LOCATING AND ESTIMATING AIR
EMISSIONS FROM SOURCES OF
VINYLIDENE '."'CHLORIDE
ENVIRONMENTAL PROTECTION AGENCY
DRAFT REPORT
SEPTEMBER, 1984
NOTE: THIS REPORT IS A DRAFT PREPARED FOR EXTERNAL REVIEW ONLY.
DO NOT QUOTE OR CITE
This document is a preliminary draft. It has not been subjected to the
Agency's required peer and policy review and therefore does not necessarily
reflect the views of the Agency, and official endorsement should not be
inferred.
EPA
450/
1984.2
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-------
,. too
O
y
CONTENTS
r\
,,.
^
............. 51
5 . Source Test Procedures ...... . .......... . ....... . ...... 52
References ........ ................... « .................... • ...... 54
Appendix - Fugitive Emission Calculations for Vinylidene
Chloride Production ........................................... A-l
References for Appendix ................................. • ..... • • A-8
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CD
CO
tu
J1
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FIGURES
Number page
1 Chemical Use Tree for Vinylidene Chloride 8
2 Basic Operations That May Be Used For Vinylidene
Chloride Production from 1,1,2-Trichloroethane 12
3 Basic Operations That May Be Used In Perchloro-
ethylene and Trichloroethylene Production by
Chlorination of Ethylene Dichloride 19
4 Basic Operations That May Be Used in Perchloroethylene
and Trichloroethylene Production by Oxychlorination
of Ethylene Dichloride 22
5 Basic Operations That May Be Used in the Production
of 1,1,1-Trichloroethane from Ethane... * 29
6 Basic Reactions Involved in the Polymerization of
Vinylidene Chloride with a Comonomer 33
7 Basic Operations That May Be Used for the Production
of Vinylidene Chloride Copolymers 36
8 Basic Operations That May Be Used in the Coating of
Cellophane with High-VDC Copolymer 44
9 Method 23 Sampling Train 53
iv
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TABLES
Number Page
1 Physical and Chemical Properties of Vinylidene
Chloride 6
2 Controlled and Uncontrolled Vinylidene Chloride
Emission Factors for a Hypothetical Vinylidene
Chloride Production Facility 14
3 Production of Vinylidene Chloride 17
4 Controlled and Uncontrolled Vinylidene Chloride
Emissions for Hypothetical Perchloroethylene/
Trichloroethylene Production Processes 23
_ *
5 Facilities Producing Perchloroethylene and/or
Trichloroethylene 25
6 Facilities Producing 1,1,1-Trichlorethane..., 31
7 Vinylidene Chloride Copolymers, Production Methods,
and Applications 34
8 Controlled Vinylidene Chloride Emissions for a
Hypothetical Vinylidene Chloride Polymerization
Plant 39
9 Potential Emission Controls for Polymer Plants 40
10 Facilities Producing Polyvinylidene Chloride 41
11 Estimates of Uncontrolled Emission Factors from
High-VDC Copolymer Fabrication Processes 47
12 Facilities Fabricating High Vinylidene Chloride
Copolymers 49
A-l Estimated Process Line Composition in VDC Production... A-3
A-2 VDC Emissions from Valves and Pumps A-5
A-3 VDC Emissions from Relief Valves A-6
A-4 Fugitive Emission Controls and Controlled Emission
Rates A-7
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SECTION 1
PURPOSE OF DOCUMENT
EPA, States and local air pollution control agencies are becoming
increasingly aware of the presence of substances in the ambient air that
may be toxic at certain concentrations. This awareness, in turn, has led
to attempts to identify source/receptor relationships for these substances
and.to develop control programs to regulate emissions. Unfortunately,
very little information is available on the ambient air concentrations of
these substances or on the sources that may be discharging them to the
atmosphere.
To assist groups interested in inventorying air emissions of various
potentially toxic substances, EPA is preparing a series of documents such "
as this that compiles available information on sources and emissions of
these substances. This document specifically deals with vinylidene chloride.
Its intended audience includes Federal, State and local air pollution
personnel and others who are interested in locating potential emitters
of vinylidene chloride and making gross estimates of air emissions therefrom.
Because of the limited amounts of data available on vinylidene chloride
emissions, and since the configuration of many sources will not be the same
as those described herein, this document is best used as a primer to inform
air pollution personnel about 1) the types of sources that may emit vinylidene
chloride, 2) process variations and release points that may be expected
within these sources, and 3) available emissions information indicating
the potential for vinylidene chloride to be released into the air from
each operation.
The reader is strongly cautioned against using the emissions
information contained in this document to try to develop an exact assessment
of emissions from any particular facility. Since insufficient data are
available to develop statistical estimates of the accuracy of these emission
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factors, no estimate can be made of the-error that could result when these
factors are used to calculate emissions from any given facility. It is possible,
in some extreme cases, that orders-of-magnitude differences could result
between actual and calculated emissions, depending on differences in source
configurations, control equipment and operating practices. Thus, in situations
where an accurate assessment of vinylidene chloride emissions is necessary,
source-specific information should be obtained to confirm the existence of
particular emitting operations, the types and effectiveness of control measures,
and the impact of operating practices. A source test and/or material balance
should be considered as the best means to determine air emissions directly
from an operation.
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SECTION 2
OVERVIEW OF DOCUMENT CONTENTS
As noted in Section 1, the purpose of this document is to assist
Federal, State and local air pollution control agencies and others who are
interested in locating potential air emitters of vinylidene chloride and
making gross estimates of air emissions therefrom. Because of the
limited background data available, the information summarized in this
document does not and should not be assumed to represent the source
configuration or emissions associated with any particular facility.
This section provides an overview of the contents of this document.
It briefly outlines the nature, extent and format of the material presented
in the remaining sections of this report.
SecftLon 3 of this document provides a brief summary of the physical
and chemical characteristics of vinylidene chloride, its commonly occurring
forms and an overview of its production and uses. A chemical use tree
summarizes the quantities of vinylidene chloride consumed in various end
use categories in the United States. This background section may be
useful to someone who needs to develop a general perspective on the
nature of the substance and where it is manufactured and consumed.
Section 4 of this document focuses on major industrial source
categories that may discharge vinylidene chloride air emissions. This
section discusses the production of vinylidene chloride, its use as an
industrial feedstock, and processes which produce vinylidene chloride as
a byproduct. For each major industrial source category described in
Section 4, example process descriptions and flow diagrams are given,
potential emission points are identified, and available emission factor
estimates are presented that show the potential for vinylidene chloride
emissions before and after controls employed by industry. Individual companies
are named that are reported to be involved with either the production or use
of vinylidene chloride, based primarily on trade publications.
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The final section of this document summarizes available procedures
for source sampling and analysis of vinylidene chloride. Details are
not prescribed nor is any EPA endorsement given or implied to any of
these sampling and analysis procedures. At this time, EPA generally has
not evaluated these methods. Consequently, this document merely provides
an overview of applicable source sampling procedures, citing references
for those interested in conducting source tests.
This document does not contain any discussion of health or other
environmental effects of vinylidene chloride, nor does it include any
discussion of ambient air levels or ambient air monitoring techniques.
Comments on the contents or usefulness of this document are welcomed,
as is any information on process descriptions, operating practices,
control measures and emissions information that would enable EPA to
improve its contents. All comments should be sent to:
Chief, Source Analysis Section (MD-14)
Air Management Technology Branch
U.S. Environmental Protection Agency'
Research Triangle Park, N.C. 27711
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SECTION 3
BACKGROUND
NATURE OF POLLUTANT
Vinylidene chloride (VDC) is a clear liquid with low viscosity at
room temperature. It has a sweet odor similar to other chlorinated
hydrocarbons, which can be detected at concentrations of about 500 ppm.
The chemical name for vinylidene chloride is 1,1-dichloroethylene, and its
structure is as illustrated below:
Cl X.
>=<
Cl ^H
Vinylidene chloride is practically insoluble in water, but is soluble in
most other polar and nonpolar solvents. It is very soluble in chloroform
and ether, and is soluble in benzene, acetone, and ethanol. Chemical and
1 2
physical properties of VDC are summarized in Table 1. '
In the presence of air or oxygen, pure vinylidene chloride can form
a peroxide compound that is violently explosive. The peroxide also
initiates polymerization of the bulk VDC. Commercial grades of VDC
typically contain about 200 ppm of hydroquinone monomethyl ether (MEHQ)
inhibitor, which prevents the formation of peroxide and spontaneous
polymerization. Other impurities in commercial grade vinylidene chloride
include trans-l,2-dichloroethylene (900 ppm), vinyl chloride (850 ppm),
1,1,1-trichloroethane (150 ppm), cis-l,2-dichloroethylene (10 ppm),
1,1-dichloroethane (<10 ppm), ethylene chloride (<10 ppm), and
trichloroethylene (<10 ppm).
1,2
Vinylidene chloride liquid is very volatile, with a vapor pressure of
660 mm Hg at room temperature, and the vapor burns readily when ignited. The
flash point of the liquid is about -15°C and the explosive limits of the
vapor are 7 to 16 percent. The decomposition products of VDC exposed to
oxygen include formaldehyde, phosgene, and hydrogen chloride.
1,2
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TABLE 1. PHYSICAL AND CHEMICAL PROPERTIES OF VINYLIDENE CHLORIDE
Synonyms: VDC, 1,1-dichloroethylene, 1,1
Chemical formula
CAS registry number
Molecular weight, g/mole
Density (20°C liquid), g/cm
Boiling point, °C
Melting point, °C
Flash point, °C
open cup
closed cup
Autoignition temperature in air, °C
Flammable limits in air, volume percent
Latent heats, kJ/mole
vaporization (at boiling point)
fusion (at freezing point)
Heat of combustion (25°C liquid), kJ/mole
Heat of polymerization (25°C), kJ/mole
Heat of formation, kJ/mole
liquid
vapor
Heat capacity, J/mole-K
liquid (25°C)
vapor (25°C)
Critical properties
Temperature, °C
Pressure, MPa
Volume, cm-Vmole
Vapor pressure, kPa
0°C
10 °C
20°C
30°C
Water solubilities at 20°C, g/lOOg
Vinylidene chloride in water
Water in vinylidene chloride
Dielectric constant (16°C liquid)
Viscosity (20°C), centipoise
,-dichloroethene
C12C - CH2
75-35-4 .
96.9
1.2137
31.56
-122.56
-16
-28
513a
5.6-16.0
26.48
6.51
1095.9
-75.3
-25.1
1.26
111.27
67.03
280.8
5.21
218
28.92
44.54
66.34
95.91
0.25
0.035
4.67
0.33
stabilized by MEHQ.
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The residence time of vinylidene chloride in the atmosphere is
about 23 hours, where residence time is defined as the time required for
the concen tration to decay to 1/e (i.e., 372) of its original value.
The major mechanism for destruction of VDC in the atmosphere is reaction
with hydroxyl radicals. The principal reaction products are formic
acid, carbon monoxide, chloroacetyl chloride, hydrogen chloride, phosgene,
3 A
and formaldehyde. '
Vinylidene chloride can be polymerized to produce polyvinylidene
chloride (PVDC) polymer chains made up of monomer units joined head to
tail:
H- Cl H Cl H Cl
I I I II I
—c-c-c-c-c-c —
i I II I I
H Cl H Cl H Cl
Vinylidene chloride can also be polymerized with other monomers to
produce polyvinylidene chloride copolymers.
OVERVIEW OF PRODUCTION AND USE
Vinylidene chloride was first used in the late 1930's by Dow Chemical
Company. VDC is produced commercially by the dehydrochlorination of
1,1,2-trichloroethane with lime or caustic. It may also be recovered
as a byproduct of chlorination and oxychlorination reactions to produce
other compounds. Today, production of VDC in the United States exceeds
2
90,700 megagrams (Mg) per year. Exact production figures are not
available because the producers of VDC consider these to be proprietary.
Figure 1 gives a chemical use tree summarizing the production and
2 3 5-7
use of VDC. ' ' The main use of VDC is in the production of VDC
copolymers. About 68,000 Mg of VDC is consumed annually in the production
2
of polymers containing VDC. In the United States, the generic term
"Saran" is used to refer to high VDC-content polymers. Saran formerly
was a trademark of the Dow Chemical Company and is still a Dow trademark
in other countries. PVDC homopolymer (Saran A) is difficult to fabricate
and for this reason is not used. However, copolymers .of vinylidene
chloride with vinyl chloride (Saran B), alkyl acrylates (Saran C), and
acrylonitrile (Saran F) are widely used. Polymers containing VDC are
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Cl
Cl
H Cl
KaOH \ /
a — w — v — i»i —'•'—' n v ^ ncux » u *
/ \ 2 /
EH H
l.:,2-triehloro- VDC
ethane
Cl Cl
% *
., — - HCl » C =• C
.x^ 1 \
.Xcl H Cl
Cl Cl X^ 2
\ / trichloro-
E — C — C — H ethylene
H H "- — ^ Cl Cl Cl
• * ^^^\2 \ /
•thylene 0^ •- HCl • C * C
cichloride 2 / \
H Cl
VDC
OSES
H Cl
\ • / other
/ \ Bononer
H Cl
VOC
H Cl 0
\ t 2
•Ht^HI^ C S C * ~~
1 \ Cl
H Cl 2
\
Cl
Cl Cl
\f
/
* C » C
/ \
Cl Cl
perchloro-
ethylene
Cl. Cl
\ /
* C = C
/ \
Cl Cl
VDC
P800UCTIOS
* including M
VOC
byproducts
* including -~—J
VOC
Saron films
^
High-VDC ^x^" Saran coatings
heat copoly»ero
initiator Low-VOC
copolymars _^^_^ Flame retardent rug backing
Cl Cl
\ /
H — C — C
/ ^j.
H 0
chloroacetyl
chloride
Synthetic fibers
Interned! ate
in the
* production
of -tear gas and
Pharmaceuticals
Figure 1. Chemical use tree for vinylidene chloride.
-------
resistant to photodegradation and chemical attack, and, because of their
high density and crystallinity, they are impermeable to a wide range of
gases. The low permeability of VDC copolymers to water and oxygen is
the main reason for the commercial importance of vinylidene chloride.
2,8
In addition to the production of Saran. polymers, VDC is also used as a
9
chemical intermediate in the production of chloroacetyl chloride. Chloroacetyl
chloride is a chemical intermediate in the production of pharmaceutical products
and tear gas. Formerly, a major use of VDC (about 60 Mg/yr) was as an
intermediate in the production of 1,1,1-trichloroethane. However, the VDC-based
process for 1,1,1-trichloroethane was only used at one plant, and was replaced
in the late 1970's by a vinyl chloride based process.
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SECTION 4
VINYLIDENE CHLORIDE EMISSION SOURCES
This section discusses vinylidene chloride emissions from processes
where the chemical is produced, processes where it is used as a chemical
intermediate, and processes where it is produced as a byproduct. Process
and emissions data are presented for each source category.
The following industrial processes have been identified as potential
sources of VDC emissions:
o vinylidene chloride production,
o perchloroethylene and trichloroethylene production,
o 1,1,1-trichloroethane production,
o - VDC polymerization,
o use of VDC in specialty chemical*production,
o VDC copolymer fabrication, and
o volatilization from waste treatment, storage, and disposal..
VDC is a byproduct of perchloroethylene.and trichloroethylene production
and of 1,1,1-trichloroethane production from ethane.
VINYLIDENE CHLORIDE PRODUCTION
Vinylidene chloride is produced domestically by the dehydrochlorination
of 1,1,2-trichloroethane with sodium hydroxide.
2,11
Three plants in the U.S.
produce VDC; each of these produces a variety of other chlorinated hydrocarbons
by a variety of processes. The raw material 1,1,2-trichloroethane is
produced as a coproduct in the chlorination and oxychlorination of ethane,
ethylene, and ethylene dichloride (1,2-dichloroethane) to produce chlorinated
12
species
At the plants using the 1,1,2-trichloroethane dehydrochlori-
nation process, additional VDC may also be recovered as a byproduct of
12
various chlorination and oxychlorination processes. These processes are
discussed in later sections.
10
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Process Description
The reaction for the dehydrochlorination of 1,1,2-trichloroethane
to produce VDC is as follows:
Cl-
H
\
H
Cl
B
-H
Cl
1,1,2-tri
chloroethane
NaOH
sodium
hydroxide
H
NaCl
H20
Cl
VDC
The reaction is carried out with 2 to 10 percent excess caustic with
product yields ranging from 85 to 90 percent. Basic operations that
may be used in the production of VDC from 1,1,2-trichloroethane are
shown in Figure 2. Concentrated sodium hydroxide (Stream 1) is diluted
with water (Stream 2) to about 5 to 10 weight percent and is mixed with
the 1,1,2-trichloroethane feed (Stream 3) and fed (Stream 4) to the
dehydrochlorination reactor. The reaction is carried out in the liquid
phase at 'about 100°C without catalyst. Because the aqueous and organic
reactants are not miscible, the reaction is carried out in a liquid
dispersion. The dehydrochlorination reactor is continuously purged with
nitrogen (Stream 5) to prevent the accumulation of monochloroacetylene
impurity in the product VDC. The nitrogen is discharged from Vent A.
The VDC-containing product from the dehydrochlorination reactor
(Stream 6) is separated in a decanter into an aqueous phase (Stream 7)
and an organic phase (Stream 8). The aqueous phase, comprising a sodium
hydroxide/sodium chloride solution, is divided. One fraction (Stream 9)
is recycled (Stream 4) to the hydrochlorination reactor, and the other
fraction (Stream 10) is steam stripped to remove organics and discharged
to a wastewater treatment system (Discharge F).
* The organics from the aqueous phase (Stream 11) are combined with
the organic phase from the decanter (Stream 8). The combined organics
(Stream 12) are fed to a drying column, where residual water is removed
as a bottoms stream (Stream 13). The water removed from the drying
column is fed to the steam stripper with the aqueous stream from the
product decanter (Stream 10).
11
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The organic stream from the drying column (Stream 14) is fed to a
distillation column, which removes unreacted 1,1,2-trichloroethane as
overheads (Stream 15). The unreacted trichloroethane is recycled to the
dehydrochlorination reactor. Purified VDC product, removed as bottoms from
the finishing column (Stream 16), is used onsite or stored in pressurized
tanks before being shipped to users.- •
Emissions
Uncontrolled VDC emission factors for VDC production are given in
Table 2. The table also lists potentially applicable control techniques and
associated controlled emission factors. The emission factors were developed
based on published data for individual plants and for general processing
techniques. Because of variation in process design, age of equipment, and
other process parameters, actual emissions vary for each plant.
Process Vent. Emissions—
Process vents which are sources of VDC emissions include the reactor
nitrogen purge vent (Vent A, Figure 2) and the distillation column vents
(Vents B, Figure 2). Uncontrolled VDC emission factors are estimated at
6.2 kilograms VDC per megagratn VDC produced (kg/Mg) for the reactor vent, and
13
0.7 kg/Mg for the distillation vents.
Emissions from the reactor vent can be controlled by incineration with
14 15
an efficiency of about 98 percent or higher. ' Incineration destruction
efficiency varies with emission stream properties and incinerator operating
parameters. The 98 percent efficiency level is based on incineration of a
compound which is difficult to destroy at 870°C, and with a residence time of
0.75 seconds. The emission reduction may be greater than 98 percent for
incineration of VDC with these operating parameters, and would also increase
at higher temperatures and longer residence times. A 98 percent reduction
of reactor vent emissions corresponds to a controlled VDC factor of about
0.12 kg/Mg VDC produced. Controlled reactor vent emissions reported for
specific plants range from 0.063 kg/Mg to 0.090 kg/Mg.
13
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VDC emissions from the distillation column vents can be controlled
either by aqueous scrubbing or by refrigerated vent condensers with an efficiency
14 17
of about 90 percent. ' - As in the case of incineration, the control
efficiency attainable using these techniques is dependent on operating
parameters and emission stream characteristics. A 90 percent reduction of
distillation column vent emissions corresponds to a controlled emission
factor of about 0.07 kg/Mg TOG produced. Controlled VDC emissions reported
for distillation vents at specific plants range from 0.18 kg/Mg to 0.38 kg/Mg.
Storage and Handling Emissions—
Vinylidene chloride emissions result from the storage of VDC product and
intermediates containing VDC (Source D, Figure 2). VDC emissions also occur
where VDC product is loaded to tank cars or trucks. .Insufficient data were
available to estimate uncontrolled emissions of VDC from storage and handling.
Controlled storage and handling emissions of VDC reported for two specific
facilities were about 0.056 kg/Mg VDC produced. The types of controls used
to attain this emission rate are not known. Controls typically used to
reduce storage and handling emissions include pressurized storage tanks and
refrigerated vapor condensers.
Process Fugitive Emissions
Fugitive emissions of VDC and other volatile organic compounds result
from leaks in process valves, pumps, compressors, and pressure relief valves
(Source E, Figure 2). Fugitive emissions from a typical VDC plant were
estimated based on process flow diagrams, process operation data, and •
emission factors developed by EPA for typical process emission sources. The
techniques used to estimate the numbers of various fugitive emission sources
and the total fugitive emission rate are described in detail in the Appendix.
The estimated fugitive emission rate for VDC production from 1,1,2-
trichloroethane is about 0.96 kg VDC/hr. This emission rate is not dependent
on the size of the production plant. However, fugitive emission rates differ
from plant to plant depending on the age of the equipment, the level of
preventative maintenance, and whether a leak detection and elimination program
is used.
15
-------
Secondary Emissions— . - -
Secondary emissions result from the handling and disposal of process
waste streams. In VDC production from 1,1,2-trichloroethane, wastewater from
the VDC production reaction (Source F, Figure 2) is a potential source of
secondary VDC emissions. Data were not available to estimate emissions from
the treatment and disposal of this stream. Figure 2 shows that a wastewater
stripper typically is incorporated as part of the VDC production process to
reduce VDC emissions and for product recovery.
Source Locations
Major vinylidene chloride producers and production locations are listed
in Table 3.18
16
-------
TABLE 3. PRODUCTION OF VINYLIDENE CHLORIDE
18
Manufacturer
Location
Dow Chemical U.S.A.
PPG Industries, Inc.
Chemicals Group
Chemical Division
Freeport, TX
Plaquemine, LA
Lake Charles, LA
Note: This listing is subject to change as market conditions
change, facility ownership changes, plants are closed,
etc. The reader should verify the existance of parti-
cular facilities by consulting current listings and/or
the plants themselves. The level of VDC emissions from
any given facility is a function of variables such as
capacity, throughput and control measures, and should be
determined through direct contacts with plant personnel.
J!
17
-------
PERCHLOROETHYLENE AND TRICHLOROETHYLENE PRODUCTION
Perchloroethylene (PCE) and trichloroethylene (TCE) are produced separately
or as coproducts by either chlorination or oxychlorination of ethylene dichloride
(EDC) or other €„ chlorinated hydrocarbons. A number of byproducts are
produced in each of these reactions, including vinylidene chloride (VDC).
These byproducts may be isolated and refined, recycled to the process, or
discharged in various waste streams. For instance, in a case where VDC is
produced from 1,1,2-trichloroethane at a facility which also produces TCE and
PCE, the VDC byproduct may be recovered and purified by distillation in the
12
VDC finishing section of the 1,1,2-trichloroethane process. Raw material
ratios and reactor conditions determine the relative proportions of PCE, TCE, -
and any byproducts produced.
Process Descriptions
Ethylene Dichloride Chlorination Process—
The overall reactions for the chlorination of EDC to produce TCE and
PCE, are as follows:
Cl
\
H - C
/
H
Cl
C - H
\
' H
EDC
3C1,
Cl
\
Cl
C = C
Cl
Cl
PCE
+ 4HC1 + byproducts
Cl
\
H - C
Cl
- C - H
I \
H
H
2C1,
Cl
\
Cl
/ \
Cl
H
TCE
3HC1
byproducts
VDC is among the byproducts produced in these reactions. Basic operations
19
that may be used in the EDC chlorination process are shown in Figure 3.
18
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Ethylene dichloride (Stream 1) and chlorine (Stream 2) are vaporized and
fed to the reactor. Other chlorinated C~ hydrocarbons or recycled chlorinated
hydrocarbon byproducts may also be fed to the reactor. The chlorination is
carried out at 400° to 450°C, slightly above atmospheric pressure. Hydrogen
chloride byproduct (Stream 3) is removed as an overhead stream from the
chlorinated hydrocarbon mixture (Stream 4) produced in the reactor. The
chlorinated hydrocarbon mixture (Stream 4) is neutralized with sodium hydroxide
19
solution (Stream 5) and dried.
The dried crude product (Stream 7) is separated by a distillation column
into crude TCE (Stream 8) and crude PCE (Stream 9). The crude TCE (Stream 8)
is fed to two columns in series which remove light ends (Stream 10) and heavy
ends (Stream 13). TCE (Stream 12) is taken overhead from the heavy ends
column and sent to TCE storage; the heavy ends (Stream 13) and the light ends
19
(Stream 10) are combined, stored, and recycled.
The crude (Stream 9) fr-om the PCE/TCE separation column is sent to the
PCE column, where PCE (Stream 14) is removed as'an overhead stream to PCE
storage. Bottoms from this column (Stream 15) are sent to a heavy ends
column and separated into heavy ends and tars. Heavy ends (Stream 16) are
19
stored "and recycled, and tars are incinerated.
Ethylene Dichloride Oxychlorination Process—
The overall reactions for the production of perchloroethylene and
trichloroethylene by EDC oxychlorination are as follows: .
Cl Cl
\ /
H - C - C - H
/ \
H H
C1
Cu Cl,
Cl
\
Cl
Cl
I
C
I
Cl
2H2°
+ byproducts
Cl
\
H - C
/
H
Cl
C - H
\
H
+ 1/2C1. + 1/4 0,
CuCl,
Cl
\
. C
Cl
Cl
+ 3/2 H20 '+ byproducts
H
20
-------
The crude product contains 85 to 90 weight percent PCE plus TCE and 10 to
15 weight percent byproduct organics, including VDC. Essentially all byproduct
organics are recovered during purification and are recycled to the reactor.
The process is very flexible, so that the reaction can be directed toward the
production of either PCE or TCE in varying proportions. Side reactions
produce carbon dioxide, hydrogen chloride, and several chlorinated hydrocarbons.
Figure 4 shows basic operations that may be used in oxychlorination.
Ethylene dichloride (Stream 1), chlorine or hydrogen chloride (Stream 2),
and oxygen (Stream 3) are fed in the gas phase to a fluidbed reactor. The
reactor contains a vertical bundle of tubes with boiling liquid o*utside the
tubes .which maintains the reaction temperature at about 425°C. The reactor
is operated at pressure slightly above atmospheric, and the catalyst, which
contains copper chloride, is continuously added to the tube bundle with the
19
crude product.
The reactor product stream (Stream 4) is fed serially to a water cooled
condenser, a refrigerated condenser, and a decanter. The noncondensed inert
gases (Stream 5), consisting of carbon dioxide, hydrogen chloride, nitrogen,
and a small amount of uncondensed chlorinated hydrocarbons, are fed to an
absorber, where hydrogen chloride ±s recovered by absorption in process water
to make byproduct hydrochloric acid (Stream 6). The remaining inert gases
19
are purged (Vent A).
In the decanter, the crude product (Stream 7} is separated from the
aqueous phase and catalyst fines (Stream 8) and sent to the drying column for
removal of dissolved water by azeotropic distillation. The dried crude
product (Stream 10) is separated into crude TCE (Stream 11) and crude PCE
(Stream 12) in a PCE/TCE column. The aqueous phase from the decanter
(Stream 8) and the water from the drying column (Stream 9) are sent to waste
9
treatment.
The crude TCE (Stream 11) is sent to the TCE column, where light ends
(Stream 13) are removed to be stored and recycled. The bottoms (Stream 14),
containing mainly TCE, are neutralized with ammonia and then dried to produce
19
finished TCE (Stream 15) which is sent to the TCE storage.
21
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The crude PCE (Stream 12) from the PCE/TCE separation column is fed to a
heavy ends removal column where PCE and light ends (Stream 16) go overhead to
a PCE finishing column and the heavy ends (Stream 17) remaining as the bottoms
are sent to the organic recycle system. Here the organics that can be recycled
(Stream 18) are separated from tars and sent to the recycle organic storage.
The tars are incinerated. The PCE and light ends (Stream 16) from the heavy
ends column are fed to a light ends removal column. Light ends (Stream 20)
are removed overhead and are stored and recycled. The PCE bottoms (Stream 21)
are neutralized with ammonia and then dried to obtain finished PCE (Stream 22)
19
which is sent to the PCE storage.
Emissions
Process Vent Emissions—
Table 4 gives emissions data for process vents in PCE and TCE production
processes which may contain VDC. The table lists: uncontrolled VDC emission
factors, potentially applicable control techniques, and associated controlled
VDC emission factors. .These emissions data were developed based on published
information for general operations used in the production of PCE and TCE.
Variations in process design, feed materials, and reaction conditions have a
substantial effect on amounts of VDC and other byproducts produced by PCE and
TCE production processes. As a result, VDC emissions vary for each plant.
Chlorination process - Vents containing VDC in the EDC chlorination
process include the neutralization and drying vent (Vent A, Figure 3), and
distillation column vents (Vents B, Figure 3). Uncontrolled VDC emission
factors are estimated at 2.5 kilograms per megagram PCE and TCE produced (kg/
Mg), for the neutralization and drying vent, and 0.106 kg/Mg PCE and TCE,'for
20
the distillation vent.
Emissions from both of these sources can be controlled by refrigerated
14
vapor condensers with an efficiency of about 80 percent. The control
efficiency attainable using refrigeration is dependent on emission stream
characteristics and condenser operating temperatures.
23
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Oxychlorination process - Vent streams containing VDC in the EDC •
oxychlorination process include the reactor vent (Vent A, Figure 4), the
drying column vent (Vent B, Figure 4) and the distillation column vents
(Vent C, Figure 4). Uncontrolled VDC emission factors have been estimated at
0.4 kg/Mg PCE and TCE produced, for the drying column vent, and 0.098 kg/Mg
20
PCE and TCE, for the distillation column vents.
The uncontrolled emission rate given in Table 4 for the reactor vent was
calculated based on a total chlorinated hydrocarbon emission factor for the
reactor vent of 21.3 kg chlorinated hydrocarbon emitted per megagram PCE and
20
TCE produced. It was assumed that the fraction of the total chlorinated
hydrocarbons comprised by VDC in the reactor vent is the same as the fraction
of chlorinated hydrocarbons comprised by VDC in the drying column vent. In
the drying column vent, VDC comprises about 18 percent of total chlorinated
hydrocarbon emissions. Thus, VDC emissions from the reactor vent were
estimated as follows:
(21.3 kg Cl species/Mg) x 0.18 kg VDC/kg Cl species) = 3.8 kg VDC/Mg
- Emissions from the reactor and drying column vents can be controlled by
14 15
incineration with an efficiency of about 98 percent or higher. ' Emissions
from the distillation column vent can be controlled by aqueous scrubbing with
14
an efficiency of about 90 percent.
Other Emission Sources
In addition to process vents, potential VDC emission sources from PCE
and TCE production include storage and handling operations, process fugitive
sources, and treatment and disposal of process wastes. VDC is expected to be
emitted from recycle storage tanks in both the chlorination and oxychlorination
processes for PCE and TCE production (Vent C in Figure 3, and Vent D in
Figure 4). VDC is also emitted from any pumps, compressors, flanges, and
valves which are exposed to streams containing VDC (Source E in Figure 3 and
Source I in Figure 4). Insufficient information is available to estimate VDC
emissions from these sources.
Source Locations
Major producers of perchloroethylene and/or trichloroethylene are listed
in Table 5.18
25
-------
TABLE 5. FACILITIES PRODUCING PERCHLOROETHYLENE
AND/OR TRICHLOROETHYLENE18
Chemical
produced
Company Location PCE TCE
Diamond Shamrock Corp. Deer Park, TX X
Dow Chemical U.S.A. Freeport, TX XX
Pittsburg, CA X
Plaquemine, LA" X
E.I. duPont de Nemours
• and Co. Corpus Christi, TX X
PPG Industries, Inc. Lake Charles, LA XX
Stauffer Chemical Co. Louisville, KYC X
Vulcan Materials Co. Geismar, LA X
Wichita, KS X
PCE = perchloroethylene
TCE = trichloroethylene
Plant has been on standby since 1981.
Note: This is a list of major facilities producing perchloroethylene and/or
trichloroethylene by any production process. Current information on
which of these facilities produce these chemicals by ethylene dichloride
chlorination or oxychlorination is not available. This list is"
subject to change as market conditions change, facility ownership
changes, or plants are closed down. The reader should verify the
existence of particular facilities by consulting current listings or
the plants themselves. The level of emissions from any given facility
is a function of variables, such as throughput and control measures, and
should be determined through direct contacts with plant personnel.
26
-------
1,1,1-TRICHLOROETHANE PRODUCTION
Most 1,1,1-trichloroethane produced in the U.S. is made from vinyl
chloride. An ethane-based process currently is used to a lesser extent.
Also, a process starting from VDC formerly was used to produce 1,1,1-
trichloroethane. ' This section discusses VDC emissions from the ethane
process, which produces VDC as a byproduct. VDC is not produced as a
byproduct of the vinyl chloride process.
Process Description
In the ethane process for 1,1,1-trichloroethane production, ethane is
chlorinated to produce the product 1,1,1-trichloroethane and a number of
21
byproducts. The main reactions in the chlorination process are as follows:
CH3-CH3 + C12 »- CH3-CH2C1 + HC1
ethane ethyl chloride hyrodgen chloride
CH,-CH0C1 + C10 *• CH.-CHC1,, + HCl
3 2 232-
1,1-dichloroethane
CH3-CH2C1 »- CH2=CH2 + HCl
ethylene
CH--CHC12 + C12 »• CH--CC1- + HCl
1,1,1-trichloroethane
CH.-CHC1 +• CH2=CHC1 + HCL
"vinyl chloride
CH3-CC13—-*-VDC + HCl
vinylidene chloride
Minor quantities of 1,2-dichloroethane and 1,1,2-trichloroethane are also
produced. Raw material ratios and reactor conditions determine the relative
proportions of 1,1,1-trichloroethane and byproducts produced. If 1,1,1-
trichloroethane is the only product desired, ethyl chloride and .'• • '.'••
1,1-dichloroethane can be recycled to the chlorination reactor, and vinyl
chloride and VDC can be catalytically hydrochlorinated to yield . .•• .'..-.
21
1,1-dichloroethane and 1,1,1-trichloroethane, respectively:
27
-------
FeCl3
CH,|=CHC1 + HC1 *-CH3-CHC12
FeCl3 .
VDC + HC1 —*- CH^—CC13
Basic operations which may be used in the ethane process, for 1,1,1-
21
trichloroethane are shown in'Figure 5. In this process, byproduct
chlorinated species, including VDC, are recycled and converted to
21
1,1,1-trichloroethane.. Chlorine (Stream 1) and ethane (Stream 2) are fed
to the chlorination reactor along with recycle streams of 1,1-dichloroethane
(Stream 13) and ethyl chloride (Stream 17). The reactor is adiabatic, with
a residence time of about 15 seconds, and is maintained at a pressure of
about 600 kiloPascals (kPa) and an average temperature of about 400°C. No
catalyst is used.
The reactor exit stream (Stream 3) is a gas containing ethane, ethylene,
vinyl chloride, ethyl chloride, VDC, 1,1-dichloroethane, 1,2-dichloroethane,
1,1,2-trichlorbethane, 1,1,1-trichloroethane, hydrogen chloride, and minor
amounts of other chlorinated hydrocarbons. This stream enters a quench
column* where it is cooled, and a residue comprising mainly tetrachloroethanes
and hexachloroethane is removed (Stream 4).
The overhead stream from the quench column (Stream 5) is fed to a
hydrogen chloride column, in which ethane, ethylene, and HC1 are removed
from chlorinated hydrocarbons. A portion of the overheads (Stream 6),
containing HCl is used to provide the HC1 requirements for VDC and vinyl
chloride hydrochlorination in a later step. The remainder (Stream 7) is
purified for use in other processes.
The bottoms from the HCl column (Stream 8), containing chlorinated
hydrocarbons, are fed to a heavy ends column, where a bottoms stream (Stream 9),
comprising mainly 1,2-dichloroethane and 1,1,2-trichloroethane, is removed
for use in other processes. Overheads from the heavy ends column (Stream 10),
comprising 1,1,1-trichloroethane, vinyl chloride, VDC, ethyl chloride and
1,1-dichloroethane, are fed to the 1,1,1-trichloroethane column, which removes
the product as a bottoms stream (Stream 11).
28
-------
o
Ti
4J
U
13
O
M
•e
-------
Overheads from the product recovery column (Stream 12) are fed to
another column.,' where 1,1-dichlorqethane is removed as bottoms (Stream 13)
and recycled to the chlorination reactor. Overheads from this column (Stream 14),
comprising mainly vinyl chloride, VDC and ethyl chloride, are fed along with
the HC1 byproduct stream (Stream 6) to a hydrochlorination reactor. This
reactor operates at a temperature of about 65°F, a pressure of about 450 kPa,
and with ferric chloride catalyst. Alternatively, these byproducts may be
used in other processes at the plant.
The hydrochlorination reactor converts vinyl chloride and VDC to
1,1-dichloroethane, and 1,1,1-trichloroethane, respectively. Thus, the
reactor product stream (Stream 15) consists of unreacted ethyl chloride, and
1,1-dichloroethane and 1,1,1-trichloroethane. This product stream is mixed
with ammonia to neutralize residual HC1 and catalyst. Spent neutralized
catalyst is removed in a filter and the product is then fed to a product
recovery column. The bottoms from this column (Stream 16), comprising mainly
r,l,l-trichloroethane, are recycled to the 1,1,1-trichloroethane column.
Overheads (Stream 17), composed of ethyl chloride and 1,1-dichloroethane, are
21
recycled to the chlorination reactor.
Emissions
Potential VDC emission sources from the ethane process for
1,1,1-trichloroethane include: the vents for the 1,1,1-trichloroethane and
1,1-dichloroethane distillation columns (Source A); and process fugitive
sources, such as valves, flanges, pumps, relief valves, and drains, located
between the chlorination reactor and the hydrochlorination reactor. Data
from one plant indicates that the concentration of-VDC in the distillation
22
column vents is negligible. Data are not available to estimate fugitive
emissions of VDC from the ethane process.
Source Locations
Major producers of 1,1,1-trichloroethane are listed in Table 6. '
Information is not available on which of these plants use the vinyl chloride
• process and which use the ethane process.
30
-------
TABLE 6. FACILITIES PRODUCING 1,1,1-TRICHLOROETHANE
10,18
Company
Location
Dow Chemical U.S.A.
PPG Industries, Inc.
Vulcan Chemicals •
Freeport, TX
Lake Charles, LA
Geismar, LA
Note: This is a list of major facilities producing 1,1,1-trichloroethane
by any production process. Current information on which of
these facilities produce this chemical from ethane or vinyl
chloride is not available. This list is subject to change as
market conditions change, facility ownership changes, or plants
are closed down. The reader should verify the existence of
particular facilities by consulting current listings or the plants
themselves. The level of emissions from any given facility is a
function of variables, such as throughput and control measures,
and should be determined through direct contacts with plant
personnel.
31
-------
POLYMERIZATION OF VINYLIDENE CHLORIDE
Vinylidene chloride monomer is polymerized with a variety of other
monomers to produce copolymers with special properties. VBC copolymers can
be divided into high VDC polymers, generally containing 70 to 95 percent VDC,
and low VDC polymers, generally containing 10 to 70 percent VDC.
High VDC polymers are unique in their low permeabilities to oxygen,
water vapor, and other gases. They also have good clarity and.a glossy
appearance. High VDC polymers typically are used as vapor barrier coatings
on various film substrates, such as paper, polyesteri polypropylene, or
polyethylene. High VDC polymers are also used to make Saran films which can
be used alone or laminated to other plastic films. The comonomers most
commonly used to produce high VDC polymers are vinyl chloride, acrylic acid,
2 23 24
acrylic esters and acrylonitrile. * '
In low VDC polymers, the VDC monomer generally is added to improve the
'flame retardant properties of the finished polymer." Low VDC polymers are
used as flame resistant coatings, saturants, dipping compounds, and adhesives.
They can also be sprayed onto fibers and textiles. Typical comonomers used
in these applications include acrylic esters, vinyl acetate, and vinyl chloride.
VDC is used with styrene and butadiene monomers to produce a flame retardant
styrene-butadiene latex for carpet backing. VDC is also used with acrylonitrile
o o o o /
to produce modacrylic synthetic fibers. » » •
Emissions from VDC polymerization are discussed in this section.
Emissions of residual VDC monomer from the subsequent processing and fabrication
of VDC in polymers are discussed in a later section. Copolymer production
and fabrication generally are carried out at separate facilities.
Process Description
The reactions involved in the production of vinylidene chloride copolymers
are illustrated in Figure 6. The major process used to produce VDC copolymers
is emulsion polymerization. This polymerization technique can be used to
23
produce both latex resin and dried resins. Suspension polymerization is
also used to produce dried resins, and solution polymerization is used to
23 24
produce copolymers for synthetic fiber production. ' Table 7 summarizes
the types of VDC copolymers produced, and identifies production processes,
typic
type.
typical comonomers used, VDC contents, and major applications for each resin
23,24
32
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Figure 6. Basic reactions involved in the polymerization of vinylidene
chloride with a comonomer.
33
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Emulsion. Polymerization—
Basic operations which may be used in emulsion and suspension polymerization
1 24 '
of VDC copolymers are shown in Figure 7. ' VDC monomer (Stream 1), comonomer
(Stream 2), and water (Stream 3) are metered and charged to a batch reactor
along with surfactants and initiator (Stream 4). The batch is agitated,
resulting in the formation of an emulsion of aqueous and organic phases.
After charging, the batch is heated causing the activation of the initiator.
Initiators generally used in emulsion polymerization are water soluble peroxides
which dissociate to form free radicals when heated. The initiator radicals,
on contacting the organic monomer phase, initiate the polymerization of VDC
and the comonomer. The polymerization reaction is exothermic; therefore,
after the reaction has commenced, the reactor must be cooled. In emulsion
polymerization, the reactor temperature typically is held at about 30°C and
the reaction duration is about 7 to 8 hours. Additional monomer and initiator
may be fed to the reactor during the course of the reaction. The.degree of
2 23
completion is 95 to 98 percent. *
Generally, the polymerized batch (Stream 5) is -stripped of unreacted
monomers (Stream 6) using steam and vacuum. This can be done either in the
reactor itself or in a separate stripping vessel. The unreacted monomer is
recycled if possible (Stream 7). For some types of copolymers, contamination
of VDC with other comonomers precludes the recycle of VDC. Stripped polymer
(Stream 8) is transferred to a holding tank, where it may be mixed with other
24
polymer batches to ensure product uniformity.
Emulsion polymerization can be used to produce either a latex (Stream 9)
or a dry product (Stream 10). A latex is an emulsion of polymer particles in
water, which is sold or used undried. If a dried product is desired, water
is removed by coagulation and dewatering, followed by drying with hot air.
The dried product comprises polymer particles
by emulsion polymerization is 100 to 150 nanometers.
Suspension Polymerization—
The particle diameter produced
2,23
The same basic steps are used in suspension polymerization as in emulsion
polymerization (Figure 7). VDC (Stream 1), comonomer (Stream 2), and water
(Stream 3) are metered and charged to a batch reactor along with surfactant
35
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36
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and initiator (Stream 4). In suspension polymerization, the initiator used
is soluble in the organic phase. The batch is agitated to produce a suspension
of the organic phase in the water phase. After charging, the'batch is
heated to activate the initiator, which causes polymerization. The reactor
2 23
must then be cooled to remove the heat of polymerization. "
Suspension polymerization generally is carried out at about 60°C. The
duration of the reaction is 30 to 60 hours and the degree of completion is
2
about 85 to 90 percent. After the polymerization reaction has reached the
desired degree of completion, the polymer (Stream 5) generally is stripped of
unreacted monomer (Stream 6) by steam and heat, either in the reactor or in a
separate vessel. Unreacted monomer is recycled (Stream 7) or vented to a
control system. The batch is then transferred to a holding tank (Stream 8)
and dried (Stream 11) with hot air to produce dry polymer particles. Typical
particle diameters produced by suspension polymerization range from 150 to
2 21
590 microns. *
Solution Polymerization—
As noted above, solution polymerization is used in the production of
vinylidene chloride copolymer synthetic fibers. These fibers typically have
2 23 24
a low VDC content. ' ' Information is not available on the specific steps
used in the solution polymerization of VDC copolymers; however, the general
reaction steps are expected to be similar to those used in the solution
polymerization of other resins.
In a solution polymerization process, the polymerization reaction is
carried out in a solvent which dissolves both the monomers and the finished
polymer. Monomers, initiators, and solvents are charged to a polymerization
reactor where the reaction typically is carried out under elevated temperature
and pressure. The process can be carried out either in a batch process or a
continuous process. In either case, the product is a homogeneous mixture of
solvent, polymer, and unreacted monomers. Unreacted monomer may be stripped
from the polymer/solvent mixture by the use of steam and heat. In a batch
process, the stripping step may be carried out either in the reaction vessel
or in a separate stripping vessel. In a continuous process, a separate
o e o£
stripping vessel would be required. '
37
-------
The resulting polymer solution is used in a "spinning" process to produce
the product synthetic fiber. In this step, polymer fibers are extruded into
a zone of hot vapor or water, where the fibers are solidified and solvent and
residual monomer are removed. This step is discussed in the subsequent
OA O C O£
section on the fabrication of VDC copolymer products. * *
Emissions
Potential VDC emissions sources at VDC polymerization plants include:
• VDC unloading and storage,
• opening and cleaning of mixing, weighing, holding, and reaction
vessels,
• relief valve discharges,
• stripper and monomer recovery system vents,
• evaporation of residual VDC from the finished copolymer, and
• process fugitive sources, including valves, flanges, pumps, compressors,
relief valves, and process drains.
Data are not available to estimate uncontrolled VDC emissions from these
sources. However, in response to previous EPA surveys, several polymerization
plants have reported total.controlled emissions of vinylidene chloride and controlled
16 23
emissions from a number of individual sources. ' Controlled VDC emission
rates reported for VDC polymerization are given in Table 8.
The emission rates given in Table 8 for process fugitive sources are based
on EPA estimates of emissions from typical small to medium sized generic
polymerization facilities using monthly inspection and maintenance of fugitive .
25
sources. Emission factors given for reactor emissions, monomer recovery emissions,
storage and transportation emissions, and total plant emissions are based on
16 23
industry estimates in response to EPA surveys. ' Data are not available
on the specific controls used to attain the reported emission rates. Techniques
which can be used to control emissions of monomers from polymerization plants
28
are identified in Table 9.
Source Locations
Table 10 lists producers of VDC copolymers. The table also gives plant
23 24 29
location and identifies the types of VDC copolymer produced at each facility. ' '
38
-------
TABLE 8. CONTROLLED VINYLIDENE CHLORIDE EMISSIONS FOR A HYPOTHETICAL
VINYLIDENE CHLORIDE POLYMERIZATION PLANT3
Source
Controlled
VDC emission
Emission source
Reactor
Monomer recovery
Unloading/storage
Process fugitive
Total
designation
B
D
A
G
factor
3.5 kg/Mgd
0.33 kg/Mgd
2.1 kg/Mgd
2.6-10 kg/hre
1.4-7.0 kg/Mgd
a
Any given plant may vary in configuration and level of control from this
hypothetical facility. The reader is encouraged to contact plant personnel
to confirm the existence of emitting operations and control technology at a
particular facility prior to estimating emissions therefrom.
Letters refer to vents designated in Figure 7.
M
Emission factors in terms of kg/Mg refer to kilogram of vinylidene chloride
emitted per megagrara of vinylidene chloride polymerized. In cases where a
particular source designation applies to multiple operations, these factors
represent combined emissions for all, not each, of these operations within
the hypothetical facility. The types of controls employed were not reported.
Based on industry estimates.
Based on EPA projections of monomer emissions from small and medium sized
generic polymerization plants with quarterly inspection and maintenances of
valves, pumps, compressors, flanges, relief valves, and process drains.
Fugitive emission rate is dependent on plant complexity rather than size.
39
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USE OF VINYLIDENE CHLORIDE IN SPECIALTY CHEMICAL PRODUCTION
Vinylidene chloride is used as a chemical intermediate in the production
of chloroacetyl chloride. This use of VDC is minor in comparison with its
use in production of VDC copolymers. The structure of chloroacetyl chloride
is as follows:
4
Cl 0
Ml
H—C—C
I!
H Cl
Its main use is in the manufacture of chloroacetophenone, the principal
7 9
ingredient in tear gas. It is also used in the manufacture of Pharmaceuticals. *
Process Des^ript^on^and Emissions
Information on the process used to produce chloroacetyl chloride from
VDC is not available, nor are data available to estimate VDC emissions from
the process. Dow Chemical reports no losses of VDC to the environment from
9
the process used in chloroacetyl chloride production'.
•
Source Locations
The VDC process for chloroacetyl chloride is used by the Dow Chemical
i., of Midland, Michigan.9 !
plant or plants use-the process.
Q
U.S.A., of Midland, Michigan. Information was not available on which Dow
42
-------
VINYLIDENE CHLORIDE COPOLYMER FABRICATION
When VDC is polymerized to produce VDC copolymers, some residual VDC
monomer remains in the polymer. During subsequent fabrication, when the
polymer is heated, dissolved, or otherwise treated, some of this residual
monomer evaporates, resulting in VDC emissions. The level of VDC residue in
the polymer, and hence the magnitude of VDC emissions, is dependent on the
type of polymer, the comonomer used, and whether stripping technology is used
at the polymerization plant.
As noted in the previous section entitled POLYMERIZATION OF VINYLIDENE
CHLORIDE, VDC copolymers can be divided into two groups: high-VDC copolymers
(70 to 90 percent) used to form moisture and vapor barrier coatings and
films; and low-VDC copolymers (10 to 70 percent), where VDC is added mainly
to improve the flame retardant properties of the finished polymer. VDC
copolymers are also produced in a number of forms: dried suspension resin,
dried emulsion resin, latex, and polymer solution. The types of VDC cogolymers
produced, production methods used, and applications of the different types
were summarized in Table 7 in the section entitled POLYMERIZATION OF VINYLIDENE
CHLORIDE. Generally, copolymer fabrication and copolymer production are
carried out at separate facilities.
Process Descriptions
Process descriptions are presented below for three methods of fabricating
high-VDC resins: coating of cellophane with copolymer solution, coating of
paper or plastic film with latex, and extrusion of dried emulsion or suspension
resin. Information was not available on the specific methods used to fabricate
low-VDC resins.
Cellophane Coating with Copolymer Solutions
Basic operations that may be used in the coating of cellophane with VDC
30
copolymer are shown in Figure 8. The inputs to this process are a dried,
high-VDC copolymer and pretreated cellophane film. The VDC polymer is first
dissolved in a solvent mixture in a closed tank. The solvent mixture includes
methyl ethyl ketone and tetrahydrofuran as the primary solvents and toluene
as a diluent. Following the dissolution step, additives such as wax, talc
and silica are added in a closed blender. The polymer solution is then fed
to a dip tank, through which a cellophane film strip is drawn.
43
-------
60
c
•rt
*J
a
o
u
41
4-1
C
•H
1-1
(U
u T
CD ^=
^S 60
•U -H
t-i 0)
CU C
C. «
O f
c-
o o
•H rH
W rH
<0 41
« U
00
-------
After passing through the dip tank, the cellophane, now coated with VDC
copolymer solution, is run through a dryer. The dryer consists of two
chambers. In the first, dry air at 90 to 140°C is passed over the film,
resulting in removal of the solvent. In the second chamber, the film is
conditioned in warm humid air.
Solvent laden vapor is collected from the drying chamber and ducted to
carbon adsorption beds. Solvent stripped from the beds is purified by
distillation and recycled to the process. Heating air from the second
drying chamber is vented to the atmosphere.
Coating with Latex Copolymer
As noted in the earlier section of POLYMERIZATION OF VINYLIDENE
CHLORIDE, a latex is a polymer emulsion in water. Materials typically
coated with high-VDC latex include paper products and plastic films.
The latex may first be blended with additives, such as wax or pigments,
or diluted with additional water in a vented mixing tank. The latex is pumped
from the mixing tank to a holding tank and then to the dip tank. The holding
tank allows reduction of any foam that may form during mixing. The material
to be coated is rolled through the dip tank and then to a drying oven. In the
drying oven, water is removed from the latex and the latex forms a barrier
fila. Both the dip tank and the drying oven are vented to the atmosphere.
Extrusion of Thermoplastic Copolyraer
The raw material for extrusion is dried emulsion or suspension resin in
the form of a powder or small granules. The polymer is mixed with additives
such as plasticizer in a high-intensity blender. Mechanical energy dissipated
in the blender heats the resin to about 170*C. The blender is vented
through a hood, usually to a roof stack. From the high-intensity blender,
the resin is fed to a ribbon blender, where it is homogenized further and
cooled. The blended resin may be stored prior to extrusion, or may be extruded
immediately, after blending.
-------
The extrusion process used on high-VDC copolymers is a blown-film
process. The resin compound is fed to an extruder, and is extruded through
a die in the fora of a tube, becoming molten in the extrusion process. The
end of the tube is then pinched off, and air is blown into the tube, expanding
it into a bubble. The bubble is then cooled by another blast of air. The
30
bubble is then flattened and undergoes further processing to form a film.
Emissions
Emission sources from VDC copolymer fabrication include: polymer
storage vents, polymer mixing and blending vents, and finished polymer
drying. Emissions from individual sources have not been quantified. However,
total VDC emissions from copolymer fabrication can be estimated by mass
balance from the concentrations of residual VDC monomer in the polymer
entering and leaving the process.
EF - Ci - Co
where EF = the overall uncontrolled emission factor for the fabrication
process, g VDC/Mg copolymer processed,
C. = the concentration of residual VDC monomer'in the copolymer
1 entering the dissolver (Figure 8) ppmw, and
C = the concentration of residual VDC monomer in the copolymer
0 leaving the dryer (Figure 8), ppmw.
Table 11 summarizes data on residual VDC levels in raw and fabricated high-VDC
copolymers, and presents estimates of uncontrolled VDC emission factors for
high-VDC copolymer fabrication processes; Data are not available on the
residual VDC levels in low-VDC copolymers.
It should be noted that the mass balance technique of estimating emissions
involves the assumption that the only removal mechanism for VDC from the
copolymer is by emissions to the atmosphere. Thus, emissions estimates
developed by the mass balance technique would be worst case estimates. In
high temperature fabrication processes and drying processes, seme of the
residual VDC may be polymerized.
46
-------
TABLE 11. ESTIMATES OF UNCONTROLLED EMISSION FACTORS FROM HIGH-VDC
COPOLYMER FABRICATION PROCESSES
Copolymer VDC
concentrations (pprnw)3
Estimated
uncontrolled
Process
Celophane coating
Latex coating
Extrusion
Raw
resinb
10-120
50-2000
2-25
Processed
resinc
neg
0-500
neg
emission
factor (g/Mg)d
10-120
50-1500
2-25
Reference 30.
Resin entering the dissolver (Figure 8).
CResin leaving the dryer (Figure 8).
Calculated from residual VDC levels. Emissions are expressed
in terms of grams of VDC per Mg of copolymer processed.
47
-------
VDC emissions from copolymer fabrication generally are uncontrolled. In
the first stage of the drying operation for cellophane coating, emissions
containing solvent are captured and ducted to.a carbon adsorption system.
The solvent is then desorbed and recycled to the polymer dissolving operation.
Some of the VDC vaporizing in the drying process would be captured on the
adsorbers. However, unless some process is used to separate the captured VDC
from the solvent, the VDC would be recycled to the process and eventually
emitted from the second stage of the drying process, from the adsorber vent,
or from another vent.
Source Locations
Table 12 gives. SL list of plants fabricating high-VDC copolymers, along
with plant locations. The list includes plants that produce PVDC-coated
cellophane, plants that apply PVDC barrier-coatings to paper and plastics,
and plants that extrude VDC copolymer.
Information is not available on.the locations of fabrications of. low-VDC
polymers. Such plants would be classified under Standard Industrial Classification
(SIC) code 282. -
48
-------
TABLE 12. FACILITIES FABRICATING HIGH VINYLIDENE CHLORIDE COPOLYMERS
30
Company
Plant Location
Processes
Cellophane Barrier Resin
coating coating extrusion
Allied Chemical Corp.
American Bag and Paper
American Can Co.
Amtech, Inc.
Consolidated Paper
Crown Zellerbach
Cryovac Div. of
W, R. Grace
Curwood Div. of
Bemis
Daniels
Diversa-Pak
Dow Chemical
E.I. dupont de Nemours
Pittsville, PA
Philadelphia, PA
Neenah, WI
Odenton, MD
Wis cons in Falls, WI
Portland, OR
Camarilla, CA
Cedar Rapids, IA
Iowa Park, TX
Simpsonville, SC
New London, WI
Rhinelander, WI
St. Petersburg, FL
Midland, MI
Richmond, VA
Circleville, OH
Continued
49
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
FMC Corp.
Gordon Cartons
Green Bay Packaging
Hercules
Interstate Folding Box
Clinton, IA
Tecumseh, KS
Fredericksburg, VA
Marcus Hook, PA
Baltimore, MD
Green Bay, WI
Covington, VA
Middletown, OH
X
X
X
X
X
X
X
X
-------
TABLE 12. (Cont'd.) FACILITIES FABRICATING HIGH VINYLIDENE CHLORIDE COPOLYMERS
Company
Plant. Location
Processes
Cellophane Barrier Resin
coating coating extrusion
Michigan Carton Co.
Milprint
Minnesota Mining and
Manufacturing
Olin Corp.
Olinkraft
Oscar Mayer
Rexham
Rhinelander Div, of
Battle Creek, MI
Milwaukee, WI
Decatur, AL
Pisgah Forest, NC
Covington, IN
West Monroe, LA
Chicago, IL
Davenport, IA
Los Angeles, CA
Madison, WI
Nashville, TN
Philadelphia, PA
Memphis, TN
X
X
X
X
X
X
X
X
X
X
X
X
X
St. Regis
Sealed Air Corp.
Standard Packaging
Thilmany
Union Carbide Corp.
Zumbril
Rhinelander, WI
Fairlawn, NJ
Clifton, NJ
Kaukauna, WI
Centerville, IA
Cincinnati, OH
X
X
X
X
X
X
:Note: This listing is subject to change as market conditions change, facility
ownership changes, plants are closed, etc. The reader should verify
the existance of particular facilities by consulting current listings
and/or the plants themselves. The level of VDC emissions from any
given facility is a function of variables such as capacity, throughput
and control measures, and should be determined through direct contacts
with plant personnel.
50
-------
VOLATILIZATION FROM WASTE TREATMENT, STORAGE, AND DISPOSAL
Considerable potential exists for emissions of volatile substances,
including VDC, from waste treatment, storage, and disposal facilities. VDC
is expected to be present in the following wastes: still bottoms and wastewater
from VDC production, perchloroethylene and trichloroethylene production, and
trichloroethane production; wastewater and off-specification polymer from
VDC polymerization; and still bottoms and wastewater from specialty chemical
production processes where VDC is used as a feedstock. (See separate sections
on emissions from these processes.) In addition, VDC may be present in wastes
from other processes.
VDC vapor may be emitted from surface impoundments for treatment and
storage of wastewater, open treatment and storage tanks, and land-treatment
areas for solid wastes and sludges. The above treatment and storage
facilities may be located at the site of generation of the waste, or at a
.separate waste treatment plant. Volatile compounds also may be emitted
from solid wastes during and even after disposal in a covered landfill.
Reference 31 summarizes general theoretical models for estimating volatile
*
substance emissions from generic waste treatment, storage, and disposal
operations, including surface impoundments, landfills, land treatment (landfarming),
wastewater treatment, and drum handling and storage operations. If facilities
of the above types are known to handle wastes containing VDC, the potential
for air emissions should be considered.
51
-------
SECTION 5
SOURCE TEST PROCEDURES
Vinylidene chloride emissions can be measured using EPA Reference Method 23,
32
which was proposed in the Federal Register on June 11, 1980. The method
has not been validated by EPA for vinylidene chloride; but a similar analytical
33 34
procedure has been used to measure occupational exposures to VDC. '
In Method 23, a sample of the exhaust gas to be analyzed is drawn into a
Tedlar or aluminized Mylar bag as shown in Figure 9. Tedlar is considered
a more reliable bag material than Mylar for VDC. The bag is placed inside
a rigid leak proof container and evacuated. The bag is then connected by a .
Teflon sampling line to a sampling probe (stainless steel, Pyrex glass-, or
Teflon ) at the center of the stack. Sample is drawn into the bag by pumping
air put of the rigid container.
The sample is then analyzed by gas chromatography (GC) coupled with
flame ionization detection (FID). Analysis should be conducted within one
day of sample collection. The recommended GC column is 3.05 m by 3.2 mm
stainless steel, filled with 20 percent SP-2100/0.1 percent Carbowax 1500 on
100/120 Supelcoport. This column normally provides an adequate resolution of
halogenated organics. (Where resolution interferences are encountered, the
GC operator should select the column best suited to the analysis.) The
column temperature should be set at 100°C. Zero helium or nitrogen should be
used as the carrier gas at a flow rate of approximately 20 ml/min.
The peak area corresponding to the retention time of vinylidene chloride
is measured and compared to peak areas for a set of standard gas mixtures to
determine the VDC concentration. The range of the method is 0.1 to 200 ppm;
however the upper limit can be extended by extending the calibration range or
diluting the sample. To avoid absorption of VDC by the Tedlar bag, the
sample should be analyzed as soon as possible after collection, preferably on
the same day. The method does not apply when vinylidene chloride is contained
in particulate matter.
52
-------
FILTER
(GLASS WOOL)
PROBE
SAMPLE
LINE
QUICK
.CONNECTS
VACUUM
LINE
STACK
WALL
FLOW
METER
CHARCOAL
TUBE
SAMPLING
BAG
RIGID
LEAKPROOF
CONTAINER
Figure 9. Method 23 sampling train.
32
53
-------
REFERENCES
1. Hushon, J., and M. Kornreich. Air Pollution Assessment of Vinylidene
Chloride. EPA-450/3-78-015, U.S. Environmental Protection Agency,
Washington, DC. February 1978. pp. 7-20.
2. Grayson, M., ed. Kirk-Othmer Encyclopedia of Chemical Technology.
Third Edition, Volume 23. John Wiley and Sons, New York, NY, 1983.
pp. 764-798.
3. Edney, E., S. Mitchell, and J. Bufalini. Atmospheric Chemistry of
Several Toxic Chemicals. EPA-600/3-82-092, U.S. Environmental Protection
Agency, Research Triangle Park, NC. November 1982. pp. 31-35.
4. Cuppitt, Larry. Fate of Toxic and Hazardous Materials in the Air
Environment. EPA-600/3-80-084, U.S.. Environmental Protection Agency-,
Research Triangle Park, NC. August 1980. pp. 3-6.
5. Standifer, R.L., and J.A. Key.- Report 4: 1,1,1-Trichloroethane,
Perchloroethylene, Trichloroethylene, and Vinylidene Chloride. In:
Organic Chemical Manufacturing—Volume 8: Selected Processes;
EPA-450/3-80-028c, U.S. Environmental-Protection Agency, Research
Triangle Park, NC. December 1980. pp. III-l to 111-17.
6. Neufeld, M.L., M. Sittenfield, M.J. Plotkin, K.F. Wolk, and R.E. Boyd.
Market Input/Output Studies—Task I: Vinylidene Chloride.
EPA-560/6-77-033, U.S. Environmental Protection Agency, Washington, DC.
October 1977. pp. 67-70, 156-163.
7. Hawley, Gessner G. The Condensed Chemical Dictionary. Tenth Edition.
Van Nostrand Reinhold Co., New York, NY. 1981. pg. 232.
8. Modern Plastics Encyclopedia. Modern Plastics. 59(10A):113-114.
October 1982.
9. Reference 6. pg. 156.
10. Reference 5. pp. II-l to II-6.
11. Reference 5. pp. 111-15 to 111-17.
12. Reference 6. pp. 67-70.
13. Reference 5. pp. IV-15, IV-18, and IV-19.
14. Reference 5. pp. V-5 to V-7.
54
-------
15.
16.
Mascone, D., U.S. Environmental Protection Agency. Memo and Addendum
to J.R. Farmer, EPA, entitled "Thermal Incinerator Performance for NSPS,"
June 11, 1980.
Eisen, P., M. Sanders, and M. Samuels. Human Exposure to Atmospheric
Concentrations of Vinylidene Chloride. Prepared by Wapora, Inc.
(Project 507-13) for the U.S. Environmental Protection Agency, Research
Triangle Park, NC. February 4, 1982. pp. 2-1 and D-l to D-3.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
Reference 6. pp. 84 to 86.
1983 Directory of Chemical Producers, United States of America.
International. Menlo Park, CA. 1983.
Reference 5. pp. III-8 to 111-14.
Reference 5. pp. IV-11 to IV-18.
pp.
SRI
Reference 5.
III-4 to III-8.
Reference 5. pp. IV-6 to IV-10.
Vinylidene Chloride Monomer Emissions from the Monomer, Polymer, and
Polymer Processing Industries. Prepared by Arthur D. Little, Inc.
(ADL Reference 76086-31} for the U.S. Environmental Protection Agency,
Research Triangle Park, NC. April 1976. pp. 16 to 42.
Reference 6. pp 9-20.
Wilkins, Glynda E. Industrial Process Profiles for Environmental Use:
Chapter 10. Plastics and Resins Industry. EPA-600/2-77-023J,
U.S. Environmental Protection Agency, Research Triangle Park, NC.
February 1977. pp. 55-58.
Synthetic Fiber Production Facilities—Background Information for Proposed
Standards (Preliminary Draft). U.S. Environmental Protection Agency,
Research Triangle Park, NC. April 1982. pp. 3-1 to 3-27.
Control of Volatile Organic Compound Fugitive Emissions form Synthetic
Organic Chemical, Polymer, and Resin Manufacturing Equipment.
U.S. Environmental Protection Agency, Research Triangle Park, NC.
August 1981. pg. 4-3.
Vinyl Chloride - A Review of National Emission Standards. EPA-450/3-82-003,
U.S. Environmental Protection Agency, Research Triangle Park, NC.
February 1982. pg. 4-2.
Reference 16. pp.
Reference 23. pp.
1-3 and 1-4.
43 to 61.
55
-------
APPENDIX A
PROCESS FUGITIVE EMISSION CALCULATIONS •
FOR VINYLIDENE CHLORIDE PRODUCTION
FROM 1,1 ,'2-TRICHLOROETHANE
Fugitive emissions of vinylidene chloride (VDC) and other volatile
organics result from leaks in process valves, pumps, compressors, and pressure
relief valves. Fugitive VDC emission rates from these sources were based on
a process flow diagram (Figure 2), process operation data, and a fugitive
fP<
2
source inventory for a hypothetical plant and EPA emission factors for
process fugitive sources.'
The first step in estimating fugitive emissions of VDC was to list the
process streams in the hypothetical plant. Their phases (i.e., gaseous or
liquid) were then identified from the process flow diagram and their compositions
estimated. For the reactor product stream, the composition was estimated
based on reaction completion data. For a stream from a distillation column
* • .
or other separator, the composition was estimated based on the composition of
the input stream-to the unit, the unit description, and the general description
of stream of interest (i.e. overheads, bottoms, or sidedraw).
After the process streams were characterized, the number of valves per
stream were estimated by dividing the total number of valves at the plant
equally among the process streams. Similarly, pumps were apportioned equally
among liquid process streams, and relief valves were apportioned equally
among all reactors, columns, and other separators. The locations of any
compressors were determined from the process flow diagram. Although the
above sources probably are not apportioned equally among the process lines at
an actual plant, the equal apportionment algorithm provides the best estimate
of the number of sources per line given the available data.
Emissions were then calculated for pumps, compressors, valves in liquid
and gas line service, and relief valves. Emissions from flanges and drains
are minor in comparison with these sources and were therefore neglected.
A-l
-------
-------
Fugitive emissions from a particular source were assumed to have the same
composition as the process fluid to which the source is exposed. For valves
in liquid service, for instance, VDC emissions were determined by taking the
product of: (1) the total number of liquid valves in VDC service; (2) the
* *
average VDC content of the streams passing through these valves; and (3) the
average fugitive emission rate per.valve per unit time as measured by EPA.
Emissions from valves in gas service, pumps and compressors were calculated in
the same manner. For relief valves, fugitive emissions were assumed to have
the composition\of the overhead.stream from the reactor or column served
by the relief valve. Emissions from the various fugitive source types were
summed to obtain total process fugitive'emissions of VDC.
Because emissions from process fugitive sources do not depend on their
size, but only on their number, total process fugitive emissions are not dependent
on plant capacity. .Thus, the overall emissions are expressed in terms of
kilograms per hour of operation.
HYPOTHETICAL PLANT FUGITIVE SOURCE INVENTORY
725 process valves
15 pumps (not including spares)
2 compressors
25 safety relief valves
PROCESS LINE COMPOSITION AND FUGITIVE SOURCE INVENTORY
Of the approximately major process lines in the production process,
9 contain at least some fraction of volatile organics compounds (VOC) and
6 contain vinylidene chloride (VDC). Compositions of the major process
streams (identified in Figure 2 in the section of VINYLIDENE CHLORIDE PRODUCTION)
are estimated in Table A-l.
A fugitive emission source inventory was not available for a VDC
production plant. However, studies of other synthetic organic chemical
manufacturing plants indicate that a typical fugitive source inventory is
as follows:
15 process valves per major process line,
1 pump (not including spares) per major liquid process line,
A-2
-------
-------
TABLE A-l. ESTIMATED PROCESS LINE COMPOSITION IN VDC PRODUCTION
Stream
number
1 •
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Phase
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
Vapor
Liquid
Liquid
Vapor
Liquid
Liquid
Stream composition
Water NaOH NaCl
0
1.00
0
0.75
0
0.77
0.90
0
0.90
0.90
0
0
0.90
0
0
0
1.000
0
0
0.061
0
0.011
0.012
0
0.012
0.012-
0
0
0.012
0
0
0
0
0
0
0
0
0.073
0.086
0
0.086
0.086
0
' - 0
0.086
0
0,
0
(weight fraction)
C12HC-CH2C1 VDC
*
0
0
1.000
0.191
0
0.024
0
0.164
0
0
0.164
0.164
0
0.164
1.000
0
0
0
0
0
0
0.121
0
0.836
0
0
0.836
0.836
0
0.836
0
1.000
Other
0
0
0
0
1.00
0
0
0
0
0
0
0
0
0
0
0
A-3
-------
-------
1 compressor for each gas line requiring pressurization, and
2 relief valves per pressure vessel or column.
EMISSION CALCULATIONS
-3
VDC emissions from valves in liquid and gas service, and for pumps
were calculated as follows:
(Total VDC emission rate for stream type) =
(# of streams ) X . .
(Average VDC content for stream type)
X (# of pumps or valves per stream)
X (Emission rate for individual rate for individual pumps or t
valves)
These calculations are summarized in Table A-2. Similarly, emissions
from relief valves were calculated for each vessel or column processing
VDC:
(VDC emissions rate) =
(2 relief valves per vessel) X
(VDC fraction in vessel overheads) X
(0.104 kg emissions/hr/relief valve)
These .calculations are summarised in Tahle A-3. No compressors are
expected to be in VDC service in the VDC-form-l,l,2-trichloroethane
process.
Total uncontrolled process fugitive emission rates for VDC
production are given in Table A-4, along with controlled emission rates
for various combinations of emission reduction techniques. The emission
reduction techniques studied were, inspection (quarterly and monthly)
for valves and pumps, use double mechanical sealed pumps, and use of
rupture disks in tandem with or in place of relief valves.
A-4
-------
-------
TABLE A-2. VDC EMISSIONS FROM VALVES AND PUMPS
Source type
Valves
vapor
liquid
Pumps
TOTAL
. Number
of
streams
2
3
3
Average
VDC weight
fraction3
0.84 '
0.60
0.60
Number
of
sources
30
45
3
Source VOC
emission rate
(kg/hr-source)
0.0056
0.0071
0.0494
Emissions
(kg/hr)
0.140
0.191
0.089
0.42
Fraction of source VOC emission rate.
A-5
-------
-------
TABLE A-3, VDC EMISSIONS FROM RELIEF VALVES
Vessel
Reactor
Phase separator
Drying column
Finishing column
Stripping column
Number of
relief
valves
2
2
2
2
2
VDC weight
fraction in
overheads
X
0.56
0.56
0.50
0.50
0.50
TOTAL
Emissions
(kg/hr)
0.12
0.12
0.10
0.10
0.10
0.54
Relief valve emission rate = 0.104 kg/hr-valve
A-6
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-------
-------
REFERENCES FOR APPENDIX
Standifer, R.L., and ,J.A. Key. Report 4: 1,1,1-Trichloroethane,
Perchloroethylene, Trichloroethylene, and Vinylidene Chloride. In:
Organic Chemical Manufacturing—Volume 8: Selected Processes.
EPA-450/3-80-028c, U.S. Environmental Protection Agency, Research
Triangle Park, NC. December 1980. pp. IV-1 to IV-22.
Fugitive Emission Sources of Organic Compounds—Additional
Information on Emissions, Emission Reductions, and Costs.
EPA-450/3-82-010, U.S. Environmental Protection Agency, Research
Triangle Park, NC. April 1982.
A-a •
------- |