TV?
EPA-600/2-77-1070
December 1977 Environmental Protection Technology Series
ENVIRONMENTAL
PROTECTION
AGENCY
DALLAS, TEXAS
LIBRARY
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are
1 Environmental Health Effects Research
2 Environmental Protection Technology
3. Ecological Research
4 Environmental Monitoring
5. Socioeconomic Environmental Studies
6 Scientific and Technical Assessment Reports (STAR)
7 Interagency Energy-Environment Research and Development
8 "Special" Reports
9 Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-77-1070
December 1977
SOURCE ASSESSMENT:
POLYCHLOROPRENE
State of the Art
by
D. A. Horn, D. R. Tierney, and T. N. Hughes
Monsanto Research Corporation
Dayton, Ohio 45407
Contract No. 68-02-1874
Project Officer
Ronald J. Turner
Industrial Pollution Control Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
-------
DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory - Cincinnati, U.S. Environmental Protection
Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or
recommendation for use.
11
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FOREWORD
When energy and material resources are extracted, processed,
converted, and used, the related pollutional impacts on our
environment and even on our health often require that new and
increasingly more efficient pollution control methods be used.
The Industrial Environmental Research Laboratory - Cincinnati
(lERL-Ci) assists in developing and demonstrating new and
improved methodologies that will meet these needs both effi-
ciently and economically.
This report contains an assessment of air emissions from the
polychloroprene industry. This study was conducted to provide
a better understanding of the distribution and characteristics
of emissions from polychloroprene manufacture. Data collection
emphasized the accumulation of sufficient information for EPA
to ascertain the need for developing control technology in this
industry. Further information on this subject may be obtained
from the Organic Chemicals and Products Branch, Industrial
Pollution Control Division.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
111
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PREFACE
The Industrial Environmental Research Laboratory (IERL) of the
U.S. Environmental Protection Agency (EPA) has the responsibility
for insuring that pollution control technology is available for
stationary sources to meet the requirements of the Clean Air Act,
the Federal Water Pollution Control Act, and solid waste legisla-
tion. If control technology is unavailable, inadequate, uneconom-
ical, or socially unacceptable, then financial support is provided
for the development of the needed control techniques for indus-
trial and extractive process industries. Approaches considered
include: process modifications, feedstock modifications, add-on
control devices, and complete process substitution. The scale of
the control technology programs ranges from bench- to full-scale
demonstration plants.
IERL has the responsibility for developing control technology for
a large number (>500) of operations in the chemical and related
industries. As in any technical program, the first step is to
identify the unsolved problems. Each of the industries is to be
examined in detail to determine if there is sufficient potential
environmental risk to justify the development of control technol-
ogy by IERL.
Monsanto Research Corporation (MRC) has contracted with EPA to
investigate the environmental impact of various industries that
represent sources of pollutants in accordance with EPA's respon-
sibility, as outlined above. Dr. Robert C. Binning serves as MRC
Program Manager in this overall program, entitled "Source Assess-
ment," which includes the investigation of sources in each of four
categories: combustion, organic materials, inorganic materials,
and open sources. Dr. Dale A. Denny of the Industrial Processes
Division at Research Triangle Park serves as EPA Project Officer
for this series. Reports prepared in this program are of two
types: Source Assessment Documents, and State-of-the-Art Reports.
Source Assessment Documents contain data on pollutants from
specific industries. Such data are gathered from the literature,
government agencies, and cooperating companies. Sampling and
analysis are also performed by the contractor when the available
information does not adequately characterize the source pollutants
These documents contain all of the information necessary for IERL
to decide whether a need exists to develop additional control
technology for specific industries.
IV
-------
State-of-the-Art Reports include data on pollutants from specific
industries which are also gathered from the literature, government
agencies and cooperating companies. However, no extensive sam-
pling is conducted by the contractor for such industries. Sources
in this category are considered by EPA to be of insufficient
priority to warrant complete assessment for control technology
decisionmaking. Therefore, results from such studies are published
as State-of-the-Art Reports for potential utility by the govern-
ment, industry, and others having specific needs and interests.
This study of polychloroprene plants was initiated by lERL-Research
Triangle Park in March 1975. Mr. Kenneth Baker served as EPA Proj-
ect Leader. The project was transferred to the Industrial Pollu-
tion Control Division, lERL-Cincinnati, in October 1975;
Mr. Ronald J. Turner served as EPA Project Leader from that time
through completion of the study.
v
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ABSTRACT
This document reviews the state of the art of air emissions from
polychloroprene manufacture. The composition, quality, and rate
of emissions, and their environmental effects are described.
Polychloroprene, generically called "neoprene," is a synthetic
rubber produced by the emulsion polymerization of 2-chloro-l,3-
butadiene (chloroprene). The monomer, chloroprene, is produced
by chlorination of butadiene with subsequent isomerization and
dehydrochlorination. Hydrocarbons such as chloroprene and tolu-
ene are emitted from storage tanks, refining columns, wash belts,
dryers, and batch polykettles. Particulates are emitted during
the dusting of neoprene rope with talc. Hydrogen chloride emis-
sions result from the incineration of waste chlorinated hydro-
carbons. Nitrogen oxides are emitted from vacuum column jets.
To assess the severity of emissions from this industry a repre-
sentative plant was defined based on specific mean values for
various plant parameters. Source severity was defined as the
ratio of the time-averaged maximum ground level concentration
of a pollutant to the primary ambient air quality standard for
criteria pollutants or to a reduced threshold limit value for
noncriteria pollutants. For a representative plant, source
severities for particulates, hydrocarbons, nitrogen oxides,
chloroprene, toluene, hydrogen chloride, and talc are 0.03, 23,
0.1, 4.3, 0.4, 0.9, and 3.4, respectively.
A decrease of about 25% in hydrocarbon emissions from this
industry is expected over the period 1976 to 1981. Polychloro-
prene manufacture contributes to the national emissions of par-
ticulates, hydrocarbons, and nitrogen oxides in the amounts of
0.0001%, 0.008%, and <0.0001%, respectively.
Hydrocarbon emissions have been controlled through a combination
of process modifications, brine-cooling systems, and nitrogen
blankets in pressurized storage tanks. Particulates emitted in
the talc dusting area may be controlled by exhaust systems in
conjunction with wet scrubbers or fabric filters. Hydrogen chlo-
ride emissions can be reduced by falling film absorbers and
packed scrubbers.
This report was submitted in partial fulfillment of Contract No.
68-02-1874 by Monsanto Research Corporation under the sponsorship
VI
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of the U.S. Environmental Protection Agency. This report covers
the period March 1975 to July 1977, and work was completed as of
July 1977.
Vll
-------
CONTENTS
Foreword iii
Preface iv
Abstract vi
Figures x
Tables xi
Abbreviations and Symbols xii
Conversion Factors and Metric Prefixes xiii
1. Introduction 1
2. Summary 2
3. Source Description 6
Process description 6
Materials flow 21
Geographic distribution 24
4. Emissions 25
Selected pollutants and their characteristics . . 25
Emission factors 25
Definition of a representative source 28
Environmental effects 28
5. Control Technology 36
Hydrocarbons 36
Hydrogen chloride 41
Particulates (talc) 41
6. Growth and Nature of the Industry 50
Present technology 50
Emerging technology 50
Industry production trends 50
References 53
Appendices
A. Calculation of emission height 57
B. Individual plant emission rates 61
C. Derivation of source severity equations 64
D. Comments by E. I. du Pont de Nemours & Company on
draft source assessment document: polychloroprene
state-of-the-art 78
Glossary 83
IX
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FIGURES
Number Page
1 Chloroprene process flow diagram 9
2 Schematic flow diagram for the disposal of
chlorinated hydrocarbon wastes ... '
3 Schematic diagram of the Incinerator-Scrubber . . j.4
4 Neoprene process flow diagram 18
5 Chloroprene process material balance 22
6 Neoprene process material balance 23
7 Locations of polychloroprene (neoprene) plants . . '4
8 Hydrocarbon concentration as a function of distance
downwind from a representative plant 35
9 Particulate concentration as a function of distance
downwind from a representative plant 35
10 Brine-cooling system for neoprene strippers ... 37
11 Combined control system for batch polykettles . . 39
12 Falling film absorption system 42
13 Centrifugal spray scrubbers 45
14 Impingement plate scrubber 46
15 Venturi scrubber 46
16 Centrifugal fan wet scrubber 48
17 Neoprene product and consumption trends 52
x
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TABLES
Number Page
1 Neoprene and 3,4-Dichloro-l-butene Plant
Locations 2
Source Severities and Emission Factors for a
Representative Plant 5
Physical Properties of Chloroprene, Its Inter-
mediates and Raw Materials 8
4 Polymerization Recipe for Neoprene 19
5 Differences in Neoprene Types 21
6 Neoprene Plant Locations 24
7 Characteristics of Emissions from Neoprene
Manufacturing Plants 26
8 Neoprene Manufacturing Emission Factors by
Compound 26
9 Neoprene Manufacturing Emission Factors 27
10 Time-Averaged Maximum Ground Level Concentrations
by Compound 29
11 Time-Averaged Maximum Ground Level Concentrations . 30
12 Source Severities for Criteria Pollutants and
Chemical Species 31
13 Source Severities 32
14 Contribution of Neoprene Production to State
Emissions of Criteria Pollutants 33
15 Contribution of Neoprene Production to 1976
National Emissions of Criteria Pollutants .... 34
16 Affected Area and Affected Population 34
17 Control Devices and their Efficiencies in the
Neoprene Industry 40
18 Neoprene End Uses 51
XI
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ABBREVIATIONS AND SYMBOLS
D -- distance from the source to the nearest plant
boundary
e -- 2.72
E -- emission factor, g/kg
F -- hazard factor
H -- emission height, m
H -- average emission height, m
P -- production rate, kg/s
Q -- mass emission rate, g/s
S -- source severity
t -- averaging time
tQ -- short term averaging time
TLV® — threshold limit value
u -- wind speed, m/s
u -- average wind speed, m/s
y -- horizontal distance from centerline of dispersion, m
X — downwind ground level concentration at reference
coordinate x and y
^max -- maximum ground level concentration
X -- mean ambient concentration
Xmax ~~ time-averaged maximum ground level concentration
AP -- change in pressure
TT — 3.14
Oy -- standard deviation of horizontal dispersion, m
az -- standard deviation of vertical dispersion, m
XII
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CONVERSION FACTORS AND METRIC PREFIXES'"
To convert from
degree Celsius (°C)
gram/kilogram (g/kg)
kilogram (kg)
meter (m)
meter (m)
meter2 (m2)
meter3 (m3)
metric ton
pascal (Pa)
pascal (Pa)
second (s)
CONVERSION FACTORS
to
degree Fahrenheit (°F)
pound/ton
pound-mass (Ib mass
avoirdupois)
foot
inch
mile2
foot3
ton (short, 2,000 Ib mass)
inch of water (60°F)
pound-force/inch2 (psi)
minute
Multiply by
t0p = 1.8
2.000
2.205
3.281
3.937 x 101
3.861 x 10~7
3.531 x 101
1.102
4.019 x 10~3
1.450 x IQ-1*
1.667 x 10~2
+ 32
Prefix
Symbol
kilo
mi Hi
micro
nano
k
m
y
n
PREFIXES
Multiplication
factor
10 3
10-3
10
-6
10
,-9
Example
1 km = 1 x 103 m
1 mm = 1 x 10~3
1 ym = 1 x 10~6
1 nm = 1 x 10~9
m
m
m
Metric Practice Guide. ASTM Designation: E 380-74, American Society for
Testing and Materials, Philadelphia, Pennsylvania, November 1974. 34 pp.
Xlll
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SECTION 1
INTRODUCTION
Polychloroprene, generically called "neoprene," is produced in
two process stages. In the first stage, the monomer preparation
stage, butadiene is chlorinated, isomerized, and dehydrochlori-
nated to produce the monomer, chloroprene. The second stage con-
sists of the emulsion polymerization of chloroprene to form
neoprene latex. This latex is then processed and the resulting
polymer isolated.
The purpose of this report is to assess the atmospheric emissions
from the manufacture of neoprene. This is accomplished by deter-
mining the type, quantity, and location of emissions in the neo-
prene production process. The information in this document has
been taken from the open literature, contacts with pertinent
government agencies, and personal communications with representa-
tives of the neoprene industry.
The principal findings of this study are summarized in Section 2.
Section 3 describes the production of neoprene from the chlori-
nation of butadiene to the final stages of roping and bagging the
neoprene polymer. Section 4 provides data on emissions: their
composition, quantity, and location, ground level concentrations,
source severities, and affected population. The control of emis-
sions from neoprene manufacture is described in Section 5, while
the growth and nature of the industry is discussed in Section 6.
-------
SECTION 2
SUMMARY
Polychloroprene, generically called "neoprene," is a synthetic
rubber. The monomer, chloroprene, is produced by chlorinating
butadiene to give a mixture of dichlorobutene isomers. These
isomers are converted by isomerization to 3,4-dichloro-l-butene,
which is dehydrochlorinated to chloroprene.
Chloroprene is polymerized in an emulsion polymerization system
using sodium rosinate as an emulsifying agent and potassium per-
sulfate as the initiator. The monomer batch is reacted until
65% to 100% of the chloroprene is polymerized. The emulsion, or
latex, is then treated with acetic acid. The sensitized latex
is passed over a freeze roll where the rubber is frozen and
formed into a sheet. Subsequently, the rubber is washed, dried,
roped, and bagged.
Neoprene is produced by two companies at three locations with a
combined capacity of 199 x 103 metric tons/yr. Refined chloro-
prene is also produced at these three locations, while 3,4-di-
chloro-l-butene is produced at two locations. Another plant in
Victoria, Texas produces only crude chloroprene. In Table 1,
1976 plant capacity data and plant locations for the manufacture
of neoprene and 3,4-dichloro-l-butene are presented.
TABLE 1. NEOPRENE AND 3,4-DICHLORO-l-BUTENE PLANT LOCATIONS (1)
Company
Capacity,
103 metric tons
Location
Product
Du Pont
Du Pont
Denka
Du Pont
Du Pont
Denka
36
136
27
177
118b
40°
La Place, LA
Louisville, KY
Houston, TX
La Place, LA
Victoria, TX
Houston, TX
Neoprene
Neoprene
Neoprene
3 , 4-Dichloro-l-butene
3 , 4-Dichloro-l-butene
3 , 4-Dichloro-l-butene
All 3,4-Dichloro-l-butene produced at this location is used in-
plant to produce crude chloroprene for shipment or as a feedstock
in nylon production.
DMRC estimate.
(1) Chemical Profile:
210(7)19, 1976.
Neoprene. Chemical Marketing Reporter,
-------
The neoprene industry has been adversely affected in recent years
by a shortage of chlorine and butadiene. Nevertheless, the
industry has grown at an average annual rate of 5% for the five
year period of 1972 through 1976. The increase in total emis-
sions did not parallel production increases. Two neoprene plants
have reduced their organic emissions by 50% to 90% to comply with
state regulations regarding the control of hydrocarbon emissions.
This reduction has been accomplished through process modifica-
tions and the improvement of equipment operating efficiencies.
For a 5 year period beginning in 1977, using an expected increase
of 5% per annum, production capacity in 1981 is expected to be
254 x 103 metric tons.
One plant is planning to further reduce hydrocarbon emissions 50%
by 1980 to comply with recent state regulations. An emission
growth factor has been determined for the neoprene industry from
the ratio of projected emissions in 1981 to the total emissions
in 1976. This ratio is given below:
1,479 metric tons in 1981 (emissions) Q _,
1,943 metric tons in 1976 (emissions)
On a statewide basis neoprene production accounts for 0.008% to
0.073% of the total hydrocarbons emitted in three states:
Kentucky, Louisiana, and Texas. Neoprene manufacture contributes
0.005% of the total national hydrocarbon emissions.
Emissions from neoprene manufacturing plants include hydrocarbons
(particularly chlorinated hydrocarbons), particulates (talc),
nitrogen oxides, and hydrogen chloride.
Hydrocarbon emissions such as chloroprene and toluene are emitted
from storage tanks, refining columns, wash belts, dryers, and
batch polykettles. Particulates are emitted during the dusting
of neoprene rope with talc, prior to bagging. Hydrogen chloride
emissions result from the incineration of waste chlorinated
hydrocarbons. Nitrogen oxides are emitted from vacuum column
jets.
A representative neoprene plant was defined as one based on the
chlorination of butadiene with an annual capacity of 95 x 103
metric tons. The annual production capacity of actual plants
ranges from 27 x 103 metric tons to 136 x 103 metric tons. A
severity factor was determined for each compound emitted. The
source severity, S, is defined as the_ ratio of the time-averaged
maximum ground level concentration, Xmax' (calculated by Gaussian
plume dispersion methodology) to the hazard factor, F, for each
material. F is defined as the ambient air quality standard for
criteria pollutants or as the corrected TLV© (i.e., TLV • 8/24
• 1/100) for noncriteria emissions. Source severity values of
1.0 and greater have been found for emissions of chloroprene
-------
and talc. Source severities greater than 1.0 were found for the
specific emission points: blend tanks, strippers, tank car
vents, polykettles, wash belts, and dryers.
Neoprene plants are located in counties with population densities
from 27 to 716 persons/km2. The number of persons exposed to a
given severity factor was calculated using this population data
in a Gaussian plume dispersion model. For an average county pop-
ulation density of 378 persons/km2, a representative plant ex-
poses 1,234 persons to a total hydrocarbon severity factor of 1.0
or greater. A source severity for particulates emitted by a rep-
resentative plant indicates that 153 persons are affected by a
ground level concentration of pollutant, Xmax' f°r which \/F >0.1.
Emission points, emission factors, source severities, and spe-
cific chemical substances emitted are given in Table 2.
Control technology for emissions from neoprene manufacture in-
volves the abatement of hydrocarbons, particulates (talc), and
hydrogen chloride. Hydrocarbon emissions have been reduced
through a combination of process modifications, brine-cooling
systems, water-spray chambers, oil absorption units, flares, and
nitrogen blankets in pressurized storage tanks. Hydrogen chloride
emissions are controlled with falling film absorbers and packed
scrubbers. Particulates emitted in the talc dusting area may be
controlled by exhaust systems in conjunction with wet scrubbers
or fabric filters.
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TABLE 2. SOURCE SEVERITIES AND EMISSION FACTORS
FOR A REPRESENTATIVE PLANT
Emission rates,
Material emitted metric ton/yr
Criteria pollutants
Particulate
Bagger exhaust
NOX
Vacuum column jet
Hydrocarbons
Jet vent scrubber
Dichlorobutene storage
Isomerizer reactor vent
Aqueous waste vent
Refined chloroprene tanks
Chloroprene vent condenser
Vacuum column jet
Recycle chloroprene tank
Blend tanks
Batch polykettles
Stripper
Emulsion storage tank
Tank car vents
Wash belts
Dryer exhaust
Process wastewater
Chemical substances
Butadiene
Chloroprene
Dichlorobutene
Dodecyl mercaptan
Toluene
Dimer
Tetrachlorobutane
Talc
Nitrogen dioxide
Miscellaneous chemicals
Acetic acid
18
0.
731
21
0.
0.
0.
41
1.
27
0.
20
105
62
16
20
18
390
3.
4.
400
2.
1.
219
83
0.
18
0.
27
0.
09
3
7
6
1
3
8
5
4
0
03
1
2
Emission
factor,
g/kg
0.
0.
7.
0.
0.
0.
0.
0.
0.
0.
0.
0.
1.
0.
0.
0.
0.
4.
0.
0.
4.
0.
0.
2.
0.
0.
0.
0.
0.
0.
19
001
7
23
003
007
006
43
01
29
003
21
1
65
17
21
19
1
04
05
2
025
Oil
3
87
0003
19
001
28
003
Source
severity
0
0
23
0
0
0
0
0
0
0
0
4
1
1
0
2
6
1
0
0
4
0
3
0
0
a
.03
a
.1
b
.15
.3
.2
.03
.4
.1
.4
.008
.5
.6
.5
.3
.0
.7
.6
.4
.0004
•3c
c
.4,,
c
c
.4
.1
-
.0003
Primary ambient air quality standard was used to calculate source
severity.
There is no primary ambient air quality standard for hydrocarbons.
The value of 160 pg/m3 used to calculate source severity for hydro-
carbons in this report is a recommended guideline for meeting the
primary ambient air quality standard for photochemical oxidants.
'Threshold limit value data not available, hence no source severity
calculated.
5
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SECTION 3
SOURCE DESCRIPTION
Polychloroprene is a commercial, synthetic elastomer produced by
the emulsion polymerization of 2-chloro-l,3-butadiene (chloro-
prene). Polychloroprene has the generic name "neoprene" (2).
Neoprene is marketed in both dry and latex forms (3). Domes-
tically, two companies (Du Pont and Denka) have combined
capacities of 199 x 103 metric tons at three plant locations.
The monomer, chloroprene, is used solely for the production of
neoprene via a continuous process. Since 1972, all chloroprene
production has been based on the chlorination of butadiene (4).
Monomer production and chemistry, the commercial route, and the
polymerization are discussed in the following process description.
Since this information has been taken from the open literature,
the details may vary from actual current commercial practices.
PROCESS DESCRIPTION
Monomer Production
Chemistry--
The production of chloroprene from butadiene depends on three
steps: chlorination, isomerization, and dehydrochlorination (2).
The chlorination of butadiene is a vapor-phase addition reaction:
CH2=CH-CH=CH2 + C12 -»- CH2-CH-CH=CH2 + C1CH2-CH=CH-CH2C1 (1)
Cl Cl
(2) Kennedy, J. P. Polymer Chemistry of Synthetic Elastomers.
Interscience Publishers, New York, New York, 1968. pp. 227-
252.
(3) Kirk-Othmer Encyclopedia of Chemical Technology, Second Edi-
tion, Vol. 7. John Wiley and Sons, Inc., New York, New York,
1967. pp. 705-716.
(4) Brownstein, A. M. U.S. Petrochemicals, Technologies, Market;
and Economics. The Petroleum Publishing Company, Tulsa,
Oklahoma, 1972. pp. 258-260.
-------
The product is 60% 3,4-dichloro-l-butene and 40% 1,4-dichloro-2-
butene (both ois and trans forms) (2). Side reactions include
substitution chlorination, over-chlorination, and thermal dehy-
drochlorination (5). Principal byproducts include chloroprene,
1-chloro-l,3-butadiene, hydrogen chloride, and high boilers
(mainly tetrachlorobutane) (6-8).
The second step involves the isomerization of 1,4-dichloro-2-
butene to 3,4-dichloro-l-butene:
catalyst
C1CH2-CH=CH-CH2C1 > CH2-CH-CH=CH2 (2)
Cl Cl
A copper-based catalyst, copper metal/cupric chloride (Cu-CuCl2),
is used commercially for the isomerization. Other catalysts that
can be used include ferric, titanium (III), and aluminum chlo-
rides, as well as other copper compounds (9).
The final step entails the dehydrochlorination of 3,4-dichloro-l-
butene to chloroprene (1):
C1CH2-CH-CH=CH2 + NaOH -> CH2=C-CH=CH2 + NaCl + H2O (3)
Cl Cl
(5) Bellringer, F. J., and C. E. Hollis. Make Chloroprene from
Butadiene. Hydrocarbon Processing, 47 (11):127-130, 1968.
(6) Crocker, H. P., C. W. Capp, and F. J. Bellringer. Process
for the Production of Dichlorobutenes. British Patent
798,027 (to The Distillers Company, Ltd.), July 16, 1958.
(7) Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 5. John Wiley and Sons, Inc., New York,
New York, 1967. pp. 215-231.
(8) Bellringer, F. J., and H. P. Crocker. Preparation of
3,4-Dichloro-l-butene. British Patent 800,787 (to The Dis-
tillers Company, Ltd.), September 3, 1958.
(9) Sachowicz, S. K. Production of Chloroprene. U.S. Patent
3,026,360 (to The Distillers Company, Ltd.), March 20, 1962.
7
-------
The product contains 2% to 3% 1-chloro-l,3-butadiene (based on
3,4-dichloro-butene) (9). Table 3 (2, 5, 10-12) lists the physi-
cal properties of chloroprene, chloroprene intermediates, and
byproducts.
TABLE 3. PHYSICAL PROPERTIES OF CHLOROPRENE, ITS
INTERMEDIATES AND RAW MATERIALS (2, 5, 10-12)
Molecular
weight,
Compound g/g-mole
Chloroprene
1-Chloro-l , 3-butadiene
3 ,4-Dichloro-l-butene
eis-l,4-Dichloro-2-butene
trans-l,4-Dichloro-2-butene
Butadiene
Chlorine
1,1,1, 2-Tetrachlorobutane
1,2,2, 3-Tetrachlorobutane
1,2,3, 3-Tetrachlorobutane
88.54
88.54
125.0
125.0
125.0
54.09
70.91
195.91
195.91
195.91
Normal
boiling
point, °C
59.4
69
123
152.5
155.5
-4.41
-34.6
134.5
182
q,,32 mm Hg
Melting
point, °C
-130±2
N.A.9
N.A.
-48
1 to 3
-108.9
-101.6
N.A.
-48 to -46
N.A.
Specific
gravity
0.958^-
0.96UJ-
N.A.
1.88^-
1.83^-
0.621^-
2.49°>b
(vapor)
1.39343-
1.428-Ur
1.420^-
TLV,
mg/m
90
N.A.
N.A.
N.A.
N.A.
2,200
3
N.A.
N.A.
N.A.
Not available.
Referenced to air.
Process--
Figure 1 is a flow diagram for the commercial manufacture of
chloroprene. Commercial-grade butadiene and chlorine are fed in
a ratio of at least one mole of butadiene to one mole of chlorine
(6, 13). The preferred ratios of butadiene to chlorine are from
(10) TLVs® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1976. American Conference of Governmental
Industrial Hygienists, Cincinnati, Ohio, 1976. 97 pp.
(11) Chemical Engineers' Handbook, Fourth Edition. J. H. Perry
and C. H. Chilton, eds. McGraw-Hill Book Company, New York,
New York, 1963.
(12) Handbook of Chemistry and Physics. R. C. Weast, ed. CRC
Press, Cleveland, Ohio, 1973.
(13) E. I. du Pont de Nemours and Company. Production of Dichlo-
robutenes. British Patent 661,806, November 28, 1951.
-------
(0
to
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o
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-------
3:1 to 6:1, respectively (13). The amount of tetrachlorobutanes
increases progressively at ratios of less than 3:1; at ratios
greater than 6:1, the problem of recycling unreacted butadiene
increases (13). The butadiene is preheated to a temperature
between 150°C to 300°C to assure a complete vapor-phase reaction
system and to control the products of the reaction (6, 13). The
butadiene and chlorine feed streams are mixed with recycled buta-
diene and hydrogen chloride before being introduced into the
reactor. The hydrogen chloride concentration in the reactor feed
is at least 5% by volume, but, preferably, is between 30% and 50%
by volume (14). The recycling of hydrogen chloride eliminates
the necessity of providing a scrubber and butadiene dryer large
enough to process the entire butadiene recycle stream (14).
The chlorinator is a glass- or ceramic-lined tubular reactor or a
series of such reactors of increasing cross-sectional area. Al-
though chlorination catalysts, packing materials, or other con-
tact substrates may be used in the chlorinator, they offer no
advantage and may, in fact, be detrimental (6, 13). Such mater-
ials promote the formation of carbon and other deposits on their
surfaces causing reactor blockages (6). The direction of flow of
the reactants is downward to minimize deposition of carbonaceous
materials (13).
Reactor conditions are important. The temperature of the initial
reaction zone is between 140°C and 220°C (13) and increases to
between 280°C and 400°C in the final reaction zone (6, 13, 14).
Reactor pressure is atmospheric (100 kPa) (6, 13, 14). Holdup
time in the reactor is less than 12 s (6, 14). For reactors of
increasing cross-sectional areas, the space velocity in the ini-
tial reaction zone is between 1,500 and 100,000 volumes of gas
(at standard temperature and pressure) per volume of initial
reaction zone per hour. The space velocity in the final reaction
zone is between 30 hr"1 and 300 hr~1 (13). Dichlorobutene yields
across the chlorinator range from 87% to 95% (mole basis) based
on chlorine feed (6, 13).
The products from the chlorinator are condensed and sent to a de-
gasser where inerts are removed from the reaction mixture. Buta-
diene and hydrogen chloride are taken overhead for recycle (15).
A portion of the overhead stream is sent to a water scrubber to
remove hydrogen chloride and, hence, prevent its buildup in the
reactor inlet stream. The butadiene from the scrubber is dried
(14) Bellringer, F. J., and H. P. Crocker. Production of
Dichlorobutenes. British Patent 798,028 (to The Distillers
Company, Ltd.), July 16, 1958.
(15) Prescott, J. H. Butadiene to Neoprene Process Makes U.S.
Debut. Chemical Engineering, 78 (3):47-49, 1971.
10
-------
and recycled to the reactor. A bleed is taken from the scrubber
to purge the inerts from the system. The remainder of the over-
head stream from the degasser is recycled directly to the
chlorinator (14).
The bottoms stream from the degasser containing dichlorobutenes
is sent to a fractionating column. Pure 3,4-dichloro-l-butene
distilled off the top of the column goes directly to the dehydro-
chlorinator. The bottoms stream from the column containing
1,4-dichloro-2-butene is sent to the isomerizer where 1,4-dichlo-
ro-2-butene is converted to 3,4-dichloro-l-butene.
A copper-based catalyst (Cu-CuCl2) is used as the isomerization
catalyst (4, 5, 7, 15-17). The isomerizer is operated at a
temperature of 123°C and atmospheric pressure (5). The desired
product, 3,4-dichloro-l-butene, is continuously distilled and
sent back to the fractionating column for purification. A purge
stream is taken from the isomerizer pot to remove high boilers
from the system (4, 5, 15).
The 3,4-dichloro-l-butene, which is sent from the fractionating
column to the dehydrochlorinator,is converted to chloroprene.
The reaction mixture is two-phase. The aqueous phase contains
10% to 20% sodium hydroxide, and the organic phase is 3,4-dichlo-
ro-l-butene. The reaction is carried out at a temperature above
the boiling point of chloroprene (^60°C), which allows removal of
the chloroprene as it is formed. Yields are 94% (18).
The chloroprene stream is then fractionated to remove 1-chloro-
1,3-butadiene and 3,4-dichloro-l-butene from the final product.
These byproducts are incinerated. The aqueous phase from the
dehydrochlorinator is stripped to remove 3,4-dichloro-l-butene
and then disposed as waste.
Aqueous wastes from the process contain hydrogen chloride and
sodium chloride. Waste chlorinated hydrocarbons are disposed
through incineration, followed by scrubbing of hydrogen chloride
from the incinerator exhaust gases. A schematic flow diagram
for the disposal of chlorinated hydrocarbon waste is shown in
(16) Bellringer, F. J. Production and Stabilisation of Dichloro-
butene. British Patent 877,586 (to The Distillers Company,
Ltd.), September 13, 1961.
(17) Capp, C. W. Improvements in the Production of Dichloro-
butenes. British Patent 984,094 (to The Distillers Company,
Ltd.), February 24, 1965.
(18) Bellringer, F. J. Preparation of Chloroprene. British
Patent 798,205 (to The Distillers Company, Ltd.), July 16,
1958.
11
-------
Figure 2. One neoprene plant recovers the hydrogen chloride from
the gas stream for reuse (19).
The incinerator section of the disposal system has been patented
by Thermal Research and Engineering Corporation. A schematic
diagram is presented in Figure 3. The incinerator consists of a
burner and a quencher. The burner is an air-atomized vortex
burner which is capable of atomizing the chlorinated hydrocarbon
waste to about 40 nm. Chlorinated hydrocarbon wastes containing
less than 70% chlorine will burn without auxiliary fuel. Wastes
containing 20% to 30% chlorine have heating values of 23 kJ/kg to
28 kJ/kg and are capable of producing 1,930°C flame temperatures
without auxiliary fuel. From 30% to 70% chlorine, hating values
decline to 10 kJ/kg to 12 kJ/kg, and flame temperature 3 ci^j. line
to 1370°C. Auxiliary fuel is required to maintain fl ie tempex .-
tures in the range of 1,370°C to 1,930°C. Wastes contai.iluy mo^e
than 70% chlorine will not support combustion. In this 0^31; the
auxiliary fuel provides:
• heat required for waste decomposition
• flame temperatures of 1,370°C to 1,930°C
• hydrogen to prevent formation of chlorine
The quencher used in the incinerator section is unique in design
since it must protect the processing equipment from damage by the
1,930°C flame temperatures. Flames from the burner are quenched
in a 27% hydrochloric acid solution. Gases leave the quencher at
149°C to 371°C. The quencher is constructed of impervious
graphite (Karbate®) to prevent corrosion.
The hydrogen chloride recovery section has been patented by Union
Carbide. Quenched gas from the incinerator section is passed
through primary, secondary, and tertiary falling film absorbers.
Of the hydrogen chloride formed in the incinerator, 99% is
recovered as 27% hydrochloric acid. Gases from the tertiary
absorber enter a vent scrubber designed to reduce hydrogen chlo-
ride emissions to 50 ppm or 3 ppm when using water or dilute
caustic, respectively, for the scrubbing liquid. The overall
hydrogen chloride collection efficiency of the absorbers and the
vent scrubber is 99.96% when using dilute caustic in the vent
scrubber.
The 27% hydrochloric acid can be upgraded to anhydrous hydrogen
chloride containing less than 50 ppm H20 in Union Carbide equip-
ment. A conventional packed column stripper is used to convert
[19) Hot Option for the Disposal of Hydrocarbon Wastes. Chemical
Week, 110(16):37-38, 1972.
12
-------
C
CO
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-P
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13
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AUXILIARY'FUELGAS
( IF REQUIRED
CHLORINATED
HYDROCARBON
COMBUSTION AIR
WATER -
SPRAYS
POLYPROPYLENE
DEMISTER-
IMPERVIOUS
GRAPHITE
LINING
DOWNCOMER
27% HCi SOLUTION
Figure 3. Schematic diagram of the Incinerator-Scrubber.
the 27% hydrochloric acid to 75% to 80% vapors. These vapors are
cooled to about 16°C to yield 99% hydrogen chloride vapors, which
are further cooled to -12°C in a brine condenser to reduce water
content to 50 ppm.
Polymer Production
Chemistry--
The conversion of chloroprene to neoprene is accomplished by free
radical-initiated emulsion polymerization (2, 3, 20). Emulsion
polymerization is a heterogeneous reaction system with a continu-
ous aqueous phase and a dispersed monomer phase. It differs from
suspension polymerization in that the initiator is located in the
aqueous phase (21).
The ideal emulsion polymerization system contains water, a water-
insoluble monomer (i.e., chloroprene), an emulsifier, and a free
radical initiator. In dilute aqueous solution at concentrations
(20) Hollis, C. E. Chloroprene and Polychloroprene Rubbers.
Chemistry and Industry (London), (31):1030-1041, 1969.
(21) Billmeyer, F. J. Textbook of Polymer Science. Interscience
Publishers, New York, New York, 1966. pp. 343-347.
14
-------
above the critical micelle concentration, the emulsifier mole-
cules form aggregates of about 100 molecules. These micelles
are roughly spherical in shape with the hydrophobic portion of
each molecule directed toward the micelle center. The average
micelle is colloidal, with a diameter of 5 nm. For typical emul-
sifier concentrations, one cubic centimeter of solution will con-
tain about 1018 micelles. The addition of monomer with agitation
results in the monomer being dispersed in the form of droplets
stabilized by the emulsifier. These droplets are usually about
1 ym in diameter. A small amount of monomer (^1%) is solubilized
by the micelles, which swell to twice their original size (22).
The free radical initiator is generated in the water phase.
About 1013 free radicals/cm3-s may be produced from the persul-
fate initiator at 50°C; hence, within a short time radicals will
contact the monomer-swollen micelles and initiate polymerization.
After initiation a new phase is produced, namely, a polymer latex
particle swollen with monomer. Thus, in the ideal system, poly-
merization takes place only in the monomer-swollen micelles (22).
After initiation, polymerization inside the micelles continues
and the latex particles grow. The emulsifier is adsorbed by the
latex particle and acts as a protective colloid, preventing the
particles from flocculating. The adsorption of the emulsifier
upsets the equilibrium between the dissolved emulsifier and the
emulsifier in the nonactivated micelles. Consequently, the non-
activated micelles disintegrate to restore the equilibrium. After
10% to 20% conversion to polymer, the nonactivated micelles have
disappeared and all of the emulsifier is adsorbed on the latex-
water interface; subsequently, no new latex particles can be
formed. Hence, the number of latex particles is fixed (vL015/cm3)
and further polymerization occurs only inside these particles
(22).
Polymerization is maintained by the diffusion of monomer from the
monomer droplets through the aqueous phase. Monomer droplets de-
crease in number until they disappear completely at a conversion
of about 60%. Subsequently, as the monomer in the latex particle
is gradually used, the polymerization rate progressively de-
creases. Polymerization stops when all of the monomer in the
particle is consumed (22).
In practice a chain-transfer agent is added to regulate the poly-
mer chain length without affecting the rate of polymerization. A
chain-transfer agent is a material that stops the growth of one
polymer chain and, in doing so, becomes the initiating species.
Thus, higher concentrations of chain-transfer agent will lower
(22) Encyclopedia of Polymer Science and Technology. H. F. Mark,
ed. John Wiley and Sons, Inc., New York, New York, 1966.
pp. 801-827.
15
-------
the molecular weight because more polymer molecules will be
terminated. The rate of polymerization remains the same because
another polymer chain is started for each polymer (22).
Polymerization can continue until the monomer disappears (100%
conversion). Complete conversion is sometimes undesirable be-
cause of latex instability, gel formation (cross linking), or
branched polymer formation. In these cases, the polymerization
reaction is stopped by the addition of a "shortstop" at the de-
sired conversion. The action of the shortstop must be immediate
and final. It must not only stop the conversion at the polymeri-
zation stage but also prevent further conversion at later proces-
sing steps. Thus, it must terminate the free radicals in the
aqueous phase and in the latex particles themselves (22).
In general, the emulsion polymerization of chloroprene is similar
to the ideal system. Unlike the ideal system, initiation in
chloroprene emulsions is not restricted to the micelles or latex
particles, but can also occur in the dissolved monomer or at the
water-monomer interface (2).
Various surfactants can be used as emulsifiers in chloroprene
polymerization. Anionic surfactants of the rosin acid, fatty
acid, or alkyl sulfonate type are usually employed. Cationic
soaps (e.g., cetyl pyridinium bromide) may be used in the stabil-
ization of neutral or acidic emulsions of chloroprene. The com-
mercial practice is to dissolve wood rosin in the chloroprene
phase and sodium hydroxide in the aqueous phase and, thus, form
the emulsifier, sodium rosinate, -In situ (2). The critical
micelle concentration for sodium rosinate is less than 10 moles/m3
at 50°C (23) . The sodium salt of the naphthalenesulfonic acid/
formaldehyde condensation product is added in commercial pro-
cesses to stabilize the latex when it is acidified for polymer
isolation (2).
Chloroprene can be polymerized by a variety of free radical ini-
tiators such as hydroperoxides (not peroxides) azo compounds, re-
active boron compounds, nitrogen sulfides, and nitrogen-containing
sulfinic acids. These common initiators are unsatisfactory in
the polymerization of chloroprene for the following reasons:
1) they are known to cause crosslinking, 2) they do not always
give uniform products and reproducible reaction rates, 3) they
have a low water solubility, 4) they do not produce the electro-
lytes that are necessary to stabilize the latex against gel
formation, 5) they are expensive, 6) they can be hazardous in
large quantities, and 7) they are sensitive to the inhibitors
used to stabilize the chloroprene. In the latter example there
(23) Fryling, C. F. Emulsion Polymerization Systems. In: Syn-
thetic Rubber, G. S. Whitby, C. C. Davis, and R. F. Dunbrook,
eds. John Wiley and Sons, Inc., New York, New York, 1954.
pp. 224-258.
16
-------
is usually an induction period followed by a sudden exothermic
polymerization which can be hazardous on a commercial scale.
Conversely, potassium persulfate (peroxodisulfate), which is used
in commerce, does not promote crosslinking, gives uniform pro-
ducts and reproducible reaction rates, is water soluble, produces
an electrolyte that stabilizes the final latex, is inexpensive,
is safe to handle in large quantities, and is insensitive to in-
hibitors used in the chloroprene (23 and personal communications
with P. Hamed, Monsanto Industrial Chemicals Co., Akron Marketing
and Research Center, Akron, Ohio, 7 July 1977 and G. A. Richard-
son, Monsanto Research Corporation, Dayton, Ohio, 7 July 1977).
Molecular weight can be controlled with chain transfer agents
such as alkyl mercaptans, diethyl xanthogen disulfides, dialkyl-
thiuram disulfides, and iodoform. Commercially, dodecyl mercap-
tans are used to control molecular weight (2). Dodecyl mercaptan
also may serve as a reductive initiator in the presence of potas-
sium persulfate, producing a "redox" catalyst system frequently
used in emulsion polymerization (23).
Conversion is controlled by using free radical inhibitors as
shortstops. These include thiurams, oxalate anions, aromatic
amines, phenolic compounds, and N,N-dialkylhydroxylamines (2).
Lower alkyl (usually methyl or ethyl) tetraalkylthiuram disul-
fides are most commonly used in commercial practice (24).
Process--
Figure 4 is a block diagram for the commercial manufacture of
Neoprene GN, which is typical of the process for the dry types
and for neoprene latexes (24). The process is semicontinuous
with the polymerization being a batch operation and the remainder
of the process being continuous (15).
Feed to the polykettle consists of two streams - an organic
stream and an aqueous stream. Table 4 gives the composition of
these streams. (Sulfur, added as a "modifier," acts as a comon-
omer.) These two streams are emulsified at 38°C by recirculating
the mixture through a centrifugal pump. The dispersed monomer
droplets are ^3 ym in diameter (3, 15).
The reactor is an agitated, 18 m3, glass-lined polykettle jac-
keted to provide temperature control. Hot water is used ini-
tially on the jacket to supply the necessary activation energy.
The polymerization reaction is exothermic (88.3 ± 6.7 kJ/mole of
chloroprene), and the hot water is changed to brine at -15°C
after the reaction starts. The reactor is controlled at 40°C ±
1°C by the brine and by varying the agitator speed (3, 15).
(24) Neal, A. M., and L. R. Mayo. Neoprene. In: Synthetic
Rubber, G. S. Whitby, C. C. Davis, and R. F. Dunbrook, eds.
John Wiley and Sons, Inc., New York, New York, 1954.
pp. 767-793.
17
-------
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TABLE 4. POLYMERIZATION RECIPE FOR NEOPRENE (24)
(based on 100 parts by weight of chloroprene)
Parts by
Feed materials weight
Aqueous
Water 150
Sodium hydroxide 0.8
Sodium salt of naphthalenesulfonic
acid/formaldehyde condensation product 0.7
Potassium persulfate 0.2 to 1.0
Organic
Chloroprene 100
N Wood rosin 4
Sulfur 0.6
The reaction is followed by monitoring the change in specific
gravity of the emulsion. At a specific gravity of 1.069 (91%
chloroprene conversion), the latex is drained by gravity from the
reactor. If a G-type neoprene is desired, the latex is taken to
a second reactor for peptization (chemical plasticization) with
tetraethylthiuram disulfide. The tetraethylthiuram disulfide
breaks some of the sulfur linkages of the chloroprene-sulfur co-
polymer formed in the polykettle. The latex is cooled to 20°C
and aged for about 8 hr to allow the tetraethylthiuram disulfide
to plasticize the polymer. The tetraethylthiuram disulfide also
acts as a stabilizer in the finished dry polymer (3, 15).
Shortstop ingredients and stabilizing agents are added to the
non-G-type latex during the final stage of polymerization. Tol-
uene is also added to help dissolve these compounds in the latex
(personal communications with T. M. Nichols/ Jr., E. I. du Pont
de Nemours and Company, Wilmington, Delaware, September 1977).
The latex is steam stripped to remove unreacted monomer (10% to
40% of the solution). The chloroprene is recycled to the chloro-
prene purification column in the monomer unit (15), while the
latex is sent to the neutralizer.
Toluene is added prior to the neutralization of G-type neoprene
to aid in dissolving shortstop ingredients and stabilizing agents
in the latex (personal communications with T. M. Nichols, Jr.,
E. I. du Pont de Nemours and Company, Wilmington, Delaware,
September 1977) .
In the neturalizer, the pH of the latex is adjusted to 5.5 to 5.8
using 10% acetic acid. Acetic acid decomposes the emulsifying
19
-------
agent, sodium rosinate, and arrests the alkaline plasticizing
action. The latex is then ready to be coagulated (2, 3, 15, 25).
The latex is processed into a sheet by the use of a freeze roll,
2.74 m in diameter and 2.74 m wide, which rotates partially sub-
merged in the latex. The roll is rotated by a motor at a
peripheral speed of 11 m/min. A doctor blade scrapes the coagu-
lated film from the roll. The roll is maintained at a surface
temperature of -5°C as it leaves the latex by circulating -12°C
brine through the roll. The latex is approximately 35% neoprene
by weight. Film thickness can be controlled by brine temperature
and depth of the roll in the latex. Typical film thickness is
8.9 mm to 10.2 mm (25).
The neoprene film is washed on a belt to replace the serum in the
film pores with water. The 2.84 m wide wash belt is composed of
woven 18-8-stainless steel, and is driven by a motor with vari-
able speed drive. Filtered wash water at 30°C is sprayed on the
film from stainless steel weirs and is drawn through the film by
a slight vacuum (AP = 370 Pa to 620 Pa) (25).
The washed film leaves the belt by a stripper roll and goes to
squeeze rolls which operate at a peripheral speed approximately
3 m/min faster than the wash belt in order to strip the film from
the wash belt. A squeeze roll unit consists of two horizontal
squeeze rolls made of steel with a rubber cover and topped by
40 mm of felt and covered with cloth. The rolls are adjusted to
give a pressure of about 103 kPa. The resulting water content of
the film is 25% to 30% on a dry basis (25).
The washed film is then dried by a multipass air layer dryer.
The neoprene film is carried through the dryer by a conveyor.
The conveyor speed may be altered from 11 m/min to 34 m/min and,
in general, is operated about 1.8 m/min to 2.4 m/min slower than
the squeeze rolls, since the film shrinks during drying. The
film is dried at about 120°C for 6 min to 8 min by air from ten
heating units. The last two sections of the dryer consist of the
cooling compartment operating at about 50°C. They are insulated
at the junction with the drying compartment. Dried product con-
tans less than 1% volatile material (2, 25).
The dried film is formed into a 19 mm diameter rope by a roping
machine. As the film leaves the dryer, two fingers of the roper
guide it into the groove of a female roll. A male roll compres-
ses the film into rope-form (25).
Finally, the rope passes into a cutter. Each cutter can handle
three ropes simultaneously. The rope is drawn through two draw-
ing discs which cut it into 0.35 m lengths. The cuttings pass
(25) Youker, M. A. Continuous Isolation of G.R.M. from Latex.
Chemical Engineering Progress, 43 (8):391-398, 1947.
20
-------
to a bagging machine in which they are dusted with talc to
facilitate handling, and loaded into 22.7 kg bags for shipment
(25, 26).
The basic process for Neoprene GN is modified to produce other
grades of neoprene. Unmodified grades are polymerized without
sulfur or sulfur-containing compounds in the recipe and conse-
quently do not require peptization. These grades are the "W"
type neoprenes that differ from the modified "G" type neoprenes
by possessing a narrower molecular weight distribution. Table 5
lists the grades of neoprene and the differences in their poly-
merization (27). Latex forms of neoprene are produced in a simi-
lar manner but do not undergo acidification or coagulation (2).
TABLE 5. DIFFERENCES IN NEOPRENE TYPES (26)
Tetraethylthiuram
Neoprene Sulfur- disulfide
type modified stabilized Grade Other
GN
GN-A
CRT
W
WRT
AC
CG
KNR
S
Yes
Yes
Yes
No
No
No
Yes
Yes
No
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
General
General
General
General
General
Specialty
Specialty
Specialty
Specialty
Secondary aromatic amine
stabilizer
Nondiscoloring
Nondiscoloring
antioxidant
antioxidant
MATERIALS FLOW
A raw material balance for the manufacture of chloroprene is
given in Figure 5. Emission points in the chloroprene process
(Figure 5) are designated by letters contained in circles. The
emissions from these points are discussed in Section 4.
Figure 6 is a flowsheet and material balance for the neoprene
production facility contiguous to the monomer plant. Emission
points are designated as before. Emissions are discussed in
Section 4.
(26) Collins, A. M. U.S. Patent 1,967,865 (to E. I. du Pont de
Nemours and Company), July 24, 1934.
(27) Catton, N. L. The Neoprenes. E. I. duPont de Nemours and
Company, Wilmington, Delaware, 1953. 245 pp.
21
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-------
GEOGRAPHICAL DISTRIBUTION
Table 6 lists manufacturing companies, locations, capacities, and
county population densities for neoprene plants. Figure 7 is a
map locating these facilities.
One company (Du Pont) possesses 86% of the total domestic neo-
prene capacity. The majority of domestic neoprene capacity (68%
of total U.S. capacity) is concentrated at one plant in Louis-
ville, Kentucky.
TABLE 6. NEOPRENE PLANT LOCATIONS (1)
1976 capacity,
Company 103 metric tons/yr
Location
County population
density, persons/km2
Du Pont
Du Pont
Denka
TOTAL
36
136
27
199
La Place, LA
Louisville, KY
Houston, TX
27
716
390
DENKA, HOUSTON, TX
DUPONT,
LOUISVILLE, KY
DU PONT, LA PLACE, LA
Figure 7. Locations of polychloroprene (neoprene) plants,
24
-------
SECTION 4
EMISSIONS
SELECTED POLLUTANTS AND THEIR CHARACTERISTICS
The process mechanism and the formation of emissions from chloro-
prene and neoprene manufacturing facilities have been described
in Section 3. Based on that information, the atmospheric emis-
sions resulting from their manufacture are: 1) hydrocarbons from
raw materials, byproducts, and intermediates; 2) particulates
from the packaging of the final product; and 3) hydrogen chloride
from substitution chlorination of butadiene. Table 7 (11, 28,
29) lists these potential pollutants together with their toxicity,
health effects, and atmospheric reactivity.
The majority of the hydrocarbon species emitted are chlorinated
materials. Toxicity and health effect data on many of these are
nonexistent or extremely limited. Chloroprene, for example, is
the only one of these compounds with an established TLV. Chloro-
prene is itself under investigation as a possible carcinogen,
although no conclusive data have yet been obtained (28).
EMISSION FACTORS
The emission factors from neoprene manufacturing are given by
compound in Table 8. Emission factors for each emission point
in the neoprene process are given in Table 9. (Personal commu-
nication with R. Everhart, Air Pollution Control District at
Jefferson County, Louisville, Kentucky, May 1975; and with
T. M. Nichols, Jr., E. I. du Pont de Nemours and Company, Wil-
mington, Delaware, May 1977.)
Emission factors specific for 3,4-dichloro-l-butene production in
the neoprene plant were calculated using plant production capaci-
ties for 3,4-dichloro-l-butene and the emission rates shown in
Appendix B, Table B-l. All of the emission factors are given in
terms of unit weight of neoprene produced.
(28) Neoprene. Chemical Marketing Reporter, 207 (13):30-41, 1975.
(29) Sax, N. I. Dangerous Properties of Industrial Materials,
Reinhold Book Corporation, New York, New YOrk, 1968.
1258 pp.
25
-------
TABLE 7. CHARACTERISTICS OF EMISSIONS FROM NEOPRENE
MANUFACTURING PLANTS (11, 28, 29)
Compound
TLV, mg/m3
Health effects
Hydrocarbons
Butadiene
Chloroprene
1-Chloro-l,3-butadiene
3,4-Dichloro-l-butene
ois-1,4-Dichloro-2-butene
trans-1,4-Dichloro-2-butene
1,1,1,2-Tetrachlorobutane
1,2,2,3-Tetrachlorobutane
1,2,3,3-Tetrachlorobutane
Toluene
Acetic acid
Dodecyl mercaptan
Chloroprene dimer
Particulates
Talc
Hydrogen chloride
Nitrogen dioxide3
2,200 Eye irritant
90 Central nervous system depressant; under
, investigation as possible carcinogen
N.A. N.D.C
N.A. N.D.
N.A. N.D.
N.A. N.D.
N.A. N.D.
N.A. N.D.
IJ.A. N.D.
375 Causes headache, nausea, lack of appetite
in exposures <200 ppm
25 Caustic, irritating; can cause burns,
lacrymation and conjuctivitis
N.A. Toxic
N.A. N.D.-
10 Can produce pulmonary fibrosis
7 Eye and respiratory irritant
9 Exceedingly toxic; death may result from
edema several days aftar exposure;
100 ppm is dangerous for even short
exposure; 200 ppm is usually fatal.
Contribute to photochemical smog.
DNot available from the American Conference of Governmental Industrial Hygienists (ACGIH)
"No data.
Particulates are atmospherically stable.
TABLE 8. NEOPRENE MANUFACTURING EMISSION
FACTORS BY COMPOUND3
Compound
Emission factor,
gAg
Butadiene
Chloroprene
Dichlorobutene
Dodecyl mercaptan
Toluene
Acetic acid
Hydrogen chloride
Talc
Dimer
Nitrogen dioxide
Miscellaneous chemicals
Tetrachlorobutane
0.047
4.19
0.025
0.011
2.28
0.002
0.018
0.19
0.87
0.001
0.281
0.00027
Personal communications with R. Everhart
and T. M. Nichols, Jr.
26
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The emission factors for compounds and emission points specific
to 3 , 4-dichloro-l-butene production have been modified to account
for a given ratio of 1.5 parts by weight of 3 , 4-dichloro-l-butene
necessary to produce 1 part by weight of neoprene. To calculate
emission factors for emission points other than those specific to
3 , 4-dichloro-l-butene , the production capacities for neoprene
manufacturing plants were utilized.
DEFINITION OF A REPRESENTATIVE SOURCE
A representative source for neoprene manufacture was defined to
determine source severities for emission points anr1 compounds
emitted. The representative source was defined as <•. '"oprene
plant using butadiene technology for chloroprene p<-oci- ..0x0*1. TJ-<=
capacity was defined as 95 x 10* metric tons/yr, whic, ; . •.<
weighted average of the three actual neoprene plants. ' i s'loaxu
be noted that emissions from the manufacture of chic "os. • c.".-. . c
considered as part of the total emissions for neoprene :- • this
section. Emissions from chloroprene manufacture -an be dJstin-
guished by correlating the emission points shown ir Tab.! ^y "* ?
-------
for hydrocarbons and 24 hr for particulates) .
between Xmax and Xmax is expressed as (30):
X
max
xmax\t
- 17
The relationship
(5)
where
X
max
~
t0 = short term averaging time = 3 min
t = averaging time
_ and height of emissions data for each compound are presented
ih~Table 10. (Personal communication with R. Everhart.) Table 11
lists X™.,,, as a function of emission point.
TABLE 10. TIME-AVERAGED MAXIMUM GROUND LEVEL
CONCENTRATIONS BY COMPOUND9'"
Compound
Emission
height,r
m
xmax'
mg/m;
Butadiene
Chloroprene
Dichlorobutene
Dodecyl mercaptan
Toluene
Acetic acid
Hydrogen chloride
Talc
Dimer
Nitrogen dioxide
Miscellaneous chemicals
Tetrachlorobutane
27.4
13.3
6.7
13.5
15.4
17.4
12.8
11.6
19.8
3.0
3.0
3.0
0.004
1.3
0.03
0.003
0.53
0.0004
0.006
0.077
0.12
1.4
1.7
0.002
Calculated using emission factors and production
capacity for a representative plant.
It should be noted that Xmax is being calculated
for each compound as if emitted from a single
point source at a certain height and at a con-
stant rate. Actual neoprene plant conditions,
however, indicate that the compounds are emitted
from two or more points of varying heights. Emis-
sion rates from each point are not constant but
vary depending upon the nature of the process
step. Values for X
max
by compound should be con-
sidered as average values only.
'See Appendix A for calculation procedure.
(30) Turner, D. B. Workbook of Atmospheric Dispersion Estimates.
Public Health Service Publication No. 999-AP-26, U.S. De-
partment of Health, Education, and Welfare, Cincinnati,
Ohio, May 1970.
29
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Source Severity
To obtain an indication of the hazard potential of the emission
source, the source severity, S, was defined as:
S =
X
max
(6)
where F is the primary ambient air quality standard (AAQS) (or
guideline) for criteria pollutants and is a corrected threshold
limit value (TLV • 8/24 • 1/100) for noncriteria pollutants.
Source severity represents the ratio of time-averaged maximum
ground level exposure to the hazard level of exposure for a par-
ticular emission. Source severity equations were derived for
each pollutant as shown in Appendix C.
For each compound having an established AAQS, guideline, or TLV,
the source severity was calculated and is shown in Table 12.
Table 13 lists the source severities for each emission point for
each compound.
TABLE 12. SOURCE SEVERITIES FOR
CRITERIA POLLUTANTS AND
CHEMICAL SPECIES
Pollutant
Hydrocarbons
Particulates
NOX
Butadiene
Chloroprene
Toluene
Acetic acid
Hydrogen chloride
Talc
TLV,
mg/m3 (10)
°-16b
0.26°
0.10°
2,200
90
375
25
7
6
Source
severity
23
0.03
0.1
0.0004
4.3
0.4
0.0003
0.9
3.4
Guideline of 160 yg/m3 used in place of
corrected TLV to compute source severity.
Primary ambient air quality standard
used in place of TLV to compute source
severity.
Contribution to Total Air Emissions
The contribution of neoprene manufacturing to statewide and
nationwide emissions was measured by the ratio of mass emissions
from this source to the total emissions from all stationary
sources.
31
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The mass emissions of criteria pollutants (organic materials were
classified as hydrocarbon) resulting from neoprene manufacture
were calculated by multiplying the emission factors by the total
production in each state. The mass emissions for each of the
three states with neoprene production is shown in Table 14 (31),
along with the percent contribution of neoprene manufacture to
the total state emissions.
TABLE 14. CONTRIBUTION OF NEOPRENE PRODUCTION
TO 1976 STATE EMISSIONS OF CRITERIA
POLLUTANTS (31)
State
Total state
emissions,
million
metric tons
Neoprene
emissions,
metric tons
Percent of
total for
state3
Kentucky
Particulate
SOX
NOX
Hydrocarbons
Carbon monoxide
Louisiana
Particulate
sox
NO
Hydrocarbons
Carbon monoxide
Texas
Particulate
sox
NOX
Hydrocarbons
Carbon monoxide
0.546
1.20
0.419
0.326
1.19
0.38
0.167
0.423
1.92
5.63
0.549
0.753
1.30
2.22
6.90
__
0.15
1,503
11.8
239
9.99
0.03
179
_ _
<0.0001
0.073
0.00310
0.078
0.00182
<0.0001
0.008
Dashes signify no reported emissions; hence, state
contribution not calculated.
Table 15 (31) gives the contribution of criteria pollutants emis-
sions from neoprene manufacture to the total criteria emissions
on a nationwide basis.
(31) Eimutis, E. C., and R. P. Quill. Source Assessment: State-
By-State Listing of Criteria Pollutant Emissions. EPA-600/
2-77-107b, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, July 1977. 138 pp.
33
-------
TABLE 15. CONTRIBUTION OF NEOPRENE PRODUCTION TO 1976
NATIONAL EMISSIONS OF CRITERIA POLLUTANTS (31)
Pollutant
Particulates
sox
NOX
Hydrocarbons
Carbon monoxide
National
emissions ,
million
metric tons
129
24
9.3
16.6
88.0
Neoprene
emissions ,
metric tons
21.8
0.18
1,921
Percent
0.00002
<0. 00002
0.01
Dashes signify no reported emissions; hence, contri-
bution to national burden not calculated.
Affected Population
The populations affected by criteria pollutants emitted from a
representative neoprene manufacturing plant are given in Table 16,
The area exposed to the time-averaged ground level concentration,
X, for which x/F >0.1 was obtained by a computer from the area
within the isopleth for x (30). The number of people within the
exposed area was then calculated by using an average population
density.
The population density used in the calculation of affected popu-
lation was 378 persons/km2. The population affected by particu-
lates from talc dusting was estimated to be 153 persons. Total
hydrocarbons emitted from a representative plant were estimated
to affect 1,234 persons for a x/F -1.0.
TABLE 16. AFFECTED AREA AND AFFECTED POPULATION
Plant parameter
Population density,
persons/km2
Emission height, m
Q, g/s
F, g/m3
Xm^v/ g/m
Amax' ^' „
Affected area, kmz
Affected population, persons
Particulates
378
11.6
0.57
0.00026
0.00008
0.40
153
Hydrocarbons
378
12.7
23
0.00016
0.004
3.2C
1,234
NO
X
378
3.0
0. 004
0.00010
_ D
0.003
1
aTalc is the only particulate emitted from the representative
neoprene plant.
Equation C-77 (Appendix C) is used to calculate source severity
rather than Xmax/F.
/•»
Area and population affected are for a X/F >1.0.
-------
Calculations determining the affected area and affected popula-
tion for a representative plant assume that the general popula-
tion is in close proximity to the buildings where neoprene
production occurs. For two actual neoprene production facilities,
however, property lines extend 450 m to 600 m from the emission
points described in the section. In Figures 8 and 9 the concen-
trations of hydrocarbons and particulates emitted during neoprene
production are shown as a function of distance downwind from the
point source. From the figures it is seen that the maximum
ground-level concentrations for hydrocarbons and particulates are
within the property lines of these two plants.
Figure 8. Hydrocarbon concentration as a function of distance
downwind from a representative plant.
130
121-120
110
"e 100
* *
S
| 80
5 TO
<_)
I 60
50
40
VALUES
DISTANCE CONCENTRATION
91 I 183 274 366 457 549 64{
114 DISTANCE, m
731 823 914 1,006
Figure 9. Particulate concentrations as a function of distance
downwind from a representative plant.
35
-------
SECTION 5
CONTROL TECHNOLOGY
Existing control technology for the neoprene processing industry
is described in this section. The control of hydrocarbons is
accomplished by condensation/ absorption, pressurized nitrogen
blankets, flares, and by process modifications. These controls
are of primary importance because hydrocarbons comprise 90+% by
weight of the total emissions from a neoprene plant. Control of
hydrogen chloride during the incineration of waste chlorinated
hydrocarbons is accomplished with falling film absorbers. Either
hydrochloric acid or anhydrous hydrogen chloride can be recovered
because hydrogen chloride is absorbed from the gas stream by an
aqueous absorbing liquid. The need to control particulate emis-
sions is confined to the area where talc is used to dust neoprene
rope prior to bagging.
HYDROCARBONS
Condensation
Organic compounds can be removed from an air stream by condensa-
tion. A vapor will condense when, at a given temperature, the
partial pressure of the compound is equal to or greater than its
vapor pressure. Similarly, if the temperature of a gaseous mix-
ture is reduced to the saturation temperature (i.e., the tempera-
ture at which the vapor pressure equals the partial pressure of
one of the constituents), the material will condense. Thus,
either increasing the system pressure or lowering the temperature
can cause condensation. In most air pollution control applica-
tions, decreased temperature is used to condense organic mater-
ials, since increased pressure is usually impractical (32).
Condensation of organic vapors in neoprene manufacture is accom-
plished by the use of direct-contact condensers and brine-cooling
systems. Direct-contact condensers are used to control hydro-
carbon emissions from polykettles, while brine-cooling systems
are*used to control emissions from the isomerizers, chloroprene
(32) Hydrocarbon Pollutant Systems Study; Volume I, Stationary
Sources, Effects, and Control. APTD-1499 (PB 219 073), U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina, 20 October 1972. 377 pp.
36
-------
condenser vents, batch polykettles, neoprene strippers and
storage tank vents.
In the direct-contact cooler, chilled water is sprayed into the
waste gas flow emitted from the batch polykettles during charg-
ing and emptying of the reactors. One neoprene plant utilizing
this control device reports a hydrocarbon removal efficiency of
43% (33).
Neoprene plants control hydrocarbon vapors by circulating brine
at -18°C around the isomerizer chloroprene condenser vents, neo-
prene strippers, and storage tank vents. A series of brine-
cooling devices used to control emissions from the neoprene
strippers is shown in Figure 10 (33).
Emissions from batch polykettles are also controlled with brine-
cooling systems operating at a temperature of 0°C.
OFF GAS-
(56UC
1
WATER
I t
(31°C
(35 °C)
BRINED
( 35 °C )
f 1
(2°C)
METHANOL
(4°C)
J BRINE[
(4°C) '
t t
-18 °C
( -9 °C )
i
rl
,
STEAM
F ( 1, 034 kPa
' / _o ®r \
PROCESS
Figure 10. Brine cooling system for neoprene strippers.
(33) Pruessner, R. D. and L. D. Broz. Hydrocarbon Emission Re-
duction Systems. Chemical Engineering Progress, 73(8): 69-
73, 1977.
37
-------
Pressurized Storage
Chlorobutadiene-water emulsion is stored in feed, hold, and aging
tanks during its polymerization into neoprene. To control hydro-
carbon emissions from emulsion storage, fixed-roof tanks are
placed under 17 kPa to 103 kPa pressure (gauge) (34). Available
vapor space in these pressurized tanks is reduced by placing a
layer of nitrogen gas over the surface of the stored chloro-
butadiene-water emulsion. This gas layer is referred to as a
nitrogen blanket.
Absorption
Oil absorption is utilized by one plant to control hydrocarbon
emissions from the fractionating columns used in chloroprene pro-
duction and from the batch polykettles after the waste gases have
passed through a direct-contact cooling system (33). The absorp-
tion tower used to control emissions from the fractionating
columns is a two-stage oil spray tower that operates under
1.33 kPa pressure (33). Absorption fluid is a process heavy
ends stream chilled to 18°C (33) . Batch polykettle emissions are
controlled by a five-stage oil absorption tower. Absorption is
accomplished by a mixture of paraffinic and aromatic oils which
are dispersed through the tower at 7°C (33). Polymerization at
hydrocarbons within the tower is reduced by the particular mix-
ture of absorbing oils. Figure 11 shows a schematic of the com-
bined control system for batch polykettles which includes the
direct-contact condenser system previously mentioned and a five-
stage absorption system (33).
The effectiveness of oil absorption in controlling hydrocarbon
emissions is dependent upon the solubility of the organic vapors
in the absorbing liquid and the area of the interface between the
gas phase and liquid phase (33). Solubility is expressed in the
form of an equilibrium constant (K) which equals the mole frac-
tion of hydrocarbons in the gas phase divided by the mole frac-
tion of hydrocarbons in the liquid phase. K will vary with
changes in temperature, pressure, and composition of the waste
gas stream and absorbing liquid (11). Increasing the area of
the interface to achieve greater control efficiency is accom-
plished by (35):
(34) Air Pollution Engineering Manual, Second Edition. J. A.
Danielson, ed. Publication No. AP-40, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina,
May 1973. 987 pp.
(35) Liptak, B. G. Environmental Engineer's Handbook, Vol. 2.
Chilton Book Company, Radnor, Pennsylvania, 1974. 1340 pp
38
-------
• dispersing the liquid phase within the gas phase
• dispersing the gas phase within the liquid phase
• spreading the liquid phase over a large surface in
contact with the gas phase
2 C WATER
WASTE
GASES
40 °C
EXITGAS
(6.7°C)
CONTACT
COOLER
WET WASTE
OIL STORAGE
TANK
\ V. V 1
0
p ( 6. 6 C )
TO
— PROCESS
~A
A
A
A
~a
A—
A
A
A
T
"*
>>
* \
>
* V
>f
-" I
>
•* v
^
•* v
FIVE-STAGE ABSORBER
Figure 11. Combined control system for batch polykettles.
39
-------
Flares
A flare is used at one plant to control organic emissions from
the butadiene vent condenser. This device is simply a combined
nozzle and ignition system attached to the vent. Vent gases pass
through the nozzles and are ignited by the ignition system to
provide a continuous flame for further combustion of vent gas.
Steam may be injected into the flame region to provide oxygen for
effective burning; and to enhance mixing of combustibles (33).
Table 17 gives an overview of emission control devices used in
the neoprene industry along with the operating companies and re-
ported control efficiencies for each device.
TABLE 17. CONTROL DEVICES AND THEIR EFFICIENCIES IN THE
NEOPRENE INDUSTRY9
Emission point
Monomer fraction-
ating columns
Du Pont ,
Louisville, KY
Water quench (89%)
Plant
Du Pont ,
La Place, LA
-18°C Brine cooling (50%)
Denka
Houston, TX (33)
Oil adsorption (90%)
Isomerizer
Chloroprene con-
denser vent
Batch polykettles
Neoprene strippers
Storage tanks
Emulsion
Butadiene vent
condenser
followed by
-18°C Brine cooling (28%)
Overall efficiency (92%)
C
0°C Brine cooling (68%)
-18°C Brine cooling (99.9%)
Nitrogen blanket (40%)
Nitrogen blanket (40%)
Brine cooling (95%)
Overall efficiency (99.5%)
-18°C Brine cooling (94%) Brine cooling (81%)
-18°C Brine cooling (95.6%) Brine cooling (99%)
0°C Brine cooling (68%) Direct-contact-cooler (43%)
Oil adsorption (97%)
Overall efficiency (98.4%)
-18°C Brine cooling (99.9%) Brine cooling (99.8%)
Nitrogen blanket (40%)
Nitrogen blanket (40%)
Flare (99.9%)
Control efficiency (%) given in parentheses.
Personal communication with T. M. Nichols, Jr., DuPont, 13 September 1977.
No control reported.
Process Modifications
Modification in process technology for neoprene manufacture is an
important method of controlling hydrocarbon emissions. Hydro-
carbon emissions have been reduced by 85% to 90% in two of the
plants manufacturing neoprene by improving the efficiency of
strippers used to separate unreacted chloroprene from neoprene
latex. Attempts are being made by industry to reduce hydrocarbon
emissions from the drying of neoprene film. One method would be
to reduce the content of volatile hydrocarbons in the film before
it is dried. Secondary condensers on isomerizer reactor vents,
chloroprene vents, and refining columns have reduced hydrocarbon
emissions from these sources by 50% to 90%. Current industry
efforts to reduce hydrocarbon emissions during neoprene produc-
tion are mainly directed in the area of process modifications.
40
-------
HYDROGEN CHLORIDE
Waste chlorinated hydrocarbons that are produced during the
manufacture of neoprene are disposed of at two of the neoprene
plants by incineration. Hydrogen chloride emissions resulting
from the incineration of chlorinated hydrocarbons are controlled
with falling film absorbers.
Combustion gases leaving the incinerator are initially cooled
from 1,330°C to 427°C in a graphite cooling chamber (19). The
cooled gases enter a falling film absorber made of graphite and
similar in design to a shell-and-tube heat exchanger. The com-
bustion gases and the absorption liquid, which can be either weak
acid or water, enter the tubes at the top of the absorber. Both
gas and liquid are distributed evenly through each tube by means
of a weir distribution system (36). As the gas and liquid flow
concurrently through the tubes, hydrogen chloride is absorbed
from the combustion gases by the weak acid or water. The heat
produced by absorption is transferred to cooling water, which
flows continuously through the shell surrounding the tubes of
the absorber.
Gas from the final absorber enters a packed scrubber where the
hydrogen chloride concentration is reduced to 5 ppm (19). The
spent absorbing liquid, having a composition of 37% to 40% hydro-
chloric acid, can be used to make product hydrochloric acid or
anhydrous hydrogen chloride (37). A typical falling film absorp-
tion system is shown in Figure 12 (36).
PARTICULATES (TALC)
The particulate emissions from the dusting of neoprene rope are
comprised of talc dust. Talc is emitted from openings in build-
ings where neoprene dusting occurs. The building can be kept
under negative pressure to reduce these fugitive losses. This
is accomplished by a fan exhaust system which draws air from the
inside of the building to the outside atmosphere via a system of
duct work. As the contaminated air is drawn through the ductwork,
talc particulates may be removed from the gas stream with wet
scrubbers or fabric filters.
(36) Hulswitt, C. E. Adiabatic and Falling Film Absorption.
Chemical and Engineering Progress, 69 (2): 50-52, 1973.
(37) Hulswitt, C. E. and J. A. Mraz. HC1 Recovered from Chlori-
nated Organic Waste. Chemical Engineering, 79 (11) :80-81,
1972.
41
-------
VENT
FEED GAS
COLD WATER
<
tx.
LLJ
o
8
•MAKE UP LIQUOR
WEAK AC ID
LEAN GAS
•PRODUCT ACID
Figure 12. Falling film absorption system (36).
Wet Scrubbing
Wet scrubbers use a liquid (e.g., water) either to remove partic-
ulate matter directly from the gas stream by contact or to im-
prove collection efficiency by preventing reentrainment. The
mechanisms for particle removal are: 1) fine particles are con-
ditioned to increase their effective size, enabling them to be
collected more easily; and 2) the collected particles are trapped
in a liquid film and washed away, reducing entrainment (38).
The effective particle size may be increased in two ways. First
fine particles can act as condensation nuclei when the vapor
passes through its dew point. Condensation can remove only a
relative small amount of dust, since the amount of condensation
required to remove high concentrations is usually prohibitive.
Second, particles can be trapped on liquid droplets by impact
using inertial forces. The following six mechanisms bring
particulate matter into contact with liquid droplets (38):
(38) Control Techniques for Particulate Air Pollutants. NAPCA
Publication No. AP-51 (PB 190 253), U.S. Department of
Health, Education, and Welfare, Washington, D.C., January
1969. 215 pp.
42
-------
Interception occurs when particles are carried by a
gas in streamlines around an obstacle at distances
which are less than the radius of the particles.
Gravitational force causes a particle, as it passes
an obstacle, to fall from the streamline and settle
on the surface of the obstacle.
Impingement occurs when an object, placed in the path
of a particle-containing gas stream causes the gas to
flow around it. The larger particles tend to continue
in a straight path because of inertia and may impinge
on the obstacle and be collected.
Diffusion results from molecular collisions and,
hence, plays little part in the separation of
particles from a gas stream.
Electrostatic forces occur when particles and liquid
droplets become electrically charged.
Thermal gradients are important to the removal of
matter from a particle-containing gas stream because
particulate matter will move from a hot area to a
cold area. This motion is caused by unequal gas
molecular collision energy on the hot and cold sur-
faces of the particles and is directly proportional
to the temperature gradient.
Wet scrubber efficiencies are compared on the bases of contacting
power and transfer units. Contacting power is the useful energy
expended in producing contact of the particulate matter with the
scrubbing liquid. The contacting power represents pressure head
loss across the scrubber, head loss of the scrubbing liquid,
sonic energy or energy supplied by a mechanical rotor. The trans-
fer unit (the numerical value of the natural logarithm of the
reciprocal of the fraction of the dust passing through the scrub-
ber) is a measure of the difficulty of separation of the particu-
late matter (38).
Spray Chamber--
The simplest type of wet scrubber is the spray chamber, a round
or rectangular chamber into which water is sprayed either cocur-
rently, countercurrently, or crosscurrently to the gas stream.
Liquid droplets travel in the direction of liquid flow until
inertial forces are overcome by air resistance. Large droplets
settle under the influence of gravity, while smaller droplets are
swept along by the gas stream. These droplets and particulate
matter may then be separated from the gas stream by gravitational
settling, impaction on baffles, filtration through shallow packed
beds, or by cyclonic action (38).
43
-------
Gravity Spray Tower—
Another simple type of wet scrubber is the gravity spray tower in
which liquid droplets fall downward through a countercurrent gas
stream containing particulate matter. To avoid droplet entrain-
ment, the terminal settling velocity of the droplets is greater
than the velocity of the gas stream. Collection efficiency in-
creases with decreasing droplet size and with increasing relative
velocity between the droplets and air stream. Since these two
conditions are mutually exclusive, there is an optimum droplet
size for maximum efficiency: from 500 ym to 1,000 ym (38).
Centrifugal Spray Scrubbers--
An improvement on the gravity spray tower is the ceo.4-i~ifugal
spray scrubber (Figure 13). This type of wet scrubber inc. -v^se?
the relative velocity between the droplets and gas str -in, by
using the centrifugal force of a spinning gas stream. Tn^ .spin-
ning motion may be imparted by tangential entry of e^ ther the
liquid or gas streams or by the use of fixed vanes >~uid .IT,, -allers
(38).
Impingement Plate Scrubbers--
An impingement plate scrubber (Figure 14) consists of a tower
equipped with one or more impingement stages, mist removal baf-
fles, and spray chambers. The impingement stage consists of a
perforated plate that has from 6,500 to 32,000 holes per square
meter and a set of impingement baffles arranged so that a baffle
is located above every hole. The perforated plate has a weir for
control of its liquid level. The liquid flows over the plate and
through a downcomer to a sump or lower stage. The gas enters in
the lower sector of the scrubber and passes up through a spray
zone created by a series of low pressure sprays. As the gas
passes through the impingement stage, the high gas and particle
velocity (2.25 m/s to 3 m/s) atomizes the liquid at the edges of
perforations. The spray droplets, about 10 ym in diameter, in-
crease fine dust collection (38).
Venturi Scrubbers--
High collection efficiency of fine particles by impingement re-
quires small obstacle diameter and high relative velocity of the
particle as it impinges on the obstacle. Venturi scrubbers
(Figure 15) accomplish this by introducing the scrubbing liquid
at right angles to a high velocity gas flow in the throat of a
venturi where the velocity of the gas alone causes the disinte-
gration of the liquid. Another factor which affects the effi-
ciency of a venturi scrubber is the conditioning of the particles
by con densation. If the gas in the reduced pressure region in
the throat is saturated or supersaturated, the Joule-Thompson
effect will cause condensation. This helps the particle to grow,
and the wetness of the particle surface helps agglomeration and
separation (38).
44
-------
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45
-------
IMPINGEMENT
BAFFLE STAGE
AGGLOMERATING
SLOT STAGE
ARRANGEMENT OF "TARGET PLATES"
IN IMPINGEMENT SCRUBBER
WATER DROPLETS ATOMIZED
AT EDGES OF ORIFICES
tx/1 I
•K
IMPINGEMENT SCRUBBER
DOWNSPOUT TO
LOWER STAGE
IMPINGEMENT PLATE DETAILS
Figure 14. Impingement plate scrubber (38)
Figure 15. Venturi scrubber (38)
46
-------
The irrigating liquid serves to wet, dissolve, and/or wash the
entrained particulate matter from the bed. In general, smaller-
diameter tower packing gives a higher particle target efficiency
than larger-size packing for a given gas velocity (38).
Self-Induced Spray Scrubbers--
The self-induced spray scrubber uses a spray curtain for particle
collection. The spray curtain is induced by gas flow through a
partially submerged orifice or streamlined baffle. Baffles or
swirl chambers are used to minimize mist carryover.
The chief advantage of the self-induced spray scrubber is its
ability to handle high dust concentrations and concentrated
slurries (38).
Mechanically Induced Spray Scrubbers--
Mechanically induced spray scrubbers use high velocity sprays
generated at right angles to the direction of gas flow by a par-
tially submerged rotor. Scrubbing is achieved by impaction of
both high radial droplet velocity and vertical gas velocity.
Advantages are the relatively low liquid requirements, small
space requirements, high scrubbing efficiency, and high dust load
capacity. The rotor, however, is susceptible to erosion from
large particles and abrasive dusts (38).
Disintegrator Scrubber--
A disintegrator scrubber consists of a barred rotor with a barred
stator. Water is injected axially through the rotor shaft and is
separated into fine droplets by the high relative velocity of
rotor and stator bars. Advantages of this scrubber are high
efficiency for submicron particles and low space requirements.
The primary disadvantage is its large power requirement (38).
Centrifugal Fan Wet Scrubber--
This type of scrubber (Figure 16) consists of a multiple-blade
centrifugal blower. Its advantages are low space requirements,
moderate power requirements, low water consumption, and a rela-
tively high scrubbing efficiency (38).
Inline Wet Scrubber—
In the axial-fan-powered gas scrubber, a water spray and baffle
screen wet the particles, and centrifugal fan action eliminates
the wetted particles through concentric louvers. Advantages are
low space requirements and low installation costs (38).
Irrigated Wet Filters—
Irrigated wet filters consist of an upper chamber, containing wet
filters and spray nozzles for cleaning the gas, and a lower cham-
ber for storing scrubbing liquid. Liquid is recirculated and
sprayed into the surface of the filters on the upstream side of
the bed. Two or more filter stages are used in series (38).
47
-------
DIRT AND WATER
DISCHARGED AT
BLADE TIPS
DIRTY GAS
INLET
-------
Fabric Filtration
Fabric filters use a filter medium to separate particulate matter
from a gas stream. Two types of fabric filters are in use--high
energy cleaned collectors and low energy cleaned collectors (39).
High Energy Collectors—
High energy collectors use pulse jets to clean the filter medium,
a felt fabric which is kept as clean as possible (39). The prin-
ciple of the pulse jet is based on the use of an air ejector for
dislodging dust from the bags. The ejector produces a short
pulse of compressed air in the direction opposite to that of the
gas being filtered. The jet must accomplish three things (40):
• Stop the normal filtering flow.
• Transmit a burst of air to the filtration medium,
giving it a vibratory shock.
• Create enough pressure in the bag to ensure a
reversal of flow from the clean side to the dirty
side of the bag.
Low Energy Collectors--
Low energy collectors use shaking or reverse air flow methods of
cleaning. The filter base is a woven cloth that acts as a site
on which the true filter medium, or dust cake, can build up (39).
(39) Frey, R. E. Types of Fabric Filter Installations. Journal
of the Air Pollution Control Association, 24 (12):1148-1150,
1974.
(40) Bakke, E. Optimizing Filter Parameters. Journal of the
Air Pollution Control Association, 24(12):1150-1154 , 1974.
49
-------
SECTION 6
GROWTH AND NATURE OF THE INDUSTRY
PRESENT TECHNOLOGY
The neoprene industry has recently emerged from an industry-wide
change of technology. Prior to 1970, Du Pont was the only domes-
tic manufacturer of chloroprene/neoprene and all of their chloro-
prene facilities used acetylene as the raw material. In 1970,
Denka brought its Houston plant on stream using butadiene tech-
nology. Since that time, Du Pont has also converted to the
butadiene process. Thus, since the end of 1972, all chloroprene
production has been based on butadiene (5, 41).
EMERGING TECHNOLOGY
Since the recent industry-wide conversion from acetylene-based to
butadiene-based processes for chloroprene, there have been no
reports of new technology in the U.S. literature. Reports of a
modification of the butadiene route to chloroprene have been pub-
lished in the British literature. This modification, using a
mixed C^ stream (free from isobutene and isobutane) as feed
material, is based on the reaction:
CH3-CH=CH-CH3 + CH2=CH-CH2-CH3 + Cl •*
C1-CH2-CH=CH-CH3 J CH2=CH-CHC1-CH3 + HC1 (7)
This reaction will take place in parallel with the chlorination
of butadiene. The ;monochlorobutene products are then thermally
dehydrochlorinated to give butadiene and hydrogen chloride. The
butadiene is then recycled to the chlorinator. This process,
however, has only been demonstrated on a pilot scale (6).
INDUSTRY PRODUCTION TRENDS
Because of its combination of properties (i.e., tensile strength,
resilience, abrasion resistance, and resistance to deterioration
by oil, solvents, weather, oxygen, ozone, heat, and flame), neo-
prene vulcanizates are used in a wide variety of applications.
(41) Neoprene: Enter a Second Supplier. Chemical Week, 98(3)
19-20, 1966.
50
-------
The major volume use for neoprene is in mechanical and automotive
goods, such as hose, belts, tire sidewalls, and molded goods.
Other end uses are wire and cable jackets, highway joint seals,
bridge pads, soil pipe gaskets, roof and maintenance coatings,
caulks and sealants, and adhesives. Neoprene latex is used for
foams for mattresses, railroad journal box lubricators, fiber
binders, and adhesives. Table 18 summarizes neoprene uses and
the quantity of neoprene consumed in each (2, 3, 42).
TABLE 18. NEOPRENE END USES (42)
(1969 consumption)
Consumption,
End use 103 metric tons Percent
Footwear, shoe products
Belts, belting
Hose
0-rings, packings, gaskets
Other mechanical goods and
automotive uses
Adhesives, sealants, coatings
Rolls
Coated fabrics
Wire, cable
Latex
Other
TOTAL
2.27
2.27
7.26
2.27
10.44
4.54
0.45
1.82
8.17
9.53
9.99
59.01
3.85
3.85
12.30
3.85
17.69
7.69
0.76
3.08
13.85
16.15
16.93
100.00
Figure 17 is a neoprene industry growth curve showing both neo-
prene production and domestic consumption. The historical (1962-
1972) growth rate of neoprene has been 2.9%/yr (43). This growth
rate would have been much higher if ethylene-propylene rubber
(EPDM) had not replaced neoprene in some automotive and mechani-
cal goods because of its cost advantage. Indications are, how-
ever, that EPDM has replaced neoprene in all the applications
that it can (43). Therefore, the neoprene growth rate for the
future (through 1981) should be about 5%/yr (43). This growth of
neoprene should result in a demand of 252 x 103 metric tons/yr in
1981. The industry emission growth factor, defined as the ratio
of 1981 emissions to 1976 emissions however, is equal to 0.76.
This ratio is due to the expected decrease in hydrocarbon emis-
sions for neoprene plants. State air pollution agencies have
(42) Dworkin, D. Rubber: Slower is the 70's. Chemical Week,
106 (11):56-64, 1970.
(43) Chemical Profile: Neoprene. Chemical Marketing Reporter,
204(14):9, 1973.
51
-------
initiated compliance schedules for neoprene plants which call
for a reduction of 50% in hydrocarbon emissions by 1979.
1950
1980
Figure 17. Neoprene product and consumption trends.
The neoprene market has several weaknesses. Although the average
annual increase in demand from 1970 to 1973 was nearly three
times that of the 1960's, the demand was a result of strong ad-
vances in automotive and construction uses (4). The recent
softening in these two markets could result in a decline in the
demand for neoprene.
Raw material shortages have also adversely affected neoprene. In
1973-1974, neoprene was on allocation due to shortages of buta-
diene and chlorine (43). This situation could reoccur with a
tightening energy supply.
52
-------
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1. Chemical Profile: Neoprene. Chemical Marketing Reporter,
210 (7) :9, 1976.
2. Kennedy, J. P. Polymer Chemistry of Synthetic Elastomers.
Interscience Publishers, New York, New York, 1968. pp. 227-
252.
3. Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 7. John Wiley and Sons, Inc., New York,
New York, 1967. pp. 705-716.
4. Brownstein, A. M. U.S. Petrochemicals, Technologies, Mar-
kets, and Economics. The Petroleum Publishing Company,
Tulsa, Oklahoma, 1972. pp. 258-260.
5. Bellringer, F. J., and C. E. Hollis. Make Chloroprene from
Butadiene. Hydrocarbon Processing, 47(11):127-130, 1968.
6. Crocker, H. P., C. W. Capp, and P. J. Bellringer. Process
for the Production of Dichlorobutenes. British Patent
798,027 (to the Distillers Company, Ltd.,) July 16, 1958.
7. Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 5. John Wiley and Sons, Inc., New York,
New York, 1967. pp. 215-231.
8. Bellringer, F. J., and H. P. Crocker. Preparation of 3,4-
Dichloro-1-butene. British Patent 800,787 (to The Distil-
lers Company, Ltd.), September 3, 1958.
9. Sachowicz, S. K. Production of Chloroprene. U.S. Patent
3,026,360 (to The Distillers Company, Ltd.), March 20, 1962.
10. TLVs® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1976. American Conference of Governmental
Industrial Hygienists, Cincinnati, Ohio, 1976. 97 pp.
11. Chemical Engineers' Handbook, Fourth Edition. J. H. Perry
and C. H. Chilton, eds. McGraw-Hill Book Company, New York,
New York, 1963.
53
-------
12. Handbook of Chemistry and Physics. R. C. Weast, ed. CRC
Press, Cleveland, Ohio, 1973.
13. E. I. du Pont de Nemours and Company. Production of
Dichlorobutenes. British Patent 661,806, November 28, 1951.
14. Bellringer, F. J., and H. P. Crocker. Production of
Dichlorobutenes. British Patent 798,028 (to The Distillers
Company, Ltd.), July 16, 1958.
15. Prescott, J. H. Butadiene to Neoprene Process Makes U.S.
Debut. Chemical Engineering, 78 (3):47-49, 1971.
16. Bellringer, F. J. Production and Stabilisation of Dichloro-
butene. British Patent 877,586 (to The Distillers Company,
Ltd.), September 13, 1961.
17. Capp, C. W. Improvements in the Production of Dichloro-
butenes. British Patent 984,094 (to The Distillers Company,
Ltd.), February 24, 1965.
18. Bellringer, F. J. Preparation of Chloroprene. British
Patent 798,205 (to The Distillers Company, Ltd.), July 16,
1958.
19. Hot Option for the Disposal of Hydrocarbon Wastes. Chemical
Week, 110 (16)-.37-38, 1972.
20. Hollis, C. E. Chloroprene and Polychloroprene Rubbers.
Chemistry and Industry (London), (31):1030-1041, 1969.
21. Billmeyer, F. J. Textbook of Polymer Science. Interscience
Publishers, New York, New York, 1966. pp. 343-347.
22. Encyclopedia of Polymer Science and Technology. H. F. Mark,
ed. John Wiley and Sons, Inc., New York, New York, 1966.
pp. 801-827.
23. Fryling, C. F. Emulsion Polymerization Systems. In: Syn-
thetic Rubber, G. S. Whitby, C. C. Davis, and R. F. Dunbrook,
eds. John Wiley and Sons, Inc., New York, New York, 1954.
pp. 224-258.
24. Neal, A. M., and L. R. Mayo. Neoprene. In: Synthetic
Rubber, G. S. Whitby, C. C. Davis, and R. F. Dunbrook, eds.
John Wiley and Sons, Inc., New York, New York, 1954.
pp. 767-793.
25. Youker, M. A. Continuous Isolation of G.R.M. from Latex.
Chemical Engineering Progress, 43 (8):391-398, 1947.
54
-------
26. Collins, A. M. U.S. Patent 1,967,865 (to E. I. duPont
deNemours and Company), July 24, 1934.
27. Catton, N. L. The Neoprenes. E. I. duPont de Nemours and
Company, Wilmington, Delaware, 1953. 245 pp.
28. Neoprene. Chemical Marketing Reporter, 207 (13):30-41, 1975.
29. Sax, N. I. Dangerous Properties of Industrial Materials,
Reinhold Book Corporation, New York, New York, 1968.
1258 pp.
30. Turner, D. B. Workbook of Atmospheric Dispersion Estimates.
Public Health Service Publication No. 999-AP-26, U.S. Depart-
ment of Health, Education, and Welfare, Cincinnati, Ohio,
May 1970. 84 pp.
31. Eimutis, E. C. and R. P. Quill. Source Assessment: State-
by-State Listing of Criteria Pollutant Emissions. EPA-600/
2-77-107b, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, July 1977. 138 pp.
32. Hydrocarbon Pollutant Systems Study; Volume I, Stationary
Sources, Effects, and Control. APTD-1499 (PB 219 073), U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina, 20 October 1972. 377 pp.
33. Pruessner, R. D. and L. D. Broz. Hydrocarbon Emission
Reduction Systems. Chemical Engineering Progress, 73(8):
69-73, 1977.
34. Air Pollution Engineering Manual, Second Edition. J. A.
Danielson, ed. Publication No. AP-40, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina,
May 1973. 987 pp.
35. Liptak, B. G. Environmental Engineer's Handbook, Vol. 2.
Chilton Book Company, Radnor, Pennsylvania, 1974. 1340 pp.
36. Hulswitt, C. E. Adiabatic and Falling Film Absorption.
Chemical and Engineering Progress, 69(2):50-52, 1973.
37. Hulswitt, C. E. and J. A. Mraz. HC1 Recovered from Chlori-
nated Organic Waste. Chemical Engineering, 79 (11) :80-81,
1972.
38. Control Techniques for Particulate Air Pollutants. NAPCA
Publication No. AP-51 (PB 190 253), U.S. Department of
Health, Education, and Welfare, Washington, D.C., January
1969. 215 pp.
55
-------
39. Frey, R. E. Types of Fabric Filter Installations. Journal
of the Air Pollution Control Association, 24(12):1148-1150,
1974.
40. Bakke, E. Optimizing Filter Parameters. Journal of the
Air Pollution Control Association, 24(12):1150-1154 , 1974.
41. Neoprene: Enter a Second Supplier. Chemical Week, 98(3):
19-20, 1966.
42. Dworkin, D. Rubber: Slower is the 70's. Chemical Week,
106 (11) :56-64, 1970.
43. Chemical Profile: Neoprene. Chemical Marketing Reporter,
204 (14) :9, 1973.
44. Martin, D. 0., and J. A. Tikvart. A General Atmospheric
Diffusion Model for Estimating the Effects on Air Quality
of One or More Sources. Presented at the 61st Annual
Meeting of the Air Pollution Control Association, St. Paul,
Minnesota, June 23-27, 1968. 18 pp.
45. Eimutis, E. C. and M. G. Konicek. Derivations of Continu-
ous Functions of the Lateral and Vertical Atmospheric Dis-
persion Coefficients. Atmospheric Environment, 6(11):
859-863, 1972.
46. Tadmor, J., and Y. Gur. Analytical Expressions for the
Vertical and Lateral Dispersion Coefficients in Atmospheric
Diffusion. Atmospheric Environment, 3 (6):688-689 , 1969.
47. Gifford, F. A., Jr. An Outline of Theories of Diffusion in
the Lower Layers of the Atmosphere. In: Meteorology and
Atomic Energy 1968, Chapter 3, D. A. Slade, ed. Publication
No. TID-24190, U.S. Atomic Energy Commission Technical In-
formation Center, Oak Ridge, Tennessee, July 1968. pp. 113.
48. Code of Federal Regulations, Title 42 - Public Health,
Chapter IV - Environmental Protection Agency, Part 410 -
National Primary and Secondary Ambient Air Quality Standards,
April 28, 1971. 16 pp.
56
-------
APPENDIX A
CALCULATION OF EMISSION HEIGHT
Using the equation,
X
max rr2 ~
for maximum ground level concentration,
where Q = emission rate, g/s
TT = 3.14
H = emission height, m
e - 2.72
u = wind speed = 4.47 m/s
and further, Q = E • P
where E = emission factor, g/kg
P = production rate, kg/s (constant)
we define Xmax•, the maximum ground level concentration from the
ith source as:
2 E. • P
xmax. ~ /TT \ 2 — (A-l)
i TT (H . ) ^eu
Assume that the total ground level concentration is the sum of
individual concentrations (a worst case assumption) from n sources,
Then
X
E
. -
n n 2 E. • P n E.
_ _
^~,_~^^ . -. max. ., .„ > 2 - ~ • i tv
1=1 i 1=1 fr(H.)zeu ireu 1=1 (H.
We define the total emission rate from the n sources as
Qtotal = Qi = P Ei
57
-------
Then, for an average emission height H, the maximum ground level
concentration is
_ ,,
*max, total ~ - 2- ~ - -2
Equating expressions for xmaXftotal,
n
£Ei
ireu H2 Treu i=l (H. )2
Simplifying and solving for H2,
(A-5)
n
H2 = = E (A-6)
Therefore,
(A-7)
Emissions height data for two industrial plants are shown in
Tables A-l and A-2. These data were used to calculate the average
emission height values shown in Table 16, Section 4, page 34.
58
-------
TABLE A-l. PLANT EMISSION HEIGHT DATA - PLANT A
Emission point Emission height, m
Jet vent scrubber 27.4
Butadiene vent condenser 27.4
Dichlorobutene storage tank vents ^'^a
Waste dichlorobutene tank vent 3'^a
Waste chloroprene tank vent 3.0
Isomerizer reactor vent 26.8
Heels tank 7.6
Aqueous dichlorobutene isomerizer 17.7
Refined chloroprene tank vent 11.0
Chloroprene vent condenser 18.3
Vacuum column jet 18.9
Recycle chloroprene tank 8.5
Chloroprene solution makeup tank No. 1 15.5
Chloroprene solution makeup tank No. 2 15.5
Blend tank 10.1
Polykettle mix-hold tank 17.4
Polykettles 16.8
Strippers 14.3
Unstripped Emulsion storage vent tanks 16.2
Stripped Emulsion storage vent tank 11.0
Tank car vents 7.6
Solution makeup mix-hold tank 17.4
Emulsion storage mix-hold tank 16.2
Wash belts 10.1
Dryer exhaust 19 . 8
Dryer coolers 13.4
Bagger exhaust 11.6
Estimated value.
59
-------
TABLE A-2. PLANT EMISSION HEIGHT DATA - PLANT B
Emission point Emission height, m
Chlorinated hydrocarbons incinerator 29.0
Storage tanks (3) M 4
Tank car spots V.M
CD refining columns 2 , '•' ~*
Storage tanks 4.6
Tanks 7.0
Vaporization from ditches 3,0^
Averaging basin ^"®a
Diversion basin ^'^a
Coagulation basin 3.0
CD weigh tanks 9.75
Polymerizer fan discharges 23.5
Large polykettles 24.4
Stripper condenser recovery systems 7.92
Stripper feed and hold tanks 24.4
Vapor from aging tanks 14.3
Freeze roll feed tanks 20.1
Freeze roll feed tanks 20.1
Latex storage tanks, etc. 7
Washings pit 7.62
Dryer (main stacks) 23.2
Dryer ceiling 10.7
Large CD weigh tanks 8.8
Vapor from large polykettles 24.4
Continuous kettles 0.0
Stripper condenser recovery system 8.2
Stripper feed and hold tanks 24.4
Vapor from aging tanks 21.3
Vapor from blending tanks 3.0
Freeze roll feed tanks 11.3
Washings pit 7.0
Dryer main stacks 23.2
Dryer main stacks 10.7
Wash mills 7.0
Estimated value.
60
-------
APPENDIX B
INDIVIDUAL PLANT EMISSION RATES
Emissions data for individual neoprene plants were obtained from
state and local air pollution control agencies. Data were also
provided by the individual companies manufacturing neoprene.
Table B-l is a list of the emission points and emission rates for
plant A. Table B-2 is a list for plant B with data only for the
polymer plant.
Relative error bounds for emission rate values for plant A could
not be estimated because the method of determination was not
reported.
Relative error values for plant B emissions data were estimated
by assuming a standard deviation of 25% about the mean and trip-
licate analyses for all stack analyses. At a 95% confidence
level, these assumptions lead to a ±50% relative error. Storage
tank emission factors were calculated with an assumed relative
error of ±20%.
61
-------
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o
-------
APPENDIX C
DERIVATION OF SOURCE SEVERITY EQUATIONS
SUMMARY OF SEVERITY EQUATIONS
The severity of pollutants may be calculated using the mass
emission rate, Q, the height of the emissions, H, or the distance
from the source to the nearest plant boundary, D, and the thresh-
old limit value, TLV. The equations summarized in Table C-l are
developed in detail in this appendix.
TABLE C-l. POLLUTANT SEVERITY EQUATIONS
Pollutant
Severity equation
For elevated sources:
Particulate
S0x
N0x
Hydrocarbon
CO
Other
For ground level sources:
Particulate
SO
NO
Hydrocarbon
CO
Other
S =
S =
s =
S =
S =
70 Q
H2
50 Q
H2
315 Q
H2.1
162 Q
H2
0.78 Q
H2
= 5.5 Q
TLV • H2
e _ 4,020 Q
o —
= 2,870 Q
D1.
s = 22,200 Q
D1.90
s = 9,340 Q
D1-81
c _ 44.8 Q
S =
316 Q
64
-------
DERIVATION OF Xmax FOR USE WITH u-s- AVERAGE CONDITIONS
The most widely accepted formula for predicting downwind ground
level concentrations from a point source is (44):
X =
Q
7TCT 0 U
Y z
f 1 /y \21 |~ I/ H\2~
exp - 2" It—) exp - j(— )
L v y ] L v z/.
(C-l)
where
X = downwind ground level concentration at reference
coordinate x and y with emission height of H, g/m3
Q = mass emission rate, g/s
TT = 3.14
a = standard deviation of horizontal dispersion, m
a = standard deviation of vertical dispersion, m
Z
u = wind speed, m/s
y = horizontal distance from centerline of dispersion, m
H = height of emission release, m
x = downwind dispersion distance from source of emission
release, m
We assume that xmax occurs when x»0 and y = 0. For a given sta-
bility class, standard deviations of horizontal and vertical dis-
persion have often been expressed as a function of downwind
distance by power law relationships as follows (44):
b
ay = ax
(C-2)
= cxd + f
(C-3)
Values for a, b, c, d, and f are given in Tables C-2 and C-3 (45)
Substituting these general equations into Equation C-l yields:
Q
b+d , f b
acnux + a?rufx
exp
2(cx
f)
(C-4)
(44) Martin, D. 0., and J. A. Tikvart. A General Atmospheric
Diffusion Model for Estimating the Effects on Air Quality
of One or More Sources. Presented at the 61st Annual Meet-
ing of the Air Pollution Control Association, St. Paul,
Minnesota, June 23-27, 1968. 18 pp.
(45) Eimutis, E. C. and M. G. Konicek. Derivations of Continuous
Functions of the Lateral and Vertical Atmospheric Dispersion
Coefficients. Atmospheric Environment, 6 (11):859-363, 1972.
65
-------
TABLE C-2.
VALUES OF a FOR THE
COMPUTATION OF a a (45;
Stability class
A
B
C
D
E
F
a
0.3658
0.2751
0.2089
0.1471
0.1046
0.0722
For the equation
ay = axb
where x = downwind distance
b = 0.9031 (from Reference 46)
TABLE C-3. VALUES OF THE CONSTANTS USED TO
ESTIMATE VERTICAL DISPERSION3 (44)
Usable range, m
Stability
class
Coefficient
>1,000
A
B
C
D
E
F
0.00024
0.055
0.113
1.26
6.73
18.05
2.094
1.098
0.911
0.516
0.305
0.18
M
-9.6
2.0
0.0
-13
-34
-48.6
100 to 1,000
A
B
C
D
E
F
0.0015
0.028
0.113
0.222
0.211
0.086
1.941
1.149
0.911
0.725
0.678
0.74
9.27
3.3
0.0
-1.7
-1.3
-0.35
For the equation
C3
<100
A
B
C
D
E
F
0.192
0.156
0.116
0.079
0.063
0.053
0.936
0.922
0.905
0.881
0.871
0.814
a = ex
z
+ f
(46) Tadmor, J. , and Y. Gur. Analytical Expressions for the
Vertical and Lateral Dispersion Coefficients in Atmospheric
Diffusion. Atmospheric Environment, 3 (6 ): 688-689 , 1969.
66
-------
Assuming that Xmax occurs at x<100 m or the stability class is C,
then f = 0 and Equation C-4 becomes:
Q_ T -H2 1 ,„ „.
.2c2x2d.
For convenience, let:
AD = —— and B0 = -^-
K K „ 2
ac ITU £ c
so that Equation C-5 reduces to:
-(b+d)
X = A^x l"'"' exp -^- (C-6)
K J- i - J i
Taking the first derivative of Equation C-6
(C-7)
and settling this equal to zero (to determine the roots which
give the minimum and maximum conditions of x with respect to x)
yields :
(C-8)
Since we define that x ^ 0 or °° at x » the following expression
must be equal to 0:
-2dBr)x~2d-d-b = 0 (C-9)
K
or
or
(b+d)x2d = -2dBR
b+d 2c2(b+d)
67
-------
or
c2(b+d
or
V2d
x =( ,~ " 1 at x
./ d H2 \
\c2(b+d)/
max
Thus Equations C-2 and C-3 become:
. b_
u 2 \ "o j
(C-14)
a
y
c2
-*(
\
d H2
(b+d)
=
)
2
d
d H2
(d+b)
fd_/
V
V-
\2d
/
d H
b+d
Vo
-0
az - c( ~ " p" = [^-) (C-15)
The maximum will be determined for U.S. average conditions of
stability. According to Gifford (47), this is when a = a .
Since b = 0.9031, and upon inspection of Table C-2 under U.S.
average conditions, a = a , it can be seen that 0.881 1 d 5 0.905
(class C stability3).-^ Thus, it can be assumed that b is nearly
equal to d or:
a = — (C-16)
Z /2
and
a = - - (C-17)
Y c /I
Under U.S. average conditions, oy = az and a = c if b = d and
f = 0 (between class C and D, but closer to belonging in class C) .
The values given in Table C-3 are mean values for stability class.
Class C stability describes these coefficients and exponents,
only within about a factor of two (44).
(47) Gifford, F. A., Jr. An Outline of Theories of Diffusion in
the Lower Layers of the Atmosphere. In: Meterology and
Atomic Energy 1968, Chapter 3, D. A. Slade, ed. Publication
No. TID-24190, U.S. Atomic Energy Commission Technical Infor-
mation Center, Oak Ridge, Tennessee, July 1968. pp. 113.
68
-------
Then
(C-18)
Substituting for a and a into Equation C-l and letting y = 0:
max
= 2 Q
TTUH2
exP
(C-19)
or
2 Q (C-20)
max
For ground level sources (H = 0), Xmax occurs by definition at
the nearest plant boundary or public access. Since this occurs
when y = 0, Equation C-l becomes:
x =
TTO a u
y z
From the foregoing analysis of U.S. average conditions, class C
stability coefficients are the best first approximations to U.S.
average conditions when 0 = a .
By letting D equal the distance to the occurrence of x (see
Tables C-2 and C-3),
a = 0.209 D°'9031 (C-22)
a = 0.113 D0'911 (C-23)
Z
Thus , x is determined as follows :
in 3.x
= 42.36 Q
Xmax (C24)
It will be noted that Equations C-24 and C-20 are identical with
the algebraic substitution of
H2 = 0.01737 D1' 81tt (C-25)
For U.S. average conditions u = 4.47 m/s so that Equation C-20
reduces to:
69
-------
= 0.0524 Q (c_26)
Amax 2
DEVELOPMENT OF SOURCE SEVERITY
The general source severity, S, relationship has been defined as
follows:
S = max (C-27)
F
where Xm.,v = time-averaged maximum ground level concentration
ILici.X.
F = hazard factor
Noncriteria Emissions
The value of Xmax may be derived from Xmax, an undefined "short
term" (to) concentration. An approximation for longer term (t)
concentration may be made as follows (44):
For a 24 hour time period,
Y = Y I
Amax Amax '
or
.0.17
/ 3 min \ (C_
xmax xmax I 1,440 mini
- = Xmax (0.35) (C-
Amax
Since the hazard factor is defined and derived from TLV values
as follows:
F = (TLV) (^
F = (3.33 x 10~3) TLV (C-32)
then the severity factor, S, is defined as:
s = = - - (c_33)
F (3.33 x 10" 3) TLV
70
-------
105 x
S = max (C-34)
TLV ^ '
If a weekly averaging period is used, then:
( 10,080 )
0.17
xmax ~ xmax ' ""n non ' (C-35)
or
xmax = (0'25)xmax (C-36)
and
/ /m\/ i \
(C-37)
F = (2.38 x 10~3)TLV (C-38)
and the severity factor, S, is:
Xm_ (0.25)X
F (2.38 x 10"3)TLV
or
S = "— (C-40
s = -i^n = Hl^ (C-39)
which is entirely consistent, since the TLV is being corrected
for a different exposure period.
Therefore, the severity can be derived from Xmax directly without
regard to averaging time for noncriteria emissions. Thus, com-
bining Equations C-40 and C-26, for elevated sources, gives:
S = 5'5 Q (c-41)
TLV • H2
Criteria Emissions
For the criteria pollutants, established standards may be used as
F values in Equation C-27. These are given in Table C-4. How-
ever, Equation C-28 must be used to give the appropriate averaging
period. These equations are developed for elevated sources using
Equation C-26.
71
-------
TABLE C-4. SUMMARY OF NATIONAL AMBIENT AIR
QUALITY STANDARDS (48)
Pollutant
Particulate
matter
SO
X
Carbon
monoxide
Nitrogen
dioxide
Photochemical
oxidants
Hydrocarbons
(nonme thane)
Averaging
time
Annual (geometric
mean)
24-hourb
Annual (arith-
metic mean)
24-hourb
3-hour
8-hour
l-hourb
Annual (arith-
metic mean)
l-hourb
3-hour
(6 a.m. to 9 a.m.)
Primary
standards
75
260
80
365
10
40,000
100
160
160
yg/m3
yg/m3
yg/m3
yg/m3
-
mg/m3
yg/m3
yg/m3
yg/m3
yg/m3d
Secondary
standards
60a yg/m3
160 yg/m3
60 yg/m3
260° yg/m3
1,300 yg/m3
(Same as
primary)
(Same as
primary)
(Same as
primary)
(Same as
primary)
The secondary annual standard (60 yg/m3) is a guide for assess-
ing implementation plans to achieve the 24-hour secondary
standard.
Not to be exceeded more than once per year.
The secondary annual standard (260 yg/m3) is a guide for
assessing implementation plans to achieve the annual standard.
There is no primary ambient air quality standard for hydro-
carbons. The value of 160 yg/m3 used for hydrocarbons in
this report is a recommended guideline for meeting the pri-
mary ambient air quality standard for photochemical oxidants.
(48) Code of Federal Regulations, Title 42 - Public Health,
Chapter IV - Environmental Protection Agency, Part 410 -
National Primary and Secondary Ambient Air Quality Standards,
April 28, 1971. 16 pp.
72
-------
CO Severity—
The primary standard for CO is reported for a 1-hr averaging time,
Therefore,
t = 60 min
t =3 min
max
0.17
*max = Xmax^) (C'42)
2 Q / 3\°"17
- -AJL. ( _£\ (C-43)
TT6UHZ \60 /
?-2 (0.6) (C-44)
(3.14) (2.72) (4.5)H2
- (3'12 °'2)Q
Severity, S - -- (C-47)
r
Setting F equal to the primary standard for CO, i.e., 0.04 g/m3
yields :
s = xmax = (3.12 x 10"2)Q (C-48)
F 0.04 H2
or
s = 0^78_Q (c_49)
CO R2
Hydrocarbon Severity--
The primary standard for hydrocarbon is reported for a 3-hr
averaging time.
t - 180 min
73
-------
= 3 min
xmax = xmax (C>50
- °-5*max (C-51)
_ (0.5) (0.052) Q (C-52)
H
2
2
For hydrocarbons, F = 1.6 x 10~4 g/m3 (see Table 12)
and
°-026 Q
1.6 x 10~u H
2
(C-54)
or
5_Q (c_55)
Particulate Severity--
The primary standard for particulate is reported for a 24-hr
averaging time.
0-17
= XT
max
(l,440J
(0.052) Q (0.35) (C-57)
H2
max (C-58)
max T
For particulates, F = 2.6 x 10 ^ g/m3
xmax _ 0.0182 Q
_
o "~~
2.6 x 10'4 H
74
-------
SB = m-X- (C-60)
P H2
SOX Severity--
The primary standard for SO is reported for a 24-hr averaging
time.
- = (0.0182) Q (c-fin
xmax 2
The primary standard is 3.65 x 10"^ g/m3.
and
(0.0182)Q ,„ _
s =
F 3.65 x 10~4 H2
or
S = 50 Q
S°x H2
NOX Severity—
Since NOX has a primary standard with a 1-yr averaging time, the
Xmax correction equation cannot be used. As an alternative, the
following equation was selected:
- = 2.03 Q I 1 /H_\r (c_64)
-»
A difficulty arises, however, because a distance x, from emission
point to receptor, is included and hence, the following rationale
is used:
The equation xm-,v = —
max
is valid for neutral conditions or when a so. This maximum
occurs when ^
H =
z
and since, under these conditions,
b
a = ax
z
75
-------
then the distance, x , where the maximum concentration occurs
max
is:
x
max
/ H \i
\/2a/
For class C conditions,
a = 0.113
b = 0.911
Simplifying Equation C-64,
since
a = 0.113 x °'911
z max
and
u = 4.5 m/s
Letting x = x in Equation C-64,
where
X =
4 Q
x
1.911
max
max
= /_JL\
I 0.16 I
1.098
(C-65)
(C-66)
x = 7.5 H1'098
max
(C-67)
and
Therefore
4 Q
4 Q
X 1-911 (7.5 H1'098)1'911
in 3.x
0.085 Q
X = -I-T- exp|- ^ I-
(C-68)
(C-69)
a = 0.113x°-911
z
(C-70)
76
-------
a = 0.113 (7.5 H1'1)0*911 (C-71)
z
a = 0.71 H (C-72)
z
Therefore,
- _ 0.085 Q
(C-73)
= 0.085 Q ? (c_?4)
H2.1
X = 3-15 X 10"2 Q (C-75)
H2.1
Since the NO standard is 1.0 x 10"4 g/m3, the NO severity equa-
tion is: x
= 0.15 x 10-2) Q (c_76)
x 1 x 10"4 H2-1
s _ 315 Q
NO ~ ~TT (C-77)
x H2- :
77
-------
APPENDIX D
COMMENTS BY
E. I. DU PONT DE NEMOURS & CO.
ON
JULY 1977 DRAFT OF SOURCE ASSESSMENT DOCUMENT:
POLYCHLOROPRENE STATE-OF-THE-ART
The Du Pont Company believes that the simulation approach used in
this document to define severity of stationary air pollution sources
overestimates source severities conservatively by a factor of 10 to
50. The source severity approach is an oversimplification which
does not represent the actual effect of point sources on air quality
and cannot be used as an absolute measure of the "severity" of a
source.
We note that these comments apply to all source assessment documents
where this methodology has been used.
Our concern focuses on the following major areas:
• The corrected Threshold Limit Value, F, applies safety
factors which are excessive when compared to Ambient
Air Quality Standards.
• No plume rise is used for emission sources.
• All sources are considered to emit from a single point,
rather than from widely separated locations.
• The simplified dispersion formula gives erroneous
results for the wind speed and stability used.
• The peak-to-mean averaging time factors are incorrect
for point sources at the atmospheric stability used.
• Consideration is not given to the location of the
predicted maximum concentration with respect to plant
boundaries.
• The source severity dispersion analysis includes all
sources emitting at their maximum rates while, in fact,
the chloroprene process with the exception of the
chloroprene isolation is a batch process where vessels
vent sequentially - not at one time.
78
-------
Each of these overly conservative or incorrect simplifications leads
to a significant error. When these errors are compounded, unrealis-
tically severe assessments of source impact result, as shown in more
detail below.
Comments on July 1977 Draft Document by Page Number
Section IV - Emissions
Page 28
Equation (4)
(T z
In this simplified equation, the term - is missing as
indicated below.
Max. =
\
For neutral conditions (D stability) at which the average wind
speed of approximately 15 ft/sec (4.47 m/s = 14.7 ft/sec) applies,
$Tz/ <5"y is about 0.5.^-/ Consequently, this equation over-
estimates concentrations by about 100%. Even under C stability,
as apparently used, the ratio is 0.6.
In addition, the emission height, h, is the stack height with no
credit given for plume rise due to velocity or buoyancy. Plum-?
rise is an important factor in the dispersion attained by larger
sources, as the neoprene dryers. The following table shows tie
error in calculated ground-level concentrations if plume rise is
not considered.
Error in *)£• if Plume Rise Omitted
15 Ft/Sec Wind Speed - Neoprene Dryers
Case h _.h2
A. No plume rise 65 ft 4,225 fi;2
B. Plume rise
(Bosanquet-Carey- 2
Halton) 115 ft 13,225 f
hB~
---• —~~ - j.l (Prom Equation 1}
^B V
Consequently, the maximum ground-level concentration is over-
predicted by a factor of three in this case.
79
-------
In addition as described in Appendix A, page 53, it was
assumed that the total ground-level concentration is the sum
of individual concentrations. This is a grossly inaccurate
oversimplification of a complex situation. Maxima will fall
at different locations (some within the plant boundary) at
different wind speeds. We estimate that predictions by this
method could be high by a factor of 20 to 80.
Page 29
Equation (5)
Our experience is that the exponent used in this time corre-
lation greatly overestimates maximum longer term ambient
concentrations produced by point sources. The 0.17 exponent
is best applied to highly stable atmospheres or to air mass
peak to mean ratios. We find a factor of about 0.35 is more
appropriate, which corresponds to neutral wind speed used.
This is also in agreement with the time factors by Smith.2/
Error in Time Conversion Factor
Time Period Conversion
Exponent
A. 0.17
B. 0.35
Ratios of A/B
Conversions 2.08 3.04
Consequently, the time average overpredicts by a factor of two
to three.
Page 29
Table 10 - Time Averaged Maximum Ground-Level Concentrations
by Compound
The information given in this table can be used to illustrate
the errors which arise when the distance to the property line
is not considered. The talc source at elevation 11.6 meters
is shown to produce a maximum ground-level concentration of
200 yugra/m^. We estimate the maximum concentration falls about
600 ft downwind (at D stability). However, at the property
line (~3,000 ft downwind for one of our plants), the value is
lower by a factor of seven.
3-Min to 3-Hrs
0.498
0.231
3-Min to 24-Hr s
0.350
0.115
80
-------
Similarly chloroprene concentrations are lower by a factor of
five, and dichlorobutene by a factor of 20 when property line
concentrations are compared to the predicted maxima. Conse-
quently, source severities based on maxima concentrations of
small sources close to ground may not be a meaningful measure
of the effect of a source off a plant site.
Maximum ground-level concentrations predicted in Table 10 are also
in error for the chloroprene process because they assume all
sources are emitting simultaneously and continuously. With the
exception of the chloroprene isolation system (strippers, wash
belts, driers), this is not the case. The remainder of the
chloroprene process is batchwise, with vessels venting in se-
quence rather than together. Consequently, the effect of emis-
sions from this part of the process is overestimated by a factor
of two or more.
Page 29
Equation (6)
This equation is the basis for a reasonable source severity
determination, however, the Threshold Limit Value correction
(F) for noncriteria pollutants is overly conservative and not
consistent with Ambient Air Quality Standards.
For example, S(>2» has both a TLV and an ambient air quality
standard. Using the TLV of SO2 as 5 ppm (13 mg/m3), the "F"
value becomes 5 X 8/24 X 10~2 = 0.017; if x max (24 hr) =
0.034 ppm (0.089 mg/m3), the S (source severity) = 0.034/0.017
=2. It is stated that if x max/F >1.0, "the source is
considered a definite candidate for control technology develop-
ment" and that if this ratio is 7-0.1, it "indicates a possible
need for additional control technology." These quotes are from
the Monsanto Research Corporation document on Source Assessment
Methodology. The above would say that SO? definitely needs
control although its 24-hr maximum concentration is about 25%
of the federal ambient air quality standard, and "it might
possibly need control" if its 24-hr concentration were greater
than 0.0034 ppm. This latter value which is about 2.5% of the
air quality standard as we understand it would be used in
evaluating the affected population. In this case, it probably
means the entire U.S. would be affected because 0.0034 ppm is
likely the absolute minimum background. We conclude 0.005 ppm
represents the minimum measurable detection level.
In the table below, we have substituted the TLV's of criteria
pollutant in the F formula, using the time period applicable
for each pollutant's Primary Ambient Air Standard. The F
factor is then compared against the^ Primary Standard.
81
-------
Error in F Factor as Approximation
of Primary Ambient Air Standard
Arab, Air Std. ITTV\
Criteria TLV, Time Period F*= £r .1
Pollutant mg/m
S02
NOX(N02)
Oxidants
(Ozone)
CO
13
0.2
55
T (Hours)
24
8,760
1
8
(T)(100)
0.04
0.00008
0.015
0.55
Amb. Std.
(mg/m3)
0.365
0.10
R =
Amb. Std.
F
9.1
1,250
0.160
10
10.6
18.1
*The time period (T) for which the ambient standard applies was
substituted for 24 in the Monsanto equation, which is the less
general case where only the 24-hr standard is used.
As shown by the ratio, R, this approach can lead to significant
errors which give highly misleading and unrealistic results.
Page 34
Affected Population
We question the basis of determining the population exposed to
high concentrations by the area included in an isopleth of
y>/F "2*0.1. It should be the area where ^/F^i.O, since
this would be the situation where the primary standard is being
exceeded (if F is the primary standard) . This would reduce the
affected area (and population) by a factor of about 10 for a
ground source, according to Turner. 7 We believe that the error
would be much greater still for an elevated source.
References for Appendix D
1. Turner, D. Bruce, "Workbook of Atmospheric Dispersion
Estimates," U.S. Department Health, Education, and Welfare,
1969, pp. 8-9. ( CT's taken at 1 km which is probable
greatest distance of maxima.)
2. Smith, Maynard, "Recommended Guide for the Prediction of
the Dispersion of Airbourne Effluents, ASME, p. 51.
3. Turner, p. 28.
82
-------
GLOSSARY
affected population: Number of nonplant persons exposed to con-
centrations of airborne materials which are present in
concentrations greater than a determined hazard potential
factor.
brine: Solution of sodium chloride or potassium chloride;
used as a heat exchange fluid in cooling systems designed
to remove heat produced during polymerization of monomer.
butadiene: C^ unsaturated hydrocarbon produced by the catalytic
dehydrogenation of butylenes or butane and used as a feed-
stock in the production of chloroprene.
criteria pollutant: Emission species for which ambient air
quality standards have been established. These include
particulates, carbon monoxide, sulfur oxides, nitrogen
oxides, and nonmethane hydrocarbons.
emission factor: Weight of material emitted to the atmosphere
per unit of neoprene produced; e.g., g material/kg product.
emulsion polymerization: Conversion of chloroprene to neo-
prene by a heterogeneous reaction system with a continuous
aqueous phase and a dispersed monomer phase.
nitrogen blanket: Layer of nitrogen gas under pressure which
relies on the surface of stored volatile organics; designed
to control hydrocarbon emissions from storage tanks.
noncriteria pollutant: Emission species for which no ambeint air
quality standards have been established.
polychloroprene (neoprene): Synthetic rubber produced through
the polymerization of chloroprene.
source severity: Ratio of the maximum mean ground level concen-
tration of emitted species to the hazard factor for the
species.
stability class: Factor which characterizes the atmosphere
and is determined from cloud cover, wind speed, and time of
day.
83
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 REPORT NO.
.EPA-600/2-77-1070
4. TITLE AND SUBTITLE
SOURCE ASSESSMENT:
State of the Art
3. RECIPIENT'S ACCESSION NO.
POLYCHLOROPRENE,
6 REPORT DATE
December 1977 issuing date
8. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
D. A. Horn, D. R. Tierney, and T. W. Hughes
8. PERFORMING ORGANIZATION REPORT NO.
MRC-DA-718
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
10. PROGRAM ELEMENT NO.
1AB604
11. CONTRACT/GRANT NO
68-02-1874
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Lab.
Office of Ressearch § Development
U.S. Environmental Protection Agency
Cincinnati. Ohio 4526ft
- Gin., Oh 45268
13. TYPE OF REPORT AND TERIOD COVERED
Task Final 3/75-7/77
14. SPONSORING AGENCY CODE
EPA/6UO/12
15. SUPPLEMENTARY NOTES
IERL-Ci project leader for this report is R. J. Turner, 513-684-4481
16. ABSTRACT
This document reviews the state of the art of air emissions from poly-
chloroprene manufacture. The composition, quality, and rate of emissions;
and their environmental effects are described. Polychloroprene is pro-
duced by the emulsion polymerization of 2-chloro-l,3-butadiene (chloro-
prene). Emissions include hydrocarbons, particulate, hydrogen chloride,
and nitrogen oxides. To assess the severity of emissions from this
industry, a representative plant was defined based on mean values for
plant parameters. Source severity was defined as the ratio of the time-
averaged maximum ground level concentration of an emission to the primary
AAQS for criteria pollutants or to a reduced TLV for noncriteria pollu-
tants. For a representative plant, source severities for particulate,
hydrocarbons, nitorgen oxides, chloroprene, toluene, hydrogen chloride,
and talc are 0.03, 23, 0.1, 4.3, 0.4, 0.9, and 3.4, respectively.
Hydrocarbon emissions are controlled through a combination of process
modifications. Particulates are controlled by exhaust systems in
conjunction with wet scrubbers or fabric filters. Hydrogen chloride
emissions are reduced by falling film absorbers and packed scrubbers.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Air Pollution
Assessments
Polychloroprene
Chloroprene resins
b.IDENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Source Assessment
Neoprene
COSATI Field/Group
68 E
68F
18. DISTRIBUTION STATEMENT
Release to Public
19 SECURITY CLASS (This Rrpart)
Unclassified
21 NO. OF PAGES
95
20 SECURITY CLASS (Thltpage)
Unclassified
27 PRICE
EPA Form 2220-1 (»-73)
84
*US GOVERNMENT PRINTING OFFICE 1978— 757-140/6654
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