EPA-450/2-77-034
December 1977
(OAQPSNo. 1.2-088)
GUIDELINE SERIES
CONTROL OF VOLATILE
ORGANIC EMISSIONS
FROM EXISTING
STATIONARY SOURCES
VOLUME V: SURFACE
COATING OF LARGE
APPLIANCES
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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The following is an abstract of a longer document, presenting
Reasonably Available Control Technology (RACT) for Surface Coating of
Large Appliances. In order to limit the size of the Guideline Series,
the actual RACT documents have not been incorporated? but rather,
sent out under separate cover to those agencies receiving the Guideline
Series. Agencies and individuals may request a copy of this document
by providing the title and OAQPS identification number to the appropriate
Regional Office Librarian.
Title: Control of Volatile Organic Emissions from Existing Stationary
Sources - Volume V: Surface Coating of Large Appliances
Authors: Vera N. Gallagher, Emission Standards and Engineering
Division, OAQPS
William Vatavuk, Strategies and Air Standards Division,
OAQPS
Date: December 1977
OAQPS No: 1.2-088
Summary:
This document describes the large appliance industry, provides
emission limits representing RACT, identifies sources and types of
volatile organic compound emissions from the surface coating operations,
and applicable techniques and costs of reducing these emissions. It
also discusses monitoring techniques and enforcement aspects for
coatings low in organic solvents and add-on control techniques, and
provides examples in determining if a coating proposed for use by a
large appliance facility will meet the recommended emission limit.
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EPA-450/2-77-034
(OAQPS No. 1.2-088)
CONTROL OF VOLATILE ORGANIC
EMISSIONS FROM EXISTING
STATIONARY SOURCES
VOLUME V: SURFACE COATING
OF LARGE APPLIANCES
Emissions Standards and Engineering Division
Chemical and Petroleum Branch
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 2771]
December 1977
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OAQPS GUIDELINE SERIES
The guideline series of reports is being issued by the Office of Air Quality
Planning and Standards (OAQPS) to provide information to state and local
air pollution control agencies; for example, to provide guidance on the
acquisition and processing of air quality data and on the planning and
analysis requisite for the maintenance of air quality. Reports published in
this series will be available - as supplies permit - from the Library Services
Office (MD-35), U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina 27711; or, for a nominal fee, from the National
Technical Information Service, 5285 Port Royal Road, Springfield, Virginia
22161.
Publication No. EPA-450/2-77-034
(OAQPS No. 1,2-088)
11
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PREFACE
This document is one of a series designed to inform Regional, State
and local air pollution control agencies of techniques available for
reducing emissions of volatile organic compounds (VOC) from existing
stationary sources. It deals with the surface coating of large appliances.
For the purpose of this document, "large appliances" include doors, cases,
lids, panels and interior support parts of residential and commercial
washers, dryers, ranges, refrigerators, freezers, water heaters, dish
washers, trash compactors, air conditioners and other similar products,
The report describes the industry, identifies the sources and the types
of VOC emissions, and the available methods and costs for minimizing these
emissions. It also discusses techniques for monitoring the VOC content
of surface coatings for purposes of determining compliance with anticipated
regulations. More detailed discussions on coatings low in organic solvent
and add-on control technologies are found in "Control of Volatile Organic
Emissions from Existing Stationary Sources - Volume I:Control Methods for
Surface Coating Operations." ASTM test methods for monitoring the solvent
content of coatings are summarized in a previous report titled "Control
of Volatile Organic Emissions from Existing Stationary Sources - Volume II:
Surface Coating of Cans, Coil, Paper, Fabric, Automobiles and Light Duty
Trucks,"2
The table below provides emission limitations that represent the
presumptive norm that can be achieved through the application of reasonably
available control technology (RACT). Reasonable available control technology
is defined as the lowest emission limit that a particular source is capable
of meeting by the application of control technology tha.t is reasonably
?EPA-450/2-76-028, November 1976, (OAQPS No. 1.2-067)
EPA-450/2-77-008, May 1977, (OAQPS No. 1.2-073)
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available considering technological and economic feasibility. It may
require technology that has been applied to similar, but not necessarily
identical source categories. It must be cautioned that the limits reported
in this Preface are based on capabilities and problems which are general to
the industry, but may not be applicable to every plant.
Affected Facility
Recommended Limitation
Prime, single or topcoat
application area, flashoff
area and oven
kg of organic
solvent per
1iter of coating
-(minus waterh
0,34
Ibs of organic
solvent per gal
of coating
(minus water)
2.8
This emission limit is based on the use of low organic solvent coatings.
It can be achieved with coatings which contain at least 62 volume percent
solids or any water-borne equivalent. This would result in approximately an
80 percent reduction in VOC emissions over conventional organic-borne
coatings which contain about 25 volume percent solids. An equivalent reduction
can also be achieved by use of add-on control devices such as incinerators or
carbon adsorbers. Even greater reductions, 90 percent and more, can be
achieved by conversion to electrodeposited water-borne or powder coatings.
Since the large appliance industry includes a wide variety of products, there
is no single control technique that can be considered best for the entire
industry. It is believed that most facilities will seek to meet future
regulations through the use of coatings which are low in organic solvent
rather than resort to add-on control techniques.
IV
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GLOSSARY
Prime coat means the first film of coating applied in a two-coat operation.
Topcoat means the final film of coating applied in a two-coat operation.
Interior single coat refers to a single film of coating applied to internal
parts of large appliances that are not normally visible to the user.
Exterior single coat is the same as the topcoat but is applied directly to
the metal substrate omitting the primer application.
Faraday caging means a repelling force generated during electrostatic
spraying of powders in corners and small enclosed areas of metal substrate.
Blocking agent means an agent which is released from the polymer matrix
during the curing process. It is normally an organic radical and splits
from the monomer or oligmer.at a predetermined temperature, thereby
exposing reactive sites which then combine to form the polymer. Such
reactions during the curing process may release additional volatile organic
compounds into the atmosphere.
Low organic solvent coating refers to coatings which contain less organic
solvents than the conventional coatings used by industry. Low organic
solvent coatings include water-borne, higher-solids, electrodeposition
and powder coatings.
v
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CONVERSION FACTORS FOR METRIC UNITS
Equivalent
Metric Unit Metric Name English Unit
Kg kilogram (103grams) 2.2046 Ib
liter liter 0.0353 ft3
dscm dry standard cubic meter 35.31 dry standard ft.
scmm standard cubic meter per min. 35.31 ft /min.
Mg megagram (10 grams) 2,204.6 Ib
metric ton metric ton (10 grams) 2,204.6 Ib
In keeping with U.S. Environmental Protection Agency policy,metric
units are used in this report. These units may be converted to common
English units by using the above conversion factors.
Temperature in degrees Celsius (C°) can be converted to temperature
in degrees Farenheit (°F) by the following formula:
t°f = 1.8 (t°c) + 32
t°f = temperature in degrees Farenheit
t°c = temperature in degrees Celsius or degrees Contigraae
VI
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TABLE OF CONTENTS
PREFACE , iii
GLOSSARY. .,..,, vi
CONVERSION FACTORS FOR METRIC UNITS vii
1.0 SOURCES AND TYPES OF EMISSIONS 1-1
1.1 General Discussion. .,....,.. .... 1-1
1.2 Processes and Emission Points 1-1
1.3 References 1-12
2.0 APPLICABLE SYSTEMS OF EMISSION REDUCTION. .... 2-1
2.1 Electrodeposition 2-2
2.2 Water-Borne Coatings. ....... ,.....,, 2-3
2.3 Powder Coatings 2-4
2.4 Higher-Solids Coatings 2-5
2.5 Carton Adsorption , 2-6
2.6 Incineration , ,,..,.,. 2-8
2.7 References 2-10
3.0 COST OF CONTROL OPTIONS 3-1
3.1 Introduction 3-1
3.1,1 Purpose 3-1
3,1.2 Scope , 3-1
3.1.3 Use of Model Plants 3-3
3.1,4 Bases for Capital Cost Estimates ,...,.,.,.. 3-3
3.1.5 Bases for Annualized Cost Estimates 3-5
3,2 Control of Solvent Emissions from Large Appliance
Coating Operations , , . , , , 3-6
3.2.1 Control Costs 3-6
3.3.3 Cost Effectiveness , , 3-12
3,3 References 3-18
4,0 ADVERSE AND BENEFICIAL EFFECTS OF APPLYING TECHNOLOGY 4-1
4.1 Electrodeposition , , . 4-1
4,2 Water-Borne Coatings .,.........,, 4-2
VII
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4,3 Powder Coatings 4-4
4,4 Higher Solids Coatings 4-6
4.5 Carbon Adsorption 4-7
4.6 Incineration 4-8
4.7 References 4-10
5.0 MONITORING TECHNIQUES AND ENFORCEMENT ASPECTS 5-1
APPENDIX A - SAMPLE CALCULATIONS OF CONTROL OPTIONS A-l
References A-5
vm
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1.0 SOURCES AND TYPES OF EMISSIONS
This chapter provides a general introduction to the large appliance
industry, the methods by which conventional coatings are applied, and
the volatile organic solvent (VOC) emissions which can be expected
from these coatings.
1.1 GENERAL DISCUSSION
A large appliance plant typically manufactures one or two different
types of appliances and contains only one or two lines. The lines may
range from 1200 to 4000 meters (3/4 to 2 1/2 miles) in length and operate
at speeds of 3 to 15 meters (10 to 50 feet) per minute.
Coatings are a critical constituent to a large appliance. It must
protect the metal from corrosion by its resistance, moisture, heat, detergent
and sometimes the outdoor elements, Coatings for each type of appliance
have special requirements and contains unique properties because each will
be exposed to somewhat different corrosive elements. The coatings must also be
durable and excellent adhesion properties to avoid peeling or chipping
which would then expose the metal to corrosive attack. Finally,
the coatings that are applied on home appliances must have esthetic appeal.
1.2 PROCESSES AND EMISSION POINTS
The coatings typically applied on large appliances are epoxy, expoy-
acrylic, acrylic or polyester enamels. Coatings containing alkyd resins
have also been used in some cases. The single coat for interior parts
1-1
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and primers are applied in one or two colors, and the single coats for
exterior parts and topcoats in several colors. Sometimes two variants
of the same color are used on the topcoat or exterior single coat to
provide a shaded effect on the appliance. A black asphalt-type gilsonite
coating is also applied on some large appliance parts to provide additional
moisture resistance and to act as a sound deadener. Prime and interior
single coat materials are applied at 25 to 36 volume percent solids, and
topcoat and exterior single coats at 30 to 40 volume percent solids. Many
coatings are purchased at higher solids contents but are thinned
with solvents before application. Quick-drying lacquers are also applied
on some large appliances to repair scratches and nicks that occur during
assembly; they are applied sporadically at approximately 20 volume percent
solids, and often amount to approximately one quart per shift. Because
of the small quantity used, these coatings are exempt from being required
to meet any emission limits.
Coatings applied on large appliances may contain mixtures of 2 to 15
different solvents. The typical solvents used are esters, ketones,
aliphatics, alcohols, aromatics, ethers and terpenes. The solvents used
to carry the solids to the substrate are blended to control viscosity and
evaporation rate as well as other properties to assure a continuous
durable film and a lusterous appearance.
1-2
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Each large appliance assembly line tends to be unique because of its
age, the different types and styles of large appliances manufactured and
the type of coating application equipment. Figure 1.1 portrays features
common to many large appliance lines. The following comments summarize
the steps in the process.
Cases, doors, lids, panels and interior parts for large appliances
are stamped from sheet metal and hung on overhead conveyors. The parts
are transported to the cleaning and pretreatment sections typically
located on the ground floor of the plant. The parts are cleaned with
an alkaline solution to remove grease, mill scale or dirt, rinsed,treated
with zinc or iron phosphate, rinsed again, and treated with chromate if
iron phosphate is used. The parts are then dried at 300-400°, typically
in a gas fired oven and cooled before coating. The prime coat, if required,
or interior single coat may be applied by dipping, flowcoating or by
electrostatic spraying and varies in thickness from 0.5-1.0 mils. Sometimes
thp cured flowcoat is followed by a manual spray operation for
touchup. Dip coating is typically used for small parts while flow or
spray coating are used for larger parts.
On some lines the parts enter a prime preparation booth to check the
pretreatment. Here the parts can he sanded and tack-ragged (wiped)
to provide an even finish. Such treatment is usually necessary only for
exterior parts such as doors, lids, cases and panels, where a smooth
finish is important.
1-3
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DIRECT TO METAL TOPCOAT
FROM SHEET METAL MANUFACTURING
EXTERIOR PARTS
(CASES. LIDS AND ODORS)
INTERIOR
PARTS
CLEANSING AND
PRETREATMENT
SECTION
FLASHOFF
(OPEN OR TUNNELED)
FLASNOFF
(OPEN OR TUNNELED)
PRIME DIP
TO ASSEMBLY
1-1 Diagram of a large appliance coating line.
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If the prime or single coat is dip coated, the coating is contained
in a continuously agitated tank to prevent settling. As the parts move
on the conveyor, they are immersed into the coating, withdrawn and the
excess coating is allowed to drain back into the tank. Viscosity is
critical in dip coating. If the viscosity is too low, the coating film
will be too thin, if it is too high, the coating film will be too thick,
resulting in high coating usage and drip marxs. The dip coating tank
and drain board may be completely enclosed and vented by roof fans,
or may have a ventilation system adjoining the tank and drain board,
Ventilation rates ranae from 30 to 230 scmm (1000-8000 scfm) at
VOC concentrations of 1 t.o 3 percent, of the Inwer explosive limit
(LED.
In the flowcoating process, the parts are moved by a conveyor through an
enclosed booth. A series of stationary or oscillating nozzles, located
at various angles, shoot out streams of coating which flow over the part.
Excess coating,which drains into a sink on the bottom of the booth, is
filtered and recycled. As in dip coating, the viscosity of the coating
is critical. Coated parts may enter a flashoff tunnel to allow time for
the coating to flow out properly. After being baked in the oven, the flow-
coated parts may be manually touched-up in a spray booth with conventional
spray equipment. The exhaust from the flowcoater and tunnel may range from
28 to 1841 scmm (1000-65,000 scfm) with VOC concentrations from 1-5 percent
LEL. The exhaust from the manual touch-up spray booth may range from 425
to 850 scmm (15,000-30,000 scfm) depending on booth and size of the
openings. VOC concentrations will vary from 0 to 1 percent LEL because
these touch-up coatings are applied sporadically as needed. Total emissions
are usually too low, less than a liter each day, to warrant control.
1-5
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Some primers are applied by automatic electrostatic spraying with
disc, bell or other types of spray equipment. As the paint particles
exit in a spray, they are negatively charged, and are attracted to the
grounded appliance part, coating it. Thi^ method is about 70-80 percent
efficient in transfer efficiency and provides jome reduction in VOC
emissions over conventional spray equipment. (Conventional spray
equipment is about 40-70 percent efficient.) Primer touch-up is sprayed
manually.
Spray coating is performed in a spray booth to contain any overspray,
to prevent plant or outside dirt coming in contact with the paint, and to
control the temperature and humidity at the ooint of application. Down-
draft and side-draft spray booths areused in the large appliance industry.
Each may be 15.24m (50 feet) long. The spray booths are usually equipped
with dry filters or a water wash to trap any overspray. The make-up air for
a spray booth is often kept at about 24°C (75°F) and 35 to 50 percent
relative humidity during the winter months for proper coating application.
Dryness in the spray booths will cause arcing due to electrostatic spray
equipment. During the other months, however, spray booth controls are not
necessary and only different thinners are needed in the coatings to
compensate for the different weather conditions. Air flow from the spray
booths range from 2200 to 3500 scmm (80,000-125,000 scfm) for automatic
and 550 to 1700 scmm (20,000-60,000 scfm) for manual spray applications.
The minimum air velocities in the manual spray booths ure prescribed by
OSHA for the safety of workers and are a function of the cross sectional
area of the spray booth.
1-6
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The prime and single coated large appliance parts often go through
about a seven minute flash-off period to allow the solvents to rise slowly
in the coating film to avoid popping of the film as the coating is baked.
The flash-off area maj- be contained in a "vapor release" or flash off
tunnel. The exhaust from the tunnel is about 60 to 230 scmm (2000-8000
scfm) with a VOC concentration of 1 to 5 percent LEL.
Typically, coated parts are baked for about 20 minutes at 180° to
230°C (350-450°F) in a multi-pass oven. An air velocity of 15 to 45 mpm
(50 to 150 fpm) is often required through these openings to prevent the
effluent from spilling Into the working area. Since the entry and exit
openings of the ovens are sized to accommodate the largest parts to be
coated, this often results in exhaust rates higher than what would be
required to merely maintain the oven at 25 percent LEL, as recommended by
many insurance companies. (Some insurance companies allow operation at 50
percent LEL with proper monitoring equipment.) Air curtains at oven openings
permit reduction of the air velocity to about 15 mpm (5p fpm). Other factors
which affect the exhaust rate are the humidity, air flow requirements for
proper curing, and condensation/corrosion problems of interior oven sur-
faces. Consideration of these factors have resulted in oven exhaust rates
from 280 to 1400 scmm (10,000-50,000 scfm) and VOC concentrations as low as
5 percent LEL or less.
Before the parts are topcoated, they are checked for smoothness, manually
sanded if necessary, "tack-ragged", and retouched with a manual spray gun.
Topcoat or exterior single coat (direct-to-metal topcoat) is usually applied
by automated electrostatic discs, bell or other type of spray equipment at
coating thickness of 1.0 to 1.5 mils. Such electrostatic spray equipment
is usually about 70 to 85 percent efficiency in transfer efficiency.
1-7
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The spinning disc oscillates vertically, coating the part as it moves around
the disc. There may be as many as 8 discslocated in sequence. The bells
or other spray equipment are located at various angles on each side and
bottom of the spray booth, coatina the Darts as thpv move on an
overhead conveyor, There may be as many as 50 sprayers for a single top-
coat application, Topcoat is usually applied in many colors, Topcoat
color changes are accomplished after automatically flushing the system
with solvent and take only a few seconds. The flushing solvent can be
returned to a solvent container for reuse or disposal or be sprayed directly
into the spray booth. Topcoated parts then move to a manual spray application
for touching up and applying any highlighting tones.
Topcoat and exterior single coat are applied in side-draft or down-draft
spray booths usually equipped with a water wash. The air is cleansed to
remove any dust particles. The air during the winter months is typically
maintained at temperatures of 20 to 30°C (70-85°) and 35-50 percent relative
humidity to prevent arcing of electrostatic equipment. During the other
months, the thinners are varied to compensate for the weather conditions,
The automatic spray booth exhaust will vary from 2250 to 3500 scmrn (80,000
to 125,000 scfm) at concentrations of 0,5 to 1 percent LEL, whereas exhaust
from the manual spray booths (smaller in size) is prescribed by OSHA and may
vary from 550 to 1700 scmm (20,000 to 60,000 scmm) at concentrations of 0,08
to 0,5 percent of the LEL. (OSHA regulations specify minimal allowable conditions.)
The topcoated part then undergoes a 10 minute flashoff period to allow
the solvents to rise in the coating film. The flashoff area is typically
enclosed, and the exhaust rate is about 60 to 230 scmm (2000 to 8000 scfm)
with VOC concentrations of 1 to 5 percent LEL.
1-8
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The topcoat is finally baked for 20 to 30 minutes at 140 to 180°C
(270-350°F) in a multi-pass oven. The exhaust may range from 280 to
1400 scmm (10,000-50,000 scfm) depending on the size of the opening through
which the parts enter. VOC concentrations range from 5 to 10 percent LEL.
The inside of many exterior large appliance parts are sprayed with
gilsonite for additonal moisture resistance and for sound deadening, This
coating is typically sprayed at about 25-30 volume percent solids.
In summary, organic vapor emissions from the coating of large appliances
are emitted from application areas, flashoff tunnels, and ovens, Estimates
of the relative amounts of VOC emissions from these sources, are listed in
Table 1.1.
Figure 1,2 displays the relationshop between VOC emissions and flowrate
with isopleths of organic concentration (LEL), Note that for a given
emission rate, the exhaust flowrate at 1 percent LEL concentration is 10
times that at 10 percent LEL. The flowrate and resulting concentrations are
a function of many factors-, open or enclosed spray booths, dip or flowcoater,
flashoff area or an oven. Unfortunately, flowrates are often designed
for the most difficult parts to be coated by the line and may be excessive
for the typical piece.
1-9
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Table 1.1 PERCENT DISTRIBUTION OF VOC EMISSIONS FROM LARGE
APPLIANCE COATING LINES
Application Application
Method and Flashoff Oven
Dip 50 50
Flow coat 60 40
Spray 80 20
The base case coating is applied at 25 volume percent solids, 75 percent organic solvent
organic solvent which is equivalent to a VOC emission factor of 0.66 kg of organic solvent
emitted per liter of coating (5.5 Ibs/gal) minus water,
-------
u
ro
o
to
QJ
100
90
80
70
60
50
40
30
20
10
0
T r
i I i r
20 40 60 80 100 120 140 *160 180 200
Ibs of organic solvent (VOC) emitted per hour
Figure 1.? Relationship between VOC emissions, exhaust flowrates
and VOC concentrations.
1-11
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1.3 REFERENCE
1. Connors, E.W., Jr., General Electric Company. Letter to V,N. Gallagher
in comment of the large appliance draft document. Letter dated
October 10, 1977.
1-12
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2.0 APPLICABLE SYSTEMS OF EMISSION REDUCTION
This chapter discusses coatings low in organic solvents and add-on
equipment for the control of VOC from conventional coating applications
used in the large appliance industry. It also discusses other methods of
applying coatings (powder and electrodeposition) which result in low
VOC emissions.
Table 2.1 SUMMARY OF APPLICABLE CONTROL TECHNOLOGY FOR LARGE
APPLIANCE DOORS, LIDS, PANELS, CASES.AND INTERIOR PARTS
Control Technology
Water-borne
(Electrodeposi ti on)
Water-borne (Spray, Dip,
or Flowcoat)
Powder
Higher solids (Spray)
Carbon adsorption
Incineration
Application
Prime or interior single
coat
All applications
Top, exterior, or interior
single coat
Top or exterior single coat
and sound deadener
Prime, single or topcoat
application,and flashoff
areas
Ovens
Percent Reduction
In Organic
Emissions
90-958
70-90a
95-99a
60-803
90b
90b
The base case against which these percent reductions were calculated is a
high organic solvent coating which contains 25 volume percent solids and
75 percent organic solvent. The transfer efficiencies for liquid coatings
were calculated to be 80 percent, for powders about 93 percent,and for
electrodeposition about 99 percent.
This percent reduction in VOC emissions is only across the control device,
and does not take into account the capture efficiency.
2-1
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2.1 ELECTRODEPOSITION
Many large appliance manufacturers have chanqed to the electrodeposition
technique for applying the prime coat on large appliance exterior parts
(doors, panels, lids and case) and for applying a single coat on large
1234
appliance Interior parts. ' ' ' The main reason for switching was increased
corrosion protection and increased detergent resistance, especially in
clothes washers and dryers. The electrodeposition coatings may be applied
at 0,5 to 1.0 mils thickness; film tnickness is adjusted by voltage and
immersion time.
The dry-off oven may be omitted after cleansing of the large
appliance parts if iron phosphate pretreatment is used. An additional rinse
of deionized water is necessary. After rinsing the parts are grounded and
immersed into a coating bath containing about 8 to 15 volume percent solids
and 2 to 4 volume percent organic solvent, the balance being water. A direct
current is applied in the bath, causing the solids to become attached to the
grounded metal part. The coating may be applied either by anodic or cathodic
electrodeposition. As the parts emerge from the bath, the applied coating
consists of approximately 90 volume percent solids and 2 to 4 volume percent
organic solvent. This provides about 90-95 percent reduction in organic e
emissions over conventional processes. The parts are then rinsed in several
stages to eliminate excess paint particles. The coating is then baked in
an oven at about 200°C (400°F), VOC emissions from an EDP line are emitted
from the coating bath, the rinsing stages (if the ultrafiltrate is directed
to the rinse instead of being purged into the sewer), and the oven, In
converting to electrodeposition, the flashoff tunnel can be eliminated, and
the oven exhaust mav be reduced due to the substantial decrease in organic
Solvent. This result*; in arlrlitinnal pnornv/
2-2
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For further technical details on the use of electrodeposition coating
technoloqy, see Volume I, Section 3.3,1.
2.2 WATER-BORNE - SPRAY, DIP, OR FLOWCOAT
Water-borne coatings have similar application characteristics to
organic solvent-borne coatings, thus conversion to water-borne coatings
does not often require installation of new application equipment. Organic
solvent-borne systems such as flow or dip coaters have been successfully
converted to water-borne coatings. ' However, some alterations usually are
necessary to protect equipment from corrosion, provide a longer flashoff
area, or to control the humidity in application and flashoff areas. Water-
borne coatings may be sprayed electrostatically providing the entire system
is electrically isolated Some small electrostatic lines have been converted
to water-borne coatings. Larger lines, however, may have difficulty converting
to water-borne coatings, because of electrostatic spray equipment used or
because the storage areas from where the coatings are pumped may be thousands
of feet away from the application areas, making electrical isolation difficult
891011
and sometimes financially impractical. ' ' '
Since water has a single boiling point, and a slower evaporation rate
than most organic solvents, it is often necessary to include some organic
solvents to temper the evaporation rate, provide the coating with necessary
properties, and to provide film coalescence. A reduction of 70-90 percent
in VOC emissions may be achieved by switching to water-borne coatings. The
actual reduction will depend on the composition of the water-borne coating
replacement. Further technical details on the use of water-borne coatings
12
may be found in Volume I, Section 3.3.1 and 3.3.5.
2-3
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2.3 POWDER
Powder coatings are presently being applied (often as a replacement for
porcelain) for topcoats on some range parts, and as Interior single coats
for refrigerator liners and some washer and dryer parts,13§l4'15 These
would usually be applied by electrostatic spraying because dipping would
produce excessive film thickness, About 2-4 mils film thickness may be
achieved by spraying, After application of the coating, the powder particles
are completely melted in the oven to form a continuous, solid film.
Although powders appear to be essentially all solids, they do contain
entrapped organics which are released during the curing process, often as
a result of cross-linking reactions.
Applying powder by electrostatic spray uses almost the same technique as
do solvent-borne coatings, and may be done either manually or automatically.
As the particles emerge from the spray gun, they become charged, and are
subsequently attracted to the grounded metal part, Powder coatings do not
coat well within small recesses. This problem may be reduced or eliminated
by preheating the parts. However, this will result in thicker films of coating,
Powder overspray can be reclaimed providing up to a 98 percent coating
utilization. Color changes, if the powder is recovered, require that the
booth and recovery units be cleaned to avoid color contamination. If the
overspray powders are not recovered, color change periods may be shortened.
However, this reduces the coating utilization efficiency to about 60 percent.
2-4
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To shorten the time rpnuirprl for a color chanapover, some facilities
have several recovery units available that mav easilv HP attar>pH tn
sprav booths. Others have Installed spveral mnhile spray booths with
associated recovery pnulnment. .
Powder coatings do not require flashoff tunnels, and are baked at
temperatures of 180 to 230°C (300-450°F). Since the concentrations of VOC
are almost insignificant compared to conventional coatings smaller ovens
may be installed with attendant reductions in air flow. Further technical
details on the application of powder coatings may be found in Volume I,
Section 3.3.3 and 3.3.5.18
2.4 HIGHER SOLIDS (SPRAY)
The reduction in volatile organic emissions achievable by switching to a
coating containing higher solids may range from 50 to 80 percent, depending
on the original and replacement coatings, Medium-high solids coatings (45-
50 volurre percent solids) are being applied as topcoats on some refrigerators
with prospects of even greater solids content as heated application equipment
1 g
can be perfected. Higher solid (50-60 volume percent) gilsonite
coatings can also be applied for sound deadeners.
Higher solids coatings can be applied most efficiently by automated
electrostatic spraying although manual and conventional spraying techniques
can also be used. Some increase in energy may be required to increase the
pressure of the spray gun, the temperature of the coating or power of the
electrostatic spray equipment in order to pump and atomize these coatings
due to their higher viscosities. Transfer efficiencies of higher solids
coatings are often better than those of conventional coatings, particularly
20
when sprayed electrostatically.
2-5
-------
As the solids content 1s increased, less organic solvent is evaporated
for each dry mil of coating. This can allow a reduction on the amount of
air through the spray booth required to keep the coating particles
and volatile organics away from the coating personnel. This will result
21
in an energy savings. The lower solvent content also enables the air flow
from the flashoff tunnel and oven to be reduced.
Further technical details on the use of high-solids coatings may be
found in Volume I, Section 3.3.2.22
2.5 CARBON ADSORPTION
As discussed in Chapter 1, at least two thirds of the volatile compounds
from large appliance coatings are emitted from the application and flashoff
areas. The remainder is emitted from the ovens The use of carbon
adsorption for the application and flashoff areas can reduce VOC emissions
from those areas by 75-90 percent, depending on the capture efficiency into
the control device.
Carbon adsorption is considered a viable control option for the appli-
cation and flashoff areas although there are no known carbon adsorp-
tion systems in plants which manufacture large appliances.
Adsorption is technically feasible for these applications 1n that no new
23
inventions are required for its implementation. Pilot studies, however,
may be necessary before this control technology is installed,
The size of a carbon adsorption unit is dependent on the exhaust flow
rate, VOC concentration, and the desorption period. The flowrates and
concentrations will vary with each application because of the variety of
large appliance parts coated. Flow rates may range from 30 scmm (1000 scfm)
2-6
-------
for a snail dip coater to 4500 scmm (160,000 scfm) for topcoat or exterior
single coat spray booths, and from 150 to 280 scmm (5000 to 10,000 scfm) for
a flashoff tunnel. Concentration of volatile organic compounds from a
down-draft booth are about 0.25 to 1 percent of the LEL; from a flowcoater
about 1 to 3 percent of the LEL, and from the flashoff tunnel about 1 to 5
oercent of the LEL. If coatings are applied sporadically, the concentration of
solvents in the exhaust will vary during any given time period from 0 to 1
percent LEL. The size of the carbon adsorber can be minimized (thus reducing
capital and operating costs) by routing the discharge air from the areas where
the coating is applied manually to those applied automatically. Particulate
matter from overspray is often captured at about 95 percent efficiency by
dry filters, or by water or oil wash curtains and should not coat the carbon
24
bed. Additional filtration may be necessary, however, if the residual
particulate is significant enough to pose a threat to the adsorber bed.
Flashoff areas are often enclosed. However, on lines where they are
not, they will have to be enclosed. The flow rates and concentrations of
exhaust from the flashoff areas will largely depend on the configuration
of the coating line. If the coating application areas are located on the
first floor of the plant, for example, and the ovens are mounted on the roof,
enclosure may be very difficult. In other cases, the application area may
be located near the oven, and enclosing the flashoff area would be less
difficult, In some situations, the negative pressure maintained in the oven
will entrain the solvent laden flashoff air into the oven.
Further details on the use of carbon adsorption may be found in
Volume I, Section 3.2.1,25
2-7
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2.6 INCINERATORS
There are no serious technical problems associated with the use of
either catalytic or non-catalytic Incinerators on large appllnace facilities.
Incineration has been used to reduce VOC emissions from large appliance
ovens.
Incinerators may be less costly and perhaps more efficienct than carbon
adsorbers for reducing organic emissions from many large appliance baking
ovens for several reasons: (1) the high temperature oven exhaust (150 to
230°C) would have to be cooled before entering a carbon bed, This would result
in high energy usage; (2) although additional energy is required to being
the oven exhaust near incineration temperature, this energy can be minimized
by the use of primary heat exchangers; (3) the concentration of organic
vapors is often higher in the oven exhaust providing some additional fuel
for the incinerator; (4) particulate and condensible matter from volatilization
and/or degradation of resin which often occurs in higher temperaturebaking
ovens will not affect an incinerator. It could coat a carbon bed and render
it inefficient even when a filter is used.
It will normally be desirable (but not always possible) to incorporate
heat recovery systems (aside preheating of the oven exahust) to reduce fuel
consumption to a minimum level. Incinerator exhaust heat may be recovered
for use in many areas, for example, the cleansing and pretreatment sections,
the ovens and for plant and spray booth heating during the winter months.
Incineration for application and flashoff areas is also a viable control
option if sufficient heat recovery can be used to keep fuel consumption at
an acceptable level.
2-8
-------
Otherwise, incineration of ambient temperature, low concentration gas streams
is energy intensive.
Further technical details on the use of incineration may be found in
Volume I, Section 3.2.2.26
2-9
-------
2.7 REFERENCES
1. Schrantz, Joe, Frigidaire's Conversion to Cathodic Electrocoating.
Industrial Finishing, pages 26-29, April 1975,
2. Schrantz, Joe, Two-Pass Electrocoating at Maytag. Industrial Finishing,
pages 16-20, February 1975.
3. Kennedy, W. D., Major Appliance Electrocoat, Whirlpool Corporation.
Presented at the NPCA - Chemical Coatings Conference, Cincinnati, Ohio,
April 22, 1976.
4. Gallagher, Vera N., Environmental Protection Agency, Durham, North Carolina.
Reports of trips to appliance coating facilities, 1976.
5. OAQPS Guidelines, "Control of Volatile Organic Emissions from Existing
Stationary Sources - Volume I: Control Methods for Surface Coating
Operations", EPA-450/2-76-028, November 1976.
6. Water-borne Flow Coating and Dip, Products Finishing, pages 73-76,
February 1977.
7. McCormickj, Donald, Converting to Flow Coater to Water-Borne Paint,
Whirlpool Corporation, presented at the NPCA Chemical Coatings Conference,
Cincinnati, Ohio, April 23, 1976,
8. Provin, P.J., Maytag Company. Letter to V.N. Gallagher in comment of
draft document for large appliances. Letter dated October 4, 1977.
9. Goodgame, T.H., Whirlpool Corporation. Letter to V.N. Gallagher in comment
of the draft document for large appliances. Letter dated October 19, 1977.
10. Conners, E.W., Jr., General Electric Company, Letter to V.N, Gallagher
in comment of the draft document for large appliances. Letter dated
October 10, 1977.
11. Zimrot, Werner S., DuPont. Letter to V.N. Gallagher in comment of the draft
document for metal furniture, Letter dated August 25, 1977.
12. Volume I, Op. Cit.
13. Gallagher, Op. Cit,
14. Cecil, Larry W., Paper - Powder Coating at General Electric.
15. Maytag Painting Facility Conserves Energy, Industiral Finishing, pages
26-31, January 1977.
2-10
-------
16. LeBras, L.R., PPG Industries, Inc. Letter to V.N. Gallagher in
comment to first draft of metal furniture document. Letter dated
September 22, 1977.
17. Cecil, 0. Cit.
18. Volume I, Op. Cit.
19. Gallagher, Op. Cit.
20. LeBras, L.R., Op. Cit.
21. Lunde, Donald, I., "Aqueous and High-Solids Acrylic Industrial Coatings,"
High-Solids Coatings, Volume I, No. 2, April 1976.
22. Volume I, Op. Cit.
23. Johnson, W.R., General Motors Corporation, Warren, Michigan. Letter to
Radian Corporation commenting on "Evaluation of a Carbon-Adsorption-
Incineration Control System for Auto Assembly Plants," EPA Contract
No. 68-02-1319, Task No. 46, January 1976, dated March 12, 1976.
24. Johnson, W.R,, General Motors Corporation, Warren, Michigan, Letter to
James McCarthy dated August 13, 1976.
25. Volume I, Op. Cit.
26. Volume I, Op. Cit.
2-11
-------
3.0 COST OF CONTROL OPTIONS
3.1 INTRODUCTION
3.1.1 Purpose
The purpose of this chapter is to present estimated costs for control
of volatile organic compound (VOC) emissions from coating lines at existing
major appliance plants.
3.1.2 Scope
Estimates of capital and annualized costs are presented for controlling
solvent emissions from application areas and curing ovens in prime and topcoat
electrostatic spray coating lines. Two categories of VOC control techniques
considered applicable to a coating line using the conventional solvent-borne
coating have been costed: process modifications and add-on control systems.
The process modifications involve converting of a solvent-borne prime
or topcoat line to a coating system which emits lesser amounts of VOC. The
coating lines and the modifications costed for them are:
1. Prime:
(a) Electrodeposition (EDP)
(b) Water-borne
2. Topcoat:
(a) High-solids
(b) Water-borne
(c) Powder
3. Prime/Topcoat: Powder
(The coating processes are fully described in Chapter Two.)
3-1
-------
Also, note that the control costs for prime coating lines are also
applicable to single coat operations.
The add-on control systems costed are carbon adsorption and thermal
incineration with primary heat recovery. Adsorption is for controlling VOC
emissions from the topcoat spray booth and flash-off area, while incineration
controls the topcoat curing oven.
Detailed control cost estimates are developed for a model medium-sized
existing coating line, with annual production rates of 768,000, 1,536,000,
and 2,304,000 units/year (clothes washer cabinets), representing one, two,
2
and three-shift/day operation, respectively. Each unit requires 5.4 m
2 22
(58 ft ) of coating in the prime application, and 2.7 m (29 ft ) in the
topcoat application.
Cost-effectiveness ratios (i.e., incremental annualized cost per incre-
mental weight of VOC controlled) have also been computed for each of the
alternative control systems , at these model coating line production rates.
In general, these cost-effectiveness ratios only apply to the coating
of clothes washer cabinets. However, because the costs of add-on control
systems depend on parameters whose values are more or less independent of
the type of appliance being coated (e.g., volumetric flowrate), their
cost-effectiveness ratios could be applied to other products, such as
refrigerators. On the other hand, the design and, in turn, the costs of
coating equipment are more dependent on the appliance being coated.
Despite this, the process modification cost-effectiveness values may
(with caution) be extrapolated to other major appliances.
3-2
-------
3.1.3 Use of Model Plants
The cost analyses provided in this chapter rely on the use of model
coating lines, basically defined by a baseline annual production rate
(768,000 units/year) and three operating factors (1,920, 3,840, and 5,760
1 o
hours/year). ' No attempt has been made to provide detailed design
characteristics of the coating line process equipment.
An EPA contractor has furnished most of the technical parameters upon
which the control costs have been based. Listed in Table 3-1, these
parameters have been selected to reflect typical operating conditions at
actual major appliance plants. However, most of the process modification
costs have been furnished by industry members. ° Costs for add-on
control systems, however, have been primarily obtained from a compendium
8 9
of air pollution control costs, with appropriate revisions. '
Although model plant control cost estimates may differ with actual
costs incurred, they are the most convenient means for comparing the relative
costs of the alternative control measures.
3.1.4 Bases for Capital Cost Estimates
Each capital cost represents the total investment necessary for purchase
and installation of a control alternative (i.e., process modification or
add-on system) in an existing plant—retrofit installations, in other words.
Major and auxiliary equipment purchase and installation costs have been
obtained from actual installations or vendors. Costs for research and
development, production losses during installation, start-up, and
3-3
-------
Table 3-1. TECHNICAL PARAMETERS USED IN DEVELOPING CONTROL COSTS0
I. Coating Line Baseline Production Rate:
II. Operating Factors:
III. Baseline VOC Emission Rates (Concentrations)
1. Prime coat line:
- Spray booth and application area
- Oven
2. Topcoat line:
- Spray booth and application area
- Oven
IV. VOC Control Efficiencies:
1. Add-on control systems
- Thermal incineration
- Carbon adsorption
2. Process Modifications
- Water-borne coating
- High-solids coating
- Powder coating
- Electrodeposition coating
V. Volumetric Flowrates (Temperatures)
1. Thermal incineration
2. Carbon adsorption
768,000 units/yr.
1 ,920, 3,840, and 5,760
hours/yr.
157, 314, and 471 Mg/yr.
(1% LEL)
39.2, 78.4, and 118 Mg/yr.
(15% LEL)
95.2, 190, and 286 Mg./yr.
(1% LEL)
23.8, 47.6, and 71.4 Mg/yr.
(15% LEL)
90%
90%
80%
76%
95%
87%
43.9 m3/min. (at 149°C)
1,840 m3/min. (at 21°C)
References 1 and 2.
These are the flowrates and temperatures at the add-on control system inlets.
3-4
-------
other highly variable costs are not included in the estimates. All
capital costs represent first quarter 1977 dollars.
In the case of a process modification, the capital cost simply repre-
sents the cost for modifying the existing solvent spray coating line, by
removing the old equipment and installing the new. Depending on the
modification, the cost may be small or large, relative to the existing.
coating line investment.
For add-on systems, however, the capital cost is that for installing
the control equipment on an existing spray booth or oven. None of the
coating equipment is modified, and, consequently, the capital cost is
virtually independent of the existing solvent line configuration.
3.1.5 Bases for Annualized Cost Estimates
Annualized cost estimates for the control alternatives consist of:
direct operating costs, solvent credits, and annualized capital charges.
Direct operating costs include expenditures for: labor and materials
for operating the control equipment (except solvent); utilities, such as
electric power and natural gas; disposal of liquid and/or solid wastes
generated by the control alternative; and maintenance labor and supplies.
With process modifications, these costs represent the difference or
"increment" between the respective costs incurred by the new coating
system and those for the existing solvent coating line. For the add-on
controls, the costs are merely those for the operation and maintenance of
the control equipment.
The solvent credit represents the difference between the solvent cost
for the process modification and that for the baseline, solvent-borne
3-5
-------
coating line. Because the process modification requires (and emits) less
solvent than the baseline process, this value is always negative, i.e.,
a credit. This credit does not apply to add-on control systems, however.
This is so because the solvent captured by carbon adsorbers cannot be
reused, while incinerators oxidize the solvent to carbon dioxide, water,
and other combustion products.
The annualized capital charges are subdivided into costs for depre-
ciation and interest and costs for taxes, insurance, and administration.
Depreciation and interest have been computed by a capital recovery factor
whose value is based on the depreciable life of the control equipment and
the annual interest rate. (A twelve-year life and ten percent interest
rate have been assumed for each control alternative.) Four percent per
year for taxes, insurance, and administrative charges is added to this
recovery factor, and the sum is multiplied by the capital cost, yielding
the annualized capital charges.
The total annualized cost is obtained by summing the direct operating
cost and annualized capital charges and subtracting from this sum the
solvent credit.
The annualized costs are for a one-year period beginning with the
first quarter of 1977. Factors used to compute the annualized cost are
listed in Table 3-2.
3.2 CONTROL OF SOLVENT EMISSIONS FROM LARGE APPLIANCE COATING OPERATIONS
3.2.1 Control Costs
Cost estimates for retrofitting new coating systems, carbon adsorption,
and thermal incineration systems to the model solvent prime and topcoat
3-6
-------
I.
II.
Table 3-2. COST FACTORS USED IN COMPUTING ANNUALIZED COSTS'
Pirect Operating Costs
1. Materials:
- Solvent coating (prime):
- Solvent coating (top):
- Solvent coating (solvent thinner):
- Powder coating:
- Spray water-borne coating:
- Electrodeposition water-borne coating:
- High-solids coating:
- Carbon
2. Utilities
- Electricity
- Natural gas
- Steam
- Boiler feed water
3. Direct Labor
4. Maintenance Labor
- Process modifications
- Add-on systems
5. Maintenance Materials
6. Waste Disposal
A n n u a 1 i z ed C a p i ta 1 Charges
1. Depreciation and Interest
2. Taxes, insurance, administrative charges
$1.72/liter
$2.13/1 Her
$0.28/1 Her
$3.85/Kg ($1
$2.11/liter
$1.93/1 Her
$3.17/1 Her
$2.20/Kg ($1
($6.50/gal.)
($8.05/gal)
($1.07/gal)
.75/lb)
($8.00/gal)
($7.30/gal)
($12.00/gal)
.00/lb)
$0.025/kw-hr
$1.90/thousand joules
($2.00/million Btu)
$5.50/thousand Kg
($2.50/thousand Ib)
$0.13/thousand liters
($0.50/thousand gal)
$10/man-hour
$10/man-hour
0.02 x Capital Cost
0.02 x Capital Cost
$0.03/liter coating ($0,11/
0.1468 x Capital Cost
0.04 x Capital Cost
References 1 and 9, and EPA estimates.
3-7
-------
lines are presented in Tables 3-3 and 3-4, respectively. Table 3-5
contains costs for powder coating, which applies to both lines combined.
Again, remember that the direct operating cost for a process modification
is an incremental cost; that is, it represents the increase or decrease
when comparing the cost of the new coating system to the baseline solvent
system.
For the prime coating line, Table 3-3 shows conversion to electro-
deposition (EDP) coating to be more cost-effective than conversion to
water-borne spray, despite its much higher installed cost. The EDP
annualized credits range from $235,000 to $912,000/year for the 1,920
and 5,760 hours/year operations, respectively, compared to costs of
$115,000 to $328,000/year for conversion to water-borne coating. Most
of the cost discrepancy is attributable to the high incremental materials
cost (excluding solvent) for water-borne coating, relative to solvent-borne
prime: $114,000 to $341,000/year. The direct operating costs shown for
water-borne coating also include credits for natural gas and waste disposal,
and small costs for maintenance and electricity. To contrast, the EDP
system has direct operating credits of $270,000 to $831,000/year, primarily
due to incremental credits for materials and direct labor. Their solvent
credits are about equal, at $58,000 to $174,000 and $53,000 to $158,000/year,
respectively, for EDP and water-borne. Finally, the VOC control efficiencies
for these options are 87 percent for EDP and 80 percent for water-borne.
However, Table 3-4 shows high-solids coating to be the most cost-
effective control option for the model topcoat line. The total annualized
3-8
-------
Table 3-3. CONTROL COSTS FOR MODEL EXISTING ELECTROSTATIC SPRAY PRIME COAT LINE
(Baseline Production 768,000 units per year)a
Installed capital cost ($000)e
Direct operating cost (credit)
($000/yr)f
Solvent credit ($000/yr)
Annual ized capital charges ($000/yr)
Total annualized cost(credit):$000/yr:
I/unit
Solvent emissions controlled (Mg/yr)
Emission reduction (%)
Cost-effectiveness ($/Mg of solvent
controlled)^
Water-borne
Coatinqb
1,920 hr/yrd
40
160
(53)
8
115
0.15
157
80
732
3,840 hr/yr
40
320
(106)
8
222
0.14
314
80
707
5,760 hr/yr
40
478
(158)
8
328
0.14
471
80
696
Electrodeposition (EDP)
Coating0
1 ,920 hr/yr
500
(270)
(58)
93
(235)
(0.31)
171
87
(1,370)
3,840 hr/yr
500
(550)
(116)
93
(573)
(0.37)
342
87
(1,680)
5,760 hr/yr
500
(831)
(174)
93
(912)
(0.40)
513
87
(1,780)
References 1, 2, 5, 6, and 10.
Costs are for extra insulation of equipment, and converting the spray booths to water wash.
^osts are for new application equipment.
1,920 hours/year corresponds to a production rate of 768,000 units/year; 3,840 hours/year corresponds to 1,536,000 units/y
and 5,760 hours/year corresponds to 2,304,000 units/year.
Capital costs have been rounded to the nearest ten thousand dollars; annualized costs, to the nearest thousand dollars.
Includes all incremental costs except the solvent credit, which appears immediately below.
quotient of the total annualized cost ($/yr) and the solvent emissions controlled (Mg/yr.).
Jo
-------
Table J-4. CON1KOL COSTS FOR MODEL EXISTING ELECTROSTATIC SPRAY TOPCOAT LINE
(Baseline Production: 768,C'JO iinlts/yr.)4
Process Modification
CO
I
Water-borne Coating
Installed capital cost (tOOO)9
Direct operating cost (credit)($000/yr)
Solvent credit ($000/yr)
Annual (zed capital charges (fCOO/yr)
Total annual ized costUredl t): SOOO/yr
J/unit
Solvent emissions controlled (Hg/yr)
Emission reduction (2}
Cost-effectiveness (J/Mg of solvent
controlled).!
1920 hr/yrf
30
38
(32)
5
11
0.01
95
BO
111
3040 hr/yr
30
75
(64)
5
16
0.01
190
80
83
Carbon Adsorber (spray
Installed capital cost (JOOO)9
Direct operating cost (credit) ($000/yr)
Solvent credit (JOOO/yr)
Annual 1zed capital charges ($000/yr)
Total annualized cost (credit): $OCO/yr)
$/unit
Solvent emissions controlled (Mg/yr)
Emission reduction (%)
Cost-effectiveness ($/Hg of solvent
controlled) J
1920 hr/yr
500
44
O1
93
137
0.18
H6
90
1.6QO
3840 hr/yr
500
61
0
93
154
0.10
171
90
901
5760 hr/yr
30
112
(96)
5
21
0.01
286
80
73
booth)
5760 hr/yr
500
77
0
93
1/0
0.07
257
90
665
High-Solids Coat
1920 hr/yr
40
(45)
(31)
a
(68)
(0.09)
91
76
(758)
Add-on
Themal
1920 hr/yr
79
10
0
15
26
0.03
21
90
1.170
3B40 hr/yr
40
(98)
(62)
B
(152)
(0.10)
181
76
(845)
in9c
5760 hr/yr
40
(1S2)
(93)
8
(237)
(0.10)
272
76
(H72)
Powder Coating
19?0 hr/yr
750
134
(38)
140
236
0.31
113
9b
2,090
3840 hr/'yr
750
252
(76)
140
317
'0.21
226
95
1 ,400
576C hr/yr
750
3/1
(114)
140
397
0.17
339
95
1,170
Control System
Incinerator
3840 hr/yr
79
17
0
15
32
0.02
43
90
750
(oven)6
57CO hr/yr
79
24
0
15
39
0.02
61
90
611
1920 hr/yr
579
54
0
108
162
0.2!
107
90
1.510
Total
3840 hr/yr
579
78
0
108
lee
0.12
211
90
869
5760 hr/yr
579
101
0
108
209
0.09
321
90
651
Costs are for extra insulation of equipment, arid converting the spray booths to water wash.
cCosts are for converting solvent-borne spray coating line.
Costs are for case where powder coating only replaces the solvent-based topcoat operation.
eCostS Include primary heat recovery (35i)
1,920 hours/year .corresponds to a production rate of 768,DOO unlU/yearj 3-,840-hours/year corresponds to 1,536,000 units/year; and 5,760 hrs/yr.
corresponds to 2.304,000 units/year.
'Capital costs have been rounded to the nearest ten thousand dollars; annuallzed costs, to the nearest thousand dollars.
Includes all Incremental operating costs except the solvent credit, which appears Immediately below.
Credit 1s zero for add-oti control systems, because there 1s no change In the solvent usage.
Mhp quotient of the total annual(zed cost (S/vrt and the solvent emissions controlled (Mn/yr).
-------
credit for this system ranges from $68,000 to $237,000/year.
Most of this credit is attributable to the incremental materials credit.
This is so despite the fact that high solids coating is more expensive
(at $3.18/liter) than the solvent-borne topcoating ($2.l3/liter).
However, when high-solids coating is used, the amount of coating required
is sufficiently smaller to result in a much lower materials cost.
Conversion of the topcoat line to water-borne coatings is next in
cost-effectiveness. As Table 3-4 shows, the direct operating costs are
nearly offset by the solvent credits, which range from $32,000 to $96,000
per year. And because the incremental capital cost is relatively low
($30,000),so is the annualized capital charges. Consequently, the total
annualized costs are relatively small, at $11,000 to $21,000 per year,
respectively, for the 1,920 hours/year (one-shift) and 5,760 hours/year
(three-shift) cases.
The add-on control systems—carbon adsorption on the spray booth
and flash-off area, thermal incineration with primary heat recovery on
the oven—have combined annualized costs of $162,000 to $209,000/year.
Controlling a much larger volume, the adsorption system accounts for
over 80 percent of these amounts. Most of this percentage is, in turn,
attributable to the annualized capital charges for the adsorber.
Conversion of the topcoat line to powder coating is the least cost-
effective of the options. The solvent credits shown in Table 3-4 do
little to offset the annualized capital charges and direct operating costs.
The former are due to the relatively high incremental investment ($750,000),
while most of the latter are comprised of the incremental materials costs.
These, in turn, range from $122,000 to $366,000 per year.
3-11
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The systems in Table 3-4 also represent different levels of VOC
emission reduction. The control efficiencies range from 80 percent for
water-borne coating to 95 percent for conversion to powder coating.
These efficiencies are reflected in the cost-effectiveness ratios, the
quotients of the annualized costs and the VOC emissions controlled.
(Cost-effectiveness is discussed in Section 3.2.2.)
Table 3-5 contains costs for replacing both prime and topcoat lines
with powder coating. Unlike the powder coating option in Ta.ble 3-4, this
option involves coating of both sides of the appliance, as opposed to only
one side in the topcoat operation. For this reason, the investment
($1,180,000) is much higher. Despite this high investment, the annualized
capital charges are more than offset by the solvent credits and direct
operating credits with the 3,840 and 5,760 hours/year cases. Finally,
powder coating represents the highest control efficiency for the model
plant: 95.0 percent.
3.2.2 Cost-Effectiveness
As Tables 3-3 through 3-5 show, the cost-effectiveness ratios for the
several control alternatives cover a broad range. This reflects not only the
range in annualized costs, but the various control efficiencies and the
uncontrolled emission rates for the solvent-borne prime and topcoat lines.
The annualized costs and emission reductions for the individual coating
lines have been used to calculate the cost-effectiveness ratios and VOC
emission control efficiencies for the model plant.
Table 3-6 lists these parameters, along with nine combinations of
prime and top coating line control alternatives. Listed in decreasing order,
the overall control efficiency goes from 95.0 percent (powder coating) to
3-12
-------
u>
I
Table 3-5. COSTS FOR CONVERTING MODEL EXISTING ELECTROSTATIC
SPRAY COATING LINES TO POWDER COATING
(Baseline Production: 768,000 units/yr)
Item Value
1920 hr/yrc 3840 hr/yr 3760 hr/yr
Installed capital cost ($000)d 1,180 1,180 1,180
Direct operating cost (credit) (44) (112) (180)
($000/yr)e
Solvent credit ($000/yr) (104) (208) (312)
Annualized capital charges 220 220 220
($000/yr)
Total annualized cost(credit )i$000/yr. 72 (100) (272)
$/unit 0.09 (0.07) (0.12)
Solvent emissions controlled (Mg/yr) 309 618 927
Emission reduction (%) 95 95 95
Cost-effectiveness ($/Mg of solvent 233 (162) (293)
controlled)^
References 1 to 3.
Since no prime coat is needed with powder coating, these are incremental costs for converting both coati
cl ,920 hours/year corresponds to a production rate of 768,000 units/year; 3,840 hours/year corresponds
to 1,536,000 units/year; and 5,760 hours/year corresponds to 2,304,000 units/year.
Capital costs have been rounded to the nearest ten thousand dollars; annualized costs, to the nearest
thousand dollars.
elncludes all operating costs except the solvent credit, which appears below.
-------
iu
Table 3-6. COST-EFFECTIVENESS SUMMARY FOR MODEL PLANT CONTROL ALTERNATIVES9
Control Alternatives
1.
2.
3.
4.
5.
6.
7.
8.
9.
Prime Coat Line
Powder coating
EDP coating
EDP coating
Water-borne coating
EDP coating
Water-borne coating
EDP coating
Water-borne
Water-borne coating
Top Coat Line
Powder coating
Powder coating
Carbon adsorption and
thermal incineration
Powder coating
Water-borne coating
Carbon adsorption and
thermal incineration
High-solids coating
Water-borne coating
High-solids coating
Cost-Effectiveness
($/Mg)b
1920 hr/yrc
233
4
(263)
1,300
(842)
1,050
(1,160)
500
190
3840 hr/yr
(162)
(451)
(696)
998
(1,050)
773
(1,390)
472
141
5760 hr/yr
(293)
(604)
(843)
895
(1,120)
678
(1,460)
461
122
Control
Efficiency
(*) b
95.0
90.3
88.4
85.7
84.6
83.8
83.2
80.0
78.6
References 1 through 10.
The cost-effectiveness and control efficiency numbers are for the prime and topcoat control alternatives combined.
cl ,920 hours/year corresponds to a production rate of 768,000 units/year; 3,840 hours/year corresponds to 1,536,000
units/year; and 5,760 hours/year corresponds to 2,304,000 units/year.
With this option, powder coating replaces both the prime and topcoat operations.
-------
78.6 percent for the combination of spray water-borne prime coating and
high-solids top coating. However, between these efficiency extremes,
the cost-effectiveness varies unevenly, from ($1,460) to $l,300/Mg of
solvent removed.
For discussion purposes, the control combinations can be grouped
into two efficiency ranges: moderate (78.6 to 90.3 percent) and high
(95.0 percent). If a high control efficiency were required, the prime
and top coat lines would be converted to powder coating. Its cost-
effectiveness ranges from ($293) to $233/Mg.
On the other hand, the combination of EDP prime coating and high-
solids ($l,160)/Mg, top coating would be the most cost-effective selection
at ($1,460) to ($l,160)/Mg, if a moderate emission reduction were necessary.
At 83.2 percent, the control efficiency for this combination falls about
midway in the moderate efficiency range.
EDP prime coating, in successive combination with water-borne conver-
sion of the topcoat line and carbon adsorption-thermal incineration yield the
next lowest cost-effectiveness ratios, at ($1,120) to ($842)/Mg and ($843) to
($263)/Mg, respectively. Compared to the other six combinations in the
moderate efficiency range, these are low values. These low ratios, in turn,
are mainly attributable to the relatively low incremental annualized cost of
EDP prime coating, when compared to spray water-borne coating (See Table 3-3.)
Finally, the cost-effectiveness ratios have been plotted against the
three production rates. Figure 3-1 displays these nine cost-effectiveness
curves, each numbered according to its corresponding control option in
Table 3-6. Note how the cost-effectiveness decreases with increasing
3-15
-------
production rate. For most of the curves this decrease is pronounced.
However, for curves 8 and 9, the cost-effectiveness decreases only
slightly with increasing production rate. The control options corres-
ponding to these curves involve small capital expenditures. Hence, their
annualized costs are heavily weighted toward those costs and credits pro-
portional to the production rate, such as materials, labor, and solvent.
Of course, the amount of solvent emissions removed is also proportional to
the production rate. Thus, for options 8 and 9, the cost-effectiveness
ratio—the quotient of annualized cost and solvent removed—is virtually
insensitive to changes in the production rate.
3-16
-------
Figure 3-1. Cost-Effectiveness Curves for Model
Plant Control Alternatives
1600
1200
800
T3
0)
o»
a:
cz
O)
en
s:
~x.
V*
c
O)
400 i
-400
-800
-1200
-1500
500 1000 1500 2000 2500
Production Rate (thousand units/year)
3-17
-------
2.
3.
4.
7.
8.
9.
10.
3.3 REFERENCES
1. Air Pollution Control Engineering and Cost Study of the General Surface
Coating Industry, Second Interim Report, SectionsVIII-A and -B Emission
Control Costs on Major and Small Appliances. Prepared by: Springborn
Laboratories, Inc. (formerly DeBell and Richardson), Enfield, Connecticut.
Prepared for U.S. Environmental Protection Agency, Office of Air Quality
Planning and Standards, Emissions Standards and Engineering Division,
Research Triangle Park, North Carolina, Contract No. 68-02-2075, August,
1977.
Memoranda from W. M. Vatavuk, U.S. Environmental Protection Agency,
Strategies and Air Standards Division, To V.N. Gallagher, U.S.
Environmental Protection Agency, Emissions Standards and Engineering
Division. August 23, 1977, and December 16 , 1977.
Letter from E. W. Connors, Jr., General Electric Company, Appliance Park,
Louisville, Kentucky. December 5, 1977.
Letter from W. M. Vatavuk, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, to H. Kennedy, Whirlpool Corporation,
Findlay, Ohio. December 2, 1977.
Letter from J. Pratapas, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina to Clyde Speir, Lyon Metal Furniture,
Aurora, 111. August 23, 1977.
Comments from W. Zimmt, E. I. du Pont de Nemours and Company, Inc.,
Philadelphia, Pennsylvania, regarding Control of Volatile Organic
Emissions from Existing Stationary Sources - Volume IV: The Large
fr
Appliance CoatingIndustry (Draft). November, 1977.
Kloppenburg, W. B., Trip Report #69: Keller Industries, Milford,
Virginia. Springborn Laboratories, Enfield, Conn. February 23, 1976.
Kinkley, M.L. and R. B. Neveril. Capital and Operating Costs of
Selected Air Pollution Control Systems. Prepared by GARD, Inc., Miles,
111. Prepared for U,~S". Environmental Protection Agency, Office of Air
Quality Planning and Standards, Strategies and Air Standards Division,
Research Triangle Park, North Carolina, Contract No. 68-02-2072.
May, 1976.
Ibid. Revision to Section 4.5, Adsorbers. August, 1977.
Letter from W. M. Vatavuk, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina to R. Morcom, Springborn Laboratories,
Enfield, Conn. August 17, 1977.
3-18
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4,0 ADVERSE AND BENEFICIAL EFFECTS OF APPLYING TECHNOLOGY
This chapter provides the adverse and beneficial effects of each
technique which reduces VOC emissions. These effects are not necessarily
environmental but also include energy, cost, and any limitations of low
organic solvent technology as compared to conventional .high organic
solvent coatings.
4.1 ELECTRODEPOSITION
Several other advantages, 1n addition to reduced VOC emissions, acrue
from converting to electrodeposition.
• The major one is good quality control as a consequence of the fully
automated process.
• It provides excellent coating coverage, corrosion protection, and
detergent resistance because the paint particles are able to get into small
recesses of part?. However, because the coverage is so uniform, electro-
deposition does not "mask" metal imperfections.
• Fire hazards and potential toxicity are decreased in electrodeposition
due to the reduction of organic solvent content.
• If electrodeposition replaces a spray coating operation, solids
and liquid wastes associated with spraying operations will be reduced
drastically.
• The lower organic content permits lower ventilation rates,
resulting in reduced energy consumption.
There are several disadvantages to the electrodeposition process.
4-1
-------
• Conversion to coating large appliance parts by electrodeposition
may increase electrical consumption. The amount will depend on the original
application system, the size of the electrodeposition bath, and the thick-
ness of the coating applied. In electrodeposition, electrical energy is
required for the coating system, the refrigeration to overcome the temperature
rise from the electrical process, for good paint circulation in the bath and
operate the ultrafilter. Electrodeposition may consume three times as much
2
energy as the water-borne flow or dip coating operations, This would not
be true if electrodeposition replaces a spraying operation. For example,
energy credit must be given for elimination of high volumes of treated
air necessary for spray booths. Energy consumption will also be less in the
baking process. The air flow 1n the oven may be reduced and the flashoff
tunnel may be omitted.
• If the hooks which hold the appliance parts are not properly hung
or cleansed, the electrical contact may be faulty and the coating will not
adhere to the metal.
• Conversion to electrodeposition will also necessitate a change of
equipment at significant capital cost. The use of electrodeposition can be
expensive on small scale production lines.
4.2 WATER-BORNE - SPRAY, DIP.OR FLOWCOAT
There are several advantages to converting to water-borne coatings.
• Conversion to water-borne coatings will likely be the first option
considered by many facilities because of the possibility that these coatings
can be applied essentially with existing equipment.
• Converting to water-borne coatings provides a potential
decrease in toxicity and flammability.
4-2
-------
• Water-borne coatings may be thinned with water, and coating equip-
ment can be cleaned or flushed with water rather than organic solvent.
When they are dry, however, water-borne coatings must be cleaned off
application equipment with solvent, since they are then no longer soluble
in water,
• Curing water-borne coatings may allow a decrease in oven temperature
and some reduction in air flow since the amount of organics evaporating
3
in the oven is reduced. Air flow reduction, however, may be limited by
high humidity occurring within the oven from water-borne coatings, potentially
causing improper curing of the film and condensation on the oven walls,
There are several disadvantages to water-borne coatings when compared
with conventional organic-borne coatings.
• The coating of large appliance parts with sprayed water-borne coatings
may require closer attention than with organic-borne coatings because
temperature, humidity, gun-to-metal-part distance, and flashoff time may
change the appearance and performance of the coatings.
- Some spray equipment may have to be replaced or protected from
corrosion.
• On many large electrostatic lines, spraying water-borne may be
impractical because of the difficulties involved in isolating the entire
system successfully. (Many water-borne coatings, however, may be easily
sprayed electrostatically, with conventional air,or with airless spray
methods).
• Water-borne coatings applied by conventional dip and flow coating
application equipment will need to be monitored more closely due to their
sensitive chemistry.
4-3
-------
• Cleansing and pretreatment are more critical because of possible
4
coating contamination and pH changes within the dip or flowcoating tank.
Although an additional rinse may be needed, they dry-off oven can be
eliminated in some cases prior to coating.
• As in spraying, some equipment may have to be replaced or adjusted
(due to different surface tension of water than that of organic solvent)
or protected from corrosion. In one converted flowcoating operation, only
the number of spray nozzles for the flowcoater had to be doubled to obtain
the same coverage as with conventional coatings.
• The coating bath, flashoff time, temperature, air circulation, and
humidity may have to be altered and frequently monitored, because changes in
o
weather conditions may affect the application of water-borne coatings.
• Sludge handling may be more difficult because the water-borne coating
does not settle as well.
4.3 POWDER
There are several advantages obtained after a facility is converted to
apply powder coatings besides the substantial reduction inemissions.
• There are no solid or liquid wastes to be disposed of as compared to
solvent-borne coatings,
• Powder does not require the purchase of additional solvents to
control the viscosity of the coating or to clean the equipment.
• Powders can mask imperfections or weld marks in the metal .
• Conversion to powder coatings may reduce energy requirements in a
spray booth because the large volumes of fresh air required for application
of solvent-borne coatings are no longer required.
4-4
-------
• If the powder recovery unit is highly efficient in collecting
overspray, the cleaned air may be returned to the working area.
1 Energy usage may also be reduced due to the elimination of the
flashoff tunnel and decreased air requirements for the ovens, It has
been estiamted that a 35-50 percent overall reduction in energy requirements
will result in replacing a single coat applciation with powder, and 55-70
percent reduction will occur when a two-coat applications is replaced
9
with powder.
• Powder can be reclaimed resulting in up to 98 percent coating
efficiency. However, not all reclaimed powders are suitable for reuse.
Powder containting a buildup of powder fines will have to be discarded, and
the larger and heavier granules will have to be reprocessed again before they
are suitable for reuse.
There are disadvantages encountered when applying powders.
• All application equipment, spray booths and associated equipment
(and often ovens) used for liquid systems must be replaced. This will then
limit the flexibility to apply other coatings on appliances because only
powders can be applied with this type of equipment.
• Coating film thicknesses of less than 2 mils have not been successfully
obtained with powders on a production line basis.
• Metallic powders have not yet been successfully developed.
• Color matching during manufacturing of powder is difficult,
• Powder films have appearance limitations.
• Recesses are often difficult to cover effectively due to Faraday
caging effect without resulting in application of thicker films of coating,
• Excessive humidity during storage and application can affect the
performance of powders
4-5
-------
• Powder coatings are also subject to explosions as are many particu-
1 ate dust due to difficulties in obtaining enough ventilation at all times.
1 Color changes for powder require about half an hour down time if
powder is recovered for reuse. This would greatly curtail production capaci-
ties in large appliance facilities. Color changes may be shortened if
powders are not reclaimed in their respective colors, but results in a coating
usage efficiency of only 50 to 60 percent.
• Powders may present application difficulties at the high "line speeds
which many of the large appliance manufacturers operate.
4.4 HIGHER SOLIDS COATINGS
One of the areatest advantages of converting to higher solids coatings
is that they may be applied with existing equipment, although some application
equipment (i.e., spray guns) may have to be replaced or a paint heater may
have to be installed to reduce the viscosity of the higher solids coatings.
Conversion to high-solids coatings can permit reduced energy consumption.
Air flow in the spray booth can be decreased because less organic solvent
is applied for each dry mil thickness of film. The energy consumption by
the oven and the flashoff tunnel may also be reduced by reducing the volume of
the oven exhaust otherwise necessary to maintain a low concentration ^ of
organic solvents. Solid and liquid waste may also decrease since less
coating is applied per dry mil, However, the tackiness of high solid
coatings may make cleanup more difficult.
Although the organic solvent content is reduced, this reducing the
level of toxicity, there is a potential health hazard associated with
isocyanates used in some high-solid two-component systems.
4-6
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4.5 CARBON ADSORPTION
Although the technology is well documented and considered technically
feasible, there are no large appliance or other metal coating facilities
known to be using carbon adsorption on application and flashoff areas, The
additional energy required to operate a carbon adosrption system is a
potential disadvantage. The energy requirement will depend on the type of
application, the size of adsorber(s) and the concentration of the solvents
entering the carbon bed. Any reduction which can be made in the amount of
air flow from the coating application and flashoff areas will result in less
energy usage because a smaller adsorber can be installed.
The amount of solid and liquid waste generated by the use of a carbon
adsorber will depend on the coating application system. Organics emitted
by the flow and dip coating operations will not require filtration or
scrubbing of the inlet gas stream into an adsorber. However, emissions
from spray booths may require additional filtration or scrubbing since
overspray may not be completely removed by the spray booth collectors. Some
solvents are water miscible and may produce a water pollution problem if
regeneration steam 1s condensed ana discnargea untreatea. This, nowever,
can be solved by incinerating the uncondensed steam and solvent together, or
by stripping the condensate and disposing of the solvents, Either will
increase the cost and energy consumption of the carbon adsorption unit. There
is little possibility that the recovered solvents may be reused in the large
appliance industry because of the variety of solvent mixtures used.
An important factor to consider for carbon adsorption is plant space.
Many large appliance facilities may require many dual-bed carbon adsorption
units in parallel operation. These will require a relatively large plant area.
4-7
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4.6 INCINERATION
The most common and widely applicable technique used for the reduction
of organic emissions is incineration. One disadvantage is the quantity of
additional fuel required unless heat recovery is used. The use of primary
(preheat of the inlet gas stream to near incineration temperature) and
secondary (use of heat from the incinerator exhaust for other energy-using
processes) heat recovery will reduce energy consumption and perhaps even
reduce the plant's overall consumption if there are enough areas where
secondary heat may be utilized, Table 4-1 shows the potential decreases
in energy usage when using tube and shell heat exchangers with incineration.
Some examples (besides preheating the incinerator inlet) where heat from
the incinerator exhaust may be used are: oven makeup air, boiler, cleansing
processes, dryoff ovens, and plant heat. Greater heat recovery efficiencies
(85-90 percent) than those shown in Table 4-1 may be obtained with other
forms of heat exchangers (ceramic wheel and stone packed beds) which can be
very attractive for low organic concentration streams,
4-8
-------
TABLE 4-1
BURNER REQUIREMENTS FOR INCINERATORS
IN 106 BTU/HRa'b'14
NON-CATALYTIC INCINERATORS 5 percent LEL 15 percent LEL
No Heat Recovery
5000 scfm 5.82 4.05
15,000 scfm 17.48 12.16
30,000 scfm 34.95 24.31
38% Efficient Primary Heat Recovery
5000 scfm 3.32 1.56
15,000 scfm 10.09 4.73
30,000 scfm 19.97 9.38
Primary and 55% Efficient Secondary
Heat Recovery
5000 scfm 1.42 -0.34
15,000 scfm 4.40 -0.66
30,000 scfn 8.67 -1.82
CATALYTIC INCINERATORS
No Heat Recovery
5000 scfm 1.69 1.69
15,000 scfm 5.07 5.07
30,000 scfm 10.14 10.14
38% Efficient Primary Heat Recovery
5000 scfm 0.79 0.26
15,000 scfm 2.38 0.77
30,000 scfm 4.76 1.54
Primary and 55% Efficient Secondary
Heat Recovery
5000 scfm -0.21 -1.07
15,000 scfm -0.62 -3.22
30,000 scfm -1.24 -6.46
a) Based on 300°F oven outlet temperature; 1400°F outlet temperature for non-cata
and 600°F inlet temperature for catalytic incinerators.
b) (-) indicates net overall fuel savings.
4-9
-------
4.7 REFERENCES
1. Appliance Finishers Favor Electrocoating, Finishing Highlights, pages 8 & 9,
January-February 1977.
2. Kennedy, W.D., Major Appliance Electrocoat, Whirlpool Corporation.
Presented at the NPCA - Chemical Coatings Conference, Cincinnati, Ohio,
April 22, 1976.
3, McCormick, Donald, Converting a Flowcoater to Water-borne Paint, Whirlpool
Corporation. Presented at the NPCA Chemical Coatings Conference, Cincinnati,
Ohio, April 23, 1976.
4. Water-borne Flowcoating and Dip, Products Finishing, pages 73-76,
February 1977.
5. McCormick, Op. Cit.
6. Products Finishing, Op. Cit.
7. McCormick, Op. Cit.
8. Products Finishing, Op. Cit.
9. Economic Justification of Powder Coating, Powder Finishing World, pages 18-22,
4th Quarter 1976.
10. LeBras, Louis, Technical Director, PPG Industries Inc., Pittsburgh, Pa.
Letter to V. N. Gallagher in comment of the metal furniture draft document.
Letter dated August 31, 1977.
11. Ibid
12. DeVittorio, J.M., Ransburg Corporation, Application Equipment for High-
Solids and Plural Component Coatings, Volume I, No. 2, April 197t,
13. "Question Corner", High-Solids Coatings, Volume I, No. 3, July 1976.
14, Combustion Engineering Air Preheater, Wellsville, N.Y., Report of Fuel
Requirements, Capital Cost and Operating Expense for Catalytic and
Thermal Afterburners, EPA Contract Report No, EPA-450/3-76-031 ,
September 1976.
4-10
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5.0 MONITORING TECHNIQUES AND ENFORCEMENT ASPECTS
This chapter discusses the recommended emission limit, the monitoring
techniques and enforcement aspects of coatings low in organic solvents and
add-on control equipment for reducing VOC emissions.
As stated in the Preface, there is no universal VOC emission control
technique applicable for all large appliance coating operations because of
the large variety of appliances manufactured and the variety of coating
application methods used, The recommended emission limit (2,8 Ibs of organic
solvent per gallon of coating)for the large appliance industry is based on
electrodeposition or water-borne coatings for primer and interior single coat,
and on water-borne or higher-solids coatings for topcoat and exterior single
coat applications. For large appliance coating facilities, it is recommended
that emission limitations be expressed in terms of organic solvent content
of the coating since these values can be determined with relatively simple
analytical techniques. To permit operators to use add-on control equipment,
alternative compliance procedures should be allowed. Sample calculations to
verify compliance with this emission limit are shown in Appendix A.
Limitations in VOC may be expressed in terms of mass or volume and may
be based on the entire coating (including organic solvent) or only on paint
solids. In this guideline, limitations are expressed as the allowable mass
of organic solvent per unit volume of coating (kgs per liter of coating or
Ibs per gallon of coating) as it is delivered to the coating applicator.
The water content of the coating is not included in the ratio. The principal
advantage of this format is that enforcement is relatively simple. Field
5-1
-------
personnel can draw samples and have them analyzed quickly. A disadvantage
is that the relationship between the solvent fraction and organic emissions
is not linear. If the organic solvent content is expressed in terms of mass
of organic solvent per unit volume of paint solids (kgs per liter or Ibs per
gallon of solids), the disparity disappears. This relationship is linear
and more readily understood e.g., a coating containing 2 Ibs of organic solvent
per gallon of solids releases twice as much organic solvent as one with one
pound per gallon. The disadvantage of this format, however, is that the
analytical methods are more complex. Appendix A of Volume II "Control of
Volatile Organic Emissions from Existing Stationary Sources - Volume II:
Surface Coating of Cans, Coils, Paper, Fabrics, Automobiles, and Light-Duty
Trucks", presents ASTM test methods for determination of the pounds of
organic solvents per gallon of coating (minus water).
Other options such as weight or volume of organic solvent per kilogram
of coating are generally less desirable although they may be entirely
appropriate for a given industry. Basing limitations on the mass of coating
or paint solids is not recommended because the specific gravity of coatings
tends to vary widely with the degree and type of pigment employed. Highly
pigmented paints have much greater density than unpigmented clear coats or
varnishes.
The recommended limitation assumed the large appliance facility merely
converts from use of an organic-borne coating to a coating low in organic
solvent. It does not consider any reduction in VOC emissions which may result
from a decrease in film thickness or an increase in the transfer efficiency
of a coating. For example, assume a facility applying conventional coating
at 1.2 mils film thickness, converts to a coating which, although it contains
5-2
-------
less organic solvent, it is not quite low enough to meet the recommended
emission limit. However, if the new coating has better hiding power and
is servicable with only 0.8 mils film thickness, it may still result in a
reduction in VOC emissions comparable to a coating which meets the recommended
emission limit. Another example would be a facility that converts from a
manual conventional spray application (at a transfer efficiency of 40-70
percent), to an automated electrostatic spray system (at a transfer
efficiency of 70-90 percent), or from any spray system to a flow or dip coat
system (at a transfer efficiency of at least 90 percent). In each case, a
reduction in VOC emissions will be realized. This reduction in VOC content
can be considered in any evaluation of the overall reduction achieved by the
operator.
In those few facilities where add-on control equipment Is a more likely
option, it may be more appropriate to state emission limits in terms of control
efficiency across the incinerator, adsorber, etc. Where limitations are
expressed only in terms of the solvent content of the coating, it will be
necessary to determine the mass emission rate from the control system and
relate it to the quantity of coating applied during the test period. This
is a more complicated procedure since it may not be easy to determine the
amount of coating consumed during the test period and an analysis by mass
of the organic solvent directed to the control device would be even more
difficult. Chapter 5 of "Control of Volatile Organic Emissions from Existing
Stationary Sources - Volume I: Control Methods for Surface Coating Operations"
presents approaches which may be used. When add-on type devices are
selected as the compliance method the air pollution control agency should
require that the coating lines be equipped with an approved capture device
to assure effective control. The capture system will likely have to be
5-3
-------
custom designed to accommodate the plant-to-plant variables which affect
performance. When reviewing the design of such a system, however, the air
pollution control offical must consider requirements imposed by the
Occupational Safety and Health Administration and the National Fire
Prevention Association.
Some coatings will emit a greater amount of VOC than merely its solvent
content. This incremental VOC may come from three possible sources. The
first is the possibility that some of the monomer may evaporate. Also, if
it reacts by condensation polymerization, the evolution of by-product com-
pounds may be a compounding factor. Finally, it has been reported that the
industry is using increasing quantities of "blocking agents" which are
released from the polymer matrix during the curing process.
There are now no approved analytical methods certified by the agency
for determining the quantity of VOC emitted by such reactions, although
certainly the organic mass emission rate could be determined by expensive
and sophisticated analytical techniques. The more practical means of
quantifying the contribution of the polymerization reaction to the overall
emission problem would be by contacting the manufacturer of the coating.
Certainly, his knowledge of the fundamental chemical mechanisms involved
would allow calculation of an emission rate based on the chemical reaction.
This emission will occur during the cure (if at all) which is usually
temperature initiated by the oven. If the oven is controlled by an
incinerator, then verification of the efficiency of the device should be
sufficient to assure compliance with the coating regulations.
5-4
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APPENDIX A
SAMPLE CALCULATIONS OF CONTROL OPTIONS
This appendix aids the local agency in determining if a coating pro-
posed for use by a large appliance facility will meet the recommended
emission limit of 0.34 kilograms of VOC per liter of coating applied,
(2.8 ibs/gal) excluding any water that the coating may contain. The
purpose of excluding water is to preclude compliance through dilution with
water. This appendix also explains how to compare the actual VOC emissions
from a facility regardless of the type of low-polluting coating or add-on
control device used.
The purpose of all coating operations is to cover a substrate with a
film that provides both corrosion resistance to the substrate and i
esthetic appeal. Therefore, the rational basis for specifying an allowable
VOC emission limit would be in units of coating volume (e.g., grams of VOC
per square meter (Ibs/sq.ft) per unit thickness of film). However, the
complexity of any analytical method which would provide a measurement of
the volume of a cured coating precluded this approach. As a compromise, the
limitations were developed in kilograms (Ibs) of VOC per unit volume of
uncured solids and organic solvent. Mathematically, then, the emission
factor (ef) for a coating would be expressed as:
A-l
-------
(1) of = (volume fractjon organic sol vent) (average organic solvent density)
* ' volume fraction of solids + volume fraction of organic solvent
(n\ f_ (volume fraction organic so Went) (average organic sol vent densjty)
* ' ~ ]- volume fraction of water
The following examples show the use of these equations to determine
the emission factor for both organic solvent-borne and water-borne coatings.
CASE 1: Determine the emission factor for an organic solvent-borne coating
which contains 35 volume percent organic solvent.
Therefore: ef= Ll*) (0.88 kg/li ter*)
= 0.31 kgs/liter ('2.6 Ibs/gal)
Since the emission factor is less than the recommended limit of 0.34 kg/liter
(2.8 Ibs/gal), this coating is in compliance.
CASE 2: Determine the emission factor for a water-borne coating containing
75 volume percent organic solvent. Of that 75 percent solvent, 80 volume
percent is water and 20 percent is orqanic solvent.
Since 80 percent of the solvent is water, the respective volumes of
water and organic solvent may be calculated as shown:
Volume water = .80 x .75 liter = .6 liter
Volume organic solvent = 0. 75 liter - .6 liter = .15 liter
Therefore: ef= (O^MO-S
= 0.32 kg/liter (2.64 Ibs/gal)
This coating also has an emission factor less than the recommended limit
and woul d comply.
*This density is considered typical and is equal to 7.36 Ibs/gal.
A-2
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The level of control represented by 0.34 kg/liter of coating
(2.8 Ibs/gal) less water can also be achieved with a conventional high
organic solvent coating if suitable add-on control equipment is installed.
However, this method of determining the equivalent emission limit factor
is not as straightforward as the previous two cases and must also consider
the volume of solids in the coating.
CASE 3: Determine the emission factor for a conventional organic-borne
coating containing 75 volume percent orqinic solvent.
Therefore: ef= (-75) ^kg/liter)*
= 0.66 kg/liter (5.5 Ibs/gal)
However, this liter of coating contains only 0.25 liter of solids whereas
the coating which represents the recommended emission limit of 0.34 kg.liter
(2.8 gal) contains 0.61 liter of solids.
(This can be back calculated from the recommended emission limit in this mannpr.)
i.e. 0.34 = (x) (0.88 kg/liter)
x = 0.38, volume percent organic solvent
Therefore fraction of solids =1 - x = 0.62
Cn a unit volume of solids basis, the conventional coating contains:
/ s
0. 66 kg organi c sol vent _ 2.64 o rgan1c so 1 vent 122 Ibs VOC
0.25 liter solids " liter solids V gal solids/
And the recommended limit reference coating contains
P_- ^ .kjL organi c s ol vent _ 0.55 kg organi c sol vent A.Gibs
0.62 1Tte r sol i ds " liter sol ids I gal soTidsJ
A-3
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Consequently, in order for the conventional coating to emit no more VOC
than the reference coating, the add-on control device must capture and
destroy (or collect) 2.09 kg of solvent per liter of solids applied
( 2.64 - 0.55), This will require a control system that is at least 79
percent efficient. Since the add-on control devices can often operate at
90 percent efficiency or greater, the agency must insure that at least
86 percent of the VOC emitted by the coating is captured and delivered to
the add-on control device. Since it will normally not be practical to
attempt the complex analytical program essential to develop a
material balance around the coating application and flashoff areas and ovens,
the agency will normally certify an acceptable capture system based on good
engineering practice.
A-4
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APPENDIX A REFERENCE
1. Young, Dexter E., Environmental Protection Agency, memorandum concerning
requirements for ventilation of spray booths and ovens. Dated March 10,
1977.
A-5
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TECHNICAL REPORT DATA
/Please read Instructions an the reverse before completing)
4, TiTLE AND SUBTITLE
5. R '•
Control of Volatile Organic Emissions from Existing
Stationary Sources - Volume V: Surface Coating of
Large Appllances
6. PERFORMING ORGANIZATION CODE
7 AUTHOH(S)
8. PERFORMING ORGANIZATION REPORT NO.
OAQPS No. 1 .2-088
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16 ABSTRACT
This document provides the necessary guidance for development of
regulations to limit emissions of volatile organic compounds (VOC) from the
coating operations of the large appliance industry. This guidance includes
an emission limit which represents Reasonably Available Control Technology
(RACT) for the large appliance industry, describes the industry, show the
methods by which VOC emissions can be reduced in this industry and describes
the monitoring and enforcement aspects,
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Air Pollution
Large Appliance Industry
Volatile Orqanic Compound Emission
Limits
Regulatory Guidance
19. DISTRIBUTION STATEMENT
Unl Imited
b.IDENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Stationary Sources
Organic Vapors
19. SECURITY CLASS (This Report/
Unclassified
20 SECURITY CLASS (This page/
Unclassified
c. COSATI l-'icld/Group
21.
22. PRICE
EPA Form 2220-1 (9-731
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