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Texas
A&M
University
Module 2
ENVIRONMENTAL CHALLENGES:
OVERVIEW FACING INDUSTRY
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Purpose of Module 2
During the past years, the perceptions of pollutions have changed,
industry has to find ways to make products without creating pollution or
to recover and reuse the materials that we have considered wastes,
this philosophy is called pollution prevention.
Process Integration is highly compatible with this philosophy and
complementary to it. This discipline encompasses a number of
methodologies for designing and changing industrial processes, based
on the unity of the whole process.
This module presents an overview of the major environmental
problems facing various industries in North America.
It also presents Process Integration as a systematic approach to solving
environmental problems.
Two major industries (pulp and paper and petroleum refineries) are
used as proof of the concept.
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STRUCTURE OF MODULE 2
The module is divided into three tiers as follows:
TIER 1: Basic Concepts
TIER 2: Case Study
TIER 3: Computer-Aided Module
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TIER 1 : BASIC CONCEPTS
This tier will provide a background including a general
description of the major industries in North America,
and focus on current environmental challenges facing
the pulp and paper as well as the petroleum refining
industries.
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TIER 1 : BASIC CONCEPTS
CONTENTS
This section in broken into three sections:
1. Major Industries in North America.
2. Petroleum Industry
2.1 Driving forces, hurdles and potential.
2.2 Environmental discharges.
2.3 Regulatory issues in North America.
2.4 Best available environmental technologies for specific processes
3. Pulp and Paper Industry
3.1 Driving forces, hurdles and potential.
3.2 Environmental discharges.
3.3 Regulatory issues in North America.
3.4 Best available environmental technologies for specific processes
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1. MAYOR INDUSTRIES IN NORTH AMERICA
The most important industrial sectors in North America were sought not through
their production but reviewing the quantity of their releases and pollutants.
Some statistics are organized by country :
CANADA
USA
MEXICO
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CANADA
INDUSTRIAL SECTORS RELEASING THE LARGEST QUANTITIES OF
POLLUTANTS OFF-SIDE
Tonnes
45000
40000
35000
30000
25000
20000
15000
10000
5000
0
Water, Sewage
and Other
Systems
Pulp, Paper and
Pulp, Paper and
Paperboard
Paperboard Mills
mills
Electricity
Generation,
Transmission
and Distribution
Pesticide,
Fertilizer and
Other
Agricultural
chemical
Manufacturing
Oil and Gas
Extraction
Canada is the world’s largest exporter of commodity-grade pulp
and paper products, making this industry one of the most
important pollutant sector.
More information:
Top 20 pollutants
More Statistics:
Canadian NPRI
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Top 20 Pollutants Released On Site in the Largest Quantities, 2001
Ammonia
Nitrate ion in solution at pH<6.0
Methanol
Hydrochloric acid
Sulphuric acid
Hydrogen sulphide
Xylene (mixed isomers)
Toluene
Methyl ethyl ketone
Carbon disulphide
n-Hexane
Zinc (and its compounds)
Hydrogen fluoride
Ethylene
Ethylene glycol
Manganese (and its compounds)
Styrene
Dicloromethane
Isopropyl alcohol
Formaldehyde
Cyclohexane
2-Butoxyethanol
Acetaldehyde
Benzene
n-Butyl alcohol
Total Releases
(tonnes)
40915.0
22500.8
20427.5
16595.3
9387.3
7234.3
6327.4
5908.5
4137.6
4065.3
3562.8
3310.0
3257.7
2472.0
2347.4
2195.4
1833.0
1777.2
1751.0
1727.0
1382.3
1223.1
1095.4
1047.1
1047.1
CANADA
Top 5 Pollutants Released On Site in the Largest Quantities, 2001
45000.0
40000.0
35000.0
30000.0
Tonnes
Pollutant
25000.0
20000.0
15000.0
10000.0
5000.0
0.0
Ammonia
Nitrate ion in
solution at
pH<6.0
Methanol
Hydrochloric
acid
Sulphuric acid
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U S A
Refineries and petroleum
subproducts are included.
T he U.S. petroleum industry is a strong contributor to the economic health of the United States,
T
its production represents about the 25% of global production.
he Pulp and Paper industry is also important since the U.S. is the world’s largest consumer or
these products, both in total tones per year and in terms of consumption per capita.
More information:
Top 20 pollutants
More Statistics:
TRI
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U S A
Chemical
Top 10 Chemicals with the Largest Total Releases, 2001
2,000,000,000
1,500,000,000
1,000,000,000
500,000,000
Co
pp
er
nHe
Le
xa
ad
ne
Co
m
po
un
ds
Cu
m
en
e
et
ha
no
l
To
Hy
lu
en
dr
oc
e
hl
or
ic
Zi
ac
nc
id
co
m
Co
po
un
pp
ds
er
co
m
pu
nd
s
Et
hy
le
ne
-
M
Total Production Related Waste Managed
(Pounds)
2,500,000,000
Methanol
Toluene
Hydrochloric acid
Zinc compounds
Copper compunds
Ethylene
Copper
n-Hexane
Lead Compounds
Cumene
Ammonia
Propylene
Nitrate compounds
Sulfuric acid
Ethylene glycol
1,2-Dichloroethane
Chlorine
Xylene
Manganese compounds
Nitric acid
Total Production
Related Waste Managed
(Pounds)
2,331,011,667
1,787,944,977
1,504,105,058
1,355,504,817
1,263,772,355
1,256,806,620
1,088,001,030
970,193,833
965,794,108
832,570,075
800,432,076
797,566,959
701,130,070
583,305,201
565,972,276
561,860,469
552,091,471
479,477,559
477,625,043
411,681,261
Subtotal (top 20)
19,286,846,925
Total (all chemicals)
26,735,591,638
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M E X I C O
Petroleum industries provide raw
material
for
the
chemical
industry.e.g.
Gas natural
Ammonia
Fertilizers
Hazardous Pollutants produced by Industry
I n Mexico, the petroleum industry development is strongly linked to the
employment rate, inflation, economic growth and capital investment.
More information
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As we showed in the statistics section, there are two industries which are very
important for the economy and development
and also are causing serious
environmental problems, making a link between the three countries.
This research is attempting to show the way in which Process Integration can be used
successfully. For this challenge we use the two major industries in North America:
Pulp and Paper
Petroleum
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No energy industry today is more engaged than petroleum in serving the global
transportation, power generation, agricultural and consumer products sectors.
Oil and natural gas are essential drivers of economic growth, that implies
enormous social and environmental responsibilities..
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2. Petroleum Industry
2.1 Driving forces, hurdles and potential.
2.2 The Petroleum Refining Industry
2.2.1
2.2.2
2.2.3
2.2.4
Definition
Primary Products
Industrial Processes in the Petroleum Refining Industry
Refinery flow diagram
2.3 Environmental discharges.
2.3.1 Refinery air emission sources
2.3.2 Types of wastewater produced in refineries
2.3.3 Refinery Residuals
2.3.4 Environmental discharges by process
2.4 Regulatory issues in North America.
2.4.1 U.S. Regulations
2.4.2 Mexican Regulations
2.4.3 General Regulations
2.5 Best available environmental technologies for specific processes
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2.1 DRIVING FORCES, HURDLES AND POTENTIALS
The characteristics of the Petroleum Industry are related. In order to understand them, the following diagram in shown.
According to Abdallah S. Jum’ah, president of Saudi Aramco, energy today, must have three characteristics which are
totally interdependent:
RELIABILITY OF SUPPLY
ENVIRONMENTAL
PROTECTION
Environment should be protected
in order to achieve a sustainable
development.
In order to secure reliable supplies
of oil and natural gas, there must be
a price mechanism sufficiently fair
and stable to maintain inflows of
investment capital. In turn, the
investment will help fund the
industry’s considerable measures to
protect environment.
Any nation’s ability to sustain domestic
development will depend on a ready
resource of fuels and feedstock. No
other energy supplier today is more
capable of assuring such a continuity of
supply than the petroleum industry.
REASONABLE PRICE
These three characteristics can act as:
•DRIVING FORCES
•HURDLES
The petroleum industry is one of the most capital-intensive,
high-maintenance, heavily regulated and excessively taxed
industries operating worldwide.
•POTENTIALS
First beak volume 20. 10 October 2002
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•The petroleum refining industry
is a strong contributor to the
economic health of the United
States and Mexico.
•For Mexico, this industry has
become the most important part
in the national economy, it is the
first source of currency for the
country.
•Hydrocarbons will long remain the resource of choice to fuel
future economic progress worldwide. This is a reason not only
to protect air, water and land resources, but also to keep
serving society through these products.
DRIVING FORCES
Economic
and
environmental
situations are involved in the
development of the petroleum
industry, but its final challenge
must be to fulfill the society needs.
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Volatile crude prices
HURDLES
The petroleum industry has been dramatically
impacted over the last three decades by
geopolitical disruptions and volatile world oil
prices. Today refiners must deal with:
Crude quality variability
Low marketing and
transport profit margins
Increasing capital and operating costs
of environmental compliance.
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HURDLES
The environmental
impact produced
by the petroleum
industry covers the
effects of all and
each step in the
energetic
cycle,
which means:
•explotation
•extraction
•refining
•transportation
•storage
•consumption
•releases
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The natural source itself and the reliability of supply
must be the greatest potential for the country that
posses them.
Technology plays an important role in developing the
petroleum industry. Also, research and development
have a great deal to do with keeping petroleum prices
reasonable. In the past, new technologies had
improved our methods of exploration and production,
along with downstream efficiencies that yield cleanerburning automotive fuels and higher-value products
from every barrel of crude oil, allowing the increase
and the improvement of the industry.
The U.S. is the largest, most sophisticated producer of
refined petroleum products in the world, representing
about 25% of global production.
POTENTIALS
Social and environmental issues will
be decisive for the framework
conditions for the future oil and gas
industry. Technology is a tool that
could help in achieving this task.
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2.2 PETROLEUM REFINING INDUSTRY
2.2.1 DEFINITION
Petroleum refining is the physical,
thermal and chemical separation of
crude oil into its major distillation
fractions which are then further
processed through a series of
separation and conversion steps
into finished petroleum products.
Petroleum refineries are a complex
system of multiple operations and
the operations used at a given
refinery
depend
upon
the
properties of the crude oil to be
refined and the desired products.
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2.2.2
The primary products of this industry are divided into three categories:
FUELS
motor gasoline, diesel and distillate
fuel oil, jet fuel, residual fuel oil,
kerosene and coke
CHEMICAL INDUSTRY
FEEDSTOCKS
naphtha, ethane, propane, butane,
ethylene, propylene, butylenes,
butadiene, benzene, toluene and
xylene
FINISHED NON FUEL
PRODUCTS
solvents, lubricating oils, greases,
petroleum wax, petroleum jelly,
asphalt and coke
These products are used as primary input to a vast number of products: fertilizers, pesticides,
paints, waxes, thinners, solvents cleaning fluids, detergents, refrigerants, anti-freeze, resins,
sealants, insulations, latex, rubber compounds, hard plastics, plastic sheeting and synthetic fibers.
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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY
In order to understand where the environmental discharges come from, we will make a review of the refining
process.
The process of oil refining involves five major processes which are briefly described:
SEPARATION
CONVERSION
TREATING
BLENDING
AUXILIARY
SEPARATION PROCESSES
These
processes
involve
separating the different fractions of
hydrocarbon compounds that make
up crude oil base on their boiling
point
differences.
Additional
processing of these fractions is
usually needed to produce final
products to be sold within the
market.
ASSOCIATED OPERATIONS
• Atmospheric distillation
• Vacuum distillation
• Light ends recovery (gas processing)
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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY
SEPARATION
CONVERSION
TREATING
BLENDING
AUXILIARY
ASSOCIATED OPERATIONS
CONVERSION PROCESSES
Include processes used to bread
down large longer chain molecules
into smaller ones by heating using
catalysts.
•
•
•
•
•
•
•
Cracking (thermal and catalytic)
Reforming
Alkylation
Polymerization
Isomerization
Coking
Visbreaking
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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY
SEPARATION
CONVERSION
TREATING
TREATING PROCESSES
Petroleum-treating processes are
used to separate the undesirable
components and impurities such as
sulfur, nitrogen and heavy metals
from the products.
BLENDING
AUXILIARY
ASSOCIATED OPERATIONS
•
•
•
•
•
Hydrodesulfurization
Hydrotreating
Chemical sweetening
Acid gas removal
Deasphalting
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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY
SEPARATION
CONVERSION
TREATING
BLENDING/COMBINATION
PROCESSES
These are used to create mixtures with
the various problem fractions to produce a
desired final product, some examples of
this are lubricating oils, asphalt, or
gasoline with different octane ratings.
BLENDING
AUXILIARY
ASSOCIATED OPERATIONS
•
•
•
•
Storage
Blending
Loading
Unloading
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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY
SEPARATION
CONVERSION
TREATING
BLENDING
AUXILIARY
AUXILIARY PROCESSES
ASSOCIATED OPERATIONS
Processes that are vital to operations
by providing power, waste treatment
and other utility services. Products
from these facilities are usually
recycled and used in other processes
within the refinery and are also
important in regards to minimizing
water and air pollution.
•
•
•
•
Boilers
Waste water treatment
Hydrogen production
Sulfur recovery plant
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LPH and Gas
2.2.4 REFINERY FLOW
DIAGRAM
Refinery fuel gas
Gasoline
Stabilizer
Sweetening
Unit
Sweet Gasoline
LPG
Naphta
Hydrotreating
Middle Distillates
Solvents
Gas
Washed Crude
Gasoline
Gas Oil
Lube-Base
Stocks
Vacuum
Distillation
Catalytic
Cracking
Solvent
Extraction and
Dewaxing
Visbreaker
Light Gas Oil
Lube Oil
Treating and Blending
Middle Distillates
Gasoline
Aviation fuels
Diesels
Heating oils
Lube oils
Waxes
Greases
Gasoline, Naphtha and
Middle distillates
Asphalts
Fuel Oil
Industrial fuels
Asphalt
Refinery fuel oil
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2.3 ENVIRONMENTAL DISCHARGES
Now, that we have seen an overview of the Refinery Process,
we can make some questions:
What is this industry discharging?
How is it discharged?
Where does it come from?
In order to answer these questions, this section will show:
Air emission sources
Wastewater sources
Residuals
Environmental discharges by process
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2.3.1 REFINERY AIR EMISSIONS SOURCES
COMBUSTION EMISSIONS: associated with the burning of fuels in the
refinery, including fuels used in the generation of electricity.
EQUIPMENT LEAK EMISSIONS (fugitive emissions): released through
leaking valves, pumps, or other process devices. They are primarily
composed of volatile compounds such as ammonia, benzene, toluene,
propylene, xylene, and others.
WASTEWATER SYSTEM EMISSIONS from tanks, ponds and sewer system
drains.
PROCESS VENT EMISSIONS: typically include emissions generated during
the refining process itself. Gas streams from all refinery processes contain
varying amounts of refinery fuel gas , hydrogen sulfide and ammonia.
STORAGE TAND EMISSIONS released when product is transferred to and
from storage tanks.
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2.3.2 TYPES OF WASTEWATER PRODUCED IN REFINERIES
COOLING WATER which normally does not come into contact
with oil streams and contains less contaminants than process
wastewater. It may contain chemical additives used to prevent
scaling and biological growth in heat exchanger pipes.
SURFACE WATER RUNOFF is generated intermittently and
may contain constituents from spills to the surface, leaks in
equipment and materials in drains.
PROCESS WASTEWATER that has been contaminated by direct contact
with oil accounts for a significant portion of total refinery wastewater. Many
of these are sour water streams and are also subjected to treatment to
remove hydrogen sulfide and ammonia.
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2.3.3 REFINERY RESIDUALS
Most refinery residuals are in the form of sludge, spend caustics, spend process catalysts, filter clay, and
incinerator ash.
These residuals could be classified as follows:
NON-HAZARDOUS RESIDUALS are incinerated, landfilled or regenerated to provide products that can
be sold off-site or returned for re-use at a refinery.
HAZARDOUS WASTES are regulated under the Resource Conservation and Recovery Act (RCRA).
Listed hazardous wastes include oily sludge, slop oil emulsion solids, dissolved air flotation floats, leads
tank bottom corrosion solids and waster from the cleaning of heat exchanger bundles.
TOXIC CHEMICALS are also use in large quantities by refineries. These are monitored through the Toxic
Release Inventory (TRI).
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2.3.4
DISCHARGES
LIQUID EFFLUENTS
AIR EMISSIONS
Po llutant
Particulate matter
Sulfur oxides
Nitrogen oxides
Benzene, toluene
and xylene (BTX)
VOC
Average rate
kg/t o f crude
0.8
1.3
0.3
0.0025
1
SOLID WASTES
Refineries generate solid wastes and
sludges ranging from 3 to 5 kg per ton
of crude processed, 80% of this sludges
may be considered hazardous because
or the presence of toxic organics and
heavy metals.
Approximately 3.5-5 cubic meters
of wastewater per ton of crude are
generated when cooling water is
recycled.
Po llutant
BOD
COD
Phenols
Oil
Benzene
Benzopyrene
Heavy metals
Chrome
Average rate
mg/l
of
wastewater
150-250
300-600
20-200
100-300
1-100
1-100
0.1-100
0.2-10
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2.3.4 ENVIRONMENTAL DISCHARGES BY PROCESS
PART 1
Process
Air Emissions
Process Waste Water
Residual Wastes
Generated
Crude oil desalting
Heater stack gas (CO,
SOx , NOx , hydrocarbons
and particulates), fugitive
emissions
(hydrocarbons)
Flow = 2.1 Gal/Bbl Oil,
H2S, NH3, phenol, high
levels of suspended
solids, dissolved solids,
high BOD, high
temperature
Crude oil/desalted
sludge (iron rust, clay,
sand, water, emulsified
oil and wax, metals)
Atmospheric
distillation
Heater stack gas (CO,
SOx , NOx , hydrocarbons
and particulates), fugitive
emissions
(hydrocarbons)
Flow = 26 Gal/Bbl Oil,
H2S, NH3 suspended
solids, chlorides,
mercaptans, phenol,
elevated pH.
Typically, little or no
residual waste
generated.
Vacuum distillation
Steam ejector emissions
(hydrocarbons), heater
stack gas (CO, SOx ,
Flow = 2.0 Gal/Bbl Oil,
H2S, NH3, phenol,
suspended solids, high
pH, BOD, COD.
Typically, little or no
residual waste
generated.
NOx , hydrocarbons and
particulates), vents and
fugitive emissions
(hydrocarbons).
Thermal
Heater stack gas (CO,
Cracking/Visbreaking SOx , NOx , hydrocarbons
and particulates), vents
and fugitive emissions
(hydrocarbons)
Coking
Heater stack gas (CO,
Flow = 1.0 Gal/Bbl High Coke dust (carbon
particles and
SOx , NOx , hydrocarbons pH, H2S, NH3,
and particulates), vents suspended solids, COD. hydrocarbons).
and fugitive emissions
(hydrocarbons) and
decoking emissions
(hydrocarbons and
particulates).
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2.3.4 ENVIRONMENTAL DISCHARGES BY PROCESS
PART 2
Process
Catalytic Cracking
Catalytic
Hydrocracking
Air Emissions
Process Waste Water
Residual Wastes
Generated
Heater stack gas (CO,
SOx , NOx , hydrocarbons
and particulates), fugitive
emissions
(hydrocarbons) and
catalyst regeneration
(CO, NOx , SOx , and
particulates).
Heater stack gas (CO,
Flow 1.5 Gal/Bbl High
levels of oil, suspended
solids, phenols
cyanides, H2S, NH3,
high pH, BOD, COD.
Spent catalysts (metals
from crude oil and
hydrocarbons), spent
catalyst fines from
electrostatic
precipitators (aluminum
silicate and metals).
SOx , NOx , hydrocarbons
and particulates), fugitive
emissions
(hydrocarbons) and
catalyst regeneration
(CO, NOx , SOx , and
dust).gas (CO,
Hydrotreating/Hydrop catalyst
Heater stack
rocessing
SOx , NOx , hydrocarbons
and particulates), vents
and fugitive emissions
(hydrocarbons) and
catalyst regeneration
(CO, NOx , SOx , and
catalyst dust).
Flow = 2.0 Gal/Bbl High Spent catalysts fines
COD, suspended solids, (metals from crude oil,
H2S, relatively low levels and hydrocarbons).
of BOD.
Flow = 1.0 Gal/Bbl H2S. Spent catalyst fines
NH3, High pH, phenols (aluminum silicate and
metals).
suspended solids, BOD,
COD.
Alkylation
Heater stack gas (CO,
SOx , NOx , hydrocarbons
and particulates), vents
and fugitive emissions
(hydrocarbons)
Low pH, suspended
solids, dissolved solids,
COD, H2S, spent
sulfuric acid.
Isomerization
Heater stack gas (CO,
Low pH, chloride salts,
SOx , NOx , hydrocarbons caustic wash, relatively
and particulates), vents low H2S and NH3.
and fugitive emissions
(hydrocarbons)
Neutralized alkylation
sludge (sulfuric acid or
calcium fluoride,
hydrocarbons).
Calcium chloride sludge
from neutralized HCl
gas.
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2.3.4 ENVIRONMENTAL DISCHARGES BY PROCESS
PART 3
Process
Air Emissions
Process Waste Water
Residual Wastes
Generated
Polymerization
H2S from caustic
washing.
H2S, NH3, caustic wash, Spent catalyst
containing phosphoric
mercaptans and
acid.
ammonia, high pH.
Catalytic Reforming
Heater stack gas (CO,
SOx, NOx , hydrocarbons
and particulates), HCl
potentially in light ends),
vents and fugitive
emissions
(hydrocarbons)
Flow = 6.0 Gal/Bbl High
levels oil, suspended
solids, COD. Relatively
low H2S.
Spent catalyst fines
from electrostatic
precipitators (alumina
silicate and metals).
Solvent Extraction
Fugitive solvents
Oil solvents
Little or no residual
wastes generated.
Dewaxing
Fugitive solvents, heaters Oil solvents
Little or no residual
wastes generated.
Propane
Deasphalting
Heater stack gas (CO,
Oil solvents
SOx , NOx , hydrocarbons
and particulates), fugitive
propane.
Little or no residual
wastes generated.
Merox treating
Vents and fugitive
Little or no wastewater
emissions (hydrocarbons generated
and disulfides).
Spent Merox caustic
solution, waste oildisulfide mixture.
Wastewater
treatment
Fugitive emissions (H2S, Not Applicable
API separator sludge
(phenols, metals and
oil), chemical
precipitation sludge
(chemical coagulants,
oil), DAF floats,
biological sludges
(metals, oil, suspended
solids), spent lime.
NH3, and hydrocarbons)
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2.3.4 ENVIRONMENTAL DISCHARGES BY PROCESS
PART 4
Process
Gas Treatment and
Sulfur Recovery
Blending
Air Emissions
Process Waste Water
SOx , NOx , and H2S from H2S, NH3, amines,
vent and tail gas
Stretford solution.
emissions.
Fugitive emissions
Little or no wastewater
(hydrocarbons)
generated
Residual Wastes
Generated
Spent catalyst.
Little of no residual
waste generated.
Heat Exchanger
cleaning
Periodic fugitive
emissions
(hydrocarbons)
Oily wastewater
generated
Heat exchanger sludge
(oil, metals, and
suspended solids)
Storage Tanks
Fugitive emissions
(hydrocarbons)
Water drained from
Tank bottom sludge (iron
tanks contaminated with rust, clay, sand, water,
tank product
emulsified oil and wax,
metals)
Blowdown and flare
Combustion products
Little or no wastewater
generated
(CO, SOx , NOx , and
hydrocarbons) from
flares, fugitive emissions
Little or no residual
waste generated.
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2.4 REGULATORY ISSUES IN NORTH AMERICA
The Petroleum Refining Industry is unique in that the environmental requirements aimed at the industry are
of two basic types:
Requirements mandating specific product
qualities for the purpose of reducing the
environmental impacts associated with the
downstream use of the product.
Requirements directed at reducing
the environmental impacts of the
refineries themselves.
For the purpose of this module, we focus on refineries, which will be used to show some Process
Integration techniques.
Petroleum refineries are complex plants, and the combination and sequence of processes is usually very
specific to the characteristics of the raw material and the products. For this reason the regulations for this
sector become very specific and dispersed because an unit have regulations for water, air and land
discharges, all of these managed by different official documents.
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2.4.1 U.S. REGULATIONS
EPA
website
In the case of the United States, there are numerous federal regulations affecting the Refinery
Industry. The Environmental Protection Agency (EPA) contains several regulatory documents
depending on the kind of resource that they pretend to protect, (e.g. Air, water and soil).
Each one of these documents presents requirements which apply for every industrial sector. Then,
when the requirements for a certain industry are needed, specific parts of the document should be
used. For example,
The Clean Air Act Amendments of 1990 has some programs for reducing air emissions from
industry in which refineries are included:
New Source Review,
New Source Performance Standards
National Emission Standards for Hazardous Air Pollutants
At the same time, the New Source Performance Standards have some sections for Refineries:
Subpart J Standards of Performance for Petroleum Refineries
Subpart KKK Standards of Performance for Volatile Organic Liquid Storage Vessels.
Subpart GG Standard of Performances for Stationary Gas Turbines.
Subpart GGG Standards of Performance for Equipment Leaks of VOC in Petroleum Refineries
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2.4.1 U.S. REGULATIONS
All these sections contain flow diagrams,
where depending on the process that is being
used, it must be applied certain norm.
To find more information:
http://www.tnrcc.state.tx.us/permitting/airperm/opd/60/60hmpg.htm
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FEDERAL REQUIREMENTS AFFECTING THE REFINERY INDUSTRY
Requirement
Clean air Act of 1970 (CAA) and regulations
Provisions That Affect Petroleum Refining
National Ambient Air Quality Standards (NAAQS) fix six constituents; new standards under
NAAQS that require control of particulate matter of 2.5 microns or smaller; lead-free gasoline;
low sulfur fuel; reformulated gasoline; hazardous air pollutants; visi
Clean Air Act Amendments of 1990 (CAAA) and Oxygenated Fuels Program for “ nonattainment areas” low sulfur highway diesel fuel;
regulations thereunder.
Reformulated fuels Program; Leaded Gasoline Removal Program; Reid Vapor pressure
regulations to reduce VOCs and other ozon precursors; New Source Review for new or
expande
Resource Conservation and Recovery Act
Standards and regulations for handling and disposing of solid and hazardous wastes.
(RCRA)
Clean Water Act (CWA)
Regulates discharges and spills to surface waters; wetlands.
Safe Drinking Water Act (SDWA)
Regulates disposal of wastewater in underground injection wells
Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA)
“superfund”, liability for CERCLA hazardous substances could apply to wastes generated
during refining, includes past releases, exempts petroleum and crude oil; provides for natural
resource damages.
Emergency Planning and Community Right-toKnow (EPCRA).
Requires annual reporting on the releases and transfers of listed toxic chemicals; reporting
presence of “extremely hazardous substances’ in excess or threshold planning quantities;
reporting certain releases of CERCL hazardous substances and EPCRA extrem
1990 Oil Pollution act and Spill Prevention Control Liability against facilities that discharge oil to navigable waters of pose a threat of doing so.
and Countermeasure Plans
OSHA Health Standards and Process Safety
Management Rules
Toxic Substances Control Act
Limits benzene and other chemical exposures in the workplace, safety plans required in all
refineries.
Collection of data on chemicals for risk evaluation, mitigation and control; can ban chemicals
that pose unreasonable risks.
Energy Policy Act of 1992
Use of alternative fuels for transportation; efficiency standards for new federal buildings,
buildings with federally backed mortgages, and commercial and industrial equipment; R&D
programs for technologies; will reduce demand for petroleum products.
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2.4.2 MEXICAN REGULATIONS
In Mexico, SEMARNAT (Secretaria de Medio Ambiente y Recursos Naturales) is in charge
or the environmental regulations, but it does not cover all aspects of a refinery because
some of them are very specific, for example,
Proyecto NOM-088-ECOL-1994 Establish the maximum permissible levels of pollutants in
the water discharges that become from storage and distribution of petroleum and its
derivates.
A classification of these norms is found in this website:
http://www.semarnat.gob.mx
Then, if the complete document is needed, you can check here:
http://cronos.cta.com.mx/cgi-bin/normas.sh/cgis/index.p
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2.4.3 GENERAL REGULATIONS
Besides all these complicated regulations, an specialized agency of the United Nations, the
World Bank, has established emission levels for the design and operation of refineries,
although country legislation should be accomplished. The guidelines given below present
emissions levels normally acceptable to the World Bank Group.
Emissions from the Petroleum Industry
Effluents from the Petroleum Industry
(milligrams per normal cubic meter)
(milligrams per liter)
Parameter
PM
Nitrogen oxides a
Sulfur oxides
Parameter
pH
BOD
COD
TSS
Oil and grease
Chromium
Hexavalent
Total
Lead
Phenol
Benzene
Benzo(a)pyrene
Sulfide
Nitrogen(total)a
Temperature increase
Maximum value
50
460
150 for sulfur recovey
units; 500 for other
units
Nickel and vanadium
2
(combined)
Hydrogen sulfide
152
Solid Wastes
Generation of sludges should be minimized to
0.3 kg per ton of crude processed, with a
maximum of 0.5 kg per ton of crude
processed.
Maximum value
6--9
30
150
30
10
0.1
0.5
0.1
0.5
0.05
0.05
1
10
<=3 C
World Band Group, 1998. Pollution Prevention and Abatement Handbook. World Bank Group. Pages 377-381.
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2.5 ENVIRONMENTAL TECHNOLOGIES
USED IN THE PETROLEUM INDUSTRY
Primary wastewater treatment
Consists on the separation of
oil, water and solids in two
stages.
1st stage
API separator or
Corrugated plate interceptor.
2nd stage
Chemical
and
physical
methods are utilized to
separate emulsified oils from
the wastewater.
More information
about the equipment
www.panamenv.com
Physical methods may include
the use of series of settling
ponds with a long retention
time, or the use of dissolved air
flotation (DAF).
More information
about the equipment
Chemicals, such
as ferric
hydroxide
or
aluminum
hydroxide are used to coagulate
impurities.
www.panamenv.com
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2.5 ENVIRONMENTAL TECHNOLOGIES
PETROLEUM INDUSTRY
Secondary wastewater treatment
Dissolved oil and other organic
pollutants may be consumed
biologically.
Biological treatment may require
oxygen
through
different
techniques:
• Activated sludge units
• Trickling filters
• Rotating biological contactors.
Polishing
Some refineries employ it as an
additional stage of wastewater
treatment to meet discharge
limits.
Generates bio-mass waste
which is treated anaerobically.
• Activated carbon
• Anthracite coal
• Sand
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2.5 ENVIRONMENTAL TECHNOLOGIES
PETROLEUM INDUSTRY
Gas treatment and Sulfur Recovery
In order to meet the SOx emissions limits and to recover saleable sulfur, refinery process off-gas streams should be treated.
These fuel gases (methane and ethane) need to be
separated before elemental sulfur can be recovered.
Process off-gas streams contain high concentrations of:
hydrogen sulfide + light refinery fuel gases.
Amine + hydrogen sulfide
hydrogen sulfide
This is accomplished by:
• Dissolving the hydrogen sulfide in a chemical
solvent such as diethanolamine (DEA) in an
absorption tower.
• Using dry adsorbents such as molecular sieves,
activated carbon, iron sponge and zinc oxide.
Is then heated and steam stripped to remove the
hydrogen sulfide gas.
Two processes are typically combined to
remove sulfur from the hydrogen sulfide gas
streams:
Beaven Process
Claus Process
Scot Process
Wellman-Land Process
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2.5 ENVIRONMENTAL TECHNOLOGIES
PETROLEUM INDUSTRY
Gas treatment
Other emissions sources come from periodic regeneration of
catalysts, these emissions may contain:
high levels of carbon monoxide + particulates + VOCs.
www.e2t.com/E2T/app_pc05.htm
Before being released to the atmosphere
CARBON MONOXIDE BOILER
To burn carbon monoxide and VOCs
ELECTROSTATIC PRECIPITATOR OR CYCLONE SEPARATOR
To remove particulate matter
Solid waste treatment
Sludge treatment use bioremediation or solvent extraction, followed by combustion of the
residues or by use for asphalt. The residue could require stabilization before disposal to reduce
the leachability of toxic metals.
More information:
www.ppcesp.com
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As we showed in the statistics section, there are two industries which are very
important for the economy and development
and also are causing serious
environmental problems, making a link between the three countries.
This research is attempting to show the way in which Process Integration can be used
successfully. For this challenge we use the two major industries in North America:
Pulp and Paper
Petroleum
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The uses and applications for paper and paper products are limitless. It is
important because it gives us the opportunity or recording, storage and
dissemination of information. Also, it is the most widely used wrapping and
packaging material and it is also used for structural applications.
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3. Paper Industry
3.1 Driving forces, hurdles and potential.
3.2 Overview of the Pulp and Paper process.
3.2.1 Different methods
3.2.2 Main steps of the process
3.3 Environmental discharges.
3.4 Regulatory issues in North America.
3.4.1 U.S. Regulations
3.4.2 Canadian Regulations
3.4.3 General Regulations
3.5 Best available environmental technologies for specific processes
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3.1 DRIVING FORCES
The Pulp and Paper Industry provides employment for vast number of people
and plays a vital role in the overall economy of both the United States and
Canada.
The U.S. forest products industry makes a strong contribution to the national
economy, producing 1.2% of the U.S. GDP.
The industry employed almost 1.3 million people just in the United
States.
Pulp and paper is the third largest industrial polluter to air, water and land in both
Canada and the United States, and releases well over a hundred million kg of toxic
pollution each year.
Paper and wood products are used in many different applications both at home
and at work.
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3.1 HURDLES
The Pulp and Paper industry in North
America is threatened by:
Plantation forests of fast growing tree species are
being developed such countries as Brazil, Indonesia,
Chile.
Quality-stand of timber have become more difficult
and costly to access.
New competitors, with lower fiber costs, have entered
the market (e.g. Russia, Austria, Chile, Australia, New
Zealand and Indonesia).
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3.1 POTENTIALS
The Pulp and paper industry
producers have some advantages:
•The high quality of woodfiber derived from them.
•Potential of the US and
Canadian market.
•Access to a substantial
endowment of timber suitable
for harvesting as saw and
pulp logs.
•Access
secure
energy.
to low-cost,
supplies
of
The strong U.S. economy of the late 1990s has revived the pulp and paper industry. Now, this industry is one
with the biggest average annual pace growth.
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3.2 OVERVIEW OF THE PULP AND PAPER PROCESS
The manufacture of pulp for paper and cardboard employs different methods:
CHEMICAL
MECHANICAL
Chemical pulps are made by cooking
the raw materials, using the kraft
(sulfate) and sulfite processes. Kraft
processes produce a variety of pulps
used mainly for packaging and highstrength papers and board. Oxygen,
hydrogen peroxide, ozone, peracetic
acid, sodium hypochlorite, chlorine
dioxide, chlorine, and other chemicals
are used to transform lignin into an
alkali-soluble form.
Separates fibers by such methods as
disk abrasion and billeting, this pulp
can be used without bleaching to
make
printing
papers
for
applications
in
which
low
brightness is acceptable. For other
applications,
bleaches
like
peroxides and hydrosulfites must be
used.
CHEMIMECHANICAL
A combination of the
previous processes.
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3.2 OVERVIEW OF THE PULP AND PAPER PROCESS
The main steps in pulp and paper manufacturing are:
Wood yard
Pulping
These steps are common for
the three processes, although
the difference is the units they
use for each task.
Bleaching
The significant environmental
impacts of the manufacture of
pulp and paper result from the
pulping and bleaching processes.
Paper
manufacture
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3.2 OVERVIEW OF THE PULP AND PAPER PROCESS
This table presents the purpose of each one of the processes presented before and the technologies
used to reach their task.
PROCESS
PURPOSE
MAJOR
TECHNOLOGIES
PULPING
Convert wood chips of wastepaper
into fibers suitable for papermaking.
Chemical
(Kraft,
sulfite)digesters,
mechanical
–
refiners, semi chemical –
digesters & refiners.
CHEMICAL
RECOVERY (KRAFT
PULPING)
Recovery of inorganic chemicals
from spend pulping liquor and
combustion of organic residuals to
produce energy.
Evaporation
concentration
recovery boiler, causticizing,
calcining.
BLEACHING
Brighten of whiten pulps by using
chemicals to selectively remove
lignin.
Chlorine dioxide, oxygen,
hypochlorite, peroxide, ozone,
of chlorination- upflow of
downflowtowers,
vacuum
washers, pumps, mixers.
PAPER
MANUFACTURE
Prepare stock from pulp, sheet,
dewater, dry, caleder.
Heat box, sheet forming table.
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3.3 ENVIRONMENTAL DISCHARGES
LIQUID EFFLUENTS
AIR EMISSIONS
Po llutant
Av e ra g e ra te s
Kg /t o f AD P
Bla ck liq u o r o xid a tio n
Reduced sulfur compounds:
0.3-3
Hydrogen sulfide
Methyl mercaptan
Dimethyl sulfide
Dimethyl disulfide
Particulate matter
Sulfur oxides
Nitrogen oxides
Volatile organic compounds (VOCs)
75 -150
0.5 - 30
1--3
15
15-30
Ste a m a n d e le ctricity g e n e ra tin u n its
Fly ash
Wastewaters
BOD
Total suspended solids
COD
Chlorinated organic compounds:
Dioxins
Furans
Adsorbable organic halides
Av e ra g e ra te s
Kg /t o f AD P
20-250 m3/t
10--40
10--50
20-200
0-4
SOLID WASTES
Pu lp in g
Sulfur oxides
Pollutant
100
ADP: Air dried pulp, defined as 90% bone-dry fiber and 10% water.
t:metric ton.
The principal solid wastes of concern include
wastewater treatment sludge : 50-150 kg/t of ADP.
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3.4 REGULATORY ISSUES
U.S. REGULATIONS
The key federal group responsible for the environment is the
EPA, which is a regulatory agency that establish and enforce
environmental standards.
AIR REGULATIONS
The purpose of the EPA is to conduct research and suggest
solutions to environmental problems. Simultaneously, it has
an obligation to monitor and analyze the environment.
The components of the legislation that most influence the
pulp and paper industry are the effluent limitation
WATER REGULATIONS
guidelines that define minimum effluent conditions for 1977
and 1983.
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WATER REGULATIONS
BACKGROUND
BACKGROUND
PARAMETERS
PARAMETERS
TOXIC
TOXIC
POLLUTANTS
POLLUTANTS
NewUp
source
performance
stardard
in kg/kkg
to 1970,
stream quality
standards
in the United States were largely
Maximum 30-day average
Maximum /day
the responsibility of individual states. The federal government became
Subcategory
BDO5
TSS
BDO5
TSS
dominant until 1970, when the
Environmental Protection
Agency
Dissolving kraft
6.1
8.35
11.75
15.5
(EPA)
Market
kfaftwas established.
2.65
2.9
5.15
5.35
1972, the Federal Water3.7
Pollution Control
Act stipulated
a stepBCTInkraft
5
7.05
9.3
Finewise
Draft schedule for meeting2.55
7
conventional3.75
discharge 4.95
criteria, the first
Papergrade
sulfite
4.65
2.9
8.98
5.35
target level by 1977 being equivalent to “best practical technology”
Market
sulfiteand the second target
4.65
2.9 being equivalent
8.95
5.35
(BPT),
level by 1983
to “best
Low alpha dissolving sulfite
11.15
10
21.45
18.6
available technology economically achievable”(BATEA).
High alpha dissolving sulfite
13.8
9.45
26.5
17.6
GW:Inchemimechanical
3.3
7.5 or sub-toxic
6.15
the early 1980’s these 3.9
regulations included
toxic
GW:substances
thermomechanical
2.3
3.15 Discharge
4.45 Elimination
5.85
through the National
Pollutant
GW:CMN
papers
2
3.15
3.85
System (NPDES). Among these were a number of byproducts5.85
of
GW: fine papers
1.9
3
5.6
5.6
the chlorine bleaching process. Later, the EPA has increased the list
Soda
3.15
4.3
60
7.95
of
priority
pollutants.
Deink
3.9
4
7.5
7.45
NI fine
1.35
1.4 environmental
2.6
2.6
Thepapers
U.S federal regulations
that deal with
protection
NI tissue
papers
2.15
2.2
4.15
4.1to
change every four years. It is a constant challenge to this industry
NI tissue papers (FWP)
1.9
1.95
3.7
3.65
keep up-to-date.
GW: groundwood
Other agencies:
NI: nonintegrated
• Effluent Standards and Water Quality Information Advisory Committee (ES&WQIAC).
• The Council of Environmental Quality.
• National Commission on Water Quality
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TOXIC POLLUTANTS
Acenaphthene
Acrolein
Acrylonitrile
Aldrin/dieldrin
Antimony and compounds
Arsenic and compounds
Asbestos
Benzene
Benzidine
Beryllium and compounds
Settlement agreement toxic pollutants:
Cadmium and compounds
Carbon tetrachloride
Chlordane
Chlorinated benzenes
Chlorinated ethanes
Chloralkyl ethers
Chlorinated napthalene
Chlorinated phenols
Chloroform
2-Chlorophenol
Chromium and compounds
Copper and compounds
Cyanides
Naphtalene
Nickel and compounds
Nitrobenzene
Nitrophenols
Nitrosamines
DDT and metabolites
Dichlorobenzene
Dichlorobenzidine
Dichloroethylenes
2,4-Dichlorophenol
Dichloropropane and dichloropropene
2,4-Dimethylphenol
Dinitrotoluene
Diphenylhydrazine
Endosulfan and metabolites
Endrin
Ethylbenzene
Haloethers
Halomethanes
Heptachlor and metabolites
Hexachlorocyclohexane
Hexachlorocyclopentadiene
Isophorone
Lead and compounds
Mercury and compounds
Silver and compounds
2,3,7,8-Tetrachlorodibenzo-p-dioxin
Tetrachloroethylene
Thalium and compounds
Toluene
Toxaphene
Trichloroethylene
Pentachlorophenol
Phenol
Phthalate esters
Polychlorinated bephenyls
Vinyl chloride
Polynuclear
aromatic
hydrocarbons
Zinc and compounds
Selenium and compounds
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AIR REGULATIONS
The Clean Air Act of 1963, was a benchmark piece of legislation. It represented
Representative MACT II limits
the first allocation by the federal government of significant funds for air pollution
problems.
GENERAL INFORMATION
BACKGROUND
BACKGROUND
PARAMETERS
Talking about the Pulp and Paper industry, the objective of
air Mill
regulations
is Emission
the elimination
of tohazardous
air pollutants
type
pointdecided
PMform
HAP the U.S.
TGO HAP
In 1970,
President
Richard
Nixon
Environmental
Recovery
funace
PM
<
0.015
grains/dry
<
0.025
lb/tonControl
of black
Protection
Agency,
which
absorbed
the
National
Air
Pollution
such as methanol, total reduced sulfur gases, and chlorine.
Administration.
standard
cubic
foot
at
8%
liquor
solids
(BLS)
Maximum achievable control technology (MACT) is the level
Kraft of
andcontrol
soda
oxygen
at the average of the
best 12% of the mills in the
The Clean Air Act Amendments
of 1970,
covered
primary areas:
Smelt dissolving
tank PM
< 0.12 three
lb/ton BLS
None
EPA
data
base
of
that
category.
•Attainment and maintenance of National Ambient Air Quality Standards
(NAAQS).
Lime kiln
PM < 0.01 grains/dry None
•Establishment
regulations
the sorted
emission
ofmill
The MACTofrules
have covering
three tiers
type.pollutants from
standard
cubicby
foot
atcertain
8%
mobile
and
stationary
sources.
•MACT I is for chemical oxygen
pulp mills including kraft,
•Establishment of New Source Performance Standards (NSPS).
Sulfitesulfite.
combustion PM < 0.02 grains/dry
semichemical, and
EPA established standards for seven pollutants: sulfur dioxide, total suspended
units kraft, soda,
standard cubic foot at 8% and sulfite
•MACT
II
is
for
particulates, carbon monoxide, nitrogen semichemical
oxides, photochemical oxidants,
Sulfite
oxygen
combustion
sources
including
units, smelt
hydrocarbons,
and lead.
NAAQS needed
reviewrecovery
every five years.
Chemical recovery None
< 2.97 lb/ton BLS or
dissolving tanks, and lime kilns.
Stand
alone
semichemical
combustion
units
90% reduction
The 1990 CAA is probably the most dramatically impacting air pollution
legislation
•MACT III is for paper machines, mechanical pulping and
of all time became law in 1990. Possibly most important to the pulp and paper
secondary
fiber and
nonwood
fiber.
HAP:the
particulate
matter
hazardous
industryPMwas
new air
toxics
controlmaterial.
program. The 1990 law relied on
TGO to
HAP:
totalemissions
gaseous organic
material.
technology
control
of 189hazardous
hazardous
air pollutants.
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CANADIAN
CANADIANREGULATIONS
REGULATIONS
BACKGROUND
BACKGROUND
BACKGROUND
PARAMETERS
In first
1992,
federal Canadian
government
released
The
set the
of regulations
for the pulp
and paper
industry,
REGULATIONS
newWATER
Pulp and
Paper Effluent Regulations under the
which came into force in 1971, did not limit the total amount
of Fisheries
pollution, Act.
but rather permitted the discharge of pollutants
MAXIMUM
AND MAXIMUM
in proportion
to theBDO
production
of the mill. QUANTITY OF
TheSUSPENDED
PPER set limits
on BOD5,
TSS, and FOR
acuteMILLS.
toxicity
SOLIDS
AUTHORIZED
had numerous
reporting
requirements.
Regulations
In and
1991,
the federal
government
responded
to public
limiting
the
discharge
of
chlorinated
dioxins
and
pressure by introducing a regulatory scheme that furans
required
also
went
into
effect
in
1992
under
the
Canadian
mills to implement secondary treatment systems and abide
Protection
(CEPA). of certain harmful
byEnvironmental
limits
to control
the Act
discharge
AIR REGULATIONS
pollutants, including dioxins and furans.
TheTHERE
CEPA and
massive
AREPPER
NO regulations
LEGALLY resulted
BINDINGin a
CANADIAN
investment
to
change
bleaching
processes
and
install
FEDERAL
OR PROVINCIAL
FOR
AIRset
In 1992,
the Pulp
and Paper REGULATIONS
Effluent Regulations
EMISSIONS
FROM before
PULP the
MILLS
FOR
AMBIENT
AIR
secondary
treatment
end
of
1996
at
a
many
minimum
standards.
QUALITY.
Canadian mills.
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MAXIMUM BDO AND MAXIMUM QUANTITY OF SUSPENDED SOLIDS AUTHORIZED FOR MILLS.
Except where an authorization or transitional authorization is issued authorizing the
deposit of BDO matter or suspended solids, the maximum BDO of all BDO matter and the
maximum quantity of all suspended solids that may be deposited in the case of a mill is
determined by:
In respect of any 24-hour period, the formula:
Qd  F * 2.5 * RPR
In respect of any month the formula:
Qm  F * D *1.5 * RPR
Where :
F = is equal to a factor of 5 in respect of BDO and 7.5 in respect
of suspended solids, expressed in kilograms per tonne of finished
product.
RPR = is the reference production rate.
D = number of days in a month.
Original source: Department of Justice Canada
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3.4.3 GENERAL REGULATIONS
Emissions levels for the design and operation of each project must be established throuth the environmental assessment process on
the basis of country legislation and the Pollution Prevention Handbook, which establishes the following.
Air Emissions
Liquid effluents
(milligrams per normal cubic meter)
Parameter
PM
Hydrogen sulfide
Total sulfur emitted
Sulfite mills
Kraft and other
Nitrogen oxides
Maximum value
100 for recovery furnace
15 (for lime kilns)
1.5 kg/t ADP
1.0 kg/t ADP
2 kg/t ADP
Parameter
pH
COD
AOX
Total phosphorus
Total nitrogen
Temperature
Maximum value
6--9
300 mg/l and 15 kg/t for kraft and
CTMP pulp mills; 700 mg/l and
40kg/t of sulfite pulp mills; 10 mg/l
and 5kg/t of mechanical and
recycled fiber pulp; 250 mg/l for
paper mills
40 mg/l and 2 kg/t (aim for 8 mg/l
and 0.4 kg/t and retrofits and for 4
mg/l and 0.2 kg/t for new mills)
and 4 mg/l for paper mills
0.05 kg/t
0.4 kg/t
<3C
Source: Pollution Prevention and Abatement Handbook 1998. World Bank Group. P 395-399
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3.5 ENVIRONMENTAL TECHNOLOGIES
PULP AND PAPER INDUSTRY
Gas treatment
In the kraft pulping process, highly emissions of reduced sulfur compounds, measured as total reduced sulfur (TRS) and
including hydrogen sulfide, methyl marcaptan, dimethyl sulfide, and dimethyl disulfide, are emitted.
Sulfur oxide emissions are scrubbed with slightly
alkaline solutions.
More information:
www.jrfindia.com
The reduced sulfur-compounds gases are collected
using headers, hoods, and venting equipment.
Condensates from the digester relief condenser
and evaporation of black liquor are stripped of
reduced sulfur compounds.
More information:
www.wesinc.com
Stripper overhead and noncondensable are
incinerated in a lime kiln or a combustion
unit.
Texas
A&M
University
3.5 ENVIRONMENTAL TECHNOLOGIES
PULP AND PAPER INDUSTRY
Wastewater treatment
To remove suspended solids:
•
•
•
•
To remove the organic content:
Neutralization
Screening
Sedimentation
Flotation
• Activated sludge
• Aerated lagoons
• Anaerobic fermentation
More information:
www.sequencertech.com
Solid waste treatment
Solid waste treatment steps include dewatering of sludge and combustion in an incinerator, bark boiler, or fossil-fuelfired boiler.
Texas
A&M
University
TIER 2 : STUDY CASE
This tier will demonstrate the relevance of Process
Integration for specific examples of key processes in
the Pulp and Paper Industry as well as in Refineries.
Texas
A&M
University
STUDY CASE 1
KRAFT PULPING PROCESS
(Dunn and El-Halwagi, 1993)
As we saw in Tier 1, the Pulping Process can be accomplished by
chemical, semichemical or mechanical methods. About 80% of the
wood pulp in the United States is produced through the kraft
chemical pulping process.
A environmental problem associated with the kraft process is the
atmospheric emission of considerable quantities of hydrogen
sulfide.
The serious health and environmental problems of
discharging hydrogen sulfide to the atmosphere call for effective
sulfur-waste reduction processes in a pulp and paper plant.
The purpose of this study case is to employ the Mass Exchange
Network methodology to develop an optimal design of
recycle/reuse networks for reducing the emission of hydrogen
sulfide for pulp and paper plants.
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
Causticizers
PULP
Weak Black
Liquor
Evaporators
Lime Mud
Contaminated
Condensate
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Wood chips, containing ligning,
PULP
cellulose and hemicellulose are
added to white liquor (NaOH,
Na2S, Na2CO3). The chips are
cooked to solubilize the lignin.
Washers
Weak Black
Liquor
Evaporators
Causticizers
Lime Mud
Contaminated
Condensate
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
Weak Black
Liquor
Evaporators
Causticizers
PULP
Contaminated
Condensate
The solubilized lignin leaves as
black
liquor,
leaving
the
cellulose and hemicellulose
which are the constituents of
pulp.
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Lime Mud
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
Weak Black
Liquor
Evaporators
Causticizers
PULP
Contaminated
Condensate
It is sent to the bleaching
of papermaking process,
depending on the end
product desired.
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Lime Mud
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
Weak Black
Liquor
Evaporators
Causticizers
PULP
Contaminated
Condensate
The main constituents of White
Liquor are:
NaOH, Na2S,
Na2CO3, Na2SO4, Na2S2O3, NaCl,
water.
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Lime Mud
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
Weak Black
Liquor
Evaporators
Causticizers
PULP
Contaminated
Condensate
The Weak Black Liquor is
processed through a series of
evaporators to increase the solid
content from 15% to 70%
approximately.
Strong Black
Liquor
Recovering
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Lime Mud
Slaker
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
Weak Black
Liquor
Evaporators
Causticizers
PULP
Contaminated
Condensate
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Lime Mud
The Strong Black Liquor is
incinerated to supply energy for
the pulping process and to form
inorganic smelt.
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
Causticizers
PULP
Weak Black
Liquor
Evaporators
Lime Mud
Contaminated
Condensate
Na2CO3 and Na2S
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
Causticizers
PULP
Weak Black
Liquor
Evaporators
Lime Mud
Contaminated
Condensate
Smelt is dissolved in water
to form the Green Liquor.
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
Causticizers
PULP
Weak Black
Liquor
Evaporators
Lime Mud
Contaminated
Condensate
NaOH, Na2S, Na2CO3 and
water.
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
Weak Black
Liquor
Evaporators
Causticizers
PULP
Lime (CaO) is converted
to CaOH2 in presence of
water.
Lime Mud
Contaminated
Condensate
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
Washers
CaOH2 reacts with Na2CO3
to form NaOH and a
CaCO3 as precipitant.
Weak Black
Liquor
Evaporators
Causticizers
PULP
Lime Mud
Contaminated
Condensate
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
The CaCO3 is heated to
regenerate the CaO and
release CO2.
Lime Kiln
Washers
Causticizers
PULP
Weak Black
Liquor
Evaporators
Lime Mud
Contaminated
Condensate
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
DESCRIPTION OF THE KRAFT PROCESS
CHIPS
White Liquor
Clarifier
White Liquor
Digester
Lime Kiln
NaOH, Na2S, NaCO3 and
water.
Washers
Causticizers
PULP
Weak Black
Liquor
Evaporators
Lime Mud
Contaminated
Condensate
Slaker
Strong Black
Liquor
Recovering
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Lime
Texas
A&M
University
EMISSION SOURCES OF THE KRAFT PROCESS
CHIPS
White Liquor
White Liquor
Clarifier
Digester
Three major sources in the Kraft Process are
Responsible for the majority of the H2S emissions.
PULP
Washers
Lime Kiln
Causticizers
R3
Air
Emission
Weak Black
Liquor
R2
Evaporators
Contaminated
Condensate
Evaporators
Air
Lime Mud
Air
Air
Stripping
Stripping
Lime
Slaker
Wastewater
Strong Black
Liquor
R1
Recovering
Recovery
Furnace
Furnace
Smelt
Dissolving
Tank
Green
Liquor
Texas
A&M
University
INTERNAL MASS SEPARATING AGENTS
CHIPS
S1
Several Mass-Exchange operations
such as absorption or adsorption can be
White
White Liquor
Liquor
White Liquor
employed to reduce the H2S emissions.
Digester
Clarifier
Three liquid streams that already exist in the plant
(process MSAs) can be used.
PULP
Washers
Lime Kiln
Causticizers
Weak Black
S2
Liquor Black
Weak
Air
Emission
Lime Mud
Liquor
Evaporators
Contaminated
Condensate
Air
Smelt
Slaker
Wastewater
Strong Black
Liquor
Recovering
Furnace
Lime
Air
Stripping
Dissolving
Tank
S3
Green
Green
Liquor
Liquor
Texas
A&M
University
EXTERNAL MASS SEPARATING AGENTS
Three external MSAs will be considered potential
candidates for recovering H2S:
• S4, Diethanolamine (DEA)
• S5, Activated Carbon
• S6, 30 wt% Hot potassium carbonate solution
Texas
A&M
University
Evaporator Emissions, R2
R3, Air Stripping Emissions
White Liquor, S1
S1
Green Liquor, S2
S2
REACTIVE
Black Liquor, S3
DEA, S4
S3
MASS-EXCHANGE
NETWORK
Activated Carbon, S5
S4
S5
Hot K2CO3 solution, S6
S6
R1
R2
To atmosphere
R3
Texas
A&M
University
Evaporator Emissions, R2
R3, Air Stripping Emissions
Dissolving
Causticizer
DigesterTank
Evaporators
Digester
Slaker
White Liquor, S1
S1
Green Liquor, S2
S2
REACTIVE
Black Liquor, S3
DEA, S4
S3
MASS-EXCHANGE
NETWORK
Activated Carbon, S5
S4
S5
Hot K2CO3 solution, S6
S6
R1
R2
To atmosphere
R3
Texas
A&M
University
DATA FOR THE KRAFT PROCESS PROBLEM
DATA FOR THE WASTE STREAMS
Stream
R1
R2
R3
Emissions stream
Gi
description
Recovery furnace
Evaporator
Air stripping
m3/s
170.000
0.433
465.800
yi s
kmol/m 3
3.08 x 10-5
8.20 x 10-5
1.19 x 10-5
yi t
kmol/m 3
2.1 x 10-7
2.1 x 10-7
2.1 x 10-7
DATA FOR THE MASS SEPARATING AGENTS
Stream
S1
S2
S3
S4
S5
S6
Stream description
White liquor
Green liquor
Black liquor
DEA
Activated carbon
Hot KCO3 solution
Max.
available
flowrate
m3/s
0.040
0.049
0.100



x js
x jt
kmol/m 3
3.2 x 10-1
2.9 x 10-1
0.2 x 10-1
2.0 x 10-6
1.0 x 10-6
0.3 x 10-2
kmol/m 3
3.10 x 100
1.29 x 100
1.00 x 10-1
2 x 10-2
1.7 x 10-3
2.8 x 10-1
Texas
A&M
University
DESIGN METHODOLOGY
We are looking forward the potentials for waste reduction in the Kraft Process by establishing
tradeoffs between environmental and economic objectives in order to obtain the optimal
configuration for a Waste-reduction system.
The solution of this problem will follow two different approaches:
GRAPHICAL
ALGEBRAIC
Texas
A&M
University
OBTAIN
PINCH POINT
PLOT LEAN
STREAM
CREATE
ONE-TO-ONE
CORRESPONDENCE
PLOT RICH STREAM
INTERPRET
THE RESULTS
GRAPHICAL APPROACH
These are the main steps that we will follow to find an optimal design of recycle/reuse
networks for reducing the emission of hydrogen sulfide from a pulp and paper plant using a
GRAPHICAL APPROACH.
Texas
A&M
University
0.01
R2
0.00907
0.009
0.00904
0.008
R1
Mass
Exchanged
kmol H2S/s
0.007
0.006
The first step is to plot the mass exchanged or
each rich stream versus its composition.
0.005
0.00544
The slope of the arrows will be equal to the stream
Each stream
represented
as an arrow
whose
flowrate
and isthe
vertical distance
between
thetail
tail
Each
arrow
should
be
placed
starting
with
the
waste
corresponds
to
its
supply
composition
and
its
and the head of each arrow represents the mass of
stream
having
the
lowest
composition.
head
to itsthat
target
composition.
pollutant
is lost
by
eachtarget
rich stream:
MRi=Gi(yis – yit), i=1,2,…,NR.
0.004
0.003
R3
0.002
0.001
0
0.00E+00
y1,2,3t
1.00E-05
y3s
2.00E-05
3.00E-05
y1s
4.00E-05
5.00E-05
6.00E-05
7.00E-05
8.00E-05
y2s
y
9.00E-05
GRAPHICAL APPROACH
RICH COMPOSITE STREAM
Texas
A&M
University
GRAPHICAL APPROACH
RICH COMPOSITE STREAM
0.01
0.01
0.009
0.009
0.008
0.008
Mass
Mass
Exchanged
Exchanged
kmol H2S/s
kmol H2S/s
0.007
0.007
This rich composite stream
represents the cumulative
mass of the pollutant lost by
all the streams.
0.006
0.006
0.005
0.005
The rich composite stream is
obtained by applying superposition
to the rich streams.
0.004
0.004
0.003
0.003
0.002
0.002
0.001
0.001
00
0.00E+00
0.00E+00 1.00E-05
1.00E-05
y
2.00E-05
2.00E-05
3.00E-05
3.00E-05
4.00E-05
4.00E-05
5.00E-05
5.00E-05
6.00E-05
6.00E-05
7.00E-05
7.00E-05
y
8.00E-05 9.00E-05
9.00E-05
8.00E-05
Texas
A&M
University
The second step is to generate a one-to-one correspondence among compositions of the three waste
streams and the six MSAs.
Consider a waste stream i, and and MSA, j, for which equilibrium is given by:
yi*= fi(xj*)
For any mass-exchange operation to be thermodynamically feasible, some
conditions must be satisfied:
xj<xj*
and/or yi>yi*
To generate the one-to-one correspondence, we use the following equation:
y=f(xj+εj)
Where εj is the minimum allowable composition difference, which means that
we are adding a driving force to allow mass transfer.
A deep explanation of
these concepts is
given in Module 3.
GRAPHICAL APPROACH
ONE-TO-ONE CORRESPONDENCE
Texas
A&M
University
Some examples of the generation of the one-to-one correspondence are the following:
MSA1
White liquor
MSA2
Green liquor
Equilibrium equation
y1= 2.0402 x 10-9(10)1.1786x1
y2= 2.5763 x 10-9(10)2.8136x2
Adding the driving force
y1= 2.0402 x 10-9(10)1.1786(x1+ε1)
ε1 = 7.64
y2= 2.5763 x 10-9(10)2.8136(x2+ε2)
ε2 = 3.20
Supply correspondence
y1s= 2.0402 x 10-9(10)1.1786(0.32+7.64)
y1s= 4.91
y2s= 2.5763 x 10-9(10)2.8136(0.29+3.20)
y2s= 17.00
Target correspondence
y1t= 2.0402 x 10-9(10)1.1786(3.10+7.64)
y1t= 9186
y2t= 2.5763 x 10-9(10)2.8136(1.29+3.20)
y2t= 11068
The equilibrium equation for the MSA3 (Black liquor) is:
y3=352.8 x30.71512
GRAPHICAL APPROACH
ONE-TO-ONE CORRESPONDENCE
Texas
A&M
University
0.18
0.18
The mass of pollutant that can be gained by each process
MSA is plotted
versus
the composition
scale
Once again,
we used
the diagonal rule
of of that MSA
0.16
0.16
superposition to obtain the cumulative mass
of the pollutant gained by all the MSAs.
0.14
0.14
Mass of pollutant that can be gained by each MSA is
calculated:
Mass
Exchanged
kmol H2S/s
0.12
Mass
Exchanged
kmol H2S/s
GRAPHICAL APPROACH
LEAN COMPOSITE STREAM
0.12
0.1
MSj= Ljc (xjt – xjs)
0.1
j=1,2,…,NSP
0.08
0.06
0.08
Also in this case, the arrows represent each of the process
MSA, being the tail the supply composition and the head the
target composition.
0.04 0.06
0.02 0.04
0
0.02
0.00E+00
1.00E-05
0.32
0.29
y
2.00E-05
3.00E-05
4.00E-05
5.00E-05 6.00E-05
7.00E-05
8.00E-05
9.00E-05
1.00E-04
x
1
3.1
x2
1.29
0
0.00E+00 1.00E-05
0.02
2.00E-05 3.00E-05
4.00E-05
5.00E-05
6.00E-05
7.00E-05 8.00E-05
0.01
9.00E-05
x3 y
1.00E-04
Texas
A&M
University
PICH POINT
GRAPHICAL APPROACH
0.18
0.16
Mass
Exchanged
kmol H2S/s
0.14
Lean
Composite
Stream
Thevertical
lean
composite
can
be
slid
The
vertical
overlap stream
between
two
The
distance
referred
asthe
Excess
To
guarantee
thermodynamic
The
next
step
is
to
plot
both
down
until
it
touches
the
waste
composite
streamscorresponds
is the maximum
Mass
Exchanged
to the
feasibility
the lean
composite
composite
stream.
The
point
where
composite
streams
on
the
same
amount
of
the
pollutant
that
can
be
capacity
of
the
process
MSAs
to
remove
should
be
above and
left touch
of theis
the
two
composite
streams
diagram.that
transferred
from
the waste
streams
to
pollutants
cannot
be used
because
waste
composite
stream.
called
“mass
exchange
pinch point”.
process
MSAs.
ofthe
thermodynamic
infeasibility.
0.12
0.1
Excess
Mass
Exchanged
0.08
0.06
0.04
Rich
Composite
Stream
0.02
Pinch
Point
0
0.00E+00
1.00E-05
2.00E-05
3.00E-05
4.00E-05
5.00E-05
6.00E-05
Integrated
Mass Exchange
7.00E-05
8.00E-05
9.00E-05
y
1.00E-04
Texas
A&M
University
The Algebraic Approach follows these steps:
TABLE OF
EXCHANGEABLE
LOADS (TEL)
COMPOSITION
INTERVAL
DIAGRAM
CREATE ONE-TO ONE
CORRESPONDENCE
ALGEBRAIC APPROACH
MASS-EXCHANGE
CASCADE
DIAGRAM
Texas
A&M
University
The CID is a useful tool for visualizing the
mass exchange insuring thermodynamic
feasibility.
ALGEBRAIC APPROACH
COMPOSITION-INTERVAL DIAGRAM (CID)
Texas
A&M
University
RICH STREAMS
ALGEBRAIC APPROACH
COMPOSITION-INTERVAL DIAGRAM (CID)
LEAN PROCESS STREAMS
y x 109
x1
x2
82000
1
2
3
4
5
6
7
0
30800
11900
11068
1.
The composition
2. Corresponding
composition scale for the waste stream is established.
scales for the process MSAs
are created.
9186
210
17.0
4.86
1
2
3
4
5
6
Texas
A&M
University
RICH STREAMS
LEAN PROCESS STREAMS
y x 109
82000
1
30800
2
3
x1
x2
R2
These intervals are numerated
From top to bottom.
Horizontal lines are drawn at the
heads and tails of the arrows to
define composition intervals.
R1
11900
S3
R3
3. Each process stream is represented as a vertical arrow
11068
4
ALGEBRAIC APPROACH
COMPOSITION-INTERVAL DIAGRAM (CID)
9186
5
The tail of each arrow represents its supply composition and its head
represents its target composition.
210
6
17.0
7
S2
4.86
0
S1
1
2
3
4
5
6
Texas
A&M
University
By constructing the TEL, we want to determine the mass-exchange loads
of the process streams in each composition interval.
The exchangeable lead of each waste stream with passes through each
interval is defined as:
Wi,kR = Gi(yk-1 – yk)
W1,1R = 0.433(0.000082-0.0000308)
W1,2R = 117(0.0000308-0.0000119)
W2,2R = 0.433(0.0000308-0.0000119)
Wj,kS = Lj(xj.k-1 – xj,k)
W1,4S = 0.049(1.29-1.261)
W1,5S = 0.04(3.1-1.708)
W2,5S = 0.049(1.261-0.678)
WkR = Σ Wi,kR
WkS = Σ Wj,kS
W2R = W1,2R + W2,2R = 0.0022
W5S = W1,5S + W2,5S = 0.0842
ALGEBRAIC APPROACH
TABLE OF EXCHANGEABLE LOADS (TEL)
Texas
A&M
University
ALGEBRAIC APPROACH
TABLE OF EXCHANGEABLE LOADS (TEL)
Material Balance of the key pollutant should be done for each interval.
Residual Mass from
Preceding Interval
δ k-1
Mass Recovered
From Waste
Streams
WkR
WkS
k
δk
Residual Mass to
Subsequent Interval
Mass Transferred
To MSAs
Texas
A&M
University
0
0.00002
1
0
0.00002
0.002219
2
0
0.00224
A negative δk indicates that the
The most negative δk is the excess
capacity of the process leans streams
capacity of the process MSAs when
at that level is greater than the load
removing the pollutant.
of the waste streams.
0.000477
3
0
0.00272
0.001106
4
0
0.00382
0.005235
5
0.05568
-0.04662
0
6
0.03708
-0.08370
0
7
-0.10214
0.01844
ALGEBRAIC APPROACH
TABLE OF EXCHANGEABLE LOADS (TEL)
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ALGEBRAIC APPROACH
TABLE OF EXCHANGEABLE LOADS (TEL)
0
2.22E-05
1
0
0.00002
The excess capacity of the process MSA should be
2
0
reduced0.002219
by lowering the flowrate.
0.00224
The new flowrate is calculated as follows:
0.000477
L  0.04 
0.001106
3
0
1.02 E  1
 0.003259 m3/s
0.00272
3.10  0.32
4
0
Another TEL should be constructed after removing
0.00382
the excess capacity of the MSA.
0.005235
5
On
the
revised
cascade
diagram the location at which
the residual mass was the most
negative should be zero. It
corresponds to the pinch point.
0.004608
0.00445
0
6
0.003068
0.00138
0
7
0.00
0.001526
PINCH POINT
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Since the graphical approach, we saw that the pollutant could be removed just by using one MSA,
so there is no need of a network. This problem has some different solutions that could be taken
depending on how much we want to spend. The following figure is one solution, in which some
material balance should be done in order to give the right flowrate to each absorber.
R1
R2
m3/s
117
3.08e-5 kmol/m3
0.44
8.20e-5 kmol/m3
0.547 kmol/m3
Absorber
1
2.1e-7kmol/m3
R3
m3/s
m3/s
465.8
1.19e-5 kmol/m3
0.547 kmol/m3
Absorber
2
2.1e-7kmol/m3
0.0158 m3/s
0.320 kmol/m3
0.547 kmol/m3
Absorber
3
2.1e-7kmol/m3
1.56e-4 m3/s
0.320 kmol/m3
White Liquor
0.0158 m3/s
0.320 kmol/m3
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R1
117 m3/s
3.08e-5 kmol/m3
R2
0.44 m3/s
8.20e-5 kmol/m3
R3
465.8 m3/s
1.19e-5 kmol/m3
3.10 kmol/m3
Absorber
581.24 m3/s
2.1e-7 kmol/m3
0.00326 m3/s
0.32 kmol/m3
White Liquor
Another way of achieve this task is
the following, in which the rich
streams are for final disposal and can
be mixed and treated as one stream,
also, his arrange is more desirable in
terms of costs because just one unit
is needed.
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STUDY CASE 2
PETROLEUM REFINERY WASTES
A major concern in refineries is the release
of phenols, although described as this, the
category may include a variety of similar
chemical compounds among which are
polyphenols,
chlorophenols,
and
phenoxyacids. The concern is because of
their toxicity to aquatic life and the high
oxygen demand they sponsor in the
streams that receive it. Phenols are toxic
to fish and also they can cause taste and
odor problems when present in potable
water.
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PROBLEM STATEMENT
The next study case applies some of the skills of Process Integration to show the
methodology once again and make it more understandable. This case was taken from ElHalwagi, M. “Pollution Prevention through Process Integration”, 1997.
“The process generates two major sources of phenolic wastewater; one from the catalytic
cracking unit and the other from the visbreaking system. Two technologies can be used
to remove phenol from R1 and R2: solvent extraction using light gas oil S1 (a process
MSA) and adsorption using activated carbon S2(an external MSA). A minimum allowable
composition difference, εj, of 0.01 can be used for the two MSAs.
By constructing a pinch diagram for the problem, find the minimum cost of MSAs needed
to remove phenol from R1 and R2. How do you characterize the point at which both
composite streams touch? Is it a true pinch point?”
DATA
MSAs
Rich stream
Stream
R1
R2
Gi
kg/s
8.00
6.00
yis
yit
Stream
0.1
0.08
0.01
0.01
S1
S2
Lcj
kg/s
10.00
xjs
xjt
mj
bj
0.01
0.00
0.02
0.11
2.00
0.02
0.00
0.00
cj
$/kg
0.00
0.08
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LPH and Gas
Refinery fuel gas
PROCESS DESCRIPTION
Gasoline
Stabilizer
Sweetening
Unit
Sweet Gasoline
LPG
Naphta
The first step in a
petroleum refinery
is to preheat the
crude, then it is
washed with water
to remove various
salts.
Hydrotreating
Middle Distillates
Solvents
Gas
Gas Oil
Lube-Base
Stocks
Vacuum
Distillation
Treating and Blending
Middle Distillates
Gasoline
Aviation fuels
Gas oil and heavy stocks are fed to a catalytic-cracking unit
to be converted to lower molecular weight fractions. The
The waste
light gas
oil Gasoline
leaving
fractionator
can
serve from
as a
main
stream
from
thisthe
process
is the condensate
Diesels
lean-oil
solvent
in
a
phenol
extraction
process,
being
this
a
stripping
Catalytic in the fractionating column. This condensate
Light
Gas
Oil
beneficiary
mass
transfer
because
in
addition
to
purify
Cracking contains ammonia, phenols and sulfides as
commonly
water, phenolsthis
canhas
acttoasbe
oxidation
andoils
as color
contaminants,
strippedinhibitors
to remove
ammonia
Heating
stabilizers.
and sulfides.Wastewater,
The bottom
product of the stripper must be
R1
treated to eliminate phenols.
Solvent
Extraction and
Dewaxing
Lube Oil
Lube oils
Waxes
Greases
Gasoline, Naphtha and
Asphalts
The main objectives
of visbreaking are to reduce the
Middle distillates
viscosity and the pour points of vacuum-tower bottoms
Oil stocks to catalytic cracking. The
and to increase theFuel
feed
Visbreaker
Industrial fuels
source of wastewater
is
Asphalt the overhead accumulator on the
fractionator, where water is separated from the
Wastewater,
R2 water contains phenols, ammonia
hydrocarbon
vapor. This
Refinery fuel oil
an sulfides
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1. PLOT THE RICH STREAM
1.2
1
R1
Mass exchanged
0.8
0.6
0.4
R2
0.2
0
0
y1t, y2t
0.02
0.04
0.06
0.08s
y2
0.1s
y1
0.12
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1. PLOT THE RICH STREAM
1.2
Mass exchanged
1
0.8
R1
0.6
0.4
R2
0.2
0
0
y1t, y2t
0.02
0.04
0.06
0.08
y2s
0.1
y1
0.12
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2. ONE-TO-ONE CORRESPONDANCE
To generate the one-to-one correspondence, we use the following equation:
y=f(xj+εj)
Where εj is the minimum allowable composition difference. εj=0.01
In this case the equilibrium equation is linear:
y = m(x+ε) + b
y1s = 2(0.01+0.01) =
0.04
y2s = 0.02(0.00+0.01) =
0.0002
y1t = 2(0.02+0.01) =
0.06
y2t = 0.02(0.11+0.01) =
0.0024
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3. PLOT THE LEAN STREAM
1.2
1
0.8
0.6
0.4
0.2
S1
MS1
y
0
0
0.02
0.04
x1s
S2
0.06
x1t
0.08
0.1
0.12
x1
x2
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4. OBTAIN THE PINCH POINT
1.2
1
Mass exchanged
0.8
Stream 1 would not be useful, since
external MSAs should be used before and
after using this stream. That means that
this is not a true pinch point.
0.6
0.4
0.2
y
0
0
0.02
0.04
0.06
0.08
0.1
0.00
0.01
0.02
0.03
0.04
1.00
2.00
3.00
4.00
5.00
0.12
x1
x
2
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5. INTERPRET THE RESULTS
1.2
Unit 1
1
0.1
The lean stream can be moved to remove
the pollutant in another range of
composition, but still three units would be
needed.
0.8
Mass exchanged
Unit 2
0.6
Unit 3
0.4
0.2
y
0
0
0.02
0.04
0.06
0.08
0.1
0.12
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5. INTERPRET THE RESULTS
1.2
Unit 1
1
0.8
If the lean stream remove the pollutant
since its higher composition, just 2 units
are needed.
0.6
Unit 2
0.4
0.2
y
0
0
0.02
0.04
0.06
0.08
0.1
0.00
0.01
0.02
0.03
0.04
1.00
2.00
3.00
4.00
5.00
0.12
x1
x
2
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5. INTERPRET THE RESULTS
1.2
Mass removed by
Process MSA
Mass exchanged
1
0.8
0.6
Mass removed by
External MSA
0.4
0.2
0
y
0
0.02
0.04
0.06
0.08
0.1
0.12
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•Alan P. Rossiter. Waste Minimization through Process Design. pp 43-49. McGraw Hill. 1995.
•Nicholas P. Cheremisinoff, Handbook of Pollution Prevention Practices. pp 269-313, 353-358. Marcel Dekker Inc. 2001.
•The World Bank Group. Pollution Prevention and Abatement Handbook 1998. pp 377-381, 395-399. 1998
•El-Halwagi, M. M. Pollution Prevention through Process Integration. Academic Press. 1997.
•Dunn R., El-Halwagi, M. M. Optimal Recycle/Reuse Policies for Minimizing the Wastes of Pulp and Paper Plants. J. Environ. Sci. Health, A28(1), 217-234
(1993).
•El-Halwagi, M.M., El-Halwagi, A.M., Manousiouthakis, V. Optimal Design of the Phenolization Networks for Petroleum-Refinery Wastes. Trans IChemE,
Vol 70, Part B, pp 131-139. August 1992.
•Environmental Update #12, Hazardous Substance Research Centers/Southwest Outreach Program, June 2003.
•Abdallah S. Jum’ah, president and CEO, Saudi Aramco. Petroleum and social responsibility: and agenda for action. News Feature. First bread volume
20. 10 October 2002.
•Energy and Environmental Profile of the U.S. Petroleum Refining Industry. December 1998. U.S. Department of Energy, Office of Industrial
Technologies
•EPA Office of Compliance Sector Notebook Project, Profile of the Petroleum Refining Industry, September 1995.
•National Pollutant Release Inventory (Canada)
•2001 Toxic Release Inventory Executive Summary (US)
•Input to the AMG Working Group Studying the Impact of Greenhouse Gas Abatement on the Competitiveness of Canadian Industries. Pulp, Paper and
Paperboark Mills. Manufacturing Industries Branch. Industry Canada. March 11, 2002
•Instituto Nacional de Estadistica, Geografia e Informatica (Mexico)