12CO ?'xth
Seattle, i/VA
POLYMER INDUSTRY RANKING BY
VOC EMISSIONS REDUCTION
THAT WOULD OCCUR FROM
NEW SOURCE PERFORMANCE STANDARDS
Pullman Kellogg
... \
Division of Pullman Incorporated
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August 30, 1979
POLYMER INDUSTRY RANKING BY
VOC EMISSIONS REDUCTION
THAT WOULD OCCUR FROM
NEW SOURCE PERFORMANCE STANDARDS
by
C.N. Click
O.K. Webber
PULLMAN KELLOGG
16200 Park Row, Industrial Park Ten
Houston, Texas 77084
Contract No. 68-02-2619, Task No. 7
Project Officer
Dennis Grumpier
U.S. EPA, OAQPS, ESED, CPB, CAS
Room 730 Mutual Building (MD-13)
Research Triangle Park,
North Carolina, 27711
Project Manager
J.A. McSorley
Operations Program Officer
Industrial Environmental
Research Laboratory
Research Triangle Park,
North Carolina 27711
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGE*"""
RESEARCH TRIANGLE PARK, NC 277]
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. , CONTENTS
Section
1.0 INTRODUCTION 1
2.0 SUMMARY 3
3.0 PRIORITY RANKING 5
4.0 DISCUSSION AND DATA 15
4.1 General 15
4.2 Processes and Flowsheets 16
4.3 Company Visits and Categories of Plastics 16
4.4 VOC Emissions Data 17
4.5 Applicable Controls and Efficiencies 17
4.6 Data Reduction 19
4.7 References and Credits 19
5.0 ACRYLIC RESINS 20
5.1 Industry Description 20
5.2 Acrylic Resin Manufacture by Hydrocarbon Based 27
Processes
5.2.1 Hydrocarbon Based Process,. Descriptions 27
5.2.2 VOC Emissions for the Hydrocarbon Based 30
Processes
5.2.3 Applicable Controls for the Hydrocarbon 33
Based Processes
5.3 Acrylic Resin Manufacture by Water Based Processes 34
5.3.1 Water Based Process Description 34
5.3.2 VOC Emissions for the Water Based Processes 37
5.3.3 Applicable Control Systems (Water Based 40
Processes)
6.0 ALKYD RESINS 42
6.1 Industry Description 42
6.2 Alkyd Resin Manufacture By Solvent Process 50
6.2.1 Process Description 50
6.2.2 VOC Emissions 52
6.2.3 Applicable Control Systems 55
7.0 MELAMINE - FORMALDEHYDE RESINS 58
7.1 Industry Description 58
7.2 Manufacture Of Melamine-Formaldehyde Resin And A 60
Butylated MF Resin
7.2.1 Process Description 60
7.2.2 VOC Emissions 77
7.2.3 Applicable Control Systems 80
ii
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CONTENTS
Section Page
8.0 NYLON 6 FIBER . 81
8.1 Industry Description 81
8.1.1 General 81
8.1.2 Nylon 6 82
8.1.3 Production Levels for Nylon and Aramid 83
8.2 Nylon 6 Manufacture by the Continuous Chip Process 85
8.2.1 Process Description 85
8.2.2 VOC Emissions 89
8.2.3 Applicable Control Systems 92
9.0 NYLON 66 FIBER 94
9.1 Industry Description 94
9.2 Batch or Continuous Polycondensation of Nylon 66 94
9.2.1 Process Description 94
9.2.2 VOC Emissions 101
9.2.3 Applicable Control Systems 105
10.0 PHENOL-FORMALDEHYDE (PHENOLIC) RESINS 107
10.1 Industry Description 107
10.2 Manufacture of Phenol-Formaldehyde (Phenolic) Resins 108
10.2.1 Process Description 108
10.2.2 VOC Emissions 112
10.2.3 Applicable Control Systems 116
ll.O POLYESTER FIBERS 118
11.1 Industry Description 118
11.2 P.P. Manufacture by Dimethyl Terephthalate Process 123
11.2.1 Process Description 123
11.2.2 VOC Emissions (DMT Process) 126
11.2.3 Applicable Control Systems (DMT Process) 130
11.3 P.P. Manufacture by Terephthalic Acid (TPA) Process 130
11.3.1 Process Description (TPA) 130
11.3.2 VOC Emissions (TPA Process) 130
11.3.3 Applicable Control Systems (DMT & TPA 130
Processes)
iii
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CONTENTS
Section Page
12.0 HIGH DENSITY POLYETHYLENE 137
12.1 Industry Description 137
12.2 HOPE Manufacture by Liquid Phase Processes 138
12.2.1 Process Description (Liquid Phase) 138
12.2.2 VOC Emissions (Liquid Phase) 143
12.2.3 Applicable Control Systems (Liquid Phase) 146
12.3 HOPE Manufacture by Gas Phase Processes 147
12.3.1 Process Description (Gas Phase) 147
12.3.2 VOC Emissions (Gas Phase). ... 150
12.3.3 Applicable Control Systems (Gas Phase) 152
13.0 LOW DENSITY POLYETHYLENE 154
13.1 Industry Description 154
13.2 LDPE Manufacture by Liquid Phase (High Pressure) 159
13.2.1 Process Description (Liquid Phase) 159
13.2.2 VOC Emissions (Liquid Phase) 161
13.2.3 Applicable Control Systems (Liquid Phase) 164
13.3 LDPE Manufacture by Gas Phase Processes 166
13.3.1 Process Description (Gas Phase) 166
13.3.2 VOC Emissions (Gas Phase) 169
13.3.3 Applicable Control Systems (Gas Phase) 171
14.0 POLYPROPYLENE 173
14.1 Industry Description and Status 173
14.2 Polypropylene Manufacture 179
iv
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Section
CONTENTS
Page
14.2.1 Process Description 179
14.2.2 VOC Emissions 122
14.2.3 Applicable Control Systems
15.0 POLYSTYRENE RESINS 187
15.1 Industry Description
15.2 Manufacture of Polystyrene Resin by Bulk (Mass),
Suspension, or Bulk-Suspension Processes
15.2.1 Process Description 188
15.2.2 VOC Emissions 195
15.2.3 Applicable Control Systems 198
16.0 POLYVINYL ACETATE 200
16.1 Industry Description 200
16.2 Polyvinyl Acetate by Emulsion Polymerization 203
16.2.1 Process Description 203
16.2.2 VOC Emissions 211
16.2.3 Applicable Control Systems 213
17.0 POLYVINYL ALCOHOL 215
17.1 Industry Description 215
17.2 Manufacture of Polyvinyl Alcohol 217
17.2.1 Process Description 217
17.2.2 VOC Emissions 221
17.2.3 Applicable Control Systems 224
v
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CONTENTS
Section
18.0 STYRENE BUTADIENE LATEX 227
18.1 Industry Description 227
18.2 Styrene-Butadiene by Emulsion Polymerization 229
18.2.1 Process Description 229
18.2.2 VOC Emissions 233
18.2.3 Applicable Control Systems 236
19.0 UNSATURATED POLYESTER RESINS 238
19.1 Industry Description 238
19.2 Unsaturated Polyester Resin Manufacture 245
19.2.1 Process Description (Fusion and Solvent 245
Processes)
19.2.2 VOC Emissions 249
19.2.3 Applicable Control Systems 252
20.0 UREA- FORMALDEHYDE RESINS 254
20.1 Industry Description 254
20.2 Urea Formaldehyde Syrup and Filled Powder Manufacture256
20.2.1 Process Description 256
20.2.2 VOC Emissions 253
20.2.3 Applicable Control Systems 261
REFERENCES 263
VI
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FIGURES
Figure Page
3-1 Capacity regulated by existing standards and by NSPS 9
versus year since NSPS promulgation.
5-1 Acrylics resins manufacture by bulk/solution processes. 28
5-2 Acrylics resins manufacture by emulsion/suspension 35
processes.
6-1 Alkyd resins by a batch solvent process. 51
7-1 Melamine-formaldehyde resin - Batch process. 73
8-1 Nylon 6 - Continuous chip process. 87
9-1 Nylon 66 by batch or continuous polycondensation. 97
10-1 Phenol-formaldehyde resin using one. step or two 109
step processes.
11-1 Polyester fibers using DMT/TPA processes. 124
12-1 HDPE by liquid-phase (diluent) processes. 142
12-2 HDPE by gas-phase processes. 149
13-1 LDPE by liquid-phase (high-pressure) processes. 160
13-2 LDPE by gas-phase (low-pressure) processes. 167
14-1 Polypropylene - Continuous slurry process. 180
15-1 Polystyrene by suspension, bulk, or bulk-suspension 191
processes.
16-1 Polyvinyl acetate - Emulsion polymerization. 209
17-1 Polyvinyl alcohol - Solution polymerization. 218
18-1 Styrene-butadiene latex using emulsion polymerization. 232
19-1 Unsaturated polyester resin using fusion or solvent 247
processes.
20-1 Urea formaldehyde resin - Batch process. 257
VII
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TABLES
Tables Page
3-1 VOC Data Summary and Results For Plastics Ranking 12
3-II Ranking Comparison 13
5-1 Producers of Acrylic Resins and Related Products 22-26
5-II VOC Emissions from Acrylic Resins - Bulk/Solution 31
Processes
5-III VOC Emissions From Acrylic Resins - Emulsion/ 38
Suspension Processes
6-1 Estimated Consumption of Alkyd Surface Coatings By 44
Major Market, 1976 - 1981
6-II Estimated Consumption of Industrial Alkyd Surface 45
Coatings
6-III VOC Emissions from Alkyd Resins By Solvent Process 53
7-1 Producers of Amino and Phenolic Resins 61-72
7-II VOC Emissions From Butylated Melamine-Formaldehyde 78
Resin
8-1 Nylon 6 Yarn, Staple, and Tow Annual Capacity as of 86
September 1976
8-II VOC Emissions From Nylon 6 - Continuous Chip Process 90
9-1 Nylon 66 Yarn, Staple, and Tow Annual Capacity as of 91
September 1976
9-II VOC Emissions from Nylon 66 Batch or Continuous Process 102
10-1 VOC Emissions from Phenol Formaldehyde Resins 113
11-1 Polyester Yarn Staple and Tow Producing Companies 120-122
as of September 1977
11-11 VOC Emissions from Polyester Fiber - DMT Process 127
ll-III VOC Emissions from Polyester Fiber - TPA Process 132
12-1 U.S. Manufacturers of HOPE Resins and Their Locations 139-140
and Capacities
12-11 VOC Emissions from HOPE - Solvent Processes 144
12-111 VOC Emissions from HOPE - Gas Phase Processes 151
viii
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TABLES
Continued
Tables . Page
13-I(a) Summary of U.S. Manufacturers of LDPE Resins and Their 155
Capacities
13-I(b) U.S. Manufacturers of LDPE Resins and Their Locations 157
and Capacities
13-11 VOC Emissions from LDPE - Liquid Phase (High Pressure) 162
Processes
13-111 VOC Emissions from LDPE - Gas Phase (Low Pressure) 168
Processes
14-1 U.S. Producers of Polypropylene Resins 177-178
14-11 VOC Emissions from Polypropylene -. Continuous Slurry 183
Process
15-1 U.S. Producers of Polystyrene Resins 189-190
15-11 VOC Emissions from Polystyrene Resin Manufacture 196
16-1 Producers of Merchant PVAc Emulsions and Resins 204-205
16-11 Producers of PVAc Emulsions and Resins for Compounding 206
16-111 VOC Emissions from Polyvinyl Acetate Latex - Emulsion 216
Polymerization
17-1 U.S. Producers of Polyvinyl Alcohol . 216
17-11 VOC Emissions From Polyvinyl Alcohol Manufacture 222
18-1 U.S. Producers of Styrene-Butadiene Latexes 230-231
18-11 VOC Emissions from Styrene-Butadiene Latex - Emulsion 234
Polymerization
19-1 U.S. Producers of Unsaturated Polyester Resins 240-243
19-11 Common Raw Materials For Unsaturated Polyester 244
Manufacture
19-111 VOC Emissions From Unsaturated Polyester Resin - Fusion
or Solvent Processes 250
20-1 VOC Emissions From Urea Formaldehyde 259
IX
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SECTION 1
INTRODUCTION
Pullman Kellogg performed this study for the Environmental
Protection Agency (EPA) under Contract Number 68-02-2619 , Work
Assignment No. 7. The study ranks the plastics surveyed for the
.impact on volatile organic compound (VOC) emissions that new
source performance standards (NSPS) would have. In alphabetical
order, the plastics studied were:
Acrylics
Alkyds
Melamine Formaldehyde
Nylon 6
Nylon 66
Phenol Formaldehyde
Polyester Fibers
High Density Polyethylene
Low Density Polyethylene
Polypropylene
Polystyrene
Polyvinyl Acetate
Polyvinyl Alcohol
Styrene Butadiene Latex
Unsaturated Polyester Resins
Urea Formaldehyde
The objectives of this study were to estimate the amount of VOC
that could be prevented from going to atmosphere during the
period 1979 through 1989 if new production facilities constructed
during this period met NSPS and to rank the sixteen plastic
industries according to their potential for reducing VOC. The
production facilities included for each of the 16 industries
studied were monomer storage; polymerization; and plastics
processing, handling, and storage.
-1-
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The study was completed by obtaining background information about
the sources of VOC emissions from manufacturers that polymerize
and process the chosen polymers. The information obtained was
used to determine the magnitude of the current emissions, to show
their sources (vents, etc.), and to estimate their growth rate
and the level of control achievable.
The scope of the study included an evaluation and report based on
literature surveys, calculation, 114 letters, telephone contacts,
and visits to company headquarters. Data collection was limited
to the 16 plastics listed.
Since a description of the content of this report will aid in
reading it, a brief outline of the approach follows. An
Introduction and Summary establish the parameters and findings of
the report. They are followed by Section 3 on Ranking which
discusses the EPA's Model IV (_!) system which is used to rank the
products.
Section 4, Data and Controls, describes the approach used to
select data, the data obtained, data reduction methods, flowsheet
development, and the VOC tables and controls selected. Sections
5 through 20 describe each of the sixteen plastics products and
are meant to stand alone. Generally these sections begin with an
"Industry Description" sub-section. This sub-section contains a
brief summary of the plastic product and emphasizes name, loca-
tion, and capacity of all known manufacturers; information on
production and growth rates; and the most common processes, raw
materials, and catalysts used. The second sub-section, "Manu-
facturing by (Specified) Process", contains a brief process de-
scription and flowsheet, a table of VOC emissions, and a descrip-
tion of the applicable controls and efficiency. The "References"
list following Section 20 cites all the literature used for the
study.
_ O —
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SECTION 2
SUMMARY
This study ranks plastics industries on the basis of the
calculated impact on VOC emissions that new source performance
standards (NSPS) would cause. The' names of the plastics and the
resultant ranking are tabulated below for convenience in
summarizing the study findings.
RANKING FOR NSPS IMPACT FOR 10 YEAR VOC EMISSIONS REDUCTION
Plastic
Impact
Ranking
Model Impact
(Millions of Pounds - MMP)
HOPE
Polypropylene
LDPE
SB Latex
PE Fiber
Polystyrene
Polyvinyl Acetate
Acrylics
Unsaturated Polyester
Nylon 66
Phenol Formaldehyde
Melamine Formaldehyde
Polyvinyl Alcohol
Nylon 6
Alkyds
Urea Formaldehyde
#1
#2
#3
#4
#5
#6
#7
#8
#9
#10
#11
#12
#13
#14
#15
#16
61.2
18 .2
16.3
15.4
14.3
10.4
6.6
5.7
2.2
1.04
0.96
0.50
0.50
0.20
-0.04
-0.45
— 3 —
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The model used for the ranking, EPA Model IV, calculates the
difference (impact) between emissions under baseline year
regulations and under new source performance standards. The
components of the model are K, the utilization factor; Eg and
EN, which are respectively, emissions factors for the
baseline year regulations and for NSPS; and B and C, the new
capacities used for replacement and for growth. Values of K were
obtained from the literature. Emissions factors, expressed in
units of pounds per 1000 pounds (#/1000#), were determined for
each plastic from data obtained from industry. Capacity and
growth were obtained from industry and the literature and
obsolescence was arbitrarily chosen at 0 and 5%.
Data were obtained for the plastics and flowsheets were prepared
indicating the major VOC emission sources. Tables of VOC
emissions were made showing "Uncontrolled"-, "Current Practice",
and "Well Controlled" emissions factors. Finally, a brief
discussion of applicable control technology was provided.
The following observations were made:
1. EPA's Model IV should be used to rank the plastics surveyed
for the impact of NSPS on VOC emissions. Current emissions,
TA, is also a good indicator of the impact, but it should
not be relied upon for decision making.
2. Because of inherent uncertainty in the data used for the
model, plastics whose rankings differ by only a few percent
like LDPE, SB Latex, and PE Fiber, should be considered as
equal-ranked.
3. The decrease in emissions per plastic in the descending order
of the ranking table is greater than two orders-of-magnitude.
Relatively large changes in production or emissions would not
likely change these rankings more than one or two places.
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SECTION 3
PRIORITY RANKING
This study and ranking were undertaken because new source
performance standards may be established for those new stationary
sources which contribute significantly to air pollution. The EPA
Model IV (jj priority ranking system, which was developed to
determine priorities in the NSPS setting process, was used in
this work. Section 114 letter responses and information obtained
from visits to various manufacturers was used to obtain emissions
data, and these were combined with other industry data as well as
information from the literature.
Model IV determines the difference or "impact" between emissions
under baseline year regulations and under new source performance
standards (NSPS). The model incorporates a factor for capacity
use and factors for both obsolescence and growth rates.. Various
refinements are available for the model (including the use of
different standards for new and existing plants and for designa-
ted pollutants), but none of these were used in this study.
There are several limitations of Model IV which affect its
applicability to the plastics studied. Among these limitations
are:
1) Little impact is shown for plastics whose production capacity
is on the decline (e.g., alkyds and urea-formaldehyde).
2) Little impact is shown for plastics with either little, or, no
known BDCT or with high fugitive emissions (e.g., acrylics).
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3) The model is sensitive to all the component factors. But two
of these, K and B, are especially variable and hard to
determine. Generally historic K's are desired for consistency
but when using them the model depends on greater-and-greater
time intervals. Estimates for B can be based on depreciation
schedules (tax-based) or on experience, and they probably vary
significantly from industry to industry.
4) The condfidence with which any of the impacts shown should be
valued decreases with time from the base year (1979), and,
therefore, 10 year projections might err appreciably due to
changes in the growth, obsolescence, or utilization rates.
The model is responsive to data updating, and it improves as the
time interval of the impact is reduced. Also it provides a
quantitative estimate of the impact of NSPS. The impact of NSPS
is taken as the difference between emissions under baseline year
regulations (Ts) and emissions under NSPS (TN). The
model relationship is:
(Ts - TN) = K (Es - EN) (B + C)
(1)
from Ts = KES (A - B) + KEg (B+C) and
TN = KES (A - B) + KEN (B+C)
Where:
Ts = total emissions in the ith year under baseline year
regulations (MMP)
TN = total emissions in the ith year under new or revised
NSPS which have been promulgated in the the jth year
(MMP)
K = normal utilization rate of existing capacity, (ratio of
production to capacity) assumed constant during time
interval
Eg = allowable emissions under existing regulations (mass/
unit capacity) _,-_
-------
EN = allowable emissions under NSPS (mass/unit capacity)
A = baseline year capacity (production units/yr)
B = capacity from construction and modification to replace
obsolete facilities (production units/yr)
C = capacity from construction and modification to increase
output above baseline year capacity (production units/yr)
The values of K used in the model have either an historic or a
recent (1978 - 1979) data base. Historic values were used most
and were obtained from the literature. Often the appropriate SRI
documents were the source (See References) for historic K values.
For HDPE, LDPE, Polypropylene, Polyester Fiber, and Polystyrene,
recent data were available and were used (2) . Of the top six
ranked plastics, all impacts were calculated from current K data
except that for SB latex. Current K's were calculated from known
1978 production and the construction growth rate (P^) and es-
timated 1979 industry capacity. Generally, utilization rates
cluster around 0.8 to 0.9 representing production of 80 to 90% of
name plate capacity.
The emissions factors, Eg and EN, were obtained from
industry data (see Sections 5 through .20) and were.based on
actual emissions and actual production (not capacity) data. It
was recognized that these factors might change with changes in
production, but because such changes were not predictable, Eg
and EN were used as obtained. The values obtained were low
compared to those for the major acrylonitrile using polymer
industries, for example (3J .
The construction rate necessary to replace obsolete equipment,
Pg, was arbitrarily chosen at two values, 0 and 0.05, for
comparison purposes. Because of this, Table 3-1 has two columns
of estimated VOC emissions reductions, Tg-TN, one for
each PB value assumed.
-7-
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Figure 3-1 illustrates the effects of both B and C on the
applicability of NSPS with time. Thus, given initial capacity A
in the baseline year (1979), the effect of B, capacity
replacement due to obsolesence, is to reduce the capacity (A-B)
regulated by the existing standards and increase that regulated
by NSPS. Likewise the effect of C, capacity addition for growth,
is to increase the capacity (B+C) regulated by NSPS. Thus, both
B and C are working with time to increase the capacity regulated
by the new standards.
All the capacity variables in the model (A,B and C) are assumed
to be related and B and C may be expressed as functions of A.
Simple growth was assumed for B to reduce the errors^
introduced over large time spans and compound growth was assumed
for C.
Thus, with B limited to simple growth and C to compound growth,
B = [PB 10]A and
C = [(Pc + l)10_i]A
all baseline year capacity, A, has been replaced by
capacity, B, (constructed to replace obsolete equipment) 100% of
the industry capacity is regulated by NSPS and no further growth
of the regulated percent (100%) is possible. Either method of
growth (simple or compound) applied to B for a long enough time
will result in calculated values of B that exceed 100% of A.
Use of simple growth instead of compound simply prolongs the
time until this occurs. A better method would be to limit B to
the value of A as a maximum.
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Q
W
s
CO
0
co
o
U
"
TOTAL END-OF-PERIOD CAPACITY
A (BASELINE YEAR CAPACITY)
END OF f(P^) PERIOD CAPACITY
___ _^^_ — B _____ _____ ______ ______ _____
REGULATED BY EXISTING STANDARDS
REG. BY
EXIST.
STDS.
YEARS i
(A-B)=CAPACITY REGULATED BY EXISTING STANDARDS.
(B+C)=CAPACITY REGULATED BY NSPS.
Figure 3-1.- Capacity regulated by existing standards and by NSPS versus
year since NSPS promulgation.
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Where:
Pg = construction and modification rate to replace obsolete
capacity (decimal fraction of baseline capacity/yr)
PC = construction and modification rate to increase industry
capacity (decimal fraction of baseline capacity/yr)
10 = elapsed time, years
For the purposes of this study, ith year is defined as 1989 and
the jth year is 1979.
The form of the model used for this study was:
(TS-TN) = K(ES-EN) [(PB 10) + (PC+
Table 3-1 is a summary of the data used for calculating the
ranking, and it includes the impacts (emissions reductions) for
both PB = 0 and PB = 5%. Both historic and
current-estimate K's are listed, with the latter footnoted.
Emissions factors, Eg and E^, are based on production as
noted above. Construction growth rate, Pc, estimates are
historic. The estimated 1979 Industry Capacity values, A, were
derived from published data.
The table in Section 2, Summary, orders the industries in
descending value of Tg-TN, thus providing a priority
ranking according to EPA's Model IV.
The priority rankings given in the ranking table are based on the
EPA Model IV in accordance with equation (2) with PB = 5% (5%
obsolescence) for all plastics with positive growth rates
(PQ>O). The two plastics that were studied having negative
growth rates, alkyds and urea formaldehyde, were ranked last
arbitrarily. Table 3-1 shows the data used to apply the model
and is in alphabetical order.
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The data needed to calculate current VOC emissions, TA =
KEg A are included in Table 3-1. Values for TA are
listed in Table 3-II so they can be compared to the impact
rankings Ts - TN* (at 5% obsolescence), and the estimated
1979 capacities, A. Table 3-II lists TS-TN for two,
fixed-obsolescence rates, 0 and 5%, and lists TA and A for
comparison. Refer to Table 3-II. The model rankings are based
on 5% obsolescence but agree between 0 and 5% obsolescence for
the first 12 rankings with the exception of SB latex, #4, and PE
Fiber #5. SB Latex and PE Fiber are close in either case and
switch between ranks #4 and #5. Thus, though obsolescence rate
variations between 0 and 5% may interchange close rankings for
the plastics that were studied, they do not change rankings that
vary significantly.
Next, with two exceptions, [polypropylene, (#2), and PE Fiber,
(#5); and polyvinylacetate, (#7), and acrylics, (#8)], ranking
according to current emissions, TA, shows the same order as
the model through the first 12 rankings. Polypropylene and PE
Fiber both are similar-sized (5000 MM PPY) , plastics industries
with relatively low existing emissions (Eg) and good control
(low EN). Both are experiencing good growth (PC). The
reason for the difference in ranking between th.e model,
Tg-T^j, and current emissions (TA) can be seen in
Table 3-1. TA the product of K, Eg and A is similar for
polypropylene and PE Fibers with TA slightly higher (<10%)
for polypropylene. However, the model takes into account that
polypropylene has better control technology available resulting
in lower estimated EN and greater impact for polypropylene.
Polyvinylacetate and acrylics have their difference in size made
up for by their difference in controllable emissions, and,
therefore, are about equally ranked.
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TABLE 3-1.- VOC DATA SUMMARY AND RESULTS FOR PL'ASTICS RANKING
SECT. PLASTIC
5 ACRYLICS
6 ALKYD
7 MELAMINE FORMALDEHYDE
8 NYLON 6
9 NYLON 66
10 PHENOL FORMALDEHYDE
11 POLYESTER FIBERS
12 HIGH DENSITY
POLYETHYLENE
13 LOW DENSITY
POLYETHYLENE
14 POLYPROPYLENE
!_, 15 POLYSTYRENE
16 POLYVINYL ACETATE
17 POLYVINYL ALCOHOL
18- STYRENE BUTADIENE
LATEX (SB LATEX)
19 UNSATURATED POLYESTER
RESIN
20 UREA FORMALDEHYDE
to
I
0.83
0.85
0.71
0.80
VOC EMISSION
INDUSTRY
FACTOR
K
0.85
0.68
0.80
0.72
0.72
0.80
0.80
FACTORS ESTIMATES NEW/MODIFIED PLANT CAPACITY
EXIST Eo NEW EN FOR GROWTH P FOR REPLACE P
8/1000S #/1000# % %
3.97
0.88
2.81
0.24
0.90
0.60
2.87
1.64
0.19
0.18
NIL
0.21
0.02
0.30
6.7
-1.0
3.5
5
4
4
6.5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
10.28
20.92
1.51
2.93
2.17
0.91
0.69
0.75
0.85
0.80
3.69
3.85
2.54
7.44
2.37
1.89
0.54
0.25
1.40
0.11
2.19
0.44
0.02
8
5.5
8
5
6
8
8
-1.5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
MMPPY
A
2100
1062
261
1049
2153
2102
5050
5480
8245
4795
5373
999
167
856
1735
1382
1979-1989 ESTIMATED
VOC EMISSIONS
REDUCTIONS
(IMPACT)
T - T
MMP
3
-0
0
0
0
0
9
42
9
12
5
4
0
8
1
-0
RATE,
0
.64
.04
.23
.11
.51
.47
.11
.74
.56
.69
.80
.06
.34
.57
.53
.45
V5%
5.73
0.20
0.50
0.20
1.04
0.96
14.30
61.19
16.32
18.17
10.42
6.62
0.50
15.39
2.19
1.16
3.
THE VALUES OF Eg AND EN SHOWN WERE USED IN THE CALCULATIONS AND ARE DERIVED FROM THE VOC TABLES. THESE VALUES
ARE BASED ON PRODUCTION RATHER THAN CAPACITY.
SOME ACRYLIC PRODUCTS CONTAIN WATER OR SOLVENT. CAPACITY (2100) USED FOR ACRYLICS CALCULATIONS WAS ADJUSTED FROM
ESTIMATED 1468 RESIN CAPACITY TO INCLUDE THESE WEIGHTS.
K ADJUSTED FROM HISTORIC TO CONFORM TO KNOWN PRODUCTION/CAPACITY RATIOS.
-------
TABLE 3-II.- RANKING1 COMPARISON
U)
I
RANK
#11
#12
113
#14
#15
#16
1.
PLASTIC
#1
#2
#3
#4
#5
#6
#7
#8
#9
#10
HOPE
POLYPROPYLENE
LDPE
SB LATEX
PE FIBER
POLYSTYRENE
POLYVIHYL ACETATE
ACRYLICS
UNSATURATED POLYESTER
NYLON 66
PHENOL FORMALDEHYDE
MELAMINE FORMALDEHYDE2
POLYVINYL ALCOHOL2
NYLON 6
ALKYDS
UREA FORMALDEHYDE
10 YR
T -T
VUC IMPACT
MMP MODEL
e o%
42.7
12.7
9 .6
8.6
9 .1
5.8
4.1
3.6
1.5
0.51
0.47
0.23
0.34
0.11
-0.04
-0.45
@ 5%
61.2
18 .2
16.3
15.4
14.3
10.4
6.6
5.7
2.2
1.04
0.96
0.50
0.50
0.20
0.20
1.15
1979 ANNUAL
ESTIMATED
EMISSIONS
T , MMPPY
— A
46.3
12.7
27.7
15.2
11.6
10.2
6.3
8.3
1.86
1.40
1.01
0.59
0.32
0.18
0.64
3.2
1979 ANNUAL
ESTIMATED
CAPACITY
A, MMPPY
5480
4795
3245
856
5050
5373
999
2100
1735
2153
2110
261
167
1049
1062
1382
RANKING BY IMPACT. IMPACT BASED ON 5% OBSOLESCENCE RATE (PB) FOR ALL PLASTICS
WITH POSITIVE GROWTH. ALKYDS AND UREA-FORMALDEHYDE WERE BASED ON PB = 0.
2. EQUAL IMPACT.
-------
Referring again to Table 3-II, the model ranks PE Fiber (#5)
close to SB Latex (#4), and not far below LDPE (#3). Thus the
model shows all four plastics ranked after HOPE (polypropylene,
LDPE, SB Latex, and PE Fiber) to be closely ranked with little
impact difference from plastic-to-plastic. However, current
emissions, TA, for the four reflect the large differences in
capacity, A, between LDPE and the others; and in the existing
emissions factor, Eg, between SB Latex and the others.
Although TA ranks polypropylene significantly (>10%) below
LDPE and SB Latex, the model shows that the long-term impact of
NSPS on VOC emissions actually will be slightly greater for
polypropylene than for either LDPE or SB Latex. Thus Model IV
should be used to rank these plastics rather than current
emissions, TA. Surprisingly, rankings #8 through #14 agree
between the model (TS-TN for PB = 5%) and .current
emissions, TA.
Finally though capacity, A, has a direct influence on emissions,
ranking by either the model or current emissions does not relate
to capacity in a direct fashion.
-14-
-------
SECTION 4
DISCUSSION AND DATA
4.1 GENERAL
Some VOC emissions data were received for all the plastics
surveyed. All data were screened and, in cases where there
were questionable data, the manufacturers were contacted to
resolve the questions. This was an important function and,
in some cases, resulted in significant changes. The
resultant data were weighted for the production represented;
and then used with the appropriate bias. Batch data
(generally high emissions) were assumed in all cases where
continuous data were not available and/or the production
split between batch and continuous was not known.
Many vents and emissions sources were combined to reduce the
total number of vents considered in these survey studies.
Every effort was made to gather only similar or related
sources. This merging helped to indicate the nature of the
major emissions sources such as feed section, reactor area,
polymer recovery, etc. The combinations also helped to make
comparisons between processes possible, helped to facilitate
applicable control studies, and helped to arrive at overall
emissions factors Eg and EN.
-15-
-------
4.2 PROCESSES AND FLOWSHEETS
One or two composite flowsheets were prepared for each
plastic surveyed that represent most-used processes.
Specific equipment configurations and the number and types
of process trains will vary quite widely depending on the
product grades, the specific process or processes, and
whether operation is batch or continuous. Block diagrams
provided by industry were combined with classic flowsheets
from the literature to produce flowsheets showing the
primary emissions points. Some of the flowsheets contain
equipment enclosed in dashed boxes to indicate optional
steps or processes for making special products. The aim of
each flowsheet was to represent the process simply and to
facilitate consolidating the emissions.
4.3 CATEGORIES OF PLASTICS AND COMPANY VISITS
The plastics surveyed in this study have been grouped into
three categories based on decreasing process complexity.
Category I plastics contain high volume, continuous, complex
technology processes that generally have only a few
manufacturers - ones who cannot readily switch products.
The products include HOPE, LDPE, polypropylene, polyester
fiber, polyvinyl alcohol, and the nylons. Category 2
plastics contain the products resulting from simple batch
processes with variations. Generally, they have many
manufacturers (and they can sometimes switch products by
changing recipes and operations). This category includes SB
latex and polyvinyl acetate emulsions and also the
formaldehydes, unsaturated polyesters, and alkyds. Category
3 plastics include products that don1t fit into the other
categories. These include polystyrene and acrylics.
-16-
-------
When industry visits were planned, only those companies that
manufacture 5 to 10 of the plastics surveyed were chosen.
The six headquarters visits decided on were chosen to
include all of the Category 1 and 3 plastics, plus those
that produce the largest volume of Category 2 plastic's,
including pheno 1-formaIdehyde , urea-forma 1dehyde,
unsaturated polyster, polyvinyl acetate, alkyds, and SB
latexes.
4.4 VOC EMISSIONS DATA
Detailed VOC emissions data are reported in tables in the
appropriate plastics sections. National emissions factors,
ES"and EN are summarized in Section 3, Table 3-1.
All data reported are in units of #/1000# product, unless
other units are specified with the numbers. Generally, the
data reported in the VOC tables for each section are in
three columns called, "Uncontrolled", "Current Practice",
and "Well-Controlled". Where it is known, "Uncontrolled"
data are either inlet control device values or they are
presently, or recently, uncontrolled emissions estimates.
"Current Practice" data (basis for Eg) are properly
weighted VOC emissions from control device ou.tlets or
estimates as submitted by industry. Finally, "Well
Controlled" data (basis for EN estimates) are estimates
based either on BDCT as submitted by industry or on good
engineering judgement with regard to the nature of the
emission source and applicable controls (see 4.5 below).
4.5 APPLICABLE CONTROLS AND EFFICIENCIES
Methods considered to bring process emissions to a "well-
controlled" or BDCT status included process modifications as
well as add-on control technology. The process
-17-
-------
modifications considered included product stripping to
remove residual monomers/solvents prior to finishing (both
stripping and soaking); increased conversion reactions,
e.g., Urea-Formaldehyde; underwater pelletization; recycle
drying; switching from steam jets to mechanical vacuum
systems; use of vapor return lines and ^-blanket
controls.
Fugitive emissions were not considered controllable, but
reductions are generally achieved by new plants or by major
process changes, and values are shown when available.
The add-on controls considered included flares and thermal
incinerators; catalytic incinerators; water and caustic
scrubbers; water or refrigerated.condensers; carbon
adsorption; once-through-water spray condensers for steam
jets; mist eliminators; and electrostatic precipitators.
Control efficiencies used were based either on data
submitted or on the following guidelines:
Control Assumed Efficiency (%)
(based on 100% capture)
Flares 90
Thermal Incinerators 95-99
Catalytic Incinerators 60 - 98
Scrubbers and Condensers 80-90
Carbon Adsorption 80-90
Water Spray Condensers 80-90
Mist Eliminators 70
Electrostatic Precipitators 90-98
Vapor Return Lines 60
-18-
-------
4.6 DATA REDUCTION
Some form of data reduction was used on most of the VOC
emissions data in the report. Most individual plastics
sections VOC tables are direct estimates of the national
emissions factors, Eg and EN, the table in the
Summary and in Table 3-II. A few, e.g. Acrylics, HOPE and
LDPE had to be weighted between two types of processes
before inclusion in these tables.
The data reduction used to obtain the individual VOC tables
included, for example, weighting for process variations;
assuming fugitive emissions for solution was the same as for
bulk processes; and arbritrary lumping together data for two
processes whose product distribution was unknown (Table
5-III).
4.7 REFERENCES AND CREDITS
Literature references for the whole report are listed at the
end of the report. The references are divided into
"general" and specific (cited). General references are
listed separately and were used for information on the
model, chemical processes, chemicals, control technologies,
etc. Specific references were cited for each industry and
make up the bibliography. However, special notice should be
given the following references because the authors used them
extensively. "Impact of New Source Performance Standards on
1985 National Emissions from Stationary Sources", Volume I,
The Research Corporation of New England. The Chemical
Economics Handbook and the Process Economics Program Reports
of Stanford Research Institute.
-19-
-------
SECTION 5
ACRYLIC RESINS
5.1 INDUSTRY DESCRIPTION
Acrylics are a family of vinyl polymers made from acrylic
acid and methacrylic acid and their esters. The products
range from thermo-plastics to thermosets and from glass-like
sheets, through enamels, to resin powders, to latexes.
Methyl methacrylate, ethyl acrylate and butyl acrylate are
the largest volume acrylic monomers used. Most potential
VOC emissions are these monomers plus whatever solvents,
modifiers, and volatile organic additives are used. Almost
all acrylics are produced in batch processes, and only batch
processes will be treated in this report. The four common
polymerization methods are all used (bulk or mass, solution,
suspension and emulsion) and these may be grouped as
"hydrocarbon-based" or "water-based" processes for
discussion.
The estimated 1978 U.S. production of all acrylics monomers
was 1314 MM PPY for all uses, and indicates 6 to 7% overall
annual growth rate over 1977 (some 31 MM PPY (4_) used in
fiber co-polymers was not included). While nameplate
capacity for acrylic resins was unknown, production was 1100
MM PPY in 1977 (j[) . Using an estimated utilization rate of
85% and an average growth rate of 6.5%, capacity is
estimated to be 1468MM PPY in 1979.
-20-
-------
The estimated 1980 MMA and acrylate ester consumption
markets have been grouped as follows:
Process % Monomers Consumed
Bulk 25 Hydrocarbon-based
Solution 10
Suspension 10 Water-based
Emulsion 55
100
As the table indicates, about 35% of production will be
hydrocarbon-based, and 65% will be water-based. Within
these two groups, the processes have similarities in VOC
emissions, emission points, and applicable controls and
therefore, they will be treated by group.
Although more than a hundred U.S. manufacturers of
acrylics resins are listed (]_, pp 21 - 23), only a few
are large chemical companies that also produce the
monomers. Most of the large monomer producers also make
finished products such as cast sheets and/or latex
paints. Table 5-1 lists all the U.S. acryl-ic resins
manufacturers (ca 1970) and indicates the product
distribution they make. Some of the larger U.S.
producers are Rohm and Haas, DuPont, and American
Cyanamid.
The largest single raw material used is methyl
methacrylate (MMA), the second is ethyl acrylate (EA),
and the third n-butyl acrylate (n-BA) so these make up
the potential monomer VOC. Total use proportions are
estimated (by Pullman Kellogg) to be about 75% MMA, 15%
EA, and 10% n-BA. Product recipes vary widely from 100%
poly MMA (sheets) to 100% poly EA dissolved in toluene
-21-
-------
TABLE 5-1.-
PRODUCERS OF ACRYLIC RESINS AN RELATED PRODUCTS (Concluded)
Company
Tenneco Chem. (NJ)
Thielex Plastics (NJ)
Triangle Conduit & Cable (NJ)
Tylac Chem. Div., Int'l Latex
& Chemical (DL)
U.S. Plastics & Chem., sub.
Kopper Co. (NY)
United Resins Co. (NJ)
Union Carbide (NY)
Union Oil of California (CA)
Upaco Adhesives Inc. (MA)
Vacuum Plastics Corp. (OH)
Vernon-Benshoff Co. (NY)
Westlake Plastics (PA)
World Plastics Extruders (NJ)
Resins
Molding
and
Extrusion
Powder
Solution
or
Emulsion
Or Both
X
X
Films and Sheets
Cast Extruded
Biaxially
Oriented
Rods, Tubes
Standard Profiles
Cast
X
X
Extruded
Yates Company (PA)
-------
TABLE 5-1.-
PRODUCERS OF ACRYLIC RESINS AN RELATED PRODUCTS (Continued)
Company
Resins
Molding
and
Extrusion
Powder
Polymer Industries (CT)
Polytech Co. (HO)
Polyvinyl Chem. (MA)
PPG Industries (PA)
Purethane Div., Easton RS Corp. (NY)
Purex Corp. (CA)
RA Chemical (NY)
Raffi & Swanson (MA)
Rayll Plastics (NY)
Reichhold Chem. (NY)
Research Sales Inc. (NY)
Rohm & Haas (PA)
Rubba, Inc. (NY)
Sandee Mfg. Co. (IL)
Sartoraer Resins, Inc.
Seven-K Color Corp. (CA)
Sherwin-Williams Co. (IL)
Silraar Div., Vistron (CA)
Southern Plastics (SC)
Stanley, A.E. Mfg. Co. (IL)
Standard T Chem. (NY)
Sterling Varnish (PA)
Sun Chemical (PA)
Swedlow, Inc. (CA)
Solution
or
Emulsion
Or Both
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Films and Sheets
Cast Extruded
Biaxially
Oriented
Rods, Tubes
Standard Profiles
Cast
X
X
Extruded
-------
TABLE 5-1.-
PRODUCERS OF ACRYLIC RESINS AN RELATED PRODUCTS (Continued)
I
NJ
Company Resins
Jersey State Chem. (NJ)
Jet Plastics (CA)
Jodee Plastics (NJ) X
Johnson, S.C. & Sons (WI)
Jones-Blair Paint (TX)
Key Polymer Corp. (MA) X
Koro Corp. (MA)
Laminations Inc. (PA)
Landover Mfg. Div.,
National Lead (MD)
Leathertone, Inc. (MA)
M.R. Plastics and Coatings (MO)
3M Co. (MN) X
McClosky Varnish (PA)
Midland Ind. Finishes (IL)
Milligan, J.G. & Co. (WI)
Mobil Chemical (OH)
Monsanto (MO)
Morton Chemical (IL)
Munray Prod't. Div., Fanner MEg . (OH)
National Lead (NY)
National Starch & Chem (NY)
O.C. Adhesives Corp. (NY)
O'Brien Corp. (IN)
Molding
and
Extrusion
Powder
Solution
or
Emulsion
Or Both
Films and Sheets
Biaxially
Cast Extruded Oriented
Rods, Tubes
Standard Profiles
Cast
Extruded
-------
TABLE 5-1.-
PRODUCERS OF ACRYLIC RESINS AND RELATED PRODUCTS (Continued)
Company
Daylite Industries (NY)
Dennis Chemicals (MO)
De Soto Chem. Coatings (IL)
Dimensional Plastics (FL)
Dow Chemical (MI)
Du Pont (DE)
Dura Plastics (NY)
Electro-seal Glasflex (NJ)
Extron Corp. (TN)
Franklin Fibre-Lamitex (DL)
Freeman Chemical (WI)
Fuller, H.B. Co. (OH)
Fusecolor Corp. (NJ)
^ General Latex & Chem. (MA)
(j\ George, P.O. Co. (MO)
I Glidden Co. (MD)
Goodyear Aerospace (OH)
Goodyear Tire and Rubber (OH)
Guardian Chem. Coatings (MI)
Hand R Plastics Inc. (PA)
Heath Tecna Corp. (WA)
Hunt Foods & Industries (CA)
Hyde, A.L. Co. (NJ)
Interchemical Corp. (NJ)
International Coatings (CA)
Isochem Resins Co. (RI)
Resins
Molding
and
Extrusion
Powder
Solution
or
Emulsion
Or Both
Films and Sheets
Cast
Biaxially
Extruded Oriented Cast
Rods, Tubes
Standard Profiles
Extruded
X
X
-------
TABLE 5-1.- PRODUCERS OF ACRYLIC RESINS AND RELATED PRODUCTS (7)
I
to
en
I
Company Resins
Acco Polymers (MI) X
Ace Plastics (NY)
Aero Chemical Prod't (NJ)
Adam Spence Corp. (NJ)
Allied Chemical (NJ)
American Acrylic Corp. (NY)
American Cyanamid (U.S.)
American Mineral Spirit (IL)
American Polymers Inc. (NJ)
Anesite Div., Clow Corp. (IL)
Armstrong Paint & Varnish ( IL)
Ashland Chemical X
Avecor Inc. (CA)
Axel Plastics Res. Lab. (NY) X
Baltimore Paint & Chem. (MD)
BASF Corporation (NY)
Bay Plastics (CA)
Borden Chemical (NY)
Cadillac Plastics & Chem. (MI)
Caig Lab. Inc. (NY) X
Cast Optics Corp. (NJ)
Celanese
Chemical Coatings & Engineering (PA)
Clearfloat Inc. (MA)
Colab Resin Corp. (MA)
Colonial Kolonite Co. (IL)
Columbia Technical Corp. (NY)
Columbian Carbon Co. (NY)
Contours Unlimited (MA)
Cook Paint & Varnish
Crystal-X Corp. (PA)
Custom Chemical (NJ)
Molding
and
Extrusion
Powder
Solution
or
Emulsion
Or Both
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Films and Sheets
Cast
Biaxially
Extruded Oriented
Rods, Tubes
Standard Profiles
Cast Extruded
-------
(laquers) and include many miscellaneous acrylates and
organic additives. All present U.S. MMA production uses
the acetone cyanohydrin process and is dependent on both
the acetone and methanol supply situation.
The most common poly-acrylate solvents and process
liquids, and thus potential non-monomer VOC, are toluene,
methanol, acetone and methylene chloride. Toluene is
likely the plant solvent-of-choice for clean up as well as
the most likely process and/or product solvent. The
primary use of methanol is to regenerate the ion-exchange
resin beds used to remove hydroquinone (or other
inhibitor) from monomers before polymerization. Acetone
and methylene chloride are alternate solvents.
5.2 ACRYLIC RESIN MANUFACTURE BY HYDROCARBON BASED PROCESSES
5.2.1 Hydrocarbon Based Process Descriptions
Figure 5-1, Acrylic resins manufacture by bulk/solution
processes, is the flow schematic for both bulk and
solution processes. Both are completely hydrocarbon
based, that is process solvents are monomers.or other
hydrocarbons. These processes are simpler than water
based processes because they do not require emulsification
or suspension and have simpler polymer recovery sections
(if required at all). Most of Figure 5-1 is for a bulk
process making cast sheet (above the heavy dotted line)
but below the line alternate equipment and lines are
indicated for a solution process that makes lacquer and
enamel coatings. For clarity two process descriptions are
given (first bulk, then solution) but only one flowsheet,
VOC discussion, table of emissions, and "applicable
controls" section.
-27-
-------
I
NJ
CO
[1]
-r-H
FILTERJ
f
nil I
LIQUID PRODUCT
STORAGE TANKS
MONOMER
SOLVENT/
MIX TANK
FEED
REACT
RECOVERY/FINISH
Figure 5-1.-•Acrylics resins manufacture by bulk/solution-processes. '
r
-------
5.2.1.1 Bulk process.-
A batch process for polymethyl-methacrylate sheets is
described but it applies to all batch monomer and
polymer-monomer syrup casting processes.
Referring to Figure 5-1, above the heavy horizontal
dashed line, the bulk process for cast sheets starts
with inhibitor removal from stored MMA via an ion-
exchange resin bed system. Purified MMA flows from the
resin bed to a monomer surge/mix tank before filtration
and subsequent reaction. A catalyst, usually benzoyl
peroxide, is dissolved in monomer or solvent in a small
tank (not shown) and joins the purified monomer in the
reactor. For the bulk process, reaction is started in
the presence of the catalyst and (if desired)
accelerator by heating to 70-95°C for 5-10 minutes with
constant agitation in the reactor. As soon as
polymerization is adequate (about 10% solids) the
mixture is cooled rapidly to 4°C to halt the
polymerization temporarily. Any additional chemicals
used are added now (plasticizers, U.V. inhibitors,
etc.), and the partially polymerized syrup is dearated
with vacuum to remove bubbles before casting.
Dearated syrup can be stored temporarily at 4°C. For
immediate casting the syrup is reheated, filtered, and
cast. Polymerization is completed in the casting cells
and the sheets are discharged to curing ovens. Cured
sheets are paper coated for protection and sent to
storage or sales. Spent ion-exchanger resin beds are
regenerated with methanol and reused.
-29-
-------
5.2.1.2 Solution process.-
A batch process for copolymer methyl methacrylate/ethyl-
acrylate lacquer is shown. The liquid product is 40%
polymer 60% solvent but various recipes could be used'.
Figure 5-1, Acrylic resins manufacture by bulk/solution
processes, is the flowsheet. Referring to Figure 5-1,
both above and below the heavy horizontal dashed line,
the solution process for coatings starts with inhibitor
removal from stored monomers. Both MMA and EA monomers
are fed to ion-exchange resin beds and the purified
monomers flow to a surge/mix tank. Toluene solvent is
fed from storage to the monomer/solvent mix tank and
blended with purified monomers from the monomer
surge/mix tank. A separate flow of toluene goes to a
catalyst and solvent mix tank (not shown). From the
monomer and solvent mix tank the mix flows through a
filter to the reactor. Catalyst and solvent mix is fed
to the reactor and polymerization is begun by heating.
Reactor cycles are long and may be complex as solution
polymerization is slower than bulk, suspension or
emulsion polymerization. Polymerization is essentially
completed in the reactor. Product flows from the
reactor to the liquid product storage tank without
filtering. Liquid product goes directly to a finishing
line (pails) or to bulk shipment.
5.2.2 VOC Emissions For The Hydrocarbon Based Processes
All significant emissions from acry1ic-resin
manufacturing by hydrocarbon based processes are shown
in Figure 5-1 and listed in Table 5-II with bracketed
numbers (8_) . The tabular values in Table 5-II were
calculated from industry product distribution data. The
-30-
-------
TABLE 5-II.- VOC EMISSIONS FROM ACRYLIC RESINS MANUFACTURED BY BULK/SOLUTION PROCESSES
Stream
Uncontrolled
(Bulk Only) Current Practice Well Controlled
#/1000f Product #/1000# Product #/1000# Resin Composition
U>
H
I
[1] Monomer and Solvent
Storage and Handling —
[2] Monomer Mix Tanks,
Reactor/De-aerator,
Polymer Surge Tank —
[3] Casting, Cells and Shapes 20
[4] Curing, Product Storage 30
[5] Fugitive, includes Solvent
Cleaning of Equipment —
TOTALS 50
0.09
0.09
Pure VOC
2.55
2.46
0.54
3.75
9 .4
0.26
0.25
0.05
3.75
4.4
VOC in N2
VOC in air
VOC in air
VOC in air
-------
distribution was assumed to be (25/35) = 70% bulk, and
(10/35) = 30% solution products.
Note that VOC emissions are based on pounds of actual
product which may include up to 60% solvent for solution
products (lacquers and enamels) but none for bulk since
the products are cast sheets and molded shapes.
The major emission points of these processes are:
[1] Monomer and solvent storage and handling - The
emissions are working and breathing losses from
tankage as well as valve and line losses and pump
seal leaks (storage and handling only).
[2] Monomer mix tanks, reactor/.deaerator and polymer
surge tank - Emissions arise from working losses on
all tanks and reactors and consist of monomers and,
for solution processes, solvent vapors in N2«
Emissions also arise from deaerating bulk process
syrup, from evacuating the reactor to remove oxygen
before the batch and from the polymer surge tank.
[3] Casting, sheets and molded shapes - For bulk pro-
cesses only, deaerated and partially polymerized
syrup is cast or molded then completely polymerized.
Emissions are monomer vapors only and arise from
filling the molds with syrup and from
polymerization. Solution processes have no
comparable step.
[4] Curing and product storage - For sheets, products
are oven cured. Lacquers and other liquid solution
products are stored for bulk shipment or packaged.
Emissions are residual monomers from sheets and
solvent vapors from liquid products during
packaging.
-32-
-------
[5] Fugitive - The majority of these emissions are plant
cleaning solvent, usually toluene. Emissions arise
from washings required to remove polymerized
material from pipes, agitators, coils etc. when
changing recipes and cleaning equipment. Some waste
materials (syrups) are also polymerized and land
filled for disposal and therefore emit some monomers
and solvent.
5.2.3 Applicable Controls Systems For The Hydrocarbon Based
Processes
[1] Monomer and solvent storage and handling - Present
emissions are relatively small. Existing controls are
primarily conservation vents on fixed-roof tanks.
Some tanks have cooling water condensers on the vent
for volatile solvents. Refrigerated vent condensers
can be used for methyl methacrylate monomer. No
additional controls are presently warranted.
[2] Monomer mix tanks, reactor/deaerator, polymer/syrup
surge tanks - These vent streams constitute one of the
largest emission points. Emissions are working losses
on tankage, inert gas purges, and vacuum deaeration.
All losses are VOC in small flows of N2• Existing
controls are generally limited to a reflux condenser
on the reactor. Applicable controls are refrigerated
condensers or incinerators. It was assumed 90%
control could be achieved.
[3] Casting, sheets and molded shapes (Bulk processes
only) - One of the largest emission sources for
acrylics processes, VOC are monomer vapors arising
during mold filling and polymerization. Ventilation
is provided for worker health and flows are generally
too large for direct control. Applicable controls
require tighter hooding to reduce flows; incineration,
-33-
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especially in an existing boiler, should be examined.
It was assumed 90% control could be achieved.
[4] Curing and product storage (For sheets and shapes,
products are oven-cured) - VOC are unreacted monomers
in large flows of air. Relatively small emissions may
not warrant additional controls. For solutions warm
products are pumped into cooling/surge tanks before
packaging or bulk storage. VOC are solvents in
air/N2 from working losses of these tanks.
Applicable controls are refrigerated condensers and
incinerators and 90% efficiency was assumed.
[5] Fugitive - Emissions are solvent VOC in air from
cleaning and residual monomers in scrap and waste.
These are a major VOC emissions point for hydro-
carbon-based acrylics resins.. Applicable controls
include alternate disposal for partially polymerized
scrap and waste syrup (incineration instead of
landfill) and better housekeeping. No control
efficiency was assumed.
5.3 ACRYLIC RESIN MANUFACTURE BY WATER BASED PROCESSES
5.3.1 Water Based Process Description
Both emulsion and suspension processes use water as a
process fluid and require special steps to achieve
emulsification or suspension. Most emulsion process
acrylics are sold as a latex product (paints, adhesives
etc.) and thus do not require complex recovery systems as
do suspension process acrylics. Figure 5-2, Acrylic
resins manufacture by emulsion/suspension processes, is a
schematic showing both processes. The left side of'Figure
5-2 is common to both emulsion and suspension processes.
On the right side the upper train is for emulsions only
and produces a latex product. The lower right side train
-34-
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[5]
I
U)
Ul
I
SUSPENSION
CATALYST
T .
N
PROCESS EMISSIONS
MONOMER
MIX TANK
EMULSION
CATALYST, <-••
EMULSIFIERS
OR SUSPENSION
AGENTS
SLURRY
SURGE
TANK
EXTRUDER-
PELLETIZER
FOR
CLEANING,
RINSING
EMULSIONS
TO PACKAGING
OR SHIPPING
WWT
RESINS TO
PACKAGING OR
BULK SHIPPING
FEED REACT . RECOVERY/FINISH
Figure 5-2.- Acrylics resins manufacture by emulsion/suspension processes.
-------
shows a brief suspension polymer-recovery system. Two
process descriptions have been developed, one for
emulsions and one for suspensions; but the other
information is combined and only one flowsheet, VOC
discussion, table of emissions, and controls section" is
used.
5.3.1.1 Emulsion process.-
A batch process for a methyl methacrylate/ethyl acrylate
emulsion co-polymer latex with 40% solids content is
described in this text, but it represents a variety of
recipes and emulsion products. Reference to Figure 5-2
will aid in following the discussion.
Demineralized water is emulsified with surfactants,
catalyst, small amounts of monomers, and other additives
in the additive mix tank. This flows to the reactor.
Next, MMA and EA monomers flow to a monomer mix tank
then through a filter to the reactor where they join the
emulsified water, surfactant, catalyst, and additives.
The reactor is heated to initiate polymerization and
taken through a batch cycle resulting in about 98-99%
monomer conversion. The resulting latex is vacuum
stripped in the reactor to remove residual monomers then
discharged via a cooling and surge tank to product
storage. The final step for latex is packaging or bulk
shipment. Latexes are difficult to purify and
emulsifiers, catalysts, and other additives cannot be
removed and are generally sold with the product.
Although no monomer inhibitor removal steps are shown
(low-inhibitor grade monomers are assumed) any of the
three classic means could be used, ion-exchange ,
distillation, and caustic washing.
-36-
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5.3.1.2 Suspension process.-
A batch process for a methyl methacrylate/ethyl acrylate
suspension co-polymer resin is described in this
section. There is an extruder-pelletizer in the
finishing line, but the process produces resin powder
without it. A variety of recipes and resultant resins
can be produced. Low-inhibitor grade monomers are
assumed.
Reference to Figure 5-2 shows that the description for
the suspension process is the same as for the emulsion
process up to the cooling tank after the reactor - with
two exceptions. One exception is that suspension or
dispersion agents are used in place of emulsifiers, and
the other is that catalyst is added directly to the
reactor rather than the mix tank. Suspension (slurry)
leaving the cooling tank is dewatered in a centrifuge,
the resulting resin powder is dried in a hot-air drier
prior to finishing. Dried resin powder can be the final
product and either packaged or bulk shipped or it can be
processed into pellets via the extruder-pel le ti zer .
Suspension products are low in residual additives as
these are removed with the water during dewatering and
sent to wast'e water treatment (WWT, not shown) .
5.3.2 VOC Emissions For The Water Based Processes
All significant emissions from acrylic resin
manufacturing by water-based processes are shown in
Figure 5-2 and listed with bracketed numbers in Table
5-III. The VOC values in the table were calculated from
industry data assuming (55/65) = 85% emulsion and
(10/65) = 15% suspension products.
-37-
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TABLE 5-III.- VOC EMISSIONS FROM ACRYLIC RESINS EMULSION/SUSPENSION PROCESSES*
Uncontrolled
(Bulk Only) Current Practice Well Controlled
Stream it/10001 Product #/1000# Product fl/1000# Resin Composition
[1] Monomer and Solvent
Storage 0.15 0.15 0.06 Pure Monomers
and Solvent
[2] Monomer Mix Tanks,
Reactor/Stripper, Monomers and
Surge/Cool 0.48 0.48 0.05 Solvent VOC
in N2
[3] Dewatering, Drying* 0.42 0.42 0.04 Residual Monomers
' in Air
OJ
oo
I [4] Extrusion, Finishing,
Packaging* 1.26 0.00 0.00 Residual Monomers
in Air
TOTALS 2.31 1.05 0.15
* Assumes that emulsions are 85%, suspensions 15%, of water based processes; dewatering,
drying, extrusion and finishing apply to suspension processes only.
-------
Note that VOC emissions are based on pounds of actual
product which includes up to 60% water for emulsions
(latex) but none for suspensions since the products are
resin powders or extrusions.
The major emission points of these processes are:
[1] Monomer and solvent storage and handling - Emissions
released are working and breathing losses from
tankage as well as valve and pump seal and line
losses during loading and transfer. A solvent may
be used for clean up and for ion-exchange bed
regeneration (usually methanol, not shown on Figure
5-2) but only storage and transfer losses are
included here. Emissions are pure monomer and
solvent vapors, primarily.
[2] Mix tanks, polymerizer/stripper and latex cooling
tanks - Emissions come from working losses on
tankage plus residual monomers stripped. All
emissions (VOC) are monomers in a flow of N2•
Both emulsions and suspensions can have these
emissions.
[3] Dewatering, drying - For suspension processes only,
because acrylic emulsions are used as emulsions and
not subjected to recovery. Suspension process
products are recovered by dewatering (screens,
centrifuge) and drying. Emissions are residual
monomers in air from these operations.
[4] Extrusion, finishing and packaging - Extrusion and
finishing emissions shown are for suspension
processes only. Some emulsions are packaged into
small cans and have a very small potential VOC from
packaging. Emissions are residual monomer vapors in
ventilation air.
-39-
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No data were available on fugitive emissions from
either emulsion or suspension processes. However,
water-based processes are expected to have much
lower fugitive VOC emissions than hydrocarbon-based
processes because of the reduced opportunity for VOC
emissions from leaks, spills and cleaning.
5.3.3 Applicable Control Systems (Water Based Processes)
[1] Monomer and solvent storage and handling - As with
hydrocarbon based acrylics, present emissions are
relatively small and existing controls usually are
limited to conservation vents on fixed roof tanks
perhaps with cooling water condensers for the more
volatile substances. Refrigerated (ca 14°F)
condensers are sometimes used on MMA and should
achieve about 90% reduction in VOC. No additional
controls seem presently warranted.
[2] Monomer and additive mix tanks, polymerizer/ stripper
and latex cooling tanks - Presently there are few
controls on the mix tanks and cooling tanks and
cooling water or refrigerated condensers would be
applicable and could achieve up to 90% VOC reduction.
Most polymerizer/strippers presently have cooling
water condensers for economic reasons. High (>90%)
emissions reductions have been achieved for steam
ejector vacuum systems in similar service by spray
condensers. This system (spray condensers for
steam-jet evacuators) seems attractive for control
where applicable but creates a waste-water.
[3] Dewatering and drying - For suspension processes only.
Emissions are machine ventilation and dryer exhaust
and are presently unabated. Again, as in storage,
controls do not seem warranted at present. However
-40-
-------
one means of control that may be available is
incineration in an existing boiler. If incineration
is used actual combustion efficiency of VOC reduction
will exceed 90%. However, recycle of dryer air and
purges and/or flow splitting will probably limit
reductions to <90%.
[4] Extrusion, finishing and packaging - Extrusion and
finishing only apply to suspension processes.
Emissions of residual monomer vapors are collected by
ventilation equipment. If uncontrolled, these
emissions can be the largest VOC source in water-based
acrylics manufacture. Tightly hooded or enclosed (as
in an extruder- devolatilizer) equipment can be
evacuated and controlled by a steam-jet evacuator and
spray condenser. Well over 90%. VOC reduction can be
achieved; but, again, a waste water will be produced.
-41-
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SECTION 6
ALKYD RESINS
6.1 INDUSTRY DESCRIPTION
Alkyd resins are a type of polyester resin (a condensation
reaction product of polybasic acids or anhydrides and
polyhydric alcohols) . Alkyds are distinguished from other
polyester resins in that alkyds contain fatty oils or fatty
acid as a third component. The fatty acids are usually in
the form of naturally occurring oils, such as linseed, soya,
and tung oils. Alkyds may be modified by co-reacting with
other synthetic resins or monomers, and may be blended with
other resin systems to expand their range of properties.
Alkyd resins are marketed primarily as a liquid solution
with an aliphatic or aromatic solvent. The resin is used
mainly for surface coatings, including oil based paints.
About 95% of alkyd resins produced are consumed in surface
coatings with most of the remaining 5% being consumed in
printing ink vehicles (9_) .
The most common reactants are phthalic anhydride (polybasic
acids or anhydrides), pentaerthrito 1 and glycerin
(polyhydric alcohols), and linseed and soybean oils (fatty
oils or fatty acids). Other polybasic acids utilized are
isophthalic, maleic and fumaric acid.
•42-
-------
The popularity of alkyd coating resins has been due to
their low cost, ease of application, and great
versatility. Among the more important trade sales
applications of alkyd surface coatings are solvent-based
interior and exterior enamels. Typical industrial end
uses include finishes for metal furniture, machinery and
equipment, wood furniture, and general maintenance.
One of several methods for classifying alkyd coating
resins is by type and/or amount of oil (or fatty acid) in
the resin. The type of oil determines if the alkyd will
be a drying (polymerizable) or nondrying type.
No production capacity data exist for this industry.
Capacity estimates may vary because, the same equipment can
be used to manufacture other products such as plasticizers
like di-octyl phthalate (OOP) and unsaturated polyester
resins. However, an historic utilization factor of K =
0.68 (_!) was combined with an estimated 1% annual
production shrinkage to provide a 1979 capacity estimate
of 1062 MM PPY for the model.
In 1976 over 265 million gallons of alkyd surface
coatings, containing about 700 million pounds of alkyd
resin solids, were produced in the United States. The
sales value of these alkyd-containing coatings was
estimated at about 1.7 billion dollars. The following
table summarizes the U.S. supply/demand situation for
alkyd surface coatings in 1976. Also, Table 6-1 (JL.O)
gives some consumption (demand) details as well as
estimates of growth, and Table 6-II (11) gives details for
industrial alkyd consumption.
-43-
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TABLE 6-1.- ESTIMATED CONSUMPTION OF ALKYD SURFACE COATINGS BY MAJOR MARKET, 1976 and 1981 (10)
1976 1981
Trade Sales
Exterior
Interior
Miscellaneous
Industrial
Product Finishes 100
Maintenance
Total
Coatings
(millions of gals)
135
Alkyd Resin
Solids Content
(millions of Ibs)
365
Alkyd Resin
Coatings Solids Content
(millions of gals) (millions of Ibs)
110
300
40
40
55
00
30
140
115
110
130
245
85
30
30
50
330
95
30
105
90
105
125 315
230
85
-5.5
-5.0
-1.0
-1.0
0
265
695
235
615
Average Annual
Growth Rate
1976-198la
(percent)
-4.0%
-1.0%
-2.5%
a. Growth rates are rounded to nearest one-half percent.
-------
TABLE 6-II.-ESTIMATED CONSUMPTION OF INDUSTRIAL ALKYD SURFACE COATINGS
1976
Ul
I
End Uses
Coatings
(millions of gals)
Alkyd Resin
Solids Content
(millions of Ibs)
1981
Alkyd Resin
Coatings Solids Content
(millions of gals) (millions of Ibs)
Product Finishes 100
Machinery and
Equipment 16
Metal Furniture
and Fixtures 13
Factory-Finished
Wood 15
Wood Furniture
and Fixtures'3 25
Automotive, OEM 11
Topcoat <1
Primer 4
After-Market and
Miscellaneous 7
Trucks and Buses 4
Containers and
Closures 5
Insulation Varnishes 3
Sheet Strip and Coil 2.5
Other Trans., OEMC 2
Appliances 1.5
Other Product Finishes^ 2.5
Maintenance Coatings
Exterior
Interior
Marine
Total6
15
12
3
0.5
13
17
30
130
245
46
35
35
35
30
15
14
9
42
35
8
85
330
18
15
13
25
7
16
12
2
95
30
125
50
40
30
35
23
10
13
6
6
15
45
35
5
230
Average Annual
Growth Rate
1976-19813
(percent)
-1.0%
85
315
-1.0%
a. Growth rates are rounded to the nearest one-half percent.
b. Includes nitrocellulose lacquers plasticized with alkyd resins.
c. Includes coatings for railroad equipment, aircraft, and miscellaneous transportation equipment.
d. Includes miscellaneous products such as toys, sporting goods, and gym equipment.
e. Totals may not equal the sums of the categories due to rounding.
-------
STATUS OF ALKYD SURFACE COATINGS - 1976 (10)
ALKYD RESIN
COATINGS SOLIDS CONTENT
(Millions of Gallons) (Millions of Pounds)
Production 267 700
Domestic Consumption 265 695
Trade Sales 135 365
Industrial Products 130 330
Exports 2 5
Alkyd formulations are the predominant types of surface
coatings currently in use. They can be tailored to meet a
variety of end-use requirements through the choice and
ratio of reactants and/or modifiers. However, in recent
years some of the advantages of alkyds have diminished and
the trend away from solvent-based coatings toward
water-based systems has intensified. The demand for alkyd
coatings declined steadily from 1973 through 1975; but in
1976 alkyds still made up about 30% of the resins consumed
in surface coatings.
Consumption of alkyd surface coatings is expected to
decrease about 2.5% annually between 1976 and 1981 (10).
By 1981 an estimated 235 million gallons of alkyd systems
(615 million pounds of alkyd resin solids) will be
consumed domestically, compared with approximately 265
million gallons (695 million pounds of solid resin)
consumed in 1976. The major reason for the diminishing
demand for alkyd systems will be intensified antipollution
regulations regarding solvent use and emissions (as
requiring the removal of solvents from coating systems) .
Beyond 1981 the rate of decline for conventional
-46-
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solvent-based alkyd formulations will probably begin to
accelerate. (See Table 6-1).
The manufacture of an alkyd resin involves such reactions
as esterification, polymerization of unsaturated fatty
acid chains, and ether ification of hydroxyl groups.
Ester ification is the major reaction used. Batch
processing is most commonly used with the reaction taking
place in a jacketed, agitated reactor equipped with a
condenser and a decanter.
Processes for alkyd resin manufacture may be categorized
by the following two systems:
1. Fusion and solvent - by the methods by which fluidity
and water removal are achieved in the reactor. The
fusion and the solvent (or azeotrope) processes are the
important processes in this system and are described
briefly below:
o When the reaction is carried out by heating in the
presence of an inert gas it is called the fusion
process (fluidity of the mass is achieved by heat).
In this case, the water produced by the reaction is
swept out with the inert gas and vented to
atmosphere or collected in a fume scrubber system.
o When the reaction is carried out by heating in the
presence of a solvent it is called the solvent (or
azeotrope) process. The solvent process involves
addition of another liquid (e.g., ethylbenzene or
xylene at a level of 3-10% of the batch charge) to
aid in the removal of water.
-47-
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Although the trend is in the direction of solvent
processing techniques, there will still be a
considerable volume of alkyds made by the fusion
process because;
- There is a large investment in existing plant
installations,
Certain alkyds, such as the isophthalic types,
are more easily made by the fusion process,
- Investment cost is lower on new alkyd
installations,
Safety requirements are less stringent than with
solvent processing equipment.
Fatty acid and alcholysis methods - by the nature of
the ester ification reation (direct one-step or
two-step) which is controlled by the order of
ingredient addition to the reactor and the source of
ingredients. Four basic methods are recognized within
this category; the fatty acid method, the fatty
acid-oil method, the oil-dilution method, and the
alcoholysis method. The fatty acid and the alcoholysis
methods are most important today, and these are
described below.
o Fatty Acid Method - The entire charge of fatty
acids, polyhydric alcohols, and dibasic acids is
heated to reaction temperature (usually 210-250°C,
but as high as 230°C may be used) and maintained
until product specifications are met.
-48-
-------
o Alcoholysis Method - A large proportion of alkyd
manufacture is accomplished by alcoholyzing
triglyceride oils, such as soybean and linseed oil,
with pentaerythritol or glycerol as the additional
polyol. After redistribution of the fatty acid
groups, the partial esters, which now have free
hydroxyl groups, are esterified with dibasic acids
such as phthalic anhydride. The general alcoholysis
method proceeds as follows: The oil is heated to
230-250°C; the sublimed litharge (lead oxide) and
then the polyol are added; and the mixture is
reheated to 230-250°C. One way to follow the course
of the alcoholysis reaction is by noting the
solubility of the mixture in anhydrous methyl
alcohol.
Any of the four methods can be modified further by
manufacturing technique during the esterification cycle.
The ester ification is a condensation reaction with
elimination of water.
Producers of alkyd coating resins can be divided into
groups of companies whose product is for sale .only, for
sale and captive use, or for captive use primarily (little
or no merchant sales). Eighteen companies in the first
category produced approximately one-third of total alkyd
coating resins (solids basis) in 1976. Ashland Chemical,
Cargill, and Reichhold Chemicals are the three largest in
this category. Twenty companies in the second category
also produced approximately a third of the total alkyd
coating resins (solids basis) made in 1976. Celanese,
Cook Paint and Varnish, McCloskey Varnish, Reliance
Universal, and Syncon Resins are believed to be the largest
of these. Thirty-four companies in the third category
accounted for approximately the remaining third
-49-
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of the total alkyd coating resins (solids basis) produced
in 1976. The relative production of these companies and
specific types of alkyd resins produced by them are
unknown.
6.2 ALKYD RESIN MANUFACTURE BY SOLVENT PROCESS
6.2.1 Process Description
The process described here is a one-step solvent batch
process for the production of a resin containing phthalic
anhydride and glycerine and soybean oil and dissolved in
toluene. Figure 6-1 is the process schematic for such a
process. A fusion batch process description, schematic,
and equipment would be very similar but without xylene
solvent reflux, azeotropic distillation, and recovery or
recycle.
The process consists of two main operations - poly-
ester if icat ion and thinning. In pol yes ter i f ica t ion ,
molten phthalic anhydride, glycerine, and soybean oil are
charged into the reactor from storage tanks. The mixture
is agitated and heated (batch) while the reactor and the
overhead condensation system are purged with an inert gas.
Then xylene is added. The polyester if ication is carried
out at 250°C. When the polyesterification reaction
becomes vigorous the water of reaction evolves rapidly.
The temperature at the top of the column is kept at
100-120°C by refluxing xylene from the decanter of the
solvent recovery system to minimize the loss of reactants.
As the reaction approaches completion the evolution of
water from the reaction mixture begins to diminish. The
reflux of xylene is stopped and all the xylene is
distilled from the reactor. An inert gas sparge is then
-50-
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VAPOR
RETURN
PHTHALIC
ANHYDRIDE
STORAGE
STACK
GASES
TO DRUM AND
BULK LOADING
FEED
REACT
RECOVERY
FINISH
Figure 6-1.- Alkyd resins by a batch solvent process.
-------
used to remove residual water and unreacted reactants.
When the polyesterification has reached the desired acid
number, the alkyd resin product is pumped to the thinning
vessel. During the reaction and thinning, some of the
reactants are carried out of the reactor with the water
and thereby lost from the product. After most of the
volatiles are condensed, the vapor exhausted from the
reactor is scrubbed with water before it leaves the
process vent.
In the thinning operation the thinning vessel containing
the required amount of toluene (solvent) is purged with
inert gas and then partially cooled alkyd resin is added
at a rate such that the resin temperature is kept at
about 66°C. The resin is checked for color or refractive
index (or both), acid number, viscosity, and specific
gravity while in the thinning vessel. Additives such as
filter aids, etc., are also added before the thinned
resin is pumped out through the filter to the storage
tanks.
6.2.2 VOC Emissions
All significant emission rates and sources for this
product are shown on Table 6-III. Figure 6-1 is the
schematic flowsheet for this product. It includes the
emission streams and their sources.
The following paragraphs describe the emission streams
that are encountered:
[1] Raw material, solvent, and modifier storage tanks -
Fixed roof storage tanks are used in existing
facilities (except for a floating roof tank for
-52-
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TABLE 6-III.-VOC EMISSIONS FROM ALKYD RESIN - SOLVENT PROCESS
Current
Uncontrolled Practice Well Controlled
Stream #/1000# Resin #/1000#Resin #/1000# Resin
[1] Raw Material, 0.14 0.14 0.06
Solvent and
Modifier Storage
Tanks
[2] Reactor 7.05 0.40 0.10
[3] Thinning Vessel 0.26 .0.09 0.01
[4] Product Storage Tanks 0.13 0.13 0.01
[5] Product Drum and Bulk 0.11 0.11 0.01
Loading Operations
[6] Product Filter 0.01 0.01 nil
Operations .
Totals 7.70 0.88 0.19
-53-
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toluene). Emissions are vapors of the substances
stored (and blanket gas if used), and they result
from vapor displacement (working losses) and tank
breathing. Phthalic anhydride (a solid at ambient
conditions) is stored at elevated temperatures- in
heated, insulated tanks. Toluene, glycerine, and
soybean oil are stored at ambient conditions.
[2] The reactor vent - This stream is the largest
potential emission source in the process. The flow
rate and stream composition vary as the batch goes
through its cycle (as is true for most batch reaction
flows) . The stream carries unreacted monomers and
volatile impurities from the feeds along with inert
gas. Inert gas is added to the reactor to strip
residual volatiles from the product after the
reaction is complete, to aid in water removal, and to
prevent atmospheric oxygen from contacting the
reaction mixture which would result in product
discoloration. The system through which the
resulting emission travels includes the overhead
condenser and aqueous or caustic scrubber the system
also collects small emissions, normally xylene, from
the reactor solvent recovery system.
[3] Thinning vessel - This stream consists of toluene
(solvent) vapor from the overhead condenser in an
inert gas resulting from an inert gas purge flow
maintained to exclude oxygen from the product. Some
of the vapor is from displacement losses when the
vessel is filled from the reactor.
[4] Product storage tanks - Fixed roof storage tanks are
utilized. Emissions are vapors of the solvent (i.e.
toluene) used in the product resin solution and
-54-
-------
result from tank breathing and vapor displacement
(working losses).
[5] Product drum and bulk loading operations - The
emissions are vapors of the solvent (i.e. toluene)
used in the product resin solution and emitted
through vapor displacement when filling product
drums, tank trucks or tank cars.
[6] Product filter operations - Emissions are primarily
vapors of the solvent (i.e. toluene) used in the
product resin solution. The emissions result from
filter operations and maintenance, primarily opening
the filter to clean plates or leaves. They are
fugitive and diluted highly by air.
6.2.3 Applicable Control Systems
The following control technologies are recommended for the
emission streams described in Section 6.2.2 and in the
schematic flowsheet for this product.
[1] Raw material, solvent, and modifier storage tanks - A
floating roof storage tank is used for toluene
solvent. Glycerine and soybean oil have vapor
pressures below the range generally considered to be
VOC. Other tanks in this category should utilize
vapor return lines to the loading tank trucks or cars
in order to eliminate all vapor displacement working
losses occuring during tank filling. This results in
an efficiency level of approximately 58% of the total
tank losses. (Modifiers or reactants used in some
locations or for some special product runs might
require an inert gas blanket/flare or incinerator
systems or floating roofs because of higher vapor
pressures.) Conservation valves should also be used;
they are justified adequately by process economics
-55-
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alone. Aqueous scrubbers also should be used on
phthalic anhydride storage tank vents, primarily for
housekeeping purposes. Phthalic anhydride is a
crystalline solid at ambient conditions that causes
sublimed solids buildup on the cool surfaces adjacent
to tank vents. Quite high VOC removal efficiencies
have been reported for this scrubber application
(.12), (.13).
/
[2] Reactor - An overhead condensing system is used for
process and economic reasons regardless of emissions.
Normally this system consists of a direct condensing
partial condenser or a distillation column and total
condenser. Emissions from the condensing system
should be reduced by aqueous or caustic scrubbing
followed by incineration (thermal or catalytic) .
Minimum efficiencies of 85% for the scrubber and 90%
for the incinerator should be readily obtained.
Various vents from the reactor solvent recovery
system, such as from the decanter, will also use the
reactor scrubber and incinerator, both for
housekeeping purposes and to prevent plugging.
[3] Thinning vessel - A refrigerant cooled
after-condenser with 40°F coolant can be used to
yield a significant reduction without moisture
freeze-up; however, this condenser would normally be
provided anyhow for process economic reasons. The
non-condensibles from the condenser are sent to the
incinerator (thermal or catalytic) which is also
required for the reactor. A minimum of 90%
efficiency is assumed for this system.
[4] Product storage - An inert gas blanket/flare or
incinerator system, or equivalent should be utilized
on the tanks involved here. A minimum of 90%
-56-
-------
reduction efficiency is assumed with these
provisions.
[5] Product drum and bulk loading operation - Use hoods
over all relevant points that are connected to the
incinerator through ducts equipped with fans. Also,
where applicable and practicable, u'se vapor return
lines. Mininum efficiencies of 90% are assumed here.
[6] Product filter operations - A hood is used that is
designed for the filter area and connected to the
incinerator through ducts equipped with fans. (The
system may tie into and use the duct/fans system for
stream [#5] above). A mininum incinerator efficiency
of 90% is assumed.
-57-
-------
SECTION 7
MELAMINE - FORMALDEHYDE RESINS
7.1 INDUSTRY DESCRIPTION
Melamine-formaldehyde resins (MF resins) are aminoplasts,
which are a class of thermosetting resins made by the
reaction of formaldehyde with the amino (-NI^) group of
compounds including melamine, urea, or urea derivatives (one
of these, Urea-formaldehyde Resins, is discussed more fully
in Section 20). The polymerization of melamine-formaldehyde
is analogous to that of urea and formaldehyde with
exceptions related to the different reactivity of the
-NH2 groups in melamine. MF resins are generally made
by a batch reaction in an aqueous medium with the primary
reactions being addition, condensation and polymerization.
The first products of the addition reaction between melamine
and formaldehyde are methylolmelamines and these begin
further (condensation and cross linking) reactions almost
immediately. When sufficiently reacted to provide the
product properties desired the condensation and cross-
linking are stopped by cooling or by chemical means.
MF resins have many properties that are similar to those of
the urea-formaldehyde (UF) resins described in Section 20,
and they are made using a similar technology. Frequently in
fact, they use the same equipment. Like the UF resins, the
MF resins are clear and colorless, and have outstanding
electrical properties. MF resins also provide better
chemical, water, and heat resistance than UF resins, which
justifies their higher price for specialized applications.
-58-
-------
The resin product can be shipped as an aqueous syrup
(approximately 50% of sales poundage), a powder made by
first impregnating syrup into a solid filler, or as a
spray-dried powder. (All types of powder make up the
remaining 50% of sales poundage). The final stage' of
polymerization-cross-linking of linear chains does not take
place, usually, until the resin is cured to its final shape
- an insoluble thermoset product. Resins for molding
powders are generally polymerized further than resins for
syrup applications such as adhesives. Aqueous syrups may be
mixed with other coating formulations, or used to impregnate
fillers, paper, or textiles.
The solution stability of methylolmelamines can be improved
by etherfying the methylol groups formed when formaldehyde
reacts with melamine, usually with an alcohol such as
methanol or butanol. The reaction can also take place on
melamine condensates that have unreacted methylol groups.
Methylated MF resins are water soluble, and the aqueous
syrups are useful for treating textiles to impart crease
resistance. Butylated MF resins are hydrophobic, and are
soluble in organic solvents such as toluene; they are widely
used in surface coatings, such as varnishes and baking
enamel, because they are compatible with alkyd resins and
epoxy resins. A typical product of a batch process for
making butylated MF resin is a syrup containing 58.7% -resin
solids in xylene solvent.
Production of MF resins in 1976 was 188 MM Ibs (dry basis)
(2^, and average market growth rate of 3.5%/yr is projected.
Little production capacity data exist. Production equipment
can be used interchangeably to manufacture MF resins or
urea-formaldehyde resins, and usually phenol-formaldehyde
resins also.
-59-
-------
Approximately 60 manufacturers are known to produce MF
resins in the United States. These producers are shown in
Table 7-1, which also includes the producers of phenolic
(phenol- formaldehyde) and urea-formaldehyde resins (the
latter is the other major amino resin).
7.2 MANUFACTURE OF MELAMINE-FORMALDEHYDE RESIN AND A BUTYLATED
MF RESIN
7.2.1 Process Description
Melamine-formaldehyde syrup is made by the batch reaction
of melamine and aqueous formaldehyde solution. In a
simple basic recipe, the two ingredients are mixed
together and the pH is adjusted with NaOH to about 8.5.
Melamine is not soluble in aqueous formaldehyde at room
temperature, but as the mixture is heated, the melamine is
slowly converted to the soluble methylolmelamines. No
catalyst is necessary, and the addition reaction takes
place easily and more completely than it does with urea.
Condensation between methylolmelamine molecules begins
immediately and as it proceeds hydrophobic intermediates
appear. After about 3 hours, the syrup is tested for
miscibility with water. When the test indicates that the
desired degree of condensation has been reached, the batch
is cooled and impurities are filtered out. Figure 7-1
shows a schematic for making both MF syrup and butylated
MF resin. Some of the equipment shown is needed only for
the butylated MF resin. Both processes are described
further below (17) . Emission data were available only for
butylated MF resin.
-60-
-------
TABLE 7-1.- PRODUCERS OF AMINO AND PHENOLIC RESINS
COMPANY AND PLANT
LOCATION
ALLIED CHEMICAL CORPORATION
Specialty Chemical Division
South Point, Ohio
Toledo, Ohio
Phenol-
Formal-
dehyde
X
AMERICAN CYANAMID COMPANY
Formica Corp.,.subsidiary
Columbia, South Carolina
Evendale, Ohio X
Industrial Chemicals and
Plastics Division
Azusa, California
Longview, Washington
Wallingford, Connecticut
ASHLAND OIL, INC.
Ashland Chemical Co., div
Foundry Products Division
Cleveland, Ohio X
Hammond, Indiana X
Resins and Plastics Division
Calumet City, Illinois X
Fords, New Jersey X
Pensacola, Florida X
AURALUX CHEMICAL ASSOCIATES, INC.
Hope Valley, Rhode Island
THE BENDIX CORPORATION
Friction Materials Division
Green Island, New York X
BORDEN INC.
Borden Chemical Division
Adhesives and Chemicals Div., East
Bainbridge, New York X
Demopolis, Alabama X
Diboll, Texas
Fayetteville, NC X
Louisville, Kentucky
Sheboygan, Wisconsin X
RESIN TYPE
Urea-
Formal-
dehyde
X
X
X
X
X
X
X
X
X
X
X
Melamine-
Form al-
dehyde
X
X
X
X
X
X
X
X
X
X
X
-61-
-------
TABLE 7-I.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Continued)
COMPANY AND PLANT
LOCATION
Phenol-
Formal-
dehyde
RESIN TYPE
Urea-
Formal-
dehyde
BORDEN INC.
Borden Chemical Division
Adhesives and Chemicals
Division - West
Fremont, California X
Kent, Washington X
La Grande, Oregon X
Missoula, Montana X
Springfield, Oregon X
BRAND-S CORPORATION
Cascade Resins, Inc., div.
Eugene, Oregon X
THE CARBORUNDUM COMPANY
Wheatfield, New York X
CARGILL, INC.
Chemical Products Division
Carpentersville, Illinois
Philadelphia, Pennsylvania
CELANESE CORPORATION
Celanese Coatings and Specialty
Chemicals Co., sub., Celanese
Resins Division
Charlotte, North Carolina
Louisville, Kentucky
CHAMPION INTERNATION, CORP.
U.S. Plywood Division
Redding, California X
CLARK CHEMICAL CORPORATION
Blue Island, Illinois X
CNC CHEMICAL CORPORATION
Providence, Rhode Island
COMBUSTION ENGINEERING, INC.
C-E Cast Industrial Products Div.
Muse, Pennsylvania X
X
X
X
X
X
X
X
X
X
X
Melamine-
Formal-
dehyde
X
X
X
-62-
-------
TABLE 7-1.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Continued)
COMPANY AND PLANT
LOCATION
COMMERCIAL PRODUCTS COMPANY
Hawthorne, New Jersey
CONCHEMCO INCORPORATED
Baltimore, Maryland
Kansas City, Missouri
CONSOLIDATED PAPERS, INC.
Wisconsin Rapids, Wisonsin
CONWED CORPORATION
Cloquet, Minnesota
COOK PAINT & VARNISH CO.
Detroit, Michigan
North Kansas, Missouri
CORE-LUBE, INC.
Danville, Illinois
CPC INTERNTIONAL, INC.
Acme Resin Co., division
Forest Park, Illinois
DAN RIVER, INC.
Danville, Virginia
DE SOTO, INC.
Berkeley, California
Garland, Texas
THE DEXTER CORPORATION
Waukegan, Illinois
DOCK RESINS CORPORATION
Linden, New Jersey
THE DUPLAN CORPORATION
Cap-Roc Incorporated, sub.
Capital Plastic Division
Brodhead, Wisconsin
Phenol-
Formal-
dehyde
X
X
RESIN TYPE
Urea-
Formal-
dehyde
X
X
X
X
X
X
X
X
X
Melamine-
Formal-
dehyde
X
X
X
X
X
X
-63-
-------
TABLE 7-1.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Continued)
COMPANY AND PLANT
LOCATION
EASTERN COLOR & CHEMICAL CO.
Providence, Rhode Island
EMKAY CHEMICAL COMPANY
Elizabeth, New Jersey
EXXON CORPORATION
Nevamar Division
Odenton, Maryland
•THE FIBERITE CORPORATION
Winona, Minnesota
FORD MOTOR COMPANY
Mt. Clemens, Michigan
GAF CORPORATION
Chemical Division
Chattanooga, Tennessee
GENERAL ELECTRIC COMPANY
Chemical and Metallurgical
Div., Laminated and Insulating
Materials Business Department
Cosocton, Ohio
Schenectady, New York
Engineering Plastics Product
Department
Pittsfield, Massachusetts
THE P.O. GEORGE CO.
St. Louis, Missouri
GEORGIA-PACIFIC CORPORATION
Chemical Division
Albany, Oregon
Columbus, Ohio
Conway, North Carolina
Coos Bay, Oregon
Crossett, Arkansas
Louisville, Mississippi
Lufkin, Texas
Russellville, SC
Savannah, Georgia
Taylorsville, Mississippi
Tewkesbury, Massachusetts
Ukiah, California
Vienna, Georgia
Phenol-
Formal-
dehyde
RESIN TYPE
Urea-
Formal-
dehyde
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
-64-
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Melamine-
. Formal-
dehyde
X
X
X
X
X
X
X
X
X
X
X
X
X
X
-------
TABLE 7-1.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Continued)
COMPANY AND PLANT
LOCATION
GETTY OIL COMPANY
Chembond Corp., sub.
Andalusia, Alabama
Spokane, Washington
Springfield, Oregon
Winnfield, Louisiana
GILMAN PAINT & VARNISH CO.
Chattanooga, Tennessee
W.R. GRACE & CO.
Agricultural Chemicals Group
Alliance, Ohio
Charleston, South Carolina
Columbus, Ohio
Finley, Ohio
Fort Pierce, Florida
Henrietta, Illinois
Lansing, Michigan
Memphis, Tennessee
San Juan, Puerto Rico
Statesville, North Carolina
Tampa, Florida
Tulsa, Oklahoma
Wilmington, North Carolina
GUARDSMAN CHEMICALS, INC.
Grand Rapids, Michigan
GULF OIL CORPORATION
Gulf Oil Chemicals Co., div.
Adhesives & Resins Dept.
Alexandria, Louisiana
High Point, North Carolina
Lansdale, Pennsylvania
Shawano, Wisconsin
Valleyfield, Quebec
West Memphis, Arkansas
HANNA CHEMICAL COATINGS CORP.
Hanna Chemical Coatings Co.,
Subsidiary
Birmingham, Alabama
Phenol-
Formal-
dehyde
X
X
X
X
X
X
X
RESIN TYPE
Urea-
Formal-
dehyde
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Melamine-
Formal-
dehyde
X
X
X
X
-65-
-------
TABLE 7-1.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Continued)
COMPANY AND PLANT
LOCATION
HART PRODUCTS CORP.
Jersey City, New Jersey
HERCULES INCORPORATED
Organics Department
Chicopee, Massachusetts
,Hattiesburg, Mississippi
Milwaukee, Wisconsin
Haveg Industries Inc., sub.
Marshallton, Delaware
HERESITE & CHEMICAL COMPANY
Manitowoc, Wisconsin
H & N CHEMICAL COMPANY
Totowa, New Jersey
E.F. HOUGHTON & COMPANY
Philadelphia, Pennsylvania
INLAND STEEL COMPANY
Alsip, Illinois
INMONT CORPORATION
Anaheim, California
Cincinnati, Ohio
Detroit, Michigan
Greenville, Ohio
Phenol-
Formal-
dehyde
X
X
X
X
INTERNATIONAL MINERALS & CHEMICAL
CORPORATION Aristo Intl. Corp.
Detroit, Michigan X
THE IRONSIDES CO.
Ironsides Resins, division
Columbus, Ohio
KNOEDLER CHEMICAL COMPANY
Lancaster, Pennsylvania
KOOPERS COMPANY, INC.
Organics Materials Division
Bridgeville, Pennsylvania
KORDELL INDUSTRIES
Mishawaka, Indiana
X
X
X
-66-
RESIN TYPE
Urea-
Formal-
dehyde
Melamine-
Formal-
dehyde
X
X
X
X
-------
TABLE 7-1.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Continued)
Phenol-
Formal-
dehyde
X
COMPANY AND PLANT
LOCATION
LAWTER CHEMICALS, INC.
South Kearney, New.Jersey
MAGNA CORPORATION
Houston, Texas
THE MARBLETTE CORPORATION
Long Island City, New York
MASONITE CORPOTATION
Alpine Division
Gulfport, Mississippi
MILLMASTER ONYX CORPORATION
(a subsidiary of Kewanee Ind.)
Refined-Onyx Division
Lyndhurst, New Jersey
MINNESOTA MINING AND MANUFACTURING
Cordova, Illinois X
Cottage Grove, Minnesota X
MOBIL OIL CORPORATION
Mobil Chemical Company, division
Chemical Coatings Division
Kankakee, Illinois
MONSANTO COMPANY
Monsanto Plastics & Resins Co.
Addyston, Ohio X
Alvin, Texas X
Eugene, Oregon X
La Salle, Quebec
Santa Clara, California X
Springfield, Massachusetts X
NAPKO CORPORATION
Houston, Texas X
NATIONAL CASEIN COMPANY
Chicago, Illinois
Tyler, Texas
RESIN TYPE
Urea-
Formal-
dehyde
Melamine-
Formal-
dehyde
X
X
X
X
X
X
X
X
X
X
X
-67-
-------
TABLE 7-1.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Continued)
Phenol
Formal
dehyde
COMPANY AND PLANT
_ LOCATION
NATIONAL CASEIN OF CALIFORNIA
(affiliate of National Casein)
Santa Ana, California
NATIONAL CASEIN OF NEW JERSEY
(affiliate of National Casein)
Riverton, New Jersey
NATIONAL STARCH AND CHEMICAL CORP.
Proctor Chemical Company, sub.
Salisbury, North Carolina
OCCIDNETAL PETROLEUM CORP.
Hooker Chemical Corp., sub.
Hooker Chemicals and Plastics
Corporation, subsidiary
Kenton, Ohio
N. Tonawanda, New York
RESIN TYPE
Urea-
Formal-
dehyde
X
ONYX OILS & RESINS INC.
Newark, New Jersey
OWENS-CORNING FIBERGLAS CORP.
Resins and Coatings Division
Barrington, New Jersey
Kansas City, Kansas
Newark, Ohio
Waxahachie, Texas
PAT CHEMICAL INCORPORATED
Greenville, South Carolina
PATENT PLASTICS COMPANY
Knoxville, Tennessee
PERSTORP U.S. INC.
(subsidiary of Perstorp AB
[Sweeden] )
Florence, Massachusetts
PIONEER PLASTICS CORPORATION
Chemical Division
Auburn, Maine
X
X
X
X
X
X
X
Melamine
Formal
dehyde
X
Xa
X
-68-
-------
TABLE 7-1.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Continued)
COMPANY AND PLANT
LOCATION
PLASTICS ENGINEERING CO.
Sheboygan, Wisconsin
PLASTICS MANUFACTURING CO.
Dallas, Texas
POLYMER APPLICATIONS INC.
Tonawanda, New York
POLYREZ COMPANY, INC.
Woodbury, New Jersey
PPG INDUSTRIES INC.
Coatings and Resins Div.
Circleville, Ohio
Oak Creek, Wisconsin
RAYBESTOS-MANHATTAN, INC.
Stratford, Connecticut
REICHHOLD CHEMICALS, INC.
Andover, Massachusetts
Azusa, California
Carteret, New Jersey
Detroit, Michigan
Houston, Texas
Kansas City, Missouri
Malvern, Arkansas
Moncure, North Carolina
Niagara Falls, New York
South San Francisco, CA
Tacoma, Washington
Tuscaloosa, Alabama
White City, Oregon
RIEGEL TEXTILE CORPORATION
H.I.T. Chemicals Division
Ware Shoals, South Carolina
ROGERS CORPORATION
Manchester, Connecticut
Phenol-
Formal-
dehyde
X
X
X
X
X
X
X
X
X
X
X
X
RESIN TYPE
Urea-
Formal-
dehyde
X
X
X
X
X
X
X
X
X
X
X
X
X
Melamine-
Formal-
dehyde
X
X
X
X
X
X
X
-69-
-------
TABLE 7-1.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Continued)
Phenol-
Formal-
dehyde
X
X
X
COMPANY AND PLANT
LOCATION
SCHENECTADY CHEMICALS INC.
Oyster Creek, Texas
Rotterdam Junction, NY
Schenectady, New York
SCHER BROTHERS, INC.
Clifton, New Jersey
SCOTT PAPER COMPANY
Packaged Products Division
Chester, Pennsylvania
Everett, Washington
Fort Edward, New York
Marinette, Wisconsin
Mobile, Alabama
SHANCO PLASTICS & CHEMICALS INC.
Tonawanda, New York X
THE SHERWIN-WILLIAMS COMPANY
Chicago, Illinois
Cleveland, Ohio
Morrow, Georgia
Newark, New Jersey
RESIN TYPE
Urea-
Formal-
dehyde
SIMPSON TIMBER COMPANY
Arcata, California
Portland, Oregon
SOUTHEASTERN ADHESIVES COMPANY
Lenoir, North Carolina
SPAULDING FIBRE COMPANY, INC.
De Kalb, Illinois
Tonawanda, New York
SUN CHEMICAL CORPORATION
Chemicals Group
Chester, South Carolina
SYBRON CORPORATION
Jersey State Chemical Co., div
Haledon, New Jersey
X
X
X
X
X
X
X
X
X
X
X
X
X
Melamine-
Formal-
dehyde
X
X
X
-70-
-------
TABLE 7-1.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Continued)
Phenol-
Formal-
dehyde
COMPANY AND PLANT
LOCATION
SYNTHRON, INC.
Ashton, Rhode Island -
Morganton, North Carolina
THOMASON INDUSTRIES INC.
Southern Resin Division
Fayetteville, North Carolina
Thomasville, North Carolina
.TRW INC.
IRC Division
Dowington, Pennsylvania
UNION CAMP CORPORATION
Valdosta, Georgia X
UNION CARBIDE CORPORATION
Chemicals and Plastics Division
Bound Brook, New Jersey X
Elk Grove, California X
Marietta, Ohio X
Sacramento, California X
Texas City, Texas X
UNITED-ERIE, INC.
Erie, Pennsylvania X
UNITED MERCHANTS & MANUFACTURERS
Valchem-Chemical Division
Langley, South Carolina
U.S. OIL COMPANY
Southern U.S. Chemical Co., Inc. sub.
East Providence, Rhode Island
Rock Hill, South Carolina
UNIVAR CORPORATION
Pacific Resins & Chemicals, Inc.
Eugene, Oregon X
Newark, Ohio X
Portland, Oregon X
Richmond, California X
RESIN TYPE
Urea-
Formal-
dehyde
X
X
X
X
Melamine-
Formal-
dehyde
X
X
X
X
X
X
X
X
X
X
-71-
-------
TABLE 7-I.-PRODUCERS OF AMINO AND PHENOLIC RESINS (Concluded)
COMPANY AND PLANT
LOCATION
USM CORPORATION
Crown-Metro, Inc., sub.
Greenville, South Carolina
VALENTINE SUGARS, INC.
Valite Division
Lockport, Louisiana
WEST COAST ADHESIVES COMPANY
Portland, Oregon
Phenol-
Formal-
dehyde
X
X
WESTINGHOUSE ELECTRIC CORPORATION
Insulating Materials Division
Manor, Pennsylvania X
Micarta Division
Hampton, South Carolina X
WEST POINT-PEPPERELL, INC.
Griftex Chemical Co., sub
Opelika, Alabama
WEYERHAEUSER COMPANY
Longview, Washington
Marshfield, Wisconsin
X
X
RESIN TYPE
Urea-
Formal-
dehyde
Melamine-
Formal-
dehyde
X
X
X
a Plant to be owned by Libby Owens Ford
-72-
-------
U)
I
VAPOR
RETURN
REFLUX
CONDENSER
BUTANOL
STORAGE
(100%)
A V
^rC,
DECANTER
VAPOR
RETURN
TO PROCESS SEWER
OR ALCOHOL RECOVERY
FORMALDEHYDE SOLUTION
37? or 52$, @ 138°F
(IN BUTANOL FOR BUTYLATED)
XYLENE,
(SOLVENT)'
TO FLARE
* COULD MAKE M-F SYRUP,
M-F FILLED POWDER, OR
BUTYLATED M-F SYRUP AS
SHOWN
RESIN
IMPREGNATOR
(MIXER)
MOLDING POWDER PRODUCT
•TO FURTHER SIZE
PROCESSING & PACKAGING
RESIN SYRUP STORAGE
FEED REACT
Figure 7-1.- Melamine-formaldehyde resin - Batch process,
STM
RECOVERY/FINISH
-------
MF Manufacture
The first process described is a simple one that makes a
concentrated MF syrup widely used for decorative
laminates, surface coatings, or filled powder. The
following operating steps are followed:
1. Charge the reactor with 37% or 52% formaldehyde
aqueous solution, melamine crystals, and aqueous
sodium hydroxide.
2. Heat the mixture to the desired reaction temperature
with heating jacket steam, and reflux under vacuum at
reaction temperature (typically 175°F).
3. Monitor the reaction progress by sampling the reactor
contents for miscibility with water.
4. At the desired miscibility, cool the batch and
concentrate the syrup by evaporating water under a
vacuum. (This step may not be required, since 63% (wt)
solids syrup is made without concentration).
5. Adjust the pH (8.5-9.0) as required and pump out the
syrup through a filter to the holding tank.
At this point resin syrup can be stored or further
concentrated for use or for sale in varnishes, surface
coatings, adhesives, or textile treating or laminating
preparation or it can be further processed into a powder.
Procedures for making MF molding compounds are also
followed in UP molding compound manufacture (Section 20).
An unfilled powder can be made by spray drying aqueous
syrup and a filled powder can be made by impregnating a
solid filler with aqueous syrup. A batch process for
filled powder is described below:
1. Filler (such as kraft paper) is impregnated with resin
syrup and mixed to a wet paste in a mixer.
2. Water is removed in a tunnel dryer to form a dry
cake.
-74-
-------
3. The cake (popcorn) is pulverized to a coarse powder in
a micro-pulverizer.
4. This powder is milled in a ball mill with additives to
form a blended fine powder.
5. The fine powder is deaerated and compressed into a
corrugated ribbon, which is then cut into molding
granules for storage and sale.
7.2.1.1 Process variations.-
Additional ingredients that are used in recipe
variations include other monomers, pH control agents,
viscosity control agents, and catalysts.
Product formulations of MF resins are varied by adding
less expensive monomers, such as urea or phenol, to
produce a mixed polymer that has many of the desirable
features of MF resins. Up to 25% of the melamine
monomer in MF resins is replaced by other compounds that
react with formaldehyde. Compounds that form
aminoplasts, such as those containing amino groups are
preferred (e.g., urea and substituted ureas, carboxylic
acid amides, toluenesulfonamides, and other reactive
compounds). Other additives such as colors, fillers,
stabilizers, and lubricants are usually added at a later
stage of manufacture, a practice which avoids handling
and storing many grades of resin syrup and also avoids
contamination of the syrup reaction kettle with
additives that are not required.
The F/M mol ratio is usually about 2-3 for molding
compounds and about 3 for liquid casting resins. For
making syrups to be etherified as discussed belo.w,
-75-
-------
higher mol ratios are frequently used, for example, 3.3
for methylated resins, and 5.8 for butylated resins.
The initial product of the reaction is always a liquid
syrup, which can be sold in this form (with or without
concentration) or further processed and converted to a
dry powder, either filled or unfilled, for molding or
adhesive applications.
No information is available regarding the relative
importance of filled and unfilled powder manufacture
although it is believed that spray drying is favored by
process economics while filler impregnation (unfilled)
gives a more acceptable product.
7.2.1.2 Butylated MF manufacture.-
Butylated MF resins are hydrophobic, soluble in organic
solvents, and widely used in surface coatings such as
baking enamel.
Formaldehyde, butanol, melamine, and catalyst are all
charged together to the reactor at the beginning of each
batch.
The batch is heated to the atmospheric boiling point,
about 204°F. Methylolation of melamine and butylation
of me thylolme 1 amine take place more or less
simultaneously, along with some oligomer formation. The
vapors are condensed in the reflux condenser and the
subcooled condensate is separated into two layers in the
decanter. The upper layer (79.9% wt, butanol) is
returned to the reactor. The lower layer (7.7% wt,
butanol) is stored for butanol recovery, and the
-76-
-------
withdrawal of this stream removes water from the batch.
Some unreacted formaldehyde also leaves in this stream.
As the reaction proceeds the viscosity increases, and as
the water is removed the batch temperature rises to
about 230°F in 5 hours. Solids content reaches about
52-55% (wt).
When the reaction has proceeded to the desired point, a
sample is miscible with six volumes of mineral spirits.
The rest of the water, unreacted formaldehyde, and some
of the butanol are removed by vacuum distillation.
Pressure is reduced to 250 mm Hg or less and this vacuum
reduces the batch boiling temperature to about 190°F
slowing the reaction. Water and butanol are removed
until the viscosity increases to the desired value. The
batch is finished by diluting with xylene solvent,
stirring, and filtering the cool syrup as it is pumped
to a rundown tank for final tests and adjustments of
solids content. Storage tanks and drums are provided
for the product group.
7.2.2 VOC Emissions
All significant emission rates and sources for this
product are shown on Table 7-II. Figure 7-1 is the
schematic flowsheet for this product; it includes the
emission streams and their sources.
The only emission data available are presented here.
They are for a process making a butylated MF resin syrup
rather than for an MF resin syrup or powder. The equip-
ment and flowsheet for these products are quite similar
but the emission data presented for butylated MF may not
be representative of the basic MF resin industry. The
-77-
-------
TABLE 7-1I.- VOC EMISSIONS FROM BUTYLATED MELAMINE-FORMALDEHYDE
RESIN BY BATCH PROCESS
Current
Uncontrolled Practice Well Controlled
Stream #/1000# Resin #/1000#Resin #/1000# Resin
[1] Storage of Monomers,
Alcohol, Solvents 0.10 0.10 0.04
[2] Reactor 2.66 2.66 0.13
[3] Blend (Thinning) Tank 0.05 0.05 0.01
Totals 2.81 2.81 0.18
-78-
-------
process is related to that of MF somewhat in the nature of
a co-polymer of MF. In the butylated MF process, an ether
linkage (etherification) is brought about by reacting
butanol with the N-methylol groups (maximum of six) formed
when formaldehyde is reacted with melamine.
There are such considerable differences in emission
components that any attempt to relate MF process emissions
to butylated MF process emissions is of questionable
value. Also the absence of a dryer in the butylated
process is significant because it is a large potential
source of emissions. The dryer is present in MF
filled-powder manufacture (filled and unfilled powders
make up approximately 50% of the MF resin sold).
The major emission points of this process are:
[1] Liquid monomer (and comonomer) and solvent storage
tanks (fixed roof) - Causes of emissions are normal
breathing and filling. Formaldehyde tanks - 37% or
52% aqueous solution kept at 138°F by internal steam
coils. Emission streams contain air drawn in the tank
from atmosphere, formaldehyde and water vapor from
stored solution and small amounts of methanol vapor
(small percent of methanol allowed by formaldehyde
specification). Formaldehyde in butanol may be stored
for use in the butylated MF process.
Butanol and xylene (or similar organic solvent) tanks
will be present for the butylated MF process and will
emit these substances, respectively, along with air
drawn in from the atmosphere. Emission causes are
breathing and filling. All of the above storage
emissions are relatively small with butanol emissions
-79-
-------
the largest of the three and xylene and formaldehyde
next, in that order.
[2] Reactor overhead vacuum system - Largest VOC emitting
source in the plant. Actual flow rates vary because
process is batch. VOC components are butanol and
formaldehyde diluted with air (approximate composition
in wt% is - butanol, 55%; formaldehyde, 5%; air, 40%).
Emits through vacuum pump (or steam jet ejectors).
Steam is obviously also present if jet ejectors are
used.
[3] Blend tanks - Approximately 5% (wt) xylene solvent (or
other solvent used such as butanol) in air. Vents
from blend (rundown) tank, which discharges blend to
resin syrup storage tanks.
7.2.3 Applicable Control Systems
The following control technologies are recommended for the
emission streams described in Section 7.2.2 and in the
schematic flowsheet for this product. The same stream
numbering system is followed.
[1] Formaldehyde solution, butanol, and xylene storage
tanks - Utilize pressure-equalizing, vapor-return
lines to the tank cars or trucks to eliminate working
losses from storage tank filling (approximately 58% of
total potential storage emissions). Conservation
vents will also be required. Since they would
normally be installed for economic reasons, no
pollution control credit is given them.
-80-
-------
SECTION 8
NYLON 6 FIBER
8.1 INDUSTRY DESCRIPTION
8.1.1 General
Nylon is the common name given to any of a group of
commercially important synthetic linear polyamides of high
molecular weight. Polyamides are synthetic resins having
recurring amide groups in the polymer chain; these resins
may be formed into fibers, bristles, moldings, sheets, and
coatings. The U.S. International Trade Commission has
divided the class of polyamide fibers into two groups -
nylon fibers and aramid fibers based on the percentage of
amide linkages attached directly to two aromatic rings.
Nylons are identified by the number of carbon atoms in the
monomers used; hence nylon 6 is a homopolymer of a six
carbon compound - caprolactam. Nylon 66 indicates that
the polymer is made from two monomers, each having a
six-carbon chain. Nylon 66 was the first major fiber made
entirely of synthetic polymer. Nylon 66 and nylon 6
accounted for 98% of all domestic nylon fiber production
in 1976. Other commercial nylon fibers include nylon 610,
612, 11, 12 and Qiana nylon. Less commercially attractive
nylons include nylon 3, 5, and 8. Nylon 66 is discussed
more thoroughly in Section 9 of this report.
-81-
-------
today. Nylon also exhibits elastic properties; it will
return to its original length after stretching up to 8 %.
This characteristic is used advantageously in
manufacturing clothing with satisfactory dimensional
stability. Nylon is not attacked by insects, mildew, or
perspiration.
Differences between nylon 6 and nylon 66 are slight. The
principal difference between the two is that nylon 6 has a
lower softening and melting point. The minor property
differences between nylon 6 and nylon 66 give one or the
other the advantage in given applications, and they
compete in many applications (18) , (19 ) .
8.1.2 Nylon 6
The primary market for nylon 6 is in fibers with
applications in all major fiber markets, including
carpeting, hoisery, wearing apparel, and tire cord. There
is a much smaller market in thermoplastics applications.
High tenacity nylon 6 is used in industrial applications,
including fabrics, and for home furnishings.
Most domestic nylon 6 is manufactured by the "chip"
process in which fiber spinning is carried out as a
separate operation after remelting the "chips". Two
polymerization processes are of industrial importance -
hydrolytic or water-catalyzed polymerization and anionic
or base-catalyzed polymerization. The water-catalyzed
process is the overwhelming choice for fibers because it
is more suitable for large-scale operation and because it
is easier to control.
-82-
-------
General consensus in the industry is that nylon 6 develops
by a reaction mechanism involving opening the lactam ring
by heat, hydrolyzing by water, and chain growth by joining
the exposed functional groups by polycondensation (two
polymer chains react and combine) with elimination of
water and with polyaddition (a molecule of monomer adds on
to a polymer chain) . Special reagents in the reaction
mix, such as acetic acid or amines, serve to control chain
length. The polymerization is an equilibrium reaction
with approximately 10% water extractable at completion.
These are lower molecular weight compounds, including
monomer and oligomers.
About 70% of all nylon 6 polymer is produced by continuous
polymerization. The subsequent chip extrusion, extraction
(to remove the 10% water extractables remaining), and
drying operations are carried out normally on a continuous
basis regardless of whether continuous or batch polymeri-
zation is used. Emissions data per pound of nylon 6 chips
produced are believed to be very similar for both the
continuous and batch manufacturing processes. Future
plants are expected to have approximately the same 70/30%
split between continuous and batch processing.
Ten to twenty percent of nylon 6 production uses a method
known as "direct spinning" to make fibers. The hot melt
polymer is vacuum-stripped to remove unreacted monomers
and oligomers before it is sent directly to spinning.
Chip extrusion is eliminated.
8.1.3 Production Levels for Nylon and Aramid
In 1976, U.S. production of nylon and aramid fibers
amounted to 2,169 million pounds, a quantity equal to 27%
-83-
-------
of the total U.S. man-made fiber production. On a
poundage basis, nylon ranked second of the six most
important man-made fibers consumed domestically. Of the
total nylon and aramid fiber produced in 1976, nylon 66
fiber accounted for 1,360 million pounds (63%wt); nylon 6
accounted for 667 million pounds (31%wt); other types of
nylon accounted for 26 million pounds (l%wt); aramid
fibers accounted for 23 million pounds (l%wt); and all
types of nylon and aramid waste accounted for 93 million
pounds (4%wt).
Data concerning consumption of nylon 66 and nylon 6 by end
use are not available, but estimates in the percentage
split of major markets can be made from the amounts of
production capacity designated for various products. The
following table presents these estimated percentages for
1976:
ESTIMATED CONSUMPTION OF NYLON 66 AND NYLON 6 BY END USE
1976 (Percent)
Total Yarn and Staple
Total Yarn
Total Staple
Textile Yarn and Staple
Textile Yarn
Textile Staple
Carpet Yarn and Staple
Carpet Yarn
Carpet Staple
Industrial Yarn and Staple
Industrial Yarn
Industrial Staple
NYLON 66
67
70
61
79
78
100
60
60
60
76
78
45
NYLON 6
33
30
39
21
22
0
40
40
40
24
22
55
-84-
-------
Nylon 6 demand is projected to grow from 652 MM#/Yr in
1976 to 880 #MM/Yr in 1982, an average rate of 5.1%/Yr.
As of October 1977 there were eleven U.S. producers of
nylon 6 fiber (yarn, staple, and tow) with a total of
fourteen plants and total nylon 6 production capacity of
919 million pounds per year. (Nylon 6 capacity
represented 33% of total nylon capacity and nylon 66
accounts for 64%. Monofilaments and other nylons
accounting for the remainder, or approximately 3%. Three
of the eleven manufacturers, Allied, Akzona, and Dow
Badische, have 84% of the total spinning capacity.
The capacity data given in Table 8-1 refer to spinning
capacity, not polymerization capacity. Only five of the
manufacturers listed (Akzona, Allied, Dow Badische,
Firestone, and Rohm and Haas) have polymerization
capability. The others purchase merchant chip for their
spinning operations (18).
8.2 NYLON 6 MANUFACTURE BY THE CONTINUOUS CHIP PROCESS
8.2.1 Process Description
This process uses a tower or vertical tube reactor, strand
die pelletization, a continous countercurrent chip
extraction column, and a recirculating nitrogen drying
system. Figure 8-1 describes the process schematically.
Caprolactam monomer is stored with agitation and under a
nitrogen blanket at approximately 175°F. It is metered
continuously into the reactor along with catalyst (water),
the chain terminating agent (acetic acid), and additives
such as delusterants and antistatic agents. The reactants
flow down through the reactor at approximately 500°F
-85-
-------
TABLE 8-1.- NYLON 6 - YARN, STAPLE, AND TOW
PRODUCING COMPANY AND
I
00
ANNUAL CAPACITY AS OF OCTOBER 1977
(Millions of Pounds)
CONTINUOUS FILAMENT YARN STAPLE AND TOW
TEXTILE CARPET INDUSTRIAL TEXTILE CARPET INDUSTRIAL TOTAL
36
AKZONA INCORPORATED
American Enka Company,
division Central, SC
Enka, North Carolina X
Lowland, Tennessee X
ALLIED CHEMICAL CORP.
Fibers Division
Columbia, SC
Hopewell, Virginia
CAMAC CORPORATION
Bristol, Virginia 4
COURTAULDS NORTH AMERICA, INC.
(100% owned subsidiary of
Courtaulds, Limited (United
Kingdom)
Le Hoyne (Mobile), Alabama 5
DOW BADISCHE COMPANY
(jointly owned by Dow Chemical
U.S.A. and BASF AG [Federal
Republic of Germany))
Anderson, South Carolina 23
THE FIRESTONE TIRE & RUBBER CO.
Firestone Synthetic Fibers
Company, division
Hopewell, Virginia 0
GULFORD MILLS, INC.
Gainesville Division
Gainesville, Georgia 4
HANOVER MILLS, INC.
(100% owned subsidiary of Falk
Fibers & Fabrics, Inc.)
Yanceyville, North Carolina 4
ROHM AND HAAS CO.
Fibers Division
Fayetteville, NC 0
STAR FIBERS, INC.
(100% owned subsidiary of Star
Textile and Research, Inc. a
subsidiary of Dayco Corporation)
Edgefield, South Carolina 0
SUNBURST YARNS, INC.
(100% owned subsidiary of Tulex
Corporation)
Afton, Virginia 1
TOTAL 115
X
X
X
106
X
105
55
0
0
0
50
0
322
X
64
48
0
0
0
0
112
X
l8~5
0
X
8
55
0
0
0
0
25
000
0 358 12
I3T
. 309
10
135
48
4
4
50
25
1
919
-------
TO
FLARE
\2\
Q
. . REFLUX
V \ CONDENSER
y^N T^A WASTE WATER
(^— ( )•• 1 r»~i TO TREATMENT
I ^V ^
t VENTN
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VENT ^ CONDENSER
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TO 1 ACETIC ACID>-J
RECOVERY «-» „.„„„ ',
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VAPOR iv
RETURN r
1
00
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WH i c*n j — ^
ADDITIVES V-»
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1 1
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s.
REAC
(TUBE
^M
TOR
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W
DOWTHERM
-•H
\^~~-^
^~^T-^ UNDERWATER
CAPROLACTAM
MONOMER
STORAGE
f lAlfl SYSTEM* PELLETIZER
EXTRUDER
1
•QUENCH BATH
I
—
ET CHIPS f
•
H20
T
^-
jU
N2 COOLER
s—S
CHIP
EXTRACTION
COLUMN
re
.
*FOR DIRECT SPINNING USE BRINKS
NTRIFUGE
1
-J
n nvn
DEMISTER (WET FILTER) & FLARE
PRODUCT
*
I
WASTE WATER
TO TREATMENT
CHIP
DRYER
II U C1 * T C1 O
•i TO SPINNING
(CHIPS)
TO STORAGE
FEED REACT
RECOVERY
FINISH
Figure 8-1.- Nylon 6 - Continuous chip process.
-------
during a residence time of approximately 18 hours. Under
these conditions the polymer approaches equilibrium. The
molten polymer flowing out of the bottom of the reactor is
extruded, water quenched, and pelletized to a proper
physical form for extraction of residual monomer and
oligomer. The top of the reactor contains a boiling
polymerization reaction mixture. The reflux condenser
serves to return caprolactam and other vaporized reactants
to the reactor, while excess water taken overhead is
removed.
Oligomer and unreacted monomers are removed from the
chips, by continuous countercurrent extraction with water,
at approximately 200°F. The extraction process reduces
the content of oligmers plus monomers (mainly caprolactom)
from 10% to 3%, yielding a product with approximately 0.5%
residual monomer. The chips are centrifuged next, but
they still contain 10 to 12% internal moisture. The
moisture remaining in the chips is removed in a
continuous, circulating, hot-nitrogen dryer. The cool wet
nitrogen exhausted from the dryer is cooled further to
condense out the water, and then it is compressed,
reheated, and returned to the dryer. The dried nylon
chips are transferred to silo storage for subsequent sale
or remelt and spinning.
Several variations of the process described above exist
(20^) , (2±) . They use different types of reactors, chip
extraction equipment, and/or dryers. Examples of such
variations are:
o Using three, stirred-tank reactors in series (one
plant).
-88-
-------
o Using stirred tanks in series rather than
countercurrent extraction.
o Using vacuum drying instead of inert gas.
o Using a thin-film evaporator for monomer/ol igmer
removal when direct spinning is carried out.
8.2.2 VOC Emissions
All significant emission rates and sources for this
product are shown on Table 8-II. The schematic flowsheet
(Figure 8-1) for the product includes the emission streams
and their sources, and the same stream number is used for
a given stream throughout these discussions. Nylon 6 chip
dryer and storage have not been included because no VOC
emissions were reported from these sources. Emission
figures include both continuous and batch process
emissions - prorated according to the reported nylon 6
production poundage. The estimated U.S. production split
was 70% continuous and 30% batch. VOC emissions from the
two types of processes are believed to be nearly equal on
a per pound of nylon 6 produced basis.
The largest emissions from nylon 6 manufacturing plants
actually come from the fiber spinning facilities
downstream from the chip manufacturing facilities
described here. However, these spinning emissions are
outside the scope of this study. Conversely, this study
does include spinning emissions when evolved from "direct
spinning", where fibers are spun directly from the reactor
hot melt without a separate or intermediate chip-making
step. The estimates are that 10 to 20% of U.S. nylon 6
fibers are manufactured by "direct spinning".
A description of the emission streams follows:
-89-
-------
TABLE 8-1I.- VOC EMISSIONS FROM NYLON 6 MANUFACTURE BY THE CONTINUOUS
CHIP PROCESS
Current
Uncontrolled Practice Well Controlled
Stream f/lOOOft Resin #/1000#Resin #/1000# Resin
[1] Caprolactam Monomer
Storage 0.01 0.01 nil
[2] Polymerization
Reactor 0.02 0.01 nil
[3] Extrusion/Pelletizing 0.65 0.22 nil
Sections (includes
spinning if direct
spinning)
Totals 0.68 0.24 nil
-90-
-------
[1] Caprolactam monomer storage tanks - This stream emits
vapor with blanket nitrogen from the fixed roof tanks
or from cylinders storing molten caprolactam. Normal
breathing, filling, and withdrawing of monomer are the
emission causes. Caprolactam is kept molten by water
heated internal coils and agitators or mixers are
generally provided. Internal pressure in the tanks is
either atmospheric or slightly positive and a nitrogen
blanket is required. Storage temperature normally is
160 to 170°C. The same tanks can serve batch and
continuous processes, if both are present.
[2] Polymerization reactor - This stream emits caprolactam
vapor diluted by blanket nitrogen and traces of water
vapor which taken overhead from the polymerization
reactor. This reactor typically is a continuous UK
vertical tube vessel heated by Dowtherm in the
jackets. The stream normally passes through a reflux
condenser, a vapor condenser, and a K.O. drum, from
which it is emitted directly.
In the less common batch process case, the reactor
usually is an autoclave with an overhead condenser. A
vacuum is drawn during part of the reaction cycle and
part of the cycle proceeds as a closed system at
elevated pressures. The stream components are the
same as for continuous processing but in somewhat
different proportions.
[3] Extrusion/pelletizing sections - This stream is
potentially the largest VOC emission source from a
nylon 6 plant. Molten nylon 6 polymer from the bottom
of the reactor is extruded through a die to form heavy
-91-
-------
strands which are quenched in water, and pelletized.
Pellets are slurried with water for further
processing. Vapors are produced by the extrusion,
quenching, and pelletizing operations and normally are
collected by hoods. Steam or a water spray is
commonly added to the exhaust vapor stream to prevent
crystallization.
The stream is composed of caprolactam and water vapors
in a large volume of air. These operations are
usually continuous and this emission is essentially
unaffected by the type of upstream process (batch or
continuous). Additional caprolactam emissions are
generated by the direct spinning process and included
in this stream, but direct spinning is only used for
an estimated 10 to 20% of production.
8.2.3 Applicable Control Systems
The following control technologies are recommended for the
emission streams that are described in Section 8.2.2 and
shown on the schematic flowsheet.
[1] Caprolactam monomer storage tanks - This monomer
requires a nitrogen blanket on the storage tanks
regardless of VOC emission considerations. A pressure
equalizing vapor return line to the tank cars or
trucks should be used to eliminate working losses from
storage tank filling. This represents 58% of the
total potential storage losses or emissions. The
inert gas blanket system should exhaust tank vapors,
on pressure control, to a flare. A minimum reduction
of 90% in the remaining VOC emissions from breathing
is assumed for either case. Any tank or vessel
pressure relief valves utilized for either emission
-92-
-------
control or safety should also be tied into a flare.
[2] Polymerization reactor - Use a spray condenser to
wash emission stream and follow it by bubbling
through a seal pot. The result is an extremely low
concentration of caprolactam vapor in nitrogen.
Route the resulting stream to the flare. (If no
flare is available, atmospheric emission would be
acceptable because the condenser effectiveness is
high and the resulting VOC emission level is low).
[3] Extrusion/pelletizing sections - All non-direct
spinning continuous and batch processes should use
the newly demonstrated "underwater pel le t ization
system" to eliminate nearly all VOC fumes. This
system also has noise reduction and process economics
advantages. For direct spinning, hoods are to be
used to collect extrusion emissions and the take-off
exhaust from the spinning room air recirculation
system. Both should be sent to wet-filter demisters
then to flare.
-93-
-------
SECTION 9
NYLON 66 FIBER
9.1 INDUSTRY DESCRIPTION
Nylons (polyamides) are identified by the number of carbon
atoms in the monomers from which the particular product is
synthesized. Hence nylon 66 is a copolymer of the two
six-carbon compounds, adipic acid and hexamethylene
diamine. Together nylon 66 and nylon 6 accounted for 98%
of the domestic nylon fiber produced in 1976. The primary
market for nylon 66 is in fibers, with major applications
in carpeting, hoisery, wearing apparel, and tires. A much
smaller market exists in thermoplastics applications.
U.S. production of nylon 66 was 1375 MM Ibs in 1976. The
projected growth rate for U.S. consumption for 1976-1981
is 4.2% per year.
The significant domestic producers of nylon 66 are shown
on Table 9-1. Du Pont and Monsanto have 89% (wt) of the
total capacity of the six manufacturers listed (18).
9.2 BATCH OR CONTINUOUS POLYCONDENSATION OF NYLON 66
9.2.1 Process Description
The commercial process for manufacturing nylon 66 starts
with the production of a water solution of nylon salt
-94-
-------
TABLE 9-1.- NYLON 66 FIBERS - PRODUCERS
I
vo
PRODUCING COMPANY AND
PLANT LOCATION
CHEVRON CHEMICAL COMPANY
OF PUERTO RICO
(100% owned subsidiary of
Standard Oil of California)
Guayama, Puerto Rico
E.I. DU PONT DE NEMOURS &
COMPANY, INC.
Textile Fibers Department
Camden, South Carolina
Chatanooga, Tennessee
Martinsville, Virginia
Richmond, Virginia
Waynesboro, Virginia
FIBER INDUSTRIES, INC.
(62.5% owned by Celanese Corp.
and 37.5% owned by ICI, Ltd.
(United Kingdom)
Greenville, South Carolina
Shelby, North Carolina
KAYSER-ROTH CORPORATION
Yarn Processing Division
Creedmoor, North Carolina
NYLON 66 - YARN, STAPLE AND TOW
ANNUAL CAPACITY AS OF SEPTEMBER 1977
(Millions of Pounds)
CONTINUOUS FILAMENT YARN
Textile Carpet Industrial
MONSANTO
Monsanto Textiles Company
Decatur, Alabama
Greenwood, South Carolina
Pensacola, Florida
WELLMAN, INC.
Wellraan Industries, Ir.c. sub.,
Man-Made Fiber Division
Johnsonville, South Carolina
TOTAL
50
X
X
X
2AQ
10
X
X
94
21
X
344
X
X
To"
X
X
TT~O
~
X
115
STAPLE AND TOW
Textile Carpet Industrial
28
—0
X
X
16
X
X
210
X
X
~55
394
475
385
44
X
T7~5
40
480
Total
71
1,098
10
0
10
494
40
1,788
-------
(hexamethylenediammonium-adipate). The process described
is shown on Figure 9-1. The polymerization reaction takes
place in the following three stages:
o Evaporation of part of the water with some poly-
condensation.
o Polycondensation with removal of all but a small
quantity of water.
o Polycondensation to the desired degree and removal of
the residual quantity of water. Unlike the nylon 6
reaction, which is of the equilibrium type, this
reaction goes to completion.
The nylon 66 process described here can be entirely
continuous and make either chips, flakes, or pellets for
later spinning. Also it can be combined with direct
spinning to produce yarn, staple, or tow. The current
trend appears to be toward direct spinning. Continuous
nylon salt preparation may be integrated with batch
Polycondensation, in which case either chips, flakes, or
pellets must be made. The diagram depicts all of these
operations, but the process as built would have separate
trains or items of equipment and control for batch and
continuous operations (22) , (23 ) .
9.2.1.1 Nylon salt production.-
Adipic acid is dissolved in hot water at 40°C in a
jacketed, agitated vessel in a nitrogen atmosphere, and
HMD (hexamethylene-diamine) is dissolved in another.
The two solutions are brought together in a jacketed,
agitated reactor and nylon salt (hexamethylenediammonium
adipate) is formed. This aqueous solution of nylon salt
is transferred to a surge vessel and stored for later
use in the nylon 66 polycondensation reactor.
-96-
-------
0
H20<,
VAPOR
RETURN
I
vo
J f[2]
""• ~& SPRAY
CONDENSER
I CUTTEB
WASTE f~"\
TREATING ^
ATION / h^
/AIR rf
12]
_
WAS1
_ NYL(
TO
CATALYTIC
INCINERATOR
BLEND/DRYER
[2]j
FLAKES,OR PELLETS
OVERHEAD
CONDENSER
(HEAT RECOVERY
[3]
CONTINUOUS
FILAMENT
YARN
FIBER
•TOW
MELT(DIRECT)
SPINNING
FEED
REACT
REACT
RECOVERY
FINISH
Figure 9-1.- Nylon 66 by batch or continuous polycondensation.
-------
9.2.1.2 Nylon salt purification and concentration.-
The 48% nylon salt solution is concentrated in an
evaporator to a concentration of 65%. After passing
through a clarifier (typically a cartridge type) to
remove the trace of solid, it is ready for
polycondensation.
The evaporator can be run for either batch or continuous
operation, and generally it will be operated in the same
mode as the polycondensation reactor.
9.2.1.3 Polycondensation by a batch process.-
The operation typically requires a cycle of five hours
consisting of the following steps:
A. One and one-half hour charging and heating of the
65% nylon salt solution from the surge or day tank
to 230°C; at the same time, the pressure is built up
to 250 psig. Viscosity stabilizer is added.
B. One hour heating, up to 245°C, while the pressure is
maintained at 250 psig. During this time,
delusterant, stabilizer, and other ingredients are
added.
C. One and one-half hour heating with gradual release
of pressure from 250 to 0 psig at 270°C.
D. One-half hour heating at 270-275°C with pressure
still at 0 psig.
E. One-half hour discharging, with some nitrogen
pressure utilized to facilitate discharge.
-98-
-------
Two jacketed reactors, each provided with an agitator
and nitrogen blanketing are normally used (only one is
shown in the diagram).
9.2.1.4 Polycondensation by a continuous tank process.-
Although only one reactor is shown on the schematic, the
two stage polycondensation described here is more common
than single stage.
The nylon salt solution from the surge or day tank is
pressurized to 290 psig, preheated to 530°F, and charged
to a first-stage tank reactor, which is regulated at
530°F and 265 psig. Additives, prepared separately in
small vessels, are added under nitrogen pressure. In
the normally agitated first-stage reactor, the major
part of the water is evaporated and a part of the
adipate is polycondensed to a low degree. This material
is then pumped and sprayed into a second-stage reactor
together with a larger quantity of liquor re-circulated
from that reactor. A stream of hot nitrogen flows
countercurrent to the liquid spray and carries away the
water vapor in a manner preventing congelation of the
polyamide. Nylon 66 formed in this reactor, still
containing some water, is partially recirculated and the
remainder is conveyed to a finisher where the residual
water is removed and the molecular weight is increased
to the desired degree. The mass in the second-stage
reactor is viscous and requires agitation.
Typical additives used at this stage are acetic acid as
a viscosity stabilizer and titanium dioxide as a
delusterant.
-99-
-------
Other additives may include phenylphosphonate or
kaolinite as a nucleating agents, various substances
as stabilizing agents, and glycol as an anti-static
agent. The total amount of additives often comes to
about 2-3% (wt) of the nylon 66 polymerized. Some
additives may be added to the finished nylon 66 after
the polycondensation step, but viscosity stabilizer and
delusterant should be added only during the
polycondensation.
9.2.1.5 Formation of nylon 66 chips.-
Nylon 66 may be used in molten condition (direct
spinning process) for processing into fiber, or chips
may be formed and later remelted for spinning (chip-
remelt, spinning process). Where nylon 66 is produced
for plastic use, it must be made in a pellet form.
The process described here, with minor modifications,
can be used to produce either nylon 66 chips, flakes, or
cylindrical pellets. Molten nylon 66 from the finisher
is charged to a casting wheel (chilled with cold water),
and solidified and quenched by water sprays, then cooled
and dried with a flow of inert gas. The nylon ribbon
that forms is loosened from the wheel by a scraper and
fed to a cutter which reduces it to small chips or
flakes. These fall into the blend/dryer for further
drying and an inert gas purge is taken to the catalytic
incinerator. The chips or flakes go to storage for
shipment or later remelt spinning on site., Heat
treatment in the solid state increases the molecular
weight and melt viscosity for certain desired blends,
such as those for plastic resins.
-100-
-------
9.2.1.6 Fiber spinning.-
Fiber spinning is accomplished either directly from the
hot melt (direct spinning) or by first remelting chips
or pellets made previously and stored. Direct spinning
is only practiced in conjunction with continuous
polycondensation.
Nylon 66 and nylon 6 are quite similar in their melt
spinning and drawing capabilities. However, VOC
emissions from direct spinning is less for nylon 66 than
for nylon 6 manufacture because no residual monomer
remains in nylon 66 at this stage. The absence of
residual monomer in nylon 66 reduces fuming at the
spinneret. Minor handling differences result between
the two because of nylon 66's higher melting point and
lower thermal stability.
9.2.2 VOC Emissions
All significant emission rates and sources for this
product are shown on Table 9-II. The schematic
flowsheet, Figure 9-1, includes the emission streams and
their sources.
The plants studied employ a spectrum of technology
(improved over 40 years) and make a wide variety of
products such that exact defining of (emission) sources
and compositions is impossible and arriving at a
representative model is difficult. The differences in
common source emissions between batch and continuous
operations are minor in composition but significant in
amount.
-101-
-------
o
NJ
I
TABLE 9-II.- VOC EMISSIONS FROM NYLON 66 FIBER - BATCH OR CONTINUOUS PROCESS
Uncontrolled Current Practice Well Controlled
Stream t/1000t Resin #/1000# Resin #/1000# Resin
[1] Nylon salt preparation
Section 0.77 0.44 0.12
[2] Polycondensation Section 2.10 0.29 0.01
[3] Fiber Spinning Section 0.76 0.17 0.08
Totals 3.63 0.90 0.21
-------
It is possible that a significant portion of nylon 66
plant emissions also fall into the category of
particulates (primarily as aerosols). The extent of such
emissions and the affect of particulate controls and
regulations in reducing VOC emissions should be given
further consideration in a detailed study.
A description of the designated emission streams follows:
[1] Nylon salt preparation section - The significant VOC
emissions come from the evaporators which concentrate
the aqueous solution of nylon salt prepared and stored
upstream of the evaporators. Evaporation
(concentration) can be either batch or continuous. In
either case, the stream will be composed largely of
water vapor (99+% by wt) with small amounts of
hexamethylene diamine, ammonia, and C02 and with
traces of hexamethylene imine and cyclopentanone. The
temperature (before control) will typically be 212°F.
Monomer storage losses which could be included here
were reported to be negligible. Adipic acid is
supplied as a powdered crystalline solid and is
typically dissolved in water in a closed, N2
blanketed dissolver vessel. The hexamethylene diamine
storage tanks are inert gas blanketed and have vapor
displacement lines back to the shipping tank car.
[2] Polycondensation section - The polycondensation VOC
emissions are primarily those accompanying the water
vapor exhausted overhead from the polycondensation
reactors. They can be from either batch or continuous
operations. This is potentially the largest nylon 66
VOC emission source. Although the relative quantities
-103-
-------
will vary somewhat, the composition of the exhaust
stream is similar with either type of operation -
typically water vapor (99+% by wt water of solution
and of polymerization), hexamethylene diamine,
ammonia, and CC^1 and traces of volatile, water-
soluble, ingredient impurities (i.e. hexamethylene
imine, and cyclopentanone) . Temperature is 212°F or
somewhat above depending on the pressure used.
This stream also includes the exhaust from the
finisher and the blend/dryer. The finisher completes
the water removal by an inert gas purge and the
composition is largely nitrogen, typically 95+% (by
wt) , 4 to 5% by wt water vapor, and small amounts of
hexamethylene diamine and cyclo,pentanone_. The
blend/dryer (for chip or flake processing) exhaust has
a composition similar to that for the finisher (blend/
dryer data were commonly included in the fiber
spinning exhaust data received and appear to be
relatively small) .
[3] Fiber spinning section - This stream, the second
largest potential nylon 66 VOC emission source,
includes both emissions from direct (melt) spinning of
filament yarn and from the casting and blend-drying of
nylon 66 made into chips, flakes, or pellets. In the
latter case, the fiber spinning is done later in a
separate step when the chips are remelted. This step
could be done either at the same or at a separate
plant location, and the related VOC emissions for this
step are not included here. Direct spinning is only
used with continuous polymerization, but indirect
spinning via chips, flakes, or pellets can use either
batch or continuous polymerization.
-104-
-------
The VOC exhausted in direct spinning is composed,
primarily of small amounts of oil based finishes
(mineral/vegetable oils applied to the fiber in the
process to provide lubrication and static suppression) and
hexamethylene diamine in water vapor.
In the case where chips, flakes, or pellets are made, the
composition is small amounts of hexamethylene diamine and
cyclopentanone in water vapor and inert gas (air or
nitrogen).
9.2.3 Applicable Control Systems
The following control technologies are recommended for the
emission streams described in Section 9.2.2 and on the
schematic flowsheet for this product. The same stream
numbering system is followed here. VOC reduction
efficiencies given are based on calculated values from
reporting producers and on estimates.
[1] Nylon salt preparation section - Send overhead vapors
from the evaporator to a spray condenser using water
as a condensing medium. VOC reduction efficiency is
approximately 85%. (No credit was given for the
condensation occuring in the preheat exchanger, a unit
which would be justified on the basis of process
economics) . The HMD storage tank would have an inert
gas blanket system with vapor displacement back to the
tank car for unloading.
[2] Polycondensation section - Send overhead vapors from
the polycondensation reactor to a spray condenser
using water as a condensing medium. VOC reduction
efficiency is approximately 95%. (Typically heat
-105-
-------
recovery and condensation occur here which involve
preheat of the reactor feed stream).
No pollution control credit was given because of the
process economics justification. The remaining
non-condensibles from the spray condenser would be
sent to the catalytic incinerator. VOC reduction
efficiency is approximately 90% for this operation.
Pass the finisher exhaust through a vent condenser
(95% efficiency) and then to the catalytic incinerator
using platinum catalyst. 90% reduction efficiency is
assumed for the latter. The blend/dryer exhaust will
go to the catalytic incinerator, again with a
reduction efficiency of 90%.
[3] Fiber spinning section - Send this stream to a
catalytic oxidizer using a platinum catalyst. VOC
reduction efficiency is approximately 90%. (Demisters
often will be used for particulate or aerosol
control).
-106-
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SECTION 10
PHENOL-FORMALDEHYDE (PHENOLIC) RESINS
10.1 INDUSTRY DESCRIPTION
Phenol-formaldehyde or phenolic resins are condensation
products of phenol with formaldehyde. They are produced in
the largest quantities of any thermosetting resins and are
considered a work-horse of the plastics industry. They are
used primarily for plywood and fiberglass lamination, for
insulation, varnishes, industrial laminates, binders,
electrical devices and components, and for appliance
housings. They were the first synthetic thermosetting
polymer discovered and were trademarked early as "Bakelite"
in reference to the discoverer, Dr. Leo Baekland.
"Resols" and "novolacs" are the two main types of phenolic
resin made. ResolLs are most often made as an aqueous syrup
in a one step process. Another common "resol" form is
varnish, where the resin is dissolved in an alcohol or
other organic solvent. Novolacs are most commonly made in
the form of molding powders in a two step process.
Equipment for the two processes is similar through the
polymerization reaction.
Production of phenolic resins was 1660 MM Ibs for 1977.
The projected growth rate for U.S. consumption for the
period of 1977-1982 is 3.5 to 4.5% per year (24) ,(25) .
-107-
-------
Approximately 60 manufacturers are known to produce
phenolic resins in the U.S. These producers are shown in
Table 7-1, Melaraine-Formaldehyde Resins.
10.2 MANUFACTURE OF PHENOL-FORMALDEHYDE (PHENOLIC) RESINS
10.2.1 Process Description
The two processes described here are both simple batch
processes and together are believed to represent more than
75% of the total phenolic resin production in the U.S.
Figure 10-1 shows a schematic for both processes. The
resol process is considered a one-step process (the curing
is done by heat only, and there is no requirement for a
second addition of cross-linking reagent) The reaction
uses a base catalyst. It is used most often to make
either a concentrated aqueous syrup or a varnish (resin in
an organic alcohol solution). The novolac process
discussed in this section is considered a two-step process
(the curing is done by adding a curing agent that requires
a separate step) using an acidic catalyst, and it is used
normally to make a filled powder for compression molding
(iZ)' (!§_>' (M)-
A. One Step Process - Syrup or Varnish -
The following operating steps are carried out in this
batch process. One batch cycle normally takes up to 8
hours.
1. Charge liquid phenol, 37 or 50% aqueous
formaldehyde solution, and aqueous sodium hydroxide
catalyst to the reactor.
-108-
-------
TO INCINERATOR
O
vo
ORGANIC SOLVENTS
STORAGE (SEPARATE
TANKS AS SHOWN,
TYPICALLY FOR
HETHANOL, ETHANOL,
& BUTANOL)
RIBBON
BLENDER
•SYRUP, VARNISH, OR MOLDING POWDER
CAN BE MADE BY PROCESSES SHOWN
HOLDING POWDER
PACKAGING
PELLETIZER
FEED
REACT
RECOVERY/FINISH
Figure 1C-1.- Phenol-formaldehyde resr.n using one-step or two-step processes
-------
2. Heat the mixture to the desired reaction temperature
under agitation and allow it to reflux under vacuum.
Temperature is typically 140-210°F. Overheating
from the highly exothermic reaction is prevented by
utilization of internal cooling coils.
3. Monitor the reaction progress by sampling the
reactor contents for viscosity and/or gel time (set
up time).
4. Neutralize the mixture with an acid. Formic,
acetic, phosphoric, and sulfuric acids are commonly
used.
5. Concentrate the syrup by water evaporation under a
vacuum to the concentration desired.
6. Cool (this must be done quickly), filter, and store
as a concentrated syrup product (50% solids,
normally) . If the product is to be held for later
use, stabilizers often must be used to prevent
premature curing.
7. Alternately, if a varnish is to be made, complete
the dehydration step, add solvent (usually an
alcohol such as methanol) cool, filter, and store
the varnish product.
B. Two Step Process - Molding Powder-
The following operating steps are carried out in batch
operation.
1. Liquid phenol is charged to the reactor and heated.
Acidic catalyst (e.g., oxalic acid) and surfactant
are added.
2. When reaction temperature is reached (approximately
220°F) formaldehyde solution addition is begun and
continued over a period of several hours.
-110-
-------
2. Heat the mixture to the desired reaction temperature
under agitation and allow it to reflux under vacuum.
Temperature is typically 140-210°F. Overheating
from the highly exothermic reaction is prevented by
utilization of internal cooling coils.
3. Monitor the reaction progress by sampling the
reactor contents for viscosity and/or gel time (set
up time).
4. Neutralize the mixture with an acid. Formic,
acetic, phosphoric, and sulfuric acids are commonly
used.
5. Concentrate the syrup by water evaporation under a
vacuum to the concentration desired.
6. Cool (this must be done quickly), filter, and store
as a concentrated syrup product (50% solids,
normally) . If the product is to be held for later
use, stabilizers often must be used to prevent
premature curing.
7. Alternately, if a varnish is to be made, complete
the dehydration step, add solvent (usually an
alcohol such as methanol) cool, filter, and store
the varnish product.
B. Two Step Process - Molding Powder-
The following operating steps are carried out in batch
operation.
1. Liquid phenol is charged to the reactor and heated.
Acidic catalyst (e.g., oxalic acid) and surfactant
are added.
2. When reaction temperature is reached (approximately
220°F) formaldehyde solution addition is begun and
continued over a period of several hours.
•Ill-
-------
3. After formaldehyde addition is complete, the mixture
is allowed to react for an additional hour or two.
4. The temperature is increased to approximately 270°F
(at atmospheric pressure) to allow water and
unreacted phenol to distill off.
5. Application of a vacuum, a further temperature
increase to 320°F, and injection of live steam
strip residual volatiles from the melt.
6. The resin melt is fed to a chilled drum flaker. The
flake is then fed to a grinder and ground to a
powder.
7. The powder resin is blended with wood flour filler,
lubricants, curing agent, (e.g., hexamethylene
tetramine) and other additives in a ribbon blender.
8. The filled resin is pelletized and stored prior to
shipment or use.
10.2.2 VOC Emissions
All significant emission rates and sources for this
product are shown in Table 10-1. Figure 10-1, which is
the schematic flowsheet for this product, includes the
emission streams and their sources.
[1] Liquid monomer, solvent, and organic additive storage
tanks - Causes of emissions are normal breathing and
filling (fixed roof tanks).
Formaldehyde tanks - 37% or 50% aqueous solution is
kept at 120°F by internal steam coils. The emission
stream contains air drawn into the tank from
atmosphere, formaldehyde and water vapor from the
stored solution and a small amount of methanol vapor
-.112-
-------
TABLE 10-1.- VOC EMISSIONS FROM PHENOL-FORMALDEHYDE RESIN
MANUFACTURER
Current
Uncontrolled Practice Well Controlled
Stream #/1000# Resin #/1000#Resin #/1000# Resin
[1] Storage for Monomers,
Solvents, & Organic
Additives 0.14 0.14 0.01
[2] Polymerization Reactor 0.22 0.22 0.00+
[3] Product Storage and
Blending (Liquid) 0.24 0.24 0.01+
TOTALS 0.60 0.60 0.02+
-113-
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(small percent of methanol allowed by formaldehyde
specification).
Phenol tanks - Liquid phenol is maintained above the
108°F melting point by internal steam coils. The
emission stream contains air, drawn into the tank from
the atmosphere, and phenol vapor.
Tanks for organic solvents (typically methanol,
ethanol, and butanol), organic additives and/or
catalysts (aniline is a typical basic organic
catalyst) are at ambient conditions. Emission causes
for these, and for phenol, are the same as described
for formaldehyde breathing and filling. The exhaust
emitted will contain vapor of these substances, along
with air drawn into the tanks from atmosphere.
All of the above storage emissions are relatively
small separately but together they are in the range of
the other main streams in these plants. Although the
types and relative amounts of each solvent used will
vary, a typical ranking of emissions from these tanks
would show methanol as the largest emitter, followed
by ethanol, phenol and formaldehyde, all in the same
general range, and with aniline emissions considerably
smaller. With respect to weigh tank operations, a
small amount of VOC emissions are generated by
charging these tanks from the phenol and formaldehyde
storage tanks with the weighed charge fed directly
into the reactor. The substance charged is the only
VOC component of the exhaust stream in each case.
Explosive range considerations may require nitrogen
blanketing on some or all of the tanks venting to the
incinerator (organic solvents and formaldehyde).
-114-
-------
[2] Overhead emissions from polymerization reactor - This
stream is actually a composite of two reactor related
vents. The first vent exhausts from the overhead
(reflux) condenser during charging (phenol and
formaldehyde discharged with air and water vapor) and
during the atmospheric dehydration portion of the
cycle (phenol, formaldehyde, solvent such as methanol,
and water vapor discharged). The temperatures
typically are 35°C and 25°C, respectively.
The second vent exhausts downstream of the vacuum
equipment that is connected to the overhead condenser
during dehydration under vacuum and refluxing. The
composition is largely formaldehyde, air, and water
vapor with some phenol and other reaction products.
These streams together are of the same order of
magnitude as the total product storage emission
streams (the vacuum system vent stream VOC content is
several times the quantity of the atmospheric vent) .
The temperature of this stream is typically 25-35°C
(depending on cooling or treatment beyond the reflux
condenser). Emission rates and composition vary over
the complete batch cycle. The vacuum may sometimes be
provided by steam jets rather than a vacuum pump.
[3] Liquid resin syrup and varnish product and product
blend tanks - There are normal breathing and filling
losses. Tanks are normally fixed roof at ambient
temperatures although some resins or resin
intermediates are stored at elevated temperatures.
The emission stream normally -contains phenol,
formaldehyde, and vapor of the solvent used for that
resin (water or organics such as methanol, ethanol, or
-115-
-------
butanol). When combined these emissions are
potentially (uncontrolled) significant and as large or
larger than any other emission stream in these
plants.
10.2.3 Applicable Control Systems
The following control technologies are recommended for the
emission streams described in Section 10.2.2 and in the
schematic flowsheet for this product.
[1] Liquid monomer, solvent, and organic additive storage
tanks - For streams venting tanks other than phenol
(typically formaldehyde, and methanol, ethanol, and
butanol solvents and aniline as a basic catalyst) use
incineration. 95% reduction efficiency is assumed for
these streams. For phenol tanks - use a vent
condenser with discharge to atmosphere. Calculated
reduction efficiency is 87%. Sending this stream to
incinerator is not feasible because of coating of
ducts when phenol cools and freezes.
[2] Overhead emissions from polymerization reactor - The
atmospheric vent should be discharged directly to the
incinerator. (Reduction efficiency of 95% assumed for
this discharge). The stream exhausting during vacuum
portions of the batch cycle should be scrubbed in a
baffled, aqueous scrubber after the reflux condenser
but ahead of the vacuum pumps. The discharge from the
vacuum pumps should then be incinerated. (Where a
steam jet system is used, either in place of a vacuum
pump or in parallel for the high vacuum end of the
cycle, the same system would be employed except for
adding a barometric condenser after the final stage.
-116-
-------
The estimated efficiency of the aqueous scrubber is
90% and the incineration is assumed to be 95%
efficient.
[3] Liquid resin syrup and varnish product and product
blend tanks - Incinerate these streams. 95% reduction
efficiency is assumed.
-117-
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SECTION 11
POLYESTER FIBERS
11.1 INDUSTRY DESCRIPTION
Polyester fibers (P.P.) are defined as a manufactured fiber
in which at least 85% weight of the fiber polymer is an
ester of a dihydric alcohol and a substituted aromatic
carboxylic acid. In commercial practice essentially all
P.P. polymer is produced from ethylene glycol and either
dimethyl terephthalate (DMT) or terephthalic acid (TPA).
The fiber polymer is produced using the intermediate bis-
(2-hydroxyethyl)-terephthalate (BHET) monomer with either
of the two processes. DMT is the older and more entrenched
process making up about 77% of the existing capacity, but
the TPA process is now preferred and most new- construction
is built for it.
Polyester is the largest of the synthetic fibers. In 1978
polyester fiber production in the United States reached
3,800 million pounds and it continued to show significant
market strength through the first quarter of 1979, (2^).
Current polyester fiber capacity in the United States is
estimted at approximately 5050 million pounds divided
almost equally between continuous filament yarn, staple,
and tow. In 1976, capacity utilization for textile-grade
filament yarn at 62% (based on November 1976 capacity) was
particularly depressed, (21_) . However, low capacity growth
-118-
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(about 2% actual per year for 1977 and 1978) and good
markets have increased utilization to an estimated 80% for
1979. Sufficient capacity exists to satisfy anticipated
demand to 1980/1981. Projected demand until 1982 is
essentially equivalent to the planned capacity.
Polyester fiber polymer manufactured directly from TPA is
preferred since the recovery and purification of byproduct
methanol is avoided. However, much existing capacity is
based on DMT because polymerization grade TPA has only been
available since 1963. Table 11-1 lists the domestic
polyester fiber manufacturers. Of the 18 manufacturers
listed, four - DuPont, Fiber Industries (Celanese) , Eastman
Kodak, and American Hoechst - have approximately 80% of the
total capacity. Most fiber manufacturers purchase either
DMT or TPA as well as ethylene glycol. Only American
Hoechst, E.I. DuPont, and Eastman Kodak have captive raw
material producing facilities, and all three produce DMT,
not TPA.
P.P. polymer manufacture is dependent on aromatic feedstock
supplys because DMT and TPA produced in the United States
are derived from paraxylene.
The DMT process consists of the catalyzed exchange of
ethylene glycol groups for methyl alcohol to yield the
intermediate, BHET. The liberated methyl alcohol is removed
from the system by distillation in order to drive the
exchange to completion. Significant VOC emissions can occur
from methanol recovery.
The TPA process produces the intermediate BHET by the
reaction of ethylene glycol with TPA and, since there is no
byproduct methanol, VOC emissions are lower.
-119-
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TABLE 11-1.- POLYESTER YARN, STAPLE, AND TOW PRODUCING COMPANIES
to
o
I
PRODUCING COMPANY AND
PLANT LOCATION
AKZONA INCORPORATED
(owned 64.5% by Akzo N.V.
(The Netherlands) American
Enka Company, division
Central (Clerason), SC
Lowland, Tennessee
ALLIED CHEMICAL CORP.
Fibers Division
Columbia, South Carolina
Moncure, North Carolina
AMERICAN CYANAMIDE COMPANY
Fibers Division
IRC Fibers Co., subsidiary
Panesville, Ohio
AVTEX FIBERS INC.
Front Royal, Virginia
Lewistown, Pennsylvania
BEAUNIT CORPORATION
Elizabethton, Tennessee
DOW BADISCHE COMPANY
(jointly owned by Dow Chemical
U.S.A. and BASF AG)
Anderson, South Carolina
E.I. DU PONT DE NEMOURS & CO.,
Textile Fibers Department
Caraden, South Carolina
Cape Fear, North Carolina
Chattanooga, Tennessee
Cooper River, South Carolina
Kinston, North Carolina
Old Hickory, Tennessee
ANNUAL CAPACITY AS OF SEPTEMBER 1977
(Millions of Pounds)
CONTINUOUS
FILAMENT YARN STAPLE AND TOW
TOTAL
X
X
130
X
X
70
55
20
X
X
X
X
X
X
7F5
10
45
20
X
X
X
840
140
70
55
115
60
20
-------
TABLE 11-1.- POLYESTER YARN, STAPLE, AND TOW PRODUCING COMPANIES (continued)
NJ
M
I
PRODUCING COMPANY AND
PLANT LOCATION
EASTMAN KODAK COMPANY
Eastman Chemicals Division
Eastman Chemicals Products, Inc.
subsidiary, Carolina Eastman Co.
division
Columbia, South Carolina
Tennessee Eastman Co., division
Kingsport, Tennessee
FALK FIBERS & FABRICS INC.
Universal Polymer Products Co.
subsidiary
Fuquay-Varina, North Carolina
FIBER INDUSTRIES INC.
(owned 62.5% by Celanese Corp.
and 37.5% by Imperial Chemical
Industries Limited (UK)
Greenville, South Carolina
Palmetto (Darlington), SC
Salisbury, North Carolina
Shelby, North Carolina
THE FIRESTONE TIRE & RUBBER CO.
Firestone Synthetic Fiber Co., div
Hopewell, Virginia
THE GOODYEAR TIRE & RUBBER CO.
Chemical Division
Scottsboro, Alabama
CLARENCE L. MEYERS & CO.
Meyers Fibers, Inc.
Ansonville, North Carolina
MONSANTO COMPANY
Monsanto Textiles Company
Decatur; Alabama
Sand Mountain (Lake
Guntersville), Alabama
ANNUAL CAPACITY AS OF SEPTEMBER 1977
(Millions of Pounds)
CONTINUOUS
FILAMENT YARN STAPLE AND TOW
TOTAL
10
X
X
450
30
30
10
X
TTD"
X
405
520
10
X
X
X
705
1,155
30
30
10
240
-------
TABLE 11-1.- POLYESTER YARN, STAPLE, AND TOW PRODUCING COMPANIES (concluded)
PRODUCING COMPANY AND
PLANT LOCATION
PHILLIPS FIBERS CORP.
(owned 90% by Phillips Petroleum
Company and 10% by Phone-Poulenc
SA [France])
Rocky Mount; North Carolina
ROHM AND HAAS COMPANY
Rohm and Haas Carolina Inc., sub.
Fayetteville, North Carolina
TEXFI INDUSTRIES, INC.
Texfi Yarn and Fibers Group
Asheboro, North Carolina
New Bern, North Carolina
WELLMAN, INC.
Wellman Industries Inc., sub.
Man-Made Fiber Division
Johnsonville, South Carolina
TOTAL
ANNUAL CAPACITY AS OF SEPTEMBER 1977
(Millions of Pounds)
CONTINUOUS
FILAMENT YARN STAPLE AND TOW
50
140
X
X
40
2445
0
2295
TOTAL
50
140
45
40
4,740
-------
11.2 P.P. MANUFACTURE BY DIMETHYL TEREPHTHALATE PROCESS
11.2.1 Process Description
Polyester fiber is manufactured from DMT in either batch
or continuous processes. (Only a batch process is
described.) The three basic changes required between
batch and continous operations are; 1) Replacing the
kettle-reactor in batch operations for a column-type
reactor in the ester exchanger, 2) "No-back-mix" reactor
designs are required for continuous processes at the
polymerizer, and 3) Differing additives and catalysts
are required to make a product with proper molecular
weight, molecular weight distribution, etc. The batch
process described here is a two-reaction-step process
which begins with an ester exchange between ethylene
glycol and DMT. The products of this reaction are
methanol vapor (MeOH) and BHET monomer. The monomer is
polymerized to polyethylene terephthalate (PET) in a
second reaction step in the presence of heat, catalysts,
and vacuum. The major polymerization by-product is
ethylene glycol with smaller amounts of methanol. The
ethylene glycol and methanol are condensed and
transferred to storage tanks for reprocessing by others
(28_), (29,).
Fibers are produced from PET by spinning, either
directly from the polymer melt, or indirectly from
chips. Staple fiber is wetted, drawn, crimped, dried
with indirect heat, and may be cut before baling. Yarn
fiber may be dryed and heat set before it is tube wound„
Referring directly to Figure 11-1, Polyester fiber
manufacture by the DMT/TPA process, molten dimethyl
-123-
-------
TO SPENT
EG STORAGE
N2 & RECOVERY
POLYMERIZATION I
REACTORS I
FIBER
'PRODUCT
-$FROM EG SPRAY CONDENSER
ALTERNATIVE
CHIP
FORMING
TO EG RECOVERY
FEED ESTER REACT
POLY REACT .
FINISH
Figure 11-1.- Polyester fibers using DMT/TPA processes,
-------
terephthalate (DMT) and ethylene glycol (EG) are drawn
from storage tanks [1] and sent to the first step, or
ester exchange, reactor. The EG goes first to a small
mix tank where catalysts and additives are stirred in,
and then to the reactor. About 0.6 Ib EG and 1.0 Ib DMT
are used for each 1.0 Ib PET product. The ester
exchange reaction is conducted to start at 170 and end
at 230°C with atmospheric pressure, and the major
products are BHET monomer and methanol. Methanol has to
be removed from the reactor as a vapor to shift the
reaction to increase the formation of BHET. Methanol
vapor overhead (OHD) from the ester exchange reactor is
controlled by cooling water (CW) and refrigerated
condensers, and the vent stream [2] is the first major
process emission source. Condensed byproduct methanol
is sent to methanol storage for export to the DMT
supplier for reuse, and the tank vent for this methanol
storage tank is another major emission source, [5]„
Bottoms from the ester exchange reactor contain the
desired BHET intermediate or monomer. They are sent to
the second step, the polymerization reactors. In the
first polymerization reactor, the pressure is lowered to
the range of 1-760 mm Hg absolute and the temperature is
increased to 230-285°C to remove residual methanol and
the EG forming from BHET polymerization to PET. In the
second polymerization reactor, to further reduce
methanol and EG residuals, the pressure is lowered below
1 mm Hg, and the temperature is raised to 260-300°C. A
metallic catalyst is employed. The vapor streams from
the polymerization reactors are combined and controlled
by various systems designed to avoid plugging or fouling
from PET solids. These systems include EG spray
condensers or contactors and the vacuum systems shown in
-125-
-------
Figure 11-1. The vent from these vapor systems is the
third major process emission point, stream [3]. Systems
that use steam jet ejectors for vacuum produce VOC
contaminated contact waters, and they will have
substantially greater VOC emissions if these waters are
cooled with atmospheric cooling towers (atmospheric
contact) than if once-through f^O or mechanical
vacuum pumps (non-atmospheric contact) are used.
The two polymerization reactors are operated in series
with the (product) bottoms from the second reactor being
sent either to melt spinning or to a chip forming
machine for later spinning. Chip forming is not
discussed in this report. Oil base finishes are applied
to the filaments made in melt spinning to provide
lubrication and static suppression for fiber processing.
The bulk of the oil base (finish) is recovered and
recirculated. A small quantity is emitted through the
spinning machine vents and constitutes the fourth
emission stream, [4]. The oil exits the spinning
machine vents in the form of a "smoke".
11.2.2 VOC Emissions (DMT Process)
All significant emissions for this product are shown on
Table 11-11. The schematic flowsheet for this product,
which includes the emission streams and their sources,
is Figure 11-1. The same stream number is used for a
given stream throughout, but note that the DMT process
has streams [1] through [5] and TPA only has [1] through
[4]. The designated streams for the DMT process are:
[1] Raw and recovered materials storage tanks, except
recovered methanol (MEOH) - Fixed roof storage tanks
are used throughout in existing facilities.
-126-
-------
TABLE 11-11.- VOC EMISSIONS FROM POLYESTER FIBER MANUFACTURE BY DIMETHYL
TEREPHTHALATE PROCESS
Uncontrolled Current Practice Well Controlled
Stream #/1000» Resin #/1000# Resin #/1000# Resin
H
NJ
1
[1]
[2]
[3]
[4]
[5]
Raw and Recovered
Material Storage
Ester Exchange Reactor
Polymer izers*
(a) non-atmos contact
(b) atmos contact
Spinning Machines
MEOH Storage - DMT
Process Only
Subtotals*
(a) Non-atmos contact
(b) Atmos contact
0.15
0.04
3.65
3.83
0.29
4.31 ,
7.96
0.15
0.04
3.65
1.28
0.09
1.56
5.21
0.05
0.04
0.19
0.03
0.31
0.31
Weighted Total - DMT 6.07 3.32 0.31
51.8% (a) , 48 .2% (b)
*Emissions subtotals are given assuming polymerizer vents [3] are controlled by
(a) non-atmos contact condensers and (bj non-atmos contact + atmos contact
(cooling tower) condensers.
-------
Emissions are vapors of EG and DMT and result from
vapor displacement (working losses) and tank
breathing. The bulk of dimethyl terephthalate (a
solid at ambient conditions) is stored in hopper
bins until needed. Then it is melted at elevated
temperatures in heated, insulated tanks. Fresh and
spent ethylene glycol are stored at ambient
conditions. Recovered methanol (MEOH) storage is
treated as emission stream [5].
[2] The ester exchange reactor - This stream is one of
the larger potential emission sources in this
process. The flow rate and stream composition vary
as the batch goes through its cycle. The stream
carries methanol byproduct vapors primarily and
steam, and it is processed through both cooling
water and refrigerated condensers.
[3] The polymerization reactors - This stream carries
large quantities of steam and ethylene glycol
vapors, small amounts of MEOH vapors, volatile feed
impurities, and inert gas. Inert gas is added to
the reactor to strip ethylene glycol vapors,
residual volatiles, and steam from the polymer and
prevent product discoloration from oxygen
contamination. The resulting emissions pass through
a system that includes glycol and water contact
condensers (spray). There are two types of contact
condensers; (a) non-atmospheric contact or
once-through, and (b) atmospheric-contact. Although
type (a) produces a flow of contaminated water, it
has low VOC emissions compared to type (b) . Type
(b) systems use a cooling tower to cool the
contaminated water for reuse in the spray condenser,
and the cooling tower itself becomes a large
potential VOC emission source.
-128-
-------
[4] The spinning machines - A fume or smoke of oil and
moisture is emitted from various vents. Usual
controls include catalytic incinerators and mist
eliminators.
[5] Recovered methanol storage tank ventilation (DMT
process only) - This stream is large due to the
volatility of MEOH, and refrigerated condensers are
used to control it.
VOC emissions from the DMT process can be summarized as
follows:
o Polymerizer vent gas treatment exhaust, stream [3],
is a potentially large emission source, depending on
the following process variation. Spray condenser
bottoms, largely warm contaminated water, can be
handled in either of two ways - Type (a) process,
once through or recycle without atmospheric contact
and - Type (b), recycle through a cooling tower with
atmospheric contact. Type (a) emissions are
estimated to be 0.044 lb/1000 whereas Type (b) are
estimated to be 3.65 lb/1000.
o Spinning machine vents, stream [4] are another large
emissions source, and they are the largest for the
Type (a) variation, second largest for Type (b).
Current practice puts stream [4] at 1.28 lb/1000.
Thus the total emissions of a non-contact plant
[type (a)], with current practice, are estimated to
be 1.56 lb/1000 and those for a contact plant [Type
(b)] are 5.21 lb/1000. Table 11-11 summarizes the
emissions for polyester fibers manufacture by the
DMT process.
-129-
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11.2.3 Applicable Controls (DMT Process)
(Section 11.2.3 has been combined with 11.3.3 that
follows since the controls are the same for both
processes.)
11.3 P.P. MANUFACTURE BY TEREPHTHALIC ACID (TPA) PROCESS
11.3.1 Process Description (TPA)
Polyester fiber is manufactured from TPA in either batch
or continous processes, but only a batch process is
described. The process is a two-step process exactly
analogous to the DMT process described in Section 11.2.
The products of the first, or esterification, reactor
are t^O vapor and BHET. BHET is polymerized in the
second step reactors just as in the DMT process. The
absence of MEOH vapor as a first step byproduct
eliminates the need for the byproduct, MEOH, storage
tank, vent [5], and the VOC in major emission stream
[2]. For the purposes of this study, these are the only
significant differences between the two processes.
Figure 11-1, therefore, represents the process flow for
the TPA process provided the MEOH storage tank and
emission stream [5] are deleted. Of course process
conditions for TPA differ from DMT, but the objectives
are the same - short reaction time, low polymer ether
linkage content, good polymer color and thermal
stability.
11.3.2 VOC Emissions (TPA Process)
The emission streams for this process correspond to
those for the DMT process except that there are no
byproduct methanol emissions. Again, Figure 11-1 can be
-130-
-------
used minus stream [5] and the MEOH storage tank. Table
ll-III summarizes the emission rates and sources for the
TPA process. The major streams are:
[1] Raw and recovered materials storage tank - Fixed
roof storage tanks and bins are used throughout the
process and they have conservation vents on the
tanks. The emisssions are vapors of EG, TPA and TPA
dust; and they result from working (vapor
displacement) and breathing losses. Terephthalic
acid is stored in bins at ambient conditions until
needed, and then it is melted and stored in
insulated tanks at elevated temperatures until
i
charged. There are no emissions.
[2] Esterification reactor - This stream consists
primarily of steam and EG vapors, with small amounts
of feed impurities and volatile side products. For
economic reasons (EG recovery) it is controlled with
condensers, and exits at about 220°F.
[3] Polymerization reactors - Like stream [2] , this
stream consists of steam and EG vapors with small
amounts of volatile impurities. It is well
controlled by CW condensers exiting at about 120°F.
[4] Melt spinning - A fume or smoke of oil and water
droplets is emitted from various vents. This is the
largest single source of hydrocarbon emissions from
PET manufacture by TPA. Usual controls include
catalytic incinerators and mist eliminators.
The polyester fibers by TPA process is relatively
non-polluting because it does not produce byproduct
methanol with attendant recovery and storage emissions.
Like the Type (a) variation of the DMT process, spinning
machine vents, Stream [4], are the largest single
emissions source at 1.28 lb/1000 (current practice).
-131-
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TABLE ll-III.- VOC EMISSIONS FROM POLYESTER FIBER MANUFACTURE BY TEREPHTHALIC
ACID PROCESS
Stream
Uncontrolled Current Practice Well Controlled
#/1000# Resin #/1000# Resin #/1000# Resin
[1]
[2]
[3]
[4]
Raw and Recovered
Material Storage
Ester Exchange Reactor
Polymerizers
Spinning Machines
Nil
0.039
0.042
3.83
Nil
0.039
0.042
1.28
Nil
0.039
0.042
0.191
Totals
3.91
1.36
0.27
-------
Total emissions are estimated to be 1.36 lb/1000 with
current practice. Table ll-III summarizes emissions for
polyester fiber manufacture by the TPA process.
11.3.3 Applicable Control Systems (DMT and TPA Processes) (See
paragraph 11.2.3)
Because the DMT and TPA processes are similar, differing
only in that DMT produces byproduct methanol and has a
control option with atmospheric contacting of
contaminated cooling water, and TPA produces byproduct
water and does not have such an option, the control
systems for the two are discussed together. The
following controls are recommended for the streams
described in Sections 11.2.2 and 11.3.2 and shown on
Figure 11-1. The same stream numbering system is used
throughout.
[1] Emissions from fresh and recovered materials storage
tanks - Fixed roof tanks are satisfactory for
ethylene glycol since its vapor pressure is low.
Other tanks with more volatile or hazardo.us vapors
should use vapor return lines to loading tank trucks
or cars, thereby eliminating working losses or
approximately 58% of total (working plus breathing)
tank emissions. Conservation vents should be used
on all tanks not equipped with more sophisticated
vent control and they are almost always economically
justified. Inert gas blanketing and
flare/incinerator systems may be required for some
storage tanks, or CW or refrigerated condensers.
Water scrubbers may be applicable on DMT and TPA
tank vents primarily for housekeeping purposes. DMT
and TPA are crystaline solids at ambient conditions
-133-
-------
and can cause sublimed solids buildup on cool
surfaces adjacent to tank vents. High VOC removal
efficiencies have been reported when scrubbing
phthalic anhydride (12^) , (13); a material physically
similar to DMT. No control efficiency was assumed.
[2] Emissions from the ester exchange or esterification
reactors -
o DMT process - With the DMT process, byproduct
methanol vapor must be removed to enhance the
reaction and recovered for economic reasons; the
reactor vent is a major process emission source.
Presently economic controls include a C.W.
condenser and provision for refluxing part of the
MeOH for continuous or column-type reactors.
BDCT will include a refrigerated condenser on the
K.O. drum vent. 90% reduction of MeOH vapors was
assumed.
o TPA Process - With the TPA process the main
byproduct is H20 vapor, not MeOH; however,
ethylene glycol vapors and volatile feed impuri-
ties and side products are all present and the
ethylene glycol must be recovered. Present con-
trols are C.W. condensers with the exit vent
temperature about 220°F.
[3] For the polymerization reactors -
o DMT process - The polymerization of BHET is
conducted under vacuum to remove EG vapors and
shift the reaction toward completion.
Temperatures are high (520-560°F) and an N2
inert gas blanket is used in all equipment
-134-
-------
downstream of the polymerization reactor feed
tank (not shown in Figure 11-1) . For the
continous process a pre-polymerization reactor
proceeds polymerization. The major emission
point [3] is the vacuum system discharge (at
least two separate vents for the continuous
version) . Cooling water condenser controls are
used for EG recovery for economic reasons and the
exit temperature is about 100°F. Polymer solids
content of the vapor streams is high enough to
foul surfaces and plug jet nozzles so some type
of prevention is commonly practiced. One method
sprays hot EG vapors into the vacuum lines to
reduce deposition. The scheme shown in Figure
11-1 shows spray contact condensing the vapors
with cold EG liquid to avoid solids clogging the
vacuum system nozzles. The contactor bottoms are
saponfied before EG purification. The well-
controlled value assumes discontinuance of
atmospheric-contact, cooling water.
o TPA process - Essentially the same as for the DMT
process.
[4] Melt spinning - DMT and TPA processes - Spinning
lubricant and water vapor are emitted as an aerosol
or smoke from various spinning vents. This stream,
[4], is the major emission source for these plants.
Common controls include mist eliminators and
catalytic incinerators, and expected efficiencies
-135-
-------
are 70 and 80%, respectively. Improved control can
be obtained by controlling a higher percentage of
the total number of spinning machines and by using
more efficient control devices such as electrostatic
precipitators. An overall (from uncontrolled)
control efficiency of 95% was assumed.
[5] MeOH storage - DMT process only - Byproduct methanol
is produced from the DMT process only. Controls
include a refrigerated condenser system. An overall
efficiency of 90% was assumed.
-136-
-------
SECTION 12
HIGH DENSITY POLYETHYLENE
12.1 INDUSTRY DESCRIPTION
High-density polyethylene (HOPE) resins are linear
thermoplastic polymers of ethylene with densities higher
than 0.94 g/cm^.
HOPE resins are typically produced by low-pressure
processes operated at 100-1500 psi. In these processes,
generally, organic solvents are used and the ethylene is
dissolved in them; the solid catalyst is in suspension; and
the polymer forms a slurry (e.g., the processes originated
by Phillips Petroleum Company, and Solvay & Cie, sa) .
Amoco Chemicals Corporation and Union Carbide Corporation,
however, have new gas-phase processes that do not require
solvents. The solvent processes have higher potential VOC
emissions than the new gas-phase processes.
Although there are various solvent processes used, the
variations do not affect emissions except with respect to
the solvent recovery methods used.
The 1978 U.S. production of HOPE was 4200 MM PPY and
capacity was 5300 MM PPY (2:) , (50) . These figures
represent increases of 15% and 21% respectively over 1977.
Overall utilization of capacity was 79% in 1978 and
increasing, but resin supply is expected to be adequate
through 1983.
-137-
-------
Capacity in 1979 is estimated to be 5480 MM PPY (jj) , (51)
and utilization, K, will rise to 0.83 if 8% growth (50)
is assumed from 1978 to 1979.
There are eleven U.S. producers of HDPE and the market is
not particularly dominated by any one or a few. Table
12-1 lists the U.S. manufacturers of HDPE and gives their
location and capacity (52).
Current over-capacity for ethylene (greater than 30% )
ensures adequate raw material supplies to HDPE
manufacturers since ethylene makes up over 97% of HDPE
resin production. Typically, about 1.05 Ib ethylene are
required to produce 1 Ib of HDPE resins, and about 40% of
all production is homopolymer. The remaining 60%
copolymer resin is usually greater than 95% ethylene and
has less than 5% of such comonomers as 1-butene and
propylene.
Classically HDPE has been made using low-pressure
technology, (500-1500 psig) and LDPE has been using high
pressure. New low pressure technology using Zeigler
catalysts can produce LDPE also, and so, not only does
the classic pressure distinction not exit, but also some
equipment can be used for both of the major resin types.
For example, 38% of the 855 MM PPY (1978) Phillips
Petroleum Company capacity at Pasadena, Texas, can swing
between HDPE and LDPE (see Table 12-1).
12.2 HDPE MANUFACTURE BY LIQUID PHASE PROCESSES
12.2.1 Process Description (Liquid Phase Processes.)
Various solution, suspension or "diluent" liquid-phase
HDPE processes have been produced commercially (j^3_,j>4_) ,
-138-
-------
TABLE 12-1.- U.S. MANUFACTURERS OF HOPE RESINS AND THEIR LOCATIONS
AND CAPACITYS (52)
ANNUAL CAPACITY
AS OF OCTOBER 78
U)
UD
I
COMPANY AND PLANT LOCATION
ALLIED CHEMICAL CORPORATION
Specialty Chemicals Division
Baton Rouge, Louisiana
ATLANTIC RICHFIELD COMPANY
ARCO/Polymers, Inc., subsidiary
Port Arthur, Texas
CHEMPLEX COMPANY
(jointly owned by American Can Company
and Getty Oil Company)
Clinton, Iowa
CITIES SERVICE COMPANY
Chemicals Group
Columbian Chemicals, division
Texas City, Texas
DOW CHEMICAL U.S.A.
Freeport, Texas
Plaquemine, Louisiana
E.I. DU PONT DE NEMOURS & COMPANY, INC.
Plastic Products and Resins Department
Orange, Texas
Victoria, Texas
GULF OIL CORPORATION
Gulf Oil Chemicals Company
Plastics Division
Orange, Texas
THOUSANDS OF
METRIC TONS
272
68
86
82
136
125
104
102
200
MILLIONS
OF POUNDS
600
150
190
180
300
275
230
225
440
PROCESS
Phillips, Ziegler
Ziegler, Koppers
Phillips
Ziegler
Own
Own
Phillips,
Union Carbide
-------
TABLE 12-1.- U.S. MANUFACTURERS OP HOPE RESINS AND THEIR LOCATIONS
AND CAPACITYS (Continued)
ANNUAL CAPACITY
AS OF OCTOBER 78
THOUSANDS OF MILLIONS
COMPANY AND PLANT LOCATION METRIC TONS OF POUNDS PROCESS
HERCULES INCORPORATED
Polymers Department
Lake Charles, Louisiana 7 15
NATIONAL PETRO CHEMICALS CORPORATION
(jointly owned by National Distillers and
Chemical Corporation and Owens-Illinois, Inc)
La Porte, Texas 227 500 Phillips, Solvay,
US I
PHILLIPS PETROLEUM COMPANY
Plastics Division
Pasadena, Texas 388 855 Own
SOLTEK POLYMER CORPORATION
Deer Park, Texas 270 595 Phillips, Solvay
STANDARD OIL CORPORATION (INDIANA)
Amoco Chemicals Corporation, subisidiary
Chocolate Bayou, Texas 159 350 Own, Solvay, USI
UNION CARBIDE CORPORATION
Chemicals and Plastics, division
Seadrift, Texas 181 400 Own
TOTAL 2,406 5,305
-------
including Phillips' original solution and also their
particle-form processes, Solvay1s hexane slurry, and
various proprietary systems like those of Dow Chemical.
Conventional Zeigler catalysts require recovery systems
and, therefore, have higher potential VOC emissions. The
high-efficiency Ziegler catalysts and supported metal
oxide catalysts such as those used in UCC's liquid-phase,
Phillips-particle-form process do not require recovery,
so they have lower potential VOC emissions. The process
shown here (diluent) could be either solution or
suspension and is assumed to be of the high-efficiency
catalyst type that does not require catalyst recovery.
The Phillips particle-form process serves as the basis
for this description but it is intended to represent all
other liquid phase processes with high-efficiency
catalysts.
Referring to the schematic for this process, Figure 12-1,
the "Feed" section also depicts catalyst preparation.
Silica gel is impregnated with chromium; then it is
dried, dehydrated and activated. Thus prepared, catalyst
is fed to the reactor by being slurried in a stream of
process solvent (pentane) . Ethylene monomer and a
suitable comonomer (butene-1) are also fed to the reactor
where polymerization takes place in pentane. There are
diluent VOC emissions from both storage [1] and catalyst
preparation [2].
Product polyethylene is recovered, see "Recovery"
section - Figure 12-1, by flashing from a low pressure
(500 psig) to a vacuum and by steam stripping, [3]. Heat
-141-
-------
to
I
[3] FROM DILUENT RECOVERY,
VENTS, PURGE GASES, WAX
FLARE/
INCINERATOR ,
SYSTEMS [5]
FRESH
FEED
FRESH
AIRV
^ "I
A
X]—«"-TO SAFETY FLARE
FRESH
FEED REACT RECOVERY
Figure 12-1.- HDPE~ by "liquid-phase (diluent) processes.
FINISH
-------
is supplied by circulating pentane vapor through a
heater and mixing hot vapor with reactor effluent and by
steam. The diluent purification and recovery system is
not shown. The main streams leaving the flash drum and
stripper are taken to this system from which both a
light ends bleed, [3]/ and bottoms (wax) purge, [3], are
made. Finally polymer solids are blended with
antioxidant (A.O.) and pelletized in an
extruder-pelletizer. Conditions in the steam strippers
leave the polymer solids wet so that they must be
dewatered by rolls or centrifuges and dried, [4], prior
to extrusion. Phillips particle-form solids require
solvent drying (sections shown in dotted box) and this
produces associated potential VOC emissions.
An ethylene safety flare is always a part of each system
and some plants may use it for VOC emissions control. A
special flare or incineration system may also be
provided especially for the diluent recovery light ends
bleed [3] . A wax incinerator (low molecular weight
polymer) is also provided sometimes and may only be 9 5%
efficient for VOC removal. Thus the wax incinerator
vent, [5], may have a VOC emission.
12.2.2 VOC Emissions (Liquid Phase Processes)
All significant emissions for liquid-phase HOPE are shown
in Figure 12-1 and listed in Table 12-11 using bracketed
numbers to indicate the emission streams (8_) , (55) .
The major emission points of this process are:
[1] and [2] Diluent and comonomer storage and catalyst
makeup - Diluents are usually stored in fixed roof
-143-
-------
TABLE 12-11.- VOC EMISSIONS FROM HOPE MANUFACTURED BY SOLVENT PROCESSES
Uncontrolled Current Practice Well Controlled Composition
Stream #/1000g Resin »/1000» Resin fl/lOOOt Resin Vol %
[1] Diluent and Comonomer
Storage 0.20 0.20 0 15 - 70% VOC
[2] Cat Makeup 0.01 0.01 0 90% VOC
[3] Product Recovery Flash
Drum Purge, Including
Strip Decanter &
Centrifuge 23 0.50 0.2 Approx. 50% VOC
£ [4] Polymer Drier 8 8 0.4 0-5% VOC
£>
I [5] Wax Incinerator 0.40 0.04 0.04 0.2% VOC
[6] Fugitive 1.53 1.53 1.53
TOTAL 33.14 10.28 2.17
-------
tanks with conservation vents. Some diluent is also
used in catalyst preparation and addition. Emissions
are from tank breathing and working losses and from
catalyst slurrying.
[3] Product recovery - (Flash drum purge, stripper-
decanter, and dewater rolls or centrifuge) - From the
reactor, polymer and associated gas are blown down
into the flash drum. Vapors from the drum [3] are
sent to distillation (diluent recovery) from which a
light ends bleed is sent to flare or incineration to
purge impurities and ethylene. From the drum,
polymer with absorbed and adsorbed diluent is sent to
the steam stripper for diluent recovery. Steam
stripped diluent is condensed and decanted for
separation into water-rich and diluent-rich streams.
The decanter vapors [3] are flared or burned in a
boiler or incinerator. VOC are emitted from the
diluent-recovery, distillation, overhead purge and
from the stripper-decanter vapors and are sent to
flare or to incineration.
[4] Pellet Dryer/Stripper - Pellet dryers are usually
required for systems that steam strip polyethylene
fluff or powder. Dryers remove residual diluent from
the polymer and emit it to the atmosphere and are the
major emission point for the process. Some systems
produce pellets from a melt and thus do not have
water-wet pellets to dry. These systems produce
pellets with entrained or dissolved diluent that must
be steam-stripped. The amount of VOC emitted from
drying or pellet stripping depends on the residuals
from the polymers in the preceeding processes. It
varies widely.
-145-
-------
[5] Flare/Incinerator Systems - One or more flares will
be in use at most HOPE plants. Some manufacturers
use new or existing boilers to recover fuel values as
well as dispose of certain VOC containing streams.
Figure 12-1 is meant to show both flare and
incinerator systems vents as indicated by stream [5].
A low molecular weight wax is removed from still
bottoms in diluent recovery, and it too is
incinerated, usually in a special incinerator.
Emissions are usually small because flares and
incinerators can achieve high emissions reductions.
[6] Fugitive - This includes leaks, samples and equipment
entry losses mostly from feed, reactor, and diluent
recovery sections.
12.2.3 Applicable Control Systems (Liquid Phase Processes)
The following controls are recommended for the streams
described in Section 12.2.2 and shown in Figure 12-1 and
Table 12-11. The same numbering system has been used.
[1] and [2] Diluent and comonomer storage and catalyst
preparation - Most present-day diluent and some
comonomer storage is fixed-roof tankage and may or
may not have an N2~pad to flare. Catalyst
preparation VOC losses are from tankage and from
activation- solution drying, but they are minimal.
Future tankage will be floating roof and/or inert-pad
or condenser protected. Control was assumed 100%.
[3] Product recovery including flash drum purge,
stripper-decanter vapors, and dewatering rolls or
centrifuge ventilation - Flash drum and
stripper-decanter vapors bleeds or purges are
controlled effectively now by flare or boiler
-146-
-------
incineration. As the cost of energy and solvents
rises, more attempts will be made to recover these
materials before flaring. Improved control will
result both from VOC recovery before flaring and from
increased use of flaring for those not presently
practicing it. Sixty percent control efficiency has
been demonstrated.
[4] Pellet drying/stripping - Dryer/stripper exhaust
conditions vary widely and essentially are
uncontrolled at present. Boiler or other incineration
is recommended but adsorption/recovery may also be
feasible especially for those processes using N2
gas dryers and/or practicing dryer recycle. An
efficiency level of 95% was assumed.
[5] Flaring and incineration. Well controlled flares,
incinerators, and boilers can achieve greater than 99%
reduction of the VOC in the inlet. Wax incinerators
were assumed to be 95% efficient for both VOC and wax.
Wider use of flares and incinerators at existing
plants could greatly reduce all HOPE VOC emissions
except for drying. Control efficiency of 95% has been
demonstrated.
[6] Fugitive - Distributed fugitive leaks can only be
reduced by good housekeeping and by equipment
replacement. No efficiency estimate was made.
12.3 HOPE MANUFACTURE BY GAS PHASE PROCESSES
12.3.1 Process Description (Gas Phase Processes)
Union Carbide Corporation's (UCC) silica-supported ,
chromium-oxide-catalyst, gas-phase process was the first
ever commercialized. The original UCC plant was built at
Seadrift, Texas in 1968 (30 MM PPY capacity). BASF's
-147-
-------
gas-phase process is somewhat similar and is assumed to
have similar VOC emissions. Major differences between
the UCC and BASF processes, besides catalyst systems,
include use of fluid-bed technology for UCC's reactors
and use of mechanically stirred dry/reactor beds for
BASF. Because the BASF process uses a higher pressure
and temperature (500 psig, 100-110°C) than UCC (300 psig,
93°C), it would be somewhat higher in potential VOC
emissions.
The UCC fluid-bed gas phase process serves as the basis
for this description, but it is intended to represent
other gas phase processes as well (52), (54) , (55) .
Referring to Figure 12-2, HOPE by gas phase processes,
the "Feed" section of the flowsheet also depicts catalyst
preparation. Silica gel is impregnated with chromium
oxide via metallo-organic compounds, and water, and
hexane solvent. Impregnated catalyst is dried with warm
inerts (N2) and the resulting VOC stream, [3], is
flared. Dried catalyst is conveyed into the reactor bed
fluidized in N2« Gas-phase processes do not require
catalyst recovery systems since the high-activity
catalyst is left in the product polymer. Ethylene
monomer and suitable comonomers (such as butene-1) are
fed to the reactor along with the catalyst where
polymerization takes place around small catalyst
particles.
With UCC technology, the reactor is fluidized and the
polymerization reaction is controlled by recirculating a
large flow of gas and fines through a circulation
compressor and coolers. Compressor seal-oil (saturated
with ethylene) vents and gas sample analyzer vents are
-148-
-------
FRESH,
FEED
BUTENE-1
CO-MONOMER
RECYCLE
FRESH
ETHYLENE MONOMER
A
A
CAT SUBSTRATE
FROM _ _
CAT [3]
DRYER
POLYMER
PURGE
TANK
LAJ
T
FLARE &
INCINERATOR
SYSTEMS
CAT ACTIVATION
SOLVENTS
ETHYLENE
CIRCULATION CW
COMPRESSOR COOLER
-SMETALO-ORGAHICS
TO
FLARE
POLYMER
DISCHARGE
TANK
SAFETY
VENTS
VENT
VENT
GAS COMPRESSOR
-TO
FLARE
fflP
N2^-ST7
TPOLYMER
PURGE
I TANK
AIRS-—*-
AIR-CONVEYING
A.O.
EXTRUDER-PELLETIZER
TO PELLET STORAGE
GRANULE SALES
FEED
REACT
RECOVER
FINISH
Figure 12-2.- HOPE by gas-phase processes.
-------
taken from the reactor [2], From the reactor, product
polymer is blown down to a polymer discharge vessel and
purge tank system for product recovery. The polymer
discharge vessel vent is picked up by a separate vent
compressor and returned to the reactor. The polymer
purge tank is purged with N2 and this stream is
flared [3]. Product fluff or powder is air conveyed to
the powder polymer bins for storage and is captured by a
baghouse. Baghouse air is vented to the atmosphere [4].
A conventional extruder-pelletizer finishing line
follows the powder polymer bin storage.
12.3.2 VOC Emissions (Gas Phase Processes)
All significant emissions for gas phase HOPE are shown in
Figure 12-2 and summarized in Table 12-III0 VOC
emissions streams are indicated by bracketed numbers on
both Figure 12-2 and Table 12-111.
The major emission points for gas phase HDPE processes
are:
[1] Comonomer and solvent storage and loading - Comonomers
like butene-1 will be stored under pressure or with
inert gas to avoid oxygen contamination and safety
hazards. Solvents are used in small quantities for
catalyst impregnation. Total emissions are estimated
to be less than 0.01 lb/1000 and are negligible.
[2] Compressor Seal-Oil vents; Gas Sample Analyzer Vent -
Compressor seal oil becomes saturated with reactor
contents, primarily ethylene. These dissolved gases
bubble out in the seal oil recirculation surge tank
and are vented. The reactor is controlled by sampling
and analyzing the reactor recirculation flow. The Gas
-150-
-------
TABLE 12-111.- VOC EMISSIONS FROM HOPE MANUFACTURED BY GAS PHASE PROCESSES
I
M
Ui
Stream
[1] Co-Monomer and Solvent
Storage and Loading
[2] Compressor Seal-Oil Vents?
Gas Sample Analyzer Vent
[3] Product Receiver; Catalyst
Dryer
[4] Product Handling-Collect,
Compound, A.O. Feed,
Pelletizer, Storage
[5] Flare
[6] Fugitive
TOTALS
Uncontrolled
#/1000ft Resin
Neg
0.02
No Data
0.09
0.02
0.13
Current Practice
S/lOOOfl Resin
Neg
0.02
Neg
(Flared)
0.09
0.02
0.13
Well Controlled
«/1000# Resin
Neg
0.02
Neg
(Flared)
0.09
0.02
0.13
Composition
Vol %
72% Propylene
18% Butene-1
10% Isopentam
100% Ethylene
Ethylene,
Isopentane
<0.1% VOC
+99% N2
-------
Sample Analyzer samples a small portion of the sample
flow and vents it to the atmosphere; the bypassed flow
is sent to flare.
[3] Product Receiver; Catalyst Dryer - Potentially the
largest VOC stream for the process, this stream [3]
from the Polymer Purge Tank is flared in the UCC
version of the process. The catalyst dryer VOC are
those volatiles from the organo-metallic compounds and
solvents used in catalyst impregnations. Drying is
accomplished by jacket heat and an N2 purge. The
N2 Purge stream bearing catalyst drying VOC is
flared.
[4] Product Handling Including Collecting, Compounding,
Anti-Oxidant (A.O.) Feed, Etc. - Residual dissolved
monomer and other hydrocarbons are stripped from the
polymer by the flow of conveying air. Some volatile
A.O. material is lost during feeding and compounding
and is picked up by machine ventilation. These are
large very dilute (about 700 ppm, VOC) streams.
[5] Flare - The flare controls the largest potential VOC
stream, [3], from the product receiver, as well as the
catalyst drying VOC, the Gas Sample Analyzer bypass
flow, and miscellaneous vents. No data are available
concerning inlet or outlet conditions. It is assumed
that outlet VOC is negligible.
[6] Fugitive - Calculated value.
12.3.3 Applicable Control Systems (Gas Phase Processes)
Controls are discussed for the streams described in
Section 12.3.2 and shown in Figure 12-2 and Table 12-111.
[1] Storage and loading VOC emissions for comonomer and
solvent are less than 0.01 lb/1000, and controls are
not warranted.
-152-
-------
[2] Compressor Seal-Oil Vents and Gas Sample Analyzer
Vent - VOC emissions are small and control is not
warranted at present. Future controls could use
either local carbon cannister adsorption or piping to
flare or incinerator.
[3] Product Receiver; Catalyst Dryer - These are
potentially large sources of VOC emissions but are
completely controlled by existing flare systems. No
additional controls are needed.
[4] Product Handling and Collecting; Compounding with
Anti-Oxidant, A.O. Feed; Pellet Storage - Residuals
stripped from the polymer by conveying air make up
most of this VOC emission. Emissions are low (0.09
lb/1000) and dilute (<700 ppmv) at present. If
controls are needed, some form of conveying air
recycle should be investigated, or incineration in a
boiler may be feasible if a capacity match can be
made. Presently no controls are warranted.
[5] Flare - Well designed and well-controlled flares can
achieve greater than 99% reduction of gaseous VOC in
the inlet. The major VOC bearing stream (stream [3]
from the Polymer Purge Tank) is flared. No controls
are needed for flare exhaust.
[6] Fugitive - No applicable controls are known.
-153-
-------
SECTION 13
LOW DENSITY POLYETHYLENE
13.1 INDUSTRY DESCRIPTION
Low density polyethylene (LDPE) resins are thermoplastic
polymers of ethylene produced by free radical addition
reactions. They have densities below 0.94 g/cm^. The
lower density (compared to HOPE) results from their more
amorphous (i.e. less crystalline) molecular structure.
Most LDPE resins are homopolymers but some are copolymers
and these have potential VOC emissions of the comonomers as
well as ethylene* The most important comonomer is vinyl
acetate; some others include acrylic acid and ethyl
acrylate.
LDPE resins are the largest volume thermoplastic resins
produced in the U.S. and worldwide with U.S. production
passing the 7 billion ppy mark for the first time in 1978.
The 1978 U.S. production of LDPE was 7110 MM PPY and
capacity was 8245 MM PPY. These figures represent
increases of about 9% for production and capacity over
1977. Utilization of capacity, K, remained about the same
for 1978 as for 1977 at 85%, but was climbing at year's end
(1978). K was expected to reach 91% in 1979, based on
anticipated growth and no new capacity (2), (5).
-154-
-------
There are 14 U.S. manufacturers of LDPE, counting Phillips
Petroleum's swing capacity (300-350 MM LDPE), the bulk of
which presently also make HDPE. Although UCC is the
largest with 18% of the capacity and DOW second with 12%,
there is a wide distribution of the remaining 70%. Thus
the market is not particularly dominated by just a few
large producers. Tables 13-1(a) (56) and (b) (57) list the
U.S. manufacturers of LDPE and Table (b) gives the
location and capacity. Table 13-1 (a) is a simple summary
of Table 13-1 (b) for size comparison. Phillip's capacity
is not counted in these tables although Phillips is listed
in Table 13-1 (b).
Current over-capacity for ethylene (greater than 30%)
spells adequate raw materials supplys to LDPE resin
producers. Usually about 1.05 Ib ethylene is required to
produce a pound of product resin. Conditions in the
reactors are such that ethylene is a liquid and no solvents
are used except for naptha to dissolve the organic peroxide
initiators. Co-monomers used in some resins include vinyl
acetate, acrylic acid and ethyl acrylate. Potential VOC
emissions are primarily ethylene due to the high pressures
used in the reactors, but naptha, organic iniators, and
various co- monomers may also be emitted.
Classically LDPE was made by high-pressure (15,000 - 50,000
psig) technology and HDPE by low (500 - 1500 psig). New
low pressure technology (example UCC's catalyzed fluid bed
gas phase process) can produce LDPE as well as HDPE so the
classic distinction no longer exists. Phillips Petroleum's
Pasadena, Texas, plant is an example with 300 MM PPY (1978)
HDPE that can swing to make LDPE. It is currently making
HDPE and so is listed in Table 13-I(b) but the capacity is
not included in the total.
-155-
-------
TABLE 13-1(3).- SUMMARY OF U.S. MANUFACTURERS OF LDPE RESINS
AND THEIR CAPACITIES (56)
LOW-DENSITY POLYETHYLENE RESINS
Major Producers
ANNUAL CAPACITY AS OF MID YEAR
1978
Thousands of Metric Millions Of
Tons Pounds
Union Carbide 674 1,485
Dow 463 1,020
Northern Petrochemical 295 650
Gulf 386 850
USI 324 715
Du Pont 320 705
Cities Service 159 350
Exxon 299 660
Others 821 1,810
Total 3,740 8,245
-156-
-------
TABLE 13-I(b).- U.S. MANUFACTURERS OF LDPE RESINS
AND THEIR LOCATIONS AND CAPACITIES
ANNUAL CAPACITY
AS OF OCTOBER 19 78
CO. & PLANT LOCATION
ATLANTIC RICHFIELD COMPANY
ARCO/Polymers, Inc., sub.
Houston, Texas
CHEMPLEX CO. (jointly owned
by American Can Co. & Getty
Oil Company)
Clinton, Iowa
Thousands of
Metric Tons
181
Millions of
Pounds
400
141
310
CITIES SERVICE COMPANY
Chemical Group
Columbian Chemicals, division
Lake Charles, Louisiana 159
DART INDUSTRIES INC.
Chemical-Plastics Group
Plastic Raw Materials Sector
Rexene Polyolefins Company
Bayport, Texas 68
Odessa, Texas 181
350
DOW CHEMICAL U.S.A.
Freeport, Texas
Plaquemine, Louisiana
299
163
E.I. DU PONT DE NEMOURS & CO., INC.
Plastics Products and Resins Dept.
Orange, Texas 211
Victoria, Texas 109
EASTMAN KODAK COMPANY
Eastman Chemical Products, Inc.
subsidiary, Texas Eastman Co.
Longview, Texas 113
EXXON CORPORATION
Exxon Chemical Co., division
Exxon Chemical Co., USA
Baton Rouge, Louisiana 299
150
400
660
360
465
240
250
660
-157-
-------
TABLE 13-I(b).- U.S. MANUFACTURERS OF LDPE RESINS
AND THEIR LOCATIONS AND CAPACITIES (Continued)
ANNUAL CAPACITY
AS OF OCTOBER 1978
CO. & PLANT LOCATION
GULF OIL CORPORATION
Gulf Oil Chemicals Company
Plastics Division
Cedar Bayou, Texas
Orange, Texas
MOBIL CORPORATION
Mobil Oil Corporation
Mobil Chemical Co., div.
Petrochemicals Division
Beaumont, Texas
NATIONAL DISTILLERS AND
CHEMICAL CORPORATION
Chemicals Division .
U.S. Industrial Chemicals
Co., division
Deer Park, Texas
Tuscola, Illinois
Thousands of
Metric Tons
Millions of
Pounds
249
136
550
300
136
300
249
75
550
165
NORTHERN NATURAL GAS COMPANY
Northern Petrochemical Co., sub.
Polymers Division
Morris, Illinois 295
PHILLIPS PETROLEUM COMPANY
Plastics Division
Pasadena, Texas f
UNION CARBIDE CORPORATION
Chemicals and Plastics, div.
Seadrift, Texas 336
Texas City, Texas 125
Torrance, California 73
Union Carbide Caribe, Inc., sub.
Penuelas, Puerto Rico 141
650
Total
3,740
740
275
160
310
8 ,245
-158-
-------
13.2 LDPE MANUFACTURE BY LIQUID PHASE (HIGH PRESSURE)
PROCESSES
13.2.1 Process Description (Liquid Phase Processes)
Two primary variations of the high-pressure liquid-phase
processes have emerged. They are based on reactor type,
either tubular or autoclave. For the purposes of this
report, these two types and all high-pressure variations
of them will be treated as one process. Reactors are
operated continuously with initiator solution being
injected upstream or directly into the reactor. Reactor
effluent is flashed through separators with ethylene
recyled. Melted polymer is cooled, blended with
antioxidants, and pelletized. The polymerization is
highly exothermic so product cooling is used as well as
jacket cooling for tubular reactors.
A tubular reactor version of this process is described
but it is intended to apply to the autoclave reactor
version too.
Referring to Figure 13-1, LDPE by liquid-phase
(high-pressure) processes, fresh and. recovered ethylene
streams are dried and fed to the suction of the
multi-stage "primary" compressor where the pressure is
raised to about 4000 psig. Co-monomers and some recycle
gas from the high pressure separator wax K.O. drum join
the primary compressor discharge at the suction to the
"hyper" compressor. The "hyper" compressor raises the
pressure to the 40,000-50,000 psig reactor pressure. The
feed section also contains the initiator (organic
peroxide, catalyst-like materials), initiator diluent,
mix tank, and injector pumps. Prepared initiator
solution is injected directly into the reactor downstream
-159-
-------
cr>
o
I
TO
SAFETY
FLARE
FRESH
FEED
PROCESS
FUGITIVE
EMISSIONS
FROM
OLEFINS
RECOVERY
EXTRUDER-
PELLETIZER
FLARES AND
INCINERATION
SYSTEMS
A.
T/WAX FROM K.O.'S
"•*} SAFETY FLARES,
WASTE RESIN,
OLEFINS BOTTOMS
RESIDUES
TO WAX
INCINERATOR
TO PELLET
STORAGE
VENT/RECYCLE RECOVERY
COMPRESSOR
*REACTOR MAY BE AUTOCLAVE
FEED
REACT/RECOVERY
FINISH
Figure' 13-1.- LDPE by liquid-phase (high-pressure) processes
-------
of the hyper compressor discharge. The tubular reactor
shown is actually jacketed and supplied with both steam
(for "light off" or start-up) and cooling water. Reactor
effluent is throttled into the high pressure separator.
High pressure separator overheads are cooled for wax
condensation and returned to the hyper compressor suction
via the high pressure wax K.O. drum. High pressure
separator bottoms are throttled down to the low pressure
separator. The low pressure separator overheads are also
cooled for wax removal and routed through the low
pressure wax K.O. drum to the vent/recycle gas
compressor and thence to the olefins recovery unit (not
shown) . The low pressure separator bottoms are the
product resins still containing residual ethylene
monomer. These product resins are routed to the
finishing line where anti-oxidants (A.O.) are added and
they are pelletized in an extr uder-pelle t i zer . Hot
extruded pellets are water cooled and conveyed to a
hot-air dryer. Most residual ethylene monomer is driven
from the product resins by the extruder - pelleti zer and
dryer (vent [3]). Dried pellets are air conveyed to
pellet storage (_55) , (J58_) , ( 59 ) .
13.2.2 VOC Emissions (Liquid Phase) Processes
All significant emissions from high pressure LDPE resin
manufacture are shown in Figure 13-1 and listed in Table
13-11 with bracketed numbers.
The major emission points of this process are:
[1] Additives, initiator systems and hydrocarbon storage-
Various liquid hydrocarbon additives may actually be
co-monomers like vinyl acetate or 1-butene, or they
may be modifiers, etc., that are either lost as VOC
or actually recovered and reused. Initiator systems
-161-
-------
TABLE 13-11.- VOC EMISSIONS FROM LDPE MANUFACTURED BY LIQUID PHASE (HIGH PRESSURE) PROCESSES
Stream
Uncontrolled Current Practice Well Controlled
»/1000# Resin ft/10008 Resin fl/lOOOft Resin Composition
[1] Additive Initiator
Systems Storage
2.10
0.50
0.00
Ethylene; VOC
[2] Reactor Slowdown; Reject
System Scrubber and Vent
Tank 1.60
0.70
0.00
Ethylene only
to
I
[3] Polymer Extruder; Dryer;
Storage 0.90
[4] *Wax; Safety Flares;
Incinerator for Waste
Residues 0.40
0.80
0.04
0.20
0.04
Ethylene; VOC
0.2% VOC in
combustion gases
[5) Fugitive
7.60
1.65
1.65
100% ethylene
TOTALS
12.60
3.69
1.89
'Assumed same as wax incinerator values for HDP3 by Solvent Processes. See Section 12
-------
involve the special organic-peroxide initiators as
well as initiator solvents such as isopropanol,
acetone or naphtha. Various other hydrocarbon
additives and solvents are used and stored and stream
[1] includes them. Emissions are working and
breathing losses from tankage and mixing tank
ventilation as well as valve and pump seal leaks,
etc.
[2] Reactor blowdowns; reject system scrubber and reject
system vent tank - Reactor blowdowns occur when
pressure surges from the reactor must be relieved.
Blowdowns are routed to a wetted cyclonic separator
where resin fluff is scrubbed from the gas with
water. The resin-water, separator bottoms slurry is
routed to a vent tank where a nitrogen purge removes
degassing ethylene vapors. VOC are nearly pure
ethylene.
[3] Polymer extruder-pelletizer and dryer, pellet storage
bins - Organic liquid additives especially
anti-oxidants (A.O.) are incorporated into the resin
in the extruder and are the major non-ethylene VOC.
Emissions arise from extrusion, pelletizing, A.O.
addition, pellet drying before storage, and from the
pellet storage bins. VOC is ethylene and organic
(A.O.).
[4] Wax, waste and residue incinerator, safety flares - A
low molecular weight polyethylene wax is removed from
both high and low pressure separator vapor streams
after cooling. A special incinerator is used to
destroy this material as well as the waste resin
(contaminated or off-spec) and residues from the
olefins recovery unit (not shown on Figure 13-1).
Since the special incinerator will not achieve
-163-
-------
complete combustion, VOC will be various feed
impurities, low molecular weight polymer and residual
volatiles, and some vaporized wax or combustion
gases. Data given in Table 13-11, stream [4], are
for HOPE wax incinerators. Safety flares will be
(primarily) burning ethylene from various relief
valves, etc., and are assumed to have complete
combustion and thus no VOC.
[5] Fugitive process emissions - Most of these emissions
are reactor cell (high pressure ethylene) leaks.
Values shown in Table 13-11 are estimated by industry
for LDPE by high pressure processes.
13.2.3 Applicable Control Systems (Liquid Phase Processes)
The following controls are recommended for the bracketed
streams shown in Figure 13-1 and listed in Table 13-11.
[1] Additives, initiator systems and hydrocarbon storage-
tankage losses may be reduced to nearly zero with
inert gas safety padding and venting to incinerators
or flares or to recovery systems. The major VOC
source in this stream is the uncontrolled catalyst
(inititator) system, mix-tank vent. This tank should
be provided with an N2 pad and be vented to the
flare or recovery systems. Demonstrated efficiency
is nearly 100%.
[2] Reactor blowdowns; reject system scrubber and reject
system vent tank - Although cyclonic scrubber-
separators have been used to remove resin, gaseous
emissions have been uncontrolled for these safety-
related emissions. Newer plants route these gases to
special safety flares and efficiency of VOC removal
is essentially 100%.
-164-
-------
[3] Polymer extruder-pelletizer and dryer; pellet storage
bins - Although older plants do not always have them,
applicable controls for the extruder-pelletizer
include collection and flaring or recovery and reuse.
Pellet storage bin emissions could be greatly reduced
by hotwater soaking after pelletizing and before
drying or by other devo1 ati 1 ization means
demonstrated efficiency is 75%.
[4] Wax, waste and residue incinerator; safety flares -
Unburned wax was assumed to be 50%, low-molecular-
weight, polyethylene wax and 50% various hydrocarbons
(based on industry data for HOPE). About 0.8 Ib of
wax was produced per 1000 Ib of HDPE and this 0.8
lb/1000 Ib was arbitrarily assumed for high pressure
LDPE. The "uncontrolled" value in Table 13-11 is 50%
(0.8) = 0.4 lb/1000 (wax was assumed not volatile),
and the "controlled" value (95% efficiency wax
incinerator) is 5% (0.8) = 0.04 lb/1000. These
values were obtained by assuming the incinerator
makes an aerosol VOC of the unburned wax and that the
95% efficiency applies to waste resin and residues.
No controls are needed for incinerator effluent.
Safety flares were assumed 100% efficient in
combustion and so have no VOC or need for controls.
[5] Fugitive process emissions - High pressure reactor
cell leaks account for most fugitive emissions in a
high pressure LDPE unit. No applicable controls are
known. Generally, newer units have lower fugitive
emissions probably due to better seals and
construction techniques. In a well-controlled older
plant, fugitive emissions are the major source of
VOC.
•165-
-------
13.3 LDPE MANUFACTURE BY GAS PHASE PROCESSES
13.3.1 Process Description (Gas Phase Processes)
Union Carbide Corporation's (UCC) low pressure gas phase
LDPE process serves as the basis for this description,
but it is intended to represent others also. Although
UCC does not now have a commercial gas phase LDPE unit,
they are making market-test quantities of product resin
in a converted HOPE gas-phase unit of similar
construction. The VOC emissions in Table 13-111 are
projections for a UCC planned, 300 MM PPY unit.
The process description below is the same as that given
under Table 12-111, HOPE manufacture by gas phase
processes, except for the chapter number headings and for
the process schematic, Figure 13-2, and Table of VOC
emissions, Table 13-111.
Reference to Figure 13-2, LDPE by gas phase (low
pressure) processes, indicates that the "Feed" section of
the flowsheet also depicts catalyst preparation. Silica
gel is impregnated with chromium oxide via
metallo-organic compounds and water and hexane solvent.
Impregnated catalyst is dried with warm inerts t^)
and the resulting VOC stream, [3], is flared. Dried
catalyst is conveyed into the reactor fluidized in
N2• Gas phase processes do not require catalyst
recovery systems because the high-activity catalyst
remains with the product polymer.
Ethylene monomer and suitable comonomers (such as
butene-1) are fed to the reactor along with the catalyst
-166-
-------
FRESH
FEED
BUTENE-1
CO-KONOMER
RECYCLE
FRESH
ETHYLENE MONOMER
A
CAT SUBSTRATE
AIRfr-
CAT ACTIVATION
ETHYLENE^ _
CIRCULATION CW -
COMPRESSOR COOLER
SMETALO-ORGANICS
FLARE
SOLVENTS 9-i
CAT f3")
DRYING LJ
POLYMER
PURGE
FLARE &
INCINERATOR
SYSTEMS
SAFETY
VENTS
POLYMER
DISCHARGE
TANK
VENT'I (V):
|VBNT
GAS COMPRESSOR
FLARE
N2$~-S~7
TPOLYMER
A.O. f-*J PURGE
"^n TANK
AIRJ-*
SHIPPING
PACKAGING
LINE
AIR-CONVEYING
CO
FEED REACT RECOVER
Figure 13-2.- LDPE by gas-phase (low pressure) processes,
FINISH
-------
TABLE 13-111.- VOC EMISSIONS FROM LDPE MANUFACTURED BY GAS PHASE (LOW PRESSURE) PROCESSES
00
I
Stream
[1] Co-Monomer and Solvent
Storage and Loading
[2] Compressor Seal-Oil Vents;
Gas Sample Analyzer Vent
[3] Reactor Slowdown; Product
Receiver; Catalyst Dryer
[4] Product Handling-Collect,
Compound, A.O. Feed,
Pelletizer, Storage
(5) Flare*
(6) Fugitive
TOTALS
*99.8% combustion efficiency claimed.
Uncontrolled
#/1000# Resin
0.01
0.01
34.6
0.10
H /i
IM/ /*
0.02
34.7
Current Practice
#/1000# Resin
Neg
(Flared)
Neg
(Flared)
Meg
(Flared)
Neg
(Flared)
OA7
. U /
0.02
0.09
Well Controlled
#/1000# Resin
Neg
(Flared)
Neg
(Flared)
Neg
(Flared)
Neg
(Flared)
Om
. u /
0.02
0.09
Composition
Vol %
5% Butene-1
95% Isopropanol
100% Ethylene
N2,
Isopropanol
<0.1% VOC
+99% N2
100% Ethylene
-------
where polymerization takes place around small catalyst
particles.
After fluid-bed polymerization (UCC technology) in the
reactor, product polymer is blown down to a polymer
discharge vessel and purge tank system for product
recovery. The reactor is fluidized and the reaction
controlled by recirculating a large flow of gas and fines
through a circulation compressor and coolers. Compressor
seal-oil (saturated with ethylene) vents and gas sample
analyzer vents are taken from the reactor [2] . The
polymer discharge vessel vent is picked up by a separate
vent compressor and returned to the reactor. The polymer
purge tank is purged with N2 and this stream is
flared. Antioxidant (A.O.) is metered to the line and
product granules are blown to the powder polymer bin via
air and are captured there by a baghouse. • Baghouse air
is vented to the atmosphere [4] . A conventional
packaging line follows the powder polymer bin storage.
13.3.2 VOC Emissions (Gas Phase Processes)
All significant emissions for gas phase LDPE are shown in
Figure 13-2 and summarized in Table 13-111. VOC
emissions streams are indicated by bracketed numbers on
both the figure and the table.
The major emission points for gas-phase LDPE processes
are:
[1] Comonomer and solvent storage and loading -
Comonomers like butene-1 will be stored under
pressure or with inert gas to avoid oxygen
contamination and safety hazards. Solvents are used
-169-
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in small quantities for catalyst impregnation. Total
emissions are estimated to be less than 0.01 lb/1000
and are negligible.
[2] Compressor Seal-Oil vents; Gas Sample Analyzer Vent-
Compressor seal oil becomes saturated with reactor
contents, primarily ethylene. These dissolved gases
bubble out in the seal oil recirculation surge tank
and are vented. The reactor is controlled by
sampling and analyzing the reactor recirculation
flow. The Gas Sample Analyzer samples a small
portion of the sample flow and vents it to the
atmosphere; bypassed flow is sent to flare.
[3] Reactor Slowdown; Product Receiver; Catalyst Dryer-
Potentially the largest VOC stream for the process,
this stream [3] from the Polymer Purge Tank arises
from product charges and from shutdown/startup. It
is flared in the UCC version of the process. The
catalyst dryer VOC are those volatiles from the
organo-metallic compounds and solvents used in
catalyst impregnations. Drying is accomplished by
jacket heat and an N2 purge. The N2 purge
stream that bears catalyst drying VOC is also
flared.
[4] Product Handling Including Collecting, Compounding
Anti-Oxidant (A.O.) Feed, Etc. - Residual dissolved
monomer and other hydrocarbons are stripped from the
polymer by the flow of conveying air. Some volatile
A.O. material is lost during feeding and
compounding and is picked up by machine ventilation.
These are large very dilute (hundreds of ppm, VOC)
streams.
-170-
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[5] Flare - The flare controls the largest potential VOC
stream, [3], from the product receiver as well as the
catalyst drying VOC, the Gas Sample Analyzer bypass
flow, and miscellaneous vents. It is assumed that
outlet VOC is only 0.07 lb/1000 since claimed
efficiency is 99 .8%.
[6] Fugitive - Same as for HDPE by gas phase processes.
13.3.3 Applicable Control Systems and Efficiency for Gas Phase
LDPE Processes
Controls are discussed for the streams described in
Section 13.3.2 and shown in Figure 13-2 and Table 13-111.
[1] Comonomer and solvent storage and loading VOC
emissions are less than 0.01 lb/1000, and controls
are not warranted.
[2] Compressor Seal-Oil Vents and Gas Sample Analyzer
Vent - VOC emissions are small and flare control is
provided. No additional controls are needed.
[3] Reactor Slowdown; Product Receiver; Catalyst Dryer -
These are potentially large sources of VOC emissions,
but they are completely controlled by existing flare
systems. No additional controls are needed.
[4] Product Handling and Collecting; Compounding with
Anit-Oxidant, A.O. Feed; Pelletizer and Storage -
Stripped residuals from the polymer removed by
conveying air make up most of this VOC emission.
Emissions are low (0.10 lb/1000), dilute (<1000 ppmv)
-171-
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at present, and are flared. No additional controls
are needed.
[5] Flare - Well-designed and well-controlled flares can
achieve greater than 99% reduction of gaseous VOC in
the inlet. It was assumed this flare was 99.8%
efficient. The major VOC bearing stream (Stream [3]
from the Polymer Purge Tank) is flared. No controls
are needed for flare exhaust.
[6] Fugitive - No applicable controls known.
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SECTION 14
POLYPROPYLENE
14.1 INDUSTRY DESCRIPTION AND STATUS
The principal characteristics of polypropylene that have
contributed to its rapid growth and acceptance are:
o Comparatively low density;
o Improved stiffness, deflection temperature, clarity,
stress-crack resistance, chemical resistance, and
electrical insulating properties as compared to
low-density polyethylene;
o Mechanical strength properties sufficient to compete
with more costly engineering plastics in many
applications;
o Good injection-molding characteristics;
o Ability to be drawn and oriented - this is the basis
for the production of polypropylene fibers, and of
oriented film and bottles.
Polypropylene of commercial value could, not be produced
until the stereospecific catalysts were discovered in the
1950's. Because of the methyl group it contains, a
molecular unit of polypropylene is asymmetric and can
assume either of these two regular geometric arrangements;
isotactic, with all methyl groups aligned on the same side
of the chain, or synd iotactic, with the methyl groups
alternating. All other forms, in which this positioning is
more or less random, are called atactic. First prepared by
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Giulio Natta in 1954, only the isotactic form is of
commercial interest.
Because it is linear and stereoregular, isotactic
polypropylene is capable of crystallization when cooled
from the melt. Typically, commercial samples of
polypropylene contain about 70% crystalline material
(isotatic), with the remainder amorphous (atactic). A
significant drawback of polypropylene is its
comparatively low, low-temperature impact strength. To
improve this property, blends with ethylene-propylene
elastomers, and copolymers containing 5 to 20% ethylene,
were introduced. Other drawbacks of polypropylene
include its narrow melt range and its tendency to sag
when hot. These weaknesses have prevented it from making
deep penetration of some large thermoplastic resin
markets. The major current uses of polypropylene are:
Wt%
Fiber products 30%
Car and Truck Parts 15%
Packaging 15%
Toys, housewares 5%
Appliance Parts 5%
Other 30%
Total 100%
The automotive market for polypropylene has been growing
at a rate faster than has the to'tal demand for
polypropylene, mainly because of its displacement of
steel (due to its lighter weight). Fiber products of all
kinds actually make up the largest single use of
polypropylene. These uses account for nearly a third of
domestic U.S. consumption, and they grow at close to or
slightly above the rate for all polypropylene (an average
rate of 8% annually) . Packaging ranks close to
-174-
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automotive use in importance as a polypropylene outlet.
Most attention in packaging uses goes to oriented
polypropylene films, which are cutting into use of
cellophane dramatically. Other uses - for example,
bottles, certain wire and cable coverings, and appliance
parts - have small market bases, large growth rates, and
big potential.
Polypropylene resins are supplied in many grades for a
variety of uses. There are major distinctions between
homopolymer, intermediate-impact copolymer, and high-
impact copolymer, the grades may also differ in specific
formulation. New super-active catalyst systems of the
type that have been successfully used in high-density
polyethylene production for some time are beginning to be
used in polypropylene production.
Polypropylene resins are converted to end products
through injection molding and through variations of the
extrusion process. Filament extrusion is- the most
important of the latter.
Key data showing the 1977 supply/demand picture of
polypropylene in the United States (2), (60) are
tabulated below:
POLYPROPYLENE RESINS - U.S. SUPPLY/DEMAND, 1977
(Millions of Pounds)
ANNUAL PRODUCTION CAPACITY (year-end) 3,658
ESTIMATED PRODUCTION 2,750
ESTIMATED DOMESTIC CONSUMPTION 2,470
ESTIMATED EXPORTS 280
-175-
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Demand levels and corresponding U.S. polypropylene
capacities are tabulated, as follows, for the period
1978-1980 with projections for both the basic and
extraordinary set of demand assumptions, (j>) , (60) .
U.S. POLYPROPYLENE CAPACITY VERSUS DEMAND
1978 1979 1980
Basic Extra* Basic Extra* Basic Extra*
Average Annual Demand 8% . 10% 8% 10% 8% 10%
Growth Rate
Total Demand (Millions 2,973 3,028 3,.214 3,333 3,474 3,670
of Pounds)
Effective Capacity, (90% 4,325 4,795 4,795
of Nameplate, Millions
of Pounds
Capacity Utilization 69% 70% 66% 69% 72% 76%
*Extra = Extraordinary
Polypropylene demand is projected to grow at an average rate
of 8.0% per year. This assumes a GNP growth on the order of
3.5% and one year of very low or zero growth in five years.
U.S. producers of polypropylene are listed in Table 14-1,
and this includes the new capacities already announced for
completion through 1979, (61).
-176-
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TABLE 14-1.- U.S. PRODUCERS OF POLYPROPYLENE RESINS (61)
COMPANY AND PLANT
LOCATION
START-UP ANNUAL YEAR-END CAPACITY
YEAR (MILLIONS OF POUNDS)
1977 1979
ATLANTIC RICHFIELD CO.
ARCO/Polymers, Inc.
subsidiary
La Porte, Texas3 1962
DART INDUSTRIES, INC
Chemical Group
Plastic Raw Material
Sector, Rexene Poly-
olefins Company
Bayport, Texas 1976
Odessa, Texas 1966
EASTMAN KODAK CO.
Eastman Chemical Prod.,
Inc., subsidiary Texas
Eastman Company
Longview, Texas 1960
EXXON CORPORATION
Exxon Chemical Co.
division Exxon Chemical
Company, U.S.A.
Baytown, Texas 1960
GULF OIL CORPORATION
Gulf Oil Chemicals Co.
division, Plastics Div.
Cedar Bayou, Texas 1978
HERCULES INCORPORATED
Polymers Department
Bayport, Texas 1974
Lake Charles, LA • 1961
280
400
150
150
150
150
140
140
500
550
400
750
400
400
750
-177-
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TABLE 14-1.- U.S. PRODUCERS OF POLYPROPYLENE RESINS (17)
(Continued)
COMPANY AND PLANT
LOCATION
START-UP ANNUAL YEAR-END CAPACITY
YEAR (MILLIONS OF POUNDS)
1977 1979
NORTHERN NATURAL GAS CO.
Northern Petrochemical Co.
subsidiary, Polymers Div.
Morris, Illinois 1978
NOVAMONT CORPORATION
Kenova, West Virginia 1961
La Porte, Texas 1979
PHILLIPS PETROLEUM CO.
Plastics Division
Pasadena, Texas 1970
SHELL CHEMICAL COMPANY
Norco, Louisiana 1977
Woodbury, New Jersey 1963
SOLTEK POLYUMER CORP.
Deer Park, Texas 1978
STANDARD OIL CO. (IND)
Amoco Chemicals Corp.,
subsidiary.
Chocolate Bayou, Texas 1971
New Castle, Delaware 1960
160
180
150
300
200
160
265
180
300
300
200
275
250
575
250
TOTAL
3,685
5,370
aPlant was acquired from Diamond Shamrock Corporation in April 77.
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14.2 POLYPROPYLENE MANUFACTURE
14.2.1 Process Description
Commercial polypropylene resins are characterized by
having a controlled content of isotactic material. They
are obtained through coordination polymerization,
employing a heterogeneous Ziegler-Natta type catalyst
system, which typically is a combination of titanium
tetrachloride and aluminum alkyls.
The process described here is a continuous slurry
process; it is the most widely used commercially. Figure
14-1 shows a schematic for the process. The major raw
material, propylene, is stored in pressure vessels while
methanol solvent and hexane diluent are stored in
vertical floating and fixed roof storage tanks.
The process steps consist of mixing and metering the
catalyst system, manufactured on site, into the
polymerization reactor along with propylene and the
diluent hexane, which acts as a heat transfer agent and
polymer-suspending medium. A portion of the mixture of
polymer/monomer/diluent is continuously fed to a flash
tank where volatile components, mostly propane and
unreacted propylene, are vaporized, withdrawn, and
recovered. Slurry from the flash tank is fed to the
deactivation/decanting section for washing with methanol
to remove most of the catalyst residues. The light
hydrocarbon crude product slurry is decanted from the
heavy methanol-water phase; the latter is fed to methanol
recovery. The light crude product slurry, containing
isotactic polymer product solids and an atactic
polymer-hexane solution, is fed to a centrifuge, where
the two phases are separated. The isotactic polymer
-179-
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TO FLARE
OD
O
I
cn
CHILLER I J
TO WASTE WATER TREATMENT
TO WASTE OIL TREATMENT
«. ATATIC POLYMER TO
RECOVERY OR LANDFILL
EXTRUDER/PELLETIZER
DEACTIVATION/DECANTING
SECTION .
PELLET
STORAGEl
EXAU,ST AIR
ii
CYCLONE
PRODUCT
(TO HOPPER CARS)
PELLET PRODUCT
••(TO BAGS,CARTONS,
OR HOPPER CARS)
•INCLUDES VIRGIN, RECOVERED
AND SPENT MATERIAL
FEED
REACT
RECOVERY
FINISH
Figure 14-1.- Polypropylene - Continuous slurry process,
-------
solids layer is fed to the product drier while the
atactic-hexane solution phase is fed to diluent recovery.
Dried polypropylene/ containing less than 0.5% volatiles
by weight, is extruded, pelletized and sent to product
storage.
In the methanol recovery section, the crude methanol
streams are refined and recycled and the bottoms streams,
mostly water and catalyst metals are sent to sewer. In
the hexane recovery section, hexane is purified and dried
for recycle, and the atactic solids are recovered or
landfilled. The water stream containing small amounts of
hexane is sent to sewer or recycled for cooling water.
Methanol, a polar materal, is a catalyst deactivation
agent when intermixed with the flash tank slurry. Highly
corrosive products are formed by catalyst residues so
that construction materials exposed to them must be
designed accordingly and special efforts must be made to
minimize such residues in the process. Catalyst residues
also affect the resins processing characteristics
adversely.
While all of the installations for which data were
received use the process described, continuous slurry
with a Zieg 1er-natta type catalyst, a few process
differences were noted. One producer used a mixture of
aliphatic hydrocarbons with 10 to 12 carbon atoms as a
process diluent rather than hexane. In another case
isopropyl alcohol replaced methanol as a washing/
deactivation agent. Minor differences exist, in certain
processes, in equipment used (in the deactivation/
decanting section) for removing catalyst residues from
the polymer and diluent from the slurry.
-181-
-------
Besides the common method of extruding and pelletizing
product, some facilities may also send it to storage in
flake form. Polymer dryers vary with the facility but
the fluid bed dryer with hot nitrogen or air is now the
most common. Most plants use nitrogen blanketing to some
degree on process systems and/or storage, and one
facility reported nitrogen blanketing of essentially the
entire system.
14.2.2 VOC Emissions
All emission rates and sources for this product are
listed on Table 14-11, and the sources are shown on the
flowsheet, Figure 14-1. Numbers for the streams
discussed below are consistent with the numbers
designating the same streams used on the table and on the
flowsheet.
[1] Alcohol and process diluent storage tanks - These
streams vent organic vapors in nitrogen (used for
inert blanketing) during normal tank breathing and
filling. The VOC portion of each stream is composed
only of the alcohol or process diluent stored. The
numbered stream represents the total emissions from
all such tanks.
[2] TiCl^ and aluminum alkyl liquid storage tanks
(catalyst raw materials) - These streams vent organic
vapors from the catalyst manufacturing section
storage during normal breathing and filling. VOC is
process diluent (i.e., hexane) in blanket nitrogen.
-182-
-------
TABLE 14-11.- VOC EMISSIONS FROM POLYPROPYLENE MANUFACTURE
BY A CONTINUOUS SLURRY PROCESS
Current
Uncontrolled Practice Well Controlled
Stream #/1000# Resin #/1000#Resin #/1000# Resin
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
Liquid Storage:
Alcohol; Diluent
Aluminum Alkyl and
TiCl4 Storage
Catalyst Manufacturing
Section
Polymerization Reactor
Deactivation/
Decanting Section
Alcohol Recovery
Section
Diluent Recovery
Section
Product Dryer;
0.18
0.01
0.13
4.07
21.30
Nil
11.40
8 .02
0.08
Nil
0.01
0.00
0.06
Nil
0.32
2.99
0.00
Nil
0.00
0.00
0.00
Nil
0.00
0.15
Extruder/Pelletizer
Section
[9] Fugitive. Primarily 0.39 0.39 0.39
API Separator
Total 45.50 3.85 0.54
-183-
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[3] Catalyst manufacturing section - This stream is
similar to [2] . It vents volatile organic vapors
dispersed in blanket nitrogen but with an
approximately equal amount of ethane (not within VOC
definition). One of the relatively small emission
streams, [3] is effectively controlled in current
practice.'
[4] Polymerization reactor - This stream vents organic
process off-gases, mostly propane and unreacted
propylene with some diluent vapors. A large amount
of blanket nitrogen from the reactor accompanies the
organic off-gases.
[5] Process deactiyation/decanting section - This stream
is process diluent and wash alcohol vapors in blanket
nitrogen. It is the largest source of VOC emissions
in the typical plant before control but is
effectively controlled in current practice.
[6] Alcohol recovery section - VOC, primarily process
alcohol vapors and traces of by-product organics such
as cyclohexane, are vented with inert blanket
nitrogen. Venting occurs when the recovery section
is in (normally continuous) operation and emissions
are small.
[7] Diluent recovery section - This stream vents inert
blanket nitrogen with small amounts of volatile
organic compounds. VOC are composed of diluent
(hexane) and alcohol (methanol) vapors and other
organics such as ethane (not considered a VOC). This
stream is the second largest VOC emission stream in a
typical plant (prior to control) and the third
largest source of VOC emissions in current practice
(after control).
-184-
-------
[8] Product dryer and extruder/pelletizer section - This
stream vents the product dryer near the end of the
production train. Emissions from the extruder/
pelletizer are included. The dryer emission is the
largest VOC stream emitted to the atmosphere from a
typical plant as currently practiced. The
extruder/pelletizer stream is much smaller both
potentially (uncontrolled) and controlled (current
practice) . A single vent system and control
technology could serve both sections in some process
design schemes. Emissions consist of vapors of
hexane, methanol, and propane, and (possibly) some
propylene diluted by a large quantity of drying
medium, commonly, hot N2«
[9] Fugitive - Most fugitive emissions arise from the
waste organic/water separator (API) serving the
section. VOC are mostly process alcohol with some
diluent and other organic solvents. Fugitive
emissions are the second largest source of VOC
emissions from a typical plant with current practice.
14.2.3 Applicable Control Systems
The following control technologies are recommended for
the emission streams described in Section 14.2.2 and on
Figure 14-1. Flaring with or without refrigerated vapor
condensation is the control system recommended for the
majority of emissions. This system has a high control
efficiency (90% assumed) and is commonly practiced.
Sale, or use as a boiler fuel, now common for some of the
emission streams, constitutes complete abatement (100%
abatement) and is equivalent to any recommended control
technology. Actual flare systems used are subject to
normal design considerations such as available pressure,
required line sizes and materials, cross contamination
-185-
-------
(within a process section) flammability, etc.
[1] Alcohol and process diluent storage tanks -
Refrigerated vent condensers on each vent followed by
flaring.3 100% control efficiency was assumed.
[2] TiCl4 and aluminum alkyl liquid storage tanks -
Refrigerated vent condensers on each vent followed by
seal pots. No additional controls are needed.
[3] Catalyst manufacturing section - Refrigerated vent
condenser followed by flaring. 100% efficiency was
assumed.
[4] Polymerization reactor - Flaring vent stream. No
additional controls are required.
[5] Process deactivation/decanting section - Flowing vent
stream. 100% efficiency was assumed.
[6] Alcohol recovery section - Refrigerated vent
condenser. No additional controls are required.
[7] Diluent recovery section - Refrigerated vent
condenser followed by flaring. 100% efficiency was
assumed.
[8] Product dryer and extruder/pelletizer section -
Flaring of vent streams preceded by refrigerated vent
condenser on dryer vents only. 95% efficiency was
assumed.
[9] Fugitive - Enclose separation vessel with necessary
control systems. The organic phase should be piped
to waste or slop oil treatment arid the water phase to
waste water treatment. An acceptable alternative
control scheme would be an enclose.d tank or vessel
with a vapor recovery system. No control was
assumed.
aprocess economics frequently dictate use of cooled and/or
refrigerated vent condensers in these services.
-186-
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SECTION 15
POLYSTYRENE RESINS
15.1 INDUSTRY DESCRIPTION
Polystyrene offers a combination of excellent physical
properties and processability at a relatively low price for
thermoplastic materials. It is crystal clear and has
colorability, rigidity, good electrical properties, thermal
stability, and high flexural and tensile strengths. The
family of polymers and copolymers from styrene monomer and
its modifications ranks third in all plastics consumption
in this country.
Products made of polystyrene include packaging materials,
refrigerator linings, major and small appliance parts,
containers, radio and television housings, housewares,
toys, insulation for lighting and signs, insulating boards
and cups, automotive components, telephones, and machine
parts.
The demand for polystyrene did not grow rapidly until after
World War II, when the many plants built during the war to
supply styrene monomer for GR-S synthetic rubber production
began to make a large quantity of relatively inexpensive
styrene monomer available. Polystyrene resins are marketed
in general purpose (styrene homopolymer) and rubber
modified impact grades (typically homopolymer plus 5-10%
of polybutadiene rubber). Slightly more than one half of
-137-
-------
the polystyrene sold is impact grade. Polystyrene is
often marketed in pellet or bead form; however, some is
captively converted to film, sheet, and foam.
There are approximately seventeen major manufacturers of
polystyrene resins in the U.S. These producers are shown
in Table 15-1 as follows (65).
Production of polystyrene resins in the U.S. for 1978
(2) was 3823 MM pounds including exports. The projected
U.S. consumption growth rate for the period of 1977-1982
is 3 .9-5.9%/year. Using 5% growth and the 1978
production, a 1979 capacity estimate (jj) of 5373 gives
utilization, K = 0.75.
15.2 MANUFACTURE OP' POLYSTYRENE RESIN BY BULK (MASS),
SUSPENSION, OR BULK-SUSPENSION PROCESSES
15.2.1 Process Description
The processes described here and shown on Figure 15-1 are
the most widely used today for producing polystyrene
resins. The equipment shown can be used to make either
general purpose grade or impact grade polystyrene by the
suspension process, the bulk (mass) process, or the
bulk-suspension process (63 ) , (66).
The suspension process is, alone or in .conjunction with
bulk prepolymerization (the bulk-suspension process), the
most widely used process for polystyrenes today. The
bulk or mass process was formerly the most widely used.
Suspension polymerization is essentially mass
polymerization taking place in small spherical droplets
of monomer suspended in water; each droplet acts as an
-188-
-------
TABLE 15-1.- U.S. PRODUCERS OF POLYSTYRENE RESINS (65)
ESTIMATED ANNUAL CAPACITY AS OF
COMPANY AND PLANT LOCATION JULY 1, 1977 (in Millions of Ibs)
A & E PLASTIK PAR CO., INC.
A & E Plastics Division
City of Industry, California 45
AMERICAN HOECHST CORPORATION
Foster Grant Company, Inc., sub.
Plastics Division
Chesapeake, Virginia 210
Leominster, Massachusetts 120 610
Peru, Illinois 280
AMERICAN PETROFINA, INCORPORATED
Cosden Oil & Chemical Co., subsidiary
Big Spring, Texas 150
Calumet City, Illinois 270 420
Polymer Research Inc., subsidiary
Orange, California 60
Windsor, New Jersey 120 180
ATLANTIC RICHFIELD COMPANY
ARCO/Polymers, Inc., subsidiary
Beaver Valley, Pennsylvania 440
BASF WYANDOTTE CORPORATION
Polymers Group
Styropor Division
Jamesburg, New Jersey 95
DART INDUSTRIES INC.
Chemical Group
Plastic Raw Materials Sector
Rexene Styrenics Company
Holyoke, Massachusetts 60
Joliet, Illinois 40 130
Santa Ana, California 30
DOW CHEMICAL U.S.A.
Allyn's Point, Connecticut 150
Ironton, Ohio 180"
Joliet, Illinois 130 920
Midland, Michigan 260
Torrance, California 200
CARL GORDON INDUSTRIES, INC.
Gordon Chemical Company Division
Oxford, Massachusetts 110
Hammond Plastics Division
Worcester, Massachusetts 75 265
Hammond Plastics - Midwest, Inc.
Owensboro, Kentucky 80
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-------
TABLE 15-1.- U.S. PRODUCERS OF POLYSTYRENE RESINS (continued)
ESTIMATED ANNUAL CAPACITY AS OF
COMPANY AND PLANT LOCATION JULY I, 1977 (in Millions of Lbs)
HUNTSMAN CHEMICAL AND OIL CORPORATION
Troy, Ohio 30
MONSANTO COMPANY
Monsanto Plastics & Resins Company
Addyston, Ohio 300
Decatur, Alabama 100 800
Long Beach, California 50
Springfield, Massachusetts 350
PLASTIC SERVICES AND PRODUCTS INC.
S.P. Polymers, Inc., division
Los Angeles, California 20
POLYSAR GROUP
Polysar Plastics Inc.
D.C. Division, Polystyrene Plant
Forest City, North Carolina 40
Polysar Resins Inc.
Copley, Ohio ' 120 235
Leominster, Massachusetts 115
THE RICHARDSON COMPANY
Plastics Group
Polymeric Systems Division
Channelview, Texas 50
West Haven, Connecticut 40
SHELL OIL COMPANY
Shell Chemical Company, division
Belpre (Marietta), Ohio 220
STANDARD OIL COMPANY (INDIANA)
Amoco Chemicals Corporation, subsidiary
Joliet, Illinois 250
Medina, Ohio 45 320
Torrance, California 35
Willow Springs, Illinois 35
UNION CARBIDE CORPORATION
Chemicals and Plastics, division
Bound Brook, New Jersey 125
Marietta, Ohio 225 ' 350
UNITED STATES STEEL CORPORATION
USS Chemicals, division
Haverhill, Ohio 225
TOTAL 5,345
-190-
-------
VACUUM
PUMP
DEMISTER
CENTRIFUGE. | ,
(D^FER)' I
FAN/DEMISTERI I
A n
Mil 11II' \/
^•TO FLARE
DISSOLVER PREPOLYMERIZER
(MIXER) (BULK REACTOR)
FEED/DISSOLVE
•EITHER GENERAL PURPOSE
GRADE OR IMPACT GRADE
POLYSTYRENE .CAN BE HADE
PREPOLY/REACT
EXTRUDER-PELLETIZER
(WITH QUENCH BATH)
PRODUCT OUT
RECOVERY
FINISH
Figure 15-1.- Polystyrene by suspension, bulk, or bulk-suspension processes.
-------
individual mass polymerization system. Suspension
simplifies heat transfer with the heat of reaction
dissipating into water. The process allows better rate
and temperature control than in mass polymerization.
Separation of the polymer from water and the suspending
agents is not difficult. A typical reaction formulation
for this process is deionized and deaerated water (68
parts), deoxygenated styrene monomer (100 parts), hydroxy
apatite (0.77 part), dodecyl benzene sulfonate (0.00256
part), and benzoyl peroxide (0.204 part).
The bulk-suspension process is a natural evolution from
the bulk and the suspension processes, combining some of
the advantages of each. The equipment shown can be used
either for continuous or batch processes. The finishing
and separation steps downstream of the suspension reactor
and devolatilizer a're normally run continuously in either
case.
All of the equipment shown would be used if making impact
grade polystyrene by the bulk-suspension process. Impact
grade resin requires monomer modification by dissolving
chopped butadiene rubber into the styrene. For general
purpose grade resin, the manufacturer simply skips this
elastomer predissolving step. The suspension process
could be used alone by deleting the bulk prepolymer-
ization step. Either grade of polystyrene, impact or
general purpose, could be made by the suspension process.
A medium impact resin is made by blending the general
purpose and high impact polystyrenes.
Specific equipment configurations and the number and
types of process trains vary widely depending on the
product grades and dominant process.
-192-
-------
Typically the following operating steps are performed to
make impact grade polystyrene by the bulk-suspension
process:
Step 1. Rubber elastomer dissolving.
o Styrene is charged and heated in the dissolving
tank.
o Rubber bales are chopped and added to hot
styrene in the dissolving tank.
o The mixture is agitated for 4-8 hours to
complete rubber dissolution. Rubber/styrene
solution is transferred to the bulk
prepolymerizer.
Step 2. Bulk (Mass) Prepolymerization
o The rubber/styrene solution heated to reaction
temperature in the prepolymerizer.
o Catalyst is added, and the mixture is allowed to
react to 30-40% conversion of styrene monomer.
The resulting suspension is transferred to the
suspension reactor.
Step 3. Suspension Polymerization
o The reactor is evacuated. Demineralized water
and suspending agents are charged and the
reactor evacuated a second time.
o The prepolymerized suspension from Step 2 is
transferred into the suspension reactor with
agitation to ensure satisfactory particle size
is made.
-193-
-------
o After the mixture is heated to reaction
temperature, additional catalyst (usually an oil
soluble peroxide) is added as required by the
formulation and the mixture is allowed to react.
The reaction temperature may be increased and/or
catalyst additions made to ensure a high percent
conversion of styrene. Three to eighteen hours
total reaction time may be required.
o The product suspension of beads in water is
cooled, devolatilized, and transferred to slurry
storage tankage.
Step 4. The beads produced in the suspension
polymerization reactor are washed and dewatered
with a solid bowl centrifuge. Surface water and
suspending agent removals are accomplished in
this step.
Step 5. Bead form polymer may be sold as is, but it is
more commonly converted to pellet form. For
pellet production, dyes, pigments, lubricants,
antistatic agents, and other additives are
mixed with the beads and then melt extruded
through a die. Extruded polymer is cooled in a
quench bath and, finally, pelletized.
There are a number of variations on the process described
in addition to the reaction process variations noted
above. Some of these include:
o The residual monomer level in the beads may be
reduced by steam stripping of the slurry.
o Increased bead washing efficiency may be obtained
by first vacuum filtering the slurry, then
-194-
-------
reslurrying in fresh water, and then
centrifuging.
o Various hot air dryers, such as rotary, fluid bed
or flash, may be used after the centrifuging
step.
15.2.2 VOC Emissions
All significant emission rates and sources for this
product are shown on Table 15-11. The schematic
flowsheet for this product, which includes the emission
streams and their sources, is Figure 15-1. The same
stream numbering system is used throughout.
[1] Styrene monomer, reactor feed, and mixing/ dissolving
tanks - All of these sources are fixed roof tanks or
kettles operating at atmospheric pressure. The VOC
emission is essentially styrene with traces of other
organics. The emission cause is normal breathing and
filling for all sources so atmospheric air will be
part of the emission. Operation of these sources can
be either batch or continuous. Together they are a
relatively small source of VOC emissions.
[2] Reactor atmospheric vent - This emission results from
charging the reactor in a batch operation. The
stream is primarily styrene vapor in air or nitrogen.
It is typically at 110°F and potentially of a
moderate quantity.
[3] Devolatilizer overhead condenser - These are
non-condensibles from this condenser, and typically
exhaust through a vacuum pump. An oil demister is
often used downstream of the vacuum pump primarily to
-195-
-------
TABLE 15-11.- VOC EMISSIONS FROM POLYSTYRENE RESIN MANUFACTURE
a\
Stream
Uncontrolled Current Practice Well Controlled
#/1000# Resin #/1000# Resin #/1000# Resin
[1]
[2]
[3]
[4]
[5]
[6]
Styrene monomer, reactor
feed, and feed mixing/
dissolving tanks
Reactor atmospheric vent
Devolatilizer overhead
condenser
Styrene recovery tower
overhead condenser
Recycle Styrene storage
and intermediate hold tanks
Extruder-pelletizer vent
TOTALS
0.11
0.12
3.10
0.10
nil
0.19
3.62
0.11
0.12
2.07
0.10
nil
0.14
2.54
0.06
0.01
0.17
0.01
nil
.00+
0.25+
-------
separate out organic mist. The stream is largely air
with styrene, the main VOC component, along with
traces of other volatile organic components from the
reaction melt. The temperature will normally be
moderate, typically 80°F, unless steam jets are used
instead of a vacuum pump, in which case it will be
much hotter, perhaps 212°F. This is potentially the
largest VOC stream in the plant, but it is not a
particularly large quantity. It would be present
regardless of which basic process was being utilized
in the plant equipment. This part of the plant
normally runs as a continuous operation regardless of
how the polymerization section is run.
[4] Styrene recovery section ove'rhead condenser - The
noncondensibles from this condenser usually are also
exhausted through a vacuum pump, and this is similar
to the stream discussed in [3] above except that it
is smaller. This stream is composed of a small
percent of styrene in air, normally at nearly ambient
temperature. If stream ejectors are used instead of
the vacuum pump, it will contain water vapor and be
at about 212°F. This is normally a continuous
emission stream.
[5] Intermediate hold tanks (other than for reactor) and
recycle styrene storage tank - These sources are all
fixed roof tanks and constitute a minor source of VOC
emissions (the least quantity of any of the streams
listed). The recycled styrene hold tank and the hold
tank for the styrene recovery tower feed are the main
sources in this stream. Normal breathing and filling
are the causes of emissions for these and the
emission composition in both cases is air drawn from
-197-
-------
the atmosphere and styrene vapor from the liquid
stored. Other hold tanks have essentially no VOC
emissions. These tanks are all in the continuous
section of the plant.
[6] Extruder-pelletizer section vent - This stream is a
continuous emission, but it is typically of a
fugitive type. The emission results when hot,
extruded, polystyrene-product strands from the
dieplate contact the cold quench bath water.
Typically, it is composed of 5-7 ppm styrene in water
vapor and air at approximately ambient temperature.
Though small, this stream is potentially the second
largest VOC emission source from the plant.
15.2.3 Applicable Control Systems
The following control technologies are recommended for
the emission streams described in Section 15.2.2 and
shown on the schematic flowsheet for this product. The
same stream numbering system is followed here.
[1] Styrene monomer, reactor feed, and mixing/dissolving
tanks - Use a pressure equallizing vapor return line
to the tank cars or trucks from the styrene monomer
tank to eliminate working losses from tank filling
(reduces styrene tank VOC emissions by approximately
58%). No other controls are required, except for
conservation valves, where usable, and those would
be justified for economic reasons.
[2] Reactor atmospheric vent - Flare this stream. A 90%
reduction efficiency is assumed for this mode of
control.
-198-
-------
[3] Devolatilizer overhead condenser - Flaring is the
primary control to be used here. 90% reduction
efficiency is assumed for this mode of control. An
oil demister is also recommended, primarily for
elimination of organic mist. However, it should
effect some VOC reduction and a conservative estimate
of 20% reduction has been assumed.
[4] Styrene recovery overhead condenser - Flare this
stream. A 90% reduction efficiency is assumed for
this mode of control.
[5] Intermediate hold tanks and recycle styrene storage
tank - These are very low VOC emission sources and
require no control other than .conservation valves.
[6] Extruder-pelletizer section vent - F],are this stream.
A 90% reduction efficiency is assumed. As this
emission is of the fugitive type, a hood and fan will
be required for area pick-up. An oil demister is
also recommended, primarily for elimination of the
mist created.
-199-
-------
SECTION 16
POLYVINYL ACETATE
16.1 INDUSTRY DESCRIPTION
Polyvinyl acetate (PVAc) in this report includes vinyl
acetate homopolymer and all the copolymers in which vinyl
acetate is the major constituent. Polyvinyl acetate is
marketed as an emulsion and as a solid resin. Homopolymer
and copolymer emulsions are the predominant form of PVAc,
with paints and adhesives accounting for about
three-quarters of total consumption. PVAc is also produced
as an intermediate in the manufacture of polyvinyl alcohol
(PVA), polyvinyl butyral, and polyvinyl formal but such
production will not be included here. (See Section 17 of
this report for polyvinyl alcohol production) . The
predominant copolymers are those with n-butyl acr.ylate and
2-ethylhexyl acrylate.
Polyvinyl acetate and its important copolymers are largely
thermoplastic. An unplasticized vinyl acetate homopolymer
film of medium molecular weight is clear and quite hard and
tough at room temperature, but its softening point lies
only several degrees higher. Depending on their chemical
structure, comonomers may have a plasticizing or hardening
effect, thus altering both the softening temperature and
the mechanical properties of the resin considerably. PVAc
and its copolymers generally exhibit good light stability.
-200-
-------
Most vinyl acetate horaopolymers and copolymers are used in
the form of aqueous emulsions. Major applications are in
paints, adhesives, textile treatments, paper coatings and
other uses. Emulsions for paints and for adhesives commonly
have a solid resin content of 55%; most PVAc emulsions for
paper coatings have a solids content of 48% (^8_) . Adhesive
uses include packaging and labeling, construction, and
other miscellaneous uses. The largest single segment in
the latter category is textile treating (including textile
sizing), which involves mostly finishing, fabric coating,
and laminating. Some homopolymers and copolymers come as
solid resins in the form of powders or beads, among which
certain types are especially designed to be redispersed in
water, while others are redispersed in different solvents
(e.g., ethyl acetate in the case of 'a homopolymer).
About 80% of the PVAc (excluding that produced as an
intermediate) is manufactured by emulsion polymerization
usually by batch processes. Polymerization is carried out
in water in the presence of surfactants and a free-radical
initiator, e.g., a suitable peroxide, persulfate, or diazo
compound. PVAc homopolymer and copolymer emulsions are
produced by varying recipes for different end uses. Solid
polyvinyl acetate resins are usually made by suspension
polymerization (similar to emulsion polymerization except
that a suspension agent is used rather than emulsifiers) .
The estimated U.S. demand and growth rates for polyvinyl
acetate are shown below for the period of 1976 to 1981. No
manufacturing capacity data are available for this product.
A 1979 capacity estimate of 999 MM PPY was made based on
1976 sales (69), 6% annual growth, and 0.85 utilization.
-201-
-------
Paints are expected to remain the largest market, but
growth should be modest as the penetration of this market
is quite high. The use of PVAc emulsions (especially
copolymers) in adhesives will grow somewhat faster than
paints. PVAc demand for paper coatings will grow at
similar rates as adhesives, as a result of the replacement
of natural binders. Some sources feel that PVAc
consumption for paper coatings will grow at an average of
at least 6% per year.
ESTIMATED U.S. DEMAND FOR POLYVINYL ACETATE, 19 76-1981*( 69_.)
DEMAND
MILLIONS OF LBS AVERAGE ANNUAL
1976 198'1 GROWTH RATE, (%)
Polyvinyl Acetate (dry base) 713 926-985 5.4-6.7%
Paints 250 319 5
Adhesives 259 347-381 6-8
Paper Coatings 90 115-126
Other Uses 98 125-137 5-7
Exports 16 20-22
Historically, production of PVAc emulsions has been low in
capital costs and therefore many companies have built
facilities to produce it. Today, more spohisticated
product requirements and stricter pollution controls impose
*Includes homopolymers and copolymers with more than 60% vinyl
acetate content.
-202-
-------
demands which cannot be met by many small producers.
However, the producers can be subdivided into three
groups:
o Producers of merchant PVAc emulsions and resins 'for
multiple uses, i.e., merchant suppliers of paint
and/or of emulsions, emulsions and resins for all
other uses;
o Paint companies which produce most or all of their
PVAc emulsions captively;
o Producers of PVAc emulsions primarily for captive
compounding (other than paint production), although
many of these producers occasionally sell emulsions to
other compounders, distributors, or users.
Tables 16-1 and 16-11 list U.S. manufacturers of
polyvinyl acetate.
16.2 POLYVINYL ACETATE BY EMULSION POLYMERIZATION
16.2.1 Process Description
The process described here is a batch emulsion
polymerization followed by batch stripping and resulting
in an emulsion product (latex) (7_0) , (^1). Figure 16-1
is the process schematic. The following process steps
are the principal ones carried out:
o Apply vacuum to reactor to remove residual oxygen,
break vacuum with inert gas, and re-evacuate.
o Charge water, monomers, emulsifiers and modifier.
(Monomers are usually vinyl acetate with small
amounts of acrylic monomers or ethylene.)
-203-
-------
TABLE 16-1.- PRODUCERS OF MERCHANT PVAc EMULSIONS AND RESINS (68)
COMPANY
PLANT LOCATION
AIR PRODUCTS AND CHEMICALS, INC,
Polymer Chemicals Division
Calvert City, Kentucky
AIR PRODUCTS AND CHEMICALS, INC,
Polymer Chemicals Division
City of Industry, CA
Cleveland, Ohio
Elkton, Maryland
South Brunswik, NJ
BORDEN, INC.
Borden Chemical Division
Thermoplastic Products
Bainbridge, New York
Compton, California
Illiopolis, Illinois
Leominster, MA
CELANESE CORPORATION
Celanese Polymer Specialties Co.,
subsidiary Celanese Resins Division
Louisville, Kentucky
Newark, New Jersey
CIBA-GEIGY CORPORATION
Dyestuffs and Chemicals Division
Chas. S. Tanner Company, subsidiary
Greenville, SC
E.I. DU PONT DE NEMOURS & CO., INC.
Plastic Products and Resins Department
Seneca, Illinois
W.R. GRACE & CO.
Industrial Chemicals Group
Dewey and Almy Chemical Division
-204-
Owensboro, Kentucky
South Acton, MA
-------
TABLE 16-1.- PRODUCERS OF MERCHANT PVAc EMULSIONS AND RESINS
(Continued)
COMPANY
PLANT LOCATION
H & N CHEMICAL COMPANY
Totowa, New Jersey
MONSANTO COMPANY
Monsanto Plastics and Resins Company
NATIONAL STARCH AND CHEMICAL CORP.
REICHHOLD CHEMICALS, INC.
Reichhold Polymers Inc., subsidiary
(formerly Standard Brands Chemical
Industries, Inc.)
Springfield, MA
Meredosia, Illinois
Plainfield, New Jersey
Charlotte, NC
Kansas City, Kansas
Morris, Illinois
South San Francisco, CA
Stamford, Connecticut
Cheswold, Delaware
Clifton, New Jersey
STANCHEM, INC.
East Berlin, CT
UNION CARBIDE CORPORATION
Chemicals and Plastics, division
Alsip, Illinois
Garland, Texas
Somerset, New Jersey
South Charleston, WVA
Torrance, California
Tucker, Georgia
UNION OIL COMPANY OF CALIFORNIA
AMSCO Division
-205-
Charlotte, NC
La Mirada, California
Tacoma, Washington
-------
TABLE 16-11.-PRODUCERS OF PVAc EMULSIONS AND RESINS FOR
COMPOUNDING (68 )
COMPANY AND PLANT LOCATION
ADHESIVES
TEXTILE
TREATING
AZS CORPORATION
AZS Chemical Company Division
Atlanta, Georgia
CELANESE CORPORATION
Celanese Resins Division
Bridgeview, Illinois
Charlotte, North Carolina
Newark, California
X
X
X
X
X
X
Wica Chemicals Division
Charlotte, North Carolina
COLLOIDS, INC.
North Chemical Company, Inc., subsidiary
Marietta, Georgia
X
DAN RIVER, INC.
Chemicals Products Division
Danville, Virginia
DIAMOND SHAMROCK CORPORATION
Process Chemicals Division
Cedartown, Georgia
DOBBS-LIFESAVERS, INC.
Beech-Nut, Inc., subsidiary
Canajoharie, New York
(chewing gum)
-206-
-------
TABLE 16-11.-PRODUCERS OF PVAc EMULSIONS AND RESINS FOR
COMPOUNDING (Continued)
TEXTILE
COMPANY AND PLANT LOCATION ADHESIVES TREATING
EMKAY CHEMICAL COMPANY
Elizabeth, New Jersey X
FRANKLIN CHEMICAL COMPANY
Columbus, Ohio X
H.B. FULLER COMPANY
Polymer Division
Atlanta, Georgia . X
St. Bernard, Ohio
GULF OIL CORPORATION
Gulf Oil Chemicals Company, division
Industrial and Specialty Chemicals Div.
Lansdale, Pennsylvania X
KEWANEE INDUSTRIES, INCORPORATED
Milmaster Onyx Group
Refined-Onyx Division
Lyndhurst, New Jersey X
PHILIP MORRIS, INCORPORATED
Polymer Industries, Inc., subsidiary
Greenville, South Carolina X X
Springdale, Connecticut X
-207-
-------
TABLE 16-11.-PRODUCERS OF PVAc EMULSIONS AND RESINS FOR
COMPOUNDING (Continued)
TEXTILE
COMPANY AND PLANT LOCATION ADHESIVES TREATING
QUAKER CHEMICAL CORPORATION
Conshohocken, Pennsylvania X
RAFFI AND SWANSON, INC.
Polymeric Resins Division
Wilmington, Massachusetts X
SCHOLLER BROTHERS, INC.
Elwood, New Jersey . X
A.E. STALEY MANUFACTURING COMPANY
Chemical Specialties Division
Corning, New Jersey X
Lemont, Illinois X X
SYBRON CORPORATION
Jersey State Chemical Company, division
Haledon, New Jersey X X
UNITED MERCHANTS & MANUFACTURERS, INC.
Valchem - Chemical Division
Langley, South Carolina X
-208-
-------
O
>£>
I
VAPOR
RETURN
VACUUM STEAM JET
.V. WATER
EMULSIFIER
CATALYST
MODIFIER
INITIATOR
VINYL ACETATE
MONOMER STORAGE
AFTER
REFLUX CONDENSER
CONDENSER
CW OR STM
POLYMERIZATION
REACTOR
V.AC.
TO RECOVERY
•TO FLARE
TO W.W.
TREATMENT
PRODUCT OUT
P.V.AC.
LATEX STORAGE
FEED
REACT
RECOVERY/FINISH
Figure 16-1.- Polyvinyl acetate - Emulsion polymerization,
-------
o Heat reactor contents to desired reaction
temperature, typically 120-140°F, by circulation of
hot water through reactor jacket.
o Initiate reaction by charging catalyst, activator and
reducing agent, which may be potassium persulfa'te,
ferrous sulfate, and sodium bisulfite, respectively.
Heat of reaction is removed by cold water circulation
through jacket.
o After reaction goes to completion, batch is vacuum
stripped to remove residual monomer and to
concentrate latex. Heating is accomplished again by
circulating hot water through jacket.
o Cool product latex and discharge reactor contents to
storage.
A number of variations to this basic scheme exist, some
of the more significant are:
o Oxygen removal may be accomplished by inert gas
purging rather than application of vacuum.
o Monomers may be added in several increments or may be
metered into reactor while reaction is proceeding
rather than being added as single charge, prior to
initiation.
o Jacket cooling may be augmented by overhead reflux
condenser.
o Stripping may be carried out in separate vessel.
o Residual monomer may be removed by gas sparging (with
air or preferably inert gas) or by steam distillation
or by one of these operations combined with vacuum
stripping.
o It may be advisable or necessary to screen emulsion
upon discharge to receiving vessels for removal of
small amounts of agglomerates.
. -210-
-------
16.2.2 VOC Emissions
All significant emission rates and sources for this
product are shown on Table 16-111. The flowsheet for
this product which includes the emission streams and
their sources is Figure 16-1. No emissions were reported
for product storage. A description of the designated
emission streams follows:
[1] Monomer storage tanks - These streams vent the fixed
roof storage tanks for vinylacetate (VAc) liquid
monomer at ambient conditions. Pure VAc monomer
vapor with air is the only emission unless an inert
blanket gas is used. Normal breathing, filling, and
emptying are the causes of the emissions. This
stream is the second largest significant emission
stream from this process as currently controlled.
[2] Reactor-safety relief valves and rupture discs - This
stream carries materials vented under emergency
conditions from the polymerization reactor.
Relieving this stream occurs very rarely,
approximately one batch per year per plant, and
generally results from reactor jacket and/or reflux-
condenser, cool ing-water failure while the
(exothermic) reaction step is in progress. The
constituents of this stream vary with time but are
primarily VAc monomer vapor (the VOC component),
water vapor, PVAc product (solids), and some other
vaporized liquids from the reactor including
initiator and various emulsifying and other agents
present in the reaction mix. The emission stream is
the smallest emission stream from the process as
currently practiced. Note that mid-batch conditions
are reflected in Table 16-111. The quantity of VOC
-211-
-------
TABLE 16-III.-VOC EMISSIONS FROM POLYVINYL ACETATE LATEX -
EMULSION POLYMERIZATION
Current
Uncontrolled Practice Well Controlled
Stream #/1000# Resin t/1000#Resin #/1000# Resin
[1] Vinyl Acetate 2.02 2.02 0.85
Monomer Storage
[2] Reactor Safety Relief 0.05 0.05 0.01
[3] Reactor Vacuum System 5.37 ' 5.37 0.54
TOTAL 7.44 7.44 1.40
-212-
-------
released varies widely between early and late in the
batch.
[3] Polymerization reactor through overhead vacuum system
- This stream carries non-condensibles vented through
the vacuum-steam jet system. The composition varies
with time; however, upon leaving the jets, the stream
will be composed of steam with some VAc and air.
This stream is the largest source of VOC emissions
from the process, both potentially and in current
practice. The air emitted enters the system by
leakage into the vacuum conditions in the reactor.
16.2.3 Applicable Control Systems
The following control technologies are recommended for
the emission streams described in Section 16.2.2.
Equivalent systems to those recommended here should be
available and would be acceptable alternatives. Actual
flare systems used would be subject to normal good
engineering practice considerations, including maximizing
recovery of both liquid and vapor organics and designing
for pressure levels available.
[1] Monomer storage tanks - A vapor return line to the
tank truck loading area will eliminate all working
loss emissions from tank filling (58% of total
current emissions from these tanks). Conservation
valves will also be required on these tank vents, but
these would be installed for economic reasons and no
pollution control credit is given them (Vapor loss
prevention efficiency of these valves is quite low.)
This minimum abatement system should be quite cost
effective.
-213-
-------
[2] Reactor safety relief system - To plant flare
systems. Flare efficiency of 90% is assumed.
[3] Polymerization reactor through overhead vacuum system
- Exhaust from the vacuum steam jets goes to an
after-condenser cooled by 90°F water, the remaining
non-condensibles are sent to plant flare. Flare
efficiency of 90% is assumed. Insufficient
information was available to calculate an efficiency
for the after-condenser. The wel1-contro 11 ed
emission figure for this stream as shown in Column 2,
Table 16-111 reflects the effect of flaring only.
Use of the after-condenser would lower this emission
figure somewhat and would be quite cost effective.
-214-
-------
SECTION 17
POLYVINYL ALCOHOL
17.1 INDUSTRY DESCRIPTION
Du Pont introduced polyvinyl alcohol (PVAL) commercially
into the U.S. in 1939. PVAL includes all resins made by
the alcoholysis of polyvinylacetate (PVAc). It is
characteristically a white to cream colored powder which
is water soluble. PVAL cannot be prepared by direct
polymerization because vinyl alcohol is an unstable
liquid.
U.S. production of polyvinyl alcohol was 127 MM Ibs in
1978 (2J . Imports from Japan are expected to remain at
the 1976 level of 10 MM despite the fact that excess U.S.
production capacity existed and some was exported.
(Japan is the world's largest producer and' had been
exporting more to the U.S. before U.S. capacity was
increased substantially around 1973.) The projected
growth rate for U.S. consumption for 1976-1981 is 6.7 to
8.6% per year (69).
There are only three major producers of polyvinyl alcohol
in the U.S. These producers are shown on Table 17-1
(68).
-215-
-------
TABLE 17-1.- U.S. PRODUCERS OF POLYVINYL ALCOHOL (68)
Company and Plant Location
Annual Capacity
As Of July 19.77
(Millions of Lbs)
AIR PRODUCTS AND CHEMICALS, INC.
Polymer Chemicals Division
Calvert City, Kentucky
40a
E.I. DU PONT DE NEMOURS & CO., INC,
Plastic Products and Resins Dept.
La Porte, Texas
125b
MONSANTO COMPANY
Monsanto Plastics & Resins Company
Springfield, Massachusetts
Total
45'
210 (160)c
aExpansion to an estimated total of 55 million pounds is
planned.
^portion of capacity (on the order of 25 million pounds per
year for each company) is used to produce PVA1 for captive
polyvinyl
butyral production.
cDatum in parentheses indicates capacity for PVA not
including
that used captively for polyvinyl butyral production.
-216-
-------
17.2 MANUFACTURE OF POLYVINYL ALCOHOL
17.2.1 Process Description
The process described here and shown in Figure 17-1 is
entirely continuous and utilizes solution polymerization
with methanol as the solvent and a hydrolysis reaction
catalyzed by a base (8_) , (T0_) . The molecular weight of
PVAL polymer and the degree of hydrolysis are controlled
by the processing conditions. These characteristics
greatly influence the properties (and uses) of the PVAL
made. The two significant commercial grades of the latter
are partially hydrolyzed (87 to 89%) and completely
hydrolyzed (+99%).
A. Raw Material Storage and Purification
Inhibitor in vinyl acetate monomer (VAM) is removed in a
stripping column, and purified uninhibited VAM is stored
in a daytank. Initiator solution, along with VAM, is
charged into the polymerization section by pump.
B. Polymerization and Hydrolysis
Special properties may be obtained by treatment of the
PVAc during polymerization before hydrolysis, or by
giving special treatment in finishing the PVAL.
Polymerization of vinyl acetate usually is carried out in
two stages at 140°F (60°C). Polymer solution from the
second reactor is collected in a polymer solution surge
tank. An inhibitor is added into the surge tank to
prevent polymerization in the monomer stripping column.
Methanol vapor from the evaporator is used to strip
unconverted monomer in the polymer solution. Additional
liquid methanol is added to the stripping column to
-217-
-------
NC1NERATOH
OO
I
Figure 17-1.- Polyvinyl alcohol - Solution polymerization.
-------
control the viscosity of the polymer solution in the
column. Essentially all the VAM is removed in methanol
solution from the overhead of the column and recycled to
the polymerization reactor section. The polymer product
from the bottom of the monomer stripping column is a 35
wt% PVAc solution in methanol.
This solution is hydrolyzed continuously in two parallel
reactors. The reaction is catalyzed with sodium
hydroxide-methanol solution (charged intermittently from
a feed tank once every 5 minutes). PVAL slurry is
withdrawn continuously from the hydrolysis reactors and
collected in a surge tank. Surge tank slurry is
neutralized with acetic acid from storage.
C. Solvent Separation and Product Drying
Neutralized PVAL slurry is sent to the centrifuge where
PVAL is separated from the mother liquor and washed with
methanol. Mother liquor and washing methanol are
collected in a crude solvent storage tank. Washed PVAL,
usually containing 10 wt% methanol, is dried in a rotary
dryer. Close-looped nitrogen gas is used to. dry PVAL,
and part of the methanol vapor in the nitrogen stream
from the dryer is condensed and sent to the crude solvent
storage tank.
D. Bulk Handling
Dried PVAL from the rotary dryer is transferred to the
storage bins. PVAL product from the storage bins is
loaded in railroad cars or trucks from transportaion to
purchasers.
-219-
-------
E. Solvent and By-product Recovery
Crude solvent from the crude storage tank contains
methanol, methyl acetate, some sodium acetate, and water.
Methanol and methyl acetate are recovered as overhead
from the mixed solvent column and pass into the ester
hydrolyzer where methyl acetate is hydrolyzed to methanol
and acetic acid. A stream of water is added near the top
of the column for hydrolysis and to condense rising
vapor. Essentially all the methyl acetate is hydrolyzed,
and the stream from the bottom of the column is comprised
of methanol, acetic acid and water. Methanol is
separated from the acetic acid and water in the methanol
column, and sent to the methanol storage tank for
recycle. The dilute acetic acid from the bottom of the
methanol column is sent to crude acetic acid storage (not
shown) until needed for the acetic acid extractor and
column.
Sodium acetate is converted to acetic acid by reaction
with sulfuric acid in the acetic acid reactor. The
reaction product is combined with the dilute acetic acid
from the methanol column and extracted wi.th methyl
acetate for acetic acid recovery. Recovered acetic acid
is separated from methyl acetate in an acetic acid
recovery column and sent to storage. Part of the acetic
acid is used to neutralize the hydrolysis reaction
product, and the remainder is sent to a VAM plant or sold
as a by-product. The dilute methyl acetate solution from
the acetic acid column overhead is sent to the methyl
acetate recovery column for recovery. The recovered
methyl acetate is used in the extractor for acetic acid
extraction. The bottom stream from the methyl acetate
recovery column is sent to waste treatment.
-220-
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17.2.2 VOC Emissions
All signifacant emission rates and sources for this
product are shown on Table 17-11. The schematic
flowsheet, Figure 17-1, includes the emission streams'and
their sources. The major emission points are:
[1] Vinyl acetate monomer (VAM) storage tanks - The cause
of emissions is normal breathing and filling
associated with fixed roof storage tanks. The tanks
are normally blanketed with nitrogen. The
composition (weight) is greater than 50% nitrogen the
remainder is principally VAM vapor. The temperature
is ambient.
[2] Methanol storage tank - The.cause of emissions is
normal breathing and filling. The composition is
approximately 25% (by wt) methanol and 75% air
(N2 if the tank is blanketed). The temperature
is ambient.
[3] VAM purification section - This stream vents inerts
from a VAM inhibitor stripper column and associated
surge tank (breathing and filling losses) treating
the VAM before it is charged to the polymerization
reactor. The overall composition is largely inerts
(N^) with less than 1% VOC, typically acetatalde-
hyde and vinyl acetate, in approximately equal
amounts. The temperature is ambient.
[4] VAM recovery column - This column is part of the VAM
recycle system following polymerization of the
monomer. The stream vents inerts from the system.
The composition is primarily nitrogen accompanied by
vinyl acetate and traces of acetaldehyde. Most of
the vinyl acetate is condensed in the overhead
condensing system provided for process reasons. The
temperature is about 95°F.
-221-
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TABLE 17-II.-VOC EMISSIONS FROM POLYVINYL ALCOHOL MANUFACTURE
Current
Uncontrolled Practice Well Controlled
Stream #/1000# Resin #/1000#Resin #/1000# Resin
[1] VAM Storage Tanks 0.35 0.07 0.00+
[2] Methanol Storage
Tanks 0.47 0.07 0.00+
[3] VAM Purification
Section 0.04 0.04 0.00+
[4] VAM Recovery Column 1.67 0.25 0.01
[5] Intermediate Process
Storage Tanks 0.22 0.03 0.00+
[6] Hydroylsis, Solvent
Separation and Product
Drying Sections 48.0 0.27 0.01
[7] Storage for Solvent and
By-product Recovery
Areas 6.07 1.34 0.07
[8] Solid Resin Conveying
Section 0.24 0.24 0.00+
[9] Truck and Hopper Car
Loading and Unloading 0.04 0.04 0.02
[10] Solvent and Distillate
Recovery Section 1.00 0.02 0.00+
TOTAL 58.1 2.37 0.11+
-222-
-------
[5] Intermediate process storage tanks - Causes of the
emissions here are normal breathing and filling of
the fixed roof tanks holding the reacted polymer for
hydrolysis. This also includes such losses from
storage tanks as reaction inhibitor. The stream is
nitrogen, from displacement in the tanks, with 10 to
20% (by wt) methanol as the VOC component. This
intermittent stream is usually at or slightly above
ambient temperature.
[6] Hydrolysis, solvent separation and product drying
sections - These streams exhaust inerts under normal
process conditions. They also include the hydrolysis
area catalyst storage tank breathing and filling
emissions (methanol in nitrogen at 160°F). The
overall uncontrolled stream composition is methanol
and methyl acetate in nitrogen. The resultant stream
temperature is 110 to 115°F. Treatment of this stream
by a water scrubber will knock out most of the VOC.
[7] Storage for solvent and by-product recovery areas -
These storage tanks include the crude solvent tanks
and other intermediate tanks serving the solvent,
distillate, and by-product recovery area. All of the
tanks are atmospheric, fixed-roof tanks at ambient
temperature. Emissions are caused by normal
breathing and filling (the recovery columns operate
continuously). Composition of the exhausts vented
from these tanks are methanol, methyl acetate, and
vinyl acetate vapors and blanket nitrogen in varying
amounts depending on the particular service. The
combined stream is 45% nitrogen, 30% methyl acetate,
20% methanol, and 5% vinyl acetate (weight) .
However, these tanks will generally have refrigerated
exhaust vent condensers with the non-condensibles
combined for further treatment. The composition of
such a composite stream would be approximately 10%
methanol, 10% methyl acetate, 1% vinyl acetate and
-223-
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79% nitrogen (weight ).
[8] Solid resin conveying section - This stream exhausts
inerts and volatile organics during various cycles of
material conveying, classification, and packaging.
Pneumatic conveying is often used and flow rate is
intermittent because different powders are made at
different times. Composition is mostly inerts with
about 2 to 3% (by wt) methanol and methyl acetate in
approximately equal quantities. The streams are
usually ambient vents from powder storage bins or
silos.
[9] Truck and hopper car loading and unloading - This
stream is intermittent, varying with the type of
powder and the amount being handled. Composition is
typically inerts (air or N2> with approximately
1/2% by weight each, of methanol and methyl acetate.
Emissions are caused by displacement and are at
ambient temperature.
[10] Solvent and distillate recovery section - This stream
is the normal overhead process vent from the recovery
towers. The composition is about 50% nitrogen by
weight, with large amounts of methyl and vinyl
acetate and lesser amounts (a few percent) of
methanol and acetaldehyde. The methyl acetate is
from the acetic acid column while the vinyl acetate
comes off the mixed solvent column.
17.2.3 Applicable Control Systems
The following control technologies are recommended for
the emission streams described in Section 17.2.2. VOC
reduction efficiencies given for various controls in this
section are based on calculated values from reporting
resin producers unless otherwise designated.
-224-
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Efficiencies said to be assumed have been estimated.
Reduction efficiency for all streams recommended to be
incinerated is 95% (Pullman Kellogg estimate).
[1] VAM storage tanks - Use refrigerated vent condenser
(20°F refrigerant) and incinerate the non-
condensibles. Condenser reduction efficiency is
approximately 80%.
[2] Methanol storage tank - Use refrigerated vent
condenser (20°F refrigerant) and incinerate the non-
condensibles. Condenser reduction efficiency is
approximately 85%.
[3] VAM purification section - Incineration only is
recommended because of low initial (uncontrolled)
levels of emissions. A refrigerated condenser would
normally be provided on the column here for process
reasons (no VOC emission reduction credit was given
this condenser).
[4] VAM recovery column - Use a refrigerated vent
condenser (20°F refrigerated) on the column overhead
vent and incinerate the non-condensibles. Condenser
reduction efficiency is approximately 85%.
[5] Intermediate process storage tanks - Use separate
vent condensers (70°F water) on these tanks.
Incinerate the non-condensibles from all such vent
condensers. Condenser VOC reduction efficiencies are
approximately 90%.
[6] Hydrolysis, solvent separation and product drying
sections - Send component streams to a single
scrubber using water as a scrubbing agent and
incinerate the overhead from the scrubber. Scrubber
VOC reduction efficiency is approximately 99.6%.
There will also be a vent condenser on the rotary
dryer exhaust for process reasons (No credit is taken
for this reduction) .
-225-
-------
[7] Storage for solvent and by-product recovery areas -
Use a separate refrigerated vent condenser (20°F
refrigerant) on these tanks. Incinerate the non-
condensibles from all such vent condensers. Vent
condenser VOC reduction efficiencies range from
approximatley 70% to 90%. The average condenser
efficiency for the composite stream is 78%.
[8] Solid resin conveying section - This is an
intermittent stream and incineration is not
recommended. Scrubbing with water as a scrubbing
agent should be used. A 98% VOC reduction efficiency
is assumed for such scrubbing.
[9] Truck and hopper car loading and unloading - Because
these are intermittent emissions (during loading
operations) and relatively small, they will not be
incinerated. Filling losses could be substantially
reduced by using vapor return lines to source storage
bins or tanks. Assume 60% VOC reduction for this
means of control.
[10] Solvent and distillate recovery section - Use a
single scrubber with water as the scrubbing agent,
and incinerate the overhead from the scrubber.
Scrubber VOC reduction efficiency is approximately
98%.
-226-
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SECTION 18
STYRENE BUTADIENE LATEX
18.1 INDUSTRY DESCRIPTION
Styrene-butadiene (S/B) latex is a high-styrene-content
resin sold in emulsion form. S/B is a copolymer of
polystyrene (covered in Section 15), one of the principal
commodity thermoplastics. Acrylonitrile-butadiene-styrene
(ABS) and styrene-acrylonitrile (SAN) resins are the other
important copolymers (3_) . The major markets for S/B latex
are carpet and upholstery backing, and paper coating which
account for over 80% of domestic consumption.
The copolymer latexes, also known as S/B emulsions or high
styrene emulsions, usually have a resin content of about
50-65%. The styrene/butadiene ratio varies from 54:46 to
80:20. The bulk are carboxylated (achieved through the use
of such acids as maleic, itaconic, fumaric, acrylic, or
methacrylic). The type and degree of carboxylation have an
effect on adhesion, compound stability during application,
and cross-linking ability. Small amounts of co-monomers
other than styrene and butadiene may be used, depending on
the application.
These styrene-based polymers have a wide range of physical
properties. Generally, they all have excellent resistance
to water and are very good electrical insulators, but their
mechanical properties and resistance to weathering vary
-227-
-------
widely, depending on the exact type of resin. Polystyrene,
especially in the form of foam products, burns when ignited
and to combat this problem, special fire retardant grades
are produced by incorporating additives.
It is believed that all commercial S/B latex is
manufactured by batch emulsion polymerization. A free-
radical polymerization of the copolymers styrene and
butadiene is involved; this reaction may be initiated by
heating or, more effectively, by heating in the presence of
a free-radical initiator (such as benzoyl peroxide) . The
polymerization of styrene-butadiene is highly exothermic,
and the molecular weight and molecular- weight distribution
of the resins depend greatly on the conditions of their
manufacture.
Only S/B latexes with over 45% styrene are considered in
this report. The U.S. production of such S/B latexes was
estimated to be 660 million pounds (solids content) for
1977 (Tl)• Of this amount 595 million pounds are believed
to be carboxylated S/B latexes. Production capacity data
for S/B latexes are not available, but existing total
capacity is believed to be ample for demand until 1982. A
capacity estimate for 1979 of 856 MM pounds/year was made
based on 1977 production, 5% growth and 0.85 utilization.
The processing equipment for S/B latexes also can be used
to make acrylic or polyvinyl acetate emulsions. (These
products are discussed in Sections 5 and 16,
respectively).
S/B latex demand in its major markets is generally expected
to grow at an average of 4 to 5% annually from 1977 to
1982. This would lead to a consumption level of 790-830
million pounds, dry basis, by 1982. The mostly
-228-
-------
modest growth projections for the major styrene-based
polymers reflect the effects of the increasingly
competitive interplay of thermoplastic resins in the
extrusion, molding, and emulsion markets.
Table 18-1 lists U.S. producers of S/B latexes (73) .
The largest four (probably accounting for over 50% of
total production in 1976) are Dow, Reichhold, AMSCO, and
General Tire (71), (74).
18.2 STYRENE-BUTADIENE BY EMULSION POLYMERIZATION
18 .2.1 Process Description
The batch process described consists of emulsion
polymerization followed by stripping. The product is an
emulsion (latex) and Figure 18-1 is a schematic for the
process.
The major process steps are:
o Apply vacuum to reactor to remove residual oxygen,
break vacuum with inert gas, and re-evacuate..
o Charge water, monomers, emulsifier and modifier.
(Monomers are mixtures of styrenes and butadiene with
small amounts of other monomers).
o Heat reactor contents to desired temperature,
140-160°F, by circulation of hot water through
jacket.
o Initiate reaction by charging catalyst, activator and
reducing agent (typically potassium persulfate,
ferrous sulfate, and sodium bisulfite respectively).
Heat of reaction is removed by circulating cold water
in jacket.
-229-
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TABLE 18-1.- U.S. PRODUCERS OF STYRENE-BUTADIENE LATEXESa(73)
COMPANY
PLANT LOCATION
AMERICAN SYNTHETIC RUBBER CORPORATION
Louisville, Kentucky
ATLANTIC RICHFIELD COMPANY
ARCO/Polymers, Inc., subsidiary
Beaver'Valley, PA
BORDEN, INC.
Borden Chemical Division
Thermoplastics Products
Illiopolis, Illinois
Leominster, MA
DART INDUSTRIES INC.
Chemical Group
Plastic Raw Materials Sector
Southwest Latex Corporation
Bayport, Texas
DOW CHEMICAL U.S.A.
Allyn1s Point, CT
Dalton, Georgia
Freeport, Texas
Midland, Michigan
Pittsburg, California
THE FIRESTONE TIRE & RUBBER COMPANY
Firestone Synthetic Rubber and Latex
Company, division
Akron, Ohio
GAF CORPORATION
Chemical Products
Chattanooga, Tennessee
-230-
-------
TABLE 18-1.- U.S.
PRODUCERS OF STYRENE-BUTADIENE LATEXES
(Continued)
COMPANY
PLANT LOCATION
THE GENERAL TIRE & RUBBER COMPANY
Chemical/Plastics Division
Mogadore, Ohio
THE B.F. GOODRICH COMPANY
B.F. Goodrich Chemical Company, division Louisville, Kentucky
THE GOODYEAR TIRE & RUBBER COMPANY
Chemical Division
Akron Ohio
W.R. GRACE & COMPANY
Industrial Chemicals Group
Dewey and Almy Chemical Division
Owensboro, Kentucky
South Acton, MA
REICHHOLD CHEMICALS, INC.
Reighhold Polymers Inc., subsidiary
(formerly Standard Brands Chemical
Industries, Incorporated)
Cheswold, Delaware
Kensington, Georgia
UNION OIL COMPANY OF CALIFORNIA
AMSCO Division
Charlotte, NC
La Mirada, California
UNIROYAL, INC.
Uniroyal Chemical, division Scotts Bluff,
Louisiana
aProducers of solid S/B copolymer resins are not included. For
example, Phillips Petroleum Company produces K-Resin, BDS Polymer,
a clear, impact-grade butadiene-styrene copolymer for packaging, at
Borger, Texas, in a plant with a capacity of 10 million pounds per
year. _231_
-------
VAPOR
RETURN
WATER
EMULSIFIER '
CATALYST!
MODIFIER !
INITIATOR '
JK.O.
DRUM VAC> STM> jET
STM'
STYRENE MONOMER STORAGE
(OR CYLIMDRIC TANKS)
I
M
U)
K>
I
CW OR STM
TO FLARE
[3]
K.O.
DRUM/
CW
POLYMER
REACTOR
BUTADIENE MONOMER STORAGE
(PRESSURE TANKS OR MORTON SPHERES)
DISPOSAL
CW 55°F
REFLUX
COND.'
VAC. STM. JET
STM
t
<=^r=
dr>
>
— 1
^»-
cw
^
(OR VACUUM PUMP)
CW 55°F
K.O.I
DRUM
DISPOSAL
VACUUM
STRIPPER
PRODUCT OUT
S/B LATEX STORAGE
TUNNEL DRYER
.SOLID RESIN
PRODUCT (POWDER)
FEED REACT RECOVERY FINISH
Figure.18-1.- Styrene-butadiene latex using emulsion polymerization.
-------
o After reaction runs to completion, batch is vacuum
stripped in separate vessel to remove residual monomer
and concentrate latex. Heating is accomplished by
circulating hot water through jacket.
A number of variations are possible and some of the more
significant ones are:
o Oxygen removal may be accomplished by inert gas
purging rather than application of vacuum.
o Monomers may be added in several increments or may be
metered into reactor while reaction is proceeding
rather than added as a single batch charge prior to
initiation.
o Stripping may be carried out in.reactor rather than in
separate vessel.
o Catalyst may be added at the start or may be metered
into reactor while reaction is proceeding.
o Residual monomers may be removed by either gas
sparging (with air or inert gas), or steam
distillation, or one of these operations combined with
vacuum stripping.
o The drying section for producing solid resin, (powder)
may or may not be present.
o The reactor and stripping vacuum may be provided by
either vacuum steam jets or vacuum pumps.
18.2.2 VOC Emissions
All significant emission rates and sources for this
product are shown in Table 18-11. The schematic
flowsheet for this product, which includes the emission
streams and their sources, is Figure 18-1. Emissions
were reported to be nil for product storage. A
description of the emission streams follows:
-233-
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TABLE 18-II.-VOC EMISSIONS FROM STYRENE-BUTADIENE LATEX MANUFACTURE
BY EMULSION POLYMERIZATION PROCESS
Stream
[1] Styrene Monomer
Storage
[2] Reactor Safety
Relief
[3] Reactor Reflux
condenser and
vacuum system
[4] Vacuum Stripper
overhead
[5] Solid Resin Dryer
TOTALS
Current
Uncontrolled Practice Well Controlled
#/1000# Resin #/1000#Resin #/1000# Resin
0.31
nil
20.41
nil
0.20
0.31
nil
20.41
nil
' 0.20
0.13
nil
2.04
nil
0.02
20.92
20.92
2.19
-234-
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[1] Styrene monomer storage tanks - This stream vents the
fixed roof storage tanks for styrene monomer at
ambient conditions. Pure styrene vapor in air (or
inert blanket gas if used) compose the gas emitted.
This stream is one of the two primary sources of
styrene emissions within the typical S/B latex (by
emulsion polymerization) plant.
[2] Reactor safety relief valves and rupture discs -
Under emergency conditions, this stream carries
materials vented from the polymerization reactor.
The main emergency conditions causing relief are
reactor jacket and/or reflux condenser cooling water
failures and agitator failures during the reaction.
Steam composition varies with time as the batch
proceeds but is generally butadiene (the most
volatile VOC component), styrene monomer vapor water
vapor, inert gas or air, other vaporized liquids from
minor constituents in the batch, and emulsified S/B
product solids and entrained liquids. Relieving this
stream is extremely rare, only once per 5 to 10 years
per reactor. Because of the great infrequency of
relieving, no average yearly quantity of VOC emitted
is considered.
[3] Polymerization reactor (reflux condenser) - This
stream emits butadiene from the reactor along with
water vapor and non-condensibles. It is the largest
source of VOC emissions from the process (both
potential and as currently practiced). It includes
emissions during the vacuum cycle of the reactor,
through the steam jets, and emissions during the
-235-
-------
pressure cycle of the reactor. Water vapor (or
steam) enters from the reaction mix and from the
steam jets (while under vacuum) and air enters the
system by leakage when under vacuum.
[4] Vacuum stripper (stripper reflux condenser) - This
stream is listed for reference only since no VOC
emissions are reported from it. The stream consists
almost wholly of steam and non-condensibles removed
by vacuum jets. VOC is minute quantities of
styrene.
[5] Tunnel dryer for solid resin - This stream is the
second major source of styrene emissions from the
process, but it will only be present in plants that
make the alternate solid resin product in addition to
the normal emulsion product (estimated to be 1/2 of
the plants) . The stream will consist of the drying
medium (e.g., air or nitrogen), in addition with
styrene vapor.
18 .2.3 Applicable Control Systems
The following control technologies are recommended for
the emission streams described in Section 18.2.2 and in
the schematic flowsheet (Figure 18-1) for this product.
Several systems equivalent to those recommended are
available and might prove preferable after detailed
study. The actual plant flare system provided is subject
to a number of considerations and the guidelines of good
engineering practice. Stream [3], venting butadiene
monomer from the reactor raises the question of flare
versus incinerator, and this should be resolved in a
detailed study. Control by flare was selected for
-236-
-------
economic reasons, but it raises the question of the
flammability of the mixtures. A more detailed study
would determine both flammability and explosive limits.
[1] Styrene monomer storage tanks - A vapor return line
to the tank truck will eliminate all working loss
emissions or 58% of current emissions. Conservation
valves should also be used, but these should be
installed for economic reasons. No pollution
abatement credit is given them.
[2] Reactor safety relief valves and rupture discs -
These are routed to the plant flare system and are
preceded by the knock-out vessel (a flare efficiency
of 90% is assumed).
[3] Polymerization reactor (reflux condenser) - Exhaust
from either vacuum steam jets or vacuum pumps to a
water-cooled after-condenser and knock-out vessel is
sent to plant flare. Flare efficiency of 90% is
assumed. The after-condenser has little direct
effect on VOC emissions but condenses water vapor so
the flared mixture can be burned (within
flammability limits). An alternate route for this
stream (for the portion of the batch cycle when the
reactor is under pressure) by-passes the vacuum
equipment and after-condenser but goes to the
knock-out vessel and then to the flare.
[4] Vacuum stripper reflux condenser - The reflux
condenser can be justified for process reasons but
also serves as (nearly 100%) abatement for VOC
(styrene) emissions.
[5] Tunnel dryer for solid resin - This is routed to the
plant flare system.
-237-
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SECTION 19
UNSATURATED POLYESTER RESINS
19.1 INDUSTRY DESCRIPTION
Unsaturated polyester (UP) resins are esters of diols like
propylene glycol (PG) and the anhydrides of unsaturated and
saturated dicarboxylic acids like maleic (unsaturated) and
phthalic (saturated) acid. UP resins are supplied
dissolved in a vinylic monomer, usually styrene, with which
they are cross-linked during application or cure. They are
usually reinforced with fiberglass or mineral fillers, as
in fiberglass reinforced plastics (FRP).
Unsaturated polyester resins are produced typically by a
batch polyesterification (polycondensation) reaction in a
jacketed, agitated reactor fitted with a water condenser.
A few newer plants produce the resin by a continuous
process. Formulation variables that affect the properties
of unsaturated polyester resins are manipulated with
relative ease, so that their exact composition varies
widely. Composition and amount of VOC emissions will
depend on the exact formulation. As an example, data for
one halogenated specialty resin indicate a high emission of
a halogenated solvent with that formulation and no other.
Unsaturated polyester resins are marketed as liquid resin
solutions in styrene monomer and are used to make FRP
panels, bath fixtures and boat hulls. U.S. production in
-238-
-------
1978 was approximately 1210 MM pounds (2^) and installed
capacity was estimated to be 1600 MM pounds (75) . Based on
1977 data ( 7_6 ) , utilization, K, was 0.71 and with an 8%
average annual growth , 1979 installed capacity was
estimated to be 1735 MM pounds (7_7) , (^78_) . Adequate supply
seems assured for the next five years. Installed capacity
figures currently show an excess capacity, but estimates
for this industry can be misleading because the same
equipment can be used for alkyd resins.
There were more than 20 producing companies in the U.S. in
1977, most of them operating more than one plant. Table
19-1 lists the U.S. manufacturers and gives plant locations
{7_5) . The four largest, Reichhold, W.R. Grace, Koppers,
and Ashland Oil, have 52% of the capacity; the top 12
manufactures have 90% of it.
The most common raw materials for these resins are maleic
anhydride (unsaturated) , phthalic anhydride (saturated),
and propylene glycol (diol) all of which can produce VOC
emissions. The thinning and crosslinking monomer is
styrene (STY), also a potential VOC emission source. Other
saturated and unsaturated acids and higher molecular weight
glycols are substituted in varying amounts to yield
improvements in one property or another. Table 19-11 lists
the most common raw materials and their chemical formulas
and molecular weights.
The common processes used for U.S. unsaturated polyester
manufacture may be classified either as "fusion" or as
"solvent" processes. Fusion processes use inert gas to
remove the water of reaction, and the solvent processes use
-239-
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TABLE 19-1.- U.S. PRODUCERS OF UNSATURATED POLYESTER RESINS (75)
ESTIMATED ANNUAL CAPACITY AS OF
COMPANY AND PLANT LOCATION JANUARY I, 1978 (Millions of Lbs)
ALPHA CHEMICAL CORPORATION 90
Colierville, Tennessee
Kathleen, Florida
Riverside, California
ASHLAND OIL, INCORPORATED 130
Ashland Chemical Co., division
Resins and Plastics Division
Calumet City, Illinois
Los Angeles, California
Newark, New Jersey
Valley Park, Missouri
AZS CORPORATION
AZ Products, Inc., division 10
Eaton Park, Florida
Lancaster Chemical Corp., division
Newark, New Jersey
CARGILL, INCORPORATED 50
Chemical Products Division
Carpentersville, Illinois
Forest Park, Georgia
Lynwood, California
COOK PAINT & VARNISH COMPANY 30
Detroit, Michigan
Milpitas, California
North Kansas City, Missouri
W.R. GRACE & COMPANY 225
Hatco Group
Hatco Polyesters Group
Bartow, Florida
Colton, California
Jacksonville, Arkansas
Linden, New Jersey
Swanton, Ohio
ICI AMERICAS INCORPORATED 25
Specialty Chemicals Division
Wilmington, Delaware
-240-
-------
TABLE 19-I.-U.S. PRODUCERS OF UNSATURATED POLYESTER RESINS
(Continued)
ESTIMATED ANNUAL CAPACITY AS OF
COMPANY AND PLANT LOCATION JANUARY I, 1978 (Millions of Lbs)
INTERPLASTIC CORPORATION 75
Commercial Resins Division
Jackson, Mississippi
Minneapolis, Minnesota
Pryor, Oklahoma
KOPPERS COMPANY, INCORPORATED 130
Organic Materials Group
Coatings and Resins Division
Bridgeville, Pennsylvania
Chicago, Illinoisb
Redwood City, California
Richmond, California
OWENS-CORNING FIBERGLAS CORPORATION 100
Resins and Coatings Division
Anderson, South Carolina
Valparaiso, Indiana
PPG INDUSTRIES, INCORPORATED 80
Coatings and Resins Division
Circleville, Ohio
Houston, Texas
Springdale, Pennsylvania
Torrance, California
REICHHOLD CHEMICALS, INCORPORATED 350
Azusa, California
Detroit, Michigan
Elizabeth, New Jersey
Houston, Texas
Jacksonville, Florida
Morris, Illinois
South San Francisco, California
Tacoma, Washington
H.H. ROBERTSON COMPANY 100
Freeman Chemical Corporation, subsidiary
Chatham, Virginia
Marshall, Texasb
Saukville, Wisconsin
-241-
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TABLE 19-I.-U.S. PRODUCERS OF UNSATURATED POLYESTER RESINS
(Continued)
ESTIMATED ANNUAL CAPACITY AS OF
COMPANY AND PLANT LOCATION JANUARY 1, 1978 (Millions of Lbs)
ROCKWELL INTERNATIONAL CORPORATION 20
Automotive Operations
General Components Group-Plastics Division
Ashtabula, Ohio
ROHM AND HAAS COMPANY 30
Philadelphia, Pennsylvania
Rohm and Haas Tennessee Inc., subsidiary
Knoxville, Tennessee
SCM CORPORATION 20
• SCM Coatings and Resins Division
Chicago, Illinois
Cleveland, Ohio
Huron, Ohio
Reading, Pennsylvania
San Francisco, California
THE SHERWIN-WILLIAMS COMPANY 20
Coatings Group
Cleveland, Ohio
Emeryville, California
THE STANDARD OIL COMPANY (OHIO) 75
Vistron Corporation, subsidiary
Chemicals Department
Silmar Division
Cowington, Kentucky
Hawthorne, California
UNITED STATES STEEL CORPORATION
USS Chemicals, division0
Neville Island, Pennsylvania
-242-
-------
TABLE 19-I.-U.S. PRODUCERS OF UNSATURATED POLYESTER RESINS
(Concluded)
ESTIMATED ANNUAL CAPACITY AS OF
COMPANY AND PLANT LOCATION JANUARY 1, 1978 (Millions of Lbs)
WHITTAKER CORPORATION 20
Whittaker Coatings and Chemicals .
Mol-Rez Division
Minneapolis, Minnesota
OTHERS 20
TOTAL 1,600
aCapacity estimates for this industry have limited value,
since multipurpose reactors for condensation products (e.g.,
alkyd resins, plactizers) can be used. Estimates listed are
only for condensa capacity dedicated to unsaturated polyester
resins production.
^To begin operation in the second half of 1978.
CA plant at Neville Island, Pennsylvania is expected to start
up in 1979 with a capacity of 9 0 million pounds per year. Resin
is produced at the Wallingford, Connecticut plant of American
Cyanamid Company and will continue to be produced there until
the new facility is opened.
-243-
-------
TABLE 19-II.-COMMON RAW MATERIALS FOR UNSATURATED POLYESTER
MANUFACTURE
SYMBOL
FORMULA
MOL. WT,
Maleic anhydride MA
Phthalic anhydride PA
Isophthalic acid IA
Fumaric acid FA
Hydrogenated bisphenol A HBA
C4H2°3
C8H4°3
C8H4°4
C4H4°4
C15H28°2
98.1
148 .1
166.1
116.1
240.4
Tetrahydrophthalic
anhydride THPA
Tetrahydrobromophthalic
anhydride THBA
Propylene glycol PG
Diethylene glycol DG
Styrene STY
C8H8°3
C8H3Br4
C3H8°2
C4H10°5
C8H8
152.1
463.7
76.1
106.1
104.1
Methyl methacrylate
MMA
,H8°2
100.1
-244-
-------
azeotropic distillation. Although both are known to be
produced commercially in the U.S., there is no published
information about relative capacities. Uncontrolled
emissions levels from the fusion process are higher than
from the solvent process because inert gas stripping is
used with it, and VOC are not recovered (solvent recovery
provides some VOC reduction for the solvent process).
Although lower than the fusion process in VOC emissions,
the solvent process does have solvent - usually xylene -
as well as other emissions. The xylene or other solvent
is added in the reactor and removes the water of reaction
by being azeotropically distilled overhead where it is
condensed, decanted, and recycled. A more detailed
discussion of fusion and solvent processes is developed
in the sections that follow (79) . .
19.2 UNSATURATED POLYESTER RESIN MANUFACTURE
19.2.1 Process Description (Fusion and Solvent Processes)
Both the fusion and the solvent processes described below
are batch operations and both can be performed either as
one-step or as two-step processes, virtually without
equipment changes. The emission points are the same for
both processes. Extra equipment used to make a
fire-retardant specialty resin (shown in the dashed box
of the schematic) presumably could be used with either
the fusion or the solvent process. The extra equipment
is bypassed during normal resin production.
-245-
-------
The process described first is a one-step fusion^
process for producing polyester resin made from phthalic
and maleic anhydrides, and propylene glycol, and
dissolved in styrene. Figure 19-1, Unsaturated polyester
resin manufacture by fusion/solvent processes, is a
schematic diagram of the process.
The process has two parts, namely reacting (polyester-
ification) , and thinning. After the polyesterif ication
reactor and its overhead condensation system are purged
with an inert gas, molten maleic and phthalic anhydrides
and propylene glycol are charged into the reactor and the
mixture is agitated and heated. For the fusion process
the overhead condensation system generally consists of a
packed column, a partial and a total condenser and
various tanks, lines, and a caustic scrubber.
Polyesterif ication is carried out at 200°C, and as the
reaction proceeds, byproduct water is evolved. The inert
gas flow is increased to remove this water, and the
temperature at the top of the packed column is kept at
100-120°C by first injecting and then refluxing water
from the partial condenser. As the reaction approaches
completion and the volatiles begin to diminish, the
temperature starts to rise in the reactor and fall in the
column. The inert gas rate is increased further to
remove most of the residual water vapor and unreacted
materials. When the desired acid number is reached in
IA variation uses the same equipment in a two-step process
wherein the saturated anhydride (PA) is added and esterified
first, and cooled slightly, before the MA is added and
esterified. Because reactor temperatures are lowered for the
two-step process, VOC emissions of glycols can be lessened.
-246-
-------
« FOR THE SOLVENT PROCESS THIS . WATER TANK
REPLACED BY DECANTER AND TWO RECEIVERS
I
to
EXTRA EQUIPMENT SPECIALTY RESINS
v>^^-
-------
the reactor, the polymer is cooled, blended with
additives-'-, if any, and pumped to the thinning
vessel. During the reaction and thinning, some of the
reactants are carried out of the reactor with the water
vapor and lost from the product. After most of the
volatiles are condensed the vapor exhaust from the
reactor is scrubbed with caustic or water before it
leaves the process vent. The reactor vent [2] is the
single largest emission source in the process and the
only emission point for the reactor. The solvent
process is similar, basically, to the fusion process.
The major process difference is that a xylene-water
azeotrope is formed in the reactor to remove byproduct
water vapor overhead. This necessitates different
equipment to remove and reuse the solvent. Solvent
process equipment changes in Figure 19-1 are indicated
by asterisk and include a decanter and two receivers in
place of a water tank/K.O. drum for the fusion process.
In the thinning operation, the thinning vessel
containing the required amount of styrene is purged with
inert gas before the partially cooled unsaturated
polyester is added at a rate that keeps the resin
temperature at about 66°C. Overhead vapors from the
thinning operation are controlled by a condenser.
Thinning tank emissions are shown as emission point [3].
They are VOC (mostly STY) carried out in an inert gas
flow.
^Additives may be added in the reactor or in the thinning
vessel. In the thinning vessel resin is checked for color, acid
number, and other physical properties, and additives such as
hydroquinone inhibitor, and filter aids are added.
-248-
-------
Certain specialty resins are made by additional
processing after the reactor but before thinning.
Figure 19-1 shows extra equipment in the dashed box for
making special (fire-retardant) halogenated resins. The
halogenation process has potential VOC emissions from
two pieces of equipment - the halogen-reactor scrubber
vent, and the stripper overhead vent. Both vents are
identified as emission stream [2] and their estimated
emissions are given in the table with the process
reactor emissions, vent [2] . Resin leaving the
specialty equipment flows back to enter the thinning
operations and processing continues as for regular
production resins.
19.2.2 VOC Emissions
All significant emissions for this product are listed in
Table 19-111. Emission points are indicated on the
flowsheet by bracketed numbers. Both the fusion and
solvent processes are represented by the data. The
emissions streams are:
[1] Raw material storage, except monomer - Fixed roof
storage tanks are used throughout the operations in
the existing facilities. Emissions are vapors of
phthalic and maleic anhydrides (PA and MA) and
propylene glycol which result from vapor
displacement (working) and tank breathing. Both PA
and MA are solids at room temperature and both are
stored in hopper bins until needed. As needed, they
are melted at high temperatures^ (290 and 160°F
respectively) in heated, insulated tanks.
At these temperatures PA and MA tend to sublime and
recondense causing solids deposits.
-249-
-------
TABLE 19-1II.- VOC EMISSIONS FROM UNSATURATED POLYESTER RESIN - FUSION OR SOLVENT
PROCESSES
STREAM
UNCONTROLLED CURRENT PRACTICE WELL CONTROLLED COMPOSITION
#/1000# RESIN #/1000# RESIN #/1000# RESIN VOL %
[1] RAW MATERIAL STORAGE
[2] PROCESS
NORMAL
REACTOR
RESIN
SPECIALTY RESIN
I
NJ
(Jl
o
1
[3] THINNING
[4] PRODUCT
[5] MONOMER
AND BLENDING
STORAGE
STORAGE
TOTALS - NORMAL :
- SPECIALTY:
12
22
0
0
0
12
23
.4
.8
.11
.05
.02
.6
.0
0
0
18
0
0
0
0
18
.04
.44
.0
.08
.05
.02
.6
.2
0
0
6
0
0
0
0
6
.0
.05
.3
.02
.05
.01
.1
.43
0
0
0
1
8
1
0
0
1
.97 PA,
.14 MA,
.01 PG
.0
.0
.0
.5
.2
.0
PG
MCI 2,
PG
STY
STY
STY
-------
[2] From the esterification reactor - This stream is the
largest potential emissions source for either the
fusion or solvent process. The flow rate and
composition vary, but the major VOC component is
propylene glycol. The reactor vent carries
unreacted monomers and volatile impurities contained
in the monomers in a stream of inert gas. The
stream of inert gas serves three purposes:
o Assists in removal of water formed in the
reaction and thus pushes the reaction forward;
o Strips residual volatiles;
o Prevents oxygen contamination.
The specialty resin has a vol-atile- solvent process
that greatly increases VOC emissions. Table 19-111
shows the composition of all the streams.
[3] Thinning vessel - This vent discharges styrene vapor
in an inert gas resulting from the purge flow from
the product.
[4] Product storage - Fixed roof tanks are used, and
small amounts of VOC are emitted from working and
breathing losses. Almost all emissions are styrene
vapors.
[5] Monomer storage - Styrene is the predominant monomer
used in thinning, and it is stored in fixed roof
tanks. Due to styrene1s higher vapor pressure (10
mmHg at 87°F) it is a larger potential VOC emission
source, [5], than the other raw material storage
vents, [1].
-------
19 .2.3 Applicable Control Systems
Because emissions from the fusion and solvent processes
are similar and arise from the same process sources, .the
control systems for the two are discussed together. The
following controls are recommended for the streams
described in section 19.2.2 and shown in Figure 19-1.
[1] Emissions from feed material storage (except
monomers) - Fixed roof tanks are satisfactory for
PAf MA and propylene glycol since vapor pressures of
all three materials are low at ambient temperature.
However, both PA and MA have potential housekeeping
problems since they are heated prior to reactor
charging and because they are solids that sublime
and reform at vents. Presently uncontrolled in the
unsaturated polyester industry, these vents are
controlled (12) (13) by aqueous scrubbers with about
95% VOC efficiency in the phthalic and maleic
anhydride producing industries.
[2] Reactor vent emissions - For many unsaturated
polyester manufacturers, the reactor vent is the
largest potential VOC emission source even through
nearly all are controlled by a combination of packed
columns, condensers, and scrubbers with perhaps
90-95% reduction of VOC. Several manufacturers use
thermal incinerators or boilers for tail-gas cleanup
of the reactor vent and may expect 95% additional
VOC removal efficiency. For specialty resins, the
volatile halogenated solvent used may be controlled
by refrigerated (-30°F) condensers on both the
halogen-reactor scrubber vent (ice traps will be
required) and the stripper vent. Demonstrated
control is 90% for normal resins and 65% for
specialty resins.
-252-
-------
[3] Thinning vessel vent emissions - These emissions are
primarily styrene vapor in an inert gas flow.
Present controls vary from none to a cooling-water
condenser. Adequate control would include a
refrigerated brine condenser. Cooling to 40°F,
gives an 80% emissions reduction without moisture
freeze-up. 80% control was assumed.
[4] Product storage - Emissions are almost entirely
styrene vapor. Storage tanks have fixed roofs and
should be equipped with conservation vents.
Emissions are low and no controls are warranted.
[5] Monomer storage - Generally, styrene monomer is
stored in fixed roof tanks with conservation vents.
Presently, most tanks are uncontrolled. Future
tanks will use f1oating-roof tanks and/or
refrigerated-vent condensers. 50% control was
assumed.
-253-
-------
SECTION 20
UREA-FORMALDEHYDE RESINS
20.1 INDUSTRY DESCRIPTION
Urea-formaldehyde resins (UP resins) are aminoplasts, which
are a class of thermosetting resins made by the reaction of
formaldehyde with the amino (-N!^) group of urea or
urea derivatives (14) , (15).
Desirable properties of urea-formaldehyde resins include
heat resistance, solvent and chemical resistance, extreme
surface hardness, and resistance to discoloration on
exposure to heat or light. The largest end uses for
urea-formaldehyde resins are as an adhesive in particle-
board and medium-density fiberboard, for other adhesives,
and in compression-molded plastic parts. Other major
applications include textile and paper treating and
coating, and cross-1inkers for 1 ess-expensive ,
thermosetting, surface coatings. One or more properties of
UF resins may be improved by replacing part or all of the
urea with various urea derivatives. The most widely used
example of this type - melamine - has been the base of a
separate branch of the aminoplast industry. Melamine was
discussed in Section 7.
The reaction of urea and formaldehyde is complex, involving
stepwise condensation and competing reactions. The overall
reaction is analogous to PF resol formation (See Section
10). UF resins are generally made by a batch reaction in an
-254-
-------
aqueous medium. A mixture of low molecular weight UP
polymers with some methylolurea and dimethylolurea is the
normal commercial resin. The resin product can be
shipped as an aqueous syrup (approximately 75% of sales
poundage) or as a powder produced either by impregnating
the syrup on a solid filler, or by spray drying. The
final stage of polymerization (cross linking) takes place
when the resin is cured to its final form, an insoluble
thermoset product.
Production of UF resins was 1122 MM PPY in 1978 (2_) .
Although some disagreement exists, most market experts
expect UF resin sales to decline at a rate of
approximately 1.5% per year during the next five years.
Economic and environmental conc.erns are the primary
reasons given. Particleboard is becoming less profitable
since the resin costs are increasing faster than the
price of the particleboard itself. For this reason some
plants are closing, and industry sources doubt that
additional capacity will be added for quite some time.
Also, urea-formaldehyde is not a permanent bond; under
certain conditions, it breaks down releasing formaldehyde
and the odor is obnoxious. Little production capacity
data for UF resins exist. Production equipment can be
used interchangably to make melamine-formaldehyde
(another aminoplast) or UF resins, and, in many cases,
phenol-formaldehyde resins.
The 1978 production of 1122 MM PPY was combined with 1.5%
anticipated decline and a 0.8 utilization to arrive at a
1979 capacity estimate of 1381.5 MM PPY. Approximately
60 manufacturers are known to produce UF resins in the
United States. These producers are shown in Table 7-1 of
Section 7.
-255-
-------
20.2 UREA FORMALDEHYDE SYRUP AND FILLED POWDER MANUFACTURE
20.2.1 Process Description
The process first described is a simple batch process
used to make a concentrated syrup widely used in the
manufacture of partic1eboard and medium density
fiberboard. Figure 20-1 shows a schematic for the
processes described here (17) , (21).
The following operating steps are carried out:
o Charge 37 or 52% formaldehyde solution, solid prilled
urea, and aqueous sodium hydroxide in correct
proportions to the reactor that is being agitated.
o Heat mixture to desired reaction temperature by
utilizing steam in the jacket, and allow it to reflux
under vacuum at reaction temperature.
o Monitor reaction progress by sampling reactor contents
for viscosity.
o At desired viscosity, cool batch to approximately
140°F, and then concentrate syrup by evaporation of
water under vacuum until desired degree of
concentration is reached (typically 65% wt).
o Adjust batch pH as required and pump out syrup through
filter to syrup holding tank.
At this point the resin syrup can be stored for sale.
Also it can be condentrated further, or processed further
for sale as a solid powder. An unfilled powder- can be
manufactured by spray drying the aqueous syrup, and a
filled powder can be obtained where a solid filler is
impregnated by the syrup and further processed. A batch
process of the latter type is described below:
-256-
-------
VAPOR
RETURN
CAUSTIC
FORMALDEHYDE SOLUTION,
52? e 138°F (FIXED ROOF)
STM
RESIN SYRUP
STORAGE
FORMALDEHYDE
SCRUBBER
TO
INCINERATOR
SYRUP PRODUCT
-»- TO DRUMS
OR TANK CARS
RESIN
IMPREGNATOR1
(MIXEJO
AIR
(MAKE-UP)
PROCESS
SEWER
MOLDING POWDER
' PRODUCT TO FURTHER
SIZE PROCESSING
& PACKAGING
FAN
*AN
FEED
REACT
RECOVERY/FINISH
Figure 20-1.- Urea-formaldehyde resin - Batch process,
-------
o Filler (such as kraft paper) is impregnated with resin
syrup and mixed to wet paste in a mixer.
o Water is removed in tunnel dryer to form dry cake.
o Cake ("popcorn") is pulverized in a Mikro- Pulverizer
to coarse powder.
o Coarse powder is milled in ball mill with additives to
form blended fine powder.
o Fine powder is deaerated and compressed into
corrugated ribbon, which is cut into molding granules
for storage and sale.
20.2.2 VOC Emissions
All significant emission rates and sources for this
product are discussed in this section. Also they are
shown on Table 20-1. Figure 20-1 is the schematic
flowsheet for the product, which includes the emission
streams and their sources. Emissions from the
impregnator and dryer (streams [3] and [4]) were prorated
to reflect an estimated conversion of only 25% of the
resin syrup to molding powder within the total domestic
UF resin industry.
[1] Formaldehyde solution storage tanks - This stream
vents the fixed-roof storage tank for the 52% (wt)
aqueous solution of formaldehyde (37% is also
commonly used) kept at 138°F by internal steam coils.
Normal breathing and filling cause the emissions.
The stream is composed of air drawn in the tank from
the atmosphere, formaldehyde and water vapor from the
stored solution, and some methanol vapor (methanol is
a common constituent of formaldehyde, functioning as
an inhibitor - purchase specification of 0.5 - 1.0
wt% methanol).
-258-
-------
TABLE 20-1.-VOC EMISSIONS FROM UREA-FORMALDEHYDE - BATCH PROCESS
Current
Uncontrolled Practice Well Controlled
Stream #/1000# Resin 1/lMOJResin I/IOOO* Resin
[1] Formaldehyde
Solution Storage
[2] Resin Reactor
[*3] Resin Impregnator
(Mixer)
[*4] Powder Dryer
Totals
0
0
0
11
12
.01
.08
.02
.99
.10
0.01
0.07
0.02
2.83
2.93
0.01
0.00 +
0.00+
0.01
0.02 +
* Prorated to reflect estimated conversion of only 25% of resin
syrup to molding powder (filled and unfilled) within domestic
UF resin industry.
-259-
-------
[2] Overhead emissions from reactor - This stream is a
relatively small potential source of VOC emissions
and includes the fugitive emissions picked up at the
reactor manhole when reactants and various additives
are charged to the reactor. The emission rate and
composition vary over the batch cycle. The average
composition includes large quantities of air;
considerable water vapor evolved by the reaction and
from the formaldehyde solution charged; unreacted
formaldehyde; methanol from the formaldehyde; and
traces of other reactants, additives, catalyst, and
reaction products from the reactor. Most of the VOC
emissions here are exhausted from the overhead vacuum
and condensing system used for each batch.
[3] Resin impregnator (mixer) -.This stream is also a
relatively small potential source of VOC emissions.
The emissions are of a fugitive nature, being
generated by the impregnator or mixer in which the
solid filler is impregnated with resin syrup from the
reactor and then mixed to a wet paste. The equipment
is completely housed; operators also work within the
enclosed space, which has controlled ventilation.
The VOC constituents, formaldehyde and methanol, are
exhausted with large quantities of air and water
vapor. A proration is made in this stream to reflect
only 25% of total syrup resins going to powder.
[4] Dryer for powder - Stream exhausts the tunnel dryer
removing water from filled powdered resin. This is
the largest potential emission source of VOC from the
plant even with the proration that was made to
account for only 25% of total syrup resins going to
powder. The bulk of the stream is air, the drying
medium, with water vapor comprising under 5% (wt) and
the main VOC components, formaldehyde and methanol,
less than 0.1% (wt).
-260-
-------
20.2.3 Applicable Control Systems
The following control technologies are recommended for
the emission streams described in Section 20.2.2 and
shown in the schematic flowsheet for this product.
[1] Formaldehyde solution storage tanks - Use the
pressure equallizing vapor return line to tank cars
or trucks to eliminate working losses from storage
tank filling (approximately 58% of total potential
storage emissions). Conservation valves will also be
required; since they would normally be installed for
economic reasons, no pollution control credit is
given them.
[2] Overhead emissions from reactor - This stream will
include both fugitive emissions picked up at the
reactor manhole and emissions from the overhead
vacuum and reflux system for the reactor. Controls
for the former should utilize sufficient hoods and a
fan for gathering and containment. Both this stream
and emissions from the enclosed overhead
vacuum/reflux system (which will have an
after-condenser) should be sent to the incinerator.
The incinerator will be required especially for
Stream [4], the dryer exhaust. The VOC reduction
efficiency of the incinerator applicable to the total
reactor exhaust is assumed to be 95%.
[3] Resin impregnator (mixer) - Recommended control here
is area pick-up of fugitive emissions and proper
ventilation, much as currently practiced. Additional
hoods or other pick-up aids should be added where
needed. Current practice reflects the benefit of the
overall process change (increased conversion) but the
reduction effect is considerably less here than for
-261-
-------
the dryer (20% reduction from the uncontrolled
estimate). The emissions gathered here should be
sent to the incinerator ([4], dryer exhaust). A VOC
reduction efficiency of 95% on this impregnator
stream is assumed using the incinerator.
[4] Dryer for powder - A very important control
recommended here is already reflected in current
practice figures. It is the process change
increasing conversion of formaldehyde to resin. An
85% reduction in the formaldehyde content of the VOC
stream from uncontrolled emission rates was found to
result (by measurement) from this change and is
probably the maximum reduction possible from this
technique. Further reduction by other means (in
series) are still required for this stream.
Water scrubbing of the dryer exhaust should be used
in conjunction with dryer recycle. This should be
followed by incineration of a purge stream
(approximately 10% by volume). A relativley large
flow of water (approximately 100 GPM) will be needed
in the scrubber but high removal efficiencies,
approximatley 99% for methanol and approximately 85%
for formaldehyde, can be achieved. VOC reduction
efficiency for the incinerator is assumed to be
approximately 95% on the purge stream.
-2G2-
-------
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