EPA-450/2-77-022
November 1977
(OAQPS NO. 1.2-079)
OAQPS GUIDELINES
CONTROL OF VOLATILE
ORGANIC EMISSIONS
FROM
SOLVENT METAL CLEANING
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
I
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EPA-450/2-77-022
CONTROL OF VOLATILE
ORGANIC EMISSIONS
FROM
SOLVENT METAL CLEANING
Emissions Standards and Engineering Division
Chemical and Petroleum Branch
L S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park. North Carolina 27711
No\ember 1977
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This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - in limited quantities - from the
Library Services Office (MD-35) , Research Triangle Park, North Carolina
27711; or, for a fee, from the National Technical Information Service,
5285 Port Royal Road, Springfield, Virginia 22161.
Publication No. EPA-450/2-77-022
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PREFACE
The purpose of this document is to inform regional, State, and local
air pollution control agencies of the different techniques available for
reducing organic emissions from solvent metal cleaning (degreasing). Solvent
metal cleaning includes the use of equipment from any of three broad categories:
cold cleaners, open top vapor degreasers, and conveyorized degreasers. All
of these employ organic solvents to remove soluble impurities from metal
surfaces.
The diversity in designs and applications of degreasers make an emission
limit approach inappropriate; rather, regulations based on equipment specifications
and operating requirements are recommended. Reasonably available control
technology (RACT) for these sources entails implementation of operating
procedures which minimize solvent loss and retrofit of applicable control devices.
Required control equipment can be as simple as a manual cover or as complex
as a carbon adsorption system, depending on the size and design of the
degreaser. Required operating procedures include covering degreasing
equipment whenever possible, properly using solvent sprays, reducing the amount
of solvent carried out of the unit on cleaned work by various means, promptly
repairing leaking equipment, and most importantly properly disposing of wastes
containing volatile organics. Not all controls and procedures will be applicable
to all degreasers, although in general specific operating requirements and
control devices will be applicable to the majority of designs within each
category of degreasers. Control of open top and conveyorized vapor
degreasing is the most cost effective, followed by waste solvent disposal
for all degreasing operations, manufacturing cold cleaning and maintenance
cold cleaning.
m
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Two levels of control for each type of degreaser have been identified
here as examples of reasonably available control technology (RACT). In general,
control level A shows proper operating practice and simple, inexpensive
control equipment. Control level B consists of level A plus additional
requirements to improve the effectiveness of control. The degree of
emission reduction for both individual items and control levels are
discussed in the text. Specific requirements can be modified to achieve
whatever level of control is necessary. Control systems for cold cleaners
are shown in Table 1, those for open top vapor degreasers in Table 2, and
those for conveyorized degreasers in Table 3.
Two exemptions are recommended. First, conveyorized degreasers smaller
2
than 2.0 m of air/vapor interface should be exempt from a requirement for
a major control device. This would not be cost effective and would tend to
move the small conveyorized degreaser users to open top vapor degreasers
which emit more solvent per unit work load. Second, open top vapor degreasers
2
smaller than 1 m of open area should be exempt from the application of
refrigerated chillers or carbon adsorbers. Again, requirement for these
would not be cost effective.
IV
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TABLE 1- CONTROL SYSTEMS FOR COLD CLEANING
Control System A
Control Equipment:
1 . Cover
2. Facility for draining cleaned parts
3' Permanent, conspicuous label, seizing the operating requirements
Operating Requirements:
not dispose of waste solvent or transfer it to another party,
£** Sffr^STA'S 5*3 <^="
2. Close degreaser cover whenever not handling parts in the cleaner.
3. Drain cleaned parts for at least 15 seconds or until dripping ceases.
Control System B
Control Equipment:
1 Cover: Same as in System A, except if W "W,^1!^ "
counterweight! nq or powered systems.)
SM tf ^cft?^^^^™ ^t fit inlo tL cleaning
system.
3 Label: Same as in System A
» '.
excessive splashing.
5 MOT control d.vie. for Mghly .ol.ttl. sol«nt,: If tts so1«nt
jf'fflia I: iJi't?«:"fcWi! 82 m." Ai£,"«2t5
devices must be used:
a. Freeboard that gives a freeboard ratio*** >. 0.7
b. Mater cover (solvent must be insoluble in and heavier than water)
c. Other systems of equivalent control, such as a refrigerated chiller
or carbon adsorption.
Operating Requirempntt:
Same as in System A
d1vld"'
width of the degreaser.
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TABLE 2. COMPLETE CONTROL SYSTEMS FOR OPEN TOP VAPOR DEGREASERS
Control System A
Control Equipment:
1. Cover that can be opened and closed easily without disturbing the
vapor zone.
Operating Requirements:
1. Keep cover closed at all times except when processing work loads
through the degreaser.
2. Minimize solvent carry-out by the following measures:
a. Rack parts to allow full drainage.
b. Move parts in and out of the degreaser at less than 3.3 m/sec (11 ft/nrin).
c. Degrcase the work load in the vapor zone at least 30 sec. or until
condensation ceases.
d. Tip out any pools of solvent on the cleaned parts before removal.
e. Allow parts to dry within the degreaser for at least 15 sec. or until
visually dry.
3. Do not degrease porous or absorbent materials, such as cloth, leather,
wood or rope.
4. Work loads should not occupy more than half of the degreaser's open
top area.
5. The vapor level should not drop more than 10 cm (4 in) when the
work load enters the vapor zone.
6. Never spray above the vapor level.
7. Repair solvent leaks immediately, or shutdown the degreaser.
8, Do not dispose of waste solvent or transfer it to another party
such that greater than 20 percent of the waste (by weight) will
evaporate into the atmosphere. Store waste solvent only in closed containers.
9. Exhaust ventilation should not exceed 20 m /min per m (65 cfm per ft2)
of degreaser open area, unless necessary to meet OSHA requirements. Ventilation
fans should not be used near the degreaser opening.
10. Water should not be visually detectable in solvent exiting the water
separator.
Control System B
Control Equipment:
1. Cover Csame as in system A}.
2. Safety switches
a. Condenser flow svrftcPi and thermostat - Csfiuts off sump neat if condenser
coolant is either not circulating or too warm).
b. Spray safety switch - (shuts off spray pump if the vapor level drops
excessively, about 10 cm (4 in).
3. Major Control Device:
Either: a. Freeboard ratio greater than or equal to 0.75, and if the
degreaser opening is > 1 m (10 ft'), the cover must be powered,
b. Refrigerated chiller,
c. Enclosed design (cover or door opens only when the dry part
is actually entering or exiting the degreaser.), , „
2 d. Carbon adsorption system, with ventilation >_ 15 m /min per m
(50 cfm/ft ) of air/vapor area (when cover is open), and exhausting <25 ppm
solvent averaged over one complete adsorption cycle, or
e. Control system, demonstrated to have control efficiency,
equivalent to or better than any of the above.
4. Permanent, conspicuous label, summarizing operating procedures #1 to #6.
Operating Requirements:
Same as in System A
vi
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TABLE 3. CONTROL SYSTEMS FOR CONVEYORIZEO DEGREASERS
Control System A
Control Equipment: None
Operating Requirements: 2 ,
., .e
fins should not be used near the degreaser opening.
2. Minimize carry-out emissions by:
:-. ssaaisr-i5=» S^SKJ
3 Do not dispose of waste solvent or transfer It to another party such
ss
4. Repair solvent leaks inmediately, or shutdown the degreaser.
5. Water should not be visibly detectable in the solvent exiting the
water separator.
Control System B
Control Equipment:
1. Major control devices; the degreaser must be controlled by either:
a. Refrigerated chiller, upntiiation > 15 m2/min per m2 (50 cfm/ft2)
b. Carbon ^sorption system wthvent.lat ij5^^' <25 ppm of
or
than either of the above.
or vapor.
3. Safety switches
a Condenser flow switch and thermostat - Cshuts off sump heat if
C°01T ^raylafS S^Si." P-P " Conveyor if the vapor
off sump heat when vapor
level rises too high).
of the opening.
5 ' Down-time covers: Covers should be provided for closing off the
entrance and exit during shutdown hours.
Operating Requirements:
1 to 5 . Same as for System A
and removed just before they are
vn
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TABLE OF CONTENTS
Page
Preface -Hi
Chapter 1.0 Introduction and Summary 1_1
1.1 Need to Regulate Solvent Metal Cleaning 1-1
1.2 Regulatory Approach 1-2
Chapter 2.0 Sources and Types of Emissions 2-1
2.1 Industry Description 2-1
2.2 Types of Degreasers and Their Emissions 2-4
2.2.1 Cold Cleaners 2-7
2.2.1.1 Design and Operation 2-7
2.2.1.2 Emissions 2-12
2.2.2 Open Top Vapor Degreasers 2-16
2.2.2.1 Design and Operation 2-16
2.2.2.2 Emissions 2-25
2.2.3 Conveyorized Degreasing 2-33
2.2.3.1 Design and Operation 2-33
2.2.3.2 Emissions 2-39
2.4 References 2-45
Chapter 3.0 Emission Control Technology 3-1
- 3.1 Emission Control Devices 3-1
3.1.1 Emission Control Devices 3-1
3.1.1.1 Improved Cover 3-2
3.1.1.2 High Freeboard 3-5
vm
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Page
3.1.1.3 Refrigerated Chillers 3"6
3-9
3.1.1.4 Carbon Adsorption
3-14
3.1.1.5 Safety Switches
o -I c
3.1.2' Controls to Minimize Carry-Out
3 l 3 Controls for Both Solvent Bath and 3_18
Carry-Out Emissions Combined
3.1.3.1 Automated Cover-Conveyor System 3-18
o 20
3.1.3.2 Refrigeration Condensation
3.1.4 Control of Waste Solvent Evaporation 3'22
3.1.4.1 Current Practices 3'22
3.1.4.2 Recommended Practices 3"2
3-27
3.1.5 Other Control Devices
•3 OQ
3.1.5.1 Incineration
o oft
3.1.5.2 Liquid Absorption
3-29
3.2 Complete Control Systems
3-30
3.2.1 Cold Cleaning Control Systems °
3.2.2 Control Systems for Open Top Vapor 3_32
Degreasing
3.2.3 Control Systems for Conveyorized Degreasers 3-32
3-37
3.3 References
4-1
Chapter 4.0 Cost Analysis
4-1
4.1 Introduction
4-1
4.1.1 Purpose
4-1
4.1.2 Scope
4-2
4.1.3 Model Plants
4.1.4 Capital Cost Estimates 4"
4-3
4.1.5 Annualized Costs
IX
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Page
4.2 Cold Cleaners 4-4
4.E.I Model Plant Parameters 4-4 |
4.2.2 Control Costs 4-6
4.3 Open Top Vapor Degreasers 4-8
4.3.1 Model Plant Parameters 4-8
4.3.2 Control Costs 4-8
4.3.3 Cost Effectiveness ... 4-14
4.4 Conveyorized Degreasers 4-16
4.4.1 Model Plant Parameters 4-16
4.4.2 Control Costs 4-18
4.4.3 Cost Effectiveness 4-20
4.5 References 4-24
Chapter 5.0 Adverse Environmental Effects of Applying
The Technology 5-1
5.1 Air Impacts 5-1 ^
5.2 Water Impacts 5-1
5.2.1 Waste Solvent Disposal 5-1
5.2.2 Steam Condensate from Carbon Adsorption 5-2
5.2.2.1 Chlorinated Solvent in Steam
Condensate 5-2
5.2.2.2 Stabilizers in Steam Condensate 5-3
5.2.3 Effluents from Water Separators 5-4
5.3 Solid Waste Impact 5-4
5.4 Energy Impact 5-5
5.5 Other Environmental Concerns 5-6
5.6 References 5-8
Chapter 6.0 Compliance Testing Methods and Monitoring
Techniques 6-1
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6 1 Observation of Control Equipment and
Operating Practices
fi—?
6.2 Material Balance
6-3
6.3 Other Emission Tests
Chapter 7.0 Enforcement Aspects
7-2
7.1 Regulatory Approaches
7.1.1 Emission Standards 7"2
7.1.2 Equipment Standards 7~3
7.1.3 Operational Standards 7"4
7.1.4 Solvent Exemption Standards
7.2 Affected Facilities - Priorities 7"5
7.2.1 Definitions of Affected Facilities 7'5
7.2.2 Priorities of Enforcement
Appendix A.O Emission Test Results
Appendix B.O Calculations
XI
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LIST OF TABLES
Page I
Table 1 Control Systems for Cold Cleaning v
Table 2 Control Systems for Open Top Vapor Degreasers vi
Table 3 Control Systems for Conveyorized Degreasers vii
Table 2-1 Common Metal Cleaning Solvents 2-3
Table 2-2 National Degreasfng Solvent Consumption (.1974) 2-5
Table 2-3 Emissions from Solvent Degreasers (1974) 2-6
Table 3-1 Control Systems for Cold Cleaning 3-31
Table 3-2 Complete Control Systems for Open Top Vapor Degreasers .... 3-33
Table 3-3 Control Systems for Conveyortzed Degreasers 3-35
Table 4-1 Cost Parameters for Model Cold Cleaners 4-5
Table 4-2 Control Costs for Typical Cold Cleaners 4-7
Table 4-3 Cost Parameters for Model Open Top Vapor Degreasers 4-9
Table 4-4 Control Cost for Typical Stze Open Top 1/apor Degreaser .... 4-10 M
Table 4-5 Control Cost for Small Open Top 'Vapor Degreaser 4-11
Table 4-6 Cost Parameters for Model Conyeyorfzed Degreasers 4-17
Table 4-7 Control Costs for Typical Conveyorized Degreasers 4-19
xn
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LIST Of FIGURES
Page
Figure 2-1 Cold Cleaner 2~9
Figure 2-2 Cold Cleaner Emission Points 2~13
Figure 2-3 Open Top Vapor Degreaser 2-18
Figure 2-4 Basic Principle for Water Separator for Vapor Degreaser . . 2-20
Figure 2-5 Open Top Degreaser with Offset Condenser Coils 2-21
Figure 2-6 Two Compartment Degreaser with Offset Boiling Chamber . . . 2-22
Figure 2-7 Two Compartment Degreaser z~23
Figure 2-8 Degreaser with Lip Exhaust 2'24
Figure 2-9 Open Top Vapor Degreaser Emission Points 2~26
Figure 2-10 Cross Rod Conveyorized Degreaser 2~35
Figure 2-11 Monorail Conveyorized Degreaser 2-36
Figure 2-12 Vibra Degreaser Z"37
7 *3Q
Figure 2-13 Ferris Wheel Degreaser c"°°
Figure 2-14 Mesh Belt Conveyorized Degreaser 2-40
Figure 2-15 Conveyorized Degreaser Emission Points 2~42
Figure 3-1 Refrigerated Freeboard Chiller 3~7
Figure 3-2 Carbon Adsorber 3"10
Figure 3-3 Adsorption Cycle 3"11
Figure 3-4 Desorption Cycle 3"12
Figure 3-5 Elevator Design of Degreaser - Vapor Type 3-19
Figure 3-6 Vapor Pressures of Several Solvents 3~21
Figure 3-7 -External Still 3"25
Figure 4-1 Cost-Effectiveness of Alternative Control Options for
Existing Open Top Vapor Degreasers ^-'3
Figure 4-2 Cost-Effectiveness of Alternative Control Options for
Existing Monorail Degreasers ^'
Figure 4-3 Cost-Effectiveness of Alternative Control Options for
Existing Cross-Rod Degreasers 4""
xm
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1.0 INTRODUCTION AND SUMMARY
The purpose of EPA's series of control technique guideline documents
is to provide guidance on emission reduction techniques which can be applied
to existing sources in specific industries. The documents are to be used to
assist States fn revising their implementation plans (SIP's) to attain and
Tnafntain National Ambient Air Quality Standards (NAAQS). This document discusses
volatile organic compound (VOC) emissions and applicable control techniques
for organic solvent metal cleaning operations (degreasing with solvents).
1.1 NEED TO REGULATE SOLVENT METAL CLEANING
Solvent metal cleaning is a significant source of volatile organic
compounds (VOC) and tends to be concentrated in urban areas where the
oxidant NAAQS is likely to be exceeded. In 1975 solvent metal cleaning
emitted about 725 thousand metric tons of organics. This represents
about four percent of the national organic emissions from stationary
sources. Presently, solvent metal cleaning is the fifth largest stationary
source of organic emissions. Although emissions from solvent degreasing
(i.e., metal cleaning) represent about four percent of nationwide VOC
sources, the proportion is significantly higher in most urban areas,
because of their high concentration of metalworking industries. For example,
1-1
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the Southern California Air Quality Management District estimates that 14.8
percent of the stationary organic emissions in Los Angeles County are 4
attributable to solvent degreasing.
Control technology is available to reduce hydrocarbon emissions from
existing solvent metal cleaning operations. However, this technology has
not been broadly applied largely because of unawareness of economic
incentives and the absence of regulatory requirements. In 1974, for example,
16 states covered degreasing operations with solvent regulations identical
or similar to Rule 66 of the Los Angeles County Air Pollution Control District.
Since then, additional state and local agencies have adopted the same types of
statutes. Generally, up to 3,000 pounds of VOC emissions per day are allowed
from sources using solvents considered non-photochemically reactive under
Rule 66 criteria. Since solvent metal cleaning operations rarely release
more than that amount, they have usually complied with Rule 66 regulations
merely by substitution. Regulatory incentive to institute control technology A
rather than substitution is necessary to achieve positive emission reduction.
1.2 REGULATORY APPROACH
Photochemical oxidant control strategies in the past have relied heavily
on the substitution of solvents of relatively low photochemical reactivity to reduce
emissions of higher reactivity VOC. Thus, total emissions did not necessarily
decrease, only the make-up of those emissions changed. One problem with this
approach was that many solvents classed as low reactivity materials have since
been found to be moderately and in some cases highly reactive. EPA's current
direction and the direction of this document is toward positive reductions of
all VOC emissions. This is not only more rational from a standpoint of
conservation but some low reactivity solvents are now suspected of contributing
1-2
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to upper atmospheric ozone depletion. These reasons and others support the
decision to concentrate on positive reduction rather than substitution.
Positive emission reduction from solvent metal cleaning should be
attained though use of proper operating practices and retrofit control
equipment. Proper operating practices are those which minimize solvent
loss to the atmosphere. These include covering degreasing equipment
whenever possible, proper use of solvent sprays, various means of reducing
the amount of solvent carried out of the degreaser on cleaned work, prompt
repair of leaking equipment, and most importantly, proper disposal of wastes
containing volatile organic solvents. In addition to proper operating
practices there are many control devices which can be retrofit to degreasers;
however, because of the diversity in their designs, not all degreasers
require all control devices. Small degreasers using room temperature solvent
may require only a cover, whereas a large degreaser using boiling solvent
may require a refrigerated freeboard chiller or a carbon adsorption system.
Two types of control equipment which will be applicable to many degreaser
designs are drainage facilities for cleaned parts and safety switches and
thermostats which prevent large emissions due to equipment malfunction. The
many degreaser designs along with the emissions characteristic of those
designs and the factors affecting those emissions are described in Chapter 2.
Control devices for each type of emission and control systems for each
degreaser design are described in Chapter 3.
1-3
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2.0 SOURCES AND TYPES OF EMISSIONS
2.1 INDUSTRY DESCRIPTION
Solvent metal cleaning describes those processes using non-aqueous
solvents to clean and remove soils from metal surfaces. These solvents,
which are principally derived from petroleum, include petroleum distillates,
chlorinated hydrocarbons, ketones, and alcohols. Organic solvents such as
these can be used alone or in blends to remove water insoluble soils for
cleaning purposes and to prepare parts for painting, plating, repair,
inspection, assembly, heat treatment or machining.
Solvent metal cleaning is usually chosen after experience has indicated
that satisfactory cleaning is not obtained with water or detergent solutions.
Availability, low cost and farniMarily combine to make water the first
consideration for cleaning; however, water has several limitations as a
cleaning agent. For example, it exhibits low solubility for many organic
soils, a slow drying rate, electrical conductivity, a high surface tension
and a propensity for rusting ferrous metals and staining non-ferrous metals.
All of these limitations can be overcome with the use of organic solvents.
A typical industrial deceasing solvent would be expected to dissolve
oils, greases, waxes, tars, and in some cases water. Insoluble matter such
as sand, metal chips, buffing abrasives or fibers, held by the soils, are
flushed away.
2-1
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A broad spectrum of organic solvents is available. Choices among the
solvents are based on the solubility of the soil, toxicity, flammability,
evaporation rate, effect on non-metallic portions of the part cleaned and
numerous other properties. The most important properties of solvents
commonly used in metal cleaning are summarized in Table 2-1.
As would be expected, the metal working industry is the major user of
solvent metal cleaning. Eight SIC codes (Numbers 25 and 33 to 39) cover
these industry categories. Examples of industries within these classifications
are automotive, electronics, appliances, furniture, jewelry, plumbing,
aircraft, refrigeration, business machinery and fasteners. All are frequent
users of organic solvents for metal cleaning. However, the use of solvents
for metal cleaning is not limited to these industries; solvent metal cleaning
is also used in non-metal working industries such as printing, chemicals,
plastics, rubber, textiles, glass, paper and electric power. Often, the
function of the organic solvents in these industries is to provide maintenance
cleaning of electric motors, fork lift trucks, printing presses, etc. Even in
non-manufacturing industries, solvent metal cleaning is commonplace. Most
automotive, railroad, bus, aircraft, truck and electric tool repair stations
use these solvents. In short, most businesses perform solvent metal cleaning,
at least part time, if not regularly. The number of companies routinely using
solvent metal cleaning operations probably exceeds one million. Furthermore,
large scale users may often have over 100 separate degreasing operations at
one plant location.
Solvent metal cleaning is broken into three major categories: cold
cleaning, open top vapor degreasing and conveyorized degreasing. In cold
cleaning operations, all types of solvents are used depending on the type
of parts to be cleaned. Vapor degreasing uses halogenated solvents because
2-2
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Table 2-1
COMMON METAL CLEANING SOLVENTS****
Tvpe of Solvent/
Solvent
Soils
Toxicity Flash Evaporation Solubility
t Rate** & wt.j —
Alcohols
Ethanol (95%)
Isopropanol
Methanol
Aliphatic Hydrocarbons
Heptane
Kerosene
Stoddard
Mineral Spirits 66
Aromatic Hydrocarbons
Benzene***
• SC 150
vj Toluene
'0 Turpentine
Xylene
Chlorinated Solvents ,.4 *«,*•*
Carbon Tetrachloride***
Methylene Chloride
Perchloroethylene
1,1,1-Trichloroethane
Trichloroethylene
Fluorinated Solvents
Trichlorotrifluoro-
ethane (FC-113)
Ketones
Acetone
Methyl ethyl ketone
poor
poor
poor
good
good
good
good
good
good
good
good
good
excellent
excellent
excellent
excellent
excellent
good
good
good
11
1000*
400*
200*
500*
500
200
200
10*
200
200*
100*
100*
10*
500*
100*
350*
100*
60°F
55°F
58"F
<20°F
149°F
105°F
107°F
10°F
151°F
45°F
91°F
81°F
none
none
none
none
none
24.7
19
45
26
0.63
2.2
1.5
132
0.48
17
2.9
4.7
111
363
16
103
62.4
1000*
1000*
200*
none
<0°F
28°F
439
122
45
0.2
27
Boiling Point Pounds
(Ranqe) Per Gal,
165-176°F
179-181°F
147-1498F
201-207°P
354-525-F
313-380°F
318-382'F
176-177eF
370-410°F
230-232°F
314-327'F
281-2848F
170-172°F
104-105. 5°F
250-254-F
165-194eF
188-190°F
6.76
6.55
6.60
5.79
6.74
6.38
6.40
7.36
7.42
7.26
7.17
7.23
13.22
10.98
13.47
10.97
12.14
Price
Per GaLt
$ 1.59
$ 1.26
$ 1.11
$ 0.86
$ 0.66
$ 0.62
$ 0.62
$ 1.06
$ 0.90
$ 2.40
$ 0.96
$ 3.70
$ 2.83
$ 3.33
$ 2.78
$ 3.13
117°F
132-134°F
174-176°F
13.16 $ 7.84
6.59
6.71
•Federal Register, June 27, 1974, Vol 39^No. 125 beaker Qn an analytical balance (Dow Chemical Co
(July 1, 1975).
$ 1.45
$ 1.74
ethod)
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they are not flammable and their vapors are much heavier than air.
The most recent estimates are that there are 1,300,000 cold
cleaning units in the United States, with about 70 percent of these
devoted to maintenance or servicing operations and the remainder used
for manufacturing operations. There are also an estimated 22,000 open
top vapor degreasers and 4,000 conveyorized degreasers. Of the estimated
726,000 metric tons per year of solvent used for degreasing, roughly 60
percent is for cold cleaning, 25 percent for open top vapor degreasing
and 15 percent for conveyorized degreasing. Tables 2-2 and 2-3 summarize
the above information. Emissions are discussed in detail in the next
chapter.
2.2 TYPES OF DEGREASERS AND THEIR EMISSIONS
There are three basic types of organic solvent degreasers: cold
cleaners, open top vapor degreasers, and conveyorized degreasers. Cold
cleaners are usually the simplest and least expensive. Their solvent is
usually near room temperature, but is sometimes heated. The temperature,
however, always remains below the solvent's boiling point. A cold cleaner
is a tank of solvent usually including a cover for nonuse periods. Inside
is a work surface or basket suspended over the solvent. An open top vapor
degreaser resembles a large cold cleaner; however, the solvent is heated to
its boiling point. This creates a zone of solvent vapor that is contained by
a set of cooling coils. Both the cold cleaner and the open top vapor degreaser
clean individual batches of parts; thus, they are termed "batch loaded". A
conveyorized degreaser is loaded continuously by means of various types of conveyor
systems, and may either operate as a vapor degreaser as a cold cleaner.
2-4
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Solvent Type
Table 2-2
National Degreasing Solvent Consumption* (1974)
*^
Solvent Consumption (10 metric tons)
cleaningVapor degreaslng
Halogenated:
Trichloroethylene
1,1,1 Trichloroethane
Perchloroethylene
Methylene Chloride
Tri chl orotri f1uoroethane
Aliphatics
Aromatics:
Benzene
Toluene
Xylene
Cyclohexane
Heavy Aromatics
T53
222
7
14
12
1
12
4T
"276
legreaslng
25
82
13
23
10
128
80
41
7
20
153
162
54
30
30
~~429~
222
46
Oxygenated:
Ketones:
Acetone
Methyl Ethyl Ketone
Alcohols:
Butyl
Ethers
10
8
29
Total Solvents:
Range of Accuracy:
on the above estimates.
Delude!125,000 metric tone^from non boiling conyevorized degreasers.
Includes 75,000 metric tons from conveyorized vapor degreasers.
***
2-5
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Type Degreaser
Table 2-3
Emissions from Solvent Degreasers (1974)
Estimated National
Emission
(103Mt/yr)
Approximate
No. of Units
Nationally
Averaged Emission
Rate per Unit
(Mt/yr)
Cold Cleaners
Open Top Vapor
Degreasers
Conveyorized
Degreasers
380'
200
100
1,220,000
21,000
3,700
0.3
10
27
*380 emission = 450 consumption (from Table 2-2) minus 25 for wiping losses,
25 for conveyorized cold cleaning and 20 for non-evaporative waste solvent
disposal (incineration and non-evaporating landfill encapsulation).
iJ-6
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2.2.1 Cold Cleaners
Cold cleaner operations include spraying, brushing, flushing and
immersion. The solvent occasionally is heated in cold cleaners but always
remains well below its boiling point.
Cold cleaners are defined here not to include nonboiling conveyortzed
degreasers which are covered in Section 2.3. Wipe cleaning is also not
included.
Cold cleaners are estimated to result in the largest total emission
of the three categories of degreasers. This is primarily because of the
extremely large number of these units (over 1 million nationally) and because
much of the disposed of waste solvent is allowed to evaporate. It is
estimated that cold cleaners emit 380 thousand metric tons of organics per
year, this being about 55 percent of the national degreasing emissions
(see Appendix B.I). Cold cleaning solvents nationally account for almost
all of the aliphatic, aromatic, and oxygenated degreasing solvents and
about one-third of halogenated degreasing solvents.
Despite the large aggregate emission, the average cold cleaning unit
generally emits only about one-third ton per year of organics, with about
one-half to three-fourths of that emission resulting from evaporation of
the waste solvent at a disposal site.
2.2.1.1 Design and Operation -
2-7
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Typical Model - A typical cold cleaner is shown in Figure 2-2. The
dirty parts are cleaned manually by spraying and by soaking in the dip tank.
The solvent in the dip tank is often agitated to enhance the cleaning action.
After cleaning, the basket of cleaned parts may be suspended over the solvent
to allow the parts to drain, or the cleaned parts may be drained on an
external drainage rack (not shown) which routes the drained solvent back into
the cleaner. The cover is intended to be closed whenever parts are not being
handled in the cleaner. The cold cleaner described and shown in Figure 2-|
is most often used for maintenance cleaning of metal parts. A typical size
of such a maintenance cold cleaner is about 0.4 m2 (4 ft2) of opening and
about 0.1 m (30 gallon) capacity.
Applications - The two basic types of cold cleaners are maintenance
cleaners and manufacturing cleaners. The maintenance cold cleaners are usually
simpler, less expensive, and smaller. They are designed principally for
automotive and general plant maintenance cleaning.
Manufacturing cold cleaners usually perform a higher quality of cleaning
than do maintenance cleaners and are thus more specialized. Manufacturing
cold cleaning is generally an integral stage in metalworking production.
Manufacturing cold cleaners are fewer in number than maintenance cleaners
but tend to emit more solvent per unit because of the larger size and work
load. Manufacturing cleaners use a wide variety of solvents, whereas
maintenance cleaners use mainly petroleum solvents such as mineral spirits
(petroleum distillates, and Stoddard solvents). Some cold cleaners can
serve both maintenance and manufacturing purposes and thus are difficult
to classify.
The type of cold cleaner to be used for a particular application depends
on two main factors: (1) the work load and (2) the required cleaning
2-8
-------
Figure ?-l
COLD CLEANER
Basket
Solvent
Cleaner
Pump
2-9
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effectiveness. Work load is a function of tank size, frequency of cleaning,
and type of parts. Naturally, the larger work loads require larger degreasers.
The more frequently the cold cleaner is used, the greater the need to automate
and speed up the cleaning process; more efficient materials handling systems
help automate, while agitation speeds cleaning. Finally, the type of parts
to be cleaned is important because more thorough cleaning and draining
techniques are necessitated for more complexly shaped parts.
The required cleaning effectiveness establishes the choice of solvent
and the degree of agitation. For greater cleaning effectiveness, more
powerful solvents and more vigorous agitation are used. Generally, emissions
will increase with agitation and with higher solvency.
Equipment Design - Although classifying cold cleaners according to
maintenance or manufacturing application is a convenient initial approach,
manufacturing cold cleaners vary so widely in design that no one typical
design can adequately describe them. Thus, a more specific classification of
manufacturing cold cleaners must also consider the equipment design. The
most important design factors are tank design, agitation technique, and the
material handling of parts to be cleaned.
The two basic tank designs are the simple spray sink and the drip tank.
The simple spray sink is usually less expensive. It is more appropriate for
cleaning applications that are not difficult and require only a relatively
low degree of cleanliness. The dip tank provides more thorough cleaning
through soaking of dirty parts. Dip tanks also can employ agitation, which
improves cleaning efficiency.
Agitation is generally accomplished through use of pumping, compressed
air, vertical motion or ultrasonics. In the pump agitated cold cleaner,
the solvent is rapidly circulated in the soaking tank. Air agitation involves
2-10
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dispersing compressed air fro. the bottom of the soaking tank; the air bubbles
providing a scrubbing action. In the vertically agitated cold cleaner, dirty
parts move up and down while submerged in order to enhance the cleaning process.
Finally, in the ultrasonically agitated tank, the solvent is vibrated by high
frequency sound waves. Ultrasonically agitated liquids often need to be heated
to specific temperatures to achieve optimum cavitation. Cavitation is the
implosion of microscopic vapor cavities within the liquid solvent. The implosions,
which are caused by pressure differentials of the sound waves in the solvent,
break down the dirt film on the parts.
The designs for material handling in cold cleaning systems are almost
endless, but they are generally divided into manual and batchloaded conveyorized
systems. (Continuously loaded conveyorized systems are described separately in
Section 2.3). Manual loading is used for simple, small-scale cleaning operations
and is self explanatory. Batchloaded conveyorized systems are for use in the
rnore complex, larger-scale cleaning operations. These systems may include an
automated dip, which automatically lowers, pauses, and raises the work load.
They may also include systems, such as a roller conveyor, to transfer the work
load to other operations. In another variation, two or more dip tanks may be
used in series. These tanks may contain increasingly pure solvent in a "cascade--
cleaning system. The consecutive dip tanks may also contain different cleaning
solutions for more complex operations and may even be combined with vapor
cleaning and aqueous systems.
The materials handling technique can be important in reducing emissions
from cold cleaning. Regardless of the system, the work loads need to be handled
so that the solvent has sufficient time to drain from the cleaned parts into an
appropriate container. Drainage facilities are described in Section 3.1.2.
2-11
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2.2.1.2 Emissions -
Solvent evaporates both directly and indirectly from the cold cleaners.
The emission rates vary widely; nevertheless, the average emission rate,
calculated from national consumption data, is estimated to be about 0.3
metric ton per year. Maintenance and manufacturing cold cleaners are
estimated to emit approximately 0.25 and 0.5 metric tons per year, respectively
(see Appendix B.2.2). Data from the Safety Kleen Corporation reports only
0.17 metric tons per year for thier cold cleaner. However, their emissions
are expected to be lower than others because most of the waste solvent from
Safety Kleen units is distilled and recycled by the company.
Emissions from a cold cleaner occur through: (1) bath evaporation, (2)
solvent carry-out, (3) agitation, (4) waste solvent evaporation, and (5)
spray evaporation. These are depicted in Figure 2-2 and discussed in the
following sections.
Bath Evaporation - Bath evaporation can be greatly reduced through use of
a cover. Generally, the cover should be closed whenever the parts are not being
handled in the cold cleaner. Although covers are standard equipment on most
cold cleaners, keeping the cover closed requires conscientious effort on the part
of the operator and his suoervision. As will be discussed in Section 3.1.1, there
are various means of inducing the operator to close the cover more frequently.
Where solvents much more volatile than mineral spirits are used, adequate
freeboard height is important to reduce evaporation. Freeboard height is the
distance from the solvent to the top edge of the cold cleaner. The requirement
for freeboard height is most commonly expressed as freeboard ratio, with freeboard
ratio being defined as the ratio of freeboard height to degreaser width (not
length).
Excessive drafts in the workshop can significantly increase solvent bath
evaporation. Thus, room and exhaust ventilation should be no greater than is
2-12
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BATH/ ,
EVAPORATION /
Figure 2-2. COLD CLEANER EMISSION POINTS
2-13
-------
necessary to provide safe levels for the operator's health and plant's protection.
Agitation Emissions - Agitation increases emissions. The rate of emission
depends upon: (1) use of the cover, (2) agitation system adjustments and (3) vola-
tility of the solvent. If the cover is kept closed during agitation, then emissions
usually are insignificant. However, agitation emissions can increase dramatically
with the cover open. This is especially true with ultrasonic agitation of solvents
heated to their optimum cavitation temperature. The bath should also be agitated for
no longer than necessary to complete the cleaning. Poor adjustment of the agitation
system may also increase emissions. In particular, the air flow into air agitated
3
cleaners should be about 0.01 to 0.03 m per minute per square meter of opening.
EPA tests on cold cleaners indicate that the volatility of the solvent greatly
affects emissions due to agitation. Emissions of low volatility solvents increase
significantly with agitation; however, contrary to what one might expect, agitation
causes only a small increase in emissions of high volatility solvents. This is
believed to be due to the already high unagitated evaporation rate of high volatility
solvents (see Appendix A). Little difference was found between the effects of pump
agitation and air agitation.
Carry-Out Emissions - Carry-out emissions depend on the existence and use of a
drainage facility. Drainage facilities are racks or shelves used for draining excess
solvent off cleaned parts. The drainage facility is standard equipment for some cold
cleaners and is easily and inexpensively retrofitted for most other cold cleaners.
Drainage facilities are described further in Section 3.1.2.
Although installation of a drainage facility is usually no problem, it will
sometimes require a special effort to fully use the facility. As recommended
from ASTM D-26, cleaned parts should drain at least 15 seconds. For rapid
pace work, such as automotive repair, this time may be perceived as too
2-14
-------
delaying; nonetheless, the 15 second drain time should be adhered to.
^ - Waste solvent evaporation is the greatest
source of emissions from cold cleaning. The amount of waste solvent disposed
of depends on the size of the cold cleaner and on the frequency of disposal.
When the cleaning job removes large quantities of oil and other contaminants,
or requires a high degree of cleanliness, the solvent will be disposed of
more frequently. Conversely, if the cold cleaner is equipped with an effective
filter, as many cold cleaners present are, then solid impurities are removed
and disposal is required less frequently.
Waste solvent evaporation depends not only upon the amount but also upon
the method of disposal. Acceptable methods of handling waste solvent include
proper incineration, distillation, and chemical landfilling, where the waste
solvent is buried in enclosed containers and encapsulated by impermeable soil.
Disposal routes that result in total emission to the environment include flushing
into sewers, spreading waste solvent for dust control, such as on dirt roads,
and landfilling where the solvent can evaporate or leach into the soil. Waste
solvent evaporation is discussed further in Section 3.1.4.
Sprav Evaporation - Evaporation from solvent spraying will increase with
the pressure of the spray, the fineness of the spray, and the tendency to splash
and overspray out of the tank. Evaporation is also greater when the spray is
used constantly and when volatile solvents are used. Preferrably, the spraying
pressure should be less than 10 psig, and the spray should be a solid, fluid
stream.2 The solvent loss from overspraying and splashing can usually be
eliminated by sensible design and careful operation.
Solvent Type - The type of solvent is a factor that greatly affects the
emission rate from the cold cleaner. The volatility of the solvent at the
ooeratinq temperature is the sinale most important variable.
2-15
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More toxic organics are rarely used in degreasers, but when they are
they tend to be much better controlled to protect workers and to comply
with OSHA regulations. These include carbon tetrachloride, benzene and
methyl ethyl ketone.
The price of the solvent influences the care that is taken to conserve
it. Thus, more expensive solvents are emitted less. In addition, the higher
the price of the solvent, the more likely that the wastes will be recovered,
and the more economical control will become.
2.2.2 Open Top Vapor Degreasers
Vapor degreasers clean through the condensation of hot solvent vapor on
colder metal parts. Open top vapor degreasers are batch loaded, ue., they
clean only one work load at a time.
Open top vapor degreasers are estimated to result in the second largest
emission of the three categories of degreasers. It is estimated that open
top vapor degreasers emit 200 thousand metric tons of organics per year, this
being about 30 percent of the national degreasing emissions (see Appendix B.3).
2.2.2.1 Design and Operation -
The Cleaning Process - In the vapor degreaser, solvent vapors condense on
the parts to be cleaned until the temperature of the parts approaches the boiling
point of the solvent. The condensing solvent both dissolves oils and provides a
washing action to clean the parts. The selected solvents boil at much lower
temperatures than do the contaminants; thus, the solvent/soil mixture in the
degreaser boils to produce an essentially pure solvent vapor.
The simplest cleaning cycle involves lowering the parts into the vapor
zone so that the condensation action can begin. When condensation* ceases, the
parts are slowly withdrawn from the degreaser. Residual liquid solvent on the
2-16
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parts rapidly evaporates as the parts are removed from the vapor zone. The
cleaning action is often increased by spraying the parts with solvent (below
the vapor level) or by immersing them into the liquid solvent bath.
Basic Design - A typical vapor degreaser, shown in Figure 2-3, is a
tank designed to produce and contain solvent vapor. At least one section of
the tank is equipped with a heating system that uses steam, electricity, or
fuel combustion to boil the solvent. As the solvent boils, the dense solvent
vapors displace the air within the equipment. The upper level of these pure
vapors is controlled by condenser coils located on the sidewalls of the
degreaser. These coils, which are supplied with a coolant such as water, are
generally located around the entire inner surface of the degreaser, although
for some smaller equipment they are limited to a spiral coil at one end of the
degreaser. Most vapor degreasers are also equipped with a water jacket which
provides additional cooling and prevents convection of solvent vapors up hot
degreaser walls.
The cooling coils must be placed at some distance below the top edge of
the degreaser to protect the solvent vapor zone from disturbance caused by air
movement around the equipment. This distance from the top of the vapor zone
to the top of the degreaser tank is called the freeboard and is generally
•
established by the location of the condenser coils. The freeboard is customarily
50 to 60 percent of the width of the degreaser for solvents with higher boiling
points, such as perch!oroethylene, trichloroethylene, and 1,1,1-trichloroethane.
For solvents with lower boiling points, such as trichlorotrifluoroethane
and meth.ylene chloride, degreasers have normally been designed with a
freeboard equal to at least 75 percent of the degreaser width. Higher
freeboards than those recommended will further reduce solvent emissions; however,
there comes a point where difficulty associated with moving parts into and out
2-17
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'. Figure 2-3
OPEN TOP DEGREASER
Safety Thermostat
Condensing Coils
Freeboard
Water Jacket
Condensate Trough
Water Separator
Temperature
Indicator
Cleanout Door
Solvent Level Sight Glass
Heating Elements
Work Rest And Protective Grate
2-18
-------
of a degreaser with a high freeboard outweighs the benefit of increased
emission control.
Nearly all vapor degreasers are equipped with a water separator such as
that depicted in Figure 2-4. The condensed solvent and moisture are collected
in a trough below the condenser coils and directed to the water separator. The
water separator is a simple container which allows the water (being immiscible
and less dense than solvents) to separate from the solvent and decant from the
system while the solvent flows from the bottom of the chamber back into the
vapor degreaser.
Variations in Design - Figure 2-5, 2-6 and 2-7 show the most popular open
top vapor degreasers in use. These units range in size from table top models
with open top dimensions of 1 foot by 2 feet up to units which are 110 feet long
and 6 feet wide. A typical open top vapor degreaser is about 3 feet wide by 6
feet long.
Historically, degreasers of the typical size and smaller have been supplied
with a single piece, unhinged, metal cover. The inconvenience of using this
cover has resulted in general disuse or, at best, use only during prolonged
periods when the degreaser would not be operated, for example on weekends. More
recently, small open top degreasers have been equipped with manually operated
roll-type plastic covers, canvas curtains, or hinged and counter-balanced metal
covers. Larger units have been equipped with segmented metal covers. Finally,
most of the larger open top vapor degreasers (200 square feet and larger) and
some of the smaller degreasers have had manually controlled powered covers.
Lip exhausts such as those shown in Figure 2-8 are not uncommon although
in use en less than half of the existing open top vapor degreasers. These
exhaust systems are designed to capture solvent vapors escaping from the
degreasers and carry them away from the operating personnel. To the extent
2-19
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Figure 2-4
BASIC PRINCIPLE FOR WATER SEPARATOR
FOR VAPOR DEGREASER
SOLA
01
f^
/ENT
JT
V
i
(WATER)
t
(SOLVENT)
J)
WATER
OUT
WET SOLVENT
FROM
CONDENSER
2-20
-------
L Picture 2-5
OPEN TOP DEGREASER WITH OFFSET CONDENSER COILS
Freeboard
Water
Jacket
Heat
Input
Condenser
Coil
Water
Separator
2-21
-------
2-8
DEGREASER WITH LIP EXHAUST
Exhaust Inlet
Exhaust
Duct
Condensing Unit
2-24
-------
that they disturb the vapor zone, they increase solvent losses. For
properly designed exhaust systems, the covers dlose below the
lip exhaust inlet level.
Applications - Open top vapor degreasers are usually less capital intensive
than conveyorized systems, but more capital intensive than cold cleaning
equipment. They are generally located near the work which is to be cleaned at
convenient sites in the plant, whereas conveyorized vapor degreasers tend to be
located at central cleaning stations requiring transport of parts for cleaning.
Open top degreasers operate manually and are generally used for only a small
portion of the workday or shift.
Open top vapor degreasers are found primarily in metal working plants,
as described previously. Furthermore, the larger the plant the more likely
it will use vapor degreasers instead of cold cleaners. Vapor degreasers are
generally not used for ordinary maintenance cleaning of metal parts, because
cold cleaners can usually do this cleaning at a lower cost. An exception may
be maintenance cleaning of electrical parts by means of vapor degreasers because
a high degree of cleanliness is needed and there is intricacy of design.
2.2.2.2 Emissions -
Unlike cold cleaners, open top vapor degreasers lose a relatively small
proportion of their solvent in the waste material and as liquid carry-out.
Rather, most of the emissions are those vapors that diffuse out of the degreaser.
As with cold cleaning, open top vapor degreasing emissions depend heavily on
the operator. The major types of emissions from open top vapor degreasers
are depicted in Figure 2-9.
An average open top vapor degreaser emits about 2.5 kilograms per hour
2 2
per m of opening (0.5 pounds per hour ft ). This estimate is derived from
2-25
-------
en
CD
DIFFUSION AND
CONVECTION
•v.i '/•;••
V\,' '••
CARRY-OUT
CONDENSER
COILS
Figure 2-9. OPEN TOP DECREASED EMISSION POINTS
-------
national consumption data on vapor degreasing solvents and from seven EPA
emission tests summarized in Appendix A. Assuming an average open top vapor
2 2
degreaser would have an open top area of about 1.67 m (18 ft ), a typical
emission rate would be 4.2 kilograms per hour or 9,500 kilograms per year
(9 pounds per hour or 10 tons per year).
Diffusion Losses - Diffusion is the escape of solvent vapors from the
vapor zone out of the degreaser. Solvent vapors mix with air at the top of
the vapor zone. This mixing increases with drafts and with disturbances
from cleaned parts being moved Into and out of the vapor zone. The solvent
vapors thus diffuse into the room air and into the atmosphere. These solvent
losses include the convection of warm solvent-laden air upwards out of the
degreaser.
Diffusion losses from the open top vapor degreaser can be minimized by
the following actions:
a. Closing the cover,
b. Minimizing drafts,
c. Providing sufficient cooling by the condensing coils,
d. Spraying only below the vapor level,
e. Avoiding excessively massive work loads,
f. Maintaining an effective water separator,
g. Promptly repairing leaks.
The cover must be closed whenever the degreaser is not in use. This
includes shutdown hours and times between loads. Cover design is also important.
Improved designs for the cover can make it easier to use thereby facilitating
more frequent closure. Covers should also be designed to be closed while a
part is being cleaned in the degreaser.
Drafts can be minimized by avoiding the use of ventilation fans near the
2-27
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degreaser opening and by placing baffles on the windward side of the degreaser.
A baffle is simply a vertical sheet of material placed along the top of the
degreaser to shield the degreaser from drafts.
Sufficient cooling by the condensing coils should be attained by following
design specifications for the degreaser. Cooling rate is a function of solvent
type, heat input rate, coolant temperature and coolant flow. If the vapor
level does not rise above the midpoint of the cooling coils, then the cooling
4
rate is probably adequate.
The solvent must not be sprayed above the vapor level because such
spraying will cause solvent vapors to mix with the air and be emitted. When
this occurs, the operator should wait for the vapor level to return to normal
and then should cautiously operate the spray wand only below the vapor level.
A massive work load will displace a large quantity of solvent vapor. The
work load should not be so massive that the vapor level drops more than about
10 on (4 inches) as the work load is removed from the vapor zone. Otherwise,
excessive quantities of solvent vapors will mix with the air as the vapor level
falls and rises.
The water separator should be kept properly functioning so that water does
not return to the surface of the boiling solvent sump. Water can combine with
the solvent to form an azeotrope, a constant boiling mixture of solvent and water
that has a lower vapor density and higher volatility than does pure solvent
6
vapor.
Lastly, it is important for any leaks to be repaired properly and promptly.
Special attention should be paid to leaks of hot solvent because hot solvent
evaporates quickly. These leaks may be greater than they appear or go completely
unnoticed.
Carry-Out Emissions - Carry-out emissions are the liquid and vaporous solvent
entrained on the clean parts as they are taken out of the degreaser. Crevices
2-28
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and cupped portions of the cleaned parts may contain trapped liquids or vapors
even after the parts appear to be dried. Also, as the hot cleaned part is with-
drawn from the vapor zone, it drags up solvent vapors and heats solvent-laden
air causing it to convect upwards out of the degreaser.
There are seven factors which directly effect the rate of carry-out
emissions:
a. Porosity or absorbency of work loads,
b. Size of work loads in relation to the degreaser1s vapor area,
c. Racking parts for drainage,
d. Hoist or conveyor speed,
e. Cleaning time in the vapor zone,
f. Solvent trapped in cleaned parts,
g. Drying time.
Porous or absorbent materials such as cloth, leather, wood or rope will
absorb and trap condensed solvent. Such materials should never enter a vapor
zone.
The work load preferably should not occupy more than one-half of the
degreaser's working area. Otherwise, vapors will be pushed out of the
vapor zone by means of a piston effect.
Proper racking of parts is necessary to minimize entrainment (cupping) of
solvent. For example, parts should be positioned vertically with cups or
crevices facing downward.
A maximum hoist speed of 3.3 meters per minute (11 feet per minute) has been
generally accepted as reasonable by the degreasing industry.8 Rushing work
loads into and out of the degreaser will force solvent vapors out into the air
and leave liquid solvent on the cleaned parts which can subsequently evaporate
into the air.
2-29
-------
Cleaning time is the period the work load remains in the vapor zone.
If this is not long enough to allow the work load to reach the temperature
of the condensing vapor, the parts will not dry properly when removed from
the vapor zone. The work load should remain in the vapor zone until the vapors
is
10
9
no longer condense on the parts. Usually, 30 seconds is sufficient;
however, massive work loads may require longer periods.
Before the cleaned parts emerge from the vapor zone, they should be
tipped and/or rotated to pour out any collected liquid solvent. The work load
should be removed from the vapor zone slowly (at a vertical speed not to exceed
11 feet per minute).
Drying time is critical. It should be long enough to allow the solvent
to vaporize from the clean part but not significantly longer. When a hot
dried part rests just above the vapor level, it causes solvent-laden air to
12
heat up and rise. Typically a work load can dry in 15 seconds.
Waste Solvent Evaporation - Solvent emissions may also result from
disposing of waste solvent sludge in ways where the solvent can evaporate
into the atmosphere. The volume of waste solvent in sludge from vapor degreasers
is much less than that from cold cleaners for equivalent work loads for two
reasons. First, the solvent in the vapor degreaser sump can be allowed to become
much more contaminated than the solvent used in a cold cleaner because the
contaminants, with high boiling points, stay in the sump rather than vaporize
into the vapor zone. Second, vapor degreasing solvents are halogenated and as
such are generally more expensive; thus, they are more often distilled and
recycled than cold cleaning solvents.
Although the waste solvent evaporation from vapor degreaser sludge is
usually less than the diffusion and carry-out losses, it still contributes
about 5 to 20 percent of the degreaser's total solvent emissions. When
2-30
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the solvent in the sump accumulates too much oil and other contaminants
problems can occur. The most serious is coating of the heater surfaces, leading
to overheating and subsequent chemical degradation of the solvent.
Thus, the solvent sludge must be cleaned out of the degreaser periodically
and replaced with fresh solvent.
There are four practices that can reduce and nearly eliminate the
atmospheric evaporation from waste solvent disposal:
a. Boil-down,
b. Use of in-house distillation,
c. Use of contract reclamation services,
d. Transfer to acceptable disposal facilities.
Boil-down is a technique of distilling pure solvent from the contaminated
mixture in the degeeaser. As the contaminated solvent is boiled in the sump.
pure solvent vaporizes and condenses on the cooling coils where it is routed
to and stored in a holding tank. Boil-down can usually reduce the solvent
content in the contaminated material to less than 40 to 45 percent by volume.
When production schedules permit further boil-down time,considerably lower
14
levels can be achieved.
In-house distillation can be an efficient and often profitable method of
treating waste solvent. Distilled solvents can normally be reused although
additional stabilizers must be added sometimes. Distillation systems vary from
centralized centers to relatively small external stills for one or more vapor
degreasers. Through distillation, the so>vent content of the waste solvent
sludge can be reduced to about 20 percent by weight (12-15 percent by volume)
in most operations. Additional steam stripping can reduce this further.
Presently most vapor degreaser operators do not use in-house distillation
2-31
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but transfer their waste solvent to another system or company. Even if the
waste solvent is distilled, there are oils and contaminants, called still
bottoms, that require disposal. The preferable disposal methods, for
minimizing solvent evaporation into the atmosphere, are distillation plants
and special incineration plants. Disposal in landfills after evaporation
is also ased but is less desirable. Waste solvent disposal is discussed
in greater detail in Section 3.1.4.
Exhaust Emissions - Exhaust systems are often used on larger than average
open top vapor degreasers. These systems are called lip or lateral exhausts
and they draw in solvent-laden air around the top perimeter of the degreaser.
Although a collector of emissions, an exhaust system can actually increase
evaporation from the bath, particularly if the exhaust rate is excessive.
Some exhaust systems include carbon adsorbers to collect the exhaust solvent
for reuse; thus, exhaust emissions can be nearly eliminated if the adsorption
system functions properly.
In some poorly designed exhaust systems, the ventilation rate can be too
high. If the air/vapor interface is disrupted by high ventilation rates, more
solvent vapors will mix with air and be carried out by the exhaust system. A
rule of thumb used by manufacturers of degreaser equipment and control systems
is to set the exhaust rate at 50 cubic feet per minute per square foot of
3 ? 1 fi
degreaser opening (15 m per minute • m ).
The primary objective of exhausting is to assure that the threshold limit
value (TLV) as adopted by OSHA is not exceeded. The exhaust level recommended
above is satisfactory for OSHA requirements on ventilation except when the quality
of operation of the degreaser is rated as "average" or "poor." Poor operation is
noted by OSHA to include excess carry-out of the vapor and liquid solvent,
contamination of the solvent, or improper heat balance. In these cases, and
2-32
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for solvents with a TLV <_100 opm, the minimum OSHA ventilation requirement is
75 or TOO cubic feet per minute per square foot of degreaser opening,
Consequently, atmospheric emissions from poorly operated degreasers are
increased even further.
2.2.3 Conveyorized Degreesing
There are several types of conveyorized degreasers, operating both with
cold and vaporized solvents. An average conveyorized degreaser emits about
25 metric tons per year of solvent; however, because of their limited numbers they
contribute only about 15 percent of the total solvent degreasing emissions.
Because of their large work capacity conveyorized degreasers actually emit
less solvent per part cleaned than either open top vapor degreasers or cold
cleaners. Controls discussed in Chapter 3 can reduce this amount still
further.
2.2.3.1 Design and Operation -
In conveyorized equipment, most, and sometimes all, of the manual parts
handling associated with open top vapor degreasing has been eliminated.
Conveyorized degreasers are nearly always hooded or covered. The enclosure
of a degreaser diminishes solvent losses from the system as the result of air
movement within the plant. Conveyorized degreasers are used by a broad
spectrum of metalworking industries but are most often found in plants where
there is enough production to provide a constant stream of products to be
degreased.
There are seven main types of conveyorized degreasers: monorail, cross-rod,
vibra, fern's wheel, belt, strip, and circuit board cleaners. While most of the
seven types of conveyorized degreasers may be used with cold or vaporized solvent,
the first four are almost always vapor degreasers.
2-33
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The cross-rod degreaser (Figure 2-10)obtains its name from the rods
between the two power driven chains from which parts are supported as they
are conveyed through the equipment. The parts are contained in pendant
baskets or, where tumbling of the parts is desired, perforated cylinders.
These cylinders are rotated by a rack and pinion design within the solvent
and/or the vapor zone. This type of equipment lends itself particularly
well to handling small parts which need to be immersed in solvent to obtain
satisfactory cleaning or requires tumbling to provide solvent drainage from
cavities in the parts.
A monorail vapor degreaser (Figure 2-11) is usually chosen when the
parts to be cleaned are being transported between manufacturing operations
using a monorail conveyor. This design lends itself to automatic cleaning
with solvent spray and vapor. The parts can be moved in one side and out the
other, as illustrated, or they can turn 180° while in the vapor or spray
portions of the equipment and exit the equipment through a tunnel parallel to
the entrance.
In a vibra degreaser (Figure 2-12) dirty parts are fed through a chute
which directs them into a pan flooded with solvent. The pan is connected
to a spiral elevator. The pan and spiral elevator are vibrated,
causing the parts to move from the pan ap the spiral to the exit chute. The
parts condense solvent vapor as they are vibrated up the spiral and dry as
soon as they leave the vapor zone. These degreasers are capable of processing
quantities of small parts. Since the vibratory action creates considerable
noise, acoustical insulation of the equipment is needed or the system must be
enclosed in a noise-control booth.
Three other typical units are the ferris wheel, belt, and strip degreasers
The ferris wheel degreaser (Figure 2-13) is one of the least expensive and
2-34
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.Figure 2-10
CROSS-ROD CONVEYOlRIZED DEGREASER
Conveyor.
Path
Chain
Supports
Work
Basket
Cross Rods
Water
Jacket
Boiling Chamber
2-35
-------
i Elflure 2-11
MONORAIL CONVEYORIZED DEGREASER
Spray
Pump
Bo i
Chamber
Water
Jacket
2-36
-------
I Figure 2-12
VIBRA DEGREASER
Workload Discharger Chute
Ascending
Vibrating
Trough
Condensers
Distillate
Trough
Workload
Entry Chute
Distillate Return
For Counter-
flow Wash
2-37
-------
Figure 2-13
FERRIS WHEEL DEGREASER
Work
Basket
Sear to tumble
baskets
Boiling
Chamber
2-3b
-------
smallest conveyorized degreasers. It generally uses perforated baskets,
as does the cross-rod degreaser. The belt degreaser is designed to enable
simple and rapid loading and unloading of parts (see Figure 2-14). A strip
degreaser resembles a belt degreaser, except that the strip itself is being
cleaned. The strip degreaser is an integral step in the fabrication and
coating of some sheet metal products.
Circuit board cleaners are conveyorized degreasers which use one of the
previously described designs specifically in the production of printed circuit
boards. There are three types of circuit board cleaners: developers,
stripoers, and defluxers. In the production of circuit boards, ultraviolet rays
are projected through a film of an electrical circuit pattern to create an
image on a copper sheet covered with resist. The developer degreaser dissolves
off the unexposed resist. This copper covered board is then dipped in an acid
bath to etch away the copper that is not covered by the hard, developed
resist. Next, the stripper degreaser dissolves off the developed resist.
Then a wave of solder passes over the bare copper circuit and bonds to it.
Lastly, the defluxer degreaser dissolves off the flux left after the solder
hardens. Because of the nature of the materials being cleaned, circuit board
cleaners can use cold (room temperature) solvents, as well as vapor
degreasing processes.
2.2.3.2 Emissions -
About 85 percent of the conveyorized degreasers are vapor types, leaving
15 percent as conveyorized non-boiling degreasers. Circuit board cleaners
represent most of the non-boiling conveyorized degreasers.1 An average
emission rate from a conveyorized vapor degreaser is about 25 metric tons
per year, while that for non-boiling conveyorized degreasers is almost 50
metric tons per year. However, most new designs for non-boiling conveyorized
2-39
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Fiqure t-14
MESH BELT CONVEYORIZEO DEGREASER
Conveyor;
Path
Boil ing
Chamber
-------
degreasers are far more efficient than the older designs.18 It is estimated
that the vapor types presently contribute about 75 percent of the conveyorized
degreaser emissions nationally and the non-boiling types contribute the
remaining 25 percent. On the national scale, about 75,000 metric tons/year
are emitted from conveyorized vapor degreasers, and about 25,000 metric tons/
year are from conveyorized non-boiling degreasers .(see Appendix B.4). The
major types of emissions from conveyorized degreasers are depicted in Figure 2-15.
Bath Evaporation - For an equivalent work load, the diffusion and convection
of solvent vapors from the solvent bath are considerably less for conveyorized
degreasers than for open top degreasers. This is because the conveyorized de-
greasers are normally enclosed except for a relatively small entrance and exit.
Because conveyorized degreasers are generally automated, operating practice
is a minor factor while design and adjustment are major factors affecting
emissions. Proper adjustment of the degreasing system primarily affects bath
evaporation and exhaust emissions, while operation and degreaser design affect
carry-out and waste solvent evaporation.
The main adjustment affecting the bath evaporation rate is the heating
and cooling balance. Basically, the cooling supplied by the primary
condensing coils should be sufficient to condense all the vaporized solvent.
Also, the heating rate needs to be large enough to prevent the vapor level
from dropping as cold parts enter the vapor zone*
With regard to equipment design, bath evaporation can be reduced by
19
minimizing the entrance and exit areas and by regulating the spray system.
Naturally the smaller the area of opening, the lower the loss of solvent
vapors. Partial covers can be placed over the openings which silhouette the
parts to be cleaned yet give enough margin for safe passage. Sprays should be
designed or adjusted so that they do not cause turbulence at the air/vapor
interface. Spray pressure should the minimum necessary for proper performance
2-41
-------
ro
i
IV)
DIFFUSION AND
CONVECTION
®
WASTE SOLVENT
Figure 2-15. CONVEYORIZED DEGREASER EMISSION POINTS
-------
One well designed system uses the high pressure spray in a contained and
partially submerged chamber.
Poor operation can increase convective losses from the solvent bath.
For instance, if work baskets are overloaded the vapor zone may collapse
increasing air vapor mixing and, thus, emissions. This can be avoided by
following the manufacturer's specification for allowable work load in tons
per hour, which is determined through an energy balance of the system. The
heating capacity of the solvent boiler must be greater than the heat loss due
to solvent condensation on the work load. Evaporative losses from the bath
also increase when there is delay in solvent leak repair.
Carry-Out Emissions - Carry out of vapor and liquid solvent is usually
the major emission from conveyorized degreasers. It is difficult to reduce
carry-out emissions, because the amount of work load is inherently large.
Two factors affecting carry-out emissions are the drainage of cleaned
parts and their drying time. Parts drainage is improved by proper racking,
as was discussed for open top vapor degreasing. Racking is especially critical
in conveyorized degreasers, because there is little an operator can do to
reduce carry-out from a poorly designed system. The degreaser design should
allow sufficient space and time for the cleaned parts to dry completely. Some
designs include a shroud extending from the exit to form a drying tunnel. Again
the conveyor speed should not exceed 3.3 meters per minute (11 feet per minute)
?n
vertical rise.
Exhaust Emissions - In some cases the emissions can be high because of
an excessive ventilation rate. As with open top vapor degreasers the ventilation
rate should not be much greater than 15 m3/min-m2 (50 cfm/ft2) of air/solvent
21
interface.
2-43
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Waste Solvent Evaporation - Evaporation from waste solvent disposal is
the smallest emission from conveyorized degreasers. Most conveyorized
degreasers are designed to distill their own solvent. An external still is
attached to the conveyorized degreaser so that used solvent can be constantly
pumped out, distilled and returned. Thus, the wastes will usually
consist only of still bottoms. Still, because of the high volume, waste solvent
emissions from conveyorized degreasers are significant, typically equalling
oo
10 to 20 percent of the total emissions from a conveyorized degreaser.
As was discussed earlier, the method of disposal of the still bottoms
or undistilled waste solvent will determine the amount of solvent that
evaporates into the atmosphere.
2-44
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REFERENCES
1. T. J. Kearney, "Reply to J. C. Bellinger letter of September 3, 1976,"
letter of October 1976.
2. American Society for Testing and Materials (ASTM), Committee D-26,
"Recommended Practice for New Source Performance Standards to Control
Solvent Metal Cleaning Emissions."
3. Surprenant, K. S. and Richards, D. W. of Dow Chemical Company, "Study
to Support New Source Performance Standards for Solvent Metal Cleaning
Operations," Volume 2, Appendix C.-12, prepared for Emission Standards
and Engineering Division (ESED), under Contract # 68-02-1329, Task Order
#9, June 30, 1976.
4. Information provided by K. S. Surprenant by telephone to J. C. Bellinger
EPA, March 3, 1977.
5. Dow Chemical Company, "Modern Vapor Degreasing," operating manual, Form #
100-5185-72.
6. ASTM, D-26., "Handbook of Vapor Degreasing," ASTM Special Technical
Publication 310 A, Philadelphia, April, 1976.
7. Detrex Chemical Ind., Inc., Detroit, "Todays' Concepts of Solvent
Degreasing," operating manual.
8. ASTM, D-26, Op. Cit.
9. Ibid.
10. Surprenant, Op. Cit.
11. American Society for Testing and Materials Op. Cit.
12. Surprenant, Op. Cit.
13. "Trip Report - Meeting of ASTM Committee D-26 on Halogenated Organic Solvents,
Gatlinburg, Tenn.", EPA memorandum from J. L. Shumaker to D. R. Patrick,
June 30, 1977.
2-45
-------
14. Information provided by Detrex Chemical Industries, Inc., Letter from
L. Schlossberg to J. L. Shumaker, June 28, 1977.
15. Surprenant, Op. Cit.
16. ASTM, D-26, Op. Cit.
17. Bellinger, J. C., "Maximum Impact of NSPS on 1985 National Degreasing
Emissions," December, 1975.
18. Information provided by Bob Porter of Hollis Engineering Company, Nashua,
N. H. by telephone to J. C. Bellinger, EPA, March 28, 1977.
19. American Society, Op. Cit.
20. ASTM, D-26, Op. Cit.
21. Information, K. S. Surprenant, Op. Cit.
22. Ibid.
2-46
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3.0 EMISSION CONTROL TECHNOLOGY
This chapter describes individual emission control devices applicable
to solvent degreasers, and then shows how these can be combined to form
complete control systems. Estimates are also provided of the control
efficiency (i.e., percent emission reduction) of individual control devices
along with a range of control efficiency for the complete control systems.
It is important to keep in mind that optimum control systems will not
be equivalent for each degreaser design or even each application of a
particular design. All of the major devices discribed in this chapter will
yield optimum control in certain instances; however, because degreaser
designs and applications vary, one or more of these devices could be
completely unsuitable for a given degreaser. Processes must be evaluated
individually to determine the optimum control system. The individuality
of systems is such that control efficiencies estimated in this chapter are
not directly comparable and should not be used to rate one device against
another. They are given only as general levels of control which one could
expect from appropriately applied technology.
3.1 EMISSION CONTROL DEVICES
3.1.1 Solvent Bath Emissions
There are five main devices that can reduce emissions from the solvent
bath:
1. Improved cover,
2. High freeboard,
3-1
-------
3. Refrigerated chillers,
4. Carbon adsorption,
5. Safety switches.
3.1.1.1 Improved Cover -
The cover is the single most important control device for open top vapor
degreasers. Although covers are normally provided on open top degreasers
as standard equipment, they can usually be made more easy to use, and hence
more frequently used, if they are mechanically assisted, powered or automated.
For vapor degreasers the cover should open and close in a horizontal
motion, so that the air/vapor interface disturbance is minimized. These
types of covers include roll type plastic covers, canvas curtains and
guillotine covers. It is usually advantageous on larger open top vapor
degreasers to power the cover. This may be done pneumatically or electrically,
usually by manual control with an automatic cut off. The most advanced covering
systems are automated in coordination with the hoist or conveyor. The cover
can be designed so it will close while the parts are being cleaned and dried.
Thus, the cover would only be opened for a short period of time when the parts
are actually entering or exiting the degreaser. This is further described in
Section 3.1.3.1.
On cold cleaners, covers are frequently mechanically assisted by means
of spring loading or counterweighing. A pedal operated or powered system
can make the cover even more convenient to use. For specific applications,
two additional types of covers can be used; these are the submerged cover
and the water cover. The submerged cover (commercially termed "turbulence
baffle") is a horizontal sheet of material submerged about two inches below
the surface of the liquid solvent that is vigorously pump agitated. The
water cover is simply a layer of water about two to four inches thick over a
3-2
-------
halogenated solvent. The water cover cannot be used in many applications, however
because the water may corrode the metal surface of the cleaned parts or may
cause chemical degradation of halogenated solvent.
Covers on cold cleaners which use flammable solvents generally have a
fusible link in the support arm. This link is designed to open if the solvent
catches fire, thus allowing the cover to close and smother the flames.
Unfortunately, some designs require disassembly of the mechanism for normal
closing of the cover. These designs cause unnecessary emissions and should be
avoided.
Not all cold cleaner designs include a soaking feature. Some of the
smaller maintenance units are designed with an enclosed sump from which solvent
is pumped to a sink for cleaning parts. The sink drains back to the sump,
minimizing the time during which solvent can evaporate. Although the solvent
is contained, these units generally include a cover on the sink as a fire
prevention feature. It is doubtful that closing this cover can effect a
significant additional emission reduction.
Even though conveyorized degreasers are basically covered by design,
additional cover related control can be achieved by minimizing the openings*/
and covering the openings during shutdown hours. ASTM has recommended that
there not be more than 6 inches (15 cm) clearance between the parts on the
conveyor and the sides of the opening.1 This clearance can be specifically
defined as the average distance between the edge of the openings and the part,
and termed the "average silhouette clearance." Average silhouette clearance
can be appreciably less than 6 inches (15 cm) for parts that are not unusually
large. EPA recommends an average silhouette clearance of 4 inches (10 cm) or
10 percent of the opening's width.
3-3
-------
Covers can be easily made for the entrance and exit to the conveyorized
degreaser so that they can be closed immediately after shutting down the
degreaser. These covers can be made of any material that impedes drafts
into the degreaser and should cover at least 80 to 90 percent of the
opening. Closing these covers is most important during the hours immediately
after shutdown, because the hot solvent is cooling and evaporation continues.
Even after the solvent sump has cooled, the down-time cover may be significantly
effective for more volatile vapor degreasing solvents.
A cover on an open top vapor degreaser has been shown to reduce total
emissions by approximately 20-40 percent depending upon the frequency of
2
its use.
It is impossible to estimate a single control efficiency for the cold
cleaning cover, because the emission reduction varies too greatly with respect
to the solvent volatility, draft velocity, freeboard ratio, operating temperature
and agitation. However, it can be estimated that bath evaporation rate varies (
directly with the solvent volatility at operating temperature. Although a
closed cover can nearly eliminate the bath evaporation, the cover can do nothing
to reduce the carry-out or waste solvent emissions. Thus, a normally closed
cover becomes effective only when bath evaporation accounts for an appreciable
portion of the total emission. More specifically, when solvent volatility is
moderate to high (approximately > 0.3 psi at 100°F (2.1 kPa at 38°O), it is
significantly effective to close the cover at all times when parts are not
being cleaned manually in the cold cleaner. It is especially important that
the cover be closed when the bath is agitated or heated. If none of these
conditions apply, then the cover should at least be closed during long periods
3
of cold cleaner disuse, such as during shutdown hours and idle periods > 1/2 hour.
3-4
-------
The effectiveness of a down-time cover on conveyorized degreasers should
be significant, although it is difficult to quantify. One test found that
about 18 percent of the total emissions was due to evaporation during down-time.
It is expected that most of this loss could be eliminated by a down-time cover.
3.1.1.2 High Freeboard -
The freeboard primarily serves to reduce drafts near the air/solvent
interface. An acceptable freeboard height 1s usually determined by the freeboard
ratio, the freeboard height divided by the width (not length) of the degreaser's
air/sol vent area.
Normally the freeboard ratio is 0.5-0.6 for the open top vapor degreasers,
except for very volatile solvents, such as methylene chloride or fluorocarbon
solvents, where a minimum freeboard ratio of 0.75 is used. In fact, the
American Society for Testing and Materials has recommended that a minimum
freeboard ratio of 0.75 be an alternative control for open top degreasers using
5
all solvents.
For an open top vapor degreaser that is idling (has no work load), the
emission reduction from raising a freeboard ratio from 0.5 to 0.75 may typically
be 25-30 percent. In fact, an increase in ratio from 0.5 to 1.0 may yield
about a 50 percent reduction in emissions. These are EPA estimates based on
a test by Dow Chemical,6 The total emission reduction due to the freeboard
will generally be less for open top vapor degreasers under normal work load,
because the freeboard is less effective in reducing the carry-out emissions
than solvent bath emissions.
The freeboard height seems to have little effect on cold cleaners using
solvents with low volatilities, such as mineral spirits, but provides significant
benefits for cold cleaners using higher volatility solvents, such as the
halogenated ones. OSHA requires at least a 6 inch (15 cm) freeboard for
cold cleaners.
3-5
-------
3.1.1.3 Refrigerated Chillers -
The vapors created within a vapor degreaser are prevented from overflowing
the equipment by means of condenser coils and a freeboard water jacket.
Refrigerated freeboard chillers add to this basic system a second set of
condenser coils located slightly above the primary condenser coils of the
degreaser (see Figure 3*1). Functionally, the primary condenser coils
control the upper limit of the vapor zone. The refrigerated freeboard
chilling coils on the other hand impede the diffusion of solvent vapors from
the vapor zone into the work atmosphere by chilling the air immediately above
the vapor zone and creating a cold air blanket. The cold air blanket results
in a sharper temperature gradient. This reduces the mixing of air and solvent
vapors by narrowing the air/vapor mixing zone. Finally, the chilling produces a
stable inversion layer which decreases the upward convection of solvent laden air.
Freeboard chillers operate with refrigerant temperatures in the range of
*
-30 to 5°C. Although there is a patent on units which operate below 0°C,
most major manufacturers of vapor degreasing equipment offer both above
and below freezing freeboard chillers.
The recommended operating temperature for below freezing chillers is
-30 to -25°C. Because of these low temperatures, designs must include a timed
defrost cycle to remove the ice from the coils and restore the heat exchange
efficiency. Although the liquid water formed during the defrost cycle is
directed to the water separator, some water contamination of the vapor
degreasing solvents is not uncommon. Water contamination of vapor degreasing
solvents can have an adverse effect on water soluble stabilizer systems,
although major stabilizer depletions from this are rare. Water, however,
contributes to equipment corrosion and can diminish the working life of the
equipment significantly.
US Patent 3,375,177 issued to AutoSonics Inc., March 26, 1968.
3-6
-------
I Figure 3-j__
REFRIGERATED FREEBOARD CHILLER
Chiller
Primary
Coils
Water Jacket
3-7
-------
Refrigerated freeboard chillers are normally sized by specifying
the cooling capacity per length of perimeter. The above freezing refrigerated
freeboard chiller is normally designed to achieve a minimum of 500 Btu/hr
(865 W/m-°K) cooling capacity per foot of air/vapor interface perimeter, while
the below freezing refrigerated freeboard chiller is normally designed to
the following specifications:
Minimum Cooling Capacity
Degreaser Width (Btu/hr ft of perimeter)
< 3.5 ft. (1.1 m) 200
> 3.5 ft. (1.1 m) 300
> 6 ft. (1.8 m) 400
> 8 ft. (2.4 m) 500
> 10 ft. (3.0 m) 600
Normally each pass of finned cooling coil is expected to remove 100 Btu/hr
o
ft (173 W/m-°K). The previous specifications are typical design standards
used by manufacturers of chillers. EPA test data indicate that these design
standards will provide satisfactory emission control, but at present data are
insufficient to confirm that they yield optimum emission control.
In addition to these, a third type of refrigerated chiller, known as
the refrigerated condenser coil, is available. Refrigerated condenser coils
do not provide an extra set of chilling coils as the freeboard chillers do,
but replace the primary condenser coils. If the coolant in the condenser
coils is refrigerated enough, it will create a layer of cold air above the
air/vapor interface. DuPont and Rucker Ultrasonics have recommended that the
cooling rate of refrigerated condenser coils be equal to 100-120 percent of
the heat input rate in the boiling sump, in order to give optimum emission
Q
control. The refrigerated condenser coils are normally used only on small
open top vapor degreasers (especially with fluorocarbon solvent), because
3-8
-------
energy consumption may be too great when used on larger open top vapor degreasers.
The refrigerated condenser coil offers portability of the open top vapor
degreaser by excluding the need for plumbing to cool condenser coils with
tap water.
Tests have been performed for EPA on three below freezing refrigerated
freeboard chillers. Emission reductions of 16, 43, and 62 percent were
measured.10 The chiller which achieved only a 16 percent reduction in emissions
was installed around 1968 and the design was not representative of present
designs. This degreaser also had a low "uncontrolled" emission rate of
0.14 Ib/hr ft2, partly due to the use of a cover. The units which achieved
43 and 62 percent reduction in emissions are thought to be more representative
of present designs.
EPA has not performed tests on above freezing freeboard chillers or
refrigerated condensing coils. However, tests are planned which should
help quantify the effectiveness of these controls.
Chillers are not normally used on cold cleaners. While it is certain
that a chiller would reduce emissions, especially from units using the more
volatile solvents, this control is generally too expensive for a normal cold
cleaner. A chiller on a cold cleaner should have about the same effectiveness
as a normally closed cover, but it would cost considerably more. In fact, a
chiller could well cost more than the cold cleaner itself. Still, some
manufacturing cold cleaners with unusually high emission rates could find
a chiller appropriate.
3.1.1.4 Carbon Adsorption -
Carbon adsorption systems are widely used to capture solvent emissions
from metal cleaning operations. On appropriate degreasing processes, these
devices can achieve high levels of emission control. Equipment design and
operation (as illustrated in Figures 3-2, 3-3, and 3-4) are fairly well
3-9
-------
Figure 3-2. CARBON ADSORBER
Solvent-Laden Air Inlet
co
o
Steam Line
Clean Air Exhaust
-------
Figure 3-3
ADSORPTION CYCLE
Solvent-Laden
Air Inlet
Activated Carbon
Bed
Clean Air
Exhaust
3-11
-------
Figure 3-4
DESORPTION CYCLE
Condenser
Recovered 4~
Solvent
Solvent laden
steam
Activate
Carbon
3-12
-------
standardized and described in detail in general literature, in the Dow
n 12
Report and in the report by JACA Corporation.
A well designed and maintained carbon adsorption system will normally
capture in excess of 95 percent of the organic input to the bed. Carbon
adsorption systems for solvent metal cleaning normally will achieve about
13
40-65 percent reduction of the total solvent emission. One reason for
the difference between the theoretical awl actual tsr that tfie ventilation apparatus
of the control system cannot capture all of the solvent vapors and deliver
them to the adsorption bed. As has been discussed earlier, major loss
areas are drag-out on parts, leaks, spills, and disposal of waste solvent, none
of which are greatly affected by the ventilation system. Improved ventilation
design can increase an adsorber's overall emission control efficiency.
Higher ventilation rate alone, however, will not necessarily be advantageous,
since increased turbulence could disrupt the air/vapor interface causing an
increase in emissions, all of which would not be captured by the collection
systems. The effectiveness of the ventilation system can also be improved
through use of drying tunnels and other devices which decrease losses due
to dragout.
Poor operation has been found to decrease the control efficiency of
carbon adsorption systems. Examples are dampers that do not open and close
properly, use of carbon that does not meet specifications, poor timing of
the desorption cycles, and excessive inlet flow rates. Desorption cycles
must be frequent enough to prevent breakthrough of the carbon beds, but not
so frequent as to cause excessive energy waste. The degreaser's air/vapor
interface may be disturbed as a result of excessive adsorber inlet flow. This
can increase losses due to low adsorber inlet collection efficiency. Good
3-13
-------
operating practice and proper maintenance will eliminate all of the above
problems.
Carbon adsorption systems can effect the highest achievable level of
emission control for many degreasing operations. Its positive aspects are
well known. There are, however, a few negative aspects that should be
mentioned. First, where solvent mixtures are used, the collected solvent
emissions will be richer in the more volatile components. Thus, the
recovered solvent mixture is rarely identical to that used in the cleaning
system. Second, there are solvent components that are water soluble. Examples
are acetone or et%.J alcohol used as co-solvents with trichlorotrifluoroethane and
various stabilizers added to many solvents to inhibit decomposition. These, water
soluble components will be selectively extracted by the steam during the desorption
process. In these cases, fresh solvent, stabilizers and/or co-solvents must
be added to the recovered solvent before it is reused.
Tests performed on carbon adsorption systems controlling an open top
vapor degreaser and a conveyorized non-boiling degreaser, measured 60 and
65 percent emission reduction respectively. These levels of control are
typical of properly designed,adjusted and maintained adsorption systems on
degreasing operations which are suitable for this type of control. Three
other carbon adsorption systems were tested and found to have low control
efficiencies. Two of these systems achieved 21 percent and 25 percent emission
15
reductions. A third was found to actually increase emissions by 8 percent.
These tests exemplify the need for proper application, design, operation,
and maintenance of carbon adsorption systems.
3.1.1.5 Safety Switches -
Safety switches are devices used on vapor degreasers to prevent emissions
during malfunctions and abnormal operation. The five main types of safety
3-14
-------
switches are:
1. Vapor level control thermostat,
2. Condenser water flow switch and thermostat,
3. Sump thermostat,
4. Solvent level control,
5. Spray safety switch.
The first four safety switches listed above turn off the sump heat while the
fifth turns off the spray.
The most important safety switch is the vapor level control thermostat.
This device is activated when solvent vapor zone rises above the designed
operating level. This can occur if the coolant flow is interrupted, for
example. When the hot vapors are sensed, the sump heater is turned off thus
minimizing vapor escape. This thermostat should be a manual reset type for
manually operated degreasers. For conveyorized degreasers, the vapor level
control thermostat should activate an alarm system. These controls should
be checked frequently.
The condenser water flow switch and thermostat turn off the sump heat
when either the condenser water stops circulating or the condenser water becomes
warmer than specified. If the condenser water flow switch and thermostat is
properly adjusted, then it will serve as a back-up for the safety vapor
thermostat and also assure efficient operation of the condenser coils.
In summer months, the cooling water for condensing coils often becomes too
warm. In this case, the thermostats in a condenser water flow switch can
signal a need for improvement, such as increasing the water flow rate. This
problem occurred during a test performed for EPA.
As oils, greases and other contaminants build up in the solvent, the
boiling point of the mixture increases. Both the sump thermostat and solvent
3-15
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level control prevent the sump from becoming too hot, thus causing solvent
decomposition. The sump thermostat cuts off the heat when the sump temperature
rises significantly above the solvent's boiling point. The solvent level
control turns off the heat when the liquid level of the boiling sump drops
down to the height of the sump heater coils. Without these controls,
excessive heat could decompose the solvent, emitting such things as hydrochloric
acid.
The spray safety switch is not used as often as the other safety switches,
but it can offer a significant benefit. Specifically, if the vapor level
drops below a specified level, then the pump for the spray application will
be cut off until the normal vapor level is resumed. Thus, the spray safety
switch prevents spraying above the vapor level which causes excessive
emissions.
The effectiveness of the five safety switches cannot be quantified
because their operation results from poor degreaser maintenance and use.
Nevertheless, considering the fact that vapor degreasers do not always
receive proper attention and maintenance, it is expected that the safety
switches will provide a significant reduction in emissions for typical vapor
degreasing operations.
3.1.2 Controls to Minimize Carry-out
Carry-out emissions are the solvent emissions that result when clean
parts still containing liquids or vapors are extracted from the vapor degreaser.
As described in chapter 2, good operating practices are the primary method of
reducing carry-out emissions. Furthermore, there are devices that can help
minimize the carry-out from cold cleaners and conveyorized degreasers, but
not generally from open top vapor degreasers.
3-16
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The main control device for carry-out emissions from cold cleaners is
a simple drainage facility. The two types of drainage facilities are the
external and internal drainage racks (or shelves). The external drainage rack
is attached to the side of the cold cleaaer at the top. The liquid solvent
from the cleaned parts drains into a tra«jj| ami is returned to the cold cleaning
bath. This control is Inexpensive Sal easily wtrotttted. An internal
drainage facility is located beneath the cover. It may be a basket that
is suspended over the solvent bath, or a shelf from which the solvent drains.
Particularly with solvents of higher volatilities (i.e., much greater than
that of mineral spirits), an internal drainage facility can prevent a
significant solvent emission. The internal drainage facility sometimes cannot
be reasonably retrofitted, because there may not be enough room inside the
cold cleaner to drain parts while cleaning other parts.
The main control devices for carry-out emissions from conveyorized
degreasers are a drying tunnel and rotating baskets. A drying tunnel is
simply an extension from the exit of the conveyorized degreaser. This tunnel
extension gives cleaned parts more time to dry completely. The drying tunnel
should work particularly well in combination with carbon adsorption. Drying
tunnels can be retrofitted, if there is adequate space. Rotating baskets ^
may be used on cross-rod degreasers and ferris wheel degreasers. A rotating
basket is a perforated cylinder containing parts to be cleaned that is slowly
rotated through the cleaning system, so that the parts cannot trap liquid
solvent. Rotating baskets are designed into the conveyorized system and hence
are not easily retrofitted.
Conveyors themselves can contribute to carry-out emissions. Some
designs cause less emissions than others. In general, these emissions are
directly proportional to the surface area entering and leaving the cleaning
3-17
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zone. One design, uses small pushers to move parts along fixed rods which
support the work. This design is advertised to carry-out 70 percent less
solvent than conventional wire mesh conveyors.
The effectiveness of control devices that help minimize carry-out
emissions cannot be quantified. The amount of carry-out depends too much
on the type of work loads (shape and crevices) and the quality of operation.
Nevertheless, it is obvious that if the exiting cleaning parts visibly show
liquid solvent, then carry-out emissions will be substantial.
3.1.3 Controls for Solvent Bath and Carry-out Emjssjpns Combi ned
Two control systems reduce both solvent bath and carry-out emissions.
They are the automated cover-conveyor system and a refrigeration condensation
system. Both systems are relatively new designs and infrequently used in
practice. They are somewhat complex and expensive in relation to most other
control devices.
3.1.3.1 Automated Cover-Conveyor System -
The purpose of an automated cover-conveyor system is to close the
cover of an open top vapor degreaser when parts are being cleaned and
dried. Thus, the cover is open only for the short period of time when dry
parts are actually entering or exiting. (It is possible to use this system
on a cold cleaner but the solvent volatility and losses would generally
have to be very high to justify the expense of such a system.) The automated
cover must be capable of closing while the part is inside the degreaser. If
the part is conveyed by means of a cable and hoist, then the cover can
close horizontally and be split into two parts so that it closes at the center
where the cable is located. If the parts are conveyed by means of a shelf
that automatically lowers and rises, then the vapor degreaser can be
covered by a permanent enclosure with a vertical door, (See Figure 3-5).
3-18
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&.-
-------
Automated conveyor systems include adjustable timing delays for cleaning
and drying and automatic cut-offs to position the work load for cooking and
drying.
Because emissions could occur only for the short period of time when
dry parts are entering or exiting the automated degreaser, it is expected
that an automated cover-conveyor system would provide highly effective
control.
3.1.3.2 Refrigeration Condensation -
Direct condensation of solvent vapors from exhaust air streams is a
possible although perhaps difficult means of recovering solvent. Some
20
insight into the problem is gained by examining Figure 3-6.
Condensation will occur when an air/vapor stream is refrigerated to
a temperature where the solvent's equilibrium vapor pressure is less than
its actual vapor pressure. The actual vapor pressure is calculated by
multiplying the percent solvent vapor concentration (by volume) by the total
pressure (usually atmospheric). For example, 1000 ppm of perchloroethylene
at atmospheric pressure yields an actual vapor pressure of 0.76 mm Hg
(0.1 percent concentration multiplied by 760 mm Hg). Extrapolating from
the graph, 0.76 mm Hg intersects curve #9 at -25°C; thus, condensation
occurs below -25°C for perchloroethylene at 1000 ppm and 1 atmosphere.
Although solvent concentrations may reach 1000 ppm momentarily, the
average concentration of chlorinated solvent vapors from typical operations
21
is about 300 ppm (0.23 millimeters Hg). Consequently, direct condensation
of perchloroethylene would not usually occur until the temperature of the
air/vapor stream was reduced to at least -40°C.
There are two major problems with refrigeration condensation. First,
at these low temperatures, ice forms rapidly on the heat exchange surfaces,
reducing the heat exchange efficiency. The ice formation also requires the removal
3-20
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Figure 3-6. Vapor Pressures ot Several Solvents
1
1
4
5
Methytane chloride
1 1 l-TrichloroMhane
Carbon tttrachloride
fi
7
8
9
10
Ethytene dichloride (1,2-dichloroethana)
Trichloroethytene
1 , 1 ,2-Trichloroethane
Perchloroethylene
Stoddard Solvent
Til
\?
ii
I4
15
JO- 40- 50" 60- 70- 60- 90' IOO' |20- I4Q- I6Q- ISO' 200' "°' "°'C
10.000
5000
1000
-20 -10 *0 10 20 30 40 50 o 60 70 80 90100 12O 140 160 180 20O 220 24O
3-21
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of a large amount of heat (1300 Btu's per pound) which will add significantly
to the cost of this control, Second, when condensation occurs a fine mist of
liquid solvent is formed. The problem is in removing this mist from the air
stream.
This analysis indicates that it would be difficult to control emissions
from degreasers with refrigeration condensation, However, this rests on two
assumptions: (1) 1 atmosphere pressure is maintained and (2) vapors cannot
be collected in higher concentrations, Still, this does not preclude its
successful use, An example is one design which was reported after the initial
EPA test program had been completed, The equipment manufacturer, Autosonics
Inc., reported successful emission control using a prototype of their design,
called the "Zero-Emission" vapor degreaser. This system employs refrigeration
condensation along with carbon adsorption and is reported to be able to
capture solvent vapors with unusually high efficiency. EPA tests on this
degreaser are planned,
3.1,4 Control of Waste Solvent Evaporation
3,1,4,1 Current Practices -
Emissions from waste solvent occur through a number of diverse routes,
none of which can be easily monitored or quantified. Based on the limited
information currently available (see Appendix B,5), it is estimated that
about 280 thousand metric tons of waste solvent were disposed of from metal
degreasing operations in 1974, This is approximately one-third of the total
metal degreasing emissions.
Most of this waste is disposed of in a manner such that it can evaporate
into the atmosphere, A large fraction is indiscriminately dumped into
drains or onto the grounds surrounding the using facility. Some waste
solvent is stored in open containers and evaporates. A small amount of waste
solvent finds its way to municipal or chemical landfills that make no
3-22
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attempt to encapsulate the solvent. Some larger companies have used
deep well injection, but overall this is considered an insignificant disposal
route for waste solvent from degreasing. It has been estimated that these
four disposal routes account for ^35 percent of the total waste solvent
load.
It is convenient for automotive maintenance facilities to dispose of
their waste solvent along with their waste crankcase oil. Perhaps as much
as 15 percent of the total waste solvent load (or <33 percent of the
waste solvent from maintenance cold cleaners) enters this route. Crankcase
oil is reprocessed, rerefined, used for dust control on unpaved roads or handled
in other ways, none of which pay significant attention to the solvent
fraction.
Properly controlled incineration is one of the few disposal routes
which does not result in organic emissions to the atmosphere. However,
only a small fraction (^5 percent) of waste solvent is believed to be disposed
of in this manner.
Solvent reclamation is the most environmentally acceptable route for
waste solvent. It is believed that ^45 percent of the waste solvent load
22 23
is being reclaimed through distillation. ' Primarily, halogenated
solvents are distilled; petroleum related solvents, such as mineral spirits,
are more difficult and less profitable to distill, because such solvents
are flammable and inexpensive, compared to halogenated solvents.
3.1.4.2 Recommended Practices -
Reclamation Services - Reclamation services collect waste solvent, distill
it, and return the reclaimed portion to the solvent user. Charges vary but
are roughly equal to one half the market value of the solvent. In industrial
areas where large numbers of users are present, solvent scavenging and
reclamation is being practiced profitably. In rural areas, where users are
3-23
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separated by large distances, collection and transportation is a limiting
factor. However, suitable collection systems could be devised and reclamation
service could be expanded beyond the industrial areas. For example, it would
be possible for the rural user to store waste solvent in sealed containers
until sufficient volume is acquired to make collection economical.
Another alternative is offered by the Safety Kleen Corporation. This
firm provides a service of supplying both the solvent and cold cleaning
equipment to users. The solvent used is periodically collected and replaced
with fresh solvent by the company and the used solvent is distilled at central
locations. The firm operates in industrial areas throughout the U.S.
In-House Reelamation - Many large users practice in-house reclamation.
In vapor degreasing, the use of stills is fairly common. For instance,
nearly all conveyorized vapor degreasers and large open top degreasers are
equipped with stills, (see Figure 3-7). These stills have been customarily
used because they reduce the maintenance cost of cleaning the vapor degreasing
system, enable the system to remove soils collected without interrupting
the cleaning process and recover valuable quantities of solvent. The Dow
Report estimated that the total yearly cost of in-house reclamation of
chlorinated solvents can be recovered from the first 350 gallons distilled.
Nonchlorinated solvents, because of their flammability and lower recovery
value, would require 6 to 12 times this quantity.
Bottoms from all distillation columns are of a hazardous nature,
containing metals, sludge, residual solvent, etc. They must be disposed
of properly in chemical landfills or preferably through a properly controlled
high temperature incineration facility.
Each solvent class exhibits its own peculiar problems in distillation.
Chlorinated solvents are partially stripped of their stabilizers during
3-24
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Figure 3-7
EXTERNAL STILL
Water
Separator
Condensate
Collection
Trough
Steam Inlets
Freeboard
Water Jacket
Water Inlet
Automatic
Level Control
>Steam Outlets
3-25
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distillation. These must be replaced to avoid chemical decomposition of
the recovered solvent. Nonchlorinated solvents are quite flammable and
require equipment designed to prevent fires and explosions. Solvent blends
usually consist of solvents of different boiling points; thus, the solvent
initially recovered has a higher portion of lower boiling point solvents.
Certain contaminates can also greatly increase the difficulty of distilling
any solvent. For example, azeotropes can form between contaminates and solvents
during distillation, making separation difficult. Also, adverse chemical
reactions can occur. For these reasons distillation service companies
generally analyze waste solvent. The company using in-house distillation
can often eliminate analysis and avoid many of the problems encountered by
services which distill a mixture of solvents from different users, because the
solvents and the contaminants are known.
Direct Incineration - Direct incineration in a properly controlled
facility is another environmentally acceptable disposal route for waste
solvent. Incineration does not, however, produce a useable product and
often requires significant amounts of supplementary fuel. For these
reasons, it is not as attractive as reclamation. Nonchlorinated solvents are
fuel oil grade waste and after simple filtration of hazardous contaminates
could provide the heat value necessary for incineration of chlorinated
compounds. However, their fuel value will be considerably less than their
solvent value.
There are approximately 25 to 50 facilities in the United States capable
of acceptably incinerating chlorinated solvents. Such facilities require high
temperatures H200°C), sufficient residence time (about 2 seconds), and
sophisticated exhaust gas cleaning equipment to remove halogenated compounds
(primarily HC1), particulates, and other contaminants. Capital investment to
3-26
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build this type of incinerator is significant (1.5 to 5 million dollars for
6 gallon of waste per minute capacity). Operating costs have been estimated
24
at less than 2
-------
3.1.5.1 Incineration -
Incineration has been used for many years to control emissions of organics
to the atmosphere. For degreasing operations, it could be applied most
easily to systems using petroleum hydrocarbons and oxygenated solvents which
readily combust to carbon dioxide and water. Application to systems using
halogenated hydrocarbons would be more difficult. Although halogenated
hydrocarbons are non-flammable under normal conditions, they can be pyrolyzed
at temperatures in the incineration range. The pyrolytic decomposition of
chlorinated hydrocarbons, for example, will release chlorine, hydrochloric
acid, and phosgene depending upon the conditions of oxidation. These products
would have to be removed from the off-gas stream of the incinerator using
sophisticated gas cleaning equipment before exhausting to the atmosphere.
The cost of incineration could also be high. First, capital requirements
are generally large, particularly in comparison to the relatively low cost of
most degreasers. Furthermore, costs would be significantly increased with
the addition of gas cleaning equipment, were that needed. Next, solvent
concentrations in exhaust streams are frequently below the range required
to sustain combustion; thus, supplemental fuel would be required. Scarce fuel
resources would make this a limiting factor.
3.1.5.2 Liquid Absorption -
Liquid absorption is a well known process that has been investigated for
use in solvent metal cleaning. For example, trichloroethylene vapors in air
could be substantially reduced by absorption in mineral oil. However, at an
absorption column temperature of 30°C (86°F), the air stream leaving the
column might contain about 120 ppm mineral oil. Thus, the process could
result in control of one hydrocarbon but emission of another at a nearly
I O
equal or possibly greater rate.
3-28
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Chilling the absorbing fluid would reduce its concentration in the
exhaust air. However, cooling to a temperature below 0°C (32°F) would cause
ice formation in the column since water is insoluble in mineral oil. Although
this could be avoided by prerefHgeration of the air stream, the use of
refrigeration would greatly increase energy consumption. Finally, the energy
requirement for recovering the solvent from the mineral oil is great. Thus,
it appears that this method of emission control is impractical except for the
recovery of (1) high concentrations of solvent vapors in air, (2) very valuable
19
vapors or (3) highly toxic chemical vapors.
3.2 COMPLETE CONTROL SYSTEMS
A complete emission control system utilizes both control equipment and
operating procedures. Although controls can be combined in many ways to form
many different control systems, two basic control systems for each type
degreaser are presented here. Generally, control system A consists of proper
operating practices and simple, inexpensive control equipment. Control
system B consists of system A plus other devices that increase the effectiveness
of control. The details of control system A or B can be modified to arrive
at the level of control needed.
The emission control efficiency of reasonably well designed and maintained
control systems is estimated from the present test data base. Control systems
which are seriously defective are not uncommon. A few such systems were
even recommended unintentionally by control system vendors to EPA as being
exemplary; it required close inspection and sometimes emission measurements
to discover that the systems were defective.
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3.2.1 Cold Cleaning Control Systems
The most important emission control for cold cleaners is the control
of waste solvent. The waste solvent needs to be reclaimed or disposed of so
that a minimum evaporates into the atmosphere. Next in importance are the
operating practices of closing the cover and draining cleaned parts. Several
other control techniques become significant only in a small fraction of
applications. The control devices and operating practices for control
systems A and B are summarized in Table 3-1.
There is not a large difference in effect between system A and B,
because most of the cold cleaning emissions are controlled in system A. If
the requirements of system A were followed conscientiously by nearly all
of the cold cleaning operators, there would be little need for the additional
system B requirements. However, because cold cleaning operators can tend
to be lax in keeping the cover closed, equipment requirements #1 and #4 in ^
system B are added. Similarly, the modifications for #2 and the equipment
requirements in #3 would effect significant emission reductions in a few
applications.
Although the effectiveness of the control systems depends greatly on
the quality of operation, average cases have been approximated, (see Appendix B.2).
System A could reduce cold cleaning emissions by 50 (±20) percent
and system B may reduce it by 53 (+20) percent. The lower end of the range
represents the emission reduction projected for poor compliance, and the higher
end represents excellent compliance. As can be readily seen from these estimates,
the expected benefit from system B is only slightly better than that for
system A for an average cold cleaner, assuming low volatility
solvents. This difference is small because the additional devices required
in system B generally control only bath evaporation, which represents about M
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TABLE 3-1. CONTROL SYSTEMS FOR COLD CLEANING
Control System A
Control Equipment:
1. Cover
2. Facility for draining cleaned parts
3. Permanent, conspicuous label, summarizing the operating requirements
Operating Requirements:
1. Do not dispose of waste solvent or transfer it to another party,
sucK that greater than 20 percent of the waste (by weight) can evaporate
into the atmosphere.* Store waste solvent onlv in covered containers.
2. Close degreaser cover whenever not handling parts in the cleaner.
3. Drain cleaned parts for at least 15 seconds or until dripping ceases.
Control System B
Control Equipment:
1. Cover: Same as in System A, except if (a) solvent volatility is
greater than 2 kPa (15 mm Hg or 0.3 psi) measured at 38°C (100°F),**
(b) solvent is agitated, or (c) solvent is heated, then the cover must
be designed so that it can be easily operated with one hand. (Covers for
larger deqreasers may require mechanical assistance, by spring loading,
counterweiqhtinq or Dowered systems.)
2. Drainage facility: Same as in System A, except that if solvent
volatility is greater than about 4.3 kPa (32 mm Hg or 0.6 psi) measured at
38°C (100°F), then the drainage facility must be internal, so that parts are
enclosed under the cover while draining. The drainage facility may be
external for applications where an internal type cannot fit into the cleaning
system.
3. Label: Same as in System A
4. If used, the solvent spray must be a solid, fluid stream (not a
fine, atomized or shower type spray) and at a pressure which does not cause
excessive splashing.
5. Major control device for highly volatile solvents: If the solvent
volatility is > 4.3 kPa (33 mm Hg or 0.6 psi) measured at 38°C (100°F), or
if solvent is heated above 50°C (120°F), then one of the following control
devices must be used:
a. Freeboard that gives a freeboard ratio*** >_0.7
b. Water cover (solvent must be insoluble in and heavier than water)
c. Other systems of equivalent control, such as a refrigerated chiller
or carbon adsorption.
Operating Requirement.*;:
Same as in System A
*Water and solid waste regulations must also be complied with..
**Generally solvents consisting primarily of mineral spirits (Stoddard) have
volatilities < 2 kPa.
***Freeboard ratio is defined as the freeboard height divided by the
width of the degreaser.
3-31
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20 to 30 percent of the total emission from an average cold cleaner. For
cold cleaners with high volatility solvents, bath evaporation may
contribute ^50 percent of the total emission; ft is estimated that system B
may achieve 69 (+20) percent control efficiency, whereas system A might
experience only 55 (+20) percent control.
3.2.2 Control Systems for Open Top Vapor Degreasing
The basic elements of a control system for open top vapor degreasers
are proper operating practices and use of control equipment. There are
about ten main operating practices. The control equipment includes a cover,
safety switches and a major control device, either high freeboard, refrigerated
chiller, enclosed design or carbon adsorption. Two control systems for open
top vapor degreasers are outlined in Table 3-2.
The vapor level thermostat is not included because it is already required
by OSHA on "open surface vapor degreasing tanks." The sump thermostat and
solvent level control are used primarily to prevent solvent degradation and
protect the equipment and thus are also not included here. The emission
reduction by these controls is a secondary effect in any event. The two
safety switches presented serve primarily to reduce vapor solvent emissions.
System A may reduce open top vapor degreasing emissions by 45 (+15) percent,
and system B may reduce them by 60 (+J5) percent. For an average size
open top vapor degreaser, system A and B would reduce emissions from 9.5 m
tons/year down to about 5.0 and 3.8 m tons/year, respectively. It is clear that
system B is appreciably more effective than system A.
3.2.3 Control Systems for Conveyorized Degreasers
Control devices tend to work most effectively on conveyorized degreasers»
mainly because they are enclosed. Since these control devices can usually
result in solvent savings, they often will net an annualized profit.
3-32
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TABLE 3-2. COMPLETE CONTROL SYSTEMS FOR OPEN TOP VAPOR DE6REASERS
Control System A
Control Equipment:
1. Cover that can be opened and closed easily without disturbing the
vapor zone.
Operating Requirements:
1. Keep cover closed at all times except when processing work loads
through the degreaser.
2. Minimize solvent carry-out by the following measures:
t: K S8 X STJ"!} ffi'SR— « 0c ,
c Degrease the work load in the vapor zone at least 30 sec. or until
visually ^ry.^ ^^^ porQus Qr absorbent materials, such as cloth, leather,
wood or rope.
4. Work loads should not occupy more than half of the degreaser 's open
top area.
5. The vapor level should not drop more than 10 cm (4 in) when the
work load enters the vapor zone.
6. Never spray above the vapor level.
7. Repair solvent leaks immediately, or shutdown the degreaser.
8. Do not dispose of waste solvent or transfer It to another party
1
,
fans should not be used near the degreaser opening.
10. Water should not be visually detectable in solvent exiting the water
separator.
Control System JL
Control Equipment:
1. Cover (same as in system A).
2. Safety switches
a Condenser flow switch ana tnermostat - Csnuts off sump neat if condenser
C°°lan ^ (IhuTs'oVspTay pump if the vapor level drops
b
excessively, about 10 cm (4 in).
3. Major Control Device:
Either- a Freeboard ratio greater than or equal to 0.75, and if the
degreaser opening is > 1 m2 (10 ft*), the cover must be powered,
b Refrigerated chiller,
c' Enclosed design (cover or door opens only when the dry part
is actually entering orbiting the denser.), .3 .2
(50 cfm/ft2) of air/vapor area (when cover is open), and exhausting <25 ppm
solvent averaged over one c^^^tSd^S^control efficiency,
equivalent to or better than any of the above.
4. Permanent, conspicuous label, summarizing operating procedures #1 to #6.
Operating Requirements:
Same as in System A
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Two recommended control systems for conveyorized degreasers are shown in
Table 3-3. Control system A requires only proper operating procedures which
can be implemented, in most cases, without large capital expenditures. Control
system B, on the other hand, requires a major control device.
Major control devices can provide effective and economical control for
conveyorized degreasers. A refrigerated chiller will tend to have a high
control efficiency, because room drafts generally do not disturb the cold air
blanket. A carbon adsorber also tends to yield a high control efficiency,
because collection systems are more effective and inlet streams contain
higher solvent concentrations for conveyorized degreasers than for open top
vapor degreasers.
Small scale conveyorized degreasing applications can result in significantly
high annualized costs from using a major control device. Consequently, many
operators raay be motivated to use the less expensive open top vapor degreaser
in place of a conveyorized one, even though more solvent is emitted for an *
equivalent work. load. Thus, it is reasonable to exempt eonveyorized degreasers with
less than 2.0 m of air/vapor interface from requirement of a major control device.
The remaining three control devices recommended in system B should entail
nominal expense in relation to their potential solvent savings. Because of
the wide diversity of applications for conveyorized degreasing, there may be
a few applications where the drying tunnel or a minimized opening may be
impractical; thus, occasional exceptions may have to be made for these two
requirements. For example, a plant might not have enough space available to
permit use of a drying tunnel; also, hanging parts may occasionally swing
from a conveyor line more than the clearance allowed by the control requirement.
The control efficiency for system A is estimated at 25 C±5) percent and
for system B, 60 (±10) percent. Emissions from a typical conveyorized degreaser
' 3-34
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TABLE 3-3. CONTROL SYSTEMS FOR CONVEYORIZED DEGREASERS
Control System A
Control Equipment: None
Operating Requirements:
i Exhaust ventilation should not exceed 20 m3/min per m2 (65 cfm per ft )
of degreaSrTpening! unless necessary to meet OSHA requirements. Work place
fans should not be used near the degreaser opemng.
2. Minimize carry-out emissions by:
conTeyorlpeed at < 3.3 m/min (11 ft/min).
3 Do not dispose of waste solvent or transfer it to another party such
that greater than 20 percent of the waste (by weight) can evaporate
into the atmosphere. Store waste solvent only in covered containers.
4. Repair solvent leaks immediately, or shutdown the degreaser.
5. Water should not be visibly detectable in the solvent exiting the
water separator.
Control System B
Control Equipment:
1. Major control devices; the degreaser must be controlled by either:
b asorptSon1 Astern, with ventilation >15 m^/min per m2 (50 cfm/ft2)
of air/vapor area (when down-time covers are open), and exhausting <25 ppm of
solvent by volume averaged over a complete adsorption cycle, or
c. System demonstrated to have control efficiency -qumlent to or better
than either of the above.
2 Either a drying tunnel, or another means such as rotating (tumbling)
basket] sufficient to prevent cleaned parts from carrying out solvent nquid
or vapor.
3. Safety switches
a. Condenser flow switch and thermostat - (shuts off sump heat if
coolant is either not circulating or too warm).
b. Spray safety switch - (shuts off spray pump or conveyor if the vapor
! drons excessively, e.g. > 10 cm (4 in.)).
c Sapor ?evel control thermostat - (shuts off sump heat when vapor
level rises too high).
4 Minimized openings: Entrances and exits should silhouette work
loads so that the average clearance (between parts and the edge of the
degreaser opening) is either <10 cm (4 in.) or <10 percent of the width
of the opening.
5. Down-time covers: Covers should be provided for closing off the
entrance and exit during shutdown hours.
Operating Requirements:
1. to 5. Same as for System A
6 Down-time cover must be placed over entrances and exits of conveyorized
degreasers immediately after the conveyor and exhaust are shutdown
and removed just before they are started up.
3-35
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may decrease from 27 to 'vZO and Ml (metric 1 tons/yr for systems A and B,
respectively. Thus, system B offers a much greater emission reduction per
degreaser for conveyorfzed degreasers than for cold cleaners or open top vapor
degreasers.
3-36
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3.3 REFERENCES
1. American Society for Testing and Materials (ASTM), Committee D-26,
"Recommended Practice for New Source Performance Standards to Control
Solvent Metal Cleaning Emissions."
2. Surprenant, K. S. and Richards, D. W. of Dow Chemical Company, "Study
to Support New Source Performance Standards for Solvent Metal Cleaning
Operations," Vol. 2, prepared for Emission Standards and Engineering
Division (ESED), under Contract # 68-02-1329, Task Order #9, June 30, 1976.
3. Ibid.
4. Ibid, Appendix C-9.
5. American Society for Testing Materials, Op. Cit.
6. Surprenant, K. S., Op. Cit, Appendix C-12.
7. Information provided by H. A. Rowan of Magnus Division of Economics Lab.
Inc., S. Plainfield, N. J., by telephone to J. C. Bellinger, EPA
March 28, 1977.
8. Information provided by J. Picorney of Baron Blakeslee Inc., Chicago,
by telephone to J. C. Bellinger, EPA, November 18, 1976.
9. "Trip Report - Collins tnow Rucker Ultrasonics) Inc., Concord, Calif."
EPA memorandum from J. C. Bollinger to D. R. Patrick, November 5, 1976.
10. Surprenant, K. S., Op. Cit., Appendices C-3, C-5, and C-7.
11. Ibid, pg. 4-5.
12. JACA Corp., Fort Washington, Pa., "Air Pollution Control of Hydrocarbon
Emissions - Solvent Metal Cleaning Operations," prepared for EPA, Office
of Technology Transfer, Seminar: "Upgrading Metal Machining, Fabricating,
and Coating Operations to Reduce Pollution."
13. Surprenant, *C. S., Op. Cit., pg. 4-59.
14. Ibid, Appendices C-10 and C-ll.
3-37
-------
15. Ibid, Appendices C-4, C-5, and C-8.
16. Ibid, Appendix C-7.
17. Kearney, T. J., Detrex Chem. Inc., letter to J. F. Durham, EPA,
February 17, 1976.
18. Surprenant, 1C. S., Op. Cit.
19. Ibid.
20. Ibid, pg. 4-16.
21. Ibid, pg. 4-18.
22. Information provided by F. X.. Barr, Graymtlls Co., Chicago, by telephone
to J. L. Shuroakfir, EPA, January 13, 1977.
23. Information provided by K. S. Surprenant, Dow Chemical, Midland, Michigan
by telephone to J. L. Shumaker, EPA, January 11, 1977.
24. Information provided by Hydroscience, Inc., Knoxville, Tennessee by
telephone to J. L. Shumaker, EPA, March 24, 1977.
3-38
-------
4.0 COST ANALYSIS
4.1 INTRODUCTION
4.1.1 Purpose
The purpose of this chapter is to present estimated costs for applying
alternative emission control techniques in the metal cleaning, or deceasing
industry. Cost data will be provided for hydrocarbon controls on cold
cleaners, open top vapor degreasers, and conveyorized vapor degreasers.
These cost data will be presented for model new facilities as well as for
model existing plants.
4.1.2 Scope
With regard to cold cleaners, control cost estimates will reflect the
use of the following techniques:
1. drainage facility;
2. mechanically assisted cover (spring loaded).
The scope of this section includes both low volatility solvents, such as
mineral spirits, and high volatility solvents such as 1,1,1- trichloroethane.
Costs will be presented for only one size cold cleaner facility.
No incremental costs for housekeeping controls are presented in this
chapter. A reasonable judgment is that such costs are negligible, particularly
considering that they are offset by savings in recovering additional solvent
from improved housekeeping.
With regard to open top vapor degreasers, control cost estimates will be
presented for two sizes of facilities that primarily use trichloroethylene
solvent or 1,1,1-trichloroethane solvents. The control cost estimates will
reflect the following techniques:
4-1
-------
1. use of a manual cover;
2. use of a manual or powered cover in combination with extended freeboard;
3. refrigerated chiller;
4. carbon adsorber;
As in the case of cold cleaners, incremental costs for housekeeping
controls on open top vapor degreasers are not presented because they appear
to be negligible.
With regard to conveyorized vapor degreasers, control cost estimates
will be presented for facilities that primarily use trichloroethylene or
perchloroethylene solvents. The control cost estimates will reflect the use
of the following techniques:
a. carbon adsorber
b. refrigerated chillers
Again, incremental costs for housekeeping are not presented because they
appear to be negligible.
4.1.3 Model Plants
Control cost estimates are presented for typical model degreasers in the
metal cleaning industry. Specific model plant parameters will be presented
in the subsequent portions of this chapter. Admittedly, control costs may
vary from one installation to another, perhaps even appreciably from the
costs described for the models in this chapter. However, the difficulty of
obtaining actual plant control costs requires use of model plants. To the
extent possible, EPA has incorporated actual plant cost information into the
cost analysis.
4-2
-------
Cost information is presented both for typical new model degreasers as
well as for typical existing model facilities. Model degreasers depicting
size, design, and solvent usage have been developed. The purpose of this
is to show the relative variation in control equipment costs with these
factors. Although the degreaser models chosen for the analysis are believed
to be representative of degreasers used throughout the industry, no attempt
has been made to span the range of existing degreaser designs and sizes.
4.1.4 Capital Cost Estimates
Control cost estimates comprise installed capital costs and annualized
operating costs. The installed capital cost estimates reflect the cost of
designing, purchasing, and installing a particular control device. These
estimates include costs for both major and auxiliary equipment, rearrangement
or removal of any existing equipment, site preparation, equipment installation
and design engineering. No attempt has been made to include costs for lost
production during equipment installation or start-up. For degreasing operations,
most of the controls discussed will take a matter of hours for installation
which should minimize delays in production. All capital costs reflect first
quarter 1977 costs. In general, information for capital costs has been
developed through contacts with degreaser equipment manufacturers. In addition,
an EPA contractor study1 and EPA in-house files have been used to develop the
capital costs.
4.1.5 Annualized Costs
Annualized cost estimates include costs for operating labor, maintenance
.and utilities, credits for solvent recovery, depreciation, interest, adminis-
trative overhead, property taxes, and insurance. Operating cost estimates
4-3
-------
have been developed on the basis of the EPA contractor study cited above.
The number of annual operating hours was assumed to be 2250 hours. The cost
2
of electricity is assessed at 4 cents per kilowatt-hour. Solvent prices
used were $0.20 per kilogram for mineral spirits, and $0.43 for trichloro-
ethylene and $0.41 for the chlorinated blended solvent used in cold cleaning.
These solvent prices are based on recent quotations from the Chemical
Marketing Reporter.3 Maintenance costs for all controls (except housekeeping)
were estimated to be 4 percent of the purchase cost of the equipment. Estimates
of depreciation and interest costs have been developed by EPA based on the use
of the capital recovery factor, an interest rate of 10 percent, and an equip-
ment life of 10 years. In addition to costs for depreciation and interest,
other capital charges include a 4 percent charge for administrative overhead,
property taxes, and insurance.
4.2 COLD CLEANERS
4.2.1 Model Plant Parameters
The model parameters that were used in developing control costs for cold
cleaners are shown in Table 4-1. These parameters are based on industry
contacts and EPA studies of the solvent degreasing industry. The most common
type of cleaning is represented by low volatile solvent cleaning. Also shown
is high volatile solvent cleaning, which is important from the standpoint of
higher emission rates. The emission rates in Table 4-1 represent typical
values. The recovered solvent values and the cost of solvent are used to
estimate solvent credits which will reduce the annualized control costs. The
assumed composition for the high volatility solvent blend is 60 percent
1,1,1-trichloroethane, 20 percent xylene, and 20 percent mineral spirits.
4-4
-------
Table 4-1. COST PARAMETERS FOR MODEL COLD CLEANERS
,
Working Area, m
Solvent Used
Uncontrolled Emission Rate,
metric tons per year
Emission Rate with House-
keeping Requirements,
metric tons per year
f Solvent Recovered by Control
011 System, metric tons per year
Solvent cost, $ per kg
Low Volatility
Solvents
0.5
Mineral Spirits
0.25
0.16
U.024
0.20
High Volatility
Solvents
0.5
Blended Solvent
0.40
0.32
0.096
0.41
Source: EPA assumptions based on industry contacts, contractor studies and in-house files
-------
4.2.2 Control Costs
Costs for control of emissions from cold cleaners have been developed
for the following cases for model new and existing cold cleaners:
1. drainage facility for low volatility solvent cleaning
2. drainage facility plus a mechanically assisted cover for high
volatility solvent cleaning.
The drainage facility consists of an external rack equipped with a drain
line to return recovered solvent to the storage tank, which supplies the
solvent for cleaning. The mechanically assisted cover consists of a spring
loaded plunger which helps the operator to easily open and close the cover.
The costs for these equipment features are presented in Table 4-2.
Estimates are presented for installed capital costs, annualized costs, and
the cost per kilogram of hydrocarbon controlled. The capital costs for the
drainage facility are the same for an existing cleaner as for a new one
because of the ease with which it can be retrofitted. The capital costs
for the cover are for the spring loaded plunger which can be retrofitted
onto the cover of an existing cleaner. These costs were provided to EPA by
a manufacturer of cold cleaning equipment.4'5 One hour of labor is assumed
as the requirement for installing the spring loaded plunger.
The cost of hydrocarbon control per kilogram of recovered solvent is
quite sensitive to the value of the recovered solvent. Note that the low
volatility solvent cleaner in Table 4-2 incurs a cost of $0.021 per kilogram
whereas the high volatility solvent cleaner saves $0.31 per kilogram for the
new facility and $0.267 per kilogram for the existing facility.
4-6
-------
Table 4-2. CONTROL COSTS FOR TYPICAL COLD CLEANERS
(Vapor to Air Area of 0.5m2)
I. Model New Facilities
Installed Capital ($)
Direct operating costs ($/yr)
Capital charges ($/yr)
Solvent cost (credit) ($/yr)
Annualized cost (credit) ($/yr)
Controlled emissions (metric tons/year)
Cost (credit), $ per Kg controlled
II. Model Existing Facilities
Installed capital ($)
Direct operating costs ($/yr)
Capital charges ($/yr)
Solvent cost (credit) ($/yr)
Annualized cost (credit) ($/yr)
Controlled emissions (metric tons/year)
Cost (credit), $ per Kg controlled
Low Volatility Solvent
25
1.00
4.30
(4.80)
0.50
0.024
0.021
25
1.00
4.30
(4.80)
0.50
0.024
0.021
High Volatility Solvent
45
1.80
7.72
(39.36)
(29.84)
0,096
(0.31)
65
2.60
11.15
(39.36)
(25.61)
0.096
(0.267)
Source:Reference 4, 5 for estimates of capital and annualized costs
-------
4.3 OPEN TOP VAPOR DE6REASERS
4.3.1 Model Plant Parameters
The model parameters that were used in developing control costs for
two sizes of open top vapor degreasers are displayed in Table 4-3. The
two sizes represented are characterized by working area and solvent emissions.
These parameters were selected as a result of industry contacts and EPA studies
of the industry. The emission rates in Table 4-3 represent typical values.
The working area is used to determine costs for covers, refrigerated chillers,
and freeboard extensions. The assumption used to estimate costs is that the
length of the working area is twice the width. The recovered solvent values
and the cost of solvent are used to estimate solvent credits which are deducted
from the annualized costs of the control devices.
4.3.2 Control Costs
Costs for control of emissions from open top vapor degreasers have been
developed for the following cases for model new and existing degreasers:
1. manual cover;
2
2. manual or powered cover for working area exceeding 1.0 m in
combination with extended freeboard;
3. refrigerated chiller;
4. carbon adsorber.
Table 4-4 presents the costs for these controls on the average sized
degreaser, and Table 4-5 presents costs for the smaller degreaser. Costs
are presented in terms of installed capital costs, annualized costs, and the
cost per kilogram of hydrocarbon controlled.
4-8
-------
Table 4-3. COST PARAMETERS FOR MODEL OPEN TOP VAPOR DEGREASERS
Working Area, m
Uncontrolled Emission Rate,
metric tons per year
Emission rate with housekeeping
requirements, metric tons per year
Solvent recovered by control system,
metric tons per year
a) Manual cover
b) High freeboard and
powered cover
c) Chiller
d) Carbon adsorber
Solvent Cost, $ per kg
Typical Degreaser
1,67
9.5
6.7
2.0
2.7
3.0
3.3
0.43
aser
Small
(
0.83
4.75
3.35
1.0
1.35
1.50
1.65
(D
0.43
Manual cover and high freeboard.
SOURCE: EPA assumptions based on industry contact, contractor studies, and in-house files,
-------
Table 4-4. CONTROL COSTS FOR TYPICAL SIZE OPEN TOP VAPOR DEGREASER
(Vapor to Air Area of 1.67
VA
irK)
Control Technique
I. Model New Facilities
Installed capital ($)
Direct operating cost ($/yr)
Capital charges ($/yr)
Solvent cost (credit) ($/yr)
Net annuali zed cost (credit) ($/yr)
Controlled emissions (metric tons/yr.)
Cost (credit) per Kg controlled
II. Model Existing Facilities
Instal led capital ($)
Direct operating cost ($/yr)
Capital charges ($/yr)
Solvent cost (credit) ($/yr)
Net annualized cost (credit)
($/yr)
Controlled emissions (metric tons/yr.)
Cost (credit), $ per Kg controlled
Manual
Cover
250^
10
43
(860)
(807)
2.0
(0.404)
aooW
10
51
(860)
(799)
2.0
(0.40)
Carbon
Adsorption
7400 ^
451
1268
(1419)
300
3.3
0.091
10,300^
451
1,765
(1419)
797
3.3
0.242
Refrigerated
Chiller
4900 ^3^
259
840
(1290)
(191)
3.0
(0.064)
6500^3^
259
1115
(1290)
84
3.0
0.028
Extended Freeboard
. « ruwcreu l/over
• — • — — — .
2500 (4)
100
430
(1161)
(631)
2.7
(0.234)
8000(*,2)
100
1372
(1161)
311
2.7
0.115
(2) Reference 1
3) Reference 1
4) References 7 and 8.
-------
Table 4-5. CONTROL COSTS FOR SMALL OPEN TOP VAPOR DEGREASER
(Vapor to Air Area of 0.8 m^)
Control Technique
T MnHpl New Facilities
Installed capital ($)
Direct operating costs ($/yr)
Capital charges ($/yr)
Solvent cost (credit) ($/yr
Net annualized cost (credit)
($/yr)
Controlled emissions (metric
tons/yr.)
Cost (credit), $ per Kg
controlled
II. Model Existing Facilities
Installed capital ($)
Direct operating costs ($/yr)
Capital charges ($/y>")
Solvent cost (credit) ($/yr)
Net annualized cost (credit)
• ($/yr)
Controlled emissions
(metric tons/yr.)
Cost (credit), $ per Kg
controlled
(1 ) Reference 7.
(2) Reference 1
(3) Reference 1
(4) References 7 and 8.
Manual
Cover
_- —
230^
9
40
(430)
(381)
1I"»
.0
(0.381)
270^
9
(430)
(375)
1 0
1 • V
(0.375)
Carbon
Adsorption
7400(2)
404
1268
(710)
962
1 65
1 « U>^
0.583
10,300(2)
404
1,765
(710)
1,459
1.65
0.884
Refrigerated
Chiller
2700 (3)
158
463
(645)
(24)
1.5
(0.016)
4030 ^
158
691
(645)
204
1.5
0.136
Extended Freeboard
and Manual Cover
430 (4)
17
74
(581)
(490)
1.35
(0.363)
570 (4)
17
98
(581)
(466)
1.35
(0.345)
-------
With regard to Tables 4-4 and 4-5, the installed capital for the carbon
adsorber in the existing facility represents the worst retrofit situation
to be encountered for this control device. This would occur if no steam
capacity is available for solvent desorption, and space is limited. Retrofit
capital would include a small steam boiler and an elevated platform to provide
space. For most retrofit situations, the installed capital would be somewhere
between the costs for a new facility and the estimates shown for the existing
facilities.
The retrofit factor for carbon adsorbers applied to existing degreasers
was developed from an actual facility.6 The cost of the carbon adsorber for
the facility was $13,990; the boiler, $4,000; and the platform above ground
level in the plant to house both the boiler and the adsorber, $3,300.
The ratio of the boiler and platform costs to the carbon adsorber costs is
approximately 0.50.
The retrofit factor for the refrigerated chillers is also approximately
50 percent, or in other words, retrofit costs are 50 percent more for existing
degreasers than for new units. The basis for this is the study cited earlier
(see reference 1).
Retrofit costs for freeboard extensions, or high freeboards, and covers
are difficult to determine in some situations. Based on contacts with two
manufacturers of these devices, approximate installation reouirements are
10 man-hours for manual covers,7 16 man-hours for freeboards, and 16 man-hours
8
for powered covers.
The installed capital in Table 4-4 for the powered cover with extended
freeboard in an existing facility includes $5,5009 for digging a concrete
pit. The purpose of the pit is to allow room for a hoist or a conveyor
4-12
-------
bringing parts to the cleaner. Such a problem most likely would not exist
for small degreasers. Consequently, a provision for this type of retrofit
penalty is provided in Table 4-4 but not in Table 4-5.
Another difference to be noted in capital costs for the powered cover-
extended freeboard design is that the powered cover is required only for
this degreaser with working area in excess of 1.0 m2. Otherwise, the
degreaser would be required to install only a manual cover. Note the
difference in capital between the manual cover-extended freeboard design
in Table 4-5 and the powered cover design in Table 4-4 for new facilities.
In both Tables 4-4 and 4-5, the costs of hydrocarbon control per kilogram
of recovered solvent are reported. These values will be used to develop the
cost-effectiveness curves later in this chapter. As these tables indicate,
the costs of hydrocarbon control vary considerably depending upon the size
of the degreaser, the type of control, and the amount of recovered solvent.
As an illustration, carbon adsorber costs range from $0.091 per kilogram
(Table 4-4) in a new facility for the typical degreaser to $0.583 per kilogram
(Table 4-5) for the small degreaser. This is an indication that carbon ad-
sorbers should be much less expensive for larger open top vapor degreasers.
Conversely, the extended freeboard and manual cover combination is less expen-
sive for the smaller degreasers than the similar combination with the powered
cover on larger degreasers. This conclusion is shown by the difference in
savings between $0.234 per kilogram for the typical degreaser in a new facility
(Table 4-4) and $0.363 per kilogram for the small degreaser (Table 4-5).
4-13
-------
4.3.3 Cost-Effectiveness
The purpose of this section is to provide a graphical analysis of the
cost-effectiveness of alternative control options for various types of open
top vapor degreasers. This analysis will attempt lo relate the annualized
cost per kilogram of hydrocarbon removal with degreaser size for each control
option.
Figure 4-1 is a presentation of the typical relationship for control of
hydrocarbon emissions from open top vapor degreasers. Curves are shown for
carbon adsorbers, refrigerated chillers, powered covers with extended free-
boards, and manual covers. The size range shown in Figure 4-1 represents the
approximate range of most degreasers (0.8 square meters to 18 square meters)
based on EPA data, contractor studies, and contacts with degreaser manufacturers.
The efficiencies of the control devices shown represent the capability of the
control device for reducing emissions from a well maintained degreaser (which
has carried out all good housekeeping practices). Although detailed costs
are presented for two model degreasers in Section 4.3, several more estimates
were derived in order to define the curves with reasonable precision.
The curves represent the retrofit costs for existing facilities. However,
this constraint was somewhat relaxed for the powered cover option which does
not include the cost of the concrete pit shown in Table 4-4. The reason for
this is that the powered cover option with a lower control efficiency may
be an acceptable option in those situations where the concrete pit is not
necessary. On the other hand, if the pit were required, then the refrigerated
chiller with a higher control efficiency (45 percent) becomes more attractive.
4-14
-------
Cost (credit) per kg Controlled ($)
ro
a>
-s
o
CD
a>
-------
For example, Table 4-4 shows for the degreaser with 1.67 square meters a
cost of $0.028 per kilogram for the chiller and $0.115 for the powered cover
with the concrete pit.
An important concept for control of degreaser emissions is the fact
that credits for recovered solvent offset to some extent the annualized
costs of installing, operating, and maintaining a control device. In re-
viewing Figure 4-1, the reader will observe the extent to which solvent
credits can more than offset the annualized costs of the control device.
This is graphically illustrated by the horizontal dashed line of $0. per
kilogram. This dashed line indicates that application of carbon adsorbers
will result in an out-of-the-pocket expense to the operator of the degreaser
for a size below an approximate 6 square meters in working area. Similarly,
refrigerated chillers will do the same for degreasers smaller than approximately
2 square meters.
4.4 CONVEYORIZED DEGREASERS
4.4.1 Model Plant Parameters
The model plant parameters that were used in developing control costs for
conveyorized degreasers are displayed in Table 4-6 for monorail and cross-rod
designs. These parameter selections are based on industry contacts and EPA
studies of the industry, in the same manner as cold cleaners and open top
vapor degreasers. The emission rates in Table 4-6 represent typical values.
The working area is used to determine costs for refrigerated chillers. The
assumption used to estimate chiller costs is that length of the working area,
or interface, is 2.7 times the width. The basis for this is an emission test
study performed on a monorail degreaser. The recovered solvent values and
the cost of solvent are used to estimate solvent credits which will reduce the
annualized control costs of the control devices.
4-16
-------
Table 4-6. COST PARAMETERS FOR MODEL CONVEYORIZED DEGREASERS
2
Working Area, m
Uncontrolled emission rate, 35
metric tons per year
26 10-5
Emission rate with housekeeping
requirements, metric tons
per year
13 1 ^'^'
Solvent recovered by control
system, metric tons per year
0 43 °'43
Solvent cost, $ per kg
___ —— —
Source: EPA assumptions based on industry contacts, contractor studies and in-house files.
-------
4.4.2 Control Costs
Costs for control of emissions Prom conveyorized degreasers have been
developed for the following control devices:
1. carbon adsorbers
2. refrigerated chillers.
Table 4-7 presents the costs for the model conveyorized degreasers.
Costs are presented in terms of installed capital costs, annualized costs,
and the cost per kilogram of hydrocarbon controlled. The installed capital
for the carbon adsorber in the existing facility represents the worst retrofit
situation to be encountered. This would occur if no steam capacity is available
for regeneration of adsorbed solvent and space is limited. Retrofit capital
includes a small steam boiler and an elevated platform for the carbon adsorber.
The retrofit factor applied to the new source costs for the carbon adsorber
is the same as the retrofit factor used for open top vapor degreasers.
Most existing facilities already have steam raising capacity to operate
a still to reclaim dirty solvent. These facilities could possibly schedule
their steam boiler to desorb the carbon bed during periods when the still is
not used. For most retrofit situations, the installed capital would lie
somewhere between the costs shown for new and existing facilities.
The figure of $8,550 shown for the existing facility on the monorail
degreaser compares reasonably well with a figure of $8,294 (1975 dollars) on
an actual facility. The latter would be $9,123 in 1977 dollars based on the
use of the Chemical Engineering Plant Index. The retrofit factor used to
estimate costs for chillers is the same as the one used for the chillers on
open top vapor degreasers.
4-18
-------
Table 4-7, CONTROL COSTS FOR TYPICAL CONVEYORIZED DEGREASERS
(Vapor to Air Vapor Area.of 3.8 m?)
Monorail Degreaser
Cross-Rod Degreaser
Carbon
Adsorber
Refrigerated
Chi 1 ler
Carbon
Adsorber
Control T6chm Qti6_ — . — — — •• • •-• - • — •••• - ~
I. Model New Facilities
II.
Installed capital ($)
Direct operating costs ($/yr)
Capital charges ($/yr)
Solvent cost (credit) ($/yr)
Annualized cost (credit) ($/yr)
Controlled emissions (metric
tons/yr.)
Cost (credit), $ per Kg controlled
Model Existing Facilities
Installed capital ($)
Direct operating costs ($/yr)
Capital charges ($/yr)
Solvent cost (credit) ($/yr)
Annual i zed cost (credit) ($/yr)
Controlled emissions (metrft tors/yr]
Cost (credit), $ per Kg controlled
1 1 ,800
970
2,024
(5,633)
(2,639)
1O 1
10. 1
(0.201)
17,600
970
3,020
(5,633)
(1,638)
13.1
(0.125)
5,725
430
982
(5.633)
(4,221)
101
I J * 1
(0.322)
8,550
430
1,466
(5,633)
(3,734)
13.1
(0.285)
11,800
754
2,024
(2,258)
520
5.25
0.100'
17,600
754
3,020
(2,258)
1516
5.25
0.289
Refrigerated
Chiller
5,000
334
858
(2,258)
(1,066)
5.25
(0.203)
7,460
*3O A
334-
1,279
(2,258)
(646)
5.25
(0.123)
Source:Reference 1 for estimates of capital and annualized costs.
-------
The cost of hydrocarbon control per kilogram shown in Table 4-7 for
the carbon adsorber on a new facility costs $0.10 per kilogram for the cross-
rod degreaser. On the other hand, the application of a carbon adsorber results
in a saving of $0.201 for the monorail degreaser. On the retrofitted facility,
the application of the carbon adsorber costs $0.289 per kilogram for the cross-
rod degreaser but results in a savings of $0.125 for the monorail degreaser.
It must be noted that the difference in cost for the two degreaser models
is sensitive to the emission rate and potential solvent recovered because the
annualized costs of installing and operating a carbon adsorber are assumed to
remain approximately the same in both cases. This is an important consideration
in the impact of control upon the owner of the degreasers.
The refrigerated chiller appears to be inexpensive to the user regardless
of the type of degreaser and the degree of retrofit. This is demonstrated by
the savings shown for all cases in Table 4-7.
4.4.3 Cost-Effectiveness
This section provides a graphical analysis of the cost-effectiveness
for alternative control options on conveyorized degreasers. This analysis will
relate the annualized cost per kilogram of hydrocarbon control to degreaser
size for each control option.
Figure 4-2 shows a relationship of cost versus size for carbon adsorbers
and refrigerated chillers on monorail degreasers. The assumptions regarding
the size range and control efficiencies are similar to those outlined for open
top degreasers. The size range of most monorail degreasers is 1.9 to 18
square meters. As shown in Figure 4-2, the application of carbon adsorption
results in an out-of-the-pocket expense for degreasers smaller than approximately
2 square meters in working area. By the same token, carbon adsorbers can
4-20
-------
•o
-------
be quite cost-effective for degraasers with Urge air to vapor working areas.
Figure 4-3 shows a similar relationship for cross-rod cisare^ssi-s. There
are two important differences between Figure 4-3 a'-vi Figure ^-2 fcr ihe
monorail ctegreaserL, Flr^t, the si7?, i'^nqc- ~s ?.*\-v .,:s-r ;ro»" ?;fre cross-rod
degreasers. The rsnye for most cros^-rod '-i^r-na^rs 1?, !.<;• square rr/ate'-1." to
4c8 square meters. For- moncrel'1 oec-easert. vh« rang^ is 1.9 to '8 cq.-arc
meters. Seconds controls are generally mere expensive for cross-rod degressars
than for moncrail degreasers. in particular,the cost of carbon adsorption
appears to be more than offsetting solvent credits along the entire size range.
This is shown by the position of the carbon adsorption curve in relation to
the horizontal line of $0. per kilogram control in Figure 4-3. The information
depicted in the two figures for monorail and cross-rod degreasers demonstrates
the variation in costs with degreaser design that can be anticipated for
conveyorized degreasers.
4-22
-------
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4.6 REFERENCES
1. Surprenant, K.S., and Richards, D.W., "Study to Support New Source
Performance Standards for Solvent Metal Cleaning Operations" prepared
for the Environmental Protection Agency, Contract No. 68-02-1329,
Dow Chemical Company, Midland, Michigan, June 30, 1976.
2. Anon., "Typical Electric Bills 1976," Federal Power Commission.
3. Chemical Marketing Reporter, Schnell Publishing Co., March 7, 1977.
4. Private communication, Frank L. Bunyard, OAQPS, Environmental Protection
Agency, to Jerry Shields, Manager of Marketings Graymills, Chicago,
August, 1976.
5. Private communication, Frank L. Bunyard, OAQPS, Environmental Protection
Agency, to Jerry Shields, Manager of Marketing, Graymills, Chicago,
August, 1976.
6. Surprenant and Richards, OJK cit., Appendix C-4.
7. Private communication, Frank L. Bunyard, OAQPS, Environmental protection
Agency to Parker Johnson, Vice President of Sales, Baron Blakeslee Corp.,
Cicero, Illinois, March 16, 1977.
8. Private communication, Frank L. Bunyard, OAQPS, Environmental Protection
Agency to Dick Clement, Detrex Chemical, Detroit, Michigan, March 21, 1977.
9. Surprenant and Richards, 0£. cit.. page 4-97.
10. Surprenant and Richards, op_. cit., Appendix C-7.
11. Ibid., page 10.
4-24
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CHAPTER 5. ADVERSE ENVIRONMENTAL EFFECTS
OF APPLYING THE TECHNOLOGY
5.1 AIR IMPACTS
No significant adverse air impacts should result from solvent degreaslng
regulations, although gross negligence with maintenance and operation of
control devices could increase emissions in individual cases. Examples are
carbon adsorption systems operating with spent or saturated adsorbent,
maladjusted refrigeration systems and excessive ventilation rates. Proper
maintenance and operation of these controls will eliminate increases and
effect significant reductions in emissions.
Improper incineration of waste solvent is another possible area where
emissions could increase. If chlorinated waste solvents are incinerated
without subsequent gas cleaning, hydrochloric acid, chlorine, phosgene and
other potentially harmfully emissions could result. Sophisticated gas cleaning
equipment is required to control these emissions.
Boiler emissions may increase due to the steam required to distill waste
solvent and regenerate carbon beds, but in general these increases will be
insigificant compared to the emission reductions obtained by this equipment.
5.2 WATER IMPACTS
5.2.1 waste Solvent Disposal
The major potential water pollutants from solvent degreasers are waste
5-1
-------
solvents. Waste solvent can enter natural water systems through sewer
disposal or as leachate f-om landfills, Additional air pollution control?
are not expecteo to allow sewer or improper landfl'l disposal because much
of the solvent would eventually evaporate. Thus, water pollution would
probably be diminished by additional air pollution control.
5.2.2 Steam Condensate from Carbon Adsorption
The largest impact on water quality resulting from the control of solvent
metal cleaning comes from the use of carbon adsorption. Steam used to desorb
the solvent is condensed with the solvent and separated by gravity. Water
soluble stabilizers* and some solvent will remain with the water and eventually
enter the sewer system.
Stabilizers are organic chemicals added in very small quantities to
chlorinated solvents to protect them from decomposition. Stabilizers
evaporate from the degreaser as does the chlorinated solvent and both are
amenable to collection by adsorption. Furthermore, many stabilizers are
water miscible and thus will be removed almost completely from the process
during steam desorption. Chlorinated solvents are only slightly water
miscible but small quantities will remain with the water.
5.2.2.1 Chlorinated Solvent in Steam Condensate -
Solvent discharge into the sewer can typically reach 190 kg (0.13 m3 or
35 gallons) per year. This assumes solvent at a concentration of 900 ppm in
the condensate and a total of about 40,000 gallons per year of steam condensate.
*
Stabilizers may also be referred to as inhibitors or additives Some
.stabilizers are normally lost into the water of the degreaser1s water
5-2
-------
In comparison, the reduction in atmospheric emissions from the degreaser by
using the carbon adsorber would typically be 14,000 kg (10 m3 or 2500 gallons)
per year. Therefore, in this case potential sewer emissions of solvent
(before evaporating) are less than about 1.5 percent of the degreaser emissions
prevented by the carbon adsorber. The above estimates are based on two tests
which measured the solvent content in waste water from adsorbers used on
1 2
chlorinated solvents. *
5.2.2.2. Stabilizers in Steam Condensate -
In addition to chlorinated compounds, steam condensate will contain small
amounts of solvent stabilizers. When the condensate is disposed of most of
these stabilizers, because of their volatile nature, will eventually evaporate
The highest sewer stabilizer emission would probably occur with 1,1,1-
trichloroethane which requires considerable amounts of water soluble stabilizers.
Assuming a solvent recovery rate of 10 m3 per year (2500 gallons per year),
5 percent stabilizers in the 1,1,1-trichloroethane blend and 40 percent of the
stabilizer being water soluble, the stabilizer effluent to the sewer would be
0.2 m3 per year (50 gallons per year). This would be the worst case; however,
and it may not be representative of any actual degreasing processes. The
captured solvent vapor does not necessarily contain as high a precentage of
stabilizers as does the original liquid solvent. For this reason even systems
using 1,1,1-trichloroethane may not emit this amount. Furthermore, other major
solvents contain less water soluble stabilizers than 1,1,1-trichloroethane;
3
therefore, the average stabilizer emission would be less than 0.2 m per year.
A method for assessing the impact of the stabilizers would be to analyze
the toxicity, water solubility, percent composition, volatility, and BOD
(relates to the decomposition rate) for each stabilizer. Unfortunately,
percent compositions are generally considered trade secrets by solvent
5-3
-------
manufacturers. However, a literature search yielded some data which is given
in Appendix B.6.2.
After studying the effects of some of the more toxic substances, it was
concluded that only diisobutylene and triethylamine, which are used in
trichloroethylene, present any significant potential problem with regard to
o
fish toxicity. Two other stabilizers of possible concern are acrylonitrile
and epichlorohydrin, although the data on them are not yet conclusive.
If the quantity of stabilizers and solvent dissolved in the steam
condensate were found to be significant, then air sparging could dramatically
reduce the levels of all these compounds. During sparging it may be advanta-
geous to vent the off-gas back into the adsorber. Thus, atmospheric emission
of the sparge off-gas would be controlled. Furthermore, more stabilizer would
tend to remain in the recovered solvent. Although sparging appears to be an
inexpensive means of treating the waste water, the data thus far have not
indicated a significant environmental need.
5.2.3 Effluents from Water Separators
Water separators on vapor degreasers and distillation units collect a
small amount of contaminated water. This is generally less than a gallon or
two per day per degreaser, and should not create a significant impact on wate.r
quality. De-icing of refrigerated control systems which operate below 32 F,
will increase this, but probably not enough to create a problem. Steam
stripping of still bottoms in distillation units to reduce solvent content will
also increase this amount, but again probably not enough to create a problem.
5.3 SOLID WASTE IMPACT
There appears to be no significant" solid waste impact resulting from
control of solvent degreasers. The* quantity of waste solvent would not increase
as a result of controls but should decrease because of increased practice of *
5-4
-------
distillation and incineration.
Carbon used in carbon adsorber beds is discarded periodically. Vendors
and users have estimated the life of carbon at up to 30 years but replacement
is generally recommended every 10 to 15 years. Assuming there are up to
7,000 degreasers, using 50 kg of carbon each and averaging a 10 percent annual
replacement rate, disposal of carbon from adsorbers could reach 35,000 kg
annually for the nation. This amount would never be realized, however, because
spent carbon can easily be reactivated. Most major activated carbon manufacturers
are equipped for this task.
5.4 ENERGY IMPACT
Carbon adsorbers, refrigerated chillers and distillation units are the
principal energy consuming control devices used for controlling deceasing
emissions.
A carbon adsorber consumes the greatest amount of enerav because of steam
required for desorption; however, this energy expenditure is far less than the
energy required to manufacture replacement solvent. A typical carbon adsorption
system on a degreaser may consume 35 kw (120,000 Btu per hour) of energy and
recover 7 kg per hour (15 pounds per hour) of solvent. This energy consumption
estimate is based on the following assumptions: 4 kw per kg solvent for steam
production, 3 to 12 kw (10,000 to 40,000 Btu per hour) for fan power. A carbon
adsorber may typically increase the energy consumption of a vapor deceasing
4
system by 20 percent.
A typical refrigerated freeboard chiller may increase a degreaser's energy
consumption by 5 percent. The chiller would consume 0.7 to 2.2 kw (2500 to 7500
Btu per hour) if it ran at 100 percent output. The above values are derived
from assuming an average of 1 to 3 horsepower for compressor ratings. A chiller
5-5
-------
may reduce emissions by about 1.5 kg per hour (3 Ibs per hour) on a typical
2
open top vapor degreaser having a 1.7 m (18 square feet) opening. Thus,
roughly 0.5 kw • hr may be spent to save 1.5 kg of solvent.0
Solvent- distillation requires about 0.1 to 0,2 kw hr/kg of recovered
solvent (150 to 300 Btu/pounri). Assuming - , ^aam cost o* 0,78 cents/kwhr
F
(2.30 $/10 8ti!,'s than the euer.;,/ costs r,i)e lo •: '!5 ,;/k;.j of Stilled soU'erif
(0.035 to 0.07 cj/lb). Considering that c.h'sorinated solvent cost? about 45
tf/kg (20 <£/lb), the cost of the distillation energy appears to be an insignifican
expenditure.
Other vapor control devices are the powered cover and powered hoist.
Their energy consumption is insigificant because the electric motors are small
and are used only for short durations.
The energy value of the solvent saved is much greater than the energy
expended to conserve the solvent. The energy value of the solvent is composed
of the solvent manufacturing process energy plus the heat of combustion lost
when the processed petroleum feedstock is not used as fuel, plus other energy
consumed to replace the lost solvent. The heat value of the feedstock alone
is greater than the energy required to recover the solvent. Without doubt
control of solvent emissions, by any method, would have a favorable impact on
energy consumption.
5.5 OTHER ENVIRONMENTAL CONCERNS
The only other consideration might be blower noise associated with carbon
adsorbers. This noise does not affect the environment external to the plant,
although it would be noticeable inside the plant near the adsorber. Noise levels
have not been measured because they have not appeared significant when compared
to the normal noise level in machine shops and other manufacturing areas where
4
5-6
-------
carbon adsorbers are found. While noise does not seem to present a
significant environmental problem, it is worthy of consideration when
choosing the in-plant location for a carbon adsorber. This problem could
be resolved by utilizing existing noise suppression technology.
5-7
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REFERENCES
1. Scheil, George W., Midwest Research Institute. "Source Test
Trichloroethylene Degreaser Adsorber," EPA Project Report No.
76-DEG-l.
2. Scheil, George W. "Test of Industrial Dry Cleaning Operation,"
EPA Report No. 76-DRY-2.
3. Surprenant, K.S. and Richards, D.W., Dow Chemical. "Study to
Support New Source Performance Standards for Solvent Metal
Cleaning Operations," Prepared for EPA, Contract No. 68-02-1329,
Task Order No. 9.
4. IBID. pg. 7-8.
5. IBID. pg. 7-9.
6. IBID. pg. 7-9.
5-8
-------
CHAPTER 6. COMPLIANCE TEST METHODS
AND MONITORING TECHNIQUES
It is not expected that emission testing will play a significant part
in a compliance program for degreasers. This results from the difficulty
in measuring emissions and in enforcing emission standards, as discussed in
Chapter 7. Instead, equipment and operating practice standards appear to be
more realistic options. In these, compliance relies principally upon
observation to determine if control equipment is designed and functioning
properly and to ensure that operating practices, as observed under normal
conditions, are being properly followed.
Although the compliance emphasis should be on equipment and operating
practice standards, the emission rate of a degreaser system may be useful
supplementary information. For example, if emissions are greater than
average for a system of a certain size, it is an indication that the system
is inadequately or improperly controlled. Emission rates can be estimated
roughly with an analysis of solvent purchase and inventory records and more
accurately with a material balance test.
Other emission tests that could be useful in compliance programs are
tests for leaks and tests of carbon adsorption off gas streams. The costs
of these tests will often be offset by solvent savings from reduced emissions.
An investigator with some familiarity with degreasers and carbon adsorption
systems can frequently identify defective systems with a brief inspection and,
6-1
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thus, avoid the expense of emission testing.
6.1 OBSERVATION OF CONTROL EQUIPMENT AND OPERATING PRACTICES
If the degreasing regulation specifies equipment and operating
standards, the compliance test is basically one of visual observation. The
observation control equipment and operating practices mainly involves checking
through a list of requirements; however, a Basic understanding of degreasfng
systems is necessary. The details to observe are described in Sections 3.1
and 3.2 of this report.
6.2 MATERIAL BALANCE
A material balance test seeks to quantify the amount of solvent input
into a degreaser over a sufficiently long time period so that an average
emission rate can be calculated. The major advantages of the material
balance method are: (1) the total system is checked, (2) the test is simple
and does not require expensive, complicated test equipment, and (3) records
are usually kept of solvent use, and generally all solvent added is make-up
for solvent emitted.
The disadvantage of the material balance method is that it is time
consuming. Because many degreasers are operated intermittently and because
there is inaccuracy in determining liquid levels, an extended test time is
needed to ensure that calculated emission rates are true averages.
In order to perform a material balance test, the following general
procedure should be followed:
1. Fill the solvent sump (or bath) to a marked level.
2. Begin normal operation of the degreaser, recording the quantity of
make-up solvent and hours of operation.
6-2
-------
3. Conduct the test for about four weeks, or until the solvent loss is
great enough to minimize the error in measurement.
4. Refill the solvent sump to the original, marked level, recording
the volume of solvent added. The total volume of solvent added during the
test period approximately equals the solvent emitted.
Although a highly accurate material balance is not usually necessary,
the following modifications will improve the accuracy of the test.
1. Clean the degreaser sump before testing.
2. Record the amount of solvent added to the tank with a flow meter.
3. Record the weight and type of work load degreased each day.
4. At the end of the test run, pump out the used solvent and measure
the amount with a flow meter. Also, approximate the volume of metal chips
and other material remaining in the emptied sump, if significant.
5. Bottle a sample of the used solvent and analyze it to find the
percent that is oil and other contaminants. The oil and solvent proportions
can be estimated by weighing samples of used solvent before and after boiling
off the solvent. Calculate the volume of oils in the used solvent. The volume
of solvent displaced by this oil along with the volume of make-up solvent
added during operations is equal to the solvent emission.
Proper maintenance and adjustment should be performed on the degreaser
and control system before the test period.
6.3 OTHER EMISSION TESTS
An emission measurement test on the off-gas stream from a carbon adsorber
may occasionally be necessary. However, this has value only in evaluating the
adsorption efficiency not the control efficiency of the system. This test
will give no indication of the effectiveness of the adsorber's collection
6-3
-------
system; neither will it guantify emissions from waste solvent evaporation,
leakage lossess carry-out or sump evaporation.
The better sampling systems for organic solvents use gas chromatography
(GC). Techniques for using GC are discussed in EPA-450/2-76-028, "Control
of Volatile Organic Emissions from Stationary Sources. Volume 1: Control
Methods for Surface Coating Operations." A specific method for perchloro-
ethylene is also detailed as EPA Method 23: "Determination of Total Non-Methane
Hydrocarbons as Perch!oroethylene from Stationary Sources." Finally, a method
for another chlorinated hydrocarbon is EPA Method 106: "Determination of Vinyl
Chloride from Stationary Sources." For stack measurments, velocity and flow
rate can be determined using EPA Methods 1 and 2.
One EPA emission test measured carbon adsorber inlet and outlet concen-
trations both with a flame ionization detector and with a gas chromatograph,
using integrated gas-bag samples. The methodology and test results are detailed
in EPA Project Report No. 76-DEG-l. "
Useful tools in locating leaks and other points of emission are the halide
torch and the Drager tube. The halide torch is useful as a locating device
that will detect sources of halogenated hydrocarbon vapors. The Drager tube
will quantify the vapor concentration in ppm and is useful in survey work.
These should be useful and relatively inexpensive means to locate sources and
quantify by magnitude the hydrocarbon loss. They would allow a maintenance
check of control equipment operation and prevent inadvertent losses.
6-4
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CHAPTER 7. ENFORCEMENT ASPECTS
Emission standards are generally not practical to enforce for solvent
degreasing for three reasons: (1) there is an extremely large number of
solvent degreasers, (2) emission tests are time consuming, and (3) there
are complexities in specifying acceptable emission rates. In order to
avoid use of emission standards and to provide quick, inexpensive compliance
testing, equipment and operational standards are recommended.
Even though visual inspection is relatively quick and inexpensive, it
can not easily determine whether or not the equipment and operation is in
compliance. For example, on cold cleaners it must be determined whether
or not it is practical to install an internal drainage facility. Also, for
highly volatile solvents in cold cleaners, one must decide whether or not
the cover can be classified as easily operable. Another example is in
deciding what is significant liquid carry-out. Even though Chapters 3 and 6
give background on making decisions for visual inspection, the inspector
still needs an adequate background knowledge of degreasing operations to deal
with some of the less definite aspects of enforcement.
Because most emission controls serve to reduce the emissions inside the
plant, it is reasonable to consider combining enforcement by OSHA and EPA for
control of solvent degreasers. The possibilities of a cooperative enforcement
program with OSHA and EPA are being explored.
7-1
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7.1 REGULATORY APPROACHES
There are four types of regulations which can be considered for solvent
metal cleaning: (1) emission standards, (2) equipment specification
standards, (3) operational requirement standards, and (4) solvent exemption
standards. Equipment and operational standards appear to be superior to
either emission standards or solvent exemption standards. Each of these
approaches is discussed in the following sections.
7.1.1 Emission Standards
Emission standards require an emission measurement. A material balance
is the most accurate measurement method for compliance testing but could
require over a month for one test. If solvent consumption records kept by
the degreasing operator are accurate and complete, they could satisfy the
requirement for a material balance test.
If enforcement were only to determine whether or not degreasing systems
are designed properly, then one emission test would be sufficient for each
degreaser model. However, adjastment, maintenance, and operation of degreasers
varies so greatly that the actual level of emission control cannot be expected
to be similar, even for identical degreaser models. Thus, individual degreasers
rather than models must be evaluated.
An emission standard may be a simple emission rate or it may be related
to another variable, such as work load tonnage, heat input, idling mode
emission or uncontrolled emission rate. The three most reasonable alternatives
for emission standards are: (1) simple emission rate, (2) emission rate per
open area of degreaser and (3) emission rate per work load tonnage. These
alternatives are briefly discussed below.
The simple emission rate standard provides a conventional regulation
7-2
-------
that is readily understood. However, different values of acceptable emission
rates would have to be provided for each type of degreaser. It would also
not be reasonable to require the same emission rate for large degreasers as
for small degreasers; this would require an emission rate based on the open
area of the degreaser.
Although emission rate is related to the area of the air/vapor interface,
an important consideration is the amount of work load processed. Thus, possible
improvement to an emission standard would be to relate it to the work tonnage,
for example, a specified amount of solvent emission could be allowed per ton
of work load cleaned. This type of standard would be particularly useful if
the work loads were consistent in their surface-to-weight ratio and their
tendency to entrain solvent; however, this is rarely the case. For example,
deceasing a ton of hollow rivets would result in much greater solvent
emissions than would degreasing a ton of cannon balls.
Generally, for an emission standard to apply fairly to all degreasing
applications, it must relate to the amount and type of work load. Preferably,
the emission standard should also consider the type of degreaser and its size.
Even if an emission standard could be devised to satisfy these requirements,
it would be difficult to enforce and very burdensome for degreasing operators
to have to record quantities and types of prrts cleaned.
7.1.2 Equipment Standards
Equipment standards can be easily enforced and fairly applied to the large
variety of degreasing applications. Equipment standards would not require
the same performance by a degreasing operation with a large work load as that
with a small work load.
The equipment requirement must be specific enough to ensure effective
control but not so restrictive that it would discourage new control technology.
7-3
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For example, the high freeboard, refrigerated chiller, and carbon adsorption
ventilation rate can be specified to ensure sufficient emission control.
The specifications usually represent an engineering judgement by experts in
the degreasing fields and could be revised as new test data are collected.
Another type of specification for control equipment is the exemption of
degreasers that are too small for control equipment to be economically
reasonable. Particularly in the case of refrigerated chillers and carbon
adsorbers, installation could be too expensive for small degreasers and could
even cost more than the degreaser itself, thus, a lower level cut-off of
P
approximately 1 m for open top vapor degreasers is recommended. Because
of the continuing developments in emission control for solvent degreasing,
provision must be made to approve control systems that do not satisfy the
requirements specified in this document but may still be effective. Section
3.2 describes equipisent and operational standards that can be formulated.
7.1.3 Operational Standards
As with equipment standards, operational standards can apply to almost
all degreasing applications, regardless of their size and type of work load.
Operators will play a key role in achieving emission control; however, they
will have little incentive to follow complex standards. Thus, the standard
must be simple, understandable, and precise. The numerous operational
requirements can be more easily remembered by the operator if a permanent,
conspicuous label is attached to the degreaser summarizing them. The
difficulty of enforcement may be minimized by educating the supervision and the
operator to the fact that proper operation and control equipment maintenance
will usually provide a net profit from solvent savings.
7-4
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7.1.4 Solvent Exemption Standards
There is very little flexibility in converting from non-exempt to
exempt solvents. A recent EPA notice (42 FF, 35314) has suggested that the
only materials that should be allowed exemptions are methane, ethane, 1,1,1-
trichloroethane, and trichlorotrifluoroethane. This choice is further
limited because of differences in solvency, flammability, cost, chemical
stability and boiling temperature. In general, the exempt solvent approach
to regulating solvent metal cleaning is not recommended, because it does
not achieve positive emission reduction. The rationale for this
fs discussed further in Chapter 1.
7.2 AFFECTED FACILITIES - PRIORITIES
Since there is a wide diversity of solvent degreasers, the definition
of facilities affected by degreasing regulations must be accurate. Although
all solvent degreasers may be subject to potential regulations, there are
an extremely large number of degreasers; thus, those with greater emissions
should be given higher priority for enforcement.
7.2.1 Definitions of Affected Facilities
The following defines the three types of solvent degreasers that can
be regulated.
1. Cold cleaner: batch loaded, non-boiling solvent degreaser
2. Open top vapor degreaser: batch loaded, boiling solvent degreaser
3. Conveyorized degreaser: continuously loaded, conveyorized solvent
degreaser, either boiling or non-boiling.
7.2.2 Priorities of Enforcement
Individual degreasers that yield the greatest emission reduction at
reasonable cost should have the highest priority for enforcement. Within
7-5
-------
that grouping, priority operations are vapor degreasing and waste solvent
disposal from all degreasing operations. The lowest priority is assigned to
cold cleaners, especially maintenance type with low volatility solvents, such
as those used with automotive repair.
An emission reduction of 5 to 15 tons per year can be achieved by
controlling a typical open top vapor degreaser or conveyorized degreaser.
In comparison, emissions from individual cold cleaners usually cannot be
reduced by more than 0.1 tons per year (see Appendix B). Even though
conveyorized degreaser emissions can be reduced more than open top vapor
degreasing emissions on the average, regulation of conveyorized degreasers
before open top vapor degreasers is not recommended, because conveyorized
degreasers emit significantly less solvent than do open top vapor degreasers
for an equivalent work load. Thus, it would not be advantageous to encourage
degreaser operators to choose open top vapor degreasers in order to avoid
regulations on conveyorized degreasers.
Waste solvent is a high priority area for control. Controls could be
directed towards solvent users, solvent producers, and/or solvent
disposal facilities. It is the responsibility of the solvent user to properly
dispose of his waste. Facilities which accept waste solvent must use
disposal methods which minimize evaporation. It is recommended that solvent
producers label new solvents to indicate regulations on waste disposal. For
example, a label could read that waste solvent should not be disposed of so
that it can evaporate into the air or pollute the waters. In addition to
regulating degreasing waste solvent disposal a more comprehensive enforcement
program which would cover disposal of all waste solvent and similar volatile
organic materials should be considered.
7-6
-------
Although enforcement of regulations on cold cleaners is made difficult
by their large numbers, it can be practical when enforcement trips are com-
bined with other purposes, or if there are numerous cold cleaners and
other solvent degreasers at a particular plant.
7-7
-------
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APPENDIX A. TEST RESULTS
-------
APPEND 13 A: TEST RESULTS
CONTENTS
Page
A.I Test results from Dow Report A-1
A.2 EPA Cold Cleaner Test Report A-3
-------
A.I TEST RESULTS FROM THE DDK REPORT
Under contract to the EPA the Dow Chemical Company tested eleven solvent
metal cleaners. Detailed reports of each test are contained in the Appendices
to tfte document: "Study to Support New Source Performance Standards for Solvent
Metal Cleaning Operations," prepared under EPA contract no. 68-02-1329 by
K. S. Surprenant and D. ST. Rtc&ards and dated April 30, 1976. A summary of
the results is given fn Table A-l.
A-l
-------
TABLE A-l: TEST RESULTS FROM DOW REPORT
Dow Report*
Appendix* User
C-5 Pratt Whitney
C-2 Eaton
C-12 Dow Lab
C-3 Hamilton
Standard
C-10 Vic
C-7 Schlage Lock
C-ll W. Electric
Hawthorne
Oegreaser*
OTVD
OTVD
OTVD
OTVD
(#203)
OTVO
(O&R)
OTVD
CVD-
Monorai 1
CND
def luxer
UNSATISFACTORY CONTROL SYSTEMS
C-5 ' Pratt Whitney OTVD
C-8 Super Radiator
C-4 Hewlette
Packard
C-9 J. L.
Thompson
OTVD
CND
Monorai 1
Developer
CVD
Cross rod
Vapor Area
65" x 110"
49.6 ft2
.
24.2"x22"
3.7 ft2
24.2"x22"
3.7 ft2
15 ft2
11.1 ft2
12'x4.5'
54 ft2
41.3 ft2
56"x90"
35 ft?
6'x12;
72 ft2
Solvent
1,1,1
Tri.
1,1,1
1,1,1
1,1,1
Methylene
Chloride
Methylene
Chloride
Tri.
Perc.
Tri.
1,1,1
Perc.
1,1,1
Tri
TVD = Convi
(gal/unit) (Ib/ft2-hr) (gal/unit) (Ib/ft2-hr)
97.5 gal/wk
129 Ib/ton
111 Ib/ton
7.5 gal opday
6.43 gal /day
3.63 gal/opday
2.9 gal/day
108 gal/wk
19.5 gal/wday
0.063 gal/ft2 of
circuit board
23.8 gal/wday
58 gal/wk
49 gal /day
0.33 gal/board
1.4 gal/hr
*"
50.5 gal/wk
jvorized Vapor Degi
0.16
-
-
0.373
0.373
0.373
0.955
0.955
0.955
0.186
0.450
0.605
0.79
_
0.138
1.53
-easer, Cl
58.4 gal/wk
99 Ib/ton
80 Ib/ton
4.53 gal/opday
3.67 gal/day
2.60 gal/opday
1.73 gal /day
38 gal/wk
7.5 gal/wday
0.025 gal /ft2
10.4 gal/wday
49 gal/wk
37 gal/day
0.26 gal/board
1.06 gal/hr
49.5 gal/wk
ND = Conveyor! zed
0.10
-
-
0.373
0.273
0.167
.
0.051
0.054
0.112
0.322
0.213
0.304
-
0.117
1.14
Non-boiling
Efficiency
40%
23%
28%
0
27%
55%
-
46%
43%
>40%
>43%
28%
40%
65%
62%
60%
16%
-8%
21%
25%
50%
Degreaser,
Control System
Cover-pneumatically
powered
Cover (manual)
FR = 0.5
- 0.75
• 1.0
FR • 0.5
0.75
1.0
Cold Trap
FR = 0.83 (covered
during disuse)
Cold Trap
FR = 0.75
(never covered)
Carbon adsorption
Chiller
Carbon adsorption
Cold Trap
Carbon Adsorption
Carbon Adsorption
Carbon Adsorption
Carbon Adsorption
Opday - Day degreaser
Comments
Uncovered for 24 hrs/day and
7 day/wk
No much Information on the test.
Idle (no work loads), moderate draft
_
Idle, quiet air
Work load when CT on was 50% more than when
CT off -«> 40%.
Inaccurate results. The O&R deg 1s expected to
have a higher n, due to being uncovered. O&R had
only ^-*rlf loa<|s P6*1 operating day whereas #203 had
Ventilation rate of 103 cfm/ft2. Accuracy of record-keeping
Is report** % Dow to be poor. Thus, accuracy of results
would be poor.
Range of n 1s 45 to 65%.
FR = 59%, Cold Trap design tested here was reported
obsolete model. Covered during disuse.
as an
Defective adsorption system - breakthrough; Insufficient
FR 0.04 jjFR<_ O.J. Only 37 cfm/ft^
Low control efficiency of the adsorption system is
to be because of poor ventilation design.
Material balance results
Resulcs from purchase records
1s
thought
in operaT.iun, wuay - wuiMiiy uaj , ^> MUI-* ><«*v» •'> • •• ^ •-•
1,1,1 = methyl chloroform, Tri. = trichloroethylene, Perc. •= perchloroethylene.
'The appendix of the''Dow Report describes each test in detail.
-------
A.2 EPA COLD CLEANER TEST REPORT
-------
TEST REPORT
EVAPORATIVE EMISSIONS STUDY ON COLD CLEANERS
By
Walter Pelletier
Peter R. Westlin
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
May, 1977
-------
SUMMARY
A preliminary study of cold cleaner solvent emissions was undertaken,
the purposes of which were to quantify hydrocarbon solvent evaporation losses
from typical air-agitated, pump-agitated, and unagitated cold cleaners; and
to establish relationships between evaporation rates and several controlled
test parameters. These parameters included solvent volatility, room draft
velocity, freeboard ratio, and cold cleaner operation.
Results of these tests indicate that highly volatile solvents, such as
perch!oroethylene, used in different types of cold cleaners with different
types of solvent agitation produce comparable evaporation rates. Solvents
emissions from air-agitated, pump-agitated, and unagitated units showed similar
test results with perch!oroethylene as the solvent. With less volatile
solvents, such as Mineral Spirits, agitated cold cleaners showed significantly
greater solvent emissions than did the unagitated. In addition, these test
results demonstrate a tendency for solvent emissions to increase as the room
draft velocity is increased. Closing the cover on a cold cleaner drastically
reduces solvent emissions as is also shown in these tests.
An increase in solvent emissions with a decrease in freeboard ratio in
unagitated units is indicated by these test results. Also indicated is an effect
on solvent emissions caused by the shape of the sol vent-to-air interface area
of unagitated tanks. For these tests, a square sol vent-to-air interface surface
resulted in greater solvent emissions than did a rectangular one. This result
may be affected by the orientation of the tank to the room draft air movement.
The effect of solvent volatility on evaporation rates is shown as increased
volatility produces increased solvent emissions. The largest difference between
solvent emission rates is shown between tests with the highly volatile,
relatively pure perch!oroethylene and the mineral spirits mixtures.
-------
TABLE OF CONTENTS
Page No.
I. INTRODUCTION -,
II. EQUIPMENT AND SOLVENTS
III. TEST PROCEDURES 2
IV. DISCUSSION OF RESULTS 5
Appendix A: Test Data 15
Appendix B: Solvent Analyses 21
-------
I. INTRODUCTION
The Emission Measurement Branch of the Emission Standards and
Engineering Division undertook a laboratory study of cold cleaners used for
parts degreasing. The purpose of the study was twofold: first, to quantify
hydrocarbon solvent evaporation losses from typical air-agitated, pump-agitated,
and unagitated cold cleaners; and second, to establish relationships between
evaporation rate and several test parameters including solvent volatility,
room draft velocity, and free-board ratio.
In this preliminary study, a minimum number of data have been collected.
In most cases, each data value represents only one test run, the curves are
plotted with only two or three points, and comparisons are made based on only
two or three test runs. The results included in this report should be regarded
as preliminary and, at best, only indications of trends that can occur with cold
cleaner solvent emissions.
The tests were conducted at the IRL laboratory under controlled conditions.
Four different cold cleaner models were used for this study: an air-agitated
Kleer-Flo model 90 unit, a pump-agitated Gray Mills model 500 cleaner, a Kleer-
Flo model A-15 unagitated unit, and a Gray Mills model SL-32 unagitated cleaner.
The four different solvents used for these tests were perchloroethylene, 102
mineral spirits, 112 mineral spirits, and 140 mineral spirits.
The results are expressed in mi Hi liters of solvent lost per hour per
2
square meter of surface area (ml/hr . m ) and in grams of solvent lost per hour
2
per square meter of surface area (g/hr . m ). These data are used to develop
curves displaying the relationships between evaporation rate and the test
parameters.
II. EQUIPMENT AND SOLVENTS
A schematic of the Kleer-Flo model 90, an air-agitated cold cleaner, is
-------
2
shown in Figure 1. The air for agitation was supplied by an industrial
compressor, and the rate of air injection was set at a relatively constant
4 to 5 liters per minute with the use of a calibrated orifice meter. Although
not used in any calculations, the air injection temperature was monitored with
a dial thermometer.
The pump-agitated cold cleaner used in these tests was the Gray Mills
model 500 unit. This unit was connected to a timer-switch set to run the pump
agitator for 20 minutes out of every 65 minutes in a repeating cycle for all
test runs. This was done to avoid over-heating the solvents and to more
realistically represent the operation of the cleaner.
Tests of unagitated cold cleaners were performed using two different sized
units. One was a Kleer-Flo model A-15 shown in Figure 2. The other cleaner
was a Gray Mills model SL-32. Calibrated thermocouples were used to measure
solvent temperature and ambient temperature for these test runs as well as for
the other test runs.
III. TEST PROCEDURES
The measurements made for each test included solvent volume, room and
solvent temperatures, room draft velocity, and solvent density. Temperatures
were measured with chrome!-alumel thermocouples calibrated at the water-ice
point and at water boiling temperature corrected for barometric pressure. Re-
corders were used to monitor these temperatures over an extended period of
time. The temperatures reported in this report represent runs averages that
have ranges of about +. 5°K. Accuracy of the measured values is estimated at
+ 1°K.
Room draft velocity was measured with an A!nor thermo-anemometer held
30 cm above the top of the tank. The measurements are estimated to have a
+_ 10 percent accuracy for draft velocities above 30 m/min while below this
10
-------
Figure l: Schematic Diagram'of
Kleer-Flo Model #90
Cold Cleaner
COVER
09-A
SUPPORT ARM ASS'M
IO
SPRING CLOSURE
10-2
FUSIBLE LINK
10-1.
LOWER HOSE
12
— BARRIER FILTER
13
•FILTER HOUSING
14-1 •
FILTER CARTRIDGE
14-5
-MOTORS. PUMP ASS'M
15
KLEER-F 0 SUPER CLEANMASTER
MODEL 90
NOT 5HOWJL
07
CASTERS 02-2
DRYING SHELF
BASKET 08
COVER KNOB 09-2
BRUSH 83-1
BRUSH HOLDER 09-1
_
RIGHT HAND
LEFT HAND Oo
AIR GUN 03-14
AIR HOSE OJ-ll
AIR VALVE O3-9
MOTOR LOUVRE 04
SWITCH 04-2
INDICATOR LIGHT 04-
RESERVIOR COVER 05-
-------
(COVEft ANO 6ASh£T REMOVED)
Figure 2: Schematic Diagram .
of Kleer Flo Model # A-15
Cpld Cleaner •
•COVER
(l 509)
.-BASKET
(1506)
12
'' MAM I 0«-D
-------
5
level, the accuracy falls to about +_ 20 percent.
Solvent density was determined gravimetrically before and after each
test run. Solvent volumes were measured with calibrated containers. Accuracy
of these measurements is estimated to be about + 2 percent. Samples of solvents
were collected for analysis of distillation characteristics and volatility.
These data are shown in Appendix B.
Prior to initiation of the test, the cold cleaner units were partially
filled with solvent and operated, if applicable, for a short period. This
conditioning step filled any reservoirs with solvent. After the cleaner was
drained, a measured amount of solvent was placed in the cleaner and the test
conditions were set as desired. Draft velocity was maintained with a laboratory-
hood exhaust fan and small, caged, portable fans. At the end of the test period,
the solvent was drained from the cold cleaner in the same manner as was completed
earlier. The volumes were measured with calibrated containers and the volumes
were recorded. Test conditions such as solvent temperature, ambient temperature
and humidity, and other test parameters were recorded.
IV. DISCUSSION OF RESULTS
Tables 1 and 2 show the results of tests with the air-agitated and pump-
agitated cold cleaners, respectively. The test data for the two unagitated units
are shown in Tables 3 and 4. Figure 3 shows a plot of the relationship between
evaporation rate of perch!oroethylene and room draft velocity for these cleaners.
The scatter in the results shown on this figure indicates that the type of cold
cleaner and the agitation method have little effect on the evaporation rate of
a highly volatile solvent such as perch!oroethylene. One result that is evident
is that the evaporation rate of solvent increases with an increase in room draft
velocity for all types of cleaners. The data show that for the air-agitated unit,
-------
TABLE 1. EVAPORATION RATE TEST RESULTS FOR THE
AIR-AGITATED COLD CLEANING UNIT
Solvent
Perchloroethylene
Perchloroethylene
Perchloroethylene
112 Mineral
Spirits
140 Mineral
Spirits
140 Mineral
Spi ri ts
Cover
Position
Open
Open
Closed
Open
Open
Open
Room
Draft
(m/min)
27
85
83
4
3
22
Evaporation
Rate
(ml/hr . m2)
616
1758
143
83
34
75
Evaporation
Rate
(g/hr . m2)
992
2848
231
65
26
57
-------
TABLE 2. EVAPORATION RATE TEST RESULTS FOR THE
PUMP-AGITATED COLD CLEANING UNIT
Room
Draft
(m/min)
64
28
97
Evaporation
Rate
(ml/hr . m2)
1167
464
423
Evaporation
Rate
(a/hr . m2)
1891
751
677
Solvent
Perchloroethylene
Perchloroethylene
Perchloroethylene No
Agitation
102 Mineral 186
Spirits 59 *w
140 Mineral ,.
Spirits 3 64
-------
TABLE 3. EVAPORATION RATE TEST RESULTS FOR AN
UNAGITATED COLD CLEANING UNIT
GRAY MILLS MODEL SL-32
(Dimensions: 81 cm x 41 cm x 25 cm Deep)
,_ , , n .. Freeboard Height\
(Freeboard Ratio = a—)
Freeboard
Solvent Ratio
Perchl oroethylene
Perchl oroethylene
Perchl oroethylene
Perchl oroethylene
102 Mineral
Spi ri ts
102 Mineral
Spirits
102 Mineral
Spirits
HO Mineral
Spirits
140 Mineral
Spirits
0.27
0.50
0.29
0.50
0.50
0.29
0.50
0.29
0.50
Room
Draft
{m/mi n )
57
52
3
3
52
3
3
3
3
Evaporation
Rate
(ml/hr . m2)
1156
824
56
8
142
9
8
n
4
Evaporation
Rate
(q/hr . m2)
1873
1311
89
12
109
7
6
8
3
-------
TABLE 4. EVAPORATION RATE TEST RESULTS FOR AN
UNAGITATED COLD CLEANER
KLEER-FLO MODEL A-15
(Dimensions: 33 cm x 33 cm x 32 cm Deep)
Freeboard Height^
VrreeDoara Kdtiu
Freeboard
Solvent Ratio
Perchl oroethyl ene
Perchl oroethyl ene
Perchl oroethyl ene
Perchl oroethyl ene
Perchl oroethyl ene
102 Mineral
Spirits
102 Mineral
Spirits
102 Mineral
Spirits
102 Mineral
Spirits
140 Mineral
Spirits
140 Mineral
Spirits
140 Mineral
Spirits
0.20
0.42
0.20
0.42
0.74
0.42
0.20
0.42
0.74
0.20
0.42
0.74
33
Room
Draft
(m/min)
58
53
3
3
3
53
3
3
3
3
3
3
/
Evaporation
Rate
(ml/hr . m2)
1508
1210
88
20
27
159
26
27
24
9
11
11
Evaporation
Rate
(q/hr . m2)
2442
1937
141
31
43
124
20
20
18
7
9
8
-------
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-------
11
2
the evaporation rate of perchloroethylene increases from about 1000 g/hr . m
at a room draft velocity of 27 m/min to over 2800 g/hr . m2 at 85 m/min. Tests
with the other models showed similar results.
A third test run was made with the perchloroethylene in the air-agitated
cold cleaner with the lid closed. At a draft velocity of about 85 m/min, the
2
evaporation rate with the cover open was over 2800 g/hr . m , while with the
2
cover closed, the evaporation rate was reduced to about 230 g/hr . m . This
represents better than a 90 percent reduction in emissions.
Results of tests with less volatile minerals spirits showed somewhat
different relationships. At room draft velocities below 5 m/min, the agitated
cold cleaners showed significantly greater evaporation rates of mineral spirits
than did the unagitated models. For example, under similar test conditions and
room draft velocities under 5 m/min, the emissions from the air-agitated cold
cleaner were about 25 g/hr . m2 of 140 mineral spirits, the pump-agitated unit
emissions were about 50 g/hr . m2, while the unagitated unit emissions were less
than 10 g/hr . m2. Data from tests at higher draft velocities are limited, but
a similar result can be shown for the evaporation rates of 102 mineral spirits
at 50 to 60 m/min draft velocity from the pump-agitated unit and from the two
unagitated models.
For these tests freeboard ratio is defined as the height from the surface
of the solvent to the top of the tank (freeboard height) divided by the length
of the shorter side of the tank. Figure 4 shows the relationship of the
evaporation rate of perchloroethylene versus freeboard ratio. The figure
demonstrates the tendency for solvent emissions to decrease as the freeboard
ratio is increased.
-------
-------
13
Figure 5 displays the relationship between evaporation rate of various
grades of Mineral Spirits Events and freeboard ratio. Solent losses for
these tests were extre*ly small and the Inherent Imprecision In measuring
these small differences probably account for the lack of clear trends on this
figure One notable result demonstrated Is that the KUer-Flo A-15 cold
cleaner showed greater evaporation losses under the same conditions than did
the Gray Mills cold cleaner. This difference may be due to the difference
in the shape of the two units. The Kleer-Flo model has a square solvent-to-
air interface area, while the Gray Mills unit has a rectangular C- 2:1 length
to width ratio) interface area. These data are normalized as to the solvent
area, and the conditions under which these data were conducted were lto.tic.1.
so any difference between test results from the two tanks may be because of
the shape difference. In addition, the Gray Mills tank was oriented the same
way for all tests; that 1s, the room draft direction was parallel with the
short sides of the tank. Turning the tank so that the room draft direction i.
parallel with the long sides of the tank would Hkely produce different results.
The effect of solvent volatility, In terms of solvent Initial boiling
temperature, an evaporation rate Is demonstrated In Figure 7. For this figure,
an increase In Initial boiling temperature corresponds to a decrease In solvent
volatility. The slopes of the three curves on Figure 7 Indicate that evaporation
rates decrease with decreasing solvent volatility. The Kleer-Ro A-15 mode! cold
cleaner was used for these tests. It Is not apparent that the square surface
shape of this unit had any effect on these results.
-------
o
"jCr-' ra ft.;:
- '-:
-------
Ott,
I
01*
OO
-------
APPENDIX A
TEST DATA
-------
PO
en
TABLE A. EVAPORATION TEST RESULTS FOR THE KLEER-FLO MODEL 90
AIR-AGITATED COLD CLEANER
(Surface Area of Agitated Section = 0.398 m2, Total Solvent Surface Area = 0.974 m )
Run
1-A
Open
2-A
Open
3-A
Closed
4-A
Open
5-A
Open
6-A
Open
Solvent
Perch! oroethylene
-
Perchloroethylene
Perch! oroethylene
!12 Mineral
Spirits
140 Mineral
Spirits
140 Mineral
Spirits
Ave.
Room
Temp.
293
290
293
293
293
295
Ave.
Solvent
Temp.
291
289
292
389
293
295
Ave.
Injected
Air
Temp.
( K)
291
290
292
288
291
293
Ave.
Injected
Air
Moisture
w
1.6
.0.8
0.4
1.5
1.7
1.5
Ave.
Injected
Air
Rate
(1/min)
4.9
4.0
4.2
4.4
4.8
5.0
Ave.
Room
Draft
(m/min)
27
85
83
4
3
22
Solvent
Density
(g/ral )
1.61
1.62
1.62
0.78
0.77
0.77
Test
Run
Time
(hrs:min)
19:08
16:40
16:16
47:19
89:53
74:25
Volume
Loss
(1)
8.34
28.54
2.26
3.81
3.00
5.41
Evaporation
Rate y
(ml/hr . i/)
616
1758
143
83
34
75
Evaporation
Rate ?
(g/hr . nT)
992
2848
231
65
26
57
-------
TABLE B. EVAPORATION TEST RESULTS FOR THE GRAY MILLS MODEL 500
PUMP-AGITATED COLD CLEANER
Run
Solvent
(Surface Area = 0.415 m )
Ave. Room Ave. Solvent Ave. Room
Temp. Temp. Draft
Solvent Test Run
Density Time
(g/ml) (hrrmin)
Volume Evaporation Evaporation
Loss Rate ? Rate „
(1) (ml/hr . nT) (g/hr . nT)
1-B
2-B
3-B
lo Agi
4-B
Perch! oroethylene
Perchloroethylene
Perghl oroethylene
tation
102 mineral
Spirits
292
293
299
288
293
• 295
298
292
64
28
27
59
1
1
1
0
.62
.62
.60
.76
21:18
43:08
93:35
95:47
10.
8.
16.
9.
32
34
4
7
1167
464
423
244
1891
751
677
186
5-B 140 Mineral
Spirits
292
295
0.77 90:27
2.4
64
49
-------
TABLE C
EVAPORATION TEST RESULTS FOR THE GRAY MILLS MODEL SL-32
UNAGITATED COLD CLEANER
2
(Surface Area = 0.332 m )
Ave. Room
Temp.
Solvent (°K)
Perchloroethylene
Perchloroethylene
Perchloroethylene
Perchloroethylene
102 Mineral
Spirits
102 Mineral
Spi ri ts
102 Mineral
Spirits
140 Mineral
Spirits
140 Mineral
Spirits
290
292
298
292
290
295
297
296
299
Ave.
Solvent
Temp.
292
294
298
292
293
293
296
294
297
Ave.
Room
Draft
(m/min)
57
52
3
3
52
3
3
3
3
Freeboard
Ratio
0.27
0.50
0.29
0.50
0.50
0.29
0.50
0.29
0.50
Solvent
Density
(g/ml)
1.62
1.59
1.60
1.61
0.77
0.76
0.76
0.77
0.76
Test Run
Time
(hr:min)
16:09
16:20
137:15
116.27
98:59
137:50
141:25
115:20
164:30
Volume
Loss
(1)
6.2
4.5
2.5
0.3
4.7
0.4
0.4
0.4
0.2
Evaporation
Rate 2
(ml/hr . m )
..,-.,. i — .
1156
824
56
8
142
9
8
11
4
Evaporation
Rate o
(g/hr . nr)
— —..... ., - . — •
1873
1311
89
12
109
7
6
8
3
-------
TABLE D. EVAPORATION TEST RESULTS FOR THE KLEER-FLO MODEL A-15
UMAGITATED COLD CLEANER
(Surface Area = 0.109 m2)
Run
1-D
2-D
3-D
4-D
5-D
6-D
7-D
8-D
9-D
10-D
11-D
12-D
Solvent
Perchloroethylene
Perchloroethylene
Perchl oroethyl ene
Perchloroethylene
Perchloroethylene
102 Mineral
Spi ri ts
102 Mineral
Spirits
102 Mineral
Spirits
102 Mineral
Spirits
140 Mineral
Spirits
140 Mineral
Spirits
140 Mineral
Ave.
Room
Temp.
(°K)
290
292
298
292
300
290
295
297
299
295
299
295
Ave.
Solvent
Temp.
(°K)
292
294
299
292
299
293
293
296
297
295
298
295
Ave.
Room
Draft
(m/min)
58
53
3
3
3
53
3
3
3
3
3
3
Freeboard
Ratio
0.20
0.42
0,20
0.42
0.74
0.42
0.20
0.42
0.74
0.20
0.42
0,74
Solvent
Dens i ty
(g/ml)
1.62
1,60
1,60
1.61
1,60
0,78
0.76
0.76
0.77
0.77
Q.76
0.77
Test Run
Time
(hr:min)
16:09
16:20
92:40
117:17
71:25
98:59
92:40
140:55
93:10
114:40
164:15
75:30
Volume
Loss
(1)
2.7
2,2
0,9
0,3
0.2
1,7
0,3
0.4
0.2
0.1
0.2
0.1
Evaporation
Rate 9
(ml/hr . ITI )
1508
1210
88
20
27
159
26
27
24
9
11
11
Evaporation
Rate 9
(g/hr . r/)
2442
1937
141
31
43
124
20
20
18
7
9
8
Spirits
-------
APPENDIX B
SOLVENT ANALYSES
-------
DATE:
,UBJECT:
FROM:
TO:
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
May 4, 1977
Analysis of Mineral Spirits and Perchlorethylene
Chemistry Section, ACB (MD-78)
R. Shigehara, OAQPS/EMB (MD-13)
W. Pellitier, OAQPS/EMB (MD-13)
Seventeen samples were submitted to this laboratory on a
Sample Request and Report Form dated April 21, 1977. Reid Vapor
Pressure and Distillation analysis was requested. Distillations
were run on all but one sample where a specific request was made
that it not be run. Reid Vapor Pressure was requested and attempted
on all samples but only three samples had enough pressure for positive
measure. This analysis was conducted using the ASTM Method D-323.
EPA Form 1320-6 IRc«. 3-76>
o .
-------
REPORT OF ANALYSIS
TRACE ELEMENTS
ppm • (or solid sornples
ug/ml - for liquid samples
Mc-V (xi (or specific c':',ns
(i| m block to lei! o! Ifleil. No
oil onol)Sis on '.fxji line
m LJ m LznnnnrEjij LJ LJ L
JIITTIJT:JTJIIJIITT:JTITTJ i ih LJ CTEJT
; ZTT: ire JT: TT; n
c iru im JTTJT: un ire im im irt 3T±n: jn ire ITT- D
im 3ijTr uxc
I-HAA, 2-SSMS, 3-OES, 4-AA, 5 AGV, 6-XRF, ond 7-otliei
; "-' fi^'^'S • U'e Totiie B lo fill ordysis requsiletl [o5o/e etch column)
MorX (x) loi spccilic analysis 'e^s'.'.
-------
TRACE EUVEVS V;-* ~*i'
^ 3.BP
J 32-1
_J 7^2
_l 5T3/7
j-r-,f *J *j ,* -it
\ *2. t "s
J $.*/£
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lo %
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— 1 3?-£
J 3}£
J ^-z^/fr
J
So'h
J 3**-
LJ 323
J $43
, 1 %£/
1 •?,£ /
— 1 £•/£
J 333
-J 333
-Jjy/
u
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— J 313
J if£
U ^f3
J sfi/
-J 31}
-J MS
LJ^/7
— ' 3/7
LJ 370
J
//*
— 1 f//s
J 1/J.f
J y/2%
J t/zg
J ¥o1
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J _j^f
-J 39&
J
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of
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-------
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SAMPLING DATE
SOURCE SAMPLE REQUEST & REPORT
(MUST BE FILLED OUT FOR EACH TEST RUN)
YR
MO
DAY
FIRST IDENT.
NO. USED
- ooa-
LAST IDENT.
NO. USED
TEST NO
RUN NO
INDUSTRY TeLwtrf'^ov* V\.
(USE TABLE A)
I^VQ'
COMPANY.
ADDRESS .
SAMPLING.
METHOD
V
UNIT PROCESS OPERATION.
AIR POLLUTION CONTROL.
FUEL USED.
e
D INLET D OUTLET
CAS VOLUME SAMPLED
(METER VOL IN FT3)
IDEM NO
JaSS
DESCRIPTION OF
SAMPLE OR SAMPLE
FRACTION
>o
./f^//)
To
SAMPLE
WT VOL
(SOLID)
MG
(LIQUID)
ML
Soo
5oO
ANALYSIS REQUESTED - GENERAL COMMENTS
(APPROX CONCENTRATIONS - POSSIBLE INTERFERENCES
ETC) (INDICATE SPECIFIC ANALYSIS ON BACKSIDE)
c-\i t-,vx /\
3
n
-1°
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D-ATE P . ".EQUEST ^ - SV -^\"3
_DATE ANALYSIS REQUESTED.
DATE OF REQUEST
(iQ aE FiLLtD IN br :>;>rA6)
-------
Samples of Mineral Spirits and Perchloroethylene From EMB.
Distillation
Sample No.
S-77-002-602
-603
-604
-605
-606
-607
-608
-609
-610
S-77-002-639
S-77-002-656
-657
-658
-659
-660
-661
-662
- •"
Ton
IBP
.
326 330
332 333
339 340
332 333
327 328
245 245
Distillation Not
322 325
325 325
330 330
369 372
317 327
368 371
364 371
369 372
246 244
246 245
..
50%
352
353
353
351
351
245
Requested
333
333
342
378
342
379
379
380
245
! 245
90%
383
386
383
384
382
245
359
357
370
393
371
395
395
394
246
246
EP RVI
415
428
423
423
409
286
388
392
409
417
411
423
423
420
286
290
0.0
0.5
0.9
0.8
-------
' REPORT OF ANALYSIS
TRACE ELEMENTS
5 ppm - for solid samples
Q eg/ml - for liquid samples
O
i
O
o
o
o
o
©
0
©
©
o
©
o
o
0
•0
e
o
o
o
o
Ident No.
Ar
olysis M
Hq
J L
J L
J L
J L
J L
j d
J L
J L
J L
1 1
ethod:
Be
J L
J L
J L
J L
J LJ
J L
J L
J L
J L
1
l-NAA,
Cd
J L
J L
J L
J L
J L
J L
J L
J L
J L
J L
As
J L
J L
J L
J L,
J U
J L,
r1 L
J L
J L
J L
V
J L
J L
J L
J U
J L
J L
TT_
J L
J L
J L
Mn
TE
J L
J L
J L
J L
J L
ITC
r1 L
TT:
J L
Ni
TT:
TT
J L
r1 L
J L
TT
im
J L
TT:
J L
Sb
TT:
TT:
J L
TT:
J L
TT
TT:
TE
TTJ
J U
Cr
TT:
J L
J L
TT_
J L
ZTL
TTJ
TT:
T"L
J L
Zn
TT:
J L
J L
J L
J L
J L,
TC.
TT_
J L
J L
Cu
J L
r1 L
r1 L
J L
TT:
J L
J L
J L
J L
J L
Hb
J L
J L
J L
J L
_F L
J L
J L
U L
J L
J L
lie
J L
J L
J L
pl L
J L
J L
J L
J L
J L
J L
B
J L
J L
J L,
J L
J L
J L
J L
J L
J L
J L
F
J L
J L
J L
J L
J L
J L
J L
J L
J L
J L
LI
J L
J L
r1 L
r1 L
J L
J L
J L
J L
J L
J L
Ag
J L
J L
J L
J L
J L
l_iT_
J L
J L
J L
J L"
Sn
J L
J L
r1 L
J L
J L
TH
J L
J L
J L
TT:
Fe
J L
J L
J L
J L
J L
TI
J L
TT:
L
J L.
Work (n) for specific analysis
Mark (n) in block to left of Ident. No w
requesting all analysis on thot line
Sr
J L
L
J L
L
J L
L
J L
J l_
L_
No
J L
J L
J L
L
J L
TJ
L
J L
T L
T_
K
J L
J L
L
L
L
L
\—
TL
J L
L
Co
L
J L
L
L
L
L_
_1 L
L
Si
J L
J L
L
L
L
L
_l L
L
Mg
J L
J L
J L.
L
L
I f-T
J L
L
L
Bo
— i — i —
J L
— i —
L.
J L
— i —
L
3
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L
— i —
i_
D— T—
L
— i —
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— i — i —
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— i — i —
_J L
— i —
L
— i — i —
i— ' "—
— i —
L
— i — '
1 —
D— i —
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D— i —
1
— I — i —
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— i —
L
— i — i —
_J L_
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1
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2-SSMS 3-OES 4-AA, 5-ASV, 6-XRF, end 7-other Comments.
nthpr Analysis - Use Table B to fill analysis requested (obove each column)
Ident No.
A
/ x/
/ ^7
*
///
(to
lalvst
Method
Comments:
i^Of J°
J
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SAMPLING DATE
INDUS
COMP
ADDR
SAMP
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IDENT NO
r^~~
-
1
\n A ~>"i 1
(' l\ A SQJ i
JYR MO DAY 1
(USE
ANY,
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LING.
00
suURCE SAMPLE REQUEST & REPORT
(MUST BE FILLED OUT FOR EACH TEST SUN)
TEST NO
'FIRST IDENT. LAST IDENT. -
NO USED S-T-l.OOa.^X HO. USED 5 ~ ^^ - OO^ - <-^ RUN NO
TABLE A)
DESCRIPTION OF
SAMPLE OR SAMPLE
FRACTION
,-> VVN o, »v s K r • a
N
1 COMMENTS: —
j 1 ,. .
SAMPLING
UNIT PROCESS QPERATIOf
A!R POLLUTION CONTRO
FUEL USE
D INLET D OU
GAS VOLUME SAMPLE
(METER VOL IN FT3
SAMPLE
WT VOL
(SOLID) (LIQUID)
MG ML
49,0
S>oo
i __ • —
n . —
TLET
n..... —
ANALYSIS REQUESTED • GENERAL COWENTS
(APPROX CONCENTRATIONS - POSSIBLE INTERFERENCES
ETC) (INDICATE SPECIFIC ANALYSIS ON BACKSIDE)
\l,\A. Ve,c,4.i_J?VT ",'.— <• ' T^XAVaW V
\t
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— —
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REQUEST
Bnnirr.Tnrnr.rn t.NAV.,o> ^A^ .V.ns^ „ REVIEWED BY
CONTRACTOR ___...«,.,.-,,. .....
(IF APPLICABLE)
fL r^nnccT niiTe «u»i vci« pcnn«TFn _____ DATE OF REQUEST _______ _ /ti n
DA!t 01- RtQUEST_ _
i
-------
* — .*-^,<--_»2f.-tt- jift-f---M--'- A>-;t_UiV-^.T.r"J-j""'A-r'-'^ --"-**-**S*-*-
t> o e ''e^©'© i© i©1© 'o oiolo
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SAMPLING DATE
INDUS
COMF
ADDR
SAM?
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1DHNT NO
Co 3
Gc-s
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YR MO DAY I ^
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to © o o cio o c © o e o © o,© o o©ooo©oco
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SOURCE SAMPLE REQUEST & REPORT
(MUST BE FILLED OUT FOR EACH TEST RUN)
IDENT. LAST IDENT. ^2^
SED £>-TT - oo'2 - C.02. NO. USED ^' 77- QQS - faf^r
.v-^^^vtvC YJV-CIP^
. (USE TABLE A)
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DESCRIPTION OF
SAMPLE OR SAMPLE
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hAv,'-\ S>o^,u-\o2. (\r>'iWO T?u*3-F
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UNIT PROCESS OPERATIC
AIR POLLUTION CONTRC
FUEL USE
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GAS VOLUME SAMPL
(METER VOL IN FT^
SAM
WT
(SOLID)
MG
.^
^
2- CvA.^ 'Sv^S^Kv.iotel
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ANALYSIS REQUESTED - GENERAL COMMENTS
(APPROX CONCENTRATIONS - POSSIBLE INTERFERENCES
ETC) (INDICATE SPECIFIC ANALYSIS ON BACKSIDE)
^«vA V-O-- "Pje-^^r*
- "\^..AAVo\x'o^ tWW.-,
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SAMPLING
CONTRACTO
DATE OF REQW
EPAlDUR)245'
R
T-I - REQUEST // <^/ J
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(IF APPLICABLE) '
"ST 4/7 \ /Tf OATF AN4I YSIS RFOIIFSTPn DATE OF RFOUFST
(TO BE FILLED IN BY SSFAB)
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-------
APPENDIX B. CALCULATIONS
-------
APPENDIX B
CALCULATIONS
CONTENTS
Page
B.I Degreasing Emission Summary B-l
B.2 Cold Cleaner Emissions B-3
B.2.1 National Cold Cleaner Emissions (1974) B-3
B.2.2 Emission Rate Per Cold Cleaner B-4
B.2.3 Projected Emission Reductions B-5
B.3 Open Top Vapor Degreaser Emissions B-7
B.3.1 National Open Top Vapor Degreaser Emissions (1974) B-7
B.3.2 Emissions Per Average Unit B-7
B.3.3 Projected Emission Reductions B-7
B.4 Conveyorized Degreaser Emissions B-9
B.4.1 National Conveyorized Degreaser Emissions (1974) B-9
B.4.2 Emissions Per Average Unit B-9
B.4.3 Projected Emission Reductions B-9
B.5 Degreasing Waste Solvent Disposal B-ll
B.6 Calculations Relating to Adverse Environmental Affects B-13
B.6.1 Increased Boiler Emissions B-13
B.6.2 Stabilizers in Chlorinated Solvents B-14
B.6.3 Utilities Consumption of Carbon Adsorbers B-16
B.6.4 Fuel Costs of Incineration for Manufacturing
Cold Cleaners B-17
B.7 References B-18
-------
*3
B.I DECREASING EMISSION SUMMARY, 1974 (All units = 10 metric tons/yr)
1, Total Organic Emissions from Degreasing 700
Cold Cleaning 380 (55%)
Open Top Vapor Degreasing 200 (28%)
Conveyor i zed Degreasers 100 (14%)
(25 CND & 75 CVD)
Wiping Losses 20 (3%)
2. Contribution to National HC Emissions
Degreasing Emissions (1974) = 700 = 2 5%
National HC Emission (197b) 2lfiOO
Degreasing Emissions = 700 = 4j%
National HC Emissions from 1/000
Stationary Sources (1975)
3, Solvent consumption data were collected from several sources and
tabulated in Table B-l. The consumption estimates were averaged to estimate
the solvent consumption of each type of degreaser. These data were the basis
for our emission estimates.
B-l
-------
U.S. Consumption of Dpg^e.ising Solvents
Table B-l
1974 (10 metric tons/year)
Solvent Type
Halogenated
I'richloroethylene 1
1,1,1 Trichloroethane
Perchloroethylene
Methyl ene Chloride
Trichlorotrifluoroet-hane
"otal '-
Aliphatic
Aromatic
bei.zene
Toluene
Xylene
Cyclohexane
Heavy Aromatics
Total
Oxygenated
Atones
Acetone
Methyl Ethyl Ketone
A \ c o h o 1 s
Butyl
Ethers
Total
TOTAL
Breakdown:
Vapor Deg. Solvents
Weighed
Average
vp+CC=Total
28+2: n53
°.Q+8? - . t>?
.11^3= 54
7 + i' 1= 30
20+lu- 30
/t + lb3=-tJ9
222
7
14
12
1
_12
4T5
10
8
5
6
19
726
- VD - 276 ^
1 2
Monsanto-S.A.D. U.S. Tariff Comm.
Tom Hoogheem-1974 Report for 1974
VD_ + CC_ = Total VD + CC_ = Total
157 142 + 8 = 150
90 + 78 = 168 73 +106 = 179
43 + 11 = 54 40 + 19 = 59
10 + 46 = 56 7 + 18 = 25
- = 17 - . = .
-
225
7
. 4
1 '' Ho
1 Data
-
10
7-5
No
30 Da t a
. 3
6
26.5
Expected Accuracy:
: 275 ±10 percent - VD = 275 +25
Dow Final
Report3
Survey for 1974
VD + CC_
103 + 39
110 + 63
41+9
7.5 +6.3
34 + 18
296 +135
Ranges:
= 250 to
= Total
= 142
= 173
= 50
= 13.8
= 52
= 431
No
Data
10
8
7
_
~
300 T3T
Dow
Chart
for
1974
VD Only
J43
73
40
9
20
285
No
Data
No
Data
10 metric
Detrex Es
Pr
1975
VD
114
63
45
8
20
25T5"
No
Data
No
Data
ton/yr)
;t1mat
•oject'
1974
VD
124
53
40
6
18
241
No
Data
J. S. Gunnir£
Shell Chemical
Solvent Bus. Ctr.
No Data
218
12
No Data
Cold Clean. Solvents ? CC = 153+222+46+29
= 153+222+75
= 153+297
= 450
±15%±30%±50% - CC = (155±25) + (220 ±65) + (75± 35)
= (130 + 155 + 38) to (180 + 285 + 112)
= 323 to 557
= 4bO ± 127
R_9
-------
B.2 COLD CLEANER EMISSIONS
B.2.1 National Cold Cleaner Emissions (1974)
Given: (a) Gross cold cleaning solvent consumption = 450 Gg/yr* 1974
(b) about 5% of this is from wiping operations, which are
not considered cold cleaner (CC) emissions
(c) about 25 Gg/yr of this is from conveyorized non-boiling
degreasers (CND). (See subsection B.4.1)
(d) Waste solvent disposal (WSD) amounts to 280 Gg/yr.
Approximately 7% of this is incinerated or landfilled in such
a manner that no emissions occur. (See Section 3.1.4)
Calculate: Cold Cleaner Emissions Estimate
450 = Gross cold cleaning solvent consumption
- 25 = for wiping losses
- 25 = CND losses
400 = Cold cleaner emissions if all WSD evaporates
- 20 = controlled emissions due to proper waste solvent disposal
380 (+100) Gg/yr = estimated emissions from cold cleaners-1974
*Gg = 103 metric tons
B-3
-------
B.2.2 Emission Rate Per Cold Cleaner
Given: (a) 880,000 Maintenance cold cleaners (1974)
340,000 Manufacturing cold cleaners (1974)
1.22 x 106 Total cold cleaners 1974
(b) A manufacturing cold cleaner has twice the average emission
of a maintenance cold cleaner.
Calculate: Individual cold cleaner emission rates
(a) 380 (±100) Gg/yr n 0, ,.n no. M ,
1.22Vlift units = °'31 (i-°-08) M9^r Per urnt
= 660 Ib/yr per unit
% 100 (+20) gal/yr per unit
(b) IF: X = average maintenance cold cleaner emission
2X = average manufacturing cold cleaner emission
Ta-j = national maintenance cold cleaner emissions
Ta2 = national manufacturing cold cleaner emissions
THEN: X x 880 (xlO3) = Ta]
2X x 340 (xl()3) = Ta2
Ta1 + Ta2 = 380 (+J00)(xl03 metric ton/yr) in 1974
AND: Ta1 =215 (xlO3 metric ton/yr)
Ta2 = 165 (xlO3 metric ton/yr)
X =0,24 metric ton/yr = (490 Ib/yr)
2X = 0.48 metric ton/yr = (980 Ib/yr)
(c) "Safety Kleen" maintenance cold cleaners and others:
Let X = average emission from a Safety Kleen cleaner
X = average emission from other maintenance cold cleaners
Then:
X . = 24 x 10 metric ton/yr _ 0.17 metric ton/sk cleaner-
SK T40.000 ~ 38f) lb/vr
Xo =0.24 metric ton= 530 Ib/yr
B-4
-------
B.2.3 -Projected Emission Reductions*
A. Cold Cleaner System A
Assumptions & Estimations:
1. Average typical cold cleaner emits about 0,3 metric tons/yr.
2. An average of 55% of cold cleaning emissions is due to
evaporation of waste solvent. This could be reduced to
with excellent compliance
30% with average compliance
40% with poor compliance.
3. 45% of the emissions occur directly from the cold cleaner.
20% is through bath evaporation (including agitated & spray
evaporation) and 25% is through carry out. Cover closing can reduce
bath evaporation from 20% to 4% with excellent compliance
9% with average compliance
18% with poor compliance.
Drainage practice could reduce carry-out from
25% to 5% with excellent compliance
11% with average compliance
18% with ooor compliance.
Conclusion:
With excellent compliance system A could reduce emissions by 100-10-4-5=
80%. With average compliance, emissions could be reduced by 100-30-9-11=
50%, With poor compliance, emissions could be reduced by 100-40-14-18=
28%,
*The previous and the following projected estimates represent the best engineering
iudqement that can be made given the limited data base. These estimates are
not"to be interpreted as test data; thus, a wide range is given for most
estimates.
B-5
-------
B. ^old Cleaner System B
Note that excellent compliance would not vary much between systems
A and B,
Assumptions & Estimations—same as for system A except:
1, Mechanically assisted covers, the "major control device" and
spray specifications and agitation restrictions are estimated to
reduce bath evaporation from 20% to 2% with excellent compliance
6% with average compliance
10% with poor compliance
Conclusion:
With excellent compliance system B could reduce emissions by 100-10-25=
83%, With average compliance, emissions could be reduced by 100-30-6-11=
53%. With poor compliance, emissions could be reduced by 100-40-10-18=
32%.
C, Cold Cleaners Using High Volatility Solvent
Recommended controls would effect higher emission reductions on
units using highly volatile solvents. It is estimated that with average
compliance emission reduction would increase to 55% for system A and to
69% for system B.
Note:Table 3-14 in the Dow Report estimates emissions from a.typical,
maintenance cold cleaner, Although the overall emission rates are on the high
side, the percentage of emissions from waste solvent evaporation (refilling)
carry-out and bath evaporation calculate to 58%, 28%, and 16% respectively. '
This compares reasonably with the previous estimates of 55%, 25% and 20% for
all types of cold cleaners, (considering that manufacturing, cold cleaners
tend to have a higher proportion of bath evaporation than do maintenance
cleaners).
B-6
-------
B.3 OPEN TOP VAPOR DEGREASER EMISSIONS
B.3.1 National Open Top Vapor Degreaser Emissions (1974)
Gross vapor degreasing solvent consumption is 275 (+25) Gg*/yr.
Approximately 200 (+20) Gg/yr of this is from Open Top Vapor Degreasing (OTVD)
and 75 Gg/yr is from Conveyorized Vapor Degreasing (CVD). These estimates are
similar to previous estimates that CVD emit about 65 Gg/yr and OTVD, 210 Gg/yr.
B.3.2 Emissions Per Average Unit
1. If there are 21,000 OTVD (1974), an average OTVD would emit about
200 (+20) Gg/yr ^ 21,000 = 9.5 MT/yr.
2 2
2. If an average OTVD has an open area 18 (+3) ft = 1.67 (+0.3) m
p
then emission per area would average 5,7 MT/yr-m (These averages probably
are within +_ 25 percent accuracy.)
B.3.3 Projected Emission Reductions
Estimates have been made of the total control efficiencies (n+), the control
efficiencies from improved operating practices (r^) and control efficiencies
from control equipment (nfi) for control systems A and B.
no
ne
Approx. n+
System A
Compliance
poor average
15 25
20 30
32 47
30 45
excellent
35
40
61
60
System B
Compliance
poor average
20 30
30 45
44 62
45 60
excellent
40
60
76
75
Note: (1 - n+) = 0 - -n0) (1 -
*Gg = 10J metric tons
B-7
-------
2. Given 9.5 mT/yr per average OTVD,
Emission Per
uncontrolled Emission per controlled unit
unit poor average excellent
System A
System B
9.5
9.5
6.5
5.3
5.2
3.8
3.7
2.4
B-8
-------
B.4 CONVEYORIZED DEGREASER EMISSIONS
B.4.1 National Conveyorized Degreaser Emissions (1974)
Given: (a) Emissions from conveyorized vapor degreasers (CVD) is
75 Gg*/yr.
(b) It is estimated that between 25 to 35 percent of the
conveyorized degreasers are Conveyorized Non-Boiling Degreasers
(CND),8 This estimate appears somewhat high, thus choose 25 percent
which is on the lower end of the range,
Calculate:
(a) CND emit 25 Gg/yr
(b) CVD emit 75 Gg/yr
(c) Total conveyorized degreaser emission are 100 Gg/yr.
B.4,2 Emissions Per Average Unit
1. Estimate that there are about 3170 CVD and 530 CND nationally in
1974.
9,10
2 An average emission rate for a CVD would be 75.000 Mg/yr _ 03 7 MT/vr
3,170 units ' IJ
3. Average emission from a CND would be 25,000 = 47^ MT/yr.
3O\y
B.4.3 Projected Emission Reductions
Estimates have been made of total control efficiencies (n+), the control
efficiencies from improved operating practices (n0) and the control efficiencies
from control equipment for control systems A and B.
Control
Efficiencies
(n) (*)
Improved nQ
operation
Control n
equipment
Total n+
approximated
System A
Compliance:
poor average excellent
20 25 30
- - -
20 25 30
- - -
System B
Compliance:
poor avg. excl .
20
40
52
50
25 30
50 60
62.5 72
60 70
Note: (l-n+) = 0~O 0-np)
^ U C n rt
*Gg = 10 MT
-------
2. Emission control for typical units:
Conveyorized Vapor Deg.
Con. Non-boiling Deg.
••^
Average CD
Emission rate (MT/yr)
Uncontrolled
24
^48
27
Controlled with
System A
18. (17 to 19)
36 (34 to 38)
20 (19 to 21)
Controlled with
System B
9 (7 to 11)
18 (13 to 23)
10 (7.5 to 13)
B-10
-------
B.5 DECREASING WASTE SOLVENT DISPOSAL
It has been estimated that 280 (±80) thousand metric tons/yr of waste
solvent are disposed of by the solvent metal cleaning industry in 1974. The
calculation is based on the following assumptions and estimates.*
Assumption^
1. Percent virgin solvent that becomes waste solvent for each category
of degreasers. (EPA and Dow Chemical estimates)
a. Degreasing industry collectively 30% to 50%
b. Cold cleaners collectively 45% tO 70%
c. Maintenance cold cleaners 50% to 75%
d. Manufacturing cold cleaners 40% to 60%
e. Conveyorized vapor degreasers 10% to 20%
f. Open top vapor degreasers 20% to 25%
2. Virgin solvent consumption. (EPA estimates)
a. Cold cleaners (excluding 10% as wiping losses)
Maintenance (56%) 215,000 Mt/yr
Manufacturing (44%)* 165,000 Mt/yr
b. Open top vapor degreasers 200,000 Mt/yr
c. Conveyorized degreasers (vapor and cold) 100,000 Mt/yr
Waste Solvent Estimates
1. Maintenance cold cleaners - 134,000 Mt/yr
(or 215,000 x .625 = 134,000 Mt/yr)
2. Manufacturing cold cleaners = 83,000 Mt/yr
(165,000 x .50)
3. Conveyorized vapor degreasers = 15,000 Mt/yr
(100,000 x .15)
*The accuracy of the estimates is not expected to be better than + 30%,
B-ll
-------
4. Open top vapor degreasers = 45,000 Mt/yr
(200,000 x .225)
Total waste solvent = 277,OOOMt/yr(+85,000 Mt/yr)
B-12
-------
B.6 CALCULATIONS RELATING TO ADVERSE ENVIRONMENTAL EFFECTS
B.6.1 Increased Boiler Emissions-Computation
The objective is to determine the magnitude of increased boiler emissions
caused by use of a carbon adsorber. The carbon adsorber generally has the
highest energy consumption compared to that of other control devices. A
typical carbon adsorber could be a Vic #536 AD. According to the J. L. Thompson
test report by Dow, the steam usage may be 113 Ib. per desorption cycle which
converts to 113,000 Btu/cycle. Taking an average of two desorption .cycles
per day, the consumption becomes about 225,000 Btu/day or 28,000 Btu/hr.
Assume that high sulfur fuel oil were to be used to fire the boiler. Take
residual fuel oil with 2% sulfur content. According to "Compilation of Air
Pollution Emission Factors" (AP 42) such fuel combustion would emit the following
pollutants per 103 gal. fuel oil: 310 Ib SO,,, 23 Ib particulates, 60 Ib NOX,
4 Ib CO and 3 Ib HC (hydrocarbons).
Relate the emissions to an hourly emission rate. To produce 28,000 Btu/hr
at 75% conversion efficiency would require 37,000 Btu/hr of fuel. Choosing
#5 fuel oil, we have 148,000 Btu/gal. Thus,; increase* fuel consumption would
be about 0.25 gal/hr.* Increased pollutant emission would then be 0.08 Ib/hr
(0.036 kg/hr) S02, 0.005 Ib/hr (0.002 kg/hr) particulates, 0.008 Ib/hr
(0.00035 kg/hr) NOX, 0.0005 Ib/hr (0.0002 kg/hr) CO and 0.0004 Ib/hr
(0.0002 kg/hr) HC.
Compare the increased emissions to the emission reduction caused by the
carbon adsorber. A typical adsorber system that is properly designed and
maintained may save 50 gal/wk * 15 Ib/hr = 6.8 kg/hr. Thus, the total increased
boiler emissions equals about 0.6% of the emission reduction caused by a typical
carbon adsorber.
*37.000 Btu/hr~~T Q 25 1/hr of fuel
148,000 Btu/ga! u<^ y
B-13
-------
B,6,2 Stabilizers in Chlorinated Solvents
Fish
Trichloroethylene
Epichlorohydrin
Butylene Oxide
Glycidol
Acrylonitrile
Diisopropylamine
Triethylamine
Ethyl Acetate
Diisofautylene
Thymol
N -Methyl Pyrrole
Acetaldehyde
Dimethyl
Hydrazone
Tetrahydrofuran
Sec. Butanol
N-Propanol
1,1,1 Trichloroethane
1,2 Butylene Oxide
Butylene
Nitroethane
Nitromethane
3-Methoxy
Propronitrile
1,3-Dioxolane
1 ,4-Dioxane
N -Me thy! -Pyrrole
Toluene
Methyl Ethyl
Ketone
Isobutyl Alcohol
Tertiary Butanol
Sec. Butanol
Acrylonitrile
Acetonitrile
Isopropyl Nitrate
Tertiary Amy!
Al cohol
1 ,3,5 Trioxane
2 Methyl -3-Butynol -
2
JSl. = slightly and s.
TDL - oral human
Solubility
in water
x \ -
6
25-58
si.s*
5.5
9
SI.S
sTs
100
13
S
10
non-mi sc.
10
100
100
S
27-37
10
^20
13
100
partially
S
= soluable
Toxicity BOD-20 Boiling Point
ppm x % of Theory °C
15
20
30
>1QO
1
>100
>10Q,
1900*
>100
1000
300
>100
3100+
>1000
>100
>100
>100
14**
Concentration
nrnmri fns\ ft sv u.«t 1
50
50-60
0
80
0
45
85
60
115
30
0
30
60 112
75 80
80
£120
85
75
82
115
giving 50% fatality to rat:
B-14
-------
% Fish
Solubility Toxictty
in water x x ppm
Methyl ene Chloride
Propylene Oxide
Butyl ene Oxide
Amy! ene
Cyclohexane
Methyl ene Chloride
Perch! oroethylene
Thymol
4-Methyl
Morphol ine
P-Tertiary Amy!
Phenol
3-N-Propoxy
Propionitrile
Isopropyl Alcohol
Epichlorohydrin
Diallylamine
40-60
Sl.S
0
2
Sl.S
100
partially
100
6
>100
30
21001
BQD-2Q Boiling Point
of Theory v °C
75
5
34
Sl.S
100
partially
100
6
2700f
3100f
>100 80
15 50
115
82
112
Estimated Stabilizer Emissions into Sewer
Approximate
Stabilizers in Solubility
Solvent blend %
gal/wk
Sewer Emission Rate
m3/wk
Worst Case:
Average Case:
_—_——————
Typical Emission Control:
2%
0.2
0.004
0.0008
Atmospheric Emission Reduction
50 gal/wk
0.2 m°/wk
B-15
54
-------
B.6.3 UTILITIES CONSUMPTION OF CARBON ADSORBERS
Reference to
Dow Report
Appendix:
C-10
C-8
C-9
C-ll
Average
Test Site
Vic Manuf. Co.
Super Radiator Co.
J. L. Thompson Co.
W. Electric Co.
Model
Adsorber
Vic #
572AD
554AD
536AD
536AD
Ventilation Rate
Both Beds Adsorbing
(cfm)
5500
£3000
940
£1300
2700
Solvent
Recovered
(qal/wk)
70
*
i
25 to 50*
85
Water
Consumption
(103 gal/yr)
630
1380
230
1380
900
Steam
Consumption
(106 Btu/yr)
310
380
54
520
320
Electricity
(103 kw)
30
30
\
4'
13
19
*Defective control systems
B-16
-------
B6 4 Fuei_Costj>fJMS!!2ti°5-^^
Assume a ventilation rate of 50 cubic ft/minute/ft2 of open top area,
an average tan. area of 6 f t2 , 8 hours of operation per weekday and 2 1/2
dollars/million BTU fuel cost. Using an air density of 0.075 Ibs/ft , a
specific heat of 0.25 BTU/1bs°F for air, and a maxin™ temperature of 800°F,
,„ approximate annual fuel cost would be about $1200/year, as su^arized
below. 6
Exhaust volume . 300 cfm x 60 min/hr x 8 hr/day x 240 day/yr - 35 x 10
ffrVyr
- — ' fesVoer5 Wft X '
Annual fuel cost - 485 x vfi BTU/yr x 2.50 $/!# BTU - 1215 5; 1200 $/yr
B-17
-------
B.7 REFERENCES
1. Information provided by Tom Hoogheem, Monsanto Research Corp., Dayton,
Ohio, by telephone to J. C, Bellinger, EPA, on December ] and 6, 1976.
2. Surprenant, K. S. and Richards, D. W. of Dow Chemical Company, "Study
to Support New Source Performance Standards for Solvent Metal Cleaning
Operations," 2 vol., prepared for Emission Standards and Engineering
Division (ESED), under Contract # 68-02-1329, Task Order #9, June 30, 1976,
PP. 7-3.
3. Ibid.
4. Kearney, T. J,, Detrex Chemical Ind., letter to J. C. Bollinger, EPA,
January 9, 1976.
5. Information provided by J. S. Gunnin, Shell Chemical Co., Houston, by
telephone to J, C, Bollinger, EPA, September 16, 1976.
6. Op, Cit., Surprenant, K. S., pp. 7-3.
7. Bollinger, John C., "Trip Report - ASTM, Consultant and Two Waste Solvent
Plants," memo to David R. Patrick reporting on trip to ASTM D-26 meeting
of January 26, 1977.
8. Bollinger, J. C., "Maximum Impact of NSPS on 1985 National Degreasing
Emissions," December 1975.
9. Ibid.
10. Surprenant, K. S., Op. Cit.
11. Ibid. pp. 7-3.
B-18
-------
TECHNICAL REF'ORT DATA
(Please read Instructions on tlir reverse before completing)
REPOR r NO. 2.
PA 450/2-77-022 |_
T ITLE AND SUBTITLE
Control of Volatile Organic Emissions from
lOlvent Metal Cleaning
AUTHOR(S)
lohn C. Bellinger*
effrey L. Shumaker, ESED
PERFORMING ORGANIZATION NAME AND ADDRESS
. S. Environmental Protection Agency
)ffice of Air and Waste Management
)ffice of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
. SPONSORING AGENCY NAME AND ADDRESS
3. RECIPIENT'S ACCESSION- NO.
5. REPORT DATE
November 1977
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
OAQPS 1.2-079
10. PRCIGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
^SUPPLEMENTARY NOTES
*No longer with EPA
This report provides the necessary guidance to control emissions of
volatile organic compounds (VOC) from solvent metal cleaning operations.
Emissions are characterized and reasonably available control technology'(RACT)
is defined for each of the three major categories of solvent metal cleaners-
:old cleaners, open top vapor degreasers, and conveyorized degreasers.
Information on the cost of control, environmental impact and enforcement
issues is also included.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Mr Pollution
Solvent Metal Cleaning (Degreasing)
Emissions and Controls
Regulatory Guidance
b.IDENTIFIERS/OPEN ENDED TERMS
Air Pollution Controls
Stationary Sources
Organic Vapors
Degreasing
COSATI 1-icld/Group
iUTION STATEMENT
19 SECURITY CLASS (Tim Report)
Unclassified
21 NO. OF PAGES
203
Unlimi ted
2O. SECURITY CLASS (This pagcf
Unclassified
22 PRICE
E!PA Form 2220-1 (9 73)
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