United States Office at Air Quality EPA 453/R-92-018
Environmental Protection Planning and Standards December 1992
Agency Research Triangle Park NC 27711
dEPA Control Techniques
for Volatile
Organic Compound
Emissions from
Stationary Sources
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EPA 453/R-92-018
Control Techniques for
Volatile Organic Compound
Emissions from
Stationary Sources
Emission Standards Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
December 1992
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This report has been reviewed by the Emission Standards
Division of the Office of Air Quality Planning and
Standards, EPA, and approved for publication. Mention
of trade names or commercial products is not intended
to constitute endorsement or recommendation for use.
Copies of this report are available - as supplies
permit - through the Library Services Office (MD-35),
U.S. Environmental Protection Agency, Research Triangle
Park NC 27711, (919) 541-2777, or from National
Technical Information Services, 5285 Port Royal Road,
Springfield VA 22161, (703) 487-4650.
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TABLE OF CONTENTS
TITLE PAGE
1. SUMMARY
1.1 Introduction and Purpose 1-1
1.2 Emission Sources and Levels 1-3
1.3 Control Techniques 1-4
1.4 Regulatory Status 1-11
2. CHARACTERISTICS OF VOC
2.1 Definitions 2-1
2.2 Photochemical Reactions 2-3
2.3 Sampling Methods 2-4
2.4 Current Emission Level Estimates 2-5
2.5 Air Quality and Emission Trends 2-12
2.6 References 2-12
3. CONTROL TECHNOLOGIES AND EQUIPMENT
3.1 Capture 3-1
3.2 Combustion 3-7
3.2.1 Thermal Incinerators 3-7
3.2.2 Catalytic Incinerators 3-13
3.2.3 Industrial Boilers and Process Heaters 3-18
3.2.4 Flares 3-22
3.3 Adsorption 3-28
3.4 Absorption 3-52
3.5 Condensation 3-63
3.6 Other Control Methods 3-75
3.7 References 3-78
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TABLE OF CONTENTS (CON'T)
TITLE PAGE
4. CONTROL TECHNIQUES APPLICABLE TO SOURCE CATEGORIES 4-1
4.1 Petroleum Refineries 4-2
4.1.1 Equipment Leaks 4-2
4.1.2 Vacuum Producing Systems 4-6
4.1.3 Process Unit Turnarounds 4-8
4.1.4 Cooling Towers 4-10
4.1.5 Wastewater Systems 4-13
4.2 Petroleum Products - Storage, Transportation,
and Marketing 4-17
4.2.1 Oil and Gas Production Fields 4-17
4.2.2 Natural Gas and Natural Gasoline
Processing Plants 4-21
4.2.3 Petroleum Liquid Storage Tanks 4-25
4.2.4 Ship and Barge Transfer of
Gasoline and Crude Oil 4-33
4.2.5 Bulk Gasoline Terminals 4-36
4.2.6 Gasoline Bulk Plants 4-38
4.2.7 Service Station Storage Tanks 4-41
4.2.8 Vehicle Refueling at Service Stations 4-43
4.2.9 Vessel Cleaning 4-46
4.3 Organic Chemical Manufacture 4-49
4.3.1 Process Vents 4-50
4.3.1.1 Reactor Processes 4-50
4.3.1.2 Air Oxidation 4-53
4.3.1.3 Distillation Operations 4-57
4.3.2 Volatile Organic Liquid Storajge Tanks 4-59
4.3.3 Equipment Leaks 4-65
4.3.4 Transfer 4-69
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TABLE OF CONTENTS (CON'T)
TITLE
4.4 Industrial Manufacturing Processes
4.4.1 Paint and Varnish
4.4.2 Vegetable Oil Processing
4.4.3 Pharmaceutical
4.4.4 Rubber Products
4.4.4.1 Styrene - Butadiene Copolymer
4.4.4.2 Pneumatic Rubber Tire
4.4.5 Polymers and Resins
4.4.5.1 Polyethylene, Polypropylene,
Polystyrene, and Polyester Resin
4.4.6 Synthetic Fibers
4.4.7 Plywood Manufacture
4.4.8 Beer and Wine Production
4.4.9 Whiskey Warehousing
4.4.10 Other Industrial
4.5 Application of Paints, Inks, and Other Coatings
4.5.1 Surface Coating
4.5.1.1 Large Appliances
4.5.1.2 Magnet Wi re
4.5.1.3 Automobiles and Light-Duty Trucks
4.5.1.4 Cans
4.5.1.5 Metal Coils
4.5.1.6 Paper
4.5.1.6.1 Pressure Sensitive
Tapes and Labels
4.5.1.6.2 Magnetic Tapes
4.5.1.7 Fabric Coating and Printing
4.5.1.8 Metal Furniture
4.5.1.9 Wood Furniture
PAGE
4-71
4-71
4-74
4-77
4-81
4-81
4-84
4-87
4-88
4-92
4-97
4-99
4-101
4-103
4-104
4-105
4-105
4-109
4-111
4-116
4-119
4-122
4-125
4-128
4-131
4-136
4-140
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TABLE OF CONTENTS (CON'T)
TITLE PAGE
4.5.1 Surface Coating (Cont')
4.5.1.10 Flat Wood Paneling 4-143
4.5.1.11 Other Metal Products 4-146
4.5.1.12 Larye A1rcraft 4-150
4.5.1.13 Ships and Recreational Boats 4-154
4.5.1.14 Plastic Parts for Business
Machines 4-159
4.5.1.15 Flexible Vinyl and Urethane 4-152
4.5.1.16 Architectural Coatings 4-165
4.5.1.17 Auto Refinishing 4-167
4.5.1.18 Other Surface Coating 4-170
4.5.2 Graphic Arts 4-171
4.5.2.1 Rotogravure 4-171
4.5.2.2 Flexography 4-173
4.5.2.3 Lithography 4-174
4.5.2.4 Letterpress 4-176
4.5.2.5- Flexible Packaging 4-178
4.5.3 Adhesives 4-182
4.6 Other Solvent Use 4-185
4.6.1 Solvent Metal Cleaning 4-185
4.6.2 Petroleum Dry Cleaning 4-189
4.6.3 Cutback Asphalt 4-192
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TABLE OF CONTENTS (CON'T)
TITLE PAGE
4.7 Other Miscellaneous Sources 4-194
4.7.1 Stationary Fuel Combustion 4-194
4.7.1.1 External 4-194
4.7.1.2 Internal 4-199
4.7.2 Forest, Agricultural, and Other
Open Burning 4-202
4.7.3 Hazardous Waste Treatment, Storage,
and Disposal Facilities (TSDF) . 4-206
4.7.4 Publicly Owned Treatment Works (POTW's) 4-209
APPENDIX A Emission Estimates A-l
APPENDIX B Cost Indexes B-l
APPENDIX C Additional Information on Control
Technologies C-l
APPENDIX D Listing of Air Emission Control
Standards and Documents D-l
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PREFACE
This is the third edition of a report originally published
by the Department of Health, Education, and Welfare (HEW) titled,
"Control Techniques for Hydrocarbon and Organic Solvent Emissions
from Stationary Sources (AP-68)." The first edition was
published in March 1970 by the National Air Pollution Control
Administration, a part of HEW. The second edition, was published
by the U. S. Environmental Protection Agency in May 1978. It
contained numerous changes from the original and was retitled
"Control Techniques for Volatile organic Emissions from
Stationary Sources" (EPA-450/2-78-022) to better express the
EPA's concern with pollutants other than hydrocarbons. This
third edition incorporates the knowledge gained by the Agency
during the years subsequent to 1978 and condenses it for easy
reference.
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1.0 SUMMARY
This document is a summary document containing general
information on sources of volatile organic compound (VOC)
emissions, applicable control techniques, and the impacts
resulting from control applications. It references other
documents which contain much more detailed information on
individual sources and control techniques.
1.1 INTRODUCTION AND PURPOSE
In March 1970, the U. S. Department of Health, Education and
Welfare published Control Techniques for Hydrocarbon and Organic
Solvent Emissions from Stationary Sources (AP-68) as one of a
series of documents summarizing control techniques information
for criteria air pollutants. Section 108(b) of the Clean Air Act
(CAA) as amended in 1977 instructs the Administrator to review
and modify these control techniques documents from time to time
as appropriate:
". . . the Administrator shall, after consultation with
appropriate advisory committees and Federal departments
and agencies, issue to the States and appropriate air
pollution control agencies information on air pollution
control techniques, which information shall include
data relating to the cost of installation and
operation, energy requirements, emission reduction
benefits, and environmental impact of the emission
control technology. Such information shall include
such data as are available on available technology and
alternative methods of prevention and control of air
pollution. Such information shall also include data on
alternative fuels, processes, and operating methods
which will result in elimination or significant
reduction of emissions."
Additionally, Section 183(c) of the CAA as amended in 1990,
provided:
. . the administrator shall issue technical
documents which identify alternative controls for all
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categories of stationary sources of volatile organic
compounds and oxides of nitrogen which emit, or have
the potential to emit 25 tons per year or more of such
air pollutant."
This third edition, incorporates new information on VOC emissions
and technologies gathered during the development of national air
emission standards under Section 111 and 112 of the CAA, during
the preparation of control, technique guidelines, alternative
control technology documents, and other technical studies to aid
States in developing VOC regulations, and during the review and
comment period on the draft of this document by Federal and State
agencies, industry and other public groups and individuals, and
the National Air Pollution Control Technical Advisory Committee.
The CAA included this document primarily as a general
reference for State and local air pollution control engineers.
Based on the interest shown in this and previous editions by the
industrial community, it will serve a much broader clientele.
Because of the general nature of the document, it should not be
used as the basis for developing regulations or enforcing them
although it can be helpful as a basic reference from which to
begin such an effort. It can be used to provide:
1) summary information and reference material on
sources of oxidant precursors and control of these
• sources,
2) estimates of control costs, and
3) estimates of emission reductions achievable through
control.
The costs presented in the text are the averages for a variety of
differing industrial applications and consequently can be
considered only rough estimates for any specific application.
Actual costs for a particular installation may differ
substantially from the average costs presented.
VOC is of concern because it contributes to lower
atmospheric ozone formation, which in turn causes health and
welfare effects. An estimate of nationwide VOC emissions is
presented in Chapter 2.0, as is a brief discussion of the
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mechanism by which photochemical oxidants (ozone) are formed in
the lower atmosphere. The health effects associated with
volatile organic and their secondary atmospheric reaction
products are discussed in an EPA report Air Quality Criteria for
Ozone and Other Photochemical Oxidants.
The techniques for control of VOC described in this report
represent a broad spectrum of information from many technical
fields. The devices, methods, and principles have been developed
and used over many years and are constantly being revised and
improved. These techniques vary in type, application,
effectiveness, and cost. The "best technique" is to design and
operate process equipment for maximum product yield, i.e.,
complete and efficient use of the raw materials being processed.
Failing this, control equipment can be used to recover or destroy
materials that otherwise would escape as air pollution.
Operating principles, design characteristics, disadvantages,
applications, costs, and energy considerations for a variety of
air pollution control equipment and other control techniques are
described in Chapter 3.0.
Chapter 4.0 provides a more focused view of a number of
industrial processes and source categories. Emission
characteristics for each.process are described. The control
techniques that can be applied to reduce VOC from each process
are reviewed. The proper choice of a method of controlling VOC
emissions from a specific source depends on many factors,
including the source characteristics. No attempt is made here to
review all possible combinations of control techniques that may
be used to reduce a certain emission.
As the title indicates, this report presents information on
VOC control only for stationary sources. Information on control
of emissions of VOC from mobile sources is available from the
EPA's Office of Mobile Sources in Washington, D.C.
1.2 EMISSION SOURCES AND LEVELS
For purposes of this document, a volatile organic compound
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(VOC) is any organic compound that participates in atmospheric
photochemical reactions to form ozone. Nearly all organic react
photochemically in the atmosphere to produce ozone and other
oxidants, furthermore, as increasingly more information becomes
available, we find many VOC*s are individually toxic. Oxidants
have long been associated with a variety of adverse health and
welfare effects and were designated a criteria pollutant in 1971.
Some organics are hazardous pollutants and may also be VOC (e.g.,
vinyl chloride and benzene) or be in the same emission stream as
VOC. Therefore, controlling VOC often indirectly reduces
hazardous pollutants. Therefore, volatile organic emissions are
an important concern in the Agency's quest to protect the public
health.
Figure 1-1 presents estimates of nationwide emissions of VOC
for each general industrial (or source group) categ&ry for 1985.
Notice that about two-thirds of volatile organic emissions from
all sources are from stationary source. These estimates take
into account Federal, State and local air pollution regulations.
Also, it should be noted that the percentages shown in the bar
graph are a function of how the sources are grouped together. A
breakdown of each grouping is shown on Table 2-5 of Chapter 2.
1.3 CONTROL TECHNIQUES
The two methods commonly employed to reduce emissions of
VOC's to the atmosphere are:
1. Installation of so called "add-on" control equipment to
recover or destroy off-gas pollutants. Equipment to capture the
emissions is often required in conjunction with add-on devices
themselves.
2. Changes in a process and/or raw material to eliminate or
reduce generation of pollutants by the process.
1.3.1 Add-On Control Equipment
There are five widely used add-on control techniques for
limiting emissions of VOC. These five are: combustion,
adsorption, absorption, and condensation.
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Figure 1-1. SOURCES OF VOC EMISSIONS AND
1985 NATIONAL VOC AIR EMISSION ESTIMATES
(Total = ~ 24,300 Gg/yr OR ~ 26,800,000 Tons/yr)
Mobile Sources -
Misc. Sovent Uses
Hazardous Waste TSDF -
Surface Coating -p
Petroleum Marketing
Petroleum Refining -
Chemical Manufacturing -
Industrial Processes -
Miscellaneous Sources -
7,200
(30%)
3,600 (15%)
3,500 (14%)
3,160 (13%)
2,230 (9%)
740 (3%)
500 (2%)
365 (2%)
3,020 (12%)
0 2,000 4,000 6,000 8,000 10,000
VOC EMISSIONS, Gigagrams/Year
(% of Total Emissions)
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Tables 1-1 and 1-2 present a listing of these "add-on"
control techniques including control levels achievable with some
of these techniques, and critical design conditions. In the case
of flares, boilers and thermal incinerators, emission testing on
a variety of VOC streams has shovn that if you meet the design
conditions presented in the table, the VOC stream will be reduced
by at least 98 percent. Adsorption equipment have been shown to
achieve at least 95 percent removal efficiency, but the
efficiency is dependent on the basic design parameters listed.
As with adsorption equipment, catalytic incinerators, absorbers
and condensers VOC control efficiencies are more dependent on the
VOC streams characteristics. Thus for these techniques the
equipment must be designed for each application.
Below is a general discussion of the operation principals
for add-on equipment. A detailed discussion of each technology
is presented in Chapter 3.
Combustion. Essentially all VOC will burn; hence combustion
is the technique most universally applicable to reducing VOC
emissions. Gases containing organic are usually burned if they
have little recovery value or contain contaminants that make
recovery unprofitable. Combustion devices include thermal
incinerators, catalytic incinerators, boilers and process
heaters.
Incinerators destroy pollutants through thermal or catalytic
oxidation and control efficiencies should be at least 98 percent.
Pollutant streams not capable of sustaining combustion may
require additional fuel. Fuel costs can be at least partially
offset by employing various methods of heat recovery. In
addition, some pollutant streams can be directly vented into a
process boiler's flame, thus reducing energy costs for the boiler
and alleviating the need (or cost) of an add-on control device.
Incineration has been successfully applied to aluminum chip
dryers, petroleum processing and marketing operations, animal
blood dryers, automotive brakeshoe debonding ovens, citrus pulp
dryers, coffee roasters, wire enameling ovens, foundry core
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Table 1-1. CONTROL TECHNOLOGIES THAT FORM
THE BASIS OF STANDARDS
Control Levels Design Conditions to
Tvr>e Achievable Meet Control Level
Flares > 98%
Boilers > 98%
° Flame present at all
times - monitor pilot.
0 Non-assisted Flares
>200 Btu/scf heating
value, and 60 ft/sec
mas. exit velocity.
0 Air and Steam Assisted
Flares - >300 Btu/scf
heating value, and max.
exit velocity based on
Btu content formula.
0 Vent stream directly
into flame.
0 Destroy rather than
recovers organic.
° Smoking allowed for
5 min/2 hr.
0 Not used on
corrosive streams.
° Destroys rather
than recovers
organic.
Thermal
Incinerators
> 98%, or
20 ppm
1600°F Combustion
temperature
0.75 sec. residence
For halogenated
streams 2000°F,
1.0 sec. and use a
scrubber on outlet.
Proper mixing
° Destroys rather
than recovers
organic.
° May need vapor
holder on inter-
mittent streams.
Adsorption
* 95%
° Adequate quantity and
appropriate quality
of carbon.
0 Gas stream receives
appropriate conditioning
(cooling, filtering)
° Appropriate regeneration
and cooling of carbon
beds before breakthrough
occur?.
0 Most efficient on
streams with low
relative humidity.
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TABLE 1-2. OTHER CONTROL TECHNOLOGIES THAT CAN BE USED
TO MEET STANDARDS
Critical Variables That
Tvpe Affect Control Level Cpfflgentg
Catalytic 0 Dependent on compounds, 0 Destroys rather than recovers
Incinerators temp, and catalyst bed recovers organic.
size. .0 Technical limitations include
particulate or compounds that
poison catalysts.
Absorption
° Solubility of gas stream
in the absorbent.
° Good contact between
absorbent and gas stream
° Availability of absorbent.
° Disposal or recovery of
absorbent and organic.
0 Preferable on concentrated
streams.
Condensation ° Proper design of the 0 Preferable on concentrated
heat exchanger. streams.
° Proper flow and
temperature of coolant.
ovens, meat smokehouses, paint baking ovens, varnish cookers,
paper printing and impregnating installations, pharmaceutical
manufacturing plants, sewage disposal plants, chemical processing
plants, and textile finishing plants.
Flares have historically been employed as safety devices to
incinerate exhaust gases from petroleum refining and chemical
manufacturing operations to prevent them from.creating an
explosion hazard within the facility. Because of their
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simplicity and economy, flares are often used when disposing of
gas streams which do not require supplemental fuel.
Adsorption. Adsorption is the use of a solid material to
trap a gas. The material most commonly used is carbon, a highly
porous material. Adsorption occurs in two ways: (1) physical
adsorption, in which van der Waal's forces attract and hold gas
molecules to the adsorbent surface, and (2) chemical adsorption,
in which gas molecules are chemically bonded to the adsorbent.
Additionally, within the capillaries of the porous solid, surface
adsorption is supplemented by capillary condensation. The VOC
is usually recovered by stripping the organic from the carbon by
heating with steam.
Activated carbon is the most widely used adsorbent for
recovering VOC. "Carbon adsorption" is usually more economical
tha^n. combustion for the control of organic in low concentrations
where the cost of supplemental fuel can be very high. Depending
on the application, carbon adsorption efficiencies can be at
least 95 percent. In addition, this control technique offers
recovery of adsorbed organic which can be recycled to the process
or used as fuel. Recovery and reuse has gained greater favor by
industries as the price of petrochemicals has risen over the last
decade.
Adsorption systems have been used successfully in the
following industries: organic chemical processing, varnish
manufacture, synthetic rubber manufacture, production of selected
rubber products, pharmaceutical processing, graphic arts
operations, food production, dry cleaning, synthetic fiber
manufacture, and some surface coating operations.
Absorption. Absorption is the use of a liquid media to trap
a gas. Absorption may be purely physical (organics simply
dissolve in the absorbent) or chemical (organics react with the
absorbent or with reagents dissolved in the absorbent). The
generally low organic concentration of exhaust gases require long
contact times and large quantities of absorbent for adequate
emissions control rendering it a fairly expensive control
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technique. Therefore, absorption is less desirable than
adsorption or incineration, unless there is something unique
offered by a process such as the absorbent is easily regenerated
or can be used as a process make-up stream.
Absorption has been used to control organic vapors and
particulates in waste handling and treatment plants, degreasing
operations, asphalt batch plants, ceramic tile manufacturing
plants, coffee roasters, chromium plating units, petroleum coker
units, fish meal systems, chemical plants, and varnish and resin
cookers.
Condensation. Condensation is the physical change from the
vapor to liquid phase. Condensers operate in either of two ways:
(1) the most common is a constant pressure system where the
temperature of the gas stream is reduced to cause the desired
condensable materials to liquify, or (2) less common is the .
technique of increasing the pressure of a gas stream to cause the
combustible material to liquify. Condensation is also commonly
applied to a gas stream to reduce VOC concentrations before the
stream is routed to the other "add-on" devices spoken of earlier.
Condensers have been used successfully in bulk gasoline
terminals, petroleum refining, petrochemical manufacturing, dry
cleaning, degreasing, and tar dripping.
1.3.2 Process and/or Raw Material Changes.
In many manufacturing or processing operations, it may be
possible to lower emission levels by changing the process or raw
materials. For example, organic emissions from surface coating
operations can be significantly reduced by using lower solvent
coatings such as water-borne, higher solids, or powder coatings.
Other examples of process and material changes improve the
efficiency of the operation by increasing the yield on raw
materials thereby eliminating the need for add-on control
equipment. Typically, process or raw material changes require
considerable research and testing of product quality, therefore
these changes generally take several years to adopt. Twenty
years ago, air pollution agencies attempted to reduce ambient
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ozone levels by encouraging industry to substitute organic
compounds they believed inert to the atmospheric chemical
reactions that form ozone for the more photochemically reactive
compounds previously used. Subsequently investigation has
revealed this to be nearly futile since essentially all organics
participate in photochemical reactions, although some are slower
than others. Of those that do not react, many are inherently
toxic and some have been implicated in the undesirable
destruction of the stratospheric ozone layer.
1.4 REGULATORY STATUS
EPA has four ongoing control programs for reducing VOC
emissions from existing and new stationary sources:
(1) New source performance standards (NSPS),
(2) National emission standards for hazardous pollutants
(NESHAP),'
(3) Resource Conservation and Recovery Act (RCRA) air
standards, and
(4) Publication of control technique guidelines (CTG).
The NSPS and NESHAP programs are authorized by Congress in
the Clean Air Act as amended in 1977 and 1990 and codified in
Section 111 and 112, respectively. The NSPS program focuses on
new (rather than existing) sources of pollution to guard against
new air pollution problems and provide results in long-term
improvements in air quality as existing plants are replaced,
modified or reconstructed to make an existing source subject to a
NSPS. Congress authorized the Administrator to propose NSPS
regulations for any category of stationary sources that "causes,
or contributes significantly to, air pollution which may
reasonably be anticipated to endanger public health or welfare."
NSPS are based on the best demonstrated control technology (BDT).
In the language of Section 111, the standards of performance for
1 Reducing specific organic compounds which are listed as
hazardous often reduces VOC emissions.
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each affected facility Nshall reflect the degree of emission
limitation and the percentage reduction achievable through
application of the best technological systems of continuous
emission reduction which (taking into consideration the cost of
achieving such emission reduction, any non-air quality health and
environmental impact and energy requirements) the Administrator
determines has been adequately demonstrated." Provided in
Appendix D is a listing of the NSPS standards which have been
promulgated, proposed, or are under development, and also
provided are the appropriate dates, Federal Register cites and
background information documents (BID'S) for the standards. The
BID documents provide a detailed description of the industry's
emission sources, control techniques, control costs, and economic
impact, and anticipated VOC emission reductions. The Act
requires that NSPS standards be reviewed every 4 years to
incorporate advancements in control technology.
Hazardous air pollutants (HAP) are regulated under Section
112. Standards developed prior to the passage of the 1990 CAA
amendments defined a "hazardous air pollutant" as one which, in
the judgment of the Administrator, "causes or contributes to air
pollution which may reasonably be anticipated to result in an
increase in mortality or an increase in serious irreversible, or
incapacitating reversible, illness." The intent of those NESHAP
standards is to protect the public health with an ample margin of
safety. Some organic compounds which were listed as hazardous
may also be VOC (e.g., vinyl chloride and benzene) or be in the
same emission streams as VOC. The CAA amendments of 1990,
defined "hazardous air pollutants" as any air pollutant listed in
the CAA, and provided a list of them in Section 112(b). The 1990
CAA provisions on NESHAP standards are required to ".require the
maximum degree of reduction in emissions of "HAP" (so called,
maximum achievable control technology standards — MACT
standards). As an alternative standard, the smaller area sources
may be required to install generally available control
technologies (GACT). In terms of VOC, standards developed under
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Section 112 often indirectly reduce VOC as well as hazardous
pollutant emissions. Appendix D provides a list of the NESHAP
standards which have been proposed, promulgated, withdrawn, or
are under development, and cites the appropriate BID'S.
EPA is currently evaluating air emissions of VOC,
particulates, and specific toxic substances from hazardous waste
treatment, storage, and disposal facilities (TSDF) under the
authority of Section 3004 of the Resource Conservation and
Recovery Act and Sections 111 and 112 of the Clean Air Act. Like
the NESHAP standards, controlling air emissions of hazardous
wastes indirectly controls VOC emissions. Appendix D provides a
list of the RCRA air emission standards that have been proposed
and promulgated, and their BIDs.
The CAA requires each State in which the national ambient
air quality standards (NAAQS) are exceeded to adopt and submit
revised State Implementation Plans (SIP's) to EPA. Sections
172(a)(2) and (b)(3) of the Clean Air Act require that such
"nonattainment" area SIP's require installation of reasonably
available control technology (RACT) for select stationary
sources. RACT defines the lowest emission limitation that a
particular source is capable of meeting by the application of
control technology that is reasonably available, considering
technological and economic feasibility. The EPA required that
States adopt RACT regulations for each specific category of
stationary sources of VOC only after EPA has published guidance
on control technology via a control techniques guideline (CTG)
for that source category. Although CTG documents provide
available information and.data concerning the technology and cost
of various control techniques, they are general in nature and are
not able to fully account for variations within a stationary
source category. The CTG's provide State and local air pollution
control agencies with an initial information base (industry
description, emission sources, control technology, emission
reduction, control costs, and cost effectiveness) for proceeding
with their own assessment of RACT for specific stationary
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sources. Appendix D provides a listing of the CTG's published
and under development.
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2.0 CHARACTERISTICS OF VOLATILE ORGANIC EMISSIONS
2.1 DEFINITIONS*
The original of this report (AP-68) was titled Control Techniques
for Hydrocarbon and Organic Solvent Emissions from Stationary Sources.
Hydrocarbons are compounds containing only the elements hydrogen and
carbon. "Organic solvents" was intended to include materials such as
diluents and thinners which could also contain oxygen, nitrogen, sulfur,
and halogens.
There are reasons for replacing "Hydrocarbon and Organic Solvents"
with "Volatile Organic Compound" (VOC) in the title. There has been some
confusion in the previous use of the term "hydrocarbons." Previously,
the term "hydrocarbons" incorrectly referred to all organic chemicals.
Many organics which are photochemical oxidant precursors are not hydro-
carbons and are not used as solvent. To correct the previous confusion
this report is titled Control Techniques for Volatile Organic Compound
Emissions from Stationary Sources. A volatile organic compound (VOC) is
defined as "any organic compound which participates in atmospheric photo-
chemical reactions; or which is measured by a reference test method"
(40 Code of Federal Regulations, Part 60.2).
Since its inception in 1970, the approach adopted by EPA to reduce
photochemical (O3) and other oxidants (0X) in the ambient air has been
based on unilateral control of one of its precursers VOC. From time to
time EPA has listed in the Federal Register certain VOC's that a State
may exempt from control by virture of it's negligibly low photochemical
•reactivity. All other organics are presumed reactive. This policy has
and continues to be open to revision as new evidence develops that might
justify reclassifying the reactivity of a specific VOC.
The EPA released its "Recommended Policy on Control of Volatile
Organic Compounds" in 1977 (July 8, 1977, 42 FR 35314). That policy
divided VOCs into three classes based on three criteria: photochemical
reactivity, role in stratospheric O3 depletion, and direct health effects.
2-1
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The first class, shown in Table 2-1, includes those VOCs which by virtue
of their negligible reactivity could be exempted from regulation. The
second class, shown in Table 2-2, includes those VOCs which have low-
photochemical reactivity and must be included in the ozone SIP inventories
but their control has lower priority than that of the more reactive
compounds. The third class, encompassing all VOCs other than those in
Tables 2-1 and 2-2 includes those VOCs the control of which h-as relatively
high priority.
Perchloroethylene (perc) was judged in 1977 to have photochemical
reactivity comparable to those in Table 2-2 but was not included there
because of its reported health effects. According to a more recent
study (1983), perc is "judged to contribute less to the ambient photo-
chemical 03/0x problem than an equal concentration of ethane"*. The EPA
has formally proposed (October 24, 1983, 48 FR 49097) to reclassify perc
with the organic compounds shown on Table 2-1, however a final decision
has not been made. In addition, EPA has now formally announced
(December 26, 1985, 50 FR 52880) the intent to add perc to the list of
hazardous air pollutants. [For the purpose of this draft report, it is
assumed that perc is not a VOC, thus its sources, emissions, and controls
will not be further discussed.]
* The current definition of VOC and list of non-VOCs are in part
51 of chapter I of title 40 of the Code of Federal Regulations.
2-2
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TABLE 2-1. VOLATILE ORGANIC COMPOUNDS OF NEGLIGIBLE PHOTOCHEMICAL REACTIVITY
THAT SHOULD BE EXEMPT FROM REGULATION UNDER STATE IMPLEMENTATION
PLANS (JULY 8, 1977, 42 FR 35314)
Methane
Ethane
1,1,1-Trichloroethane (Methyl Chloroform)3
Trichlorotrifluoroethane (Freon 113)a
Methylene Chloride3
Trichlorofluoromethane (Freon ll)a
Dichlorodifluoromethane (Freon 12)a
Chlorodifluoromethane (Freon 22)a
Tri fluoromethane3
Chioropentafluoroethane (Freon 115)a
Dichlorotetrafluoroethane (Freon 114)a
d According to more recent EPA notices in the Federal Register (44 FR 32042,
June 4, 1979, and 45 FR 48941, July 22, 1980), these compounds are of
continuing.concern to EPA over possible environmental effects and may be
subject to future controls.*
TABLE 2-2. VOLATILE ORGANIC COMPOUNDS OF "LOW" PHOTOCHEMICAL REACTIVITY*
(July 8, 1977, 42 FR 35314)
Propane
Acetone
Methyl Ethyl Ketone
Methanol
Isopropanol
Methyl Benzoate
Tertiary Alkyl Alcohols
Methyl Acetate
Phenyl Acetate
Ethyl Amines
Acetylene
N,N-dimethyl formamide
* The current definition of VOC and list of non-VOCs are in part
51 of chapter I of title 40 of the Code of Federal
2-3
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2.2 PHOTOCHEMICAL REACTIONS
Much research has been conducted concerning the causes and effects of
photochemical smog. Investigations have revealed a complex series of chemical
reactions take place in the atmosphere which result in high levels of photo-
chemical oxidant (mostly NO2 and ozone with smaller concentrations of
peroxyacetyl nitrates and other peroxy compounds). These compounds produce
haze, damage plant and animal life, and materials such as rubber, induce
discomfort and are suspected to have toxic effects on man. Although
specific volatile organics are inherently toxic, this text is devoted to
a discussion of generic organic emissions, whose collective effect is
most significant in their role as a precursor of photochemical oxidants.
A very simple, mec-hanistic description of the photochemical formation
of ozone is shown in Equations 1 through 4.
Sunlight
N02 —> NO + 0 (1)
0 + O2 M O3 + M (2)
O3 + NO —> NO2 + O2 (3)
R0X + NO —> N02 + ROy (4)
In these chemical equations M is a third body (usually N2, O2, or H2O)
stabilizing the molecule; R is an organic or inorganic radical; x = 1, 2,
or 3; and y = x-1.
Reactions 1 through 3 are very rapid and their rates are nearly equal.
At steady state conditions, ozone and NO are formed and destroyed in equal
quantities. An equilibrium equation can be written relating the concentrations
of O3, NO, and N02:
[03] = k Eno23 (5)
[NO]
This equation shows that any reaction which causes NO to be converted to
N02 (Equation 4) will cause high N02 levels and high O3 levels.
Hydroxyl and peroxy radicals are important atmospheric reactants
which convert NO to NO2. Hydroxyl radicals may react with CO or an
organic compound to result i«- peroxy radicals which, by reacting with NO,
2-4
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cause high levels of NO2 and O3. Additionally, some organic compounds
(notably aldehydes) can photolize in the atmosphere to form radicals which
participate in atmospheric reactions. Some of the organic radicals formed
may react with N0X to form nitrogenated organic pollutants, such as PAN.
The presence of highly reactive organic radicals can result in high
oxidant levels within a few hours. These materials may be carried downwind
great distances, thereby increasing ozone levels downwind from the pollutant
source at a later time.
Volatile organics or oxidant precursors are emitted to the atmosphere
from both natural and man-made sources. Globally, natural emissions,
appear to outweigh anthropogenic emissions. However, it is the high
concentration of anthropogenic sources of volatile organics together with
N0X emissions from combustion processes in urban areas which give rise to
the urban ozone problem. Wind and other climatalogical activities
(transport mechanisms) may carry the ensuring oxidant formed into rural
areas.
It is conceivable that natural phenomena may contribute to high
oxidant levels. It has been suggested that terpenes emitted from heavily
forested areas might act as precursors and react with naturally occuring
N0X to form ozone. It has also been postulated that intrusions of
stratospheric ozone into the atmosphere might contribute to oxidant
levels.
2.3 SAMPLING AND ANALYTICAL METHODS
The rationale for selection of specific sampling and analysis methods
for the measurement of volatile organic emissions from stationary sources
is addressed in two documents in the Guideline Series: "Measurement of
Volatile Organic Compounds" (EPA-450/2-78-041, September 1979), and
"Measurement of Volatile Organic Compounds - Supplement 1" (EPA-450/3-82-019,
July 1982).
In considering test methods for VOC's, one must recognize that organic
emissions normally occur as a mixture of (rather than a single) compounds.
There is no simple quantitative method for a mixture. Several detection
2-5
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techniques respond to organic compounds; however, the response can vary
widely depending on the compound and will therefore, not likely be proportional
to the total organic mass (or volume) of the mixture.
The principle concern when selecting a measurement method, is that
it satisfies the intent of the appropriate emission standard by both using
the correct sampling and analysis procedures, and expressing the results
in a form consistent with the regulation. In some cases, the regulations
are expressed in terms of the volatile organic content of a coating. In
others, they restrict organic volume or mass concentrations, mass emission
rates, or efficiency of the control device.
Table 2-3 lists the reference methods currently employed by EPA to
measure VOC. Still other methods may be required to locate sampling
points, standardize the measurements, and determine .gas flowrates. Those
methods are listed 1n Table 2-4.
2.4 CURRENT EMISSION LEVEL ESTIMATES
A list of VOC emission estimates by industry source category is
presented in Table 2-5. These estimates by the EPA are based on data from
a number of sources. The emission figures represent the nationwide
combination of facilities (sources), both uncontrolled and controlled,
and are based on local, State and Federal requirements on typical processes
for each source category. These national emission estimates should be
considered rough estimate largely because many estimates are ratioed up
from "typical" plants, are dependent on how much EPA has studied a particular
source and most estimates assume that required control equipment is properly
inspected, operated and maintained. More specific information on their
use and origin can be found in Chapter 4, where each source is discussed
separately.
Mobile source emission estimates are also presented in Table 2-5 to
present a comparison of stationary and mobile sources. As can be derived
from the table, about two-thirds of VOC emissions is from stationary
sources.
2-6
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TABLE 2-3. THE ENVIRONMENTAL PROTECTION AGENCY REFERENCE
METHODS FOR MEASUREMENT OF VOLATILE ORGANIC COMPOUNDS
Type of Measurement
Test Method
(40 CFR Part 60, Appendix A)
1.
Tank truck leaks, pressure and
vacuum test.
Method 27
2.
Fugitive emissions (leaks), ppmv
as calibrated (reference
compound in specified
regul ati on).
Method 21
3.
Solvent in surface coatings,
weight of volatile organic
compound per volume of solids.
Method 24
4.
Solvent in ink, weight of
volatile organic compound per
volume of sol ids.
Method 24A
5.
Total gaseous nonmethane
organics, ppmv as carbon.
Method 25
6.
Total organic carbon/flame
ionization analyzer, ppmv as
carbon.
Method 25A
7.
Total organic
carbon/nondispersive infra-red
analyzer, ppmv as carbon.
Method 25B
8.
Total nonmethane volatile
organics/gas chromatography, ppmv
as individual compounds.
Method 18
2-7
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TABLE 2-4. THE ENVIRONMENTAL PROTECTION AGENCY REFERENCE
METHODS TO DETERMINE THE FLOW OF A GAS
Type of Measurement
lest Method
(40 CFR Part 60, Appendix A)
.1.
Sample and velocity traverse
1ocations.
Method I
2.
Sample and velocity traverse
locations - small stacks and
ducts.
Method 1A
3.
Stack gas velocity and flow rate,
type S pitot tube.
Method 2
4.
Gas flow rate, volume meter.
Method 2A
5.
Gas flow rate, carbon balance.
Method 2B
6.
Stack gas velocity and flow rate,
standard pitot tube.
Method 2C
7.
Gas flow rate - small pipes and
ducts.
Method 2D
8.
Gas analysis for CO?, 03, excess
air, and dry molecular weight.
Method 3
9.
Gas moisture content.
Method 4
2-8
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TABLE 2-5. SOURCES OF VOLATILE ORGANIC COMPOUNDS
1985
Source Estimated Emissions3
Gg/yr 10^ Tons/yr
PETROLEUM REFINERIES
Equipment Leaks 370 409
Vacuum Producing Systems 44 49
Process Unit Turnaround 270 29b
Cooling Towers 3 3
Wastewater Systems 55 60
740 820
PETROLEUM MARKETING
Oil and Gas Production Fields 226 250
Natural Gas and Natural Gasoline
Processing Plants 76 84
Petroleum Liquid Storage15 668 736
Ship and Barge Transfer of
Gasoline and Crude Oil 71 78
Bulk Gasoline Terminals0 172 190
Gasoline Bulk Plantsd 180 -200
Service Station Loading (Stage I) 256 280
Service Station Unloading (Stage II) 569 627
Vessel Cleaning 10 11
2,23(5 TW
ORGANIC CHEMICAL MANUFACTURE
Process Vents 306 337
Storage and Transfer 45 50
Equipment Leaks 148 163
"5(50" "550
INDUSTRIAL MANUFACTURING PROCESSES
Paint and Varnish 12 13
Vegetable Oil 65 71
Pharmaceutical 50 55
Styrene-Butadiene Copolymer NAf NA
Rubber Tire 40 44
Polymers and Resins 86 95
Synthetic Fibers 70 77
Plywood 2 2
Beer and Wine 2 2
Whiskey Warehousing 38 42
355" ~50o
2-9
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TABLE 2-5. SOURCES OF VOLATILE ORGANIC COMPOUNDS (continued)
tSS3S3S3S3S3ll3SSSa33SS33SSSS33S3SS3S3SS3SSSS33SSSSSS3SS3S3 3 3S:
1985
Source Estimated Emissions3
Gg/yr 103 Tons/yr
APPLICATION OF PAINTS, INKS, AND OTHER COATINGS
- SURFACE COATING
Large Appliances
24
26
Magnet Wire
7
8
Automobiles and Light-Duty Trucks
64
70
Cans
68
75-
Metal Coils
33
36
Paper, Film and Foil
175
193
Tapes and Labels
450
496
Magnetic Tape
8
9
Fabric Coating and Printing
70
77
Metal Furniture
95
105
Wood Furniture
200
220
F1at Wood Paneli ng
24
26
Other Metal Products
330
364
Large Aircraft
2
2
Large Ships and Boats
18
20
Plastic Parts (Business Machines)
5
6
Flexible Vinyl and Urethane
23
25
Architectural Coatings
360
397
Auto Refinishing
200
220
Others - Surface Coating
236
260
GRAPHIC ARTS
467
514
ADHESIVES
305
336
3,16U
3,490
OTHER SOLVENT USE
Metal Cleaning 920 1,010
Petroleum Dry Cleaning 83 91
Cutback Asphalt Paving 19b 214
Other Solvent Use9 2,400 2,645
3,600 3,560
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TABLE 2-5. SOURCES OF VOLATILE ORGANIC COMPOUNDS (continued)
33SSS3SSS3SaiSSISISS3SSSSSS333S3SSSS3SSSSS333SSS3SS3S33SS3SSSSSS3SSS3S3S5S33S33SSS
1985
Source Estimated Emissions3
Gg/yr 103 Tons/yr
OTHER MISCELLANEOUS STATIONARY SOURCES
Fuel Combustion 2,100 2,300
Forest, Agricultural, and Other
Open Burning 900 (990
Hazardous Waste Treatment, Storage,
and Disposal Facilities 3,500 3,860
Publicly Owned Treatment Works (POTW's) 21 23
6,5W 7,190
TOTAL VOLATILE ORGANIC EMISSIONS
FROM STATIONARY SOURCES 17,100 18,870
MOBILE S0URCESe .
Highway Vehicles 6,000 6,600
Off-Highway Vehicles 400 440
Rail 200 220
Aircraft 200 220
Vessels 400 440
TOTAL VOLATILE ORGANIC EMISSION
FROM MOBILE SOURCES 7,200 7,920
TOTAL VOLATILE ORGANIC EMISSIONS 24,300 26,800
a 1985 EPA Estimates, due to data limitations all emission calculations may
not be based on 1985 data. See Chapter 4 of this document for more information.
b Petroleum Liquid Storage - includes all storage facilities except those
at service stations and bulk plants.
c Bulk Terminals - emissions from loading tank trucks.
d Bulk Plants - emissions from storage and transfer.
e Estimates from "National Air Pollutant Emission Estimates (1940 - 1983),
U.S. Environmental Protection Agency, Research Triangle Park, North Carolina,
EPA 450/4-84-028, December 1984.
f Not available.
9 Estimates from End Use of Solvents Containing VOC, U.S. EPA,
EPA-450/379-032, May 1979.
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2.5 AIR QUALITY AND EMISSION TRENDS
EPA annually publishes a report on air quality and emission trends.2
Improvements are reported for long-term (1975 through 1983) ozone levels.
In summary, the report shows an 8 percent decrease in the average of the
second-highest daily maximum 1-hour ambient ozone levels. VOC emissions
were also reported to have decreased by 12 percent during the same time
peri od.
2.6 REFERENCES
1. Dimitriades, B.; Gay, B.; Arnts, R.; and Selia, R. "Photochemical Reactiv
of Perchloroethylene," U. S. Environmental Protection Agency, Environmental
Sciences Research Laboratory, Research Triangle Park, North Carolina 27711,
EPA-600/3-83-001, January 1983, pg. 46.
2. National Air Quality and Emissions Trends Report, 1983, U.S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research
Triangle Park, North Carolina, EPA-450/4-84-029, April 1985.
2-12
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3.0 CONTROL TECHNOLOGIES AND EQUIPMENT
Two methods employed commercially to control emissions of volatile
organic compounds are:
1. installation of control equipment to destroy or extract the
organic vapors from exhaust gases, and
2. changes to the process or raw materials that reduce or eliminate
vapor emissions.
There are four major types of control equipment. They are based on
combustion, adsorption, absorption, and condensation. These are discussed
in Section 3.2 through 3.5, where operating characteristics of each are
explained and the primary areas of application are indicated. Some represen-
tative estimates of capital and annualized costs are provided, along with
energy requirements and environmental impact.
3.1 CAPTURE
Any control system that reduces volatile organic compound (VOC)
emisssions from a process, has two fundamental components. The first is
the containment or capture system, which is a single device or group of
devices whose function is to collect the pollutant vapors and direct them
into a duct leading to a control device. The second component is the
control device, which reduces the quantity of the pollutant emitted to
the atmosphere.
The efficiency with which vapors from a process are collected by the
containment or capture system and delivered to the control device is
called "Capture Efficiency" (CE). It is defined as "the fraction of all
organic vapors generated by a process that is directed to an abatement or
recovery device". "Control Device Efficiency" (CDE) is defined as
"the ratio of the pollution destroyed or recovered by a control device to
the pollution introduced to the control device." The "Overall Control
3-1
-------
Efficiency" (OCE) is the product of the capture and control device
efficiencies or
OCE » CE X CDE (Equation 1)
For this reason a highly effective capture system 1s critical to achieving
high levels of VOC emission control.*
There are three types of capture systems: local ventilation, partial
enclosures, and total enclosures. Each of these are discussed below.
Local Ventilation Systems.^ Local ventilation systems are the most
common capture systems. They usually consist of one or more hoods such
as floor sweeps, slotted ducts, and even certain kinds of partial
enclosures. Capture efficiencies of these ventilatlion systems vary widely.
An efficient local ventilation capture system shou>d maximize the
collection of VOC emissions, minimize the collection of dilution air, and
maintain an adequate ventilation rate in the work place. The factors
important in designing an efficient capture system include:
1. Degree of turbulance;
2. Capture velocity; and
3. Selectivity of collection.
Although these factors are interdependent, each will be discussed separately.
Turbulence in the air around a VOC emission source is a serious
impediment to effective collection. Turbulence dilutes the solvent laden
air stream and contributes to the transport of VOC away from the capture
device. The resulting increase in of dilution air increases the size and
resultant cost of control equipment. Sources of turbulence that should
be recognized and minimized include:
1. Thermal air currents;
2. Machinery motion;
3. Material motion;
4. Operator movements;
5. Room air currents; and
6. Spot cooling and heating of equipment.
3-2
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Turbulence around hoods and exhaust vents should also be minimized.
The coefficient of entry (Ce) is a measure of the degree of turbulence
caused by the shape of the opening. A perfect hood with no turbulence
losses would have a coefficient of entry equal to 1. Table 3-1 gives
coefficients of entry for selected hood openings. Flanged or bell-mouthed
hood openings reduce the pressure drop at the entrance which reduces
turbulence, and, thereby, improves capture.
The velocity necessary to collect contaminated air and draw it into
a capture device is called the capture velocity. At capture velocity,
the inflow of air to the capture device is sufficient to overcome the
effects of turbulence and, thereby, minimize the escape of contaminated
air. Local ventilation systems require higher capture velocities than
p
total or partial enclosures and result in larger quantities of air being
ducted to the control device. Empirical testing of operating systems has
been used to develop the guidelines for capture velocity presented in
Table 3-2.
Selectivity describes the ability of the capture system to collect
pollutants at their highest concentration by minimizing the inflow of
clean air. A highly selective system will achieve a high capture efficiency
using low airflow rates. Low airflow rates and the increased VOC
concentration in the air stream result in control systems that are
relatively economical to operate.
The best method of improving selectivity is to minimize the distance
between the emission of source and the capture device. Selectivity also
can be enhanced by the use of flanges or bell-shaped openings on hoods
and exhaust points. These features cause the airflow to be pulled more
directly from the source of emissions. Less dilution air is pulled from
behind and the sides of the hood.
Partial Enclosures. A partial enclosure is any rigid or semirigid
structure other than a total enclosure, that partially surrounds or
enshrouds a manufacturing process or other source of emissions. For
example, it may be open on at least one side to provide unobstructed access
3-3
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TABLE 3-1. COEFFICIENTS OF ENTRY FOR SELECTED HOOD OPENINGS3
Hood type
Description
6^
Plain opening
0.72
Flanged opening
0.82
Bell mount inlet
0.98
TABLE 3-2. RANGE OF CAPTURE VELOCITIES3
Condition of dispersion of contaminant
Capture velocity,
m/s (fpm)
Released with little velocity into quiet air
Released at low velocity into moderately still
air
Active generation into zone of rapid air motion
Released at high initial velocity into zone of
very rapid air motion
3-4
0.25-0.51 (50-100)
0.51-1.02 (100-200)
1.02-2.54 (200-500)
2.54-10.2 (500-2,000)
-------
to the process equipment. (A total enclosure would be a partial enclosure
if operated with an open door.) Because the partial enclosure only
partially encloses the source of emissions, part of the VOC might not be
contained (for ducting through a stack or into an oven), but rather might
escape to the atmosphere as fugitive emissions. Examples are a tunnel
open at one end, a spray booth open on one side or a room with an open
doorway. The emissions may be vented through the drying oven and then to
the control device or directly to the control device.
Total Enclosures.^ The most effective emission capture system is a
total enclosure that surrounds the emission source. The only openings
are those which allow raw materials into the enclosure or that specifically
allow air into prevent a buildup of organic vapors to hazardous exposure
or explosive concentrations. A negative-pressure differential is maintained
with respect to the outside of the enclosure to ensure that no air can
escape through the limited openings.
A ventilation system can be designed so that the room containing the
source(s) of emissions functions as a total enclosure. By closing all
doors and windows, the room may be evacuated either by the draft from the
oven(s) or by hoods and exhaust ducts. The room ventilation exhaust can
be directed to the control device; it can be used as make-up air to any
ovens which are served by a control device; or, it can be split between
the two routes.
A total enclosure also may be designed as a small room surrounding
the emission source or as a "glove box" shaped to conform roughly to the
shape of the equipment. This design may preclude total emission capture
at all times, however, because of turbulence or back drafts caused by the
opening of enclosure doors during operation, if frequent worker access is
necessary. If the pressure diffential between inside and outside the
enclosure is adequate, fugitive losses would be minimal.
If frequent or continuous worker access is necessary, fresh air
could be supplied directly to operators stationed wi'thin the" enclosure.
Another approach would be to have the total enclosure equipped with local
3-5
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hoods and evacuated at a rate that maintains a safe concentration for the
worker without requiring a fresh air supply system. The amount of air
necessary to achieve this condition would be a function of the proximity
of the hood(s) to the source(s) of emissions.
The VOC emissions that are contained by the glove box enclosure, as
with the emissions from the large room, can be ducted to the oven to
serve as make-up air or directly to a control device. When the captured
emissions are used as oven make-up air, the total airflow to the control
device is lower than that for systems that duct air from the process area
to the control device through independent ductwork. In some cases, the
draft from the oven opening at the substrate entrance may be sufficient
to draw the captured emissions into the oven without the use of additional
hoods and ducts. Using ventilation air as oven make-up increases the VOC
concentration in the solvent laden air that is ductedto the control device;
thus, the potential size of the control device required to treat the solvent
laden air may be smaller.
3-6
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3.2 COMBUSTION CONTROL DEVICES
Combustion control devices include process heaters, boilers, flares,
and thermal and catalytic incinerators. Combustion is a rapid, exothermic
oxidation process which will convert VOC to water and carbon dioxide. Fuels
and VOC contain carbon and hydrogen, which when burned to completion with
oxygen, form carbon dioxide and water. Combustion control devices destroy
any organic raw material or product in the offgas. Much of the thermal
energy released by combustion in incinerators can be recovered with equipment
such as recuperative heat exchangers or waste heat boilers, if desired.
3.2.1 Thermal Incinerators
3.2.1.1 Equipment and Operating Principles
Incineration destroys volatile organics by oxidizing them to carbon
dioxide and water. Any VOC heated to a sufficiently high temperature in the
presence of oxygen will burn or oxidize. Theoretical combustion temperatures
vary depending upon the chemical structure of the VOC, incinerator residence
time, and availability of oxygen in the proximity of the VOC (mixing).
Properly designed incinerators include the following:
1. A sufficiently high design temperature for the combustion chamber
to ensure rapid and complete oxidation.
2. Adequate turbulence to obtain good mixing between combustion air,
VOC, and hot combustion products from the burner.
3. Sufficient residence time at incineration temperature for complete
combustion.
A typical thermal incinerator consists of a refractory-lined chamber
containing one or more burners. As shown in Figure 3-la, the design provides
for a thorough mixing of waste gas, combustion air, and hot combustion products
from the burner. The gas mixture then passes into a combustion chamber (5)
sized to allow complete combustion with a typical residence time of 0.3 to
1.0 second. Energy can be recovered from the hot flue gases in a heat recovery
section (6). Energy so recovered can be used to preheat subsequent combustion
air, offgas or both, to generate steam in a waste heat boiler, or for a variety
of other uses such as providing process heat elsewhere in the plant, to heat
3-7
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121
lastt Gas
Auxiliary
ru«l Burner
(disrate) -—
(1)
Air
1
!
Stack
4
(*f|
Mixinf
Secnan
(4)
Camawaon
Stcocn (5]
' Concsai
Htst
Recovery (6,
Figure 3-1.a Discrete burner, thermal incinerator.
u ' (4)
i
i
(natural {as)
Auxiliary ?*:et
Figure 3-1.b Distributed burner, thermal incinerator.
3-8
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ventilation air in wintertime, etc. If the waste gas is preheated, insurance
regulations require the VOC concentration be maintained at or below 50 percent
of the lower explosive limit (LEL) with proper instrumentation to prevent
risk of fire or explosion.
A second type of thermal incinerator uses a distributed gas burner as
shown in Figure 3-lb.^ Tiny natural gas flame jets (1) on the burner plate
(2) ignite the waste gas as it passes through the grid. The grid acts as a
baffle for mixing the gases in the chamber (3). This design provides high
efficiency and reportedly requires less fuel and a lower chamber temperature.
The use of natural gas allows a shorter combustion section than a fuel oil
fired incinerator.
Incinerator performance is affected by the heating value of the waste
gas, the inert content, the water content, and the amount of excess combustion
air. Combustion of waste gas with a heating value less t.han 1.9 MJ/scm
(50 Btu/scf) usually requires auxiliary fuel to maintain the desired combus-
tion temperature. Waste gas with a heating value above 1.9 MJ/scm (50 Btu/scf)
will burn but it may need auxiliary fuel for flame stability. Auxiliary fuel
requirements can be decreased if recuperative heat exchangers are installed
to preheat combustion air.
When a waste gas contains entrained water droplets, additional auxiliary
fuel is required to vaporize the water and raise it to the combustion chamber
temperature. If the heat value or moisture content varies, then increased
monitoring and control are required to maintain proper temperatures and
removal efficiency.
To insure sufficient oxygen is present for complete combustion, incinerators
are always operated with some excess air. The amount of excess air introduced
may vary with fuel and burner type, but is kept low to avoid wasting fuel.
Excess air increases flue gas volume and can require increases in the size and
cost of the incinerator control system. Packaged, single unit thermal inciner-
ators are available to control gas flow rates from about 0.14 scm/sec (300
scfm) to 24 scm/sec (50,000 scfm).
Thermal incinerators burning halogenated VOC typically require special
materials of construction and additional control equipment to prevent release
3-9
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of the corrosive combustion products. Flue gases are quenched to lower their
temperature and are then often routed through absorption equipment to remove
the corrosive gases. Failure to scrub the acid flue gases can result in
corrosion problems in downstream equipment and on any plant equipment on which
the stack gases impact.
VOC destruction efficiency depends upon design criteria, i.e., chamber
temperature, residence time, inlet VOC concentration, compound type, and
degree of mixing as previously discussed. An analysis of test results, along
with kinetics calculations, indicate that for a nonhalogenated VOC, 98 percent
~
destruction efficiency is achieved with a combustion temperature of 870°C
(1,600°F) and a residence time of 0.75 seconds.6
At temperatures over 760°C (1,400°F), oxidation reaction rates are much
faster than the mixing rates. The VOC destruction efficiency then become
dependent upon the fluid mechanics within the combustion chamber. High
efficiencies require rapid, thorough mixing of the VOC stream, combustion
air, and hot combustion products from the burner.
Studies of thermal incinerator efficiency indicate that new incinerators
using current technology can achieve 98 percent VOC destruction or a 20 ppmv
compound exit concentration.? For vent streams with VOC concentration below
approximately 2,000 ppmv, reaction rates decrease, maximum VOC destruction
efficiency decreases, and an incinerator outlet concentration of 20 ppmv
(volume, by compound), or lower, is achievable by all new thermal inciner-
ators.8 For vent streams with VOC concentration above approximately 2,000
ppmv, a 98 percent destruction efficiency is predicted for incinerators
operated at 870°C (1,600°F) with 0.75 seconds residence time. For halogenated
streams, 98 percent efficiency is predicted for incinerators operated at
1,100°C (2,000°F) with 1 second residence time.
Applications
Thermal Incinerators can be used to reduce emissions from almost all
volatile organic emission sources including reactor vents, distillation
vents, solvent operations, and operations performed in ovens, dryers, and
kilns. They can handle minor fluctutations in flow, however excess fluctations
require the use of a flare. Presence of elements such as halogens or sulfur
requires additional equipment such as scrubbers for acid gas removal.
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3.2.1.3 Costs
Capital costs for thermal incinerators depend upon the following factors:
(1) the fuel valve of the gas (2) the gas flowrate, (3) the fuel used, (4)
the degree of heat recovery, (5) the residence time, and (6) the presence of
contaminants. A thermal incinerator control system may consist of the following
equipment: combustion chamber, recuperative heat exchanger, waste heat boiler,
Puench/scrubber system, and auxiliary equipment such as ducts, pipe rack,
fans, and stack.
The Control Techniques Guideline Document for Air Oxidation Processes in
the Synthetic Organic Chemical Manufacturing Industry^ presents a series of
capital cost equations which include purchase costs and retrofit installation
costs for thermal incinerators, recuperative heat exchangers, ducts, fans,
and stacks and support structures for the ductwork. Equations are available
for two incineration temperatures, 870°C (1,600F) and 1,100°C (2,000°F).
Equations are available both halogenated and non-halogenated streams. For
halogenated streams, the purchase and retrofit installation costs of waste
heat boilers and flue gas scrubbers are also included. The equations used
capital costs data obtained from vendor quotations.10 Total installed capital
costs include such installation cost components as foundation, insulation,
erection, instruments, painting, electrical, fire protection, engineering,"
freight and taxes. Capital costs increase as design flowrate increases and
decrease as off-gas heating value increases.
For a process vent stream with a flowrate of 327 nm^/min (11,500 scfm)
and a heating value of 48 MJ/nnr* (1,300 Btu/scf), the installed capital cost
for the thermal incinerator is estimated at $2,300,000 in 1984 dollars.^1
The annualized cost consists of direct operating and maintenance costs,
and annualized capital charges. Direct operating and maintenance costs
consist of operating and maintenance labor, replacement parts, utilities,
fuel, and caustic. Utility requirements include electricity (for fans and
pumps), and make-up water for operation of the quench system. Natural gas is
needed to supplement the heating value of many vent streams and to maintain
the pilot flame. Caustic may be required to neutralize acidic scrubber
3-11
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water. Capital charges include annualized equipment costs, indirect costs
for overhead, taxes, insurance, administration and capital recovery.
For the process vent stream cited above, annualized costs for the incinerator
are $1,000,000 in 1984 dollars.^
3.2.1.4 Energy Requirements
The use of incineration typically requires supplemental fuel and
electricity. Supplemental fuel is frequently required to support combustion.
Electricity is required to operate pumps, fans, blowers, and instrumentation.
Fans and blowers are needed to transport vent streams and combustion air.
Pumps are necessary to circulate absorbent through scrubbers. Electricity
generally accounts for less than 2 percent of the total energy impact, while
fuel use accounts for the remainder*3
In general, supplemental fuel requirements depend on the organic content
of the process gas stream, waste stream temperature, incineration temperature,
and type of heat recovery employed. For halogenated vent streams with heat
content values of less than 3.5 MJ/nnr* (95 Btu/scf) and nonhalogenated streams
with heat content values of less than 1.9 MJ/nnr* (51 Btu/scf) the fuel require-
ment can be estimated at 0.33 MJ of natural gas heat per normal cubic meter of
offgas (89 Btu/scf). For halogenated vent streams with heat content values
of greater than 3.5 MJ/nm^ (95 Btu/scf) and nonhalogenated streams with heat
content values of greater than 1.9 MJ/nnr* (51 Btu/scf) the amount of fuel
required per normal cubic meter of offgas is equivalent to 10 percent of the
offgas heating value.14
3.2.1.5 Environmental Impacts
Destruction of volatile organics with a thermal incinerator can produce
secondary emissions, particularly nitrogen oxides (N0X). Factors affecting
the rate of NOx formation during combustion include the following: the
amount of excess air available, the peak flame temperature, the length of
time that the combustion gases are at a peak tempeature, and the cooling rate
of the combustion products.15 A series of tests conducted at three air
oxidation process units found incineration outlet N0X concentrations ranging
from 8 to 200 ppmv.1® The 200 ppmv concentration is the maximum value that
can be anticipated.
3-12
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Combustion of halogenated VOC emissions may result in the release of
halogenated combustion products to the environment. To ensure 98 percent
destruction of halogenated VOC, incineration temperatures greater than 870°C
are required. The HC1 emissions generated at this temperature are removed
by wet scrubbing, preventing the release of halogenated combustion products
to the environment.
The use of scrubbers to control HC1 emissions does result in a small
increase in wastewater. Water use is estimated at 0.033 m^/Kg (19.2 gal/lb)
of halogen in the waste gas.17 Effluent guidelines may also require pH
adjustment prior to discharge to the plant effluent system. The scrubber
wastewater is also likely to contain small quantities of organic compounds.
No significant solid wastes are generated by a thermal incinerator used
for VOC destruction.
3.2.2 Catalytic Incinerators
3.2.2.1 Equipment and Operating Principles
A catalyst is a substance that changes the rate of a chemical reaction
without being permanently altered. Catalysts in catalytic incinerators
cause the oxidizing reaction to occur at a lower temperature than is required
for thermal oxidation. Catalyst materials include platinum, platinum alloys,
copper oxide, chromium, and cobalt. These materials are plated in thin
layers on inert substrates designed to provide maximum surface area between
the catalyst and the VOC stream.
Figure 3-2 presents a catalytic incinerator. The waste gas (1) is
introduced into a mixing chamber (3) where it is heated to approximately
320°C (~600°F) by the hot combustion products of the auxiliary burners (2).
The heated mixture then passes through the catalyst bed (4). Oxygen and VOC
diffuse onto the catalyst surface and are adsorbed in the pores of the catalyst.
The oxidation reaction takes place at these active sites. Reaction products
are desorbed from the active sites and diffuse back into the gas. The com-
busted gas can then be routed through a waste heat recovery device (5) before
exhausting into the atmosphere.
3-13
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Stacx
Catalyst Sed (4)
Auxiliary
Fuel Burners
Qotional
Heat Recovery
(5)
Mixing Chamber (3)
Figure 3-2 Catalytic oxidizer.
3-14
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Combustion catalysts usually open over a temperature range of 320 to
650°C (600 to 1,200°F). Lower temperatures can slow down or stop the oxidation
reaction. Higher temperatures can shorten the life of the catalyst or evaporate
the catalyst from the inert substrate. Offgas streams with high VOC concentra-
tions can result in temperatures high enough to cause catalyst failure. In
such cases, dilution air may be required. Accumulations of particulate
matter, condensed VOC, or polymerized hydrocarbons on the catalyst can block
the active sites and reduce efficiency. Catalysts can also be deactivated by
compounds containing sulfur, bismuth, phosphorous, arsenic, antimony, mercury,
lead, zinc, tin, or halogens. If these compounds deactivate the catalytic
unit, VOC will pass through unreacted or be partially oxidized to form com-
pounds (aldehydes, ketones, and organic acids) that are highly reactive
atmospheric pollutants which can corrode plant equipment.
Catalytic incineration destruction efficiency is dependent on VOC compo-
sition and concentration, operating temperature, oxygen concentration, catalyst
characteristics, and space velocity. Space velocity is commonly defined as
the volumetric flow of gas entering the catalyst bed chamber divided by the
volume of the catalyst bed. The relationship between space velocity and VOC
destruction efficiency is strongly influenced by catalyst operating tempera-
ture. As space velocity increases, destruction efficiency decreases, and as
temperature increases, VOC destruction efficiency Increases. A catalytic
unit operating at about 450°C (840°F) with a catalyst bed volume of 0.014 to
0.057 m^ (0.5 to 2 ft^) per 0.47 scm/sec (1,000 scfm) of offgas passing through
the device can achieve 95 percent VOC destruction efficiency.^ Destruction
efficiencies of 98 percent or greater can be obtained by utilizing the appro-
priate catalyst bed volume to offgas flow rate.
Applications
Catalytic incineration has been applied to waste streams from a variety
of stationary sources. Solvent evaporation processes associated with surface
coating and printing operalons are a major source of VOC emissions, and
catalytic incineration is widely used by many industries in this category.
Catalytic incinerators have also been used to control emissions from varnish
3-15
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cookers, foundry core ovens, filter paper processing ovens, plywood veneer
dryers, and gasoline bulk loading stations.
The sensitivity of catalytic incinerators to VOC inlet stream flow
conditions and catalyst deactivation, limit their applicability for many
industrial processes.
3.2.2.3 Costs .
Capital costs for catalytic incinerators are dependent upon the same
variables as thermal incinerators (see Section 3.1.1.3). Cost data on
catalytic incinerators are available in an EPA study^ for seven waste-gas
flows: 700, 2,000, 5,000, 10,000, 20,000, 50,000, and 100,000 scfm; for a
destruction efficiency of 99 percent; and for no heat recovery, with a recuper-
ative heat exchanger used to heat the waste gas and combustion air, and heat
recovery with a waste-heat boiler used to produce steam. The cost data
includes all indirect costs, such as engineering and contractors' fees and
overheads.
Figure 3-3 presents the installed capital costs for a waste gas
with heat content at 10 Btu/scf in air. Using Appendix B to update costs to
May of 1984, capital costs for a 10,000 scfm waste-gas flow to a catalytic
incinerator with heat exchanger and 99 percent destruction are $730,000.2°
Annualized costs for a catalytaic incinerator include the same cost
items presented in the discussion of thermal incinerators (see Section
3.2.1.3). For catalytic incinerators, catalyst replacement costs must be
included. Catalysts can result in savings of about 40-60 percent in fuel
costs as compared to thermal incinerators.
Annualized costs for the catalytic incinerator handling 10,000 scfm
waste-gas discussed previously are $380,OOO2* (in 1984 dollars).
3.2.2.4 Energy Requirements
Like thermal incinerators, catalytic Incinerators typically require
supplemental fuel and electricity. Where VOC concentrations are high enough,
however, catalytic incinerators with recuperative heat exchangers require
little or no fuel except for start-up. Fuel savings are due to the lower
temperatures associated with catalytic incinerators. Gases which require
heating to 750°C with no catalyst might be oxidized at 300°C with a catalyst.
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10,000
99% Destruction
90% Destruction
(a) No heat recovery
(b) Waste-heat boiler, 56% recovery
(c) Recuperative heat exchanger, 53% recovery
«/»
= 1000
0»
100
1000
100
10,000
100,000
Waste-Gas Flow (sclm)
li'l. 3-3 Install ml Capital Couls of Catalytic Oxidizer Systumu
for Waste Gas with a Heat Content of 10 Btu/scf in Air
-------
3.2.2.5 Environmental Impacts
Environmental Impacts for catalytic incinerators are similar to impacts
presented in Section 3.2.1.5 for thermal incinerators. In addition, regenera-
tion or replacement of the catalyst can present a secondary pollution problem.
When the catalyst needs to be completely replaced, the used catalyst is treated
as solid waste requiring proper disposal. Regeneration of the catalyst also
requires proper disposal of any waste material that is produced.
3.2.3 Industrial Boilers and Process Heaters
3.2.3.1 Equipment and Operating Principles
Industrial boilers and process heaters can be used for VOC destruction.
The waste gas is either mixed in with the fuel or fed in through a separate
burner. A typical industrial boiler in the chemical industry is the watertube
design fired by natural gas. In a watertube boiler, hot combustion gases
contact the outside of heat transfer tubes, which contain hot water and
steam. , These tubes are interconnected by a set of drums that collect and
store the heated water and steam. Energy transfer from the hot flue gases to
water in the furnace water tube and drum system can be above 85 percent
efficient. Additional energy can be recovered from the flue gas by preheating
combustion air in an air preheater or by preheating incoming boiler feedwater
in an economizer unit.
Forced or natural draft burners are used to thoroughly mix the incoming
fuel and combustion air. If a process vent stream is combusted in a boiler,
it can be mixed with the incoming fuel or fed to the furnace through a separate
burner. In general, burner design depends on the characteristics of the fuel
mix (when the process vent stream and fuel are combined) or of the characteristics
of the vent stream alone (when a separate burner is used). A particular
burner design, commonly known as a high intensity or vortex burner, can be
effective for vent streams with low heating values (i.e., streams where a
conventional burner may not be applicable). Effective combustion of low
heating value streams is accomplished 1n a high intensity burner by passing
the combustion air through a series of spin vanes to generate a strong
vortex.22
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Furnace residence time and temperature profiles vary for industrial
boilers depending on the furnace and burner configuration, fuel type, heat
input, and excess air level. A mathematical model has been developed that
estimates the furnace residence time and temperature profiles for a variety
of industrial boilers.23 This model predicts mean furnace residence times of
from 0.25 to 0.83 seconds for natural gas-fired watertube boilers in the size
range from 4.4 to 44MW (15 to 150 x 10® Btu/hr). In boilers at or above the
44 MW size residence times and operating temperatures ensure a 98 percent VOC
destruction efficiency. Units are designed to mix and burn all fuel efficiently.
Furnace exit temperatures for this range of boiler sizes are at or above
1,200°C (2,200°F) with peak furnace temperatures occurring in excess of
1,540°C (2,810®F). Residence times for oil-fired boilers are similar to the
natural gas-fired boilers described here.
Like boilers, process heaters take the heat produced by fuel combustion
and transfer it by radiation and convection to fluids contained in tubular
coils. Process heaters are used in the chemical industry to drive endothermic
reactions. They are also used as feed preheaters and as reboilers for some
distillation operations. Fuels used include natural gas, refinery off gases,
and various grades of fuel oil. Gaseous fuels predominate.
In the design of process heaters, the radiant and convective sections
are modified depending on the application considered. In general, the radiant
section consists of the bumer(s), the firebox, and a row of tubular coils
containing the process fluid. Most heaters also contain a convective section
in which heat is recovered from hot combustion gases by convective heat
transfer to the process fluid.
Process heater applications in the chemical industry can be broadly
classified with respect to firebox temperature as follows: (1) low firebox
temperature applications such as feed preheaters and reboilers, (2) medium
firebox temperature applications such as steam superheaters, and (3) high
firebox temperature applications such as pyrolysis furnaces and steam-
hydrocarbon reformers. Firebox temperatures within the chemical industry
can range from about 400°C (750°F) for preheaters and reboilers to 1,260°C
(2,300°F) for pyrolysis furnaces.
3-19
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A boiler or process heater furnace Is comparable to an incinerator where
the average furnace temperature and residence time determines the combustion
efficiency. However, when a vent gas 1s injected as a fuel into the flame
zone of a boiler or process heater, the required residence time is reduced
due to the relatively high flame zone temperature. The following test data,
which document the destruction efficiencies for industrial boilers and process
heaters, are based on injecting the wastes identified into the flame zone of
each combustion control device.
As discussed in previous sections, firebox temperatures for process
heaters show relatively wide variations depending on the application. Tests
were conducted by EPA to determine the benzene destruction efficiency of five
process heaters firing a benzene offgas and natural gas mixture. The units
tested .are representative of process heaters with low temperature fireboxes
(reboilers) and medium temperature fireboxes (superheaters). Sampling problems
occurred while testing one of these heaters, and as a result, the data for
that test may not be reliable and are not presented. The reboiler and super-
heater units tested showed greater than a 98 percent overall destruction
efficiency for to Cg hydrocarbons. Additional tests conducted on a second
super heater and a hot oil heater showed that greater than 99 percent overall
destruction of to Cg hydrocarbons occurred for both units.^
3.2.3.2 Applications
Industrial boilers and process heaters are currently used by industry to
combust process vent streams from chemical manufacturing operations, and
general refinery operations. Both devices are most applicable where high
vent stream heat recovery potential exists.
Combustion of process vent strams can affect the performance of a boiler.
The vent stream characteristics must be considered. Variable flow rates,
variable heat contents, and the presence of corrosive compounds may require
changes in operating methods but do not prevent use of a boiler as a control
device.
The introduction of a process vent stream into the furnace of a boiler
or heater could alter the heat transfer characteristics of the furnace. Heat
3-20
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transfer characteristics are dependent on the flowrate, heating value, and
elemental composition of the process vent stream, and the size and type of
heat generating unit being used. Often, there is no significant alteration
of the heat transfer, and the organic content of the process vent stream can
in some cases lead to a reduction in the amount of fuel required to achieve
the desired heat production. In other cases, the change in heat transfer
characteristics after introduction of a process vent stream may affect the
performance of the heat generating unit, and increase fuel requirements.
Flame fluttering within the furnace could also result from variations in the
process vent stream characteristics. Precautionary measures should be consid-
ered in these situations.
When a boiler or process heater is applicable and available, they
are excellent control devices since they can provide at least 98 percent
destruction of VOC in most cases. In addition, near complete recovery of the
vent stream heat content is possible. However, both devices must operate
continuously and concurrently with the pollution source unless an alternate
control strategy is available.
3.2.3.3 Costs
Capital costs for application of a boiler or process heater to control
VOC typically assume the plant has an existing boiler which can be modified
to accommodate the vent stream. Natural gas-fired watertube boilers are
most common and boiler modifications include increasing the induced fan size
and replacing the existing burner with one capable of burning a fuel and vent
gas mixture. Total installed capital costs associated with a boiler combusting
a 0.0123 scm/s (26 scfm) vent stream with a heating value of 494 Btu/scf are
$32,000 (1984 dollars).26 Capital costs include the pipes, fittings and
compressors necessary to transport the vent stream from its source to the
control device.
Annualized costs for a boiler include direct operating and maintenance
costs, and annualized capital changes. In many cases, the energy recovery
associated with combusting the vent stream results 1n a cost savings. For
the vent stream discussed above, annualized costs are a net cost savings of
$27,000 (in 1984 dollars).27
3-21
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3.2.3.4. Energy Requirements
As noted earlier combustion of vent streams with high heat contents in
boilers or process heatrs can result in a net energy savings. Savings result
from decreased fuel consumption or increased steam production.
3.2.3.5. Environmental Impacts
The principal environmental impact associated with the use of boilers or
process heaters is the increased nitrogen oxides emissions. Most units use
natural gas as a primary or supplemental fuel. Data on N0X emissions from
gas-fired process heaters show N0X concentrations from 76 to 138 ppmv.
Typically, mechanical draft heaters with preheating emit more N0X than
furnaces without preheating and natural draft furnaces. Also, N0X
emissions are higher under typical excess air conditions (about 5.5 percent
oxygen) than under low excess air conditions (about 3 percent oxygen).28
Adding the process vent VOC results in an incremental increase in NOx.
3.2.4 Flares
A flare is a combustion control device which provides a safe and
economical way of disposing of sudden releases of large amounts of gas.
Flares are also used to combust continuous vent streams. Flares are used
extensively to burn purged and waste products from refineries, excess gas
production from oil wells, vented gas from blast furnaces, unused gas from
coke ovens and waste and purge products from the chemical industry.
3.2.4.1 Equipment and Operating Principles
Flaring is an open combustion process. The air surrounding the flare
provides the oxygen needed for combustion. Along with the oxygen, good
combustion in flare requires adequate flame temperature, sufficient residence
time in the combustion zone, and turbulent mixing.
Flares can be divided into two major types, with or without assist.
Flares with assist include steam-assisted, air-assisted, and pressure-
assisted.
Figure 3-4 indicates the primary elements of an elevated, steam-assisted
flare. Process off gases are delivered to the flare through the collection
header. The knock-out drum removes water or liquid hydrocarbons to prevent
3-22
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(9) Flare Tip
SaiiM
Helps prevent flash back
&u Callccnoa Hutut
Mfl Tiamin Lut> (1)
Quia
Figure 3-4 Steam-assisted elevated flare system.
3-23
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problems in the flare combustion zone. Off-gases usually pass through a
water seal and a gas barrier to prevent flame flashbacks during low gas
f1ows.
Flashbacks are also prevented by controlled addition of a purge gas (N2,
CO2, or natural gas). Careful control of the gas flow rate can prevent both
flashbacks due to low flows and detached flames due to very high flows.
The gas stream enters at the base of the flame where it is heated by the
already burning fuel and the pilot burners at the flare tip. The flare tips
are designed to stably burn gases over a very wide range of flow rates and
to suppress soot. For most fuels and flow rates, soot suppression requires
that air be mixed into the flare at a faster rate than simple gas diffusion
can supply. Steam-assisted flares use steam to increase gas turbulence in
the flame boundary zones. The turbulence draws in more combustion air and
improves combustion efficiency. By minimizing the cracking reactions that
form carbon, the steam injection promotes smokeless operation. The steam
requirement depends on the tip diameter, the gas composition, and the steam
nozzle velocity. Typically, 0.15 to 0.5 kg of steam per kg of flare gas is
required.29 The injection of steam into a flare can be controlled either
manually or automatically. Manually controlled flares require an operator to
observe the flare and add steam as necessary to maintain smokeless operation.
Steam consumption can be minimized by using devices which sense flame
characteristics and adjust the steam flow rate to maintain smokeless operation.
In situations where steam is too expensive, flares then use forced air
for combustion air and mixing. Air-assist is rarely used on large flares
because the air flow is difficult to control when the gas flow is intermittent.
About 0.8 hp of blower capacity is required for each 100 lbs/hr of gas flared.-*0
In a small percentage of flares, the system pressure, in conjunction
with the nozzle design, provides the necessary gas turbulence. This type of
flare is described as pressure-assisted. These flares have multiple burner
heads staged to operate based on the quantity of gas released to the flare.
With a high nozzle pressure drop, the energy of the flared gas provides the
mixing necessary for smokeless operations. This type of flare is usually
enclosed and located at ground level.
3-24
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Typically, flares without assist burn gas continuously while steam-
assisted flares are required for large volumes of gas released during emergen-
cies.
Based on a series of flare combustion efficiency studies, EPA has
concluded that 98 percent combustion efficiency can be achieved by steam-
assisted and air-assisted flares combusting gases with heat contents greater
than 11 MJ/nm3 (300 btu/scf). In addition, steam-assisted and nonassisted
flares must be designed and operated with an exit velocity either (a) less than
60 scf per second (fps), (b) less than 400 fps if the heat content of the gss
being combusted is greater than 37 MJ/nm3 (1,000 Btu/scf), or (c) less than a
velocity determined by an equation based on the heat content if the gas being
combusted is between 11 MJ/nm3 and 37MJ/nm3 (300 Btu/scf and 1,000 Btu/scf).
Air-assisted flares must be designed and operated with an exit velocity less
than a velocity determined by another equation based on the heat content of
the gas being combusted in the flare.3*
Flares are not normally operated at the very high steam to gas ratios
that resulted in low efficiency in some tests because steam is expensive and
operators make every effort to keep steam consumption low. Flares with high
steam rates are also noisy and may be a neighborhood nuisance.
3.2.4.2 Applications
Estimates from 1980 reported 16 million ton/year of gas are flared in
the United States. Blast furnace gas accounted for 60 percent by weight and
19 percent by heating value. Petroleum production gases accounted for
18 percent by weight and 32 percent by heating value.^2
These values reflect the varied composition of gases flared in the United
States. Gases flared from refineries, petroleum production, and the chemical
industry are composed largely of low molecular weight VOC and have high
heating values. Those flared from blast furnaces consist of inert species
and carbon monoxide with a low heating value. Gases flared from coke ovens
are Intermediate in composition to the other two groups and have a moderate
heating value.
3-25
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For dilute gas streams, supplemental fuel costs can eliminate flares as a
disposal alternative. Unlike incinerators, flares have no heat recovery
capability.
In a typical installation, flares are designed to control the normal
operating vents or emergency upsets which require release of large volumes of
gases. Large diameter flares may control low volume continuous vent streams
from operations such as distillation and also handle emergency releases. In
refineries usually all process vents are combined in a common header which
supplies fuel to boilers and process heaters. However, excess gases and
fluctuations in flow in the header are flared.
An emission'control device that can be used for almost any VOC stream
with sufficient heat content, flares can handle fluctuations in VOC concen-
tration, flowrate, and inerts content very easily. Gases containing high
concentrations of halogen should not be flared to prevent corrosion of the
flare tip or secondary pollution such as SO2 or HC1.
3.2.4.3 Costs
Flare capital costs are dependent upon flare height and tip diameter.
The tip-diameter selected is a function of the combined vent streams and
supplemental fuel flowrates, the combined gas temperature, mean molecular
weight, and the assumed tip velocity. Flare height is selected to minimize
the risk to workers. The flare height is selected so the maximum ground
level heat intensity is 440 W/m^ (140 BTU/hr ft.2).
The Background Information Document for Proposed Standards on Reactor
Processes in Synthetic Organic Chemical Manufacturing Industry33 presents a
capital cost equation for a flare as a function of flare height and tip
diameter. The equation was generated by using a linear regression analysis
of cost curves presented in an EPA report.34 Adding in the ducting and fan
costs results in the installed capital costs of the flare system.
As an example, for a reactor process vent stream with a medidan value
flow rate (2.0 scm/m) and a median heat content (12 MJ/scm), installed capital
costs for flare systems are $78,000 (in 1984 dollars).^
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Annualized costs for a flare include the cost items presented in the
discussion of thermal incinerators (see Section 3.2.1.3). Utility requirements
for flares do not include make-up water but do include steam for the flare
operation. Supplemental natural gas is used to purge flare systems. Caustic
is not required.
For the reactor process vent stream cited previously, annualized costs
for the flare system are $47,000 (in 1984 dollars).^
3.2.4.4 Energy Requirements
Flares usually do not need any additional fuel to support the combustion
of the waste stream. Energy is required for the steam used in steam-assisted
flares and for the electricity to run the blower on an air-assisted flare. A
small amount of gas is used by the pilot burners.
3.2.4.5 Environmental Impacts
As with other .combustion control techniques, destruction of VOC with a
flare results in secondary emissions, particularly N0X. N0X concentrations
were measured at two flares used to control hydrocarbon emissions from refinery
and petrochemical processes. One flare was steam-assisted and the other air-
assisted, and the heat content of the fuels ranged from 5.5 to 81 MJ/scm (146
to 2,183 Btu/scf). The measured N0X concentrations ranged from 0.4 to 8.2 ppmv.
These values were somewhat lower than those for incinerators (Section ,3.1.1.5)
and considerably lower than those for boilers (Section 3.1.3.5). The ranges
of relative N0X emissions per unit of heat input are 7.8 t 90 g/GJ (0.018 to
0.208 lbs/10® Btu) for flares.Streams containing halogenated VOC are not
typically controlled by a flare, so halogenated combustion products are not
secondary pollutants.
3-27
-------
3.3. ADSORPTION *
Adsorption 1s the process by which components of a gas, vapor or dissolved
matter are retained on the surface of a solid. Commercial application of this
process for abatement of air pollution uses solid adsorbent carbon particles
which are highly porous, resulting 1n a very large surface-to-volume ratio.
Gas molecules are able to enter the porous material and, as a result, the large
surface area of the carbon particle is available for adsorption.
Vapor-phase carbon adsorbers are used by many industries as a control
technique for VOC emissions. They can be used on waste-gas streams of low VOC
concentration where a condenser or scrubber 1s ineffective or uneconomical.
After the organics are retained by the adsorbent, they can subsequently be
desorbed in a more concentrated form for reuse or disposal.
Adsorption systems are available as "package installations" from a
number of manufacturers. The economic feasibility of organic vapor emission
control by adsorption depends on the concentration of the organics in the
exhaust" stream, the value of the recovered organics, the life of the carbon,
and the cost of removing adsorbed organics from the adsorbent bed.
3.3.1 Operating Principles and Equipment
Adsorption occurs primarily through two mechanisms: (1) physical
adsorption, in which van der Waals' adsorption produces a layer of gas not
more than several molecules thick on the surface of the carbon. Within
the capillaries of a porous solid, however, this surface adsorption is
supplemented by capillary condensation. The combination of capillary
condensation and molecular attraction substantially increases the total
amount of-vapor which can be adsorbed. (2) Chemical adsorption, or
"chemisorption," results in an adsorbed gas layer only one molecule
thick. Both chemisorption and physical adsorption are exothermic processes;
the heat released from adsorption is on the order of 10 kcal/g-mole.
Carbon has a finite adsorption capacity. Initially, adsorption
1s rapid and, with properly designed system, the bed of carbon removes
essentially all of the pollutant from the gas stream. As the organic-laden
gas passes through the carbon bed, the cafbon particles which are first
* Additional information on carbon adsorption is contained in
Appendix C of this report.
3-28
-------
encountered gradually become saturated, i.e., all of the surface is covered
with organic material. The subsequent carbon then is exposed to organics
and it begins to adsorb. Over a period of time the saturation "front"
travels through the bed until no active surface remains. At this time,
"breakthrough" occurs, i.e., there is no further solvent reduction and
the outlet organic concentration will equal the inlet. In reality, this
doesn't happen quite so precipitiously. Because of channeling of gases
through the bed and absence of perfection in contact between the carbon and
organic vapor, the loss of adsorption efficiency is not instantaneous.
The point at which removal efficiency first diminishes (the exhaust
concentration begins to increase) is called the "break-point". In order
to maximize vapor recovery, design and operating procedures considerations
should require the adsorber be taken off-stream to be regenerated before
the break-point is reached.
A schematic of the adsorption process is shown in Figure 3-5. The
diagram shows how the concentration of VOC varies from the inlet to the
exit of a carbon bed at three different times. The organic content of
the bed, presented as percent of saturation, is shown as a function of
distance along the bed. The curve at Time 1 represents conditions shortly
after placing a regenerated bed on line. Conventional regeneration of a
bed does not remove all of the adsorbed organics. For that reason, the
entire bed retains a small amount of VOC after regeneration. This "heel"
will result in some small amount of emissions when it is returned to
service as the gas stream will strip these organics from the carbon nearest
the outlet. This "base-line" effluent concentration is usually less than
10 ppm.38 The exit VOC concentration from an adsorber is near zero during
the first adsorbtion cycle when virgin carbon is used.39
The curve at Time 2 represents conditions part way through the adsorption
cycle. A significant portion of the carbon bed is now saturated. The effluent
VOC concentration, however, remains constant and low, typically, below 20 ppm.
The length of the curve represents the interface within the bed between
the layer of saturated carbon particles and the adjacent unsaturated
ones, i.e., the transfer zone along which adsorption takes place.
3-29
-------
%
100
ffime 3.
Vapor Flow
Time 1.
-+
Inlet
—
Outlet
-------
As more of the carbon becomes saturated, this transfer zone progresses
through the bed until carbon at the outlet face of the adsorber begins to
accept VOC. At this time the effluent concentration begins to increase,
and "breakthrough" occurs. This is represented by the curve at Time 3 of
Figure 3-5. Shortly before (and certainly no later than) the breakthrough
point, a well operated adsorption system will remove that carbon bed from
service by directing the VOC laden inlet stream to another carbon bed which
has been regenerated since it last saw service. The saturated carbon must
be regenerated to remove the VOC (or the carbon replaced) in preparation
for future operation.
The adsorption capacity of carbon for various organics 1s not uniform.
Generally, the adsorption capacity is inversely proportional to volatility.
Initially, all organic vapors are adsorbed equally. With time, however,
higher-boiling constituents will displace more volatile components. Of
general interest, this displacement phenomena, which repeats for each
vapor in a mixture, has seen limited use as a technique to separate
specific organics from a mixture.
Conventional adsorption systems recover the organic vapors which are
desorbed from the carbon during the regeneration cycle. Used or "spent"
carbon beds are usually regenerated with low-pressure steam that is
passed through the bed in the opposite direction of the gas flow during the
adsorption cycle. The adsorption capacity of carbon is inversely proportional
to temperature. Steam both heats the bed and strips the adsorbed organics.
The organic adsorbate which remains on the carbon after regeneration (the
heel) accounts for most of the difference between the saturated adsorption
capacity and the operating capacity. The amount of heel which remains
after regeneration is a function of the amount of steam used.4^
A carbon adsorber bed may be fixed, moving, or fluidized. A typical
fixed-bed adsorber system, with two adsorbtion units or beds, is shown in
Figure 3-6. One adsorber cleanses the vapor-laden stream while the other
is undergoing steam regeneration. The steam, contaminated with the
pollutant vapors, is condensed after which the organics and water can be
separated by gravity decantation or distillation. In some cases, the
mixture is incinerated.
3-31
-------
I XIIAtini AMI
II) AIMOM'III MC
r~
STEAM 4-SOLVENT
vapors
TO
ATMOSPIIEnE
CONOENSEn
311;AM OM llOt OAS
DECANTER ANO/OH
DISTILLATION
COLUMN
WASTE
WATER
07-till-•
Kigun- 3-6. A TWO-UNIT FIXED BED ADSORBFR
-------
Although many two-unit adsorber systems are in use, three unit systems
are becoming more comnon. Since adsorbative capacity is inversely proportional
to temperature, for maximum efficiency, a bed must be cooled after regeneration
before it is again placed in service. Inclusion of the third bed in the
rotation sequence permits more time for a regenerated bed to cool. Some
three bed systems place the cooling bed in service downstream of the bed
in the primary adsorbtion cycle in order to recover emissions which
otherwise would be lost as a result of breakthrough of the primary bed.
The simplest fixed-bed adsorber is a vertical cylindrical vessel
fitted with horizonal perforated screens that support the carbon. Another
is shaped like a cone. The cone allows more inlet and exit surface area
for gas contact within a fixed vessel diameter thereby accommodating
higher gas flow rates at lower pressure drops than would be available with
a flat bed in the same vessel. •
Moving bed adsorbers move the adsorbent into and out of the adsorption
zone. Because of the continuous regeneration capability of a moving bed,
a more efficient utilization of the adsorbent is possible than with
stationary bed systems. Disadvantages include wear on moving parts, and
attrition of the adsorbent.
In fluidized-bed systems, adsorption and desorption are carried out
continuously in the same vessel. The system consists of a multistage,
countercurrent, fluidized-bed adsorption section; a pressure-sealing
section; and a desorption section. Nitrogen gas is used as a carrier to
remove the solvent vapors. The regenerated carbon is carried by air from
the bottom to the top of the column.
The solvent laden air (SLA) is introduced into the bottom of the
adsorption section of the column and passes upward countercurrent to the
flow of carbon particles. Adsorpton occurs on each tray as the carbon is
fluidized by the SLA. The carbon falls down the cdlumn through a system
of overflow weirs. Below the last tray, the carbon falls to the desorption
section where indirect heating desorbs the organic compounds from the
carbon; hot nitrogen gas passes through the bed countercurrent to the
3-33
-------
carbon flow and removes the organic compounds. The desorption temperature
is normally around 121°C (250°F) but can be raised to 260°C (500°C) to
remove buildup of highboiling materials. The desorption section is
maintained continuously at the temperature required to volatilize the
absorbed compounds. The solvent and nitrogen mixture is directed to a
condenser where the solvent can be recovered for reuse. The nitrogen is
sent through the "secondary adsorber" (top layer of carbon in the desorption
section), which removes residual solvent from the nitrogen, and is then
recycled.
The microspherical particles of carbon used in a fluidized-bed are
formed by spray-drying molten petroleum pitch. The carbon particles are
easily fluidized and have strong attrition resistance. The adsorptive
properties of carbon made this way are similar to those of other activated
carbons.
The parameters considered in design of a fluidized-bed carbon adsorber
system ;
are:
1.
Type of solvent(s);
'2.
SLA inlet concentration;
3.
SLA flow rate;
4.
Temperature of the inlet SLA;
5.
Relative humidity of the inlet SLA;
6.
Superficial bed velocity;
7.
Bed pressure drop;
8.
Rate of carbon flow;
9.
Degree of regeneration of the carbon (bed); and
10.
Condenser water outlet temperature.
The first five parameters are characteristics of the production process.
The next two are design parameters for the adsorber. The next three are
operating parameters. The rate of carbon flow is set by the operator to
achieve desired control efficiency. Just as with fixed-bed, the dryer
exhaust gas (the SLA) must be cooled before 1t reaches the adsorber in
order to optimize the carbon's adsorbability. Pressure drop per stage
3-34
-------
normally ranges from 1 to 2 kilopascals (kPa) (4 to 8 in. water), with
six to eight stages required, depending on the application. The pressure
drop across the entire bed is 6 to 16 kPa (24 to 64 in. water). The gas
velocity through the adsorption section is as high as 1 m/s (200 fpm),
which is two to four times that used in fixed bed adsorbers. For a given
flow rate, this high gas velocity reduces the cross-sectional area of the
bed.
The primary problem that may occur with operation of fluidized-bed
adsorbers is fouling of the carbon. The same factors that affect fouling
of carbon in fixed-bed adsorbers also affect the carbon used in fluidized-
bed adsorbers. Corrosion is generally not a problem in fluidized-bed
adsorbers; because stripping is b.y nitrogen rather than steam, the water
content of the recovered solvent is low, typically 5 percent or less.
The only water present in the recovered solvent is that which was adsorbed
from the SLA. Thus, generally, the carbon adsorber need not be made of
expensive corrosion-resistant materials. Bed fires are generally not a
problem in fluidized-bed adsorbers because the relatively high superficial
velocities and the intimate contact between the SLA and activated carbon
eliminate the possibility of hot spot formation. However, hot spots can
form, depending on the solvents adsorbed, if the bed is shut down before
being completely stripped. Shutdowns resulting from mechanical problems
could create conditions leading to potential bed fires.
A distillation system may not be required for a fluidized-bed
adsorption system because of the low water content of the recovered
solvent (less than 5 percent water by weight). Cleanup can be as simple
as drying by the addition of caustic soda.
3.3.2 Appl1 cations
Processes that can be controlled by adsorption include VOC emissions
from dry cleaning, degreasing, paint spraying, solvent extracting, metal
foil coating, paper coating, plastic film coating, printing, fabric
impregnation, and manufacturing of plastics, chemicals, pharmaceuticals,
rubber, linoleum, and transparent wrapping.
3-35
-------
Organics desorbed from the carbon are generally condensed and either
reused directly or reprocessed. In some cases, such as controlling a
mixture of organics emitted from a paint spray booth, it may be more practical
to send the desorbed organics directly to an incinerator without ever
condensing them. In this situation the adsorber acts as a "concentrator."
The desorbed organic-laden stream is lower in volume and higher in organic
concentration than the feed stream to the adsorber. This allows for use
of a smaller incinerator with consequently lower capital and operating costs
than if the feed stream were sent directly to an Incinerator. Moving bed
adsorbers have been used in Europe and Japan for thts purpose and are now
beginning to see similar use in this country.
The preferential 'adsorption charactristies and physical properties
of a variety of industrial adsorbents determine the appropriate applications
of each type. Physical adsorbents can remove organic solvents, impurities,
and water vapor from gas streams. Adsorbents may have an affinity for
either polar or nonpolar compounds. Polar adsorbents such as silica gel
and activated alumina are poor adsorbents for organics because of their
strong affinity for water. Activated carbon is the most widely used
nonpolar adsorbent. It will selectively adsorb organic vapors from gases
even in the presence of water. A list of some of the organics for which
activated carbon is known to be used is presented in Table 3-3.
Molecular sieves are also classed as physical adsorbents. Like
silica gel and alumina, their strong affinity for water greatly limits
their use for control of organic vapor emissions.
Soda lime, sometimes combined with activated carbon, has been used
to chemisorb vapors such as ethanoic acid, acetonitrile, acrylonitrile,
allyl chloride, and vinyl propyl disulfide. Some physical adsorbents are
impregnated with chemically reactive compounds that react with vapor
molecules after physical adsorption has occurred. Pollutant vapors that
have been removed by impregnated adsorbents include ethylene, organic
acids, mercaptans, olefins, phosgene, and thiophenol.
3-36
-------
TABLE 3-3. ORGANIC COMPOUNDS CONTROLLED BY CARBON ADSORPTION42
1.
Acetaldehyde
23.
Ethanol
45.
Methyl Isobutyl Ketone
2.
Acetone
24.
Ethyl Acetate
46.
Methyl Methacrylate
3.
Acetylene
25.
Ethyl Acrylate
47.
Methylene Chloride
4.
Acrylonitrile
26.
Ethyl Mercaptan
48.
VM&P Naphtha
5.
Ammonium Thiocyanate
27.
Fluorazepam HC1
49.
Naphthalene
6.
Asphalt
28.
Fluoro-trlchloromethane
50.
ClO-Paraffin
7.
Benzene
29.
Formaldehyde
51.
Perchloroethylene
8.
Benzoyl Chloride
. 30.
Freon 11, 114ABS
52.
Phenol
9.
Butanol
31.
Heptane
53.
Phosgene
10.
Butyl Acrylate
32.
n-Hexane
54.
Propane
11.
Carbon Tetrachloride
33.
Isopropanol
55.
Stoddard Solvent
12.
Cellosolve
34.
"Lactol"
56.
Styrene
13.
Chloroform
35.
Malelc Anhydride
57.
Terephthalic Ac1d-HN03
14.
Cumene
36.
Mercaptans
58.
Toluene
15.
Cumene Hydroperoxide
37.
Methacrylic Acid
59.
Toluene Dllsocyanate
16.
Cyclohexane
38.
Methanol
60.
Trichloroethane
17.
1,6-Diamlnoloxane
39.
Methyl Acetate
61.
trichloroethylene
18.
D1bromochloropropane
40.
Methyl Bromide
62.
Vinyl Chloride
19.
p-Dichlorobenzene
41.
Methyl Chloride
63.
Vinylidene Chloride
20.
Dlchloroethylene
42.
Methyl Chloroform
64.
Xylene, meta & para
21.
Diethyl Ether
43.
Methyl Ethyl Ketone
65.
p-Xylengen
22.
Dimethyl Ketone
44.
Methyl Formcel
66.
Xylol
-------
In some specific situations the owner of an adsorbtion system may
choose a regeneration system other than conventional steam regeneration.
When making such a selection, the owner will likely evaluate the least
cost method for ultimate recovery or disposal of the organics. Alternative
regeneration systems include:^
1. Heated air or inert gas regeneration of the primary bed followed
by a second adsorption with steam regeneration of the second bed.
2. Heated air or Inert gas regeneration followed by solvent condensa-
tion at lowered temperature with recycle of noncondensibles through absorbent
bed.
3. Regeneration by pressure reduction.
Under normal circumstances, the cost effectiveness of a carbon bed recovery
system is Inversely proportional to the organic concentration of the exhaust
gas stream. There are some restrictions, however to the maximum concentration
that can be fed to an adsorber. Safety considerations will likely preclude
concentrations greater than 50 percent of the lower explosive limit. Also, the
heat of adsorption must be considered because the heat released by adsorption
may raise the temperature of the carbon bed high enough to cause spontaneous
combustion.
After regeneration, a bed is normally cooled by passing clean air or
the discharge from another bed through the carbon. If the time required
for regenerating and cooling a bed is longer than the adsorption time for
another bed then a satisfactory system will require at least three beds
to assure a clean cool bed is available before breakthrough of the bed in
service.
3.3.3.1 Capital Costs^
The capital cost f.or a carbon adsorber is a function of the ventilation
rate, the type and mass emission rate of the pollutant, the length of the
adsorption and regeneration cycle, and the adsorption capacity of the carbon
at operating conditions. The key design parameters that determine the
size of the carbon adsorber are the face velocity and the bed depth. The
desired face velocity is approximately 80 to 100 feet per minute for most
commercial and industrial applications involving solvent recovery. The
depth of the beds may vary from 6 inches to 30 inches.
3-38
-------
For air purification systems where the concentration of pollutants
is on the order of 1 ppm or less, the desired face velocity is reduced to
approximately 40 fpm and bed depths may be only 0.5 to 3 inches. For a
given ventilation rate, the maximum desirable face velocity and the
minimum practical bed depth determine the minimum volume of working bed
of carbon that will be required.
For design purposes, the minimum working bed volume for minimum pre-
selected cycle time can be determined from the adsorption isotherm for
the particular adsorbent and adsorbate. The adsorption isotherm is a
plot of the adsorption capacity at constant temperature as a function of
the vapor pressure or the relative partial pressure of the adsorbate 1n
the gas stream. Normally, the adsorption .capacity of an adsorbent increases
with increased vapor pressure and decreases with increased temperature.
Using the appropriate adsorption isotherm, the adsorption capacity in
pounds of adsorbate per pound of adsorbent can be obtained for the desired
operating conditions. The adsorption capacity is then multiplied by a
design factor of between 0.1 and 0.5 to determine a working capacity.
A design factor of 0.25 can be used for preliminary sizing in most applica-
tions^. The weight of carbon for each bed is then determined by multiplying
the organic emission rate in pounds per hour by the desired length of the
adsorption cycle, in hours, and dividing by the working capacity in
pounds of adsorbate per pound of adsorbent.
For example, assume that toluene vapors at 70°F are generated by
a source at a rate of 6.15 lb/min and the inlet concentration to the
adsorber is to be maintained at 25 percent of the lower explosive limit
(LEL). The LEL for toluene in air is 1.29 percent or 3.07 lbs/1000
cu.ft.; hence, 25 percent of the LEL would be 0.32 percent or 0.768
lbs/1000 cu.ft. The vapor pressure of the toluene in air at a total
pressure of 760 mm Hg is determined by multiplying the concentration
(0.0032) by the operating pressure (760 mm Hg) to obtain a pressure of
2.4 mm Hg. Using the adsorption isotherm in Figure 3-7, the adsorption
capacity in percent by weight at this vapor pressure 1s 35 percent or
'3-39
-------
o
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I 1—-t—•]— 1 — i — i—1 • f —
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Pressure: 760 mm Hg
Carbon: 27 Ibs/FT^
TOLUENE VAPOR PRESSURE (itm Hg at 21 °C)
Figure 3-7. ADSORPTION ISOTHERM FOR TOLUENE 46
3-40
-------
0.35 lbs of toluene per lb. of carbon. Note that the adsorption isotherm
is for operating temperatures of 21°C (70°F) and operating pressures of
760 mm Hg with a carbon adsorbent having a density of 27 lbs/ cu.ft. A
working capacity of 8.75 percent is obtained by multiplying the adsorption
capacity from Figure 3-7 by a design factor of 0.25. If the adsorption
period is one hour per bed, then 369 lbs of toluene (6.15 Ibs/min x 60
mn/hr) will be recovered per bed. The carbon requirements per bed will
be 369 lbs/hr divided by 0.0875 lbs toluene/lb carbon or approximately
4200 lbs per bed with a one-hour adsorption cycle.
Adsorption isotherms for other hydrocarbons are available from
handbooks and manufacturers' literature. These isotherms have been devel-
oped for many adsorbents operating at select pressures and temperatures.
The cost of carbon adsorbers are presented in Figures 3-8 and
3-9, as a function of total pounds of carbon in the unit. The total or
gross number of pounds is determined by the adsorption rate and the
regeneration rate of the carbon for the emission being controlled. A
carbon adsorber will normally be a dual system with one bed on-line
adsorbing while the second bed will be off-line regenerating. Variations
in regeneration time are due to the type of solvent being desorbed and
any specific drying and cooling requirements. Normally, one hour is the
longest expected regeneration time. For some operations, such as dry-
cleaning and solvent metal cleaning where working bed capacity is high, a
longer adsorption phase may be desired. This is likely if steam capacity
for desorption is not always available.
Figure 3-8 represents the cost of packaged units for automatic -operation
in commercial and industrial applications. Commercial applications would
include dry-cleaning and solvent metal cleaning. Industrial applications,
which include lithography and petrochemical processing, cost about 30 percent
more than commercial requirements. Industrial requirements would include
those beds designed for heavier materials which will require high steam or
vacuum pressure designs and more elaborate controls to assure safety
against explosions and prevent breakthrough. Figure 3-9 presents the
cost of custom units, used mostly for industrial applications where the
gas flow rate exceeds 10,000 acfm.
3-41
-------
120
100
80
60
AO
20
WEIGHT OF
5 6 7
CARBON, 1000 LBS.
Figure 3-8.
PRICES FOR PACKAGED STATIONARY BED CARBON ADSORPTION
UNITS WITH STEAM REGENERATION
-------
o
o
c
1200
1000
800
OJ
i
OJ
600
400
200
-------
3.3.3.2 Annualized Costs47
An estimate of annualized costs will have two components, operating
costs and the annualized cost of the original capital investment. Table
3-4 provides a list of parameters and their use rate which may be used to
estimate operating costs for a carbon adsorber including requirements for
steam, cooling water, maintenance, electricity, and replacement carbon.
These assumptions represent a composite of information obtained by the EPA
from a variety of sources. To use the values in Table 3-4, independent
variables required to estimate costs are the pollutant emission rate,
estimated recovery efficiency, annual operating hours, exhaust gas rate,
and the purchase price. Replacement of carbon requires the same quantity
as the original capital installation.
In Table 3-4, the figure for steam consumption is based on both the
sensible heat (energy necessary to heat the bed and vessel from the
operating temperature (100°F) to the solvent boiling temperature) and the
latent heat of vaporization (the energy required to evaporate the solvent
from the bed). The latent heat is directly proportional to the quantity
present. The sensible heat depends also on the amount of carbon and the
design of the bed. For estimation purposes, a value of 4 lbs. per lb.
solvent desorbed is a reasonably figure.
The cooling water requirement is proportional to the steam consumption
rate in that it is used to condense and cool the regeneration steam. The
electrical consumption presumes a pressure drop of 20 inches of water
across the adsorber (a bed depth of 1.5 feet of 8-14 mesh carbon). The
pressure drop through a carbon bed is a function of the carbon granule
size, the size distribution, the packing of the bed, flow velocity and
vessel configuration. Given a specific carbon bed, pressure losses through
the bed are proportional to the square of the superficial face velocity.
The second major cost factor is a function of the original installed
cost of the adsorber. This can be minimized by reducing the amount of waste
gas to be treated (thus increasing the concentration of organics), thereby
reducing the size of the adsorber needed.
3-44
-------
TABLE 3-4 - TECHNICAL ASSUMPTIONS FOR ESTIMATION OF DIRECT OPERATING COSTS47
Item
Steam Consumption
Cooling Water
Electricity
Maintenance
Carbon Replacement
Assumption
4 lb. per lb. pollutant recovered
12 gal. per 100 lbs. steam
5 HP per 1000 ACFM
5% of equipment purchase cost
Replace original carbon every five years
Reference
MSA, DOW, STAUFFER, VIC
SHAW
STAUFFER, MSA
Compromise between DOW and MSA
STAUFFER, MSA
MSA - "Hydrocarbon Pollutant Systems Study" by MSA Research Corp., EPA Contract EHSD 71-72, January, 1973.
DOW - "Study to Support New Source Performance Standards for Solvent Metal Cleaning Operations," EPA
Contract 68-02-1329, Dow Chemical Co., June, 1976.
STAUFFER - Private communication from J. J. Harte, Stauffer Chemical Co. to Richard Schippers, EPA,
April 11, 1977 on subject of carbon adsorber costs for control of ketones and toluene.
VIC - Private communication from J. W. Barber, VIC Manufacturing Co., to F. L. Bunyard, EPA, June 3, 1977.
SHAW - "Carbon Adsorption/Emission Control Benefits and Limitations," paper presented at Surface Coatings
Industry Symposium, April 26, 1979.
-------
Since almost all recovered organics have some value, a by-product
credit should be included as part of the calculation of the annualized
cost of control. Depending on the value of the recovered
organic, this credit can have a substantial effect on the amortization
rate of the capital costs of the equipment.
The annualized carbon adsorption costs for a plant producing rubber-
coated industrial fabric (dip-coating process) are presented in Table 3-5.
3.3.3.3 Comparison to Incineration
Carbon adsorption is usually less costly than incineration for
the control of organics in concentrations below 100 ppm because of the
cost of supplemental fuel required for combustion. The cost of the carbon
adsorption process, however, is adversely affected if the waste gas
stream contains water-soluble compounds, or organics that are very difficult
to desorb since, in the first case, an aditional purification step may be
necessary to obtain maximum value for the adsorbate, and in the second
case, the effective life of the carbon is decreased.
If the waste gas stream is sufficiently rich in organics to sustain
combustion, then the operating costs for a combustion device can be very
low, rendering an incinerator the most economical device. This is
particularly true when the recovered organics would have little value.
Once the decision is made to use an incinerator, incorporation of primary
and/or secondary heat recovery will reduce the cost of incineration.4^
3.3.4 Utility Requirements
An adsorption system requires steam (or hot gas) to regenerate the
carbon and electricity to power pumps, fans and instrumentation. If the
concentration of organics in the waste gas can be increased by reducing
the volume of exhaust gas, energy costs for the fan will decrease.
Figure 3-10 illustrates the effect of concentration on energy requirements
for a typical dual fixed-bed adsorber operating at 100°F (38°C).50
When steam is used to regenerate the adsorption bed, it represents the
majority of the total energy required for the adsorption system. The
amount of steam needed is about 4 pounds per pound (4 kg/kg) of organic
vapor adsorbed. Regeneration by steam leaves the bed wet; thus, some
cooling of the gas is accomplished.
3-46
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TABLE 3-5. TYPICAL COMPONENTS OF ANNUALIZED COSTS FOR CARBON ADSORPTION
SYSTEMS4^
Configuration
1. Dual fixed-bed adsorber operating at 95°F
2. Toluene recovery with condenser and decanter
3. Total carbon required: 2,160 lbs.
4. Total installed cost: $215,300
Gas Stream Characteristics
Flow 2,050 scfm
Concentration 25% LEL
Process Gas Temperature 200°F
Component Annual Cost (1st Quarter 1984 dollars)
(1) Operating and maintenance labor $12,920
plus materials: (6 percent of total installed cost)
(2) Carbon replacement cost at 5-year life $ 580
f2160 lb x $1.35 per lb. a 583)
5
(3) Utilities:
Electricity $ 1,170
(2550 acfm x 5 hp x 0.746 kwh x 2000 hr/yr
10-3 cfm hp
x $0.056 x 1.1 = $1,170)
kwh
3-47
-------
Table 3-5 (Continued)
Steam $ 4,870
/l.53 x 105 lb, VOC x 4 lb. steam x $7.96
yr lb. VOC 1000 lbs. steam
= $4,870)
Cool ing Water $ 600
( 12 gpm x 306 lb. steam x 60 min. x 2000 hr.
100 lbs. steam hr. hr. yr.
x $0.13 = 5570)
1000 gal.
(Water used to cool exhaust to 95° C 3 $30)
(4) Captial Recovery Charges $47,370
(22 percent of total installed cost)
(5) Recovered Solvent Credit $26,010
(76.5 tons/VOC x 2000 lb/ton x $0.17 = $26,010)
yr lb. VOC
Net Annualized Costs $41,500
3-48
-------
J I I I I L_
5 10 15 20 25 30
GAS FLOW TO A0S0R86B. 103 SCFM
Figure 3-10. Energy Requirement for Adsorption-Solvent
Recovery System
3-49
-------
One alternative to steam is use of a hot noncondensible gas; another
is electrical resistance heating of the bed. The major energy requirements
for these systems are for heating and transporting the noncondensible gas
(usually air) or to power the resistance heating.
Waste gases from which the organics are to be removed are often from
an oven or other heated source and are usually too hot for efficient
adsorption and must first be cooled. This is usually accomplished in a
heat exchanger with cooling water. The water requires pretreatment,
hence, some minimal energy expenditure will be required then also.
A blower is used to force the gas through the adsorption bed. The
amount of electricity consumed by the fan depends upon the exhaust gas rate
and the resistance of the bed (type and configuration of the carbon bed).
If a bed is to be regenerated by steam (which is to be subsequently
condensed) the adsorption system must provide for separation of the
organics from the condensate as part of either the organic recovery or
waste disposal system.
If a noncondensible gas is used for regeneration, the organics-1aden
regeneration gas can be incinerated directly or the organics can be separated
from the gas by condensation, or a second adsorber. Energy requirements
for an entire adsorption system are heavily dependent on the requirements
for final treatment.
3.3.5 VOC Removal Efficiency and Environmental Impacts of Adsorption
VOC removal efficiencies of more than 95 percent can be achieved by
carbon adsorption provided: (1) the adsorber is charged with an adequate
quantity of high-quality activated carbon, (2) the gas stream receives
appropriate preconditioning (e.g., cooling, filtering) before entering the
carbon bed, and (3) the carbon beds are regenerated before breakthrough.51
An adsorption system poses two potential secondary pollution problems,
disposal of both contaminated wastewater (steam condensate) and waste
carbon. If the carbon bed is regenerated with steam, and some of the
recovered organics are water soluable, then some separation is required to
3-50
-------
minimize contamination of the condensate wastewater. If the waste gas
stream contains particulates, they will plug the voids in the carbon bed,
rendering it ineffective. This can be avoided by precleaning the gas
feed stream, usually with a fabric filter, but perhaps with a small
sacrificial carbon bed. The ultimate disposal of spent adsorbent is an
environmental concern, but generally it will be returned to the manufacturer
at infrequent intervals for screening and regeneration at very high
(combustion) temperature in an inert atmosphere thereby rendering it suitable
for recycle back to an adsorber for further service. This greatly reduces
the rate at which carbon it must be transferred to a solid waste disposal
site or burned.
3-51
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3.4 ABSORPTION
Absorption is the process in which certain constituents of a gas stream
are selectively removed by a liquid solvent. Absorption may be purely
physical, in which the solute simply dissolves in the absorbent, or chemical,
in which the gases react with the liquid absorbent or with reagents
dissolved in the absorbent. The combined solvent and solute can then be
further processed by stripping or desorbing to remove the solute. The
recovered solvent is then available for reuse. In some cases the chemical
product may be returned to storage without separation as in the case of
hydrocarbon recovery of oil or gasoline.52
Low concentrations of organics in a waste gas stream will require long
contact times and large quantities of absorbent for effective removal
(emissions control). Absorption is therefore generally more expensive than
adsorption or incineration. Absorption can be an attractive pollution
control process if the absorbent is easily regenerated or the resulting
solution can be used as a make-up stream.
3.4.1 Equipment and Operating Principles
The desirability of an absorption process for use as an emission
control method depends on the ease with which organic vapors are removed by
a readily available absorbent. In general, absorption is most efficient
under the following conditions:53
1. the organic^ vapors are quite soluble in the absorbent,
2. the absorbent is relatively nonvolatile,
3. the absorbent is noncorroslve,
4. the absorbent is inexpensive and readily available,
5. the absorbent has low viscosity, and
6. the absorbent is nontoxic, nonflammable, chemically stable, and has
a low freezing point.
Absorption requires intimate mixing of the vapor-laden gas and the
liquid absorbent. A variety of absorption equipment has been designed to
achieve good contact between the gas and the absorbent. Different types of
3-52
-------
absorption equipment are packed towers, plate or tray towers, spray towers,
and venturi scrubbers. Schematics of this equipment are shown in Figures
3-11 to 3-14.54,55
Packed towers can achieve high rates of absorption. A packed tower is
a vertical cylinder filled with an irregularly-shaped packing material such
as shown in Figure 3-15.56 A liquid absorbent is introduced near the top
of the tower through a distribution system above the packing in an attempt
to assure wetting the entire packing surface. The absorbent flows by
gravity down through the tower countercurrent to the waste gas introduced
at the bottom of the tower. The concentration of the solute in the gas
stream decreases as the gas rises through the tower because the absorbate
is absorbed by the liquid absorbent as they contact in their countercurrent
flow through the packing material. The height of packing, required is a
function of the affinity of the absorbate for the absorbent.
Plate or tray towers provide contact between the waste gas and liquid
absorbent via a series of plates arranged in a step-like manner. Typically
the plates are designed to retain a layer of liquid on top of each plate
as the liquid spills down through the tower from plate to plate. The gas
is forced to bubble up through the liquid to achieve intimate mixing at
each plate. The bubbling is induced by holes in the plates through which
gases rise to the top of the tower. The number of required plates is
determined by the difficulty of the mass transfer operation and the desired
• degree of absorption.57
A spray tower is an empty chamber equipped with a series of nozzles
which spray liquid across the cross section of the vessel. The waste gas is
passed up through the sprays. The size of the spray droplets and their
distribution affects the efficiency by determining available surface area
for contact between two phases. One type of spray tower, a wash oil scrubber,'
can be used to control emissions from a storage tank in a by-product recovery
plant.58 Applications include light-oil and pure benzene storage tanks. The
emissions enter the bottom of the tower and contact a spray of wash oil that is
introduced into the top of the tower. Recent designs of wash-oil scrubbers
3-53
-------
,v CLEAN GAS OUT
SHELL-
TRAY-
DOWNSPOUT
TRAY SUPPORT
RING
TRAY STIFFENER
VAPOR RISER
FROTH
L
^-ABSORBENT IN
r -i 'r*V- y
-------
CLEAN GAS OUT
MIST ELIMINATORS
ABSORBENT IN
, .'LIQUID SPRAY V
. ' \ i i • I . V '
EXHAUST
GAS IN
ABSORBENT
Figure 3-13. Spray Tower
ABSORBENT IN
EXHAUST
GAS IN
NOZZLE
CLEAN GAS
OUT
SEPARATOR
ABSORBENT
Figure 3-14. Venturi Scrubber
3-55
-------
BERLSADDLE
RASCHIG RING
PALL RING
INTALOXSADDLE
TELLERETTE
Figure 3-15. Commonly Used Materials for Tower Packing
3-56
-------
accomplish contact by the use of single conical spray nozzles placed at two
or three elevations in the tower. Spray towers do not suffer from restrictions
to gas flow by accumulated residues commonly found in packed scrubbers.59
Unfortunately, spray towers have the least effective mass transfer capability
and thus, are generally limited to use for particulate removal and with
high-solubility gases.60
A venturi scrubber is sometimes used to develop intimate contact between
a liquid and a gas because of the unique properties of a venturi. The gas
phase is drawn into the throat of a venturi by a stream of absorbing liquid
sprayed into a convergent duct section. The effectiveness Increases with
increasing flow rate, as does the energy requirements. High gas velocities
increase the effectiveness of the collision between the gas and liquid streams.
Venturis have the advantage of obtaining a high degree of liquid-gas mixing,
but have the disadvantage of short contact times..Like spray towers, their
more common use is for particulate removal or absorption of high solubility
gases.
Due to the noted limitations of spray towers and venturi scrubbers,
VOC control by gas absorption is generally limited to packed or plate towers.
Packed columns are frequently used for handling corrosive materials, liquid
with foaming or plugging tendencies, or where excessive pressure drops
would result from use of plate columns. Packed columns are also less
expensive than plate columns. Plate columns are preferred for large-scale
operations where internal cooling is desired or where low liquid flow rates
would inadequately wet the packing.62
3.4.2 Applications
The suitability of gas absorption as a VOC emission control method is
generally dependent on the following factors:6-^
1. availability of a suitable solvent,
2. VOC removal efficiency required,
3. recovery value or terminal disposal cost of the VOC,
4. capacity required for handling vapors, and
5. VOC concentration in the inlet vapor.
3-57
-------
Gas absorption as an emission control method may use water as a solvent for
absorption of organic compounds that have high water solubility. Other
solvents such as mineral oil or nonvolatile hydrocarbon oils are used for
organic compounds that have low water solubility.®4 Absorption has been used
to control VOCs from surface coating operations, waste handling and treatment
plants, degreasing operations, asphalt batch plants, ceramic tile manufactu-
ring plants, coffee roasters, chromium plating units, petroleum coker units,
fish meal systems, smoke generators, and varnish and resin cookersAbsorp-
tion is attractive if a significant amount of VOC can be recovered and if the
recovered VOC can be reused. It is usually not considered when the VOC
concentration is below 200-300 ppmv.66
3.4.3 Absorption Costs
Absorption costs vary widely and depend on many factors.67 The
estimated costs presented in Figure 3-16 represent the total investment,
including all indirect costs such as engineering and contractors' fees and
overheads, required for the purchase and installation of all equipment and
materials. These are battery - limit costs. These costs are based on a
new installation; no retrofit cost considerations are included. Retrofit
is usually more costly. These costs apply to packed or tray columns in
which the solvent is used on a once-through basis (see Appendix B). The
annual cost is shown in Figure 3-17.
It is emphasized that these cost figures are for illustrative purposes
only. Each particular application of an absorption system will require an
engineering analysis of performance requirements and gas stream characteristics
before the costs can be estimated.For more specific costing information,
refer to Part XIII of the "Cost File" series published in Chemical Engineering
Magazine.70 Figures 3-16 and 3-17 are based on the parameters presented in
Table 3-6.
3.4.4 Absorption Energy Requirements
The energy required for an absorber will vary greatly depending upon
the type used. Energy is required for driving pumps and blowers, cooling
water (primarily on a condenser if a stripper'is used), and heat if regenera-
tion of the absorbent is desired.
3-58
-------
2SM
ISM
u
u fM
WASTE GAS FLOW RATE, tcfm
Figure 3-16. Installed Capital Cost vs Flow
Rate for Complete Absorption
System (No Stripper) With A
Solute-Solvent System
Operating at 99.0% VOC Removal
Efficiency
|zooo
1500
5 500
WASTE GAS FLOW RATE.iclm
Figure 3-17. Annual Cost vs Flow Rate
for Absorber Only (No
Stripper) With A Solute-
Solvent System Operating
At 99.0? VOC Removal
Efficiency
-------
TABLE 3-6. Components Of The Annualized Cost Of An Absorption Unit
SSSSSS3SSS3333S3SSSSSSSSS3 3 3S3SS3SSS3SSS33SSSSS3SSS333SSSSSSSSSSSSSSS53:
Gas Stream Characteristics
Flow Rate
Concentration
Equilibrium Curve Slope
Installed Capital Cost
10,000 scfm
0.5% (by weight) V0C
2.0
$518,000
Direct Operating Costs
Utilities
Process water ($0.33/1,000 gal.) $27,500
Electricity ($0.04/kWh) $63,000
Wastewater treatment ($0.33/1,000) $27,500
Maintenance, labor,and materials $34,000a
Operating labor ($20/hr) $17,500
Capital Charges $110,000b
Net Annualized Costs $279,500°
333333333S33383333333SI33333333333333333333333333S333335:sa
a Computed as 6.5 percent of installed capital cost.
b Calculated as 21 percent of installed capital cost. Based on 10 percent
interest for 10 years plus 5 percent for taxes, insurance, and administrative
charges.
c Computed as operating costs + capital charges. There is no V0C recovery
credit for air containing 0.5 wt. percent of V0C.
3-60
-------
Power requirements for pump operation are generally small compared to
requirements for the blower.Blower requirements are a function of
the quantity of gas which must be treated and the pressure drop of the
absorber. The energy required for a typical tower (plate or packed) as a
function of gas flow rate is shown in Figure 3-18.^
3.4.5 VOC Removal Efficiency
Many factors in the design and operation of an absorber affect its
performance, but two of the most important are solubility of the absorbate
in the absorbent and intimacy of mixing between the two phases caused by
the absorber.73 For example, two important factors influence the rate and
efficiency of benzene absorption in a wash-oil spray chamber. The first
factor is the amount of benzene vapor absorbed by the wash oil at equilibrium.
The second is the scrubber's contacting efficiency. One measure of this
efficiency is the number of equilibrium stages provided by the scrubber.
The contacting efficiency increases as the number of stages increases.
In theory, a properly designed and operated scrubber can provide a
benzene control efficiency of 95 percent or greater. The highest control
efficiency known to have been demonstrated so far is 90 percent.
3.4.6 Environmental Impact of an Absorption Process
Potential adverse environmental problems from an absorber include
processing or disposal of the organic-laden liquid effluent, loss of absorbent
to the atmosphere, and an increase for water use. The liquid effluent from
some absorbers can be used elsewhere in the process. When this is not
possible the absorbent effluent should be treated. Such treatment may include
a physical separation process (decanting or distilling) or a chemical
treating operation.
Sometimes regeneration may be accomplished by merely heating the
liquid effluent stream to reduce the solubility of the absorbed organics
and flash them from the absorbent. These concentrated organics can then be
condensed or burned. If burned, emissions of S0X, N0X, or incomplete oxidation
products of organics may result. The decision to burn will depend on the
nature of the regenerated gas stream.
3-61
-------
too
*
>
WASTE GAS FLOW RATE, ufm
Figure 3-18. Annual Energy Requirements vs Flcv: Rate for Absorber Only
(No Stripper) With A Solute-Solvent Systen Having An
Equilibrium Curve Slope of 2.0 and Operating at 99.0%
VOC Removal Efficiency.
3-62
-------
The control of one volatile organic compound can result in emissions
of another at an even greater rate when absorption is employed. For example,
vapors of trichloroethylene can be substantially reduced in an air stream
by absorption in a lean mineral oil; however,, at ambient temperature the
air stream leaving the absorber might contain some of the mineral oil.76
3.5 CONDENSATION
Condensation as an emission control method is often used in combination
with other air pollution control equipment. Condensers may be located
upstream of absorbers, carbon beds, or incinerators to reduce the VOC load
entering the more expensive control devices.77 A condenser can also be
used to remove components that might cause corrosion, adversely affect the
operation of downstream equipment, or to recover valuable components before
burning the waste gas stream. When used as the only control technique,
such as to limit emissions of gasoline vapor at bulk terminals, refrigeration
is often required to achieve the low temperatures necessary to cause
condensation.
3.5.1 Equipment and Operating Principles
In a vapor, condensation occurs when the partial pressure of a condensible
component is equal to its vapor pressure. This may be accomplished by
either increasing the pressure of the vapor, reducing the temperature of
the vapor, or a combination of the two.
The two most common types of condensers are surface and contact condensers.
Both operate at essentially constant pressure. The design of a surface
condenser does not permit contact between the coolant and either the vapors
or condensate. Condensation occurs on the walls that separate the two
fluids. A contact condenser encourages intimate mixing of the fluids.
Most surface condensers are shel1-and-tube heat exchangers like the
one in Figure 3-19.7® The coolant usually flows through the tubes and the
vapor condenses on the outside tube surface. The condensate forms a film
on the cool tube and gravity drains from the exchanger. Air-cooled condensers
may be used. These are constructed with tubes with external surface fins
through which air is blown. The vapor condenses inside the tubes.79
3-63
-------
COOLANT INLET VAPOR OUTLET VAPOR INLET
COOLANT OUTLET CONDENSED VOC
Figure 3-19. Schematic Diagram of a Shell-and-Tube Surface Condenser
» VAPOR OUTLET
//
WATER INLET
VAPOR INLET
DISTRIBUTION
TRAY
LIOUIO LEVEL
LIQUID OUTLET
Figure 3-20. Schematic Diagram of a Contact Condenser
3-64
-------
Vapors are cooled in contact condensers by spraying relatively cold
liquid directly into the gas stream. The coolant is often water, although
in some situations another coolant may be used. Most contact condensers
are simple spray chambers, like the one pictured in Figure 3-20.80
Contact condensers are, in general, less expensive, more flexible, and
more efficient in removing organic vapors than surface condensers. On the
other hand, surface condensers may recover marketable condensate and minimize
waste disposal problems. Often condensate from contact condensers cannot
be reused and may require significant wastewater treatment prior to disposal.
Surface condensers must be equipped with more auxiliary equipment and have
greater maintenance requirements.
Refrigerated brine vapor recovery systems require the following equipment
to produce the coolant for the vapor condenser: a refrigeration unit, a
heat exchanger/evaporator, storage for the chilled and defrost brines, and
a vapor condenser. To develop low temperatures, the refrigeration unit is
normally a compound system (temperatures to approximately - 100°F) or a
cascade multistage system (temperatures as low as - 250°F). Most petroleum
products require temperatures of approximately - 110°F, consequently,
cascade systems such as the one in Figure 3-21, are normally used.81 In
the cascade system, the condenser of one refrigeration stage acts as the
evaporator for the second stage to produce a lower temperature. Below 32°F,
moisture in the gas stream frosts and files the condensing surface. To
remove the ice, the condenser must be periodically defrosted. For a continuous
vapor recovery system, two condensers may be required, one condensing while
the second is defrosting.82
Refrigeration systems are particularly well suited for applications
for high value organics such as the recovery of hydrocarbon vapors from
gasoline marketing operations. Such systems are sold as packaged units
that contain all of the necessary piping, controls, and components. These
are usually skidmounted with weather enclosure.83 The size and cost of a
refrigerated vapor recovery unit will depend on the operational schedule,
process flow rate, load of VOC emissions, and the gas and liquid storage
capacities desired.
3-65
-------
VAPOR/AIR IN
AIR OUT
AIR COOLED
CONDENSER
AIR
EVAP/
CONO
COLD BRINE
RESERVOIR
2ml STAGE
EVAPORATOR
fend STAGE|
COMPRESSOR
(1st STAGE) L
COMPRESSOR
DEFROST
BRINE
RESERVOIR
RECLAIM HEAT
> VAPOR
CONDENSER,
FROM REFRIGERATION
COMPRESSORS
CONDENSED
WATER VAPOR
CONDENSED ORGANIC
Figure 3-21. Cascade Refrigeration System for Vapor Recovery
-------
A condensation system using a nitrogen-blanketed drying oven and a
nitrogen-cooled heat exchanger is one type of system that has been used to
recover VOC emissions from drying ovens at polymeric coating plants.
Figure 3-22 presents a flow diagram of this condensation system. Nitrogen
is used in the drying oven to permit operation with high solvent vapor
concentrations without the danger of explosion. The nitrogen recycled through
the oven is monftored and operated to maintain solvent vapor concentrations
of 10 to 30 percent by volume. Solvents are recovered by sending a bleed
stream of approximately 1 percent of the recycle flow through a shel1-and-tube
condenser. The liquid nitrogen is on the tube side, and the solvent-laden
nitrogen passes over the outside of the tube surfaces. Vapors condense and
drain into a collection tank. The nitrogen that vaporizes in the heat exchanger
is recycled to the drying oven.84
A system now available from the Linde Division of Union Carbide Corporation
uses liquid nitrogen to condense and recover vapors. Many plants presently
use nitrogen at ambient temperature to blanket liquid-storage facilities
for safety or purity purposes. The nitrogen is delivered and stored as a
liquid and vaporized before use. Typically, the cooling potential of the
liquid nitrogen is presently wasted. The Linde system uses the Joule-Thompson
effect of the liquid nitrogen (en route to its being warmed to ambient
temperature for use in blanketing) as a refrigerant for a condenser. At
sites where the cryogen is already being used, such cooling is available at
little or no additional cost. Even in cases where liquid nitrogen is not
presently stored this condensation system may still be economical.85
3.5.2 Applications
Refrigerated condensers are being used for recovery of gasoline vapors
at bulk gasoline terminals. The suitability of condensation for VOC emissions
control is generally dependent on the following: VOC concentration in the
inlet; the VOC removal efficiency required; the value of the recovered VOC;
and the cost of the condenser required to handle the gas flow rate.86
A refrigerated condenser system may be used independently or in combination
with another process. To recover organic vapors from transfer operations
at gasoline terminals and bulk plants, refrigeration can be used to condense
3-67
-------
ORV NITROGEN CAS
RECYCLED GASES
Ufa
VOC EMISSIONS
HEATER
SOLVENT
STORAGE
LIQUIO
MEAT EXCHANGER
WITH LIQUID N2
COOLANT
DRYING OVEN WITH INERT ATMOSPHERE
INERTING CURTAIN INERTING CURTAIN
Figure 3-22. Schematic of Condensation System IJsinq Nitronen
-------
the vapors at essentially atmospheric pressure or by compressing the vapors,
requiring less refrigeration.8? A primary condenser system is an integral
part of any distillation operation. These condensers provide reflux for
the fractionating columns. A secondary condenser may be used to remove
even more VOC from the "noncondensible" vent stream which exits the primary
condenser.88
Condensers have been used successfully (but usually in conjunction
with other control equipment) in reducing organic emissions from petroleum
refining, petrochemical manufacturing, asphalt manufacturing, coal tar
dipping operations, degreasing operations, dry cleaning units, and sometimes
the surface coating industry.8^
3.5.3 Condensation Costs
The cost of a shel1-and-tube surface condenser depends on the following:^
1. the nature and concentrations of the vapors in the waste gas,
2. the mean temperature difference between gas and coolant,
3. the nature of the coolant,
4. the desired degree of condensate subcooling,
5. the presence of noncondensible gases in the waste gas, and
6. the buildup of particulate matter on heat exchanger surfaces.
Using the above factors and standardized heat exchanger equations, the
requisite contact area may be calculated from which the cost may be estimated.
Generally, the capital cost for a surface condenser will be greater than for
a contact condenser, although selection of a contact condenser will usually
necessitate additional capital for treatment of the coolant effluent.
Annual and capital costs for refrigerated vapor recovery units for use
at bulk gasoline terminals have been published by the EPA in a document on
control of air pollution from the gasoline marketing industry.91 These cost
estimates are shown in Figures 3-23 and 3-24. All costs are indexed to
second quarter 1984 dollars (see Appendix B). A negative annual cost
indicates the profit associated with the control scheme.
The capital cost represents the total investment required to purchase
and install a refrigeration unit. ' While the cost for installation at
an existing facility may be slightly more than for a new one, the costs
3-69
-------
3M
m
~ 320
3M
o
u
<2N
u
•I i i i i I
6 20 40 00 00 100
CAS FLOW TO CONDENSER, tdm
Fiqure 3-23. Installed Capital Cost
vs Gas Flow Rate To A
Condenser For A Refri-
nerated Vapor Recovery
Uni t'
3 40
H 120-
-100
200
IN
20
40
00
SAS FLOW TO CONDENSER, sdm
Fiqure 3-21. Annual Cost vs Flow Rate
To A Condenser For A
Refrioeration Vapor Recovery
Uni t
-------
presented here are intended to represent the more expensive case. For a
more detailed discussion of cost information, refer to Part XVI of the
"Cost File" series published in Chemical Engineering Magazine.^
Some components of the annualized cost of operating a refrigerated
vapor recovery unit are shown in Table 3-7. Utilities costs will depend on
the inlet concentration of the organic; high recovery of gasoline can yield
an annual savings. The increased price of gasoline over the past few years
has made refrigerated condensers more profitable where high concentration
of the valuable organic can be recovered.
TABLE'3-7 Components Of Annualized Costs For A Refrigeration Vapor Recovery Unit
Gas Stream Flow Rate 23.3 scfm (.66 m^ j
Installed Capital Cost $280,000
Direct Operating Costs:
Utilities $23,000a
Maintenance 7,000b
Operating Labor 5,500
Capital Charges 59,500c
Gasoline Recovery (Credit) ($75,000)d
Net Annualized Costs $20,000e
mm
a Electricity 9 $0.04/kWh.
b Maintenance as 2.5 percent of the capital cost.
c Calculated at 10 percent for 10 years plus 5 percent for taxes,
insurance, and administrative costs.
d Gasoline valued at a wholesale price $0.31 per liter F.O.B. terminal before tax.
e Computed as operating cost + capital charges - gasoline recovery credits.
3-71
-------
3.5.4 Energy Requirements for a Refrigerated Condenser
The refrigeration unit (that provides coolant to the condenser) and
the pumps require electrical power. The amount, of course, is determined
by the amount of refrigeration needed and the coolant temperatures required.
The power required for a blower will be roughly proportional to the gas
flow rate through the system and will therefore vary with the concentration
and removal efficiencies selected.93
A contact condenser requires energy to chill the cold liquid, power the
injection pumps, and the blower that moves the gas through the condensation
zone. A surface condenser requires energy for a cooling water system or
forced convection air cooler.94
Figure 3-25 shows the energy requirements for a refrigerated condenser
system used to recover gasoline vapors at a bulk terminal as a function of
vapor flow rates.95 These costs are based on the electrical power required
by the refrigeration unit.
3.5.5 VOC Removal Efficiency
Condensers are operated at efficiencies between 50 and 95 percent.96 Where
solvent contamination is low and organic vapor concentration is relatively high,
recovery efficiencies are reported greater than 96 percent. In cases where
ambient air is mixed with the vapor and some contamination is present,
efficiencies of about 90 percent are reported.97
For gasoline vapor recovery, refrigeration units have the capacity of
recovering more than 90 percent of the organics when tne gas entering the
condenser consists of 35 percent gasoline vapors by volume. Refrigeration units
will recover 70 percent of the organics when the gas entering the condenser
consists of 15 percent gasoline vapor by volume.98
3.5.6 Environwental Impact of Condensers
Secondary environmental problems created by condensers include contamination
of: (1) non-condensibles from surface condensers and refrigeration systems
and (2) the liquid effluent from a contact condenser.
The non-condensible effluent from a surface condenser may be vented to
the atmosphere or further processed (e.g., via incineration), depending on
its composition. Since the coolant never contacts the condensate in a surface
3-72
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2.8
2.6
in
t-
E 2.2 -
2 2.0
s 1.8
.1 i i i i I
0 20 40 60 SO 100
GAS FLOW TO CONDENSER, scfm
Figure 3-25. Annual Energy Requirement vs Gas Flow Rate To A
Condenser For A Refrigeration Condenser (Gasoline
Vapor Recovery System At A Bulk Terminal)
3-73
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condenser, the recovered organic compounds are not contaminated and are usually
reusable. It might not be economical to recover the condensate if more than
one organic compound is present and their separation is costly. In such a
case, proper treatment of the condensate is imperative before final disposal.
This is also true of volatile organics recovered by a refrigerated condenser.
The condensate from a contact condenser is contaminated with the coolant
liquid. The usual procedure is treatment of the waste stream to remove the
organics and subsequent disposal. The amount of organic material entrained
in the exiting wastewater will depend on the extent of treatment.^
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3.6 OTHER CONTROL METHODS
3.6.1 Changes to the Process or Its Raw Materials
The control "option" most difficult to discuss is the variety of
changes that can be made to a process or its raw materials which can reduce
the emission rate.
A process change can be a very simple and often inexpensive measure
such as closing an open vessel or trough from which solvents evaporate. It
can also be more complicated such as replacement of open printing technology,
reportedly not only reduces fugitive emissions from the Ink fountain, but
also permits much more precise control of the ink delivered to the substrate.
It is reported that this has improved the quality of the print and reduced
ink consumption thereby invoking both value to the printer and environmental
benefits.
Other process changes with environmental benefits include installation
of equipment to reduce breathing losses (from storage tanks that contain
volatile organics) or replacement of steam jet ejectors with vacuum pumps
thereby reducing the volume of exhaust gases and rendering abatement control
less expensive. Another common change now being made in spray painting
operations is the installation of new, more efficient spray techniques. As
a result there is less waste, fewer emissions and resulting economies to
the plant owner because of decreased paint costs. In addition to the
efficiencies offered by electrostatic spraying techniques, many firms are
installing robots to manage the spray equipment. Additional efficiencies
are obtained because of the absolute repetitiveness offered by a robot.
Waste motion and spray can be eliminated, ultimately resulting in even
greater reductions of waste coatings and their VOC. The possibilities are
endless and require an innovative analysis of the production process under
scrutiny to determine the possibilities for improvement. One of the simplest
changes to undertake, improvements in housekeeping and maintenance procedures,
can have a dramatic effect on reducing emissions.
3-75
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Routine inspections of pumps, valves, flanges and other fittings will allow
more speedy identification of vapor and liquid losses. Rapid repair will
minimize emissions and maximize product yield.
Changes in raw materials are much easier to conceptualize, but sometimes
difficult to accomplish. One of the more noted successes of the last few
years has been the change to hot melt adhesives to replace many of the
solvent based materials previously applied by gravure rolls. Another change
is the trend in many coating industries to convert to the use of low solvent
paints and inks. Powder coatings, waterborne coatings, higher solids
coatings'are increasing their market share. All three products are replacing
traditional coatings with solvent emtssions several-fold greater.
Some raw material changes essentially eliminate organic emissions. An
increasingly common example has been the transition to powder coatings.
Powder coatings require no solvent and are applied as a dry powder. Sprayed
electrostatically, the paint adheres to the substrate. When subsequently
heated in an oven, the powder first melts and flows to gather to form a
uniform film, then reacts to hardent into an esthetically pleasing and
protective coating.
Other essentially zero emission raw materials include inks and coatings
that are cured by ultraviolet or electron beam radiation. These liquid
monomeric materials, which contain little or no solvent, react when the
polymeric reaction is Initiated by radiation.
3.6.2 Replacement of Organic Materials with Others Which are Less
Photochemically Reactive
This technique of- emission reduction was a major facet of the Los
Angeles A1 r Pollution Control District's Rule 66 (now, "South Coast Air
Quality Management District Rule 442") in force in the mid-60's. The use
of so-called exempt solvents began to fade in 1977 when EPA published its
Recommended Policy on Control of Volatile Organic Compounds (July 8, 1977,
Federal Register, page 35314). That policy allowed continued use of Rule
66 type regulations by states during some interim transitional period as
new regulations were developed to obtain real emission reductions.
3-76
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The policy announced that research subsequent to enactment of the Los
Angeles Rule had determined that essentially all organic compounds react
photochemically to form ozone. The Los Angeles Rule was based on the
photochemical reactivity of organics during experimental tests for a few
hours (generally one "solar day" of about six (6) hours). When the "low
photochemcially reactive" compounds identified by this test were exposed to
photolysis for longer periods, they too reacted to form ozone. Rule 66,
then, perhaps had successfully aided the Los Angeles Valley in ameliorating
smog levels only at the expense of higher levels downwind.
This information led to EPA's policy that is founded on the nationwide
transport phenomena of air pollutants. It makes little sense to permit
substitution of slow (low photochemical reactivity) reacting organics for
faster reacting ones if the result is transport of one metropolitan area's
smog problem downwind to another place. EPA's policy declared essentially
all organics reactive. The policy declared some exceptions, predominantly
halogenated organics, which have negligible photochemical reactivity.
Accompanying this declaration was a caution that although these materials
do not react to produce ozone, some were suspected of being toxic and any
decision to use them should consider such other environmental aspects. The
cloud of uncertainty over some of these halogenated solvents has not yet
cleared completely. In October 1984, the EPA published a final rule for
manufacturers and processors of 1,1,1 trichloroethane that requires testing
for "teratorgenic effects or, more appropriately, developmentally toxic
effects." The caution in the 1977 policy statement to evaluate other
potentially damaging environmental effects of halogenated solvents before
substituting them for photochemically reactive ones seems no less important
today than then.
3-77
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3.7 REFERENCES
1. Glossary for Air Pollution Control of Industrial Coating Operations.
2nd ed., EPA-450/3-83-013R, Dec. 1983.
2. Polymeric Coating of Supporting Substrates - Background Information
for Development of New Source Performance Standards, Draft Report,
EPA Contract No. 68-02-3817, October 1985, pages 4-3—10.
3. Industrial Venti1ation, 18th ed., American Conference of Government
Industial Hygienists, Cincinnati, 1984,
4. "Determining the Efficiency of a Vapor Containment or Capture System
as One Element of a Compliance Determination." Paper presented at
the 79th Annual Meeting and Exhibition of the Air Pollution Control
Association, Minneapolis, Minnesota, June 22-27, 1986.
5. Reed, R. J. North American Combustion Handbook. North American
• Manufacturing Company, Cleveland, Ohio. 1979. p. 269.
6. Memo and attachments from Farmer, J.R., EPA, to distribution.
August 22, 1980. 29 p. Thermal incinerator performance for NSPS.
7. Reference 6.
8. Reference 6.
9. U.S. Environmental Protection Agency. Control of Volatile Organic
Compound Emissions from Air Oxidation Processes in Synthetic Organic
Chemical Manufacturing Industry - Guideline Series. Research Triangle
Park, NC. Publication No. EPA-450/3-84-015. December 1984.
10. Chemical Manufacturing, Volume 4: Combustion Control Devices.
Research Triangle Park, N.C. Publication No. EPA-450/3-30-026.
December 1980. Reports 1 and 2.
11. Reference 9. p. 5-19.
12. Reference 9. p. 5-19.
13. U.S. Environmental Protection Agency. Reactor Processes in
Synthetic Organic Chemical Manufacturing Industry - Background Information
for Proposed Standards. (Preliminary Draft) Research Triangle Park, N.C.
September 1984.
14. Reference 13. p. 8-4.
15. Reference 13. p. V-43.
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16. U. S. Environmental Protection Agency. Air Oxidation Processes in
Synthetic Organic Chemical Manufacturing Industry - Background
Information for Proposed Standards. Research Triangle Park, N.C.
Publication No. EPA-450/3-82-001a. January 1982. P. C-22.
17. Reference 13. p. 7-9.
18. Key. J. A. (I. T. Environscience.) Control Device Evaluation Catalytic
Oxidation. In: U. S. Environmental Protection Agency. Organic
Chemical Manufacturing, Volume 4: Combustion Control Devices.
Research Triangle Park, N.C. Publication No. EPA-450/3-80-026.
December 1980. Report 3.
19. Reference 18.
20. Reference 18.
21. Reference 18.
22. U. S. Environmental Protection Agency. Background Information Document
for Industrial Boilers. Research Triangle Park, N.C., Publication
No. EPA-450/3-82-006a. March 25, 1982. p. 3-27.
23. U.S. Environmental Protection Agency. A Technical Overview of the
Concept of Disposing of Hazardous Wastes in Industrial Boilers (Draft).
Cincinnati, Ohio. EPA Contract No. 68-03-2567. October 1982. p. 73.
24. Reference 13. p. 4-28.
25. U. S. Environmental Protection Agency. Emission Test Report. USS
Chemicals (Houston, Texas). Research Triangle Park, N.C., EMB
Report No. 80-0CM-19. August 1980.
26. U. S. Environmental Protection Agency. Distillation Operations
in Synthetic Organic Chemical Manufacturing - Background Information
for Proposed Standards. (Final E1S) Research Triangle Park,
N.C., Publication No. EPA-450/3-83-005a.
27. Reference 26 p. 8-15.
28. Memo from Keller, L.E., Radian Corporation, to File. October 31, 1983.
2 pgs. N0X Emissions from Gas-Fired Heaters.
29. Reference 13 p. 4-15.
30. Klett, M.G. and J. B. Galeski. (Lockhead Missiles and Space Co.,
Inc.) Flare Systems Study. (Prepared for U.S. Environmental Protection
Agency.) Huntsville, Alabama. Publication No. EPA-600/2-76-079.
March 1976.
31. Federal Register 51 FR 2699.
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32. Joseph, D., J. Lee, C. McKinnon, R. Payne and J. Pohl, "Evaluation
of the Efficiency of Industrial Flares: Background - Experimental
Design - Facility," EPA Report No. 600/2-83-070, August 1983.
33. Reference 13.
34. Kalcevic, V. (I.T. Enviroscience.) Control Device Evaluation Flares
and the Use of Emissions as Fuels. In: U.S. Environmental Protection
Agency. Organic Chemical Manufacturing Volume 4: Combustion Control
Devices. Research Triangle Park, N.C. Publication No. EPA-450/3-80-026.
December 1980. Report 4.
35. Reference 13. p. 8-20.
36. Reference 13. p. 8-20.
37. McDaniel, M., Engineering Science. Flare Efficiency Study, Prepared,
for U. S. Environmental Protection Agency. Washington, D.C. Publication
No. EPA-600/2-83-052. July 1983. 134 p.
38. Parmele, C. S., O'Connell, W. I., and Basdekis, H. S. "Vapor-
phase adsorption cuts pollution, recovers solvents," Chemical Engineering,
December 31, 1979.
39. Crane, G. B. Carbon Adsorption for V0C Control, U. S.
Environmental Protection Agency, Research Triangle Park, North Carolina,
January 1982.
40. Organic Chemical Manufacturing, Volume 5: Adsorption, Condensation
and Adsorption Devices, EPA-450/3-80-027, U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina, December, 1980.
41. Kenson, R.E., "KPR System for VOC Emission Control from Paint
Spray Booths," Paper presented at Air Pollution Control Association
Annual Meeting, June 1985, Detroit, Michigan.
42. Hobbs, F. D., Parmele, C. H., and Barton, D. A. Survey of
Industrial Applications of Vapor-Phase Activated Carbon Adsorption for
Control of Pollutant Compounds from Manufacture of Organic Compounds.
EPA-600/2-83-035, U. S. Environmental Protection Agency, Research Triangle
Park, North Carolina, April 1983.
43. MSA Research Corporation. Package Sorption Device System Study.
Evans City, Pennsylvania. EPA-R2-73-202. April 1973. Chapters 4 and 6.
44. Neverll, R. B., Capital and Operating Costs of Selected Air
Pollution Control Systems, EPA 450/5-80-002, U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina, December 1978.
45. "Industrial Ventilation" 10th Edition, American Conference of
Governmental Industrial Hygienist.
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46. Shaw, N. R., "Carbon Absorption/Emission Control Benefits and Limitations,"
Paper presented at symposium on Volatile Organic Compound Control in
Surface Coating Industries, April 25-26, 1979, Chicago, IL.
47. Reference 44.
48. Memo from Banker, L., MRI to Crumpler, D., EPA. Draft Tabular
Costs, Polymeric Coating of Supporting Substrates, September 12, 1984.
49. Control of Volatile Organic Emissions from Existing Stationary
Sources, Volume 1: Control Methods for Surface-Coating Operations, U. S.
Environmental Protection Agency. Research Triangle Park, North Carolina.
EPA-450/2-76-028. November 1976. pp. 17-79, 88-94, 98-127.
50. MSA Research Corporation. Hydrocarbon Pollutant Systems Study,
Volume 2. PB-219 074. 1973. Appendix C.
51. Crane, G.B., Carbon Adsorption for VOC Control, U.S. Environmental
Protection Agency, Chemicals and Petroleum Branch, January 1982.
52. Reference 44.
53-54. Treybal, R. E., Mass Transfer Operations. New York. McGraw-Hill
Book Co., 1980. pp. 139-211, 281-282.
55. "Control Techniques of Volatile Organic Emissions from Stationary
Sources." EPA-450/2-78-022. Office of Air Quality Planning and Standards,
U. S. Environmental Protection Agency, May 1978.
56. "Organic Chemical Manufacturing Volune 5: Adsorption, Condensation,
and Absorption Devices." EPA-450/3-80-027. Office of Air Quality Planning
and Standards, U. S..Environmental Protection Agency, December 1980.
57. "Synthetic Fiber Production Facilities - Background Information for
Proposed Standards," Draft EIS. EPA-450/3-82-011a. Office of Air Quality
Planning and Standards, U. S. Environmental Protection Agency, October 1983.
58-59. "Benzene Emissions from Coke By-Product Recovery Plants Background
Information for Proposed Standards," Draft EIS. EPA-450/3-83-016a.
Office of Air Quality Planning and Standards, U. S. Environmental Protection
Agency, May 1984.
60. "Distillation Operations in Synthetic Organic Chemical Manufacturing
Background Information for Proposed Standards," Draft EIS. EPA-450/3-83-
005a. Office of Air Quality Planning and Standards, U. S. Environmental
Protection Agency, December 1983.
61. Reference 57.
62. Reference 60.
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63-64. Reference 56.
65. Reference 55.
66. Reference 60.
67. Reference 55.
68-69. Reference 56.
70. Vatavuk, William M. and Robert Neveril, "Part XIII: Costs of Gas
Absorbers". Chemical Engineering, October 4, 1982. pp 135-136.
71-72. Reference 56.
73-75. Reference 58.
76. Surprent, K.S. and O.W. Richards of Dow Chemical Company, "Study
to Support New Source Performance Standards for Solvent Metal Cleaning
Operations," 2 vol., prepared for the Emission Standards and Engineering
Division (ESED). Contract No. 68-02-1329, Task Order No. 9, June 30, 1976.
77. Reference 55.
78. Davidson, J.H., Air Pollution Engineering Manual, 2nd ed. Air
Pollution Control District, County or Los Angeles.
79. Reference 55.
80. Reference 53.
81-82. Reference 44.
83. "Control of Volatile Organic Compound Emissions from Volatile Organic
Liquid Storage in Floating and Fixed Roof Tanks." EPA-450/3-84-005.
Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, June 1984.
84. "Polymeric Coating of Supporting Substrates—Background Information
for Proposed Standards," Draft EIS, U.S. Environmental Protection
Agency, Office of Air Quality Planning and Standards, October 1985.
85. "System Uses Nitrogen to Cut Emissions", Union Carbide Corp., Linde
Division. Chemical Engineering, May 28, 1984. pp. 53-55.
86. Reference 56.
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87. Reference 44.
88. Reference 60.
89-90. Reference 55.
91. "Evaluation of Air Pollution Regulatory Strategies for Gasoline
Marketing Industry." EPA-450/3-84-012a. Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency,
July 1984.
92. Vatavuk, William M. and Robert Neveril, "Part XVI: Costs of Refriger-
ation Systems." Chemical Engineering, May 15, 1983. pp. 95-98.
93. Reference 56.
94. Reference 55.
95. Reference 86.
96. Reference 60.
97. Reference 57.
98. Reference 44.
99. Reference 50.
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4.0 CONTROL TECHNIQUES APPLICABLE TO SOURCE CATEGORIES
This chapter provides a brief description of the emission rates and
control technology for the major volatile organic compound (VOC) emission
source categories. For each source category the following are described:
A. Process and Facility Description
B. Emission Sources and Factors
C. Control Techniques and Emission Reductions
D. Regulatory Status
E. Current National Emission Estimate
F. Capital and Annual Control Costs
G. References
This chapter relies heavily on the reference material developed
under the present EPA emission control programs - NESHAP, NSPS and CTG
documents. The reference docisnents should be reviewed to obtain a complete
understanding of the subject matter. This chapter also provides the
source of the national VOC emission estimates presented in Chapters 1 and
2.
All control costs (unless otherwise noted) have been updated to
second quarter or May 1984 dollars to provide a rough estimate of cost in
current dollars for comparing control costs with other source categories.
The method for updating costs is presented in Appendix B.
4-1
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4.1 PETROLEUM REFINERIES
4.1.1 Petroleum Refinery Equipment Leaks
A. Process and Facility Description
Petroleum refineries are facilities engaged in the production of gasoline,
aromatics, kerosene, distillate fuel oils, residual fuel oils, and other
products through the distillation of petroleum, or through the redistillation,
cracking, rearrangement, or reforming of unfinished petroleum derivatives.
Refineries are comprised of one or more processing units (equipment assembled
to produce intermediate or final products). There are approximately 220
petroleum refineries operating in the United States (as of January 1, 1984),
with a total crude capacity of about 2,522,000 m^/calendar day (15,862,883
bb1/ calendar day).1
B. Emission Sources and Factors
Emissions of VOC from refineries can result when process fluids (either
gaseous or liquid) leak from plant equipment. Potential leaking equipment
include: pumps, compressors, valves, pressure relief devices, open-ended
lines, sampling systems and flanges and other connectors. Emission factors for
process equipment have been developed based on the results of several source
testing studies. Emissions from petroleum refinery processing units can be
estimated by multiplying emission factors for specific types of equipment by
the number of equipment pieces in the process units. Refinery process unit
emissions may range from about 80 to 5U0 Mg/yr (88 to 550 tons/yr) in the
absence of regulatory controls. Emissions of VOC from a hypothetical refinery
with 10 process units would be approximately 2,360 Mg/yr (2,60u tons/yr).
Emissions from petroleum refinery equipment leaks are discussed in the background
information documents for the proposed and promulgated new source performance
standards (NSPS) for petroleum refinery fugitive emissions.2,3
C. Control Techniques and Emission Reductions
Two approaches are available to control refinery equipment leaks of VOC:
(1) a leak detection and repair program and (2) the installation of specific
controls or leakless equipment. The emission reduction efficiency of leak
4-2
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detection and repair programs is dependent upon a number of factors including:
(1) the monitoring method (visual, instrument, or soap solution); (2) leak
definition; (3) frequency of inspections; (4) the time interval allowed between
leak detection and subsequent leak repair; and (5) the emission reduction
achieved by each successful repair. Leak detection and repair program control
efficiencies are presented in Table 4.1.1-1.4 The control estimates are based
on available data on the occurrence and recurrence of leaking equipment and on
the effectiveness of leak repair that are used in a model program that predicts
control effectiveness using recursive equations developed for evaluating leak
detection and repair programs. Control equipment can achieve control efficiencies
approaching 100 percent. Examples of equipment controls include (1) venting
emissions from pressure relief devices, pumps, and compressors to a control
device (e.g., flare or process heater); (2) dual mechanical seals with barrier
fluid systems for pumps and compressors; (3) caps, plugs, or second valves on
openended lines; (4) closed purge sampling systems; and (5) sealed bellows
valves.
TABLE 4.1.1-1. EMISSION FACTORS AND CONTROL EFFECTIVENESS3
Control led
Emissions
Quarterly Monitoring
Monthly Monitoring
Average
Equi pment
Emi ssi on
Emissien Percent
Emission Percent
Type/Service
Factor,
Factor, Reduction
Factor, Reduction
kg/hr
kg/hr
kg/hr
Valves -
Ga s
0.64
0.262
59.7
0.192
70.3
Light Liquid
0.26
0.098
62.7
0.072
72.5
Pumps - Light Liquid
2.7
0.78
70.9
0.45
83.3
Pressure Relief
Devices - Gas
3.9
2.18
44
1.8
53
Reference 2. Appendix F.
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D. Regulatory Status
The EPA Issued a CTG in June 1978 and set NSPS on May 30, 1984, (40 CFR 60
Subpart GGG) to control equipment leaks (fugitive emissions) of VOC in petroleum
refineries. The CTG recommends quarterly leak detection and repair for valves,
pressure relief devices, and compressors in gas/vapor service and annual leak
detection and repair for pumps and valves in light liquid service. Pumps also
would receive weekly visual inspections. The CTG additionally recommends that
caps be installed on open-ended lines. The NSPS requires monthly leak detection
for valves in gas/vapor and light liquid service and pumps in light liquid
service. Pressure relief devices are subject to a no detectable emissions
limit, compressors are to be equipped with a barrier fluid seal system that
prevents leakage of VOC to atmosphere, sampling lines require closed purge
systems, and caps be installed on open-ended lines. About 120 refineries (56
percent) are estimated to have implemented controls recommended by the CTG as
required under State or local regulations.! By the end of 1984, 38 refinery
process units are projected to be subject to the NSPS.^
E. Current National Emission Estimates
Total annual VOC emissions from petroleum refinery equipment leaks in 1984
has been estimated at 370,000 megagrams based on 1984 levels of control.3'5
This estimate was derived by multiplying the total estimated number of refinery
process units by process unit emission estimates. The nationwide emissions
estimate assumes that 56 percent of the refineries are in nonattainment areas.7
F. Capital and Annual Control Costs
Capital and annual costs for controlling refinery equipment leaks are
presented in Table 4.1.1-2 for a small and large process unit. These costs
are estimated based upon control costs for individual equipment type multiplied
by the number of each type of equipment in the process unit. The costs presented
also include expenditures incurred for monitoring instruments.7 A typical
uncontrolled petroleum refinery (10 process units) would incur a capital cost
of $161,000 and annual cost savings of $54,500 to comply with State and local
regulations to control equipment leaks of VOC. The same refinery would incur
about $1.2 million in capital costs and $140,000 in annual costs to comply with
the NSPS requirements.7
4-4
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TABLE 4.1.1-2. CAPITAL AND ANNUAL COSTS TO
CONTROL REFINERY EQUIPMENT LEAKS3
Costs ($1,000)
CTG
NSPS
Capital Cost
Small Unitb
4.7
43.6
Large Unit
27.2
237
Annual Cost
Small Unit
(1.9)
3.7
Large Unit
(4.1)
25.7
Parentheses denote cost savings.
aReference 7.
bA small and large unit correspond to Model Units A and C, .
respectively, from Reference 2.
G. References
1. Annual refinery survey. The 011 and Gas Journal. Volume-82, Number
13. March 26, 1984. p. 112.
2. VOC Fugitive Emissions in Petroleum Refining Industry Background
Information for Proposed Standards. U.S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research Triangle Park,
North Carolina. EPA-450/3-81-015a. November 1982.
3. Petroleum Fugitive Emissions - Background Information for Promulgated
Standards. U.S. Environmental Protection Agency. Office of Air Quality
Planning an
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4.1.2 Petroleuro Refining Vacuum Producing Systems
A. Process and Facility Description
Vacuum distillation columns can be a significant source of VOC from
petroleum refineries. Vacuum is created within the vacuum distillation
column by removal of non-condensible gases and process steam by steam jet
ejectors or mechanical vacuum pumps. A steam nozzle in a jet ejector discharges
a jet of high velocity steam across a suction chamber that is connected to
the piece of equipment in which the vacuum is to be maintained. Mechanical
vacuum pumps, although less popular than steam jet ejectors, are more energy
efficient and produce a stream consisting almost entirely of hydrocarbons.
The exiting steam (for steam jet ejectors) and any entrained vapors are
condensed by direct water quench in a barometric condenser or by a surface
condenser. In 1984 there were 165 refineries operating vacuum distillation
units with a combined vacuum distillation charge capacity of 1,115,000 m^/stream
day (7,015,590 barrels/stream day).1
B. Emission Sources and Factors
All vacuum producing systems discharge a stream of non-condensible VOC
while generating the vacuum. Steam ejectors with contact condensers also
have potential VOC emissions from their hotwells. VOC emissions from vacuum
producing systems that vent non-condensible hydrocarbons to atmosphere are
estimated to be 145 kg/1,000 m^ (51 lb/ 1,000 bbl) of refinery throughput.2
C. Control Techniques and Emission Reductions
VOC emissions from vacuum producing systems can be prevented by
piping the non-condensible vapors to a control device (e.g., flare, incinerator)
or compressing the vapors and adding them to refinery fuel gas. The hotwells
associated with contact condensers can be covered and the vapors incinerated.
Controllrng vacuum producing systems in this manner will result in negligible
emissions of hydrocarbons from this source.
D. Regulatory Status
The EPA issued a CTG in October 1977 recommending that refineries control
vacuum producing system emissions by piping non-condensible vapors to a
control device. It is estimated that 56 percent (123) of the existing petroleum
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refineries have controlled vacuum producing system emissions as required
under State regulations.1»3
E. Current National Emission Estimates
Emissions of VOC from petroleum refinery vacuum producing systems in 1984
have been estimated at 44,000 Mg/year (48,500 tons/year).1-5 The nationwide
emissions were estimated by multiplying the throughputbased emission factor by
the nations' vacuum distillation charge capacity, and by an industry-wide
utilization rate.
F. Capital and Annual Control Costs
For a typical 15,900 m3 (100,000 bbl) per day throughput refinery, capital
costs for piping vacuum producing system non-condensible hydrocarbons from
surface condensers or mechanical vacuum pumps are estimated at $36,500.
Capital costs for controlling emissions from contact (barometric) condensers
and covering their hotwell areS are estimated at $79,500. Recovering vapor
producing system emissions would result in a net annualized cost savings
estimated in excess of $100,000 per year.2,5
G. References
1. Annual Refining Report., Oi 1 and Gas Journal, Volume 82, Number 13,
March 26, 1984.
2. Guideline Series - Control of Refinery Vacuum Producing Systems,
Wastewater Separators, and Process Unit Turnarounds, U.S. Environmental
Protection Agency, EPA-450/2-77-025, October 1977.
3. Overview Survey of Status of Refineries in the U.S. with RACT
Requirements, U.S. EPA Contract No. 68-01-4147, Task No. 65 and 74, October
1979.
4. Outlook: U.S. petroleum product usage, Hydrocarbon Processing,
Volume 63, No. 11, November 1984.
5. Memorandum, Rhoads, T., Pacific Environmental Services, Inc., to S.
Shedd, U.S. EPA, Derivation of Cost Emissions, and Emission Reductions presented
in the VOC Control Techniques Document. November 1985.
4-7
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4.1.3 Petroleum Refinery Process Unit Turnarounds
A. Process and Facility Description
Petroleum refinery process units (e.g., crude distillation unit, fluid
catalytic cracking units) are periodically shut down and emptied for internal
inspection and maintenance. The action of unit shutdown, repair, or inspection
and start-up is termed a unit turnaround. In order for workmen to enter
process vessels, vessel liquids are pumped to storage and vapors are purged
(by depressurizing and flushing with water, steam, or nitrogen) and the
vessel is ventillated. Refinery process unit turnarounds range in frequency
from 6 months to 6 years. A typical process unit is shut down every 3 years.I-4
It is estimated that in 1984, there were over 600 process unit turnarounds
nationwide.5
B. Emission Sources and Factors
VOC emissions occur when vessels are purged to provide a safe interior
atmosphere for workmen. Significant amounts of VOC are emitted by refineries
that vent vessel vapors to atmosphere. These refineries release the vapors
to atmosphere through a blowdown stack usually remotely located to ensure
that combustible mixtures will not be released within the refinery. The
emission factor for uncontrolled refinery process unit turnarounds 860 kg/10^
(300 lb/10-3 bbl) of refinery throughput is based on engineering estimates.®
C. Control Techniques and Emission Reductions
VOC emissions from process unit turnarounds can be controlled by venting
vessel vapors to a vapor recovery system or to a flare until the pressure in
the vessel is as cose to atmospheric pressure as practicable. The exact
pressure at which the vent to atmosphere is opened will depend on the pressure
drop of the disposal system. Most refineries depressurize a vessel almost to
atmospheric pressure, then flood the vessel with steam before the vessel is
opened to atmosphere.1»2,3 in some refineries the hydrocarbon concentration
within the vessel can range from 1 to 30 percent before the vessel is vented
to atmosphere.^ The emission factor for refineries that control process unit
turnarounds by depressurizing to a control device is 15 kg/103 (5.2 lb/103
bbl) of refinery throughput.6 Control of VOC emissions during a process
unit turnaround can reduce emissions by 845 kg/10^ m^ (296 lb/10^ bbl)
of refinery throughput, or about 98 percent.
4-8
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0. Regulatory Status
The EPA issued a CTG in October 1977 recommending that refineries pipe
process unit turnaround emissions to a flare header system or to fireboxes.6
It is estimated that about 56 percent (123) of the existing petroleum refineries
are controlling process unit turnaround emissions as required under State
regulations.?»8
E. Current National Emission Estimates
Nationwide emissions resulting from process unit turnarounds have been
estimated at 267,000 Mg/yr (294,000 tons/yr). Nationwide emissions were
estimated by multiplying the emission factors for controlled and uncontrolled
refineries by an estimated throughput for refineries. It was assumed that
^ the number of refineries in non-attainment areas is proportionate to refinery
throughput in non-attainment areas.6,8,9
F. Capital and Annual Control Costs
Control costs for process unit turnarounds are based on piping purge
vapors to a flare header system or control device for a typical 15,900 m^/day
(100,000 bbl/day) crude throughput refinery. The capital and annual costs of
this system are estimated at $158,000 and $42,000, respectively. Although
the annual costs assume no recovery credits, if all the emissions are recovered,
the control method could provide an annual cost savings.5,6
G. References
1. Letter with attachments from Carleton B. Scott, Union Oil Company of
California, to Don Goodwin, U.S. EPA, December 3, 1976.
2. Letter with attachments from L. Kronenberger, Exxon Company U.S.A.,
to Don Goodwin, U.S. EPA, February 2, 1977.
3. Letter with attachments from I.H. Gilman, Standard Oil Company of
California, to Don Goodwin, U.S. EPA, November 30, 1976.
4. Letter with attachments from R.E. Van Ingen, Shell Oil Company, to
Don Goodwin, U.S. EPA, January 10, 1977.
5. Memorandum. Rhoads, T., Pacific Environmental Services, Inc., to S.
Shedd, U.S. EPA, Derivation of Cost, Emissions, and Emission Reduction presented
in the VOC Control Techniques Document. November 1985.
4-9
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6. Guideline Series - Control of Refinery Vacuum Producing Systems,
Wastewater Separators, and Process Unit Turnarounds. U.S. Environmental
Protection Agency. EPA-450/2-77-025. October 1977.
7. Overview Survey of Status of Refineries in the U.S. with RACT
Requirements. U.S. EPA Contract No. 68-01-4147, Task Nos. 65 and 74.
October 1979.
8. Annual Refining Report, Oi1 and Gas Journal, Volume 82, Number 13,
March 26, 1984.
9. Outlook: U.S. petroleum product usage, Hydrocarbon Processing,
Volume 63, No. 11, November 1984.
4.1.4 Petroleum Refinery Cooling Towers
A. Process and Facility Description
Cooling towers dissipate heat from water used to cool process equipment
such as reactors, condensers, and heat exchangers. Cooling water is circulated
through process units and returned to a cooling tower where the water is
cooled evaporatively by forced air circulation. A study of petroleum refineries
found an average of 4 cooling towers per refinery.! It is estimated that
there were 880 refinery cooling towers in the United States in 1984.
B. Emission Sources and Factors
Emissions from cooling towers occur when petroleum fluids enter the
cooling water from leaking heat exchanger tubes or from reuse of process
wastewater in the cooling system. VOC's can be released to atmosphere at the
top of the tower as cooling water vaporizes and from the bottom where cooled
water collects prior to recirculation through the process water system. A
"worst-case" estimate of average emissions developed from a study of 31
refinery cooling towers is 0.084 kg/1,000 m^ water flow rate (0.0007 lb/1,000
gal).A typical refinery indirect contact cooling tower with a water flow
rate of 10,000 irrVhr (2,600,000 gal/hr) would emit 7.4 Mg (8.2 tons) of V0C
per year to atmosphere.
C. Control Techniques and Emission Reductions
Cooling tower V0C emissions are controlled by minimizing the amount of
V0C entering the tower. One control technique is to eliminate the use of
contaminated process water as cooling tower make-up. Another technique is to
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monitor total organic carbon in the cooling water to detect early indications
of small equipment leaks, and then find and repair them. Existing controls
consist of equipment inspection and maintenance. A study of controlled
cooling towers estimated emissions at 0.013 kg/1,000 m-* water flow rate (0.11
lb/10^ gal).4 The emission reduction for control of a typical 10,000 m^/hr
cooling tower may be approximately 6.3 Mg/yr (6.9 tons/yr).
D. Regulatory Status
The EPA hras not issued a CTG nor set NSPS standards to control emissions
of V0C from cooling towers.
E. Current National Emission Estimates
The majority of refinery cooling towers do not emit significant quantities
of V0C. A study of 31 refinery cooling towers found only 8 (26 percent) to
have statistically significant emissions.4 The total nationwide emissions of
V0C from cooling towers has been estimated at 2,400 Mg/yr.^ The nationwide
estimate was derived by multiplying the total number of estimated cooling
towers by an average sized cooling tower water flowrate and by a weighted
average emission factor. The emission factor was based on the assumption
that 26 percent of the cooling towers would have V0C controls in effect.
F. Capital and Annual Control Costs
Inspection and maintenance of refinery process equipment is already
performed in many refineries. Costs are for labor to inspect and repair
equipment and maintenance materials. Costs credits are received for product
recovery and improved process operations. Increased plant safety is an
additional benefit. Costs for monitoring equipment to detect organic
contamination in water range between $6,000 and $17,000.5»6
G. References
1. Development of Petroleum Refinery Plot Plans, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, EPA450/3-78-025,
June 1978.
2. Annual Refining Report, Oi1 and Gas Journal, Volume 82, Number 13,
March 26, 1984.
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3. Assessment of Atmospheric Emissions from Petroleum Refining: Volume
3. Appendix B, U.S. Environmental Protection Agency, EPA-600/ 2-80-075c,
April 1980.
4. Assessment of Atmospheric Emissions from Petroleum Refining: Volume
1, Technical Report, U.S. Environmental Protection Agency, EPA-600/2-80-075a,
April 1980.
5. Memorandum. Rhoads, T., Pacific Environmental Services, Inc., to S.
Shedd, U.S. EPA, Derivation of Costs, Emissions, and Emission Reduction
Presented in the VOC Control Techniques Document. November 1985.
6. Instrumentation for Pollution Control Engineering, 9:1, 20-22, January
1977.
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4.1.5 Wastewater Systems
A. Process and Facility Description
Wastewater is generated by a variety of sources 1n a petroleum
refinery including cooling water, condensed stripping steam, tank draw
offs and stormwater runoff. Oily water 1s usually collected by a segre-
gated oily wastewater collection system. Wastewater enters the collection
system by way of process drains. Process drains are connected directly
to sewer lines which eventually lead to the wastewater treatment system.
The wastewater treatment system usually Includes primary, secondary,
and tertiary treatment processes. Primary treatment removes free oil,
solIds and emulsified oil using such processes as oil-water separators
and a1r flotation units. Secondary treatment removes dissolved organlcs
and reduces BOD and COD. Tertiary treatment provides final polishing of
the wastewater before discharge.
B. Emission Sources and Factors*
The primary emission sources in the refinery wastewater system are
process drains, oil-water separators and air flotation units. Wastewater
entering secondary treatment processes downstream of the air flotation unit
is low in volatile organic content. Although sources such as oxidation ponds,
clarlfiers and holding ponds are generally large area sources, emissions per
unit surface area are low.
A common process drain is a straight section of pipe usually 10 to 15
centimeters (4-6 inches) in diameter. The pipe extends vertically to slightly
above grade and connects directly to a lateral sewer below grade. Drain
lines from refinery process units generally terminate just within, at, or
slightly above the open mouth of the process drain. There is often more
than one drain line depositing wastewater into a single process drain. A
medium-sized refinery might have as many as a thousand process drains.
As part of a study to develop emission factors for fugitive sources 1n
petroleum refineries, VOC emission measurements were made on process
drains. The emission factor developed for refinery process drains is
0.032 kilograms VOC per hour per drain.
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011-water separators are usually rectangular concrete basins in the
ground. This type of separator is known as an API separator. Typical
dimensions are 6 x 25 meters (20 x 80 feet) with a depth of 2.5 meters
(8 feet). Free oil, having a specific gravity less than water, rises to
the surface where 1t 1s skimmed at the downstream end of the separator.
The recovered oil 1s then sent back to the refining process. Emissions
from an uncovered separator are primarily affected by the wastewater
temperature, ambient temperature, oil volatility, and the volume and oil
content of wastewater. A relationship between percent loss of oil 1n the
separator and the ambient temperature, Influent wastewater temperature,
and the 10 percent boiling point of the influent oil was developed from
results of tests conducted by Litchfield. Typical wastewater conditions
were used to estimate an emission factor of 420 kilograms V0C per million
gallons of wastewater treated 1n an uncontrolled oil-water separator.
Dissolved air flotation uses dissolved gas to form bubbles in the
wastewater. These bubbles become attached to suspended solids and emulsified
oil 1n the wastewater and causes these substances to rise to the surface
of the flotation chamber where they are removed. The emission factor for
uncovered air flotation units is 15.2 kilograms V0C per million gallons
of wastewater. This emission factor was developed from results of
continuous monitoring of V0C from four air flotation units.
C. Control Techniques and Emission Reductions*
The control technique for reducing emissions from process drains
involves the use of a water seal. One type of water seal is the P-leg
water seal which is identical to the P-trap common to household kitchen
sinks. The water in the P-leg Isolates the sewer line from the atmosphere.
The control efficiency of the water seal is estimated to be 50 percent.
Control technology for an oil-water separator 1s a fixed roof with
vapors vented to a control device (e.g., flares) or a floating roof with a
perimeter seal system (similar to an external floating roof tank). These
control techniques can achieve an emissions reduction of approximately
97 percent.
4-14
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Reasonable control technology for dissolved air flotation units is
the installation of a well sealed fixed roof. The control efficiency is
estimated to be 77 percent.
D. Regulatory Status
The EPA issued a CTG in 1977 recommending fixed roofs be installed
on oil-water separators.2 Approximately 85 percent of existing separators
are equipped with some type of cover.
New source performance standards were proposed in 1986 (40 CFR, Part
60, Subpart QQQ) for controlling VOC emissions from process drains, oil-
water separators and air flotation units. The proposed NSPS was an
equipment standard requiring water seals on drains, fixed roofs with vapor
collection on oil-water separators and fixed roofs on air flotation units.
E. National Emission Estimates
Emissions estimates for 1984 are 47.4 gigagrams per year (Gg/yr)
from process drains, 7.5 Gg/yr from oil-water separators, and 0.6 Gg/yr
from air flotation systems.^
F. Capital and Annual Control Costs
For a process unit of medium complexity (e.g., alkylation unit)
having 44 drains, the total depreciable investment (TDI) for P-leg water
seals is $10,700. Annual operating costs and capital charges are estimated
to be $2,600.
For a 100 m^ oil-water separator, the TDI for a fixed roof and vapor
collection system is estimated to be $49,700. Annual costs are $27,400.
The TDI for a floating roof with a double seal system is approximately
$81,200. The annual costs are estimated to be $19,600.3
For a 70 dissolved air flotation unit, the TDI for a fixed roof
is estimated to be $15,300 and the annual costs are approximately $3,800.
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G. References
1. VOC Emissions from Petroleum Refinery Wastewater Systems -
Background Information for Proposed Standards. U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, July 1984.
2. Control of Refinery Vacuum Producing Systems, Wastewater Separators
and Process Unit Turnarounds - Guideline Series. U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina. EPA 450/2-77-
025, October 1977.
3. Memo from Mitsch, B. Radian Corporation, to docket file. November 30,
1984. Adjusted Cost-Effectiveness Estimates for Floating Roofs on Oil-
Water Separators.
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4.2 PETROLEUM PRODUCTS - STORAGE, TRANSPORTATION, AND MARKETING
4.2.1 Oil and Gas Production Fields
A. Process and Facility Description
There are three basic operations involved in producing and processing
crude oil and natural gas. The operations are (1) well drilling, (2) oil and
gas separation, and (3) natural gas processing. Drilling is necessary to
produce the crude oil and gas. The well-head gas/oi1/water mixture is separated
into crude oil for sale and transfer to pipeline companies, natural gas for
sale and transfer to pipelines, and water for disposal/reinjection. Crude
oil is stored at tank batteries prior to lease custody transfer. Natural gas
may be processed to remove H2S and CO2 if necessary and processed to remove
natural gas liquids if desired. Natural gas liquids removal is discussed in
Section 4.2.2.
B. Emission Sources and Factors
Emissions from drilling operations occur when drilling muds are degassed.
Drilling mud is pumped from a suction tank or mud pit to the drill string.
The mud is returned to a shale shaker for cuttings removal, and finally to a
settling pit and temporary storage in a sump pit. Some formation gases
entrained in the mud will be emitted to the atmosphere in the shale shakers
and mud pits, but most of the gas will be extracted by a degasser prior to
reinjection. The average VOC emission rate per day per producing well being
drilled ranges from 2.7 Kg/day (5.9 lb/day) f-or Alabama to 8.2 Kg/day (18.0
lb/day) for Colorado. The equation describing the VOC emissions (E, Kg per
day) occurring during the drilling of an oil or gas well is as follows:*
E = VZPD + LT + MH
where:
E = VOC emissions, (Kg/day)
V = Volume of hole drilled, (M^)
Z * Producing zone depth/well depth, (fraction)
P = Porosity of producing zone cutters, (fraction)
D = Density of oil/gas 1n producing zone, (Kg/m^)
L = Leakage of oil/gas into drilling mud, (Kg/day)
T = Avg. producing zone exposed time, (day)
M = Oil-base mud emission, (Kg/day)
H = Avg. hole drilling time, (days)
4-17
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Emission sources from the separation process or tank battery include
storage tanks and equiment leaks. Production storage tanks commonly have a
fixed roof and are of either bolted or welded construction. New tanks are
primarily shop fabricated and of welded construction. VOC emissions from
tank battery tanks are estimated to be approximately 1 Mg/yr/tank (1.1 tons/yr/
tank).2 Equations for estimating storage tank emissions are provided in EPA's
publication AP-42. Major assumptions for emissions estimate are as follow:
stored product is crude oil; tank volume (20,000 gallon); number of turnovers
(36/yr); vapor pressure @ storage temperature (2.8 psia); tank diameter (15.5
ft); tank height (15 ft); and molecular weight (50 lb/lb mole). This estimate
may overstate VOC emissions because the methane/ethane content of the gas
vapors is not subtracted from the estimate.
Emissions of VOC from tank batteries can result when process fluids (either
gaseous or liquid) leak from plant equipment. Potential leaking equipment
includes: pumps, compressors, valves, pressure relief devices, open-ended
lines and flanges, and other connectors. Emissions of VOC from a tank battery
equipment 1n the absence of regulatory controls would be approximately 0.6
Mg/yr (0.66 tons/yr).3 Emissions from equipment leaks are discussed in the
background information document for the proposed NSPS^ and the CTG^ document
for gas plant equipment leaks.
C. Control Techniques and Emission Reductions
Emissions from fixed roof tanks can be controlled by the installation
of an internal floating roof and seals or by using a vapor recovery system.
The control efficiency of internal floating roof systems ranges from 60 to
99 percent, depending on the type of roof and seals installed and on the
type of organic liquid stored. Internal floating roof systems are not effec-
tive on bolted storage tanks because tank bolts affect the seals.
Several vapor recovery procedures may be used, including vapor/liquid
absorption, vapor compression, vapor cooling, vapor/solid adsorption, or a
combination of these. The overall control efficiencies of vapor recovery
systems are as high as 90 to 98 percent.
Thermal oxidation or flaring is another method of emission control for
fixed roof tanks; control efficiencies for this system can range from 96 to
99 percent.
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Two approaches are available to control tank battery equipment leaks of
VOC: (1) a leak detection and repair program and (2) the installation of
specific controls or leakless equipment. The emission reduction efficiency
of leak detection and repair programs is dependent upon a number of factors
including: (1) the monitoring method (visual, instrument, or soap solution);
(2) leak definition; (3) frequency of inspections; (4) the time interval
allowed between leak detection and subsequent leak repair; and (5) the emission
reduction achieved by each successful repair. Leak detection and repair
programs may achieve control efficiencies up to 60 and 80 percent for pumps
and valves, respectively, under a monthly monitoring program. Control
equipment can achieve control efficiencies approaching 100 percent. Examples
of control equipment include: (1) venting emissions from pressure relief
devices, pumps, and compressors to a control device (e.g., flare or process
heater); (2) dual mechanical seals with barrier fluid systems for pumps and
compressors; (3) caps, plugs, or second valves or open-ended lines; and (4)
sealed bellows valves.
D. Regulatory Status
There are no EPA regulations or guidelines which address VOC emissions
from drilling operations or tank battery storage tanks and equipment leaks.
E. Current National Emission Estimates
Annual VOC emissions from tank battery storage and equipment leaks are
estimated at approximately 175,000^ and 51,000 megagrams per year in 1984,
respectively. Tank battery storage estimate is based on a tank battery
population of 84,000 with two tanks per tank battery.
F. Capital and Annual Control Costs6
For a new 20,000 gallon capacity storage tank, capital costs for an
internal floating roof tank are estimated at approximately $7,800 (in 1984
dollars); deck and seal costs are $6,300 and $1,500, respectively. Annual
operating costs and capital charges are estimated at approximately $1,760; a
20- and 10-year life were estimated for the deck and seal, respectively.
A net annual savings of $200 for crude oil recovery would be realized; thus,
reducing annual costs to $1,560.
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G. References
1. Assessment of Oil Production VOC Sources, U.S. Environmental Protec-
tion Agency, Research Triangle Park, North Carolina, EPA-600/2-81-197 (NTIS
#PB82108-176). 1982.
2. Memo from David Markwordt to File: Oil and Production Fields, March 1,
1985.
. 3. Source Category Survey Report, Onshore Production, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina. March 19, 1980.
Docket A-80-20-A II-A-13. p. 4-11.
4. Equipment Leaks of VOC in Natural Gas Production Industry - Background
Information for Proposed Standards, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, EPA-450/3-82-024a. December 1983.
5. Guideline Series - Control of Volatile Organic Compound Equipment
Leaks from Natural Gas/Gasoline Processing Plants, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, EPA-450/3-83-007.
December 1983.
6. Memo from David Markwordt to File: Oil and Production Fields, March 1,
1985.
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4.2.2 Natural Gas and Natural Gasoline Processing Plants
A. Process and Facility Description
Natural gas and natural gasoline processing plants (gas plants) are
facilities engaged in the separation of natural gas liquids from field gas,
the fractionation of liquids into natural gas products (i.e., gasoline), or
other operations associated with the processing of natural gas products.
There are approximately 880 gas plants operating in the United States (as of
January 1, 1984), with a total gas capacity of 1,970 (68,943.0 MMcfd) and
throughput of 1,074 (37,576.8 MMcfd).*
B. Emission Sources and Factors
Emissions of VOC from gas plants can result when process fluids (either
gaseous or liquid) leak from plant equipment. Potential leaking equipment
include: pumps, compressors, valves, pressure relief devices., open-ended
lines and flanges, and other connectors. Emission factors for process equipment
have been developed based on the results of several source testing studies.
Emissions from gas plant processing units can be estimated by multiplying
emissions for specific types of equipment by the number of equipment pieces
in the processing units. Equipment emission factors are presented in Table
4.2.2-1. Emissions of VOC from gas plants in the absence of regulatory controls
may range from 30 to 300 Mg/yr (33 to 330 ton/yr).2 Emissions from gas plant
equipment leaks are discussed in the background information documents for the
proposed and promulgated NSPS3.4 and the CTG document for gas plant equipment
leaks.5
C. Control Techniques and Emission Reductions
Two approaches are available to control gas plant equipment leaks of VOC:
(1) a leak detection and repair program and (2) the installation of specific
controls or leakless equipment. The emission reduction efficiency of leak
detection and repair programs is dependent upon a number of factors including:
(1) the monitoring method (visual, instrument, or soap solution); (2) leak
definition; (3) frequency of inspections; (4) the time interval allowed
between leak detection and subsequent leak repair; and (5) the emission reduction
achieved by each successful repair. Leak detection and repair programs may
achieve control efficiencies are presented in Table 4.2.2-1 for quarterly
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and monthly monitoring programs.3 Control equipment can achieve control
efficiencies approaching 100 percent. Examples of control equipment include:
(1) venting emissions from pressure relief devices, pumps, and compressors to
a control device (e.g., flare or process heater); (2) dual mechanical seals
with barrier fluid systems for pumps and compressors; (3) caps, plugs, or
second valves on open-ended lines; and (4) sealed bellows valves.
TABLE 4.2.2-1 EMISSION FACTORS AND CONTROL EFFECTIVENESS3
Control Emission Reductions
Average
Quarterly Monitoring
Monthly Monitoring
Equi pment
Emission
Emi ssion
Percent
Emission
Percent
Type/Service
Factor
Factor,
Reduction
Factor,
Reducti on
kg/hr
Kg/hr
Kg/hr
Valves
0.18
0.041
77
0.029
84
Relief Valves
0.33
0.12
63
0.10
70
Compressor Seals
1.0
0.18
82
-
-
Pump Seals
1.2
0.50
58
0.42
65
aReference 3.
D. Regulatory Status
The EPA issued a CTG in February 1984 and set NSPS on June 24, 1985
(49 FR 26122), to control equipment leaks of VOC in gas plants. The CTG
recommends quarterly leak detection and repair for pumps, valves, pressure
relief devices, and compressors in gas/vapor or light liquid service. Pumps
also would receive weekly visual inspections. The CTG recommends that caps
be installed on open-ended lines. The NSPS requires monthly monitoring of
valves and pumps and quarterly monitoring of pressure relief devices. The
NSPS allows quarterly monitoring for valves not found leaking for 2 successive
months. Compressors in natural gas liquids service would be equipped with
seals having a barrier fluid system that prevents leakage of the process
fluids to the atmosphere and caps are required for open-ended lines. An
estimated 120 gas plants (14 percent) have implemented the controls recommended
by the CTG as required under State or local regulations.
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E. Current National Emission Estimates
Annual VOC emissions from gas plant equipment leaks has been estimated at
76,000 megagrams (84,000 tons) per year in 1984. The nationwide emissions
estimate was derived by multiplying the total estimated number of gas plant
process units by process unit emission estimates. The nationwide emission
estimate assumes that 14 percent of the gas plants are in non-attainment
areas.6
F. Capital and Annual Control Costs
Capital and annual costs for controlling gas plant equipment leaks are
presented in Table 4.2.2- 2. for a small and large process unit. These costs
are estimated based on control costs for individual types of equipment multiplied
by the number of each type of equipment in the process unit. The costs
presented include expenditures incurred for monitoring instruments.6
TABLE 4.2.2-2 CAPITAL AND ANNUAL COSTS TO CONTROL GAS PLANT
EQUIPMENT LEAKS3
Costs Capital Cost Annual Cost
($1,000) CTG NSPS CTG NSPS
Unit Si ze:
Small 15 24 5.4 8.5
Large 50 71 (9.0) 9.6
Parentheses denote cost savings.
Reference 6.
G. References
1. Worldwide Gas Processing, Oi1 and Gas Journal, Volume 82, No. 29,
July 16, 1984, p. 80.
2. Memorandum, T.L. Norwood, Pacific Environmental Services, Inc., to
Docket A-80-20(B), Nationwide Emission Reductions and Costs of the Promulgated
NSPS for Gas Plants (ESED Project Number 80/22), January 2, 1984.
3. Equipment Leaks of VOC in Natural Gas Production Industry Background
Information for Proposed Standards, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, EPA-450/ 3-82-024a. December 1983.
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4. Equipment Leaks of VOC in Natural Gas Production Industry Background
Information for Promulgated Standards, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, EPA-450/ 3-82-0246. May 1985.
5. Guideline Series - Control of Volatile Organic Compound Equipment
Leaks from Natural Gas/Gasoline Processing Plants, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, EPA-450/3-83-007. December
1983.
6. Memorandum. Rhoads, T., Pacific Environmental Services, Inc., to
S. Shedd, U.S. EPA, Derivation of Cost, Emissions, and Emission Reductions
Presented in the VOC Control Techniques Document. November 1985.
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4.2.3 Petroleum Liquid Storage Tanks
A. Process and Facility Description
Organic liquids in the petroleum industry (petroleum liquids) are
mixtures of chemicals having dissimilar true vapor pressures (for example,
gasoline and crude oil). Petroleum liquids are stored in tanks having any one
of three basic tank designs: fixed-roof, internal floating-roof, and
external floating-roof. It is estimated that in 1983 there were a total of
44,300 petroleum storage tanks nationwide (with capacities greater than
40,000 gallons).^
A typical fixed-roof tank consists of a cylindrical steel shell with a
permanently affixed roof. An internal floating-roof tank has both a perma-
nently affixed roof and a cover that floats on the liquid surface (contact
roof), or that rests on pontoons several inches above the liquid surface
(noncontact roof), inside the tank; This roof rises and falls with the
liquid level. The floating roof commonly incorporates flexible perimeter
seals or wipers which slide against the tank wall as the roof moves up and
down. An external floating-roof tank consists of a cylindrical steel shell
equipped with a deck or roof which floats on the surface of the stored liquid,
rising and falling with the liquid level. A seal (or seal system) attached
to the roof, contacts the tank wall to cover the small annular space between
the roof and the tank wall and slides against the tank wall as the roof is
raised or lowered.
B. Emission Sources and Factors
Two types of emissions from fixed-roof tanks are breathing losses and
working losses. The expansion of vapors in the tank due to changes in ambient
temperature and pressure result in V0C emissions termed "breathing losses."
Additional V0C emissions termed "working losses" result from vapors emitted
from a tank as a result of filling and emptying operations. The total annual
V0C emissions from a fixed-roof storage tank would be the sum of the
breathing and working losses. The total annual V0C emissions from a large
diameter (30 meter) and a small diameter (10 meter) fixed-roof storage tank
are presented in Table 4.2.3.1.2
The emission estimates presented throughout this section are calculated
using current emission formulae as presented in the fourth edition of the EPA
publication AP-42.3 The emission factor equation for fixed-roof tank
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TABLE 4.2.3.1. FIXED-ROOF TANK EMISSIONS AND EMISSION REDUCTIONS
OBTAINED WITH AN INTERNAL FLOATING-ROOF3
(Gasoline at 10 psi RVP)
FRT IFRTlm Emission Percent
Capacity Diameter Turnovers Emissions Emissions Reduction Reduction
(m3) (m) (Mg/yr) (Mg/yr) (Mg/yr)
1,000 10.0 10.0 13.49 1.14 12.35 91.6
1,000 10.0 20.0 23.37 1.14 22.23 95.1
10,000 30.0 5.0 77.76 4.49 73.27 94.2
10,000 30.0 10.0 127.18 4.50 122.68 96.5
Reference 2.
Nomenclature explanation - FRT = Fixed-roof tank
IFRTlm * Internal floating-roof tank (with a liquid-mounted primary seal).
TABLE 4.2.3.2. EXTERNAL FLOATING-ROOF TANK EMISSIONS AND
EMISSION REDUCTIONS OBTAINED WITH A SECONDARY
SEAL OVER A MECHANICAL SHOE SEAL3
(Gasoline at 10 psi RVP)
EFRTms EFRTms ss Emission Percent
Capacity Diameter Turnovers Emissions Emissions Reduction Reduction
(nr) (m) (Mg/yr) (Mg/yr) (Mg/yr)
1,000
1,000
10,000
10,000
10.0
10.0
30.0
30.0
10.0
20.0
5.0
10.0
4.06
4.06
12.16
12.17
0.22
0.22
0.65
0.66
3.84
3.84
11.51
11.51
94.6
94.6
94.6
94.6
Reference 2.
Nomenclature explanation - EFRTm<. = External floating-roof tank (with a
mechanical shoe primary seal) EFRTms ss = External floating-roof tank (with*a
mechanical shoe primary seal and a rim-mounted secondary seal).
4-26
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breathing losses is based on test data collected by the Western Oil and Gas
Association, the Environmental Protection Agency, and the German Society for
Petroleum Science and Carbon Chemistry. A comparison was made between the
new test data in these reports and the breathing losses calculated by using
the 1977 version of the emission factor equation in AP-42. It was determined
from this comparison that the emission factor equation for fixed-roof
breathing losses tended to over-predict and was therefore scaled downward.^
The American Petroleum Institute sponsored a program to develop additional
laboratory, pilot tank and field tank data on evaporative losses from internal
and external floating-roof tanks. The mechanisms of evaporative loss were
investigated and the effects of relevant variables were quantified, which
resulted in the formulation of the current AP-42 emission factor equations.
External and internal floating-roof tanks have similar sources of VOC
emissions, known as "standing storage losses" and "withdrawal losses".
Standing storage losses or seal losses for both external and internal floating
roofs can be the result of an improper fit between the seal and the tank wall
which causes some of the liquid surface to be exposed to the atmosphere.
Internal floating-roof tanks can also have standing storage losses through
the openings in the deck required for various types of fittings (fitting
losses); and through the nonwelded seams formed when joining sections of the
deck material (deck seam losses). Withdrawal loss is the vaporization of
liquid that clings to the tank wall and is exposed to the atmosphere when a
floating-roof is lowered by withdrawal of liquid. Thus the total annual
VOC emissions from either an external floating-roof storage tank or an
internal floating-roof storage tank would be the sum of the standing storage
loss and the withdrawal loss.
The total annual VOC emissions from a large and a small diameter internal
floating-roof storage tank, equipped with a liquid-mounted primary seal,
a bolted deck and controlled fittings are shown in Table 4.2.3.1.2 The total
annual VOC emissions from a large and a small diameter external floating-
roof storage tank, equipped with a mechanical shoe primary seal are shown in
Table 4.2.3.2.2
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C. Control Techniques and Emission Reductions
Several methods are available to control VOC emissions from fixed-roof
tanks: (1) the installation of an internal floating-roof and seal system,
(2) a vapor recovery system (e.g., refrigerated vent condensers, carbon
adsorption), and (3) a vapor destruction system (thermal oxidation). The
emission reduction and percentage reduction which may be obtained with an
internal floating-roof tank over a fixed-roof tank are shown in Table 1.
Generally an internal floating-roof installed on a fixed-roof tank will
reduce VOC emissions by 93 to 97 percent.7 A carbon adsorption vapor control
system is estimated to reduce VOC emissions by approximately 98 percent.® A
thermal oxidation vapor control system is estimated to reduce VOC emissions
by approximately 98 percent.5.10 Standing storage loss emissions from external
and internal floating-roof tanks are controlled by one or two separate
seals. The first seal is called the primary seal, and the other, mounted
above the primary seal, is called the secondary seal. There are tnree oasic
types of primary seal: (1) mechanical (metallic shoe), (2) resilient (non-
metallic, either vapor-mounted or liquid-mounted), and (3) flexible wiper.
A primary seal serves as a conservation device by closing the annular space
between the edge of the floating-roof and the tank wall. Two types of
secondary seal are currently available, shoe-mounted and rim-mounted. A
liquid-mounted primary seal has a lower emission rate and thus a higher
control efficiency than a vapor-mounted seal. Metallic shoe seals are
commonly employed only on external floating-roof tanks and are more effective
than vapor-mounted seals, but less effective than liquid-mounted seals.
A secondary seal, be it in conjunction with a liquid- or vapor-mounted
primary seal, provides an additional level of control.^ The emission reduc-
tion and percentage reduction which may be obtained with a rim-mounted
secondary seal over a mechanical shoe primary seal in an external floating-
roof tank are shown in Table 4.2.3.2.2
0. Regulatory Status
The EPA issued CTG's in 1977 and 1978 and set NSPS in 1974 (40 CFR 60
Subpart K) and revised the NSPS in 1980 (40 CFR 60 Subpart Ka) to control VOC
emissions from storage of petroleum liquids. Also, the NSPS for volatile
organic liquid storage tanks which was proposed in 1984 (40 CFR 60 Subpart
4-28
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Kb) included control of VOC emissions from storage of petroleum liquids. The
CTG is applicable to fixed-roof storage tanks having a capacity greater
than 150,000 liters (40,000 gal) and storing petroleum liquids which have a
true vapor pressure greater than 10.5 kPa (1.5 psia). The CTG recommendations
are stated in terms of equipment specifications and maintenance requirements.
The installation of internal floating-roofs inside fixed-roof tanks is
recommended. The CTG also recommends the use of alternative control equipment
of equivalent efficiency.
Subpart K of the NSPS applies to storage tanks with a capacity greater
than 151,416 liters (40,000 gal) and less than or equal to 246,052 liters
(65,000 gal) which were constructed or modified after March 8, 1974 and prior
to May 19, 1978. Also, it applies to storage tanks with a capacity greater
than 246,052 liters (65,000 gal) which were constructed or modified after
June 11, 1973 and prior to May 19, 1978. Subpart K requires that a storage
tank be equipped with a floating-roof, a vapor recovery system, or their
equivalent if the petroleum liquid being stored has a true vapor pressure
greater than or equal to 10.5 kPa (1.5 psia) but less than or equal to 76.6
kPa (11.1 psia). Also, a storage tank is required to have a vapor recovery
system or its equivalent if the petroleum liquid being stored has a true
vapor pressure greater than or equal to 76.6 kPa (11.1 psia).
Subpart Ka of the NSPS applies to storage tanks with a capacity greater
than 151,416 liters (40,000 gal) which were constructed or modified after
May 18, 1978 and prior to July 23, 1984. For storage tanks which contain a
petroleum liquid having a true vapor pressure greater than or equal to 10.5
kPa (1.5 psia) but less than or equal to 76.6 kPa (11.1 psia), Subpart Ka
requires the use of: (1) an external floating-roof with primary and
secondary seals, (2) an internal floating-roof on a fixed-roof tank, (3)
a vapor recovery system, or (4) an equivalent system. If the storage tank
contains a petroleum liquid having a true vapor pressure greater than 76.6
kPa (11,1 psia), Subpart Ka requires the use of a vapor recovery system.
Subpart Kb applies to petroleum storage tanks which were constructed or
modified after July 23, 1984. A detailed description of the requirements in
Subpart Kb are presented in Section 4.3.2.
4-29
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E. Current National Emission Estimates
Total annual VOC emissions from petroleum liquid storage tanks has been
estimated at 667,902 Mg/yr (736,240 tons/yr) in 1983. This estimate is based
on projected new external floating-roof tanks being equipped with a vapor-
mounted primary seal and a rim-mounted secondary seal and projected new
internal floating-roof tanks being equipped with typical uncontrolled
fittings.^
F. Capital and Annual Control Costs
The capital and net annualized cost to install an internal floating-
roof equipped with a liquid-mounted primary seal on a new fixed-roof
tank for either a small or a large size tank is shown in Table 4.2.3.3.2»7
The capital and net annualized cost to install a secondary seal on a new
external floating-roof tank for either a small or a large size tank is
shown in Table 4.2.3.4.2i7
6. References
1. Pacific Environmental Services, Inc. Estimated Nationwide Petroleum
Storage Tank VOC Emissions for the Years 1983 and 1988. Report to TRW Environ-
mental Engineering Division, Research Triangle Park, North Carolina. Contract
No. M23399JL3M. April 5, 1983. p. 20.
2. Memorandum. Gschwandtner, K., Pacific Environmental Services, Inc.,
to S. Shedd, U.S. EPA. Derivation of Cost, Emissions and Emission Reductions
presented in the VOC Control Techniques Document. January 1986.
3. Compilation of Air Pollutant Emission Factors - Fourth Edition.
U.S. Environmental Protection Agency, Office of Air Quality Planning and
Standards, Research Triangle Park, North Carolina. AP-42. September 1985.
'4. Petroleum Liquid Storage Vessels - Revision of AP-42 - Background
Document, EPA Contract No. 68-02-3063, TRW Environmental, Inc., Research
Triangle Park, North Carolina, May 1981.
5. Evaporation Loss From Internal Floating-Roof Tanks, Third Edition,
Bulletin No. 2519, American Petroleum Institute, Washington, D.C., 1983.
6. Evaporation Loss From External Floating-Roof Tanks, Second Edition,
Bulletin No. 2517, American Petroleum Institute, Washington, D.C., 1980.
4-30
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TABLE 4.2.3.3. CAPITAL AND ANNUALIZED COST FOR AN INTERNAL FLOATING-ROOF
INSTALLED IN A NEW FIXED-ROOF TANK3
(second quarter 1984 dollars)
Capacity
(nr)
Total
Diameter Turn- Capital Cost
(m) overs ($/Tank)
Total
Annualized Cost
($/year)
Net
Annualized Cost*5
($/year)
1,000
1,000
10,000
10,000
10.0
10.0
30.0
30.0
10.0
20.0
5.0
10.0
15,015
15,015
43,129
43,129
4,100
4,100
11,776
11,776
Reference 2.
bBased on a product recovery credit of $0.21/1iter for gasoline,
cNet annualized savings.'
147
(3,014)c
(ll,671)c
(27,480)c
TABLE 4.2.3.4. CAPITAL AND ANNUALIZED COST FOR A SECONDARY SEAL INSTALLED IN
A NEW EXTERNAL FLOATING-ROOF TANK WITH A MECHANICAL SHOE SEAL3
(second quarter 1984 dollars)
Total
Capacity Diameter Turn- Capital Cost
(m3) (m) overs ($/Tank)
Total
Annualized Cost
($/year)
Net
Annualized Costb
($/year)
1,000
1,000
10,000
10,000
10.0
10.0
30.0
30.0
10.0
20,0
5.0
10.0
2,724
2,724
8,171
8,171
744
744
2,231
2,231
aReference 2.
bBased on a product recovery credit of $0.21/liter for gasoline,
cNet annualized savings.
(484)c
(484)c
(l,452)c
(1,452)c
4-31
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7. VOC Emissions from Volatile Organic Liquid Storage Tanks - Background
Information for Proposed Standards. U.S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research Triangle Park, North
Carolina. EPA-450/3-81-003a. July 1984. pp. 4-9.
8. Letter from McLaughlin, Nancy D., U.S. Environmental Protection
Agency to D. Ailor, TRW, Inc. Comments on the benzene storage model plants
package. May 3, 1979.
9. Letter and attachments from D.C. Mascone, EPA/CPB, to J.R. Farmer,
EPA. June 11, 1980. Memo concerning thermal incinerator performance for
NSPS.
10. U.S. Environmental Protection Agency. Organic Chemical Manufacturing
Volume 4: Combustion Control Devices. Research Triangle Park, North Carolina.
Publication No. EPA-450/3-80-026. December 1980.
11. Reference 7, p. 4-15.
12. Reference 1, p. 3 and 12.
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4.2.4 Ship and Barge Transfer of Gasoline and Crude Oil
A. Process and Facility Description
Motor gasoline produced at petroleum refineries is transferred
primarily by pipeline, ship, or barge to intermediate storage and bulk
terminals. Various grades of gasoline are dispensed from refineries into
barges at dockside loading terminals. From barge loading terminals, gasoline
is delivered to bulk terminals.
Crude oil is imported to the contiguous 48 states via tanker and
pumped to shoreside storage facilities. The crude oil is then transferred
by pipeline or barge to refineries for processing.
B. Emission Sources and Factors*
Emissions from tanker and barge loading operations occur when gasoline
or crude oil being loaded displaces the vapors in the vessel to the atmosphere.
Loading is performed by connecting shoreside lines to the vessel header
system; a loading arm is used to attach the flanged delivery lines to the
vessel. Both tankers and barges have more than one tank to receive liquids;
there is a vapor vent on each tank. During loading, ullage caps are opened
for gauging to relieve vapors which simply are emitted to the atmosphere.
Emissions from tanker unloading operations occur when ballast being
loaded displaces vapors in cargo tanks previously unloaded. Barges are
not ballasted.
Emission rates for gasoline and crude loading and crude oil ballast
emissions are summarized below:
Loading
Bal1ast
(mg/1) (lb/103 gal)
(mg/1) (lb/103 gal)
transferred
ballast water
Barge
Crude Oi1
Gasoli ne
120
410
1.0
3.4
NA
NA
NA
NA
Tanker
Crude Oi1
Gasoline
73
215
0.61
1.8
129
100
1.1
0.8
4-26
4-33
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C. Control Techniques and Emission Reductions
Control techniques utilized to minimize emissions during tanker
ballasting operations include: (1) segregated ballast and (2) simultaneous
unloading and ballasting. Segregated ballast completely eliminates emissions
because VOC vapors are not present in space dedicated to ballast. Simultaneous
unloading and ballasting reduces emissions at port by displacing ballast
emissions Into the cargo space being unloaded.
Potential control techniques for barge loading operations include
refrigeration, carbon adsorption, thermal oxidation, and flaring.
Displaced vapors are vented directly to the control device. The control
system requires a vapor collection header onboard the barge. Hatches
must be closed during loading operations to maximize vapor collection.
Assuming that the loading and collection system is vapor tight, the emission
reduction using a thermal oxidizer or flare will be 98 and 90 percent,
respectively. However, leakage may occur resulting in less than 100 percent
capture. Based on gasoline terminal tests, the lowest leakage rate obtained
was approximately 10 percent of the vapors, by requiring annual pressure
tests and necessary maintenance; without test requirements the average
vapor leakage loss was approximately 30 percent. Therefore, total emission
reduction from loading operations could range from 88 to 68 percent for
thermal oxidizers and from 81.to 63 percent for flares.
Safety issues associated with tanker and barge control are not discussed
i n thi s document.
D. Regulatory Status
There are no EPA regulations or guidelines which address tanker and
barge loading and ballasting operations.
E. National Emission Estimates
• National emission estimates in 1982 are estimated at approximately
60,000 metric tons (66,000 tons) of VOC from gasoline and crude petroleum
barge loading operations and approximately 11,000 metric tons (12,000 tons)
of VOC from crude petroleum and gasoline ballasting operations. National
estimates are based on the volume of crude oil and gasoline transferred in
1982 as reported in the "Waterborne Commerce of the United States." Calendar
Year 1982. DoA Corps of Engineers, WRSC-WCUS - 82-5. Ballast water was
assumed to be 20 percent of tanker crude oil and gasoline unloaded.
4-34
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F. Captial and Annual Control Costs
Capital and annual control costs are not available.
G. References
1. Compilation of Air Pollutant Emission Factors. Volume 1. Stationary
Point and Area Sources. AP-42 Fourth Edition, September 1985. pp. 4.4-1
to 4.4-15.
2. Memo from David Markwordt, EPA, ESED, to Ship and Barge File.
"Section 4.2.4 Ship and barge Transfer of Gasoline and Crude Oil." February 28,
1986.
4-35
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4.2.5 BULK GASOLINE TERMINALS
A. Process and Facility Description
Motor gasoline produced at petroleum refineries is transferred primarily
by pipeline, ship, or barge to intermediate storage at bulk gasoline
terminals. Various grades of gasoline are dispensed through loading
racks into tank trucks at bulk gasoline terminals. From terminals, the
gasoline is delivered to bulk plants or to commercial or retail accounts
(service stations). It is estimated that there were approximately 1,500
tank truck gasoline loading terminals in the United States in 1982.1
B. Emission Sources and Factors
Emissions from tank truck loading operations occur when gasoline being
loaded displaces the vapors in the tank truck and forces the vapors to
the atmosphere. The amount of transfer emissions are dependent on the
vapor pressure of the product, product and tank temperature, condition of
the tank, tank leakage, and loading method. Loading may be performed
using either top splash or submerged loading methods, resulting in emissions
at typical rates of 1,940 and 800 milligrams of V0C per liter (mg/1) of product
loaded (or 16 and 6.7 lb/10^ gal.), respectively (Reference 2 and assuming
national average 12.6 RVP gasoline). Tank trucks returning with vapor,
displaced from storage tanks at service stations or bulk plants which
have installed vapor balance equipment, produce higher emission rates
(1,335 mg/1 or 11 lb/103 gal). Leaks from loading equipment, vapor
collection equipment and tank trucks are also an emission source. The
average V0C loss due to leakage from vapor collection equipment on gasoline
tank trucks was found during emission tests to be 30 percent (ranges
from 0 to 100 percent). Emissions from bulk terminal storage tanks are
discussed and covered under the Petroleum Liquid Storage section of this
Chapter.
C. Control Techniques and Emission Reductions
Control technology utilized to minimize emissions during tank truck
loading includes: (1) switching from top loading to submerged loading,
and (2) collecting displaced vapors, and routing the vapors to a vapor
4-36
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- thermal oxidizers, refrigeration, and carbon adsorbers - can reduce
these emissions to better than 35 mg/l.^ A good maintenance and annual
testing program can reduce leakage from vapor collection equipment on
tanks trucks to 10 percent.3
D. Regulatory Status
The EPA issued a CTG in 1977 and set NSPS standards in 1983 (40 CFR
60 Subpart XX) to control emissions during tank truck loading at gasoline
terminals.^ The CTG recommends and the NSPS requires emissions from tank
truck loading operations to be limited to 80 and 35 mg/1, respectively.
In addition, the NSPS requires annual testing of tank trucks for leaks.
There is also a CTG for tank trucks which recommends the same leak testing
program.5 Roughly two-thirds of the bulk gasoline terminals in 1982 are
estimated to have installed vapor processors (required under State
regulations).6 The EPA is reviewing the need to regulate benzene and
gasoline vapor emissions from all bulk gasoline terminals under Section 112
(see 49 FR 31706).
E. Current National Emission Estimates
The loading of tank trucks at bulk gasoline terminals has been esti-
mated to emit 142,000 meagrams of V0C in 1983 based on 1982 control levels.
F. Capital and Annual Control Costs6
For a typical 950,000 liter per day throughput terminal, capital
cost for installing a carbon adsorber and vapor collection equipment is
estimated to be $324,000 (in 1982 dollars). Annual operating costs and
capital charges are estimated to be $93,000. A net annual savings of
$70,000 for gasoline recovery would be realized; thus, reducing the annual
costs to $23,000.
G. References
1. National Petroleum News, 1983 Factbook Issue, Mid-June 1983,
Volume 75, No. 7A.
2. Transportation and Marketing of Petroleum Liquids. In: Compilation
of Air Pollution Emission Factors, U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina, AP-42, July 1979.
4-37
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G. References
1. National Petroleum News, 1983 Factbook Issue, Mid-June 1983,
Volume 7 5, No. 7A.
2. Transportation and Marketing of Petroleum Liquids. In: Compliation
of Air Pollution Emission Factors, U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina, AP-42, July 1979.
3. Bulk Gasoline Terminals - Background Information for Proposed
Standards -- and Promulgated Standards, U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina, EPA 450/3-80-038a and b.
December 1980 and August 1983.
4. Guidelines Series: Control of Hydrocarbons from Tank Truck Gasoline
Loading Terminals, U. S. Environmental Protection Agency, Research Triangle
Park, North Carolina, EPA 450/2-77-026, October 1977.
5. Control of Volati-le Organic Compound Leaks from Gasoline Tank
Trucks and Vapor Collection Systems, U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina, EPA-450/2-78-051, December 1978.
6. Evaluation of Regulatory Strategies for Gasoline Marketing Industry,
U. S. Environmental Protection Agency, Office of Air and Radiation,
Washington, D.C., EPA 450/3-84-012a, July 1984. [This document is under
public review and is subject to change. A revised document is scheduled
to be released by the end of 1986.]
7. Preliminary information on reanalysis of analyses in Reference 6.
4.2.6 BULK GASOLINE PLANTS
A. Process and Facility Description
Motor gasoline is transferred by truck from bulk terminals to intermediate
storage facilities, known as bulk gasoline plants or delivered directly
to service stations. The gasoline delivered to bulk plants is again
transferred into tank trucks and delivered to service stations and private
accounts, such as farmers. The trend in recent years has been toward
reducing the amount of gasoline passed through bulk plants. Approximately
25 percent of national gasoline consumption is passed through an estimated
15,000 bulk gasoline plants.
4-38
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B. Emission Sources and Factors2»3
Emissions from bulk plants occur when gasoline being loaded displaces
the vapors displaced in the tank truck or storage tank and forces the
vapors to the atmosphere (commonly called "working losses"). Emission
factors for loading of tank trucks at bulk plants are the same as discussed
previously for bulk terminals.
Temperature induced pressure differentials can expel vapor-laden air or
induce fresh air into storage tanks (breathing losses) and result in an
emission rate of roughly 228 mg/1 (1.9 lb/10^ gal.). Liquid transfers in
and out of storage tanks create loading and draining losses which combined
are called "working losses." Storage tank working losses result in emission
rates of roughly 1,640 mg/1 (13.7 Tb/lO^ gal.)
C. Control Techniques and Emission Reductions
Control technology utilized to minimize emissions during tank truck
and storage tank loading at bulk plants includes: (1) switching from top
splash loading to submerged loading, (2) collecting displaced vapors from
the loading of storage tanks and balancing the vapors back to the truck
being unloaded, and (3) collecting displaced vapors from trucks being
loaded and balancing the vapors back to the bulk plant's storage tank.
Converting the loading equipment from top splash to submerged loading
will reduce emissions by approximately 60 percent. Vapor balancing tank
truck and storage tank transfers can reduce working loss emissions by 90
to 95 percent.2 A good maintenance and annual testing program can reduce
leakage from vapor collection equipment on tank trucks to 10 percent.
D. Regulatory Status
The EPA issued CTGs in 1977 and 1978 to control emissions from bulk
plants and leakage from gasoline tank trucks and vapor collection systems,
respectivelyThe bulk plant CT6 recommends installation of balance
equipment for incoming and outgoing tank truck transfers. However, it
does address that plants below 15,000 liters (about 4,000 gallons) per
day of gasoline throughput may not be cost-effective in some situations.
4-39
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Roughly 45 percent of the bulk plants in 1982 are estimated to have
installed vapor balance systems on both the incoming and outgoing truck
transfers (required under State and local regulations).2 An additional 4
percent of the bulk plants have been estimated to have installed vapor
balancing of only incoming truck transfers. Both of the above CTG's
recommended checking for leakage from vapor piping and tank trucks with a
combustible gas detector. Additionally, the tank truck CTG recommends an
annual maintenance and pressure-vacuum testing program to reduce leakage
from vapor collection equipment on gasoline tank trucks. The EPA is
currently reviewing the need to regulate benzene and gasoline vapor
emissions from all bulk plants under Section 112 of the Clean Air Act
(see 49 FR 31706).
E. Current National Emission Estimates-*
Emissions from truck loading and unloading operations, and storage
tanks at bulk plants have been estimated to emit 180,000 megagrams (198,000
tons) of V0C in 1984 based on 1982 control levels.
F. Capital and Annual Control Costs 2
For a typical 24,600 liter (6,500 gallons) per day throughput bulk
plant, capital costs for installing vapor balance equipment on both the
incoming and outgoing truck transfers are estimated to average about
$28,540. Annual operating costs and capital charges are estimated to be
$5,750. A net annual savings of $2,540 for gasoline recovery would be
realized; thus reducing the annual costs to $3,210. Control costs vary
due to the size and layout of the facility. For more information on cost
varibility, References 2 and 4 should be consulted.
G. References
1. National Petroleum News, 1983 Factbook Issue, Mid-June 1983,
Volume 75, No. 7A.
2. Evaluation of Regulatory Strategies for Gasoline Marketing
Industry, U.S. Environmental Protection Agency, Office of Air and
Radiation, Washington, D.C., EPA 450/3-84-012a, July 1984. [This document
is under public review and is subject to change. A revised document is
scheduled to be released by the end of 1986.]
4-40
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3. Preliminary information on reanalysis of Reference 2.
4. Guideline Series: Control of Volatile Organic Emissions from
Bulk Gasoline Plants, U.S. Environmental Protection Agency, Office of
Air Quality Planning and Standards, Research Triangle Park, N.C.,
EPA-450/2-77-035, December 1977.
5. Control of Volatile Organic Compound Leaks from Gasoline Tank
Trucks and Vapor Collection Systems, U.S. Environmental Protection
Agency, Office of Air Quality Planning and Standards, Research Triangle Park,
North Carolina, EPA-450/2-78-051, December 1978.
4.2.7 SERVICE STATION STORAGE TANKS (STAGE I)
A. process and Facility Description
Motor gasoline is transferred by truck from bulk storage facilities
(bulk terminals or plants) to retail, public or private service stations.
Various grades of gasoline are unloaded, usually by gravity, from tank
trucks to underground storage tanks. The gasoline is again dispensed
through pumps into gas tanks on vehicles. Vehicle refueling operations
are discussed in the next section. It is estimated that there were
approximately 421,000 service stations (not including an estimated 2.5
million agricultural outlets) in the U.S. in 1982.*
B. Emission Sources and Factors *~2
Two types of emissions occur from service station storage tanks breathing
and working losses. Working losses occur when gasoline being unloaded
from the tank truck displaces vapors in the storage tank (loading losses)
and when fresh air is brought into the storage tank when small amounts of
gasoline is pumped out of the storage tank (emptying losses). Later,
this volume of fresh air becomes saturated with vapor (thus increasing
in volume) and the additional vapor volume is expelled to the atmosphere
through the storage tank vents. As discussed in the previous section
on bulk terminals, many parameters influence the amount of losses and those
emission factors discussed in the next few sentences are "typical" factors.
Loading may be performed using either top splash or submerged loading methods,
resulting in emissions (loading losses) of 1,690 or 1U75 milligrams (14 or
4-41
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9 lb/10^ gal.) of VOC per. liter (mg/1) of product loaded, respectively.
Emptying losses are estimated to be roughly 120 mg/1 (1 lb/lC)3 gallons).
Breathing losses occurring from temperature changes in the storage tank
have not been quantified, but are believed to be insignificant since
temperature fluctuations in underground tanks are small.
C. Control Techniques and Emission Reductions*
Control technology utilized to minimize emissions resulting from
storage tank working losses include: (1) switching from top splash
loading to submerged loading, and, (2) vapor balancing vapors displaced
vapors from the storage tanks back into the truck tank delivering the
gasoline. Converting loading equipment from top splash to submerged
loading, by extending the length of the fill pipe, can reduce loading
losses by approximately 60 percent. Installing piping and fittings for
vapor balancing equipment can reduce emissions by 95 percent. Since the
vapor balance system works on slight pressure in the storage tank and'
slight vacuum in the truck tank, all tanks and piping must be leak
free or little emission reduction will be achieved. • Although the emission
leak rates have not been quantified, routine checking leaks with a
combustible gas detector and annual tank truck vacuum testing is necessary.
D. Regulatory Status
The EPA issued a guidance paper in 1975 to control emissions from
service station storage tanks.3 This guidance paper recommends design
parameters and e'quipment specifications for vapor balance equipment. In
addition, EPA issued a CTG in 1973 to provide test procedures for tank .
trucks and vapor piping.4 Roughly one-half of the service stations in
1982 are estimated to have installed storage tank vapor balance systems
(required under State and local regulations).* The EPA is currently review-
ing the need to regulate benzene and gasoline vapor emissions from all
service stations under Section 112 of the Clean Air Act (see 49 FR 31706).
E. Current National Emission Estimates2
Emissions from storage tanks at service stations has been estimated
to emit 256,000 megagrams (282,000 tons) of VOC in 1984 based on the 1982
control levels discussed above.
4-42
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F. Capital and Annual Control Costs^
For a typical service station, capital costs for installing vapor
balance equipment is estimated to be $1,698. Annual operating costs and
capital charges are estimated to be $342. Unlike other gasoline marketing
controls, no liquid recovery credit is assumed since recovered vapors are
displaced back to the tank truck which returns the vapors to a bulk plant
or bulk terminal.
G. References
1. Evaluation of Regulatory Strategies for Gasoline Marketing
Industry, U.S. Environmental Protection Agency, Office of Air and Radiation,
Washington, D.C., EPA/3-84-012a, July 1984. [This document is under
public review and is subject to change. A revised document is scheduled
to be released by the end of 1986.]
2. Preliminary information on reanalysis of Reference 1 analysis.
3. "Design Criteria for Stage I Vapor Control Systems, Gasoline
Service Stations," U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle Park, North Carolina,
November 1975.
4. Control of Volatile Organic Compound Leaks from Gasoline Tank
Trucks and Vapor Collection Systems, U.S. Environmental Protection
Agency, Office of Air Quality Planning and Standards, Research Triangle
Park, North Carolina, EPA-450/2-78-051, December 1978.
4.2.8 VEHICLE REFUELING AT SERVICE STATIONS^ (Stage II)
A. Process and Facility Description
Motor gasoline is transferred by truck from bulk storage facilities
(bulk terminals or plants) to retail, public and private service stations.
Various grades of gasoline are unloaded from tank trucks into underground
storage tanks at service stations. (See previous section on service
station storage tanks.) The gasoline is again dispensed through pumps
and meters into gas tanks on vehicles (cars and trucks). It is estimated
that there were approximately 421,000 service stations (not including an
estimated 2.5 million agricultural outlets) in the U.S. in 1982.
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B. Emission Sources and Factors
Emissions from vehicle refueling operations occur when gasoline being
pumped into the vehicle gas tank displaces the vapors in the vehicle gas
tank to the atmosphere by way of the open fill neck. Recent EPA testing
has shown that refueling of a "typical" vehicle results in VOC emission
rates of 1,552 milligrams per liter (mg/1) (12.9 Ib/lO^ gallons) of
gasoline transferred. Other EPA testing in the 1970's has shown that
spillage of gasoline on the ground, side of vehicle, etc., accounts for
VOC emissions of roughly 84 mg/1 (0.7 lb/10^ gal) transferred.
C. Control Techniques and Emission Reductions
Vehicle refueling emissions can be controlled by: (1) equipment
installed at the service station which transfers the displaced vapors
from the motor vehicle gas tank back to the underground storage tank
(termed "Stage II Controls"), or (2) carbon canisters and a fill-pipe
seal installed on the motor vehicle whereby the displaced vapors are
adsorbed by the vehicles carbon canister as the gas tank is filled with
gasoline (termed "onboard controls"). Both Stage II and onboard controls
can be highly effective (as high as 95 and 98 percent, respectively).
However, their high theoretical efficiencies are likely to be reduced
during use (to as low as 62 percent for Stage II, depending on the level
of enforcement, and to about 95 percent for onboard controls, given the
expected level of tampering).
0. Regulatory Status
Stage II controls in 1984 are being used in 26 counties in California
and the District of Columbia (required by local and State regulations),
and are being considered for use by at least seven states. It is estimated
that the installed Stage II controls control 9 percent of the national
gasoline consumption. The EPA is currently reviewing the need for refueling
controls in ozone nonattainment areas and the need to regulate benzene and
gasoline vapor emissions from all vehicle refueling service stations under
Section 112 and 202(a)(6) of the Clean Air Act (see 49 FR 31706). As part
of the above review, EPA is reviewing which refueling control approach--
Stage II or onboard controls—is the preferred control technology.
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E. Current National Emission Estimates
Vehicle refueling at service stations has been estimated to emit 569,000
megagrams (627,000 tons) of V0C in 1984 based on 1982 control levels.
F. Capital and Annual Control Costs
For a 130,000 liter (34,000 gal.) per month throughput station (6-9
nozzles), average capital costs for installing Stage II controls is estimated
to be about $11,500. Annual operating costs and capital charges are
estimated to be $4,000. A net annual savings of $900 for gasoline recovery
would be realized; thus, reducing the total annual costs to $3,100. Costs
are dependent on the type of equipment used, number of nozzles and gasoline
throughput.
The average fleet cost per vehicle for onboard systems is estimated
to be $22. This would be the average cost to the purchaser of a new car
or truck.
G. References
1. Evaluation of Regulatory Strategies for Gasoine Marketing
Industry, U.S.- Environmental Protection Agency, Office of Air and Radiation,
Washington, D.C., EPA-450/3-84-012a, July 1984. [This document is under
public review and is subject to change. A revised document is scheduled
to be released by the end of 1986.]
2. Preliminary information on reanalysis of Reference 1 analysis.
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4.2.9 Vessel Cleaning
A. Process and Facility Description
Transportation vehicles--rail tank cars, tank trucks, and barges--are
used to transport a wide variety of petroleum and chemical commodities from
producer to consumer; as many as 70 commodities are transported by these
carriers. Facilities which clean vessels are either: (a) independent shops,
the business of which is cleaning vessels; (b) maintenance land service
stations which clean vessels incidental to repair operations or prior to
leasing; and (c) carrier facilities at shipping and receiving terminals or
manufacturers or producers.
Prior to vessel cleaning, a determination of vessel contents is made to.
determine the appropriate cleaning technique. This determination is made by-
either checking the cargo history or performing lab tests on the vessel
residuum or "heel." Vessels carrying hazardous chemicals or potentially
explosive gases may have to be freed of gases prior to cleaning; this can be
done by filling or flushing with water or pulling a vacuum or blowing air
depending on the vessel. These vapors will be released directly to or treated
prior to release to the atmosphere.
After vessels are made safe for cleaning, various cleaning agents are
used to remove residuum from the vessels. Steam, water, detergents, caustic
acid, and solvents may be employed in any number of combinations to clean the
vessels. Steam hoses, pressure wands, and rotating spray heads may be used to
apply cleaning agents to vessels. Wastewater from an estimated two-thirds of
the installations is directed to municipal treatment systems. Approximately
one-third of the existing facilities discharge directly to surface water
streams with only some oil separation. Newer facilities are using combinations
of one or more wastewater treatment methods such as gravity separation,
equalization, emulsion breaking, dissolved air flotation, coagulation, aerated
lagoons, trickling filter, activated sludge, activated carbon adsorption,
biological treatment, etc., to control wastewater. Temporary holding tanks
may be employed for wastewater prior to wastewater treatment or discharge.
4-46
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B. Emission Sources and Factors
Emission sources at cleaning facilities include gas freeing prior to
cleaning if necessary, vapor displacement during cleaning operations, holding
tanks, and wastewater treatment systems. Emission factors for vapor displacement
were estimated to be 24 mg and 58 mg per liter (0.0002 and 0.0005 lb per gallon)
of cargo capacity for barges and railcar/tank trucks, respectively. These
emission factors were calculated using the ideal gas law at 20°C (68°F) and
assuming 10 and 50 percent saturation of the air vapor volume being expelled
from the barges and railcar/tank trucks, respectively. The factor for
railcar/tank trucks is a weighted average of emission factors for the top 50
organic chemical compounds produced in 1983. The factor for barges is a
weighted average of emission factors for 13 of the largest V0C reported for
1982 in the "Waterborne Commerce of the United States," Calendar Year 1982,
DoA Corps of Engineers, WRSC-WCUS - 82-5.
C. Control Techniques and Emission Reductions
Flares and thermal oxidizers are practical techniques for controlling
cleaning vapor emissions because of their ability to handle many different
types of compounds. Displaced vapors during cleaning are vented directly to
the control device. The EPA has concluded that a combustion efficiency of
90 percent is attainable with a smokeless flare. Based on the EPA studies of
thermal oxidizers (TO) systems, a 98 percent V0C reduction is attainable with
a properly operated TO.
Assuming that the cleaning and collection system is vapor tight, the
emission reduction using a thermal oxidizer or flare will be 98 and 90 percent,
respectively. However, leakage may occur resulting in less than 100 percnt
capture. Based on gasoline terminal tests, the lowest leakage rate obtainable
was approximately 10 percent of the vapors, by requiring annual pressure tests
and necessary maintenance; without test requirements the average vapor leakage
loss was approximately 30 percent. Therefore, total emission reduction from
cleaning operations could range from 88 to 68 percent for thermal oxidizers
and from 81 to 63 percent for flares.
4-47
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0. Regulatory Status
There are no EPA regulations or guidelines which address vessel cleaning
operations.
E. National Emission Estimates
National emissions in 1982 are estimated at 10 metric tons of VOC from
vapor displacement during cleaning operations.*
F. Capital and Annual Control Costs
Capital and annual costs are not available.
G. Reference
1. Memo, Markwordt to Vessel Cleaning File. February 8, 1985.
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4.3. ORGANIC CHEMICAL MANUFACTURE
Standards development for VOC emissions from the manufacture of organic
chemicals center on the synthetic organic chemical manufacturing industry
(SOCMI) which uses 15 basic chemicals to produce over 7,000 intermediate and
end-product chemicals.1 Regulations focus on approximately 400 of the highest
volume chemicals. The basic chemicals are derived primarily from crude oil,
natural gas, and coal. Examples of basic chemicals include benzene, ethylene,
propylene, and propane. Basic chemicals are used to produce hundreds of
intermediate chemicals, which are subsequently used to manufacture end-product
chemicals. Generally, each process level contains more chemicals than the
preceding level, and process units manufacturing chemicals at the end of the
production system generally have smaller capacities (in terms of production
volume) than process units producing the basic materials. Also, the volatil-
ities of the end-product chemicals are typically less than those of basic
materi als.
A SOCMI process unit uses two broad categories of processes to manufacture
organic chemicals: conversion and separation. Conversion processes involve
chemical reactions that alter the molecular structure of chemical compounds.
Synthesis is a conversion process in which more complex compounds are formed
by combining simpler compounds or radicals. Conversion processes comprise the
reactor processes segment of a SOCMI plant. Separation processes often follow
conversion processes and divide chemical mixtures into distinct fractions.
Examples of separation processes are distillation, filtration, crystallization,
and extraction.
SOCMI emissioas have been divided into a number of groups according to
emission mechanisms to make the development of NSPS more manageable. These
major emission groups are process vents, equipment leaks, storage, and secondary.
Sources within each SOCMI group are similar with respect to operating procedures,
emission characteristics, and applicable emission control techniques. Process
vents from chemical reactor processes have been divided into two subsets, air
oxidation processes and reactor processes. Emissions from distillation
operations is the other category of process vents.
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4.3.1 Process Vents
4.3.1.1 SOCMI Reactor Processes
A. Process and Facility Description
Synthetic organic chemical manufacturing industry (SOCMI) emissions
have been divided into a number of groups according to emission mechanisms
to make the development of NSPS more manageable (See section 4.3)2. Reactor
processes are part of several groups constituting process vent emissions.
The focus of the reactor processes NSPS is all reactor processes other than
air oxidation. The category covers 32 different types of chemical reactions
used to produce about 180 high-volume chemicals.-*
B. Emission Sources and Factors
Reactor VOC emissions include all VOC in process vent streams from
reactors and associated product recovery systems. Process product recovery
equiment includes devices such as condensers, absorbers, and adsorbers.
Reactor processes may use be either liquid phase reactions or gas phase
reactions. Potential atmospheric emissions points include the following:
1. Direct reactor process vents from liquid phase reactors;
2. Vents from recovery devices applied to vent streams from liquid
phase reactors (Raw materials, products, or by-products may be recovered from
vent streams for economic or environmental reasons.);
3. Process vents from gas phase reactors after either the primary or
secondary product recovery device (Gas phase reactors always have primary
product recovery devices.); and
4. Exhaust gases from-combustion devices applied to any of the above
streams.
Some chemical production processes may have no reactor process vent to the
atmosphere, while others may have one or more vent streams.
VOC emission characteristics vary widely between the different chemical
reactions. For example, VOC emission factors range from 0 Kg/Gg of product
(0 lb/ton of product) for pyrolysis reactions to 180,000 Kg/Gg of product
(360 lb/ton of product) for chlorination reactions.
4-50
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VOC emission characteristics also vary widely for process units using the
same chemical reaction. Process units using chlorination reactions have
VOC emission factors that range from 228 to 180,000 Kg/Gg (0.46 to 360 lb/ton).
Process vent stream flow rates and heat values are not as variable. Flow
rates range from 0 to 537 scm/min, and heating valves range from 0 to 537
normal cubic meters/min (nm^/minMO to 19,000 standard cubic feet per minute
(scfm)). Heating values range from 0 to 48 Megajoules (MJ) per nm^ (0 to
1,300 Btu/scf)4.
C. Control Techniques and Emission Reductions
Control technology for reactor VOC emissions is divided into two cate-
gories: noncombustion control devices and combustion control devices. Non-
combustion control devices are generally gas treatment devices that recover
VOC from process streams; combustion control devices are designed to destroy
the VOC in the vent stream prior to atmospheric discharge. Combustion control
devices may also recover energy.
Noncombustion control devices include adsorbers, absorbers, and condens-
ers. Since VOC emission characteristics vary so widely between different
reactor processes, no one noncombustion control device can always be installed.
Adsorbers are not recommended for vent streams with high VOC concentrations,
and absorbers are generally not used on streams with VOC concentrations below
200 to 300 parts per million by volume (ppmv). Condensers are not well
suited for vent streams containing either low boiling point VOC or large
inert concentrations. Control efficiencies vary from 50 to 95 percent for
condensers and absorbers and up to 95 percent for adsorbers.
Combustion control devices include flares, thermal incinerators, catalytic
incinerators, industrial boilers, and process heaters. Aside from the catalytic
units, these devices can be applied to a wide variety of vent streams and can
achieve 98 percent efficiency or greater if properly designed and operated.
Combustion devices can adjust to moderate chartges in flow rate and VOC concen-
tration. Control efficiency is not greatly affected by the type of VOC
present. Addition of a scrubber may be required to incinerate process vent
streams containing halogenated or sulfonated compounds. These compounds can
also cause corrosion problems with flare tips, boiler tubes, and other plant
equipment.
4-51
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D. Regulatory Status
The EPA is currently drafting NSPS standards to control emissions from
the Synthetic Organic Chemical Manufacturing Industry (SOCMI) reactor processes.
The recommended standards would require VOC emissions from new, modified, and
reconstructed reactor process facilities to be reduced by 98 weight percent
or to 20 ppmv, whichever is less stringent.
E. National Emission Estimates
The emissions of reactor processes are estimated to be 55,700 Mg per
year (61,000 tons per year) in 1990 based on 1984 control levels. If the
recommended standards are implemented, VOC emissions will be reduced by about
2,030 Mg per year (2,240 tons per year) in 1990.
F. Captial and Annual Control Costs
For an individual reactor process vent stream with median flow rate and
median heat content, capital cost for installing a flare is estimated to be
$81,000 (in 1984 dollars). Annualized cost is estimated to be $107,000.
Reference 1 defines the median flowrate as 3.4 nm^/mm (121 scfm). The median
heat content is defined as 6.7 MJ/nm^ (180 Btu/scf). The median VOC flowrate
is 3.0 kg/hr (6.6 Ib/hr). Reference 1 presents cost equations generated by a
linear regression analysis of EPA cost curves. Flare costs are presented as a
function of height and top diameter.
G. References
1. U.S. Environmental Protection Agency. Reactor Processes in Synthetic
Organic Chemical Manufacturing Industry—Background Information for Proposed
Standards. (Preliminary Draft) Research Triangle Park, N.C. March 1985.
2. Reference 1.
3. Memo from Fidler, K., Radian Corporation, to L. B. Evans, EPA.
July 6, 1983. Identification of chemical production routes and unit processes
expected to be used in the future to manufacture the 176 chemicals considered
in the carrier gas Project.
4. Reference 1.
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4.3.1.2 SOCMI Air Oxidation
A. Process and Facility Description
Air oxidation processes are part of several groups constituting process
vent emissions from SOCMI. In air oxidation processes, one or more chemicals
are reacted with oxygen supplied as air or air enriched with oxygen. This
group also includes chemicals produced using a combination of atranonia and air
or of halogens and air as reactants. Thirty-six chemicals identified as
using air oxidation routes are shown in Table 4.3-1.^ Plastics and textile
fibers are the major end uses for the bulk of air oxidation chemicals.
B. Emission Sources and Factors
Air oxidation chemicals are produced with a large variety of reaction
types. Air oxidation processes can be grouped together because they all vent
large quantities of inert material containing VOC to the atmosphere. These
inerts are predominantly nitrogen from the air which has passed through the
reaction unreacted. The exact quantity of nitrogen and unreacted oxygen
emitted is a function of the amount of excess air used in the production
process.
Air oxidation reactions can be carried out in either liquid or gas
phase. For liquid phase, liquid feedstock and catalyst are fed into a reactor.
The reaction is carried out by passing air through this liquid mixture at a
controlled temperature and pressure. After completion of the reaction, two
streams come out of the reactor, liquid and gaseous. The liquid stream
usually contains the desired product, which is taken to a product recovery
system consisting of a series of different unit operations (e.g., distilla-
tion, crystallization, evaporation, etc.). The gaseous stream containing
nitrogen, unreacted oxygen, carbon dioxide, and some VOC is condensed or
cooled; then fed into the gas separator to recover the condensable compounds
4-53
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TABLE 4.3-1. SOCMI CHEMICALS PRODUCED BY AIR OXIDATION-
1. Acetaldehyde 20.
2. Acetic Acid 21.
3. Acetone 22.
4. Acetonitrile 23.
5. Acetophenone 24.
6. Acrolein 25.
7. Acrylic Acid 26.
8. Acrylonitrile 27.
9. Anthraquinone 28.
10. Benzaldehyde 29.
11. Benzoic Acid 30.
12. 1,3-Butadiene 31.
13. p-t-Butyl Benzoic Acid 32.
14. n-Butyric Acid 33.
15. Crotonic Acid 34.
16. Cumene Hydroperoxide
17. Cyclohexanol 35.
lb. Cyclohexanone 36.
19. Ethylene Dichloride
Dimethyl Terephthalate
Ethylene Oxide
Formaldehyde
Formic Acid
Glyoxal
Hydrogen Cyanide
Isobutyric Acid
Isophthalic Acid
Maleic Anhydride
Methyl Ethyl Ketone
-Methyl Styrene
Phenol
Phthalic Anhydride
Propionic Acid
Propylene Oxide
(tert butyl hydroperoxide)
Styrene
Terephthalic Acid
4-S4
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before venting it to the atmosphere or a control device. Vapor phase reactions
have a similar sequence of steps. However, liquid feedstocks are first
vaporized, then mixed with air in a mixing chamber prior to the reactor.
Atmospheric emissions originate at vents from the product recovery
devices. Hourly emissions range from 0 to 2100kg/hr (0 to 4,600 lb/hr).
F1 owrates range from 24 to 3,600 Nm3/m-jn (850 to 127,000 scfm), and heating
values range from 0 to 4 MJ/nm^ (0 to 107 Btu/scf).
C. Control Techniques and Emission Reductions
Control technology options for air oxidation process vents are identical
to options for reactor process vents (See Section 4.3.1.1C). Air oxidation
process vents are typically too dilute for flares to be cost-effective control
devices. Changes in flowrates, V0C concentrations, and waste stream contaminants
associatd with air oxidation process emissions can reduce the efficiency of
condensers, absorbers, adsorbers, and catalytic oxidizers. Thermal incinerators
are therefore the only demonstrated V0C control which is applicable to all
S0CMI air oxidation processes.
All new incincerators, if properly designed, adjusted, maintained, and
operated, can achieve at least a 98 percent V0C reduction or 20 ppmv exit
concentration, whichever is less stringent. This control level can be achieved
by incinerator operation at conditions which include a maximum of 1600°F and
0.75 second residence time.
D. Regulatory Status
In October of 1983, EPA proposed NSPS standards to control emissions
from the Synthetic Organic Chemical Manufacturing Industry (S0CMI) air oxida-
tion processes. The recommended standards would require V0C emissions from
new, modified, and reconstructed air oxidation process facilities to be
reduced by 98 weight percent or to 20 parts per million by volume (ppmv),
whichever is less stringent.
E. National Emission Estimates
The V0C emissions of air oxidation processes have been estimated at
110,000 Mg per year (121,000 tons per year) in 1984.
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F. Current Capital and Annual Control Costs
For a VOC-rich stream with a heating value of 2.6 MJ/nm^ (70 Btu/scf)
and a flowrate of 456 nm^ (16,000 scf) installed capital costs for a thermal
incinerator system are estimated to be $1,200,000 (in 1984 dollars). Annualized
cost is estimated to be $610,000.2 Costs are proportional to the flowrate of
the vent stream and inversely proportional to the net heating value. Refer-
ence 1 presents emission control 'costs and cost-effectiveness for various
vent streams.
G. References
1. U.S. Environmental Protection Agency. Air Oxidation Processes in
Synthetic Organic Chemical Manufacturing Industry - Background Information
for Proposed Standards. Research Triangle Park, North Carolina. Publication
No. EPA-450/3-82-001a. October 1983. p. 3-20.
2. Reference 2. p.8-21.
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4.3.1.3 SOCMI Distination Operations
A. Process and Facility Description
Distillation is a major processing step within the synthetic organic
chemical manufacturing industry (SOCMI). Distillation is a unit operation
used to separate one or more inlet feed streams into two or more outlet
product streams, each product stream having component concentrations different
from those in the feed streams. The separation concentrates the more volatile
component in the vapor phase while the less volatile component concentrates
in the liquid phase. Distillation systems can be divided into subcategories
according to the operating mode, the operating pressure, the number of
distillation stages, the introduction of inert gases, and the use of additional
compounds to aid separation.*
B. Emission Sources and Factors
During operation of a distillation column, vapors separating from the
liquid phase rise out of the column to a condenser. These vapors can
contain VOC, water vapor, and noncondensibles such as oxygen, nitrogen, and
carbon dioxide. The vapors and gases originate from vaporization of liquid
feeds, dissolved gases in liquid feeds, inert gases added to assist in distil-
lation, and air leaking into the column, especially in vacuum distillation.
Most gases and vapors entering the condenser are cooled enough to be collected
as a liquid phase. Noncondensibles are present as a gas stream at the end of
the condenser. Portions of this gas stream are often recovered in devices
such as scrubbers, adsorbers, and secondary condensers.
Atmospheric emissions vary between different distillation systems. VOC
emissions range from 0 to 1700 kg/hr (0 to 3,700 lb/hr). Flow rates range
from 0.0001 to 18 nm^/min (.004 to 640 scfm) and heating valves range from
0 to 180 MJ/nnr* (0 to 4,800 Btu/scf).^
C. Control Techniques and Emission Reductions
VOC control techniques for distillation operations include both non-
combustion and combustion control devices. Noncombustion devices may be
attractive if a significant amount of usable VOC can be recovered. Though
certain vent stream characteristics can limit the use of noncombustion devices
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(See Sections 3.3 and 3.4), many condensers and absorbers are applied to
distillation vent streams in the industry. Control efficiencies vary from 50
to 95 percent for condensers and up to 95 percent for adsorbers.
Combustion control devices are typically both capital and energy
intensive. However, these devices are applicable to a wide variety of vent
stream characteristics and all can achieve at least 98 percent destruction
efficiency .3
0. Regulatory Status
In December of 1983, EPA proposed NSPS standards (40 CFR, Part 60,
Subpart NNN) to control emissions from the Synthetic Organic Chemical
Manufacturing Industry (SOCMI) distillation operations. The recommended
standards would require VOC emissions from new, modified, and reconstructed
distillation operations to be reduced by 98 weight percent.
E. National Emission Estimates
The VOC emissions of distillation operations have been estimated at
140 Gg per year (150,000'tons per year) in 1984.
F. Current Capital and Annual Control Costs
For an average individual distillation vent stream with a flow rate of
0.7 nm^/min (25 scf/min) and a heating valve of 28 MJ/nrn^ (750 Btu/scf),
installed capital costs for boiler, flare, and incinerator are $31,500,
$53,200, and $345,000, respectively (in 1984 dollars). Annualized costs for
flare and incinerator are $36,500 and $164,000 (in 1984 dollars). Use of a
boiler results in a net annual savings of $26,600 due to reduced natural gas
consumption. Costs increase with increasing vent stream flow rates and
decrease with increasing vent stream heat values.
G. References
1. U.S. Environmental Protection Agency. Distillation Operations in
Synthetic OSrganic Chemical Manufacturing - Background Information for Proposed
Standards. Research Triangle Park, North Carolina. Publication No. EPA-
450/3-83-005a. December 1983.
2. Reference 1.
3. Reference 1.
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4.3.2 Volatile Organic Liquid Storage Tanks
A. Process and Facility Description
Five basic tank designs are used for storage of volatile organic liquids:
fixed-roof, internal floating-roof, external floating-roof, variable vapor
space, and pressure. It is estimated that in 1977 there were a total of 27,540
volatile organic liquid storage tanks nationwide.!
A typical fixed-roof tank consists of a cylindrical steel shell with a
permanently affixed roof. An internal floating-roof tank has both a perma-
nently affixed roof and a cover that floats on the liquid surface (contact
roof), or that rests on pontoons several inches above the liquid surface
(noncontact roof), inside the tank. This roof rises and falls with the
liquid level. The floating roof commonly incorporates flexible perimeter
seals or wipers which slide against the tank wall as the roof moves up and
down. An external floating-roof tank consists of a cylindrical steel shell
equipped with a deck or roof which floats on the surface of the stored liquid,
rising and falling with the liquid level. A seal (or seal system) attached
to the roof, contacts the tank wall to cover the small annular space between
the roof and the tank wall and slides against the tank wall as the roof is
raised or lowered. Variable vapor space tanks are equipped with expandable
vapor reservoirs to accommodate vapor volume fluctuations attributable to
temperature and barometric pressure changes. There are two classes of pressure
tanks, low pressure (2-15 psig) and high pressure (up to 250 psig or higher).
Pressure tanks are used for storage of organic liquids with high vapor pres-
sures and are found in many sizes and shapes depending on the operating range
of the tanks.
B. Emission Sources and Factors
Two types of emissions from fixed-roof tanks are breathing losses and
working losses. The expansion of vapors in the tank due to changes in ambient
temperature and pressure result in VOC emissions termed "breathing losses."
VOC emissions termed "working losses" result from vapors emitted from a tank
as a result of filling and emptying operations. The total annual VOC emis-
sions from a fixed-roof storage tank would be the sum of the breathing and
working losses. The total annual VOC emissions from a large diameter (10-
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meter) and a small diameter (7 meter) fixed-roof storage tank are presented
in Table 4.3.2.1.2
The emission estimates presented throughout this section are calculated
using current emission formulae as presented in the fourth edition of the EPA
Publication AP-42.3 The emission factor equation for fixed-roof tank
breathing losses is based on test data collected by the Western Oil and Gas
Association, the Environmental Protection Agency, and the German Society for
Petroleum Science and Carbon Chemistry. A comparison was made between the
new test data in these reports and the breathing losses calculated by using
the 1977 version of the emission factor equation in AP-42. It was determined
from this comparison, that the emission factor equation for fixed-roof
breathing losses tended to over-predict and was therefore scaled downward.**
The American Petroleum Institute sponsored a program to develop additional
laboratory, pilot tank "arid field tank data on evaporative losses from internal
and external floating-roof tanks. The mechanisms of evaporative loss were
investigated and the effects of relevant variables were quantified, which
resulted in the formulation of the current AP-42 emission factor equations.5.6
External and internal floating-roof tanks have similar sources of VOC
emissions, known as "standing storage losses" and "withdrawal losses".
Standing storage losses or seal losses for both external and internal floating-
roofs can be the result of an improper fit between the seal and the tank wall
which causes some of the liquid surface to bfe exposed to the atmosphere.
Internal floating-roof tanks can also have standing storage losses through
the openings in the deck required for various types of fittings (fitting
losses); and through the nonwelded seams formed when joining sections of the
deck material (deck seam losses). Withdrawal loss is the vaporization of
liquid that clings to the tank wall and is exposed to the atmosphere when a
floating roof is lowered by withdrawal of liquid. Thus, the total annual VOC
emissions from either an external floating-roof storage tank or an internal
floating-roof storage tank would be the combination of the standing storage
loss and withdrawal loss. The total annual VOC emissions from a large and a
small diameter internal floating-roof storage tank, equipped with a liquid-
mounted primary seal, a bolted deck and controlled fitti'ngs are also shown in
Table 4.3.2.1.2
VOC losses occur in low pressure tanks during withdrawal and filling
•*-60
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TABLE 4.3.2.1. FIXED ROOF TANK EMISSIONS AND EMISSION REDUCTIONS
OBTAINED WITH AN INTERNAL FLOATING ROOF3
(Cyclohexane at 2.0 psi TVP)
Capacity
(m )
Di ameter
(m)
Turnovers
FRT
Emissions
(Mg/yr)
IFRT1m
Emissions
(Mg/yr)
Emi ssi on
Reduction
(Mg/yr)
Percent
Reducti<
200
7.0
20.0
2.54
0.37
2.17
85.6
200
7.0
40.0
4.47
0.37
4.10
91.7
1,000
10.0
10.0
6.81
0.49
6.31
92.8
1,000
10.0
20.0
11.64
0.50
11.14
95.7
Reference 2.
Nomenclature explanation - FRT = Fixed-roof tank, IFRTim = Internal floating-
roof tank (with a liquid-mounted primary seal and controlled fittings).
TABLE 4.3.2.2. CAPITAL AND ANNUALIZED COST FOR AN INTERNAL FLOATING ROOF
INSTALLED IN A NEW FIXED-ROOF TANK3
(second quarter 1984 dollars)
Capacity
(m3)
Di ameter
(m)
Turn-
overs
Total
Capital Cost
($/Tank)
Total
Annualized Cost
($/year)
Net
Annualized Costb
($/year)
200
7.0
20.0
10,798
2,948
1,982
200
7.0
40.0
10,798
2,948
1,123
1,000
10.0
10.0
15,015
4,100
1,290
1,000
10.0
20.0
15,015
4,100
(859)c
Reference 2.
bBased on a product recovery credit of $0.35/liter for cyclohexane.
cNet annualized savings.
4-bl
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operations when the pressure of the vapor space exceeds the pressure-vacuum
vent setting and vapors are expelled. High pressure tanks are considered
closed systems, with virtually no emissions. In the case of variable vapor
space tanks, filling losses result when vapor is displaced by liquid during
filling operations. Loss of vapor occurs only when the vapor storage capacity
of the variable vapor space tank is exceeded.
C. Control Techniques and Emission Reductions
Several methods are available to control VOC emissions from fixed-roof
tanks: (1) the installation of an internal floating-roof and seal system,
(2) a vapor recovery system (e.g., refrigerated vent condensers, carbon
adsorption), and (3) vapor destruction system (thermal oxidation). The
emission reduction and percentage reduction which may be obtained with an
internal floating-roof tank over a fixed-roof tank are shown in Table 1.2
A carbon adsorption vapor control system is estimated to reduce VOC emissions
by approximately 98 percent.® A thermal oxidation vapor control system is
estimated to reduce VOC emissions by approximately 98 percent.Standing
storage loss emissions from external and internal floating-roof tanks are
controlled by one or two separate seals. The first seal is called the primary
seal, and the other, mounted above the primary seal, is called the secondary
seal. There are three basic types of primary seals: (1) mechanical (metallic
shoe), (2) resilient (nonmetallic either vapor-mounted or liquid-mounted),
and (3) flexible wiper. A primary seal serves as a conservation device by
closing the annular space between the edge of the floating-roof and the
tank wall. Two types of secondary seal are currently available, shoe-
mounted and rim-mounted. A liquid-mounted primary seal has a lower
emission rate and thus a higher control efficiency than a vapor-mounted
seal. Metallic shoe seals are commonly employed only on external floating-
roof tanks and are more effective than vapor-mounted seals, but less
effective than liquid-mounted seals. A secondary seal, be it in conjunction
with a liquid- or vapor-mounted primary seal, provides an additional level
of control.
D. Regulatory Status
The EPA proposed NSPS in 1984 (40 CFR 60 Subpart Kb) to control VOC
emissions from storage of volatile organic liquids. Currently some State and
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local regulations have adopted petroleum storage tank CTG recommendations for
control of VOC emissions from VOL storage tanks. The NSPS requires one of
the following: (1) a fixed-roof in combination with an internal floating-
roof which incorporates either a liquid-mounted primary seal or two seals
(primary and secondary) where the primary seal may be vapor-mounted and
controlled fittings; (2) an external floating-roof tank with a liquid-
mounted or metallic shoe seal and a continuous rim secondary seal (other
detailed specifications are also required and may be read in the regulation);
and (3) a closed vent system and a control device to reduce VOC emissions by
95 percent or greater. The requirements described above will apply to each
storage tank either with a design capacity greater than or equal to 151 m3
(40,000 gal) containing a VOL that has a maximum true vapor pressure equal to
or greater than 3.5 kPa (0.5 psia) but less than 76.6 kPa (11.1 psia) or a *
storage tank with a design capacity greater than or equal to 75 m3 (20,000
gal) but less than 151 m3 (40,000 gal) containing a VOL that has a maximum
true vapor pressure equal to or greater than 27.6 kPa (4.0 psia) but less than
76.6 kPa (11.1 psia). The NSPS additionally requires a closed vent system
and control device to reduce VOC emissions by 95 percent or greater for storage
tanks with a design capacity greater than or equal to 75 m3 (20,000 gal)
which contains a VOL that has a maximum true vapor pressure greater than or
equal to 76.6 kPa (11.1 psia).
E. Current National Emission Estimates
Total annual VOC emissions from volatile organic liquid storage tanks has
been estimated at 37,800 Mg/yr in 1983, based on 1977 tank population data and
current State and local control levels. This emissions total includes an estimated
34,000 Mg/yr of VOC emitted by fixed-roof tanks and an estimated 3,800 Mg/yr of
VOC from floating-roof tanks.®
F. Capital and Annual Control Costs
The capital and net annualized cost to install an internal floating-roof
roof equipped with a liquid-mounted primary seal on new fixed-roof tank, for
either a small or a large size tank, is shown in Table 4.3.2.2.2
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G. • References
1. VOC Emissions from Volatile Organic Liquid Storage Tanks - Back-
ground Information for Proposed Standards. U.S. Environmental Protection
Agency, Office of Air Quality Planning and Standards, Research Triangle Park,
North Carolina. EPA-450/3-81-003a. July 1984. p. 3-2.
2. Memorandum. Gschwandtner, K., Pacific Environmental Services, Inc.,
to S. Shedd, U.S. EPA. Derivation of Cost Emissions and Emission Reductions
presented in the VOC Control Techniques Document. January 1986.
3. Compilation of Air Pollutant Emission Factors - Fourth Edition.
U.S. Environmental Protection Agency, Office of Air Quality Planning and
Standards, Research Triangle Park, North Carolina. AP-42. September 1985.
4. Petroleum Liquid Storage Vessels - Revision of AP-42 - Background
Document, EPA Contract No. 68-02-3063, TRW Environmental, Inc., Research
Triangle Park, North Carolina, May 1981.
5. Evaporation Loss from Internal Floating-Roof Tanks, Third Edition,
Bulletin No. 2519, American Petroleum Institute, Washington, D.C., 1983.
6. Letter from McLaughlin, Nancy D., U.S. Environmental Protection
Agency to D. A1lor, TRW, Inc. Comments on the benzene storage model plants
package. May 3, 1979.
7. Letter and attachments from D.C. Mascone, EPA/CPB, to J.R. Farmer,
EPA. June 11, 1980. Memo concerning thermal incinerator performance for NSPS.
8. U.S. Environmental Protection Agency. Organic Chemical Manufacturing
Volume 4: Combustion Control Devices. Research Triangle Park, North Carolina.
Publication No. EPA-450/3-80-026. December 1980.
9. Reference 1, p. 3-35.
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4.3.3 SOCMI Equipment Leaks
A. Process and Facility Description
The synthetic organic chemical manufacturing industry (SOCMI) is
comprised of facilities engaged in the production of one to several organic
chemicals using one or more processes. These chemicals may represent final
products or intermediate products which serve as feedstocks to yet other
processes. There are over 2,000 chemical plants (as of 1984) operating in the
United States. The 359 chemicals listed in the Organic Chemical Producers
Data Base developed by EPA* represent the types of compounds manufactured by
the industry.
B. Emission Sources and Factors
Emissions of VOC from the SOCMI can result when process fluids (either
gaseous or liquid) leak from plant equipment. Potential leaking equipment
include: pumps, compressors, valves, pressure relief devices, open-ended
lines, sampling systems, and flanges and other connectors. Emission factors
for process equipment presented in Table 4.3.3-1 have been developed based on
the results of several source testing studies. Emissions from SOCMI process
units can be estimated by multiplying the number of equipment pieces times
the emission factors specific to the type of equipment. SOCMI process unit
baseline emissions may range from about 30 to 300 Mg/yr depending upon the
complexity (number and types of equipment) of the unit.2 Emissions from the
SOCMI equipment leaks are discussed in the background information documents
for the proposed! and promulgated^ new source performance standards (NSPS)
for SOCMI and an additional information document on fugitive emissions of
organic compounds.3
C. Control Techniques and Emission Factors
Two approaches are available to control SOCMI equipment leaks of VOC:
(1) a leak detection and repair program and (2) the installation of specific
controls or leakless equipment. The emission reduction efficiency of leak
detection and repair programs is dependent upon a number of factors including:
(1) the monitoring method (visual, instrument, or soap solution); (2) leak
definition; (3) frequency of inspections; (4) the time interval allowed
between leak detection and subsequent repair; and (5) the emission reduction
achieved by each successful repair. The control efficiencies of leak detection
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and repair programs are presented in Table 4.3.3-1. The control estimates
are based on available data on the occurrence and recurrence of leaking
equipment and on the effectiveness of leak repair that are used in a model
program that predicts control effectiveness using recursive equations developed
for evaluating leak detection and repair programs. Control equipment can
achieve control efficiencies approaching 100 percent. Examples of equipment
controls include: (1) venting emissions from pressure relief devices, pumps,
and compressors to a control device (e.g., flare or process heater); (2) dual
mechanical seals with barrier fluid systems for pumps and compressors; (3) •
caps, plugs, or second valves on open-ended lines; (4) closed purge sampling
systems; and (5) sealed bellows valves.
Table 4.3.3-1. Emissi.on Factors And Control Effectiveness3
Controlled Emissions
Equi pment
Type/Service
Average
Quarterly Monitoring
Monthly Monitoring
Emi ssion
Emi ssion
Percent
Emi ssion
Percent
Factor,
Factor,
Reducti on
Factor,
Reducti on
kg/hr
kg/hr
kg/hr
Valves -
Ga s
0.0056
0.0020
0.64
0.0015
0.73
Light Liquid
0.0071
0.0040
0.44
0.0029
0.59
Pumps - Light
Li quid
0.0494
0.0333
0.33
0.019
0.61
Pressure Relief
Devices - Gas
0.104
0.0580
0.44
"References 3 and 4
D. Regulatory Status
The EPA set NSPS on October 18, 1983, (40 CFR 60 Subpart VV) and issued
a CTG in April 1984 to control equipment leaks of VOC in the SOCMI. The CTG
recommends quarterly leak detection and repair for pumps, valves, compressors,
and safety relief valves. Pumps would also be visually inspected weekly.
The CTG recommends installation of caps on open-ended lines. The NSPS
requires monthly leak detection for valves in gas/vapor and light liquid
service. Pressure relief devices are subject to a no detectable emissions
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limit, compressors are to be equipped with a barrier fluid seal system that
prevents leakage of VOC to atmosphere, sampling lines require closed purge
systems and open-ended lines should be capped. About half of the existing
facilities are estimated to have implemented controls recommended by the CTG
as required under State or local regulations. By the end of 1984, 645 SOCMI
process units are projected to be subject to the NSPS.l
E. Current National Emissions Estimates
Total annual VOC emissions from the SOCMI in 1984 has been estimated at
148,000 megagrams. This estimate was derived by multiplying the total
estimated number of SOCMI process units by process unit emission estimates.
The nationwide emission estimate assumes that half of the process units are
located in nonattainment areas.2.5
F. Capital and Annual Control Costs'
Capital and annual costs for controlling SOCMI equipment leaks are
presented in Table 4.3.3-2 for a small and large process unit to comply with
State and local regulations (based on reference 2 recommendations) and NSPS
requirements. These costs are estimated based upon control costs for individual
equipment type multiplied by the number of each type of equipment in the
process unit. The costs presented also include expenditures incurred for
monitoring instruments.3
Table 4.3.3-2. Capital And Annual Costs To
Control SOCMI Equipment Leaks
Costs ($1,000)
CTGa
NSPSb
Capital Cost
Small Unitc
19.7
31.3
Large Unit
113
219
Annual Cost
Small Unit
6.8
• 12.6
Large Unit
2.9
67.7
Reference 4.
Reference 2.
CA small and large unit correspond to Model Units A and C,
respectively, from References 2 and 4.
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6. References
1. VOC Fugitive Emissions in Synthetic Organic Chemicals Manufacturing
Industry - Background Information for Proposed Standards. U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina. EPA-450/3-80-033a.
November 1980.
2. VOC Fugitive Emissions in Synthetic Organic Chemicals Manufacturing
Industry - Background Information for Promulgated Standards, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina. EPA-450/3-80-033b.
June 1982.
3. Fugitive Emission Sources of Organic Compounds -- Additional Information
on Emissions, Emission Reductions, and Costs. U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina. EPA-450/3-82-010. April
1982.
4. Guideline Series - Control of Volatile Organic Compound Leaks from
Synthetic Organic Chemical and Polymer Manufacturing Equipment. U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina.
EPA-450/3-83-006. March 1984.
5. Memorandum. Rhoads, T., Pacific Environmental Services, Inc., to
S. Shedd, U.S. EPA. Derivation of Cost, Emissions, and Emission Reductions
presented in the VOC Control Techniques Document. November 1985.
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4.3.4 VOL TRANSFER OPERATIONS1
A. Process and Facility Description
Volatile organic liquids (VOL) are transported from production facilities
and bulk terminals to packaging plants, other processing plants, and users
and bulk terminals by ships, barges, tank trucks and rail cars. Although
motor gasoline is a VOL, it is not included in this discussion. (See Section
4.2 of this chapter.) Over 7,000 organic chemicals are being produced today.
However, a small percentage of these compounds constitutes the major of
industries output. Roughly 67 percent of the total production is represented
by the top 50 chemicals produced. No data is available on the number or size
of the organic chemical loading facilities.
B. Emission Sources and Factors
Emissions from transfer operations occur when organic chemicals being
loaded displaces the vapors in the tank and forces the vapors to the atmosphere.
Transfer losses are dependent on the condition of the tank before loading,
loading method, product and tank temperature and vapor pressure of the product
being loaded or previously loaded. No published reports have been found that
presents a listing of emission factors for the variety of chemicals loaded.
From industry contacts there seemed to be a consensus that most VOL'S are
being submerged filled, and vehicle tanks are in dedicated service or
are usually cleaned before switching to other products. Also, if the VOL is
a gas, loadings are performed under pressure and no emissions should occur.
According to the above description of loading techniques and condition of
tanks before loading and review of the information contained in AP-422, most
vapor spaces in tank carrying VOL'S would be 50 to 100 percent saturated.
Transfer emissions then can be calculated using the ideal gas law.
C. Control Techniques and Emission Reductions
Control technology utilized to minimize emissions during tank truck
loading includes: (1) switching from top loading to submerged loading, and
(2) collecting displaced vapors, and routing the vapors to a vapor processor.
Converting the loading equipment from top splash to submerged loading will
reduce emissions by approximately 60 percent. Vapor processors - thermal
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oxidizers, refrigeration, carbon adsorbers - should reduce emissions to better
than 90 percent. A very small number of vapor processors (mostly thermal
oxidizers) have been demonstrated on this source of emissions.
0. Regulatory Status
The EPA has not developed any guidance documents or have standards under
development on this source. A few States and local agencies have requirements
requiring 90 percent control at high throughput loading facilities.
E. National Emission Estimates
The loading of ships, barges, rail cars, and tank trucks is estimated to
emit from 4,700 to 9,400 megagrams (5,200 to 10,400 tons) of V0C in 1983.3
This estimate is based'on the most recent production estimates for the top 50
organic chemical produced, and emission factors calculated using the ideal
gas law and assuming a 50 to 100 percent saturation of the air-vapor volume
being expelled from the tanks being loaded.
F. Capital and Annual Control Costs
No capital or annual control costs have been estimated at this time,
however, control costs for thermal oxidizers should be simliar to those
available in EPA documents for gasoline bulk terminals.4
G. References
1. Memorandum from Shedd, S., U.S. EPA/0AQPS to Durham, J., U.S. EPA/0AQPS,
Pre-Phase 1 Report for VOL Transfer, August 27, 1982.
2. Transportation and Marketing of Petroleum Liquids. In: Compliation of
Air Pollution Emission Factors, U.S. Environmental Protection Agency, Research
Triangle Park, AP-42, July 1979.
3. Memorandum from Shedd, S., U. S. EPA/0AQPS to Branch File, File
#84/21 - V0C CTD, Emission Estimate Update to August 27, 1982, Pre-Phase 1
Report for VOL Transfer, May 1985.
4. Bulk Gasoline Terminals - Background Information for Proposed
Standards--and Promulgated Standards, U.S. EPA, RTP, North Carolina, EPA
450/3-80-038 a and b, December 1980 and August 1983.
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4.4. INDUSTRIAL PROCESSES
4.4.1 Paint And Varnish Manufacturing
A. Process Description
The manufacture of paint and varnish requires three general steps.
First, reactive organic compounds of low molecular weight called monomers
are reacted or polymerized with the aid of heat and catalysts to produce
a resin. In the second step the resin is developed further by reacting
or "cooking" it with certain oils, or fatty acids or alcohols. Solvent
is added to reduce the viscosity, and the resulting mixture is called the
"vehicle." The third and final step is to blend pigments, driers and
other additives with the resin or resin vehicle and make final viscosity
adjustments for storage. Varnishes are generally not pigmented but they
may contain dyes or stains. *
There are approximately 1,100 coating manufacturers; however, the top
15 firms account for 48 percent of the sales. The Bureau of Census has
reported that 1.5 million cubic meters (410 million gallons) of original
equipment coatings and 2.2 million cubic meters (590 million gallons) of
architectural coatings and 0.6 million cubic meters (154 million gallons)
of special purpose coatings were shipped during 1984.2
B. Emission Sources and Factors
VOC emissions occur from all three manufacturing steps identified
above. Over the last decade the resin and varnish base cooking has
migrated to the chemical plants that polymerized the resins. Emissions
from these steps will therefore not be covered in this section. The
manufacture of polymers and resins and related emissions and controls is
covered in more detail in Section 4.4.5.
Emissions from grinding mixing, blending and final thinning of the
paint or varnish occur usually from filling or charging the vessels, or
as fugitives from leaking valves, and covers or charging ports left open
inadvertently. Thinning tanks venting directly to atmosphere might emit
6 to 80 Mg/yr depending on size, frequency of charging solvents used,
agitation rate and temperature. The remainder of the processes would
4-71
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collectively contribute approximately half that amount. One estimate for
a medium size paint plant has been put at 28 Mg VOC per year.
C. Control Techniques and Emission Reduction
Thinning tanks may be equipped with condensers that reduce emissions
by over 95 percent during filling and agitation. The remaining emission
reduction will depend on improving "housekeeping" measures such as repair
of leaking valves and keeping lids and charging portholes closed and
sealed.
A substantial reduction in emissions has and will continue to occur
as an indirect result of EPA regulating VOC emissions from paint users.
To comply with regulations, industrial paint users must use abatement
equipment or coatings that release less solvent and other VOC when dried
or cured. The latter is usually less capital intensive and often more
desirable to the paint user. Resin and paint manufacturers have responded
by developing low solvent paints for many end uses. Assuming that emissions
from paint manufacturing are proportinal to the total solvent used by the
paint manufacturing process, reduction of 30 to 95 percent have been
achieved depending on the company's success at supplying new low solvent
coati ngs.
D. Regulatory Status
The Agency has developed or assisted the States to develop numerous
regulations for companies that apply paint, varnishes, and inks. All have
resulted in indirect pressure on the manufacturers to develop new products
which contain significantly less solvent. This will dramatically reduce
the amount of solvent which each manufacturer processes and, again indirectly,
reduce its emissions. The Agency has thus encouraged maximum expenditure on
research and minimum investment in hardware which would become less, and
perhaps prohibitively cost effective as solvent throughput through a
plant decreases. Some States may limit the maximum daily emissions from
a plant, others may choose to require leak detection and repair programs
as discussed on page 4-18, or they may merely require good housekeeping
measures such as tops or lids on all vessels.
4-72
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E. National Emission Estimates
It is estimated that approximately 12,000 Mg VOC are emitted yearly.3
F. Capital and Annual Control Cost
Condensers, seals and other devices that restrict fugitive emissions
(hence might be construed as control devices) are usually part of the
process equipment. They are installed as safety and cost saving features,
their role in of VOC controls is usually incidental. For that reason,
capital and annualized control costs are considered negligible or non-
existent for VOC control purposes.
G. References
1. Air Pollution Control Engineering and Cost Study of the Paint
and Varnish'Industry, U.S. Environmental Protection Agency, EPA-450/3-74-031,
June 197 4.
,2. American Paint & Coatings Journal, April 29, 1985, page 9.
3. Memorandum from Crumpler, 0., U.S. Environmental Protection
Agency, to ESED File No. 84/21, Estimation of VOC Emissions from Paint
Manufacturing and Reduction of Emissions due to Production of Low Solvent
Coatings, May 31, 1985.
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4.4.2 Vegetable 011 Processing
A. Process and Facility Description
In the United States, nearly all vegetable oil 1s extracted from
soybeans, cotton, corn or peanuts. The processes and equipment used to
manufacture vegetable oil are generally the same regardless of the type of
seed being processed. The seed 1s cracked, dehulled and cooked before
mechanically pressed to remove a portion of the oil prior to solvent extrac-
tion. The most common solvent used 1n commercial edible oil extraction
systems 1s hexane. After solvent extraction, hexane and oil are separated
by distillation and hexane is removed from the meal in a desolventlzer
toaster. Following desolventizatlon, the meal 1s dried, cooled, ground and
stored for transport. Following distillation, the vegetable oil is collected
for refining while the sol vent-water vapor is condensed, decanted, and the
solvent is recycled for further use.. Fresh solvent is added to the recycled
solvent to replenish solvent lost during the process.
B. Emission Sources and Factors
Since soybean oil constitutes over 80 percent of the vegetable oil
market most studies of emissions from vegetable oil manufacturing have been
limited to soybean oil production. Therefore, the remainder of this section
will apply directly to soybean oil but can generally be applied to all
vegetable oil manufacturing.
Solvent vapors from the solvent extraction, distillation unit, solvent-
water separator, solvent work tank and other indirect sources are transported
by a blower to the main vent. The predominant technique for solvent recovery
from the main vent is a cool water condenser followed by a mineral oil
scrubber.
Assuming that all hexane lost during the process 1s eventually emitted
to the atmosphere, the emission factor for soybean processing can be determined
from solvent Inventories. The average solvent loss for. 64 plants operating
1n 1979 was 0.9 gallons per metric ton of soybeans processed.* The emission
factor for soybean manufacturing is 2.3 kilograms VOC per metric ton of
soybeans processed.
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An approximate break-down of hexane loss by source is 5 percent from
the main vent following the mineral oil scrubber, 41 percent from the meal
dryer vent and 3 percent from the cooler vent. Approximately 2 percent of the
hexane is lost to the crude oil that goes to refining and 27 percent is lost
to the finished meal. Fugitive losses are estimated to be 22 percent of the
total hexane lost to the atmosphere.2
C. Control Techniques and Emission Reductions
The three processess in soybean oil manufacturing plants that are amenable
to control are the dryer, the cooler, and the main vent following a scrubber.
These facilities all have ducted emissions. Currently, there are no plants
controlling VOC from these vents. Both carbon adsorption and incineration
have been investigated as control devices, but the National Soybean Processors
Association (NSPA) doesn't consider either of these devices to be acceptable
due to fire hazard. However, several well-operated modern soybean processing
plants that have reduced fugitive emissions and reduced the amount of hexane
in the meal leaving the desolventizer toaster report operating at an overall
hexane loss of 1.4 kilograms per metric ton of soybeans processed.2
D. Regulatory Status
The EPA issued a CTG in 1978 recommending a control device on the
main vent (e.g., mineral oil scrubber) and a control device on the dryer/cooler
vent (e.g., carbon adsorber or incinerator).^ in 1979, the CTG was rescinded
pending further information that was to be provided upon completion of
the field testing for the New Source Performance Standard (NSPS) project.*
But in 1980 all work was discontinued on the NSPS for VOC and particulate
emissions from soybean oil extraction plants because no demonstrated control
technology could be identified.4
E. National Emission Estimates
In 1980, eighty-nine soybean processing plants were in operation with
a total capacity of 96,500 metric tons per day.5 It was estimated that
80 percent of the capacity was utilized. The national emission estimate
for soybean processing plants in 1980 is 64,800 metric tons of VOC.
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F. References
1. Taken from confidential information received by EPA in 1979.
2. VOC and Particulate Emissions from Soybean Oil Extraction Plants -
Background Information, Draft Chapter 6, April 1980. U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
3. Control of Volatile Organic Emissions from Manufacture of
Vegetable Oils - Guideline Series. U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina. EPA 1450/2-78-035, June 1978.
4. Memo from Farmer, J. R., USEPA, to Don R. Goodwin, USEPA. July
2, 1980. Recommendation Memo - New Source Performance Standards for Soybean
Oil Extraction Plants.
5. Memo from Parker, C. D., Research Triangle Institute, to Richard
Burr U. S. EPA. May 27, 1980. Review of TRC Environmental Consultants
Report, "National Vegetable Oil Processing Plant Inventory."
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4.4.3 Pharmaceuticals Manufacture
A. Process and Facility Description
The pharmaceutical industry processess thousands of individual products
including drugs, enzymes, hormones, vaccines, and blood fractions. There are
approximately 800 pharmaceutical plants producing drugs in the United States
and its territories. Production activities can be divided into the following
four categories: chemical synthesis, fermentation, biologicals and botanicals,
formulation, and packaging.
Synthetic pharmaceuticals are typically manufactured in a series of
batch processes. Solid reactants and solvents are charged to a washed reactor
where they are held, and sometimes heated. After the reaction is complete,
any remaining unre'acted volatile compounds and solvents are removed from the
reactor by distillation and condensed. The pharmaceutical product is then
transferred to a holding tank. Subsequent steps include washing, drying, and
crystallization.l
Fermentation processes use microorganisms to produce certain pharmaceuticals,
such as antibiotics. In these instances the reactor contains an aqueous
nutrient mixture with living organisms such as fungi or bateria. The crude
antibiotic is recovered by solvent extraction and is purified by essentially
the same methods described above for chemically synthesized pharmaceuticals.
Biologicals and botanicals include pharmaceuticals produced by extraction
from plant or animal tissues. Insulin i^a biological drug extracted from
hog or beef pancreas. The extraction process involves the use of a solvent.
Formulation and packaging consists of the formulation of bulk chemicals
into tablets, capsules, ointments, and liquids. VOC emissions can occur
during tablet drying and coating.
Organic chemicals are used as raw materials and as solvents. Typical
chemicals include methanol, ethanol, isopropanol, acetone, acetic anhydride,
methylene chloride, chloroform, amylacetate, cyclohexylamine, and toluene.
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B. Emission Sources and Factors
When solvent is used in the manufacture of a pharmaceutical product,
each step of the manufacturing process may be a source of solvent emissions.
An approximate ranking of emission sources has been established for the
synthesized pharmaceutical category. In the following list, the first four
sources typically account for the majority of emissions: (1) dryers, (2)
reactors, (3) distillation units, (4) storage and transfer, (5) filters, (6)
extractors, (7) centifuges, and (8) crystallizers.l For the three other
pharmaceutical categories, emissions are primarily associated with dryers,
coaters, and extractors. Emission rates for uncontrolled reactors can vary
from 0.0001 Mg/yr to 10 MG/yr (.00011 tons/yr to 11 tons/yr). Reference 1
presents emission rates for a variety of processes and operations.
C. Control Techniques and Emission Reductions
Applicable controls for all of the emission sources except storage and
transfer are the following: condensers, scrubbers, and carbon adsorbers.
Storage and transfer emissions can be controlled by the use of vapor return
lines, conservation vents, vent scrubbers, pressurized storage tanks, and
floating roof storage tanks. Thermal incinerators are a control option in
certain instances. They are sometimes used in the industry to control odors
from fermentation vessels. Although control efficiencies will vary with the
specific process, greater than 90 percent control has been demonstrated.2
D. Regulatory Status
The EPA issued a CTG for synthesized pharmaceutical products in 1978.
The CTG recommends regulation on a plant-by-plant basis after identification
of operations with significant emissions.
Where an individual approach is not practical, the CTG presents guidelines
for a generalized control program. The guidelines can be briefly summarized
as follows:
1. For each vent from reactors, distillation operations, crystal 1izers,
centrifuges, and vacuum dryers that emit 6.8 kg/day (15 lb/day) or more of
V0C require surface condensers or equivalent controls. (Maximum condenser
outlet gas temperatures are specified.)
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2. For air dryers and production equipment exhaust systems that emit
150 kg/day (330 lbs/day) or more of VOC, require 90 percent emission
reduction. For air dryers and production equipment exhaust systems that emit
less than 150 kg/day (3.30 lbs/day), required emission reduction to 15 kg/day
(33 lbs/day).
3. Pressure/vacuum conservation vents on tanks storing VOC with vapor
pressure greater than 10 kPa (1.5 psi) at 20°C.
4. Ninety percent effective vapor balance or equivalent on deliverys to
all tanks greater than 7,500 liters (2,000 gallons) for VOC liquids with
vapor pressure greater than 28 kPa (4.1 psi) at 20°C.
5. Enclose all centrifuges and filters processing liquids with VOC
vapor pressure of 3.5 kPa (0.5 psi) or more at 20°C.
6. All in-process tanks shall have covers.
9
7. For liquids containing VOC all leaks should be repaired as soon as
practical.
E. National Emission Estimates
The manufacture of ethical (i.e., prescription) pharmaceuticals was
estimated to emit 50,000 Mg/yr (55,000 tons/yr) of VOC in 1975. No data are
available for proprietary (i.e., over-the-counter) pharmaceuticals. Seventy-
three percent of the total emissions were attributed to chemical synthesis
operations.^
F. Capital and Annual Control Costs
For a carbon adsorption system sized for 250 Kg/hr (550 lb/hr) VOC from
a dryer, captial costs are $540,000 (in 1984 dollars). If the adsorber
operates 16 hours per day, 7 days per week, annualized costs are $23,000 (in
1984 dollars).
Capital costs for a conservation vent on a 38 m^ (10,000-gal1 on) storage
tank are $700 (in 1984 dollars). Annualized costs without VOC recovery credits
are $180. Credits for VOC emitted are dependent upon tank diameter but may
be large enough to reduce the total annualized cost to a credit.
Chapter 5 of Reference 1 presents costs for a variety of control devices.
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G. References
1. Guideline Series: Control of Volatile Organic Emissions from
Manufacture of Synthesized Pharmaceutical Products, U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina, EPA-450/2-78-029,
December, 1978.
2. Richard Crume, EPA, "Recommendation for Continuing Study of the
Pharmaceutical Industry, "Memo to Robert Rosensteel, EPA, November 24, 1982.
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4.4.4 Rubber Products Manufacture
4.4.4.1 Styrene-Butadiene Copolymer Manufacture
A. Process and Facility Description
Styrene-butadiene copolymers(SBC) are used extensively in the manufacture
of rubber tires, dipped goods, carpet underlay, adhesives, moldings, paper
coatings, paints, and carpet back sizing. Most manufacturers use an emulsion
polymerization process which provides an aqueous medium as a reaction site
for the styrene and butadiene monomers. Emulsion products are sold in
either a solid form, known as crumb, or a liquid form, known as latex. Crumb
products are typically produced continuously in a train of reactors. Latex
products are usually polymerized in a batch process.
B. Emission Sources and Factors
Table 4.4.4-1 presents^ emissions for an emulsion crumb model plant pro-
ducing 136,000 Mg/yr (150,000 tons/yr) and an emulsion latex model plant
producing 27,000 Mg/yr (30,000 tons/yr).
C. Control Techniques and Emission Reductions
Control techniques for the SBC industry include both add-on air pollution
control devices and process modification. Applicable add-on equipment includes
carbon adsorption, condensers, thermal and catalytic incinerators, and the
compression of organic vapors into fuel manifolds. Applicable process
modification consists of optimizing the steam stripping step in the emulsion
crumb polymerization process.
D. Regulatory Status
No regulations have been issued on styrene-butadiene copolymers.
E. National Emission Estimates
No data are available on current V0C emissions associated with the
manufacture of SBC.
F. Capital and Annual Control Costs
Installed capital costs represent total investment to install a thermal
incinerator equipped with heat exchanges (70 percent recovery). Installed
capital costs for the emulsion crumb model plant (see Table 4.4.4-2) are
$360,000 (in 1984 dollars). Installed capital costs for the emulsion latex
plant is $380,000 (in 1984 dollars). Annualized costs for the emulsion crumb
and emulsion latex plants are $110,000 and $120,000, respectively (in 1984
dollars).
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Table 4.4.4-1 Model Plant VOC Emissions
Process VOC Emissions
Production Rate Facility Mg/yr
Emulsion crumb Monomer Recovery - absorbent 35
136,000 Mg/yr Coagulation/blend tanks 57
Dryers 328
Emulsion Latex Monomer removal - butadiene 224
27,000 Mg/yr Monomer removal - styrene 4
Blend tanks 3
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G. References
1. U.S. Environmental Protection Agency. Control of Volatile Organic
Compound Emissions from Manufacture of Styrene-Butadiene Copolymers. Prelim-
inary Draft. Research Triangle Park, North Carolina. April 1980.
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4.4.4.2 Pneumatic Rubber Tires
A. Process and Facility Description*
The tire manufacturing process generally consists of four main
steps: (1) compounding of raw materials, (2) transforming the raw
materials into tire components and preparing the components for assembly,
(3) assembling the components, (tire building), and (4) molding, curing
and finishing of the assembled components into the final product. Each
of these steps is a potential*source of VOC emissions.
During compounding, raw crumb rubber is combined with fillers, extend-
ers, accelerators, antioxidants and pigments. This mixture is then trans-
ferred to roll mills which knead the material and form it into sheets.
Tire components are made in several parallel operations. Rubber
stock and other raw materials, including wire and fabric, are used to
make tire tread, sidewalls, cords, belts and beads. The major source of
VOC emissions during this step is the evaporation of VOC's from solvent-based
cements. A detailed presentation of the various operations in can be
found in Chapter 3 of Reference 1.
Tire building is the assembly of the various tire components to
form an uncured or "green" tire. The assembly takes place on a collapsible,
rotating drum. Organic solvents may be applied to some tire components
in this step to further "tacklfy" (make sticky) the rubber.
Green tires are then sprayed on the inside with lubricants and on
the outside with mold release agents before molding and curing in automatic
presses. Curing usually takes 20 to 60 minutes at a temperature of 100°C
to 200°C. The cooled tire is finished with buffing and grinding operations.
In 1984, the rubber tire manufacturing industry consisted of
approximately 60 plants nationwide.
B. Emission Sources and Factors*
Each of the four production steps may include one or more sources
of VOC emissions. A detailed discussion on the individual emission
sources and their estimated emission factors is provided in Reference 1.
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Organic solvent-based green tire spraying, undertread cementing, sidewall
cementing, tire building, tread end cementing, and bead cementing contribute
97 percent of the total VOC's emitted from tire production.
C. Control Techniques and Emission Reductions*
Emission control by either incineration or carbon adsorption is
applicable to undertread cementing, sidewall cementing, automatic or
manual tread end cementing, bead cementing and green tire spraying. With
an 80 percent efficient capture system, emission reductions of 75 percent
can be attained for each of these processes.
In addition to add-on control technology, there are low solvent
use techniques which are applicable to several processes. Limiting the
amount of solvent used during tread end cementing and bead cementing can
effectively reduce emissions from these sources by as much as 85 percent.
VOC emissions from water-based green tire sprays are 90 to 100 percent
less than emissions from organic solvent-based sprays.
D. Regulatory Status
The EPA issued a guideline in 1978 which recommended that emission
reductions ranging from 60 to 86 percent could be achieved at undertread
cementing, tread-end cementing, bead dipping, and green tire spraying.
These recommendations are based on carbon adsorption or incineration
control technology. Use of water-based sprays could result in a 97
percent emission reduction from green tire spraying.2
The EPA proposed an NSPS in 1983 (48 FR 14). The proposed standards
are structured so they can be met by low solvent use techniques or water-based
green tire sprays without employment of a control device. The proposed
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standards are given below:
Operation
each undertread cementing and
each sidewall cementing operation
each tread end cementing operation
each bead cementing operation
each inside green tire spraying operation
each outside green tire spraying operation
Emission Limit^
(grams VOC/tire)
25* or 75 percent
reduction
10
10
1.2
9.3
*Low solvent use cut-off.
E. Current National Emission Estimates*
The 1985 emissions from the manufacture of rubber tire is estimated
at 40,000 megagarams (44,000 tons) of V0C based on tire demand and the
current level of emission control.
F. Capital and Annual Control Costs*
The capital and annual control costs for carbon adsorption, applied
to the sidewall cementing facilities at a 30,000 tire per day plant, are
estimated at $1,000,000 and $250,000, respectively (2nd quarter 1984
dollars). Control costs vary with production and solvent use rates.
More detailed information is available in Chapter 8 of Reference 1.
G. References
1. Rubber Tire Manufacturing'Industry - Background Information for
Proposed Standards, EPA-450/3-81-008a, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, July 1981.
2. Control of Volatile Organic Emissions from Manufacture of
Pneumatic Rubber Tires, EPA-450/2-78-030, U.S. Environmental Protection
Agency, Research Triangle Park, North Carclina, December 1978.
3. Standards of Performance for New Stationary Sources; Rubber
Tire Manufacturing Industry, Federal Register, Vol. 48, No. 14, January 20,
1983
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4.4.5 Polymers and Resins Manufacture
The polymers and resins industry includes operations that convert monomer
or chemical intermediate materials into polymeric or copolymeric products.
Sixteen of the major polymers types manufactured in the United States are:
The total process emissions from the polymer manufacturing industry are
approximately 86,000 megagrams of VOC per year (1983 estimate). About
75 percent of these emissions come from the following sources.
1. Polypropylene
2. Polyethylene
3. Polystyrene
4. Polyester resin, also known as poly(ethylene terephthalate), or PET
There are approximately 130 plants in the United States that manufacture
polymers and resins.
Acrylics
A1 kyds
High-Density Polyethylene
Low-Density Polyethylene
Mel amine Formaldehyde
Nylon 6
Nylon 66
Phenol Formaldehyde
Polyester Fibers
Polypropyl ene
Polystyrene
Polyvinyl Acetate
Polyvinyl Alcohol
Styrene-Butadiene Latex
Unsaturated Polyester Resins
Urea Formaldehyde
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4.4.5.1 Polyethylene. Polypropylene, Polystyrene, and Polyester Resin
A. Process and Facility Description
The manufacture of each of these polymers may be considered as a
five-step operation:
(1) raw materials storage and preparation, (2) polymerization reaction,
(3) materials recovery, (4) product finishing, and (5) product storage.
The first, raw materials storage and preparation includes methods of
storing monomers and other raw materials to be used in the polymerization
reaction. In preparation for the next step, raw materials may be dried
and still other purification steps may be taken. Raw materials are then
routed to the polymerization reactor.
In the reactor, raw materials and catalyst are combined with other
processing materials, as appropriate, to produce the polymer. Reactor
conditions, such as temperature and pressure, are specific for each
product. After polymerization, any unreacted raw materials are recovered
and returned to storage. The polymer is routed to "product finishing".
The product finishing stage of the polymerization process may include
extruding and pelletizing, cooling and drying, introduction of additives,
shaping operations and curing operations. The polymer is then ready for
"product storage and shipping". The final step, "product storage and
shipping" takes place in storage containers and associated solids transfer
equi pment.
B. Emission Sources and Factors
Pollutant emissions from the polymers and resins manufacturing process
may be considered in two categories: (1) process emissions, those that can
be anticipated based on the process flow diagram and, (2) fugitive emissions,
those that can be identified only by sampling procedures.
The major sources of process emissions are vents and product recovery
systems. Process emissions vary dramatically, both in composition and
flow, depending on the process. Some streams may have a VOC concentration
of less than 1 percent, others essentially 100 percent. Most are of
relatively high concentration. Some emissions are continuous. Others are
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intermittent. A more detailed description of the emissions sources and
factors for thirteen different production processes used in the manufacture
of polypropylene, high and low density polyethylene, polystyrene, and
poly (ethylene terephtalate) (polyester resin) 1s presented in reference
2. Fugitive VOC emissions result when process fluids leak from the plant
equipment. Sources include valves, pump seals, compressor seals, safety
or relief valves, flanges, sampling connections, and open-ended lines.
Fugitive emission factors are discussed in reference 2.
C. Control Techniques and Emission Reductions^
The control techniques for process emissions may be characterized
by two broad categories: combustion or recovery techniques. The four
major combustion devices applicable to process emissions are flares,
thermal or catalytic incinerators, and boilers. These four devices are
all expected to provide a destruction efficiency of 98 percent or greater.
The three major recovery devices are condensers, adsorbers and absorbers.
Recovery devices permit many organic materials to be retained and, in
some cases, reused in the process. A recovery efficiency of 95 percent
or greater can be expected from the application of any of these devices.
Two approaches are available to reduce fugitive VOC emissions by
the polymers and resin industry. The first is a leak detection and repair
program requires periodic inspections in which leaking fugitive emissions
sources are located and repaired at specific intervals. The second is a
preventive approach whereby fugitive emissions are either captured and
vented to a control device or eliminated through the installation of
specified controls or "leakless" equipment.
D. Regulj^ory Status
The EPA Issued a control techniques guideline in 1983 to specify
reasonable control technology (RACT) for the control of VOC emissions
from manufacture of high-density polyethylene, polypropylene, and
polystyrene resins. The following emission reductions or limitations are
considered representative of RACT;1
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(1) Fop polypropylene plants using liquid phase processes: a 98
weight percent reduction (or reduction to 20 ppm) of continuous VOC
emissions from the polymerization reaction section (i.e., reactor
vents), the material recovery section (i.e., decanter vents, neutralizer
vents, slurry vacuum/filter system vents, by-product and diluent recovery
operations vents), and the product finishing section (i.e., dryer vents
and extrusion and pelletizing vents).
(2) For high-density polyethylene plants using liquid phase slurry
processes: a 98 weight percent reduction (or reduction to 20 ppm) of
continuous VOC emissions from the material recovery section (i.e., ethylene
recycle treater vents or, if ethylene recycle is not used, emissions from
the flash tank) and the product finishing section (i.e., dryer vents
and continuous mixer vents).
(3) For polystyrene plants using continuous processes: an emission
limit of 0.12 kg VOC/1,000 kg product from the material recovery section
(i.e., product devolatilizer system, including the devolatilizer condenser
vent and the solvent recovery unit condenser vent).
Standards of performance for stationary sources of VOC's from
process and fugitive emission sources in the polymers and resins industry
are currently being" developed.2 The new source performance standard,
which will cover segments of the polypropylene, polyethylene, polystyrene
and poly(ethylene terephthalate) manufacturing processes, is expected to
reduce VOC emissions by almost 3,000 megagrams per year. This is about a
42 percent reduction of emissions that would be expected from the affected
facilities if there were no NSPS.
E. Current National Emission Estimate1
The total pirocess emissions from the manufacture of polypropylene,
polyethylene, polystyrene, and poly(ethylene terephthalate) are approximately
65,000 megagrams of VOC per year (1983 estimate).
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F. Capital and Annual Control Costs*
Control costs estimates are for 98 percent VOC destruction by
either thermal incinerators or flare control of the combined continuous
emission streams from the liquid-phase polypropylene process. The cost
analysis is based on a fluidized bed dryer with emissions of 0.6 kg
V0C/1000 kg of product. The total installed capital cost .is approximately
$735,000 for a thermal incinerator system and $90,000 for a flare system.
The annualized cost is about $218,000 per year for an incinerator system
and $80,000 per year for a flare. These numbers for this typical operation
are given for illustrative purposes. Costs for the whole range of polymer
•processes are given in reference 1. Detailed costs discussions also
constitute a chapter of reference 2.
G. References
1. Control of Volatile Organic Compound Emissions from Manufacture
of High-Density Polyethylene, Polypropylene, and Polystyrene Resins,
EPA-450/3-83-008, U. S. Environmental Protection Agency, Research Triangle
Park, N.C., November 1983.
2. Polymer Manufacturing Industry - Background Information for
Proposed Standards - Preliminary Draft, EPA 450/3-83-019a, U. S. Environmental
Protection Agency, Research Triangle Park, N.C., September 1983.
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4.4.6 Synthetic Fibers
A. Process and Facility Description 1»2
Synthetic fibers are manufactured as continuous filaments (which may
then be chopped into staple) of modified cellulose or man-made polymers.
They are used to manufacture carpets, apparel, industrial textiles, rope,
tires, cigarette filters, and composite materials. There are three broad
manufacturing classifications: melt spinning, solvent spinning, and
reaction spinning.
In the melt-spinning process, a thermoplastic polymer is heated to
above its melting point and is forced (extruded) through a spinneret (a
group of orifices). The filament solidifies as it is quenched in a stream
of cool air or other medium. Typical polymers suitable for melt spinning
are polyesters, nylons and polyolefins. Melt-spinning accounts for the
preponderance of synthetic fiber production in the U. S. with 2,300,000 Mg
(5.0 billion lbs) produced in 1983. There are approximately 130 plants
engaged in melt-spinning.
Solvent spinning can be subdivided into two types of processes, wet
or dry. Both first require the polymer to be dissolved in a suitable
solvent at a ratio of about three parts solvent to one part polymer. In wet
spinning, the polymer solution is extruded through a spinneret that is
submerged in a liquid that extracts the solvent, thereby precipitating
the polymer filament. In dry spinning the polymer solution is extruded
into a zone of heated gas that evaporates the solvent leaving the polymer
filament behind.
A third process, reaction spinning, is much like wet spinning. A
low molecular weight fluid "prepolymer" is extruded into a bath containing
a co-reactant which causes formation of the filament by polymerization.
This process is minor tonnage-wise and henceforth will be included in the
discussion of the wet spinning process.
Typical polymers suitable for solvent spinning are acrylics, modacrylics,
acetates, triacetates, rayon and spandex. Approximately 1,400,000 Mg
(3.0 billion lb) of solvent-spun fiber were produced in the U.S. in 1983
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at approximately 20 plants.
Once spun, all fibers undergo post-spinning processing. It may involve
one or more of the following: washing, stretching, cutting (into staple),
crimping, twisting, drying and finally packaging.
B. Emission Sources and Factors
Solvents are not used in melt-spinning; therefore, all VOC emissions are
due to unreacted monomer and oils applied to the filaments as they emerge
from the spinneret. Emissions may occur in the exhaust from the quenching
step or any of the post-spinning processing steps that require steam, hot
water, or dry heat. The monomer concentrations are usually quite low.
The lubricating oils have rather low vapor pressures and often condense
into a visible aerosol. VOC emission factors for melt-spinning are given
be1ow:
An average size plant will produce approximately 100 Mg fiber per year so
plant emissions would range from 0.1 to 0.5 Mg. per year. Solvent spinning
involves such large quantities of solvent that even though efficient
solvent recovery is essential to each process, substantial emissions
still occur. Typical emission points are fugitive leaks from mixers and
filters, wet-(and reaction-) spinning baths, the fiber as it emerges from
the dry-spinning cabinet or wet-spinning bath, and subsequent processing
steps that require steam, hot water or dry heat. Emission factors for
the most common solvent-spinning processes are given below. 1
Polymer
Uncontrolled Emissions
(Kg/Mg fiber)
Nylon 6
Nylon 66
Polyester
Polyolefins
2
0.8
2
5
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Type of Fiber
Emission Factor (kq/Mq Fiber)
Wet spun Acrylic &
Modacrylic 40
Dry Spun Acrylic 45
Dry Spun Modacrylic 140
Cellulose Acetate Cigarette Fil-
tration Tow 120
Cellulose Acetate Textile Yarn 145
Dry Spun Spandex 10
Wet (Reaction) Spun Spandex 150
More detailed information about specific process steps can be found in
Reference 1.
C. Control Techniques and Emission Reductions
Melt spinning and the associated post-spinning processes, if controlled
at all, are usually served by fabric-fi 1 ters, rotoclones, scrubbers or
elec-"ostatic precipitators. Since the uncontrolled emission rates are
smali, controls are installed at the plant's discretion. Removal
efficiencies have not been determined by EPA. The textile industry has
reported reductions of similar types of emissions by 70 to 95 percent.4
For economic purposes, most of the solvent used in the solvent
spinning process is normally recovered either from the dry-spinning spin
cell, or the wet-spinning spin bath. The method of recovery depends on
the solvent and its concentration in the process stream from which it is
recovered. Dry spinning solvents are recovered with packed or plate
tower scrubbers using water as the scrubbing medium. Carbon adsorption
is used for some solvents. Distillation is necessary to separate the
water and solvent. Normally, 90 percent of the solvent used in the
spinning step is recovered and recycled. Most of the remainder of the
recoverable solvent, about 10 percent of the total solvent feed to the
process, can be recovered by enclosing filters and the post-spinning
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processing steps and ventillating the exhaust to a scrubber or carbon
adsorber. These exhaust streams might be merged with streams from the
spinning step or controlled individually. VOC emission reduction achievable
from these points would be expected to also range from 90 to 95 percent.
D. Regulatory Status
Regulations for existing plants are nonexistent or very general in
scope, employing a ceiling, or guideline, similar to the technique used by
the old Los Angeles County Rule 66, i.e., 40 lbs per day. A new source
performance standard was promulgated by EPA on April 5, 1984. It is
applicable only to plants that solvent-spin fibers. The standard for
facilities that produce acrylic fibers is 10 kilograms VOC per megagram
of total solvent used. The standard for facilities that produce nonacrylic
fibers is 17 kilograms per megagram. Compliance-is determined on a
6-month rolling average basis. There are no regulations specific to
melt-spinning processes.
E. National Emission Estimates
Emissions from melt spinning and associated postspinning processes
were estimated at 4,600 Mg for 1983. Solvent spinning emissions (excluding
carbon disulfide (CS2) and (H2S) from rayon) for that same year were
64,390 Mg. Emissions of CS2 and H2S from rayon production were estimated
at 5,400 Mg.
F. Capital and Annual Control Cost
There are no regulations for the melt spinning processes. The EPA
therefore has not estimated the cost effectiveness of controlling those
emissions. The capital cost for using a refrigerated condensation aerosol
removal system has been estimated at $550,000 (1984) for a 5,000 scfm
exhaust from a textile plant.4 The types of emissions and their concentrations
would be similar to a melt spinning plant. Annualized costs were not
estimated.
The cost of control for solvent spinning process will vary due to the
variety of spinning technologies and postspinning processing steps that
arise from the variety of fibers that are produced. The table below
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reflects typical capital and annualized costs (May 1984) for models of the
most conroon processes and likely control strategies.
Fiber
Plant Control Strategy
Size Spinning used for
Gg/yr Process Estimating Costs
Capital Annualized
Costs Costs
Million Dollars
Ac ryli c
Ac ryli c
Mod-Acryl ic
Cel1ulose
Acetate
Cellulose
Acetate
45
Wet
98
76
Scrubber/Di stil lation
Train
Scrubber/Di stil lation
Train
Scrubber/Di stil lation
Train •
Scrubber or Carbon
Adsorber/Di stillation
Trai n
Carbon Adsorber/
Distillation Train
For more information on capital and annualized cost, refer to reference 1.
G. References
45
20
23
23
Dry
Dry
Dry
Dry
93
60
88
117
68
34
40
45
1. Synthetic Fiber Production Facilities - Background Information for
Proposed Standards, EPA-450/3-82-011a, October 1982.
2. Chemical & Engineering News 62(8), 1984, p.24.
3. Zerbonia, R., and G. Lantham, Source Category Survey Report - Synthetic
Fibers Industry, Pacific Environmental Services, Inc. EPA Contract No. 68-02-3060,
February 14, 1980.
4. Control of Hydrocarbon Emissions from Cotton and Synthetic Textile
Finishing Plants, EPA 600/2-83-041, May 1983.
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4.4.7 Plywood Manufacture
A. Process and Facility Description^
Plywood is a product composed of layers of wood veneer glued together
with an adhesive. The grain of each successive layer is placed at right
angles to give the product strength in two directions. Softwood plywood
is constructed using veneers from coniferous or needlebearing trees.
Emissions from hardwood veneer processing are insignificant compared to
emissions from softwood processes. In January 1980, an estimated 267
facilites were manufacturing softwood plywood and veneer in the continental
United States. By January 1982, many mills were closed, either temporarily
or permanently.
Four steps used in the production of plywood are listed below:
(1) Green process - log conditioning, followed by peeling into
green veneer;
(2) Veneer drying;
(3) Veneer patching and grading, lay-up and glueing, and pressing
to make plywood;
(4) Sizing and finishing of the plywood.
B. Emission Sources and Factors^
The primary sources of VOC emissions in this industry are the veneer
dryers. Veneer dryers emit condensible organic compounds. The rate of
uncontrolled emissions from a veneer dryer is a function both of the
characteristics of the wood and of the dryer and operating conditions.
Veneer dryers emit approximately 1.1 kilograms per thousand square meters
(10W) VOC/loV of 1-cm thick plywood produced^.
Fugitive emissions can comprise a significant portion of the total
from a veneer dryer. The main factors affecting the quantity of fugitive
emissions are the type of dryer, the condition of the door seals and end
baffles, and stock damper settings.
C. Control Techniques and Emission Reductions
Stack emissions from plywood veneer dryers can best be controlled
by add-on equipment. Wet scrubbing and incineration are the most common
control techniques presently used The most commonly employed wet scrubbing
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process consists of multiple spray chambers in series. The control
efficiency is generally less than 50 percent for this system. Incineration
has the potential to reduce dryer emissions by more than 90 percent.
Based on the performance of combustion equipment elsewhere, incineration
of all dryer exhausts in a fuel cell incinerator, or furnace could achieve
VOC removal efficiencies of greater than 90 percent from wood-fired
veneer dryers.
Control .techniques for minimizing fugitive emissions include
maintenance of door seals, dryer skins, tops, and end baffles; proper
balancing of air flows; and use of end-sealing sections.
0. Regulatory Status
There are no Federal regulations for plywood plants but one or more
States have regulations.
E. Current National Emission Estimate3
National VOC emissions from plywood production are estimated at
approximately 1,700 megagrams per year.
F. Capital and Annual Control Costsl
Boiler incineration control for a plywood plant with a single steam-
heated dryer is estimated to have an installed cost of $199,000 and total
annualized costs of $103,000. These costs are for a typical situation;
however, there are different configurations for plywood plants depending
on the number of dryers and whether the dryers are steam heated or wood
fired. Reference 1 contains a more complete discussion of costs.
G. References
1. Control Techniques for Organic Emissions from Plywood Veneer
Dryers, EPA-450/3-83-012, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, May 1983.
2. Plywood Veneer and Layout Operations. In: Compilation of Air
Pollutant Emission Factors, Third Edition. AP-42, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, August 1977.
3. Emission estimate based upon 1981 softwood plywood production
data provided by the National Paint- and Coatings Association, Inc.
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4.4.8 Beer and Wine Production
A. Process and Facility Description
Beer and wine are alcoholic beverages made by fermentation. Beer
production begins with malting. Barley is malted by adding moisture and heat
until germination occurs. Wine production begins with stemming and crushing
of grapes. Fermentation is the next step for both beverages. During fermenta-
tion, specially cultivated yeasts convert the malt sugar or grape sugar into
ethanol and carbon dioxide. Additional production steps include storage,
clarification, pasteurization, and packaging. Beer production also includes
recarbonati on.
B. Emission Sources and Factors
VOC emissions from beer making are primarily associated with the spent
grain drying and are estimated to be 1.31 kg/Mg (3.2 lb/ton) of grain handled.*
The volatile organics consist principally of ethanol. All emissions during
fermentation are collected for the carbon dioxide. Emissions from other brewry
operations are minor. Emission factors are not available.
For wine making, VOC emissions are due to ethanol entrainment in the CO2
produced during fermentation. For fermentation at 27°C (80°F), ethanol
emissions range from 574 g/kl (4.8 lb/thousand gallons) for white wine to
862 g/kl (7.2 lb/thousand gallons) for red wine.* VOC emissions are expected
from other operations, though no testing data are available.
C. Control Techniques and Emission Reductions
VOC emissions due to spent grain drying could be controlled by mixing
the dryer exhaust with the combustion air of a boiler.^ VOC destruction
efficiency would be 95 percent or greater.
VOC control techniques have not been implemented by the wine industry.
D. Regulatory Status
Presently there are no EPA, state, or local air regulations directed
specifically at controlling VOC emissions from beer or wine making.
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E. National Emission Estimates
VOC emissions associated with beer production were estimated at
360 Mg/yr (400 tons/year) in 1982.
VOC emissions due to wine production were estimated at 1,300 Mg/yr
(1,400 tons/yr) in 1983. Emissions estimates are based on emission factors.
No test data are available.
F. Current Capital and Annual Costs
No cost information is available.
G. References
1. U.S. Environmental Protection Agency. Compilation of Air Pollutant
Emission Factors. Research Triangle Park, North Carolina. Publication
AP-42. April 1981.
2. Predicasts, Inc., Predicasts Basebook, Cleveland, Ohio, 1984.
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4.4.9 Whiskey Warehousing
A. Process and Facility Description
The manufacture of whiskey involves two distinct operations--the
production of unaged whiskey from cereal grains and the maturation of this
whiskey by storage in charred white oak barrels. Production steps include
grain milling, cooking, malting, fermentation, and distillation. Following
production, whiskey must be aged by storage in charred oak barrels to produce
an alcoholic beverage with the traditional taste and aroma of whiskey.
Since production steps account for only a small percentage of total VOC
emissions, this source category will focus on whiskey warehousing operations.
B. Emission Sources and Factors
During warehousing, there are two sources of VOC emis'sions—evaporation
from the barrel wood during storage and evaporation from the saturated wood
after the barrel is emptied. Storage evaporation occurs when liquid diffuses
through the barrel staves and heads via the wood pores or travels by capillary
action to the ends of the barrel staves. Evaporation from emptied barrels
occurs when the saturated barrels are stored after emptying. The combined
emissions from both sources are 3.2 kg ethanol lost/barrel-yr.* A barrel
consists of 55 proof-gallons and a proof-gallon is defined as one U.S. gallon
containing 50 percent by volume ethanol or any volume of liquid containing an
equivalent amount of ethanol.
C. Control Techniques
Two methods for reduction of warehouse emissions have been investigated:
(1) carbon adsorption and (2) an alternate aging system. Use of a carbon
adsorption system would require closing the warehouse and ducting the interior
to a skid-mounted package system. The carbon adsorption system should recover
85 percent of the ethanol allowing for maximum ethanol losses. An alternate
system of aging--using sealed stainless steel vessels--is under development.
Perfection of such a system with no reduction in whiskey quality would essen-
tially el imini ate all ethanol losses. The EPA issued a cost and engineering
study on VOC emissions from whiskey warehousing in April 1978.
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0. Regulatory Status
No Federal regulations have been issued on whiskey warehousing. Over
90 percent of whiskey warehousing occurs in five states—Kentucky, Indiana,
Illinois, Maryland, and Tennessee. None of these States have regulated these
emissions.
E. National Emission Estimate
The national emission estimate is 38,170 Mg/yr based on 11.9 million
barrels stored in June 1976. the estimate is based on emission factors derived
from aggregate loss data obtained from the IRS.
F. Capital and Annual Costs
For a 50,000-barrel warehouse, capital cost for a carbon adsorption
system to control warehouse emissions is $190,000 (in 1984 dollars). Total
annual costs after alcohol recovery and resale are $5,600. Costs were
developed from vendor quotes.
G. References
Cost and Engineering Study--Control of Volatile Organic Emissions
from Whiskey Warehousing, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, EPA-450/2-78-013, April, 1978.
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4.4.10 Other Industrial Processes
A major problem which impedes the Nation's progress in its goal of
reducing ambient levels of ozone is the extremely large number of industries
for which VOC regulations must be developed; almost every industrial
activity is a source of organic emissions. As a result, a regulatory
program that will ultimately achieve and maintain the ambient air
quality standard is necessarily extensive and complex. Appendix A provides
a list of many industrial operations that use and emit VOC. Even it,
however, is far from complete. For example, many metal-forming operations
such as casting, forging, rolling (of aluminum foil), and machining also
use and emit organic lubricants. Ultimately, regulatory programs will be
required for many more industrial processes before the air over all of
America will have ozone contamination levels that are less than the
national ambient air quality standard.
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4.5 APPLICATION OF PAINTS, INKS, AND OTHER COATINGS
Introduction
Activities by the Environmental Protection Agency in 1977 have had a
profound and continuing influence on the coating industry. In May of
that year the Agency published its first volume of guidance for States to
develop regulations. This guidance was contained in a series of reports
that are now uniformly referred to as "CTG's" (Control Techniques
Guidelines). These reports strongly influenced the ensuing State
regulations that limit emissions from large segments of the original
equipment manufacturers that use large volumes of coatings. Born of the
environmental movement and nurtured by tfre energy shortage of the later
1970's, the search to develop coatings that contain less solvent has
almost become a way of life for the coating manufacturing industry.
Large companies have dropped entire product lines because the large
investments required for research made it prudent to specialize in certain
types of coatings or coatings for certain types of customers. The industry
was shaken from a lethargy common to many large mature industries.
Suddenly, innovation and exploration of new paint chemistry became
paramount as customers placed pressure on suppliers to provide low-solvent
coatings that would preempt the only alternative, purchase of capital-
intensive abatement equipment. The results of the research are becoming
increasingly evident in the marketplace as more companies come into
compliance by use of new coatings applied with new application equipment.
Often, having made the transition, both the coaters and coating manufacturers
are finding economic advantages in use of the low-solvent coatings that
were not expected. These include low transportation costs and less
warehousing requirements (because of the more concentrated coatings),
less waste disposal problems because of improvements in application
equipment, lower insurance rates, and more desirable working conditions
because of the decrease in solvent.
A survey* in April of 1984 revealed that 63 percent of the finishers
that responded had changed their coatings in the last 3 years and 51 percent
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of that group ascribed their motivation to environmental regulations. A
subsequent survey^ revealed that 61 percent of the responders intended to
change coatings within the next 5 years. Of that group, almost half,
49 percent, ascribed environmental regulations as the major factor in
their decision.
Similarly, manufacturers of ink have explored new ink technologies.
Waterborne inks are being used to a greater extent than ever before. The
industry also alleges that newer ink technology has reduced the solvent:
solids ratio of inks and the resin: pigment ratio of the solids portion
of the ink. Both changes would reduce emissions.
The printing Ipdustry has also made equipment changes that reduce
fugitive emissions. Many companies now cover ink cans that formerly
remained open. Ink fountains at some plants have been replaced by closed
ink systems and doctor blades. One company has developed an air driven
pump for the ink can that does not heat the ink as it is recycled. By
operating cooler, the solvent does not evaporate as rapidly and the amount
of make-up solvent required decreases.
The EPA has published two references that are critical to understanding
the Agency's program for reducing emissions from coating operations. The
first is a glossary of terms^ which standardizes the vocabulary for this
segment of environmental control. The second contains instructions and
forms that manufacturers and applicators may use to certify the VOC
content of their coatings.4
References
1. Industrial Finishing, April 1984, pg. 9.
2. Industrial Finishing, September 1984, pg. 9.
3. Glossary for Air Pollution of Industrial Coating Operations,
Second Edition, EPA-450/3-83--013R, December 1983.
4. Procedures for Certifying Quantity of Volatile Organic Compounds
Emitted by Paint, Ink, and Other Coatings, EPA-450/3-84-019, December 1984.
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4.5.1 SURFACE COATING
4.5.1.1 Large Appliances
A. Process and Facility Description^
Large appliance products include kitchen ranges, ovens, microwave
ovens, refrigerators, freezers, washers, dryers, dishwashers, water
heaters, and trash compactors. A "large appliance surface-coating line"
consists of the coating operations for a single assembly line within an
appliance assembly plant. Typically, the metal substrate is first cleaned,
rinsed in a phosphate bath, and oven dried to improve coating adhesion.
If a prime coat is necessary, the part may be dipped, sprayed, or flow-
coated and dried in a curing oven. Subsequently, the topcoat is applied,
usually by spray. The freshly-coated parts are conveyed through a flashoff
tunnel to evaporate solvent and cause the coating to flow out properly.
After coating and flashoff, the parts are baked in single or multipass
ovens at 150-230°C.
There are approximately 170 plants in the United States that manufacture
large appliances.
B. Emission Sources and Factors
A surface coating line has three main sources of emissions. Major
emissions occur at the application (spray booth) area, fla-shoff area, and
the curing oven. Fugitive emissions occur during mixing of coatings.2 The
uncontrolled emission factor for an organic borne coating containing 25-volume
percent solids (75-volume percent organic solvent) is 0.66 kilograms of
VOC per liter of coating (minus water)* consumed.3 An emission estimate
of 50 megagrams of VOC per year is reasonable for the average appliance
pi ant.3
~Equivalent to 0.66 kilograms of VOC per liter of coating consumed
for an organic borne coating that contains no water.
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C. Control Techniques and Emission Reductions*
Control techniques used in the large appliance surface coating
industry include converting to low solvent coatings, improving transfer
efficiency with state-of-the-art equipment, or incineration. Changing
from traditional to high-solids or waterborne coatings can reduce VOC
emissions from prime coating operations by 70 percent and 92 percent,
respectively. Use of electrodeposition to apply the prime coat can reduce
emissions by 94 percent over conventional spray prime coat operations.
Emissions from top-coat application can be reduced by use of waterborne,
high-solids or powder coatings, giving reductions of 80 percent, 70
percent, and 99 percent, respectively, from levels typical of high VOC
coatings.
Transfer efficiency is the ratio of the amount of coating solids
deposited onto the surface of the coated part to the total amount of
coating solids used. Improvments in transfer efficiency decreases the
volume of coating that must be sprayed to cover a specific part, thereby
decreasing the total VOC emission rate a proportional amount.
Historically, the large volumes of air used to ventilate open spray
booths and flashoff areas made it prohibitively expensive to incinerate
emissions from these sources. Incineration of VOC emissions in the
curing oven exhaust, however, has been feasible, primarily because
concentrations are higher. Incineration of the curing oven exhaust can
reduce overall emissions from the large appliance surface coating line by
about 15 percent.
D. Regulatory Status
The EPA issued a guideline to assist States in developing regulations
for this industry in 1977 and set NSPS standards for it in 1980 (40 CFR
60 Subpart SS). The recommended emission limit for existing plants is
0.34 kilograms of VOC per liter of coating minus water (2.8 lb VOC/gallon
coating minus water). This limit is based on the use of low solvent
organic borne coatings.2 The NSPS requires that emissions be limited to
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0.90 kilograms of VOC per liter of applied coating solids. It 1s based
on a 62-volume percent solids coating applied at a transfer efficiency of
60 percent.1
E. National Emission Estimates
It has been estimated that surface coating of large appliances
resulted in emissions of approximately 24,000 megagrams of VOC4 in 1981.
F. Capital and Annual Control Costs1
Higher solids, waterborne and powder coatings are available which
will meet the standards and can be used for approximately the same cost
as conventional high-solvent coatings. In some cases companies can save
as much as $360,000 annually by switching to low solvent coatings.2
Costs estimates for switching coatings are highly dependent on the
particular installation. A case-by-case analysis should be performed on
each installation when switching coatings.
G. References
1. Industrial Surface Coating: Appliances - Background Information
for Proposed Standards - and Promulgated Standards, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, EPA-450/3-80-
037a and b, November 1980 and October 1982.
2. Guideline Series: Control of Volatile Organic Emissions from
Existing Stationary Sources Volume V: Surface Coating of Large Appliances,
U.S. Environmental Protection Agency, Research Triangle Park, North
Carolina, AP-42, May 1983.
3. Compilation of Air Pollutant Emission Factors, Third Edition.
Supplement No. 14, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, AP-42, May 1983.
4. Based on information provided by the National Paint and Coatings
Association, Inc., Washington, D.C., 1981 data.
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4.5.1.2 Magnet Wire
A. Process and Facility Description*
Magnet wire coating is the process of applying a coating of
electrically insulating varnish or enamel to aluminum or copper wire for
use in electrical machinery. The uncoated wire is unwound from spools
and passed through an annealing furnace to make the wire more pliable and
to burn off oil and dirt left from previous operations. The wire passes
from the furnace to the coating applicator. At a typical applicator, the
wire acquires a thick coating by passage through a coating bath. The
wire is then drawn vertically through an orifice or coating die which
scrapes off excess coating and leaves a thin film of the desired thickness.
The wire is routed from the coating die into an oven where the coating is
dried and cured. A typical oven has two zones. The wire enters the
drying zone, held at 200°C, and exits through the curing zone, held at
430°C. A wire may pass repeatedly through the coating applicator and oven
to build a multilayered coating. After the final pass through the oven,
the wire is rewound on a spool for shipment. There are approximately 30
plants nationwide which coat magnet wire.
B. Emission Sources and Factors
The oven exhaust is the most important emission source in the wire
coating process. Solvent emissions from the applicator are low due to
the dip coating technique. A typical uncontrolled wire coating line
emits about 12 kilograms of VOC per hour. It is not unusual for a wire
coating plant to have 50 ovens, therefore an uncontrolled plant could
easily emit more than 90 megagrams of VOC per year.*,2
C. Control Techniques and Emission Reductions1
Incineration, either thermal or catalytic, is the most common
control technique for emissions from wire coating operations. Essentially
all solvent emissions from the oven can be directed to an incinerator
with a combustion efficiency of at least 90 percent. Equivalent
emission reductions achieved through coating reformulations would require
replacement of conventional solvent-borne coatings with either high-solids
coatings (greater than 77 percent solids by volume) or waterborne coatings
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(i.e., 29 volume percent solids, 8 volume percent organic solvent, 63
volume percent water). Use of powder coatings, hot melt coatings or
waterborne emulsions, which contain little or no organic solvent, would
eliminate VOC emissions.
D. Regulatory Status*
The EPA issued a guideline (CTG) in 1977 which recommends emissions
from wire coating ovens be limited to 0.20 kilograms of VOC per liter of
coating (minus water). This limit was based on use of incineration
control although conversion to a low solvent coating that yields equivalent
reductions would be an acceptable alternative.
E. National Emission Estimates
Coatings used for insulating of magnet wire in 1983 are estimated
to have contained 22,000 megagrams of VOC.3 Since many magnet wire
lines already use incinerators, it is estimated that less than 7,000 Mg
per year of VOC was actually emitted.
F. Capital and Annual Control Costs*
The capital and annual costs of a facility which exhausts 10,000 scfm
that controls VOC emissions by incineration with primary heat recovery
are approximately $325,000 and $170,000, respectively. The costs are for
a typical size magnet wire facility; however, line sizes vary and the
cost of the control equipment will be a function of the number of coating
lines served by a single piece of control equipment. See reference 1 for
a more complete discussion of costs.
G. References
1. Control of Volatile Organic Emissions from Existing Stationary
Sources, Volume IV: Surface Coating for Insulation of Magnet Wire, U. S.
Environmental Protection Agency, Research Triangle Park, North Carolina,
EPA-450/2-77-033, December 1977.
2. Magnet Wire Coating. Compilation of Air Pollutant Emission
Factors, Third Edition, Supplement NO. 15, U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina, AP-42, January 1984.
3. Based on information provided by the National Paint and Coatings
Association, Inc.
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4.5.1.3 Automobiles and Light-Duty Trucks
A. Process and Facility Description*
The automobile and light-duty (less than 8,500 pounds gross vehicle
weight) truck assembly industry receives parts from a variety of sources
and produces finished vehicles ready for sale to vehicle dealers. The
automobile and light-duty truck coating process is a multistep operation
performed on an assembly line producing up to 90 units per hour. There
were about 65 automobile or light-duty truck assembly plants in the United
States in 1984.
Body surfaces to be coated are cleaned with various materials which
may include solvents to remove oil and grease. Then a phosphating process
prepares the surface for the prime coat. The primer is applied*to protect
metal surfaces from corrosion and to ensure good adhesion of the topcoat.
Primer may be solvent-based or waterborne. Solvent-based primer is
applied by a combination of manual and automatic spraying, flow coat or
dip processes. Waterborne primer is most comon now and is most often
applied in an electrodeposition (EDP) bath. The prime coat is oven cured
before further coating. When EDP is used to apply primer, the resulting
film may be too thin and rough to compensate for all surface defects, so
a guide coat (primer-surfacer) is usually applied and oven-cured before
the topcoat application. Recent developments in EDP technology produce a
thicker dry film which in some cases elminates the need for the guide
coat.
On some vehicles an additional coating called a chip guard or anti-
chip primer is applied along the bottom of the doors and fenders. These
flexible urethane or plastisol coatings help protect susceptible parts of
the coated vehicle from damage by stones or gravel.
The topcoat (color) is then applied by a combination of manual and
automatic spraying. The topcoat requires multiple applications to ensure
adequate appearance and durability. An oven bake may follow each topcoat
application, or the individual coats may be applied wet-on-wet with a
final oven bake.
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The painted body is then taken to a trim operation area where
vehicle assembly is completed. Some additional coating may be done in a
final off-line repair step if needed to correct paint defects or damage.
Single coating (not clearcoated) lacquer and enamel topcoats have
traditionally been used in this industry. Since 1980, the entire domestic
auto industry has been converting to a composite, two coating, topcoat
system which consistes of a thin layer of a highly pigmented basecoat
followed by a thick layer of clearcoat. These two coating systems are
referred to as basecoat/clearcoat. They can provide higher gloss and
better chemical resistance than conventional single coating topcoats,
especially for metallic colors. Some domestic manufacturers are switching
all of their colors to basecoat/clearcoat while others are using basecoat/
clearcoat for metallic colors only. The switch to basecoat/clearcoat was
prompted by the use of basecoat/clearcoat on virtually all imported
metallic colored cars.
B. Emission Sources and Factors^
Solvent emissions occur in the application and curing stages of the
surface coating operations. The application and curing of the prime coat
guide coat and topcoat accounted for a majority of the VOC emitted from
most assembly plants in the past. Over the last ten years, conversions
to lower VOC content coatings and more efficient application equipment
has reduced the contribution of these operations to total plant-wide VOC
emissions at many assembly plants. Final topcoat repair, cleanup,
adhesives, sound deadeners, and miscellaneous coating sources account for
the remaining emissions. Approximately 70 to 90 percent of the VOC
emitted during the application and curing process is emitted from the
spray booth and flashoff areas, and 10 to 30 percent from the bake oven.
Typical emission ranges for major automobile surface-coating operations
are summarized in the table below:
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Coating
Kg VOC/Vehicle
lb VOC/Vehicle
Prime Coat
Solvent-borne spray
Electrodeposition
1.8-3.6
0.5-1.4
4-8
1-3
"Guide Coat
Solvent-borne spray
Waterborne spray
0.5-1.8
0.5-0.8
1-4
1-2
Topcoat
Solution lacquer
Dispersion lacquer
Conventional enamel
Higher solids enamel
Waterborne enamel
13.6-22.7
5.9-9.1
5.0-10.0
2.3-5.0
1.6-2.7
30-50
13-20
11-22
5-11
3.5-6
C. Control Techniques and Emission Reductions^
Use of waterborne EDP coatings is the most common control technique
for prime coats. Waterborne guide coats and topcoats have been used in
three plants.
Since 1980, the industry and its suppliers have focused primarily on
developing higher solids solvent-borne enamels and improving transfer
efficiency. Most of the coating development work has been directed toward
basecoat/clearcoat coatings. Low solids, high VOC content basecoat/clearcoat
materials have been used since the mid-1960's, especially on metallic-
9
colored imported cars. Higher solids basecoat/clearcoat topcoats have
been developed to help meet VOC emission regulations and match the
appearance of imported vehicles. These coatings are in use at many plants,
including two of the plants that used waterborne topcoats. (The third
plant that used waterborne topcoats has closed.)
New coating application systems are also being installed in assembly
plants. Electrostatic, automatic and robot spray equipment are being
used to improve transfer efficiency, quality and productivity.
Add-on control devices are also applicable in this industry. Thermal
incineration can reduce VOC emissions from bake oven exhausts by at least
90 percent. Pilot studies in the United States have proven that carbon
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adsorbers can efficiently reduce spray booth exhaust emissions. Several
manufacturers are actively considering installation of carbon adsorption
on some spray booth exhausts to meet VOC emission limitations and for
odor control.
0. Regulatory Status
The EPA issued a guideline (CTG) in 1977. The guideline contained
recommendations which were expressed in terms of the VOC content of the
various coatings and were based upon waterborne coatings then in use for
primer, guide coat and topcoat; and solvent-borne coatings for final
repair. Later guidance suggested associating a baseline transfer efficiency
of 30 percent with the recommendations for guide coat and topcoat. This
later recommendation was based on the results of transfer efficiency
tests conducted at two plants using waterborne guide coat and topcoat.
The CTG recommendations are summarized below:
CTG Recommendation Later Guidance
Kg VOC/1 iter (lb/gal) Kg VOC/liter (lb/gal)
Operation coating less water solids applied
Prime coat 0.15 (1.2)
Guide coat 0.34 (2.8) 1.8 (15.1)
Topcoat 0.34 (2.8) 1.8 (15.1)
Final repair 0.58 (4.8)
An NSPS was promulgated in 1980 (40 CFR 60 Subpart MM). These standards
are summarized below:
Emission Limit
Affected Facility Kg VOC/liter (lb/gal) solids applied
Prime coat 0.16 (1.3)
Guide coat 1.40 (11.7)
Topcoat 1.47 (12.2)
A revision to the prime coat NSPS was proposed on July 29, 1982
(47 FR 146). This revision has not yet been made final. The purpose of
the revisions is to better describe the emission characteristics of the
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best demonstrated technology (cathodic electrodeposited primer) under a
variety of operating conditions.
E. National Emission Estimates
The surface coating (prime coat, guide coat, topcoat and final
repair) of automobiles and light-duty trucks is estimated to have resulted
in VOC emissions of approximately 64,000 meyagrams (70,000 tons) in 1984.4
F. Capital and Annual Control Costs
The cost of controlling topcoat bake oven and spray booth emissions
with incinerators or carbon adsorbers varies with the VOC and solids
content of the coatings used, ventilation rates, production rates, and
other plant specific factors.
G. References
1. Automobile and Light-Duty Truck Surface Coating Operations -
Background Information for Proposed Standards, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, EPA-450/3-79-030,
September 1979.
2. Letter from Fred W. Bowditch, Motor Vehicle Manufacturers
Association to Jack R. Farmer, U.S. EPA, September 13, 1985.
3. Control of Volatile Organic Emissions from Existing Stationary
Sources - Volume II: Surface Coating of Cans, Coils, Paper, Fabrics,
Automobiles and Light-Duty Trucks, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, EPA-450/2-77-008, May 1977.
4. Based on information provided by the National Paint and Coatings
Association, Inc.
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4.5.1.4 Cans
A. Process Description
There are two major types of cans. Coating application methods used
by can manufacturers vary with the type of can. The coatings used depend
on the type of can and the type of product to be packed in the can.
A "three-piece" can is made from a cylindrical body and two end
pieces. A large metal sheet is first roll coated with both an exterior
and an interior coating, then cut to size, rolled into a cylinder (body)
and sealed at the side seam. A bottom end piece formed from coated metal
is then attached to the body. The can interior may then be spray coated
before the can is filled with a product and sealed with the top end piece.
A "two-piece" can body and bottom is drawn and wall ironed from a
single shallow cup. After the can is formed, exterior and interior
coatings are applied by roll coating and spraying techniques, respectively.
The can is then filled with product and the top end piece is attached.!
The metal can industry consists of over 400 plants nationwide.^ In
recent years there has been a dramatic shift from three-piece cans to two-
piece cans. Almost all beverage cans and many food cans are now two-piece.
B. Emission Sources and Factors
Solvent emissions from can coating operations occur from the application
area, flashoff area, and the curing/drying oven. Typical per plant,
annual emissions from can coating operations were estimated in 1977 to
vary from 13 megagrams (14 tons) for the end sealing operation to 240
megagrams (264 tons) for coating two-piece cans.2 Since then, increased
use of low VOC content waterborne coatings, especially for two-piece beverage
cans has reduced emissions considerably.
Emissions vary with production rate, VOC content of coatings used,
and other factors. More detailed information on the annual emissions
from individual coating operations in can manufacturing plants is presented
in Reference 4.
C. Control Techniques and Emission Reductions
Emission reductions of up to 90 percent can be achieved by incinerating
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emissions from can coating operations. Substitution of waterborne or
high-solids coatings for conventional coatings can reduce VOC emissions
by 60 to 90 percent at many of these operations.! .3
D. Regulatory Status
The EPA issued a guideline in 1977 which recommends separate VOC
emission limits for the different steps in the can coating process.
Although generally based on abatement techniques, the emission limits were
expressed in terms of the VOC content of the coating to encourage
development and use of low solvent coatings.
Can Coating CTG Recommendations*
Affected Facility Recommended Limitation
lb per gallon
kg per liter
of coating
minus water
0.34
of coating
less water
2.8
Sheet basecoat (exterior and
interior and overvarnish;
two-piece can exterior
(basecoat and overvarnish)
Two and three-piece can interior
body spray, two-piece an interior
end (spray or roll coat)
Three-piece can side-seam spray
End sealing compound
The EPA set new source performance standards in 1983 (40 CFR 60
Subpart WW) which limit VOC emissions from two-piece beverage can surface
coating operations as follows:
(1) 0.29 kilograms VOC per liter (2.4 pounds per gallon) of coating
solids from each exterior base coating operation except clear base coating.
(2) 0.46 kilograms VOC per liter (3.8 pounds per gallon) of coating
solids from each over-varnish coating and each clear base coating operation,and
0.51
0.66
0.44
4.3
5.5
3.7
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(3) 0.89 kilograms VOC per liter (7.4 pounds per gallon) of coating
sol Ids from each inside spray coating operation.
E. National Emission Estimate
It has been estimated that surface coating of cans resulted in
emissions of 68,000 megagrams (75,000 tons) of VOC in 1981.7
F. Capital and Annual Control Costs^
A can coating facility with a 5,000 scfm exhaust stream using either
thermal or catalytic incineration (with primary heat recovery), or carbon
adsorption (with credit for recovered solvent at fuel value), would
require a capital expenditure ranging from $190,000 to $240,000 and have
annualized costs from $60,000 to $110,000 (2nd quarter dollars). Control
costs vary with production rate and other factors. More detailed informatin
is presented in Chapter 8 of Reference 3.
G. References
1. Control of Volatile Organic Emissions from Existing Stationary
Sources - Volume II: Surface Coating of Cans, Coils, Paper, Fabrics,
Automobiles, and Light-Duty Trucks. EPA-450/2-77-008, 0AQPS No. 1.2-073,
U.S. Environmental Protection Agency, Research Triangle Park, North
Carolina 27711. May 1977.
2. U. S. Industrial Outlook 1983. (J. S. Department of Commerce,
Washington, D. C. January 1983.
3. Beverage Can Surface Coating Industry - Background Information
for Proposed Standards, EPA-450/3-80-036a, U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina 27711. September 1980.
4. Beverage Can Surface Coating Industry -'Background Information
for Promulgated Standards, EPA-450/3-80-03b. U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina 27711. August 1983.
5. Standards of Performance for New Stationary Sources; Beverage
Can Surface Coating Industry. Proposed Rule. Federal Register, Vol 45,
No. 230, November 26, 1980.
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4.5.1.5 Metal Coils
A. Process and Facility Description1
The metal coil coating industry applies coatings to metal sheets or
strips that come in rolls or coils. The metal strip is uncoiled at the
beginning of the coating line, cleaned and then pretreated to promote
adhesion of the coating to the metal surface. When the coil reaches the
coating application station, a coating 1s applied, usually by rollers, to
one or both sides of the metal strip. Some coil coatings are applied by
electrodeposition. The strip then passes through an oven to cure the
coating and is then water or air quenched. If the line is a "tandem"
line, the metal strip passes through a second sequence of coating applicator,
oven and quench station. Finally, the coil 1s rewound for shipment or
further processing. In 1980, there were 109 plants containing an estimated
147 coil coating lines in the United States.
B. Emission Sources and Factorsl
Approximately 90 percent of the total VOC content of the coating
evaporates in the curing ovens. Of the remaining 10 percent, about 8
percent evaporates at the applicator station and 2 percent at the quency
station. The rate at which VOC emissions occur is determined by the
operating parameters of the line, including: (1) the width of the metal
strip, (2) the VOC and solids content of the coating, (3) the speed at
which the strip is processed, (4) the thickness at which the coating is
applied and (5) whether emission abatement equipment has been installed.
Annual emission from a coil coating line may range from 30-2000 megagrams
(35-2200 tons). More detailed information on emission rates is presented
in Reference 1.
C. Control Techniques and Emission Reductions
An 80-90 percent emission reduction can be achieved by venting the
VOC that evaporates in the oven (90 percent) and directing it to an
incinerator. An overall VOC emission reduction of 90 percent or more may
be achieved if emissions from the coating application stations are also
vented to an incinerator.1
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Low solvent and waterborne coatings are also available for many end
uses. These coatings may achieve emission reductions of up to 90 percent
compared to conventional solvent-borne materials. In 1980, approximately
15 percent of the coatings used were waterborne.
0. Regulatory Status
The EPA issued a guideline (CTG) in 1977 and set NSPS standards (40
CFR 60 Subpart TT) in 1982 to control emissions from metal coil surface
coating operations. The CTG recommends a VOC emission limit of 0.31
kilograms per liter of coating minus water (2.6 pounds per gallon minus
water).2 The NSPS has the following emission limits:
(1) 0.28 kilograms of VOC per liter (2.3 pounds per gallon) of
coating solids applied for each calendar month for each affected facility
that does not use an emission control device; or
(2) 0.14 kilograms of VOC per liter (1.2 pounds per gallon) of
coating solids applied for each calendar month for each affected facility
that continuously uses an emission control device; or
(3) a 90 percent emission reduction for each calendar month for
each affected facility that continuously uses an emission control device,
or
(4) a value between 0.14 (or a 90 percent emiss.ion reduction) and
0.28 kilograms of VOC per liter (1.2 and 2.3 pounds per gallon) of coating
solids applied for each calendar month for each affected facility that
intermittently uses an emission control device.
E. National Emission Estimate
It has been estimated that metal coil surface coating operations
emitted approximately 33,000 megagrams (36,000 tons) in 1984.3
F. Capital and Annual Control Costs*
For a metal coil coating facility with a coating capacity of
14 x 10® square meters (15 x 10^ square feet) per year, the capital and
annual control cost for an incineration system capable of achieving 90
percent overall emission reduction is estimated to be $1,650,000 and
$230,000, respectively (2nd quarter 1984 dollars). The annual emission
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reduction at such a plant would be 750 megagrams (820 tons).
Control costs vary with the factors described in Section B above.
More detailed information on control costs is provided in Chapter 8 of
Reference 1.
G. References
1. Metal Coil Surface Coating Industry - Background Information for
Proposed Standards, EPA-450/3-80-035a, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, October 1980.
2. Control of Volatile Organic Emissions from Existing Stationary
Sources, Volume II: Surface Coating of Cans, Coils, Paper, Fabrics,
Automobiles,1 and Light-Duty Trucks, EPA-450/2-77-008, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, May 1977.
3. Based on information provided by the National Paint and Coatings
Association, Inc.
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4.5.1.6 Paper, Film and Foil*
A. Process and Facility Description
Paper is coated for a variety of decorative and functional purposes
with a variety of coatings which may be waterborne, organic solvent-borne,
or solventless extrusion type materials. A coating operation is defined
as the application of a uniform layer across a substrate. This definition
of coating also Includes saturation processes. In paper-coating operations,
the coating mixture is usually applied by means of a reverse roller, a
knife, or a rotogravure roller to a web of paper. The major components
of a paper-coating line are, 1n sequence: the unwind roll (from which
the paper is fed to the process), the coating applicator, the oven,
tension and chill rolls, and the rewind roll. Ovens may be divided into
from two to five different temperature zones. The first is usually
maintained at about 43°C. The other zones have progressively higher
temperatures up to 200°C to cure the coating after most of the solvent
has evaporated. The large volume organic solvents used in paper coating
mixtures are toluene, xylene, methyl ethyl ketone, isopropyl alcohol,
methanol, acetone and ethanol.l There are approximately 800 plants
nationwide where paper-coating operations are employed.^
B. Emission Sources and Factors3
The main emission points from a paper-coating lines are the coating
applicator and the oven. In a typical paper-coating plant, about 70
percent of all emissions are from the coating lines, The other 30 percent
are emitted from solvent transfer, storage and mixing operations. Most
of the VOC emitted by the line are from the first zone of the oven.
* Throughout this section, the term "paper coating" refers to coating of
paper, plastic film and metallic foil. Products with plastic substrates
such as magnetic tape and photographic film are included as are all types
of pressure sensitive tapes and labels, regardless of substrate.
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C. Control Techniques and Emission Reductions1
Almost all emissions from a coating line can be contained and sent
to a control device. Thermal incinerators and carbon adsorbers can
operate at 98 and 95 percent efficiencies, respectively. Use of low-solvent
coatings can achieve significant reductions in VOC emissions when substituted
for conventional organic solvent-borne coatings. One type, waterborne,
can effect an 80 to 99 percent reduction.
Fugitive emissions from solvent transfer, storage and mixing operations
can be reduced through good housekeeping practices, such as maintaining
lids on mixing vessels, and good maintenance, such as repairing leaks
promptly.
0. Regulatory Status1
The EPA issued a guideline in 1977 which recommends VOC emissions
from paper-coating lines be limited to 0.35 kilograms of VOC per liter of
coating minus water.
E. National Emission Estimates^
It has been estimated that 175,000 megagrams of VOC were emitted in
1984 by paper-coating operations (excluding those from coating pressure
sensitive tapes and labels). Emission estimates for pollution from
coating pressure sensitive tape and labels are given in Section 4.5.6.1.
F. Capital and Annual Control Costs^
The cost of carbon adsorption for a line coating adhesive onto
39 million square meters (10® m^) year of paper have been estimated as
$1,343,000 total installed capital costs and an annual operating credit
of $648,000 due to the value of recovered solvent. Control costs will,
of course, vary with the size of a line. Generally, the smaller the
line, the greater the cost of control per ton of solvent removed. Costs
for a range of line sizes are discussed in reference 5.
G. References
1. Control of Volatile Organic Emissions from Existing Stationary
Sources, Volume II: Surface Coating of Cans, Coils, Paper, Fabrics,
Automobiles, and Li'ght-Duty Trucks,.EPA-450/2-77-008, U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina, May 197 7.
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2. Census of Manufacturers, 1982. Bureau of Census, U. S. Department
of Commerce.
3. Paper Coating. In: Compilation of Air Pollutant Emission
Factors, Third Editor, Supplement No. 15, U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina, AP-42, January 1984.
4. Organic Solvent Use in Web-coating Operations, EPA-450/3-81-012,
U. S. Environmental Protection Agency, Research Triangle Park, North Carolina,
September 1981.
5. Pressure Sensitive Tape and Label Surface Coating Industry -
Background Information for Proposed Standards, EPA-450/3-80-003a,
U. S. Environmental Protection Agency, September 1980.
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4.5.1.6.1 Pressure Sensitive Tapes and Labels
A. Process and Facility Description^
The coating of pressure sensitive tapes and labels (PSTL) is an
operation in which a backing material such as paper, cloth, or cellophane
is coated one or more times to create a tape or label that sticks on
contact. Adhesives and release agents are the two primary types of
coatings applied in this industry. Essentially all of the VOC emissions
from the PSTL industry come from solvent-based coatings which are used to
produce 80 to 85 percent of al1 PSTL products.
In the solvent-based coating process, a roll of backing material is
unrolled, coated, dried, and rolled up. The coating may be applied to
the web by knife coater, blade coater, metering rod coater, gravure
coater, reverse roll coater, or a dip and squeeze coater.
After the coating has been applied, the web moves into a drying oven
where the web coating is dried by solvent evaporation and/or cured to a
final finish. Direct-fired ovens are the most common type used. Drying
ovens are typically multizoned with a separate hot air supply and exhaust
for each zone. The temperature increases from zone to zone in the direction
in which the web is moving, thus the zone maintained at the highest
temperature is the final zone that the web traverses before exiting the
oven. A large drying/curing oven may have up to six zones ranging in
temperature from 43°C to 204°C.
A tandem coating line is one in which the web undergoes a sequence
of coating and drying steps without rewidening between steps. Tandem
coating lines are usually employed by plants that manufacture large
volumes of the same product.
Over 100 plants with a total of about 300 coating lines produce
pressure sensitive tapes and labels in the United States.
B. Emission Sources and Factors^
By definition, all PSTL products have an adhesive coating. It is
generally the thickest coating applied and the source of 85 to 95 percent
of the total emissions from a line.
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In an uncontrolled facility, essentially all of the solvent used in
the coating formulation is emitted to the atmosphere. Of these uncontrolled
emissions, 80 to 95 percent are emitted from the drying oven. A small
fraction of the coating solvent may remain in the web after drying. The
remaining 5 to 20 percent of applied solvent is lost as fugitive emissions
by evaporation from a number of small sources such as the applicator
system and the coated web upstream of the drying oven. Some fugitive
losses also occur from storage and handling of solvent, spills, and mixing
tanks, and during cleaning of equipment, such as a gravure roll.
The emission factor for uncontrolled emissions from a drying oven
ranges from 0.80 to 0.95 kg VOC per kg of total solvent used. The emission
factors for fugitive losses in the plant and from the product due to
retention are estimated at 0.01 - 0.15 and 0.01 - 0.05 kg VOC per kg
total solvent u$ed, respectively.
C. Control Techniques and Emission Reductions^
Carbon adsorption and thermal incineration control systems are
.suitable for the PSTL Industry. Both systems can reduce the VOC emissions
directed to them by 95 percent. The overall control efficiency for both
devices is dependent upon the efficiency of the emission capture system.
Drying ovens capture 80 to 95 percent of VOC emissions from the
coating process. Floor sweeps and/or hooding systems around the coating
head and exposed coated web will increase the overall capture efficiency.
Total enclosure of the entire coating line or lines theoretically can
contain 100 percent of the emissions. By venting the exhausts from a
total enclosure to a carbon adsorber or incinerator, overall emission
control efficiencies of over 90 percent are possible.
An alternate emission control technique is the use of 'ow-V0C coatings
such as waterborne, hot-melt, and radiation cured coatings. Emissions of
VOC from such coatings are negligible. There may not be a low-VOC coating
available for every product in the PSTL industry.
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D. Regulatory Status
The EPA issued a control techniques guideline in 1977 for paper
coating, including the PSTL industry, which recommends emissions from
coating lines be limited to 0.35 kilograms of VOC per liter of coating
minus water.3 In 1983, the EPA promulgated NSPS standards (40 CFR 60
Subpart RR) which requires emissions from coating lines to be limited to
0.20 kilograms of VOC per kilogram of coating solids applied. A 90
percent overall VOC emissions reduction is considered equivalent to this
limit.
E. Current National Emission Estimate*
The estimated total national VOC emissions potential from the PSTL
industry is from 300,000 to 600,000 megagrams per year.
F. Capital and Annual Control Costs1
The control costs of carbon adsorption for a 39 million square meters
(10® m2)/yr production PSTL plant have been estimated as $1,343,000 total
installed capital costs and $648,000 total annual operating savings in
operating costs due to the value of recovered savings. These costs are for
a fairly large line which is typical of a manufacturing plant, but line
size for pressure sensitive tape lines can vary greatly. Reference 1 gives
costs for a range of line sizes.
G. References
1. Pressure Sensitive Tape and Label Surface*Coating Industry -
Background Information for Proposed Standards - and Promulgated Standards,
EPA-450/3-80-003a and b, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, September 1980 and September 1983.
2. Pressure Sensitive Tapes and Labels. In: Compilation of Air
Pollutant Emission Factors, Third Edition, Supplement No. 13,. AP-42, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina,
August 1982.
3. Control of Volatile Organic Emissions form Existing Stationary
Soruces - Volume II: Surface Coating of Cans, Coils, Paper, Fabrics,
Automobiles, and Light-Duty Trucks, EPA 450/2-77-008, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, May 1977.
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4.5.1.6.2 Magnetic Tape
A. Process and Facility Description
Organic solvent, metal-oxide particles and suitable resins are
combined to form the coatings used by magnetic tape coating operations.
The coating equipment consists of an unwind roll for the plastic film
substrate, a coating applicator, a drying oven and a windup roll for the
coated tape. The coating mixture is supplied to the plastic film substrate
by the coating applicator (often via some sort of roll or rotogravure
coater). The plastic film is carried through the drying oven where
organic solvent evaporates. The plastic substrate with the dried magnetic
coating is then rewound at the end of the line. Slitting operations to
produce the consumer product are almost always performed later as an
off-line operation.
B. Emission Sources and Factors
Roughly ten percent of the solvent used by a plant evaporates from
mix and storage tanks. Another ten percent evaporates from the coating
applicator and the flash-off area between the coater and the oven. The
remainder evaporates in the drying oven and is exhausted through the oven
exhaust stack.
A typical coating operation with one coating line would process
about 700 Mg of solvent annually. Of this, about 70 Mg will evaporate
from the mix room and storage areas. Ttie remainder, about 630 Mg, will
evaporate from the coating line.
C. Control Techniques and Emission Reductions*
The oven exhaust, which typically contains 80 percent or more of
the solvent used in the plant can be ducted to a control device operated
at more than 95% efficiency to remove organic solvents from the gas
stream. Carbon adsorption is the most commonly used control device since
the recovered solvent can be reused. Other control devices used by the
industry are incinerators and condensation systems.
Some plants have an enclosure around the coating applicator and
flashoff area. Emissions from the enclosure are ducted to the control
device. Vessels in the mix room can also be vented to a control device.
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D. Regulatory Status
The EPA issued a guideline (CTG) in 1977 for "paper coating" which
included magnetic tape and other plastic film coating.2 This CTG recommends
that emissions from the coating operation be no more than if a coating
containing 0.35 kg of VOC per liter of coating (minus water) is used.
This is equivalent to about an 81 percent reduction in emissions from a
typical operation. An NSPS currently being written for this industry
was proposed on January 22, 1986.3
E. Current National Emission Estimates
It is estimated that 38,000 Mg of VOC was used in the production
of magnetic tapes in the U.S. in 1984.4 Due abatement devices already
in use only about 20 percent of this solvent was actually emitted.
Therefore, emissions were about 7,600 Mg/year of VOC from all domestic
magnetic tape plants in 1984.
F. Capital and Annual Control Costs
For a typical line (0.66 meter wide, 2.5 m/second.1ine speed), the
capital cost for installing a carbon adsorber is $1,695,000.1 The annual
operating cost and capital charges for the absorber are estimated to be
$43,200. This fairly low operating cost results from the large credit
for recovered solvent which offsets part of the annualized capital cost.
These costs are for a large line which is typical of manufacturing plants.
Smaller lines are becoming increasingly popular. Their control equipment
costs are lower, but recovered solvent credit is less. See reference 1
for a full cost analysis of various size lines.
G. References
1. "Magnetic Tape Manufacturing Industry - Background Information
for Proposed Standards," Preliminary Draft, U.S. Environmental Protection
Agency, November 1984.
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2. "Control of Volatile Organic Emissions from Existing Sources -
Volume II: Surface Coating of Cans, Coils, Paper, Fabrics, Automobiles
and Light-Duty Trucks," U.S. Environmental Protection Agency,
EPA-450/2-77-008, May 1977.
3. January 22, 1986, Federal Register, page 2996.
4. "Organic Solvent Use in Web Coating Operations," U.S. Environmental
Protection Agency, EPA-450/3-81-012, September 1981.
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4.5.1.7 Fabric Coating And Printing
A. Process and Facility Description
Fabric coating involves the application of decorative or protective
coatings to a textile substrate. A large segment of this industry is
application of rubber coatings to fabrics.1 More specifically, for
purposes of the regulatory program, fabric coating is the uniform application
of, 1) an elastomeric or thermoplastic polymer solution, or 2) a vinyl
plastisol or organisol, across all of one (or both) side of a supporting
fabric surface or substrate.2 The coating imparts to the fabric substrate
such properties as elasticity, strength, stability, appearance, and
resistance to abrasion, water, chemicals, heat, fire or oil.3 Coatings
are usually applied by blade, roll coater, reverse roll coater, rotogravure
coater, or dip coater.
The basic fabric coating process includes preparation of the coating,
the application of the coating to the substrate, and the drying/curing of the
applied coating. The web substrate is unwound from a continuous roll, passed
through a coating applicator and drying/curing oven, and then rewound.
Fabric printing is application of a decorative design to a fabric
by intaglio (etched) roller (another name for rotogravure), rotary screen,
or flat screen printing operation. The fabric web passes through the
print machine where a print paste is applied to the substrate. After
leaving the print machine, the web passes over steam cans or through a
drying oven to remove water and organic solvent from the printed product.
After the drying process, the fabric is washed and dried again.4
There are at least 130 fabric coating plants^ and approximately
200 fabric printing plants4 located throughout the United States.
B. Emission Sources and Factors
The major sources of VOC emissions in a fabric coating plant are the
mixer and coating storage vessels, the coating applicator, and the drying
oven. The relative contribution of these three areas are estimated at 10
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to 25 percent, 20 to 30 percent and 45 to 70 percent, respectively. The
potential VOC emissions from a fabric coating plant are equal to the
total solvent used at the pi ant.2
The most significant source of VOC emissions in a fabric printing
plant is the drying process, either the steam cans or the ovens. Other
emissions occur as fugitive VOC. These are as evaporation from wastewater
streams, open print paste barrels, printing troughs, the printing rollers
and screens, "strikethrough" onto the backing material, and from the
printed fabric before it reaches the drying process. Average emission
factors for printing fabric are 142 kg VOC per 1000 kg fabric for roller
printing, 23 kg VOC per 1000 kg fabric for rotary screen printing, and 79
kg VOC per 1000 kg fabric for flat screen printing.5
C. Control Techniques and Emission Reductions
Incineration is the most common means for control of coating application
and curing emissions on fabric coating lines which use a variety of coating
formulations. Coaters which use a single solvent can be most economically
controlled by carbon adsorption.2 Either of these control devices can
reduce the VOC emissions in the gases directed to the device by 95 percent
or more. Inert gas condensation systems may be applicable to some fabric
coating 'ines. Such systems are estimated to be about 99 percent efficient
in the recovery of solvent which passes through the system.3
The overall emission reduction achievable by any of technology
depends on the efficiency of the vapor collection or capture device.
Total enclosure of the coating and flashoff area should allow the operator
to achieve a 95 percent capture efficiency. Partial enclosures, more
common in this industry, should achieve 90 percent capture or more, if
well-designed. Fugitive losses from solvent storage tanks may be reduced
through use of pressure vacuum relief valves or disposable-canister
carbon adsorbers.3
Presently there is no fabric printing plant that has installed
add-on emission control technology for organic emissions.5
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The use of low-solvent coatings or inks is an effective technique
to reduce VOC emissions from both the fabric coating and printing industries.
Waterborne, higher-solids, plastisol, calendered and extruded coatings
are presently used in a significant number of fabric coating plants.3
Use of low-solvent print pastes by the fabric printing industry has increased
in the past decade. Significant reductions in VOC emissions have been
achieved by switching to rotary screen printing processes that utilize
waterborne print paste, or to a lesser extent, replacing the mineral
spirit based intaglio inks with waterborne, foamed intaglio inks. Substitution
of low-solvent coatings in place of conventional solvent-borne coatings
can reduce VOC emissions by 60 to 98 percent, depending upon the formulations
of the before and after coatings.®
D. Regulatory Status
The EPA issued a guideline (CTG) in 1977 which recommended emissions
from fabric coating lines be limited to 0.35 kilograms of VOC per liter
of coating (minus water). This limit was derived from use of an add-on
control that results in an 81 percent overall emission reduction.7 The
EPA is currently developing a NSPS standard to regulate the emissions from
polymeric coatings of supporting webs. It will restrict emissions from
new fabric coating but not fabric printing operations.
Emissions from fabric printing lines are currently limited only by
individual State regulations.
E. Current National Emission Estimates
The potential nationwide uncontrolled VOC emissions were estimated
to have been 29,000 to 35,000 megagrams (in 1984) from fabric coating^
and approximately 38,000 megagrams (in 1982) from fabric printing.8
F. Capital and Annual Control Costs
Capital and annualized cost of pollution control for fabric coaters
are influenced primarily by the choice of abatement equipment, the total
amount of VOC generated by the process being controlled and the level of
control that is required. The VOC that is generated is a function of
process rates, solvent content of the coatings and the rate of coating
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consumption. Presented below is a table of capital and annualized cost
(May 1984) for two types of control equipment and three rates of solvent
usage. The analysis used to produce these values assumes the level of
VOC control is 81 percent.
Solvent Usage |
Capital
Cost ($)
Annualized Cost ($)
(Mgs/yr) |
Carbon |
1
Carbon |
1
Adsorption |
Condensation I.
Adsorption |
Condensation
95 |
286,000 |
168,000 |
62,000 |
23,000
154 |
261,000 |
147,000 |
43,000 |
15,000
308 |
352,000 |
223,000 |
37,000 |
savings
For more details on control cost for fabric coatings, refer to reference 3.
Capital and annualized cost of pollution control for fabric printers are
influenced generally by the same factors. One additional key determinant
of solvent use, however, is whether the printing machine is rotary screen,
flat screen, or roller. The solvent content for each respective type of
print paste is different. The different pieces of equipment result in
rather divergent process emission profiles, i.e., relative amounts of
fugitive, flash off and oven emissions. Below are three sets of capital and
annualized cost (May 1984) based on printing machine type.
| Organic
Capital
Cost ($)
Annuali zed
Cost ($)
Printing
I Solvent
Carbon
Carbon
1
Machine Type
|Consumption(Mqs/yr)
Adsorption
I Incineration
Adsorption
I Incineration
Rotary Screen
| 270
990
| 1,020,000
1,310,000
| 1,390,000
F1at Screen
| 30
790
| 840,000
600,000
| 620,000
Ro1ler
| 290
650
| 620,000
1,270,000
| 1,400,000
For additional information on control costfor fabric printing, refer to
reference 10.
G. References
1. Summary of Group I Control Technique Guideline Documents for
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Control of Volatile Organic Emissions from Existing Stationary Sources.
EPA-450/3-78-120 U. S. Environmental Protection Agency, Research Triangle
Park, N.C., December 1978.
2. Fabric Coating In: Compilation of Air Pollutant Emission Factors,
Third Edition, Supplement No.15, AP-42, U. S. Environmental Protection Agency,
Research Triangle Park, N.C., January 1984.
3. Polymeric Coating of Supporting Substrates - Background Information
for Development of New Source Performance Standards (Draft), EPA Contract No.
68-02-3817, October 1985.
4. Fabric Printing. In: Summary of Technical Information for
Selected Volatile Organic Compound Source Categories, EPA-450/3-81-007,
U. S. Environmental Protection Agency, Research Triangle Park, N.C., May 1981.
5. Texti.le Fabric Printing. In: Compilation of Air Pollutant
Emission Factors, Third Edition, Supplement No.13, AP-42, U. S. Environmental
Protection Agency, Research Triangle Park, N.C., August 1982.
6. General Industrial Surface Coating. In: Compilation of Air Pollutant
Emission Factors, Third Edition, Supplement No. 15, AP-42, U. S. Environmental
Protection Agency, Research Triangle Park, N.C., January 1984.
7. Control of Volatile Organic Emissions from Existing Stationary
Sources - Volume II: Surface Coating of Cans, Coils, Paper, Fabrics,
Automobiles, and Light-Duty Trucks. EPA-450/2-77-008. U. S. Environmental
Protection Agency, Research Triangle Park, N.C., May 1977.
8. Memorandum from Johnson, W., EPA to Berry, J., EPA. Emission Estimates
for CAS Industries, December 16, 1982.
9. Memorandum from Banker, L., MR I; to Crumpler, D., EPA. Final
Tabular Costs, Polymeric Coating of Supporting Substrates, November 29, 1984.
10. Economic Impact Analysis of Catalytic Incineration and Carbon
Adsorption on the Fabric Printing Industry, EPA Contract No. 68-02-3535,
November 1981.
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4.5.1.8 Metal Furniture
A. Process and Facility Description*,2
Metal furniture coating consists of the application of prime and top
coatings to any piece of metal furniture or metal part included in the
categories of household furniture, office furniture, public building and
related furniture, and partitions and fixtures. Typically, the metal
substrate is first cleaned, rinsed in a phosphate bath and oven-dried to
improve coating adhesion. If a prime coat is necessary, the part may be
dipped, sprayed, or flow coated and then dried in a curing oven.
Subsequent top coats, or in the event no prime is requied, the single
topcoat is usually by spray. The freshly-coated parts are conveyed to
the oven through a flashoff tunnel during which the coating "flows out"
to a'uniform thickness and some of the solvent evaporates. The parts are
baked in single or multi-pass ovens at 150-230°C.
There are approximately 1400 known domestic metal furniture coating
plants, including 445 for household and 253 for office furniture.-* There
are likely several hundred more that custom manufacture, finish or refinish
metal furniture that have not yet been identified.
B. Emission Sources and Factors
Specific emission sources on the coating line are the coating
application, the flash-off area and the bake oven. On the average conveyorized
spray coating line, it is estimated that about 40 percent of the total
VOC emissions come from the application station, 30 percent from the
flash-off area, and 30 percent from the bake oven. In addition, fugitive
emissions also occur during mixing and transfer of coatings. The uncontrolled
VOC emission factor for a metal furniture coating is 0.66 kilograms of
VOC per liter coating (minus water).
C. Control Techniques and Emission Reductions*
Control techniques used by this industry include converting to
low-solvent coatings, improving transfer efficiency with state-of-the-art
application equipment or incineration. Adoption of high-solids or waterborne
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coatings can reduce VOC emissions from prime-coating operations by
70 and 92 percent, respectively. Conversion to an electrodeposition
prime coat can reduce emissions by 94 percent. Emissions from topcoats
can be reduced by conversion to waterborne, high-solids or powder coatings,
giving reductions of up to 80 percent, 70 percent, and 99 percent, respectively.
Transfer efficiency (TE) is the ratio of the amount of coating
solids deposited onto the surface of the coated part to the total amount
of coating solids used. Improved TE decreases the volume of coating that
must be used, thereby decreasing the total VOC emission rate.
Historically, the large volumes of air used to ventilate open-spray
booths and flash-off areas made the expense of incinerating emissions from
these sources prohibitive. Many industries are now applying a novel air
management techniques to reduce the exhaust gas rates, thereby making
VOC control feasible at more reasonable cost. Incineration of the curing
oven exhaust can reduce overall emissions from the metal furniture surface
coating line by up to 25 percent. Coupled with other technologies noted
above, incineration can achieve even larger plant-wide emission reductions.
D. Regulatory Status
The EPA issued a guideline (CTG) in 1977 and set NSPS standards in
1982 (40 CFR 60, Subpart EE) to control emissions from surface coating of
metal furniture. Based on emission reductions achievable by converting
to low solvent coatings, the CTG recommends an emission limit of 0.36
kilograms of VOC per liter of coating minus water.5 The NSPS requires
emissions be limited to 0.90 kilograms of VOC per liter of coating solids
applied. The limit is based on the use of a coating with 62 percent by
volume solids and a 60 percent TE.
E. National Emission Estimates
It is conservatively estimated that surface coating of metal furniture
results in emissions of about 95,000 megagrams of VOC per year.®
F. Capital and Annual Control Costs
The captial and annualized cost of control using low solvent coating
technology depends upon the type coating that is selected, the size of
the operation, the type of substrates that are coated, and the resulting
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TE. Capital costs will generally reflect charges to the painting lines,
and extra or new equipment necessary for applying the new coating technology.
The annualized cost will primarily reflect changes in coating consumption
which is a function of the transfer efficiency and the solids content of
the new coating.
The table below presents a few capital and annualized costs (May 1984)
for various types of low solvent coating technologies and three sizes of
pi ants.
Facility Size (M? coated) 4,000,000
yr
Substrate Shape/TE Flat/85%
Application Method Spray.
780,000
Complex/65%
sPray
45,000
Flat/85%
Spray
Coating Technology
Powder
Waterborne
70% Solids
65% Solids
60% Solids
Cost ($)
Cost ($)
Cost (S)
Capital
356,000
1,000,000
-0-
-0-
-0-
Annualized
163,000
287,000
Capital[Annualized
124,0001
Capital Annualized
42,000
308,000|
-0- |
-0- I
-0- I
85,000
46,000
-0-
-0-
-0-
Note that the costs for 60, 65, and 70 solids coatings are essentially the
same as for conventional coatings. See reference 1 for more details on
capital and annualized cost.
G. References
1. Surface Coating of Metal Furniture - Background Information for
Proposed Standards, EPA-450/3-80-007a, U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina, September 1980.
2. Summary of Group I Control Technique Guideline Documents for
Control of Volatile Organic Emissions from Existing Stationary Sources,
EPA-450/3-78-120, U. S. Environmental Protection Agency, Research Triangle
Park, North Carolina, December 1978.
8,000
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3. Census of Manufacturers, 1982. Bureau of Census, U. S. Department
of Commerce.
4. Metal Furniture Surface Coating. In: Compilation of Air
Pollutant Emission Factors, Third Edition, Supplement No. 14, AP-42,
U. S. Environmental Protection Agency, Research Triangle Park, North
Carolina, May 1983.
5. Control of Volatile Organic Emissions from Existing Stationary
Sources, Volume III: Surface Coating of Metal Furniture, EPA-450/2-77-032,
U. S. Environmental Protection Agency, Research Triangle Park,
North Carolina, December 1977.
6. 1982 data provided by the National Paint and Qoatings Association.
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4.5.1.9 Mood Furniture
A. Process and Facility Description*
The wood furniture industry is one of the largest sources of VOC
emissions among surface coating industries for three reasons: 1) it is a
large industry, 2) the coatings traditionally used contain very little
solids material, about 90 percent or greater is solvent and 3) because of
the extremely low solids content of the coatings, very high volume of
coatings are required to build the coating film on the manufactured
product. Kitchen cabinet and household furniture plants account for
almost 90 percent of all wood furniture facilities. Most wood furniture
products are coated in a roughly similar way, although furniture will
usually receive a much more elaborate series'and greater number of finishes
than kitchen cabinets.
The coating finish is applied in a series of steps. The number and
complexity of coating steps may vary greatly, but the usual sequence is
as follows: body stain, wash coat, filler, sealer, glaze and shading
stains, and the final topcoat. The various layers of coating used in a
particular case are referred to collectively as a coating system. Furniture
finishing is still something of an 'art and the techniques, equipment, and
procedures may vary considerably from plant to plant.
In larger furniture factories with conveyorized coating lines,
coatings are usually applied by air spray at a separate spray booth for
each coating operation. After the coating is applied at one spray booth,
the conveyor carries it either to the next spray booth or to an oven.
Ovens for wood furniture are set at relatively low temperatures since
almost all wood finishes are lacquer solutions and the oven accelerates
evaporation of the solvent. Wood furniture coatings generally are not of
a type that require baking or curing. Coating lines without ovens rely
on "air drying" or evaporation of the solvent at ambient temperature.
There are currently over 2,500 wood household furniture plants and
approximately 3,000 wood kitchen cabinet plants in the United States.2
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B. Emission Sources and Factors1
Individual furniture factories vary greatly in size, but a moderately
large factory can emit around 1300 kilograms of VOC per day or over 300
megagrams per year. The amount of solvent emissions from a piece of
furniture depends on the amount of each type of coating used as well as
its solvent content. The source of essentially all VOC emissions in this
industry is the evaporation of solvents from the applied coatings.
More VOC emissions come from application of the topcoat than from
any other single step in the coating system. Usually the topcoat material
is applied in two or three consecutive layers, each of which completely
coat the part. An emission factor for each layer is approximately 14 kg
of VOC per 100 square meters. Overall emission levels for a coating
system range from 85 to 160 kilograms of VOC per 100 square meters of
surface coated.
C.' Control Techniques and Emission Reductions
Is is possible to reduce VOC emissions from wood furniture finishing
operations by changes in coating materials or processes and/or by the use
of add-on emission control devices. Material changes involve substituting
coatings that have less VOC components, such as waterborne and higher
solids coatings. Process changes can reduce the quantity of coating being
wasted. A promising process change is the installation of electrostatic
spray equipment to decrease paint waste. Manufacturers of air-assisted
airless spray guns indicate that this type of spray equipment will improve
transfer efficiency and reduce emissions. Add-on controls to reduce VOC
emissions have not been used by this Industry. Incineration would be the
most practical abatement technique. Its cost, however, will be excessive'
until the industry explores innovative air management techniques such as
enclosure of the spray booth and some scheme for recirculating the air
which ventilates the booth.
Recent gains by foreign manufacturers in domestic sales of "flat
line" furniture is awakening segments of the wood furniture industry to the
need to investigate modern manufacturing techniques and improved coating
systems. (Flat line furniture is a "modern" type furniture that is coated as
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panels lying flat on a moving conveyer. The flat pieces are subsequently
assembled Into "boxy" shaped furniture.) Coatings used are opaque,
catalyzed high solids materials that require oven curing. A typical flat
line coating could emit 80 percent less emissions than conventional
materials based on lower VOC content alone if high solids catalyzed
coatings are used.
Conversion to systems that use waterborne coatings could reduce
emissions from 26 to 94 percent. Electrostatic spray equipment can
reduce VOC emissions by about 50 percent as a result of improved transfer
efficiency. Where incinerators are used, control efficiencies of at
least 90 percent can be attained on the VOC directed to the incinerator.
D. Regulatory Status
Emissions from coating of wood furniture are currently limited by a
few State regulations. Illinois and California are two States that have
drafted such rules. California's model rule, which has been adopted in
the Los Angeles area, focuses on improved transfer efficiency of the
spray operation.
E. Current National Emission Estimates
Total VOC emissions from coating wood furniture in 1984 have been
estimated to be about 200,000 megagrams.3
F. Capital and Annual Control Costs*
The capital and total annualized costs of control by converting to
waterborne coatings at a medium-sized wood furniture plant with 12 spray
booths and 12 ovens are estimated at about $368,000 and $68,000, respectively.
Since very little use has been made of waterborne coatings in the wood
furniture Industry, these costs are somewhat hypothetical.
G. References
1. Surface Coating of Wood Furniture. In: Summary of Technical
Information- for Selected Volatile Organic Compound Source Categories,
EPA-450/3-81-007. U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, May 1981.
2. Census of Manufacturers, 1982. Bureau of Census, U.S. Department
of Commerce.
3. Based on information provided by the National Paint and Coatings
Association, Inc.
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4.5.1.10 Flat Wood Paneling
A. Process and Facility Description*
A typical flat wood coating facility applies stains and varnishes to
natural plywood panels used for wall coverings. Other plants print wood
grain patterns on particle board panels that were first undercoated with
an opaque coating to mask the original surface. Coatings applied to flat
wood paneling include fillers, sealers, "groove" coats, primers, stains,
basecoats, inks and topcoats. Most coatings are applied by direct roll
coating. Filler is usually applied by reverse roll coating. The offset
rotogravure process is used where the coating and printing operation
requires precision printing techniques. Other coating methods include
spray techniques, brush coating and curtain coating. A typical flat wood
paneling coating line includes a succession of coating operations. Each
individual operation consists of the application of one or more coatings
followed by a heated oven to cure the coatings. A typical production
line begins with mechanical alterations of the substrate (filling of
holes, cutting of grooves, sanding, etc.), followed by the coating operations,
and packaging/stacking for shipment. Approximately 60 domestic plants
coat flat wood paneling.2
B. Emission Sources and Factors
Emission of VOC from a flat wood coating occurs primarily at the
coating line, although some emissions also occur at paint mixing and
storage areas. All solvent that is not recovered can be considered a
potential emission. VOC emission factors for conventional solvent based
coatings applied to interior printed panels are as follows (expressed as
kilograms of VOC per 100 m2 coated): 3.0 for filler, 0.5 for sealer, 2.4
for basecoat, 0.3 for inks, and 1.8 for topcoats.1
C. Control Techniques and Emission Reduction1
Control techniques for flat wood panels include add-on controls,
materials changes and process changes. Incineration should give a minimum
control efficiency in excess of 95 percent of the VOC captured. Overall
plant control would be less because not all organic emissions could be
captured. Conversion to waterborne coatings can lower VOC emissions by
4-143
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at least 70 percent. Use of low solvent coatings that cure by ultraviolet
light is gaining greater acceptance and, where applicable, effects a near
100 percent reduction of VOC emissions. Over 99 percent reduction can be
achieved by using coatings that cure by exposure to an electron beam, but
costs of both the cure system and coatings limit the applicability of this
technique at this time.
0. Regulatory Status
The EPA issued a guideline* (CTG) in 1978 recommending emission
limits for VOC from the surface coating of flat wood paneling. These
limits are given in the table below and are based upon the partial use of
waterborne or low solvent coatings.
FACTORY FINISHED PANELING
Product Category Recommended Limitation
kg of VOC per
100 sq meters of
coated surface
Printed interior wall panels made of O
hardwood plywood and thin particle board
Natural finish hardwood plywood panels 5.8
Class II finishes for hardwood 4.8
paneling
E. National Emission Estimate-*
It has been estimated that surface coating of flat wood paneling
emitted 24,000 metric tons of VOC in 1981.
F. Capital and Annual Control Costs*
For a plant producing about 61.5 million square feet of paneling
per year, the capital cost of changing to waterborne coatings is estimated
to be $77,000. This gives an annualized capital charge of $13,000. The
main additional annual expense would be the slight difference in material
cost between waterborne and solvent-borne coatings. Costs for add-on
controls such as incinerators will change with line size. Reference 1
contains a thorough discussion of these costs for various size lines.
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G. References
1. Control of Volatile Organic Emissions from Existing Stationary
Sources, Volume VIII: Factors Surface Coating of Flat Wood Paneling, EPA-
450/2-78-032, U. S. Environmental Protection Agency, Reserch Triangle
Park, North Carolina, June 1978.
2. F1 at wood Paneling Surface Coating Plants. In: Directory of
Volatile Organic Compound Sourcs Coverred by Reasonably Available Control
Technology (RACT) Requirements, Volume II: Group II RACT Categories, EPA-
450/4-81-0076, U. S. Environmental Protection Agency, Research Triangle
Park, North Carolina, February 1981.
3. Based on 1981 production data supplied by the National Paint
and Coatings Association, Inc.
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4.5.1.11 Other Metal Products
A. Process and Facility Description*
The original equipment manufacturers discussed here have been
referred to by a variety of names, including coaters of miscellaneous
metal parts. The category includes hundreds of small- and medium-sized
industries and their companies which coat metal parts for which more
specific regulatory guidance was not published as part of the guideline
series, (i.e. can, coil, wire, automobile and light-duty truck, metal
furniture, and large appliances covered in sections 4.5.1.1 - 4.5.1.8).
Although many products are coated by manufacturers in this category, the
coating processes have many features in connon. Typically, the metal
substrate is first cleaned, rinsed in a phosphate bath and oven-dried to
minimize contamination and maximize coating adhesion. If a prime coat is
used, it may be applied by dipping, spraying, or flow-coating. The part
is then dried in a curing oven. Subsequent top coats, or if no prime is
used, the single topcoat is usually applied by spray. The freshly-coated
parts are often conveyed through a flash-off tunnel or room , permit the
coating to flow out to a uniform thickness. Some of the solvent will
evaporate during this time. The parts are then baked in single or multi-pass
ovens at 150-230°C. Large products with high mass such as large industrial,
construction, and transportation equipment are usually coated with materials
that will cure by air- or forced air-drying, rather than baking, since
the specific heat capacity of the large mass makes raising its temperature
high enough to cure a coating in an oven prohibitively expensive.
B. Emission Sources and Factors**^
Organic emissions from coating miscellaneous metal parts and
products are emitted from the application, flash-off area and the bake oven
(if used). The bulk of VOC emitted by lines which spray or flow coat,
evaporates from the application and flash-off areas. For dip-coating
operations, the bulk of the VOC is emitted from the flash-off area and
bake oven. Fugitive emissions also occur during mixing and transfer of
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coatings. The uncontrolled VOC emission factor for a coating containing
25-volume percent solids and 75-volume percent organic solvent is 0.66
kilograms of VOC per liter of coating (minus water) consumed.
C. Control Techniques and Emission Reductions*
Control techniques available to the industries that coat miscellaneous
metal parts and products include converting to low-solvent coatings, improving
transfer efficiency with state-of-the-art application equipment, or inciner-
ation. Spray application of waterborne coatings can reduce emissions by
70 to 95 percent; use of higher solids coatings from 50 to 80 percent;
and powder coatings, 95 to 98 percent. Use of electrodeposition (EDP) to
apply prime coats can reduce emissions up to 94 percent over conventional
coatings used for operations. Transfer efficiency is the ratio of the
amount of coating solids deposited onto the surface of the coated part to
the total amount of coating sol Ids used. Improvements 1n transfer efficiency
will decrease the volume of coating that must be sprayed to cover a
specific part. Of course, the less paint used, the lower the total VOC
emission rate.
Historically, the large volumes of ai.r used to ventilate open spray
booths and flash-off areas made the expense of incinerating emissions
from these sources prohibitive. The VOC in the exhaust from a curing
oven, however, can be concentrated (by reducing air throughput), to
levels that makes incineration feasible. Incineration of the curing oven
exhaust can reduce emissions from the surface coating line from 15 - 25
percent, depending on how much of the total emissions from the line are
released from the oven.
0. Regulatory Status*
The EPA issued a control technique guideline (CTG) in 1978 to aid
States in development of regulations for plants that surface coat miscellaneous
metal parts and products. The recommended limits are given in Figure
4.5.11.1. To use the figure, start at the top of the diagram and at each
decision node, choose the appropriate option.
4-147
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Manufacture of Metal Parts and Product!
Can
Frequent color crianoe anc/
or large numoer 3f colors
aoplied, or Hrst coat an
untreated ferrous suDstrata
0.36 kg/liter
(3.0 Ibs/aal) (7)
Other
Coil
Auto
and
light
. Cuty
Truck
Metal1 '
Furniture
Otner
Wire
Other^ '
3.36 kg/liter
(3.0 lbs/gal
No or infrequent color chanae
or small number of colors
applied.
Outdoor or harsn
exoosure or extreme
performance
characteristics ,
0.42 kg/liter l5)
(3.5 lbs/gal)
Air or forced air-dned items:
Parts too large or too heavy for
practical size ovens and/or sensi-
tive neat requirements. Parts to
which heat sensitive materials are
attached, equipment assembled
prior to too coating for soecific
performance or juality standards.
0.42 kq/Mier (3.S lbs/gal) v5)
Clear Coat 0.S2 kg/1iterv
(4.3 lbs/gal)
logic diagram for derivation of emission
limits for coatina of miscellaneous ^ietal parts and
products.
Figure 4.5.11.1
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E. National Emission Estimate
It is estimated that emissions from surface coating o-f miscellaneous
metal parts and products amounts to 330,000 megagrams of VOC yearly.2
F. Capital and Annual Control Costs^
A conveyorized single-coat spraying operation which coats 743,000 m^/yr
and uses incineration control is estimated to have capital and annual control
costs of $1,400,000 and $460,000, respectively (May 1984 dollars). It is
likely that most companies will plan to adapt low solvent coatings to
comply with the regulations rather than attempt to abate.
The cost of complying with low solvent coatings will be dependent on
the particular type of coating technology that is chosen and the shape of
the substrate(s) being coated which affects the transfer efficiency of
the application equipment. Cost of using higher solids paints would be
comparable to the cost of applying conventional paints; therefore, the
control cost would be negligible. The cost of using waterborne or powder
coatings would be the same as or similar to cost for other coating industries
that use those technologies. See section 4.5.1.8, Surface Coating of
Metal Furniture, for additional cost information on waterborne and powder
coatings.
G. References
1. Control of Volatile Organic Emissions from Existing Stationary
Sources, Volume VI: Surface Coating of Miscellaneous Metal Parts and Products,
EPA-450/2-78-015, U. S. Environmental Protection Agency, Research Triangle Park,
North Carolina, June 1978.
2. 1982 data provided by the National Paint and Coatings Association.
3. Memorandum from Crumpler, D., U.S. Environmental Protection Agency/
0AQPS to File #84/21, VOC CTD, Emission Estimate for Miscellaneous Metal
Parts and Products, May 31, 1985.
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4.5.1.12 Surface Coating of Large Aircraft*^
A. Process and Facility Description
The original equipment aircraft industry (not including refinishers
of commercial and private aircraft) consists of about 175 establishments
operated by 38 companies. They manufactured about 20,000 civilian and
military aircraft in 1977 of which about 5,600 were exported. Aircraft
are coated in facilities across the Nation but California, Texas, and
Florida have particularly large numbers of plants.
The surface coating process for aircraft is relatively simple and
straightforward, a "batch" type operation with one aircraft painted at a
time. The first step 1s to prepare the skin of the aircraft to receive
the coating. This could require sandblasting, or blasting with plastic
beads followed by a solvent wipe.
The second step is application of a prime coating. It serves two
main functions. It provides corrosion resistance in case the topcoat
falls and it provides an intermediate surface to maximize bonding between
the topcoat and substrate.
The final step, application of the topcoat provides col or,-corrosion
protection, and, ideally, minimizes aerodynamic drag. Companies are very
sensitive to the coating systems used on aircraft. Weight of the coating
is kept to a minimum because excessive amounts increase fuel consumption
and reduce the allowable payload. Two component polyurethanes are considered
the best and most widely used topcoat for all types of aircraft.
To reduce exposure to contamination during painting, the aircraft is
generally wheeled Into an enclosed hangar, although some establishments
have huge "spray booths" that can accommodate the plane.
The coatings are applied manually, often from mobile hydraulic
scaffolding that permits the operator to move about and over all parts of
the aircraft. The spray application methods presently used include air
spray, air-assisted airless spray and electrostatic.
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B. Emission Sources and Factors
The major VOC emissions are the solvent used to clean the substrate
prior to coating (solvent wipe) and the VOC emitted during flash-off and
cure of the prime and topcoats. It is estimated that large transport-type
aircraft require about 60 gallons of primer and 80 gallons of topcoat
each, whereas general aviation aircraft, those fixed wing aircraft that
seat 2 to 20 people, require 10 and 7 gallons, respectively.
Additional emissions may result during thinning and from poor house-
keeping practices such as spillage, waste disposal and clean-up procedures.
C. Control Techniques and Emission Reductions
There are three obvious approaches to reduce VOC emissions from coating
aircraft: improve the method of application, convert to low-VOC coatings,
and emphasize good housekeeping . Use of add-on control devices has been
limited to-date (partially because of the large volumes of air required
for ventiHating the spray chamber with once-through air systems).
Although the Air Force is known to operate a conventional carbon adsorber
at one repaint facility. Abatement may gain greater favor as States
place greater emphasis on control. If they do, present abatement costs
can be ameloriated in several ways including: 1) recent commercialization
of a unique new adsorbtion system which removes dilute organics from one
stream and concentrates them into an air stream of much lower volume,
thereby making recovery or combustion much less costly, 2) new air manage-
ment schemes that permit much of the exhaust from a spray booth to be
recycled, thereby reducing the cost of abatement and, 3) increasing use
of personal air supplies that permit a reduction in the ventilation rate
within a spray booth thereby decreasing abatement costs.
Since the quantity of VOC emissions from a surface-coating operation
depends on the amount of coating applied, improvements in the efficiency of
coating application or reductions 1n the VOC content of the coating will
reduce emissions. Surface coating of aircraft is done by spray coating,
and the transfer efficiency of the application method is a major factor
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in the production of VOC (and also, amount of paint wasted). In general,
transfer efficiencies vary with the configuration of the part being
coated, the coating being applied, the equipment, and the skill and care
of the operator.
Primers and topcoats can be applied by various spray techniques.
These include air spray (both hot and cold), airless spray (both hot and
cold), air-assisted airless spray (both hot and cold), electrostatic air
spray, electrostatic-airless spray, and electrostatic air-assisted airless
spray. An air spray produces a fine spray, but the air which aspirates
the coating through the nozzle (at a rate of 8 to 30 scfm) also introduces
turbulence. This air turbulence interferes with movement of the paint to
the substrate and causes excessive "overspray," or waste. The ratio of
the amount of material deposited on the surface being painted to the
amount of material delivered from the spray gun is low. Airless spray
which uses air only to pressurize the tank which delivers paint to the
spray gun minimizes overspray; however, the particle size from an airless
spray are larger and heavier and paint is wasted when these heavier
particles drip to the floor before arriving at the substrate. Proponents
of the air-assisted airless spray claim it to both eliminates drips or
"tailings" and better focuses the spray pattern and consequently has a
better transfer efficiency than either of the other two spray systems.
Changing to coatings which have less volatile organic compounds in the
coating will also reduce emissions. A water-reducible epoxy primer has
been approved for use on some military aircraft.3 it has less than 2.9 lb
VOC/gal coating (350 g/1) versus 5.4 lb VOC/gal coating (650 g/1) for
typical solvent-based primers. Substitution of the water-reducible
primer for solvent-based primer would reduce VOC emissions from priming
operations by about 80 percent. There currently are no waterborne top coat-
ings that meet military specifications. The most promising coating technology
for topcoats appears to be two component, reaction type chemistries such as
polyurethanes.
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D. Regulatory Status
California limits emissions from coating aircraft coating. California
Rule 67.9 Aerospace Coating Operations is applicable to coating, masking,
surface cleaning and paint stripping. Effective in August, 1983, the
rule originally restricted emissions from prime coat to 650 grams of VOC
per liter and those from topcoat to 600 grams per liter. In July 1985,
the standard automatically become more stringent, allowing prime coats to
release only 350 grams per liter and topcoats, 600 grams per liter. The
regulation also limits several other smaller sources within the plant
including emissions from pretreatment coatings, strippers, and maskants.
It provides special consideration for coatings used for fuel tanks or to
avoid electromagnetic radar detection.
E. National Emission Estimates
In 1976, an estimated 220,000 gallons of primer and 196,000 gallons
of topcoat were used. Assuming 30 percent solids coatings, this represents
approximately 1,400 tons of VOC emissions annually, or 4 tons daily. Of
this, general aviation aircraft account for about 65 percent.
F. References
1. Surface Coating of Large Aircraft, Technical Information Document
for Development of a Revised Ozone State Implementation Plan for Birmingham,
Alabama, November 28, 1984.
2. Surface Coating in the Aircraft Industry; Booze, Allen and
Hamilton, Inc., September 29, 1978.
3. Bud Levine, Development and Application of a Water-Reducible
Primer for the Aerospace Industry, presented at the 77th Annual Meeting
of the Air Pollution Control Association, June 1984.
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4.5.1.13. Ships and Recreational Boats*
A. Process and Facility Description
Approximately 475 establishments were engaged in building and repairing
all ships**, barges and lighters in 1975. Over half of these were small,
employing less than 50 personnel. There were about 1,600 engaged in
building and repairing all types of recreational boats. Almost 90 percent
of these have less than 50 employees.
Construction of a new ship requires the steps below and might take
3 months to 3 years to complete, depending on the size of the vessel:
- Steel plates are for the shell sand-blasted in a blast mill.
- Plates are coated with 0.5 mil weldable preconstruction primer coating.
- Plates are cut and fabricated into panels which are then assembled into
ship sections (units and sub-units) in shops.
- Preconstruction primer may then be removed by blasting after which
welding areas are masked off and the remaining areas painted (interior
and exterior) with primer and/or first coat.
- Units are then assembled, welded, and tested for strength before the
final finish coating, including topcoat and any antifouling coat
is applied.
Except at the plate stage and occasionally at the sub-unit stage, painting
is generally carried out in the open (often because of the size of substrate
involved) rather than in a contained space where a spray booth would be.
suitable.
~Information in this section 1s based on the industry status in 1975-77
time frame.
**The scope of coverage is for recreational vessels and for ships of over
1,000 gross tons. This would exclude vessels such as tugs, fishing
trawlers, ferries, and tenders although the discussion of surface-coating
operations would be applicable to all vessels.
4-lb4
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A ship's coating system consists of several layers of primer, inter-
mediate coat, topcoat (or finish coat) and antifoul ant coat (exterior,
below water line). The selection of the materials for the various coats
is based partially on the solvent and resin compatibility of the adjacent
coats. The coatings industry supplies a variety of materials and formula-
tions to meet the technical and economic requirements of the shipbuilders
and ship owners.
Maintenance painting can range from spot painting to a complete
repainting job. Maintenance coating is generally an incidental task
while the ship is being dry-docked for mechanical repairs or inspection.
Recreational boats are generally built from fiberglass reinforced
polyester, aluminum or wood, with fiberglass-polyester the dominant
material of construction. The Boating Industry Association estimates that
production of wooden boats is negligible; aluminum is commonly used for
boats up to about 14 feet and might represent about 20 percent of the
total production; the remaining 80 percent of recreational boats are made
from fiberglass reinforced polyester.
Glass reinforced polyester boats are constructed by applying glass
cloth to preformed molds, saturating the glass with a catalyzed polyester
resin and allowing the composite glass reinforced polyester (GRP) to harden.
GRP boats receive a 15 mil polyester gel coat during the molding/fabrica-
tion process, to give a smoqth finish and color. The gel coat consists
of about 60 percent (volume) polyester resin and 40 percent styrene
monomer. During application, about half of the styrene is retained
during the curing process; the remainder evaporates.
Only a small fraction of the aluminum boats manufactured are coated.
Those coated might Include some of the bigger, premium quality boats. Many
aluminum rowboats, dinghies, canoes and other small aluminum boats manu-
factured are shipped unpainted. The surface coating of (the) aluminum
boats follow the three basic steps - surface preparation, priming and
finishing. The prepared surface is generally sprayed with a thin layer of
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of wash primer containing zinc chromate, phosphoric acid and polyvinyl
butyral. The VOC content in this wash primer is estimated to be 60 to 70
percent. The primer coat is followed by an alkyd finish coat containing
about 60 to 70 volume percent as applied. Acrylic base finish coats used
by some manufacturers have about the same solvent content. Topcoats are
applied in the 2 to 4 mil dry-film thickness range with conventional
air-spray or airless spray equipment.
C. Control Technology and Emission Reduction
For those portions of the shipcoatlng operation that occur outdoors,
economically acceptable use of abatement control technology seems remote at
this time. As a result, emission reductions must be sought by changes in the
solvent content of coatings and the efficiency with which the coatings
are applied. Formulation of low solvent coatings for ships and boats
may face problems not encountered by coatings for general metal products
because of the corrosive nature of the marine environment.
Merely changing from use of air-spray equipment to another type
will significantly reduce the paint wasted and accompanying air pollution.
These improvements could reduce waste by as much as 20 to 40 percent.
Emissions from those portions of a ship painted indoors (plates and
sub-units) can be controlled by abatement equipment. This has not been done to
date, perhaps partially because these emissions constitute a small portion of
the total from a ship building establishment.
Many of the coatings in present use are relatively high in VOC
content; wash primers, 92 to 94 percent; preconstruction primers, 70 to
85 percent; and shop primers 65 to 75 percent. Antifouling paints are
typically 70 percent solvent. Use of coatings with increased solids
content (decreased solvent : solids ratios) could dramatically reduce the
amount of VOC emitted to the atmosphere.
The only water-based coating in commercial use is the inorganic zinc
primers used on ships. Such coatings are widely accepted for performance,
however, during winter, their use is often practical only in warm regions
because of the threat of freezing in colder parts of the Nation.
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Based on the great strides in development of higher-solids coatings
for industries such as the auto, appliance and furniture industries,
coatings with solids contents of 35 to 4U volume percent for prime and 45
to 50 percent of topcoats is conceivable in the short term for most
marine requirements. This would represent an emission reduction of 95
percent for wash primers and about 40 percent for preconstruction and
shop primers.
E. Current National Emission Estimate
Information regarding sales of marine paints is not available from
published sources. Based on industry interviews with suppliers of coating
materials, it is estimated that roughly 50 to 100 tons of V0C might be
emitted daily from surface coating of ships and boats.
In the mid-70's, the California Air Resources Board (CARB) estimated
hydrocarbon emissions from marine-coating operations in California to be
about 10 tons/day. Based on this estimate, industry sources consider 50
to 100 tons/day reasonable for the whole country.
Over 90 percent of these emissions may be attributed to coating of
ships; the remaining emissions would result from coating of pleasure
boats.
F. Capital and Annualized Control Costs
The cost of surface coating a new ship may be as much as 10 percent of
the total cost of the ship. This, coupled with the high cost of repainting
or worse, the potentially higher cost of paint failure, makes selection of
coating system very critical.
Proper maintenance of antifouling coatings used under water on
ocean-going vessels also significantly affect fuel costs. Hull roughness
caused by corrosion will cause hydraulic turbulence or "drag" and increase
power requirements. The magnitude of the costs is so high that in conducti
an economic evaluation of a coating system, a life-cycle costing approach
should be taken rather than the one-time cost.
For example:
- Dry-docking charges may be as high as $100,000 per day.
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- Dry docks may not be available on short notice.
- A large tanker (VLCC) can consume more than $700,000 in extra fuel over
a 30-month period because of drag caused by fouling.
Because of the large fixed cost associated with coating of ships,
the cost of the coatings is near negligible. Consequently, a marine
facility could pay a several fold greater price for a low solvent coating
without significantly affecting the cost of the coating operation. On
the other hand, the cost of using a new coating that requires more frequent
repair can be huge.
G. References
1 Surface coatings in the Ships and Boats Industry, Booze, Allen and
Hamilton, Inc., September 29, 1978.
2 County Business Patterns, 1975.
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4.5.1.14 Plastic Parts for Business Machines
A. Process Description
Plastic parts for business machines are coated for several reasons.
Exterior coatings are applied to improve appearance, colormatch, and
provide chemical resistance. Metal-filled coatings are applied to interior
surfaces to provide electromagnetic interference/ radio frequency interference
(EMI/RFI) shielding. This limits both escape and intrusion of stray
electronic signa.ls, and in many cases is required by Federal Communications
Commission (FCC) regulations. Coatings are generally spray applied in
this industry, using air-atomized spray equipment. Many of the conventional
and lower VOC content coatings used in this industry are two-component
urethane coatings.*
B. Emission Sources and Factors
VOC emissions from plastic parts coating occur in the spray booth
flash-off area and bake oven. Up to 90 percent of all VOC emissions
come off in the spray booth. Annual VOC emissions from plastic parts
coating facilities range from 10 to 200 megagrams. Annual emissions depend
on the amount and VOC content of each coating used as described in Chapters 3
and 6 of Reference 1.
C. Control Techniques and Emission Reductions
Substitution of waterborne or higher-solids coatings for conventional
coatings can reduce VOC emissions from exterior coating and EMI/RFI
shielding by 60-80 percent. VOC emissions can also be reduced by improving
transfer efficiency by switching to air-assisted-airless or electrostatic
spray equipment. Since plastics are not-electrically conductive, a
conductive sensitizer must first be applied to the plastic when electrostatic
spray equipment will be used. There are also several EMI/RFI shielding
techniques (zinc-arc spray, electroless plating and conductive plastics)
which may produce no VOC emissions. Incineration could be used to reduce
emissions, but it has not been used in this industry because
of the high cost associated with controlling what are typically high volume,
low VOC concentration exhaust streams.*
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D. Regulatory Status
The EPA has not issued a CTU for plastic parts coatiny. The Bay
Area Air Quality Management District ir>> California has adopted a reyulation
which limits emissions from exterior coating operations to 3.b lb VOC/yallon
of coatiny less water after January 1, 1985, and 2.8 lb VOC/gallon of
coatiny less water after January 1, 1987.2
The EPA proposed a new source standard for surface coatiny of
plastic parts for business machines in January 198b (40 CFR 60 Subpart TTT).
This standard limits emissions from exterior coatiny to 1.5 kiloyrams of
VOC per liter of solids applied for prime coat, color coat and fog coat;-
and 2.3 kiloyrams of VOC per liter of solids applied for texture coat and
touch-up. These limits are a^poximately equal to 12.5 and 19.2 pounds of
of VOC per yallon of solids deposited respectively. No standard was proposed
for EMI/RFI shielding because the cost-effectiveness of" each of the
alternatives studied (hiyher solids solvent-borne nickel filled coatinys,
wateroorne nickel filled coatinys, and zinc-arc spray) was found to be
too hiyh compared to conventional nickel filled coatinys. As waterborne
nickel filled coatinys see yreater use, their cost should come down and
they may become a cost-effective option. Similarly, electroless platiny
and vacuum deposition of aluminum may also become cost-effective control
options in the future.
E. National Emission Estimate
Surface coating of plastic parts for business machines are estimated
to have resulted in about 5,400 meyayrams (6,000 tons) of VOC emissions
in 198b as described in Chapter 7 of Reference 1.
F. Capital ano Annual Control Costs
Some additional capital expenditure may be required before low-VOC
content coatinys can be used. For example, automatic proportioning
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equipment may be needed to mix the components of the nighest solids (60 volume
percent) two-component urethane exterior coatinys at the spray yun immediately
before sprayiny. The installed capital cost of this equipment is about
$3b00 per spray yun. On an annual basis, the productivity increases and
labor savinys associated with these coatinys far outweiyh the extra equipment
costs.
G. References
1. Surface Coatiny of Plastic Parts for Business Machines - Background
Information for Proposed Standards, EPA 4bU/3-8b-Ulya. U. S. Environmental
Protection Ayency, Research Triangle Park, North Carolina 27711. December
1985.
2. Bay Area Air Quality Management District, Regulation 8, Rule 31,
Surface Coatiny of Plastic Parts and Products, September 1983.
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4.5.1.15 Flexible Vinyl And Urethane
A. Process and Facility Description
Vinyl coating and printing refers to any printing or decorative or
protective topcoat applied over a vinyl-coated fabric or a continuous
vinyl sheet. Coating and printing of urethane substrates is essentially
the same process as the coating and printing of vinyl. The vinyl or
vinyl-coated fabric web is fed from a continuous roll through a series of
rotogravure printing and coating stations" (also see Section 4.5.2.1). A
typical coating and printing line will successively apply a precoat,
decorative print, and a wearcoat or topcoat. The precoat provides a
background color for subsequent printing. The printing step consists of a
series of print stations, each of which prints a different pattern or
color. The topcoat provides protection against scuffing and wear. After
each printing or coating station, the web travels through an oven where
heated air evaporates the volatile solvent. At the end of the line, the
finished product is rewound for shipment or further processing. There
are approximately 100 plants in the U.S. which coat and print on flexible
vinyl substrates.
B. Emission Sources and Factors*
The major source of VOC emissions from the line are the drying ovens.
It is estimated that up to 79 percent of the solvent which enters a
printing station is evaporated in the associated oven. The remaining 21
percent is emitted as fugitive vapors from the printing stations.
Other sources of fugitive emissions from a plant are the coating
preparation and storage areas and from use of solvent to wash equipment
and floors. The total VOC emissions from an average coating and printing
operation are estimated to be 620 megagrams per year, equivalent to an
emission factor of 0.075 kilograms of VOC per square meter of substrate
processed.
C. Control Techniques and Emission Reductions*
The emission reduction achievable through the use of abatement devices
is a function of the efficiencies of the vapor collection (or capture)
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system and the control device. The best capture systems demonstrated in
this and similar web-processing industries achieve 90 percent, or greater,
capture efficiencies.3 Abatement devices presently used are carbon
adsorbers, incinerators, and wet scrubbers. Carbon adsorbers have demon-
strated removal of 95 percent of the entering VOC. Similar efficiencies
habe been demonstrated by incinerators, although more than 99 percent of
the VOC entering an Incinerator can be destroyed; the actual value is
limited primarily by the operating temperature. The efficiency of VOC
removal by wet caustic scrubbers used by this industry has been reported
to be about 90 percent.
Significant reductions in VOC emissions may be possible in the near
future through use of coatings and inks that contain less VOC. Several
waterborne inks and topcoats are currently under development.
D. Regulatory Status
The EPA issued a control technique guideline (CTG) in 1977 which
recommended an emission limit of 0.45 kilograms of VOC per liter of coating
minus water which was based on an abatement system which achieves an 81
percent overall reduction of the VOC emitted by the vinyl surface coating
1ine.2
The EPA also issued a CTG in 1978 recommending add-on control technology
which would give a 65 percent overall VOC reduction for packaging rotogravure
printing.3 The rotogravure CTG also allows the use of waterborne inks,
the volatile fraction of which must contain 25 percent or less by volume
organic solvent and 75 percent or more of water to meet the specified
1evel of control.
The EPA set NSPS standards in 1984 (40 CFR 60 subpart FFF) which requires
an overall VOC emission reduction of 85 percent for new flexible vinyl
and urethane coating and printing operations. This limit may also be met
through the use of waterborne inks with an average VOC content of less
than 1.0 kilogram of VOC per kilogram of ink solids.
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E. Current National Emission Estimate*
It is estimated that the flexible vinyl and urethane coating and printing
industry emitted about 23,000 megagrams of VOC (controlled) in 1984, with
total potential (uncontrolled) emissions of about 64,000 megagrams of VOC.
F. Capital and Annual Control Costs*
The capital and annualized cost of controlling VOC from flexible
vinyl or urethane is primarily a function of the rate at which VOC is
generated by the printing press and in the ovens. This rate is affected
by line speed, the number of printing stations served by the control device,
coverage of the web, web width, and, the VOC content of the ink. Below
is a table of capital and annualized cost (May 1984) for control by carbon
adserptlon of several different "model" plants.
Number of
Production
Solvent Use
Capital
Annuali zed
Print Stations
m^/yrxlO^
Mq/yr
Cost S
Cost $
3
1.8
280
1,240,000
13,320,000
6
1.8
1,300
2,240,000
14,600,000
6
0.9
650
1,240,000
7,560,000
18
. 11.0
1,700
7,470,000
79,840,000
36
11.0
8,000
13,450,000
87,040,000
For more detailed information on capital and annualized cost, see reference 1.
G. References
1. Flexible Vinyl Coating and Printing Operations - Background
Information for Proposed Standards, EPA-450/3-81-016a, U. S. Environmental
Protection Agency, Research Triangle Park, N.C., January 1983.
2. Control of Volatile Organic Emissions from Existing Stationary
Sources - Volume II: Surface Coating of Cans, Coils, Paper, Fabrics, Auto-
mobiles and Light-Outy-Trucks, EPA-450/2-77-008, U. S. Environmental Protection
Agency, Research Triangle Park, N.C. May 1977.
3. Control of Volatile Organic Emissions from Existing Stationary
Sources - Volume VIII - Graphic Arts - Rotogravure and Flexography,
EPA-450/2-78-033, U. S. Environmental Protection Agency, Research Triangle
Park, N.C., December 1978.
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4.5.1.16 Architectural Coatings
A. Process and Facility Description
Architectural surface coatings (ASC) are defined as stock type or
shelf coatings which are formulated for decorative and/or protective
service for general application on new and existing residential, commercial,
institutional, and industrial structures. These are distributed through
wholesale-retail channels and purchased by the general public, painters,
building contractors, and others.1 ASC are applied in situ to a wide
variety of interior and exterior architectural surfaces. ASC air dry to
their final finish.
B. Emission Sources and Factors
VOC emissions from architectural surface coating result primarily from
the evaporation of organic solvents. The total potential emissions are
equal to the total organic solvent content of the coatings as applied
plus any solvent used for cleanup.
C. Control Techniques and Emission Reductions
The only feasible technique for reducing VOC emissions from ASC is
substitution of coatings that contain less organic solvent. Recent consumption
trends indicate waterborne coatings are replacing solvent-based ASC in
many cases.2 Currently, waterborne coatings constitute about 80 percent
of the interior ASC market and over 60 percent of the exterior ASC market.^
It has been estimated that the substitution of waterborne coatings only
in those cases where acceptable performance will be realized would still
result in an emission reduction of about 35 percent compared to actual
emissions (1975 data).4
D. Regulatory Status
VOC emissions from ASC are currently limited by only a few State
and local regulations, most notably in California.
E. Current National Emission Estimates
Current emissions from ASC are estimated at 360,000 megagrams per
year based on coating consumption in 1981.3
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F. Capital and Annual Control Costs^
The use of waterborne coatings which perform as well as traditional
solvent-borne coatings is not expected to increase coating costs per unit
area coated for the consumer.
G. References
1. Glossary for Air Pollution Control of Industrial Coating Operations,
Second Edition, EPA-450/3-83-013R, U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina, December 1983.
2. Nonindustrial Surface Coating, in: Compilation of Air Pollutant
Emission Factors, Third Edition, Supplement No. 12, AP-42, U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina, April 1981.
3. Information provided by the National Paint and Coatings Association,
Inc.
4. "Consideration of Model Organic Solvent Rule Applicable to
Architectural Coatings," June 1977, State of California Air Resources Board,
Sacramento, California.
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4.6.1.17 Auto Refinishing
A. Process and Facility Description1*2^
Most automobile refinishing is done in conjunction with body repair
work. Many times the entire vehicle is refinished. The refinishing
process begins with washing or steam cleaning of the automobile surface,
followed by sanding and a solvent wipe to remove contaminants. Primer
and color coats are manually applied, usually with air-atomized spray
guns. Refinishing paints may be acrylic lacquer, acrylic enamel, alkyd
enamel, or polyurethane enamel. Although the number of shops with spray
booths 1s increasing, most shops still do not have spray booths and do
their painting in the general work area.
The coatings are generally allowed to air dry. Some shops use
low-temperature bake ovens or portable heaters to speed up the drying
process.
There is a very large number of automobile refinishing shops nation-
wide, as indicated by an estimate of 2,000 of these sources in the
Philadelphia area alone.
B. Emission Sources and Factors1*2^
VOC emissions from automobile refinishing result from the evaporation
of organic solvent during the surface preparation and painting processes.
Lacquer coatings contain about 0.78 kg of VOC per liter (6.5 lbs of VOC
per gallon). Enamel coatings contain about 0.66-0.72 kg of VOC per liter
(5.5 - 6.0 lbs of VOC per gallon). Additional VOC emissions occur from
solvent wipe and clean-up operations.
C. Control Techniques and Emission Reductions
The most feasible approach to reduction of emissions from automobile
refinishing involves lower VOC content coatings. Enamels contain less
VOC than lacquers, but also dry slower. This is of concern because the
wet coating is susceptible to contamination with dirt or dust. Bake
ovens or portable heaters may be needed to speed the drying process and
minimize contamination. Some low VOC content waterborne primers are also
avai1able.
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Another way to reduce emissions is to improve transfer efficiency.
Some shops use modified airspray guns that use less atomizing air and
more shaping air to reduce bounce-back and overspray.^ Some shops in
Europe use hand-held electrostatic spray guns to reduce coating use and
emi ssions.
Emission reduction by means of add-on controls (incineration or
carbon adsorption) is technically feasible, but generally economically
prohibitive due to the intermittent nature of the process, the low
concentration of VOC in the spray booth exhaust stream and the fact that most
repair shops are very small, low capital, businesses. Perhaps some large
shops that paint many cars each day could afford some control equipment.
D. Regulatory Status
There are no regulations specifically for the control of VOC emissions
from automobile refinishing.
E. Current National Emission Estimates^ ,
The annual nationwide emissions of VOC from automobile refinishing are
estimated at 200,000 megagrams (220,000 tons), based on 1981 coating use.
F. Capital and Annual Control Costs
The capital and net annual costs of incineration control of automobile
refinishing emissions are estimated at $92,000 and $170,000, respectively
(in 2nd quarter 1984 dollars updated from 1982 dollars in reference 3).
6. References
1. A Dlscusson of Alternatives to Reduce Emissions of Volatile
Organic Compounds from the Automotive Refinishing Industry, California
Air Resources Board, Sacramento, California, draft, April 1982.
2. Surface Coating in the Automotive Refinishing Industry, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina,
December 1977.
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3. Volatile Organic Compound Emission Controls for the Automobile
Refinishing Industry, U.S. Environmental Protection Agency, Region III,
Philadelphia, Pennsylvania, May 1983.
4. Industrial Finishing, October 1985, page 17.
5. National Paint and Coatings Association.
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4.5.1.18 Other Surface Coating
There are a plethora of major coating operations for which detailed
investigations have not been conducted by the Agency. These include, but
are not limited to, large trucks ("18-wheelers"), their trailers, railroad
rolling stock, heavy off-road equipment (cranes, earth-moving equipment)
and farm machinery. These are now all considered under the general cate-
gory of "miscellaneous metal products." Close scrutiny of their coating
practices in light of the advances in technology since 1977 would likely
reveal new lower-solvent coating options that would support a move to
more stringent regulations for many industrial products. This is especially
• true of products that either use sufficiently high volumes of coatings to
warrant the cost of the requisite research by coating manufacturers or
are able to use coatings that have been developed for other large volume
users.
Appendix A and Table 2-5 provides the Agency's best estimate of
emissions from a variety of coating operations for which the Agency has
data. There are a number of smaller sources of VOC emissions from mis-
cellaneous coating operations for which the Agency does not have detailed
emission estimates. However, an overall estimate for other surface
coatings is given in Table 2-5 based on solvent usage data provided by
the National Paint and Coating Association.*
Reference
1. NPCA Data Bank Program 1982, by SRI International and Chemical
Marketing Services, Inc., prepared for the National Paint and Coatings
Association.
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4.5.2. Graphic Arts
The graphic arts or printing industry is characterized by both
a large number of small plants and a small number of large plants.
Historically, the bulk of commercial printing has been done in the large
metropolitan areas of the country.
Printing operations of any sizeable volume utilize presses in
which the image carrier is curved and mounted on a cylinder which rotates,
or the image is engraved or etched directly on the cylinder. This type
of arrangement is referred to as a rotary press. When the substrate to
be printed is fed to the rotary press from a continuous roll, it 1s
referred to as the "web."
In direct printing, the image is transferred directly from the .
image carrier to the substrate. In offset printing the image is transferred
first to an intermediate roll (blanket roll) and then to the substrate.
There are four basic printing processes in the graphic arts industry
which are potentially significant sources of VOC emissions: rotogravure,
flexography, lithography, and letterpress.
4.5.2.1 Rotogravure
A. Process Description
In the rotogravure printing process, image areas are recessed relative
to nonimage areas. The rotating cylinder picks up ink from an ink trough or
fountain. Excess ink is scraped from the blank area by a steel doctor
blade. The ink is then transferred directly as the roll contacts the web.
The web is then dried in a low temperature dryer. Typical ink solvents
include alcohols, aliphatic napthas, aromatic hydrocarbons, esters,
glycol ethers, ketones and nitroparaffins.l It is estimated that there
were approximately 1,600 rotogravure presses in the United States in 1984.2
B. Emission Sources and Factors
The major emission points from a rotogravure press are the ink foun-
tains, wet printing cylinders, wet printed web and drier exhaust. The
total amount of organic solvent consumed by the printing plant is the
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maximum potential VOC emission (if no reaction by-products are formed
during the drying operation). This consists of solvent in the raw ink,
solvent contained in any extenders used, solvent added at the press, and
solvent used for cleanup-*. Estimated emission factors for rotogravure
printing are 1.6 kilograms of VOC per kilogram of solvent base ink and 0.25
kilograms of VOC per kilogram of waterborne ink used at the press^.
C. Control Techniques and Emission Reductions
Emission reductions from rotogravure press operations can be achieved
by containing fugitive emissions from the print stations and directing
them to a carbon adsorber or incinerator. A reduction efficiency of 95
percent of the VOC delivered to either of these devices 1s reasonable.
Publication rotogravure plants with carbon adsorption systems have demonstrated
overall recovery efficiencies of 75 percent. Packaging rotogravure presses
can achieve an overall VOC recovery/control efficiency of 65 percent for
either adsorption or incineration systems.1 New publication rotogravure
presses with good capture or containment devices can achieve better than
84 percent overall control.3 For some printing operations, equivalent
emission reductions may be possible through use of waterborne and/or high
solids inks.
0. Regulatory Status
The EPA issued a guideline in 1978 which recommends a 65 percent overall
VOC emission reduction for packaging rotogravure operations and a 75
percent reduction for publication rotogravure when add on control technology
such as an incinerator or a carbon adsorber is used.* Use of waterborne
coatings 1) where 75 percent by volume of the volatile portion is water or
2) where higher solids coating contain 60 percent solids will also comply
with EPA guidelines. The EPA in 1982 set NSPS standards (40 CFR 60
Subpart QQ) which require an 84 percent emission reduction for publication
rotogravure plants which are constructed on or after October 28, 1980.3
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E. National Emission Estimates
It has been estimated that rotogravure package printing processes
emitted 87,000 megagrams of VOC in 1984.2 Solvent use for publication
rotogravure is about 150,000 Mg/yr. Since carbon adsorption is widely
used in the publication segment of the industry, only about 38,000 Mg
are actually emitted from publication rotogravure each year.
F. Capital and Annual Control Costs^
For a typical four-press publication rotogravure facility, the
capital cost for installing a carbon adsorber and associated solvent recovery
equipment is estimated to be about $1,674,000 while total annual operating
costs are estimated to return about $116,000 per year due to value of the
recovered solvent. Line sizes vary and control costs vary with line size.
Reference 3 gives a more complete discussion of costs.
G. References
1. Control of Volatile Organic Emissions from Existing Stationary
Sources - Volume VIII: Graphic Arts - Rotogravure and Flexography.
EPA-450/2-78-033, 0AQPS No. 1.1-109, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711, December 1978.
2. Memo from Howie, R., Radian, to Johnson, W., EPA: CPB.
July 20, 1984. Estimated Industry Emissions and Growth for the Paper,
Film, and Foil Converting Source Category.
3. Publication Rotogravure Printing - Background Information for
Proposed Standards - and Promulgated Standards, EPA-450/3-80-031a and b.
U. S. Environmental Protection Agency, Research Triangle Park,
North Carolina, October 1980 and October 1982.
4.5.2.2 Flexography
A. Process Description1
The image areas on the image cylinder of a flexographic press are
raised above the nonimage areas. A distinguishing feature is that the image
carrier is made of rubber which 1s attached to the cylinder. A feed
cylinder which rotates in an ink fountain delivers ink to a distribution
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roll, which 1n turn transfers ink to the image cylinder. Following
transfer from the image cylinder to substrate, the ink dries by evaporation
in a high velocity, low temperature (<120°F) air dryer. Some solvent is
absorbed into the web. Typical ink solvents are alcohols, glycols,
esters, hydrocarbons and ethers. An estimated 21,400 flexographic presses
were in operation in the United States in 1984.
B. Emission Sources and Factors
The major emission points from a flexographic press are the ink
fountains, feed cylinder, distribution roll, image cylinder, printed web
and dryer exhaust. The potential amount of VOC emissions is equal to
the total amount of solvent consumed by the printing plant if none of the
ink reacts to form an organic by-product. This includes the solvent in
the raw inks, solvent in any extenders used,, the solvent added at the
press, and clean-up solvent.1 Typical emission factors for flexographic
printing operations are 2.0 kilograms of VOC per kilogram of solvent-based
ink and 0.25 kilograms of VOC per kilogram of waterborne ink.
C. Control Techniques and Emission Reductions*
Emissions from flexographic printing operations can be reduced by
improvements in the equipment for containment of the emissions from the
print station and installation of an incineration system. Overall,
a capture efficiency of 65 to 70 percent and a combustion efficiency of
90 percent (for an overall reduction of 60 percent) appears reasonable.
Some flexographic packaging operations can now use waterborne inks.
Emission reductions equal to or better than those achieved by incineration
can be attained when the solvent portion of the ink consists of 75 volume
percent water and 25 volume percent organic solvent (solids to liquid
ratio remaining the same). Higher-solids inks with 60 percent solids are
becoming available.
D. Regulatory Status1
The EPA issued a control technique guideline (CT6) in 1978 which
recommends States adopt limitations for flexographic printing. When
add-on controls such as carbon adsorbers or incinerators are used, an
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overall 60 percent control efficiency is reasonable. Use of waterborne
inks whose volatile portion contains 75 volume percent water is an acceptable
control techniques as is the use of higher-solids inks which contain 60
percent or more solids.
E. National Emission Estimates
It has been estimated that the flexographic package printing industry emitted
67,000 megagrams of V0C in 1984.
F. Capital and Annual Control Costs
For a flexographic printing plant using 400 megagrams of ink per
year, the capital and total annualized costs of V0C control by thermal
incineration with 40 percent heat recovery are estimated to be about
$455,000 and $282,800, respectively. The costs vary widely wrth ink
usage. See reference 1 which discusses costs for a variety of situations.
G. References
1. Control of Volatile Organic Emissions from Existing Stationary
Sources—Volume VIII: Graphic Arts—Rotogravure and Flexography.
EPA-450/2-78-033, 0AQPS No. 1.2-109, U. S. Environmental Protection Agency.
Research Triangle Park, North Carolina 27711. December 1978.
4.5.2.3 Lithography
A. Process and Facility Description
Lithography is a printing process characterized by a planographic
image carrier (i.e., the image and nonimage areas are on the same plane)
which is mounted on a plate cylinder. The image area is made water
repellent while the nonimage area is water receptive. Rotation of the plate
cylinder causes the image plate to first contact an aqueous fountain
solution which typically contains up to 25 weight percent isopropyl
alcohol. This solution wets only the nonimage area of the plate. The image
plate then contacts the ink which adhered only to the image area. In
offset lithographic printing, the ink is transferred from the image plate
to a rubber-covered blanket cylinder. The blanket cylinder then transfers
the image to the web. Lithographic heatset inks, containing approximately
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40 volume percent solvent, require a heated dryer to solidify the printed
ink. Other lithographic inks, containing about 5 volume percent solvent,
dry by oxidation or by absorption into the substrate.
There are approximately 400 printing plants in the United States
operating over 1000 heatset web offset lithographic printing presses.
B. Emission Sources and Factors
Emission points on a web-offset lithographic printing line include
the ink fountains and associated inking rollers, the water fountains and
associated dampening rollers, the plate and blanket cylinders, the dryer,
and the final printed product. Alcohol is emitted from the dampening
system and the plate and'blanket cylinders at a rate of about 0.5 kilograms
per kilogram of ink consumed.1 Wash-up solvents are" a small source of
emissions from the inking system and the plate and blanket cylinders. When
heat-set inks are printed, the drying oven is the major source of VOC
emissions with 40 to 60 percent of the ink solvent evaporating from the oven.2
C. Control Techniques and Emission Reductions*
Two approaches for controlling VOC emissions from heat-set web offset
lithographic printing presses are 1) material reformulation and 2) add-on
control. Substitution of polyols, such as ethylene glycol, for the
alcohol in the aqueous fountain solution can result in a reduction of VOC
emissions from fountain solutions. Ink reformulation to reduce the
solvent content will reduce VOC emissions from the dryer somewhat.
The two major add-on control systems that have been used successfully
on lithographic printing presses are cooler/electrostatic precipitators
(cooler/ESP) and incinerators. A cooler/ESP system has demonstrated an
overall VOC control efficiency of about 80 percent when applied to heat-set
web offset lithographic printing dryer exhausts. Thermal (direct flame)
or catalytic Incineration can effectively reduce dryer exhaust VOC emissions
by 90 percent.
D. Regulatory Status
VOC emissions from lithographic printing are currently not
limited by Federal regulations.
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E. Current National Emission Estimate
Total annual emissions from all heatset web offset printing is about
70,000 megagrams per year.* This includes VOC emissions from lithographic
package printing which have been estimated to be about 6,500 megagrams.
F. Capital and Annual Control Costs*
Total installed capital costs for a catalytic incinerator with primary
heat exchange is estimated at $134,000 for a printing press equipped with
a high-velocity hot air dryer. The total annualized cost of this system,
based on 2,000 hours per year operation, is estimated to be $42,000. Of
course, these control costs will vary with line size. Reference 1 gives
costs for a variety of line sizes.
G. References
1. Control of Volatile Organic Compound Emissions from Full-Web
Process-Color Heatset Web Offset Lithographic Printing (Draft),
U.S. Environmental Protection Agency, Research Triangle Park, North Carolina,
August 1981.
2. Graphic Arts. In: Compilation of Air Pollutant Emission Factors,
Third Edition, Supplement No.12, AP-42, U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina, April 1981.
3. Memo from Howie, R., Radian to Johnson, W., EPA. Estimated
Industry Emissions and Growth for the Paper, Film, and Foil Converting
Source Category. July 20, 1984.
4.5.2.4 Letterpress
A. Process and Facility Description1»2
Letterpress is the oldest form of moveable type printing, with the
image areas raised relative to the blank or nonimage areas. The image
carrier may be made of metal or plastic. Viscous ink is applied to the
image carrier and transferred directly to paper or other substrate.
Letterpress is the dominate printing process for periodical and
newspaper publishing. Newspaper ink is composed of petroleum oils and
carbon black, but no volatile solvent. The ink "dries" by adsorption
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into the substrate. Web presses printing on nonporous substrates employ
solvent-borne inks which dry by evaporation. Sheet-fed presses employ
solventless inks which dry by air oxidation.
There are over 10,000 commercial letterpress printing plants in the
United States.-*
B. Emission Sources and Factors*
The major VOC emission points on web letterpress printing lines are
the image carrier and inking mechanism of the press, the dryer, the chill
rolls and the printed product. About 60 percent of the solvent in the
ink is lost in the drying process. Use of washup solvents contribute to
overall VOC emissions.
C. Control Techniques and Emission Reductions?
Incinerators installed on print dryers have been reported to reduce
overall VOC emissions by 90 percent. Use of ultraviolet curing inks
in place of solvent-borne inks can essentially eliminate emissions. Use
of heat reactive inks which contain only 15 percent of the organic solvent
content of conventional inks will reduce overall emissions by 80 percent.
A similar reduction is achievable with waterborne inks.
0. Regulatory Status
No Federal guidance has been published for limiting VOC emissions
from letterpress printing operations. As a result, few, if any, States
regulate letterpress operations.
E. Current National Emission Estimate
The total national use of VOC on web letterpress operations is
estimated to be about 43,000 megagrams per year. All of this VOC may not
be emitted since part of it may be adsorbed into the substrate on which
the printing occurs.
F. Capital and Annual Control Costs
The installed cost of incinerators without heat recovery range
from $148,000 to $480,000, while annual costs range from $148,000
to $1,480,000, depending on the plant size.2 Use of heat recovery
would increase capital costs, but lessen fuel usage. See reference 2
for a more detailed cost analysis.
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G. References
1. Graphic Arts. In: Compilation of Air Pollutant Emission
Factors, Third Edition, Supplement No. 12, AP-42, U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina, April 1981.
2. Graphic Arts, Web Letterpress Printing Operations. In: Air
Pollution Control Technology Applicable to 26 Sources of Volatile Organic
Compounds, U. S. Environmental Protection Agency, Research Triangle Park,
North Carolina, May 1977.
3. Census of Manufacturers, 1982. Bureau of Census, U. S. Department
of Commerce.
4.5.2.5 Flexible Packaging
A. Processes and Facility Description
The flexible packaging industry prints, coats, and laminates bread
wrappers, frozen food cartons, cigarette packages, pharmaceutical packages,
and many other packages.*»2 Printing is done mainly by rotogravure or
flexography. [The emission sources in this industry are the same as
discussed in sections 4.5.2.1 and 4.5.2.2 on rotogravure and flexographic
printing since flexible packaging is a subcategory of rotogravure and
flexographic printing. These processes are discussed again below, since
flexible packaging is frequently considered a distinct industry.] Lamination
is often used to build multilayer composites of paper, plastic film and
foil. Sometimes coating is done on the last print station of a print
line to give a. clear protective topcoat to the film. Occasionally coating
lines are operated separately from printing lines.
B. Emission Sources and Factors
Flexographic ink is purchased in a concentrated form and cut before
use to acceptable press viscosity by adding solvent. As the ink sits
in the ink pan on the print line, solvent continually evaporates and more
solvent must periodically be added to keep the ink within an acceptable
viscosity range. For an ink purchasd at 50 percent solids, the solvent
entering the press would typically be from these sources:
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1. VOC in purchased ink 25%
2. VOC added to reduce ink to printing 30%
viscosity (initial cut)
3. VOC added on line to maintain 45%
acceptable printing viscosity
(make-up)
TOTAL 100%
The make-up solvent will evaporate from the ink pans and coating
rolls as fugitive emissions. Most of the other 50 percent will evaporate
either in the drying ovens associated with the print stations or from the
final dryer. A typical flexographic converter will emit 2.0 kilograms of
solvent for each kilogram of ink purchased. Emissions from rotogravure
printing are also approximately 1.6 Kg VOC/Kg ink purchased. Average annual
emissions per press from a package printing press and coater are:
Average Uncontrolled Reported Range of
Process Emissions3 (Kg/yr) Emissions (Kg/yr)
(per press)
Flexographic Press 37,400 4.5 - 280,813
Rotogravure Press 77,000 7.7 - 324,327
Top Coater 150,000 81 - 1,070,391
Adhesive Coater 59,000 120 - 287,347
Primer Coater 52,000 1563 - • 213,600
C. Control Techniques and Emission Reductions
Add-on controls such as carbon adsorption, incineration, or catalytic
incineration can be used on the dryer exhausts. Because fugitive emissions
on many printing lines may constitute 50% of all the solvent used, steps
must be taken to reduce fugitive emissions from the ink trays and print
rolls. This may be done by enclosing these areas, using doctor blades to
replace some of the ink transfer rolls, using solvents which evaporate
more slowly, or designing new lines so that more of the fugitive emissions
are drawn into the dryers.
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Waterborne inks have been developed for porous substrates such as
paper, and some non-porous plastic substrates. Progress has een reported
recently with using waterborne inks to print on certain plastic films
with very slick surfaces such as high slip polyethylene. High solid inks
with 60 volume percent solids have been developed in white which 1s the
"color" of highest volume usage. A number of low solvent adhesives and
coatings are available for laminating and topcoating operations.
D. Regulatory Status
The EPA issued a CTG in May 1977 which recommended that coating
operations emit no more than 2.9 lb. VOC per gallon of coating (less
water)This is about an 81 percent reduction compared to the VOC
content of conventional coatings. This paper coating CtG applied to many
coating and laminating operations in the flexible packaging industry.
In December 1978, EPA issued a CTG for rotogravure and flexography
operations.5 This document recommended that add-on controls could be
used to reduce overall VOC emissions from packaging rotogravure lines by
65 percent and from flexography lines by 60 percent. Also allowed as
acceptable control techniques are a waterborne coating where 75 percent
of the volatile portion is water or a high solids coatings with 60 percent
solids.
E. National Emission Estimates^»7»8
Estimated 1984 solvent emissions (Mg/year) are:
0
Flexographic Package Printing 67,000
Rotogravure Package Printing 87,000
Flexible Package Coating 50,000
TOTAL 204,000 Mg/year
These flexographic and rotogravure printing estimates are included
in the emission estimates made in Sections 4.5.2.1 and 4.5.2.2 for all
products printed by rotogravure and flexography.
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F. Capital and Annual Control Costs**
A flexible package printing line using 40 Mg of VOC per year could
be controlled by a thermal incinerator with a capital cost of $132,000
and an annualized operating cost (including capital charges) of $40,500.
Of course, control costs vary with line size. See Reference 5 for more
detailed discussion of costs.
G. References
1. Strauss, Victor, The Printing Industry, Printing Industries of
America, Inc., Washington, D.C., 1967.
2. Flexography Principles and Practice, Third Edition, Flexographic
Technical Association, Inc., 1980.
3. Boies, D. et al (WAP0RA, Inc.), Assessment of Organic Emissions
in the Flexible Packaging Industry. (Prepared for Industrial Environmental
Research Laboratory), Cincinnati, Ohio, Publication No. EPA-600/2-81-009,
January 1981, pp. 50-72.
4. Control of Volatile Organic Emissions from Existing Stationary
Sources - Volume II: Surface Coating of Cans, Coils, Paper, Fabrics,
Automobiles and Light-Duty Trucks," U.S. Environmental Protection Agency,
EPA-450/2-77-008, May 1977.
5. Control of Volatile Organic Emissions from Stationary Sources -
Volume VIII: Graphic Arts - Rotogravure and Flexography," U.S. Environmental
Protection Agency, EPA-450/2-78-033, December 1978.
6. 1982 Census of Manufacturers, Preliminary Report, Industrial
Series SIC 2893, U.S. Department of Commerce, Washington, D.C., 1982, p. 4.
7. "Organic Solvent Use in Web Coating Operations," U.S. Environmental
Protection Agency, EPA-450/3-81-012, September, 1981.
8. Memoramdum from Howie, R., Radian, to Johnson, W., U.S. EPA/ESED/CPB,
July 20, 1984. Estimated Industry Emissions and Growth for the Paper,
Film, and Foil Coating Source Category.
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4.5.3 Adhesives
A. Process and Facility Description*,2
Adhesives are used for joining surfaces in assembly and construction
of a large variety of products. Adhesives allow faster assembly speeds,
less labor input, and more ability for joining dissimilar materials than
other fastening methods. By far the largest use of adhesives is for the
manufacture of pressure sensitive tapes and labels. Other large industrial
users are automobile manufacturing (including especially attachment of
vinyl roofs) packaging laminating, and construction of shoes. Adhesives
may be waterborne, organic solvent-borne, or hot-melt. Only organic
solvent-borne adhesives have the potential for significant VOC emissions.
Approximately 75 percent or more of all rubber-based adhesives are
organic solvent-borne cements. Methods of application commonly used are
brush application, spraying, dipping, felt pad application, and roller
coating. Solvents used in solvent-borne adhesives include aliphatic and
aromatic hydrocarbons, alcohols, and ketones.
B. Emission Sources and Factors^
The VOC emissions from solvent-based adhesives are a result of the
evaporation of the solvents in the adhesive. Emissions arise mainly at
the point of application and in many cases are swept from the area with
local ventilation systems. Essentially all of the organic solvent in an
adhesive is emitted to the atmosphere as the adhesive dries. Adhesives
vary widely in composition but a typical solvent-borne adhesive might
contain 80 weight percent sol vent.so that approximately 0.8 kg of VOC
evaporates for every kg of adhesive used.
C. Control Techniques and Emission Reductions
The trend in control technology for solvent adhesives is not to
control emissions from a solvent-borne adhesive, but rather to replace
them with a low solvent type which can perform as well as the solvent-borne
adhesive. Various types of low solvent adhesive include waterborne,
hot-melt, solventless two-component, and radiation-cured. VOC reductions
of 80 to 99 percent can be achieved by such replacement.*
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Hot-melt adhesives are the most widely used of these alternative
processes. Use of waterborne adhesives is expected to increase significantly
in the future.2
D. Regulatory Status
The EPA has provided regulatory guidance only for the pressure
sensitive tapes and labels industry; consequently, emissions from other
adhesive applications are limited only by individual State and local
emission control regulations if there are any. The EPA set NSPS standards
only for the pressure sensitive tapes and labels industry. Emissions
from that industry are discussed in more detail 1n Section 4.5.1.6.1.
E. Current National Emission Estimate
Annual VOC emissions from adhesive applications, excluding the pressure
sensitive tapes and labels industry, are estimated at approximately 305,000
megagrams. Below are listed the largest uses of adhesives:
Application Sector Estimated Solvent Emissions (1,000 Mg/yr)
1. Pressure Sensitive Tapes & Labels 263
2. Miscellaneous Household & Industrial 67
3. Rubber Products 21
4. Auto Assembly (excluding tires) 19
5. Packaging Laminates 18
6. Construction (excluding floor tile and 14
wall covering)
7. Converted Paper Products 14
8. Floor Tile and Wall Covering 11
9. Footwear 7
F. Capital and Annual Control Costs*
Low-solvent adhesives may be lower or higher in cost, depending on the
product. In any case, the adhesive is only a small component of the cost
of the manufactured product and its price does not substantially affect
the cost of the consumer product.
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G. References:
1. Adhesives. In: Air Pollution Control Technology Applicable to
26 Sources of Volatile Organic Compounds. U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, May 27, 1977.
2. Adhesives Application. In: Summary of Technical Information
for Selected Volatile Organic Compound Source Categories, EPA-450/3-81-007,
U.S. Environmental Protection Agency, Research Triangle Park, North Carolina,
May 1981.
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4.6 OTHER SOLVENT USE
4.6.1 Solvent Metal Cleaning
A. Process and Facility Description
Solvent metal cleaning (degreasing) uses organic solvents to remove
soluble impurities from metal surfaces. Organic solvents include petroleum
distillates, chlorinated hydrocarbons, ketones, and alcohols. Industries
frequently using solvent metal cleaning include automobiles, electronics,
appliances, furniture, jewelry, plumbing, aircraft, refrigeration, business
machinery, and fasteners.
Methods of solvent metal cleaning include cold cleaning, open top vapor
degreasing, and conveyorized degreasing. Cold cleaning uses all types of
solvents with the solvent maintained below its boiling point. Open top
vapor degreasers use halogenated solvents heated to. their boiling points.
Both cold cleaners and open top vapor degreasers are batch operations.
Converyorized degreasers are loaded continuously and may operate as vapor
degreasers or as cold cleaners.
B. Emission Sources and Factors
For cold cleaners, emission sources are as follows: (1) bath evaporation,
(2) solvent carry-out, (3) agitation, (4) waste solvent evaporation, and (5)
spray evaporation. Emission rates vary widely with the average emission rate
estimated to be about 0.3 megagrams (.33 tons) per year per unit.2
Unlike cold cleaners, open top vapor degreasers lose a relatively small
proportion of their solvent in the waste material and as liquid carry-out.
Most of the emissions are vapors that diffuse out of the degreaser into the
work place. These fugitive emissions escape to the atmosphere through doors,
windows, and exhausts. An average open top vapor degreaser with an open top
area of 1.67m2 (18 ft^) has an emission rate of 4.2 kilograms (9.3 pounds)
per hour or 9,500 kilograms (21,000 pounds) per year.3
Emission sources for converyorized degreasers include bath evaporation,
carry-out emissions, exhaust emissions, and waste solvent emissions. Carry-
out emissions are the largest single source. An average emission rate for a
converyorized degreaser is about 25 megagrams (28 tons) per year while that for
a nonboiling converyorized degreaser is almost 50 megagrams (55 tons) per year.
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C. Control Techniques and Emission Reductions
Controls to reduce emissions from the solvent bath include the following:
(1) improved cover, (2) high freeboard, (3) chilled water and refrigerated
chillers, (4) carbon adsorption, and (5) safety switches. Carry-out emissions
from cold cleaners can be reduced by using drainage racks and by controlling
the velocity at which parts are introduced and withdrawn. Carry-out emissions
from conveyorized degreasers are reduced by using a drying tunnel and rotating
baskets.
Emission reductions are dependent upon both control devices and operating
techniques. For example, by recycling waste solvent, closing the cover, and
draining cleaned parts, emissions from a cold cleaning system can be reduced
50 percent. For an open top degreaser, imnplementing 10 main operating
practices and installing a cover, safety switches and a major control device
(high freeboard, refrigerated chiller, enclosed design, or carbon adsorption)
may reduce emissions by 60 percent. For conveyorized degreasers combining
five operating procedures, a control device (carbon adsorption or refrigerated
chiller), a drying tunnel, safety switches, minimized openings, and down-time
covers may reduce emissions by 60 percent.
D. Regulatory Status
A CTG was issued in November 1977. An NSPS was proposed in June, 1980.
Both the NSPS and the CTG recommend regulations based on equipment specifications
and operating requirements. Control equipment includes covers, drainage racks,
specified freeboard ratios, safety switches, refrigerated freeboard devices,
carbon adsorption systems, and drying tunnels. Requirements vary depending
upon size and type of degreaser.
E. National Emission Estimates
The V0C emissions from organic solvent cleaners have been estimated at
920,000 megagrams (1 million tons) per year in 1984 (see Table 4.6.1-1). Emis-
sions estimates are based on solvent consumption and test data. Appendices
A and B in Reference 1 present the emissions information.
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Table 4.6.1-1 1984 Emissions from Solvent Metal Cleaning3
Emissions
Mq/Year
Tons/Year
340,000
350,000
120,000
60,000
70,000
430,000
90,000
60,000
370,000
390,000
130,000
70,000
80,000
470,000
100,000
70,000
1,520,000
1,680,000
920,000
1,010,000
Solvent Used
Halogenated
Trichloroethylene
1,1,1-T ri chl oroethane*5
Perchloroethyl eneb
Methylene Chloride*5
Tri chlorotri fluoroethane^
Aliphatic
Aromati c
Oxygenated
TOTAL EMISSIONS
TOTAL VOC EMISSIONS
a Projected from 1974 Consumption Figures.®
b Non-VOC (See Section 2.1 of Chapter 2.)
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F. Current Captial and Annual Control Costs
For a large size model cold cleaner with 1.2m2 (13 ft^) working area,
capital cost of controls for a cover and a drainage rack is $150 (in 1984 dollars).
Total annualized costs with solvent recovery are a credit of $340.
For a typical open top vapor degreaser with 1.86m2 (20 ft^) working area
and controlling with a cover and a refrigerated freeboard device, capital
cost is $9,600 (in 1984 dollars). Total annualized costs with solvent recovery
are a credit of $1,000.
For a conveyorized vapor degreaser with 4.65m^ (50 ft^) working area and
using a refrigerated freeboard device, capital control cost is $17,100 (in
1984 dollars). Total annualized costs are a credit of $3,700.7
Costs are based on vendor quotations.
G. References
1. U.S. Environmental Protection Agency. Control of Volatile Organic
Emissions for Solvent Metal Cleaning - 0AQPS Guidelines. Research Triangle
Park, North Carolina. Publication No. EPA-450/2-77-022. November, 1977.
2. Reference 1.
3. Reference 1.
4. Reference 1.
5. U.S. Environmental Protection Agency. Organic Solvent Cleaners -
Background Information for Proposed Standards. Research Triangle Park,
North Carolina. Publication No. EPA-450/2-78-045a. October, 1979.
6. Reference 5.
7. Reference 5.
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4.6.2 PETROLEUM DRY CLEANING
A. Process and Facility Description
Dry cleaning 1s a service industry, involved in the cleaning of apparel
or renting apparel. Basically, the industry is segregated into three areas
based on customers and types of services offered. These areas are: (1)
coin-operated, (2) commercial, and (3) industrial. The industry is also
subdivided according to the type of solvent used, they are: petroleum solvents,
perchloroethylene (perc), and trichlorotrifluorethane (Freon-113, a registered
trade mark). Freon-113 and perc will not be discussed further since they are
considered negligibly reactive (See Section 2.1 of Chapter 2 for further
discussion ). Dry cleaning operations are similar to detergent and water
wash operations. However, dry cleaners reclaim solvent used in washers and
in many plants—from the article dryers. Soiled-solvent is cleaned by use of
either filters, stills, settling tanks or combinations of these. There are
approximately 6,000 facilities in the U. S. with petroleum dry cleaning
equi pment.l
B. Emission Sources and Factors
VOC's are emitted from dryers, washers, solvent filtration systems,
settling tanks, stills, and piping and ductwork associated with the installation
and operation of these devices. Because of the large number of variations in
the types of equipment and operating practices, in dry cleaning plants there
is a large variation in emission rates. For that reason, details on emission
o
factors or typical plant emission rates will not be discussed here, but are
discussed and documented in the references used in this section. The emission
sources in dry cleaning plants can be characterized in two broad groups -
vented and fugitive emissions. Solvent is vented from article dryers, solvent
stills, and filter and article drying cabinets. The largest source of vented
emissions is from article dryers. Fugitive emissions occur from all equipment
in dry cleaning facilities, however, these emissions vary greatly since they
are dependent on equipment operating and good housekeeping practices. The
major fugitive emission sources are solvent or liquid leaks from pipes or
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ductwork, and wet or not completely dried articles, used-wet filters, and
solvent and still waste which are all left in open containers in or outside
dry cleaning facilities.
C. Control Techniques and Emission Reductions
New petroleum article dryers using water cooled condensers have only
recently been available and have been demonstrated to achieve emission reduc-
tions of approximately 80 percent (or reduced outlet emissions to 3.5 kilograms
per 100 kilograms of articles cleaned).! Fugitive emission sources are controlled
by improved operating and maintenance practices.
D. Regulatory Status
The EPA issued a CTG in 1982 and set NSPS standards in 1984 (40 CFR 60
Subpart JJJ) for dry cleaners using petroleum based solvents.1*2 The CTG
p
recommends that for facilities using 123,000 liters (about 32,500 gallons)
of solvent per year or more: (1) limit dryer emissions to 3.5 kg petroleum
solvent per 100 kg of articles cleaned or install and properly operate a
petroleum recovery dryer (a dryer with a water cooled condser), (2) reduce
the V0C content in filter wastes to 1.0 kg or less per 100 kg of articles
cleaned, or use cartridge filters and drain them in their sealed housings for
8 hours or more before their removal, and (3) repair all leaks within 3
working days. The NSPS requires for all new, modified, or reconstructed
equipment in a petroleum dry cleaning facility with more than 38 kg (about 84
pounds) dryer -capacity to (1) install recovery dryers when installing new
dryers and perform an initial test to verify proper operation of recovery
dryers installed, (2) install cartridge filters when installing any filter
system, and drain the filter in their sealed housing for 8 hours prior to
removal, and (3) place a label on new dryers informing operators to preform
periodic inspections for leaks and repair of leaks.
E. National Emission Estimates?
Annual V0C emissions from dry cleaning facilities using petroleum solvent
is estimated to be 83,000 megagrams (91,000 tons). This estimate does not
include the reductions from either the CTG or the NSPS.
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F. Capital and Annual Control2
For a typical plant cleaning 82,000 kg (about 180,000 pounds) of articles
per year with petroleum solvent the difference in capital costs for installing
a recovery dryer (with a refrigerated water chiller) instead of a normal
(non-recovery) dryer is estimated to be $21,400. The difference in annual
operating costs and capital charges is estimated to be $2,950. A net savings
of $2,350 for solvent recovery would be realized; this reducing the annual
costs to $600.
6. References
1. Guideline Series: Control of Volatile Organic Compound Emissions
from Large Petroleum Dry Cleaners, U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina, EPA-450/3-82-009, September 1982.
2. Petroleum Dry Cleaners - Background Information for Proposed Standards—
and Promulgated Standards, EPA-450/3-82-012a and b, November 1982 and September
1984.
4-192
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4.6.3. Cutback Asphalt
A. Process and Facility Description
Liquefied asphalts are generally prepared by cutting back or blending
asphalt cement with petroleum distillate or by emulsifying asphalt cement
with water and an emulsifying agent. Heated asphalt cement is generally
used to make asphalt pavements such as asphalt concrete. Cutback and
emulsified asphalt are used in nearly all paving applications. In most
applications cutback and emulsified asphalt are sprayed directly on the
road surface; the principal other mode is in cold mix applications normally
used for winter time patching.
B. Emission Sources and Factors
Emissions from cutback asphalt occur as the petroleum distillate
9
(diluent) evaporates; the average diluent content in the cutback is
35 percent by volume. The percentage of diluent to evaporate 1s depen-
dent on the cure type. The emission factors are: Slow cure (SC) - 20 to
30 percent of diluent content, average 25 percent; Medium cure (MC) - 60
to 80 percent, average 70 percent; Rapid cure (RC) - 70 to 90 percent,
average 80 percent. These factors are independent of the percent of
diluent in the mix within the normal range of diluent usage for cutback
asphalts.1
C. Control Techniques and Emission Reductions
The technology to control hydrocarbon emissions from these paving
operations consists of substituting emulsified asphalts in place of
cutback asphalts. Emulsified asphalts use water and non-volatile
emulsifying agents for liquefaction; virtually no pollutants are emitted
during the curing of emulsions. Emulsified asphalts are used widely in
the construction and maintenance of pavements ranging from high traffic
volume highways and airports to low-volume rural roads and city streets.
4-193
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D. Regulatory Status
The EPA issued a CTG in 1977 to control emissions from the use of
cutback asphalt.2 The CTG recommends the substitution of an emulsified
asphalt for cutback asphalt. The use of cutback asphalt has decreasd
41 percent from 3.7 million metric tons (4.1 million tons) in 1977^ to
1.1 million metric tons (1.2 million tons) in 1983^.
E. National Emission Estimates
National emissions in 1983 are estimated at 195,000 metric tons
(214,000 tons) of V0C from the use of 1.1 million metric tons (1.2 million
tons) of cutback asphalt. This estimate is based on a weighted average
of the diluent in and diluent that evaporates from slow, medium, and
rapid cure cutback asphalt, i.e., approximately 17.5 percent (by weight)
p
of the cutback asphalt evaporates to the atmosphere^.
F. Capital and Annual Control Costs
A cost comparison of asphalt cutbacks with emulsions is best stated
in terms of price per gallon for the total asphalt mix. A review of the
December 1984 price quotations shows that emulsified asphalts were cheaper
than cutback asphalts®. Therefore, the replacement of cutbacks with
emulsions will generally result in a savings.
G. References
1. Guideline Series: Control of Volatile Organic Compounds from
Use of Cutback Asphalt, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, EPA-450/2-77-037, December 1977. p.2.3.
2. Ibid.
3. Ibid. p.3.2.
4. Asphalt Usage 1983 United States and Canada, the Asphalt
Institute, June 1984, p.4.
5. Guideline Series: Control of Volatile Organic Compounds from
Use of Cutback Asphalt, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, EPA-450/2-77-037, December 1977. p.4-1.
6. Engineering News Record, A McGraw-Hill weekly publication,
December 6, 1984.
4-194
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4.7 OTHER MISCELLANEOUS SOURCES
4.7.1 Stationary Fuel Combustion
Stationary fuel combustion sources may utilize external or internal
combustion. External combustion sources include boilers for steam generation,
heaters for the heating of process streams, and driers and kilns for the
curing of products. Internal combustion sources include gas turbines and
reciprocating internal combustion engines.
4.7.1.1 Stationary External Combustion Sources
A. Process and Facility Description
External combustion sources are categorized according to the type of
fuel burned in the unit. Coal, fuel oil, and natural gas are the primary
fuels used in stationary external combustion units. LP6, wood and other
cellulose materials are also used to a lesser degree in external combustion
sources. The largest market for liquified petroleum gas, LP6, is the domestic-
commercial market, followed by the chemical industry and the internal combustion
engi ne.
Bituminous coal is the most abundant fossil fuel in the United States.
Capacities of coal-fired furnaces range from 4.5 Kg (10 lb) to 360 Mg (400
tons) of coal per hour.
Anthracite coal is used in some industrial and institutional boilers and
also in hand-fired furnaces. It has a low volatile content and a relatively
high ignition temperature.
Lignite is a geologically young coal with properties that are intemediate
to those of bituminous coal and peat. Lignite has a high moisture content of
35 to 40 percent by weight, and the heating value of 1.5 to 1.8 J/Kg (6000-
7500) Btu/lb) is low on a wet basis. It is generally burned in the vicinity
of where it is mined. Although a small amount is used in industrial and
domestic applications, it is mainly used for steam production in electric
power plants.
4-195
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The two major types of fuel oil are residual and distillate. Distillate
oil is primarily a domestic fuel, but it is used in commercial and industrial
applications where high-quality oil is required. Residual oils are produced
from the residue remaining after the lighter fractions (gasoline, kerosene
and distillate oils) have been removed from the crude oil. More viscous and
less volatile than distillate oil, residual oils must be heated for easier
handling and for proper combustion. Residual oils also have higher ash and
sulfur contents.
Natural gas is used mainly for industrial process steam and heat production
and for space heating. It consists primarily of methane with varying amounts
of ethane and smaller amounts of naitrogen, helium, and carbon dioxide.
The major oil price increases and embargos of the 1970's forced companies
to consider wood as an energy source for industrial heat or power generation.
High transportation costs result in localized markets. Prime candidates for
wood combustion are companies which generate considerable quantities of
wood/bark wastes. Residential wood combustion has increased dramatically
during the past decade.
Liquified petroleum gas consists mainly of butane, propane, or a mixture
of the two, and trace amounts of propylene and butylene. It is sold as a
liquid in metal cylinders under pressure and also form tank truck and tank
cars. The heating value ranges from 26.3 KJ/m^ (97,400 Btu/gal) to 24.5 KJ/m^
(90,000 Btu/gal).
B. Emission Sources and Factors
Volatile organic emissins from stationary external combustion sources
are dependent on type and size of equipment, method of firing, maintenance
practices, and on the grade and composition of the fuel. Considerable
variation 1n organic emissions can occur, depending on the efficiency of
operation of the individual unit. Incomplete combustion leads to more
emissions. Emission factors are given in Table 4.7.1-1.
4-196
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Table 4.7.1-1 Emission Factors for Stationary External Combustion Sources
Coal - All types
Nonmethane VOC
lb/ton
Kg/Mg
Rating
Methane VOC
lb/ton
Kg/Mg
Rating
Wood
Nonmethane VOC
lb/ton
Kg/Mg
Rating
Methane VOC
1 b/ton
Kg/Mg
Rati ng
Fuel Oil - Residual
Nonmethane
lb/103 gal
Kg/103 1
Rating
Methane VOC
lb/103 gal
Kg/103 1
Rating
Fuel Oil - Distillate
Nonmethane
Kg/103 gal
Kg/103 1
Rati ng
Methane
lb/103 gal
Kg/103 1
Rating
Natural Gas
Nonmethane
lb/106 ft3
Kg/106 m3
Rating
Methane
lb/106 ft3
Kg/106 m3
Rating
Unit Type
Utility Industrial Commercial Residential
0.07 0.07 0.07 10
0.04 0.04 0.65 5
AAA 0
0.03 0.03 0.8 8
0.015 0.015 0.4 4
AAA B
1.4
0.7
D
0.3
0.15
E
100
51
0
1.0
0.5
D
0.09
0.76
A
0.034
0.28
0.14
1.13
0.03
0.28
A
0.12
1.0
A
0.057
0.475
A
0.024
0.2
A
0.04
0.34
A
0.085
0.713
A
0.006
0.052
A
0.026
0.216
A
0.214
1.78
A
1.4
2.3
C
.3
4.8
C
2.8
44
C
3
48
C
5.3
84
0
2.7
43
0
5.3
84
D
2.7
43
0
4-197
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C. Control Techniques and Emission Reduction
Volatile organic emissions from stationary external combustion sources
can be most effectively reduced by improved operating practice and equipment
designs which improve combustion efficiency. Organic emissions are directly
related to residence time, temperature, and turbulence in the combustion
zone. A high degree of fuel and air turbulence greatly increases combustion
efficiency. The trend toward better steam utilization in steam-electric
generating plants results in improved efficient in the conversion of thermal
energy from fossil fuels into electrical energy. Continued research in the
areas of magnetohydrodynamics, electrogas dynamics, fuel cells, and solar
energy may result in improved fuel usage and consequently reduced organic
emissions.
Flue gas monitoring systems such as oxygen and smoke recorders are
helpful in indicating the efficiency of furnace operation. The substitution
of gas or oil for coal in any type of furnace reduces emissions when good
combustion techniques are used. This reduction is largely effected by the
better mixing and firing characteristics of a liquid or gaseous fuel compared
to those of a solid.
D. Regulatory Status
The New Source Performance Standards promulgated for stationary external
combustion sources (fossil fuel fired steam generators and electric uility
steam generators) do not set limits on VOC emissions.
The EPA is presently developing New Source Performance Standards for wood
stoves.
E. National Emission Estimates
Table 4.7.1-2 presents VOC emissions from all types of stationary external
combustion sources. Emission estimates are based on emission factors with
ratings varying from A to D.
F. Capital and Annual Control Costs
Costs associated with increasing combustion efficiency will be site
specific. Increased efficiency reduces fuel consumption, the largest part of
annual costs.
4-198
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TABLE 4.7.1-2 VOC Emissions from Stationary Source Fuel Combustion
Source
1983 Emissions Tq/yr (10^ Mg)
Utility
0.0
0.1
0.2
2.0
. Industrial
Commercial
Residential
Total
2.1
Reference 2.
Note: A value of zero indicates emissions of less than 50,000 Mg.
G. References
1. External Combustion Sources. Compilation of Air Pollution Emission
Factors, U.S. Environmental Protection Agency, Research Triangle Park, N.C.
AP-42, August 1982.
2. National Air Pollutant Emission Estimates, 1940-1983, U.S. Environmental
Protection Agency, Research Triangle Park, N.C. EPA-450/4-84-028, December
1984, p.14.
4-199
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4.7.1.2 Stationary Internal Combustion Sources
A. Process and Facility Description
Internal combustion engines include gas turbines or large heavy-duty,
general utility reciprocating engines. Most stationary internal combustion
engines are used to generate electric power, to pump gas or other liquids, or
to compress air for pneumatic machinery.
Stationary gas turbines are used primarily in electrical generation for
continuous, peaking or stand-by power. The primary fuels are natural gas and
No. 2 (distillate) fuel oil, although residual oil is sometimes used. Emis-
sions from gas turbines are considerably lower than emissions from reciprocat-
ing engines; however, reciprocating engines are generally more efficient.
The rated power of reciprocating engines ranges from less than 15 kW to
10,044 kW (£0 to 13,500 hp). There are substantial variations in both annual
usage and engine duty cycles.
B. Emission Sources and Factors
The organic emissions from stationary internal combustion sources result
from incomplete combustion of the fuel. The emissions contain unburned
fuel components as well as organics formed from the partial combustion and
thermal cracking of the fuel. Combustion and cracking products include
aldehydes and low molecular weight saturated and unsaturated hydrocarbons. •
Emissions from compression engines, particularly reciprocating engines, are
significantly greater than those from external boilers. Table 4.7.1-3 presents
emission factors for stationary internal combustion sources.
C. Control Techniques and Emission Reductions
Emissions from internal combustion sources can be minimized by proper
operating practices and good maintenance. Emissions can be reduced greatly
with the application of catalytic converters, thermal reactors or exhaust
manifold air injections to the'engine exhaust.
The catalytic converter has been proven effective on mobile gasoline
engines. It contains a catalyst which causes the oxidation of HC and CO to
water and CO2 at reduced temperatures. Unleaded low-sulfur fuel should be
used to protect the catalyst and prevent the formation of H2SO4.
4-200
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Table A.7.1-3 Emission Factors for Stationary
Internal Combustion Sources
Diesel Engines
lb/103 hph
g/kWh
Rati ng
Gas Engines
lb/103 hph
g/kWh
Rating
Oil-fired Turbines
1b/MWh
kg/MWh
Rati ng
Gas-fired Turbines
1b/MWh
kg/MWh
Rati ng
Methane Nonmethane
0.07 0.63
0.04 0.04
C C
4.7 1.5
2.9 • 0.9
C C
.79
.36
B
.79
.36
B
4-201
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A thermal reactor provides a site for oxidation at elevated temperatures
maintained by the heat released from the oxidation of CO and HC. Air is
added to the exhaust stream in a container specially designed to maximize
both the residence time and turbulence of the charge.
Air injection into the exhaust system is similar to the thermal reactor.
However, since the existing shape of the exhaust system is not changed and
the volume is not optimized for maximum residence time, heat retention or
mixing, air injection may not be as effective as the thermal reactor.
D. Regulatory Status
New Source Performance Standards have been promulgated for stationary
gas turbines and proposed for stationary reciprocating internal combustion.
Neither standard sets limits on VOC emissions.
E. National Emission Estimates
Table 4.7.1-2 presents VOC emissions from all types of stationary combus-
tion sources. Emissions estimates are based on emissions for factors with rati
varying from A to D.
F. Capital and Annual Control Costs
No cost data are available.
G. References
1. Stationary Large Base Diesel and Dual Fuel Engines. Compilation of
Air Pollution Emission Factors, U.S. Environmental Protection Agency, Research
Triangle Park, N.C., AP-42, August 1982.
4-202
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4.7.2 Forest, Agricultural, and Open Burning
A. Source Description
Forest burning refers to forest wildfires, an uncontrolled burning of
forest fuel which can occur over hundreds of acres. Agricultural burning
refers to the combustion of field crop refuse. Agricultural burning is a
type of open burning. Open burning is used for disposal of muncipal waste,
auto body components, landscape refuse, agricultural field refuse, wood
refuse, bulky industrial refuse, and leaves. Open burning can be done in
open drums or baskets, in fields and yards, and in large open dumps or pits.
B. Emission Sources and Factors
Wildfire combustion is dependent upon the size and quantity of forest
fuels, the meteorological conditions, and the topographic features. Fuel
type and fuel quantity have been incorporated into a U. S. Forest Service
model which estimates fuel loading per acre for all regions of the country.
Using fuel loadings, acreage, and pollutant yields (12 Kg VOC/Mg of forest
fuel consumed), emissions can be calculated.1
Emissions from agricultural refuse burning are dependent upon moisture
content, wind direction relative to fire direction, fuel loading, and how the
refuse is arranged. Emission factors for open agricultural burning are
presented in Table 4.7.2-1. These factors, along with fuel loadings and acreage,
can be used to calculate VOC emissions.
Table 4.7.2-2 presents emission factors for open burning of nonagricultural
material.
C. Control Techniques and Emission Reductions
Emissions from open burning are prevented by regulations which prevent
refuse burning. Wildfire frequencies are reduced by prescribed burning, a
preventive burning of forest litter and underbrush.
D. Regulatory Status
Federal air regulations have not been set for forest, agricultural, or open
burni ng.
E. National Emission Estimates
VOC emissions due to wildfires during 1983 were estimated to be 800,000
megagrams.3 VOC emissions due to other burning during 1983 were estimated to
be 100,000 megagrams.^ All emissions estimates are based upon emission factors.
4-203
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TABLE 4.7.2-1 VOC EMISSION FACTORS FOR OPEN BURNING OF
AGRICULTURAL MATERIALS
EMISSION FACTOR RATING: B
Weeds
Forest Residues
VOC
Source
Methane
Nonmethane
Field Crops—Unspecified
kg/Mg
1b/ton
2.7
5.4
9
18
Vine Crops
kg/Mg
1b/ton
.8
1.7
3
5
kg/Mg
1b/ton
Orchard Crops--Unspecified
1.5
3
4.5
9
kg/Mg
1b/ton
1.2
2.5
4
8
kg/Mg
1b/ton
2.8
5.7
9
19
4-204
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TABLE 4.7.2-2 VOC Emission Factors for Open Burning at
Nonagricultural Material
Emission Factor Rating: B
•
VOC
Source
Methane
Nonmethane
Municipal Refuse
kg/mg
6.5
15
lb/ton
13
30
Automobile Components
kg/mg
5
16
lb/ton
10
32
4-205
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F. Capital and Annual Control Costs
No cost data are available.
G. References
1. Forest Wildfires. In - Compilation of Air Pollution Emission Factors,
U. S. Environmental Protection Agency, Research Triangle Park, North Carolina,
AP-42, January 1975.
2. Open Burning. In - Compilation of Ai r. Pol lution Emission Factors,
U. S. Environmental Protection Agency, Research Triangle Park, North Carolina,
AP42, May 1983.
3. National Air Pollutant Emission Estimates, 1940-1983, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, EPA-450/4-84-028,
December 1984.
4. Reference 3.
4-206
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4.7.3 Hazardous Waste Treatment, Storage, and Disposal Facilities (TSDF)
A. Process and Facility Description
Hazardous waste is primarily managed through treatment, storage, and
or disposal in surface impoundments, landfills, tanks, waste piles, land
treatment areas, and containers. Landfills are disposal facilities in which
hazardous wastes (excluding free liquids) are placed in containers or in bulk
form, covered over with soils and left indefinitely. In land treatment,
wastes are deposited on or worked into the soil so that natural processes can
degrade and demobilize the hazardous constituents in the wastes. Surface
Impoundments are large basins that are used to either treat or store primarily
aqueous wastes. Approximately 96 percent of all generated hazardous wastes
are managed on site with only 4 percent being shipped off site either as bulk
wastes via tank trucks, rail cars, or pipelines or as containerized wastes.
It is estimated that approximately 5,000 sites in the United States manage
hazardous waste. Based on a 1981 survey, approximately 71 billion gallons of
RCRA-regulated hazardous waste were generated.*
B. Emission Sources and Factors
These operations are primarily fugitive (non-point source) emission
sources. The potential for emissions begins at the point of generation and
continues through the ultimate treatment/disposal stage. Emissions may occur
during waste transfer as tank trucks are bottom-filled and displaced vapors
are vented to the atmosphere. During landfilling, emissions can arise from
liquids spilled on the ground or from solids, sludges, and bulk liquids which
are exposed to the atmosphere. Once the landfill is covered, emissions can
occur from compounds diffusing toward the surface and escaping to the atmo-
sphere. In surface impoundments and open tanks, atmospheric emissions are
produced by the volatilization of compounds at the surface followed by their
diffusion into the atmosphere. At land treatment facilities emissions can
occur from pools of liquid waste that may form prior to seepage, from the
evaporation of volatile constituents in the soil pore-spaces that diffuse to
the soil surface, and from tilling the soil. In fixed roof tanks volatile
materials diffuse into the head space and are vented to the atmosphere.
Leakage at the seal of floating roof tanks can contribute to emissions.
Emission factors for these sources are under development.
4-207
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C. Control Techniques and Emission Reduction^
Control of emissions from the TSDF can be accomplished through several
means: pretreatment techniques, design and operating practices, physical
barriers, and capture and control techniques. Distillation, stripping,
carbon adsorption, and solvent extraction may be appropriate pretreatment
control techniques to reduce the volatiles content of wastes to be placed in
surface impoundments, tanks, and landfills. Design considerations such as
increased freeboard depth may be a control option for surface impoundments.
Submerging the influent pipes into the bulk liquid in surface impoundments
and tanks is an option. Temporary covers may be used during the active life
of a landfill. Overloading of wastes onto land treatment areas should be
avoided. Floating rafts and synthetic covers are examples of physical barriers
to reduce emissions from surface impoundments. Installation of floating
roofs on storage tanks can decrease emissions. Capture and control would
include venting emissions from covered surface impoundments, tanks, and
landfills, and from exhaust gas streams and condenser vents on pretreatment
devices to an adsorber or incinerator. The emission reduction benefits are
in the process of being quantified (See next subsection).
D. Regulatory Status
With its enactment of the Resource Conservation and Recovery Act of
1976 (RCRA) and its subsequent amendments thereto in 1978 and 1980, Congress
required the EPA to promulgate a regulatory program ensuring adequate protection
to human health and the environment in the generation, transportation, and
management of hazardous wastes. On November 9, 1984, President Reagan signed
amendments to RCRA requiring development of air regulations for TSDF within
30 months. Sources to be regulated under Section 3004 of RCRA that are to be
considered for air emissions regulations include surface impoundments,
landfills, tanks, waste piles, land treatment facilities, containers, and
waste transfer operations. Work in the area of TSDF air emissions is in the
very preliminary stages, and standards are still to be developed.
E. National Emission Estimates
A preliminary 1983 nationwide VOC emissions estimate based on 54
RCRA regulated chemicals from TSDF estimated emissions to be about 1600
gigagrams (1.7 million tons) per year. Upon extrapolating this estimate to
4-208
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reflect emissions from all RCRA regulated chemicals, total nationwide VOC
emissions from TSDF were estimated to be between 1600 and 5400 gigagrams
(1.7 and 5.9 million tons) per year.3
F. Capital and Annual Control Costs
Currently, there are no available cost estimates for potential TSDF
control techniques. Cost estimates will be developed as the program progresses.
G. References
1. National Survey of Hazardous Waste Generators and Treatment,
Storage and Disposal Facilities regulated under RCRA in 1981, Westat, Inc.,
U.S. EPA Contract No. 68-01-6861, April 20, 1984.
2. Evaluation of Emission Controls for Hazardous Waste Treatment,
Storage and Disposal Facilities, Arthur D. Little, Inc., U.S. EPA Contract
No. 68-01-6160, November 16, 1984.
3. Assessment of Air Emissions from Hazardous Waste Treatment,
Storage and Disposal Facilities (TSDF) Preliminary National Emissions Estimate,
Draft Final Report by GCA Corporation, U.S. EPA Contract No. 68-02-3168,
August 1983.
4-209
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4.7.4 Publicly Owned Treatment Works (POTVJs)
A. Process and Facility Description
Approximately 15,000 publicly owned treatment works (POTWs) in the
United States treat domestic, nonresidential and industrial wastewaters.
Approximately 1,500 of these POTWs treat 82 percent of all Industrial
wastewater discharged to POTWs.
POTWs use a combination of biological and physical/chemical treatment
methods and are primarily designed to reduce discharges of biochemical
oxygen demand (BOO) and total suspended solids (TSS) to be receiving stream.
In addition, plants typically chlorinate the final effluent to reduce
bacterial counts. Biological treatment includes activated sludge, aerated
lagoons, stabilization ponds, trickling filters, oxidation ditches, and
rotating biological contactors (RBC). Physical/chemical treatment includes
clarification, filtration, coagulation, flocculation, flow equalization,
chlorination, and carbon adsorption. Additonal biological and physical/
chemical treatment methods are used to treat wastewater sludges.
B. Emission Sources and Factors
A1r emissions from POTWs are due to volatilization of the organic
compounds contained in the influent. Organic confounds can volatilize
en route to the POTW and at the POTW itself. Volatilization can occur
wherever air-liquid contact 1s provided. Important locations within a POTW
where this stripping can occur include aerated lagoons, activated sludge,
trickling filters, RBC, equalization basins, and aerated grit chambers.
Additional stripping can occur in other areas which provide air-wastewater
contact such as hydraulic jumps, overflow weirs, clarifier surfaces and
open channels. Incineration of sewage sludge also results in emissions
associated with the oraganic constituents that have adsorbed to the sludge.
C. Control Techniques and Emission Reduction
Control of emissions from POTWs can be accomplished through the
following methods: pretreatment, in-plant, and post-treatment. Pretreatment
methods include steam stripping, distillation, carbon adsorption, solvent
4-210
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extraction, and industrial process changes. All these methods can reduce
the volatiles content of the industrial wastewater prior to discharge to
the collection system. In-plant controls can include carbon adsorption,
covered tanks, and steam stripping. Post-treatment would include use of a
carbon adsorber or flare to control emissions from covered treatment units.
Emission reduction data are not presently available.
0. Reulatory Status
Regulations for air emissions from POTWs have not yet been developed.
Several different program offices within EPA are currently investigating
air emissions from wastewater treatment. A task force was formed in February
1986 to develop the Agency approach for regulation of these air emissions.
E. National Emission Estimates
Total nationwide volatile organic compound (VOC) emissions from POTWs
were estimated to be 21,000 Mg/yr (23,000 tons/yr) in 1985.1
F. Capital and Annual Control Costs
Cost estimates for POTW control techniques are not presently available.
G. References
1. Domestic Sewage Study, Draft Final Report by Science Applications
International Corporation, U.S. EPA Contract No. 68-01-6912, WA No. 17,
October 24, 1985.
4-211
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APPENDIX A
Appendix A gives a listing of volatile organic compound (VOC)
emissions in the United States for various miscellaneous organic solvent
uses. This list concentrates on industries that emit VOC when applying
paints and coatings to manufactured products or when applying printing
inks. The list also covers VOC emitted from the use of common household
products and from some other miscellaneous manufacturing industries.
A-l
-------
Baseline VOC Emissions Status
Before Control (NR means
Industry (Metric Tons per Year) no regulations)
Pressure Sensitive
Tapes and Labels
450,000
Paper Coating CTG, 5/77;
NSPS proposed 12/30/80
Architectural Coating
Aerosol Products
Wood Furniture
360,000
292,000
200,000
NR
NR
NR
Metal Manufacture
(metal rolling)
Autobody Refinishing
200,000
200,000
NR
NR
Mi seel 1aneous
Web Coating
Polymers and
Resins
175,000
172,000
Paper Coating CTG, 5/77
Draft CTG, 1982;
NSPS being written
Use of Household
Products Containing
VOC
160,000
NR
Synthetic Fibers
151,000
NSPS promulgated 4/5/84
Publication Rotogravure 150,000
Graphic Arts CTG,
12/78; NSPS promulgated
11/8/82
A-2
-------
Baseline VOC Emission Status
Before Control (NR means
Industry (Metric Tons Per Year) no regulations)
Pesticides 140,000
Toiletries 113,000
Industrial Maintenance 106,000
Paints
Metal Furniture 95,000
Rotogravure Package
Printing 87,000
Fabricated Metal Products 84,000
Paint Removing 75,000
Heat-set, Web Offset 70,000
Pri nting
Cans 68,000
Flexible Vinyl Coating 68,000
Flexographic Package
Printing 67,000
Rubber Tire Manufacture 65,000
Automobile Painting 64,000
OEM
NR
NR
NR
Metal Furniture CTG 10/77;
NSPS promul gated 10/29/82
Graphic Arts CTG 5/77
Misc. Metal CTG, 6/78
NR
NR
Can CTG 5/77; NSPS
promulgated 8/25/83
Fabric coating CTG
5/77; NSPS promulgated
6/29/84
Graphic Arts CTG 5/77
Tire CTG 12/78; NSPS
proposed 1/20/83
CTG, 5/77; NSPS promul-
gated 10/24/80
-------
Industry
Baseline VOC Emission
Before Control
(Metric Tons Per Year)
Status
(NR means
no regulations)
Windshield Washing
52,000
NR
Flexible Packaging
Coating
50,000
Paper-coating and Graphic
Arts CTG, 5/77 and 12/78
Ferrous Foundaries
Rubber (Elastomeric-
Coated Fabric)
49,000
43,000
NR
Fabric Coating
CTG, 5/77
Letter-Press Printing
Truck and Bus Bodies
43,000
41,000
CTG, 5/77
Misc. Metal CTG, 6/78
Polishes and Waxes
Textile Dyeing
Photographic Products
Fabric Printing
Whiskey Oistilleries
(and Warehousing)
41,000
39,000
38,000
38,000
38,000
NR
Paper-Coating CTG, 5/77
NR
NR
Machinery (Industrial
and Commercial)
35,000
Misc. Metal CTG, 6/78
A-4
-------
Industry
Baseline VOC Emissions
Before Control
(Metric Tons per Year)
Status
(NR means
no regulations)
Magnetic Tape 33,000 Paper-coating CTG, 5/77
NSPS proposed 1/22/86
Traffic Paint 33,000 NR
Coil-coating
33,000
Coil-coating CTG, 5/77;
NSPS promulgated 11/1/82
Recreational Vehicles
Farm Machinery and
Construction Equipment
30,000
Misc. Metal CTG, 6/78
Magnet Wire Coating
Construction adhesives
(including use for
floor tile and wal 1
coverings)
30,000
27,000
Magnet Wire CTG, 12/7 7
NR
(Non-Tire) Rubber
Product Adhesives
Large Appliances
24,000
24,000
NR
Appliance CTG, 12/77;
NSPS promulgated 10/27/82
Flat Wood Coating
Vinyl Floor Coverings
24,000
23,000
Wood Paneling CTG 6/78
Fabric-coating CTG, 5/77
Textile-fi n1 shing
Gi ft Wrap
Auto Assembly
Adhesives
21,000
21,000
21,000
NR
Paper-coating CTG, 5/77
NR '
A-5
-------
Baseline VOC Emissions Status
Before Control (NR means
Industry (Metric Tons per Year) no regulations)
Marine coatings
(Ships and Boats)
Rubber Footware
Manufacture
Non-Ferrous
Foundaries
Paint Manufacture
Small Appliances
Office Copier Paper
Extraction Hardwood
Pulping
Inked Ribbons for
Business Machines
Space Deodorant
Foam-blowi ng
Plywood
Moth Control
Fabricated Rubber Goods
Fiberglass Reinforced
PIastics
20,000 NR
20,000 NR
18,000 NR
17,000 NR
17,000 Miscellaneous
Metal CTG, 6/78
16,000 Paper-coating CTG
5/77
15,000. NR
15,000 Paper-coating CTG
5/77
15,000 NR
13,000 NR
12,000 Plywood CTD
5/83
12,000 NR
12,000 NR
11,000 NR
A-6
-------
Industry
Baseline VOC Emissions
Before Control
(Metric Tons per Year)
Status
(NR means
no regulations)
Solvent Extraction 11,000
SBR Rubber Production 11,000
Electronics (includes 10,000
Integrated Circuits)
Textile Heat-setting 9,000
Non-Petroleum Lube Oil 9,000
Manufacturing
Nitrocellulose-coated 9,000
Products
Aluminum Extrusions 9,000
Shoe Adhesive 8,000
Railroad Equipment 8,000
Coati ng
Wall Covering Coatings 7,000
Plastic Parts Coating
for Business Machines 5,000
Petroleum Lube Oil 5,000
Manufacturing
Adhesive Manufacture 5,000
Extraction, Rare Metals 5,000
Sandpaper Manufacture 3,000
Carbon Paper Manufacture 3,000
Textile Texturizing 3,000
Tanneries 2,800
A-7
NR
NR
NR
NR
NR
Paper-coating CTG
5/77
Misc. Metal CTG, 6/78
NR
Misc. Metal CTG, 6/78
Paper-coating CTG,
5/77
NSPS proposed 1/8/86
NR
NR
NR
Paper-coating CTG, 5/77
Paper-coating CTG, 5/77
NR
NR
-------
Industry
Baseline VOC Emissions
Before Control
(Metric Tons per Year)
Status
(NR means
no regulations)
Aircraft Coating
OEM
Tire Retreading
Rubber Reclaiming
Light Bulbs and CRT's
2,000
2,000
1,300
500
NR
NR
NR
NR
Pails and Drums
Unknown
Misc. Metal CTG
6/78
Cosmetic Manufacture
Unknown
NR
Pressure-treating of
Wood
Unknown
NR
Food Processing (includ-
ing Coffee Roasting)
Unknown
NR
A-8
-------
Appendix B - Cost Indexes
Costs presented in Chapter 4 have been updated to 1984 (second quarter
or May 1984) costs using the indexes presented in this appendix. The
cost indexes shown on Tables B-l and 8-2 are based on national or industry
average increases in product, fabrication or labor costs. Using these
indexes to update actual cost estimates will not provide the reader with
the actual cost that can be expected in 1984, but provide a rough cost
estimate for comparing control costs on an equal year basis with control
costs from other industries.
Capital costs and installation costs are updated by using the CE
Plant or Fabrication Equipment Cost Indexes. The Fabrication Equipment
Cost index is used in cases where control costs are far add-on equipment
or minor modifications to process lines or units. The CE plant index is
used in cases vrfiere control costs are for major changes or conversions in
the process lines or units. Annual costs are either recalculated using
the updated capital costs or updated by using the fixed weighted price
indexes for gross national product. Cost estimates are updated by using
the following formula:
Updated Cost Estimate
Cost = in X year(month x index for second quarter or Hay 1984
Estimate or quarter) $ index for X year(month or quarter)
B-2
-------
Table B-l. Chemical Engineering Plant (CEP) Index and
Fabricated Equipment (FE) Component Values*
Date
CEP
FE
Date
CEP
FE
Date
CEP
FE
Dec.
1977
210.3
226.2
Jun.
1979
237.2
259.9
Dec.
1980
272.5
304.0
Jan.
1978
210.6
226.6
Jul.
1979
239.3
262.6
Jan.
1981
276.6
305.9
Feb.
1978
213.1
233.0
Aug.
1979
240.7
264.2
Feb.
1981
280.5
307.1
Mar.
1978
214.1
233.6
Sep.
1979
243.4
266.6
Mar.
1981
286.3
314.7
Apr.
1978
215.7
237.1
Oct.
1979
245.8
271.6
Apr.
1981
290.3
321.9
May
1978
216.9
237.3
Nov.
1979
246.8
272.6
May
1981
295.2
321.6
Jun.
1978
217.7
237.4
Dec.
1979
247.6
273.7
Jun.
1981
298.2
322.9
Jul.
1978
219.2
238.6
Jan.
1980
24:8.5
273.8
Jul.
1981
303.1
325.6
Aug.
1978
221.6
243.3
Feb.
1980
250.8
276.9
Aug.
1981
305.2
325.7
Sep.
1978
222.8
243.2
Mar.
1980
253.5
277.7
Sep.
1981
307.8
326.7
Oct.
1978
223.5
243.8
Apr.
1980
257.3
289.3
Oct.
1981
308.4
330.8
Nov.
1978
224.7
244.1
May
1980
258.5
290.9
Nov.
1981
306.6
329.4
Dec.
1978
225.9
245.2
Jun.
1980
259.2
291.3
Dec.
1982
305.6
328.9
Jan.
1979
225.9
245.2
Jul.
1980
263.6
296.7
Jan
1982
311.8
324.5
Feb.
1979
231.0
252.5
Aug.
1980
264.9
297.3
Feb.
1982
310.7
323.4
Mar.
1979
232.5
253.1
Sep.
1980
266.2
298.1
Mar.
1982
311.4
324.1
Apr.
1979
234.0
253.7
Oct.
1980
268.6
301.2
Apr.
1982
313.2
327.8
May
1979
236.6
258.3
Nov.
1980
269.7
302.5
May
1982
314.5
329.1
B-3
-------
i. 1982
. 1982
I. 1982
i. 1982
.. 1982
. 1982
. 1982
. 1983
. 1983
. 1983
. 1983
• 1983
. 1983
. 1983
. 1983
. 1983
. 1983
. 1983
. 1983
. 1984
. 1984
. 1984
. 1984
1984
. 1984
y 1984
. 1984
. 1984
. 1984
. 1984
. 1984
. 1985
ource:
Table B-l. Chemical Engineering Plant (CEP) Index and
Fabricated Equipment (FE) Component Values* (Con't)
CEP FE Date CEP FE Date CEP FE
313.3 327.5
314.2 327.1
315.0 326.2
315.6 326.7
316.3 325.8
315.3 324.8
316.1 325.1
315.5 324.4
316.9 327.6
315.9 326.8
315.5 326.6
315.9 327.1
315.7 327.3
316.5 327.0
316.7 327.1
318.3 328.0
318.2 327.8
318.0 328.9
319.3 330.1
320.3 331.5
320.4 333.0
321.3 332.9
321.9 333.8
322.7 334.6
322.5 333.8
323.5 335.4
323.6 335.1
Chemical Engineering, McGraw-Hill Publications
B-4
-------
Table B-2. Implicit Price Deflators for Gross National Product (GNP)
and Fixed-Weighted Price Indexes for Gross National Product (WGNP)
(1972 » 100)
1st Q 2nd Q 3rd Q 4th Q
1977
GNP 138.13 140.52 142.19 144.23
WGNP 139.9 142.3 144.0 146.1
1978
GNP 145.8 148.8 151.3 153.8
WGNP 149.1 152.6 155.7 159.0
1979
GNP 160.22 163.81 167.20 170.58
WGNP 162.8 166.6 170.6 174.4
1980
GNP 171.23 175.28 170.18 183.81
WGNP 177.1 181.1 185.1 189.7
1981
GNP 190.01 193.17 197.36 201.55
WGNP 195.9 199.9 204.20 208.40
1982
GNP 203.36 206.15 208.03 210.00
WGNP 210.7 213.1 216.2 218.70
1983
GNP 212.87 214.25 215.89 218.21
WGNP 220.7 222.9 225.5 227.6
1984
GNP 220.58 222.4 NA NA
WGNP 230.4 232.8 NA NA
Source: Survey of Current Business, U. S. Department of Commerce, Bureau of
Economic Analysis
B-5
-------
APPENDIX C
ADDITIONAL INFORMATION CONTROL TECHNOLOGIES
"Summary of Control Technologies For Dilute VOC Emission
Streams", EPA, OAQPS, ESD, CPB, CAS, October 5, 1989
"Carbon Adsorption for Control of VOC Emissions: Theory and
Full Scale System Performance", EPA, OAQPS, June 1988,
EPA-450/3-88-012.
-------
October 5, 1989
Summary of Control Technologies for
Dilute VOC Emission Streams
Due to lack of compliance with the ozone standard in many parts of the
nation, it is becoming increasingly necessary to control sources of volatile
organic compounds (VOCs) which in the past have frequently been considered too
difficult or costly to control. The control of VOC from dilute, large volume
sources, for example, the exhaust from paint spray booths, has been a
challenging and often costly problem. If controlling a dilute (i.e. low VOC
concentration) gas stream with incineration, costly supplemental fuels must be
used. Steam regeneration of a carbon adsorption system can also be very
costly especially if the recovered material is not reusable or marketable.
In recent years, technology has been developed which should make the
control of low VOC concentration emissions considerably more cost effective.
Information on three relatively new systems has been presented to this office.
They are the Calgon CADRE system, the Met Pro KPR system and the
Weatherly/Nobel Chematuer Polyad FB system. CADRE and KPR utilize granular
activated carbon and activated carbon fiber respectively to concentrate the
VOC prior to sending it to a final control device, i.e., an incinerator or a
solvent recovery unit. The Polyad FB system is a fluidized bed solvent
recovery unit which utilizes an adsorbent made of a propriatory polymer. Each
of these systems has proven efficient and cost effective in trial applications
and, for Polyad FB and KPR, plant applications. Each system will be discussed
including available cost and operating data. The information presented was
provided by the manufacturers.
The Calaon CADRE System
Calgon Carbon Corporation in Pittsburgh, Pennsylvania, has been a major
domestic supplier of activated carbon for several years. It did not market
hardware, but rather sold carbon to the several carbon adsorber hardware
C-3
-------
manufacturers. In 1987, it began marketing a combined carbon
adsorption/incineration system they refer to as CADRE. CADRE was conceived as
an alternative to direct incineration of low concentration (< 500 ppm), high
volume streams or as an alternative in applications where steam regenerated
carbon adsorber designs were not economical due to high steam costs.
CADRE is a two-vessel system designed for up to 10,000 SCFM; for higher
flows, multiple vessels are used. The adsorption part of the system behaves
as a normal carbon adsorber with one bed adsorbing while the other is
regenerated and held off line. Regeneration, however, is done with 300 to
350° F flue gas from the incinerator rather than steam which is typically used
to regenerate carbon adsorbers. Figure 1 presents a schematic of CADRE. This
system is most economical for low concentration, high flow rate streams where
15-20 pounds of steam per pound adsorbate would be required as compared to a
typical range of 6-8 pounds steam/pound adsorbate. Because of low mass fldW
rate of solvent a bed can remain in the adsorption cycle for a much longer
period of time before breaking through than if it were operating on a much
richer stream.
The incinerator is operated at 1650° F if the exhaust contains
halogenated compounds and 1500° F for organic compounds. The hot gas
regeneration flow to the incinerator is limited to 5 to 10 percent of the
contaminated air stream flow rate to the adsorber. The hot regeneration gas
desorbs the organic in a concentrated stream and the low air flow rate allows
use of a much smaller incinerator than would be required for the entire
process exhaust air flow. Additionally, because of the low concentration of
V0C in the process exhaust, a bed will remain in the adsorbtion mode for an
extended period of time compared to the length of the regeneration cycle. As
a result, the incinerator must be operated only intermittently.
EPA has in the past received comments that certain industries have a
concern with the use of incinerators for the control of coating solvents from
nitrocellulose base coatings. They report that the nitrocellulose in the
overspray plates out on the duct work, thereby providing a flammable burn path
2
C-4
-------
from a incinerator back into the plant (spraybooth). As a result, a fire may
start in the incinerator and "flashback" through the ventilation duct thus
endangering employees. While the Agency has not reviewed this issue in depth
(the wide availability of flame arrestors for similar purposes would be
examined), the use of a high efficiency filtration system and a control system
such as CADRE would appear to eliminate such concerns. Since the incinerator
is only operational during regeneration of a carbon bed (i.e., the carbon bed
is disconnected from the VOC source), the incinerator is effectively isolated
from the coating process. Therefore, there can be no danger to workers due to
"flashback" caused by the incinerator.
Calgon guarantees that their system will achieve an average efficiency
of 95 percent. In pilot testing the carbon system obtained greater than 99
percent removal efficiency and the incinerator efficiency exceeded 99.9
percent for an overall control of 98.9 percent.
Limited information is available on operations and costs of the CADRE
system. Calgon has been contracted to install systems for:
o Superfund site, Long Island, NY, 9000 CFM
o Defense contractor - aircraft, Texas, 3500 CFM
o Metal furniture spray booth, Michigan.
One CADRE system is operational at a superfund site in Washington with a
flow rate of 3500 CFM. They are achieving approximately 90 - 95 percent
control, however, levels of VOC in the gas stream are so low that the exact
level of control cannot be determined. Installation costs were unavailable,
however, as other systems are being installed, and data becomes available it
will be appended to this report.
-------
The Met-Pro KPR System
Met-Pro Corporation, Harleysville, Pennsylvania, has licensed a VOC
control called the KPR Solvent system for dilute, large volume sources. The
system has been primarily marketed towards paint spray booths, due to the fact
that they are almost always dilute large volume sources. Thirty KPR systems
had been installed as of June 1988 in a variety of facilities utilizing paint
spray systems including automobile painting and aircraft parts painting.
The KPR system consists of a cylindrical rotor containing activated
carbon fiber formed into a "honeycomb". Solvent laden air enters the cylinder
and flows radially through a segment of the cylinder. The cylinder rotates,
continuously exposing a different portion of the rotor to the contaminated
air. As the rotor turns, a second, smaller, hot, air stream passes through
removing the VOC carrying it from the rotor. See Figure 2. The concentrated
exhaust from the KPR rotor is then routed to an incinerator or carbon adsorber
and is typically concentrated to 5 to 20 times that of the inlet to the
adsorption rotor.
The control efficiency of the KPR rotor for most solvents is reportedly
95-98 percent. Incineration can obtain up to 99 percent control efficiency as
well. Therefore, the control efficiency for the system can range 90 - 97
percent.
Met-Pro has reported achieving a control efficiency of > 95 percent
using the KPR system at an auto parts coating facility. At one aerospace
facility, the KPR system has been reported to achieve 90 percent control
efficiency on an inlet stream with a concentration of only 7 ppm.
The concentrating effect of the KPR system permits the incinerator to be
significantly smaller thereby reducing operating costs (fuel) over that of a
conventional incinerator. The KPR system is most cost effective when the
concentrated flow from the rotor is directed to an incinerator. Heat from the
incinerator can be used to heat the desorption air and to preheat the
4
C-6
-------
incinerator inlet stream, often requiring no additional fuel. Catalytic
incinerators are less expensive to operate than conventional thermal
incinerators.
One advantage of the KPR system that Met-Pro reports is that there is no
risk of bedfires with the KPR rotor, even for ketones which require carefully
controlled regeneration conditions to preclude bedfires in conventional fixed
bed systems. This is due to the quick and continuous adsorb/desorb cycle of
the KPR system, approximately 7 minutes, which does not allow the carbon to
get hot enough to ignite.
The system, sold as modular units, is small and light weight, readily
suitable for roof mounting. A diagram of KPR installation is found at Figure
3.
Met Pro provided cost information for two operations: a 25,000 CFM auto
parts paint spray booth with a VOC control cost of $1571/ton and a 250,000 CFM
auto topcoat paint spray booth with a VOC control cost of $2546/ton.
The cost breakdown for the KPR system on the auto parts paint spray
booth is as follows:
Installed capital cost $1,000,000
Annual operating cost $75,000 *
Tons/year removed 175
* Electricity $27,000 assuming 3840 operating hours at $0.05/KWH
Fuel gas $8,500 assuming $4.00/MMBTU
Manpower $11,000 assuming $20/hr.
Spare parts $27,000
Control efficiency is reported to be 94 percent.
5
C-7
-------
If it were assumed that $200,000 of the $1,000,000 capital costs plus
interest were paid
per year, the cost of control per ton V0C removed would be:
$200.000 + $75.000
175 tons = $1571/ton
The Nobel-Chemateur Polvad FB System
The Polyad FB Air Purification and Solvent Recovery System is a
continuous fluidized bed process. It was developed by Nobel Chemateur, the
chemical engineering company of Nobel Industries Sweden, and marketed in the
U.S. by Weatherly Inc., Atlanta, Georgia.
The adsorbent for the Polyad FB system, called Bonopore, consists of
macro-porous polymer particles with a very high specific surface
(approximately 800 m2/g) and a particle diameter of about 0.5 mm. Bonopore is
easy to desorb, requiring a low regeneration temperature (typically 100°C) and
less "air or N2 than typical of other adsorbents. It can also be modified
physically and chemically to suit various applications. Additionally, it does
not degrade or initiate polymerization of solvents, or other VOC which can
occur with carbon.
The recommended solvent concentration for the Polyad FB system is 0.1 -
lOg. sol vent per m1 air (approximately 20 - 3000 ppm). The system is usually
designed for 90 - 95 percent control, but reportedly can achieve almost 100
percent if required. System can be designed for flows from as little as a few
hundred m1 per hour up to several hundred thousand m3 per hour.
The Polyad FB system consists of two main parts: the adsorption section
comprising the main fan and one or more beds where incoming air is purified
and the desorption section comprising a polymer container, stripper column,
condenser for cooling the solvent, fan for pneumatic transport, and tank and
pump for the recovered solvent. Figure 4 is a diagram of the Polyad FB
process.
6
C-8
-------
The solvent is adsorbed by the polymer particles as the air passes
upward through the adsorption beds. The flow of air also causes the adsorbent
to fluidize so that the polymer particles behave as a liquid and flow from the
adsorption to the desorption section. A continuous flow of adsorbent through
the beds is maintained as the saturated adsorbent is removed from the bottom
and regenerated adsorbent is fed in at the top of the adsorption section.
The saturated adsorbent is transported to the top of the desorption
section for regeneration. As it descends through the desorber; it is heated
to a temperature at which the solvent is released. The vacuum created in the
top of the desorber by the pneumatic transport fan draws air and the released
solvent, where it is directed to a condenser for recovery.
Weatherly provided cost information for an installation at a 6000 cfm
wood furniture spray coating operation in Sweden:
Installed capital cost (in US dollars) $600,000
Annual operating cost $6360*
Tons/year removed 45
Bonopore Adsorbent $3240 assuming replacement of 120 kg/year at $27/kg
Does not include labor or other maintenance costs.
'Electricity $3120 assuming 2496 operating hours at $0.05/KWH
"Weatherly reported that the solvent concentration was a maximum of
2.7g/m3 (approximately 700 ppm). As this was the only concentration reported,
it was used to determine the tons/year removed.
7
C-9
-------
If it were assumed that $120,000 of the $600,000 capital costs plus
interest were paid per year, the cost of control per ton V0C removed would be:
($120.000 + S6360) = $2808/ton
45 tons
As the Polyad FB system is a solvent recovery device, the value of the
recovered solvent would reduce the control cost.
8
C-IO
-------
References
1. U. SenGupta, Calgon Carbon Corporation: "Granular Activated Carbon -
Thermal Regeneration Process for Control of VOC Emissions
from Surface Coating Operations"; presented at the
81st Annual Meeting of APCA, June 19-24, 1988.
2. Keith W. Barnett, Radian Corporation to Carbon
Adsorber/Condensation Project File, February 29,
1987, Meeting Minutes EPA - Calgon Carbon
Corporation.
3. Met-Pro Corporation: Bulletin 11300, "KPR Solvent
Concentrating Systems For Control of Low Concentration
Volatile Organics.
4. Robert E. Kenson and James F. Jackson, Met-Pro Corporation:
"Operating Experience with Systems for Paint Spray Booth VOC
Emissions Control", presented at the 81st Annual
Meeting of APCA, June 19-23, 1988.
5. Robert E. Kenson: "Operating Results from KPR
Systems for VOC Emission Control in Paint Spray
Booths", presented at the CCA Surface Coating '88
Seminar and Exhibition, May 18, 1988.
6. Nobel Chemateur: "Polyad FB Air Purification and
Solvent Recovery", brochure.
7. Christer Heinegard, Nobel Chematuer: "The Polyad FB Process
for VOC Control and Solvent Recovery", presented at the 81st
Annual Meeting of APCA, June 19 - 24, 1989.
9
c-ll
-------
United States Office of Air Quality EPA-450/3-88-012
Environmental Protection Planning and Standards June 1988
Agency Research Triangle Park NC 27711
& EPA Carbon Adsorption
for Control of
VOC Emissions:
Theory and Full Scale
System Performance
Preceding page blank
C-13
-------
Carbon Adsorption for Control of VOC Emissions:
Theory and Full Scale System Performance
Emission Standards Division
U. S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
August 1988
Preceding page blank
-------
TABLE OF CONTENTS
Section Page
1 INTRODUCTION 1-1
2 SUMMARY AND CONCLUSIONS 2-1
3 THEORY AND PERFORMANCE OF CONVENTIONAL FIXED BED
CARBON AOSORBERS 3-1
3.1 Mechanism of Adsorption and Desorption 3-1
3.2 Full Scale Adsorption Systems 3-13
3.2.1 System Overview 3-13
3.2.2 Full Scale System Design Considerations 3-15
3.3 Carbon Adsorber Long- and Short-Term Efficiency 3-22
3.3.1 Calculation of Carbon Adsorber Efficiency 3-23
3.3.2 Variability of Short-Term Removal Efficiency 3-25
3.3.3 Relationship of Outlet Concentration and
Efficiency 3-25
3.4 Effect of Operating Variables on Adsorber Performance 3-29
3.4.1 Temperature 3-29
3.4.2 Concentration 3-33
3.4.3 Humidity 3-34
3.4.4 Volumetric Flowrate 3-38
3.4.5 Bed Fouling 3-41
3.4.6 Channeling 3-43
3.5 Deliberate Changes from Initial Design
Operating Conditions 3-43
3.5.1 Adsorbate 3-45
3.5.2 Steaming Conditions 3-45
3.6 Performance Information on Industrial Adsorbers 3-46
3.6.1 Data Sources 3-47
3.6.2 Removal Efficiency Data for Performance Test 3-52
3.6.3 Continuous Removal Efficiency Data 3-57
3.7 Conclusions Regarding Carbon Adsorber Performance 3-50
Preceding page blank
ii c—17
-------
TABLE OF CONTEHTS, Continued
Section Page
4 CARBON ADSORPTION SYSTEM AT COMMENTER'S FACILITY 4-1
5 REFERENCES 5-1
C-18
1ii
-------
LIST OF TABLES
labia* Eaas.
3-1 Reported Bed Lives for Various Solvent Blends 3-44
3-2 Performance Test Data for Carbon Adsorption Systems 3-48
3-3 Performance Test Data for Carbon Adsorption Systems on a
Per Bed Basis 3-50
iv c~19
-------
LIST OF FIGURES
Figure Paoe
3-1 Representation of Carbon Pellets/Particles in Carbon Bed 3-3
3-2 Representation of Pores in Activated Carbon Particle 3-4
3-3 Mechanism of Adsorption 3-6
3-4 Simplified Representation of Carbon Capacity 3-9
3-S Available Working Capacity as a Function of Olstance
Through Bed for an Operating Bed 3-9
3-6 Simplified Pore Representation of Capacity as a Function
of Olstance Through Bed 3-11
3-7 Vapor stream Concentration as a Function of 0-1 stance
Through Bed 3-12
3-8 Carbon Adsorber System Process Flow Diagram 3-14
3-9 Steam Consumption Versus Working Capacities 3-13
3-10 Adsorbate Concentration in Bed After Steaming Countercurrently
as a Function of Olstance Through Bed 3-19
3-11 Adsorption/Oesorptlon Cycles in a 2 Bed System 3-21
3-12 Determination of Carbon Adsorber Removal Efficiency 3-24
3-13 Typical Carbon Adsorption Breakthrough Curve 3-26
3-14 Carbon Capacity vs. Temperature at Constant Pressure 3-31
3-15 Carbon Adsorber Removal Efficiency with Varying Bed
Temperature for a Complete Adsorption Cycle 3-32
3-16 6TR Test Number 6 Continuous Inlet/Outlet VOC Concentration
Oata and Removal Efficiency 3-35
3-17 GTR Test Number 5 Continuous Inlet/Outlet VOC Concentration
Oata and Removal Efficiency 3-36
3-18 Effect of Relative Humidity on Working Capacity... 3-37
3-19 Effect of Variation 1h Volumetric Flowrate on the Shape
of the Breakthrough Curve 3-39
C-20
v
-------
LIST OF FIGURES, Continued
Fioure Page
3-20 Carbon Adsorber Removal Efficiency with Varying Flowrate
for a Complete Adsorption Cycle 3-40
3-21 Carbon Adsorber Removal Efficiency as a Function of Bed
Age for a Ketone Containing System 3-42
3-22 Inlet/Outlet Concentration Curve for Test 3 3-54
3-23 GTR Test Number 5 Continuous Inlet/Outlet VOC Concentration
Data and Removal Efficiency 3-58
3-24 GTR Test Number 6 Continuous Inlet/Outlet VOC Concentration
Data and Removal Efficiency 3-59
3-25a Inlet and Outlet Concentration Versus Cycle Time for
Adsorber #1 3-61
3-25b Instantaneous and Cumulative Efficiency Versus Cycle Time
for Adsorber #1 3-61
3-25c Inlet and Outlet Concentration Versus Cycle Time for
Adsorber #2 3-62
3-25d Instantaneous and Cumulative Efficiency Versus Cycle Time
for Adsorber #2 3-62
3-25e Inlet and Outlet Concentration Versus Cycle Time for
. Adsorber #3 3-63
3-25f Instantaneous and Cumulative Efficiency Versus Cycle Time
for Adsorber #3 3-63
3-25g Inlet and Outlet Concentration Versus Cycle Time for
Adsorber # 4 3-64
3-25h Instantaneous and Cumulative Efficiency Versus Cycle Time
for Adsorber #4 3-64
3-251 Inlet and Outlet Concentration Versus Cycle Time for
Adsorber #5 3-65
3-2SJ Instantaneous and Cumulative Efficiency Versus Cycle Time
for Adsorber #5 3-65
C-21
vi
-------
LIST OF FIGURES, Continued
Figure £ias
3-25k Inlet and Outlet Concentration Versus Cycle Time for
Adsorber #6 3-65
3-251 Instantaneous and Cumulative Efficiency Versus Cycle Time
for Adsorber #6 3-66
©
C-22
vi 1
-------
1. INTRODUCTION
This report presents the results of an investigation into the performance
and operation of vapor phase carbon adsorption systems. This investigation
was initiated as a result of comments received by the U. S. Environmental
Protection Agency (EPA). These comments were in reference to the draft new
source performance standards (NSPS) for control of VOC emissions from the
manufacture of magnetic tape. The commenter challenged EPA's supporting data
for the proposed performance requirements for carbon adsorption systems and
the costs for operating and maintaining carbon adsorption systems at the
required performance level. Specifically, the commenter contended that the
95 percent efficiency requirement is not achievable on a continuous basis due
to the inherent variability of carbon adsorption systems. They also stated
that ketones, which are commonly used solvents in magnetic tape manufacture,
reduce the performance of carbon adsorbers and increase system variability and
shorten bed life which increases the cost of using carbon adsorption.
In order to respond to these comments, the EPA requested additional
information from manufacturers and users of carbon adsorber systems to further
investigate system performance and costs. The EPA also again reviewed
information obtained from previous studies by the Agency. This report
summarizes the results of this study.
This report is organized as follows. Section 2 presents the conclusions
of this study. Section 3 presents a description of the vapor phase adsorption
process, discusses impacts of changes in inlet vent stream characteristics on
adsorber performance, and presents supporting test data. Section 4 presents a
description of the carbon adsorber system which the commenter used as a basis
for developing their comments, and a discussion of the design and operation of
that system.
1-1
C-23
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2. SUMMARY AND CONCLUSIONS
This report was specifically designed to address comments submitted
concerning the proposed new source performance standards for magnetic tape
manufacture. These comments may be summarized as follows:
• One commenter questioned whether any supporting data exist for the
Agency's position that 95 percent VOC removal efficiency can be
achieved continuously by carbon adsorption systems over all
averaging periods, including short-term periods. The commenter
submitted information indicating that 24-hour averages of efficiency
of his adsorption system vary dramatically from day to day. Days
when the average efficiency was above 95 percent were followed
quickly by days with an average efficiency of less than 90 percent.
It was this information that caused the commenter to question the
Agency's decision to determine compliance and assess adsorber
operation and maintenance based on short-term measurements of
adsorber performance.
e The same commenter also stated that the evaluation of carbon
adsorption to control VOC emissions has not adequately addressed the
problems associated with the use of ketones by the magnetic tape
industry. The commenter submitted data that, in the commenter's
opinion, demonstrated reduced adsorber efficiency caused by the use
of ketones. The commenter also implied that the variability in
carbon adsorber performance is greater when ketones are present in
the solvent laden air stream and that ketones shorten the useful
life of the carbon 1n adsorption systems, resulting in greater cost
impacts attributable to the NSPS than indicated by the cost analysis
carried out by EPA prior to proposal.
In order to address these comments, Information was requested from a
number of sources. These included both magnetic tape manufacturers and other
types of coating operations using carbon adsorbers to control VOC emissions.
A meeting was also held with representatives of a major supplier of activated
carbon to obtain their perspective on proper adsorber system design and
operation based on their long term experience in this field. In addition, two
sites were visited to obtain first hand Information on the operation of carbon
adsorber systems. Emission test data from 15 tests performed for the Emission
Standards Oivision of EPA and the Office of Research and Development were also
reviewed to provide additional substantiation of adsorber performance and to
attempt to compare long- and short-term removal efficiency.
Preceding page blank
-------
Based on the data collected for this study, the following conclusions
have been made.
e When the carbon adsorber system 1s properly designed and operated,
the adsorptlon/desorptlon process 1s predictable and reproducible
from cycle to cycle.
e For well designed and operated carbon adsorber systems, continuous
VOC removal efficiencies of over 9S percent are achievable over
long- and short-term periods for a variety of solvents, including
mixtures that contain ketones such as methyl ethyl ketone (MEK) and
cyclohexanone. Several plants have been shown to continuously
achieve removal efficiencies of 97-99 percent.
e All facilities Identified by this study which had removal
efficiencies below 95 percent had Identifiable operational problems
which contributed to their poor performance. All of the operational
problems identified were correctable.
p
• A carbon adsorption system must be designed based on the following
process parameters: 1) particular solvent or solvent blend being
recovered, 2) solvent load, 3) vent stream flowrate, and 4) vent
stream temperature. Assuming the initial design provides sufficient
capacity to account for normal dally process variations and the
adsorber 1s properly operated, the performance of a carbon adsorber
system will be essentially constant from cycle to cycle, and
long-term and short-term efficiency will be the same.
e If a carbon adsorber bed 1s left on-Hne after breakthrough,
adsorber efficiency will be significantly reduced and may also
become much more variable. A key to maintaining high continuous
removal efficiencies is to detect breakthrough and bring a fresh bed
on-line. There should always be a fresh bed available if the system
is properly designed and operated.
e Because continuous high removal efficiency can be achieved by a
properly designed and operated carbon adsorber system, short-term
performance testing and monitoring requirements are appropriate as
long as the complete system cycle 1s Included in the test or
monitoring period.
e A consensus of carbon suppliers, carbon adsorption system vendors,
and carbon adsorption system operators indicates that when
cyclohexanone is adsorbed, 1t exothermally reacts on the carbon
surface to form higher molecular weight products which cannot be
removed by normal steam desorption. The subsequent build up of
these compounds results in a steady decrease in the adsorptive
capacity of the carbon. This loss 1n adsorptive capacity decreases
the time which a carbon bed can remain on-Hne before breakthrough
occurs. When the adsorption cycle time approaches the time requirec
C-26
2-2
-------
for off-line bed regeneration and proper cool down, the carbon must
bt replaced. If the carbon 1s not replaced the point will be
reached where the operator will be forced to either: 1) leave the
bed on-Hne past breakthrough in order to properly regenerate the
off-line bed or 2) switch to the regenerating bed before it has been
adequately steamed and cooled. The result in either case will be a
dramatic drop in removal efficiency.
The carbon adsorber system of which the commenter reported as having
highly variable and frequently low removal efficiencies is
significantly under-designed for the actual solvent loading it is
required to control. This results 1n the system being operated a
significant portion of the time after breakthrough has occurred. As
a result, the efficiency of this system 1s extremely sensitive to
variations in the process conditions and therefore exhibits
significant variations in efficiency from day-to-day and
cycle to cycle. The variations also result in significantly reduced
long-term efficiency. If the system was operated, within the design
limits, then the reduced efficiency and efficiency variation should
not occur.
As a carbon bed ages and Its total adsorptlve^capacity- gradually
decreases due to fouling, the working capacity can in some cases be
maintained at the desired level by increasing the steam flow during
desorption. This will increase steam.costs. The decision of
whether to use higher steam flow or replace the carbon is based on
the cost of additional steam versus the cost of new carbon.
A key parameter to maintaining continuously high removal efficiency
is replacing the carbon well before fouling reduces the adsorptive
capcity. More frequent carbon replacement results in higher
annualized carbon costs, but also prevents reaching the point where
th§ adsorber performance falls below the design value.
2-3
C-27
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3. THEORY AND PERFORMANCE OF CONVENTIONAL FIXED BED CARBON ADSORBERS
This section presents a general description of carbon adsorbers used to
remove volatile organic compounds (VOC) from a gaseous process stream. The
purpose of this presentation 1s to provide Information necessary to draw
conclusions concerning the following:
• The ability of carbon adsorbers to remove 95 percent or more of the
VOC in a process stream on both a short-term and long-term basis;
• the effect of various operating parameters such as solvent type, bed
age, inlet stream temperature, concentration, flowrate, and
regeneration steam flow on adsorber performance.
The information presented here was obtained from Industry and vendor responses
to information requests from EPA, evaluation of carbon adsorber emission test
data gathered for this and previous EPA studies, and a meeting with a major
vendor of activated carbon and carbon adsorption/Incineration systems.
The first part of this section is a discussion of the basic theory of
carbon adsorption (Section 3.1). Section 3.2 describes the design
considerations for full scale systems, Section 3.3 presents a discussion of
how adsorber efficiency is calculated, and Section 3.4 presents the impact of
operating variables on system performance. Section 3.5 presents emission test
data to substantiate the performance of carbon adsorbers. Finally Section 3.5
presents conclusions concerning carbon adsorber performance.
3.1 MECHANISM OF A0S0RPTI0N ANO OESORPTION
This section presents a detailed description of the mechanisms of carbon
adsorption and desorptlon. To describe the mechanisms Involved, a simplified
approach using a single bed of activated carbon is developed. The principles
involved 1n the single bed system are then applied to describe the operation
of a typical carbon adsorber system.
For gas phase carbon adsorption applications, the adsorber system does
not actually recover the VOC. It 1s used to transfer the VOC from a medium
where it 1s difficult to recover (the vent stream gas), to a more
concentrated form in a different medium (usually steam) where the VOC can be
more easily recovered. This transfer occurs 1n two steps. The first is the
Preceding page blank
3-1
C-29
-------
adsorption step where the VOC (adsorbate) 1s adsorbed onto the surface of
activated carbon (adsorbent). The second step 1s where the adsorbate is
removed from the carbon (desorptlon) and recovered for reuse. Both of these
steps are equally Important In the overall process.
The adsorption process can be either physical or chemical. In physical
adsorption the organic molecule Is held to the surface by weak van der Waal
type forces or Intermolecular cohesion.* The chemical nature of the adsorbed
gas remains unchanged, thus the process 1s. readily reversible. Regenerative
pollution control equipment requires the adsorption process be physical. In
chemical adsorption, electrons are exchanged thus chemically bonding the
molecule to the surface of the carbon particle.^ Chemical adsorption is not
readily reversible and, therefore, is not suitable for the regenerative
adsorber systems used in air pollution control applications.^
Figure 3-1 presents a series of exploded views which describe the
subsystems which make up a carbon adsorber bed. A carbon bed is comprised of
carbon pellets. The pellets are made up of carbon particles which have been
sintered together. The carbon used in adsorption is made by a two step
process. In the first, material from various sources such as coconut shells,
petroleum products, wood and coal 1s carbonized by heating it in the absence
of air until all organic compounds except the carbon are volatilized. Then
using high temperature steam, air, or carbon dioxide, the carbon is made
4
porous or activated. Oepending upon the extent of this process and the
original source, the carbon can be made to fit the use for which it is
desired.
The pore structure within a carbon particle is Illustrated in Figure 3
The external surface area of a carbon particle is a few square meters per
gram; however, within the pores the available surface area is hundreds of
square meters per gram.*
The pores within the carbon are classified according to their size.
Large pores (greater than 2,000 nanometers in diameter) are called macropores
and smaller pores (less than 200 nanometers) are called micropores.6 Pores
with diameters between these ranges are called transitional pores.7
Micropores are where the majority of the adsorption occurs so it is desirable
O
to have a large amount of the pore space 1n this form.
C-30
3-2
-------
Carbon Pellets in
Cross Section of Carbon Bad
Carbon Pellet
Sppilip
Carbon Particle
• O
i
Figure 3-1. Representation of Carbon Pellets/Particles in Carbon Bed
3-3
C-31
-------
anoiwi
32
3-4
-------
Th« adsorption process begins with the mechanical movement of the vent
stream through the carbon bed, which brings the organic molecules Into contact
with the carbon pellets. The remainder of the adsorption process consists of
three steps as illustrated 1n Figure 3-3. The adsorbate must first diffuse
Into the carbon pellet to the surface of the carbon particle. Next, the
adsorbate molecule must diffuse from the surface Into the pores within the
carbon particle. The extent of the diffusion within the pores 1s dependent on
the size of the molecules and the pore structure of the carbon. (Diffusion
into the larger pores occurs fairly rapidly, but as the pore diameters become
smaller the diffusing molecule strikes the walls and sticks for short periods
Q
of time. This diffusion process continues until the molecule reaches a
location where 1t no longer has sufficient energy to escape the forces which
hold it to the pore wall. This usually occurs where the pore diameter is not
10
more than approximately twice the diameter of the adsorbate molecule.
The adsorption process continues until the amount of adsorbate on the
carbon reaches a thermodynamic equilibrium with the adsorbate in the gas
phase. The thermodynamic equilibrium is a function of the carbon type,
temperature of the carbon and adsorbate, and the adsorbate partial pressure
(concentration) in the vent stream. The amount of adsorbate a particular
carbon can hold 1s called the equilibrium capacity.
As previously mentioned, the purpose of the carbon adsorber is to
actually transfer the adsorbate from the gas stream to a medium where it can
more easily be recovered or disposed of. Therefore, at some point the
adsorbate must be removed froei the carbon. This process is called desorption
or regeneration. Desorption 1s accomplished by shifting the thermodynamic
equilibrium established during the adsorption step. There are three ways to
shift the equilibrium: 1) Increase the temperature, which is usually brought
about by the addition of steam, 2) reduce the pressure of the atmosphere
surrounding the carbon, and 3) reduce the concentration in the gas stream
outside the carbon to a value less than the concentration inside the carbon.
In most air pollution control applications, Increasing the temperature is used
for desorption.
During desorption some adsorbed molecules are not removed. The reason is
that to remove all the adsorbate requires sufficient time for the adsorbate
3-5
C-33
-------
utioioni
jf,, . j* -' S. ,\JK5r
V •*.•<>• .•v.-.W-'
'^jai^aww
C-34
3-6
-------
molecules to diffuse out of the carbon particle, and that the temperature be
high enough to cause all the adsorbate to desorb. However, the energy cost to
accomplish this 1s higher than the cost to leave some adsorbate in the carbon
and use a larger amount of carbon to achieve the desired system performance.
Adsorbate remaining in the carbon after desorption is called the heel.
The amount of heel is a function of the desorption time and temperature.
Increasing adsorption time and/or temperature will reduce the heel. In virgin
carbon, a stable heel is established after two to three adsorption/ desorption
cycles.^
The process discussed above 1s summarized by the simplified
representation of a carbon pore shown in Figure 3-4. As shown, the pore has
three different volumes: the equilibrium capacity, working capacity, and the
12
heel. As previously discussed, the equilibrium capacity is a function of
the carbon type, bed temperature, and the partial pressure of the adsorbate in
the vent stream. It represents the maximum amount of adsorbate which can be
adsorbed by the carbon when it is at equilibrium with the surrounding
conditions. The heel represents the adsorbate which remains in the pore after
desorption. It is a function of the particular carbon, the adsorbates in the
vent stream, and the steaming conditions.
The practical application of the adsorption process to a full size carbon
bed is illustrated in Figure 3-5. In this figure, the solvent laden air (SLA)
flows from left to right. As shown, there are three zones in the bed labeled
saturated, mass transfer, and fresh. The saturated zone is located at the
entrance to the bed and represents the carbon which has already adsorbed its
working capacity of adsorbate. The saturated carbon 1s at thermodynamic
equilibrium with the Incoming vent stream. Therefore, no net mass transfer
occurs 1n this zone. The mass transfer zone (MTZ) is the section of the
carbon bed where the adsorbate 1s removed from the carrier stream. The carbon
1n this zone 1s at various degrees of saturation, but is still able to adsorb
some adsorbate. For a typical system, the mass transfer occurs within a
section approximately three inches 1n depth.^ The fresh zone is downstream
of the mass transfer zone and represents the region of the bed where no new
adsorbate has passed since the last regeneration. This zone still has all its
working capacity (i.e., equilibrium capacity minus the heel) available.
3-7
C-35
-------
A m Residual or Haal (located daap in tha port and difficult to dislodge)
B m Working Capacity (boundad by tha haai remaining from pravioua cyclaa and portion of pore
too larga In diameter to ratain organic)
C * Equilibrium Capacity
3
Figure 3-4. Simplified Representation of Carbon Capacity11 1
C-36
3-8
-------
SLA Flow
100%
% Of Total Equllbrlum
Capacity Available
Freah
Saturated
Zona
Heel
Remaining
Working
Capacity
-4 Maaa
Tranaler Zone
Olatance Through Bed
Figure 3*5. Available Working Capacity as a Function of Distance
Through Bed lor an Operating Bed
-------
During operation the mass transfer zone moves down the bed in the direction of
flow. Breakthrough occurs when the mass transfer zone first reaches the bed
outlet. The breakthrough point is characterized by the beginning of a sharp
increase in the outlet concentration. The available adsorption time for a
specific bed before breakthrough occurs 1s a function of the amount of carbon
present, Its working capacity, and the concentration and mass flowrate of
adsorbate.
Figure 3-6 shows a simplified representation of the carbon pores in each
of the three zones. Pores A through E represent typical pores at different
locations in the bed. Pore A, which 1s at the front of the bed, is already
completely saturated while Pore E, which has not been exposed to adsorbate
during this cycle, still retains its entire working capacity. Pores 8, C, and
0 which are located 1n the MTZ, depict various degrees of saturation. A cross
section of the bed perpendicular to the air flow will reveal pores at similar
levels of saturation. In the MTZ, pore B has been exposed to the adsorbate
for the longest period of time and is nearly saturated while the MTZ has just'
reached pore 0 which still retains most of Its adsorptive capacity. As the
adsorption cycle continues and more adsorbate enters the bed, the mass
transfer zone will continue to move through the bed.
Figure 3-7 depicts the VOC concentration within the carrier gas as a
function of axial distance down the bed. Since equilibrium has been reached
with the incoming adsorbate 1n the region prior to the mass transfer zone, the
vapor stream concentration 1s equal to the inlet concentration. Within the
mass transfer zone, the concentration of the vapor stream drops off because
the organic 1s being adsorbed Into the pores.
14
Theoretically, the concentration 1n the third zone should be zero.
However, a small amount of adsorbate Is typically present. This is a result
of two factors:
1. A small amount of SLA may pass through the adsorber without actually
contacting the carbon.
2. Due to the low concentration of adsorbate in the vent stream in the
last few Inches of the bed, the heel remaining from the previous
cycle will slowly desorb.
C-38
3-10
-------
SLA Flow i
Saturated Zona
MTZ
Freeh Zona
A
BCD
E
S
n n n
S
4
3
Saturated Zona
^ almost all
working capacity
consumed
Freeh Zona
V
working
capacity
consumed
S'S/i
^ half of working
capacity consumed
y
^ all working
capacity availabt*
almost all working
capacity available
c
3
i
Figure 3-6. Simplified Pore Representation of Capacity as a Function of
Distance Through Bed
3-11
C-39
-------
Vapor Stream
Concentration
(Pfxn)
SLA Flow i
Inlet Concanlratlon
Concentration
/
| Masa
Tranalar Zona'
Exit
Concentration
Oiatanca Through Bad
Figure 3-7. Vapor Stream Concentration as a Function of
Distance Through Bed
-------
Test results on full scale systems have shown outlet concentrations as low
as 0.5 pp«.** This outlet concentration can be minimized by proper system
design, as discussed in the next section.
The breakthrough curve, which 1s the outlet concentration as a function
of time, is a mirror image of the concentration profile in the mass transfer
zone. As the mass transfer zone reaches the end of the bed, the outlet
concentration rises. This will continue until the outlet equals the inlet
concentration.
3.2 FULL SCALE ADSORPTION SYSTEMS
This section describes full scale adsorption system design and
operation. The basic mechanisms were previously described in Section 3.1.
Section 3.2.1 presents an overview of the adsorber system. Section 3.2.2
discusses specific design considerations for a full scale system.
3.2.1 System Overview
The process flow diagram for a typical two bed carbon adsorber system
is shown in Figure 3-8. The adsorber system can be broken down into three
separate sections; pretreatment, carbon adsorber, and recovery/waste
treatment. The vent stream containing the adsorbate enters the adsorption
system via the pretreatment section. If the vent stream is above the
maximum design temperature it is reduced within the pretreatment section,
usually with a heat exchanger. In addition, a filter is included in the
pretreatment section to remove any particulate present in the vent stream.
From the pretreatment section, the vent stream enters the adsorber.
Figure 3-8 depicts a two bed adsorber system. In order to provide
continuous emission control, at least two adsorber beds are needed so that
one 1s on-Hne while the other 1s regenerated. Adsorber systems with three or
more beds are operated similarly. During operation, the organic-laden vent
stream passes through the on-line bed for a predetermined time period or
until breakthrough occurs. The on-Hne bed is then taken off-line for
regeneration (desorptlon) and the other bed 1s brought on-line.
Regeneration of the off-line bed 1s usually accomplished by passing
steam through the bed countercurrent to the direction of vent stream flow.
The steam which 1s Injected into the bed serves several purposes; 1) it
3-13
C-41
-------
Eahaual
V«nl
/ \
Ait Mate
lot CooHnolOtytna
FUI«
Si Mm
Figure 3-®. Carbon Adsorber
System Process
F8ow Diagram
m
§
r*
a
w
-------
provides the energy to raise and hold the bed at an elevated temperature,
2) It provides the energy required to desorb the adsorbate from the carbon,
and 3) 1t carries the desorbed adsorbate from the bed. The steam Is condensed
and then decanted. There are two liquid phases present 1n the decanter, the
aqueous and organic. The organic phase is generally recovered for reuse. The
aqueous phase is either disposed of or, if the level of organics is high,
treated prior to disposal. After the desorption step, the bed is sometimes
dried using heated air. However, this 1s not required in most cases because
removing water from the carbon usually has little effect on the adsorption
process. In fact, the moisture left on the bed can be beneficial because it
acts as a heat sink during the adsorption process.1®
Finally, the regenerated bed is then cooled by passing ambient air
through it. In a well designed system both cooling and drying are performed
with the air flow countercurrent to the direction of flow when the adsorber is
on-line. The air exiting the regenerating bed is directed through the on-line
bed to remove any trace adsorbate.
3.2.2 Full Scale System Design Considerations
Section 3.2.1 discussed the overall adsorption system. This section
focuses on the design of the adsorber section itself. Both the physical
system design and the system control and operation during adsorption and
desorption are important 1n order to achieve high removal efficiencies on a
continuous basis.
The design of full scale carbon adsorption systems begins with a
determination of the inlet stream characteristics. The characteristics
which may be important are:
e Specific compound(s) present;
e flowrate and temperature (range and average);
e adsorbate concentration (range and average; and
e relative humidity.
Any commercial activated carbon should be capable of providing acceptable
performance 1f the system 1s designed based on that particular carbon.
However, selecting a carbon which has a majority of micropores which are
3-15
C-43
-------
smaller than approximately twice the diameter of the adsorbate molecules, Mill
result In the greatest adsorptlve forces.17
Once the carbon has been selected, the required bed area is calculated
based on the desired superficial velocity. For a specified flowrate, the bed
area determines the superficial velocity of the vent stream through the bed.
The lower limit of superficial velocity is 20 ft/min to insure proper air
18
distribution. The upper limit is usually 100 ft/min. This upper limit is
to keep bed pressure drops within the discharge head capacities of the types
of fans used in these applications, and to avoid excessively high system power
costs. Typical superficial velocities are based on vendor experience and the
results of pilot scale testing and will usually be between 50 and 100 ft/min.
19
Generally, carbon adsorber bed depths range from l.S to 3.0 feet. A
bed depth of at least 1.5 feet is used to Insure that the bed 1s substantially
20
deeper than the MTZ, which is normally three Inches deep. If the MTZ is
longer than the bed, breakthrough will occur almost Immediately. The maximum
bed depth of three feet is based on keeping system pressure drop within
reasonable limits.
Within the constraints discussed above determination of the bed depth
becomes a function of the volume of carbon required for one adsorption cycle.
The minimum volume of carbon is determined by the solvent mass loading, the
carbon's working capacity, carbon density, and the desired available
adsorption time. The solvent mass loading and carbon density are fixed by the
stream being treated and the choices of carbon, respectively. The working
capacity and available adsorption time are interrelated and are determined by
the particular carbon, design temperature, adsorbate concentration, specific
compounds present, superficial velocity, and regeneration parameters. The
available adsorption time as a minimum must be greater than the time required
to regenerate (steam and cool) the off-line bed(s).
If the adsorbate contains multiple organic compounds, interactions
between those compounds must also be considered in the estimation of working
capacity. More strongly adsorbed compounds displace the less strongly
adsorbed and push them through the bed.** This creates a wave front of the
lower molecular weight compounds (which tend to be the compounds less strongly
C-44
3-16
-------
adsorbed) at the front of the MTZ. The phenomenon must be accounted for in
estimating the system design working capacity to Insure that breakthrough of
any of the compounds does not occur.
At this point it is necessary to determine the working capacity and
specify an adsorption time to determine the carbon volume. Empirical data
from pilot scale testing are usually required to accurately determine working
capacity for a specified set of inlet conditions, Superficial velocity, and
desorption steam flow. However, the desorptlon steam flow selected, in turn,
affects the working capacity and the minimum required adsorption time. The
economic trade-offs of system capital costs versus steam costs will determine
what set of regeneration conditions will result in the lowest annual co'.'s.
Steaming requirements are set as part of the initial system design. The
longer the bed steaming time the greater the amount of adsorbate removed, and
therefore the smaller the amount of removable heel remaining. As previously
discussed, the working capacity of a carbon bed, which 1s the amount of
adsorbate the bed can remove during an adsorption cycle, is the difference
between the heel and the equilibrium capacity. Therefore, the longer the bed
is steamed, the greater the available working capacity. An example of the
relationship of working capacity versus steam consumption for three compounds
22
is shown in Figure 3-9; The shape of this curve 1s similar for most
compounds. However, specific values of working capacity versus steam /low
vary from compound to compound. The curve usually begins to flatten out at
some steam consumption. Increasing steam use beyond the point where the curve
begins to flatten out will result In only a small increase 1n working
capacity.
In well designed systems the bed 1s steamed countercurrent to the
23
direction of flow during adsorption. This will help minimize the adsorbate
emitted at the adsorber outlet prior to breakthrough. Figure 3-10, which is a
plot of the adsorbate concentration left on the bed after steaming as a
function of axial distance through the bed, Illustrates why this is true.
After steaming, the concentration of adsorbate (I.e., the amount of heel which
remains) Is lower at the end of the bed where the steam enters. When the
adsorber 1s brought on-Hne, the lower amount of heel where the SLA exits the
bed means less adsorbate 1s available to desorb. Also, having more working
3-17
C-45
-------
0
1
o\
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oo
u
£ C
O 3
«g O
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P
£ 2
o5
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XJ
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Elhylacelat*
Cyclohexanone
Pounds of Steam per Pound of Desorbed Hydrocarbons
Figure 3-9. Steam Consumption versus Working Capacities
-------
Olfaction of Adsorption Air Flow c>
<1 Direction ol Steam Flow
Adsortoale *
Left on A
Bed Alter ¦
Steaming
Meet
Distance Through Bed
Figure 3-10. Adsorbate Concentration in Bed After Steaming Countercurrentiy
as a Function of Distance Through Bed
-------
capacity available at the bed exit helps prevent momentary increases in outlet
concentration as a result of changes 1n Inlet conditions caused by process
upsets. If the bed is steamed cocurrent to the direction of flow during
adsorption, the reverse heel profile exists and a higher outlet concentrations
will result.
Another consideration in adsorber design 1s fouling. Fouling occurs when
compounds are present in the vent stream which will not desorb from the bed.
These compounds can be solid particles* high molecular weight compounds, or
compounds which chemically react on the surface of the carbon (such as some
ketones). Regardless of the source, bed fouling gradually reduces the carbon
adsorption capacity.
There are two methods to compensate for fouling. One is to increase
volume of carbon beyond the minimum required to achieve the desired adsorption
time. The second is to gradually increase the amount of steam used to
regenerate the bed. Increasing the steam used in regeneration reduces the
heel, which helps maintain sufficient working capacity. A combination of
these methods can also be used.
A typical adsorption/desorption cycling arrangement for a two bed
adsorber system is shown in Figure 3-11. For the purpose of discussion,
illustrative times are shown on the figure corresponding to operational
aspects of the system. The sequence begins with bed 1 coming on-line as bed Z
; goes off-line at t^.-PFor'tftf example shown, adsorption lasts 90 minutes, the
. steaming time is fixed at finutei,. and the cooling/drying time is also
30 minutes. The off-line bed"has 30 minutes during which it is on standby.
In this example, the 30 aTniites of standby time allows the operator to
compensate any dally variations in vent stream conditions and bed fouling
without having to leave a bed on-line after breakthrough. It is important
that a bed not be left on-line after breakthrough because that will
significantly reduce the overall removal efficiency for that cycle.
Two types of trigger mechanisms are used for controlling the adsorption/
desorptlon cycles: continuous monitors and timers. Continuous monitors take
a bed off-line when a specified outlet concentration 1s reached. Timers cycle
the bed at a specified time. A combination may also be used. One advantage
to using continuous monitors is that they allow the beds to remain on-line
C-48
3-20
-------
Regeneration
Bad it / *»' \
| MmplkHi ^ | Sfamlnflj Drying j Stand-By | Adaorplton ^
0 30 90 I
(mln)
0 30 60 90 120 150 180 210 240 270
TlfM
Regeneration Regeneration
Bad #2 / * \ t i v
IStaamlnfli Orylno i 8tand-By « Adsorption i Slaamlng. Drying . Stand-By i
1 | j j j J | | |
~ 0 30 60 00 120 150 180 210 240 270
Tlma
(mln)
r>
* i
vo 5
Figure 3-11. Adsorption/Desorption Cycles in a 2 Bed System ?
-------
until breakthrough, thus fully utilizing their capacity during each cycle.
This 1s not the case for a timer based system, because to properly guard
against breakthrough allowances must be made for variations in the
breakthrough time due to changes in the inlet stream characteristics.
Although continuous monitors allow for the use of more of the available
adsorption capacity than timers, do, timers can be used in many situations as
the trigger mechanism. They are especially appropriate for adsorbates which
do not foul the bed or where inlet stream characteristics are very stable, [f
a timer 1s used, continuous monitors or a periodic sampling program should be
used to adjust the adsorption times as necessary. Oevlations in operating
conditions do not affect properly designed systems which use timers unless the
conditions exceed the range of the design specifications. If this is allowed
to occur, a bed may be kept on-Hne after breakthrough has occurred, This
would result in a significantly reduced removal efficiency.
A final, and important, consideration 1n system design is prevention of
channeling. Channeling occurs when a portion of the SLA bypasses the bed, or
a certain section of the bed receives a greater portion of the flow than other
sections. The inlet of the vessel must be designed to achieve proper
distribution of the SLA so that 1t does not impinge on a portion of the bed at
high velocity. The potential for channeling can be minimized by the use of
distribution baffles. It is also important to achieve proper distribution of
the regeneration steam. If steam is not well distributed the steam flow can
also cause channels to form in the bed. Also, poor steam distribution will
result in some portion of the bed not being properly regenerated.
Proper design can minimize the potential for channeling. However,
maintenance of the distribution baffles and steam distribution system should
be performed during scheduled system shutdowns or whenever an increase is
detected 1n the adsorber outlet VOC concentration which is significant enough
to result 1n a removal efficiency below the minimum design level.
3.3 CARBON AOSORBER LONG- ANO SHORT-TERM EFFICIENCY
This section discusses the relationship of long and short-term carbon
adsorber efficiency. Section 3.3.1 discusses the calculation of instantaneous
C-50
3-22
-------
versus cycle efficiency. Section 3.3.2 discusses the variability of
short-tern efficiency. Section 3.3.3 discusses the relationship of outlet
concentration and efficiency.
3.3.1 Calculation of Carbon Adsorber Efficiency
In order to discuss carbon adsorber long- and short-term efficiency, a
short discussion of the relationship of efficiency to the Inlet and outlet
concentrations over time is necessary.
The Inlet and outlet concentration as a function of time for a single
adsorption cycle of a typical carbon adsorber is shown 1n Figure 3-12. The
outlet concentration curve is also called the breakthrough curve. For the
example shown, the inlet concentration is and the outlet concentration is
CQ. The adsorber was brought on-line at tQ and taken off-line at t2 when the
outlet concentration reached some predetermined set point concentration level.
At any point in time the instantaneous removal efficiency (IRE) for this
adsorber is determined as the difference between the Inlet and outlet
concentration divided by the inlet concentration. At time tj the
instantaneous removal efficiency is:
The overall removal efficiency (ORE) at any given time during the cycle is
determined by the difference between the areas under the inlet and outlet
curves divided by the area under the outlet curve. For the adsorber shown
in Figures 3-12 at time tj the overall removal efficiency is:
ORE, - Area fADEFl - Area fBCEFl
1 Area (ADEF)
As an exaaple, 1n the magnetic tape manufacturing industry a typical inlet
concentration might be 3000 ppmv and a typical outlet concentration might be
24
30 ppmv or less prior to breakthrough. To achieve a 95 percent removal
efficiency over the period of an adsorption cycle a system with an inlet
concentration of 3,000 ppm mist have a tine weighted average outlet
concentration of 150 ppm or less. At an outlet concentration of 30 ppmv the
removal efficiency 1s 99 percent for most of the cycle. Therefore, when
breakthrough occurs the outlet concentration can rise above the 150 ppm point
3-23
C-51
-------
0
1
ut
fo
C, -
gj
rvj
C
o
CM-
Removal Efficiency at I.
Instantaneous •
C/ = Inlet Concentration
C# = Outlet Concentration
= Set Point Concentration
c. -
B
C
F
~1
I.
Time
a
Figure 3-12. Determination oH Carbon Adsorber Removal Efficiency
-------
without the overall removal efficiency going below of the required 95 percent.
Therefore, for a system designed and operated to maintain a certain minimum
Instantaneous removal efficiency, the cycle efficiency will be higher than the
Instantaneous efficiency. At one site the cycling set point for their system
is 2 hours or whenever the instantaneous removal efficiency reaches
95 percent. The result 1s an overall removal efficiency greater than
25
99 percent.
3.3.2 Variability of Short-Term Removal Efficiency
A significant issue raised is the variability of short-term carbon
adsorber removal efficiency. Assuming that Inlet stream characteristics never
vary, and the adsorber is always operated the same way, cycle efficiencies
26
should be almost Identical. The only change expected would be a gradual
decrease in carbon working capacity due to bed aging. However, the change in
performance from one cycle to the next due to bed aging will be insignificant.
However, 1n actual applications, inlet stream characteristics such as
concentration, temperature, and flowrate may vary. Also, the operator may
make deliberate changes in the solvent being adsorbed, or in system operation.
If for a well designed and operated system it can be shown that changes in
inlet stream characteristics or operation do not significantly affect
cycle-to-cycle efficiency, then the short-term removal efficiency can be
expected to be essentially constant for industrial applications. These
evaluations are shown 1n Section 3-4.
3.3.3 Relationship of Outlet Concentration and Efficiency
A typical plot of Inlet and outlet concentrations versus time for a
carbon adsorber was previously presented 1n Figure 3-12. Figure 3-13 presents
a similar curve for the outlet concentration only. In this example Y
represents the outlet concentration at the beginning of the cycle. At the
breakthrough time the outlet concentration begins a sharp increase. At this
time a fresh bed should be put on-Hne, and the other bed which has just
broken through regenerated.
The dashed line represents what happens if the operator does not remove
the bed which has broken through from service. The outlet concentration will
Increase until 1t equals the adsorber inlet concentration, which in this
example is X.
3-25
C-53
-------
Point where bed should
Im taken off-line.
X-
XL
T.
I
A iL
<5 ,
Outlet concentration curve
which reeuits if bed is not
taken offline at breakthrough.
1 krwmMdkrmttk
Time
C-54
Figure 3-13. Typical Carbon Adsorption Breakthrough Curve
3-26
-------
Also shown 1n this figure are arrows labeled "A" and "B". These arrows
represent the two possible shifts in the breakthrough curve which could occur.
The shift labeled "A" indicates a decrease 1n the adsorption cycle time prior
to breakthrough. A shift of this type normally should have little effect on
the efficiency of the adsorber, because the bed can be taken off-line for
regeneration prior to the release of any significant emissions. A slight
efficiency reduction over multiple cycles will occur because breakthrough will
occur more frequently. The magnitude of the efficiency change, however, will
be very smal1.
A shift of the A type will significantly affect efficiency if a bed is
left on-line after breakthrough. There are three possible reasons for a bed
to be left on-line after breakthrough.
1. The operator may not be aware of how quickly the concentration rises
after breakthrough and the resulting deleterious effect on the
efficiency of his adsorption system.
2. The operator may have no way of knowing when breakthrough occurs
(suitable analytical instruments have not been installed).
3. The operator may not have a replacement bed properly desorbed and
cooled, ready for service.
The first two reasons are operational problems and easily overcome. The
third should not occur if the system was designed properly and is being
operated within the design specifications, and the carbon is replaced when
necessary.
If beds are left on-Hne after breakthrough removal efficiencies will
also become much norc variable. As an example, assume that the adsorber
system discussed 1n Section 3.3.1 has a three hour adsorption time at which
point breakthrough occurs, a 3,000 ppmv inlet concentration, and a 30 ppmv
outlet concentration. Oue to a process change the inlet concentration of VOC
now increases to 3,500 ppov occasionally and this variability was not
accounted for 1n the system design. In this case, breakthrough would now
occur approximately 26 minutes earlier. If the operator does not take the bed
off-line at this tine, the outlet concentration increases very quickly to
3,500 ppm, and for that cycle the adsorber efficiency will be reduced to
approximately 85 percent. If the inlet concentration varies from 3,000 to
3-27
C-55
-------
3,500 pp« on a dally basis, then the adsorber removal efficiency will also
vary from 99 to 85 percent on a daily basis. This example demonstrates that
if the system is not designed to account for normal process variations,
efficiency will both be reduced, and become much more variable than is
normally the case with well designed and operated systems.
The shift "8" indicates an increase in the baseline outlet concentration
prior to breakthrough. A shift of this type could result in a significant
decrease in the removal efficiency achievable by the adsorber depending on the
inlet concentration and the magnitude of the outlet concentration change.
For the purpose of this analysis, it is important to understand the two
potential shifts in the breakthrough curve relative to the adsorption
mechanism itself. Assuming a constant adsorbate loading rate, a shift of type
"A" indicates a change in the working capacity of the carbon .for a given
adsorbate. The working capacity is a function of fouling and the equilibrium
conditions (i.e., temperature, pressure, and partial pressure of the
adsorbate) for a particular set of operating conditions (i.e., steaming time,
temperature, and duration). Therefore, changes in the equilibrium conditions
which effect the working capacity lead to type "A" shifts in the breakthrough
curve.
A shift of type "B" indicates one of two possibilities: 1) A portion of
the inlet stream has bypassed the bed by either short circuiting or channeling
(as previously discussed, channeling can be avoided with proper design and
maintenance). 2) A greater amount of heel is present in the last few inches
of the carbon bed. As stated previously, the amount of heel is a function of
the conditions which are established at the end of the steaming cycle. The
amount of heel related to the steaming time, temperature, and flow.
Each of the potential operational variables for a carbon adsorber is
evaluated in the next section relative to its ability to shift the
breakthrough curve of Figure 3-13 in either the "A" or "B" direction. Proper
operation practices necessary to prevent degradation of the adsorber system
are also discussed where appropriate. The results from this evaluation are
then used to determine the effect on the removal efficiency which is
C-56
3-28
-------
achievable by the system. In presenting this discussion, data and Information
available from Industry, vendors and emission test reports are used where
available.
3.4 EFFECT OF OPERATING VARIABLES ON ADSORBER PERFORMANCE
The objective of this section 1s to determine 1f the normal expected
day-to-day process variations would be expected to necessarily cause daily
variations In carbon adsorber performance. Also assessed are Impacts of
deliberate process changes, such as a change 1n solvent, on adsorber
performance. Potential dally operating variables Include the operating
temperature, Inlet adsorbate concentration, humidity, volumetric flowrate, and
bed fouling. Changes from the Initial design operating conditions include the
adsorbate types(s), and steaming conditions. Channeling will also be
discussed.
Each of the daily normal operational variables 1s evaluated relative to
Its effect on the breakthrough curve from a typical carbon adsorber bed. For
the purpose of this discussion, the assumption 1s made that any affect on the
performance of a single bed may be taken as representative of the effect on
the overall adsorber system's performance.
3.4.1 Temperature
The operating temperature of an adsorber can be affected in three ways:
changes in the Inlet stream temperature, exothermic chemical reactions taking
place inside the adsorber, or failure of the cooling step after regeneration.
Changes 1n the Inlet stream's temperature lead to changes in the adsorber
operating temperature. Changes 1n the Inlet solvent loading can change the
rate of heat generation due to the heat of adsorption. Heat can also be
generated within the system from chemical reactions taking place on the bed.
Ketones 1n particular, have been Identified by several studies as particularly
27
reactive compounds. The problem is usually not serious, however, unless the
concentration of adsorbate Is extremely high, the gas flowrate through the
carbon 1s relatively low, and the carbon 1s dry and contains no heel.
Each of the possible scenarios given above results 1n a variation in the
temperature at which the adsorption process takes place. Therefore, the
effect of temperature on the breakthrough curve must be evaluated. As
3-29
C-57
-------
previously discussed, the two possible shift directions "A" and "8" can be
assessed by studying the effect of temperature on the working capacity and the
heel, respectively. As shown 1n Figure 3-14, the relationship between carbon
capacity and temperature indicates that as the temperature within the bed
increases, the adsorptlve capacity of the carbon decreases. Thus, as the
temperature increases, the working capacity of the carbon also decreases.
Therefore, a shift in the breakthrough curve is to the left or to shorter
adsorption times. A shift in this direction has no effect on the achievable
removal efficiency but does require a change in the cycle time to compensate
for the shift.
Changes in operating temperature should not cause a B shift in the
breakthrough curve. This is because the outlet concentration at the beginning
of the cycle is primarily a function of the heel remaining in the last few
Inches of the bed. The amount of heel 1s established by the bed steaming
conditions during desorption. Only if the temperature of the carbon in the
adsorber rises to values close to those during, steaming is there a chance the
removable heel will desorb and subsequently-decrease the achievable removal
efficiency.
Temperature fluctuations in the inlet stream can be essentially
eliminated with installation of a heat exchanger upstream of the carbon
adsorber. A properly designed system will not permit the inlet temperature to
exceed the maximum design temperature.
To illustrate the 1nsens1t1vity of carbon adsorber efficiency to minor
changes 1n the bed temperature, the bed temperature and the corresponding
Instantaneous removal efficiencies for an operating adsorber system are
28
presented in Figure 3-15. As shown, the carbon bed temperature varies from
60 to 90°F during the adsorption cycle while the corresponding removal
efficiencies remain well above 99 percent. The outlet VOC concentration
29
remained constant at approximately 20 ppm.
As discussed 1n the section describing the effect of changes in the
adsorbates, ketones are known to exothermlcally polymerize on the carbon bed.
A system designed for ketones must assure the air flow through the bed is
sufficient to remove the heat of reaction to Insure the bed temperature is not
be significantly affected.^0
C-58
3-30
-------
Temperature
o S
• 5
u. 5
* Figure 3-14. Carbon Capacity vs. Temperature at Constant Pressure s
-------
0
1
-------
A properly designed and operated system will limit unacceptable heat
buildup due to reactions 1n the in any of the following ways:
• Thorough steam desorption and cool down,
• use of the maximum superficial velocity to aid in heat removal,
e avoiding prolonged adsorption periods, and
e humidity control or even use of liquid water to act as a heat sink.
When a system 1s designed to handle a ketone*bearing stream, bed temperature
1s normally monitored to detect hot spots and Initiate protective action for
the carbon bed.
3.4.2 Concentration
The concentration of organics in the inlet stream may vary because of
process changes. Short-term variations are those which occur within a given
cycle while long term variations may last over several cycles. Changes can
occur as equipment or product lines are either brought on or taken off-line.
For the purpose of this discussion, the flowrate through the bed is
assumed to remain constant. Therefore, when the concentration increases, the
loading rate to the adsorber increases.
Increasing the concentration will * increase the working capacity of the
carbon. However, the working capacity increase will not be large enough to
completely offset the Increase 1n mass loading. Therefore, the net effect
will be a breakthrough curve shift in the A direction. The effect of
variations 1n Inlet concentration on the outlet concentration prior to
breakthrough should be negligible. As stated previously, the outlet
concentration 1s a function of the heel 1n the last few inches of the bed that
remains after regeneration. Because the inlet stream reaches equilibrium with
the carbon within the mass transfer zone, the amount of heel at the adsorber
outlet is Independent of Inlet concentration. Therefore, short-term
variations in the Inlet concentration will not cause a B shift in the
breakthrough curve.
To Illustrate the Independence of the outlet concentration on short-term
variations in the Inlet concentration, the inlet and outlet concentration and
corresponding removal efficiency for an operating adsorber system are
C-61
3-33
-------
presented 1n Figure 3-16. (GTR Test #6)31 As shown in Figure 3-16 the inlet
concentration varies continuously over the six hour period shown while the
corresponding outlet concentrations and removal efficiencies show little
variation. For Inlet variations between 200 and 550 ppm the outlet
concentration varies only from 5 to IS ppm and the corresponding removal
efficiency varies from 95 to 99 percent.
Figure 3-17 also presents Inlet concentration, outlet concentration, and
the corresponding removal efficiency for a similar performance test conducted
32
on the sane adsorber system discussed above. As shown 1n Figure 3-17, the
outlet concentration (0 to 5 ppm) remains relatively constant for the entire
test period, although the inlet concentration varies from 40 ppm to 880 ppm.
Figure 3-17 also shows the removal efficiency over the test period. Ouring
the majority of the test period the removal efficiency was well above
95 percent. However, when the inlet concentration dropped below 50 ppm, the
removal efficiency was also significantly reduced. This 1s as expected
because carbon adsorbers are essentially constant outlet devices, so a large
decrease in inlet concentration will reduce short-term removal efficiency.
Because the outlet concentration remains constant throughout an
adsorption cycle, large variations 1n the Inlet concentration wilt result in
corresponding variations in removal efficiency. However, if the bed is
properly regenerated, the outlet concentration can be set at a level vfhere
greater than 95 percent removal 1s achieved for the entire range of inlet
concentrations. In addition, in many applications of carbon adsorption, a
reduction 1n Inlet concentration Is the result of equipment (such as coating
lines) being shut down. By diverting or shutting off the air flow from idle
equipment, inlet concentrations can be maintained at higher levels required to
ensure the desired removal efficiency.
3.4.3 HUfflltiltY
Working capacity as a function of steam consumption is shown for relative
33
humidities of 50 and 100 percent, 1n Figure 3-18. As shown, relative
humidity does not significantly affect working capacity. This is generally
the case for adsorbate concentrations greater than 1,000 ppm.34 Therefore,
there should be only a slight change 1n the breakthrough time associated with
variations in relative humidity in this case.
C-62
3-34
-------
too
u
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1*00 «•<
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F1gur« 3-16. GTR T«$t Nunbtr 6 Continuous Inlet/outlet VOC concentration data
and removal «ff1c1«ncy. _
3-35
-------
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rV
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m
9
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o
40
9
C
Cotctmratto* *%
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9
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iHteMMv «•. Tim*
Figure 3-17. GTR Test Number 5 Continuous Inlet/outlet VOC concentration data
c_64 and removil efficiency.
3-36
-------
Toluene - 600 ppm
MEK -1,000 ppm
Cyclohexanone - 400 ppm
Adsorption - 75 fpm
60% Relative Humidity
100% Relative Humidity
~
05
1.5
10
2.0
0
lbs. Steam/lbs. Carbon
Figure 3-18. Effect of Relative Humidity on Working Capacity
-------
Btlow adsorbate concentrations of 1,000 ppm water begins to compete with
adsorbate for the available adsorption sites and the bed working capacity for
that adsorbate is then affected. In this case, some type of dehumidification
system upstream of the bed or dilution with ambient air may be required.
Relative humidity has no effect on the amount of heel which is retained
within the carbon pore. Therefore, there is no B shift in the breakthrough
curve and no subsequent change in the achievable removal efficiency on a
long- or short-term basis.
High relative humidities are present in most operating systems regardless
of the vent stream conditions because of the water remaining on the bed after
steaming. As shown in Figure 3-18, the working capacity gained by reducing
the humidity is small. In this case, reducing steam humidity would probably
not be cost-effective. In addition, the water content in the bed provides a
heat sink valuable in controlling bed temperature.
3.4.4 Volumetric Flowrate
The superficial bed velocity for a system changes as the volumetric flow
to the system changes. The primary effect is to change the width of the mass
transfer zone within the bed. As the superficial velocity increases, the
width of the mass transfer zone also increases because the individual carbon
pellets are exposed to the adsorbate for a shorter period of time, thus the
quantity removed at a given point decreases. The effect of a wider mass
transfer zone on the shape of the breakthrough curve is shown in the top of
Figure 3-19. As shown in the bottom figure, the time prior to breakthrough is
shortened by increases in volumetric flowrate because of the wider MTZ.
To illustrate the independence of carbon adsorber removal efficiency to
short-tem variations in the volumetric flowrate, the flowrate and
corresponding Instantaneous removal efficiencies for an operating adsorber
system are presented in Figure 3-20.As shown, the flowrate varies randomly
during the entire adsorption cycle while the corresponding removal
efficiencies show little variation. For flowrate variations from 45,000 to
25,000 scfm the removal efficiency varies less than 0.5 percent with all
efficiencies being well above 99 percent.
Since variations 1n the volumetric flowrate do not affect the amount of
heel on the bed at a given time, there 1s no B shift in the outlet
C-66
3-38
-------
E
a
a
e
o
e
e
«
c
<3
£
Constant Loading
Increasing Flowrats
(0
«
(O
w
o
a
a
>
Distance Through Bed
c
o
e
9
o
a
O
Constant Loading
Increasing Flowratt
Time |
Figure 3-19. Effect of Variation in Volumetric Fiowrate on the Shape
of the Breakthrough Curve
3-39
C-67
-------
0
1
o\
00
e
8
«
i
1L
60,000
55,000-
50,000-
45,000
40,000
35,000
30,000
25,000
~ Flowull
• Removal Efficiency
20,000
60 60 100
Time, minutes
Figure 3-20. Carbon Adsorber Removal Efficiency with Varying Flowrate for a
Complete Adsorption Cycle
a.
3
-------
concentration prior to breakthrough, due to either long- or short-term
variations In the flowrate. Consequently, there 1s no effect on the long- or
short-term removal efficiency achievable by the system.
3.4.5 Bed Foul 1 no
This section discusses the effect of bed fouling an adsorber removal
efficiency. The causes of bed fouling were previously discussed in
Section 3.2.2. Bed fouling gradually decreases working capacity by tying up
the active adsorption sites 1n the micropores or blocking the pores which
prevent adsorbate molecules from entering. Because the capacity of the system
1s decreased, the time prior to breakthrough 1s shortened. As discussed
previously, this has no effect on an adsorber's removal efficiency until the
shortened length of the adsorption cycle begins to conflict with the
regeneration time. At this point the carbon should be replaced.
Fouling will not affect the outlet concentration prior to breakthrough.36
Therefore there will be no B shift in the breakthrough curve. The reason is
that fouling will not affect the amount of heel left 1n the bed.
As previously discussed, fouling does gradually reduce bed working
capacity. In some cases the steam flow and/or temperature can be increased to
reduce the heel and therefore increase working capacity the bed ages.
However, as previously shown in Figure 3-9, the point will be reached where-
increasing the steam flow will have little beneficial effect on working
capacity. Therefore, even 1f the system 1s well designed and operated, a
point will be approached where there is Insufficient time to regenerate the
off-line bed before the on-Hne bed reaches breakthrough. At this time,
carbon will need to be replaced.
Figure 3-21 presents overall removal efficiency plotted as function of
carbon bed age for a system on a vent stream containing cyclohexanone,
tetrahydrofuran, methyl ethyl ketone (MEK), and toluene.37 Both cyclohexanone
and MEK are known to cause bed fouling. As shown, there is only a slight
decline in the removal efficiency from 99.6 percent for the newest bed to 99.4
percent for the oldest bed.
Though fouling of the carbon bed has no affect on the efficiency of an
adsorber system, it does reduce bed life, which 1n turn increases the annual
operating cost of the system. The fouling rate is affected by numerous
3-41
C-69
-------
Legend
96-
Average Composition of
Recovered Solvent (Wt %|
Cyclohexenone 44
•
THF 23
MEK 19
as-
1 1 » i 1
Toluene 14
1 » ¦ i »
0 4 8 12 16 20 24 28
Bed Age, weeks
Figure 3-21. Carbon Adsorber Removal Efficiency as a Function of Bed Age for a
Ketone Containing System
-------
factors, but the adsorbate characteristics can be considered the most
dramatic. The effect of several solvent blends on bed life is shown in
Table 3-1. For the toluene and 1sopropylacetate (IPA) application shown, the
beds have not yet been changed after six years of operation and no shortening
of the adsorption time prior to breakthrough has been detected. For the
toluene and hexane application shown, the bed life is reported to be 10 years.
Lifetime removal efficiencies are also shown in Table 3-1. High removal
efficiencies are shown even for streams containing high concentrations of
cyclohexanone, a known fouling agent. Facility A has a 99.4 percent removal
efficiency on a six bed adsorption system. The bed life for this facility is
significantly less than the other facilities shown. The overall removal
efficiency at Facility A reflects the aggregate for a system with beds at
various stages of life. The solvent recovered at this facility includes
approximately 44 percent by weight cyclohexanone and 19 percent methyl ethyl
ketone. Based on the overall system removal efficiency for this system of
99.4 percent, it can be concluded that all the beds in the system are
achieving well above 95 percent removal.
3.4.6 Channelinq
As discussed in Section 3.3, a carbon adsorber system should be designed
with adequate flow baffles and proper steam distribution to prevent
channeling. If channeling does occur, it will cause elevation of the
background outlet concentration over a cycle, or a gradual increase during the
cycle. For systems with VOC monitors, these increases will be readily
apparent. If the amount of channeling is small, the system may still be able
to retain the required removal efficiency. If significant channeling occurs,
then adsorber removal efficiency would be significantly degraded.
In a wtll designed system, channeling need not occur. From the
perspective of the ability of a carbon adsorber to meet a specific regulatory
removal requirement channeling is actually a malfunction of the system, rather
than a factor causing inherent variability 1n short-term efficiency.
3.5 DELIBERATE CHANGES FROM INITIAL DESIGN OPERATING CONDITIONS
This section discusses the effect of changing the adsorbate type(s) and
steaming conditions. To assess the Impact of each change on the future
C—71
3-43
-------
TABLE 3-1. REPORTED BED LIVES FOR VARIOUS SOLVENT BLENDS38'41
Facility
Solvent blend
Reported
bed life
Reported removal
efficiency (%)
A
44% Cyclohexanonec
14% Methyl Ethyl Ketone
23* Tetrahydrofuran
19% Toluene
_d
99.4
B
50% Toluene
S0% Isopropyl Acetate
>6 Years
98a
C
95% Toluene
5% Hexane
. 10 Years
99.5b
0
Methyl Ethyl Ketone
5 Years
99.6
aValue reported by company. No data was provided to verify.
^Estimation: Assumed average inlet loading was mid range in design
specification range, and outlet loading was the reported value.
cActua1 solvent blends at this facility vary. The values are typical of the
total solvent recovered daily.
^The specific bed life at this facility 1s confidential business information.
However, it is significantly lower than the other values shown. This reduced
bed life is believed to be at least partially due to the presence of
cyclohexanone and methyl ethyl ketone.
C-72
3-44
-------
optration and performance of the adsorber system, the logic associated with
the initial specification of each design parameter is discussed.
3.5.1 Adsorbate
The concentration and type of organic are key factors in the design of a
carbon adsorption system. The adsorption characteristics of each compound are
assessed by using their physical properties data, such as: polarity;
refractive Index; boiling point; molecular weight; and solubility in water.
Nonpolar compounds and compounds with high refractive indices tend to be
42
adsorbed more readily. High vapor pressure/low boiling point adsorbates and
low molecular weight compounds adsorb less readily/3 Compounds with
molecular weights greater than 142 adsorb readily but are difficult to
44
desorb.
If the adsorbate is water soluble, water left as condensate 1n the bed
45
after steaming and cooling can contain adsorbate. When the adsorber is
brought on-line, the water and adsorbate will evaporate from the bed during
the first part of the adsorption cycle, slightly Increasing the Initial outlet
concentration for a brief time until the concentration falls rapidly to a
normal baseline value.
The properties and adsorption characteristics affect both the design and
operating conditions. If the feed stream is changed, the adsorber system must
be re-evaluated. If it can accommodate the new feed, there will be no effect
on the achievable removal efficiency; although on-line adsorption time and
steaming requirements may need to be changed. If timers are used as the
trigger mechanisms, the new working capacity of the beds must be determined.
Using this working capacity and a maximum Inlet loading, the appropriate new
adsorption time can be determined so that the timers can be reset for the new
operating conditions.
Changing the adsorbate can also affect the desorption cycle. The
relationship between steam usage and working capacity was previously shown for
three different compounds in Figure 3-9. As can be seen, if the adsorbate
blend 1s changed, the optimum steam requirements may also change.
3.5.2 Steamino Conditions
As previously discussed, steaming requirements are determined as part of
the initial system design. Variables which must be considered are the
3-45
C-73
-------
steaming temperature, duration, and rati. Generally, steam temperature is
fixed with a given plant. For this reason, the effect of temperature is not
discussed. The amount of steaa required 1s determined by the required working
capacity. Once the initial design 1s set, as long as the amount of steam used
per desorptlon cycle remains constant, the available working capacity will
remain constant assuming no fouling or other degradation of the carbon bed.
In actual application, however, the carbon's total absorption capac ity
gradually decreases over time due to fouling. If the operator desires to
maintain the same breakthrough time, steaa use per desorption cycle must be
gradually Increased. (Alternately, If sufficient standby time 1s available,
the length of the adsorption cycle can be gradually decreased as previously
discussed.) At some point the amount of steam required per desorption cycle
becomes so great that either there 1s Insufficient time to complete desorption
before breakthrough of the on-line bed, or the cost of steam becomes too
great. At this point the carbon must be replaced.
Although steaming amount is important 1n the desorption process, duration
1s also a consideration. In order to remove the adsorbate, sufficient time at
the steaming temperature is required. This 1s to allow for diffusion of the
adsorbate out of the pores and out of the carbon particle. Without sufficient
time, increasing the flow of steam will not remove the adsorbate from deep
within the pores of the carbon.
3.6 PERFORMANCE INFORMATION ON INDUSTRIAL AOSORBERS
Available data concerning the ability of carbon adsorber systems to
achieve 95 percent removal efficiencies are summarized in this section. Data
from performance tests sponsored by EPA's Office of Research and Development
(0R0), three test programs sponsored by EPA's Emissions Standards Division
(ESO), and Industry are used to support the conclusions reached. For each of
the tests, the design parameters, operating conditions during testing, and
test Information and results are given. A comparison between design and
operating information 1s then used to evaluate 1f a given system was operated
within design limits during testing.
Data sources along with the site codes and test numbering scheme used in
the presentation are discussed 1n Section 3.6.1. In Section 3.6.2 the
C-74
3-46
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adsorber systea operation 1s discussed with respect to the removal
efficiencies achieved at a given site. Specifically, poor system operating
procedures which were Identified are explained. Finally, In Section 3.6 the
conclusions reached regarding adsorber performance are presented.
A suanary of the available carbon adsorber emissions test results is
given in Table 3-2. Average overall removal efficiencies, design and actual
operating conditions, and testing information are given for each of 12 sites.
Emissions test data were available for 11 of the 12 sites. The twelfth
reported efficiencies, but provided no supporting data. For each of the tests
1-15, a unique test number is reported. Repeat tests were done at 4 of the
twelve sites. Table 3-3 presents individual average bed removal efficiencies
for several of these sites.
Tests 1-10 were performance tests performed as part of an EPA/0R0 study
46
of carbon adsorber performance 1n various industries. The manufacturing
processes included are rubberized fabric, magnetic tape, flexible packaging,
and rotogravure printing. Test 6 of this study was not presented for reasons
discussed in Section 3.6.2. Six of the 10 tests were conducted in early 1982.
The four follow-up tests were performed one to two years after the initial
test. Tests 11-13 were performed as part of EPA/ESO performance evaluations
47-49
at three specific sites. Results from Tests 14 and 15 were provided by
industry.
Tests 1-13 were conducted 1n accordance with approved EPA methods. Inlet
and outlet concentrations were measured semlcontinuously with flame ionization
detector total hydrocarbon Instrumentation as described 1n EPA Method 25A.
Volumetric flow rates were measured according to EPA Methods 1 and 2. All
tests were verified by EPA-specified quality assurance/quality control
procedures.
Tests 14 and 15 were performed 1n accordance with EPA Methods 1,2,
and 25. Method 25 differs from Method 25A 1n that integrated bag samples are
taken and the concentration of the gas within the bag is used to determine the
removal efficiency over the sampling period. Although this method does not
give the semi continuous data provided by Method 25A, it provides a means for
accurately assessing the average removal efficiency over the sampling period.
3-47
C-75
-------
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TABLE 3-3. PERFORMANCE TEST DATA FOR CARBON ADSORPTION SYSTEMS53"56
ON A PER BED BASIS
Oata collection
Removal
Test number
Bed designation
time period
efficiency, %
1
A
NAb
87.2*
B
NA
78.9a
2
I
NA
99.6
2
NA
99.3
3
NA
99.8
3
1
NA
97.3
2
NA
92.7
3
NA
95.9
4
IA
705 n1n.
94.0
IB
826 m1n.
94.0
IB
382 n1n.
94.3
IB
280 m1n.
89.2
2A
247 min.
92.9
2A
279 rain.
91.3
2B
105 rain.
88.9d'e
2B
247 rain.
95.5
3A
128 rain.
96.2
3A
271 rain.
97.7
3A
647 min.
96.6
3B
898 min.
98.0
3B
781 min.
96.2
5
1
451 rain.
99.4
2
388 rain.
99.3
2
507 min.
99.0
2
228 m1n.
99.4e
3
295 rain.
98.9f
7
A
NA
97.0
B
NA
97.6
C
NA
98.3
(continued)
C-78
3-50
-------
TABLE 3-3. (Continued)
Data collection
Removal
Test number
Bed designation
time period
efficiency, %
8
A
NA
91.4
B
NA
91.4
C
NA
97.8
9
1-1
7.6 hrs.
98.0
1-1
9.1 hrs.
97.4
1-1
8.6 hrs.
97.8
1-1
8.1 hrs.
96.6
1-1
5.5 hrs.
97.3
1-1
6.8 hrs.
97.6
1-2
8.5
97.9
1-2
9.4
96.8
1-2
8.2
97.0
1-2
6.0
97.6
1-3
8.1
97.8
1-3
6.4
97.5
1-3
7.4
98.1
10
1-1
NA
97.9
1-2
NA
98.1
•
1-3
NA
97.5
11
1
NA
99.8
1 .
NA
95.5
1
NA
97.7
1
NA
97.8
1
NA
98.9
3
NA
99.4
3
NA
96.4
3
NA
98.5
3
NA
98.8
3
NA
98.7
a0ata are from one cycle; overall system efficiency was 84.9 percent.
bNA - Not available.
c0nly one coating line 1n operation.
^Collected during startup of one of the lines.
eCoating process unsteady during this period.
^Not representative of normal operation; system returning to steady-state
after all beds on adsorption.
-------
Site I supplied no detailed Information so only the reported removal
efficiency 1s presented.52
3.6.2 Removal Efficiency Oata for Performance Tests
The overall removal efficiencies presented in Table 3-2 range from
84.9 to 99.7 percent for a variety of adsorbates including MEK, toluene, THF,
MIBK, cyclohexanone, hexane, and IPAC. On a per bed basis, the range of
removal efficiencies is 52.3 to 99.8 percent. As shown, the bed ages
associated with the adsorbers tested range from 3 to 7& months.
The overall removal efficiency of 84.9 percent reported for Test 1 is the
result of both operating outside of the original design range and poor
operation during the test. The system was designed to recover an adsorbate
blend consisting of 60 percent methyl ethyl ketone and 40 percent toluene. At
the time of the test, the organic feed was 100 percent methyl ethyl ketone.
As discussed in Section 3.5.1, switching adsorbate blends can have a
detrimental effect on removal efficiency. In addition, several operating
practices at this site may have contributed to the reduced control efficiency.
These include cocurrent steaming of the bed, cocurrent cooling of the bed with
the adsorbate laden stream, and operating with a malfunctioning steam
condenser.
Cocurrent steaming leaves more residual solvent at the bed outlet than
countercurrent steaming, thus increasing the outlet concentration when the bed
1s brought on-line. Cooling the bed with the adsorbate laden vent stream
further aggravates this problem because it allows adsorbate laden air to enter
the bed when the system working capacity is at its lowest. This allows
adsorbate to spread down the bed much further than if the system is operated
correctly. For reasons which have been discussed in Section 3.4.1 this caused
the system to bt more sensitive to variations in the operating temperature.
The final problem associated with this system was a malfunction in the
condenser system. The system was not cooling the desorbate stream
sufficiently. Since the steam from the condenser was recycled to the on-line
bed, unusually high amounts of solvent were allowed to enter the bed from.the
recycle stream. This additional solvent loading led to premature
breakthrough.
C-80
3-52
-------
In suanry, these problems would Indicate that this system was not well
designed and was poorly operated. Its removal efficiency 1s not
representative of a well designed and operated system. It should be noted
that several of the problems would have been discovered as part of normal
operation if the system had used continuous outlet monitors.
The average overall removal efficiency presented for Test 2 is
99.7 percent.
The individual bed efficiencies range from 99.6 to 99.8
percent. The solvent blend for this system was 50 percent toluene and
SO percent tetrahydrofuran, and all of the operating conditions were within
design specifications with the exception of the loading rate. The design
specification was 140 lb/hr, but the actual loading rate was 195 Ib/hr.
Test 3 is a follow-up test at site B. For this test, the average
system overall removal efficiency was 95.3 percent with the individual bed
efficiencies ranging from 92.7 to 97.3 percent. All of the beds had lower
removal efficiencies than 1n the Initial test. Test 2. The reduced removal
efficiency during the second test was attributed to the following 1n the
test report:*7
• Increased carbon age;
e lower regeneration steam temperature;
e higher SLA Inlet temperature; and
e change 1n solvent formulation to 75 tetrahydrofuran and 25 percent
toluene.
CO
Figure 3-22 presents a typical outlet concentration curve for this test.
Ouring the Initial test (Test 2), the typical outlet concentration had an
Initial spike and then decreased to approximately 1 ppm for the remainder
adsorption cycle. However, during Test 3, the outlet concentration was much
higher and an upward trend Indicating the beginning of breakthrough can be
CQ
seen at the end of the cycle. This result would be expected due to the
factors shown above. If the desorptlon and adsorption cycles had been
adjusted to account for the changes 1n SLA inlet temperature, solvent
3-53
C-81
-------
1,500
Adsorption
1,400
1,300
C 1,200
5 Moo
e
«
3
1,000
900
>
E
a
a
800
700
Av«rag« Cia ¦ 1180 ppmv
e
o
(0
w
e
-------
composition, and regeneration steam temperature, and carbon age then the
performance during Test 3 should have been similar to the Test 2 performance.
However, even though this system did show reduced efficiency in Test *
the average system efficiency was over 95 percent, which would be sufficient
to meet the 95 percent removal efficiency requirement in the proposed magnetic
tapes regulation.
The adsorbate blend concentrations for Test 4 are not specified, but the
blend included tetrahydrofuran, toluene, methyl ethyl ketone, methyl isobutyl
ketone, and cyclohexanone. The average overall removal efficiency for Test 4
1s 94.8 percent. Individual bed removal efficiencies ranged between 89.2 and
98.0 percent. The average loading for the test period was 1,260 Ib/hr which
is over twice the design level of 600 Ib/hr. If the adsorption time had been
shortened to account for the Increased loading (as discussed in Section 3.4),
removal efficiencies for all beds would have been higher and as discussed in
Section 3.3.3, the variability would be less.
Hexane is the only adsorbate at Test 5. The overall removal efficiency
shown for this test period is 99.1 percent with individual bed efficiencies
ranging between 98.9 and 99.4 percent. All of the operating conditions were
within design specifications.
The follow up test at this site was Test 6. In this test, an extremely
low removal efficiency was achieved due to a leaking steam valve. Excursions
in the outlet concentration were shown to coincide with the steaming cycle for
the off-line bed. In this system, the steam flow is cocurrent, in the same
direction as the air flow during adsorption. Consequently, the steam leak
allowed the solvent laden steam from the off-Tine bed to enter the outlet
stream of the on line beds. This resulted 1n false readings at the adsorber
outlet. For this reason no data from this test were included 1n this report.
The results shown for Test 7 are for a single component system in which
toluene 1s recovered. The overall removal efficiency for this test is
97.6 percent even through both the inlet temperature and loading rate were
slightly above design specifications. The Individual bed removal efficiencies
were between 97.0 and 98.3 percent.
The follow up to Test 7 1s Test 8. Toluene was also the only adsorbate
for this test. The removal efficiency for bed 2 is not included in the
3-55
C-83
-------
average reaoval •fflciency of 94.6 percent which 1s shown for this test.
(Table 3-2) A steam valve leak allowed steam to leak Into bed 2 raising the
temperature significantly, and severely reducing the working capacity. As in
Test 6, the outlet concentration peaks were shown to coincide with the
desorptlon period of the off-line bed. Since the data for this bed are not
representative, they were not Included. The lower removal efficiency for the
other two beds 1s the result of two related problems. A malfunctioning inlet
air cooler allowed the inlet temperature to rise 32°F above the design maximum
and also a timer occasionally malfunctioned. Once again, the use of
continuous outlet monitors 1n the operation of this system would have helped
to uncover the malfunction 1n operation.
Tests 9 and 10 were both conducted at site F with an adsorbate blend of
60 percent toluene and 40 percent Isopropyl acetate. The overall removal
efficiencies for these two tests were 97.5 percent and 97.8 percent,
respectively. The Individual bed removal efficiencies were 96.8 to
98.1 percent. These removal efficiencies agree well with what would be
expected for the two sets of operating conditions. In both tests, the inlet
adsorbate loading was above the design specifications of 810 Ib/hr. All of
the other operating conditions were within design specifications during both
tests.
No design parameters or individual bed removal efficiencies were
available for Tests 11, 12, and 13. Therefore, it was not possible to assess
the system operation 1n terms of design. The adsorbates for Test 11 were
methyl ethyl ketone, methyl isobutyl ketone, and toluene. The overall removal
efficiency shown for Test 11 1s 98.9 percent. For Test 12 the overall removal
efficiency was 98 percent for a adsorbate of 100 percent toluene. The
adsorbate mixture for Test 13 was 30 percent toluene, 4 percent xylene, and 66
percent lactol spirits, and the overall removal efficiency 1s 95.8 percent.
The overall removal efficiency shown for Test 14 1s 99.4 percent. The
average composition of the recovered VOC at this site is as follows:
44 percent cyclohexanone, 23 percent tetrahydrofuran, 19 percent methyl ethyl
ketone, and 14 percent toluene. All of the operating conditions shown for
this test are within the design limits. In Test 15, the adsorbate is
C-84
3-56
-------
100 percent methyl «thy1 ketone and the overall removal efficiency is
99.6 percent. None of the operating conditions at this site were outside of
the design conditions reported.
No actual test data are available for site L, but the overall removal
efficiency was reported by the company 99.5 percent. The adsorbate blend at
this site was 95 percent toluene and 5 percent hexane.
The performance test data shown 1n this section generally show removal
efficiencies above 95 percent. For cases where the removal efficiency was
below 95 percent, correctable problems were Identified which were the cause of
the lower removal efficiencies. It should be noted that these performance
test data are fairly short duration ranging from less than 2 hours up to
15 hours. If the time periods of startup and system malfunctions are not
considered, the removal efficiencies are fairly consistent with little
variability from bed to bed.
3.6.3 Continuous Removal Efficiency Data
Continuous efficiency data are available from two sites. These data are
presented to show a short-term efficiency variability. The data encompass a
relatively broad range of solvent blends, adsorbate loadings, flowrates, and
inlet temperatures.
Figures 3-23 and 3-24 present continuous inlet and outlet concentration
and removal efficiency data versus time for two test runs from site G in
Table 3-2. As shown in the figures, the Inlet concentrations vary
significantly throughout the respective testing periods. However, the outlet
concentrations remain fairly consistent regardless of the inlet
concentrations, and are almost always less than 10 ppm. The removal
efficiencies are also fairly consistent and are generally above 95 percent.
The only time the removal efficiency is below 95 percent is when the inlet
concentration falls below about 50 ppm. This is expected since as previously
discussed, the outlet concentration 1s Independent of the inlet concentration.
Therefore, 1f the inlet concentration 1s allowed to fall below the design
value, the instantaneous removal efficiency can also decrease below design
levels.
3-57
C-85
-------
K
W
J
1
i
\
»«« TlM
LT
Figurt 3-23. GTR Ttst Nunbtr 5 Continuous InUt/Outl«t VOC Concentration
Data and Removal Efflcitncy
c-86
3-58
-------
0*
I
s -
c
*
h
n
it* *94
I
s
11%
\%m ta
rv^
Figure 3-24. GTR T«st Number 6 Continuous Inlet/Outlet VOC Concentration
Data and Removal Efficiency
C-87
3-59
-------
Inlet and outlet concentrations and Instantaneous and cumulative removal
efficiencies for six adsorber beds at site J are presented in Figures 3-25a
through 3-25J. The continuous data shown were obtained at the request of EPA
and are typical of normal facility operation.60 As previously discussed, the
solvent blend at this facility ranges from 20-25 weight percent cyclohexanone
and 20-50 weight percent methyl ethyl ketone (MEK). Both cyclohexanone and
MEK have been identified as chemicals which react on carbon to cause fouling.
The data are continuous monitor readouts for each of the six carbon beds which
comprise the complete system. The Inlet concentrations vary between about
2,000 ppm and 3,000 ppm, with adsorbers #1 and #2 having the highest inlet
concentrations. The continuous outlet concentrations from all 6 adsorbers are
below 50 ppm. Of particular note is the fact that both the instantaneous
removal efficiency and the cumulative efficiency over the entire monitoring
period for all adsorbers are above 98.5 percent.
The instantaneous removal efficiencies of the newest bed ranged from
99.3 to 99.8 percent. The efficiency of the oldest bed ranged from 99.9 to
98.5 percent. One reason the removal efficiencies of°the beds stay well above
95 percent is that the beds are changed frequently. This facility could
operate the beds until their removal efficiency has reached 95 percent,
but has chosen not be do so to avoid operation problems which could cause
overall removal efficiency to fall below the desired value.
The data from these two sites indicate that the 95 percent removal
efficiency can be maintained continuously if the carbon absorber is properly
designed, operated within Its design specifications, and well maintained.
3.7 CONCLUSIONS REGARDING CARBON ADSORBER PERFORMANCE
The data presented In Section 3.6 demonstrate that properly designed and
operated carbon adsorption systems can achieve 95 percent removal on a
continuous basis. This removal efficiency 1s shown for numerous solvent
blends and bed ages. Greater than 95 percent removal efficiency 1s shown for
streams that contain mixtures of ketones that include cyclohexanone, and for
which claims have been made that 95 percent 1s not achievable using carbon
C-88
3-60
-------
400
no -
300 -
250 -
200 -
190 -
100 -
90 -
TIME (man)
(«l/10)
Figure 3-25a. Inlet and Outlet Concentration Versus Cycle Time for
Adsorber #1
Figure 3-ZSb. Instantaneous and Cumulative Efficiency Versus Cycle Ti
for Adsorber #1
3-61
c-
-------
400
230 "
200 -
190
100
too
120
140
20
M
100
40
•0
0
nuc (min)
a Mat (al/10) « OMtM
Figure 3-25c. Inltt and Outlet Concentration Versus Cycle Time for
Adsorber *2
M.9
MS -
M.4 -
M.2 -
M.I
M
M.7
t r -
160
0
40
20
•0
100
120
ISO
140
TMC (m)
a mtnnni «
Figure 3-25d. Instantaneous and Cumulative Efficiency Versus Cycle T
for Adsorber iZ
3-62
-------
i
A
a
i
flMC (him)
Figure 3-25*. Inlet and Outlet Concentration Versus Cycle Time for
Adsorber #3
S
z
S
Instanta*
IMC (mm)
Ciwwi<«llii
Figure 3-25f. Instantaneous and emulative Efficiency Versus Cycle Time
for Adsorber #3
3-63
C—91
-------
2M
240
230
200
A
E
1M
*
*
w
1«0
§
140
1
120
100
o
o
eo
eo
40
20
0
>
z
»•
1 I I i i I r
20 44 M
(«1/10)
IMC (mm)
• OuOM
Figure 3-25g. Inlet and Outlet Concentration Versus Cycle Tim* for
Adsorber # 4
99.9
TIJC (mm)
Figure 3-25H. Instantaneous and Cumulative Efficiency Versus Cycle Time
or Adsorber #4
C-92
3-6*
-------
300
210
200
340
200
tao
1*0
140
120
100
•0
¦0
40
20
0
0
20
40
«0
¦0
120
100
140
1«0
tao
tMC (mm)
~ M (i 1/10) « OutM
Figurt 3-251. Inlot and Qutlot Concintntfon Vtrsus Cyclo Tin* for
Adsorbtr #5
e
i
too
«•»
M.7
M.fl
M.S
M.4
M.J
M.2
M.1
M
M.7 -
MJ
M.4
M.3 -
tU -
M.1 -
M
t r—r
20
i r
40
WWwfwn
"I I I I I 1 1
IMC (man)
100
Figurt 3-25j. Instantaneous and Cuaulat1v« Efficiency Vtrsus Cycl* Time
for Adsorbtr IS
3-6S
C-93
-------
a a ¦ a a o a
nuc M
Figure 3-25k. Inlet and Outlet Concentration Versus Cycle Time
for Adsorber #6.
T1UC (mm)
Instants
Cummutat>v«
Figure 3-251. Instantaneous and Cumulative Efficiency Versus Cycle Time
for Adsorber #6.
3-66
-------
adsorption. In every case where the removal efficiency was less than
95 percent, correctable and easily Identifiable operational problems were
responsible for lower removal efficiencies.
The key to achieving 95 percent removal 1s proper design and operation
of the adsorption system. If this 1s done, maintaining a removal efficiency
of 95 percent becomes only a matter of cost where the economic trade-offs
come in the form of steam cost versus carbon replacement costs. The carbon
must be steamed sufficiently to desorb the adsorbate, but excessive steam
use raises the operating costs. The adsorption time must be sufficiently
long to allow regeneration of the other bed(s). This will require
replacement of the carbon when its working capacity gets too low.
In Section 3.4 it was shown that if a system is designed for a full range
of operating conditions, operated correctly, and the carbon 1s replaced
before its working capacity has been reduced to the point where beds are
operated after breakthrough, the short-term removal efficiency should not
vary significantly. Based on the information and data presented here, it
can be concluded that a removal efficiency of 95 percent or greater is
continuously achievable.
3-67
C-95
-------
4. CARBON AOSORPTION SYSTEM AT COMMENTER'S FACILITY
This section presents an analysis of the carbon adsorption system located
at the commenter's facility. The information presented contains data for
which the commenter has made a claim of confidentiality. This information is
located in the confidential files of the Director, Emission Standards
Division, Office of Air Quality Planning and Standards, U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina. This information
is confidential, pending final determination by the Administrator, and is not
available for public inspection.
Preceding page blank
C-97
4-1
-------
S. REFERENCES
1. U. S. Environmental Protection Agency, APTI Course 415: Control of
Gaseous Emissions. EPA-450/2-81-005. Research Triangle Park,
North Carolina. December 1981. p. 5-4.
2. Reference 1.
3. Reference 1, p. 5-6.
4. Reference 1, p. 5-13.
5. Reference 1, p. 5-2.
6. Reference 1, p. 5-14.
7. Reference 1, p. 5-14.
8. Reference 1, p. 5-14.
9. Reference 1, p. 5-3.
10. Reference 1, p. 5-14.
11. Memorandum from Barnett, K. W., Radian Corporation to Carbon Adsorber/
Condensation Project File. February 29, 1988. Meeting Minutes
EPA/Calgon Carbon Corporation, p. 8.
12. Reference 11, p. 7.
13. Reference 11, p. 14.
14. Reference 11, p. 18.
15. Crane, G., Carbon Adsorption for VOC Control. U. S. Environmental
Protection Agency. January 1982. p. 18.
16. Reference 11, pp. 17-18.
17. Reference 1, p. 5-14.
18. Reference 1, p. 5-20.
19. Reference 11, p. 14.
20. Reference 11, p. 14.
21. Reference 11, p. 12.
22. Reference 11, p. A-8. n _
Preceding page blank
C-99
5-1
-------
23. Reference 11, p. 18.
2*. Magnetic tape Manufacturing Industry - Background Information for
Proposed Standards. U. S. Enviormental Protection Agency. Research
Triangle Park, North Caronlina. Publication No. EPA-450/3-85-029a.
December 1985. Appendix C.
25. Memorandum from Crumpler, D., U. S. Environmental Protection Agency to
Berry, J., U. S. Environmental Protection Agency. April 21, 1988.
Plant Visit to Ampex Corporation, p. 2.
26. Reference 11, p. 14.
27. Miller, K. J., C. R. Noddings, and R. C. Nattkemper. 3M Company. St.
Paul, Minnesota. (Presented at Air Pollution Control Association
Meeting. New York, New York. June 21-26, 1987.) p. 4.
• 28. Memorandum from May, P., Radian Corporation, to file. May 23, 1988.
Ampex Oata Analysis, p. 14.
29. Reference 28, p. 14.
30. Reference 11, pp. 14, 17.
31. U. S. Environmental Protection Agency, Industrial Surface Coating
Emission Test Report: General Tire and Rubber Company; Reading,
Massachusetts; Test Series 2. EPA/EMB-80-VNC-1B. Research Triangle
Park, North Carolina. July 1982. Appendix B.l.
32. Reference 31.
33. Reference 11, p. 10.
34. Letter from Shullger, W., Calgon Carbon Corporation to Wyatt, S. R.,
EPA. November 11, 1987. Response to information request.
35. Reference 28, p. 5.
36. Reference 11, p. 19.
37. Reference 28, p. 14.
38. Reference 28, p. 13.
39. Letter and attachments from Sapovlch, M., Dlversitech General, to
Farmer, J., U. S. Environmental Protection Agency. January 12, 1988.
Response to Section 114 information request.
c-ioo
5-2
-------
40. Letter and attachments from Jackson, P., Dayco Products, Inc., to Farmer,
J. U. S. Environmental Protection Agency. December 12, 1987. Response
to Section 114 Information request.
41. Letter and attachments from Johnson, W., R. J. Reynolds Tobacco (Archer),
to Farmer, J., U. S. Environmental Protection Agency. December 21, 1987.
Response to Section 114 Information request.
42. Reference 11, p. 4.
43. Reference 11, p. 4.
44. Reference 11, p. 8.
45. Reference 11, p. 10.
46. Blacksmith, J. R., T. P. Nelson, and J. L. Randall (Radian
Corporation). Full Scale Carbon Adsorption Applications Study.
Prepared for U. S. Environmental Protection Agency. Cincinnati, Ohio.
Contract No. 68-03-3038. Hay 1984. 211 p.
47. Feairheller, M. R. (Monsanto Research Corporation). Graphic Arts
Emissions Test Report: Meredith Burda, Lynchburg, Virginia. Prepared
for U. S. Environmental Protection Agency. Research Triangle Park,
North Carolina. Publication No. 79-GRA-l. March 1979. 30 p.
48. Feairheller, W. R. (Monsanto Research Corporation). Graphic Arts
Emission Test Report: Texas Color Printers, Dallas, Texas. Prepared
for U. S. Environmental Protection Agency. Research Triangle Park,
North Carolina. Publication No. 79-GRA-3. August, 1979.
49. Reference 31.
50. Letter and attachments from Gilbert, R., Ampex to Farmer, J. R., U. S.
Environmental Protection Agency. December 16, 1987. Response to
Section 114 questionnaire. .
51. Reference 39.
52. Reference 40.
53. Reference 46.
54. Full Scale Carbon Adsorption Applications Study. Plant 3. Radian
Corporation (Prepared for the U. S. Environmental Protection Agency).
Cincinnati, Ohio. August 19, 1982. Draft Report.
55. Full Scale Carbon Adsorption Application Study. Plant 4. Radian
Corporation (Prepared for the U. S. Environmental Protection Agency).
Cincinnati, Ohio. February 25, 1983.
5-3
C-101
-------
56. Full Scale Carbon Adsortplon Application Study. 6- Radian
Corporation (Prepared for the U. S. Environmental Protection Agency).
Cincinnati, Ohio. October 29, 1982.
57. Reference 46, p. 108.
58. Reference 46, p. 109.
59. Reference 46, p. 110.
60. Reference 24, pp. 3-4.
C-102
5-4
-------
APPENDIX D
LISTING OF AIR EMISSION CONTROL STANDARDS AND DOCUMENTS1
Page
A. STATUS OF STANDARDS AND BIDS
- New Source Performance Standards (NSPS) D- 2
- National Emission Standards for
Hazardous Air Pollutants (NESHAP) D-15
- RCRA Air Emission Standards D-20
B. CONTROL DOCUMENTS
- Control Techniques Guidance Documents (CTG) D-21
- Control Technology Documents D-24
- CTGs to be Developed D-25
- Control Technology Center (CTC) Reports D-26
1 Copies of the documents listed in this appendix and report
that are more than one year old are normally only available
through: National Technical Information Service (NTIS)
5285 Port Royal Road
Springfield, Virginia 22161
(703) 487-4650.
D-l
-------
lap 1
sons of sojnuss of fbnbici
¦m Scant tafcnnoc Standards
40 OT 60
Opdtted: OZAt/92
Priority List
CcMrai
PtcrisioBS
SafaMrt ItftetM F»dHtT Pollrtnt
Pwniatlde teriw
Categories of statio
«7
Opacity Beconfceepiag
ad Jeporting
JtitL
BP IP.
Stat* Plus for
Sesig. Facilities B
FMsii-fMl 9
Find Steaa
Generators for
feicfc Coastnc-
tioa isOoaatacad
After 8/17/71
aad Before 9/19/78
Opacity
A Ccetimocs Opacity Monitors
1 flow Berisica
Qulity
for Caseoos CB6
tamed e&issioa guideline
pofelication date
Utility aad Iadastrial 111,308,
(coal, oil, aad gas) lOx
Rood Besidoe Aaaadaeat PH, SOx,
wan
Aaeafeeat ( fiaal rile
Li^ute fired stau Kb
generators (Aaendaeat)
Barnioa for 30-day
Averaging
SQ2
01/31/71 08/21/79
(43nMI72)«4raW222)
05/13/81-t 01/01/12
(46R25601)(47n950)
07/31/M
(49FB30676)
09/17/84-C 12/27/85
(49R36410)(S0n5.n0S)
12/27 /85 03/26/17
(50nB3115)(52rBT7»)
05/11/IX
(52R17555)
04/lf/tS 01/21/14
(S0fU49«l)(Sl!12699>
03/14/84 06/04/17
(49R9C76) (S2R21003)
04/20/81 02/20/19
(53R12962) (S4nS21tt)
06/17/71 12/23/71
06/14/74 clarification
01/17/79 11/22/76
(41R51397)
11/25/16-1
(S1R42796)
12/22/76 03/07/71
(41IS55792) (43R9276)
10/21/13
(48R48960)
01/17/84-P 11-08-85-8
(49FR1997) (50F846464)
03/23/M-P 08-17-89
(49FK10950) (54FR34008)
06/01/84-P
(49FK22835)
M-4S0/3-7»-«19
EP1-450/3-79-023
EPA-450/3-8S-013
B?A-450/3-15-013
ffl-450/3-40-033att
EPA-450/3-82-010
BMSO/3-79-421
APTXmi
ffA-450/2-76-Q30att
EPi-450/3-824O13a
EPA-450/3-«2-013b
O.S. EPA/Office of Air Caality Planning aad Standards
A - aaendaeat
K - revision
Eaissioo standards Division (MK3)
C - correction
8 • withdrawal
Sesearch Triangle Park, IC 27711
P- reep. for pvbl. coat.
! - listing
1 - notice
D—2
-------
• •
ftp 2
sons of ftinuu of kbomaki
McmnltiiMi
<0 cn <0
Proauloation l»vi«
JCSBI
Suborn AfftcCad
fciirtMt Beta
fiita Data
ID lo.
AfliMdii 1 (mlfsie add
•xdmioa)
CMtral Illiaois M.
Serrlot Co.; Icvtoa,
H Power Stitioa -
Buttle tevisioa
n
06/29/S5 U/X/W
(50R21K3)(5in<2t»)
npSftyk 0l/04/t7
(90RMU) (S2nQI94«)
03/»/»*
(SOTIU574)
Vl-4SO/)-M-OOI
Beet. Itllitr
Stee 6eentiiq
kits for Aid)
Coaatnctioa is
CoMoad After
mm
t,U, Method 3 i 3>
5,1,
B
Ptility boilers
(•olid, lifdd, i
fads)
a/01/19
(S4PU9M)
W, IB, 0»AV OC/U/79
¦ft (4Jfld54)(44ft3JS!l)
Method 9itf misioa to
Afpaadii 1 (atlfsic add
exdmioa)
B,Di, Hctkod 3 « »
1,1,
B
Iadvtrlal Vb latatrlal boil«i
loiian (cotl, ail, ?M,
solid mste, mod aad
)
m, ni
Oocractioa to prtfoaad rile
Method a i sr RTisioa to
HHiflli A (silicic add
exclusioe)
Oil-find boilars M
Industrial boilers
0S/39/tS
(90R21M3) UfX/U
{unaoi)
CJ/01/W
(S4IMS64)
0-007a
V»HSO/2-7>-007a-l
VtH90/>>7Hm
nH9O/3-M-0OI
M-<5O/3-«2-0Ofetb
ffl-450/3-42-007
IHHiO/HHOI
IM-450/3-T7-C24
A - undacat 1 • revisioa
C - oomctioa H - vitbdraaal
P - reop. for publ. coaat. L - listiaq
I - notice
D-3
-------
f*f» 3
40CT140
PnwaMl Prarlqitioa leritw
Joke: Affwtn neinn teiintut mt«
JfcU-
J*li_
BP IB.
Inil MTriil Be sue 9*ntiig eite PI^O,
IlBtltltlflMl
ftwullay felts
04/09/19 09/12/10
(S«HMmt (S5R37C74)
V1-4S0/3-M-U
IPW50/V4V12
IPA-450/J-4V13
IPA-450/3-49-14
BA-450/3/19-13
DW50/3/»-14
B»i-450/J/l9-17
CA-450/3/«»-l»
¦nsidpsl
Iaeiamton
(>90 ttm/Uj)
laeiMraten
Maldytl list* a,t»
tatlaiCmt
Plistr
litrie lci4
Nuts
Sulfuric Acid
Pluts
Sulfuric Acid
Pluts 111(4)
to Putitica
23424
Kill, cliite coolv N
•otiot of rtricv 4 ptopoood
**
I Procus oquipacat
Process oqupacat
01/17/71 12/23/71 11/27/71
(44117939)
0(A*/M
(imssits)
07-07-47
(S2R2S399)
i2/ao/t»
(54TB2U0)
12/30/19
(54R5225)
10/06/90
(S5R40I70)
02*11*91
(ssnsm)
SOx, Kid
•ist
Acid aist
01/17/71 12/23/71 10/22/79
(440407(1)
09/10/15 12/14/SS 09/10/S5
(50H049S4) (53IB03M (S0TD49M)
00/17/71 12/23/71 04/19/79
04/05/14
01/17/71 12/23/71 03/15/79
(44F115742)
01/24/15
(50F134441)
10/11/77
APfD-0711
0i-4SO/>-79-OO9
»A-4S0/3-42-00fc*fc
Bi-450/WWai
Bl-450/3-49-27*
W-4S0/3/IWJC
VA-400/3/19467
»l-400/3/»-00
m-400/3/<9-279
VA-400/3/1^404
IW-430/H9-274
BA-4S0/3-91-003
B4-450/3-91-004
0M9O/3-*fr421
ATO-0711
0MSO/3-79-O12
m-450/3-15-003*
IPA-450/H5-00»
ATO-0711
m-450/3-79-013«
APID-0711
EPA-450/3-79-003
EPA-450/3-IV-012
EPA-450/2-77-019
A - ueod«st I - revision
C • eometios M - withdrawal
P- nop. for publ. coat. L - listiaq
I - Mtict
0-4
-------
ftqe 4 '
sum or sww& or hhwbici
Ua Somt Perform* state*
40OTW
ProMsal PromlMtiQB teTiev
Subpart lffectad r*rlHt» ft>1 Intuit
JUL.
wra ¦».
wMmLJmJk
i^btlt csaa«u
rusts
I Proom tadsHit
Icrlcv ad
Petrolra
MlMriis
Storage Vessels
for PttrolMi
iifiids Ceastreo-
tioa tfttr
5/11/71 I Prior
to 5/19/71
04/11/73 <0/01/74
oftUl.
fuel ^ts ONtattoa .= 302
{evicts
dm sslfur reeoftry
*2,
ttdooed
sails; co»-
fOOBdt, ES
01/24/44-4 01/24/44
(I1IX32M) (5im29t)
04/10/44-C
(511112324)
M/U/73 #3/1/74 10/22/71
(Mfll54«)(»r»30l) (44FHC741)
03/12/7M
<«4rxmto)
03/03/40-1 ll/01/KH 12/02/44
(4Smmi)(4SR7NS2)(SlR43S72)
10/04/71 01/15/71 12/21/13
(41fI43366)( 43R10446) (44F157234)
03/20/7?-! 10/25/7*
(44R17120)(44fl4iM2)
01/31/79 ffA-450/2-74-003
(44R51225) ll©>US2a-fc
m*4S0/3>79/014
m*4»/3-©-034
KXS Otaljst l*9aa* aoT Cl/17/44 10/22/75
•ritsrs (4HI205I) J44HMX1)
11/04/45*1
(50PI44444)
Pet., CO 04/11/73 03/01/74
(3«X1540C)(39R930I)
01/10/74 04/24/77-i
(41R3M00)(«2PI32424)
ktM IP I Si rtvisioa to 05/25/K 11/24/44
J^tadii l (sslMie acid aielaaioa) <50fS21443)(Slfl4243l)
btted 1M (ilttmtin C7/U/44 04/01/17
K wtM) (51/125212)(127120391)
IH-4SO/2-74-003
1MH3S2**
IP1-450/3-79-00I
WK50/3-44-OU
IPM50/2*74-014»4
H»i-450/3-t3-0i«
B4-450/3-IHJ13
IHHS0/2-74-0Q3
iHH3S3a**
IPi-45C/> 79-004
BM50/3-44-4Q4
Ictbod 101
letted 14 1 aid ICS
Casoliae, erode oil,
i disUUitt ttsrafe
Units >40,000 plleas
capicitjr
07/02/14
04/14/17
(111124144} (52TB0474)
voc
12/04/44 01/29/17
(511144075)(52FI36404)
02/02/44
(53PI2914)*C
04/11/73 03/01/74
07/23/14 04/C4/I7
(49TO9713) (52*111420)
04/14/17-C
(52/127779)
4FTD-1352I-D
1PA-450/2-74-003
I - ueadaeat 1 • revision
C - correction if • vitMrtval
P- wop. for pobl. coot. L • lisuw;
I - aotiet
0-5
-------
mm or sruoua or i
Mr Sokcb Ntfcnaot State*
40 <71 «0
tetrrt iffrnHd fcllrft t*»
»—1^1-
lull b CmtUm
f«r Patxvlaa
Ujtl* otHL"
ties attar 5/11/71
Mlfintia
7/23/44
Lm4 L
SMltKS O*
i Bratabpt
Prodoctioa Plots
Itn tad StMl i
mil
Ira t StMl
lills (eat'4)
Iroi 40,000
opacity, Taper
> 1.5
JttL
JttL
Iqainlaey datantfu-
tlo/<
Stany Vwls D
(bditisg
laaU*M
ftssals) fcrftlcfe
Volitil* orotic WC
llqaiJ staaga tote
> 90,000 qdlaa I
4 psi « > 40,000 '
ftilflSB 4 04 psi
Flara twvisia
Bast S rawrbaRtcry 11**
•lactrie
blast foams
Bisie 0279a
toms(BOR)
ftisoty nissia
BOPf, bet aUl ad
tkiaiag stations
05/14/74 04/04/10
12/l>/*<
(4903224)
07/23/44 04/04/47
(49(129713) (S2FXU420)
04/29/S1 12/01/12
(44R23944)(47nS4234)
' 07/23/44 04/04/47
(49R29713) (S2mi430)
04/14/45
(50(114941)
04/11/73 03/04/74 04/17/40
(34raS404)(31flB3Q4) (4510004)
n 04/11/73 03/04/74 04/19/79
(34fU5404)(39fl9304) (44(135953)
05/23/44 10/30/44 05/23/44
(49R2U44)(49fl43C14)(49n214M)
PI 04/11/73 03/04/74
(34IU5404)(39R9314)
Opacity stt. 03/02/77 04/13/74 08/21/79
(39(19304) (43(U5«02)(44m74<0)
01/30/13 01/08/44
(44(804) (S1R150)
fa?itiw
PI
Slndp iaciMraton PI
toastar, ssaltiaq SOx
fumes, carcrtar PI
teyes
01/20/43 01/02/44
(44(12051) (SiniSO)
04/11/73 03/04/74 U/27/79
11/10/77-1(44(247934)
(42(154520)
CMI/M 10/04/44 04/14/44
(51R13424)(S3R39412)(S1R13424)
10/;«/74 01/15/74 03/07/44
ll/01/77-A< 49(14572)
-UJLfe*
V1-4S0/3-41-003*
M-450/3*404Q3a4b
¦IH50/3-42-CW
WS-1352a-b
MHSO/J-74-003
lTO-U52«-fc
BA-450/2-74-003
IP1H50/3-44-009
iPBK1352lab
Bi-450/2-74-003
IPA-450/3-74-114
ffl-4SO/3-42-OOS<
IPA-4S-/3-I2-OOS6
lPTD-1352a-€
EPA-450/3*79-010
(PWS0/3*44*410t
e?l-450/>4V<10b
IPA*450/2*74*002l
EPl-4S0/3*43-014ilb
D-6
I - misioa
C • oorrcctioa « • vitMrrol
P • nop. for pufcl. coat. L - listinq
II - notice
-------
pjy 6
suns or snmuss or pmoouci
Mr Scoot Parfcanoe Staadirds
40CTX 60
Proaulaation teviev
SnhMrt HHHtr
PollntJHit
Drte
BID*.
Prlnry line
0 loastar
aox
10/16/74
01/15/76 10/01/12
DA-450/2-74-002a
S»lt«rs
Sixteriag aacbiae
n
(471X44517)
Ptiaoy lud
X Slstariag aachlae,
SOX
10A4/74
01/15/76 10/01/12
E>l-450/2-74-002a
SMlters
electric oeltiag
(471X44517)
fsraace, coomter
Pri«ry iluaira
Moctica Plot*
Ptiary Hoists
ledactica Plots
Ul(d)
fbospbite
Pctillxer
Xa&stry
T
0
V
V
X
Pbospbite
Pwtiliier
Pints (Ul(d)
0m1 Pnpiritioa !
Plots
ferrotlloy
Production
facilities
Blast or mtrten- PS
tory ftxraece, sister log
MT^iiiw discharge end
Pst liaes 4 oode take Plaoridus
plots
M liaes t aaode bat* Floorides
plots
Met proas* phosphoric flnorides
Seperpbocptaric add Plaorides
Dionaia phosphite Plaorides
triple s^erpfaoe. prod. Plaorides
cnaolar tzp. sq»er» Plaorides
pbos. prod.
Saall facility ezclasloa
for Sttparts 1, a, V, N
Net prooeai pbos. add Plosrides
Suparpbospboric add Plaorides
CiuBotioe phosphite Plaorides
Triple s^erpbes. prod. Plaorides
Trpl. ssperpbos. stor. Plaorides
ilr tables od tbeml Pi
dryers
: Specific farneces
n, oo
10/23/74 01/26/76 12/11/K
(39fB7730)(4in3l2<) (SU144643)
09AV7** 06/30/10
(43PX421I6)(4SPI442Q2)
04/11/79 04/17/M
BnftCK PilllCK
10/22/74 01/06/75 12/21/10
06/21/12 02/17/13
(47R2C750)(4!PI712S)
05/12/76 03/01/77
10/24/74 01/15/76 04A4/I1
(46R2176))
04/03/19
(54PX133M)
10/21/74 06/04/76 01/26/«l
(46118033)
DW50/2-74-C2Q1-C
Bi-450/2-7»-G25a
V1-4S0/3-79-026
IPi-450/3-46-010
fPl*450/2-7t*049«ib
n"4S0/2*74«O19aib
MHS0/3-79HBU
IPW50/2-74-0214-C
V1-450/3H0^23
EP4-450/3-M-001
EP1-450/2-74-01U-C
EPA-450/3-10-041
Steel Pluts:
Electric Ire
•uniaces
JlA Electric ere furnaces P*
10/21/74 09/23/75 04/21/10
01/17/13 10/31/14 <457X26910)
(417137334)(49P143I3I)
lPA-450/2*74*O17a4b
EPA-450/3-79-033
!PA-450/3-l2-020a
A - aaeadaent 1 - revision
C - correction N • vitbdraval
P - wop. for publ. coot. L - listing
I - notice
D-7
-------
Pap 7
SXWB Of SZU&ilDS Of RBCBOKS
lev Sauce Perforsanoe Standards
40 CR tO
Jaaa utrt* nnnt, *>\it«t r»t.
led-
aaic.
toft Hip
Killt
m Digesters, Um Ulif Total
fctftNf mis
111(4)
strippers, atlt I
EL3 tanks
Stiflt
(«)
iHiwf flinini, n
list, kill, atlt taak
Utenat. imitating procedure
iMotatiw technology nim
09/24/71 02/23/71
(4inon2)(43n99M)
Oi/19/14-i 0S/20/U O/19/SM
(491X2441) (93lll4S0/3*7»-00Satt
ffi"4S0/2*77"0Qlat
EP1-450/3-U-001
1 - aandaent t - revision
C • correction 0 • withdrawal
P - nop. for pgfal. cont. L • listing
I - notict
D-8
-------
Page «
suns or szu&uzs or mnmaa
Rev Source Perfonance Standards
40 OT 60
Soma Sctaart lffected facility Pollntant
fnoeul PTPIBlatiM iCTlff
teta Pate Date
BP HOi
Sotftoe Cxtlag B
letal PBndtare
Stationary
literal Cotos-
tiea Xoqioes
Stationary Cas
Turtines
tact aetal fsraitara
jarfaoe coating
operitioa
WC U/2I/I0 10/29/tt
(45fK79390)(47R4927t)
Btoptios of saall aetal
fmitart serf ace coating
facilities vsiag < 1,000
gallons of coatiag/year
It lack IC engine Kb
66 ladi gas tarfcine Bx, S0x
Urge industrial tarblaes
exempted frot iOi std.
Llae lanfac- IE
tsriag Plants
Ictary idls, bydrator PI
10/16/M-l04/30/4S-I
(WfX405C)(50Rl<247)
07/23/79
(44FM31S2)
10/03/77 09/10/79 10/06/13
(42RS37t2)(44RS2792) (MFMS701)
04/lS/tl-X 01/27/12
(4CT220QS)(477I3767)
07/31/M-*
(49R30672)
U/05/I7-C
(527142434)
06/03/77 03/07/71
09/02/12-1 04/26/M
(47rZ3«t22)(49ntl*076)
02/17/I7-I
52P14773
BA-450/3-»-007aU>
Bl-450/3-71-125
E>A-450/2-77-017a4
IPi-450/2-77-007a4b
IPA-450/3-44-004
?odin Cutout* n
Degtcasers JJ
(Organic Solrent
Cleaners)
Lead Acid RC
Battery Manufac-
turing Placts
Retallic
Kinerals
LL
Calcinen, dryers,
bleachers
Cold cleaner, vapor
degreaser, coweyor-
ixed degreaser
II 10/1S/I0 09/22/41-*
(4SR6t616){44FI46S13)
VOC, pa, 06/11/40
KZ, K3, (45R39766)
K, PI 113 04/21/41 Applicability date deferred
(467X22761)
04/10/47-P
(52FS29544)
lead oxide production Lead
grid casting, paste
sizing, three-process
operation i lead reclaiation
letallic aineral PR
processing operations
prior to aetal reduction
01/14/40 04/16/42
(4Snt2790) (47FS16S64)
04/24/42 02/21/44
(47n364S9)(49«S645t)
IPl-450/3-4
-------
Page 9
sons or snnuos or raronua
leu Source Ferfonaace Standards
40 CFS «
Pmnoul
PrtnloatioB leview
JfiBSt
—ftbaart Affected TadKty Pollgt«t Pate
tote Date
BIB*.
lotoaofcile aad
Li^it-taty Trodt
Sarfaca Coatiaq
Operations
Fbocphate Bode
Plaits
PerdiIor»-
etbylene Dry
Cleuieg
00
iaosiia Sallate
Manufacture
Friae, quid* coat, t
top coat opratioos
at assafely plants
Priae coat revision
voc
wImIobi
Innovative tedaoloqy
waiver
Innovative tedaoloqy
waiver
Innovative tedaoloqy
waiver
Ianovat. tadm. waiver correctioa
Criadiaq, dryiag i HI
calciaiaq facilities
Dryer, wastes, VOC
filters, (tills, sock
cookers
Pf loonia sulfate dryer FM
10/05/79 12/24/10
(44I»77J2)(457*8S410)
09/09/15
(507*36830)
07/29/82-1
(477*32743)
08/06/82 02/04/S3
(477X34342) (487*5452)
09/24/14 09/09/85
(497*37548)(507*36830)
09/30/16
(517*34898)
11/04/86-C
(517*40043)
09/21/79 04/16/12
(44F*54970)(47F*1«582)
03/27/90-1
(557*11338)
11/25/80
(451*78174)
12/09/91
(567R64382H
02/04/80 11/12/SO 03/06/85
(457*7758) (45R74846) (50719055)
Vl-450/3-79-Q30atb
M-450/3-79-<>17att
B»-450/3-79-029a
EPi-450/3~79-034aib
Bl-450/3-85-004
Graphic Arts
Iadistry
(Botoqrarare)
Pressure Sensi-
tive Tapes i
Labels Coatinq
Indus. Surface
Coatinq: Larqe
Appliances
Metal Coil
Surface Coatinq
QQ Kadi publication rot*- WC
qravure printiaq press
Ht AAesive coatiaq liae, VOC
release coatinq line,
precoat coatinq line
SS Each surface coatinq VOC
operation
TT Each priie coatiaq VOC
operation, each finish
coat operation
10/28/80 11/08/82
(457*71538)(477*50644)
01/10/83-C
(487X1056)
12/30/80 10/18/83
(4S7886278)(487*48368)
12/24/80 10/27/82
(4SFR8508S)(47FR47778)
01/05/81 11/01/82
(467*1102) (477*49606)
01/10/83-C
(487K10S6)
06/24/86-C
(517*22938)
MM50/3-80-031att
IPA-45O/3-8O-0O3*4b
EPA-450/3*80-037a4b
EPA-450/3-80-035a4b
D—10
A - aaenefcent R - revision
C • correction V • withdrawal
P - reop. for publ. cout. L - listing
N - notice
-------
P»ge 10
SX1SQS Of SZUDUD8 Of RDQBUKS
lev Soorce Perfomaot Staadardi
40 CFI 60
Pranlaatiea levie*
SnhMTt Iffrctarf UriHtv
Pollntnt tot*
Ptte mte
BTDIo.
Ispfaalt PncHt 00
i ispfaalt toofiag
Imfactsi*
aocc Iquipaeot
Ltakx (hgitiw)
W
Berenge Cu
CMtiags
Balk Gasoline
Teniaals
(ISBTO]
w
Bleria? stills, Fl
•iterator, asptalt
storage tub, literals
baidling, ( storage
facilities
Listed «qsipae3t WC
(fugitive sources)
grouped within a
process ®it
fctioe of •US' Availability
Flan isTisios
b<± exterior but HOC,
OMt opentioes, wr*
vanish ooatiag operation
( inide spray coatiag
at 2 piece beverage
can plaits
11/11/10
(45R7M27)
05/26/U-A 01/06/12
(46R2tlt0)(<7R34137)
01/05/11 10/11/13
(MR11J6) (4W1M32I)
06/07/12 10/11/13
(47mJ72«)<4«n4t32l)
l2-010
lPA-450/W
-------
Page U
SZUQS OP SZUDUSS Of PfBCBOKl
Iw Sena ftdoonoi ffiiUrti
40 cn <0
JfiSOl ***** fkel»*w *"ITw>wt
fir"1 "vMlatifli tain
JttL
Jfe.
Jkk.
MB
AL
Tim
wc
tidewll cocotiag, b«ad
ntiHiwd
qreen tire spraying,
organic-based green tire
spraying, licbalis-i,
liehtlit-f, i lietalix-
aotontic
01/20/13 09/13/17
(«SHXK)(S2R3(MI)
09/19/19
(S4R3M34)H
ffi-430/3aUHMt
MfMES
-------
Page 12
sums or szuduos or mnoua
lev Source taf onaoce Standards
40 CF1 60
PpmmuI Prnmlastioa leviev
OHbore lateral UK lataral gas production
VOC
01/20/44 06/24/45
£PA-450/3-42-024a
Cas Processing fadlitle«-«qQipaest
(49R2C36) (S0R2O22)
VWS0/3-U-084b
leaks of WX
flare levision
01/21/K
(S1R2699)
Onshore lataral
as Processing
Oak* Ofts Ret
Qwoc&iaq
Distillation
Operttiocs
(SMC)
IU. lataral gas production S02
m
m
loHtetallic 000
liaerals
(includes liqbt-
veigfct *9gregate,
gypsa, i per lite)
tool Fiberglass PPP
Insolation
lasnfactaring
Pet. lefinery
Rastevater
Systoc
SOOT leactor
Processes
lagnetic Tape
Industry
QQQ
SSI
Conventional tet Pi
qosadiiag facilities
facta distillation HOC
colon is petrol, refinery
4 synthetic organic cbei.
plant used is aaliaq one
of 220 cbeaicals.
flare levision
Sad) crusher, grinding PI
lill, screening opera-
tion bucket oonveycr,
bagging operation, storage
bin, enclosed truck or
railcar loading station.
lev, aodified, l PI
reconstructed vool
fiberglass insolation
•anufactnring lines
utilizing tbe rotary
spin foning process
Individual drain TOC
systets, oil-water separators,
drain systeas with ancillary
dovnstreai wastewater exponents
SSS Industrial paper ctg.
(foil t plastic fill)
VOC
Withdrawal - solve.-4, storage
tanks
01/20/14 10/01/15
(49R26S6) (S0fl40154)
IPA-450/3-42-0234
£PA-450/3-42-023t>
Bo schedule - at present no BPS to be developed
12/30/13 06/29/50
(MR5753l)(55fC(931)
05/16/45-P
(S0R20446)
04/16/15
(5(9X14941)
04/31/13 01/01/IS
(4IR39566) (S0fX3132t)
IPA-<50/3-t3-005a
Vi-4»/3-t3-005b
BA-450/3-42-010
ffi-450/3-40-033aifc
EPA-*50/3-43-001l
EPA-450/3-43-001b
02/07/S4 02/25/15
(49R4590) (SOIK7694)
Vl«450/3~t3-022a
05/04/47 11/23/M
(S2FK334) (S3R47616)
06/29/90
(55F126953)
01/22/46 10/3/44
(S1FI2996) (53FI3SS92)
11/2S/46-W
(51FK42SOO)
EPA-450/3-45-001a
ffi-450/3*45-001b
EPA-450/3-45-005a
£PA-450/3-45-029a
EPi-450/3-45-029b
1 ->
A - aaendaent I - revision
C - correction « - withdrawal
P- reop. for publ. coast. I - listing
N - notice
-------
Pagi 13
SHIQ5 Of SZUBUBS 9 P0OMUKI
lev Some Fafeniw Standarda
40 cm 60
IffaetM) hHlfhr MMirf
tat*
ratio.
Plastic Parts
tor Nslatm
lacfeiias
Coatings
TTT
lav, nodifiad, i recw* WC
started facilities that
sarfaoa coat plastic parts
to business aac&iaes.
01/08/W
(51ft«54)
<8/9/M<
(5imOM<)
01/29/M
(S3RK72)
05/27/lt
(53rtlS300)-C
EPi-4S0/3-IS-019atb
Calciaers i
Dryers in
Mineral Indost.
000
Mineral calciaers and M
-------
hgi 14
susos or SZUBU06 or moBoia
latloeal Baissioc Standards for laxardous iir Pollutants
40 Ol 61
Prooesal Promlaation lefiev
Jesca
fintort Bfll Intent teto B»t»
El&Jk
Itoiisiflos
tadioaoclides
tMerpoond
Oraaia lines
Bnyllia
liewtfnts to
General Prouaiocs
all
pollatast*
hryllia,
Meet lotor
firing
Mrcny
tiiyl Chloride 1
missions froi C
3oke Ores Wet
Coal Qarqinq
Topside leaks, and
Door leaks
06/06/44-1
(49R23564)
04A
-------
Page 15
sons of szucuds or ptmnus
lational Eaksioa standards for laxardons lir Pollstaats
40 cn <1
-S3BB.
Sutioart lffected Facility Pollutant tot* fiat* _Jtatn
BID to.
*SBBPkB KBB tUSSQBD fO UDHSOCLDC IRQ HTIEUBL Of ROtOSE) B9UP. lADTOWT.nri
doud bt oma or ux id luunoi, usnaor, d.c
Denial of petition for
reconsideration of withdrawal
Bkmm bins. I* AUvlrtiet reactor Beuw
froa Myl- section, D bydropemi-
benme/Styreae dation reactor, hydrogen
separation syst«
Denial of petition for „
reconsideration of withdrawal
Benzene Bqaiptt. J Listed eqoipnent
tan
Denial of petition for
reoonsideration of withdrawal
: Zkist.
iron Beuene
Storage tasks
I* Each storage tank
lotice of additional
enission date
Denial of petition for
reconsideration of withdrawal
0S/23/C
(SOR34144)
07/M/M .= _
(S3mt4M)
12/ll/W
(4SRS344S)
03/0C/S4 0i/0f/M-V
(49RS3tt) (4VB347I)
10/02/14-C
(49R3IKS)
M/S/tS
(50R34144)
07/3/M
(S3R2MM)
01/05/11 06/0S/M
<46R11<5) (497123491)
01/23/15
(50TB4144)
07/2J/M
(S3R2M9C)
12/19/10
(<5Rt39S2)
11/24/X2
(47FIS305I)
03/0C/S4 06/06/M-V
(49Rt3t6) (49R2347S)
04/23/15
(50TXM144)
07/2S/U 09/14/19
(S3fS2S49«) (S4FS3S044)
ffi~4S0/>>7H8St
EPi-450/3-i4-«0-434a
IPA-4S0/3-M-004
~SJBPAH RfflBD mssioro to SADIOTOCLIDB IRQ VITSDUMiL or PMPCSZD izsap.
HAXDLZD B! OFFICE OF iH AMD HDUTIt*, tUSEDGTOH, D.C.
KADIOmaiKS
k ' anesdnent I - revision
C - correction tf • vitbdraval
P • reop. for publ. coot. L • listing
I - notice
D—16
-------
P»9» J*
srins or sTisass or ronauKi
btfcMl bin
.icm SUM
Mi for Uiart
Hi iir KUftaaU
40(71(1
Praoul
Promiwtio* leviev
Dot*
bit* fitt*
MD to.
tason torn.
I
frooan aqmp—t.
laiW
01/01IU
0*-4SO/>-4X>14«
tzm Otto 9r
•Uraft facilltlas.
(i*ntm23)
V*H30/M3-«MI
Pludfct koovtry
afupiaat leaks, ltd aw
0»/77/«4-f
Marts
(ttrUNMI
09/14/19
(Mnt3l044)
Flirt rrrlsioa
•«/i«/ts
VI «0/3-«0-013att
(soruiMi)
WSS0/3-U-010
07/21/41
(S)nutmi
04/01/91
09/19/91
(SirtDMi)
(Mrt4?404)
(MM Bum.
U
rbanacaatial *q.
fcataaa
w/ii/n
03/07/90
MH90/)*7M31
(m Cbm. Kq.
fadlitiM
-«0-OQ»
*«taCp«r,
(»n4M04)
WkHS0/W7-«U
hUM Trust.
a
ComIIm Starap lull
1 F«m
MH90/VU40U
opar.i CoboIIm
at Jarrioa fUtiaas
«•
MH90/X743I
Nototlaf
%•
H-ttO/XO-OMa
to
fell CaMliM ThvImIa
laasaat
¦IH90/>«-03«
WH3O/3-M-0Ua
a
fed! CmoIIm Flats
Bataaa
»ft-490/>-««412l
®»-4»/3-04-00lJ
rr
hUM Most* OftritiM
1 iMSMt
D1-450/M4-01*
(MfMUH
a
latettiil SoIt. Qm at
iMJMt
Mftar Tin *9. faeil.
ICMBtM
a
latest* tills: raadM)
' teteti
•
03/31/71-1
1RM90
MrfKisq (MtMtM
Uill«p); Maollti«;
umm
04/01/73
im-OTS)
saravlaq, fMricstiw,
c*mir») (urmxi
Mstt aitpwil i ianUtiaf
0&/03/7M
(nmsmi
—fact an af Mp
io/a/74-1 io/n/7Vi
»M*/2-74-00»a
•tells, rwwMtioa,
imuioM)(«ona»2)
(4ferlcati«a, aspfealt
03AI2/77-4
m-4«/>T7-030
cckzvU, products
(•21*12177)
oMUiiiaq attest*
04'i9/7|
J4
jr»243^)
N*!f in Mrt practice
CT'IMM 04/0%'14
<4irtU12»>(4tnUM<>
t .6*1 rui«, CVT»CtiO»
oi/W-w-:
iSirumi
CtfsrcMMt i CMplioa
»
01/10/IVI 11/20/90
tw»4*>/)-io or
iS4mi2) I «/!«**)
i - we*«et I - rnuiM
C • cvmctiM « - •itMritMl
f • rwf. tor p^l. coat. I • lutuq
l • Mtiet
D-17
-------
sons or
l>U«al fctaloi
or RDOKUCt
ht
40OIU
lir KilitaU
»*""* ifr-IH-
f>TP"' >wniart tfl« »ti—
. Brtl Wi Ul_
lo«kbi».
tna CIms
RMtetXi*
n«u
Lmt^hJc
lr»aic hut.
fraa Um inaic
talUc
lMtqmlc
UMale hiM.
fm li# irmic
oral* sill
toilta*
Mtiaf
taltlaf
Lm WMtic sMlttn
(tatltiaq (root *
)
SmIUc
UdiMKlldM fr-f
IffiOfSI •
N>Jp—*iMto v
iMtjak W/W/lO-l
«sm7W)
07/30/13 M/04/M
(OftniU) (SUK279M)
U/M/U 10/09/M-C
(annuo) (sirkxm)
0J/J0/M-T 01/04/M
MOT0O77)
iMtqmic 07/30/U 01/M/M
SMtiC (4M311U) IS1R27W)
U/U/O-f W/03/0K
IWBSWI (SlflBUM)
M/30/M*t
(IMMI77)
Iioraaic 07/30/1]
apadc (OmUU)
12/M/O-f 01/M/M
4U4
m-«0/W>-011i
ffHM/HMOl
ifi-4SO/W>-010l
MHSt/MMOl
DWiO/VO-OO*
¦kHSO/V-O-ttfll
M-MO/HMDl
M-4M/>*«0-aU»
DWS0/>»
-------
top II STUB or STUDUS OP KOTBUJK2
latiotl hissioa stadardi for luirtn iir ftllatots
40 cn <3
iffcetAd
Bit*
Bat* tat*
U1> to.
brlr
Miction
D
HI ltf>
«/um
(wcnii)
ViHSO/Ml'OUa
WH50/M1-0U
tatfclor»-
ctfcylow
R
tq OMiiaq
fcrctloro-
•ttri -19
L
-------
sum or sunuos or nraurx
KB* aoiCi 1004(1) ilr fciaaka
40 <71X4 ad X5
fiit*
US la.
Valatila
ca/as/r
01/21/10
VWSO/3**-00)
achate
/C
Osttarratioa Md Ncbw] Act
C • comctioa
r • rtop. (or pul>l.
I • remioa
H - vitbdTMMl
. L • liitiaq
0-20
-------
(tfru itti)
CONTROL TECHNIQUES GUIDELINES DOCUMENTS
(Groups, I, II, III)
Control of Volatile Organic Emissions froa Existing Stationary
Sources, Volume I: control Methods for Surface Coatinc
Operations, EPA-450/2-76-028, November 1976. (Group Z) Engineer;
Bill Johnson. NTIS No. PB-260 386
Control of Volatile Organic Emissions from Existing Stationary
Sources, Voluse IX: Surface Coating of Cans, Coils, Paper,
Fabrics, Autoaobiles, and Light-Duty Trucks, EPA-450/2-77-008,
May 1977. (Group Z) Engineer; Dave SalBan (can*, eolla;
autoaflhllM. and light-duty trackaW Bill Johnaon (paper,
fabric)¦ HTIS HQ. FB-272 44^
Control of Volatile Organic Eaissions froa Existing Stationary
Sources, Voluae III: Surface Coating of Metal Furniture, EPA-
450/2-77-032, Deceaber 1977. (Group Z) Engineer; Dennis
CruBPUr. NTIS No. PB-278 257
Control of Volatile Organic Eaissions froa Existing Stationary
Sources, Voluae ZV: Surface Coating of Znsulation of Magnet
wire, EPA-450/2-77-033, Deceaber 1977. (Group Z) Engineer;
Bill jQhnnnn. NTIS No. PB-278 258
Control of Volatile Organic Eaissions froa Existing Stationary
Sources, Voluae V: Surface Coating of Large Appliances, EPA-
450/2-77-034, Deceaber 1977. (Group Z) Engineer; Bill Johnaon.
HTIS HQ. PB-27B 25?
Control of Volatile Organic Eaissions froa Existing Stationary
Sources, Voluae VI: Surface Coating of Miscellaneous Metal Parts
and Products, EPA-450/2-78-015, June 1978. (Group ZZ) Engineer:
Dennla grtmnlar. n»v Sulitn ar BUI .Tnhntnn (in that order).
NTIS No. PB-286-1S7
Control of Volatile Organic Eaissions froa Existing Stationary
Sources, Voluae VZZ: Factory Surface Coating of Flat Hood
Paneling, EPA-450/2-78-032, June 1978. (Group ZZ) Enpinaer;
See J. Berrv. MTTS No. PB-292 490
Control of Volatile Organic Eaissions froa Existing Stationary
Sources, Voluae vzil: Graphic Arts - Rotogravure and
Flexography, EPA-450/2-78-033, Deceaber 1978. (Group ZZ)
Engineer; Bill Johnson. NTTS Mo. PB-292 490
Control of Volatile Organic Eaissions froa Bulk Gasoline Plants,
EPA-450/2-77-035, Deceaber 1977. (Group I) Engineer: Steve
Miedd. NTIS No. PB-276 722
D-21
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ra*ru mst
10. Control of Volatile Organic Emissions from Storage of Petroleum
Liquids in Fixed Roof Tanks, EPA-450/2-77-036, December 1977.
(Group I) Enalnier! Randv McDonald. HTIS WOi PB-276 749
11. Control of Refinery Vacuum Producing Systems, Wastewater
Separators, and Process Unit Turnarounds, EPA-450/2-77-025,
October 1977. (Gzoup I) Engineer; K. C. Hustvedt. NTIS Mo.
PB-275 662
12. Control of Volatile Organic compounds from Use of Cutback
Asphalt, EPA-450/2-77-037, December 1977. (Group I) Engineer;
Dave Markwordt. MTIS Mo. PB-278 IBS
13. Control of Hydrocarbons from Tank Truck Gasoline Loading
Terminals, EPA-450/2-77-026, December 1977. (Group Z) Engineer;
StflV* StlCdd. MTIS MO. PB-27S 060
*
14. Design Criteria for Stage I Vapor Control Systems - Gasoline
Service Stations, November 1975. (Group Z) Engineer; Steve
SUsdsL.
15. Control of Volatile Organic Compound Leaks from Petroleum
Refinery Equipment, EPA-450/2-78-036, June 1978. (Group ZZ)
Engineer; K. C. Hustvedt. MTIS Mo. PB-2B& 1S8
16. Control of Volatile Organic Emissions from Petroleum Liquid
Storage in External Floating Roof Tanks, EPA-450/2-78-047,
December 1978. (Group 1Z) Engineer; Randv McDonald. MTIS Mo.
PB—290 S79
17. Control of Volatile Organic Emissions from Perchloroethylene Dry
Cleaning Systems, EPA-450/2-78-050, December 1978. (Group ZZ)
Engineer; Steve Shedd. HTIS HO. PB~2?Q 613
18. Control of Volatile Organic Compound Leaks from Gasoline Tank
Trucks and Vapor Collection Systems, EPA-450/2-78-051, December
1978. (Group ZZ) Engineer; Steve Shedd. MTIS No. PB-290 S6fl
19. Control of Volatile Organic compound Emissions from Volatile
Organic Liquid Storage in Floating and Fixed Roof Tanks, DRAFT,
August 1981. (Group ZZZ) Engineer; Randy McDonald.
20. Control of Volatile Organic Compound Emissions from Large
Petroleum Dry Cleaners, EPA-450/3-82-009, September 1982. (Group
izz) Engineer; stave Shedd. HTIS hq. PB-83-124 875
21. Control of Volatile Orqanic Compound Fugitive Emissions from
Synthetic Organic Chemical Polymer and Resin Manufacturing
Equipment, EPA-450/3-83-006, March 1984. (Group ZZZ)~ Engineer:
K. C. Hustvedt. HTIS NO. PB-84-161 S20. Cost S17.50
D-22
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(Afrtl mil
22. Control of Volatile Organic Compound Equipment Leaks from Natural
Gas/Gasoline Processing Plants, EPA-450/2-83-007, December 1983.
Engineer; k. c. Hustvedt. ntis wo. pb-84-isi 520. cost si7.so
23. Control of Volatile Organic Emissions from Solvent Metal
Cleaning, EPA-450/2-77-022, November 1977. (Group I) Engineer:
Dave BecK. ntis no. pb-274 557. cost si9.00
24. Control of Volatile Organic Emissions from Manufacture of
Synthesized Pharmaceutical Products, 450/2-78-029, December 1978.
(Group II) Engineer: Dave Beck or Leslie Evans. NTIS No. PB-
290 580. Cost S14.5Q
25. Control of Volatile Organic Emissions from Manufacture of
Pneumatic Rubber Tires, EPA-450/2-78-030, December 1978. (Group
II) Engineer: Dave Salman. HTISHQ. PB'290 557. C08t SIP.OP
26. Control Techniques for Volatile Organic Emissions from Stationary
Sources, EPA-450/2-78-022, May 1978. (Group II) Engineer:
Dave BecK. ntis no. pb-284 804. cost $41.50
27. Control of Volatile Organic Compound Emissions from Air Oxidation
Processes in Synthetic Organic Chemical Manufacturing Industry,
EPA-450/3-84—015, December 1984. (Group III) Engineer: Leslie
Evans. NTIS No. PB—85—164 275. Coat §22,00
28. Control of Volatile Organic Compound Emissions from Manufacture
of High-Density Polyethylene, Polypropylene, and Polystyrene
Resins, EPA-450/3-83-008, November 1983. (Group III) Engineer:
William Johnson. HTIS Ho. PB-84-134 600
29. Fugitive Emission Sources of Organic compounds - Additional
Information on Emissions, Emission Reductions, and Costs, EPA-
450/3-82-010, April 1982. Engineer; k. c. Hustvedt. htis No.
PB-82—217 126. Cost S22.00
Address for HTTS
National Technical Information Service
5285 Port Royal Road
Springfield, Virginia 22161
(703)487-4650
Address for CPB/BPA
U. S. Environmental Protection Agency
Chemicals and Petroleum Branch/ESD (MD-13)
Research Triangle Park, North Carolina 27711
D—23
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tfrti mil
CONTROL TECHNOLOGY DOCUMENTS
[Documents Which Provide Background Information
on Controls Only - Not RACT]
1. Alternative Control Technology Document - Haloqenated Solvent
Cleaners - EPA-450/3-89-030, August 1989.
2. Reduction of Volatile Organic Compound Emissions from the
Application of Traffic Markings - EPA-450/3-88-007, August 1988
3. Alternative Control Technology Document - Ethylene Oxide
Sterilization/Fumigation Operations - EPA-450/3-89-007, March
1989
4. Reduction of Volatile Organic Compound Emissions from Automobile
Refinishing - EPA-450/3-88-009. NTIS No. PB-89-148 282
5. Alternative Control Technology Document - Organic Waste Process
Vents, EPA-450/3-91-007, December 1990
6. Technical Guidance - Stage II Vapor Recovery Systems for Control
of Vehicle Refueling Emissions at Gasoline Dispensing Facilities,
EPA-450/3-91-022a, November 1991. NTIS No. PB-92-132844
ArtrtreM for MTTS
National Technical Information Service
5285 Port Royal Road
Springfield, Virginia 22161
(703)487-4650
Addr«M for CPB/gPA
U. S. Environmental Protection Agency
Chemicals and Petroleum Branch/ESD (MD-13)
Research Triangle Park, North Carolina 27711
D-24
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CONTROL TECHNIQUES GUIDELIKE DOCUMENTS TO BE DEVELOPED
(IN ACCORDANCE WITH CLEAN AIR ACT AMENDMENTS OF 1990)
SOMCI* Distillation
SOCMI Reactor Vents
Batch Operations
Volatile Organic Liquid Storage
Wastewater3
Plastic Parts - Business Machines
Plastic Parts - Other
Hood Furniture
Offset Lithography
Autobody Refinishing
Cleanup Solvents
Aerospace
Shipbuilding and Repair
OTHER TITLE I ACTIVITIES
Marine Tank Vessel Loading Rule
Architectural and Industrial Coatings Rule
Consumer and Commercial Products Report to Congress
Information Contact;
U.S. Environmental Protection Agency
Chemicals and Petroleum Branch (MD-13)
Research Triangle Park, North Carolina 27711
1 SOCHI - Synthetic Organic Chemical Manufacturing Industry
2 Wastewater includes: Organic Chemicals, Plastics, Synthetic Fibers,
Pesticides, Pharmaceutical, and Hazardous Waste facilities
D-25
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April 1992
Control Technology Center . i'C)
Reports Addressing VOC Emission. *nd Controls
'Hf-WO,' EPA-400/8-91-21U, P992-135904 (aanual); EPA-600/8-91-21lb (softuore); P992-501212 (aonual and MftMar*)
¦Handbook: Control Tochnolofioe for Kinrdwi Air Mllutanta" (MP tonal), EPA-62S/4-91-014
¦Caiasion Factor* for Iron Fow+iea-Crltcrta and Toxic Pollutants," EPA-400/2-90-044, PW0-2M743
¦Evoluatlon of VOC (aisstona froa Nootod Raofinf Aapholt,' EPA-400/2-91-041, P992-115286
¦Mmaaant of VOC Eaiaaiona and Their Control froaBakersYaaot Manufacturing Facilltiea, EPA-450/3-91-027, P992-145408
^audar Casting Technology Update,• EPA-450/3-89-CS3, WO-1273*1
"tadiation curablo Coatinga," IPA-600/2-91-0J5. P991-219550
¦teat Oeaonetrated Control Technology for Iragftic Arts," EPA-450/3-91-008, *991-168427
¦AVB Export Systaa for Steaa Stripping Calculationa: Uaara' Merual," EPA-450/3-90-003
¦Indiatrial Maotoaatar VOC Eiiul«na--hck|r«i
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA 453/R-92-018
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE ANO SUBTITLE
Control Techniques for Volatile Organic
Compound Emissions from Stationary Sources
5. REPORT OATE
December 1992
6. PERFORMING ORGANIZATION CODE
7. AUTHORIS)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME ANO AOORESS
Office of Air Quality Planning and Standards
10. PROGRAM ELEMENT NO.
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME ANO AOORESS
Office of Air and Radiation
13. TYPE OF REPORT AND PERIOD COVERED
Final
U. S. Environmental
Washington, DC 20460
Protection Agency
14. SPONSORING AGENCY COOE
EPA/200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This document is a summary document containing general
information on sources of volatile organic compound (VOC)
emissions, applicable control techniques, and the impacts
resulting from control applications. It references other
documents which contain much more detailed information on
individual sources and control techniques. This is the third
edition of a report originally published by the Department of
Health, Education, and Welfare (HEW) titled, "Control Techniques
for Hydrocarbon and Organic Solvent Emissions from Stationary
Sources (AP-68)." The first edition was published in March 1970
by the National Air Pollution Control Administration, a part of
HEW.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATl Field/Group
Air Pollution
Volatile Organic Compounds
Air Pollution Contro
1 13b
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS iTIus Report/
Unclassified
21. NO. OF PAGES
471
Unlimited
20. SECURITY CLASS
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