TFH or FH
is not necessarily a pressure vessel and the working fluid—typically a petroleum-based
oil—does not change from its fluid state.
The units operate in a closed loop with the thermic fluid picking up heat energy at one
end of the loop and then transferring it to process equipment by indirect transfer via
heat exchangers.
TFHs and FHs are used for high-temperature heat transfer applications (270–300 °C).
They have advantages over boilers for applications requiring such temperatures: they
avoid the need for high-pressure steam and the related complexities such as water
treatment, pressure vessel regulations, etc.
Inputs to TFH and FH include:
• Heat from fuel
• Combustion air
• Motive power to auxiliaries (e.g. thermic fluid circulating pump, draught fans,
fuel-handling equipment, etc.)
The useful heat output is the heat transferred by the thermic fluid. Other outputs
include:
• Flue gases
• Solid waste from fuel combustion
• Unburned fuel in flue gases
In recent times, TFHs have found wide application in indirect process heating.
Employing petroleum-based fluids as the heat transfer medium, they provide
constantly maintainable temperatures for the user equipment. The combustion system
comprises a fixed grate with mechanical draught arrangements.
Modern oil fired TFHs are of double-oil, three-pass construction and are fitted with
modulated pressure jet systems. The heat carrying thermic fluid is heated (in the
heater), circulated through the user equipment where it transfers heat for the process
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via a heat exchanger, and then returned to the heater. At the user end, the flow of
thermic fluid is controlled by a pneumatically operated valve, controlled by the
operating temperature. The heater operates on low or high fire, depending on the
temperature of the returning oil which varies with system load.
The advantages of these heaters are:
• Closed cycle operation with minimum losses compared to steam boilers.
• Non-pressurized system operation, even for temperatures of around 250 °C,
against 40 kg/cm2 of steam pressure required in similar steam systems.
• Automatic control settings, offering operational flexibility.
• Good thermal efficiency, as losses due to blow down, condensate drain and flash
steam do not exist in TFH systems.
The overall economics of a TFH depend on the specific application and reference basis.
Coal fired TFHs with a thermal efficiency range of 55–65 per cent compare favourably
with most boilers. Incorporation of heat recovery devices in the flue gas path further
enhances thermal efficiency levels.
TFH efficiency
The efficiency of a heater is defined as the ratio of heat output to heat input.
Mathematically, this can be expressed as follows:
Heater efficiency =
=
Where:
MTH =
CTH =
mf
=
TS
=
TR
=
GCV =
Heat output
Heat input
MTH x CTH x (TS – TR )
m f x GCV
x 100
mass flow rate of thermic fluid, kg/hr
specific heat of thermic fluid, kcal/kg °C
quantity of fuel consumed, kg/hr
forward temperature of thermic fluid, °C
temperature of returning fluid, °C
gross calorific value of fuel, kcal/kg
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M1.5 Steam distribution and utilization
M1.5.1 Steam traps
Steam generated by boilers is used in equipment and processes where it gives up its heat
and condenses back to water (condensate). Efficient removal of the condensate from
systems is one of the most important aspects of energy conservation. Removing
condensate efficiently helps to minimize energy consumption and maximize productivity.
Functions of steam traps
Steam traps have three important functions. They:
• discharge condensate as soon as it is formed;
• prevent steam from escaping; and
• discharge air and other non-condensable gases.
Types of steam traps
Table M.11 shows different types of steam traps and their principles of operation.
Table M.11: Types of steam traps
Group
Principle of operation
Subgroup
Mechanical trap
Difference in density between
steam and condensate
Bucket type
• open bucket
• inverted bucket, with/without lever
• float type
• float with lever
• free float
Thermodynamic trap
Difference in thermodynamic
properties of steam and
condensate
Disc type
Orifice type
Thermostatic trap
Difference in temperature
between steam and
condensate
Bimetallic type
Metal expansion type
Importance of steam trapping for energy efficiency
With ever-increasing energy prices, improvement in steam trapping is a more
significant factor than ever in the field of steam applications. True energy efficiency can
only be achieved when: a) selection; b) installation; and c) maintenance of steam traps
are adequate for the purpose of the installation.
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Factors affecting steam trap selection
Guidelines for steam trap selection are shown in Table M.12. Factors affecting their
selection are:
•
•
•
•
•
•
•
•
Maximum and minimum working pressure
Maximum and minimum pressure differentials
Maximum working temperature
Quantity of condensate to be discharged
Size
Connection type
Type of steam trap
Equipment to which trap is fitted
Table M.12: Guidelines for steam trap selection
Application
Feature
Suitable trap
Steam mains
• Open to atmosphere, small
capacity
• Frequent change in pressure
• Low pressure–high pressure
Thermodynamic type
•
•
•
•
•
• Large capacity
• Variation in pressure and
temperature is undesirable
• Efficiency of the equipment
is a problem
Mechanical trap, bucket,
inverted bucket, float
• Reliability with no
over-heating
Thermodynamic and
bimetallic
Equipment
Reboiler
Heater
Dryer
Heat exchanger etc.
• Tracer line
• Instrumentation
Steam trap maintenance
The purpose of steam trap maintenance is to maintain steam traps in optimum
condition to ensure efficient operation of the steam-using equipment in the plant. The
first step in troubleshooting is to observe the operation of the steam trap for symptoms
of failure. Steam trap failures can be classified into four groups as follows:
•
•
•
•
Blockage
Steam blowing
Steam leakage
Insufficient discharge
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Steam loss through malfunctioning of steam trap
If a disc trap is blowing steam at a pressure of 5 kg/cm2, the annual steam loss is 168 tons.
Based on a unit price for steam of, say, US$20/ton, the annual monetary loss is around
US$3 360. A failed steam trap therefore causes great loss of steam and of distilled water,
wasting both money and resources. The following are therefore important:
• Periodic inspection of steam traps
• Replacement of failed steam traps with new ones
OPEN FILE
Trap capacity
(condensate,
kg/hr)
Type of discharge
(continuous/
semi-continuous/
intermittent)
Location ref.
(plant dept./
block)
Trap size
Trap type
Serial no.
Trap ref. no.
Worksheet: Technical specifications of steam traps
Trap type:
Trip float trap; plan float trap;
open top bucket trap;
inverted bucket trap;
balanced pressure thermostatic
trap; liquid expansion
thermostatic trap; bimetal
thermostatic trap; impulse
thermodynamic trap; pilot
operated thermodynamic trap;
labyrinth thermodynamic trap;
orifice plate thermodynamic
trap; ogden pump.
Application:
Steam mainlines; equipment;
trace line; etc.
Functional status:
Good; leaking; blowing steam;
shutdown; blockage; bypassed.
Remarks
Status of trap
fittings
Diagnosis of
situation
Functional
status of trap
OPEN FILE
Application
of trap
Trap location
Trap pressure
(kg/cm2)
Trap size
Trap type
Trap ref. no.
Serial no.
Worksheet: Steam trap audit
Diagnosis:
Replace with free float; replace
with disc type; dismantle and
clean; incorrect trap selection.
Location:
Plant ref.; block ref.;
department ref.
Status of fittings
OK/not OK, for: sight glass;
bypass valve; filter.
Remarks
Estimate of steam loss,
suggestions, etc.
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M1.5.2 Steam leakage
Leakage from steam lines not only wastes heat, it also causes pressure drop in the lines.
The quantity of steam leaked depends on the size of the leak and on steam pressure.
If visibly evident steam leakage is observed, it must be stopped. Table M.13 gives an
indication of steam losses at different steam pressures and leak diameters.
Table M.13: Steam loss vs. leak diameter
Section
no.
Diameter
of leak
(mm)
Annual steam loss
at 3.5 kg/cm2
tons
at 7 kg/cm2
US$
tons
US$
1
1.5
29.0
667
47.0
1 081
2
3.0
116.0
2 668
193.0
4 439
3
4.5
232.0
5 336
433.0
9 959
4
6.0
465.0
10 695
767.0
17 641
M1.5.3 Removal of air from steam installations
Air and other non-condensable gases such as oxygen and carbon dioxide are a natural
hazard in any steam-using plant. They can slow down the rate of steam distribution,
create cold spots on the heating surface, cause distortion and stressing of the plant and
can be the root cause of corrosion related problems. However, it is perhaps their overall
effect on heat transfer that is most important from the production point of view.
Some practical examples:
• The presence of air in a jacketed boiling pan increased cooking time from 12.5
minutes to 20 minutes. Sixty per cent air in the steam going to a unit heater
reduced output by as much as 30 per cent.
• Dry saturated steam at 40 psi will have a temperature of 287 °C. If there is 90 per
cent steam and 10 per cent air, the temperature will be only 280 °C. With 25 per
cent air the temperature would drop to 270 °C. In all of these cases the pressure
gauge would remain at 40 psi.
In relative terms, the thermal conductivity of air is 0.2 compared to 5 for water,
340 for iron and 2 620 for copper. Which means that a film of air only one
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1/1000 inch (0.025 mm) thick will offer the same resistance to heat flow as a wall
of copper 13 inches (32.5 cm) thick.
The removal of air is essential and can be carried out by either manual or
automatic venting. Manual air venting has the disadvantage of relying on the
human element (i.e. a staff member) knowing just when and how often the cock
should be opened. The best alternative is obviously an automatic air vent.
M1.5.4 Thermal insulation
The need for efficient thermal insulation has become more important as both
operating temperatures and energy costs have increased. The production, distribution
and use of steam require thermal insulation to ensure that process requirements are
satisfied. The first consideration is to ensure that steam generated at the boiler can be
delivered to the point of use at the correct temperature and pressure. To ensure that
energy loss remains within design tolerance it is essential to make the correct choice of
thermal insulation system.
Types and forms of insulation material
Thermal insulation materials can be divided into four types: granular, fibrous, cellular
and reflective. Typical thermal insulation materials for use in the 50–1 000 °C
temperature range are given in Table M.14.
Table M.14: Typical insulation materials for the 50–1 000 °C temperature range
Section
no.
Insulation
Type
Availability*
Density
(kg/m3)
Approx. limiting
temperature (°C)
150
450
abdef
10–150
550
abdeg
20–250
850
abc
200–260
850
a = slabs
Granular
abc
200
300
b = sections
Diatomaceous
Granular
abcj
250–500
1 000
c = plastics
7
Silica
Fibrous
def
50–150
1 000
d = loose-fill
8
Alumino silicate
Fibrous
defg
50–250
1 200
e = mattress
9
Alumino silicate
Granular
j
500–800
1 200
f = textile
10
Aluminium
Reflective
h
10–30
500
11
Stainless steel
Reflective
h
300–600
800
12
Vermiculite
Granular
abcdgj
50–500
1 100
1
Cellular glass
Cellular
ab
2
Glass fibre
Fibrous
3
Rockwool and
Slagwool
Fibrous
4
Calcium silicate
Granular
5
Magnesia
6
* Notes:
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g = sprayable
h = reflective
j = insulating bricks
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Economic thickness of insulation
The effectiveness of insulation follows a law of diminishing returns. Hence, there is a
definite economic limit to the amount of insulation that is justified. Beyond a certain
level, increased thickness is not viable in terms of cost as this cannot be recovered
through small heat savings. This limiting value is termed the economic thickness of
insulation (ETI). Firms have different fuel costs and boiler efficiencies and these factors
can be brought together to calculate ETI. In other words, for a given set of
circumstances, a certain thickness results in the lowest overall cost of insulation and
heat loss over a given period of time. Figure M.9 illustrates the principle of ETI.
Figure M.9 Determining ETI
I+H
cost
I
H
M
I
=
cost of insulation
H
=
cost of heat loss
I+H =
total cost
M
economic thickness
=
insulation thickness
Determining ETI requires attention to the following factors:
•
•
•
•
•
•
•
•
Fuel cost
Annual hours of operation
Heat content of fuel
Boiler efficiency
Operating surface temperature
Pipe diameter/thickness of surface
Estimated cost of insulation
Average exposure at ambient still air temperature
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Heat savings and application criteria
A variety of charts, graphs and references are available for heat loss calculation. As this
manual is intended for CP practitioners, the more complex procedures for working out
heat losses are not considered. Surface heat loss can be calculated with the help of the
simple equation for energy loss shown below. This can be used for surface
temperatures up to 200 °C. Factors such as wind velocity or conductivity of insulating
material have not been considered.
S =
10 + (Ts – Ta) / 20
x (Ts – Ta)
Where:
S = Surface heat loss (kcal/hr/m2)
Ts = Hot surface temperature (°C)
Ta = Ambient temperature (°C)
Total heat loss/hr (Hs) = S x A
Where A is the surface area in m2.
Based on the cost of heat energy, the value of heat loss in US$ can be worked
out as follows:
Equivalent fuel loss (Hf)(kg/yr) =
Hs x hours of operation per year
GCV x ηb
Annual heat loss in monetary terms ($) = Hf x Fuel cost (US$/kg)
Where:
GCV = Gross calorific value of fuel (kcal/kg)
ηb = Boiler efficiency (as %)
Example calculation follows …
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Example 4
Calculate the fuel savings when a steam pipe with a diameter of 100 mm, supplying steam at
10 kg/cm2 to equipment, and un-insulated over 100 m of its length, is properly insulated with
65 mm of insulating material.
Assumptions:
•
•
•
•
•
Boiler efficiency:
Fuel oil cost:
Surface temperature without insulation:
Surface temperature after insulation:
Ambient temperature:
80 %
US$300/ton
170 °C
65 °C
25 °C
Existing heat loss:
S = [10 + (Ts – Ta) / 20] x (Ts – Ta)
Ts = 170 °C
Ta = 25 °C
S = [10 + (170 – 25)/20] x (170 – 25)
= 2 500 kcal/hr m2
S1 = S = Existing heat loss (2 500 kcal/hr m2 )
Modified System:
After insulating with 65 mm of glass wool with aluminium cladding, the hot face temperature will
be 65 °C
Ts = 65 °C
Ta = 25 °C
Substituting these values:
S = [10 + (65 – 25) / 20] x (65 – 20)
= 480 kcal/hr m2
S2 = S = Existing heat loss (480 kcal/hr m2)
Table M.15 illustrates this further.
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Table M.15: Calculating fuel savings
Pipe dimension
=
100 mm φ
and 100 m length
Surface area (existing) (A1)
=
3.14 x 0.1 x 100
=
31.4 m2
=
3.14 x 0.23 x 100
=
72.2 m2
=
2 500 x 31.42
=
78 850 kcal/hr
=
480 x 72.2
=
34 656 kcal/hr
=
78 860 – 34 656
=
44 194 kcal/hr
No. of hours operation in a year
=
8 400
Total heat loss (kcal/y)
=
44 194 x 8 400
=
371 229 600
Calorific value of fuel oil
=
10 300 kcal/kg
Boiler efficiency
=
80 %
Price of fuel oil
=
US$300/ton
Yearly fuel oil savings
=
371 229 600/10 300 x 0.8
=
45 052.136 kg/year
=
45.052 x 300
=
US$13 515.64
Surface area after insulation (A2)
Total heat loss in existing system (S1 x A1)
Total heat loss in modified system (S2 x A2)
Reduction in heat loss
Monetary savings
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Table M.16 can be used as a guide for insulation schemes for steam and condensate
lines, and for hot surfaces.
Table M.16: Guide to insulation schemes
Temperature
Pipe diameter
25 mm
50 mm
75 mm
100 mm
150 mm
Flat
surfaces
Less than 100 °C
25 mm
25 mm
50 mm
50 mm
65 mm
50 mm
100–150 °C
25 mm
25 mm
50 mm
50 mm
65 mm
75 mm
150–200 °C
25 mm
40 mm
50 mm
65 mm
75 mm
90 mm
200–250 °C
25 mm
50 mm
50 mm
65 mm
75 mm
90 mm
250–300 °C
25 mm
50 mm
50 mm
75 mm
90 mm
100 mm
Thermal insulation can be justified by balancing the cost of different heat losses or heat savings
against the cost of insulation.
Cleaner Production – Energy Efficiency Manual
Existing
insulation
thickness (if any)
Existing surface
temperature
OPEN FILE
Existing outer
diameter
Equipment
reference
Location
Section no.
Worksheet: Insulation losses
page 146
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M1.5.5 Condensate recovery
Steam is used very extensively as a heating medium in various types of plants—efficient
use of steam is therefore the key to energy conservation. The heat energy contained in
steam consists of sensible heat and latent heat, the latter only being used in most types
of steam-using equipment. When steam gives off its latent heat, it condenses back to
water at the saturation point. The sensible heat contained in the condensate amounts
to as much as 20–30 per cent of the total heat of the steam (see Figure M.10).
Figure M.10 Total enthalpy of saturated steam at 10 kg/cm2
latent heat
481 kcal/kg
Total heat = sensible + latent heat
= 181 +
481
= 662 kcal/kg
sensible heat
181 kcal/kg
To maintain maximum efficiency of steam equipment, condensate forming in the
equipment should be discharged via steam traps as quickly as possible. In other words,
the higher the temperature of discharged condensate, the higher the efficiency of the
equipment, resulting in the most efficient use of steam.
In this case, the discharged condensate has the highest ‘quality’ of heat it can have, and
this heat can be used for other processes. In addition, the condensate itself can be used
as make-up water for the boiler. Figure M.11 shows the benefits of condensate recovery.
Figure M.11 Benefits of condensate recovery
total
losses
total
losses
fuel
input
fuel
input
steam
output
steam
consumer
steam
output
steam
consumer
discharged
condensate
fresh water
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recovered condensate
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Condensate recovery has numerous advantages, the most important of these are given
below:
A. Heat recovery
• Boiler fuel is saved.
• Boiler efficiency is improved.
B. Water recovery
• Water for industrial use is saved.
• Water treatment cost (and chemicals) are saved.
• Blow down is reduced.
C. Additional advantages
• Air pollution is lessened by reduction in fuel consumption in boiler.
• No steam trap operating noise.
• No screening of moisture caused by flashing of condensate discharged
through steam traps.
EVERY 6 °C INCREASE IN BOILER FEED WATER TEMPERATURE
CAN SAVE 1 PER CENT BOILER FUEL
Sizing the condensate return line
Table M.17 and Figure M.12 can be used to size the condensate return line, as
explained below.
Table M.17: Sizing the condensate return line
Pipe size (mm)
Maximum capacity – starting load (kg/hr)
15
160
20
370
25
700
32
1 500
40
2 300
50
4 500
65
8 000
80
14 000
100
29 000
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From Table M.17, it is now possible to determine size, as indicated in Figure M.12,
below.
Figure M.12 Example of condensate return line sizing
R-450 kg
R-250 kg
S-900 kg
S-500 kg
B
A
900 kg/hr
S = starting load/hr
C
1120 kg/hr
D
1620 kg/hr
E
2420 kg/hr
R-110 kg
R-400 kg
S-220 kg
S-800 kg
R = running load/hr
Table M.17 can now be used to determine the sizes as follows:
•
•
•
•
A to B carries 900 kg/hr—size required is therefore 32 mm.
B to C carries 1 120 kg/hr—size required is therefore 32 mm.
C to D carries 1 620 kg/hr—size required is therefore 40 mm.
D to E carries 2 420 kg/hr—size required is therefore 50 mm.
Lifting the condensate
The steam pressure at the steam trap does the lifting, but this may lead to back
pressure on the trap and, by doing so, reduce the pressure differential across the trap.
To avoid the problem of back pressure, there must always be sufficient steam pressure
at the trap to overcome the back pressure. Lifting condensate directly to the
condensate return line without considering the above facts has the followings
disadvantages.
• Back pressure in the equipment from which condensate is lifted.
• ‘Chattering’ in the equipment, resulting in leakages at joints.
• Reduced equipment output capacity, and hence an increase in energy
consumption.
• Effects on product quality, especially in paper/textile dryers, as condensate
accumulates.
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It is advisable to avoid lifting condensate because, even under the most favourable
conditions, lifting can be a hindrance to start-up because it causes back pressure which
slows down clearance of condensate at precisely the time this is least desirable. All of
this can be avoided by draining the condensate to a receiver by natural fall, and then
sending it to the boiler house by an independent pump.
Example 5
In a process house 3t/hr of steam at a pressure of 2.5 kg/cm2 are used indirectly in the equipment.
There is no condensate recovery system. The boiler feed water temperature is 25 °C.
Feed water temperature = 25 °C
Feed water temperature = 65 °C
Condensate
return = nil
Before adjustment
Condensate
return = 3 t/hr
After adjustment
Savings = US$37 830
The procedure for calculating the savings that can be achieved by condensate recovery
is illustrated in Figure M.13 on the following page.
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Figure M.13 Fuel savings from condensate recovery
hourly condensate recovered:
3 000 kg/hr
x hours per year:
8 400
= annual condensate recovered:
25 200 000 kg/yr
40 kcal/kg
x heat content increase,
feed water temperature = 40 °C
(25 °C to 65 °C)
= heat recovered:
1 008 x 106 kcal/yr
÷ boiler efficiency = 85%:
1.18
÷ boiler efficiency = 80%: ✓
1.25 ✓
÷ boiler efficiency = 75%:
1.33
÷ boiler efficiency = 70%:
1.43
= heat saved:
1 260 x 106 kcal/yr
Coal
÷ calorific value of fuel
Oil
kcal/kg
kcal/kg
kg/yr
kg/yr
=
kg/ton
÷
1 000
10 300
122 330
kcal/m3
m3/yr
kg/l
heavy
medium
light
= fuel saved
Gas
0.97
0.95
0.935
litres/yr
126 113
m3/yr
price/kl
US$ 300
price/m3
tons/yr
x
price/ton
= annual savings
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Factors to be considered in incorporating a condensate recovery system
• A high condensate temperature necessitates a review of the available net positive
suction head, to avoid vapour locking and cavitation problems of feed water
pumps. Table M.18 provides guidelines.
Table M.18: Feed water temperature vs. suction feed
Feed water temperature (°C)
Suction feed (m)
86
1.5
90
2.1
95
3.5
100
5.2
• In cases where increased feed water temperature gives rise to steaming problems,
as in economizers, some of the return condensate can be diverted for process
applications.
• Overflowing of condensate in collection tanks is a common occurrence. This
should be avoided by use of a simple control system with float switch.
• Thermal insulation is often ignored for condensate recovery. It is worthwhile
insulating condensate lines to save heat.
M1.5.6 Flash steam recovery
Flash steam is produced when condensate at a high pressure is released at a lower
pressure. The recovery of flash steam from high pressure condensate constitutes an
important area of heat saving.
The graph in Figure M.14 illustrates the percentage of flash steam generated under
different operating conditions.
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Figure M.14 Generation of flash steam
16
0 kg/cm2 gauge
14
pressure on traps gauge (kg/cm2 )
0.5 kg/cm2 gauge
12
1.0 kg/cm2 gauge
1.5 kg/cm2 gauge
10
2.0 kg/cm2 gauge
2.5 kg/cm2 gauge
8
6
4
2
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
kg flash per kg condensate (%)
The following example may prove helpful:
Example 6
Consider the case of a machine where 1 000 kg of condensate at 7 kg/cm2 is flashed to
atmospheric pressure.
From Figure M.14, flash quantity (kg/kg) from condensate is 14.0 per cent.
The flash steam generated per hour per 1 000 kg is therefore 140 kg/hr.
With an evaporation ratio (see Section M1.3) of 13 (i.e. 1 kg of oil burned in the boiler can
produce 13 kg of steam), the equivalent fuel oil saving (kg) by flash heat recovery is
140 ÷ 13 = 10.76 kg of oil per hour.
The annual fuel oil saving for 6 000 working hours would be:
= (10.76 x 6000) / 1000 = 64.6 t/year
Assuming a fuel oil price of US$300/ton, monetary savings would be:
= 64.6t x US$300
= US$19 385 /year
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Flash steam generated is recovered by incorporating a flash vessel. The guidelines in
Table M.19 illustrate some essentials of flash vessel design.
Table M.19: Guidelines for flash vessel design
The flash vessel should be designed so that there is a considerable
drop in velocity. This allows condensate to fall to the bottom and be
drained out by the steam trap.
The height of the vessel should be such that as little water as possible
is entrained along with the flash steam. A minimum height of 1 metre
and exit steam velocity of not more than 15 metres/second should be
aimed for.
In a flash steam recovery system—in the form of a small column—flashing vapours are
cooled by a spray. In this system, the vapours move up and lose their heat to the falling
water spray. Perforated baffles in the flow path help to provide intimate contact for
better heat transfer.
M1.6 Furnaces
The primary functions of an industrial furnace are to heat/melt/soak and generally treat
materials at given temperatures. Furnaces can be classified according to their method
of operation, their use and their method of utilizing fuel, as shown in Figure M.15.
M1.6.1 Types of furnace
Specific aspects of different types of furnaces are explained below and parameters of
various types are shown in Table M.20.
Forging furnace
Forging furnaces are used to preheat billets and ingots to forge temperature. The furnace
temperature is maintained at around 1 200 to 1 250 °C (depending on the carbon
content of the steel). Normally, large pieces are soaked for 4 to 6 hours in the furnace to
attain a uniform temperature throughout the material. Actual soaking times vary with the
type and thickness of the material. Bigger pieces, weighing between 1 and 2 tons, may
be reheated several times. Charging and discharging of the material is done manually
and this results in significant heat loss during the forging operation. Forging furnaces use
an open fireplace system with most of the heat being transmitted by radiation.
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Figure M.15: Classification of furnaces
Open fireplace furnace
According to
mode of
heat transfer
Heated through liquid
Forging
Periodical
Furnace
classification
According to
mode of
charging
Re-rolling
(batch/continuous pusher)
Pot
Continuous
Glass tank melting
(regenerative/recuperative
Recuperative
Mode of
heat reovery
Regenerative
Assessment of specific fuel consumption in this type of furnace is rather difficult
because it depends on the type of material and number of reheats required. On
average, the figure is between 0.65 to 0.85 tons of coal per ton of forging.
End fired (box type) furnace
The ‘end fired’ box type furnace is used for batch type re-rolling mills. It is preferred to
the pusher type furnace (see below) when there is a wider variety of size and weight
of ‘material’ to be heated. End fired box type furnaces are used, usually, to heat scrap,
small ingots and billets weighing from 2 to 20 kg, for re-rolling. Charging and
discharging is manual, and the final product is in the form of rods, strips, etc.
Re-rolling (batch) furnace
Re-rolling (batch) furnaces operate 8 to 10 hours per day with an average output of
1 to 1.5 t/hr. The charge is loaded before firing, and nearly 1.5 hours of heat-up time
is required to attain a temperature of 1 200 °C. The total cycle time can be broken
down into heat-up time and re-rolling time. During heat-up time the material is heated
to the required temperature and is then removed manually for re-rolling. After
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completing first re-rolling, which takes around 3.5 to 4 hours, the furnace is loaded
with fresh ‘material’, which takes only 30 minutes to heat-up for re-rolling.
Average output from these furnaces varies from 10 to 15 tons/day and the specific fuel
consumption varies from 180 to 280 kg of coal per ton of heated material. Specific coal
consumption varies with the weight of the material being heated for re-rolling and with
operating efficiency of the furnace.
Continuous pusher type furnace
Continuous pusher type furnaces have a distinct advantage over batch type furnaces.
Although the process flow diagram and operating cycles are the same as those of the
batch furnace, the cross-sectional area of the billet or ingot that can be fed into the
pusher furnace is 65 to 100 mm2 (45 to 90 kg weight/piece). These furnaces generally
operate 8 to 10 hours with an output of 20 to 25 tons per day; their normal rating is
around 4 to 6 tons/hour at peak load.
Since the length of a pusher furnace is generally between 13.7 and 15.25 metres, the
material itself can recover a part of the heat from flue gases as it moves down the
length of the furnace. Heat absorption by the material in the furnace is slow and steady
and uniform throughout the cross-section.
The material pushed into the furnace takes 2 to 2.5 hours to reach the soaking zone,
where the temperature is maintained at around 1 200 to 1 250 °C. After sufficient
soaking, which depends on cross-section, the material is removed manually for rerolling. Specific fuel consumption varies from 180 to 250 kg of coal per ton of heated
material. Inefficient furnace operation is one of the major reasons for wide variations in
specific fuel consumption.
Pot furnaces
Pot furnaces are usually used when the final product is small glassware, shells,
laboratory instruments, bangles, etc. or wherever a ‘batch’ is melted intermittently.
Coal is burned on a fixed grate with natural draught.
In pot furnaces the flue gas temperature just after the furnace is in the range of 1 200
to 1 250 °C. Specific fuel consumption is 1.2 to 1.5 tons of coal per ton of glass drawn.
This varies from unit to unit, depending on the type of product and coal quality.
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Table M.20: Furnace parameters
Furnace
Forging
(open
fireplace)
Re-rolling
Batch
Pot
Continuous
pusher
Glass tank melting
(regenerative or
recuperative)
Design parameters
Length (mm)
3 000
6 000
13 700/152 250
Width (mm)
1 850
2 000
1 800
Height (mm)
900
1 100 (front end)
1 050 (front end)
900 (rear end)
400 (rear end)
Average weight
of molten glass
200 kg per pot
Depends on the capacity
of the furnace
Grate width (mm)
900
900
900
Grate length (mm)
1 850
1 850
1 850
Furnace temperature (°C)
1 200–1 250
1 150–1 200
1 200–1 250
1 350–1 400
1 400–1 450
Flue gas temperature (°C)
1 100
700–750
550–600
1 200–1 250
200–350 (just after regeneration)
3–10
4–12
4–12
4–8(O2)
2–6 (O2)
0.6–0.8
0.18–0.28
0.18–0.25
1.2–1.5
0.55–1.0
Static producer
Operating parameters
CO2% in flue gas
Specific fuel consumption
Tons of coal/ton of
material heated
Glass furnace: a typical glass furnace consists of 10 to 12 pots, each with a capacity of
200 kg of molten glass. The furnace temperature is maintained at around 1 350 to
1 400 °C. Around 14 to 18 hours are needed for complete melting and refining of a
batch of glass. Drawing of molten glass from the pots requires another 6 to 8 hours.
In the glass tank regenerative furnace, batch charging and glass drawing is continuous.
Normally, the quantity of glass drawn ranges from 10 to 20 tons per day in such
furnaces. A tank furnace consists of a bath, the bottom and sides of which are usually
made of refractory blocks. Ports are provided for mixing of fuel and air above the
melting level.
The coal is not burned directly in the glass tank furnace. Instead, it is used as a raw
material to first generate product gas which, in turn, is cross-flow-fired to heat the tank
across the width of the furnace.
The mixed batch, comprising sand, limestone, soda ash and cullet, is shovelled into the
furnace manually. Melting of the glass in tanks occurs in the following stages:
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1. The batch is pushed into the furnace where it floats on the top of molten glass
and melts to a frothy state.
2. Temperature is held sufficiently high to remove gas bubbles and homogenize the
bath, refining the glass.
3. Glass then flows to the cooler working end for drawing at a carefully controlled
rate/temperature.
Molten glass is supplied from the working end to one or more operating units. The
forming of glassware may be carried out either by hand or by machine. The glassware
is then taken to an annealing furnace. Annealing avoids stresses being set up in the
glass by too rapid or uneven cooling, as this may increase its tendency to fracture.
Rejected articles, known as ‘cullet’, are recycled in the fresh batch.
M1.6.2 Fuel consumption and heat economy
For an industrial furnace, the term ‘efficiency’, when used in the true sense, refers to
the quantity of fuel expended to heat a unit weight of stock. While efficiency for boilers
ranges from 60 to 85 per cent, the efficiency of furnaces is sometimes as low as 5
per cent. One reason for the difference in efficiency between boilers and industrial
furnaces is in the final temperature of the material being heated. Gases can give up
heat to the charge only as long as they are hotter than the charge. Consequently, flue
gases leave industrial furnaces at a very high temperature. This factor is responsible for
low furnace efficiencies.
Examination of Figure M.16 will give a clear understanding of the distribution of heat
in a simple furnace.
Figure M.16 Flow of heat in a furnace
2
1
7
5
3
1
2
4
3
6
4
2
1 = stock
3 = hearth
5 = door
2 = ground and surroundings
4 = cracks and openings
6 = protruding stock
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Heat flow in a furnace
It is desirable for most of the heat liberated by the fuel to be imparted to the stock.
However, as shown in Figure M.16, some of the heat in a furnace passes into the
furnace walls and hearth, and some is lost to the surroundings by radiation and
convection from the outer surface of the walls or by conduction into the ground. Heat
is also radiated through cracks or other openings and furnace gases pass out around
the door, often burning in the open air and carrying off heat. Heat is also lost every
time the door is opened or can be dissipated if stock protrudes beyond the furnace
enclosure. Finally, most of the heat lost passes out along with the products of
combustion, either in the form of sensible heat or as incomplete combustion. Fuel
economy demands that the fraction of total heat that passes into the stock be as large
as possible and that all losses be minimized.
1.6.3 Factors affecting fuel economy
Complete combustion with minimum excess air
To achieve complete combustion of fuel with minimum excess air, a number of factors
(such as proper selection and maintenance of control, excess air monitoring, air
infiltration, pressure of combustion air) are to be considered. In addition to an
abnormal increase in stack losses, the ingress of too much excess air lowers flame
temperature, reducing furnace temperature and heating rate. If too little excess air is
used, combustion is incomplete and chimney gases will carry away unused fuel
potential in the form of unburned combustible gases such as carbon monoxide and
hydrogen, and unburned hydrocarbons which would otherwise have burned usefully
in the combustion chamber.
Proper heat distribution
Ideally, a furnace should be designed so that, in a given time, as much material as
possible is heated to as uniform a temperature as possible, with the minimum fuel firing
rate. To achieve this, the following points should be considered.
i) The flame should not touch the stock and should propagate clear of any solid
object. Any obstruction whatsoever de-atomizes the fuel particles, affecting
combustion and creating black smoke. If the flame touches the stock, the scale of
losses is greatly increased.
ii) Refractories are leached if the flames touch any part of the furnace, as the
products of incomplete combustion can react with some of the refractory
constituents at high flame temperatures.
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iii) The flames from burners in the combustion space should also remain clear of one
another. If flames interact, inefficient combustion will occur. This can be
controlled by staggering the burners on opposite walls.
iv) The flame has a tendency to travel freely in the combustion space just above the
material. In small reheating furnaces, the burner axis is never parallel to the
hearth but always at an upward angle. Every precaution should be taken to
ensure that the flame never impinges on the roof.
v) A larger burner produces a long flame which may be difficult to contain within the
furnace walls. More burners of less capacity give better distribution of heat in the
furnace, and also reduce scale losses while increasing furnace life, as shown in
Figure M.17.
vi) For uniform heating in smaller reheating furnaces it is advisable to maintain a long
flame with a golden yellow colour when firing furnace oil. The flame should not be
allowed to become so long that it enters the chimney and comes out at the top or
through doors, as occurs when excessive oil is fired. This operational practice is
sometimes employed to increase production rate, in reality it helps only marginally.
vii) It is also desirable to provide a combustion volume that is adequate to the heat
release rate.
Figure M.17 Heat distribution in furnaces
flame
flame
stock
flame
stock
flame
flame
incorrect
correct
incorrect
correct
Operating at the desired temperature
There is an optimum temperature for furnace operation for any given industrial heating
or melting operation. Table M.21 shows operating temperatures for different furnaces.
Operating at too high a temperature will not only mean unnecessary waste of fuel and
heat, it will also cause overheating of the stock, its spoilage or excessive oxidation and
decarburization, as well as over-stressing of refractories. To avoid this, provision should
be made for temperature control instruments.
In the ‘off’ condition, only the atomizing air enters the furnace, bringing its
temperature down rapidly so that when the oil firing process recommences, the
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Table M.21: Furnace operating temperatures
Slab reheating furnaces
1 200 °C
Rolling mill furnace
1 180 °C
Bar furnace for sheet mill
850 °C
Bogey type annealing furnace
659–750 °C
Bogey type roll annealing furnace
1 000 °C
Small forging furnace
1 150 °C
Rotary iron melting furnace
1 550 °C
Enamelling furnace
820–860 °C
amount of oil supplied to the furnace to raise the temperature is far greater than would
be necessary had the furnace been operated on ‘proportional control’.
Reducing heat losses from furnace openings
In oil fired furnaces, substantial heat losses occur through furnace openings. For every
large opening, heat loss may be calculated by multiplying black body radiation at
furnace temperature by the emissivity (usually 0.8 for furnace brick work) and the factor
for radiation through openings. Black body radiation losses and radiation factors can be
obtained directly from curves and nomograms such as those shown in Figure M.18.
Figure M.18 Using black body radiation to calculate heat loss
a) Black body radiation
b) Radiation through openings of various shapes
1.0
0.9
5 000
0.8
total radiation factor
black body radiation (kcal/cm2/hr)
6 000
4 000
3 000
2 000
0.7
0.6
0.5
0.4
0.3
0.2
1 000
D
2:1 rectangular opening
x
square opening
0.1
0
325
very long slot
round (cylindrical) opening
0
500
750
1 000
1 250
1 500
1 650
temperature (°C)
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0
0.2 0.4 0.6 0.8 1.0
ratio =
2
3
diameter or least width
thickness of wall
4
=
5
6
D
x
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Minimizing wall losses
In intermittent or continuous furnaces, heat losses generally account for around 30–40
per cent of the fuel input to the furnace. The appropriate choice of refractory and
insulation materials goes a long way towards achieving fairly high fuel savings in
industrial furnaces.
In industrial furnaces, fuel consumption can be substantially reduced by judicious
application of external insulation. Several materials with different combinations of heat
insulation and thermal inertia should be considered to minimize heat losses through
furnace walls. For intermittent furnaces, the use of insulating refractories of appropriate
quality and thickness can cut down heat storage capacity of walls and the time
required to bring the furnace to operating temperature by as much as 60–70 per cent.
Control of furnace draught
Ingress of uncontrolled free air must be prevented in any furnace. It is better to maintain
a slight excess pressure inside the furnace to avoid air infiltration. If negative pressures
exist in the furnace, air infiltration is liable to occur through the cracks and openings,
thereby affecting air/fuel ratio control. Neglecting furnace pressure could mean problems
of cold metal and non-uniform metal temperatures, which could affect subsequent
operations such as forging and rolling and could result in increased fuel consumption.
Furnace loading
One of the most vital factors affecting efficiency is loading. There is a particular loading
at which the furnace will operate at maximum thermal efficiency. If the furnace is
under-loaded, a smaller fraction of the available heat in the working chamber will be
taken up by the load and the efficiency will accordingly be low. The best method of
loading is generally obtained by trial, noting the weight of material put in at each
charge, the time it takes to reach a given temperature and the amount of fuel used.
Care should be taken to load a furnace at the rate associated with optimum efficiency,
although it must be realized that limitations in achieving this are sometimes imposed
by availability of work or other factors beyond operational control.
Placing of stock
The load should be placed on the furnace hearth in such a way that:
• It receives maximum radiation from the hot surfaces of the heating chamber and
the flames.
• The hot gases circulate efficiently around the heat receiving surfaces.
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• There is adequate spacing between the billets. Overlapping of materials results in
non-uniformity of temperature and should be avoided.
Stock should not be placed in the following positions:
• In the direct path of the burners or where the flame is likely to impinge.
• In an area which is likely to cause a blockage or restriction of the flue system of
the furnace.
• Close to any door or opening where cold spots are likely to develop.
Load residence time
In the interest of fuel economy and work quality, the materials comprising the load
should remain in the furnace for the minimum stipulated time to obtain the required
physical and metallurgical requirements. When the materials attain these properties
they should be removed from the furnace to avoid damage and fuel wastage.
M1.7 Waste heat recovery
M1.7.1 What is waste heat?
Boilers, kilns, ovens and furnaces generate large quantities of hot flue gases. If some of
this waste heat can be recovered, a considerable amount of primary fuel can be saved.
Not all of the energy lost in waste gases can be recovered. However, much of the heat
can be recovered and losses can be minimized by adopting the measures described
below.
M1.7.2 Sources of waste heat
When considering the potential for heat recovery, it is useful to note all of the
possibilities, and to grade the waste heat in terms of potential value, as shown in
Table M.22.
M1.7.3 Waste heat recovery from flue gases
After identifying sources of waste heat and possible uses, the next step is to select
suitable heat recovery systems and equipment to recover and use the heat.
Considerable fuel savings can be made by preheating combustion air. The heat saving
devices used for this purpose are the recuperator and the regenerator.
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Table M.22: Sources of waste heat
Section no.
Source
Quality
1
Heat in flue gases
The higher the temperature, the greater
the potential value for heat recovery.
2
Heat in vapour streams
As above but when condensed, latent
heat also recoverable.
3
Convective and radiant heat lost
from exterior of equipment
Low grade—if collected may be used for
space heating or air preheats.
4
Heat losses in cooling water
Low grade—useful gains if heat is
exchanged with incoming fresh water.
5
Heat losses in providing chilled
water or in the disposal of chilled
water
a) High grade if it can be utilized to
reduce demand for refrigeration.
b) Low grade if refrigeration unit used as
a form of heat pump.
6
Heat stored in products leaving the
process
Quality depends on temperature.
7
Heat in gaseous and liquid effluents
leaving process
Poor if heavily contaminated, thus
requiring alloy heat exchanger.
Recuperator
In a recuperator, heat exchange takes place between the flue gases and the air via
metallic or ceramic walls. Ducts or tubes carry the combustion air that is to be preheated, the other side of the exchanger carries the waste heat stream.
Ceramic recuperators are bulky and offer considerable resistance to transfer of heat
because of low conductivity; they also have a greater tendency to leak. Metallic
recuperators are less prone to leaks and thermal expansion and can be controlled.
Metallic recuperators are easier to maintain and install and involve less initial cost. For
the reasons outlined above, ceramic recuperators are not widely used. Some of the
common flow arrangements used in recuperators are shown in Figures M.19–M.21.
Metallic recuperators can be of three basic types, depending on the method of heat
transfer: i.e. radiation, convection, or combined convection and radiation.
Ceramic recuperator
Ceramic tube recuperators have been developed to overcome the temperature limit of
metallic recuperators (around 1 000 °C on the gas side). The materials used for ceramic
recuperators allow gas side temperatures of up to 1 300 °C and temperatures up to
850 °C on the preheated air side.
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Figure M.19 Recuperator
Figure M.20 Metallic radiation recuperator
Waste gas
Inlet air from
atmosphere
Insulation and
metal covering
Hot air to process
Exhaust gas
from process
Centre tube plate
Outside ducting
Preheated air
Tube plate
Cold air
inlet
Flue gas
The classification of recuperators based on their type of flow is given in Figure M.21.
Figure M.21 Classification of recuperators
a) Parallel flow recuperator
b) Cross flow recuperator
Both gases flow in the same direction
Gases flow at right angles to one another
Cold
input
fluid
Cooled waste gase
Cooled waste gases
Hot input fluid
Hot waste gas
Hot input fluid
Cold input fluid
Hot waste gas
c) Counter flow recuperator
Both gases flow in opposite direction
Hot waste gas
Hot input fluid
Cold input fluid
Cooled waste gase
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Radiation/convective hybrid recuperator
For maximum effectiveness of heat transfer, combinations of radiation and convective
designs are used, with the high-temperature radiation recuperator always first (see
Figure M.22). These are more expensive than simple metallic radiation recuperators,
but are less bulky.
Figure M.22 Radiation/convective hybrid recuperator
Cooled waste gas
Radiation
section
Convection
section
Hot air to process
Cold
air
inlet
Table M.23 summarizes the applications and advantages of the different types of
recuperator.
Table M.23: Furnace operating temperatures
Energy performance
Applications
Advantages
Radiation type recuperators
(30% efficiency)
Steel industry (furnaces, soaking pots,
chimneys and flues)
Can handle very dirty,
abrasive dust-laden gases
Convective recuperative system
(50–60% efficiency)
Low temperature applications (food,
textiles, brewing, pulp and paper)
Advanced designs
(self-recuperative burners, up to
70% efficiency)
High temperature applications (flue
gases from kilns, metal processing
and glass melting furnaces, etc.)
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Regenerator
In a regenerator (see Figure M.23), the flue gases and the air to be heated are passed
alternately through a heat-storing medium, thereby resulting in transfer of heat. Long
periods of reversal result in lower average temperature of preheat and consequently
reduce fuel economy.
Figure M.23 Regenerator
Gas
Chimney
Air regenerator
Gas regenerator
Air
Economizer
For a boiler system, an economizer (see Figure M.24) can be provided utilizing the flue
gas heat to pre-heat the boiler feed water. In an air pre-heater, the waste heat is used
to heat combustion air. In both cases, there is a corresponding reduction in the fuel
requirements of the boiler.
Figure M.24 Economizer
Flue gas outlet
Water inlet
Economizer cells
Water outlet
Flue gas intlet
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M1.7.4 Plate type heat exchangers
The cost of heat exchange surfaces is a major cost factor when temperature differences
are not large. One way of solving this problem is the plate type heat exchanger (see
Figure M.25), which consists of a series of separate parallel plates forming narrow flow
passages. Plates are separated by gaskets and the hot stream passes in parallel through
alternating plates while the counter-flow of liquid to be heated passes in parallel
between the hot plates. Plates are corrugated to improve heat transfer. Plate type
exchangers are summarized in Table M.24.
Figure M.25 Plate type heat exchanger
Table M.24: Characteristics of plate heat exchangers
Type of plate heat exchanger
Construction
Comments
Plain form,
cooling fluids flow
A series of separate,
parallel plates form
narrow passages through
which the heating and
cooling fluids flow
Temperature range 25–170 °C,
(special design up to 200 °C). Easy to
clean, replace parts and increase
capacity. Liquid-to-liquid systems
recover up to 80–90% of available
heat. Widely used in brewing, dairy
and chemical process industries; in
regenerative recovery, and as a
condenser for product heating.
M1.7.5 Heat pipe
The heat pipe is a device that uses an evaporation-condensation cycle to transfer up to
100 times more thermal energy than copper, the best known conductor. It is a simple
device that absorbs and transfers thermal energy with no moving parts, and hence
minimum maintenance.
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Figure M.26 Heat pipe
Vapourized fluid condenses
and gives up heat
Liquid
Heat in
Vapour
Heat out
Metal mesh wick acts
as return path for
liquid working fluid
Heat evaporates
working fluid
The heat pipe comprises three main elements: a sealed container; a working fluid; and
a capillary wick structure, (see Figure M.26).
The container encloses the working fluid which, because the container is sealed, is at
its own pressure equilibrium. Thermal energy applied to the outer surface of the heat
pipe causes the working fluid near the surface to evaporate instantaneously, picking up
the latent heat of evaporation. This region of the heat pipe is the ‘evaporator’. The
vapour, which now has a higher pressure, moves to the other, cooler, end of the pipe
where it condenses, giving up the latent heat of evaporation as it does so. This region
of the pipe forms the ‘condenser’. The capillary wick—fabricated as an integral part of
the inner surface of the evacuated container tube—provides a return path for the
working fluid, allowing the cycle to restart.
Performance and advantages
The heat pipe heat exchanger (HPHE) is a lightweight compact heat recovery system.
It requires no input power for its operation and is free from cooling water and
lubrication systems. It also lowers fan horsepower requirement and increases overall
thermal efficiency of the system. HPHE recovery systems are capable of operating at
315 °C with 60–80 per cent heat recovery capability.
Typical application
Heat pipes are used in following industrial applications:
a) Process to space heating: The HPHE transfers thermal energy from the process
exhaust for use in building heating. Preheated air can be blended if required. The
requirement for additional heating equipment to deliver heated make up air is
drastically reduced or eliminated.
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b) Process to process: Heat pipe heat exchangers recover waste thermal energy from
the process exhaust and transfer this energy to the incoming process air. The
warmed incoming air can be used for the same process or other processes, thus
reducing process energy consumption.
c) HVAC Applications:
Cooling: a HPHE can precool building make up air in summer, thus reducing the total
tons of refrigeration as well as providing savings in operation of the cooling system.
Heating: the process described above is reversed during winter to preheat the make
up air.
Other industrial applications are:
•
•
•
•
•
•
•
•
•
Preheating of steam boiler combustion air.
Recovery of waste heat from furnaces.
Reheating of fresh air for hot air driers.
Recovery of waste heat from catalytic deodorizing equipment.
Recovery of furnace waste heat as heat source for other ovens.
Pre cooling of cold air.
Heat source for air conditioning.
Cooling of closed rooms with outside air.
Preheating of boiler feed water by waste heat recovery from flue gases in the heat
pipe economizers.
M1.7.6 Heat pumps
Heat pumps have the ability to upgrade heat from a source to a value more than twice
that of the energy required to operate the device. The potential for application of heat
pumps is growing and numerous industries have benefited by recovering low grade
waste heat, upgrading it and using it in main process streams.
Basically, a heat pump system comprises a compressor, condenser, expansion valve,
evaporator and a working fluid. It extracts heat from air, water or a process liquid
stream and supplies it, via an exchanger, at a higher temperature to a liquid or gas
stream. The heat pump employs the same basic principle as the common refrigerator,
and the cycle can also be used for cooling. The principle of operation is presented in
Figure M.27.
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Figure M.27 Heat pump—operating principle
Working fluid expansion
valve converts hot liquid to
low-pressure cold
liquid/vapour mixture
Heat energy extracted from waste
air is absorbed by the working fluid
in cooling coil
Heat absorbed by cold liquid
converts it to cold gas
Heat pump compresses cold gas to
high pressure hot gas
Heating coil adding heat to supply
air from hot gas condensing to hot
liquid under pressure
Heat pump applications (see Table M.25) are most promising when both the heating
and cooling capabilities can be used in combination. One example of this is a plastics
factory where chilled water from a heat is used to cool injection-moulding machines
whilst the heat output from the heat pump is used to provide factory or office heating.
Other examples of heat pump use include product drying, maintaining dry
atmosphere for storage and drying compressed air.
Table M.25: Heat pump applications and advantages
Energy performance
Applications
Advantages
Heat drawn from warm
exhaust can achieve COPs
of 5 or 6
Timber and wood
products; ceramics and
pottery; brick
manufacture and food
products
Reclaims heat at ambient
temperatures
Maximum operating
temperature can vary (40 °C,
60 °C or 100 °C depending on
choice of working fluid)
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M1.7.7 Heat (thermal) wheels
A variation on the basic methods of heat transfer is the rotary regenerator which uses
a cylinder rotating through waste gas and air streams (see Figure M.28). The ‘heat’ or
‘energy recovery’ wheel is a rotary gas heat regenerator that transfers heat from an
exhaust stream to cooler incoming gases. Its main area of application is when there is
a requirement for heat exchange between large masses of air with small temperature
differences. Heating and ventilation systems and recovery of heat from dryer exhaust
air are typical applications.
Figure M.28 The heat wheel
Supply air ducting
Rotating regenerator
Cold outside air
Warmed air to room
Cooled exhaust air
Warm room exhaust air
Direction of rotation
Exhaust air ducting
The wheel rotor—which consists of sectors of either steel mesh or inorganic fibrous
materials with a hygroscopic coating of glass ceramic—offers a large surface area to the
air or gas flows. The wheel absorbs heat from the hot exhaust gases and, as the rotor
revolves, transfers heat to the cooler incoming stream. The speed of rotation of the
rotor is usually about 10–20 revolutions per minute. A purge bleed between the clean
and dirty gas streams is incorporated to avoid contamination between the two streams.
Efficiencies of over 80 per cent are claimed for this device, but they vary depending on
the individual case (see Table M.26).
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Table M.26: The rotary wheel—applications and advantages
Energy performance
Applications
Advantages
Waste heat recovery:
65% or more of available heat
can be recovered
Cost-effective in
furnaces, ovens, printing
machinery, paper drying
and HVAC systems,
metal melting furnaces
Reclaims heat at ambient
temperatures
More compact, lighter, and higher
temperatures than comparable
recuperators
Lower gas exit temperatures are
therefore possible
M1.7.8 Self recuperative burner
In self-recuperative burners (see Figure M.29), the recuperator is an integral part of the
burner, saving costs and making it easier to retrofit to existing furnaces. Recuperator
burners are operated in pairs. While one burner is used to burn the fuel, the other
burner uses a porous ceramic bed to store heat. After a short period (minutes), the
process is reversed and heat stored in the ceramic bed is used to preheat the
combustion air.
Figure M.29 Self-recuperative burner
Waste gas outlet
Natural gas
Hot combustion
products
Combustion products
Combustion air
Hot
combustion
products
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M1.7.9 Waste heat recovery system for diesel generation sets
Exhaust gases from diesel generation (DG) sets are at high temperatures, ranging from
330 to 550 °C depending on the type or make of the engine and the fuel used. The
energy in the hot exhaust gases can be recovered usefully for steam, hot water, thermic
fluid heating and hot air generation (see Figure M.30).
Figure M.30: Hot water generation from DG exhaust
To exhaust
DG exhaust
350 °C
Thermic fluid in
Thermic fluid out
Thermic fluid pump
Typical process
hot water bath
M1.7.10 Applicability of heat exchanger systems
Heat exchangers exist for nearly every possible combination of heat source and use.
Table M.27 indicates how common types are generally applied.
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Table M.27: matrix of waste heat recovery devices and applications
Heat recovery
device
Temperature
range
Typical sources
Typical uses
Radiation recuperator
High
Incinerator or
boiler exhaust
Combustion air preheat
Convective recuperator
Medium
to high
Soaking or annealing
ovens, melting furnaces,
afterburners, gas
incinerators, radiant tube
burners, reheat furnaces
Combustion air preheat
Furnace regenerator
High
Glass and steel melting
furnaces
Combustion air preheat
Metallic heat wheel
Low to
medium
Curing and drying ovens,
boiler exhaust
Combustion air preheat,
space preheat
Ceramic heat wheel
Medium
to high
Large boiler or Incinerator
exhaust
Combustion air preheat
Finned tube regenerator
Low to
medium
Boiler exhaust
Boiler make up
water preheat
Shell and tube
regenerator
Low
Refrigeration condensates,
waste steam, distillation
condensates, coolants from
engines, air compressors,
bearings and lubricants
Liquid flows requiring
heating
Heat pipes
Low to
medium
Drying, curing and baking
ovens, waste steam, air
dryers, kilns and
reverberatory furnaces
Combustion air preheat,
boiler make up water preheat,
steam generation, domestic
hot water, space heat
Waste heat boiler
Medium to
high
Exhaust from gas turbines,
reciprocating engines,
incinerators and furnaces
Hot water or steam
generation
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Electrical systems
M1.8 Electricity management systems
M1.8.1 Electricity cost
Electricity costs for an enterprise consist of the following:
• Energy costs in the true sense (i.e. the cost of the kWh consumed).
• Costs of power demand (i.e. the cost of the peak electrical power requirement).
Energy costs can be reduced primarily by reducing electricity consumption (i.e. by
increasing energy efficiency), while power demand costs can be reduced by other
means—by reducing peaks of power consumption. Reducing power peaks can lead to
reduced consumption of electrical energy, but this is not an inevitable consequence.
Both increasing energy efficiency and reducing maximum electrical load must be
preceded by analysis of the processes that consume electrical energy. Very precise
knowledge of the processes is necessary to define measures to increase energy
efficiency in an effective and economical way, and to be able cut off consumers during
(short) periods of time to reduce peak load.
M1.8.2 Electric load management and maximum demand control
Introduction
If processes are not to be interrupted, electricity demand and supply must match
instantaneously. This requires reserve capacity to meet peak demands, and the costs of
meeting such demands—normally referred to as demand charges—are relatively high.
Managing electricity supply costs therefore requires integrated load management that
includes control of maximum demand and scheduling of its occurrence during peak/offpeak periods. Figure M.31 gives an example of the load curve for an enterprise. How
such a curve can be plotted is explained in Example 7 (page 178).
Basically, there are two ways to reduce maximum load for an enterprise (see
Figure M.32):
a) cut off the peaks; or
b) reduce base load.
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Figure M.31 A load curve
120
110
100
electricity use (kW)
90
80
70
60
50
40
30
20
10
0
00:00
02:00
04:00
06:00
08:00
10:00
12:00
14:00
16:00
18:00
20:00
22:00
time of day
Figure M.32 Reducing the load
120
peak load limitation
by measure (control)
110
100
reduced peak by measures
electricity use (kW)
90
80
70
60
50
40
peak load limitation
by reducing base load
30
20
10
0
00:00
02:00
04:00
06:00
08:00
10:00
12:00
14:00
16:00
18:00
20:00
22:00
time of day
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Controlling peak load by load management
Load prediction
Before considering methods of load prediction, some terms used in connection with
power supply need to be defined.
• Connected load—the nameplate rating (in kW or kVA) of the apparatus installed
at a consumer’s premises.
• Maximum demand—the maximum load that a consumer uses at any time.
• Demand factor—the ratio of maximum demand to connected load.
Example 7: Plotting a load curve
A consumer has ten 40 kW electrical loads connected at a facility; the connected load is thus
400 kW. However, the maximum number of loads actually used may be only nine—all ten may
never be used at once. Maximum demand is, therefore, 9 x 40 = 360 kW, and the demand factor
of this load is 360/400 or 90 per cent. A consumer of electrical power will naturally use power as
and when required and the load will therefore be constantly changing. As shown in Figure M.31,
this can be represented by a graph known as a load curve that shows the consumer's load
demand against time at different hours of the day.
When plotted for the 24 hours of a single day, the graph is known as a daily load curve. If it is
potted for a whole year, it is known as an annual load curve. This type of curve is useful in
predicting annual energy requirements, occurrence of loads at different hours and days in the year,
and for power supply economics. As load is variable, it will only be at maximum for a certain time
and will be lower at other times. The average load during a 24 hour period, or other period
considered for the load curve, will be less than the maximum load. The ratio of average load to
maximum load is called the load factor.
Load factor =
Average load
Maximum load
The load factor can also be defined as the ratio of energy consumed during a given period to the
energy that would have been used if maximum demand had been maintained throughout that
period.
Energy consumed during 24 hours
Load factor =
Maximum recorded load x 24 hours
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CP-EE
spotlight
Example 8: Calculating the average load
A residential consumer has ten 60 W lamps connected. Demand is as follows:
From 12 midnight to 5 a.m.:
From 5 a.m. to 6 p.m.:
From 6 p.m. to 7 p.m.:
From 7 p.m. to 9 p.m.:
From 9 p.m. to 12 midnight:
60 W
Nil
480 W
540 W
240 W
The average load, maximum load, load factor and electrical energy consumption during the day
can be calculated as follows:
i)
Maximum load is 540 W for 2 hours of the day, from 7 p.m. to 9 p.m.
ii) Energy consumption during 24 hours of the day is:
(5 x 60) + (480 x 1) + (540 x 2) + (240 x 3)
= 2 580 Wh
= 2.58 kWh/day
iii) % Load factor
=
Energy consumed during 24 hours x 100%
540 W x 24 hours
=
2580 x 100%
540 W x 24 hours
=
iv) Average Load
=
In a wire drawing unit,
three items of preliminary
wire drawing equipment
with loads of 50 HP per
wire were used
simultaneously during the
day shift. The
simultaneous maximum
demand for the overall
plant was about 450 kVA.
Operation of the three
items of wire drawing
equipment was
rescheduled to the 3rd
shift, when only a few
items of equipment were
operating. With
rescheduling, maximum
demand was reduced by
150 kVA, resulting in
savings of about
US$2 000 per year in
demand charges, as well
as flattening the load
curve considerably.
19.9%
2 580 kWh
24 hours
=
107.5 kW
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Rescheduling of loads
To minimize simultaneous maximum demands, running of units or carrying out of
operations that demand a lot of power can be rescheduled to different shifts. To do
this, it is advisable to prepare an operation flow chart and a process run chart.
Analysing these charts and adopting an integrated approach make it possible to
reschedule the operations and to run heavy equipment in such a way as to reduce
maximum demand and improve the load factor (see Figure M.33).
Figure M.33 Analysing peak load
120
110
100
electricity use (kW)
90
80
70
60
50
What contributes to the peaks?
Can the processes be shifted?
40
30
20
What happens here?
Do machines etc. run unnecessarily?
10
0
00:00
02:00
04:00
06:00
08:00
10:00
12:00
14:00
16:00
18:00
20:00
22:00
time of day
CP-EE
spotlight
Staggering of motor loads
When running large capacity motors, staggering of running is advisable, with a suitable
time delay (as permitted by the process) to minimize simultaneous maximum demand
(depending on load conditions) from these motors.
Storage of products
It is possible to reduce maximum demand by using electricity during off-peak periods
to build up storage of products/materials or chilled/hot water. Additional machinery and
storage costs are often justified by reduction in demand charges—for example, storing
chilled water at night to provide day time air conditioning; adding raw material/clinker
grinding facilities in cement plants; storing chipped wood in paper plants; etc. Off-peak
operation can also help to save energy because of more favourable conditions—for
example, lower ambient temperatures can reduce needs for cooling, etc.
Cleaner Production – Energy Efficiency Manual
In a pipe manufacturing
plant, three automatic
moulds with motor loads
of 70 kW were operated
simultaneously. The
operators were instructed
to incorporate a time
delay into the running of
these motors. This
resulted in a reduction of
50 kVA in maximum
demand, and savings of
around US$660 per year
in demand charges.
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However, a cost-benefit analysis has to be made for solutions like those outlined above;
they will then be considered for implementation if economically viable.
Shedding of non-essential loads
When maximum demand tends towards a preset limit, it can be restricted by
temporary shedding of some non-essential loads. It is possible to install direct demandmonitoring systems that switch off non-essential loads when a preset level of demand
is reached. Simpler systems give an alarm, and the loads are shed manually.
Sophisticated microprocessor controlled systems are available that provide a wide
variety of control options. These provide the following options:
•
•
•
•
•
•
Accurate prediction of demand.
Graphic display of present load, available load, demand limit.
Visual and audible alarm.
Automatic load shedding in a predetermined sequence.
Automatic restoration of load.
Recording and metering.
Simple load management systems with manual load shedding are employed in some
industries.
Operation of diesel generation sets
When diesel generation (DG) sets are used to supplement the power supplied by the
electricity utilities, it is advisable to connect the DG sets for the duration of peak
demand periods. This considerably reduces load demand on the utility supply, and
minimizes demand charges.
If the DG sets generate at the same voltage as the supply authority, it is advisable to
run the systems in parallel. This results in considerable reduction in maximum demand
if the diversity of loads in the plant is used to share the peak load on the system.
If the heat produced by the engine (cooling water, exhaust gases) can be used,
additional profit is gained. In this case, operation of the DG as a cogeneration plant
could be considered.
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M1.8.3 Power factor improvement
Power factor basics
For purely resistive electrical loads, voltage (V), current (I) and resistance (R) have a
simple linear relationship expressed by the equation:
V = I x R
and for power (kW):
kW = V x I
In practice, however, purely resistive loads are a rarity, and the alternating current
supplied by electricity utilities (usually at 50 or 60 Hz) is almost always applied to
inductive loads (e.g. motors, transformers, induction furnaces, etc.). Inductive loads
require an electromagnetic field to operate and they therefore draw additional
‘reactive’ power (kVAR) to provide for this magnetizing component. Figure M.34
illustrates this situation—KW, the active power (shaft power or true power required)
and the reactive power (kVAR) are 90° out of phase, with reactive power (kVAR) lagging
the active power (kW). (As will be seen below, the ‘lag’ has significance for power factor
correction). The vector sum of kW and kVAR, is the apparent power, termed kVA. It is
kVA that represents the actual electrical load on the distribution system.
Figure M.34
kW
kVA
φ
kVAR
From Figure M.34, it can be seen that if reactive power is zero (i.e. no inductive kVAR
needed) kVA and kW will be equal but if the inductive kVAR requirement increases, the
kVA required to provide the same active power (kW) also increases. In other words, the
ratio of kW to kVA varies with the reactive power drawn. This ratio is called the power
factor. It is always equal to or less than unity.
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If all loads to which electricity utilities supply power had unity power factor, maximum
power would be transferred for the same distribution system capacity. In reality,
however, loads have power factors ranging from 0.2 to 0.9, and the lower power
factors place additional stress on the electrical distribution network. Low power factors
result largely from part load operation of motors and other equipment.
The effects of low power factors are:
•
•
•
•
•
Maximum kVA demand for a given kW load increases.
Line I2R losses increase considerably.
On-line voltage drops are higher.
Gross power consumption increases.
Distribution system (transformers, cables) bear an increased load.
Example 9: The effects of power factors
The table below shows the kVA requirements (demand) and current drawn at various power factors
by an industrial installation with a 150 kW load requirement.
kVA and current vs power factor (P.F.) for a 150 kW load
Load (kW)
P.F.
kVA drawn
Line current at 415 volts
150
0.60
250
347.8
150
0.70
214.3
298.1
150
0.80
187.5
260.9
150
0.90
166.67
231.9
150
Unity
150
208.7
Notes:
kW = kVA x P.F.
Line current = kVA ÷ √3 x voltage in kilovolts
It can be seen that, for the same kilowatt load, line current varies with power factor from
208.7 amps to as much as 347.8 amps, i.e. an increase of 66.7 per cent, with a
corresponding increase in load on the distribution system, and increase in distribution losses
to 278 per cent.
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Electricity suppliers impose penalties on users with low power factors, as these place a
heavy burden on distribution system capacity. There is therefore good reason to
compensate for reactive power.
Compensating for reactive power
A very effective and well-established method of improving power factor is to
incorporate capacitors. The capacitor is a device which stores energy in an electric field
and has the characteristic of drawing leading reactive power. In other words, current
in a capacitor leads voltage by 90° and the reactive kVAR is therefore in exact
opposition to inductive kVAR. It therefore tends to nullify the reactive power drawn, as
illustrated below in Figure M.35.
By connecting an appropriately sized capacitor across an inductive load, the effects of
a low power factor can be nullified.
Figure M.35 Balancing inductive and capacitive kVAR
balancing
capacitive
kVAR
kW = kVA
kW
kW
kVAR
without capacitor
kVAR
with capacitor
The reactive power demand at plant level can be reduced to a considerable extent by
using capacitor banks. Maximum demand can also be reduced by maintaining
optimum power factor at the main incoming bus.
High-voltage capacitor banks (suitable for voltages of 11 kV and above) are available
with microprocessor-based control systems. These systems switch the capacitor banks
on and off in accordance with load power factors.
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Example 10: Using capacitor banks to reduce power demand
•
•
•
•
•
Type of industry:
Total connected load:
Maximum demand:
Instantaneous P.F.:
Existing capacitor banks:
Food processing (pulverizing and grinding)
247.5 HP
103 kVA
0.85
4 x 20 kVAR
It was proposed to provide additional capacitors to improve the instantaneous power factor of high
unit loads.
Additional requirement of capacitors to
improve the instantaneous P.F. to 0.96
=
30 kVAR
Expected reduction in M.D.
=
12 kVA
Savings in demand charges at
US$3.0 per kVA M.D.
=
US$432
Estimated cost of installation
=
US$200
Simple payback period
=
Less than 0.5 years
Selecting capacitors
The figures given in Table M.28 are factors to be multiplied with the input power (kW)
to give the kVAR of capacitance required to change from one power factor to another.
Table M.28: Factors for capacitive kVAR
Original P.F.
Desired P.F.
1.0
0.95
0.90
0.85
0.80
0.55
1.518
1.189
1.034
0.899
0.763
0.60
1.333
1.004
0.849
0.714
0.583
0.65
1.169
0.840
0.685
0.549
0.419
0.70
1.020
0.691
0.536
0.400
0.270
0.75
0.882
0.553
0.398
0.262
0.132
0.80
0.750
0.421
0.266
0.130
0.85
0.484
0.291
0.136
0.90
0.328
0.155
0.95
0.620
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Example 11: Sizing the capacitor
The power factor for a 30 kW load is to be improved from 0.80 to 0.95.
This is obtained as follows:
Size of the capacitor
=
=
=
kW x multiplication factor
30 x 0.421
12.63 (or) 13 kVAR
Knowing the existing power factor, Table M.28 can be used to find the factor to raise
the power factor from its present value to a desired value.
For induction motors with different ratings and speeds, to improve power factor to
0.95 and above, the rating of the capacitor (in kVAR) for direct connection to induction
motor or a particular speed can be selected from Table M.29.
Table M.29:
Recommended capacitor rating for direct connection to induction
motors (in kVAR) (to improve power factor to 0.95 or more)
Motor speed (rpm)
Motor H.P.
3000
1500
1000
750
600
2.5
1.0
1.0
1.5
2.0
2.5
500
2.5
5.0
2.0
2.0
2.5
3.5
4.0
4.0
7.5
2.5
3.0
3.5
4.5
5.0
5.5
10.0
3.0
4.0
4.5
5.5
6.0
6.5
12.5
3.5
4.5
5.0
6.5
7.5
8.0
15.0
4.0
5.0
6.0
7.5
8.5
9.0
17.5
4.5
5.5
6.5
8.0
10.0
10.5
20.0
5.0
6.0
7.0
9.0
11.0
12.0
22.5
5.5
6.5
8.0
10.0
12.0
13.0
25.0
6.0
7.0
9.0
10.5
13.0
14.5
The rated voltage of the capacitor should be equal to the rated voltage of the system,
provided voltage variation is not more than 10 per cent. If the voltage variation is
more, say 15 percent, the capacitor rating must be higher, so that the maximum
permissible voltage of the capacitor bank is equal to or slightly higher than the
maximum system voltage. For such capacitors, the actual capacity at normal operating
conditions is given by:
Actual kVAR = Rated kVAR x
Operating voltage
Rated voltage
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Location of capacitors
Location of capacitors is an important factor. For the benefit of electricity boards,
connection of capacitors on the H.T. side is good enough. Although the cost of H.T.
capacitor per kVAR is low, the cost of the associated switchgear is quite high. Apart
from this, plant operations may be affected significantly from time to time because of
capacitor problems. There is also a possibility that all of the reactive current will flow
through the L.T. cable and transformers, leading to higher losses.
Alternatively, the capacitors can be connected on the L.T. side of the main substation,
although this does not help in reducing distribution losses. The best solution for
location of capacitors is to connect at load centres, e.g. connecting capacitors directly
to motors or group of motors at motor control centres. Operation of capacitors
without load is not a significant problem as the plant will be operated under leading
P.F. and voltage may rise to a small extent. Automatic P.F. correction control is also
available and is required only in special cases.
Correction of P.F. at motors has a number of advantages, since induction motors are
the main source of reactive currents in every industrial plant. Advantages include:
absence of additional switchgear; no separate control of capacitor required for
switching on and off; reduced effect of motor inrush; etc.
On the other hand, there are common problems associated with direct connection:
excess voltage due to self-excitation after switching off; and large transient torque after
fast reclosure. Generally, compensation at motor terminals is restricted to correcting
the no load current so that the P.F. at full load is corrected to 0.9–0.95 and, at partial
load, the P.F. is near to unity. Table M.30 gives typical values of capacitors to be
connected directly with induction motors.
Other types of load requiring use of capacitors include induction furnaces, induction
heaters, arc welding transformers, etc. The capacitors are normally supplied with
control gear for use with induction furnaces and induction heating applications, as
frequency is often different and, essentially, load characteristics change during melting
or heating cycles. P.F.s for arc furnaces vary widely over the melting cycle, changing
from 0.7 at the start to 0.9 at the end of the cycle.
Power factors for arc welders and resistance welders are corrected by connecting
capacitors across the primary winding of the transformers, without which their P.F.
would be around 0.35. The recommended capacitor ratings for various sizes of welding
transformers are given in Table M.31.
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Table M.30: Capacitors for induction motors (kVAR)
Motor speed (rpm)
Motor H.P.
3 000
1 500
1 000
750
5
2
2
2.5
3.5
10
3
4
4.5
5.5
15
4
5
6
7.5
25
6
7
9
10.5
50
11
12.5
16
18
100
21
23
26
28
150
31
33
36
38
200
40
42
45
47
250
48
50
53
55
Table M.31: Recommended capacitor ratings for welding transformers
Capacitor rating (kVAR)
Welding transformer rating (kVA)
Single-phase
9
4
12
6
18
8
24
12
30
18
Three-phase
57
16.5
95
30
128
45
160
60
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M1.9 Electric drives and electrical end-use equipment
M1.9.1 Electric motors
More than 85 per cent of electricity consumed by industry passes through electric
motors. However, motors constitute only an interim stage in energy conversion, as the
motor shaft power is used to drive equipment of which the efficiency is also vital if
overall electricity consumption is to be optimized. The simple example in Figure M.36
illustrates the point.
Figure M.36 Comparison of efficiency effects
Case 1: Existing
Delivery = 23.375 kW
Output = 42.5 kW
Input = 50 kW
Pump
Motor
Efficiency = 85%
Efficiency = 55%
Case 2: Motor replaced for efficiency
Delivery = 23.375 kW
Output = 42.5 kW
Input = 48.30 kW
Pump
Motor
Efficiency = 88%
Efficiency = 55%
Case 3: Pump replaced for efficiency
Delivery = 23.375 kW
Output = 33.39 kW
Input = 37.95 kW
Motor
Efficiency = 88%
Pump
Efficiency = 70%
Electric motors are intrinsically highly efficient and the margins for savings from their
replacement or improvement are low in comparison to those for driven equipment,
where much higher savings can be obtained.
Squirrel cage induction motors, the mainstay in industry, have operational efficiency of
85–95 per cent, depending on the HP rating, rpm, age, and extent of loading.
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Given the increasing costs of electricity, replacement of old and rewound motors by
energy-efficient ones can be advantageous, especially if the motors run for long hours.
The margin for kW savings is given by the following equation:
% kW savings =
(New efficiency – Old efficiency) x 100
New efficiency
It should also to be appreciated that, at today’s electricity costs, the running cost of a
motor is 8 to 10 times its investment cost. It is therefore highly advisable to select
higher efficiency motors in the first place.
Recent technologies that improve motor operation and energy efficiency are:
• Electronic soft starters, to optimize inrush starting currents and increase life.
• Variable speed drives, to optimize energy needs in cases where capacity control is
needed.
Recommended good operational practices are:
• Operating motor with correct, balanced voltage, giving 3–5 per cent savings and
longer life.
• Proper lubrication, to maintain efficiency and reduce failures.
• Proper ventilation and heat evacuation, to reduce failures and enhance life.
• Power factor correction at motor terminals is recommended, especially in cases
where H.P. ratings are over 50 and where running periods are long.
• Regular check on motor loading (amps) is recommended, to monitor variations.
• Alignment, bearings, cable terminations, lubrication and V-belt tension (in case of
belt drives) are points that warrant regular attention for safe/smooth operation.
Variable speed drives
By design, common squirrel cage induction motors run at nearly constant speed.
Conversely, pumps, fans, compressors, conveyors, rolling mills, crushers, extruders and
many other motor applications are subject to load variation and require capacity
control. Some traditional forms of control, such as throttling, valves, damper
operations, bypass operations, have very poor energy efficiency.
A variety of variable speed drive alternatives are available to help improve energy
efficiency, offering a much more elegant method of speed and capacity control for
driven machines. Table M.32 presents a menu of advantages and disadvantages.
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Table M.32: Speed control alternatives for AC induction motors
VSD Type
Advantages
Disadvantages
Electro-mechanical control methods
Variable pulley sheaves
Low cost
Low efficiency
High maintenance costs
Gears
Low cost
Low efficiency
High maintenance costs
Chains
Low cost
Low efficiency
High maintenance costs
Friction drives
Low cost
Low efficiency
High maintenance costs
Multi-speed motors
Operation at 2 or 4 fixed speeds
Stepped speed control, lower
efficiency than single-speed motors
Eddy-current drives
Max. speed ratio 10:1
Simple, relatively low cost,
stepless speed control
Low efficiency at less than 50%
rated speed
Fluid coupling drives
Max. speed ratio 5:1
Simple, relatively low cost,
stepless speed control
Low efficiency at less than 50%
rated speed
Solid-state electronic control methods
Voltage control
<25 kW, 20–100%
Simple, low cost
Harmonics, low torque, low efficiency,
limited speed range
Voltage source inverter
(VSI) <750 kW, 100:1
Good efficiency, simple
circuit design
No regenerative braking, problems at
low speed (< 10%)
Current source inverter
(CSI) <25 kW, 10–150%
Regenerative braking, simple
circuit design
Poor power factor, poor performance
at low speed
Pulse width modulation
(PWM) < 750 kW, 100:1
Good power factor,
low distortion
No regenerative braking, slightly less
efficient than VSI
Example follows …
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Example 12: Comparison before and after a variable speed drive installation
The table below shows measurements before and after installation of a PWM inverter variable
speed drive on a 45-kW, 4-pole blower fan motor in a yarn quenching application in a textile mill,
indicating potential savings.
Data before and after variable speed drive installation
Discharge pressure
Damper opening (%)
Input power (kW)
With damper control
3.6
30
34.83
4.8
40
37.71
5.4
60
38.33
6.8
70
42.52
With speed control
3.0
100
15.40
3.4
100
17.44
4.8
100
21.71
5.6
100
26.32
6.8
100
32.25
Note:
Savings high at part loads, i.e. at low damper openings
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OPEN FILE
Frequency (Hz)
Speed (rpm)
Power factor
(P.F.)
Full load current
(Amps)
Voltage (kV)
Power input
(kW)
Type
Motor drive ref.
Serial no.
Worksheet: Electric motor rated specifications
Efficienmcy (%)
Part 2 Technical modules
Note: ‘Type’ could include: induction motor, direct current (DC); synchronous motor
OPEN FILE
% motor
loading
(w.r.t. rated)
Actual output
power (kW)
Actual input
power (kW)
Power factor
(P.F.)
Current
(Amps)
Voltage (kV)
Actual measured electrical parameters
Rated power
(kW)
Motor drive ref.
Serial no.
Worksheet: Electric motor load survey
Notes:
Actual output power = Actual measured motor input power x Rated motor efficiency factor
% motor loading = Actual measured output power
Rated motor power
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M1.9.2 Transformers
A transformer is a device that transfers energy from one AC system to another.
Transformers receive energy at one voltage and deliver it at another. This allows
electrical energy to be generated at relatively low voltages; to be transmitted at high
voltages and low currents (reducing line losses); and to be used at safe voltages.
Transformers consist of two or more coils that are electrically insulated, but
magnetically linked. The primary coil is connected to the power source; the secondary
coil connects to the load. The turns ratio is the ratio of the number of turns in the
primary coil to the number of turns on the secondary. The secondary voltage is equal
to the primary voltage multiplied by the turns ratio. Ampere-turns are calculated by
multiplying the current in the coil by the number of turns. Primary ampere-turns are
equal to secondary ampere-turns. Voltage regulation of a transformer is the percentage
increase in voltage from full load to no load.
Losses and efficiency
• Transformers are inherently very efficient, by design.
• Efficiency varies from 96 per cent to 99 per cent.
However, transformer efficiency depends on load (% loading), making efficiency
dependent not only design but also on the effective operating load.
Transformer losses are of two types:
1. No-load loss, also referred to as ‘core loss’—the power consumed to sustain the
magnetic field in the transformer's core.
2. Load loss—associated with full-load current flow in the transformer windings and
due, primarily, to the resistance of the winding material. Because transformers
traditionally used copper windings, load loss is also referred to as ‘copper loss’.
From Ohm’s Law for power in a resistor (P=I2R), copper loss varies with the square
of the load current.
3. For a given transformer:
PTOTAL = PNO-LOAD + (% Load/100)2 x PLOAD
where % load = (actual load of transformer / rated power of transformer).
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Reducing transformer losses
A. Proper transformer sizing
Greatly oversized transformers can contribute to inefficiency. When transformers are
matched to their loads, efficiency increases (see Table M.33).
Table M.33: Losses in distribution transformers
kVA
No-load loss (W)
Full-load loss
Efficiency
100
500
2 000
97.5
125
570
2 350
97.66
160
670
2 840
97.81
200
800
3 400
97.90
250
950
4 000
98.02
315
1 150
4 770
98.15
400
1 380
5 700
98.23
500
1 660
6 920
98.28
630
1 980
8 260
98.37
800
2 400
9 980
98.45
1 000
2 800
11 880
98.54
B. Energy efficient amorphous transformers
Amorphous iron is expensive but reduces core loss to less than 30 per cent of
conventional steel core losses. An alternative, less expensive core material is silicone
steel which has higher losses than amorphous iron but lower than standard carbon
steel (see Table M.34).
Table M.34: Amorphous core transformer losses
Transformer kVA
No-load loss (W)
100
60
1 635
160
90
2 000
200
110
3 000
250
160
3 280
315
180
4 000
500
240
5 600
630
300
6 300
750
360
7 200
1 000
430
9 000
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Worksheet: Transformer rated specifications
Section
no.
Parameter
reference
Transformer reference
Units
1
1
Power rating
kVA
2
Primary voltage
(high voltage)
kV
3
Secondary voltage
(low voltage)
kV
4
Voltage ratio
(HV/KV)
–
5
Primary current
Amps
6
Secondary current
Amps
7
Impedance
Ohms
8
Power factor
–
9
No-load losses
kW
10
Full-load losses
kW
OPEN FILE
2
3
Worksheet: Transformer operational parameters
Section
no.
Parameter
reference
1
Power rating
2
Primary (average values)
3
4
4
OPEN FILE
Transformer reference
Units
1
2
3
4
kVA
a) Voltage
Volts
b) Current
Amps
c) Power Factor
–
d) Power Input
kVA kW
Secondary (average values)
a) Voltage
Volts
b) Current
Amps
c) Power Factor
–
d) Power Output
kVA kW
Efficiency
%
3d x 100
2d
5
% Loading
%
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M1.9.3 Pump systems
Pumps are only one component of pumping systems which also include motors, drives,
piping and valves. Typically, much less than half the electricity input to a pumping
system is converted into useful movement of fluid. The rest is dissipated in the various
components that make up the system. Energy losses are even greater when the system
is not operating at its design point. There is, therefore, a considerable potential for
saving electricity, by both improving component efficiencies and through better
system design.
Centrifugal pumps
Centrifugal pumps are used for the vast majority of pump applications in industry.
Centrifugal pumps impart energy to the fluid by centrifugal action. They rely on the
flow of fluid to create a seal to prevent fluid flowing backward through the pump. The
volute type (see Figure M.37) is the most common centrifugal design. The impeller
vanes generally curve backwards, but radial and forward vanes are also used. The
velocity head of the fluid is converted into pressure head.
Figure M.37 Volute centrifugal pump casing design
Discharge
Impeller
Impeller vanes
Suction
Volute casing
Casing drain
Need for careful selection of pumps
The characteristic curve of a centrifugal pump is shown in Figure M.38. Pumps have to
be selected so that they operate at their best efficiency point. Oversizing of flow during
initial selection can lead to shifting of the efficiency point, resulting in reduced
operational efficiency. An oversized pump also needs to be throttled for reduced flow
conditions.
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Figure M.38 Characteristic curve of a centrifugal pump
Head
250 ft.
76 m
50%
A
55%
60%
Best efficiency point
B
C
D
156 ft.
47 m
E
capacity
300 gpm
68 m3/h
The relationship between head, capacity and power is given by the following equation:
Head (metres) x capacity (m3/h)
360
= kW
The following example shows how the most appropriate size of pump can be selected
in practice.
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Example 13: Pump selection
A facility needed to pump 68 m3/hr to a 47 metre head with a pump that is 60 per cent efficient
at that point.
Liquid power:
Shaft power:
Motor power:
68 x 47 / 360 = 8.9 kW
8.9 / 0.60 = 14.8 kW
14.8 / 0.9 = 16.4 kW
(Where ‘360’ is a constant)
(Where 0.6 is the efficiency at that point)
(Where 0.9 is the motor efficiency)
As shown in Figure M.38, impeller ‘E’ is the one that should be used to do this, but the pump is
oversized, so the larger impeller ‘A’ is used with the pump discharge valve throttled back to
68 m3/hr, giving an actual head of 76 metres.
The kilowatts now look like this:
68 x 76 / 360 = 14.3 kW being produced by the pump, and 14.3 / 0.50 = 28.6 kW required to
do this. Subtracting the amount of kilowatts that should have been used gives:
28.6 – 14.8 = 13.8 extra kilowatts being used to pump against the throttled discharge valve.
Extra energy used = 8 760 hrs (i.e.1 yr) x 13.8 = 120 880 kW.
For the facility in question, that meant a saving of US$10 000/year.
In this example the extra cost of the electricity could almost equal the cost of purchasing two or
three pumps.
NOTE: Why the oversized pump?
• Safety margins were added to the original calculations.
• Several people were involved in the pump buying decision, and each of them was afraid of
recommending a pump that would prove to be too small for the job.
• It was anticipated that a larger pump would be needed in the future, so it was purchased now
to save buying the larger one later on.
• It was the only pump the dealer had in stock and a pump was needed badly. The dealer may
have proposed a ‘special deal’ on the larger size.
• The pump was taken out of the spare parts inventory. Capital equipment money is scarce so the
larger pump appeared to be the only choice.
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Affinity laws for pumps
The basic laws governing a pump are:
Q1 / Q2 = N1 / N2,
e.g.: 100 / Q2 = 1750/3500,
Q2 = 200 GPM
H1/H2 = (N12) / (N22)
e.g.: 100 / H2 = 1750 2 / 3500 2
H2 = 400 Ft
P1 / P2 = (N13) / (N23)
e.g.: 5/P2
= 17503/ 35003
P2 = 40
Where: Q = discharge head
H = head
N = rpm
P = power
Flow control strategies
Varying flow requirements can be met by conventional and low cost options such as
by pass control or throttle control, but both of these methods are highly energy
inefficient. There are occasions when permanent change in the amount of fluid
pumped or a change in the discharge head of a centrifugal pump may be desirable.
This can be achieved economically by trimming the impeller or replacing it with a
reduced size impeller or, at the worst, replacing the pump itself.
The most efficient way to deal with varying flows is by means of a variable speed drive.
This ensures that the pump always operates at the best efficiency point and eliminates
the need for any throttling. The virtue of this method is that it reduces the energy input
to the system instead of dumping the excess. With decreasing costs in power
electronics, variable speed drives are becoming more popular today.
Variable flow requirements can also be met by multiple pump operation, with pumps
switching on and off as required.
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Figure M.39: Rated pressure vs. rated flow
100
Ppm
100%
per cent rated pressure
80
60
80%
40
60%
Plm
20
40%
20%
0
0
20
40
60
80
100
120
per cent rated flow
Worksheet: Pump rated specifications
Section
no.
Parameter reference
OPEN FILE
Pump reference
Units
1
1
Make
2
Type (reciprocating/centrifugal)
3
Discharge capacity (flow)
m3/hr
4
Head developed
mwc
5
Density of fluid handled
kg/m3
6
Temperature of fluid handled
°C
7
Pump input power
kW
8
Pump speed
rpm
9
Pump efficiency
%
10
Specific power consumption
kW/(m3/hr)
11
Pump motor:
Power
kW
Full-load current
Amps
Voltage
Volts
Power factor
PF
Speed
rpm
Frequency
Hz
Efficiency
%
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Worksheet: Pump performance evaluation
Section
no.
Parameter reference
OPEN FILE
Pump reference
Units
1
1
Fluid flow measured or estimated (Q)
m3/sec
2
Suction pressure (include head correction
due to pressure gauge location)
mwc
3
Discharge pressure (include head
correction due to pressure gauge location)
mwc
4
Total dynamic head (3–2) (TDH)
mwc
5
Density of the fluid (γ)
kg/m3
6
Motor input power (P)
kW
7
Frequency
Hz
8
Combined efficiency (pump + motor)
(Q x γ ) x 9.81 x (TDH/γ) x 100
P
%
9
Pump efficiency =
Combined efficiency x 100
motor efficiency
%
10
Specific power consumption
kW/(m3/hr)
11
% Motor loading
w.r.t rated power
%
12
% Pump loading
w.r.t rated capacity
%
13
% Pump loading
w.r.t design TDH
%
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M.1.9.4 Fan systems
Introduction
Fans and blowers provide air for ventilation and industrial process requirements. They
are distinguished by the method used to move the air, and by the system pressure at
which they must operate. As a general rule, fans operate at pressures up to around 2 psi,
blowers at between 2 psi and 20 psi, although custom-designed fans and blowers may
operate well above these ranges. Air compressors are used for systems requiring more
than 20 psi. Figure M.40 shows the components of a centrifugal fan, one of the most
widely used air movers. The role of the components is explained below.
Figure M.40 Fan system components
Impeller wheel
Air outlet
Shaft
Air inlet
Scroll housing
• Air inlet—air enters the turning impeller wheel.
• Impeller wheel—imparts energy to the air in the form of motion and pressure. As
the wheel turns, air between the blades is moved in the direction of the blade
and accelerated outward by centrifugal force.
• Shaft—turned by a motor coupled either directly to the shaft or via V-belts and
pulleys.
• Scroll housing—directs air from the impeller wheel to the fan outlet efficiently.
• Outlet—typically connected to a duct distributing the air to where it is needed.
Fans generate a pressure to move air (or other gases) against a resistance caused by
ducts, dampers, or other system components. The fan rotor receives energy from a
rotating shaft and transmits it to the air. The energy appears in the air, downstream of
the fan, partly as velocity pressure and partly as static pressure. The ratio of static to
velocity pressure varies for different fan designs. Fans are typically characterized by the
algebraic sum of the two pressures, known as total pressure. Parts of the fan other than
the rotor (such as the housing, straightening vanes, and diffusers) influence the ratio
of velocity and static pressure at the outlet, but do not add energy to the airflow.
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Typical applications and efficiencies
Fan and blower selection depends on the volume flow rate, pressure, type of material
handled, space limitations, and efficiency. Fan efficiencies differ from design to design
and also between types. A range of fan efficiencies is shown in Table M.35. Table M.36
lists a few of the many applications and the type of equipment typically used.
Table M.35: Typical efficiencies of various types of fans
Fan type
Peak efficiency range
Centrifugal fans
Airfoil, backwardly curved/inclined
Modified radial
Radial
Pressure blower
Forwardly curved
79–83
72–79
69–75
58–68
60–65
Axial fan
Van-axial
Tube-axial
Propeller
78–85
67–72
45–50
Table M.36: Applications of different types of fans and blowers
Application
Type of fan or blower
Material conveying system with high air/material ratio
and fine, granular materials
Radial, backward inclined fans
Centrifugal blowers
Material conveying systems with low air/material ratio
and materials prone to clogging distribution system
Positive-displacement blowers
Supplying air for combustion
All fan types
Boilers, forced draught
Airfoil, backwards inclined, vane-axial fans
Boosting gas pressures
Centrifugal blowers
Boilers, induced draught
Forward curved, radial fans
Kiln exhaust
Radial fans
Kiln supply
Airfoil, backwards inclined, vane-axial fans
Process drying
Airfoil, backwards inclined, radial, vaneaxial, tube-axial fans. Centrifugal blowers
Aeration and agitation systems
Centrifugal, positive-displacement blowers
Plant ventilation and HVAC (clean air only)
Airfoil, backwards inclined, forward-curved
vane-axial, tube-axial, propeller fans
Air knife blow off systems, clean-up air supply, vacuum
cleaning systems
Centrifugal blowers
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Fan speed and gas flow rate
A basic understanding of fan operating principles is necessary to evaluate the
performance of an industrial ventilation system. The fan speed, expressed as
revolutions per minute (rpm), is one of the most important operating variables. The
flow rate of the air moving through the fan depends on the fan wheel rotational speed.
As the speed increases, the airflow rate increases, as indicated by the sample data in
Table M.37.
Table M.37: Sample data—fan speed vs. airflow data
Fan wheel speed
(rpm)
Air flow rate
(actual cubic feet per minute — ACFM)
800
16 000
900
18 000
1 000
20 000
1 100
22 000
1 200
24 000
It is important to understand that a 10 per cent decrease in fan speed results in a
10 per cent decrease in the airflow rate through the ventilation system. This
relationship is expressed in the first fan law:
Q2 = Q1
rpm2
rpm1
Where: Q1
Q2
rpm1
rpm2
=
=
=
=
Baseline airflow rate, ACFM
New airflow rate, ACFM
Baseline fan wheel rotational speed, revolutions per minute
New fan wheel rotational speed, revolutions per minute
Note: The rate of airflow through a fan is always expressed in terms of actual cubic feet
per minute (ACFM).
Fan static pressure rise
The air stream moving through the fan experiences a static pressure rise due to the
mechanical energy expended by the rotating fan wheel. As indicated in Figure M.41,
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the static pressure at the outlet is always higher than the static pressure at the inlet.
The general equation for calculating the static pressure rise across a fan is:
Fan Sp∆ = SP(Fan outlet) – Sp Fan inlet) – VP(fan inlet)
Where: SP(Fan outlet) = Static pressure at fan outlet, in W.C.
SP(Fan inlet) = Static pressure at fan inlet, in W.C.
VP(Fan inlet) = Velocity pressure at fan inlet, in W.C.
Figure M.41 Static pressure rise (∆SP) across a fan
–10 in W.C
+0.05 in W.C
VP = 0.4 in. W.C.
Air out, ACFM
Air in, ACFM
Centrifugal fan
Fan ∆SP = [0.05 – (–10) – 0.4] in W.C. – 9.65 in W.C.
The fan ∆SP (static pressure) is related to the square of the fan speed as indicated in
the second fan law shown below. The fan static pressure rise is usually expressed in
units of inches of water column.
rpm2
rpm1
Fan∆Sp2 = Fan∆SP1
Where: Fan ∆Sp2
Fan ∆SP1
rpm1
rpm2
=
=
=
=
2
Baseline fan static pressure rise, in W.C.
New fan static pressure rise, in W.C.
Baseline fan wheel rotational speed, revolutions per minute
New fan wheel rotational speed, revolutions per minute
The static pressure rise across the fan increases rapidly as fan speed increases. This is
illustrated in Table M.38, using sample data.
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Table M.38: Fan speed vs. fan static pressure rise
Fan ∆SP (in W.C.)
Fan wheel speed (rpm)
800
5
900
5.6
1 000
6.3
1 100
6.9
1 200
7.5
Speed vs. power
The brake horsepower is related to the cube of the fan speed as indicated in the
third fan law, shown below:
Where: Q1
Q2
rpm1
rpm2
3
rpm2
rpm1
BHP2 = BHP1
=
=
=
=
Baseline brake horse power
New brake horse power
Baseline fan wheel rotational speed, revolutions per minute
New fan wheel rotational speed, revolutions per minute
Energy audit of a fan
The first step in the energy audit of a fan system is the collection of ducting details and
of fan characteristic curves. A typical curve is shown in Figure M.42.
Figure M.42 Fan characteristic curve
4.5
100
B Peak efficiency + 10%
4.0
3.0
ris
tic
s
2.5
ar
ac
te
2.0
1.5
te
sys
1.0
m
ch
70
y
fan
60
ics
ist
er
ct
3.5
50
ar
a
40
30
ch
20
0.5
0.0
0
90
80
ef
f
fan efficiency (%)
Peak efficiency point A
c
en
ic i
static pressure across fan (kPa)
5.0
10
10
20
30
40
50
60
70
0
80
volume (m2/s)
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The fan and system operating efficiencies may then be determined from measurements
of the power input to the motor, the heads at various places in the system, and the
flow rate. The power input to the motor may be measured with a portable power
analyser. Heads may be measured by using a pitot tube and manometer. Along with
these measurements, the temperature of flow should also be measured (using a
thermometer or thermocouple) for calculation of flow density, using the known density
value at NTP (temperature 273 K and pressure 1 atm). The rpm of fan rotation may
also be measured using a tachometer.
Once the above measurements have been made, the fan and system efficiencies may
be calculated as follows:
Fan efficiency =
(
Air kW
x 100
ηm x input kW
(
)
Flow in TPH x1000 kg
100kg/m3
mmWC
x
mWC x
x 9.81m/sec2
3600
Sec
ρa
1000
) (
)
(
)
Air kW =
1000
Where: ρa =
ηm =
density of air at measured temp. (kg/m3)
efficiency of motor (0.85 for small kW motors, 0.9 for large kW motors
and 0.95 for HT motors)
Input kW = AC input power to motor terminals
CP-EE measures for fans and blowers
Improving fan efficiency
When fan design efficiency is low, replacement by fans of a more efficient design may
be considered. Fan efficiency improvement may also be obtained when a fan impeller
design is changed from one of low intrinsic efficiency to one having higher intrinsic
efficiency, for example switching from radial bladed impeller to backward, straight
bladed impeller.
When fan-operating efficiency is low because of mismatch between fan and system
(resulting from over-design) the following may be considered:
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• Reducing fan speed (by pulley change or variable speed drives).
• Replacement of impeller with a smaller one in the same series. Manufacturers
usually supply more than one impeller for the same casing, allowing a change in
head or flow. Depending on the specific job, this can allow either an increase or a
decrease in flow or head, typically 10–25 per cent.
• Reduction in impeller diameter, by cutting it.
Improving system efficiency
When system efficiency is to be improved, a detailed audit of the ducting may be done.
In addition to the losses from leaks/ingress there are often a number of flow losses that
can be reduced when the system is analysed to pinpoint specific areas where energy
savings can be made.
Even small leaks represent a constant parasitic loss of energy and of system efficiency.
All leaks in the ducting should be located and eliminated.
Examine the possibility of reducing pressure loss in bends, cross-sectional area changes
and stream splits and joints, through redesign.
Reducing damper losses
Throttle dampers are a very common means of controlling flow delivered by a fan.
They regulate the flow by offering mechanical resistance to it, thereby consuming a
large amount of energy in the form of head loss across the damper.
Where capacity regulation is desired it is, therefore, desirable to use one of the
following methods in preference to damper control:
•
•
•
•
Inlet guide vanes.
Variable speed fluid couplings or eddy current couplings.
Liquid rotor resistance control.
Variable speed AC/DC drives.
The variations in power consumption for different methods of capacity regulation are
shown in Figure M.43.
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Figure M.43 variable speed drives for fans and pumps
Energy savings from variable speed drives
From
1. Constant volume
2. Constant volume
3. Constant volume
4. Outlet dampers
5. Outlet dampers
6. Inlet vanes
To
Outlet dampers
Inlet vanes
VFDs
Inlet Vanes
VFDs
VFDs
% savings
11
31
72
23
69
59
Worksheet: Rated fan specifications
Section
no.
Parameter reference
OPEN FILE
Fan reference
Units
1
1
Make
–
2
Type (axial/centrifugal)
(Backward curve/forward curve)
–
3
Discharge flow
m3/hr
4
Total head developed
mwc
5
Name of fluid medium handled
6
Temperature of fluid medium handled
7
Density of fluid handled
kg/Nm3
8
Dust concentration
mg/Nm3
9
Flow control type
–
10
Flow control range
%
11
Fan input power
kW
12
Fan speed
rpm
13
Fan efficiency
14
Specific power consumption
2
3
4
–
°C
%
kW/(m3/hr)
Fan motor
15
Rated power
16
Full-load current
Amps
17
Voltage
Volts
18
Power factor
19
Speed
20
Frequency
Hz
21
Efficiency
%
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kW
PF
rpm
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Worksheet: Operating parameters and performance
Section
no.
Parameter reference
Fan reference
Units
1
1
Fluid (medium) flow (Q)
(measured using pitot tube at fan
discharge)
m3/sec
2
For suction pressure
(measured at fan inlet using U-tube
manometer)
mmWC
3
For discharge pressure
(measured at fan discharge using
U-tube manometer)
mmWC
4
Total head developed (TDH)
[3–4/1000]
mWC
5
Temperature of fluid medium
(measured at fan inlet using a
thermometer)
°C
6
Density of fluid medium handled (r)
(taken from standard data and
corrected to operating
temperature/pressure conditions)
kg/m3
7
Motor input power (P) measured at
motor terminals or switchgear using
panel or portable energy
meter/power analyser
kW
8
Frequency
Hz
9
Combined efficiency ( fan + motor)
(Q x r) (9.81) (TDH/r) x 100
P x 1000
%
10
Fan efficiency =
Combined efficiency x 100
Motor efficiency
%
11
% Motor loading w.r.t rated power
%
12
% Motor loading w.r.t rated capacity
%
13
% Motor loading w.r.t rated head
%
14
Specific power consumption
kW/(m3/h)
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2
3
4
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M1.9.4 Compressed air systems
Compressed air is used in almost all types of industries and accounts for a major share
of the electricity used in some plants. It is used for a variety of end-uses such as
pneumatic tools and equipment, instrumentation, conveying, etc. and is preferred in
industry because it is convenient clean, readily available and safe. Compressed air is
probably the most expensive form of energy available in a plant, yet it is still often
chosen for applications for which other energy sources would be more economical—
for example, pneumatic grinders are chosen rather than electric ones.
As a general rule, compressed air should only be used if safety improvement, significant
productivity gains, or labour reductions will result. Typical overall efficiency is around
10 per cent.
Depending on requirements, compressed air systems consist of a number of
components: compressors, receiver, filters, air dryers, inter-stage coolers, oil separators,
valves, nozzles and piping. Figure M.44 shows a system layout.
The compressor is the main system component—it must therefore be selected
carefully. The most commonly used compressors in industry are reciprocating and
screw types. Centrifugals are also used where very large volumes are required.
Figure M.44 Layout of a compressed air system
Reciprocating compressors
A reciprocating compressor (see Figure M.45) is a positive displacement machine that
uses a piston moving inside a cylinder to produce compression. The piston moves
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Figure M.45 A reciprocating compressor
First stage
Second stage
Drive motor
Baseplate
Crankcase (frame)
through the cylinder, sucking in atmospheric air at one
end of its stroke and compressing it at the other.
Reciprocating compressors are available as ‘oil-free’ or ‘lubricated’ types. The reciprocating
compressor probably accounts for most of the compressors used worldwide.
Screw compressors
A screw compressor (see Figure M.46) is a positive displacement machine that uses a
pair of intermeshing rotors instead of a piston to produce compression. The rotors
comprise helical lobes fixed to a shaft.
Figure M.46 A screw compressor
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One rotor, called the male rotor, will typically have four bulbous lobes. The other,
female, rotor has valleys machined into it that match the curvature of the male lobes.
Typically, female rotors have six valleys meaning that for one revolution of the male
rotor, the female rotor only turns through 240°. For the female rotor to complete one
cycle, the male rotor has to rotate 1.5 times. Screw compressors are available as oil-free
machines, oil-lubricated machines and, more recently, as water lubricated machines.
CP-EE options in compressed air systems
A comprehensive compressed air system audit should include an examination of both air
supply and usage and the interaction between supply and demand. An audit determines
the output (flow) of a compressed air system, energy consumption in kilowatt-hours,
annual cost of operating the system and total air losses due to leaks. All components of the
compressed air system are inspected individually and problem areas are identified. Losses
and poor performance due to system leaks, inappropriate use, demand events, poor system
design, system misuse, and total system dynamics are evaluated and CP-EE measures are
derived. Important aspects of a basic compressed air system audit are discussed below.
Pressure drop
A properly designed system should have a pressure loss of much less than 10 per cent
of the compressor's discharge pressure, measured between the receiver tank output
and the point of use. Excessive pressure drop will result in poor system performance
and excessive energy consumption.
Leaks
As illustrated by Figure M.47, leaks can be a significant source of wasted energy in an
industrial compressed air system, sometimes wasting 25–50 per cent of a compressor's
output. Proactive leak detection and repair can reduce leaks to less than 10 per cent of
compressor output.
Figure M.47 Leaks and losses
Size
Cost per year
1/16"
US$523
1/8"
US$2 095
1/4"
US$8 382
Cost calculated using electricity rate of US$0.05 per kWh,
assuming constant operation and an efficient compressor.
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In addition to being a source of wasted energy, leaks can also contribute to other
operating losses. Leaks cause a drop in system pressure, which can make air tools
function less efficiently, adversely affecting production. In addition, by forcing the
equipment to cycle more frequently, leaks shorten the life of almost all system
equipment (including the compressor package itself). Increased running time can also
lead to additional maintenance requirements and increased unscheduled downtime.
Finally, leaks can lead to addition of unnecessary compressor capacity.
Leakage can come from any part of the system, but the most common problem areas
are couplings, hoses, tubes, and fittings, pressure regulators, open condensate traps
and shut-off valves and pipe joints, disconnects, and thread sealants.
Estimating amount of leakage
For compressors that use start/stop controls, there is an easy way to estimate the
amount of leakage in the system. This involves starting the compressor when there are
no demands on the system (i.e. when all the air-operated end-use equipment is turned
off). A number of measurements are taken to determine the average time it takes to
load and unload the compressor. The compressor will load and unload because the air
leaks will cause it to cycle on and off as the pressure drops from air escaping through
the leaks. Total leakage (percentage) can be calculated as follows:
Leakage (%) =
where:
(T x 100)
(T + t)
T = on-load time (minutes)
t = off-load time (minutes)
Leakage will be expressed in terms of the percentage of compressor capacity lost. The
percentage lost to leakage should be less than 10 per cent in a well-maintained system.
Poorly maintained systems can have losses as high as 20–30 per cent of air capacity
and power. These tests should be carried out quarterly, as part of a regular leak
detection and repair programme.
Leak detection
Since air leaks are almost impossible to see, other methods must be used to locate
them. The best way to detect leaks is to use an ultrasonic acoustic detector that
recognizes the high frequency hissing sounds associated with air leaks. These portable
units consist of directional microphones, amplifiers, and audio filters, and usually have
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either visual indicators or earphones to detect leaks. A simpler method is to apply
soapy water with a paintbrush to suspect areas. Although reliable, this method can be
time consuming.
How to fix leaks
Leaks occur most often at joints and connections. Stopping leaks can be as simple as
tightening a connection or as complex as replacing faulty equipment such as
couplings, fittings, pipe sections, hoses, joints, drains, and traps. In many cases leaks
are caused by bad or improperly applied thread sealant. Select high quality fittings,
disconnects, hoses, tubing, and install them properly with appropriate thread sealant.
Non-operating equipment can be an additional source of leaks. Equipment no longer
in use should be isolated by a valve in the distribution system. Once leaks have been
repaired, the compressor control system should be re-evaluated to ascertain the total
savings potential
A leak prevention programme
A good leak prevention programme will include the following components: identification
(including tagging), tracking, repair, verification, and employee involvement. All facilities
with compressed air systems should establish an aggressive leak prevention programme.
A cross-cutting team involving decision-making representatives from production should be
formed. The leak prevention programme should be part of an overall programme aimed
at improving the performance of compressed air systems. Once leaks are found and
repaired, the system should be re-evaluated.
Rationalization of compressed air use
The need for compressed air should be questioned at every usage point. In some
instances, the volume of air may be more important than pressure. Under such
circumstances alternative options like centrifugal blowers or roots blowers can be
considered. Misuse of compressed air for cleaning should be avoided.
Using lower pressure
Compressor discharge pressure should be closely matched with the requirement
(allowing for pressure drops in the distribution system). Higher than necessary
discharge pressure is detrimental to performance since it increases the compression
ratio and hence the power consumption.
Table M.39 illustrates the effect of increased discharge pressure on specific power
consumption of reciprocating compressors.
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Table M.39: Effect of increased discharge pressure on specific power consumption
Pressure (bar)
No. of stages
Volume flow
(m3/min)
Specific power
(kW/m3/min)
1
Single
21.1
2.22
2
Single
20.3
3.40
3
Single
19.3
4.60
4
Single
18.0
5.14
7
Double
19.0
6.47
8
Double
18.9
6.76
10
Double
19.5
7.67
15
Double
19.2
9.25
Heat recovery
As much as 80–93 per cent of the electrical energy used by an industrial air compressor
is converted into heat. In many cases, a properly designed heat recovery unit can
recover anywhere from 50–90 per cent of this available thermal energy and put it to
use heating air or water.
Typical uses for recovered heat include additional space heating, industrial process
heating, water heating, make up air heating, and boiler make up water preheating.
Recoverable heat from a compressed air system is not, however, normally hot enough
to be used to produce steam directly.
Use of multiple compressors
When the demand on a compressed air system is variable in nature, and exhibits well
defined peak and slack demand periods, use of a single compressor designed to meet
peak demand would lead to under-loading of the compressor and increased duration
of the no-load cycle. Unloading power is 30 per cent of full load power. In this
situation, energy savings can be realized by using multiple compressors. The number
of compressors in operation is adjusted to the compressed air demand, thereby
avoiding under-loading of compressors.
Replacement/de-rating of oversized compressors
In the case of oversized compressors, the power wastage during unloading can be
reduced by either replacing the compressor in the case of oversized machines, or by
de-rating. De-rating can be achieved by running the compressor at a lower speed.
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Empirical relations
Some useful empirical relationships for compressors are given below:
Leakage (Nm3/min) =
Load time
Unload time + Load time
(
)
x (Compressor capacity Nm3/min)
Compressor Capacity (FAD) Nm3/hr =
(
Initial receive pressure kg/cm2.a – final receiver pressure kg/cm2.a
Atmosphere pressure kg/cm2.a
(
Volume of receiver + volume of line between compressor and receiver in m3
Time taken to fill receiver from initial pressure to fonal pressure in minutes
(
273
273 + reciever temperature °C
)
x
)
x
)
Specific power consumption =
(
Actual motor power input
FAD (Nm3/m)
)
x 100
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Worksheet: Compressor rated specification
Air compressor reference
Compressor reference
Units
1
Make
–
Type
–
No. of stages
–
Discharge capacity
Nm3/min
Discharge pressure
kg/cm2.g
Speed
rpm
Receiver capacity
m3
OPEN FILE
2
3
4
Motor rating
Power
kW
Full load current
Amps
Voltage
Volts
Power factor
P.F.
Speed
rpm
Frequency
Specific power consumption
Hz
kW/m3/min
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Worksheet: Capacity testing
Air compressor reference
OPEN FILE
Compressor reference
Units
1
Receiver volume plus volume
of pipeline between receiver
and the air compressor
m3
Receiver temperature
°C
Initial receiver pressure (P1)
kg/cm2.a
Final receiver pressure (P2)
kg/cm2.a
Time taken to fill receiver
from P1 to P2 (t)
mins.
Atmospheric pressure (Po)
kg/cm2.a
Air compressor capacity
(free air delivery) Q
Nm3/min
2
3
4
Note: Each compressor must have its own receiver.
Procedure:
1) The air compressor being tested for capacity is first isolated from the rest of the
system, by operating the isolating non-return valve.
2) The compressor drive motor is shut-off.
3) The receiver connected to this air compressor is emptied.
4) The motor is re-started.
5) The pressure in the receiver begins to rise. Initial pressure, say 2 kg/cm2 , is noted.
The stopwatch is started at this moment.
6) The stopwatch is stopped when receiver pressure has risen to, say, 9 kg/cm2.
7) Time elapsed is noted.
8) Compressor capacity is evaluated as:
(Nm3/min) =
(
P2 – P1
P0
) ( ) (
x
Vr
t
x
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273
273 + T
)
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Worksheet: Leakage testing
Compressor in operation
Compressed air users
OPEN FILE
CP-EE
spotlight
Units
Names of section of factory
--
Two (assumed)
Load time (t1)
Seconds
(Measured)
Unload time (t2)
Seconds
(Measured)
Capacity of compressor
Nm3/min
(Given)
Leakage
(
t1
t1 + t2
)
%
Leakage cfm
(
Leakage %
100
(Evaluated)
x 100
(Evaluated)
)
x (Capacity of compressor)
• Leakage will be
expressed in terms of
the percentage of
compressor capacity lost.
• The percentage lost to
leakage should be less
than 10 per cent in a
well-maintained system.
• Poorly maintained
systems can have losses
as high as 20–30 per
cent of air capacity.
Note:
1) Per cent or Nm3/min of compressed air leakage is evaluated, and the energy cost of
compressed air is determined.
2) Plant survey is undertaken to physically identify obvious compressed air leakages. No
instruments are really necessary. However, an ultra-sonic leak detector may be used,
optionally.
3) Elimination of leakage sources leads to direct and immediate compressed air and
electricity cost savings.
Procedure:
1) Leakage test is conducted when entire plant is shut-down or when all compressed air
users are not working. It would be advantageous if separate sections could be isolated
from one another by isolating valves.
2) A dedicated compressor is switched on to fill the system network with compressed air.
3) Since there are no compressed air users, the air compressor will unload the moment
the system pressure reaches the set point (say, 8 kg/cm2.g).
4) If the system has no leaks, the air compressor will remain unloaded indefinitely.
5) However, since there are bound to be system leaks, the receiver pressure gradually
begins to drop, until the lower set point is reached, at which point the air compressor
is loaded again and begins to generate compressed air.
6) Load and unload times are measured using a stopwatch over 5–6 cycles, and average
load and unload times are worked out.
7) Compressed air leakage (%) and quantity are then evaluated.
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M1.10 Cooling towers
M1.10.1 Basics of cooling towers
Heat removed from a process or building must be disposed of. In many cases, this heat
is transferred to water at a lower temperature via a heat exchanger. It is then
transferred to a heat sink.
Billions of gallons of water are used every day for air conditioning/refrigeration systems
and for industrial process cooling in, for example, paper mills, chemical plants, food
processing, etc. To reduce both water costs
and pressure on water supplies, much of
this cooling water is re-circulated. Final
exchange of heat from a building or
process to a heat sink is often by means of
a water-to-air heat exchanger, with the
atmosphere being the heat sink.
These water-to-air devices are called
cooling towers. They play a vital role in
water conservation, typically reducing
water consumption by 95 per cent or
more, depending on whether an
evaporative or dry tower is used.
From the thermodynamic point of view, there are three basic types of cooling tower.
Wet or evaporative towers are ones in which the water to be cooled comes in contact
with the outdoor air. Both latent and sensible cooling occurs. These towers have the
highest thermal efficiency. They also consume more water than the other two types
(see below), but a 95 per cent saving is still significant.
A dry tower is one in which the water to be cooled flows within an extended heat
transfer surface—a finned tube coil—over which atmospheric air is blown.
The third type of tower is the wet-dry type, which combines the functions of the two
previous types. Table M.40 includes some terminology to aid understanding. The
discussion thereafter focuses on wet towers.
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Table M.40: Table of cooling tower terminology
Air flow
Total quantity of air including the associated water vapour flowing through the
tower.
Approach
Difference between re-cooled water temperature and the inlet air wet bulb
temperature.
Capacity control
dampers
Airfoil blades placed at the discharge of a centrifugal fan that change position
so as to regulate airflow.
Casing
The part of a cooling tower enclosing the wet deck fill.
Cavitation
The phenomenon that occurs in a water pump when the pressure becomes
sufficiently low to allow vaporization of the fluid followed by a sudden collapse
of the vapour ‘bubble’ as it passes to the high pressure area of the pump.
Cold water basin
The collection point near the bottom of a cooling tower for the collection of
cooled water.
Composite
Construction material utilizing high strength glass materials held in place by
cured epoxy resins in a precise order so as to maximize strength.
Concentration
ratio
Ratio of the total mass of impurities in the circulating water to the
corresponding total mass in the make up water.
Conductivity
monitor
A device that measures the ease with which electricity passes through cooling
system water. Conductivity is directly proportional to the amount of dissolved
solids in the water and is used to initiate bleeding, feeding chemicals, etc.
Cooling range
Difference between the hot water temperature and the re-cooled water
temperature.
Cooling tower ton
15 000 Btu/hr.
Counter flow
A cooling tower configuration where the air and water flow in opposite
directions.
Cross flow
A cooling tower configuration where the air and water flow at right angles to
one another.
Cycles of
concentration
The number of times the solids content of water has been increased.
Two fold = 2 cycles; three fold = 3 cycles, etc.
Discharge hood
A discharge duct with sides that gently taper reducing the cross sectional area
thereby accelerating the discharge air. Used to ‘blast’ discharge air from an
enclosure to reduce recirculation potential. Note: suitable for centrifugal fan
towers only.
Drift loss
Water loss caused by liquid drops carried away by the outlet air stream.
Dry bulb
Temperature of air measured with a conventional thermometer with a dry bulb.
continued …
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… Table M.40: Table of cooling tower terminology (continued)
Eliminator
A device placed in the discharge airstream of a cooling tower that attempts to
‘eliminate’ entrained water droplets. It works by rapidly changing the direction
of airflow causing the heavier water particles to collide with the eliminator
surface and fall back inside the tower.
Equalizer line
A pipe connected between the cold water basins of multiple cooling towers. Its
purpose is to force ‘equalization’ of water levels.
Fan deck
The upper horizontal surface surrounding the fan stacks of a draw-through,
propeller fan cooling tower.
Fill
Material added to a cooling tower to enhance evaporation.
Hot water basin
Water collection area at the top of a crossflow cooling tower the bottom of
which is perforated to distribute water over the wet deck fill.
Latent heat
Heat which changes the properties of a material without changing its
temperature.
Louvers
Horizontal blades placed at the air inlet of some cooling towers to prevent
water from splashing out.
Make up
Water added to the circulating water system to replace leakage, evaporation,
drift loss and purge.
Psychrometric
chart
A graphical representation of the physical characteristics of air.
Purge
Water deliberately discharged from the system in order to reduce the
concentration of salts and other impurities in the circulating water.
Range
A cooling tower’s inlet water temperature minus its outlet water temperature.
Re-circulation
The proportion of outlet air which re-enters the tower.
Sensible heat
Heat that increases the temperature of a body to which it is added.
Ton
The rate of heat transfer represented by 2 000 tons of ice melting in a 24 hour
period (12 000 Btu/hr).
Turn down
The allowable percentage reduction of inlet water flow to a cooling tower.
Velocity recovery
stack
A hyperbolic discharge plenum at the top of a draw-through, prop. fan cooling
tower. The shape increases the efficiency of the fan by converting some of the
velocity pressure to static pressure for increased air flow.
Wet bulb
The temperature read from the wet bulb of a thermometer placed in a moving
air stream.
Cleaner Production – Energy Efficiency Manual
CP-EE
spotlight
Inefficient operation of a
tower with a cold water
temperature around
1.5 °C higher than it
should be can increase
process plant energy
consumption by
10 per cent or more.
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M1.10.2 Energy audit of cooling towers
Cooling towers are energy audited to assess present levels of approach and range
against their design values; to identify areas of energy wastage; and to suggest
improvements. During an energy audit, parameters such as those listed below are
measured, using portable instruments:
•
•
•
•
•
•
•
•
Wet bulb temperature of air
Dry bulb temperature of air
Cooling tower inlet water temperature
Cooling tower outlet water temperature
Exhaust air temperature
Electrical readings of pump and fan motors
Water flow rate
Air flow rate
The instruments used and the corresponding parameters measured are listed in
Table M.41.
Table M.41: Instruments and the parameters measured
Instrument used
Parameters measured
Sling hygrometer
Wet bulb and dry bulb air temperature
Temperature indicator with
thermocouple
Water temperature
Flow meter
Water flow rate
Anemometer
Air flow rate
Power analyser
Pump and fan electrical parameters
Various electrical parameters such as kW, kVA, P.F., voltage, current and frequency are
measured using the power analyser. Knowing the percentage loading and power factor
of a motor, it is possible to estimate its operating efficiency from motor characteristic
curves. If efficiency is low, the possibility of replacing it with a new motor may have to
be considered.
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Worksheet: Cooling tower performance
Section
no.
Parameter reference
Units
OPEN FILE
Cooling tower reference
1
1
Dry bulb temperature
°C
2
Wet bulb temperature
°C
3
CT inlet temperature
°C
4
CT outlet temperature
°C
5
Range
°C
6
Approach
°C
7
CT effectiveness
%
8
Average water flow
kg/hr
9
Average air quantity
kg/hr
10
Liquid gas (L/G) ratio
kg water/kg air
11
Evaporation loss
m3/hr
12
CT heat loading
kcal/hr
2
Basic equations used
a) CT Range (°C) = [CW inlet temp (°C) – CW outlet temp (°C)]
b) CT Approach (°C) = [CW outlet temp (°C) – Wet bulb temp (°C)]
c) CT Effectiveness (%) = 100 x (CW temp – CW out temp) / (CW in temp – WB temp)
d) L/G Ratio (kg/water/kg air) = Total CW water flow in CT (kg/hr) / Total air flow in CT (kg/hr)
e) CT heat loading (kcal/hr) = CW flow (m3/hr) x ∆T (°C) x density of water (kg/m3)
f)
CT evaporation loss (CMH) = CW circulation (CMH) x CW Temp. difference across CT in °C rate / 675
g) % Evaporation loss in cooling tower = Evaporation loss in CMH x 100 / CW circulation rate CMH
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M1.11 Refrigeration and air-conditioning
Refrigeration is the process of lowering the temperature of a substance below that of
its surroundings. Process industries are the major users of refrigeration facilities.
Refrigeration is used to remove the heat of chemical reactions; to liquefy gases; to
separate gases by evaporation and condensation; and to purify products by preferential
freeze-out of one component from a liquid mixture. It is also extensively used in airconditioning of plant areas for comfort, process and thermal environment uses, as well
as in hotels, hospitals and office buildings, etc.
M1.11.1 Unit of refrigeration
Refrigeration capacity is normally expressed in tons of refrigeration (TR).
One ton of refrigeration is the amount of heat extracted to produce one ton of ice at
0 °C from water at 0 °C in 24 hours:
1 TR = 210 kJ/min = 50 kcal/min
M1.11.2 Types of refrigeration
There are two popular types of refrigeration system used in industry: vapour
compression and vapour absorption.
Vapour compression refrigeration systems
Figure M.48 shows the vapour compression refrigeration cycle. The refrigerant enters
a compressor at low pressure and at a temperature a few degrees higher than its
boiling point at that pressure. In the compressor, both the temperature and the
pressure of the refrigerant gas rise. The types of compressors normally employed are:
reciprocating, rotary vane, twin screw, single screw, centrifugal, and scroll.
The hot gas from the compressor then goes into the condenser. The gas first cools
from the compressor discharge temperature to the condensing saturation temperature,
giving up its sensible heat. Most of the heat transfer in the condenser (latent heat)
occurs when the refrigerant changes from a gas to a liquid. The types of condensers
used are: water-cooled shell and tube, air-cooled, and evaporative.
The liquid refrigerant then passes to an expansion valve, where its pressure is reduced,
during which some of the liquid flashes off, forming a mixture of low temperature
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Figure M.48 The vapour compression cycle
CONDENSER
high pressure
liquid
discharge
expansion valve
high
pressure
gas
compressor
low pressure liquid
and flash gas
suction
EVAPORATOR
low
pressure
gas
liquid and low temperature vapour. Various types of valves are used: high-pressure float
valves, low-pressure float valves, and thermostatic expansion valves.
The liquid refrigerant passes to the evaporator where it is vaporized at constant
temperature. The refrigerant vapour is then returned to the compressor suction line
and the circuit is complete. Types of evaporators are: direct expansion, flooded shell
and tube, and re-circulation.
Vapour absorption refrigeration
Vapour absorption systems use a heat source instead of the compressor. This is an
economically attractive proposition where waste heat is available. The working
principle is described in Figure M.49 and important facts are listed below:
• The common commercial absorbent/ refrigerant pair is lithium bromide
(L-Br)/water.
• The refrigerant travels from the evaporator to the absorber as a vapour.
• The absorbent has a strong affinity for the refrigerant and absorbs it, creating a
vacuum (–0.2 psia in a L-Br system); the heat is removed by cooling water.
• The refrigerant–absorbent solution is then pumped towards the condenser,
passing through the generator.
• Heat applied to the generator causes the refrigerant to vaporize, leaving behind
the absorbent liquid.
• The refrigerant vapour, now separated from the liquid absorbent, travels to the
condenser.
• The liquid absorbent is re-circulated to the absorber through the regulating valve,
bringing it down to the evaporator pressure.
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Figure M.49 The vapour absorption cycle
GENERATOR
condenser
weak
solution
throttling
valve
waste heat/direct fired
regulating
valve
strong
solution
ABSORBER
pump
evaporator
cooling water
M1.11.3 Energy efficiency evaluation
Once a refrigeration system has been installed, its operating efficiency and overall
running costs will be largely determined by the effectiveness of day-to-day monitoring.
The commonly used figures for comparison of refrigeration systems are: the Coefficient
of Performance (COP), Energy Efficiency Ratio (EER), and Specific Power Consumption
(SPC).
If both the refrigeration effect (heat removed from evaporator) and the work done by
the compressor (or the input power) are in the same units (TR or kcal/hr or kW or
Btu/hr), the ratio is:
COP =
Refrigeration effect
Power supplied
If the refrigeration effect is expressed in kcal/hr and the work done in watts, the ratio is:
EER =
Refrigeration effect (Btu/hr)
Power supplied (Watts)
The other commonly used and easily understood useful figure is Specific Power
Consumption (SPC):
SPC =
Power consumption(kW)
Refrigeration effect (TR)
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M1.11.4 Estimation of capacity of refrigeration system and
air-conditioning systems
The capacity of the liquid chilling system can be estimated if water/brine flows and
chiller inlet/outlet temperatures are known:
Heat load (TR) =
Q x d x s x (Tin – Tout)
3023
Where: Q = flow (m3/hr)
d = density (kg/m3)
s = specific heat (kcal/kg/°C)
Tin = temperature at inlet (°C)
Tout = temperature at outlet (°C)
Method of capacity estimation for systems having hot wells and cold wells to
balance primary and secondary refrigerants
For this method of estimation of refrigeration capacity, the secondary pump (process
side) should be switched off for about 30 to 60 minutes. The compressor and primary
pumps should then be operated and the time to drop the temperature of the
secondary refrigerant in the hot and cold well by about 5 °C should be noted.
Cooling capacity =
Where:
V x d x s x dT
(3023 x t)
+
Primary power pump (kWt)
3.51
V = volume of the secondary refrigerant in the hot and cold well (m3)
d = density of the secondary refrigerant (kg/m3)
∆T = drop in temperature (°C)
t = time taken (hours)
s = specific heat of the secondary refrigerant (kcal/kg/°C)
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M1.11.5 Heat load calculation for centralized air-conditioning systems
Heat load (TR) =
Q x d x (hin – hout)
4.18 x 3023
Where: Q = flow, m3/hr (can be measured with an anemometer)
D = density, kg/m3 (1.2 kg/m3 approx.)
hin = enthalpy at AHU inlet, kJ/kg
hout = enthalpy at AHU outlet, kJ/kg
(Dry bulb and wet bulb temperatures can be measured at the air-handling unit (AHU)
inlet and outlet; this data can be used with a psychrometric chart to determine the
enthalpy of air at the AHU inlet and outlet.)
The power consumption for these systems can be measured using a portable power
meter or an energy meter—specific power consumption can then be calculated.
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Worksheet: Refrigeration and AC system rated specifications
Section
no.
Refrigeration compressor
Make
2
Type
3
Capacity (of cooling)
4
Chiller:
–
b) Diameter of tubes
m
c) Total heat transfer area
m2
e) Chilled water temp. difference
2
3
4
TR
a) No. of tubes
d) Chilled water flow
5
Machines reference
Units
1
1
OPEN FILE
m3/hr
°C
Condenser:
a) No. of tubes
b) Diameter of tubes
c) Total heat transfer area
m
d) Condenser water flow
m3/hr
e) Condenser water temp. diff.
6
Chilled water pump:
a) Nos.
7
°C
–
b) Capacity
m3/hr
c) Head developed
mWC
d) Rated power
kW
e) Rated efficiency
%
Condenser water pump:
a) Nos.
–
b) Capacity
m3/hr
c) Head developed
mWC
d) Rated power
kW
e) Rated efficiency
%
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Worksheet: Operating parameters
Section
no.
Parameter reference
OPEN FILE
Refrigeration compressor reference
Units
1
1
Chilled water flow (using a flow meter or
assessed by level difference)
m3/hr
2
Chilled water pump motor input power
kW
3
Chilled water pump suction pressure
kg/cm2g
4
Chilled water pump discharge pressure
kg/cm2g
5
Chiller water inlet temperature to chiller
°C
6
Chiller water outlet temperature from
chiller
°C
7
Condenser water inlet temperature
°C
8
Condenser pump suction pressure
kg/cm2
9
Condenser pump discharge pressure
kg/cm2
10
Condenser water outlet temperature
°C
11
Chiller (evaporator) outlet refrigerant
temperature
°C
12
Refrigerant pressure
13
Condenser inlet refrigerant temperature
14
Refrigerant pressure
15
Actual cooling capacity [(1)*(6-5)/3024]
TR
16
COP [11/(10-11)]
–
17
Compressor motor input power
18
Specific energy consumption
19
Input power to CT fan
kW
20
Input power to chilled water pumps in
operation
kW
21
Input power to condenser water pumps
in operation
kW
22
Overall system specific power
consumption [(2+17+19+20)/15]
Cleaner Production – Energy Efficiency Manual
2
3
4
kg/cm2 (or psig)
°C
kg/cm2 (or psig)
kW
kW/TR
kW/TR
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M1.12 Lighting systems basics
A lighting system comprises all of the components necessary to deliver a desired level
of space illumination. It includes components such as switches to control power,
wiring, voltage stabilizers, lighting luminaires, fixtures, control gear, shade of walls,
shape of room, etc. A lighting system is shown in Figure M.50.
Figure M.50 A lighting system
wiring
ceiling
lighting
controls
fixture
wall
wall
lens or diffuser
switch
desired area of illumination
work surface
floor
electricity in
Periodic maintenance of the lighting system installed on the shop floor has a profound
impact on the energy consumed. In many industrial lighting systems, the fittings act
as dust traps. If they are not cleaned periodically, they will collect more dust resulting
in lower illumination.
Efficient lamps and luminaires can not only reduce maintenance costs, they can even
lower power consumption. For instance, use of twin-lamp fluorescent fittings with
polystyrene diffusers can provide the same degree of lighting with lower wattage
consumption. Similarly, high pressure sodium lamps provide energy savings of up to
80 per cent compared to high wattage tungsten filament lamps.
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In some systems, electronic control can provide energy conservation of around 25 per
cent at near unity power factor. Automatic switch off of lights can be provided when
they are not required. Solar or mechanical timer switches can be used to turn off
artificial lighting as soon as the optimum light level is reached.
M1.12.1 Choice of lighting
The following guidelines will help in choosing lighting:
Choose
the right light
which is positioned
where it is needed
used only
when it is needed
for
as long as it is need
and
at the illumination level needed.
Search for savings
With so many different types of lighting on the market, levels of efficiency and
performance must be known if the best choice is to be made. Table M.42 gives the
luminous efficiency of various lamp sources.
Table M.42: Luminous efficiencies
Section no.
Light sources
Efficiency
(lumens/watt)
Average working
life (hours)
1
Incandescent lamps
15
1 000
2
Cool daylight fluorescent tubes
50–60
5 000
3
White fluorescent tubes
60–85
5 000
4
High pressure mercury vapour lamps
80 W
36
5 000
125 W
41
5 000
400 W
52
5 000
70 W
82
10 000
250 W
100
10 000
400 W
117
10 000
10 W
100
10 000
18 W
175
10 000
25
5 000
60–85
5 000
5
6
High pressure sodium lamps
Low pressure sodium lamps
7
Tungsten halogen
8
Metal halide
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The table shows ranges of efficiency and lamp-life. As can be seen, the lighting
efficiency (lumens per watt) of a low-pressure sodium lamp is many times
(10–17 times) greater than that of an incandescent (tungsten-filament) lamp. It should
also be noted that, in general, the efficiency of a specific lamp type is higher for higher
power lamps.
Fittings should always be suitable for the maximum wattage of lamp with which they
are used. Higher wattage of lamps will produce more heat and could damage the
fittings or shade and may even cause a fire.
Fluorescent tube lights are preferred to general lighting service (GLS) lamps because,
for the same amount of electricity consumption, they produce four times the amount
of light obtainable from GLS lamps. The tubes last much longer, as they have a life
of 6 000 to 7 000 hours, although frequent switching on and off shortens this
substantially.
Today, so-called ‘electricity saving’ bulbs can be used as a substitute for tungsten
filament bulbs. These are compact fluorescent tubes which can be screwed into the
existing conventional bulb socket. These compact fluorescent bulbs consume about 80
per cent less electricity than a conventional bulb while producing the same amount of
light. They also have a life about 6 to 8 times longer.
Table M.43 shows norms of illuminance required for various work stations.
M1.12.2 Control of lighting
Even with efficient lamps and luminaires, energy used for lighting can be wasted in
several ways. In general, people usually turn lighting on only when they need it, but
cannot be relied upon to turn it off when daylight would provide adequate light, or
when rooms are unoccupied. The ideal solution would be to provide a manual switch
and some form of control for switching off.
A further source of unnecessary use results from the common practice of controlling
large areas of lighting with small numbers of switches, or by having confusing
switch layouts so that individual requirements can only be met by turning on many
luminaires. Controls are a very effective way of reducing lighting costs, but before
incurring significant capital costs, it is suggested that occupancy patterns and
behaviour be studied.
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Table M.43: Luminous efficiencies
Lighting systems
General lighting
for rooms and
areas used
infrequently
and/or casually
or for simple
visual tasks.
General lighting
for Interiors
Illuminance (lux)
20
Minimum service illuminance in exterior circulation areas
30
Outdoor stores and stockyards
50
Exterior walkways and platforms, indoor tasks, car parks
75
Docks and quays
100
Theatres and concert halls, hotel bedrooms, bathrooms
and corridors
150
Circulation areas in industry, stores and stock rooms
200
Minimum service illuminance for a task (visual tasks not
requiring any perception of detail)
300
Rough bench and machine, motor vehicle assembly, printing
machine rooms, general offices, shops and stores, retail sales
areas
500
Medium bench and machine, motor vehicle assembly,
printing machine rooms, general offices, shops and stores,
retail sales areas
750
Proofreading, general drawing office, offices with business
machines
1 000
Fine bench and machine work, office machine assembly,
colour work and critical drawing tasks
1 500
Very fine bench and machine work, instrument and small
precision mechanism assembly, electronic components
gauging and inspection of small intricate parts; may be
partly provided by local lighting
2 000
Minutely detailed and precise work, e.g. very small parts of
instruments, watch making and engraving, operating area
in operating theatres—2 000 lux minimum
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Manual controls
Switch arrangements should at least permit individual rows of luminaires parallel and
nearest to window walls to be controlled separately.
Switches should be as near as possible to the luminaires which they control. One simple
method which has been used effectively is the pull-cord operating ceiling switches
adjacent to each luminaire, or pull-chord switches with timer controls so that the lamp
automatically switches off after a pre-set period.
Automatic controls
a) Photo-electric controls
Photo-electric control of lighting can ensure that lighting is turned off when
daylight alone provides the required illuminance. For example, a photo-electric
sensor could respond to the exterior illuminance at the work place.
b) Time controls
If the occupation of a building effectively ceases at a fixed hour every working
day, it may be worth installing a time switch so that most of the lighting is
switched off at that time.
c) Mixed control systems
Switch control can give considerable energy savings. For instance, a time control
system can switch off all selected lights for fixed period in the day, but personal,
local override (switch on) controls can be provided.
This general principle is well suited to multi-occupant spaces such as group offices.
An idea of wastage of electrical energy due to unnecessary lighting can be obtained
from Table M.44.
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Table M.44: Loss in electrical energy as a result of misuse or wastage
and its value per year
Consumption (in kWh)
Value* (US$)
40 W Tube light
15
0.88
60 W Ceiling fan
22
1.26
100 W Bulb
37
2.14
250 W Air cooler
91
5.30
450 W HPMV lamp
146
8.51
500 W Incandescent lamp
183
10.03
1 HP Electric motor
137
7.95
1 ton Window A.C.
445
25.86
1.5 ton Window A.C.
602
35.03
1 ton Water cooler
308
17.91
Item
* Cost of electricity is considered as US$0.055 per kWh
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Module 2:
Energy efficient technologies
Efficient use of energy is an on-going process. Research and development (R&D)
around the world is constantly leading to development of new processes and devices.
The basic objective of major R&D efforts on energy systems is to cut down on waste,
whether in the form of flue gases; heat lost through conduction, convection or
radiation; or to improve efficient use of electrical energy. This chapter presents some
generic examples—most of them well proven—to increase readers’ awareness of
energy systems already available or likely to be so in the future.
M2.1 New electrical technologies
● HVDC transmission system
Reduces distribution losses from 18–22 per cent to 8–10 per cent. Relevant to
utility companies, thermal power stations, etc.
● Steam-based cogeneration plant (back pressure/topping/
extraction turbine)
The primary fuel requirement to meet heat and power demand is substantially
reduced. Relevant to large process industries such as sugar, pulp and paper,
chemical and petrochemicals, etc.
● Combined cycle based cogeneration plants for industries
Higher system efficiency: 70–80 per cent in the cogeneration mode, compared to
25–36 per cent for conventional thermal stations. Obtained by integration of
thermal and electrical energy from the same source. Relevant to natural gas
consuming process industries with steam demand above 10 TPH.
● Energy efficient DG sets
Lower rpm and higher efficiency than conventional DG sets.
● High efficiency fans and pumps
High efficiency centrifugal pumps and fans are now available from most leading
pump and fan manufacturers. Efficiency range: 75–83 per cent. Relevant to
almost all industrial units.
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● Maximum demand controllers
Load factor improvement and peak demand reduction. Relevant to
industrial/commercial establishments/utilities.
● Automatic power factor controllers
Power factor improvement. Relevant to all industries.
● High efficiency motors
Motors with efficiencies of 92–96 per cent, often with a 10 year performance
guarantee, are available on the market from all leading motor manufacturers.
They are capable of working at temperatures as high as 80–100 °C.
● Static variable speed drives, frequency drives, inverters
Thyristor control systems where speed is controlled by varying the voltage and
frequency. Higher efficiency at partial loads. Relevant to medium and large
industries and power plants.
● Energy efficient fluorescent lighting system (fluorescent lamps, sodium
vapour lamps, compact fluorescent lamps)
Higher lumens per watt. Relevant to shop floor working bays, buildings, street
lights and yard lighting.
● Electronic regulators for fans
Reduction in energy loss during part load operation. Relevant to industrial offices,
technical buildings, domestic applications.
● Solid-state soft starters
Solid-state thyristor control systems. Applied voltage is varied with load on motor.
Higher efficiency at part loads. Relevant to conveyor belts, inching loads and
equipment operating frequently with part loads in medium and large industries.
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M2.2 Boiler and furnace technologies
● Air preheater
Improvement in thermal efficiency by preheating the combustion air with waste
heat available in flue gases.
i) Metallic recuperator/regenerator
Preheat to 350 °C. Relevant to large boilers, small furnaces.
ii) Metallic recuperator (special steels)
Preheat to 700 °C. Relevant to furnaces, rolling and soak pits, glass furnaces,
ceramic kilns.
iii) Ceramic recuperator/regenerator
Preheat to 1 000 °C. Relevant to integrated steel plants, glass tank furnaces.
● Film burners
Higher turn down to 7:1, reduced excess air level. Relevant to industrial boilers
and furnaces, reheating furnaces heat treatment furnaces, etc.
● Low excess air burners (0–5% x suction air)
Improvement in system efficiency. Relevant to industrial boilers, furnaces, kilns.
● Regenerative burners
Higher flame temperature and improved heat transfer. Relevant to industrial
furnaces and kilns.
● Fluidized bed boilers
Efficient combustion of inferior, high-ash-content coals and washery rejects.
● Waste heat boilers
Steam generation with waste heat available in flue. Relevant to sulphuric acid,
chemical, petrochemical, fertilizer and steel plants.
● Closed condensate recovery system
Efficient condensate recovery system. Relevant to all process and chemical
industries where indirect steam is used.
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Module 2: Energy efficient technologies
● High efficiency steam turbines
High efficiency impulse steam turbines of 5 MW and less have been developed
with efficiencies as high as 70 per cent. The back pressure class of turbines can be
used in designing cogeneration systems for industries. This would not only help in
reducing purchased energy but also in providing valuable power in cases of grid
power shortage.
● Innovation in cogeneration system
The steam based cogeneration system (bottoming cycle) may be suitable where
steam to power ratio is high. If steam to power ratio is low, gas turbine based
cogeneration systems (topping cycle or combined cycle) are more appropriate. The
latter system can absorb steam fluctuations to a certain level without sacrificing
overall system efficiency. A recent development is based on the ‘Cheng’ cycle where
any excess steam is superheated and injected back into the gas combustor. This
system allows maximum electric power generation with no or less process steam or
maximum power, as well as process steam generation simultaneously.
● On-line plugging of leaks
Leak prevention in steam and compressed air systems. Relevant to continuous
industries, power stations.
● Ceramic fibre
Reduction in heat storage and radiation losses, due to low thermal mass. Relevant
to furnaces, kilns, fired heaters, heaters, ovens, heat treatment furnaces, etc.
● Luminous wall furnace
High emissivity refractory coatings—a development of the US Space Programme—
prevent high temperature of refractory linings of furnaces. The results are 10–15 per
cent fuel savings; increased furnace structure radiation; improved temperature
uniformity; and increased working life of refractory and metallic components.
● Dynamic insulation
Air or other fluid is forced through the insulating material to oppose (contraflux)
or enhance (proflux) the transmission of heat, as required. It has additional
benefits, e.g. building insulation, pre-heated supply of filtered fresh air is readily
available. Can be used for boiler and furnace as pre-heated combustion air.
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M2.3 Heat upgrading systems
● Organic rankine cycle
Utilizing low grade waste heat for generation of power in a turbine cycle
operating with organic liquids. Relevant to cement industry, large chemical and
petrochemical plants and refineries.
● Thermo compressor
Enables utilization of low grade energy by using thermal energy in higher
pressure steam in conjunction with vapours. Relevant to process industries such as
sugar, food processing, dairy, chemicals and petrochemicals.
● Vapour absorption refrigeration system
Steam powered or by tapping low grade waste streams (150–250 °C) provides
absorption cycle refrigeration using lithium bromide or ammonia. Relevant to
process and engineering industry.
● Mechanical vapour recompression system
The low grade steam from evaporators, driers, distillation columns is upgraded.
Relevant to food processing, chemical and petro-chemicals industries.
● Heat pipes
Waste heat recovery from process streams at lower and medium temperature
levels. Faster heat transfer rate, compact design. Relevant to process chemical
industries. The heat pipe acts like a super-heat-conductor: 1 000 times more
effective than a solid copper bar of the same size.
● Thermal energy wheels
Energy wheels are compact and are available not only for recovering heat from
centrally heated and cooled buildings but also for recovering heat from boiler and
furnaces at high temperature. With the use of glass ceramic materials, they can
now withstand temperatures as high as 1 250 °C.
● Heat pumps
Heat pumps enable heat to be upgraded and transferred to a point of use. They
cut down energy consumption and are a viable alternative to electrical resistance
heating, as their coefficient of performance is in the 3–5 range. Heat pumps also
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Part 2 Technical modules
Module 2: Energy efficient technologies
utilize low temperature waste heat sources and upgrade them to temperature
levels at which they become useful.
● Condensing heat exchanger
Extracts not only sensible but also latent heat of water vapour in flue gases of
boilers and furnaces. Condensing heat exchangers comprise Teflon coated
heat exchanger surfaces resistant to acidic corrosion, thereby allowing the flue
gases to be cooled to very near ambient temperature, thus increasing the
efficiency of boilers substantially—to over 92 per cent in the case of oil and
gas firing systems.
● Special design heat exchanger
Heat transfer rate can be dramatically increased at sonic velocity. Based on this
principle, a special design of heat exchanger with much higher overall heat
transfer coefficients than those attainable in shell and tube type heat exchangers
has been developed. These devices are relatively maintenance free. Heat
exchangers with spherical matrices and helical inserts in the tubes have been
developed, reducing heat exchanger surfaces by 25–30 per cent.
● Microprocessor based system
More precise control of critical parameters. Relevant to boilers, furnaces, utilities,
distillation columns, process plants, power plants.
M2.4 Other utilities
● Air curtains
Reduction in air infiltration in air conditioning or space heating systems. Relevant
to textile and man-made fibres, cold storage plants, air conditioned buildings, etc.
● Flat belt
Modern flat belts have transmission efficiency of the order of 95–98 per cent as
compared to V-belt transmission efficiency of 80–85 per cent. Improved efficiency
is due to less friction losses between belt and pulley as well as absence of
wedging. Relevant to pulley driven drives.
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Module 2: Energy efficient technologies
● Industrial drying by electromagnetic radiation
Infrared, microwave, radio frequency and ultraviolet radiation are now being used
for drying purposes. Drying efficiencies increase by as much as 50–70 per cent.
All these techniques, are useful for particular types of product drying, e.g.
microwave for food processing; radio frequency for drying of paper, yarn
packages, etc.; infrared for curing of adhesives; ultraviolet for paint curing.
Cleaner Production – Energy Efficiency Manual
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Part 3
Tools and resources
Part 3 provides the following tools and resources:
• Checklists of procedures that improve energy
efficiency and safety in energy-using equipment.
• Thumb Rules, for rapid assessment of the efficiency
of major energy systems.
• A list of Measuring Instruments that can be used
to quantify and monitor energy flows.
• Greenhouse Gas Emissions Indicator: a spreadsheetbased calculator designed to help governments and
industry estimate greenhouse gas emissions.
• Information Resources to help in further
development of CP-EE and other energy-related
initiatives.
• Conversion Tables to provide a standardized
approach to energy measurements and calculations.
• A list of Acronyms and Abbreviations used.
Contents listing
Part 1 CP-EE methodology
Part 2 Technical modules
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Part 3 Tools and resources
A: Checklists for enhancing efficiency
and safety of energy equipment
A.1 Fuel oil checklists
● Daily checks
i. Oil temperature at the burner
ii. Oil/steam leakages
● Weekly tasks
i. Cleaning of all filters
ii. Draining of water from all tanks
● Yearly jobs
i. Cleaning of all tanks
● Troubleshooting hints
Remember!
Spilled oil is irretrievable.
Plug all leaks.
Impurities in furnace oil
affect combustion.
Filter oil in stages.
Oil has to be preheated
to obtain the right
viscosity for supply to
the burner. It is essential
to provide adequate
preheater capacity.
Oil not pumpable
• Viscosity too high
• Blocked lines and filters
• Sludge in oil
• Leak in oil suction
• Vent pipe choked
Blocking of strainers
• Sludge or wax in oil
• Heavy precipitated compounds in oil
• Rust or scale in tank
• Carbonization of oil due to excessive heating
Excess water in oil
• Water delivered along with oil
• Leaking manhole
• Seepage from underground tank
• Ingress of moisture from vent pipe
• Leaking heater steam coils
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A: Checklists for enhancing efficiency and safety
Pipeline plugged
• Sludge in oil
• High viscosity oil
• Foreign materials such as rags, scale and wood splinters in line
• Carbonization of oil
A.2 Combustion checklists and troubleshooting
Step by step procedure for efficient operation of burners
● Start up
• Check for correct sized burner/nozzle.
• Establish air supply first (start blower). Ensure no vapour/gases are present
before light up.
• Ensure a flame from a torch or other source is placed in front of the nozzle.
• Turn ON the (preheated) oil supply (before start-up, drain off cold oil).
● Operations
• Check for correct temperature of oil at the burner tip (consult viscosity vs.
temperature chart).
• Check air pressure for LAP burners (63.5 cm to 76.2 cm w.c. air pressure is
commonly adopted).
• Check for oil drips near burner.
• Check for flame fading/flame pulsation.
• Check positioning of burner (ensure no flame impingement on refractory walls
or charge).
• Adjust flame length to suit the conditions (ensure flame does not extend
beyond the furnace).
● Load changes
• Operate both air and oil valves simultaneously (For self-proportioned burner,
operate the self-proportioning lever. Do not adjust valve only in oil line).
• Adjust burners and damper for a light brown (hazy) smoke from chimney and
at least 12 per cent CO2.
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Part 3 Tools and resources
A: Checklists for enhancing efficiency and safety
Checklist 1: Troubleshooting chart for combustion
Complaint
Causes and remedies
1. Starting difficult
i.
ii.
iii.
iv.
v.
vi.
No oil in the tank.
Excess sludge and water in storage tanks.
Oil not flowing due to high viscosity/low temperature.
Choked burner tip.
No air.
Strainers choked.
2. Flame goes out
or splutters
i.
ii.
iii.
iv.
v.
Sludge or water in oil.
Unsteady oil and air pressures.
Too high a pressure for atomizing medium which tends to blow out flame.
Presence of air in oil line. Look for leakages in suction line of pump.
Broken burner block, or burner without block.
3. Flame flashes
back
i.
4
i.
ii.
iii.
iv.
v.
vi.
Smoke and soot
Oil supply left in ‘ON’ position after air supply cut off during earlier
shut off.
ii. Too high a positive pressure in combustion chamber.
iii. Furnace too cold during starting to complete combustion (when
temperature rises, unburned oil particles burn).
iv. Oil pressure too low.
Insufficient draft or blower of inadequate capacity.
Oil flow excessive.
Oil too heavy and not preheated to the required level.
Suction air holes in blower plugged.
Chimney clogged with soot/damper closed.
Blower operating speed too low.
5. Clinker on
refractory
i.
6. Cooking of fuel
in burner
i.
ii.
iii.
iv.
7. Excessive fuel
oil consumption
i. Improper ratio of oil and air.
ii. Burner nozzle oversized.
iii. Excessive draft.
iv. Improper oil/air mixing by burner.
v. Air and oil pressure not correct
vi. Oil not preheated properly.
vii. Oil viscosity too low for the type of burner used.
viii. Oil leaks in oil pipelines/preheater.
ix Bad maintenance (too high or rising stack gas temperature).
Flame hits refractory because combustion chamber is too small or burner
is not correctly aligned.
ii. Oil dripping from nozzle.
iii. Oil supply not ’cut off’ before the air supply during shut-offs.
Nozzle exposed to furnace radiation after shut-off.
Burner fed with atomizing air over 300 °C.
Burner block too short or too wide.
Oil not drained from nozzle after shut off.
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Part 3 Tools and resources
A: Checklists for enhancing efficiency and safety
● Shut down
• Close oil line first.
• Shut the blower after a few seconds (ensure gases are purged from
combustion chamber).
• Do not expose the burner nozzle to the radiant heat of the furnace. (When oil
is shut off, remove burner/nozzle or interpose a thin refractory between nozzle
and furnace).
Important!
Burners should be
dismantled and cleaned
periodically, preferably
once per shift
(always keep spare
burners ready).
A.3 Boilers
● Periodic tasks and checks outside of the boiler
• All access doors and platework should be maintained air tight with effective
gaskets.
• Flue systems should have all joints sealed effectively and be insulated where
appropriate.
• Boiler shells and sections should be effectively insulated. Is existing insulation
adequate? If insulation was applied to boilers, pipes and hot water cylinders
several years ago, it is almost certainly too thin even if it appears in good
condition. Remember, it was installed when fuel costs were much lower.
Increased thickness may well be justified.
• At the end of the heating season, boilers should be sealed thoroughly, internal
surfaces either ventilated naturally during the summer or very thoroughly
sealed with tray of desiccant inserted. (Only applicable to boilers that will
stand idle between heating seasons).
● Safety and monitoring
• Explosion relief doors should be located and/or guarded to prevent injury to
personnel.
• Safety valves should have self-draining discharge pipes terminating in a safe
location that can be easily observed.
• Installed instruments should be maintained in working order and positioned
where they can be seen easily.
• Provide test points with removable seal plugs in the flue from the boiler, to
enable flue gas combustion tests to be carried out.
• Do you check boiler combustion conditions periodically? CO2 or O2 readings
and exit temperatures can be obtained using relatively inexpensive portable
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Part 3 Tools and resources
•
•
•
•
•
•
•
•
•
•
A: Checklists for enhancing efficiency and safety
equipment. Adjusting combustion by optimizing the fuel/air ratio costs
nothing and can make substantial savings.
Do you monitor exit temperatures? There should be a steady rise between boiler
flue-duct cleaning intervals and this should not be allowed to exceed, say, 40 °C.
Try to clean based on temperature indications, rather than on the calendar.
Some older sectional boilers and certain smoke tube type shell boilers can be
fitted with baffles or ‘retarders’ to improve heat transfer and therefore
efficiency. Have you checked whether this is possible on your boilers?
Is there adequate ventilation to give sufficient combustion air for the boilers?
Insufficient ventilation can, at the least, lead to poor combustion and at worst
could enable dangerous gases to accumulate in the boiler house.
Check the water side of the boiler periodically for corrosion or scale formation.
Do you know the actual load on the boiler? A rough guide can be obtained from
oil or gas burners by timing the on/off periods, or the time on full flame for fully
modulating burners. With underfeed coal stokers, see what is the lowest speed
that will cope with demand, or put on full speed and time the on/off periods.
If the boiler is oversized, either permanently or during part of the year, consider
whether it can be de-rated during those periods by adjusting burners or stokers
to operate only up to a top limit that is lower than full maximum output. Try to
keep the boiler operating for the highest possible percentage of time.
Is there adequate boiler/burner control to match the load and prevent
excessive and unnecessary cycling?
If you have more than one boiler, do you isolate boilers which are in excess of
load requirements? Automatic flue isolation should be used, if possible, to
prevent excessive purging by chimney draught during idle periods.
In multi-boiler hot water installations, are the boilers hydraulically balanced to
ensure proper sharing of the load?
Consider fitting heat exchangers/recuperators to flues; these can recover
5–7 per cent of energy available.
● Boilers: extra items for steam-raising and hot-water boilers
• Check regularly for build-up of scale or sludge in the boiler vessel or check
TDS of boiler water each shift, but not less than once per day. Impurities in
boiler water are concentrated in the boiler and the concentration has limits
that depend on type of boiler and load. Boiler blow down should be
minimized, but consistent with maintaining correct water density. Recover
heat from blow down water.
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Part 3 Tools and resources
A: Checklists for enhancing efficiency and safety
• With steam boilers, is water treatment adequate to prevent foaming or priming
and consequent excessive carry over of water and chemicals into the steam
system?
• For steam boilers: are automatic water level controllers operational? The
presence of inter-connecting pipes can be extremely dangerous.
• Have checks been made regularly on air leakages round boiler inspection doors,
or between boiler and chimney? The former can reduce efficiency; the latter can
reduce draught availability and may encourage condensation, corrosion and
smutting.
• Combustion conditions should be checked using flue gas analysers at least
twice per season and the fuel/air ratio should be adjusted if required.
• Both detection and actual controls should be labelled effectively and checked
regularly.
• Safety lock-out features should have manual re-set and alarm features.
• Test points should be available, or permanent indicators should be fitted to oil
burners to give operating pressure/temperature conditions.
• With oil-fired or gas-fired boilers, if cables of fusible link systems for shutdown
due to fire or overheating run across any passageway accessible to personnel,
they should be fitted above head level.
• The emergency shut down facility is to be situated at exit door of the boiler
house.
• In order to reduce corrosion, steps should be taken to minimize the periods
when water return temperatures fall below dew point, particularly on oil and
coal fired boilers.
• Very large fuel users may have their own weighbridge and so can operate a
direct check on deliveries. If no weighbridge exists, do you occasionally ask
your supplier to run via a public weighbridge (or a friendly neighbour with a
weighbridge) just as a check? With liquid fuel deliveries do you check with the
vehicle’s dipsticks?
• With boiler plant, ensure that the fuel used is correct for the job. With solid
fuel, correct grading or size is important, and ash and moisture content should
be as the plant designer originally intended. With oil fuel, ensure that viscosity
is correct at the burner, and check fuel oil temperature.
• The monitoring of fuel usage should be as accurate as possible. Fuel stock
measurements must be realistic.
• With oil burners, examine parts and repairs. Burner nozzles should be changed
regularly and cleaned carefully to prevent damage to burner tip.
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Part 3 Tools and resources
A: Checklists for enhancing efficiency and safety
• Maintenance and repair procedures should be reviewed especially for burner
equipment, controls and monitoring equipment.
• Regular cleaning of heat transfer surfaces maintains efficiency at the highest
possible level.
• Ensure that the boiler operators are conversant with the operational
procedures, especially any new control equipment.
• Have you investigated the possibility of heat recovery from boiler exit gases?
Modern heat exchangers/recuperators are available for most types and sizes of
boiler.
• Do you check feed and header tanks for leaking make up valves, correct
insulation or loss of water to drain?
• The boiler plant may have originally been provided with insulation by the
manufacturer. Is this still adequate with today’s fuel costs? Check on optimum
thickness.
• If the amount of steam produced is quite large, invest in a steam meter.
• Measure the output of steam and input of fuel. The ratio of steam to fuel is
the main measure of efficiency at the boiler.
• Use the monitoring system provided: this will expose any signs of
deterioration.
• Feed water should be checked regularly for both quantity and purity.
• Steam meters should be checked occasionally as they deteriorate with time
due to erosion of the metering orifice or pilot head. It should be noted that
steam meters only give correct readings at the calibrated steam pressure.
Recalibration may be required.
• Check all pipe work, connectors and steam traps for leaks, even in inaccessible
spaces.
• Pipes not in use should be isolated and redundant pipes disconnected.
• Is someone designated to operate and generally look after the installation?
This work should be included in their job specification.
• Are basic records available to that person in the form of drawings, operational
instructions and maintenance details?
• Is a log book kept to record details of maintenance carried out, actual
combustion flue gas readings taken, fuel consumption at weekly or monthly
intervals, and complaints made?
• Ensure that steam pressure is no higher than need be for the job. When night
load is materially less than day load, consider a pressure switch to allow
pressure to vary over a much wider band during night to reduce frequency of
burner cut-out, or limit the maximum firing rate of the burner.
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Part 3 Tools and resources
A: Checklists for enhancing efficiency and safety
• Examine the need for maintaining boilers in standby conditions—this is
often an unjustified loss of heat. Standing boilers should be isolated on the
fluid and gas sides.
• Keep a proper log of boiler house activity so that performance can be
measured against targets. When checking combustion, etc. with portable
instruments, ensure that this is done regularly and that load conditions are
reported in the log: percentage of CO2 at full flame/half load, etc.
• Have the plant checked to ensure that severe load fluctuations are not caused
by incorrect operation of auxiliaries in the boiler house, for example, ON/OFF
feed control, defective modulating feed systems or incorrect header design.
• Have hot water heating systems been dosed with an anti-corrosion additive
and is this checked annually to see that concentration is still adequate? Make
sure that this additive is NOT put into the domestic hot water heater tank, it
will contaminate water going to taps at sinks and basins.
• Recover all condensate where practical and substantial savings are possible.
● Boiler rooms and plant rooms
• Ventilation openings should be kept free and clear at all times and the
opening area should be checked to ensure this is adequate.
• Plant rooms should not be used for storage, airing or drying purposes.
• Is maintenance of pumps and automatic valves in accordance with the
manufacturers’ instructions?
• Are run and standby pump units changed over approximately once per month?
• Are pump isolating valves provided?
• Are pressure/heat test points and/or indicators provided each side of the
pump?
• Are pump casings provided with air release facilities?
• Are moving parts (e.g. couplings) guarded?
• Ensure that accuracy of the instruments is checked regularly.
• Visually inspect all pipe work and valves for any leaks.
• Check that all safety devices operate efficiently.
• Check all electrical contacts to see that they are clean and secure.
• Ensure that all instrument covers and safety shields are in place.
• Inspect all sensors, make sure they are clean, unobstructed and not exposed to
unrepresentative conditions, for example temperature sensors must not be
exposed to direct sunlight nor be placed near to hot pipes or process plant.
• Ensure that only authorized personnel have access to control equipment.
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Part 3 Tools and resources
A: Checklists for enhancing efficiency and safety
• Each section of the plant should operate when essential, and should preferably
be controlled automatically.
• Time controls should be incorporated and operation of the whole plant
should, preferably, be automatic.
• In multiple boiler installations, boilers not required to be available should be
isolated on the water side and—if safe and possible—on the gas side too.
Make sure boilers cannot be fired.
• Isolation of flue system (with protection) also reduces heat losses.
• In multiple boiler installations the lead/lag control should have a change round
facility.
• Where possible, any reduction in the system operating temperature should be
made by devices external to the boiler, the boiler plant operating in a normal
constant temperature range.
● Water and steam
• Water fed into the boilers must meet the specifications given by the
manufacturers. The water must be clear, colourless and free from suspended
impurities.
• Hardness nil. Max. 0.25 ppm CaCO3.
• pH of 8 to 10 retard forward action or corrosion. pH less than 7 speeds up
corrosion due to acidic action.
• Dissolved O2 less than 0.02 mg/l. Its presence with SO2 causes corrosion problems.
• CO2 level should be kept very low. Its presence with O2 causes corrosion,
especially in copper and copper bearing alloys.
• Water must be free from oil—it causes priming.
● Boiler water
• Water must be alkaline—within 150 ppm of CaCO3 and above 50 ppm of
CaCO3 at pH 8.3.
• Alkalinity number should be less than 120.
• Total solids should be maintained below the value at which contamination of
steam becomes excessive, in order to avoid cooling over and accompanying
danger of deposition on super heater, steam mains and prime movers.
• Phosphate should be no more than 25 ppm P2 O5.
• Make up feed water should not contain more than traces of silica. There must
be less than 40 ppm in boiler water and 0.02 ppm in steam, as SiO2. Greater
amounts may be carried to turbine blades.
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Part 3 Tools and resources
A: Checklists for enhancing efficiency and safety
Table A.1: Maximum boiler water concentrations recommended
by American Boiler Manufacturers Association
Boiler steam pressure (ata)
Maximum boiler water concentration (ppm)
0–20
3 500
20–30
3 000
30–40
2 500
40–50
2 000
50–60
1 500
60–70
1 250
70–100
1 000
• Water treatment plants suitable for the application must be installed to ensure
water purity, and chemical dosing arrangement must be provided to further
control boiler water quality. Blow downs should be resorted to when
concentration increases beyond the permissible limits stipulated by the
manufacturers.
• Alkalinity not to exceed 20 per cent of total concentration. Boiler water level should
be correctly maintained. Normally, 2 gauge glasses are provided to ensure this.
• Operators should blow these down regularly in every shift, or at least once per
day where boilers are steamed less than 24 hours a day.
● Blow down (BD) procedure
A conventional and accepted procedure for blowing down gauge is as follows:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Close water lock
Open drain cock (note that steam escapes freely)
Close drain cock
Close steam cock
Open water cock
Open drain cock (note that water escapes freely)
Close drain cock
Open steam cock
Open and then close drain cock for final blow through.
The water that first appears is generally representative of the boiler water. If it is
discoloured, the reason should be ascertained.
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Part 3 Tools and resources
A: Checklists for enhancing efficiency and safety
Checklist 2: Boiler periodic checklist
System
Daily
Weekly
Monthly
Annual
BD and water
treatment
Check BD valves do not
leak. BD is not excessive.
–
Make sure solids do not
build up.
–
Feed water system
Check and correct
unsteady water level.
Ascertain cause of unsteady
water level, contaminants
over load, malfunction etc.
Check controls by stopping
the feed water pump and
allow control to stop fuel.
Nil
Condensate receiver,
deaerator system pumps.
Flue gases
Check temp. at two
different points.
Measure temp. and
compare composition at
selected firings and adjust
recommended valves.
Same as weekly. Compare
with previous readings.
Same as weekly.
Record references.
Combustion air
supply
Burners
Check adequate openings
exist in air inlet. Clean
passages.
Check controls are
operating properly. May
need cleaning several times
a day.
Clean burners, pilot
assemblies, check condition
of spark gap of electrode
burners.
Boiler operating
characteristics
Observe flame failure and
characteristics of the flame.
Relief valve
Check for leakages.
Steam pressure
Same as weekly.
Same as weekly, clean and
recondition.
Remove and recondition.
Check for excess loads
which will cause excessive
variation in pressure.
Fuel system
Check pumps, pressure
gauges, transfer lines.
Clean them.
Belts for gland
packing
Check for damages. Check
gland packing for leakages
and proper compression.
Clean and recondition
system.
Air leaks in water
side and fire side
surfaces
Clean surface as per
manufacturer’s
recommendation annually.
Air leaks
Check for leaks around
access openings and flame.
Refractories on
fuel side
Repair.
Elec. system
Clean panels outside.
Hydraulic and
pneumatic valves
Cleaner Production – Energy Efficiency Manual
Inspect panels inside.
Clean, repair terminals and
contacts etc.
Clean equipment, oil
spillages to be arrested and
air leaks to be avoided.
Repair all defects and
check for proper operation.
page 258
Part 3 Tools and resources
A: Checklists for enhancing efficiency and safety
Checklist 3: Boiler dos and don’ts
Dos
Don‘ts
1. Soot blowing regularly
1. Don’t light up torches immediately after a
fireout (purge)
2. Clean blow down gauge glass once a shift
3. Check safety valves once a week
4. Blow down in each shift, to requirement
5. Keep all furnace doors closed
2. Don’t blow down unnecessarily
3. Don’t keep furnace doors open
unnecessarily
6. Control furnace draughts
4. Don’t blow safety valves frequently (control
operation)
7. Clear, discharge ash hoppers every shift
5. Don’t over flow ash hoppers
8. Watch chimney smoke and control fires
6. Don’t increase firing rate beyond that
permitted
9. Check auto controls on fuel by stopping
feed water for short periods occasionally
7. Don’t feed raw water
10. Attend to leakages periodically
8. Don’t operate boiler blind fold
11. Check all valves, dampers etc. for correct
operation once a week
9. Don’t overload boiler as a practice
12. Lubricate all mechanisms for smooth
working
13. Keep switchboards neat and clean and
indication systems in working order
14. Keep area clean, dust free
15. Keep fire fighting arrangements in
readiness always. Rehearsals to be carried
out once a month.
16. All log sheets must be truly filled
17. Trip FD fan if ID fan trips
18. CO2 or O2 recorder must be checked/
calibrated once in three months
19. Traps should be checked and attended to
periodically
20. Quality of steam, water, should be checked
once a day, or once a shift as applicable
21. Quality of fuel should be checked once a
week
10. Don’t keep water level too high or too low
11. Don’t operate soot blowers at high loads
12. Don’t trip the ID fan while in operation
13. Don’t look at fire in furnace directly, use
tinted glasses
14. Avoid thick fuel bed
15. Don’t leave boiler to untrained operators/
technicians
16. Don’t overlook unusual observation (sound
change, change in performance, control
difficulties), investigate
17. Don’t skip annual maintenance
18. Don’t prime boilers
19. Don’t allow steam formation in economizer
(watch temps.)
20. Don’t expose grate (spread evenly)
21. Don’t operate boiler with water tube
leaking
22. Keep sub heater drain open during start up
23. Keep air cocks open during start and close
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Part 3 Tools and resources
B: Thumb rules for quick efficiency
assessment in major energy systems
B.1 Thermal energy
● Boilers
• 5 per cent reduction in excess air increases boiler efficiency by 1 per cent (or
1 per cent reduction of residual oxygen in stack gas increases boiler efficiency
by 1 per cent).
• 22 °C reduction in flue gas temperature increases boiler efficiency by 1 per cent.
• 6 °C rise in feed water temperature brought about by economizer/condensate
recovery corresponds to a 1 per cent saving in boiler fuel consumption.
• 20 °C increase in combustion air temperature, pre-heated by waste heat
recovery, results in a 1 per cent fuel saving.
• A 3 mm diameter hole in a pipe carrying 7 kg/cm2 steam would waste
32 650 litres of fuel oil per year.
• 100 m of bare steam pipe with a diameter of 150 mm carrying saturated
steam at 8 kg/cm2 would waste 25 000 litres furnace oil in a year.
• 70 per cent of heat losses can be reduced by floating a layer of 45 mm
diameter polypropylene (plastic) balls on the surface of a 90 °C hot
liquid/condensate.
• A 0.25 mm thick air film offers the same resistance to heat transfer as a 330
mm thick copper wall.
• A 3 mm thick soot deposit on a heat transfer surface can cause a 2.5 per cent
increase in fuel consumption.
• A 1 mm thick scale deposit on the water side could increase fuel consumption
by 5 to 8 per cent.
B.2 Electrical energy
● Compressed air
• Every 5 °C reduction in intake air temperature would result in a 1 per cent
reduction in compressor power consumption.
• Compressed air leaking from a 1 mm hole at a pressure of 7 kg/cm2 means
power loss equivalent to 0.5 kW.
• A reduction of 1 kg/cm2 in air pressure (8 kg/cm2 to 7 kg/cm2) would result in
a 9 per cent saving in input power.
• A reduction of 1 kg/cm2 in line pressure (7 kg/cm2 to 6 kg/cm2) can reduce
the quantity leaking from a 1 mm hole by 10 per cent.
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
B: Thumb rules for quick efficiency assessment
● Refrigeration
• Refrigeration capacity reduces by 6 per cent for every 3.5 °C increase in
condensing temperature.
• Reducing condensing temperature by 5.5 °C results in a 20–25 per cent decrease
in compressor power consumption.
• A reduction of 0.55 °C in cooling water temperature at condenser inlet reduces
compressor power consumption by 3 per cent.
• 1 mm scale build-up on condenser tubes can increase energy consumption by
40 per cent.
• 5.5 °C increase in evaporator temperature reduces compressor power
consumption by 20–25 per cent.
● Electric motors
• High efficiency motors are 4–5 per cent more efficient than standard motors.
• Every 10 °C increase in motor operating temperature beyond the recommended
peak is estimated to halve the motor‘s life.
• If rewinding is not done properly, efficiency can be reduced by 5–8 per cent.
• Balanced voltage can reduce motor input power by 3–5 per cent.
• Variable speed drives can reduce input energy consumption by 5–15 per cent. As
much as 35 per cent of energy can be saved for some pump/fan applications.
• Soft starters/energy savers help to reduce power consumption by 3–7 per cent of
operating kW.
● Lighting
• Replacement of incandescent bulbs by CFL’s offer 75–80 per cent energy savings.
• Replacement of conventional tube lights by new energy-efficient tube light with
electronic ballast helps reduce power consumption by 40–50 per cent.
• 10 per cent increase in supply voltage will reduce bulb life by one-third.
• 10 per cent increase in supply voltage will increase lighting power consumption
by an equivalent 10 per cent.
● Buildings
• An increase in room temperature of 10 °C can increase the heating fuel
consumption by 6–10 per cent.
• Installing automatic lighting controls (timers, daylight or occupancy sensors) saves
10–25 per cent of energy.
• Switching off 1 ton window A/C for 1 hour daily during lunch hour avoids
consumption of 445 kWh.
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
C: List of energy measuring
instruments
C.1 Measuring instruments in practice
An energy audit to identify and quantify energy necessitates measurements, and
measurements require the use of instruments. These must be portable, durable, easy
to operate and relatively inexpensive. The parameters usually monitored for an energy
audit include the following:
Basic Electrical Parameters in AC and DC systems: voltage (V), current (I), power
factor (PF), active power (kW), apparent power (demand) (kVA), reactive power (kVAr),
energy consumption (kWh), frequency (Hz), harmonics, etc.
Important non-electrical parameters: such as temperature and heat flow,
radiation, air and gas flow, liquid flow, revolutions per minute, air velocity, noise and
vibration, dust concentration, total dissolved solids, pH, moisture content, relative
humidity, flue gas analysis (CO2, O2, CO, SOx, NOx), combustion efficiency, etc.
C.2 Key instruments for energy audits
Examples of key measuring instruments are provided below. In all cases the operating
instructions must be understood and staff should familiarize themselves with the
instruments and their operation prior to actual use in an audit.
● Electrical measuring instruments
Electrical
measuring
instruments
measure major electrical parameters
such as kVA, kW, PF, Hertz, kVAr, current
and voltage. Some instruments also
measure harmonics. The instruments are
used ‘on-line’, i.e. on running motors
without the need to stop the motor.
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
C: List of energy measuring instruments
● Hand-held instruments
Instantaneous measurements can be made
with hand-held meters. More advanced
meters provide cumulative readings with
print-outs at specified intervals.
● Combustion analyser
Combustion analysers have in-built chemical
cells that measure gases such as O2, CO, NOX
and SOX.
● Fuel efficiency monitor
Fuel efficiency monitors measure oxygen
levels and flue gas temperatures. Calorific
values of common fuels are fed into the
microprocessor which calculates the
combustion efficiency.
Cleaner Production – Energy Efficiency Manual
page 263
Part 3 Tools and resources
C: List of energy measuring instruments
● Fyrite®
A hand-operated bellow-pump draws a flue gas sample
into the solution inside the Fyrite. A chemical reaction
changes the liquid volume giving an indication of the
amount of gas. Separate Fyrites can be used for O2 and
CO2 measurements.
● Contact thermometer
Contact thermometers are thermocouples that
measure, for example, the temperatures of flue gases,
hot air or hot water by insertion of a probe into the
stream. A leaf type probe is used with the same
instrument to measure surface temperature.
● Infrared thermometer
Infrared thermometers are non-contact type
instruments giving a temperature read out when
pointed directly at a heat source. They are useful for
measuring hot spots in furnaces, surface temperatures,
etc.
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
C: List of energy measuring instruments
● Pitot tube and manometer
Air velocity in ducts can be measured using a pitot tube
and manometer. Useful for further flow calculations.
● Water flow meter
This non-contact flow measuring device uses the
Doppler effect or ultrasound. A transmitter and receiver
are positioned on opposite sides of the pipe and the
meter indicates the flow directly. Water and other fluid
flows can be measured easily with this meter.
● Speed measurements
Speed measurements are critical in any audit
exercise, as they may change with frequency, belt
slip or loading. A simple tachometer is a contact
type instrument used where direct access is
possible. More sophisticated and safer instruments,
such as stroboscopes, are of the non contact type.
Cleaner Production – Energy Efficiency Manual
page 265
Part 3 Tools and resources
C: List of energy measuring instruments
● Leak detectors
Ultrasonic leak detectors are available to detect leaks of
compressed air and other gases which cannot normally
be detected by the human senses.
● Lux meters
Illumination levels are measured with a lux meter. The
instrument comprises a photo cell which senses the
light output and converts this to electrical pulses used
to produce a read out in lux.
Cleaner Production – Energy Efficiency Manual
page 266
Part 3 tools and resources
D: Greenhouse Gas Emissions Indicator
D.1 What is the Greenhouse Gas Emissions Indicator?
UNEP has developed the Greenhouse Gas (GHG) Emissions Indicator (UNEP Guidelines for
Calculating Greenhouse Gas Emissions for Businesses and Non-Commercial Organizations) to
provide a methodology for estimating GHG emissions that is adaptable to all
organizations, varieties of fuel mix and other related factors. The purpose of the Indicator
is to establish a common, worldwide method of reporting on GHG emissions. It will also
provide baseline information that will help in assessing progress towards targets such as
those set by international agreements like the Kyoto Protocol, or in designing Clean
Development Mechanism and emissions trading schemes. The Indicator contains tools
(Worksheets) that can be used to calculate GHG emissions directly. Originally developed
in document form, these are now available in spreadsheet format:
The GHG Indicator
is included on the
CP-EE CD-ROM together
with this Manual.
Click here to access the
files on the CD-ROM
a) on this CD-ROM (see box on right); and
b) on the UNEP DTIE website: http://www.uneptie.org/energy/tools/ghgin/index.htm
Figure D.1 GHG calculator
FUEL and ENERGY
CONVERSION
DATA
DATA
AGGREGATION
NORMALIZATION
TOTAL GHG
NORMALIZED
GHG
FUEL CONSUMPTION
ELECTRICITY USE
GHG EMISSION
FACTOR
TRANSPORT FIGURES
PROCESS RELATED
EMISSIONS
Using the Indicator allows a company (or other organization) to analyse its major GHG
emission sources (e.g. direct fuel consumption, electricity use, transport for personnel and
freight, and production process). Then, using conversion data provided and the calculator
tools, GHG emission factors can be applied to calculate the company’s or organization’s
emissions. Finally, normalizing factors such as turnover, production, added value and
numbers of employees are applied to normalize total emissions. Details of the GHG
Indicator are explained below in a question and answer format.
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
D: Greenhouse Gas Emissions Indicator
D.2 The GHG Indicator in detail
● Who can use the GHG Indicator?
Governments can use the Indicator to estimate national GHG emissions. Companies or
other organizations can use the Indicator to convert their fuel and electricity use into
GHG emissions.
● Frequently asked questions about the GHG Indicator
“I am from a company in Thailand that uses coal. How can I convert our coal consumption
(1 000 ton/year) to GHG emissions using the GHG Indicator?”
• First, use Table D.1 to find the emission factor (EF) for coal in Thailand (1.85 tons
of CO2/ton of coal used).
• Multiply your company’s coal consumption by the EF.
• Your company‘s CO2 emissions amount to 1.85 x 1 000 = 1 850 tons.
Table D.1: Emissions from fuel use—country-specific net calorific values (NCV) for
coal and CO2 emissions
Country
Australia
Bangladesh
China
Egypt
India
Iran
Iraq
Israel
Japan
Kazakhstan
Kuwait
Kyrgyzstan
Malaysia
Nepal
New Zealand
Pakistan
Singapore
South Korea
Sri Lanka
Syria
Thailand
United Arab
Uzbekistan
Default
NCV (TJ/ton)
CO2 EF (tons CO2/ton of coal used)
21.227
16.329
16.37
17.710
16.454
17.710
17.710
17.250
27.758
18.673
17.710
18.673
19.407
17.543
23.781
15.701
13.105
19.176
17.710
17.710
19.887
17.710
18.673
19.841
1.97
1.52
1.52
1.65
1.53
1.65
1.65
1.60
2.58
1.73
1.65
1.73
1.80
1.63
2.21
1.46
1.22
1.78
1.65
1.65
1.85
1.60
1.73
1.84
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
D: Greenhouse Gas Emissions Indicator
“What if my country is not listed in Table D.1 and I want to calculate GHG emissions?”
• If your country is not listed, you can use the default value (1.84 tons of CO2/ton
of coal) at the end of Table D.1.
“What if I use more than one fuel?”
• Refer to Worksheet D.1 which gives EF values for CO2 emissions from different
types of fuels. Multiply the respective EFs for the relevant fuels by the amounts
of those fuels your company uses to obtain the CO2 emissions.
• You can also total the respective CO2 emissions and divide by the total weight
of fuel to get an overall EF for your company.
Worksheet D.1: CO2 emissions from fuel use
Fuel types
Basic Unit
Therms Litres
KWh
Emission
Tons
X
tCO2
tCO2
Coal
0.00222
Petrol
Natural Gas
0.0059
tCO2
tCO2
0.0003413
1.84
0.0002496
3.07
0.0002020
2.93
Gas/Diesel Oil
0.00268
0.0002667
3.19
Residual Fuel Oil
0.00300
0.0002786
3.08
0.00165
0.0002271
2.95
0.00258
0.0002575
3.17
Shale Oil
0.0002218
2.61
Ethane
0.0002641
2.90
0.0002905
3.27
0.0002641
3.21
0.0003631
2.92
Petroleum Coke
0.0002641
3.09
Refinery Feedstock
0.0002641
3.25
0.0002403
2.92
0.0002641
2.92
LPG
0.0067
Jet Kerosene
0.00224
Naphtha
Bitumen
0.00263
Lubricants
Refinery Gas
Other Oil Products
0.007
0.00254
=
Amount of
CO2 (t)
Total
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
D: Greenhouse Gas Emissions Indicator
Example: Calculating CO2 emissions for several fuels
A refinery consumes coal, refinery feedstock and petroleum coke. Its total CO2 emissions (in tons)
and emission factor are calculated as shown below.
Fuel
Coal
Refinery feedstock
Petroleum coke
Totals
Annual fuel
consumption (tons)
EF
tCO2
500
x
1.85
=
925
3 502
x
3.25
=
11 382
45
x
3.09
=
139
4 047
12 446
Total fuel consumption
= 4 047 tons
= 12 446 tCO2
Total CO2 emissions released
CO2 Emission Factor for the refinery = Total CO2 / total fuel input
= 12 446 / 4 047
= 3.075 t CO2 per ton of fuel
“How do I calculate GHG emissions for the utility generated electricity consumed by my
company? (My company consumes 100 000 kWh per year.)”
• A complete list of emission factors for electricity usage by country (using IEA
data) is given in Table D.2. First, find your country and determine its EF (e.g. for
Thailand, the emission factor is 0.000618). Multiply the EF by consumption (in
this example this gives: 100 000 x 0.000618 = 6.18 tons of CO2).
“My company exports power and steam for economic as well as social reasons. How do I
calculate in this case?”
• Your company should not be accountable for the associated emissions. Such
emissions should be accounted for by the user of the electricity or heat. The
emissions corresponding to the amount or heat exported should be calculated
and should then be deducted from your company’s emission total.
“My company imports electricity or heat generated by public CHP. How do I calculate?”
• If you import electricity from a public CHP plant, use the electricity factors given
in Table D.2 and then use Worksheet D.1 to calculate the CO2 emissions. The
electricity emission factors in Table D.2 incorporate public CHP schemes in the
energy mix.
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
D: Greenhouse Gas Emissions Indicator
Table D.2: Electricity emission factors for different countries (tCO2/kWh)
for 1990 and 1996
Country
Africa
1990 emission factor
1996 emission factor
0.00066
0.000663
Asia (excl. China)
0.000658
0.000724
Australia
0.000777
0.000791
Bangladesh
0.000604
0.00054
China
0.00071
0.000772
Egypt
0.000546
0.000561
Emirates
0.000616
0.000783
Europe
0.000496
0.00042
India
0.000761
0.00089
Iran
0.000541
0.000534
Iraq
0.000549
0.000554
Israel
0.000814
0.000801
Japan
0.000346
0.000321
Kazakhstan
0.000000
0.001312
Korea
0.000317
0.000297
Kuwait
0.000591
0.000512
Malaysia
0.000664
0.000594
Middle East
0.000632
0.00065
Nepal
0.000674
0.000632
New Zealand
0.000103
0.000099
Pakistan
0.00041
0.000438
Singapore
0.00089
0.000622
South Africa
0.000796
0.00077
Sri Lanka
0.000003
0.000205
Syria
0.000546
0.00065
Tajikistan
0.000000
0.000068
Thailand
0.000619
0.000618
Turkey
0.000492
0.000461
Turkmenistan
0.000000
0.000731
0.000237
0.000176
United Arab
Venezuela
Cleaner Production – Energy Efficiency Manual
Source IEA.
Non-OECD:
page 271
Part 3 Tools and resources
D: Greenhouse Gas Emissions Indicator
“My company generates GHGs other than CO2 from its process. How do I account for
GHG emissions?”
• Production of process-related GHGs is estimated (in tons) and converted to CO2
equivalents using the global warming potential (GWP) for a 100 year-time horizon
as a conversion factor. Worksheet D.2 can be used for process-related emissions.
.
Worksheet D.2: Process-related greenhouse gas emissions
Trace Gas
Basic Unit
X
Conversion values
(GWP,100)
Carbon dioxide
1300
CFC-11
3400
CFC113
4500
CFC 116
6200
CFC12
7100
CFC114
7000
CFC115
7000
Chloroform
4
HCFC 123
90
HCFC 124
430
HCFC 22
1600
HFC 125
2800
HFC 32
650
HFC
150
Methylene chloride
Cleaner Production – Energy Efficiency Manual
CO2
equivalent
1
CC1 4
Methane
=
21
9
page 272
Part 3 Tools and resources
D: Greenhouse Gas Emissions Indicator
“How do I account for my transport related emissions?”
• Emissions from transport are broken down by transport mode. The guidelines in
the GHG Indicator cover:
i) road vehicle transport;
ii) non-road transport.
• For road vehicle transport, first calculate the total fuel consumption for three
major transport fuels, and use Worksheet D.3 to calculate the CO2 emissions.
“My company rents transport for employees. How do I calculate GHG emissions in this case?”
• The nature of rented transport makes it difficult to calculate the consumption of
specific fuel types. Vehicle-kilometre calculations are used in this instance.
• Worksheet D.3 can be used to calculate CO2 emissions for rented transport and
non-road transport.
Worksheet D.3: Fuel emissions from transport
Transport
mode
Basic unit
No. of
basic units
X
CO2 E.F.
CO2 E.F.
(tCO2/km) (tCO2/mile)
Average petrol car
kilometre or mile
0.000185
0.000299
Average diesel car
kilometre or mile
0.000156
0.000251
HGV
kilometre or mile
0.000782
0.00126
Passenger air
(short haul)
person.kilometre or
person.mile
0.00018
0.00029
Passenger air
(long haul)
person.kilometre or
person.mile
0.00011
0.00018
Passenger train
person.kilometre or
person.mile
0.000034
0.000054
Air freight
(short haul)
tonne.kilometre or
tonne.mile
0.000158
0.00025
Air freight
(long haul)
tonne.kilometre or
tonne.mile
0.00057
0.00091
Freight train
tonne.kilometre or
tonne.mile
0.000047
0.000075
Inland shipping
(freight)
tonne.kilometre or
tonne.mile
0.00003
0.000056
Marine shipping
(freight)
tonne.kilometre or
tonne.mile
0.000010
0.000016
Cleaner Production – Energy Efficiency Manual
=
CO2 emissions
(tonnes)
page 273
Part 3 Tools and resources
D: Greenhouse Gas Emissions Indicator
“I have finally managed to calculate all energy and process emissions from my company.
What do I do next?”
• Aggregate all the emissions and then normalize the data.
“What is aggregation?”
• Aggregation means summing of energy and transport related CO2 and processrelated emissions. See Table D.3 and the accompanying note.
“What is normalization?”
• Normalization is the process of dividing total CO2 emissions by turnover,
employees, added value and unit production. Table D.4 gives an example of
normalizing for a cement plant emitting 1 500 000 tCO2/year.
Table D.3: Total global warming impact as CO2 equivalent aggregation
GHG source
1
Fuel; combustion
2
Electricity
3
CHP
4
Road transport
5
Unit. kilometre transport
6
Process-related GHG emissions
Tons of CO2 equivalent
Step 1
Insert the relevant totals of CO2
from the previous worksheets
for each category.
Step 2
Add the column and insert the
total in box at the bottom.
TOTAL CO2
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
D: Greenhouse Gas Emissions Indicator
Table D.4: Normalizing CO2 potential
Group consolidated figures
(Column 1)
Turnover
Added value
Employees
Unit production
Normalized CO2 equivalents
(tonnes per normalizing factor)
(Column 2)
$ 20 000 000
0.075
$ 500 000
3
500
3 000
1 350 000 tons
1.11
Cleaner Production – Energy Efficiency Manual
Step 1
From your group/company
accounts, insert the relevant
figures in column 1.
Step 2
Divide the total CO2 by column
1 and insert the answer in
column 2.
Step 3
Use the answers in column 2 as
the ratio for amount of CO2
produced for each of the
normalizing factors, e.g. 1.11 t.
CO2 for every ton of cement
produced.
page 275
Part 3 Tools and resources
E: Information resources
This section provides links to Cleaner Production and Energy Efficiency resources on the
Internet. Resources are grouped together under various headings for ease of
navigation. Clicking on the blue hyperlinks in the text will launch your web browser
and link you directly to the appropriate resource.
Please read the Disclaimer (below) before consulting any of the Internet resources listed
in this Manual.
DISCLAIMER
UNEP DTIE has no control over any of the Internet resources listed in this
Manual and therefore cannot guarantee that the information held therein will
always be accurate and complete.
Although UNEP DTIE endeavours to provide links to websites which contain
accurate information, we are unable to guarantee that these pages will not
contain errors, or incomplete or out-of-date information.
Therefore, neither UNEP DTIE nor any of its contributors can be held responsible
for any loss, damage or expense that might be caused by any action, or lack of
action, that a user of this service might take as a result of reading material on a
site found using the links provided. Responsibility for such actions, or lack of
actions, remains with the reader.
Cleaner Production – Energy Efficiency Manual
page 276
Part 3 Tools and resources
E: Information resources
E.1 Energy systems
• Compressed air
An overview of Best Practices for compressed air system resources to help
industrial end users achieve efficiency improvements and related cost savings.
(Resources include compressed air tip sheets; technical publications.)
http://www.oit.doe.gov/bestpractices/compressed_air/
• Motor systems
Best Practice resources specific to motor systems. Includes publications, software
tools and training information. Most can be downloaded from this site.
http://www.oit.doe.gov/bestpractices/motors/
• Process heating
Information on process heating that can help companies realize significant savings
through system improvements and technology implementation. (Resources
include process heating ‘Tip Sheets’; technical publications.)
http://www.oit.doe.gov/bestpractices/process_heat/
• Steam system efficiency
Information on steam generation, steam distribution, steam use and steam
recovery that should be considered for improvements to help reduce
operating costs.
http://www.oit.doe.gov/bestpractices/steam/efficiency.shtml
• Motor solutions on-line
Comprehensive information and guidance, as well as practical information and
tools, to help make the right choices about electric motors.
http://www.greenhouse.gov.au/motors/
• Energy conservation in motors
Includes: terms related to motors; standard designs of motors; types of motors; motor
losses; why motors fail; equipment to read motor parameters; features of energy
efficient motors; energy conservation in motors; and energy conservation analysis.
http://www.letsconserve.org/terms_related_to_motors1.php
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
E: Information resources
• Motors and drives
Covers all aspects of motors, from an explanation of how they work, to the
advantages/disadvantages of adjustable speed drives. Also included are special
pages on motor maintenance and troubleshooting, and economic implications of
replacing existing motors with different types of motors. The information on this
site is especially valuable for commercial and industrial consumers.
http://cipco.apogee.net/mnd
• Commercial energy systems
Covers the following areas in energy systems for commercial buildings (from fast
food to retail stores, to commercial operations of all descriptions): lighting; power
quality; commercial cooking; HVAC design; HVAC systems; CES design; building
design process; commissioning.
http://cipco.apogee.net/ces
• Various energy systems
How facilities can save thousands on fan, pump and compressor, blower, motor
and AC unit costs. The site includes typical problems, opportunities, a system cost
calculator and an optimization checklist for the benefits of optimizing the
system(s) in a facility.
http://www.productiveenergy.com/home/index.asp
Cleaner Production – Energy Efficiency Manual
page 278
Part 3 Tools and resources
E: Information resources
E.2 Financing CP & EE projects
• Financing sustainable energy directory (on-line database)
An on-line database inventory of lenders and investors that provide finance to the
renewable energy and energy efficiency sectors. It is intended for project
developers and entrepreneurs seeking capital as well as for investors looking for
financing vehicles.
http://www.fse-directory.net
• International Finance Cooperation (IFC)
In recent years, the IFC has been actively seeking to finance a greater number of
energy efficiency (EE) projects and to develop special initiatives to accelerate the
market penetration of these technologies. The IFC’s efforts in this area are driven
by the significant benefits that EE projects offer from a sustainable development
standpoint, including cost savings and the realization of local and global
environmental benefits.
http://www.ifc.org/enviro/EFG/EEfficiency/eefficiency.htm
• Promotion of energy efficiency in industry and financing of related
public and private investments
This publication is divided into five parts: Part 1 presents an introductory overview
of policy issues. Part 2 gives an overview of financing options for investors. Part 3
describes policies and experiences of three selected industrialized and newly
industrializing countries that have emphasized active energy efficiency investment
to counter the growing energy import dependencies of their respective
economies. Part 4 discusses the particular difficulties faced by countries with
economies in transition in the promotion of investments for energy efficiency.
Part 5 presents an outlook on international cooperation in financing energy
efficiency investments.
http://www.unescap.org/publications/detail.asp?id=757
• Profiting from Cleaner Production
UNEP has developed and presented a series of awareness raising and training
courses on cleaner production financing. The resource kit is meant for the
industrial, financial and public sectors. It has been published on a CD-ROM and is
now available on-line, free of charge to registered users.
http://www.financingcp.org/training/training.html
Cleaner Production – Energy Efficiency Manual
page 279
Part 3 Tools and resources
E: Information resources
• UNEP Sustainable Energy Finance Initiative
The Sustainable Energy Initiative is a joint effort of UNEP and its collaborating
centre the Basel Agency for Sustainable Energy (BASE) aimed at fostering the
sustainable energy community, growing its common knowledge set and building
alliances and partnerships that, together, positively influence the flow of capital
into the sustainable energy sector.
http://sefi.unep.org
E.3 CP-EE technology providers
• The Energy Efficiency Best Practice Programme
The Energy Efficiency Best Practice Programme (EEBPP) is a UK Government
programme providing free information to organizations to help them cut their
energy bills by offering detailed technical advice on a wide range of energy
efficiency measures.
http://www.energy-efficiency.gov.uk/
• Persistent organic pollutants (POPs)—database of alternatives
Information on POPs alternatives and approaches to replace and/or reduce the
releases of POPs chemicals.
http://www.chem.unep.ch/pops/newlayout/infaltapp.htm
• GREENTIE
Using the search facility on this site, browse the full international directory of
suppliers whose technologies help to reduce GHG emissions.
http://www.greentie.org/directory/index.php
• Advanced test and measurement devices
A leading company in the development and manufacture of advanced test and
measurement technologies for use both in the field and leading edge facilities
around the world.
http://www.hioki.co.jp/eng/product/
Cleaner Production – Energy Efficiency Manual
page 280
Part 3 Tools and resources
E: Information resources
• Product and supplier finder
More than 11 000 on-line catalogues covering: sensors, transducers and
detectors; manufacturing and process equipment (e.g. heating and cooling
equipment, industrial heaters, industrial machine safeguarding, inspection tools
and instruments, materials processing equipment); material handling; data
acquisition and signal conditioning; mechanical components; industrial
computing; motion and controls; flow transfer and control; and test and
measurement equipment.
http://www.globalspec.com/ProductFinder/
• Association of Energy Services Professionals
The Association of Energy Services Professionals is dedicated to advancing the
professional interests of individuals working to provide value through energy
services and energy efficiency by sharing ideas, information and experience.
http://www.aesp.org/
• SEE-Tech Solutions Pvt. Ltd.
A company specializing in consulting, training and performance auditing in the
areas of energy conservation, energy efficiency improvement and industrial safety.
The company also provides software solutions for energy auditing.
http://www.letsconserve.org/seemain.php
• Trade portal for Indian products
On-line marketplace for industrial process equipment and accessories, and many
other Indian products.
http://www.easy2source.com/
• CADDET Energy Efficiency
A collection of studies (analysis reports) made by experts from CADDET Energy
Efficiency members and other IEA agreements, providing detailed reviews across a
wide range of topical energy efficiency subjects. They can be obtained from
CADDET Energy Efficiency National Teams (a summary can be provided, for a fee).
http://www.caddet-ee.org/reports/index.php
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E: Information resources
• National Inventory of Manufacturing Assistance Programs (NIMAP)
The NIMAP inventory is linking sources with consumers of technical information
and services. Simple lack of awareness on the part of eligible recipients is a major
barrier to achieving energy policy goals.
http://www.oit.doe.gov/bestpractices/nimap/
• Database for Energy Efficient Resources (DEER)
Database for Energy Efficient Resources (DEER) contains extensive information on
selected energy-efficient technologies and measures. The DEER provides estimates
of the average cost, market saturation, and energy-savings potential for these
technologies in residential and non-residential applications.
http://www.energy.ca.gov/deer
• Thai-Danish cooperation on sustainable energy
The Sustainable Energy Database provides an overview of activities and players in
the field of sustainable energy in Thailand, and in the Isaan region in particular.
http://www.ata.or.th/indexeng.html
• Tata Energy Research Institute (TERI)
TEDDY Online (TERI Energy Data, Directory and Yearbook) provides ready-to-use
information on different segments (energy and environment) of the Indian
economy and some aspects of international economy.
http://www.eldis.org/static/DOC4556.htm
• IEA Clean Coal Centre
The world’s foremost provider of information on efficient coal supply and use, IEA
Coal Research—The Clean Coal Centre enhances innovation and continued
development of coal as a clean source of energy.
http://www.iea-coal.org.uk/
• Energy Technology Systems Analysis Programme
The Energy Technology Systems Analysis Programme (ETSAP) of the International
Energy Agency (IEA) is a research partnership dedicated to enabling its partners
and their clients to develop sound integrated energy and environmental policy.
http://www.etsap.org/index.htm
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E: Information resources
• ETDE’s Energy Database
ETDE’s Energy Database contains a large collection of energy literature, with more
than 3.8 million abstracted and indexed records. Updated twice monthly, the
database contains bibliographic references to, and abstracts from, journal articles,
reports, conference papers, books and other documents. The database covers a
variety of subjects including environmental aspects of energy production and use,
and energy policy and planning, as well as the basic science that supports energy
research and development.
http://www.etde.org/edb/energy.html
• The Bureau of Energy Efficiency (BEE)
The BEE website, is a comprehensive source of information on energy
conservation- (EC) related developments and issues. It provides an update on the
related policy framework especially in the context of the EC Act 2001 as well as
topical write-ups, news and highlights on developments in India. The site also
features activities taken up by the BEE with stakeholders, co-opting expertise from
bilateral/multilateral agencies.
http://www.bee-india.com/
• National Lighting Product Information Programme
NLPIP, helps lighting professionals, contractors, designers, building managers,
homeowners and other consumers find and use efficient, quality products that
meet their lighting needs. With the support of government agencies, public benefit
organizations and electrical utilities, NLPIP disseminates objective, accurate, timely,
manufacturer-specific information about energy-efficient lighting products.
http://www.lrc.rpi.edu/programs/NLPIP/index.asp
E.4 CP-EE sector-specific resources
• Energy efficiency technologies
This link provides information on R&D projects in energy saving technologies for
a number of vital industries including: mining; metal casting; aluminium;
chemicals; forest products; glass; metal casting; mining; petroleum; steel; and
supporting industries).
http://www.eere.energy.gov/industry/
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E: Information resources
• Textile: smart guide
A useful guide including a summary of business cases in textile manufacturing in
different countries.
http://www.emcentre.com/unepweb/tec_case/textile_17/house/casename.shtml
• US EPA Sector Notebooks
The US EPA Sector Notebooks are comprehensive overviews of environmental
issues in about 30 major industries. Each includes descriptions of the industry,
including operations, pollutants and regulations, pollution prevention methods,
and related resources. Highly recommended.
http://www.epa.gov/compliance/resources/publications/assistance/sectors/notebooks/
• European Integrated Pollution Prevention and Control Bureau
The European Integrated Pollution Prevention and Control Bureau produces
comprehensive guides to industry sector environmental management. About 15
guides have been completed; many others are being developed.
http://www.jrc.es/pub/english.cgi/0/733169
• Australian National Pollutant Inventory Industry Handbooks
The Australian National Pollutant Inventory Industry Handbooks are manuals for
estimating emissions from about 50 types of industries. Each Handbook has
detailed process descriptions, information about emission sources, and
benchmarks and formulas for estimating emissions. Highly valuable to engineers.
http://www.npi.gov.au/handbooks/approved_handbooks/index.html
• On-line collection of pollution prevention references
This on-line collection of pollution prevention core references includes technical
references, fact sheets and case studies on pollution prevention for 30 selected
industry sectors.
http://wrrc.p2pays.org/industry/indsector.htm
• Energy Data and Analysis database (Asia Pacific )
The Expert Group on Energy Data and Analysis (EGEDA) is responsible for
providing policy relevant energy information to APEC bodies and the wider
community, through collecting energy data of the APEC region, managing the
operation of the APEC Energy database through the coordinating agency.
http://www.ieej.or.jp/egeda/database/database-top.html
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E: Information resources
E.5 Software and tools
• Electrical engineering calculators
Basic formulas, plus calculators for: conductors, resistors, capacitors and PCB’s;
semiconductors and integrated chips; and power supplies.
http://www.ifigure.com/engineer/electric/electric.htm
• Engineering calculators
Free on-line calculators for: steam approximations; power cycle analysis (carnot,
cycle, brayton, otto, and diesel cycles); power cycle components/processes;
compressible flow; unit conversion; engineering equations; and miscellaneous
engineering tools.
http://members.aol.com/engware/calcs.htm
• Mechanical engineering calculators
Engineering conversion factors; hydraulics tools (fluid flow calculator, water pump
calculator, and pump tables and charts); and heating and air conditioning tools
(psychometric calculator, saturated steam tables and air duct calculator).
http://www.ifigure.com/engineer/mechanic/mechanic.htm
• On-line calculators and formulas for power system analysis
The formulas on this web page can be used in designing power factor correction
systems and harmonic filter banks.
http://www.nepsi.com/formulas.htm
• FireCAD
User-friendly FireCAD design software products are available, developed using the
latest boiler and software technologies, for fire tube boiler, water tube package
boiler, economizer, air heater and superheater. Trial versions of these software
packages can be downloaded.
http://www.firecad.net/
• Material safety data sheets (database)
A card and the information that it contains relate to a specific chemical substance
and are concerned with the intrinsic hazards posed by that chemical. Also, a basic
tool to supply information on the properties of chemicals used. (Available in 14
languages).
http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/index.htm
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Part 3 Tools and resources
E: Information resources
• Motor solutions online self assessment tool
This self-assessment tool is designed to assist organizations in rating motor and
equipment management skills, from initial selection to eventual replacement. Not a
test, rather a tool to help identify and prioritize change within an organization—
change that can reduce life-cycle cost of equipment ownership and increase profits.
http://www.peak.co.nz/ausat/
E.6 Energy legislation
• European energy legislation (by country)
Details of both European and national laws, policies, directives, regulations,
standards, etc. Data can be searched by country.
http://www.managenergy.net/submenu/Sleg.htm
• Asia energy conservation legislation
Compendium on energy conservation legislation in countries of the Asia and
Pacific region.
http://www.unescap.org/esd/energy/publications/compend/cec.htm
• Energy Charter Treaty (Europe/Asia)
The fundamental aim of the Energy Charter Treaty is to strengthen the Rule of
Law on energy issues by creating a level playing field of rules to be observed by
all participating governments, thus minimizing the risks associated with energy
related investments and trade.
http://www.encharter.org/index.jsp
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F: Conversion tables
Système International (SI) and metric units have been adopted internationally for
energy calculations. For instance, the joule, the SI unit of energy, is commonly used in
conjunction with other SI units such as the metre, the kilogram and the kelvin (for
temperature).
The conversion tables presented below show how some units commonly used in
engineering and other professions equate to SI and metric units.
Table F.1: Abbreviations for quantities
T
=
tera
=
One million million
=
1 000 000 000 000
=
1012
G
=
giga
=
One thousand million
(Also one billion)
=
1 000 000 000
=
109
M
=
mega
=
One million
=
1 000 000
=
106
k
=
kilo
=
One thousand
=
1 000
=
103
d
=
deci
=
One tenth
=
0.1
=
10-1
c
=
centi
=
One hundredth
=
0.01
=
10-2
m
=
milli
=
One thousandth
=
0.001
=
10-3
m
=
micro
=
One millionth
=
0.000001
=
10-6
n
=
nano
=
One billionth
=
0.000000001
=
10-9
p
=
pico
=
One millionth of a millionth
=
0.000000000001
=
10-12
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F: Conversion tables
Table F.2: Commonly used units and what they mean
Btu
The British thermal unit, a measure of heat energy.
Btu/lb °F
and
kJ/kg °C
Units for the specific heat capacity of a substance—a measure of the quantity of
(heat) energy required to raise the temperature of a given quantity of the substance
through one degree.
In the imperial system, it is the number of British thermal units required to raise one
pound weight of the substance by one degree on the Fahrenheit scale.
In SI units it is the (kilo) joules of heat energy required to raise one kilogram of the
substance by one degree on the Celsius (or Centigrade) scale.
Btu in/ft 2h
and
W/m2 °C
Thermal conductance—a measure of the rate at which heat energy passes through a
given thickness of material per unit of area, with a one degree temperature
difference between the two sides.
In imperial units it is the number of British thermal units that will pass through one
square foot of material of one inch thickness in one hour with a temperature
difference of one degree Fahrenheit between the warmer and cooler surfaces.
Using SI units, it is watts of heat power that will pass through one square metre of
material with one degree Celsius (Centigrade) difference.
bar
An alternative unit of pressure equal to 105 pascals. Its value is slightly higher than
normal atmospheric pressure. The bar is often divided into millibars, (abbreviation
mbar) equal to one thousandth of a bar.
bbl
U.S. Barrel, used in the oil industry as a standard unit of oil production (equivalent to
42 US gallons or 35 imperial gallons).
cal and
(kcal)
The calorie, a metric system unit of energy now superseded by the SI unit, the joule.
(1 kcal = 1 000 calories).
grain
An older imperial unit of weight still used occasionally for very small amounts of
material (7 000 grains = 1 pound).
ha
Hectare, metric unit of ground area (equivalent to 2.47 acres), equal to 10 000 m2.
HP
Horsepower, the rate of mechanical work.
imp
Abbreviation for ‘imperial’. When used alongside a unit it indicates that the unit
belongs to the imperial system (e.g. 1 gal (imp) is 1 imperial gallon).
J and (kJ)
The joule, the SI unit of energy (1 kJ = 1 000 joules).
kWh
A measure of energy equivalent to consumption of 1 kW of power for one hour. The
kWh is the traditional ‘unit’ of electricity in industry. It is the unit usually used on
invoices to show the amount of electrical energy used by the consumer.
l (also ltr)
The litre, a metric unit of volume.
psi
and
kPa
Units of pressure.
In imperial units (pounds per square inch, psi), pounds force applied to one square
inch of surface.
In SI units, (kilo pascals, kPa), a force of 1000 pascals applied over one square metre
of surface. (The pascal is a pressure of one newton applied to one square metre).
therm
A unit of heat used traditionally by the gas industry.
tonne
The metric tonne, slightly smaller than the imperial ton (around 1.6 per cent less).
W (kW)
The watt, a unit of power (1 kW = 1 000 watts).
Cleaner Production – Energy Efficiency Manual
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F: Conversion tables
Table F.3: Conversion of measurements
Metric to British
British to metric unit
Volume
1 cm3
=
0.061 cu.in.
1 cu.in
=
16.387 cm3
1 m3
=
35.32 ft3
1 ft3
=
0.0283 m3
1 m3
=
1.308 cu.yd
1 cu.yd
=
0.7646 m3
Specific volume and weights
1 m3/kg
=
16.02 ft.3 /lb
1 ft.3/lb
=
0.0624 m3/kg
1 kg/m3
=
0.0624 lb/ft3
1 lb/ft3
=
16.01 kg/m3
1 kg/cm2
=
14.223 lb/sq.in.(psi)
1 lb/sq.in
=
0.0703 kg/cm3
1 mm WC
=
0.002937 in. of Hg
1 in. of Hg
=
340.39 mm WC
1 ounce/sq.in
=
43.9 mm WC
Pressure
Velocity
1 m/sec
=
196.9 ft/min.
100 ft/min
=
0.508 m.sec
1 m/sec
=
3.28 ft/sec
100 ft/sec
=
30.4 m/sec
=
0.589 CFM (cu.ft /min)
1 CFM
=
1.7 m3/hr
Flow
1 m3/hr
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F: Conversion tables
Table F.4: Conversion of common units of heat (thermal power and energy)
1 Btu
=
0.252 kcal
1 Btu
=
1.055 kJ
1 Btu/sec
=
1.055 kW
1 Btu/lb.
=
0.556 kcal/kg (2.3244 kJ/kg)
1 Btu/cu.ft
=
8 900 kcal/m3 (37.26 kJ/m3)
1 Btu/sq.ft.h
=
2.71 kcal/m3 h (3.155 kW/m2)
1 Btu/sq.ft.h °F
=
4.886 kcal/m2 h °C (5.678 kW/m2 °C)
1 Btu/ft.h °F
=
1.49 kcal/mh °C (17.296 kW/m °C)
1 Btu/lb °F
=
1.001 kcal/kg °C (4.187 kJ/kg °C)
1 Btu/cu.ft °F
=
16.2 kcal/m3 °C (67070 kJ/m3 °C)
1 kcal
=
3.968 Btu
1 kW
=
0.948 Btu/sec
1 kcal
=
0.239 kJ
1 kWh
=
860 kcal
1 kJ
=
0.948 Btu
1 kW
=
3412 Btu/h
1 kJ/kg
=
0.4302 Btu/lb
1 W/m °C
=
0.578 Btu/h ft °F
=
0.1761 Btu/h ft2 °F
1 kJ/kg °C
=
0.239 Btu/lb °F
1 kJ/m3 °C
=
0.0149 Btu/ft3 °F
1 kcal/kg
=
1.80 Btu/lb
kcal/m3
=
0.112 Btu/cu.ft.
1 kcal/m3 h
=
0.369 Btu/sq.ft.h
1 kcal/m3 h °C
=
0.205 Btu/sq.ft.h °F
1 kcal/mh °C
=
0.67 Btu/ft.h °F
=
8.07 Btu in/sq.ft. °F
1 kcal/kg °C
=
0.999 Btu/lb °F
1 kcal/m3 °C
=
0.0624 Btu/cu.ft. °F
860 kcal
=
1 kWh
1
1
W/m2 °C
1 kcal/mh °C
m3
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
F: Conversion tables
Table F.5: Conversion of pressure units
PSI
PSI
kg/cm2
Atmosphere
Bar
Atmosphere
kg/cm2
Bar
1
0.07031
0.06804
0.069
14 223
1
0.9678
0.981
14.69
1.033
1
1.0133
14.5
1.019
0.986
1
kJ (kilo-joule)
kWh
Table F.6: Conversion of energy units
kcal
HPh
1
4 187
0.001161
0.001556
0. 239
1
27.77 x 10-5
37.23 x 10-5
kWh
860
3 600 x 103
1
1.3411
HPh
642.5
22 685 500
0.74565
1
kcal
kJ (kilo-joule)
Table F.7: Conversion of power units
kcal/sec
kW (kilo watt)
HP
Ch
1
4.188
5 616
5.67
kW (kilo watt)
0.239
1
1.341
1.359
HP
0.178
0.746
1
1.014
Ch
0.176
0.736
0.987
1
kcal/sec
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
F: Conversion tables
Table F.8: Characteristics of fuel oils
Fuel oils
Properties
F.O.
Density
(approx. kg/m3 at 15 °C)
LS.H.S
H.P.S.
L.D.O.
0.89–0.95
0.88–0.98
0.85–0.98
0.85–0.87
Flash point (°C)
66
93
93
66
Pour point (°C)
20
72
72
12 (winter)
18 (summer)
10 200
9 500
9 500
10 700
0.25
0.25
0.25
0.1
Sulphur total
(max. % weight)
4.0
1.0
1.0
1.8
Water content
(max. % volume)
1.0
1.0
1.0
0.25
GCV (kcal/kg)
Sediment (max. % weight)
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Part 3 Tools and resources
G: Acronyms and abbreviations
General
CDM
CP
CP-EE
EE
EMS
JI
LDPM
MoU
NCPC
NGO
POPs
UNEP DTIE
UNEP
Clean Development Mechanism
Cleaner Production
Integrated Cleaner Production and Energy Efficiency
Energy Efficiency
Environmental management system
Joint Implementation
Luthra Dyeing and Printing Mills (facility assessed for Case Study in Chapter 3)
Memorandum of understanding
National Cleaner Production Centre
Nongovernmental organization
Persistent Organic Pollutants
UNEP’s Division of Technology, Industry and Economics
United Nations Environment Programme
Scientific and technical
°C
A/C
ACFM
AHU
ata
BD
BFB
BFW
BOD
BW
CES
CFL
CFM
CHP
CMH
CO
CO2
COD
COP
Degree Celsius (or centigrade)
Air conditioning
Actual cubic feet per minute
Air handling unit
Atmosphere (as a unit of pressure)
Blow down
Bubbling fluidized bed
Boiler feed water (pumps)
Biochemical oxygen demand (water)
Boiler water
Commercial Energy System
Compact fluorescent light (lamp)
Cubic feet per minute
Combined heat and power
Cubic metres per hour
Carbon monoxide
Carbon dioxide
Chemical oxygen demand (water)
Coefficient of performance
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
CSI
CT
CW
DG
DM
DP
EER
ETI
ETP
F.O.
FAD
FBC
FD
FH
FIFO
GCV
GHG
GLS
GPM
H.P.
H.T.
H2
H2O
Hg
HVAC
HVDC
I
ID
IRR
LAP
L.T.
M&E
M.D.
N
N2
NCV
NG
NOx
G: Acronyms and abbreviations
Current source inverter
Cooling tower
Cooling water
Diesel generator
Demineralized (water)
Pressure drop
Energy efficiency ratio
Economic thickness of insulation
Effluent treatment plant
Fuel oil
Free air delivery
Fluidized bed combustion
Forced draught (fans)
Fired heater
First in, first out
Gross calorific value
Greenhouse gas
General lighting service
Gallons per minute
Horsepower
High tension (voltage)
Hydrogen (molecular)
Water
Mercury (also used in pressure units, i.e. mercury column)
Heating, ventilation and air conditioning
High voltage direct current
Electrical current
Induced draught (fans)
Internal rate of return
Low air pressure (burners)
Low tension (voltage)
Material and energy (balance)
Maximum demand
Speed of rotation (machinery, etc.)
Nitrogen (molecular)
Net calorific value
Natural gas
Nitrogen oxides
Cleaner Production – Energy Efficiency Manual
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Part 3 Tools and resources
NPV
NTP
O&M
O2
P
PCB
P.F. (PF)
PFD
PI
PPM
PWM
R
R&D
RFT
RO
RPM
S
SO2
SO3
SOx
SOP
SPC
TD
TDH
TDS
TFH
TR
TS
VSD
VSI
WB
W.C. (WC)
W.R.T.
WHR
G: Acronyms and abbreviations
Net present value
Normal temperature and pressure (273 K, 1 atm)
Operating and maintenance (costs)
Oxygen (molecular)
Pressure
Printed circuit board
Power factor
Process flow diagram
Profitability index
Parts per million
Pulse width modulation
Refrigeration
Research and development
Right first time
Reverse osmosis (water treatment)
Revolutions per minute
Sulphur
Sulphur dioxide
Sulphur trioxide
Sulphur oxides
Standard operating practice
Specific power consumption
Thermodynamic
Total dynamic head
Total dissolved solids (water)
Thermic fluid heater
Ton of refrigeration (also refrigeration ton)
Total solids (water)
Variable speed drive
Voltage source inverter
Wet bulb
Water column
With respect to
Waste heat recovery
Commonly used and standard abbreviations for units are not included here. The
Conversion Tables (pages 287–292) give explanations of units used in the Manual which
may not be familiar to all readers, in addition to their equivalents in SI or metric units.
Cleaner Production – Energy Efficiency Manual
page 295
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