Feasibility Study
Site Selection
- Plant Layout and environmental issue
- Site Location
Chemical Engineering Design
Site Design Issues:
Layout and
Environmental Impact
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Site Selection & Layout
• Where will the project or plant be built?
• How much land and how many buildings will be needed?
• How will the process equipment be laid out?
• How will the plant be connected to offsites and storage
areas?
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Site Selection Factors
Exercise: What factors do companies consider
when deciding where to build a new plant?
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Site Selection Factors
Resource availability
Tax regime
(Water, land, fuel, power)
Raw materials
availability
Availability of
skilled labor
Cost of labor
(and other fixed costs)
Transport facilities
Nearness to
markets
(Roads, ports, rail, pipelines)
Political and
strategic factors
Environmental impact
Not all trade-offs will be captured by economic analysis!
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Site and Plant Layout
• Site layout goals:
– Easy access to plants for workers, emergency responders
• Lots of access roads, space between units
– Buildings located away from hazardous areas
– Allow space between process units
• At least 30m, more if processes are hazardous
– Storage areas have access to transportation infrastructure
• Locate near main road entrance so tanker drivers don’t have to drive
through the plant
• Stores also need shipping and receiving area
– Smooth flow of materials between plants, storage, utility plant
• Reduce length of pipe runs, utility system heat losses
– Make allowance for future plant expansion
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Example Site Layout
Available area
Major road
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Example Site Layout
Rail siding
Gatehouse
Tank farm
• Locate tank farm with access to road and rail
• Preferably also so that prevailing wind carries
vapors away from plant
Major road
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Example Site Layout
Rail siding
Gatehouse
Tank farm
Fire
House
S&R
Stores
Labs
Offices
Maintenance
Workshops
Canteen
Access road
High-occupancy buildings
need road access & parking,
should be upwind of plant
Major road
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Example Site Layout
Rail siding
Gatehouse
Tank farm
Fire
House
S&R
Stores
Maintenance
Workshops
Labs
Offices
• Grid of roads for allround access to plants
• Access to plants
restricted except in
emergency
Canteen
Emergency access gates, normally closed
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Major road
Chemical Engineering Design
Example Site Layout
Rail siding
Utility
Plant
Gatehouse
Tank farm
Fire
House
S&R
Stores
Labs
Offices
Maintenance
Workshops
Canteen
Plant 1
Plant 2
Area 1
Plant 3
Plant 4
Plant 2
Area 2
Major road
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Example Site Layout
Rail siding
Utility
Plant
Gatehouse
Tank farm
Fire
House
S&R
Stores
Labs
Offices
Maintenance
Workshops
Canteen
Plant 1
Plant 2
Area 1
Plant 4
Plant 2
Area 2
Areas to allow for future expansion
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Plant 3
Major road
Chemical Engineering Design
Example Site Layout
Rail siding
Utility
Plant
Gatehouse
Tank farm
Plant 1
Pipe bridge
Fire
House
S&R
Stores
Labs
Offices
Maintenance
Workshops
Canteen
Plant 2
Area 1
Plant 3
Plant 4
Plant 2
Area 2
Major road
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Plant Layout
• Usually carried out using CAD tools
• Locate major equipment items to minimize pipe runs, allow
ease of access for maintenance
• Locate at grade:
• Large items with special foundation requirements or frequent
maintenance needs
• Equipment subject to vibration (pumps, compressors, solids handling)
• Make use of open 3-D steel structure so not all items are at
grade (when practical to do so)
• Locate control room away from noise, hazards
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Chemical Engineering Design
Environmental Impact
Processes must meet acceptable environmental standards
because:
•
It is required by law
•
The costs (human, social, economic) of non-compliance
can be catastrophic
•
Lax attitudes are reflected in insurance premiums, stock
prices
•
Moral and ethical obligations
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Environmental Regulations
• Emissions from chemical plants are regulated by
national government (e.g. US EPA) and local
government agencies (e.g. SCAQMD)
• Chemical plant management must
– Monitor and document waste streams discharged to the
environment
– Maintain the necessary permits from the relevant government
agencies
– Pay fines or other penalties to address any violations
• Government agencies are able to order a facility to
cease operating & send management to jail in extreme
cases
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Environmental Impact
• Air pollution
• Water Pollution
• Hazardous Waste
• Waste Minimization
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Environmental Impact
• Air pollution
• Water Pollution
• Hazardous Waste
• Waste Minimization
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Air Pollution
Common air pollutants from chemical plants include:
• SOx
• NOx
From fired heaters, boilers, flares
• CO2
• Particulates (PM10, PM2.5)
• Volatile Organic Compounds (VOC)
• Chlorine compounds (less common)
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Air Pollution
Common air pollutants from chemical plants include:
• SOx
• NOx
• CO2
• Particulates (PM10, PM2.5)
From solids
handling
operations
• Volatile Organic Compounds (VOC)
• Chlorine compounds (less common)
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Air Pollution
Common air pollutants from chemical plants include:
• SOx
• NOx
• CO2
• Particulates (PM10, PM2.5)
From vents, tanks,
fugitive emissions
• Volatile Organic Compounds (VOC)
• Chlorine compounds (less common)
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Air Pollution
Impacts of these air pollutants include:
• SOx
Acid rain
• NOx
Acid rain, ozone, greenhouse gas
• CO2
Acid rain, greenhouse gas
• Particulates (PM10, PM2.5)
Smog
• Volatile Organic Compounds (VOC)
Smog, ozone, GHG
• Chlorine compounds (less common)
Ozone, GHG
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
How Ozone is Formed
Sources: Houston Regional Monitoring and
Business Coalition for Clean Air
FAVORABLE
CONDITIONS
Solar
Energy
•High temperature
•Low wind speed
•Low cloud cover
OXYGEN
Ground Level
Ozone (O3)
Formation
50 %
Industry
69%
NOx
Trees, Shrubs, Swamps
VOC’s
2%
14%
Industry
9%
Off-Road
8%
Cars & Trucks
Note: large amount
of NOx produced by
industry
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Natural Sources
18 %
Off-Road
30 %
Cars & Trucks
Chemical Engineering Design
Global Warming
• The basic principles of the “Greenhouse Effect” are well
understood
– Radiation from the earth is absorbed by gases
– Acts like insulation and maintains habitable surface temperatures
on earth
– Water vapor causes 80-90% of this effect
• The “Enhanced” Greenhouse Effect is the concern (i.e.,
increased CO2 from human activities creates “forcing” large
enough to cause global warming)
• The remaining uncertainties are
– How much warmer will it get?
– What will be the consequences?
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Global Warming
• Six main Greenhouse Gases (GHG) and their Global
Warming Potentials (GWP) - “ability to trap the sun’s
heat”
— CO2 - 1.0 (highest volume, most concern!)
— CH4 - 21
— N2O - 310
— Others: HFC’s, PFC’s SF6 - range 140 - 23,900
• 1997 Kyoto Protocol - reduce GHGs 5.2% worldwide
from 1990 levels by 2008-2012.
—
—
—
—
U.S. did not sign, India and China did not have targets
Most of those that did sign will not meet targets
Many countries are imposing CO2 taxes though
Governments are creating greater incentives for energy
efficiency & renewable energy sources
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
U.S. Clean Air Act Amendments of 1990
The Clean Air Act (CAA); 42 U.S.C. s/s 7401 et seq. (1970)
TITLE
I
II
III
IV
V
VI
VII-XI
SUBJECT
Provisions for Attainment and Maintenance
of National Ambient Air Quality Standards
Provisions Relating to Mobile Sources
Hazardous Air Pollutants
Acid Deposition Control
Permits
Stratospheric Ozone Protection
Enforcement, Research, Miscellaneous
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Chemical Engineering Design
Air Pollution Regulatory Approaches
• Goal Oriented
–
U.S. National Ambient Air Quality Standards (NAAQS)
•
EPA sets allowable ambient levels for seven contaminants
–
•
Set two levels based on receptor
–
–
•
Ozone, CO, lead, nitrogen dioxide, sulfur dioxide, PM10
PM2.5
Primary Standard (for public health, baseline levels)
Secondary Standard (for public welfare, more strict)
“Attainment” or “Non-attainment” Areas
• Technology Based
– U.S. National Emission Standards for Hazardous Air Pollutants
(NESHAP)
• Standards based on best 12% controlled facilities in each industry
• 189 Hazardous Air Pollutants (HAPs)
–
Maximum Available Control Technology Rule (MACT) of CAAA
Refinery MACT1995 – organics from vents, leaks, tanks, drains
• Refinery MACT II 2002 – vents of non-organics
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Chemical Engineering Design
Towler & Sinnott Chemical Engineering Design only. Do not copy
•
Impact of Clean Air Act Amendments
Stoddard, J.L., Kahl, J.S., Deviney, F.A., DeWalle, D.R., Driscoll, C.T., Herlihy, A.T., Kellogg, J.H., Murdoch, P.S.,
Webb, J.R., & Webster, K.E. Response of Surface Water Chemistry to the Clean Air Act Amendments of 1990. U.S.
EPA., Research Triangle Park, N.C., 2003.
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Impact of Clean Air Act Amendments
• Data shows
large impact
on surface
water acidity
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Impact of Clean Air Act Amendments
• Less impact on
NOx as this was
not regulated as
tightly
• As of July 2007,
USA had no NOx
non-attainment
areas
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Chemical Engineering Design
Ozone Non-Attainment
• 0.08 ppm 8 hr
standard
• Federal
reformulated
gasoline (RFG)
is mandatory in
non-attainment
areas
• > 1/3 of U.S.A.
is currently on
RFG
Source www.epa.gov
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Ozone Reduction
• Most VOCs
come from plants
• Scope for
reducing
industrial VOC
emissions is
small
Sources: Houston Regional Monitoring and
Business Coalition for Clean Air
FAVORABLE
FAVORABLE
CONDITIONS
CONDITIONS
Solar
Energy
•High
•Hightemperature
temperature
•Low
•Lowwind
windspeed
speed
•Low
•Lowcloud
cloudcover
cover
OXYGEN
OXYGEN
Ground Level
Ozone (O3)
Formation
50 %
Industry
69%
NOx
NOx
Trees, Shrubs, Swamps
VOC’s
VOC’s
14%
• Focus has now
shifted towards
more stringent
controls on NOx
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Industry
18 %
Off-Road
9%
Off-Road
2%
Natural Sources
8%
30 %
Cars & Trucks
Cars & Trucks
Chemical Engineering Design
Air Pollutant Emissions Control
• SOx
–
Easiest method is to remove S from fuel
•
•
Substitute Nat Gas or low sulfur heating oil for bunker oil
Amine scrub fuel gas more deeply: U.S. EPA - 162 ppm H2S in fuel gas (20
ppm SO2 in flue)
– More expensive is SOx capture by flue gas scrubbing (FGD)
• NOx
Must distinguish between “fuel” and “thermal” NOx
– Fuel N can be addressed by substitution
– Lower flame temperatures reduce thermal NOx
–
•
•
–
Steam injection
Burner design
Numerous tail gas treatment processes are available
•
•
Selective catalytic reduction (SCR) with NH3
Biological treatment, non-catalytic reduction, …
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Chemical Engineering Design
Fuel Desulfurization
Sweet gas
Acid gas
Lean
amine
• Simple amine
absorption process
allows fuel gas sulfur to
be reduced to 40 ppm
at low cost
Steam
Sour gas
Rich amine
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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• H2S can be reduced to
1 ppm or less using
advanced absorption or
adsorbent processes
Chemical Engineering Design
Catalytic De-NOx
•
Very Expensive
•
Operates at 400-700°F
•
Used in Retrofits when
Ultra-Low NOx burners
cannot be used
•
Coupled with air preheat
system
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Chemical Engineering Design
Air Pollutant Emissions Control
• CO
– Reduced by burning using excess air (but bad effect on NOx)
• CO2
– Not currently regulated
– Can be recovered for underground storage, oil recovery
– CO2 capture from high pressure gases is relatively cheap
• Can use amine processes similar to fuel desulfurization
• Physical solvents such as Selexol are usually cheaper
– “Oxyfuel” combustion using pure oxygen makes CO2 collection
easier, but is capital intensive
– Cost of CO2 capture and disposal ~ $40/ton
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Air Pollutant Emissions Control
• Particulates
– Mechanical collectors, e.g. cyclones
•
•
For bulk separation
High loadings, e.g., Catalytic cracking
– Electrostatic Precipitators (ESPs)
•
•
Electrical charges cause dust to migrate
across streamlines by electrophoresis
Useful for smaller particles
– Fabric Filters (“Baghouses”)
•
•
Lower loadings
Higher pressure drop
– Wet Gas Scrubbers
•
•
Low pressure drop
Transfers air pollutant into liquid stream
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Electrostatic Precipitator
Chemical Engineering Design
Air Pollutant Emissions Control: VOCs
• Recovery
– Condensation
•
Cheap, but seldom meets target
– Scrubbing
•
Low ΔP, but creates liquid waste
– Adsorption
•
Effective & expensive
Adsorption Plant
• Destruction
– Incineration (purpose, heater or flare)
•
Expensive, but can recover fuel value
– Catalytic oxidation
•
Works to very low levels, but catalysts can be sensitive
– Biological treatment
•
Cheap, but low throughput and sensitive to toxics
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Chemical Engineering Design
Air Pollutant Emissions Control: VOCs
• Fugitive emissions
– Can be 20 – 80% of VOC emissions
• Sources include
– Valves (packings, open line valves)
– Seals on pumps, compressors, instruments
– Flanges
– Pressure relief valves
– Tank roof seals
• Can be reduced by
– Improved inspection and maintenance
– Better equipment
•
•
Dual seals, seal-less pumps, dry gas seals
Welded instead of flanged joints
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Air Pollutant Emissions Control: VOCs
• VOCs are also emitted from site
waste water
– Open drains
– Water treatment plant
P-Leg Trap
Drain Type
Seal Pot
Drain Type
Drain
Pipe
• Drains are common on plant
– Sample points
– Instruments
– Maintenance
Drain
Pipe
Drain
Funnel
Seal
Seal
12" Diameter
x
8" Deep Sump
• Specify closed drains or water
sealed drains when necessary
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Chemical Engineering Design
Environmental Impact
• Air pollution
• Water Pollution
• Hazardous Waste
• Waste Minimization
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
U. S. Water Pollution Regulations
1972 Federal Water Pollution Control Act
(“Clean Water Act” 33 U.S.C. ss/1251 et seq.,
1977 )
•
Achieve clean water for swimming, boating, and
protecting fish and wildlife by 1983
•
Amended 1977 and 1987 with focus on toxics and
water quality
•
EPA sets water quality standards for pollutants in
surface waters
•
EPA sets effluent guidelines for each industrial sector
•
Unlawful to discharge any pollutant into navigable
waters without a permit
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Chemical Engineering Design
Water Pollution
Water pollutants include:
• Process waste streams
– Sour waters (H2S, NH3)
– Salt waters (neutralized streams, softeners, deionizers, etc.)
– Hydrocarbon contaminated process waters
– Biologically contaminated waters (e.g. broths)
– High ph/low ph waters (spent acids and caustics)
•
Utility waste streams
– Cooling tower water blowdown (usually largest source)
– Boiler blowdown
•
Run-off streams
– Rain water
– Hydrant flushing
– Equipment washing
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Wastewater Treatment Systems
Biological
Treatment Aeration
Clarifier
Gravity Sand Filter
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Water Pollution
•
Process waste streams
–
–
–
–
–
•
Utility waste streams
–
–
•
Sour waters (H2S, NH3)
Salt waters (neutralized streams, softeners, deionizers, etc.)
Hydrocarbon contaminated process waters
Biologically contaminated waters (e.g. broths)
High ph/low ph waters (spent acids and caustics)
Cooling tower water blowdown (usually largest source)
Boiler blowdown
Run-off streams
–
–
–
Rain water
Hydrant flushing
Equipment washing
• Low concentrations of certain highly
toxic pollutants set performance
limits for biological treatment
• Waste water segregation and use of
multiple treatment processes is
usually most economical
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Environmental Impact
• Air pollution
• Water Pollution
• Hazardous Waste
• Waste Minimization
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
U. S. Hazardous Waste Regulations
Resource Conservation and Recovery Act (RCRA)
42 U.S.C. s/s 321 et seq. 1976
•
Ultimate objective is to protect groundwater from
contamination
•
“Cradle-to-grave” hazardous waste management
– From identification as a waste to final disposal
– Generator identifies waste as “hazardous” if it is on a regulatory
list or if it has a characteristic of flammability, toxicity, corrosivity
or reactivity
– Hazardous wastes must be labeled and tracked in transport
– Treatment is required to low levels of contaminants
– Final disposal into a hazardous waste landfill of residual solid
material (e.g., incinerator ash)
•
Addresses only current and future facilities (not
abandoned or historic sites – see SARA)
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Chemical Engineering Design
Final Disposal of Wastes
• Incineration
– Usually not cheapest, but may recover fuel value
– Possible issue with chlorine containing wastes and dioxin formation
• Landfill
–
Usually after pretreatment such as dewatering, neutralization, biotreatment,
extraction, vitrification, fixation, etc.
– If hazardous by regulatory definition then requires treatment to reduce
contaminants to very low level
• Land Treatment (“land-farming”)
–
Sludge is spread over a large area of land and degraded by soil microbes
– Useful for oil sludges, spent adsorbents, etc.
– Care must be taken to control waters to prevent groundwater contamination
• Recycle
–
If a viable case can be made, e.g., rubber, aluminum
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Typical Treatment for Specific
Oil Refinery Solid Wastes
SOLID WASTE
TYPICAL TREATMENT
Tank bottom sludges
Oil recovery, incineration, fixation
Cooling tower sludges
Fixation
Exchanger bundle cleaning sludges Fixation
Coke fines
Incineration, fixation
Spent catalysts
Neutralization, metals recovery, fixation
Chemical precipitation sludges
Incineration, fixation
Silica gels
Fixation
Organic wastes
Incineration
Waste biological sludges
Dewatering, land application, incineration
Pathogenic wastes
Incineration
API separator sludge/waste oils
Oil recovery, incineration and fixation
© 2012 G.P. Towler / UOP. For educational use in conjunction with
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Chemical Engineering Design
Hazardous Waste from Abandoned
Operations
Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA or Superfund) 42 U.S.C. s/s 9601 et seq.
(1980)
• Created a tax on the chemical and petroleum industries for cleaning up
abandoned or uncontrolled hazardous waste sites
• Established prohibitions and requirements concerning closed and
abandoned hazardous waste sites and provided for liability of persons
responsible for releases of hazardous waste at these sites
The law authorized two kinds of response actions:
• Short-term removals, where actions may be taken to address releases
or threatened releases requiring prompt response.
• Long-term remedial response actions, that permanently and
significantly reduce the dangers associated with releases or threats of
releases of hazardous substances that are serious, but not immediately
life threatening.
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Chemical Engineering Design
The Superfund Amendments and
Reauthorization Act (SARA)
42 U.S.C.9601 et seq. (1986)
•
Amended CERCLA and made additions to the program
•
Stressed the importance of permanent remedies and innovative treatment
technologies in cleaning up hazardous waste sites
•
Required Superfund actions to consider the standards and requirements found
in other State and Federal environmental laws and regulations
•
Increased State involvement in every phase of the Superfund program
•
Increased the focus on human health problems posed by hazardous waste sites
•
Encouraged greater citizen participation in making decisions on how sites should
be cleaned up
•
Increased the size of the trust fund to $8.5 billion.
•
Required EPA to revise the Hazard Ranking System (HRS) to ensure that it
accurately assessed the relative degree of risk to human health and the
environment posed by uncontrolled hazardous waste sites
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Chemical Engineering Design
Environmental Impact
• Air pollution
• Water Pollution
• Hazardous Waste
• Waste Minimization
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Chemical Engineering Design
Waste Minimization
• Instead of treating the waste at the “end of pipe” we try
to reduce or eliminate it by better process design
• The heirarchy of waste management approaches is:
Source Reduction
Don’t make it in the first
place – Best Practice
Recycle
Find a use for the waste
stream
Treatment
Disposal
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Reduce the severity of
impact
Meet the requirements of
the law
Chemical Engineering Design
Source Reduction Strategies
• Reduce feed impurities by purification
– Usually leads to fewer components in waste
– Can reduce purge and vent requirements
• Protect catalysts and adsorbents
– Use guard beds or scrubbers to prevent deactivation
• Eliminate extraneous materials used for separation
– Mass separating agents such as solvents
• Increase recovery from separations
– Enhance product recovery
– Purify recycle streams
• Improve fuel quality
Partly taken from: Smith, R. & Petela, E. Waste Minimization in the Process Industries: 3. Separation and
Recycle Systems Chem. Eng., 513, 13, 1991
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Waste Minimization 5-Step Review
• Step 1: Identify waste components
for regulatory impact
• Step 2: Identify process waste
streams for size, economic impact
• Step 3: List root causes of wastes
• Step 4: List & analyze
modifications to address root
causes
• These steps can be
addressed by
putting together an
Effluent Summary
• At the design stage,
many effluents will
be estimated rather
than measured, but
the ability to make
changes is greater
• Step 5: Prioritize and implement
the best solutions
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Effluent Summary
Project Name
Project Number
Company Name
Address
REV
Sheet
DATE
BY
APVD
REV
DATE
BY
EFFLUENT SUMMARY
Form XXXXX-YY-ZZ
Owner's Name
Plant Location
Case Description
Units
English
Metric
PROCESS EMISSIONS
Pollutant
Nitrogen Oxides
Process Source (Stream No. if avail.)
Vapor Emissions
Measurement (estimate) method Continuous / Intermittent
kg/day
kg/yr
Regulatory Status
Total
Sulfur Oxides
Total
Particulate matter
1
APVD
• Lists regulated
pollutants and
summarizes
sources, quantities
Total
Volatile organic compounds
Total
HAPs (list by name)
Aqueous Waste Streams
Contaminant
Stream Name
Process Source (Stream No. if avail.)
Water flow kg/day
Contaminent flow kg/day
Stream Name
Process Source (Stream No. if avail.)
Organic Waste Streams
Measurement (estimate) method Component
kg/day
kg/yr
Stream Name
Process Source (Stream No. if avail.)
Solid Waste Streams
Measurement (estimate) method Component
kg/day
kg/yr
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Contaminent flow metric ton/yr Concentration (wt%)
• Sections for
process and
associated offsites
• Helps to focus and
prioritize pollution
prevention activities
Chemical Engineering Design
Additional Reasons for Estimating
Effluents
• May be a requirement for getting National / Local
Government permits to operate the plant
• May be a requirement for getting insurance
• May be a requirement for obtaining loans or securing
funding for construction
• May be a regulatory requirement
• May help to anticipate or avoid large mitigation costs
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Environmental Impact: Conclusion
• Be “environmentally responsible” as a design engineer
– Understand the environmental issues
– Understand your legal and ethical obligations
– Understand the best available control and remediation technologies
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Process Intensification
• Process intensification means carrying out the same process
operation using smaller equipment or smaller inventories
• This is an important strategy for increasing the inherent safety of a
process
• Process intensification is not the same thing as process
miniaturization
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
• Just-in-time manufacture – lower inventories
• In-line mixers – lower inventories
• Structured column packings – less hold-up
• Plate heat exchangers – lower ΔT, less volume
• Monolith catalysts – lower ΔT, better mass tfr
• Micro-channel reactors – better mass tfr
• HiGee fractionation – better mass tfr
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Increasing Commercial Acceptance
Process Intensification Techniques
Chemical Engineering Design
Process Intensification vs. Process
Miniaturisation
• Which is safer & why?
10 /yr 10 /yr 10 /yr 10 /yr
100 /yr
10 /yr 10 /yr 10 /yr
10 /yr 10 /yr 10 /yr
Option A
Option B
Just making things smaller doesn’t make them safer if you
need more of them to do the same job. The probability of a
failure event increases proportional to the number of
systems in parallel
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
Process Intensification vs. Process
Miniaturisation
• Which has lowest environmental impact & why?
10 /yr 10 /yr 10 /yr 10 /yr
100 /yr
10 /yr 10 /yr 10 /yr
10 /yr 10 /yr 10 /yr
Option A
Option B
It is easier to monitor and control emissions from a single
point source than from many distributed sources. It is also
easier to deploy “end-of-pipe” treatment processes
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design
RECAP
1) General outlook on the product, regionally and
worldwide (uses, current supply, demand, price,
competitors, customer, raw materials etc)
2) Site location (consider all the factors mentioned) –
compare 3 alternatives
3) Site layout
4) Financial analysis
Chemical Engineering Design
Questions ?
© 2012 G.P. Towler / UOP. For educational use in conjunction with
Towler & Sinnott Chemical Engineering Design only. Do not copy
Chemical Engineering Design