United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/3-80-028e
December 1980
Air
Organic Chemical
Manufacturing
Volume 10: Selected
Processes
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EPA-450/3-80-028e
Organic Chemical Manufacturing
Volume 10: Selected Processes
Emission Standards and Engineering Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
December 1980
-------
Ill
This report was furnished to the Environmental Protection Agency by IT
Enviroscience, Inc., 9041 Executive Park Drive, Knoxville, Tennessee 37923,
in fulfillment of Contract No. 68-02-2577. The contents of this report are
reproduced herein as received from IT Enviroscience. The opinions, findings,
and conclusions expressed are those of the authors and not necessarily those
of the Environmental Protection Agency. Mention of trade names or commercial
products is not intended to constitute endorsement or recommendation for use.
Copies of this report are available, as supplies permit, through the Library
Services Office (MD-35), U.S. Environmental Protection Agency, Research Triangle
Park, N.C. 27711, or from National Technical Information Services, 5285
Port Royal Road, Springfield, Virginia 22161.
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V
CONTENTS
Page
INTRODUCTION vii
Product Report Page
1. PROPYLENE OXIDE 1-i
2. ACRYLONITRILE 2-i
3. GLYCERIN AND ITS INTERMEDIATES (ALLYL CHLORIDE,
EPICHLOROHYDRIN, ACROLEIN, AND ALLYL ALCOHOL) 3-i
4. ACRYLIC ACID AND ESTERS 4-i
5. METHYL METHACRYLATE 5-i
6. CHLOROPRENE 6-i
7. BUTADIENE 7-i
8. ACETIC ANHYDRIDE 8-i
9. ACETIC ACID, FORMIC ACID, ETHYL ACETATE,
METHYL ETHYL KETONE 9-i
10. WASTE SULFURIC ACID TREATMENT FOR ACID RECOVERY 10-i
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VI1
INTRODUCTION
A. SOCMI PROGRAM
Concern over widespread violation of the national ambient air quality standard
for ozone (formerly photochemical oxidants) and over the presence of a number
of toxic and potentially toxic chemicals in the atmosphere led the Environ-
mental Protection Agency to initiate standards development programs for the
control of volatile organic compound (VOC) emissions. The program goals were
to reduce emissions through three mechanisms: (1) publication of Control Tech-
niques Guidelines to be used by state and local air pollution control agencies
in developing and revising regulations for existing sources; (2) promulgation
of New Source Performance Standards according to Section lll(b) of the Clean
Air Act; and (3) promulgation, as appropriate, of National Emission Standards
for Hazardous Air Pollutants under Section 112 of the Clean Air Act. Most of
the effort was to center on the development of New Source Performance Stan-
dards .
One program in particular focused on the synthetic organic chemical manufactur-
ing industry (SOCMI), that is, the industry consisting of those facilities
primarily producing basic and intermediate organics from petroleum feedstock
meterials. The potentially broad program scope was reduced by concentrating on
the production of the nearly 400 higher volume, higher volatility chemicals
estimated to account for a great majority of overall industry emissions. EPA
anticipated developing generic regulations, applicable across chemical and
process lines, since it would be practically impossible to develop separate
regulations for 400 chemicals within a reasonable time frame.
To handle the considerable task of gathering, assembling, and analyzing data to
support standards for this diverse and complex industry, EPA solicited the
technical assistance of IT Enviroscience, Inc., of Knoxville, Tennessee (EPA
Contract No. 68-02-2577). IT Enviroscienre was asked to investigate emissions
and emission controls for a wide range of important organic chemicals. Their
efforts focused on the four major chemical plant emission areas: process
vents, storage tanks, fugitive sources, and secondary sources (i.e., liquid,
solid, and aqueous waste treatment facilities that can emit VOC).
121A
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IX
B. REPORTS
To develop reasonable support for regulations, IT Enviroscience gathered data
on about 150 major chemicals and studied in-depth the manufacture of about
40 chemical products and product families. These chemicals were chosen consid-
ering their total VOC emissions from production, the potential toxicity of emis-
sions, and to encompass the significant unit processes and operations used by
the industry. From the in-depth studies and related investigations, IT Enviro-
science prepared 53 individual reports that were assembled into 10 volumes.
These ten volumes are listed below:
Volume 1 : Study Summary
Volume 2 : Process Sources
Volume 3 : Storage, Fugitive, and Secondary Sources
Volume 4 : Combustion Control Devices
Volume 5 : Adsorption, Condensation, and Absorption Devices
Volume 6-10: Selected Processes
This volume is a compilation of individual reports for the following chemical
products: propylene oxide, acrylonitrile, glycerin and its intermediates,
acrylic acid and esters, methyl methacrylate, chloroprene, butadiene, acetic
anhydride, acetic acid, formic acid, ethyl acetate, methyl ethyl ketone, and
sulfuric acid. The reports generally describe processes used to make the
products, VOC emissions from the processes, available emission controls, and
the costs and impacts of those controls (except that abbreviated reports do not
contain control costs and impacts). Information is included on all four emission
areas; however, the emphasis is on process vents. Storage tanks, fugitive sources,
and secondary sources are covered in greater detail in Volume III. The focus of
the reports is on control of new sources rather than on existing sources in
keeping with the main program objective of developing new source performance
standards for the industry. The reports do not outline regulations and are not
intended for that purpose, but they do provide a data base for regulation de-
velopment by EPA.
C. MODEL PLANTS
To facilitate emission control analyses, the reports introduce the concept of a
"model plant" (not in abbreviated reports). A model plant by definition is a
representation of a typical modern process for production of a particular chem-
ical. Because of multiple production routes or wide ranges in typical production
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XI
capacities, several model plants may be presented in one product report.
The model plants can be used to predict emission characteristics of a new
plant. Of course, describing exactly what a new plant will be like is diffi-
cult because variations of established production routes are often practiced by
individual companies. Nonetheless, model plants provide bases for making new-
plant emission estimates (uncontrolled and controlled), for selecting and siz-
ing controls for new plants, and for estimating cost and environmental impacts.
It is stressed that model-plant analyses are geared to new plants and therefore
do not necessarily reflect existing plant situations.
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REPORT 1
PROPYLENE OXIDE
C. A. Peterson
IT Enviroscience
9041 Executive Park Drive
Knoxville, Tennessee 37923
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
December 1980
This report contains certain information which has been extracted from the
Chemical Economics Handbook, Stanford Research Institute. Wherever used, it
has been so noted. The proprietary data rights which reside with Stanford
Research Institute must be recognized with any use of this material.
D82A
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CONTENTS FOR REPORT 1
Page
I. ABBREVIATIONS AND CONVERSION FACTORS 1-1
II. INDUSTRY DESCRIPTION II-l
A. Reason for Selection II-l
B. Propylene Oxide Usage and Growth II-l
C. Domestic Producers II-l
D. References II-6
III. PROCESS DESCRIPTIONS III-l
A. Introduction III-l
B. Chlorohydrination Process III-l
C. Hydroperoxide Processes III-8
D. References 111-31
IV. EMISSIONS IV-1
A. Chlorohydrination Process IV-1
B. Isobutane Hydroperoxide Process IV-4
C. Ethylbenzene Hydroperoxide Process IV-9
D. Other Processes IV-13
E. References IV-15
V. APPLICABLE CONTROL SYSTEMS V-l
A. Chlorohydrination Process V-l
B. Isobutane Hydroperoxide Process V-5
C. Ethylbenzene Hydroperoxide Process V-10
D. Other Processes V-16
E. Fugitive, Storage, and Secondary Emissions V-16
F. References V-17
VI. IMPACT ANALYSIS VI-1
A. Environmental and Energy Impacts VI-1
B. Control Cost Impact VI-1
C. References VI-5
VII. SUMMARY VII-1
A. Process Characteristics VII-1
B. Process Emission Characteristics VII-4
C. Data Base VII-8
D. Industrial Emissions Estimate VII-8
E. References VII-11
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1-v
APPENDICES OF REPORT 1
A. PHYSICAL PROPERTY DATA FOR PROPYLENE OXIDE
B. EXISTING PLANT CONSIDERATIONS
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1-vii
TABLES OF REPORT 1
Number Page
II-l Propylene Oxide Production and Growth II-2
II-2 Propylene Oxide Production Capacity, January 1979 II-3
IV-1 Total Uncontrolled VOC Emissions from the Model Plant for the IV-2
Manufacture of Propylene Oxide Using the Chlorohydrination
Process (68 Gg/yr)
IV-2 Total Uncontrolled VOC Emissions from the Model Plant for the IV-6
Manufacture of Propylene Oxide Using the Isobutane Hydroperoxide
Process (417 Gg/yr)
IV-3 Total Uncontrolled VOC Emissions from the Model Plant for the IV-10
Manufacture of Propylene Oxide Using the Ethylbenzene Hydro-
peroxide Process (181 Gg/yr)
V-l VOC Controlled Emissions for Model Plant Producing Propylene V-2
Oxide by the Chlorohydrination Process (68 Gg/yr)
V-2 Controlled Emissions for Model Plant Producing Propylene Oxide V-6
by the Isobutane Hydroperoxide Process (417 Gg/yr)
V-3 VOC Controlled Emissions for Model Plant Producing Propylene V-ll
Oxide by the Ethylbenzene Hydroperoxide Process (181 Gg/yr)
VI-1 Environmental Impact of Controlled Model Plant Producing VI-2
Propylene Oxide by the Chlorohydrination Process (68 Gg/yr)
VI-2 Environmental Impact of Controlled Model Plant Producing VI-3
Propylene Oxide by the Isobutane Hydroperoxide Process
(417 Gg/yr)
VI-3 Environmental Impact of Controlled Model Plant Producing VI-4
Propylene Oxide by the Ethylbenzene Hydroperoxide Process
(181 Gg/yr)
VII-1 Emission Summary for Model Plant Producing Propylene Oxide by VII-5
the Chlorohydrination Process (68 Gg/yr)
VII-2 Emission Summary for Model Plant Producing Propylene Oxide by VII-7
the Isobutane Hydroperoxide Process (417 Gg/yr)
VII-3 Emission Summary for Model Plant Producing Propylene Oxide by VII-9
the Ethylbenzene Hydroperoxide Process (181 Gg/yr)
B-l Existing Plant for the Manufacture of Propylene Oxide by the B-2
Chlorohydrination Process (154 Gg/yr)
B-2 Existing Plant for the Manufacture of Propylene Oxide by the B-3
Isobutane Hydroperoxide Process (417 Gg/yr)
B-3 Existing Plant for the Manufacture of Propylene Oxide by the B-4
Ethylbenzene Hydroperoxide Process (181 Gg/yr)
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1-ix
FIGURES OF REPORT 1
Number
II-l Locations of Plants Manufacturing Propylene Oxide II-4
III-l Dow/Plaquemine Propylene Oxide Flow Diagram III-4
III-2 Flow Diagram for Model Plant (Uncontrolled) for PO by III-5
Chlorohydrination
III-3 Block Flow Diagram for Oxirane, Bayport, TX, Manufacture of PO 111-10
Via t-Butyl Hydroperoxide
III-4 Model Plant (Uncontrolled) for PO via t-Butyl Hydroperoxide III-ll
III-5 Oxirane, Channelview, TX, Propylene Oxide-Styrene Monomer 111-22
Process Flow Diagram
III-6 Model Plant (Uncontrolled) for PO by EB Hydroperoxide 111-23
A-l Vapor Pressure vs. Temperature A-l
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1-1
ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements used in agency documents in metric
units. Listed below are the International System of Units (SI) abbreviations
and conversion factors for this report.
To Convert From
Pascal (Pa)
Joule (J)
Degree Celsius (°C)
Meter (m)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter/second
(m3/s)
Watt (W)
Meter (m)
Pascal (Pa)
Kilogram (kg)
Joule (J)
To
Atmosphere (760 mm Hg)
British thermal unit (Btu)
Degree Fahrenheit (°F)
Feet (ft)
Cubic feet (ft3)
Barrel (oil) (bbl)
Gallon (U.S. liquid) (gal)
Gallon (U.S. liquid)/min
(gpm)
Horsepower (electric) (hp)
Inch (in.)
Pound-force/inch2 (psi)
Pound-mass (Ib)
Watt-hour (Wh)
Multiply By
9.870 X 10~6
9.480 X 10"4
(°C X 9/5) + 32
3.28
3.531 X 101
6.290
2.643 X 102
1.585 X 104
1.340 X 10~3
3.937 X 101
1.450 X 10~4
2.205
2.778 X 10"4
Standard Conditions
68°F = 20°C
1 atmosphere = 101,325 Pascals
PREFIXES
Prefix
T
G
M
k
m
M
Symbol
tera
giga
mega
kilo
milli
micro
Multiplication
Factor
1012
109
106
103
10"3
- 10"6
Example
1
1
1
1
1
1
Tg =
Gg =
Mg =
km =
mV =
|jg =
1
1
1
1
1
1
X
X
X
X
X
X
10 12 grams
109 grams
10s grams
103 meters
10"3 volt
10~6 gram
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II-l
II. INDUSTRY DESCRIPTION
A. REASON FOR SELECTION
Propylene oxide production was selected for study because preliminary estimates
indicated that production of this material generated a fairly large amount of
air emissions. In addition, the manufacture of propylene oxide is a large and
growing industry.1
Many of the raw materials, intermediates, finished products, by-products, and
organic waste streams handled or generated in the manufacture of propylene
oxide have relatively high vapor pressure (low boiling points); so vents and
other emission sources are likely to discharge significant amounts of organic
vapors to the air unless appropriate emission control techniques are used.
B. PROPYLENE OXIDE USAGE AND GROWTH1'2
Table II-l shows propylene oxide production and growth rates. The predominant
use of propylene oxide is in the manufacture of polyether polyols used for the
manufacture of urethane foams. Use of propylene oxide for manufacture of poly-
ether polyols has varied from 52% to 62% of the total propylene oxide consumed
domestically in the period 1974 to 1978. The other principal uses for propylene
oxide are in the manufacture of propylene glycol (21 to 23%), dipropylene
glycol (2.5 to 2.9%), and glycol ethers (1.2 to 1.5%). Miscellaneous uses
accounted for the balance of the propylene oxide consumed.
Some propylene oxide is sold on the open market to processors that convert it to
other intermediates or finished products, but a large share of the total amount
manufactured is used by the producers to make other intermediates or finished
products. Because of this large internal consumption by integrated producers,
the production data shown in Table II-l are expected to contain some inaccuracies,
but they represent the best numbers available. The current projected growth of
5.3 to 7.1% per year is expected to continue through 1982.
C. DOMESTIC PRODUCERS
As of January 1979 four producers of propylene oxide in the United States were
operating plants at six locations. Table II-2 lists the producers, plant
capacity, and type of process used in the plant. Figure II-l shows the location
of the six domestic plants.1
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II-2
Table II-1. Propylene Oxide
Production and Growth*
Year
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1982 (est)
Production Rate Growth Rate
(Gg/yr) (%/yr)
73 ^
131
140
170
202
225 ^
258 ^
274
322
369
434>
534 ^
535
542
689
795
> 25.2
) 14.0
) 12.9
797^
691
827 \ 3.1
846
927
>
1116 — 12]
L5 5.3—7.1
*See refs 1 and 2.
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II-3
Table II-2. Propylene Oxide Production Capacity, January 1979
Company and
Plant Location
Dow Chemical Co.
Freeport, TX
Dow Chemical Co.
Plaquemine , LA
Oxirane Chemical Co.
Bayport , TX
Oxirane Chemical Co.
Channelview, TX
BASF Wyandotte Corp.
Wyandotte, MI
Olin Corp.
Brandenburg, KY
Total
Nameplate
Capacity
(Gg/yr)
454
154
417b
181
79
59
1344
Process Type
Chlorohydrination
Chlorohydrination
Peroxidation (via isobutane)
Peroxidation (via ethylbenzene)
Chlorohydrination
Chlorohydrination
See ref 1.
Oxirane has announced their intention to boost capacity of the
Bayport plant to 463 Gg/yr in 1980 or 1981, and also intends to
expand capacity to 644 Gg/yr sometime in the early 1980s. See
ref 3.
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11-4
I. The Dow Chemical Co., Freeport, TX
2. The Dow Chemical Co., Plaquemine, LA
3. Oxirane Corp., Channulview, TX
4. Oxirane Corp., Bayport, TX
5. BASF Wyandotte Corp., Wyandotte, MI
6. Olin Corp., Brandenburg, KY
Fig. II-l. Locations of nlants Manufacturing Propylene Oxide
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11-5
Jefferson Chemical Co. (Texaco, Inc.) shut down their plant at Port Neches, TX,
in December 1978.3
The rated capacity for domestic plants manufacturing propylene oxide was 1344 Gg/yr
in January 1979. The current capacity is reported to be 1435 Gg/yr. With the
announced expansions by Oxirane at their Bayport plant, the total production
capacity is expected to reach 1480 Gg/yr in 1980 or 1981 and to rise further to
1662 Gg/yr in the early 1980s.1—3
Reported domestic production for propylene oxide was 927 Gg in 1978, which is
only 69% of the 1979 production capacity. Production in 1982 is estimated to
be in the range of 1116 to 1215 Gg/yr, which amounts to only 75 to 82% of the
announced 1981 production capacity.2'3
With production rates running well below present and announced capacity, it is
considered likely that other older, less efficient, chlorohydrination process
plants will be shut down in the near future. If the two remaining small producers
(Olin and BASF Wyandotte) decide to shut down, the remaining producers will be
Dow Chemical Co. and Oxirane Chemical Co., both giants in the field of propylene
oxide manufacture.
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II-6
D. REFERENCES*
1. S. A. Cogswell, "Propylene Oxide," pp. 690.8021A—69G.8023D in Chemical Economics
Handbook, Stanford Research Institute, Henlo Park, CA (July 1979).
2. S. L. Soder and K. L. Ring with R. E. Davenport, "Propylene," pp. 300.5403J, K,
U, V, W, X in Chemical Economics Handbook, Stanford Research Institute, Menlo Park,
CA (August 1978).
3. "Chementator," Chemical Engineering, p. 83 (Apr. 23, 1979).
*When a reference number is used at the end of a paragraph or on a heading,
it usually refers to the entire paragraph or material under the heading.
When, however, an additional reference is required for only a certain portion
of the paragraph or captioned material, the earlier reference number may not
apply to that particular portion.
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III-l
III. PROCESS DESCRIPTIONS
A. INTRODUCTION
In the United States at present all propylene oxide is manufactured from purified
propylene.1 The two commercial processes currently practiced are the older
chlorohydrination route using chlorine and caustic (or other alkali) and the
newer hydroperoxide route in which a relatively easily oxidized hydrocarbon,
such as isobutane or ethylbenzene, is oxidized to the corresponding hydroperoxide
by air or purified oxygen. The hydroperoxide in turn is used to epoxidize
propylene to propylene oxide. The by-product alcohol from the epoxidation step
is either purified and sold as a coproduct or further processed to a useful
coproduct.*—4
The reactions involved in oxidizing propylene to propylene oxide are exothermic
and produce significant quantities of heat. Because of the temperatures and
reaction conditions at which this heat is released, it is difficult to convert
this exothermic heat energy to useful forms of energy, such as steam, and most
of the heat is rejected to the environment.2—4
B. CHLOROHYDRINATION PROCESS1—5
1. General Discussion
This process route uses a two-step reaction sequence in which chlorine is first
used in an aqueous solution to chlorohydrinate propylene to propylene chloro-
hydrin. A simplified overall equation for this first reaction is as follows:
CH2C1-CHOH-CH3
C12 + H20 + CH2=CH-CH3 >• HC1 + and
CH2OH-CHC1-CH3
(isomers)
Conditions that promote high yields and minimum amounts of by-products are low
pH, dilute solution, and relatively low reaction temperature.
The second reaction step is the reaction of the chlorohydrin isomers with an
alkali [usually NaOH or Ca(OH)2] to convert the chlorohydrins to propylene
oxide. A simplified overall equation for this second reaction is as follows:
-------
III-2
CH2C1-CHOH-CH3
and + NaOH *• NaCl + H20 + CH2-CH-CH3
CH2OH-CHC1-CH3 0
(isomers)
This reaction takes place at elevated temperature under slight pressure. Reaction
conditions are selected so that the propylene oxide is vaporized as it is generated,
and the propylene oxide is then condensed as a crude product stream to separate the
oxide from the large wastewater stream containing salt and traces of organic waste
material.
The principal by-products generated in this two-step reaction sequence are dichloro-
propane (DCP) and dichloroisopropyl ether (DCIPE). Other miscellaneous organic com-
pounds are generated in minor quantities. These miscellaneous materials are
separated during the product purification steps and are discarded as waste streams.
Industry data indicate that with the chlorohydrin process about 0.9 g of propylene
is consumed per gram of propylene oxide produced.1'5
The chlorohydrin process is the older process route for the manufacture of
propylene oxide and consumes large quantities of chlorine and caustic (or other
alkali). Since both chlorine and alkali require large amounts of energy to
manufacture, the current pressure of high and rising prices for energy make it
unlikely that this process route will be the route selected when new manufacturing
plants are constructed.
In the recent past old production plants previously used for the manufacture of
ethylene oxide by the chlorohydrin route have been converted to manufacture of
propylene oxide by this same reaction mechanism. These plants became available
when the production of ethylene oxide was switched to new, direct oxidation
plants in which air or oxygen was used to convert ethylene to ethylene oxide.
Since almost all the old plants have now either been converted for manufacture of
propylene oxide or shut down and dismantled, this route for expansion of propylene
oxide capacity is no longer readily available. Some capacity expansion could
still be made by modifying or debottlenecking these older chlorohydrination
plants, but it is very unlikely that new plants will be built for the old
chlorohydrination process.
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III-3
2. Process Technology
Figure III-l is a copy of the block flowsheet furnished by The Dow Chemical
Company for the chlorohyrination route to propylene oxide.6 The model plant*
flowsheet for the chlorohydrination process for propylene oxide given in Fig. III-2,
pp. 1 and 2, is based on the Dow flowsheet, on the process description given in
the nonconfidential trip report,6 on the process descriptions given in the
three SRI Process Economics Program Reports,2—4 and on physical property data.
The process shown probably is not an exact representation of the chlorohydrination
process as practiced by any of the manufacturers of propylene oxide by this route
but is believed to be sufficiently representative to be useful for air emission
purposes.
In the process shown on Fig. III-2 chlorine vapor (1) is mixed into and reacts
with chilled process water (3) to form hydrochloric acid and hypochlorous acid.
This large aqueous stream (4) of dilute hypochlorous acid then contacts propylene
vapor (2 + 5) in chlorohydrination reactors, where the propylene is converted
to the two isomeric forms of propylene chlorohydrin dissolved in water (8).
The unreacted propylene (5) is recycled to the chlorohydrin reactors, while a
bleed stream (6) of propylene containing residual propane and other inert gases
is fed to a vent gas scrubber. Dilute caustic (7) is used as the absorption
fluid in the vent gas scrubber to absorb and remove any traces of hydrochloric
acid vapor or chlorine gas from the vent gas stream (Aj). The wastewater (Kj)
from the scrubber is discharged to the plant wastewater system.
The dilute chlorohydrin solution (8) is mixed with an alkali solution (9) or
slurry, and fed to a saponification column, where the alkali reacts with the
propylene chlorohydrin to form salt and propylene oxide. Temperature and
pressure inside the saponification column are controlled so that the propylene
oxide is vaporized and stripped out of the aqueous reaction mixture. The
wastewater from the saponifier (K2) contains salt and some residual organic
materials. This wastewater stream (K2) is discharged to the plant wastewater
system. The vent gas stream from the saponifier column is labeled A2.
The crude propylene oxide from the saponifier is condensed (10) and fed to the
propylene oxide stripping column. This stripping column separates the propylene
oxide and other low-boiling components from the higher boiling chlorinated
*See p 1-2 for a discussion of model plants.
-------
PS* 15-
HC = r
cit •= r
c
•2, 4*
(52 T/y
!.S2 T/y
>
Chlorohydrin and
Oxide reactors
!
tSt 15
HC » 0.
C
-1, 3 PS# 15-11T
" T/V HC ' 1'° T/Y PS» 1S-14T to 19t
1 i HC = 0.30 T/y
j\ /C^^* 15"6T 6 7T PSt 15"12T *< 13X i
J \_JttC - 0.044 T/y HC - 0.436 T/y
i . n
PS# is-er to IOT
HC - 16.42 T/y
t
^To Pr°Pylene
glycol process
Crude PO strea» ^ D.,,,,Scatlon «>, PDC, DCIPE ^ Stora^e
Wastewater
to WWT
PS# 15-5
Waste HC - 1.0 T/y , .
liauid 1 Emission Control Devices**
streams T A. Vent scrubber
x"^v B. Vent scrubber
( D ] c. Refrigerated vapor condenser and scrubber
^*f/ D. Combination venturi and scrubber
** See Appendix B for more detailed description
Thermal
. .f» oxidizer
M
M
I
•See Appendix A for point source (PS) emission data as reported on
Louisiana Emission Inventory Questionnaire.
Fig. III-l. Dow/Plaquemine Propylene Oxide Flow Diagram
-------
«. Px.fn.Mte
x 2.,
O*.
Fig. III-2. Flow Diagram for Model Plant (Uncontrolled) for PO by Chlorohydrination
(page 1 of 2)
-------
Fig. III-2. (Continued)
(page 2 of 2)
-------
III-7
organic by-products. The vent gas stream from this column is labeled A3. The
overhead stream (11) from this column is fed to the lights stripping columns
for separation of the low-boiling impurities (K3) from the main product stream
(13). The vent gas stream from the lights stripping column is labeled A4.
The main-product stream (13) from the bottom of the lights stripping column may
be sold or used (14) for manufacture of other products, or it may be refined
further by being sent (15) to a final distillation column, where high-purity
product (17) is separated from residual trace impurities (16). The vent gas
stream from this final distillation column is labeled A5.
The bottoms stream (16) from the final distillation column is returned to the
propylene oxide stripping column for recovery of residual propylene oxide.
The bottoms stream (12) from the propylene oxide stripping column is sent to a
decanter for removal of residual water (K3), which is sent to the plant waste-
water treatment system. The organic layer (18) from the decanter is sent to
the DCP distillation column, where dichloropropane (20) is separated from the
by-product stream. Any residual water that goes overhead (19) with the dichloro-
propane (DCP) is separated and recycled to the decanter tank. The vent gas
stream from the DCP distillation column is labeled A6.
The bottoms stream (21) from the DCP distillation column is fed to the DCIPE
stripping column, where dichloroisopropyl ether is distilled overhead to yield
a stream (24) of purified dichloroisopropyl ether for sale or for internal
plant use. The bottoms stream (K4) from this still is sent to waste disposal.
The vent gas stream from this stripping column is labeled A7.
3. Process Variations
The C. E. Lummus firm has developed a variation of the chlorohydrin process in
which the chlorohydrination and saponification reactions are integrated with elec-
trolytic generation of chlorine and caustic from brine by use of t-butyl alcohol
converted to t-butyl hypochlorite. The brine resulting from the saponification
reaction is recycled to the electrolytic cells for regeneration of the chlorine
and caustic consumed in the chlorohydrination and saponification steps. Lummus is
offering process licenses and/or construction of production plants by this process.
A demonstration plant of unspecified capacity is being built at Bloomfield, NJ.7
-------
III-8
Other variations of the electrolytic chlorohydrin process for production of propylene
oxide are discussed in SRI reports, but commercial plants using these techniques
have not been built in the United States.3'4
C. HYDROPEROXIDE PROCESSES1—5
1. General Discussion
Two versions of the hydroperoxide process for the manufacture of propylene oxide
are practiced domestically by the Oxirane Corporation. Oxirane at Bayport, TX,
uses isobutane to form _t-butyl hydroperoxide for epoxidation of propylene to propyl-
ene oxide. The coproduct formed by using isobutane to make hydroperoxide is t-butyl
alcohol. Oxirane at Channelview, TX, uses ethylbenzene to form ethylbenzene hydro-
peroxide for expoxidation of propylene to propylene oxide. The coproduct formed by
using ethylbenzene as the hydroperoxide is or-methyl benzyl alcohol. This alcohol,
in turn, is converted to styrene monomer by a dehydration reaction, and the resultant
styrene coproduct is purified and sold.1'5
2. Isobutane Hydroperoxidation Process
a. Process Chemistry In an adjacent refinery, isobutane is produced from a mixed
stream of butane isomers. The mixed butane isomer stream is purified and
isomerized to convert the n-butane in the mixed stream to isobutane. This
conversion is represented by a simplified equation as follows:
CH3-CH2-CH2-CH3 * CH3-CH-CH3
CH3
In the hydroperoxide process the isobutane feedstock is oxidized to t-butyl
hydroperoxide in a liquid-phase oxidation process. Some of the isobutane is
oxidized to t-butyl alcohol in this oxidation step. This oxidation process is
represented by two simplified equations:
(CH3)3CH + 02 > (CH3)3C-0-OH
2(CH3)3CH + 02 > 2(CH3)3COH
Depending on reaction conditions the yields of hydroperoxide and alcohol can be
shifted, but normal yields of hydroperoxide and alcohol are about equal.
-------
III-9
The next step in the reaction sequence is the epoxidation of propylene with
t:-butyl hydroperoxide to yield propylene oxide and ^-butyl alcohol. A catalyst
is used to promote this epoxidation reaction. The following simplified equation
represents this epoxidation step:
(CH3)3-C-0-OH + CH2=CH-CH3 > CH2-CH-GH3 + (CH3)3COH
0
Separation and purification of the products after this reaction sequence yield
commercially pure grades of propylene oxide and t-butyl alcohol.
Impurities generated in the process include carbonyl compounds, glycols, ethers,
and other miscellaneous organic materials and tars. These impurities must be
removed from the product streams and treated by suitable waste disposal techniques.
Process Technology Figure III-3 is a copy of the block flowsheet for the Oxirane,
Bayport, propylene oxide—t-butyl alcohol process as furnished by the Oxirane Corp.8
Oxirane also includes manufacture of propylene glycol, dipropylene glycol, and iso-
butylene within the boundary limits of this manufacturing facility.9 Based on this
flowsheet and the accompanying nonconfidential listing of emissions, waste discharges,
and control devices given in the Oxirane letter,8 as well as on the process descrip-
tions given in the three SRI Process Economics Program Reports,2—4 and on physical
property data, a model-plant flowsheet has been constructed for this process. The
flowsheet is shown in Fig. III-4, pp. 1—4. The process shown probably is not
an exact representation of the peroxidation process as practiced by Oxirane at
their Bayport plant, but is believed to be sufficiently representative to be useful
for air emission purposes.
In this process liquid isobutane (1 and 8), along with oxygen gas (2), is fed
as separate streams into oxidation reactors, where the isobutane is oxidized to
t-butylhydroperoxide and t-butyl alcohol (T3A). Residual (inert) gas and
volatile organic compounds (VOC) from the reactors (3) pass through a caustic
scrubber, where carbonyl compounds are stripped from the gas. After caustic
scrubbing, the gas stream (4) passes through a TEA scrubber, where chilled
t-butyl alcohol is used to absorb organic vapors from the gas stream. After
scrubbing, the vent gases are discharged as vent stream Aj.
-------
I
I-1
O
lo Dlipon
•K-Nm V«»l lo FU><
Fig. III-3. Block Flow Diagram for Oxirane, Bayport, TX, Manufacture of PO Via t^Butyl Hydroperoxide
-------
. ' _ Srfiprc.it.
, PASS 3.
ftfO
Fig. III-4. Model Plant (Uncontrolled) for PO via t^Butyl Hydroperoxide
(Page 1 of 4)
-------
Fig. III-4. (Continued)
(Page 2 of 4}
-------
terror. Gj.ye.ot.
Fig. III-4. (Continued)
(Page 3 of 4)
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M
H
h-l
Fig. III-4. (Continued)
•(Page 4 of 4)
-------
111-15
The liquid stream (5) from the oxidation reactors contains t-butylhydroperoxide,
t-butyl alcohol, unreacted isobutane, and various impurities. This stream (5)
is sent to an isobutane stripping column, where the unreacted isobutane (8) is
recovered and recycled to the oxidation reactors. The vent gas (K!> from the
isobutane stripping column is rich in isobutane and other flammable hydrocarbon
vapors. This vent gas is injected into the plant fuel gas manifold for use as
fuel. The bottoms stream (7) from the isobutane stripping column contains the
crude mixture of t-butylhydroperoxide and t-butyl alcohol, and is stored in an
intermediate hold tank.
From the intermediate hold tank a side stream (9) of the crude mixture is sent
to a TBA stripping column, where process water is added and an azeotropic
mixture of t-butyl alcohol and water (11) is separated overhead. Vent gas (A2)
from this column contains nitrogen, water vapor, t-butyl alcohol vapor, and
other VOC. The bottoms stream (10) from this column consists of a mixture of
t:-butylhydroperoxide (70%) in water (30%), along with some residual impurities.
This bottoms stream (10) is stored for sale or for in-plant use.
The main-product stream (12) from the intermediate hold tank is heated and fed
to the high-pressure epoxidation reactors, along with the feed streams (13 and
23) of propylene and a small feed stream (14) of catalyst in propylene glycol
"slops."* A minor process vent gas stream (A3) discharges from the catalyst
mix tank. The reaction mixture (15) is discharged to an intermediate-pressure
flash chamber. Some of the unreacted propylene (16) exits the flash chamber as
vapor and is fed as a vapor stream to the upper section of the propylene stripping
column. The liquid stream (17) from the flash chamber is fed to the lower
section of the propylene stripping column.
The propylene stripping column removes the unreacted propylene (and other
low-boiling-point hydrocarbons) from the main-product stream. The vent gas
(20) from this column is fed as a vapor stream to the upper section of the
lights stripping column, while the overhead condensate (19) is fed as a liquid
to the lower section of the lights stripping column. The bottoms stream (18)
from the propylene stripping column contains propylene oxide, t-butyl alcohol,
and reaction residues and impurities.
*In this process the manufacturer uses the term slop to define a crude mixture of
propylene glycol contaminated predominantly with water and dipropylene glycoi.
-------
111-16
The lights stripping column separates the low-boiling-point hydrocarbons and
other impurities from the recycle propylene stream. The vent gas (K3) from the
column contains highly flammable hydrocarbons such as methane, ethane, ethylene,
etc., and is injected into the plant fuel gas manifold. The overhead condensate
stream (K2) also contains a portion of these flammable hydrocarbons, as well as
some propylene. This stream can either be collected and stored under pressure
for use as a liquid fuel or be vaporized and fed into the plant fuel gas manifold.
The bottoms stream (21) from this column is rich in propylene, propane, and
some other higher boiling point hydrocarbons. This bottoms stream (21) is fed
to the propylene purification column.
The propylene purification column is used to separate the recycle propylene
stream (23) from the higher boiling point components. The vent gas (22) from
this column is injected as a vapor into the upper section of the lights stripping
column for recovery of the propylene contained in the vapor. The bottoms
stream (K4) from the propylene purification column contains propane and other
higher boiling point hydrocarbons. This material can either be collected and
stored under pressure for use as a liquid fuel or be vaporized and injected
into the plant fuel gas manifold.
The crude t-butyl alcohol stream (11) from the TEA stripping column is combined
with the main-product stream (18) from the bottom of the propylene stripping
column. This combined stream (24) is held in the PO-TBA feed tank for delivery
to the propylene oxide (PO) stripping column. The PO stripping column separates
the crude propylene oxide (25) from the t-butyl alcohol stream (26) containing
the process residues. The vent gas stream from this PO stripping column is
labeled A4.
The bottoms stream (26) from the PO stripping column is fed to a crude TEA
recovery column. In this column crude t-butyl alcohol is separated as an
overhead water-alcohol azeotrope stream (27) from the bottoms residue stream
(K5) containing the catalyst residues and some high-boiling-point organic
compounds.
The crude t-butyl alcohol (27) is held in a crude TEA hold tank. One portion
of this t-butyl alcohol is fed as a stream (28) to the crude TEA feed tank for
-------
111-17
use as the scrubbing fluid in the TEA vent scrubber. Another portion is fed as
a stream (30) to the TEA wash-decant system, along with a stream (29) of recycled
isobutane. This mixed stream enters the TEA wash-decant system, where it is
contacted with a dilute caustic solution for reaction with and removal of
carbonyl impurities from the isobutane-t-butyl alcohol mixture. After separation,
the water layer (31) containing the sodium salts and dissolved carbonyl compounds
is sent to the wastewater stripper, while the organic layer (32) is sent to the
isobutane stripping column. In the isobutane stripping column the isobutane
(33) is separated from the mixture and recycled to the isobutane feed tank.
The t-butyl alcohol bottoms stream (34) is fed to the TEA refining column,
where purified t-butyl alcohol (35) is recovered overhead and stored for shipping
as one of the principal products of this facility. The bottoms stream (K6)
from the TEA refining column contains residual high-boiling-point impurities
and can be collected and treated for use as a liquid fuel. The vent gases from
both columns are collected as a single vent stream (K7) and injected into the
plant fuel gas manifold.
A third portion of the crude £-butyl alcohol (36) is sent to a crude TEA feed
tank, where it is combined with a recycle TEA stream (42) as a feed stream to
the dehydration reactors. In the dehydration reactors the t-butyl alcohol is
converted to a crude mixture of water, isobutylene, and residual t.-butyl alcohol.
This reaction mixture (37) is treated with dilute caustic in a wash-decant
system for removal of carbonyl impurities and unreacted t-butyl alcohol. The
aqueous stream (39) is sent to a wastewater stripping column, where an azeotropic
mixture of residual t-butyl alcohol and water (42) is recovered and recycled to
the crude TEA feed tank. The vent gas stream from the wastewater stripping
column is labeled A7. The stripped wastewater stream (K10) is sent to the
plant wastewater treatment facility. The isobutylene purification column
receives the organic layer (38) from the wash-decant system and recovers purified
isobutylene (40) from this organic stream. The bottoms stream (41) from the
isobutylene purification column contains so.ne unreacted t:-butyl alcohol and
minor impurities. The bottoms stream (41) is recycled to the wash-decant
system for extraction of these materials. The vent gas from the isobutylene
purification column, along with any vent gas from the wash-decant system, is
combined as vent gas stream Kg and sent to the plant fuel gas manifold.
-------
111-18
The crude propylene oxide (25) from the PO stripping column is held in the
crude PO feed tank. The main stream (43) from this tank is blended with the
solvent stream (44) from the solvent scrubber and held in the PO solvent hold
tank. This combined stream (46) of mixed PO and solvent is fed to the solvent-FO
separation column, where a purified propylene oxide stream (48) is separated
from the solvent stream (47) containing the higher boiling point impurities.
The vent gas from the separation column is combined with other vent gas streams
going to the solvent scrubber. The propylene oxide stream (48) from the separation
column is given a final purification step in the PO finishing column to separate
high-purity finished propylene oxide from the higher boiling point bottoms
stream (49). Stream 49 is recycled to the solvent-PO separation column. The
vent gas from the PO finishing column is combined with other vent gas streams
going to the solvent scrubber. The high-purity finished propylene oxide is
stored prior to shipment. The solvent-rich stream (47) from the solvent-PO
separation column is sent to a solvent recovery column for separation of purified
solvent (50) from the residue stream (Kn). The vent stream from the solvent
recovery column is labeled A9. The purified solvent stream is chilled and used
as scrubber liquid in the solvent scrubber, where it strips most of the propylene
oxide out of the combined vent gas stream. The vent gas discharged from the
solvent scrubber is labeled A8.
An aqueous layer (51.) containing some dissolved propylene oxide is drained
from the bottom of the PO-solvent hold tank. This stream is combined with a
side stream (51 ) of crude propylene oxide from the crude PO feed tank. This
Cl
combined stream (52) is mixed with process water, heated, and fed to the hydration
reactors for conversion of the propylene oxide to a mixture of propylene glycol,
dipropylene glycol, and miscellaneous glycolic residues dissolved in excess
water. The reaction mixture (54) is fed from a dilute glycol hold tank to the
water stripping column. In this column the wastewater stream (K12) is taken
off overhead and sent to the plant wastewater treatment system. The vent gas
stream from this column is labeled A10. Th
-------
111-19
liquid in the catalyst mix tank. After separation, the waste caustic-salt
solution (K13) is sent to the plant waste treatment facilities.
The main organic stream (57) from the glycol caustic treatment system is sent
to a propylene glycol column, where the main-product stream of propylene glycol
is distilled under vacuum, with steam vacuum jets and condensers used as the
vacuum source. The bottoms stream (58) from the propylene glycol column is
distilled under vacuum (steam jets and condensers) in the dipropylene glycol
column to yield a secondary-product stream of dipropylene glycol and a bottoms
waste stream (K15) of glycolic residues. The vent gases from the vacuum steam
jets on these two columns are combined and discharged as vent gas stream AH.
The condensate from the jet condensers is combined and discharged as the waste-
water stream (K14).
The rich wastewater streams (6) from the caustic scrubber and (31) from the TBA
wash-decant system are collected in the rich wastewater collection tank and fed
as a combined stream (59) to the wastewater stripping column. In this column
crude acetone is stripped out of the wastewater and stored for sale or in-plant
use. The vent gas stream from this column is labeled A12- The stripped waste-
water stream (K16) from this column is combined with the other wastewater streams
' K12, and K14), stored, and sent to the plant wastewater treatment system.
Vent gas streams rich in flammable hydrocarbons (Klf K3, K7, and K9) are collected
in the plant fuel gas header, compressed as required, and fed to the plant
process furnaces and other fuel gas users for combustion. The resultant flue
gases are discharged to the atmosphere.
Process waste streams rich in flammable liquids with high heating values (K2,
K4, K5/ K6, and Ktl) are collected, stored, treated as required, and fed to the
plant process furnaces and other liquid fuel consumers for combustion. Since
these waste liquid (fuel) streams do not contain troublesome components and
burn cleanly, the flue gases from combustion of these materials in the process
furnaces is vented to the atmosphere as flue gas.
The glycolic waste stream (K15) is also collected, stored, and fed to the
process furnace as a fuel stream. Glycolic wastes have a relatively low heating
-------
111-20
value and do not burn well by themselves, but they also burn cleanly when
combusted in a high-temperature fire chamber in the presence of other high-heating-
value fuels, permitting the resultant flue gases to be discharged to the atmosphere.
3. Ethylbenzene Hydroperoxidation Process
a. Process Chemistry In the first major process step purified ethylbenzene is
reacted with oxygen from the air to form a dilute solution of ethylbenzene
hydroperoxide in unreacted ethylbenzene. This conversion is represented by the
following simplified equation:
CH3-CH2 + 02
In the second major process step the ethylbenzene hydroperoxide solution is
concentrated by some of the residual ethylbenzene being evaporated, and this
concentrated solution is then used to epoxidize propylene to propylene oxide in
the presence of an epoxidation promotion catalyst. A simplified equation
representing this epoxidation step is as follows:
CH3-CHOOH + CH2=CH-CH3 S> CH2-CH-CH3 +
0
The principal coproduct of this epoxidation reaction is ct-methyl benzyl alcohol.
Some acetophenone is also produced as a by-product in this reaction sequence,
along with minor amounts of various other oxidation products, usually acidic in
nature.
After the propylene is epoxidized to propylene oxide, distillation techniques
are used to separate unreacted propylene (for recycle), propylene oxide product,
and a mixed stream of unreacted ethylbenzene, or-methyl benzyl alcohol, and
acetophenone. A caustic wash is used to remove.acidic impurities, and the
mixed stream is further distilled to remove the ethylbenzene from the mixture
of a-methyl benzyl alcohol and acetophenone. Purified ethylbenzene is recycled
to the ethylbenzene hydroperoxide step in the process.
-------
111-21
The third major process step is the dehydration of the Of-raethyl benzyl alcohol
to styrene monomer in the presence of a dehydration catalyst. The acetophenone
passes through this reaction step without being reacted. A simplified equation
for this dehydration reaction is as follows.-
CH3-CHOH >• CH2=CH + H20
Additional distillation steps are used to separate the styrene monomer from the
unreacted acetophenone and to purify the styrene monomer to polymerization-grade
monomer for sale.
The final major process step is the hydrogenation of the acetophenone by-product
to a-methyl benzyl alcohol. In this process step the acetophenone residue from
the styrene monomer distillation operation is reacted with hydrogen gas in the
presence of a hydrogenation catalyst. The following simplified equation represents
this hydrogenation step:
CH3-C=0 + H2 > CH3-CHOH
After hydrogenation the crude a-methyl benzyl alcohol formed by the reaction of
the acetophenone with hydrogen is recycled to the process for conversion to
styrene monomer.
b. Process Technology Figure III-5 is a copy of the block flowsheet for the
Oxirane, Channelview, propylene oxide—styrene monomer process as furnished by
the Oxirane Corp.9 Based on this flowsheet and the accompanying nonconfidential
information described in the trip report,9 as well as on the process descriptions
given in the three SRI Process Economics Program Reports2—4 and on physical
property data, a model plant has been constructed for this process, as shown in
Fig. III-6, pp. 1—3. The process shown is probably not an exact representation
of this peroxidation process as practiced by Oxirane at their Channelview plant
but is believed to be sufficiently representative to be useful for air emission
purposes.
-------
VEMT WATER
TO TO
FLARE B1OTPEAT
STEAM
JETS
CAUSTIC-
VENT CATALYST
TO TO
ATM DISPOSAL
ORGANIC \. |
RECOVERrj
EB, MBA
RECOVERY &
CAUSTIC WASH
M
10
Fig. III-5.
Oxirane, Channelview/ TX, Propylene Oxide-Styrene Monomer
Process Flow Diagram
-------
HS^
—~i—i ~^
Sir
V-jJX tffAVI
u .^"T._""^.-_
Fig. III-6. Model Plant (Uncontrolled) for PO by EB Hydroperoxide
(Page 1 of 3)
-------
i> MJXXD £-8
t-fC ttr. STOX+SZ
Fig. III-6. (Continued)
(Page 2 of 3)
-------
TO OIL
• i—i
I I-'-ll w-Jr=w-^---.<-
1----^ ' C=zr;>
V£T~i
•*fene f~\ /
» &n»+fj§ (4
c'u»r tZ^
F±g. in-6. (Continued)
(Page 3 of 3)
-------
111-26
In this process purified ethylbenzene (1) is fed to the oxidation reactors,;,
along with a stream of compressed air (2). The oxygen in the air converts a
small portion of the total ethylbenzene to ethylbenzene hydroperoxide. The
vent gas from this oxidation system consists of oxygen-depleted air saturated
with ethylbenzene vapor. This gas is scrubbed with "oil" and water to recover
the vaporized ethylbenzene before the vent gas (Aj) stream is discharged to the
atmosphere.
The dilute ethylbenzene hydroperoxide stream (3) is fed to a falling film
evaporator, where some of the unreacted ethylbenzene (4) is separated from the
hydroperoxide solution (5) under vacuum. The vent gas stream (A2) discharged
from the vacuum system on this evaporator contains inert gas saturated with
volatile organic compounds (VOC), principally ethylbenzene.
A portion of the hydroperoxide stream (6) is diverted to the catalyst mix tank,
where dry catalyst from storage is mixed into the hydroperoxide solution. The
vent gas stream from this mix tank is designated A3. The catalyst-hydroperoxide
mixture (7) is mixed with the main hydroperoxide stream, and this blended
stream (8) is sent to the high-pressure epoxidation reactors. Propylene (9)
from storage is also delivered to these reactors. The hydroperoxide reacts
with the propylene to produce propylene oxide, or-methyl benzyl alcohol, and
some acetophenone as a mixed-product stream (10).
The mixed-product stream (10) is fed to an intermediate pressure flash tank,
along with a compressed gas stream (23) containing principally propylene that
is recovered as the vent gas from a downstream PO stripping column.
The vapor-phase portion of the flow from the flash tank enters the upper section
of the separation column, while the liquid portion of the flow from the flash
tank enters the lower section of the column. The separation column separates
unreacted propylene (11) from the main-product stream (14). The vent gas
stream from this column is designated A4.
The unreacted propylene stream (11) is fed to a lights stripping column, where
low-boiling-point hydrocarbons (such as methane, ethane, and ethylene) are
stripped out of the main propylene recovery stream (12). The vent gas stream
from this column is designated A5. The lights are separated as a waste stream
suitable for use as a fuel.
-------
111-27
The main propylene recovery stream (12) is sent to a propylene recovery column,
where purified propylene (13) is taken overhead for recycle to the epoxidation
reactors. The vent gas stream from this column is designated as A6. The bottoms
from this column (K2) is a waste stream containing propane and other higher boiling
point hydrocarbons and is suitable for use as a fuel.
The main-product stream (14) from the separation column is held in the crude
product intermediate storage tank and then fed to the product wash-decant
system. A dilute caustic stream (25) is used as the first wash liquid in this
system. The exhausted caustic wash stream (15) discharges to the wastewater
collection manifold. The organic layer (16) is then washed with process water
to extract additional impurities. After the wastewater stream (17) from this
second wash stage joins the dilute caustic wastewater stream (15), the combined
wastewaters (K3) are sent to disposal. The washed product (18) is held in the
washed product intermediate storage tank, where residual traces of wastewater
(19) settle out and are discharged to the wastewater collection manifold. The
vent gas stream from this section is labeled A7.
The washed product stream (20) from storage is fed to the PO stripping column,
where the crude propylene oxide (21) is taken overhead to separate it from the
crude mixed hydrocarbon (HC) stream (24). The vent gas from this column is
discharged to a vent gas header, and the combined vent gas stream from this
column and the PO finishing column is compressed and the compressed gas (23) is
returned to the separation column.
The crude propylene oxide (21) is fed to the PO finishing column, where the
finished propylene oxide (22) is taken overhead and then sent to final-product
storage and shipping. The vent gas from the PO finishing column discharges to
the vent gas collection manifold, where it combines with the vent gas from the
PO stripping column. The bottoms stream (K4) from the finishing column contains
the higher boiling point impurities and is discarded as a waste stream suitable
for use as a fuel.
The crude mixed hydrocarbon stream (24) is washed wih a dilute caustic stream
(30) in the mixed HC wash-decant system. The dilute caustic stream (25) from
this system is sent to the product wash-decant system for reuse. The washed
mixed HC layer (26) is held in the washed—mixed HC intermediate storage tank.
The vent gas stream from this system is labeled A8.
-------
111-28
Ethylbenzene (EB) (27) from incoming shipments, as well as ethylbenzene (4) from
the receiver on the falling film evaporator and ethylbenzene (33) from the bottoms
of the light HC stripping column, is combined and stored in the EB bulk storage
tank. The ethylbenzene (28) from storage is fed to the EB wash-decant system,
where it is washed with a fresh dilute caustic stream (29) from the dilute caustic
mix tank. THe dilute caustic stream (30) from this system is sent to the mixed
HC wash-decant system for reuse. The washed ethylbenzene (31) is sent to the EB
feed tank. The vent gas stream on the EB wash-decant system is labeled A9.
After the washing step the mixed HC stream (26) is sent to the EB stripping
column, along with the overhead stream (42) from the light impurities stripping
column. The EB stripping column is used to separate ethylbenzene (32) from the
crude cr-methyl benzyl alcohol—acetophenone mixture (a-MBA—AP) (34). The vent
gs stream from this column is labeled A10.
The ethylbenzene (32) from the EB stripping column is sent to the light HC
stripping column, where lower boiling point hydrocarbon impurities (K5) are
stripped out of the recovered ethylbenzene (33). The hydrocarbon impurities
(K5) are suitable for use as fuel. The vent gas stream from the light HC
stripping column is labeled AH. The recovered ethylbenzene (33) is sent to
the EB bulk storage tank.
The mixed a-MBA—AP stream (34) from the EB stripping column is combined with
the oil layer (36) from the decanter tank of the vacuum steam-jet condenser
system and the crude a-MBA stream (49) from the crude a-MBA receiver, and this
combined stream (35) is held in the a-MBA—AP intermediate storage tank for
delivery to the a-MBA—AP stripping column. This column operates under vacuum
to separate the mixed a-MBA—AP stream (37) from the residual heavy-hydrocarbon
waste stream (K7). The waste stream (K7) is suitable for use as a fuel. The
vacuum steam-jet condenser system on this column condenses a mixture of hydro-
carbon and water. The hydrocarbon oil layer (36) is skimmed off the water
layer and is recycled to the a-MBA—AP intermediate storage tank. The water
layer (K6) is sent to the plant wastewater treatment system. The vent gas
stream from the column vacuum steam-jet system is labeled A12.
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111-29
The distilled a-MBA—AP stream (37) is held in an intermediate storage tank.
From this tank a small stream (38) is fed to the catalyst mix tank, where dry
catalyst from storage is mixed into the organic material to form a catalyst-
organic mixture (39). The vent gas stream from the catalyst mix tank is labeled
A13. The catalyst-containing stream (39) is then combined with the main a-MBA—AP
feed stream and the stream (46) from the oil receiver as a feed stream (40) to
the dehydration reactor. In the reactor the a-MBA is dehydrated to styrene
monomer, while the AP does not react. The condenser is used to condense the
water of reaction, along with some organic vapors. The hydrocarbon oil layer
is skimmed off the condensate and combined with the clear organic layer from
the hydroclone. Then the condensed wastewater (K8) is sent to the plant waste-
water treatment facility. The thickened mixture of exhausted catalyst and
residual organic tars (Kg) is collected for disposal. The vent gas stream from
this dehydration reactor is labeled A14.
The crude styrene monomer stream (41) from the dehydration reactor is stored in
an intermediate storage tank and then fed to the light impurities stripping
column. This column operates under vacuum to strip off low-boiling-point
impurities (42) from the crude styrene monomer (43). The vacuum-jet condenser
system on this column condenses a mixture of water and some hydrocarbon oil.
The oil layer (44) is skimmed off and sent to the oil receiver, while the
wastewater (K10) is sent to the plant wastewater treatment facility. The vent
gas stream from the vacuum-jet system is labeled A15.
The stripped styrene monomer stream (43) is fed to the styrene finishing column,
where purified styrene monomer is taken overhead, condensed, and sent to the
finished styrene monomer storage tanks prior to shipment. The vacuum steam
jets and condensers on this column condense a mixture of water and some hydro-
carbon oil. The oil layer (45) is sent to the oil receiver, while the wastewater
stream (KU) is sent to the plant wastewater treatment facility. The vent gas
stream exhausted by the vacuum steam jets is labeled A16.
The bottoms stream (47) from the styrene finishing column is held in the AP
intermediate storage tank for delivery to the hydrogenation reactor. A stream
of hydrogen (48) is also fed to this reactor, where the hydrogen reacts with
the acetophenone to form a-methyl benzyl alcohol (49). The vent gas streams
-------
Ill-30
from this reactor are labeled A17 and A18. Spent catalyst (K12) is periodi-
cally removed from the reactor and replaced with fresh catalyst. The crude
or-methyl benzyl alcohol (49) from this reactor is held in the crude a-MBA
receiver tank and then recycled to the a-MBA—AP intermediate storage tank. A
mixed stream of hydrogen and nitrogen (48) is used periodically to activate the
catalyst in this hydrogenation reactor.
-------
111-31
D. REFERENCES*
1. S. A. Cogswell, "Propylene Oxide," pp. 690.8021A—690.8023D in Chemical Economics
Handbook, Stanford Research Institute, Menlo Park, CA (July 1979).
2. K. E. Lunde, Propylene Oxide and Ethylene Oxide, Report No. 2, Process Economics
Program, Stanford Research Institute, Menlo Park, CA (nd).
3. y. C. Yen, Propylene Oxide and Ethylene Oxide, Supplement A, Report No. 2A, Process
Economics Program, Stanford Research Institute, Menlo Park, CA (February 1967).
4. Y. C. Yen, Propylene Oxide and Ethylene Oxide, Supplement B, Report No. 2B, Process
Economics Program, Stanford Research Institute, Menlo Park, CA (February 1971).
5. S. L. Soder and K. L. Ring with R. E. Davenport, "Propylene," pp. 300.5403J,
K, U, V, W, X in Chemical Economics Handbook, Stanford Research Institute,
Menlo Park, CA (August 1978).
6. c. W. Stuewe, IT Enviroscience, Inc., Trip Report for Visit to Dow Chemical Co.,
Plaquemine, LA, Nov. 16 and 17, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
7. "Chementator," Chemical Engineering 86(15), 41 (July 16, 1978).
8. Letter dated Oct. 5, 1979, from S. W. Fretwell, Oxirane Corp., Houston, TX, to
Carl A. Peterson, Jr., IT Enviroscience, Inc.
9. C. A. Peterson, IT Enviroscience, Inc., Trip Report for Visit to Oxirane Chemical
Co., Channelview, TX, Oct. 18. 1978 (on file at EPA, ESED, Research Triangle Park,
NC).
*When a reference number is used at the end of a paragraph or on a heading,
it usually refers to the entire paragraph or material under the heading.
When, however, an additional reference is required for only a certain portion
of the paragraph or captioned material, the earlier reference number may not
apply to that particular portion.
-------
IV-1
IV. EMISSIONS
Emissions in this report are usually identified in terms of volatile organic
compounds (VOC). VOC are currently considered by the EPA to be those of a
large group of organic chemicals, most of which, when emitted to the atmosphere,
participate in photochemical reactions producing ozone. A relatively small
number of organic chemicals are photochemically unreactive. However, many photo-
chemically unreactive organic chemicals are of concern and may not be exempt
from regulation by EPA under Section 111 and 112 of the Clean Air Act since
there are associated health or welfare impacts other than those related to
ozone formation.
A. CHLOROHYDRINATION PROCESS
1. Model Plant1—5
The model plant for this study on the chlorohydrination process for the manu-
facture of propylene oxide has a production capacity of 68 Gg/yr based on
8760-hr/yr operation.* Actual capacities of newer production plants using this
process range up to 454 Gg/yr, but these larger plants are composed of multiple
train units, with some larger sized purification systems. Therefore it is
presumed that the selected size of the model plant will be somewhat representative
of a single train in the multiple-train plants. The flow diagram of the model
plant shown in Fig. III-2 is believed to be typical of today's manufacturing
and engineering technology as currently practiced. Modern design methods could
probably permit the design of larger sized single-train units, but the technology
represented is believed to be close enough to be suitable for emission control
studies.
2. Sources and Emissions
Sources and emission rates for the chlorohydrination process for propylene
oxide are summarized in Table IV-1; the amounts and compositions of the VOC are
intended to represent typical emissions from a well-designed and -operated
system.
*Process downtime is normally expected to range from 5 to 15%. If the hourly
rate remains constant, the annual production and annual VOC emissions will be
correspondingly reduced. Control devices will usually operate on the same
cycle as the process. From the standpoint of cost-effectiveness calculations,
the error introduced by assuming continuous operation is negligible.
-------
Table IV-1. Total Uncontrolled VOC Emissions from the Model Plant for the Manufacture of
Propylene Oxide Using the Chlorohydrination Process (68 Gg/yr)
Emission Source
Vent gas scrubber vent
Saponification column vent
PO stripping column vent
Lights stripping column vent
PO final distillation column
vent
DCP distillation column vent
DCIPE stripping column vent
Fugitive
Storage and handling
Secondary
Stream
Designation
(Fig.III-2)
Al
A2
A3
A4
A5
A6
A7
VOC Emissions
Ratio
(g/kg)C
10.25
0.043
0.006
0.006
0.006
0.0001
Rate
(kg/hr)
79.57
0.33
0.05
0.05
0.05
0.0008
0.000004 0.00003
Not
Not
Not
10.31
estimated
estimated
estimated
80.05
Vent Gas VOC Composition (wt %}
C2 C-? PO DCP DCIPE Other
5.0 78.4 16.6
90 10
89.9 10.1
79.9 20.1
100 Trace
98 2
98 2
Non-VOC in
Vent Gas
(wt %)
4.7
47.0
46.2
46.2
46.2
83
97
Uncontrolled emissions are emissions from the process for which no specific emission control devices {other than those
necessary for economy or safety) have been installed.
^
VOC emissions exclude methane but include higher-molecular-weight organic compounds such as ethylene, propane,
propylene, etc.
~g of emission per kg of propylene oxide produced.
-------
IV-3
a- Vent Gas Scrubber Vent This vent (Alf Fig. III-2) discharges the vent gas
from the chlorohydrin reactors after the gas is scrubbed to remove residual
vapors of chlorine and hydrochloric acid. This vent stream is the main emission
source from the chlorohydrination process. The source of this vent gas is the
inert propane contained in the propylene fed to the chlorohydrin reactors. The
propane does not react in the chlorohydrin reactors and exits the system through
the vent gas scrubber. This unreactive propane acts as a sweep gas, carrying
other vapors and gases with it. The amount and composition given in Table IV-1
are intended to represent typical emissions from a well-designed and -operated
process when chemical-grade propylene at a normal purity level is used as feed
for the process.
b. Saponification Column Vent This vent (A2, Fig. III-2) discharges the inert
gases carried into the saponification column along with the column feed streams.
The inert gases act as a sweep gas to carry vapors of propylene oxide and other
materials along with them as they exit the system. The propylene oxide (PO)
from the saponification column is compressed and condensed to yield crude PO.
The inert gases that enter the system sweep with the PO through the compressor
and condenser and must eventually exit this system through a pressure control
valve. They are saturated with propylene oxide vapor from the liquefied PO and
carry the vapor with the inert gases as they exit.
c- PO Stripping Column Vent This vent (A3, Fig. III-2) discharges the inert
gases carried into the PO stripping column along with the column feed streams.
The inert gases act as sweep gases to carry vapors of propylene oxide and other
materials along with them as they exit the system.
d- Lights Stripping Column Vent-—This vent (A4, Fig. III-2) discharges the inert
gases carried into the lights stripping column along with the column feed
stream. The inert gases act as sweep gases to carry with them vapors of propylene
oxide and other materials as they exit the system.
e. PO Final Distillation Column Vent This vent (A5, Fig. III-2) discharges the
inert gases carried into the PO final distillation column along with the column
feed stream. The inert gases act as sweep gases and carry vapors of propylene
oxide and other materials along with them as they exit the system.
-------
IV-4
f- DCP Distillation Column Vent This vent (A6, Fig. III-2) discharges the inert
gases carried into the DCP (dichloropropane) distillation column along with the
column feed stream. The inert gases act as sweep gases to carry with them
vapors of DCP and other materials as they exit the system.
g. DCIPE Distillation Column Vent This vent (A7, Fig. III-2) discharges the
inert gases carried into the DCIPE (dichloroisopropyl ether) distillation
column along with the column feed stream. The inert gases act as sweep gases
to carry with them vapors of DCIPE and other materials as they exit the system.
h. Fugitive Emissions Process pumps, piping flanges, compressor shaft seals, and
valves are all potential sources of fugitive emissions. No attempt has been
made to estimate the total number of pumps, flanges, compressors, valves, or
their emission characteristics for this model plant. Refer to the separate
fugitive emissions report6 for additional information on this subject.
i. Storage and Handling Emissions Emissions result from the storage and handling
of raw materials, intermediates, finished products, by-products, and waste
streams. No attempt has been made to estimate quantity, size, condition, or
emissions generated by the storage requirements or handling requirements of
this model plant. Refer to the separate storage and handling report7 for addi-
tional information on this subject.
j. Secondary Emissions The principal sources of secondary VOC emissions are the
process waste streams generated by this process. No attempt has been made to
estimate the secondary emissions generated by the storage, handling, processing,
or treatment of the various waste streams generated by this process. Refer to
the separate secondary emissions report8 for additional information on this
subject.
B. ISOBUTANE HYDROPEROXIDE PROCESS
1. Model Plant1—4'9'10
The model plant for this study on the isobutane hydroperoxide process for the
manufacture of propylene oxide has a production capacity of 417 Gg/yr based on
8760-hr/yr operation. This selected capacity is a close match to the current
-------
IV-5
nominal production capacity of the Oxirane Bayport plant, the only domestic
plant manufacturing propylene oxide by this process. It is recognized that
some sections of this plant consist of multitrain units, but this type of
construction is not expected to cause significant variations in the emission
calculations used for the model plant. It is believed that the flow diagram of
the model plant shown in Fig. III-4 is typical of today's manufacturing and
engineering technology.
2. Sources and Emissions
Sources and emission rates for the isobutane hydroperoxide process for propylene
oxide are summarized in Table IV-2; the amounts and compositions of VOC are intended
to represent typical emissions from a well-designed and -operated plant.
a- Oxidation Reactor Scrubber Vent This vent (Aj, Fig. III-4) discharges the
inert gases carried into the oxidation reactors with the purified oxygen.
These inert gases are saturated with organic vapors and act as a sweep gas to
carry the VOC out of the reactors. A caustic scrubber is used to remove carbonyl
compounds from the inert gas stream. Another scrubber, containing cool t-butyl
alcohol (TPA), is used to absorb and remove organic vapors (principally isobutane)
from this vent gas stream before the vent gas is discharged. The TBA scrubber
is required to reduce the concentration of isobutane in the vent gas to economi-
cally acceptable levels.9
b- TBA Stripping Column Vent This vent (A2, Fig. III-4) discharges the inert gases
carried into the TBA stripping column with the column feed streams. The inert
gases act as sweep gases to carry with them TBA vapors and other materials as
they exit the system.
c- Catalyst Mix Tank Vent Fluctions in tank liquid level and temperature result .
in the inert gases that enter the tank being discharged through the opening of
this vent (A3, Fig. III-4). These inert gases are saturated with propylene glycol
vapor and act as a sweep gas to carry this VOC out of the tank vent.
d- PQ Stripping Column Vent This vent (A4, Fig. III-4) discharges the inert
gases that enter this column with the feed stream. These inert gases are
saturated with propylene. oxide vapor and act as a sweep gas to carry this VOC
out of the column vent.
-------
Table IV-2. Total Uncontrolled VOC Emissions from the Model Plant for the Manufacture of
Propylene Oxide Using the Isobutane Hydroperoxide Process (417 Gg/yr)
Emission Source
Oxidation reactor scrubber vent
TBA stripping column vent
Catalyst mix tank vent
PO stripping colunn vent
Crude TEA recover; coluttn vent
TBA wash-decant system vent
Wastewater stripping colunn vent
d
Solvent scrubber vent
Solvent recovery column vent
Hater stripping column vent
Propylene glycol column and dipropylene
•^lycol colunn combined vent
Wastewater stripping colunn vent
Plant furnace flue gas vents
Fugitive
Storage and handling
Secondary
Designation
(Flg.III-4)
Al
A2
A3
*4
A5
A6
A7
A8
S
Aio
*11
A12
A13
"uncontrolled emissions are Missions from the process
VOC Emissions
Ititio Hate Vent Gas VOC Composition
-------
IV-7
e. Crude TEA Recovery Column Vent This vent (A5, Fig. III-4) discharges the
inert gases that enter this column with the feed stream or by internal column
pressure fluctuations. These inert gases are saturated with t-butyl alcohol
vapor and act as a sweep gas to carry this VOC out of the column vent.
f- TEA Wash-Decant System Vent This vent (A6, Fig. III-4) discharges the inert
gases that enter this system with the system feed streams and/or the pad-gas
manifold. These inert gases are saturated with isobutane and t-butyl alcohol
vapor and act as a sweep gas to carry these VOC out of the system vent.
g- Wastewater Stripping Column Vent This vent (A7, Fig. III-4) discharges the
inert gases that enter this column with the feed stream or by internal column
pressure fluctuations. These inert gases are saturated with isobutylene and
t-butyl alcohol vapors and act as a sweep gas to carry these VOC vapors out of
the column vent.
h. Solvent Scrubber Vent This vent (A8, Fig. III-4) discharges the vent gases
from the various PO feed and storage tanks and the vent gases from the solvent-PO
separation column and the PO finishing column after all these vent gases are
scrubbed with solvent to absorb and remove most of the propylene oxide contained
in the vent gases. The vent gas exiting the scrubber is saturated with equilibrium
concentrations of solvent vapor and residual propylene oxide.9
i- Solvent Recovery Column Vent This vent (A9/ Fig. III-4) discharges the inert
gases that enter the column with the feed stream or by internal column pressure
fluctuations. These inert gases are saturated with solvent vapor and act as a
sweep gas to carry this VOC out of the column vent.
J- Water Stripping Column Vent This vent (A10, Fig. III-4) discharges the inert
gases that enter the column with the column feed stream or by internal column
pressure fluctuations. These inert gases are saturated with water vapor,
residual carbonyl materials (acetone, etc.), and a trace of propylene glycol
vapor and act as a sweep gas to carry these VOC vapors out of the column vent.
-------
IV-8
k- Propylene Glycol Column and Dipropylene Glycol Column Combined Vent This vent
(AH, Fig. III-4) discharges the inert gases that enter the columns with the
column feed streams or by internal column pressure fluctuations. These inert
gases are saturated with vapors of propylene glycol and dipropylene glycol and
act as a sweep gas to carry these VOC vapors out of the column vents.
1. Wastewater Stripping Column Vent This vent (A12, Fig. III-4) discharges the
inert gases that enter the column with the column feed streams or by internal
column pressure fluctuations. These inert gases are saturated with vapors of
carbonyl compounds (acetone, methanol, etc.), along with some hydrocarbon vapor
and water vapor from the VOC being stripped out of the wastewater. These inert
gases act as a sweep gas to carry these VOC vapors out of the column vent.
m. Process Furnace Flue Gas Vents These vents (A13, Fig. III-4) represent the
discharge of flue gas combustion products from the process furnaces used in the
model plant to burn the fuel-rich waste streams from the process for process
heating requirements. These flue gases contain traces of aldehydes from combustion
of the various hydrocarbons in the fuel-rich waste streams.11
n. Fugitive Emissions Process pumps, piping flanges, compressor shaft seals, and
valves are all potential sources of fugitive emissions. No attempt has been
made to estimate the total number of pumps, flanges, compressors, valves, or
their emissions characteristics for this model plant. Refer to the separate
fugitive emissions report6 for additional information on this subject.
o. Storage and Handling Emissions Emissions result from the storage and handling
of raw materials, intermediates, finished products, by-products, and waste
streams. No attempt has been made to estimate quantity, size, condition, or
emissions generated by these various storage and handling requirements of this
model plant. Refer to the separate storage and handling report7 for additional
information on this subject.
p. Secondary Emissions The principal sources for secondary emissions are the waste
streams generated by the process. No attempt has been made to estimate the second-
ary emissions generated by the storage, handling, processing, or treatment of the
various waste streams generated by the model plant. Refer to the separate secondary
emissions report8 for additional information on this subject.
-------
IV-9
C. ETHYLBENZENE HYDROPEROXIDE PROCESS
1. Model Plant1—4'12
The model plant for this study on the ethylbenzene hydroperoxide process for the
manufacture of propylene oxide has a production capacity of 181 Gg/yr based on
8760-hr/yr operation. This selected capacity is a close match to the current
nominal production capacity of the Oxirane Channelview plant, the only domestic
plant manufacturing propylene oxide by this process. It is recognized that some
sections of the plant consist of multitrain units but this type of construction is
not expected to cause significant variations in emission calculations used for the
model plant. It is believed that the flow diagram of the model plant shown in
Fig. III-6 is typical of today's manufacturing and engineering technology.
2. Sources and Emissions
Sources and emission rates for the ethylbenzene hydroperoxide process for
propylene oxide are summarized in Table IV-3; the amounts and compositions of
VOC are intended to represent typical emissions from a well-designed and -operated
plant.
a- Oxidation Reactor Scrubber Vent This vent (Aj, Fig. III-6) discharges the
inert gases carried into the oxidation reactor with the compressed air used for
oxidation of the ethylbenzene. This stream of oxygen-depleted air is saturated
with vapors of ethylbenzene and other VOC. These gases are scrubbed with oil
(a-methyl benzyl alcohol—acetophenone, a-MBA—AP) and water for recovery of
most of the hydrocarbon vapors swept out of the reactor system by the inert
gases. The vent gas scrubbers could be considered emission control devices,
but for purposes of this report they are classified as a necessary part of the
process to reduce ethylbenzene vapor losses to economically acceptable levels.
t>. FF Evaporator Vent This vent (A2, Fig. III-6) discharges the inert gases
carried into the falling film evaporator with the evaporator feed stream.
These inert gases are saturated with ethylbenzene vapor and act as a sweep gas
to carry the VOC vapors with them as they exit the system.
-------
Table IV-3. Total Uncontrolled VOC Emissions from the Model Plant for the Manufacture of
Propylene Oxide Using the Ethylbenzene Hydroperoxide Process (181 Gg/yr)
VOC
Desionation Ratio
Emission Source
Oxidation reactor scrubber vent
FF evaporator vent
Catalyst mix tank vent
Separation column vent
Lights stripping column vent
Propylene recovery column vent
Product wash-decant system vent
Mixed HC wash-decant system vent
EB wash-decant system vent
EB stripping colunn vent
Light HC stripping colunn vent
a MBA-AP stripping column vent
Catalyst mix tank vent
Dehydration reactor system vent
Light impurities stripping colunn vent
Styrene finishing column vent
Hydrogenation reactor operating vent
Hydrogenation reactor activation vent
Fugitive
Storage and handling
Secondary
Uncontrolled emissions are emissions from
installed.
VOC emissions exclude methane* but include
(Fig.III-6)
*1
A2
A3
A4
A5
A6
A7
A8
A9
Aio
All
A12
A13
A14
A15
A16
A17
A18
the process
«,Aq)C
1.61
0.0051
Trace
0.16
0.16
0.16
0.0005
0.0015
0.0014
0.0015
0.0015
0.0080
Trace
O.OO08
1.24
0.83
Normally 0
Normally 0
Not
Not
Not
4.18
Emissions
jtj,.,- Vent Gas VOC Composition (wt %)
(kq/hr) C2 C, PO EB Styrene
33.5 50
0.11 95
Trace 95
3.31 5 95
3.31 20 80
3.31 100
0.01 95
0.03 ga
0.03 100
0.03 98
0.03 95
0.17
Trace
0.02 5 95
25.7 95 2
17 -2 Trace 100
Normally 0
Normally 0
estimated
estimated
estimated
86.6
for which no specific emission control devices (other than those necessary for economy
Other
50
5
5
Trace
Trace
Trace
5
2
Trace
2
5
100
100
Trace
3
Trace
or safety
Non-VOC in
Vent Gas
(wt %)
99.9+
90
V100
17
17
17
88
90
90
90
90
99+
•"•100
99+
90
90
100
have been
higher-molecular -weight organic compounds such as ethane, ethylene, propane, propylene, etc.
g of emission per kg of propylene oxide produced.
dSee ref 12.
I
M
O
-------
IV-11
c. Catalyst Mix Tank Vent This vent (A3/ Fig. III-6) discharges the inert gases
that enter the catalyst mix tank because of fluctuations in liquid level and
temperature in the tank. These gases are saturated with VOC vapors, which are
swept out as the gases exit the tank vent. Due to low vapor pressure and small
flows of inert gases, the amount of VOC in this vent stream is very low.
d. Separation Column Vent This vent (A4, Fig. III-6) discharges the inert gases
that enter the Separation Column with the column feed streams. These inert
gases are saturated with propylene vapor and, acting as a sweep gas, carry the
VOC vapor with them as they exit the column.
e. Lights Stripping Column Vent This vent (A5, Fig. III-6) discharges the inert
gases that enter the lights stripping column with the column feed stream. These
inert gases are saturated with a mixture of low-boiling-point hydrocarbon vapors,
which are swept out with the gases as they exit the column.
f. Propylene Recovery Column Vent This vent (A6, Fig. III-6) discharges the
inert gases that enter the propylene recovery column with the column feedstream.
These inert gases, which are saturated with propylene vapor, sweep the VOC
vapors with them as they exit the column.
g. Product Wash-Decant System Vent This vent (A7, Fig. III-6) discharges the
inert gases that enter the system with the system feed streams. These inert
gases are saturated with propylene oxide vapor and other VOC vapors, which are
swept out with the gases as they exit the wash-decant system.
h. Mixed HC Wash-Decant System Vent This vent (A8, Fig. III-6) discharges the
inert gases that enter the system with the system feed streams. These inert
gases are saturated with vapors of ethylbenzene and other VOC. The inert gases
sweep these vapors with them as they exit the system.
i- EB Wash-Decant System Vent This vent (A9/ Fig. II1-6) discharges the inert
gases that enter the system with the system feed streams. These gases are
saturated with vapors of ethylbenzene, which are swept out of the system by the
inert gases as they exit the system.
-------
IV-12
j. EB Stripping Column Vent The inert gases that enter the column with the
column feed streams are discharged from this vent (A10/ Fig. III-6) and are
saturated with vapors of ethylbenzene and other VOC. These vapors are swept
out of the column along with the exiting inert gases.
k. Light HC Stripping Column Vent This vent (A1J, Fig. III-6) discharges the
inert gases that enter the column with the column feed stream. These inert
gases are saturated with mixed hydrocarbon vapors, and sweep these vapors with
them as they exit the column.
1. g-MBA—-AP Stripping Column Vent This vent (A12, Fig. III-6) discharges the inert
gases that bleed into this vacuum distillation column through the leaks in the
column system assembly. When discharged from the atmospheric exhaust of the vacuum
steam-jet system, these inert gases are saturated with water vapor and VOC vapors.
m. Catalyst Mix Tank Vent This vent (A13, Fig. III-6) discharges the inert gases
that enter the catalyst mix tank because of fluctuations in liquid level and
temperature in the tank. These gases are saturated with vapors of VOC from the
tank liquid, and sweep the VOC vapors out of the tank vent. Due to low vapor
pressure and small flows of inert gases, the amount of VOC in this vent stream
is very low.
n. Dehydration Reactor System Vent This vent (A14, Fig. III-6) discharges the
inert gases that enter the system with the system feed stream. These inert
gases are saturated with vapors of mixed VOC, which are swept out with the
inert gases as they exit the system.
o. Light Impurities Stripping Column Vent This vent (A15, Fig. III-6) discharges
the inert gases that bleed into this vacuum distillation column through the
leaks in the column system assembly. When the inert gases are discharged from
the atmospheric exhaust of the vacuum steam jet system, they are saturated with
water vapor and VOC vapor.
p. Styrene Finishing Column Vent This vent (A16, Fig. III-6) discharges the
inert gases that bleed into this vacuum distillation column through the leaks
in the column system assembly- When the inert gases are discharged from the
-------
IV-13
atmospheric exhaust of the vacuum steam-jet system, they are saturated with
water vapor and styrene monomer vapor.
q. Hydrogenation System Operating Vent This vent (A17/ Fig. III-6) does not
normally open and discharge any inert gases or VOC vapors. The small amount of
inert gases that enter the system with the feed streams normally dissolve in
the liquid and exit the reactor with the product stream.
r. Hydrogenation System Activation Vent This vent (A18, Fig. III-6) discharges a
mixture of hydrogen and nitrogen when a feed stream of mixed hydrogen and
nitrogen is used to periodically activate the reactor catalyst. Since all
organic materials are removed prior to activation, this vent stream normally
does not contain any VOC vapors.
s. Fugitive Emissions Process pumps, piping flanges, compressor shaft seals, and
valves are all potential sources of fugitive emissions. No attempt has been
made to estimate the total number of pumps, flanges, compressors, valves, or
their emission characteristics for this model plant. Refer to the Fugitive
Emissions report6 for additional information on this subject.
t- Storage and Handling Emissions Emissions result from the storage and handling
of raw materials, intermediates, finished products, by-products, and waste
streams. No attempt has been made to estimate quantity, size, condition, or
emissions generated by the various storage and handling requirements of this
model plant. Refer to the Storage and Handling report7 for additional informa-
tion on this subject.
u- Secondary Emissions The principal sources for secondary emissions are the
waste streams generated by the process. No attempt has been made to estimate
the secondary emissions generated by the storage, handling, processing, or
treatment of the various waste streams generated by the model plant. Refer to
the Secondary Emissions report8 for additional information on this subject.
D. OTHER PROCESSES1—4
The literature describes other processes for the manufacture of propylene
oxide, but the three processes previously described are the only ones now
-------
IV-14
practiced domestically. The electrochemical version of the chlorohydrination
process is being promoted by Lummus,13 but emission characteristics and process
economics for this approach are expected to be similar to those of the original
clorohydrination process.
In the hydroperoxide process it is possible to substitute other easily oxidized
hydrocarbons for isobutane or ethylbenzene (cumene, for example). When such a
substitution is made, the propylene—propylene oxide conversion is essentially
unchanged, but the conversion of the hydrocarbon to hydroperoxide to alcohol
yields a different coproduct, depending on the starting material. For the
hydroperoxide process to be economical, the coproduct alcohol must either be a
valuable product or be convertible to a valuable product. An alternative on
convertability includes the possibility of converting the alcohol coproduct
back to the starting hydrocarbon for recycle. If other hydroperoxide processes
are adopted for domestic use, their emission characteristics are expected to be
similar to those of the two existing hydroperoxide processes.
A third alternative route to the manufacture of propylene oxide is the direct
oxidation of propylene with either air or purified oxygen in a manner similar
to the present processes for ethylene oxide. A lot of research has been performed
in various attempts to find catalysts and process conditions economically
favorable for this direct oxidation route to propylene oxide, but published
results to date indicate poor yields and/or conversion rates. If future research
on an economically competitive direct oxidation route is successful, the emission
characteristics of this process are expected to be similar to those of one of the
two existing versions of the ethylene oxide direct oxidation process.
-------
IV-15
E. REFERENCES*
1. S. A. Cogswell, "Propylene Oxide," pp. 690.8021A—690.8923D in Chemical Economics
Handbook, Stanford Research Institute, Menlo Park, CA (July 1979).
2. K. E. Lunde, Propylene Oxide and Ethylene Oxide, Report No. 2, Process Economics
Program, Stanford Research Institute, Menlo Park, CA (nd).
3. Y. C. Yen, Propylene Oxide and Ethylene Oxide, Supplement A, Report No. 2A,
Process Economics Program, Stanford Research Institute, Menlo Park, CA
(February 1967).
4. Y. C. Yen, Propylene Oxide and Ethylene Oxide, Supplement B, Report No. 2B,
Process Economics Program, Stanford Research Institute, Menlo Park, CA
(February 1971).
5. c. W. Stuewe, IT Enviroscience, Inc., Trip Report for Visit to Dow Chemical Co.,
Plaguemine, LA, Nov. 16 and 17, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
6. D. G. Erikson and V. Kalcevic, IT Enviroscience, Inc., Fugitive Emissions
(September 1980) (EPA/ESED report, Research Triangle Park, NC).
7. D. G. Erikson, IT Enviroscience, Inc., Storage and Handling (September 1980)
(EPA/ESED report, Research Triangle Park, NC).
8. J. j. Cudahy and R. L. Standifer, IT Enviroscience, Inc., Secondary Emissions
(June 1980)(EPA/ESED report, Research Triangle Park, NC).
9. Letter dated Mar. 26, 1980, from S. W. Fretwell, Oxiane Corp., to J. R. Farmer,
EPA.
10. Letter dated Oct. 5, 1979, from S. W. Fretwell, Oxirane Corp., Houston, TX,
to Carl A. Peterson, Jr., IT Enviroscience, Inc.
11. Air Pollution Control District, County of Los Angeles, Air Pollution Engineering
Manual, AP-40, 2d ed., p. 552, edited by J. A. Danielson (May 1973).
12. C. A. Peterson, IT Enviroscience, Inc., Trip Report for Visit to Oxirane Chemical
Co. (Channelview), Channelview, TX, Oct. 18, 1978 (on file at EPA, ESED, Research
Triangle Park, NC).
13. "Chementator," Chemical Engineering 86(15), 41 (July 16, 1979).
*When a reference number is used at the end of a paragraph or on a heading,
it usually refers to the entire paragraph or material under the heading.
When, however, an additional reference is required for only a certain portion
of the paragraph or captioned material, the earlier reference number may not
apply to that particular portion.
-------
V-l
V. APPLICABLE CONTROL SYSTEMS
A. CHLOROHYDRINATION PROCESS1
Table V-l contains a tabulation of controlled emissions from the chlorohydrin
process model plant. These control techniques are discussed as follows:
1. Vent Gas Scrubber Vent
This stream (Alf Fig. III-2) from the vent gas scrubber vent is the largest and
most significant source of VOC emissions for the model plant and consists prin-
cipally of propane with some residual unreacted propylene. Also present in
this vent gas stream are water vapor and small amounts of hydrochloric acid and
chlorine. Because of these non-VOC contaminants this vent gas is corrosive and
difficult to handle. Its heating value is approximately 3.8 GJ/hr for the model
plant.
The source of the residual propane that is the principal cause of the VOC emis-
sion is the unreactive propane that enters the system with the chemical-grade
propylene used to manufacture propylene oxide. Chemical-grade propylene contains
up to 5% propane and other nonreactive hydrocarbons. Another source of nonreactive
inert gases in this vent are those that enter the system with the chlorine used
to hydrochlorinate the propylene. These inert gases are not a direct source of
VOC, but they function as a sweep gas to carry VOC out of the reactor system.
Several alternatives for reduction of VOC emissions from this source are possible,
as described below:
(a) Upgrade the purity of the propylene used in this process by switching to
polymer-grade propylene instead of chemical-grade propylene. This switch
in propylene purity levels would reduce the VOC emissions by at least 70%
by reducing the amount of nonreactive propane entering the system. This
technique is recommended by Dow1 as the most cost-effective method for
reduction of the major VOC emissions from this process.
(b) Upgrade the purity of the chlorine used in this process to the purity level
of liquid chlorine (about 99.5%) from the lower quality level of in-plant
gaseous chlorine containing a significantly higher level of nonreactive
-------
Table V-l. VOC Controlled Emissions for Model Plant Producing Propylene Oxide by the
Chlorohydrination Process (68 Gg/yr)a
Total VOC
Stream Emission
Designation Control Device Reduction
Emission Source (Fig.III-2) or Technique (%)
Vent gas scrubber vent A
Sapors if icat ion column vent A
PO stripping column vent A
Lights stripping column vent A
PO final distillation column vent A
DCP distillation column vent A
b
DCIPE stripping column vent A
Fugitive
Storage and handling
Secondary
Upgrade purity of 70
propylene feedstock
Fume water scrubber 95
Fume water scrubber 95
Fume water scrubber 95
Fume water scrubber 95
Fume oil scrubber 90
. None 0
VOC Controlled
Emissions
Ratio Rate
(g/kg)*> (kg/hr)
3.07 23.87
0.0021 0.017
0.0003 0.0025
0.0003 0.0025
0.0003 0.0025
0.00001 0.00008
0.000004 0.00003
Not estimated
Not estimated
Not estimated
3.078 23.90
See ref 1.
Dg of emission per kg of propylene oxide produced.
<
-------
V-3
inerts. This technique would not reduce the emissions of nonreactive propane
contained in the propylene feedstock, but by reducing the quantity of inert
sweep gas, could reduce the amount of propylene swept out of the system.
Emission reduction might be in the range of 20 to 50% if this control tech-
nique were adopted. This method could be combined with the technique described
in (a) for an overall reduction in emissions of up to 85%.
(c) Destroy the VOC contained in the vent gas by feeding this vent gas through
a thermal incinerator (or flare) to convert the hydrocarbons to carbon
dioxide and water vapor. This incineration approach would be expected to
destroy 95 to 99% of the contained VOC, depending on the efficiency of the
combustion process used. The presence of small amounts of chlorine and
hydrochloric acid vapor in the vent gas would require the use of corrosion-
resistant construction for the ductwork and thermal oxidizer used to handle
the gas.
(d) Install an oil scrubber system and associated hydrocarbon stripping column
to scrub the propane and associated hydrocarbons out of this vent stream and
to recover the propane, etc., from the stripping column for use as a fuel.
This technique could remove up to 95% of the VOC from the vent gas stream
for recovery as a fuel. Because of the corrosive nature of this vent gas,
at least the scrubber and its associated ductwork would have to be fabri-
cated of corrosion-resistant materials. The presence of chlorine in the
vent gas would require extra care in the selection of a scrubber fluid to
avoid absorption of and reaction with chlorine. A design approach that is used
to reduce the problems caused by the presence of chlorine and hydrochloric acid
in this vent gas is the installation of an alkali scrubber (dilute caustic
scrubber) to pretreat the gas stream before treating the vent gas in an oil
scrubber to remove the contained VOC.
2. Saponification Column Vent
The stream from the vent (A2, Fig. III-2) on the Saponification column is small and
is rich in propylene oxide (PO). This vent gas can be sent to a water scrubber,
where the propylene oxide would be absorbed and eventually converted to a dilute
aqueous solution of propylene glycol. It is not necessary to provide one dedicated
water scrubber for each vent containing PO, since one larger sized scrubber can
accommodate as many vent streams as can be conveniently piped to the scrubber
-------
V-4
location. With a properly designed scrubber, a PO removal efficiency of 95% or
better can reasonably be achieved.
3. PO Stripping Column Vent
The stream from the vent (A3, Fig. III-2) on the PO stripping column is a small
vent stream rich in propylene oxide. This vent stream can be treated by using
a water scrubber, as described in V-A-2.
4. Lights Stripping Column Vent
The stream from the vent (A4, Fig. III-2) on the lights stripping column is a
small stream rich in propylene oxide. This vent stream can be treated by using
a water scrubber, as described in V-A-2.
5. PO Final Distillation Column Vent
The stream from the vent (A5, Fig. III-2) on the PO final distillation column
is small and is rich in propylene oxide. This vent stream can also be treated
by using a water scrubber, as described in V-A-2.
6. DCP Distillation Column Vent
The stream from the vent (A6, Fig. III-2) on the DCP distillation column is a
small one containing a very small quantity of dichloropropane. It is possible
to remove most of the dichloropropane from this vent gas stream either by the
use of an "oil" scrubber or by adsorption of the DCP on activated charcoal in
an adsorption canister. Either regeneration of the absorption or adsorption
medium would be required or the absorbent or adsorbent would need periodic replace-
ment. Absorption or adsorption can achieve 90% or better removal of the DCP
from the vent gas, but because of the small amount of VOC in this stream, the
cost/benefit ratio for removal is expected to be relatively high.
7. DCIPE Stripping Column Vent
The stream from the vent (A7, Fig. III-2) on the DCIPE stripping column is small
and contains an extremely small amount of dichloroisopropyl ether. It is possible
to remove a large part of this DCIPE from the vent gas by the use of either an
"oil" scrubber or a canister of activated charcoal. Because of the low concen-
tration of DCIPE in the vent gas, the removal efficiency by either technique is
-------
V-5
expected to be probably 80% or lower. Because of the small quantity of VOC in
this vent stream, it is expected that the cost/benefit ratio for removal would
be extremely high.
B. ISOBUTANE HYDROPEROXIDE PROCESS2
Table V-2 gives the controlled emissions from the isobutane hydroperoxide process
model plant. The techniques for controlling these emissions are discussed as
follows:
1. Oxidation Reactor Scrubber Vent
The stream from the oxidation reactor scrubber vent (Aj, Fig. III-4) is the
largest and most significant source of VOC emissions for the model plant and
consists principally of isobutane and t-butyl alcohol (TEA) vapors in an inert
gas stream. The caustic scrubber and the TEA vent scrubber have reduced the
VOC levels to economically acceptable loss levels, but it is possible to reduce
this residual VOC further by VOC emission control techniques. Some possible
alternative techniques for VOC emission reduction are as follows:
(a) Replace the TBA vent scrubber with a lean-oil absorber and regeneration
system. Use of this technique, whereby a low-vapor-pressure oil is used
in place of TBA as the scrubbing fluid, would eliminate the TBA vapors
from the vent gas while still permitting the isobutane to be recovered
from the vent gas stream. Emission reduction would be at least 50% with
this approach.
(b) Install an activated-carbon adsorption system after the TBA vent scrubber
to remove and recover most of the VOC in the vent stream. Depending on
the design and operating conditions for this adsorption-desorption-recovery
system, the VOC emission reduction might lie in the range of 60 to 85%.
-------
Table V-2. Controlled Emissions for Model Plant Producing Propylene Oxide by the
Isobutane Hydroperoxide Process (417 Gg/yr)a
Stream
Designation
Emission Source (Fiq.III-4)
Oxidation reactor scrubber vent
TEA stripping column vent
Catalyst mix tank vent
PO stripping column vent
Crude TEA recovery column vent
TBA wash-decant system vent
Wastewater stripping column vent
Solvent scrubber vent
Solvent recovery column vent
Water stripping column vent
Propylene glycol column and dipro-
pylene glycol column combined vent
Wastewater stripping column vent
Plant furnace flue gas vents
Fugitive
Storage and handling
Secondary
Al
A2
A3
A4
A5
A6
A7
A8
A9
A10
Al1
A12
A13
Total VOC
Control Device Emission Reducti
or Technique (%)
Plant flare
Vent condenser
None
Fume water scrubber
Fume water scrubber
Plant flare
Vent condenser
Plant flare
Plant flare
Plant flare
Fume wat«r scrubber
Vent condenser
None
98
60
95
95
98
80
98
98
98
95
80
VOC Controlled Emissions
-on Ratio
(q/kq)b
0.0352
0.0014
0.000012
0.00093
0.00078
0.00036
0.190
0.013
0.0000
0.00002
0,0029
0.266
0.040
Not estimated
Not estimated
Not estimated
0.551
Rate
(kq/hr)
1.676
0.144
0.0006
0.044
0.037
0.007
9.04
0.6 ']
0.0004
0.0012
0.138
12.66
1.90
26.25
See ref 2.
3g of emission per kg of propylene oxide product.
-------
V-7
2. TEA Stripping Column Vent
The stream from the vent (A2, Fig. III-4) on the TEA stripping column is a small
one rich in TEA vapor. The most likely technique for reduction of VOC emission
from this source would be the installation of a refrigerated vent condenser on
the vent line prior to the column pressure control valve. Depending on design
and operating conditions a vent condenser might recover 60 to 90% of the contained
VOC. Because of the small quantity of VOC in the vent, it is expected that the
cost-benefit ratio would be relatively high for any device used to reduce VOC
emissions from this source.
3. Catalyst Mix Tank Vent
The vent gas stream (AS, Fig. III-4) from the catalyst mix tank contains an
extremely small quantity of propylene glycol as the principal VOC. Because of
the minute amount of VOC emitted by this vent, no emission control technique is
specified.
4. PO Stripping Column Vent
The stream from the vent (A4, Fig. III-4) on the PO stripping column is small
and is rich in propylene oxide. This vent gas can be sent to a water scrubber,
where the propylene oxide would be absorbed and eventually converted to a dilute
aqueous solution of propylene glycol. It is not necessary to provide one dedicated
water scrubber for each vent containing PO, since one larger sized scrubber can
accommodate as many vent streams as can be conveniently piped to the scrubber
location. With a properly designed scrubber, a PO removal efficiency of 95% or
better can reasonably be achieved.
5. Crude TBA Recovery Column Vent
The stream from the vent (A5, Fig. III-4) on the crude TBA recovery column is
small and is rich in TBA vapor. A possible recovery technique for this VOC would
be the installation of a refrigerated vent condenser on the vent gas line before
the column relief valve. Such a condenser could recover 60 to 90% of the con-
tained VOC, depending on column operating pressure and vent condenser design.
Because of the small size of this vent stream, cost-benefit ratios for VOC reduc-
tion of this technique would be relatively high. An alternative approach for
control of this VOC would be to direct the vent gas stream to the same water
scrubber used to absorb PO, as described in V-B-4.
-------
V-8
6. TEA Wash-Decant System Vent
The vent gas stream (A6, Fig. III-4) from the TEA wash-decant system is very
small and is rich in isobutane, with some TBA. Because of the small size of
this vent stream, techniques that would be suitable for larger streams, such as
a lean-oil absorption-recovery system or an activated-carbon adsorption-recovery
system, probably would not have an acceptable cost-benefit ratio. The system of
choice would be to pipe the vent gas to a common vent header leading to a thermal
oxidation system sized to handle multiple vent gas streams (such as a vent gas
incinerator or flare), as described in V-B-l-(c). Flare efficiency is estimated
to be 98%.
7. Wastewater Stripping Column Vent
The vent gas stream (A7/ Fig. III-4) on the wastewater stripping column is a fairly
large stream rich in isobutylene and also contains some other organic materials,
such as acetone and TBA. The most likely technique for reduction of VOC emissions
from this source would be the installation of a refrigerated vent condenser in
the column vent line before the column relief valve. Depending on column operating
pressure and vent condenser design this recovery technique might remove from 80
to 95% of the VOC. An alternative technique would be to pipe the vent stream
to a common vent header leading to a thermal oxidizer system (vent gas incinerator
or flare), as described in V-B-l-(c).
8. Solvent Scrubber Vent
The stream from the vent (A8, Fig. III-4) on the solvent scrubber contains an
extremely small amount of VOC, principally vapors of solvent. This scrubber is
used to recover propylene oxide vapors from the vents on the various propylene
oxide distillation columns and associated receivers and tanks. The scrubber
could possibly be classified as an emission control device in its own right,
but it is present in the model plant as an economically justified yield improve-
ment system. The amount of VOC in this vent stream is so small that cost-benefit
ratios would be extremely high for any effective emission control device. The
only possibility that would even approach reasonable cost effectiveness would
be to pipe the vent gas to a common vent header leading to a thermal oxidizer
system, as described in V-B-l-(c). Even this approach would be expensive for
the VOC emission reduction that could be achieved. Flare efficiency is estimated
at 95% for this small stream in a multiuse flare.
-------
V-9
9. Solvent Recovery Column Vent
The vent gas stream (A9, Fig. III-4) on the solvent recovery column contains an
extremely small amount of VOC, principally vapors of solvent. Since the amount
of VOC in this vent stream is so small, cost-benefit ratios would be extremely
high for any effective emission control device. Connecting this vent to the
vent header going to the solvent scrubber would reduce overall VOC emissions
from this source by approximately 40%. The most reasonable cost-effective
technique would be to pipe the vent stream to a vent header leading to a thermal
oxidizer system, as described in V-B-l-(c). Even this approach would be expensive
for the VOC emission reduction that could be achieved. Flare efficiency is
estimated at 98%.
10. Water Stripping Column Vent
The stream from the vent (A10, Fig. III-4) on the water stripping column con-
tains a very small amount of VOC, principally acetone, which would therefore
make cost-benefit ratios very high for any effective emission control device.
A refrigerated vent condenser could be installed to reduce VOC emissions, but
installation and operating costs would be very high. A more reasonable approach
might be to pipe the vent stream to a common vent header leading to a thermal
oxidizer system, as described in V-B-l-(c). Even this approach would be expensive
for the VOC emission reduction that could be achieved. Flare efficiency is
estimated at 98%.
11. Propylene Glycol Column and Dipropylene Glycol Column Combined Vent
This combined vent stream (AH, Fig. III-4) contains a relatively small amount
of VOC, principally propylene glycol vapor, thereby making the cost-benefit
ratios relatively high for the amount of VOC reduction achieved. The most likely
candidate for control of this VOC emission would be a cold-water scrubbing system
to absorb the propylene glycol vapors. A well-designed scrubbing system would
be expected to remove more than 95% of the VOC from the vent gas. A possible
alternative to a separate water scrubber for this vent would be to pipe the
vent stream to a combined vent header leading to the water scrubber recommended
in V-B-4 if the PO stripping column vent is reasonably close to the combined
vent of these glycol distillation columns. In either case it is expected that
the cost would be high for the amount of VOC reduction achieved.
-------
V-10
12. Wastewater Stripping Column Vent
This vent gas stream (A12, Fig. III-4) from the wastewater stripping column is
the second largest source of VOC emissions in the model plant. The principal
VOC in this vent gas is acetone, along with significant amounts of isobutane
and other organics. The suggested technique for control of this VOC emission
source is the installation of a refrigerated vent condenser in the column vent
line before the column pressure control (relief) valve. Depending on column
operating pressure and vent condenser system design the removal efficiency
could vary from 80 to 99+%.
13. Plant Furnace Flue Gas Vents
The flue gas vent stream (A13, Fig. III-4) is a relatively small source of VOC
emissions, which are principally aldehydes generated by the combustion process.
The fuel used by these plant furnaces is a mixture of various hydrocarbons in
gaseous and liquid form. The small quantity of aldehydes generated by combustion
of the fuels is present in an extremely low concentration in the flue gases.
No effective technique is known for the removal of aldehyde traces from flue
gases. The best procedure known for minimizing these emissions is to use
properly designed and maintained fuel burners and to use a small amount of
excess air above stoichiometric levels for combustion.
C. ETHYLBENZENE HYDROPEROXIDE PROCESS3
Table V-3 contains the controlled emissions data for the ethylbenzene hydro-
peroxide process model plant. The control techniques are discussed as follows:
1. Oxidation Reactor Scrubber Vent
The vent gas stream (Alf Fig. III-6) from the scrubbers on the oxidation reactors
vent is one of the larger VOC emission sources generated by this plant. The
principal organic material is ethylbenzene, along with other miscellaneous
reaction by-products. The model plant incorporates scrubbers on this emission
source to reduce the amount of hydrocarbons and carbonyl compounds in the vent
gas. These scrubbers could be considered as emission control devices in their
own right, but they are incorporated in the model plant design for safety and
economy (material recovery) purposes. The residual VOC in the vent stream is
extremely dilute and therefore difficult and expensive to remove. Thermal
oxidation is not effective at these low concentration levels. Selective adsorption
techniques, such as the use of activated carbon or molecular sieves, are the
-------
Table V-3. VOC Controlled Emissions for Model Plant Producing Propylene Oxide by the
Ethylbenzene Hydroperoxide Process (181 Gg/yr)
Emission Source
Stream
Designation
(Fig.III-6)
Control Device
or Technique
Total VOC
Emission Reduction
VOC Controlled Emissions
Catalyst mix tank vent
Separation column vent
Lights stripping column vent
Propylene recovery column vent
Product wash-decant system vent
Mixed HC wash-decant system vent
EB wash-decant system vent
EB stripping column vent
Light HC stripping column vent
a-MBArAP stripping column vent
Catalyst mix tank vent
Dehydration reactor system vent
Light impurities stripping column vent
Styrene finishing column vent
Hydrogenation reactor operating vent
Hydrogenation reactor activation vent
Fugitive
Storage and handling
Secondary
None
Pipe to fuel gas manifold 99
Pipe to fuel gas manifold 99
Pipe to fuel gas manifold 99
Fume gas scrubber 95
Plant flare 98
Plant flare 98
Plant flare 98
Plant flare 98
Plant flare 98
None
Plant flare 98
Plant flare 98
Plant flare 98
None
None
Ratio
(gAg)J
Trace
0.0016
0.0016
0.0016
0.000025
0.00003
0.00003
0.00003
0.00003
0.00016
Trace
0.00002
0.0248
0.0166
Not estimated
Not estimated
Not estimated
Rate
(kg/hr)
Oxidation reactor scrubber vent
FF evaporator vent
A. Selective adsorption
(activated carbon}
A Plant flare
80
98
0.32
0.000255
6.7
0.0055
Trace
0.0331
0.0331
0.0331
0.0005<
0.0006^
0.0006
0.0006
0.0006
0.0034
Trace
0.0004
0.514
0.344
0.367
7.67
See ref 3. g of emission per kg of propylene oxide produced.
-------
V-12
only known techniques that can function effectively at these dilution levels.
Depending on the adsorbent used and the equipment design, VOC emission reductions
of 80 to 95% could be achieved. Because the vent stream is large and has low
VOC concentration levels, the cost-benefit ratio for achieving significant
emission reduction by adsorption techniques is expected to be relatively high.
Activated-carbon adsorption is being piloted by one manufacturer, but results
are not yet available.4
2. FF Evaporator Vent
The vent stream from the vent (A2, Fig. 1II-6) on the FF (falling film) evaporator
is relatively small and contains very small amounts of VOC, principally ethylbenzenc
(EB). Adsorption and recovery techniques could be used to reduce VOC emissions from
this source, but the cost-benefit ratio would be extremely high. If a common
vent header leading to a thermal oxidation system (fume incinerator or flare)
were available to handle multiple vent streams, this small vent stream could be
piped to the common vent header as a technique for reducing the VOC emissions.
The small quantity of VOC in this vent stream would make the cost-benefit ratio for
even that technique relatively high. A flare efficiency of 95% has been assumed.
3. Catalyst Mix Tank Vent
The vent gas stream (A3, Fig. III-6) from the catalyst mix tank is extremely
small and contains only trace levels of VOC. principally ethylbenzene,- therefore
no emission control technique is suggested to reduce the VOC emissions.
4. Separation Column Vent
The vent gas stream (A4, Fig. III-6) from the separation column is relatively
small but is rich in C2 and C3 hydrocarbons. The technique suggested for control
of this vent emission is to pipe the vent stream to a common vent header that
is used as a fuel gas header to supply process furnaces with gaseous fuel. A
discharge pipe from this header could be installed to deliver any excess or
unused fuel gas to a thermal oxidizer syst'm (fume incinerator or flare). Thermal
combustion of this fuel-rich gas is expected to reduce VOC emissions by at least
99%. Cost-benefit ratios for this control technique are expected to be low (or
even negative) since use ot the gas as fuel eliminates the need to purchase
fuel for heating.
-------
V-13
5. Lights Stripping Column Vent
The gas stream from the vent (A5, Fig. III-6) on the lights stripping column is
similar in size and composition to the vent stream described in V-C-4. The VOC
emission control suggestions and comments in V-C-4 apply to this vent stream also.
6. Propylene Recovery Column Vent
This vent stream (A6, Fig. III-6) from the propylene recovery column is similar
in size and composition to the vent stream described in V-C-4. The VOC emission
control options described in V-C-4 also apply to this vent stream.
7. Product Wash-Decant System Vent
The stream from the vent (A7, Fig. III-6) on the product wash-decant system is
very small and has propylene oxide as the principal VOC. This vent gas can be
sent to a water scrubber, where the propylene oxide would be absorbed and even-
tually converted to a dilute aqueous solution of propylene glycol. A dedicated
water scrubber does not have to be provided for each vent containing PO, since
one larger sized scrubber can accommodate as many vent streams as can be conveni-
ently piped to one scrubber location. With a properly designed scrubber a PO
removal efficiency of 95% or better can reasonably be achieved. Since this VOC
emission source is very small, even piping the vent stream to a nearby water
scrubber that is installed to control other PO emission sources is expected to
show a very high cost-benefit ratio.
8. Mixed HC Wash-Decant System Vent
Since the stream from the vent (A8, Fig. III-6) on the mixed HC wash-decant system
is a very small one, with ethylbenzene vapor as the principal VOC, the only
reasonable VOC emission control technique is to pipe the vent stream to a common
vent header leading to a thermal oxidizer system, as described in V-C-2. Because
of the small amount of VOC in this vent stream, even the relatively low cost of
piping the vent gas to a common vent header is expected to show a very high cost-
benefit ratio. A flare efficiency of 98% is assumed.
9. EB Wash-Decant System Vent
The gas stream from the vent (A9, Fig. III-6) on the EB wash-decant system is
similar in size and composition to the vent stream described in V-C-8. The VOC
emission control option described in V-C-8 also applies to this vent stream.
-------
V-14
10. EB Stripping Column Vent
The EB stripping column vent (A10/ Fig. III-6) stream is similar in size and
composition to the vent stream described in V-C-8. The VOC emission control
option described in V-C-8 also applies to this vent stream.
11. Light HC Stripping Column Vent
The stream from vent AX1 (Fig. III-6) is similar in size and composition to the
vent stream described in V-C-8. Also, the VOC emission control option described
in V-C-8 is applicable to this stream.
12. a-HBA-AP Stripping Column Vent
The stream from vent A12 (Fig. III-6) on the a-MBA—AP stripping column is signifi-
cantly larger than the vent stream described in V-C-8 and contains a-methyl
benzyl alcohol (a-MBA) as the principal VOC. In spite of this difference this
vent stream is still very small, and the option given in V-C-8 on control of
VOC emissions also applies to this stream.
13. Catalyst Mix Tank Vent
The stream from the vent (A13, Fig. III-6) on this catalyst mix tank is extremely
small and contains only trace levels of VOC, principally a-MBA. No emission
control technique is suggested to reduce this extremely low level of VOC emissions.
14. Dehydration Reactor System Vent
The stream from vent A14 (Fig. III-6) on the dehydration reactor system is very
small and contains styrene monomer as the principal VOC. The VOC emission control
option given in V-C-8 applies to this stream also.
15. Light Impurities Stripping Column Vent
The stream from the stripping column vent (A15, Fig. III-6) is the largest vent
stream generated by the model plant and contains significant amounts of ethyl-
benzene and other VOC. The VOC concentration in this vent stream is relatively
low, but the total size of the vent stream brings the VOC emissions up to highly
significant levels. Several options are available for control of VOC emissions
from this source. Some of them are described below:
-------
V-15
(a) Use a common vent header to deliver the vent gas to a thermal oxidation
system (fume incinerator or flare) for destruction of the VOC. Fume incin-
erators usually operated at 99% efficiency or better, and flare efficiency
is estimated to be 98%. This approach is likely to show the lowest cost-
benefit ratio, especially when the possibility of feeding other small vent
streams into the common vent header is taken into consideration.
(b) Use a chilled lean-oil absorption system to scrub most of the VOC out of
the vent gas. The lean oil used as an absorption fluid must have a high
boiling point (low vapor pressure) to prevent significant levels of lean-oil
vapor from being added to the scrubbed vent gas. A side stream of a-MBA
and acetophenone (AP) mixture might make an effective scrubbing fluid,
since the vapor pressure of this process stream is relatively low. A further
advantage of using this process fluid is that the rich oil from the scrubber
could be returned to the process for recovery of absorbed vapors instead
of requiring a separate rich-oil stripping column. The cost-benefit ratio
for this approach is expected to be significantly higher than that for
option (a), unless the value of the recovered hydrocarbons is high enough
to offset the larger capital costs and operating expenses. Properly designed
and operated lean-oil scrubbing systems normally recover at least 95% of
the VOC from a vent stream of this type.
(c) Use a packed-bed adsorption system (such as activated carbon or molecular
sieves) to adsorb and remove the VOC. Use a twin-bed adsorption system to
permit periodic regeneration of the adsorption bed and recovery of the
adsorbed VOC. Adsorption systems of this type normally remove and recover
at least 95% of the VOC from a vent stream of this type. One problem with
this type of system is that styrene monomer in the vent gas might collect
and polymerize in the pores of the adsorbent. If this occurred, the adsorbent
material would become inactive and would have to be replaced with fresh
adsorbent material. It is expected tl.at this VOC emission reduction approach
would have a higher cost-benefit ratio than those for alternatives (b).
16. Styrene Finishing Column Vent
The stream from vent A16 (Fig. III-6) is almost as large as the vent stream
described in V-C-15 and is similar in composition; therefore the same control
options apply. The principal VOC in the stream is styrene monomer. The most
-------
V-16
sensible approach would be to combine both vent streams in one common vent
header and use a single emission control device (of larger scale) to control
both vent emissions.
17. Hydrogenation Reactor Operating Vent
The relief valve in this vent line (A17, Fig. III-6) is closed during normal
operation and no vent gas or VOC is normally discharged. Abnormal or emergency
conditions of reactor overpressure may occasionally create a vent gas discharge,
but would be very rare. No emission control device is suggested.
18. Hydrogenation Reactor Activation Vent
Periodic activation of the hydrogenation catalyst with a dilute stream of
hydrogen in nitrogen takes place to reestablish high levels of catalyst activity.
Since the hydrogenation reactor is thoroughly purged to remove residual hydrocarbons
prior to catalyst activation, the vent stream (A18, Fig. III-6) of hydrogen in
the nitrogen released during this periodic reactivation procedure does not
contain significant amounts of VOC; therefore no emission control device is
suggested.
D. OTHER PROCESSES
Since no other processes are currently being used domestically to produce
propylene oxide, no attempt has been made to estimate VOC emissions, sources,
or possible VOC emission control techniques for any other process.
E. FUGITIVE, STORAGE, AND SECONDARY EMISSIONS
Emission controls for fugitive storage, and secondary emissions are discussed
in separate reports6—8 that cover these emissions for the entire synthetic
organic chemicals manufacturing industry.
-------
V-17
F. REFERENCES*
1. C. W. Stuewe, IT Enviroscience, Inc., Trip Report for Visit to Dow Chemical Co.,
Plaquemine, LA, Nov. 16 and 17, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
2. Letter dated Oct. 5, 1979, from S. W. Fretwell, Oxirane Corp., Houston, TX,
to Carl A. Peterson, Jr., IT Enviroscience, Inc.
3. C. A. Peterson, IT Enviroscience, Inc., Trip Report for Visit to Oxirane Chemical
Co. (Channelview), Channelview, TX, Oct. 18, 1978 (on file at EPA, ESED, Research
Triangle Park, NC).
4. Letter dated Mar. 26, 1980, from S. W. Fretwell, Oxriane Corp., to J. R.
Farmer, EPA.
*When a reference number is used at the end of a paragraph or on a heading,
it usually refers to the entire paragraph or material under the heading.
When, however, an additional reference is required for only a certain portion
of the paragraph or captioned material, the earlier reference number may not
apply to that particular portion.
-------
VI-1
VI. IMPACT ANALYSIS
A. ENVIRONMENTAL AND ENERGY IMPACTS
Tables VI-1, VI-2, and VI-3 show the environmental impacts of reducing VOC emis-
sions from the model plants representing the three alternate domestic routes for
the manufacture of propylene oxide. The VOC emissions in each model plant were
reduced by the use of the applicable control systems as described in Section V.
From an energy standpoint, typical uncontrolled model plants will consume heat
in the range of 4.1 MJ/kg of product (chlorohydrination) through 14.9 MJ/kg of
product (ethylbenzene hydroperoxide) to a high value of 28.3 MJ/kg of product
(isobutane hydroperoxide). Corresponding electrical energy consumpton for
these three processes is estimated at 1.0 to 1.3 MJ/kg of product.1—3
Heat released to the environment as low-level thermal energy will contain all the
heat and electrical energy inputs listed above, in addition to the chemical energy
released as heat of reaction. Because of the large amount of energy consumed in
the manufacture of chlorine and caustic, the overall energy consumption (and
release to the environment) for propylene oxide manufacture by the chlorohydrin
process is actually higher than that for either of the hydroperoxide processes,
even though the listed values for direct process energy consumption do not reflect
this.
B. CONTROL COST IMPACT
No attempt has been made to assign or estimate capital or operating costs for
the various control techniques described in this abbreviated report. Quali-
tative value judgements as to the expected ranges of cost-benefit ratios for
the various control techniques have been inserted in the discussions on control
options presented in Section V.
-------
Table VI-1. Environmental Impact of Controlled Model Plant Producing Propylene Oxide by the
Chlorohydrination Process (68 Gg/yr)
Emission Source
Vent gas scrubber vent
Saponification cloumn vent
PO stripping column vent
Lights stripping column vent
PO final distillation column vent
DCP distillation column vent
DCIPE stripping column vent
Fugitive
Storage and handling
Secondary
Stream
Designation
(Fig.III-2)
Al
A2
A3
A4
A5
A6
A7
VOC Emission Reduction
Control Device
or Technique Percent
Upgrade purity of propylene 70
feedstock
Fume water scrubber 95
Fume water scrubber 95
Fume water scrubber 95
Fume water scrubber 95
Fume oil scrubber 90
None
Ratio
(q/kq) *
7.175
0.0408
0.0057
0.0057
0.0057
0.00009
Not estimated
Not estimated
Not estimated
7.234
Rate
(Mg/yr)
487.9
2.77
0.39
0.39
0.39
0.006
<
h-
I
N:
491.9
*g of emission per kg of propylene oxide produced.
-------
Table VI-2. Environmantal Impact of Controlled Model Plant Producing Propylene Oxide by the
Isobutane Hydroperoxide Process (417 Gg/yr)
Emission Source
Oxidation reactor scrubber vent
TBA stripping column vent
Catalyst mix tank vent
PO stripping column vent
Crude TBA recovery column vent
TBA vash-decant system vent
Wastewater stripping column vent
Solvent scrubber vent
Solvent recovery cclumn vent
Water stripping column vent
Propylene glycol column and dipro-
pylene glycol combined vent
Wastewater stripping column vent
Plant furnace flue gas vents
Fugitive
Storage and handling
Secondary
Stream
De s i gnat ion
(Fig.III-4)
Al
A2
A3
A4
A5
A6
A7
A8
A9
Aio
All
A12
A13
VOC Emission Reduction
Control Device
or Technique
Plant flare
Vent condenser
None
Fume water scrubber
Fume water scrubber
Plant flare
Vent condenser
Plant flare
Plant flare
Plant flare
Fume water scrubber
Vent condenser
None
Percent
98
60
95
95
98
80
98
98
98
95
80
Ratio
CgAg)*
1.725
0.0024
0.0176
0.0147
0.0069
0.760
0.617
0.0004
0.0012
0.0551
1.064
Not estimated
Not estimated
Not estimated
4.254
Rate
(Mq/yr)
719.3
1.0
7.3
6.1
2.9
316. 9<
M
257. 5w
0.17
0.51
23.0
443.7
1756
*g of emission per kg of propylene oxide produced.
-------
Table VT-3. Environmental Impact of Controlled Model Plant Producing Propylene Oxide by the
Ethylbenzene Hydroperoxide Process (181 Gg/yr)
Stream
Designation
Emission Source (Fig.III-6)
VOC Emission Reduction
Control Device
or Technique
Ratio
Percent (g/kg) *
Rate
(Mg/yr)
Oxidation reactor scrubber vent
FF evaporator vent
Catalyst mix tank vent
Separation column vent
Lights stripping column vent
Propylene recovery column vent
Product wash-decant system vent
Mixed HC wash-decant system vent
EB wash-decant system vent
EB stripping column vent
Light HC stripping column vent
a-MBA/RP stripping column vent
Catalyst mix tank vent
Dehydration reactor system vent
Light impurities stripping column vent
Styrene finishing column vent
Hydrogenation reactor operating vent
Hydrogenation reactor activation vent
Fugitive
Storage and handling
Secondary
e
Selective adsorption
(activated carbon)
Plant flare
None
Pipe to fuel gas manifold
Pipe to fuel gas manifold
Pipe to fuel gas manifold
Fume water scrubber
Plant flare
Plant flare
Plant flare
Plant flare
Plant flare
None
Plant flare
Plant flare
Plant flare
None
None
80
1.297
Not estimated
Not estimated
3.820
234.8
98
0
99
99
99
95
98
98
98
98
98
0
98
98
98
0
0
0.0048
0
0.1584
0.1584
0.1584
0.0005
0.0014
0.0013
0.0014
0.0014
0.0076
0
0.0008
1.2152
0.8134
0
0
Not estimated
0.9
0
28.7
28.7
28.7
0.1 <
M
0.3 i
0.2
0.3
0.3
1.4
0
0.1
219.9
147.2
0
0
691.4
-------
VI-5
REFERENCES*
K. E. Lunde, Propylene Oxide and Ethylene Oxide, Report No. 2, Process Economics
Program, Stanford Research Institute, Menlo Park, CA (nd).
Y. C. Yen, Propylene Oxide and Ethylene Oxide, Supplement A, Report No. 2A,
Process Economics Program, Stanford Research Institute, Menlo Park, CA (February
1967).
Y. C. Yen, Propylene Oxide and Ethylene Oxide, Supplement B, Report No. 2B, Process
Economics Program, Stanford Research Institute, Menlo Park, CA (February 1971).
*When a reference number is used at the end of a paragraph or on a heading,
it usually refers to the entire paragraph or material under the heading.
When, however, an additional reference is required for only a certain portion
of the paragraph or captioned material, the earlier reference number may not
apply to that particular portion.
-------
VII-1
VII. SUMMARY
Propylene oxide is manufactured domestically from purifijed (chemical-grade)
propylene by three separate processes. Each process uses propylene as the
common building block for attachment of oxygen to form propylene oxide but uses
different raw materials to accomplish this oxygen addition and generates differ-
ent by-products, co-products, and waste streams. These different by-products
and coproducts each have their own market and use patterns, and their market
and sale values are highly significant in the overall economics and growth
patterns for these three processes.
Domestic production of propylene oxide was estimated to be 927 Gg in 1978, with
the current estimated total capacity for propylene oxide now listed as 1344 Gg/yr,
giving an industrial utilization of nameplate capacity at 69%.
The principal domestic use for propylene oxide is in the manufacture of polyether
polyols used for the manufacture of urethane foams. Other uses for propylene
oxide include the manufacture of propylene glycol, dipropylene glycol, and
various glycol ethers.
A. PROCESS CHARACTERISTICS2—4
1. Chlorohydrination Process5
The chlorohydrination process is the oldest of the currently practiced domestic
processes for the manufacture of propylene oxide. When the manufacture of
ethylene oxide was converted from the old chlorohydrination process to the
newer direct oxidation process, the old chlorohydrination equipment became
available for conversion for use in the propylene oxide process. This availa-
bility of equipment has permitted the growth of the propylene oxide chlorohydrina-
tion process with relatively small capital expenditures.
The chlorohydrination process generates relatively small quantities of by-products
(principally dichloropropane and dichloroisopropyl/ether); so the successful
operation of this process does not depend on a large market being found for
co-products or by-products.
-------
VII-2
The chlorohydrination process consumes large quantities of chlorine and caustic
(or lime). Slightly more than 1 mole of chlorine (C12) and 2 moles of caustic
(NaOH) are consumed in the manufacture of 1 mole of propylene oxide, generating
slightly more than 2 moles of salt (NaCl) brine as a waste stream. Because of
this large consumption of chlorine and caustic, the overall chlorohydrination
process is an extremely extensive energy consumer, and the present high, and
rapidly rising, costs of energy are making the economics of this process less
attractive. Some smaller producers of propylene oxide using this process have
already shut down their plants, and other small producers may do the same in
the near future.
2. Isobutane Hydroperoxide Process6
The isobutane hydroperoxide process for the manufacture of propylene oxide is a
relatively new production route in which isobutane is oxidized to the hydro-
peroxide by purified oxygen. The hydroperoxide, in turn, is used to epoxidize
propylene to propylene oxide while forming the coproduct it-butyl alcohol (TBA).
Some t-butyl hydroperoxide is separated and purified as a coproduct for use
elsewhere as an effective oxidizer in the production of other valuable oxygen-
containing organic compounds. Approximately 2 moles of TBA are produced as a
co-product for each mole of propylene oxide manufactured by this process. Some
of this TBA is easily converted to isobutylene by passing the alcohol over a
dehydration catalyst.7
Isobutane is readily available as a sidestream from an integrated refinery, and
the price for purified isobutane is relatively low. Oxygen is readily separated
from the air in standard designed air separation plants. Chemical-grade propylen*
is readily available from many integrated petrochemical-refinery complexes at
standardized contract prices.
The co-products generated by the isobutane hydroperoxide process have a rapidly
expanding market that can absorb all the co-products without strain,- so manu-
facture of propylene oxide by this process is not limited by sales of the
co-products. At present a major and expanding use for TBA is for blending into
gasoline as an octane improver. Some TBA is used for chemical manufacture,
such as t-butyl chloride and _t-butyl phenol, etc. Some of the alcohol is being
-------
VI I-3
dehydrated to isobutylene, which can be reacted to form various alkylates
useful in gasoline or can be purified and used in the manufacture of butyl
rubber and polyisobutylene. A relatively new use for isobutylene is its reaction
with methanol to form methyl t-butyl ether, a relatively new gasoline octane
improver recently approved for use in unleaded gasoline.7'8
Ethylbenzene Hydroperoxide Process9
The ethylbenzene hydroperoxide process for the manufacture of propylene oxide
is the latest commercial production route in which ethylbenzene is oxidized to
the hydroperoxide by oxygen from the air. This hydroperoxide is then used to
epoxidize propylene to propylene oxide while forming the coproduct a-methyl
benzyl alcohol (a-MBA).
The a-MBA co-product does not have a large sales market, but it is dehydrated to
styrene monomer by contacting the alcohol with a dehydration catalyst. The
styrene monomer is then purified and sold to the large, well-established styrene
monomer market for conversion into thermoplastic resins, synthetic rubber,
latex emulsions, etc. A minor amount of acetophenone is produced as a by-product
during the hydroperoxide production step, and this material is separated and
reacted with hydrogen over a hydrogenation catalyst to convert the acetophenone
to additional a-MBA.
It would, perhaps, be more accurate to describe the ethylbenzene hydroperoxide
process as a process for the manufacture of styrene monomer with propylene
oxide as a co-product, since this process yields about 2.5 kg of styrene monomer
for each kg of propylene oxide produced. The major constraints on the production
of propylene oxide and styrene monomer by this process at the present time are
the availability and price of aromatic hydrocarbons (principally benzene and
toluene) from which ethylbenzene is produced. Petroleum feedstocks, particularly
those streams rich in aromatics, are in great demand for use in raising the
octane ratings of unleaded gasoline. Styrtne monomer is a relatively mature,
large-volume, commodity hydrocarbon, and its growth rate has been estimated at
4 to 6% in the 1976—1980 period, with production operating at about 78% of
total plant capacity due to aromatics supply shortages.10
-------
VII-4
B. PROCESS EMISSION CHARACTERISTICS
1. Chlorohydrination Process5
The chlorohydrin process has one large vent stream that contains 99% of the
process VOC emissions generated in the uncontrolled model plant (see Table IV-1).
The principal source of the VOC being released by this vent stream is the
propane contained in the chemical-grade propylene fed to the chlorohydrination
reactor. Dow has studied this emission source, and they state that the most
cost-effective technique for reducing the emission is to use high-purity (polymer*
grade) propylene as reactor feed, thereby eliminating most of the propane that
is released as VOC. Other techniques that could be used to reduce emissions
from this vent include thermal oxidation (fume incinerator or flare) or the use
of a lean-oil scrubbing system to absorb and recover the hydrocarbons from this
vent gas. Controlled versus uncontrolled emissions for this process are summarize
in Table VII-1.
2. Isobutane Hydroperoxide Process6
The isobutane hydroperoxide process has three fairly large vent streams that,
in total, contain over 96% of the process VOC emissions generated in the uncon-
trolled model plant (see Table IV-2). The first stream is emitted from the
scrubber system on the oxidation reactor, with the principal VOC being a mixture
of isobutane and TEA. The VOC is relatively dilute, with inert gases making up
over 75 wt % of the total stream. These inert gases (principally argon) enter
the oxidation reactor with the oxygen from the air separation plant and sweep
the organic vapors out of the oxidation reactor. Techniques that could be used
to reduce the VOC emissions from this vent include converting the TBA scrubber
to a lean-oil scrubber with associated recovery column, installing an activated-
carbon recovery system to adsorb and recover the VOC, or sending the vent gas
to a thermal oxidation system (fume incinerator or flare) to oxidize the VOC.
The second stream is emitted from the vent on the wastewater stripping column
used to strip isobutylene and TBA out of the wastewater generated by washing of
the product stream after dehydration of TBA to isobutylene. The VOC in this
vent consists principally of isobutylene, along with some lesser amounts of TBA
and acetone. Techniques that could be used to reduce the VOC emissions include
the use of a refrigerated vent condenser to recover most of the contained VOC
or the delivery of the vent gas to a thermal oxidation system (fume incinerator
or flare) to oxidize the VOC.
-------
Table VII-1. Emission Summary for Model Plant Producing Propylene Oxide by the
Chlorohydrination Process (68 Gg/yr)a
VOC Emissions
Emission Source
Vent gas scrubber vent
Saponification column vent
PO stripping column vent
Lights stripping column vent
PO final distillation column vent
DCP distillation column vent
DCIPE stripping column vent
Fugitive
Storage and handling
Secondary
Stream
Designation
(Fig.III-2)
Al
A2
A3
A4
A5
A6
A7
Uncontrolled
Control Device
or Technique
Upgrade purity of pro-
pylene feedstock
Fume water scrubber
Fume water scrubber
Fume water scrubber
Fume water scrubber
Fume oil scrubber
None
Ratio
(g/kg)b
10.25
0.043
0.006
0.006
0.006
0.0001
0.000004
10.31,
Rate
(kg/hr)
79.57
0.33
0.05
0.05
0.05
0.0008
. Controlled
Ratio
(g/kg)b
3.07
0.0021
0.0003
0.0003
0.0003
0.00001
0.00003 0.000004
Not
Not
Not
80.05
estimated
esitmated
estimated
3.087
Rate
(kg/hr)
23.87
0.017
0.0025
0.0025
0.0025
0.00008
0.00003
<
H
H
Ul
23.90
See ref 5.
Dg of emission per kg of propylene oxide produced.
-------
VII-6
The third stream is emitted from the vent on the wastewater stripping column
used to strip crude acetone out of the combined wastewater streams from the TEA
purification system and the dilute caustic scrubber on the vent of the oxidation
reactor. The VOC in the vent stream consists principally of acetone, along
with some isobutane and methanol. These VOC emissions may be controlled by
using a refrigerated vent condenser to recover most of the contained VOC. An
alternative technique that could be used is the delivery of the vent gas to a
thermal oxidizer system (fume incinerator or flare) for oxidation of the VOC.
Controlled versus uncontrolled emissions for this process are summarized in
Table VII-2.
Ethylbenzene Hydroperoxide Process9
The ethylbenzene hydroperoxide process has three moderately large vent streams
that, in total, contain over 84% of the process VOC emissions generated in the
uncontrolled model plant (see Table IV-3). The first stream comes from the
vent on the scrubber system used to recovery VOC from the oxidation reactor
vent gas. The VOC in this scrubber vent gas is extremely dilute, but the
amount of gas being vented is extremely large; therefore the total amount of
VOC in the stream is fairly large. Because this VOC is extremely dilute, the
only possible technique for its reduction is to use an adsorption technique
(activated carbon or molecular sieves) to remove and recover this VOC. Adsorp-
tion techniques for treating extremely dilute VOC in vent gas streams are quite
expensive because of high capital costs and large operating costs. It is
believed that cost-benefit ratios would be very high for any attempt to reduce
the VOC emissions from this scrubber system. An alternative approach that
might be attempted is the use of oxygen from an air separation plant in place
of air in the oxidation reactor, thereby radically reducing the amount of inert
gas being vented and reducing the contained VOC. This technique would be
extremely difficult and expensive to retrofit on an existing facility,- but, if
a new plant for the ethylbenzene hydroperoxide process were constructed, this
process change might be a relatively cost-f.ffective technique for reduction of
VOC emissions from this source.
The second and third large VOC emission sources are the vent gas exhausts on the
light impurities stripping column and the styrene finishing column. Both these
columns are located in the styrene finishing area and close to each other, as
well as being tied together operation-wise. The vent gases are relatively dilute,
but contain chemically similar VOC emissions (ethylbenzene and styrene monomer).
-------
Table VII-2.
Emission Summary for the Model Plant Producing Propylene Oxide by the
Isobutane Hydroperoxide Process (417 g/yr)a
VOC Emissions
Stream
Designation Control Device
Emission Source (Fig.III-4) or Technique
)xidation reactor scrubber vent
DBA stripping column vent
Catalyst mix tank vent
>O stripping column vent
:rude TEA recovery column vent
CBA wash-decant system vent
ffastewater stripping column vent
Solvent scrubber vent
Solvent recovery column vent
ffater stripping column vent
Propylene glycol column and dipro-
pylene glycol column combined vent
Wastewater stripping column vent
Plant furnace flue gas vents
Fugitive
Storage and handling
Secondary
Al
A2
A3
A4
A5
A6
A7
A8
A9
Aio
All
A12
A13
Plant flare
Vent condenser
None
Fume water scrubber
Fume water scrubber
Plant flare
Vent condenser
Plant flare
Plant flare
Plant flare
Fume water scrubber
Vent condenser
None
Uncontrolled
Ratio
(g/kg)b
1.76
0.004
0.000012
0.0185
0.0155
0.00174
0.95
0.63
0.00046
0.0013
0.058
1.33
0.040
4.81
Controlled
Rate Ratio
(kg/hr) (gAg)b
83.8
0.19
0.0352
0.0014
0.0006 0.000012
0.88
0.74
0.34
45.2
30.0
0.02
0.06
2.76
63.3
1.90
Not
Not
Not
229.17
0.00093
0.00078
0.00036
0.190
0.013
0.00001
0.00002
0.0029
0.266
0.040
estimated
estimated
estimated
0.551
Rate
(kg/hr)
1.676
0.114
0.0006
0.044
0.037
0.017
9.04^
H
0.60^
0.0004
0.0012
0.138
12.66
1.90
26.25
aSee ref 6.
bg of emission per kg of propylene oxide produced.
-------
VII-8
The most simple and most practical technique for reducing these VOC emissions
would be to tie the column vents together in one common vent header and direct
its output to a thermal oxidation system (fume incinerator or flare) for destruc-
tion of the contained VOC. A possible alternative technique might be the
installation of a refrigerated vent condenser on the vent header outlet to
recover contained VOC. Because of the dilution of the VOC in this vent stream,
it is believed that the use of a vent condenser would not remove as much VOC or
be as cost effective as a thermal oxidation system.
Controlled versus uncontrolled emissions for this process are summarized in
Table VII-3.
C. DATA BASE
The process emissions for the propylene oxide model plants are based on infor-
mation furnished by Dow Chemical Co.5 and by Oxirane Chemical Co.6'9 Also, the
process flowsheets were developed from published reports on propylene oxide by
Stanford Research Institute,1—4 along with an understanding of the process
chemistry and physical property data on the raw materials, intermediates,
products, coproducts, and by-products. No attempts were made to estimate
emissions due to fugitive, storage and handling, or secondary sources for this
abbreviated report.
D. INDUSTRIAL EMISSIONS ESTIMATE
Based on the estimated propylene oxide production of 985 Gg for 1979 and based on
the current capacity ratio of 746 Gg/yr by chlorohydrination, 417 Gg/yr by iso-
butane hydroperoxide, and 181 Gg/yr by ethylbenzene hydroperoxide, as well as
on information on current industry emission control practices, the total emission
of VOC during the manufacture of propylene oxide in 1979 was estimated to be
about 5.8 Gg. It is believed that over 95% of the total emissions were generated
by the chlorohydrination process, with the two hydroperoxide processes together
generating less than 5% of the total VOC eritted.
-------
Table VII-3. Emission Summary for Model Plant for Production of Propylene Oxide by the
Ethylbenzene Hydroperoxide Process (181 Gg/yr)a
VOC Emissions
Emission Source
Oxidation reactor scrubber vent
FF evaporator vent
Catalyst mix tank vent
Separation column vent
Lights stripping column vent
Propylene recovery column vent
Product wash-decant system vent
Mixed HC wash-decant system vent
EB wash-decant system vent
EB stripping column vent
Light HC stripping column vent
a MBA-AP stripping column vent
Catalyst mix tank vent
Dehydration reactor system vent
Light impurities stripping column
Styrene finishing column vent
Stream
Designation
(Fig. I I 1-6)
Al
A2
A3
A4
A5
A6
A7
A8
A9
A10
All
A12
A13
A14
vent AI _
Uncontrolled'
Control Device
or Technique
Selective adsorption
(activated carbon)
Plant flare
None
Pipe to fuel gas manifold
Pipe to fuel gas manifold
Pipe to fuel gas manifold
Fume water scrubber
Plant flare
Plant flare
Plant flare
Plant flare
Plant flare
None
Plant flare
Plant flare
Plant flare
Ratio
(g/kg)b
1.61
0.0051
Trace
0.16
0.16
0.16
0.0005
0.0015
0.0014
0.0015
0.0015
0.0080
Trace
0.0008
1.24
0.83
Rate
(kg/hr }
33.5
0.11
Trace
3.31
3.31
3.31
0.01
0.03
0.03
0.03
0.03
0.17
Trace
0.02
25.7
17.2
Controlled
Ratio
(g/kg)b
0.32
0.000255
Trace
0.0016
0.0016
0.0016
0.000025
0.00003
0.00003
0.00003
0.00003
0.00040
Trace
0.00002
0.0248
0.0166
Rate
(kg/hr)
6.7
0.0055
Trace
0.0331
0.03313
0.033li
0.0005
0.0006
0.0006
0.0006
0.0006
0.0085
Trace
0.0004
0.514
0.344
-------
Table VII-3. (Continued)
Stream
Designation Control Device
Emission Source (Fig.III-6) or Technique
Hydrogenat4.on reactor operating A^7 None
vent
Hydrogenation reactor activation Aig None
vent
Fugitive
Storage and handling
Secondary
VOC Emissions
Uncontrolled Controlled
Ratio Rate Ratio
(g/kg)b (kg/hr) (g/kg)b
Normally 0 Normally 0 0
Normally Q Normally 0 0
Not estimated
Not estimated
Not estimated
4.12 86.6 0.367
Rate
(kg/hr)
0
0.-
7.67
See ref 9.
3g of emission per kg of propylene oxide produced.
-------
VII-11
E. REFERENCES*
1- S. A. Cogswell, "Propylene Oxide," pp. 690.8021A—690.8023D in Chemical Economics
Handbook, Stanford Research Institute, Menlo Park, CA (July 1979).
2- K. E. Lunde, Propylene Oxide and Ethylene Oxide, Report No. 2, Process Economics
Program, Stanford Research Institute, Menlo Park,. CA (nd).
3. Y. C. Yen. Propylene Oxide and Ethylene Oxide.Supplement A, Report No. 2A,
Process Economics Program, Stanford Research Institute, Menlo Park, CA
(February 1967).
4. Y. C. Yen, Propylene Oxide and Ethylene Oxide. Supplement B, Report No. 2B,
Process Economics Program, Stanford Research Institute, Menlo Park, CA
(February 1971).
5. c. W. Stuewe, IT Enviroscience, Inc., Trip Report for Visit to Dow Chemical Co.,
Plaquemine, LA, Nov. 16 and 17, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
6. Letter dated Oct. 5, 1979, from S. W. Fretwell, Oxirane Corp., Houston, TX, to
Carl A. Peterson, Jr., IT Enviroscience, Inc.
7. S. L. Soder, "Butylenes," pp. 300.5600A—300.5604A in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park. CA (June 1979).
8. P. D. Sherman, Jr., "Butyl Alcohols," pp. B38-H345 in Kirk-Othmer Encyclopedia
of Chemical Technology, 3d ed., vol. 4, Exec. Editor, M. Grayson, Wiley, New York,
1978.
9. C. A. Peterson, IT Enviroscience, Inc., Trip Report for Visit to Oxirane Chemical
Co. (Channelview), Channelview, TX, Oct. 18, 1978 (on file at EPA, ESED, Research
Triangle Park, NC).
10. S. L. Soder, "Styrene," pp. 694.3051A—694.3053S in Chemical Economics Handbook.
Stanford Research Institute, Menlo Park, CA (January 1977).
*When a reference number is used at the end *n 3 paragraph or on a heading,
it usually refers to the entire paragraph cr material under the heading.
When, however, an additional reference is required for only a certain portion
of the paragraph or captioned material, the earlier reference number may not
apply to that particular portion.
-------
A-l
APPENDIX A
CO
Ul
£C
LU
OL
to
O
I
Ul
cc
D
cn
en
UJ
£C
O.
CC
O
Q.
o*c to" ao» so* «Q* atr «o" TO* so* »o« ioo'
IfoP *W
-------
B-l
Appendix B
EXISTING PLANT CONSIDERATIONS
A. EXISTING PLANT CHARACTERIZATION
Information has been received regarding control devices or techniques from the
following three manufacturers of propylene oxide,-
1- Chlorohydrination Process1
The Dow Chemical Co., Plaquemine, LA, has a nominal plant capacity of 154 Gg/yr
of propylene oxide. The information available on this plant is summarized in
Table B-l. This plant information is based on its 1977 configuration and capacity.
2. Isobutane Hydroperoxide Process2
Oxirane Corporation, Bayport, TX, has a nominal plant capacity of 417 Gg/yr of
propylene oxide. The information available on this plant is summarized in
Table B-2. This plant contains 10 different units built over a number of dif-
ferent years. The data presented represent the current technology of the newest
unit. In terms of air emissions the model plant contains several vent streams
that are not present in the Oxirane process.3
3. Ethylbenzene Hydroperoxide Process4
Oxirane Chemical Co., Channelview, TX, has a nominal plant capacity of 181 Gg/yr
of propylene oxide. The information available on this plant is summarized in
Table B-3. This plant was started up in 1977.
B. RETROFITTING CONTROLS
The control devices and techniques discussed in Sect. V may not be applicable
to existing plants. Retrofitting control devices or techniques into existing
plants brings up such questions as: Is there space in the existing plant to fit
in and install the new hardware required? Do the operating characteristics of
the emission control device fit the operating characteristics of the process
equipment? Are the operating characteristics and design limitations of the
control device compatible with the upset or emergency conditions that the process
might encounter? Are the startup and shutdown characteristics of the control
device compatible with the startup and shutdown requirements of the process?
Are extensive process modifications needed to accomplish significant emission
reductions? Where changes in feedstock or intermediates are needed to reduce
-------
Table B-l. Existing Plant for the Manufacture of Propylene Oxide by the
Chlorohydrination Process (154 Gg/yr)(Dow Chemical Co., Plaquemine, LA)a
Emission Source
Stream
Designation
(Fig. III-2)
VOC Emissions
Control Device
or Technique
Ratio
(g/kg)b
Rate
(kg/hr)
Vent gas scrubber vent
Saponification column vent
PO stripping column vent
Lights stripping column vent
PO final rlisti ] lotion column vent
DCP distillation column vent
DCIPE stripping column vent
Fugitive
Storage and handling
Combined in
report
Vent scrubber used to re-
move HC1 anc
device used
10.27
C12; no
Combined in
^5 / report
Vent scrubbers (packed
columns), with water
used as scrubbing fluid
(all vents directed to a
common vent header be-
fore control device)
Estimated fugitive losses
Vent scrubbers (packed •
column) with water used
as scrubber fluid
0.00031
0.0029
0.0059
See ref 1.
3g of emission per kg of propylene oxide produced.
180.5
0.054
CO
i
NJ
0.052
0.104
Secondary
Organic
liquid
wastes
Thermal ox-
idizer with
alkaline
water vent
scrubber
0.0059
10.29
0.104
180.8
-------
Table B-2. Existing Plant for the Manufacture of Propylene Oxide by the
Isobutane Hydroperoxide Process (417 Gg/yr)(Oxirane Corp., Bayport, TX)a
Stream
Designation
Emission Source _ (Fig.III-4)
Control " Device
or Technique
VOC Emissions
Ratio
-------
B-4
Table B-3. Existing Plant for the Manufacture of Propylene Oxide by the
Ethylbenzene Hydroperoxide Process (181 Gg/yr) (Oxirane Chemical Co., Channelview, TX)'
Emission Source
Stream
Designation
(Fig.III-6)
Control Device
or Technique
VOC Emissions
Ratio (g/kg) Rate (kg/hr)
Oxidation reactor
scrubber vent
FF evaporator vent A,
A
Catalyst mix tank A.
vent
Separation column A
vent
Lights stripping Ac
column vent
Propylene recov- A
ery column vent
Product wash-de- A
cant system vent
Mixed HC wash-de-
cant system vent
EB wash-decant
system vent
EB stripping
column vent
Light HC strip-
ping column
vent
a MBA-AP stripping
column vent
Catalyst mix tank
vent
Dehydration re-
actor system
vent
Light impurities
stripping col-
umn vent
Styrene finishing
column vent
t Combined
in re-
port
8
Oil scrubber and water
scrubber used to
control emissions
and recover pro-
duct
Plant flare
Plant fuel gas mani-
fold
Plant fuel gas mani-
fold
Plant fuel gas mani-
fold
Backpressure control
valve and nitrogen
pad
Backpressure control
valve and nitrogen
pad
Backpressure control
valve and nitrogen
pad
13
Combined Plant flare
in re-
port
None stated
A _ ^Combined
in re-
port
Plant flare
0.724
15.0
Flare emissions not stated
No emissions stated
No emissions stated
No emissions stated
Trace
Trace
Trace
Trace
Trace
Trace
Flare emissions not stated
None stated
Flare emissions not stated
16J
-------
B-5
Table B-3. (Continued)
Stream
Designation
Emission Source
-------
B-6
process emissions, are the changed feedstock or intermediates readily available
at reasonable prices? Specific comments on retrofitting controls to existing
processes are as follows:
1. Chlorohydrination Process
The one major retrofit operation most likely to fit this process is the con-
version from use of lower purity (chemical grade) propylene to the use of higher
purity (polymer grade) propylene. Both grades of propylene are available from
major propylene suppliers. The high-purity (polymer-grade) propylene commands
a premium price (usually about K/lb) over the lower purity (chemical-grade)
feedstock, but its use would reduce total plant emissions by at least 70%.
Specific supply situations at individual manufacturing plants would have to be
reviewed to see whether this approach is feasible for each producer using the
Chlorohydrination process.
An alternative approach would be the installation of a thermal oxidizer with an
alkaline vent gas scrubbing system to destroy the propane being vented from the
Chlorohydrination reactor. This equipment installation would have to be reviewed
to see whether it could be fitted into the existing plant.
2. Isobutane Hydroperoxide Process
Retrofitting control devices to existing plants using this process is likely to
be difficult. The first major emission source is the vent stream from the scrubbers
on the oxidation reactor. The simplest technique for control of this emission,
as currently practiced, is to pipe the vent gas to a thermal oxidizer system
(plant flare), with the oxidizer system assumed to have sufficient spare capacity
to handle this stream. Other techniques, such as conversion of the TEA scrubber
to a lean-oil absorption-recovery system, are likely to involve space (location)
problems, as well as being much more expensive.
The second large vent stream is emitted frc.n the vent on the wastewater stripping
column in the isobutylene conversion process. The simplest retrofit approach
for this vent, as currently practiced, is to collect the vent gas in a header
and feed it to a thermal oxidizer system (plant flare). Again to be successful,
the oxidizer system must have enough spare capacity to handle this vent gas
stream.
-------
B-7
The third large vent stream comes from the vent on the combined wastewater stripper.
Again, the simplest retrofit approach for this stream, as currently practiced,
is the installation of vent gas piping to the header of the plant thermal oxidizer
(plant flare).
Ethylbenzene Hydroperoxide Process
Emissions from the ethylbenzene hydroperoxide process are now being fairly well
controlled. The first major vent stream comes from the scrubbers on the oxi-
dation reactors, and the VOC in this vent gas is extremely dilute. Attempts to
retrofit an effective adsorption system on this vent gas stream are likely to
be very difficult and expensive. Any attempt to further improve the performance
of the existing vent gas scrubbers is also likely to be very difficult and expensive.
The second and third large VOC emission streams come from the vent on the vacuum
distillation columns in the styrene purification section. The current emission
control technique for these sources is to pipe the vent streams through a common
header to the plant thermal oxidation system (plant flare).
-------
B-8
C. REFERENCES*
1. C. W. Stuewe, IT Enviroscience, Inc., Trip Report for Visit to Dow Chemical Co.,
Plaquemine, LA, Nov. 16 and 17, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
2. Letter dated Oct. 5, 1979, from S. W. Fretwell, Oxirane Corp., Houston, TX,
to Carl A. Peterson, Jr., IT Enviroscience, Inc.
3. Letter dated Mar. 26, 1980, from S. W. Fretwell, Oxirane Corp., to J. R. Farmer,
EPA.
4. C. A. Peterson, IT Enviroscience, Inc., Trip Report for Visit to Oxirane Chemical
Co., Channelview, TX, Oct. 18, 1978 (on file at EPA, ESED, Research Triangle Park,
NC).
*When a reference number is used at the end of a paragraph or on a heading,
it usually refers to the entire paragraph or material under the heading.
When, however, an additional reference is required for only a certain portion
of the paragraph or captioned material, the earlier reference number may not
apply to that particular portion.
-------
2-i
REPORT 2
ACRYLONITRILE
J. A. Key
F. D. Hobbs
IT Enviroscience
9041 Executive Park Drive
Knoxville, Tennessee 37923
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
November 1980
This report contains certain information w'lich has been extracted from the
Chemical Economics Handbook, Stanford Research Institute. Wherever used, it has
been so noted. The proprietary data rights which reside with Stanford Research
Institute must be recognized with any use of this material.
D18I
-------
2-iii
CONTENTS FOR REPORT 2
Page
I. ABBREVIATIONS AND CONVERSION FACTORS I-1
II. INDUSTRY DESCRIPTION II-l
A. Reason for Selection II-l
B. Usage and Growth II-l
C. Domestic Producers II-l
D. References II-5
III. PROCESS DESCRIPTION III-l
A. Introduction III-l
B. Sohio Process III-l
C. Other Processes III-4
D. References III-6
IV. EMISSIONS IV-!
A. Sohio Acrylonitrile Process IV-1
B. Other Processes IV-7
C. References IV-8
V. APPLICABLE CONTROL SYSTEMS V-l
A. Sohio Acrylonitrile Process V-l
B. Other Processes V-4
C. References V-5
VI. IMPACT ANALYSIS VI-1
A. Control Cost Impact VI-1
B. Environmental and Energy Impacts VI-11
C. References VI-14
VII. SUMMARY VII-1
-------
2-v
APPENDICES OF REPORT 2
A. PHYSICAL PROPERTIES OF ACRYLONITRILE, ACETONITRILE, AND HYDROGEN
CYANIDE
B. AIR-DISPERSION PARAMETERS
C. FUGITIVE-EMISSION FACTORS
D. COST ESTIMATE SAMPLE CALCULATIONS
E. LIST OF EPA INFORMATION SOURCES
F. EXISTING PLANT CONSIDERATIONS
-------
2-vii
TABLES OF REPORT 2
Number Page
II-l Acrylonitrile Usage and Growth II-2
II-2 Acrylonitrile Capacity II-2
IV-1 Uncontrolled Emissions of Acrylonitrile and Total VOC from IV-3
Model Plant Using Sohio Process
IV-2 Model Plant Absorber Vent Gas Composition IV-4
IV-3 Model Plant Storage Parameters IV-6
V-l Acrylonitrile and Total VOC Controlled Emissions for Model V-2
Plant. Acrylonitrile by Sohio Process
VI-l Annual Cost Parameters VI-2
VI-2 Emission Control Cost Estimates for Acrylonitrile Model Plant VI-5
VI-3 Environmental Impact of Controlled Model Plant VI-12
VII-1 Emission Summary Model Plant VII-2
A-l Physical Properties of Acrylonitrile A_l
A-2 Physical Properties of Acetonitrile A-2
A-3 Physical Properties of Hydrogen Cyanide A-3
B-l Air-Dispersion Parameters for Model Plant B-l
F-l Control Devices Currently used by Domestic Acrylonitrile F-2
Industry
F-2 Emissions from Catalytic Oxidizers—Du Pont Beaumont Acrylonitrile F-3
Plant
F-3 Emissions from Thermal Oxidizers—Monsanto Chocolate Bayou F-5
Acrylonitrile Plant
-------
2-ix
FIGURES OF REPORT 2
Number
II-l Acrylonitrile Manufacturing Locations II-3
III-l Process Flow Diagram, Model Plant, Uncontrolled, Sohio III-2
Acrylonitrile Process
VI-1 Installed Capital Cost vs Plant Capacity for Emission VI-3
Control (Thermal OKidation)
VI-2 Net Annual Cost vs Plant Capacity for Emission VI-6
Control (Thermal Oxidation)
VI-3 Cost Effectiveness vs Plant Capacity for Emission Control Vl-7
(Thermal Oxidation)
VI-4 Installed Capital Cost vs Plant Capacity for Emission VI-8
Control (Flaring of Column Vent Gases)
VI-5 Net Annual Cost vs Plant Capacity for Emission Control VI-9
(Flaring of Column Vent. Gases)
VI-6 Cost Effectiveness vs Plant Capacity for Emission Control VI-10
(Flaring of Column Vent Gases)
D-l Precision of Capital Cost Estimates
D-l
-------
1-1
ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements used in agency documents in metric
units. Listed below are the International System of Units (SI) abbreviations
and conversion factors for this report.
To Convert From
Pascal (Pa)
Joule (J)
Degree Celsius (°C)
Meter (m)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter/second
(mVs)
Watt (W)
Meter (m)
Pascal (Pa)
Kilogram (kg)
Joule (J)
To
Atmosphere (760 mm Hg)
British thermal unit (Btu)
Degree Fahrenheit (°F)
Feet (ft)
Cubic feet (ft3)
Barrel (oil) (bbl)
Gallon (U.S. liquid) (gal)
Gallon (U.S. liquid)/min
(gpm)
Horsepower (electric) (hp)
Inch (in.)
Pound-force/inch2 (psi)
Pound-mass (Ib)
Watt-hour (Wh)
Multiply By
9.870 X 10"6
9.480 X 10"4
(°C X 9/5) + 32
3.28
3.531 X IO1
6.290
2.643 X 102
1.585 X 104
1.340 X 10~3
3.937 X 101
1.450 X 10~4
2.205
2.778 X 10~4
Standard Conditions
68°F = 20°C
1 atmosphere = 101,325 Pascals
PREFIXES
Prefix
T
G
M
k
m
M
Symbol
tera
giga
mega
kilo
milii
micro
Multiplication
Factor
IO12
33*
IO6
103
io"3
io"6
Example
1 Tg =
1 Gg =
1 Mg =
1 km =
1 mV =
1 vq =
1 X 10 12 grams
1 X IO9 grams
1 X 10G grams
1 X IO3 meters
1 X IO"3 volt
1 X 10~6 gram
-------
II-l
II. INDUSTRY DESCRIPTION
A. REASON FOR SELECTION
Acrylonitrile was selected for in-depth study because preliminary estimates
indicated that its manufacturing process causes higher estimated emissions of
volatile organic compounds (VOC) than any other process in the synthetic organic
chemicals manufacturing industry. The growth rate for the production of acrylo-
nitrile is expected to be higher than the industry average. Acrylonitrile is
highly toxic and has been declared to be a potential carcinogen.
Acrylonitrile is a liquid under ambient conditions but is sufficiently volatile
for gaseous emissions to occur during production (see Appendix A for pertinent
properties). The emissions from acrylonitrile production consist of propane,
propylene, acetonitrile, acrylonitrile, and hydrogen cyanide. Propane and pro-
pylene account for about 86% of the total emissions.
B. USAGE AND GROWTH
Table II-l shows acrylonitrile end uses and the expected growth rates. The pre-
dominant use for acrylonitrile is in the production of acrylic fibers, mainly for
the apparel industry. Other major end uses of acrylic fiber include carpeting
2
and home furnishings, e.g., blankets, draperies, and upholstery.
The domestic acrylonitrile production capacity was 980,000 Mg/yr at the end of
1977. Production was 754,600 Mg in 1977, or about 77% of capacity. Operating
capacity was reduced to 900,000 Mg/yr early in 1978, when one producer shut down
3
a unit and another reportedly increased capacity a small amount. Demand will
exceed current capacity by 1981 if an anticipated growth rate of 8% is realized.'
C. DOMESTIC PRODUCERS
Four producers were operating six acrylonitrile plants in 1977. Table II-2 lists
the producers with their 1977 capacities, ^nd Fig. II-l shows the plant loca-
tions.
Ammoxidation of propylene accounts for all current domestic production of acrylo-
nitrile, although catalytic reaction of acetylene and hydrogen cyanide was used
as a production method until late 1970. Other processes that have been used
commercially include catalytic dehydration of ethylene cyanohydrin and catalytic
-------
II-2
Table II-l. Acrylonitrile Usage and Growth"
Percent of Average Annual
End Use Production (1977) Growth (1977-1980) (%)
Acrylic fibers 67.2 7
Acrylonitrile-butadiene-styrene 19.7 8
copolymer (ABS) and styrene-
acrylonitrile polymer (SAN)
resins
Nitrile elastomers 5.6 4
Miscellaneous 7.5 24
See ref 3.
b
Includes adiponitrile, acrylamide, nitrile barrier resins, and other products.
Table II-2. Acrylonitrile Capacity
1977 Capacity
Plant (X 103 Mg/yr)
Cyanamid, New Orleans, LA 109
Du Pont, Beaumont, TX 159
Du Pont, Memphis, TN 136
Monsanto, Alvin, TX 204
Monsanto, Texas City, TX 191
Vistron, Lima, OH 1G1
Total 980
a ,- _
See ref 6.
Cyanamid's capacity was reportedly increased to 120 X 10 Mg/yr in 1978
(ref 5) . '
Q
Monsanto brought their Texas City plant or.-stream in 1977.
-------
II-3
1. American Cyanamid, New Orleans, Louisiana
2. Dupont Co., Beaumont, Texas
3. Dupont Co., Memphis, Tennessee
4. Monsanto Co., Alvin, Texas
5. Monsanto Co., Texas City, Texas
6. Vistron, Lima, Ohio
Fig. II-l. Acrylonitrile Manufacturing Locations
-------
II-4
reaction of propylene with nitric acid. Ammoxidation of propane for producing
acrylonitrile has been tested on a pilot-plant scale.
Companies that produce acrylonitrile are listed below:
1. Cyanamid
All acrylonitrile produced at the New Orleans plant is used captively in the
n
5
production of acrylic fibers and acrylamide. Capacity was reported to have
increased to 120,000 Mg/yr in 1978.'
2. Du Pont
Plants in Beaumont, Texas, and Memphis, Tennessee, produce acrylonitrile for
2,3
captive use in the manufacture of acrylic fibers and barrier resins.
2
Some of the acrylonitrile is marketed.
3. Monsanto
Monsanto expanded their acrylonitrile capacity by bringing a new plant
on-stream at Texas City, Texas, in 1977. The acrylonitrile is used cap-
tively in the production of acrylic fibers, acrylonitrile butadiene styrene
2 3
plastics, adiponitrile, and barrier resins. '
4. Vistron (SOHIO)
The Lima, Ohio, plant has a capacity of 181,000 Mg/yr, with 45,000 Mg of
that amount being produced by older equipment, which can be used or placed
on standby, depending on the market. The acrylonitrile is used captively
2 3
in the production of acrylamide and barrier resins and is also sold.
-------
II-5
D. REFERENCES*
1. I. Schwartz, "Environment — Facing Up to Acrylo Problems," Chemical Week, pp.
38-40 (June 22, 1977).
2. J. L. Blackford, "Acrylonitrile," pp. 607.5031B--607.5032S in Chemical Economics
Handbook, Stanford Research Institute, Menlo Park, CA (June 1974).
3. D. A. Olson, "Acrylonitrile," Chemical Engineering Progress 73(11), 42—45 (1977)
4. "Monsanto Shuts Down Acrylonitrile Plant," Chemical and Engineering News 56(3),
13 (1978). —
5. J. L. Blackford, "CEH Marketing Research Report on Acrylonitrile," p. 607.5932E
in Chemical Economics Handbook, Stanford Research Institute, Menlo Park, CA
(May 1978).
6. "Chemical Profile on Acrylonitrile," p.9 in Chemical Marketing Reporter, Jan. 10,
1977.
*Usually when a reference is located at the end of a paragraph, it refers to the
entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When the
reference appears on a heading, it refers to all the text covered by that head-
ing.
-------
Ill- 1
III. PROCESS DESCRIPTION
A. INTRODUCTION
All domestic acrylonitrile is produced by the ammoxidation of propylene by the
SOHIO process, which is predominant worldwide although other processes are used
by some foreign producers. Over 95% of the world's installed capacity for
acrylonitrile production uses the ammoxidation of propylene; and all new capac-
2
ity, either planned or under construction, will use ammoxidation of propylene.
B. SOHIO PROCESS
1. Basic Process
Acrylonitrile is produced by the following chemical reaction:
CH2=CH-CH3 + NH3 + 3/2 02 * CH2=CH-CN + 3^0
(Propylene) (Ammonia) (Oxygen) (Acrylonitrile) (Water)
The process flow diagram shown in Fig. III-l represents a typical process.
Air, ammonia, and propylene (Streams 1, 2, and 3) are fed to a gas fluid-bed
catalytic reactor that operates at 135 to 310 kPa and 400 to 510°C. The reactor
temperature is controlled by internal cooling coils, which generate about 75% of
the process steam required by the plant. The remainder is generated in a waste
heat boiler, where the gases from the reactor (Stream 4) are cooled from 510 to
230°C. The cooled reactor gases (Stream 5) are further cooled in the quench
neutralizer, and the ammonia and catalyst fines are removed. The quenched and
neutralized reactor gases (Stream 6) go to the absorber, where acrylonitrile,
acetonitrile, and hydrogen cyanide (HCN) are recovered by absorption in water,-
4 5
the absorber vent gas (Vent A) is vented to the atmosphere or to a control device. '
The absorber bottoms (Stream 7) go to a recovery column, where crude acrylo-
nitrile (Stream 8) is separated from crude acetonitrile (Stream 9) and sent to
the crude acrylonitrile storage. The crude acetonitrile (Stream 9) goes to the
acetonitrile column for separation of the water (Stream 10), which is then recy-
cled to the absorber; the dried acetonitrile (Stream 11) goes overhead and is
4—6
sent to the acetonitrile purification column for final purification.
-------
I
r-o
Fig. III-l. Process Flow Diagram for Uncontrolled
SOHIO Acrylonitrile Process for Model Plant
-------
III-3
A portion of the quench water (Stream 12) from the quench neutralizer is sent to
the wastewater column, where volatile organics (Stream 13) are separated by steam
stripping and are recycled to the quench neutralizer. The bottoms from the
wastewater column (Stream 14), which contain some of the catalyst, ammonium sul-
fate, and heavy organics, are sent to the deep-well pond along with the bottoms
from the acetonitrile column (Stream 15) and from the acetonitrile purification
column (Stream 16). The overhead from the acetonitrile purification column
(Stream 17) goes to acetonitrile storage and can be sold if it meets specifica-
tions. If there is no demand for acetonitrile or if it is off-specifications, it
is sent (Stream 18) to an incinerator.
Crude acrylonitrile (Stream 19) is separated by the light-ends column into the
light ends (Stream 20), which are sent to the HCN column; the acrylonitrile
bottoms (Stream 21) go to the product column. There the heavy impurities
(Stream 22) are removed from the product acrylonitrile (Stream 23). The heavy
impurities (Stream 22) are disposed of in the incinerator.
The light ends (Stream 20) sent to the HCN column are separated into hydrogen
cyanide (HCN) (Stream 24), which can be sold if it meets sales specifications,
and the bottoms (Stream 25), which are recycled as a portion of the feed to the
light-ends column. The HCN that does not meet specifications or that cannot be
sold because of lack of demand (Stream 26) goes to the incinerator for disposal.
The wastewater sent to the deep-well pond contains ammonium sulfate, catalyst
fines, organic polymers, and other organics. After the solids settle out in the
deep-well pond, the runoff is injected into deep wells. ' '
The absorber gas from Vent A is the largest emission and contains the following:
unreacted oxygen and nitrogen from the air (Stream 1), which is fed as a react-
ant; any propane and unreacted propylene from the propylene feed (Stream 3); the
carbon dioxide and carbon monoxide formed by side reactions; and acrylonitrile,
acetonitrile, hydrogen cyanide, and other organics carried with the nitrogen from
the absorber. Other emissions are the vent gases (Vents B) from the various
columns: recovery, acetonitrile, acetonitrile purification, light-ends, product,
and HCN.3'4'6
-------
III-4
Storage emission sources (Vents C through G) include crude acrylonitrile, hydro-
gen cyanide, acetonitrile, and acrylonitrile storage. Handling emissions (Vents H
through L) result from loading HCN, acetonitrile, and acrylonitrile into railroad
tank cars and acrylonitrile into barges.
Fugitive emissions (N) occur when leaks develop in valves or in pump or compressor
seals and when relief valves open to relieve a pressure buildup. When the proc-
ess pressures are higher than the cooling-water pressure, acrylonitrile and other
organics can leak into the cooling water and escape as fugitive emissions from
the cooling tower.
Secondary emissions occur when the waste streams, such as the product column
bottoms and any unsalable acetonitrile or HCN, are burned in an incinerator
(Vent P). Another source of secondary emissions (Q) is the evaporation of
organics from the deep-well pond.
2. Process Variations
When HCN and acetonitrile are not recovered for sale, the HCN column, HCN stor-
age, HCN loading, acetonitrile purification column, acetonitrile storage, and
acetonitrile loading are eliminated and the light ends plus the crude acetonitrile
are sent directly to the incinerator fof disposal. As another process variation,
only the HCN may be recovered for internal use or for sale. Some variations in
3,4
the arrangement of the columns in the purification section are also possible.
Catalyst 41 is currently used, rather than Catalyst 21, by all domestic acrylo-
nitrile producers. Catalyst 41 reduces the emissions from the absorber vent gas
4
(Vent A). A new acrylonitrile catalyst developed and used by Nitto Chemical
Industry Company, Ltd., of Japan (licensed to SOHIO for marketing) achieves high
purity and product yield and low by-product yield but is not used in the United
States.
C. OTHER PROCESSES
Although acrylonitrile has been produced domestically by the addition of hydrogen
cyanide to acetylene, the reaction of propylene with nitric oxide, and the dehydra
tion of ethylene cyanohydrin prepared from ethylene oxide, all domestic plants
using these processes have been shut down. The ammoxidation of propane, rather
-------
III-5
than propylene, has been studied on a pilot scale only and, unless the economics
of the process become more favorable, will not likely be widely used.
Other processes for the ammoxidation of propylene are used overseas and differ
from the SOHIO process mainly in the use of a fixed-bed reactor (except for the
Montedison-UOP process, which employs a fluidized-bed catalytic reactor) and a
different catalyst system. The catalyst system used by the Montedison-UOP proc-
ess reportedly reduces the by-products produced and therefore could reduce the
emissions from the incinerator. Two plants have been built that use this process
127
but no data are available on the absorber vent emissions. ' '
-------
III-6
D. REFERENCES*
1. J. L. Blackford, "Acrylonitrile," pp. 607.5032B — 607.5032D in Chemical Economics
Handbook, Stanford Research Institute, Menlo Park, CA (May 1978).
2. P. R. Pujado, B. V. Vora, and A. P. Krueding, "Newest Acrylonitrile Process,"
Hydrocarbon Processing 56(5). 169-172 (May 1977).
3. W. A. Schwartz et al.. Engineering and Cost Study of Air Pollution Control
for the Petrochemical Industry Volume 2: Acrylonitrile Manufacture,
EPA-450/3-73-006-b, Research Triangle Park, NC (February 1975).
4. T. W. Hughes and D. A. Horn, Source Assessment: Acrylonitrile Manufacture
(Air Emissions), EPA-600/2-77-107, Research Triangle Park, NC (September 1977).
5. "Acrylonitrile (SOHIO Process)," Hydrocarbon Processing 56(11), 124 (November 1977).
6. J. A. Key, IT Enviroscience, Inc., Trip Report for E. I. duPont de Nemours & Company,.
Inc., Beaumont, TX, Sept. 7, 1977 (on file at EPA, ESED, Research Triangle
Park, NC)..
7. "Acrylonitrile," Hydrocarbon Processing 56(11) 125 (1977).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on a heading, it refers to all the text covered by that
heading.
-------
IV-1
IV. EMISSIONS
Emissions in this report are usually identified in terms of volatile organic
compounds (VOC). VOC are currently considered by the EPA to be those of a
large group of organic chemicals, most of which, when emitted to the atmosphere
participate in photochemical reactions producing ozone. A relatively small
number of organic chemicals have low or negligible photochemical reactivity.
Hovever, many of these organic chemicals are of concern and may be subject to
regulation by EPA under Sections 111 or 112 of the Clean Air Act since there
are associated health or welfare impacts other than those related to ozone
formation. It should be noted that although ethane is included in VOC emission
totals in this report, it does not, based on current research data, participate
in ozone-forming reactions to an appreciable extent.
A. SOHIO ACRYLONITRILE PROCESS
1. Model Plant
The model plant* for this study has an acrylonitrile capacity of 180,000 Mg/yr,
based on 3760 hr of operation annually.** It also produces 21,&00 Mg/yr of
hydrogen cyanide (HOT) and 5,000 Mg/yr of acetonitrile as by-products, which
are sold or incinerated, depending on the market demand. For this study the
model plant incinerates 8640 Mg of HCN and 5,000 Mg of acetonitrile per year
because of lack of demand. The SOHIO process for ammoxidation of propylene
(Fig. III-l) using catalyst 41 best represents today's acrylonitrile manufac-
turing and engineering technology. Two reactors and quench neutralizers .feeding
a single recovery and purification train is typical for plants built recently.
Typical raw material, intermediate, product and by-product storage tank capac-
ities were estimated for a 180,000-Mg/yr plant. Storage tank requirements are
given in Sect. IV.A.2.C. Estimates of potential fugitive sources, based on
*See p 1-2 for a discussion of model plants.
**Process downtime is normally capected to range from 5 to 15%. If the hourly
production rate remains constant, the annual production and annual VOC emissions
will be correspondingly reduced. Control devices will usually operate on the
same cycle as the process. Therefore, from the standpoint of cost effectiveness
calculations, the error introduced by assuming continuous operation is negligible.
-------
IV-2
data from existing facilities, are given in Sect. IV.A.2.d. Characteristics of
the model plant that are important in air-dispersion modeling are given in
Table B-l in Appendix B.
2. Sources and Emissions
The process emissions estimated for the acrylonitrile model plant are based on
emissions reported in response to EPA's requests for information from selected
companies, the Du Pont and Vistron trip reports, studies by Houdry and Monsanto
for EPA, SRI information, and understanding of the process chemistry and yields.
Emission rates and sources for the SOHIO acrylonitrile process are summarized
in Table IV-1.
a- Absorber Vent — The absorber vent gas (Vent A, Figure III-l) contains nitro-
gen and unreacted oxygen from the air fed to the reactor; propane and unreacted
propylene from the propylene feed; and product acrylonitrile, by-product hydro-
gen cyanide (HCN), acetonitrile, other organics not recovered in the absorber,
and some water vapor. Table IV-2 shows the composition of this stream for the
model plant. The composition of the absorber vent gas depends on the catalyst,
reactor conditions, propylene purity, production rate, and absorber operating
conditions. One plant has reported acrylonitrile emissions from their absorber
vent that are equivalent to 30 times those from the model plant.2'3 The acrylo-
nitrile emissions of the model plant are meant to represent typical emissions
from a well-designed and operated SOHIO process. The propane and propylene
emissions are approximately 90% of the volatile organic compounds (VOC) in the
vent gas (see Table IV-2). The amount of propane is directly proportional to
the amount of propane in the propylene feed, assumed to be 5 wt % for the model
plant, since propane is not converted in the reactor.
During startup of a reactor the reactor product by-passes the quench neutralizer
and absorber, or the absorber only, for a short period of time. The startup
emission rate and composition change durir»g this time. The emissions during
startups are estimated in Table IV-1 as yearly averaged values, based on four
startups of each of two reactors each year and each startup lasting for 1 hr.
b. Column Vents -- The vent gases from the recovery, acetonitrile, acetonitrile
purification, light-ends, HCN, and product columns (Vents B, Fig. III-l) are
-------
IV-3
Table IV-1. Uncontrolled Emissions of Acrylonitrile and
Total VOC from Model Plant Using SOHIO Process
Source
Absorber vent, normal
b
Absorber vent, startup
Column vents
Storage vents
Crude acrylonitrile
Acetonitrile
Hydrogen cyanide
Acetonitrile run tanks
Acrylonitrile storage
Handling
., c
Hydrogen cyanide
Acetonitrile
Acrylonitrile
Acrylonitrile
Fugitive
Secondary
incinerator
Deep-well pond
Total
ag of emission per kg of
^Average rate for entire
°By tank car.
dBY barge.
Stream
Designation
(Fig. Ill-l)
A
A
B
C
D
F
G
H
J
K
L
N
P
Q
acrylonitrile
Emission Ratio Emission Rate
(g/kg) a (kg/hr)
Acrylonitrile
0.10
0.187
5.00
0.048
0.128
0.531
0.167
0.150
0.806
7.07
produced.
year, based on 8 startups per
Total VOC Acrylonitrile
100.0 2.05
0.249 3.84
10.00 103.00
0.048 0.986
0.021
0.041
0.128 2.62
0.531 10.9
0.026
0.167 3.44
0.150 2.16
1.65 16.6
0.360
13.00
126. 146.
year lasting 1 hour each.
Total VOC
2050
5.11
205.00
0.986
0.43
0.842
2.62
10.9
0.54
3.44
2.16
33.9
7.40
267.00
2590.
-------
IV-4
Table IV-2. Model-Plant Absorber Vent Gas Composition
Component
Acrylonitrile
Acetonitrile
Hydrogen cyanide
Propane
Propylene
Ethane
Other VOC
Total VOC
Inert gases (N2/ 02/ CO2/ H20, CH4)
Carbon monoxide
Total
Amount
(wt %)
0.001
0.025
0.002
0.759
0.375
0.038
0.050
1.250
97.25
1.50
100.
Emission Ratio
(g/kg) a
0.1
2.0
0.2
60.7
30.0
3.0
4.0
100.0
7780.0
120.0
8000.
a
g of emission per kg of acrylonitrile produced.
-------
IV-5
the noncondensibles that are dissolved in the feed to the columns, the VOC that
are not condensed, and, for the columns operated under vacuum, the air that
leaks into the column and is removed by the vacuum jet systems. An estimate
was made on the quantity of these emissions as the available data are scarce
and vary widely.6'7'12
Storage and Handling Emissions — Emissions result from the storage and handling
of acrylonitrile and by-product and intermediate streams. Sources for the
model plant are shown in Fig. III-l (Sources C through L). Storage tank param-
eters for the model plant are given in Table IV-3. The calculated emissions in
Table IV-1 are based on fixed-roof tanks, half full, and an 11°C diurnal tempera-
ture variation. Emission equations from AP-42 were used with one modification.
The breathing losses were divided by 4 to account for recent evidence that the
7 8
AP-42 breathing-loss equation overpredicts emissions. '
Propylene and ammonia are stored in pressure tanks and are not vented. The
only emissions are from relief valves, which are covered as fugitive sources
in the following section (d). For the model plant both propylene and ammonia
are received via pipe lines.
HCN boils at 26°C and is stored in a refrigerated tank at 0°C in the model
plant. It may also be stored in a pressure tank, with the vapors condensed by
refrigeration at -8 to 0°C. noncondensibles and associated HCN from storage
and handling are normally incinerated.
Emissions from loading of acrylonitrile and HCN in railroad tank cars and from
loading approximately 45% of the acrylonitrile in barges were calculated by use
of the equations from AP-42 and are shown in Table IV-1. The emission from
loading acetonitrile is shown as 0 to agree with the assumption that all of the
by-product acetonitrile is burned (see Sect, e, "Secondary Emissions"). At
4 5
least two plants sell some of the by-product acetonitrile produced. '
Fugitive Emissions — Process pumps, compressors, and valves are potential
sources of fugitive emissions. The model plant is estimated to have the
following equipment:
-------
Table IV-3. Model-Plant Storage Parameters
Content
Propylene (4 tanks)
Ammonia (4 tanks)
Crude acrylonitrile
Acrylonitrile (2 tanks)
Acrylonitrile (2 tanks)
Hydrogen cyanide (2 tanks)
Acetonitrile
Tank Size
(m3)
320
190
2500
380
5680
190
380
Turnovers
Per Year
345
194
6
294
20
83
61
Bulk Liquid
Temperature (°C)
21
21
27
27
27
0
27
Vapor
Pressure (kPa)
1050
890
16.4
16.4
16.4
35.2
12.9
S
-------
IV-7
Pumps in light-liquid service 50
Pipeline valves in gas/vapor service 200
Pipeline valves in light-liquid service 1000
Safety/relief valves in gas/vapor service 80
Compressor seals 2
Half of the pumps, the pipeline valves in both gas/vapor and light-liquid
service, and the safety/relief valves handle acrylonitrile. The fugitive-emission
factors from Appendix C were applied to this valve and pump and compressor seal
count, and the total is shown in Table IV-1 as fugitive emissions.
e. Secondary Emissions -- Secondary VOC emissions can result from the handling and
disposal of process-waste liquid streams. Two potential sources (P and Q) are
indicated in Fig. III-l for the model plant.
The emissions from the incinerator (Source P) were estimated on the assumption
that all of the product column bottoms (Stream 22) and by-product acetonitrile
(Stream 18) goes to the incinerator but that only 40% of the by-product HCN
(Stream 26) is incinerated, with the
the emissions are shown in Table IV-1.
(Stream 26) is incinerated, with the rest being loaded in railroad tank cars;
The emissions from the deep-well pond were estimated from the factors reported
by Monsanto Research Corp. for the sampling program performed for EPA, and are
shown in Table IV-1.
OTHER PROCESSES
No data are available on emissions from other ammoxidation processes or from
processes used previously for production of acrylonitrile.
-------
IV-8
C. REFERENCES*
1. D. A. Olson, "Acrylonitrile," Chemical Engineering Progress 73(11), 42--4S
(1977). —
2. Responses to EPA requests for information on acrylonitrile emissions; see
Appendix E.
3. T. W. Hughes and D. A. Horn, Source Assessment: Acrylonitrile Manufacture
(Air Emissions), EPA-600/2-77-107J, Research Triangle Park, NC (September
1977).
4. J. A. Key, IT Enviroscience, Inc. Trip Report to Beaumont Works, E. I. du Pont
de Nemours & Co., Beaumont, TX, Sept. 7, 1977 (on file at EPA, ESED,
Research Triangle Park, NC).
5. J. A. Key, IT Enviroscience, Inc., Trip Report to Vistron Corp., Lima, OH,
Oct. 4, 1977 (on file at EPA, ESED, Research Triangle Park, NC).
6. W. A. Schwartz et al., Engineering and Cost Study of Air Pollution Control
for the Petrochemical Industry. Volume 2; Acrylonitrile Manufacture,
EPA-450/3-73-006-b, Research Triangle Park, NC (February 1975).
7. C. C. Nasser, "Storage of Petroleum Liquids," p. 4.3-13 in Compilation of Air
Pollutant Emission Factors, AP-42, 3d ed., EPA, Research Triangle Park, NC
(August 1977).
8. E. C. Pulaski, letter from TRW to Richard Burr (EPA), May 30, 1979.
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on a heading, it refers to all the text covered by that
heading.
-------
V-l
V. APPLICABLE CONTROL SYSTEMS
A. SOHIO ACRYLONITRILE PROCESS
1. Absorber Vent
Absorber vent gases can be thermally oxidized to effectively control the acrylo-
nitrile and VOC in them; however, because of the large percentage of nitrogen
and other noncombustible gases normally present, supplemental fuel must be
added to ensure proper combustion. A portion of this supplemental fuel can be
the liquid-organic waste and by-products from the acrylonitrile recovery and
purification that are not sold. However, even though the thermal oxidizer is
designed to burn all the liquid-organic waste and by-product acetonitrile and
HCN produced, additional supplemental fuel is required. A reduction of 99% in
acrylonitrile and VOC emissions was used for calculation of the controlled
emissions from the model-plant thermal oxidizer that originated in the absorber
vent (see Table V-l).1'2
Catalytic oxidation can also control the acrylonitrile and VOC emissions from
the absorber vent, although significant destruction of the propane in the
emissions has not yet been achieved.3 It is believed that a catalytic system
can be developed to destroy propane, as well as the other VOC.4
No control has been identified for the emissions from the absorber vent during
startup when the vent gases go from air to fuel in a short time. Startup
emissions can be minimized by being sent through the absorber before they are
vented; this requires an absorber for each reactor. '6 The calculated uncontrol-
led emissions from reactor startup are shown in Table V-l. These emissions
reflect a yearly average based on eight reactor startups, each lasting for
1 hr.
2. Column Vents
The emissions from the column vents can be controlled by incineration in a
flare or by scrubbing. ' For the model plant a flare with a tip pressure drop
of 3 in. of water was selected to provide low back pressure to the columns to
-------
Table V-l. Acrylonitrile and Total VOC Controlled Emissions for
Model-Plant Acrylonitrile by SOHIO Process
Source
Absorber vent (normal)
(startup)
Column vents
Storage vents
Crude acrylonitrile
Hydrogen cyanide
Acetonitrile
Acrylonitrile run tanks
Acrylonitrile storage
Handling
Hydrogen cyanide
Acetonitrile
Acrylonitrile
Acrylonitrile
Fugitive
Secondary
Incinerator
Deep-well pond
Total
Stream
Designation
(Fig. III-2)
A
A
B
C
D
E
F
G
H
J
K
I,
N
P
Q
Control Device
or Technique
Thermal oxidizer
Flare
Water scrubber
Flare
Water scrubber
Water scrubber
Water scrubber
Flare
Water scrubber
Hater scrubber
Hater scrubber
Detection and correction
of major leaks
None
Lube oil cover
Emission
Reduction
99 (or greater)
99 tor greater)
99
99 (or greater)
99
99
99
99 (or greater)
99
99
99
71
0
92
Emission Ratio
(g/kg)a
Acrylonitrile
0.0010
0.187
0.0500
0.00048
0
0
0.00128
0.00531
0
0
0.0017
0.0011
0.238
0
0
0.300
Total VOC
1.00
0.249
0.100
0.00048
0.00041
0.00021
0.00128
0.00531
0.00026
0
0.0017
0.0011
0.487
0.360
1.100
3.31
Emission Rate
Ckg/hr)
Acrylonitrile
0.0205
3.84
1.03
0.00986
0
0
0.0262
0.109
O
0
0.0344
0.0216
4.88
0
0
9.97
Total VOC
20.5
5.11
2.05
0.0098G
0.00842
0.0043
0.0262
0.109
O.O054
0
0.0344
0.0216
10.0
7.40
22.6
67.9
ag of emission per kg of acrylonitrile produced.
bAverage rate for entire year, based on 8 startups per year lasting 1 hour each. No control has been identified for startup emissions.
°By tank car.
By barge.
-------
V-3
prevent upsets. A reduction of 99%* was used in the calculations of the controlled
emissions that originated in the column vents (see Table V-l), based on smokeless
operation of the flare and the gas flow to the flare at greater than 10% of the
maximum flow.
3. Storage and Handling Sources
Controls for storage and handling emissions from the synthetic organic chemical
g
manufacturing industry are discussed in a separate EPA report. The following
controls for the storage and handling emissions from the model plant were
selected based on demonstrated use in acrylonitrile plants. ' ' Floating-roof
tanks are also used in some services to control storage emissions, with a
reported reduction of greater than 95%.
a. Crude Acrylonitrile Storage — Emissions from the model plant crude acrylonitrile
storage vents are controlled by water scrubbers. A reduction of 99% was used
in the calculations of the controlled emissions from the crude acrylonitrile
storage (see Table V-l).
b. Hydrogen Cyanide Storage and Handling — Emissions from all HO* storage and
loading vents in the model plant are controlled by a separate flare. A refri-
gerated vent condenser can also be used for recovery of HCN from the vent gases
before they are sent to the flare.
A reduction of 99%* of the VOC to the flare was used to calculate the controlled
emissions resulting from the flaring of HCN storage and loading vent gases (see
Table V-l).7
c. Acetonitrile Storage and Handling — Emissions from acetonitrile storage and
handling in the model plant are controlled by a water scrubber. A removal
efficiency of 99% was used to calculate the controlled emissions from acetoni-
trile storage and railroad tank-car loading (see Table V-l), based on reported
field experience.
*Flare efficiencies have not been satisfactorily documented except for specific
designs and operating conditions using specific fuels. Efficiencies cited are
for tentative comparison purposes.
-------
V-4
d. Product Acrylonitrile Storage and Handling — In order to prevent cross contam-
ination of the product, the model plant has a separate water scrubber for control
of emissions from the product acrylonitrile storage and handling. Field experience
indicates that a removal efficiency of 99% can be achieved with a water scrubber;
this efficiency factor was used for calculation of the controlled emissions from
the scrubber.
4. Fugitive-Emission Sources
Controls for fugitive emissions from the synthetic organic chemicals manufac-
12
turing industry are discussed in another EPA document. Emissions from pumps
and valves can be controlled by an appropriate leak-detection system and repair
and maintenance as needed. Controlled fugitive emissions calculated with the
factors given in Appendix C are included in Table V-l; these factors are based
on the assumption that major leaks are detected and repaired.
5. Secondary Sources
a. Incinerator -- The VOC emissions caused by burning of the liquid-organic waste
streams are estimated to be the same when they are burned as a portion of the
supplemental fuel to the thermal oxidizer (see Sect. V.A.I.) as when they are
burned in the incinerator, and this quantity is shown in Table V-l. No data
are available on the emissions caused by burning the liquid-organic wastes in
the thermal oxidizer.
b. Deep-Well Pond — Control on the secondary emissions from the deep-well pond is
a layer of lubrication oil on the water. The controlled emissions from the
deep-well pond were calculated with the emission factors given by Monsanto in
their report on measured emissions.
B. OTHER PROCESSES
Data are not currently available concerniag control devices for other aimnoxi-
dation processes nor for the previously used processes for production of acrylo-
nitrile .
-------
V-5
C. REFERENCES*
1. Responses to EPA requests for information on acrylonitrile emissions; see
Appendix E.
2. J. W. Blackburn, IT Enviroscience, Inc., Control Device Evaluation. Thermal
Oxidation, (July 1980) (EPA/ESED report, Research Triangle Park, NC).
3. J. A. Key, IT Enviroscience, Inc., Trip Report To Beaumont Works, E. I. du Pont
de Nemours & Co., Beaumont, Texas, Sept. 7, 1977 (on file at EPA, ESED, Research
Triangle Park, NC).
4. W. R. Chalker, E. I. Du Pont de Nemours & Co., letter dated Feb. 6, 1979, to
D. R. Patrick, EPA, with comments on the draft report Acrylonitrile.
5. M. A. Pierle, Monsanto Chemical Intermediates Co., letter dated Mar. 16, 1979,
to D. R. Patrick, EPA, with comments on draft report Acrylonitrile.
6. M. A. Pierle, Monsanto Chemical Intermediates Co., letter dated Aug. 10, 1979,
to D. C. Mascone, EPA, with information on startup emissions from acrylonitrile
plants.
7. V. Kalcevic, IT Enviroscience, Inc., Control Device Evaluation. Flares and
the Use of Emissions as Fuels (in preparation for EPA, ESED, Research Triangle
Park, NC).
6. D. G. Erikson, IT Enviroscience, Inc., Storage and Handling (September 1980)
(EPA/ESED report, Research Triangle Park, NC).
g. J. A. Key, IT Enviroscience, Inc., Trip Report to Vistron Corp., Lima, Ohio,
Oct. 4, 1977 (on file at EPA, ESED, Research Triangle Park, NC).
jO. Responses to Texas Air Control Board 1975 Emission Inventory Questionnaire; see
Appendix E.
jj. Responses to Louisiana Air Control Commission 1975 Emission Inventory
Questionnaire; see Appendix E.
J2. D. G. Erikson and V. Kalcevic, IT Enviroscience, Inc., Fugitive Emissions
(September 1980) (EPA/ESED report, Research Triangle Park, NC).
l3> T. W. Hughes and D. A. Horn, Source Assessment; Acrylonitrile Manufacture (Air
Emissions), EPA-600/2-77-107; Research Triangle Park, NC (September 1977).
^Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on a heading, it refers to all the text covered by that
heading.
-------
VI-1
VI. IMPACT ANALYSIS
A. CONTROL COST IMPACT
This section gives estimated costs and cost-effectiveness data for control of
acrylonitrile and total VOC emissions resulting from the production of acrylo-
nitrile. Details of the model plant (Fig. III-l) are given in Sects. Ill and IV.
Cost-estimate sample calculations are included in Appendix D.
Capital cost estimates represent the total investment required to purchase and
install all equipment and material required to provide a complete emission con-
trol system performing as defined for a new plant at a typical location. These
estimates do not include the cost of acrylonitrile production lost during instal-
lation or startup, research and development, or land acquisition.
Bases for the annual cost estimates for the control alternatives include utili-
ties, operating labor, maintenance supplies and labor, recovery credits, capital
charges, and miscellaneous recurring costs such as taxes, insurance, and admini-
strative overhead. The cost factors used are itemized in Table VI-1.
1. Sohio Acrylonitrile Process
a. Absorber Vent — The estimated installed capital cost of a thermal oxidizer
designed to reduce by 99% or greater the acrylonitrile and total VOC from the
adsorber vent is $3,400,000 when recuperative heat recovery is used or is
$4,000,000 when the heat is recovered by steam being generated in a waste-heat
boiler. These costs are based on a thermal oxidizer that is designed for a
residence time of 0.75 sec at 870°C, is completely installed, and is equipped to
burn liquid wastes plus supplemental natural-gas fuel. See Appendix D for the
cost-estimate sample calculations for a thermal oxidizer, based on a complete
installation as described in the control device evaluation report on thermal
oxidizers.
The vent gas rate varies directly with the production rate; therefore a plant
with half the capacity of the model plant will require a thermal oxidizer with
half the capacity of one for the model plant. Figure VI-1 was plotted to show
the variation of installed capital cost of a thermal oxidizer, both with recupera-
tive heat recovery and with a waste-heat boiler, versus plant capacity.
-------
VI-2
Table Vl-1. Annual Cost Parameters
Operating factor
Operating labor
Fixed costs
Maintenance labor plus
materials, 6%
Capital recovery, 18%
Taxes, insurances,
administration charges, 5%
Utilities
Process water
Electric power
Steam
Natural gas
Heat recovery credits
(equivalent to natural gas)
8760 hr/yrc
$15/man-hr
29% of installed capital cost
$0.07/m ($0.25/thousand gal)
$8.33/GJ ($0.03/kWh)
$5.50/Mg ($2.50/thousand Ib or
million Btu)
$1.90/GJ ($2.00/thousand ft
million Btu)
$1.90/GJ ($2.00/million Btu)
or
Process downtime is normally expected to range from 5 to 15%. If the hourly
rate remains constant, the annual production and annual VOC emissions will be
correspondingly reduced. Control devices will usually operate on the same
cycle as the process. From the standpoint of cost-effectiveness calculations,
the error introduced by assuming continuous operation is negligible.
b
Based on 10-year life and 12% interest.
-------
VI-3
CTi
a.1
u
QJ
O
o
O
c
*
o
o
o
CJ
OJ
tr
c
— (a
ao 90 100
200
300
400
Plant Capacity (Gg/yr)
{a} Thermal oxidizer with recuperative heat recovery
(b) Thermal oxidizer with waste-heat boiler
Fig. VI-1. Installed Capital Cost vs. Plant Capacity for
Emission Control (Thermal Oxidation)
-------
VI-4
To determine the cost effectiveness of the thermal oxidizer, estimates were made
of the gross annual operating cost for both recuperative heat recovery and a
waste-heat boiler. The liquid wastes were given a value equal to that for the
natural gas replaced. The recovery credit was calculated for the waste-heat
boiler case, and the net annual cost for each case was calculated (see Table VI-2).
Figure VI-2 shows the variation of net annual cost with plant capacity for both
cases. The cost effectiveness for each case for controlling both acrylonitrile
and total VOC was calculated from the net annual cost and the emission reduction
(see Table VI-2). The variation in cost effectiveness with plant capacity of the
thermal oxidizer with recuperative heat recovery and with a waste-heat boiler
and for both acrylonitrile and total VOC is shown in Fig. VI-3.
b. Column Vents — The vent gases from the columns (Vent B, Fig. III-l) are con-
trolled by a flare with an estimated installed capital cost of $48,000 (see
Table VI-2). The variation of the estimated installed capital cost of the flare
with plant capacity is shown in Fig. VI-4. The basis for these estimates is the
installation of a complete flare system as described in the control device evalua-
tion report on flares. The estimated annual costs and the cost effectiveness
for VOC and acrylonitrile emission control are given in Table VI-2. Figure VI-5
is a plot of net annual cost of the flare system vs plant capacity, and curves a
and b of Fig. VI-6 show the variation of cost effectiveness with plant capacity
for acrylonitrile and for total VOC emission control.
c. Storage and Handling — The control systems for storage and handling emissions
are water scrubbers or flares. Another EPA report covers storage and handling
emissions and their applicable controls for all the synthetic organic chemicals
manufacturing industry.
d. Fugitive Sources — A control system for fugitive sources is defined in Appendix C.
Another EPA report covers fugitive emissions and their applicable controls for
4
all the synthetic organic chemicals manufacturing industry.
e. Secondary Sources — No control system has been identified for controlling the
secondary emissions from the incinerator. It may be possible to design and
operate the thermal oxidizer so that burning the waste organic liquids in it will
result in a reduction of secondary emissions, compared with burning them in an
older and perhaps less efficient incinerator.
-------
Table VI-2. Emission Control Cost Estimates for Acrylonitrile Model Plant
Total
(B) (C)
Annual Operating Costs Emission Cost
installed (A) Reduction Ef fectiveness
Emission Control Device Capital Gross Recovery Net Acrylonitrile Total VOC (per M?)
Source or Technique Cost Annual Credits Annual (Hg/yr) (Mg/yr) (%) Acrylonitrile Total VOC
Absorber vent Thermal oxidizer $3,400,000 $1,286,000 $1,286,000 18 18,000 99 $71,000 $71
with recuperative
heat recovery
Thermal oxidizer 4,000,000 5,888,000 4,400,000 1,488,000 18 18,000 99 83,000 83
with waste-heat
boiler
Column vents Flare 48,000 24,000 24,000 890 1,800 99 27 13
a(C) - (A) T (B).
H
I
(jn
-------
VI-6
c
c
o
«,
c
c
o
tc
O
u
c
C
01
Z
- (b)
I
80 90
100
200
300
Plant Caoacitv (S
(a) Thermal oxidizer with recuperative heat recovery
(b) Thermal oxidizer with waste-heat boiler
Fig. VI-2. Net Annual Cost vs. Plant Capacity for
Emission Control (Thermal Oxidation)
-------
VI-7
110,000
100,000 —
80 90 100
200
300
Plant Capacity (Gg/yr)
(a) Thermal oxidizer with recuperative heat recovery, acrylonitrile
(b) Thermal oxidizer with recuperative heat recovery, total VOC
(c) Thermal oxidizer with waste-heat boiler, acrylonitrile
(d) Thermal oxidizer with waste-heat boiler, total VOC
Fig. VI-3. Cost Effectiveness vs. Plant Capacity for Emission Control
(Thermal Oxidation)
-------
CTi
r-
VI-8
70
0)
u
Q)
Q
60
•M
C
ra
,-H
OH
O
O
c
50
D.
id
u
13
0)
40
in
c
30
I 111
80 90 100
200
300
400
Plant Capacity (Gg/yr)
Fig. VI-4. Installed Capital Cost vs. Plant Capacity for
Emission Control (Flaring of Column Vent Gases)
-------
VI-9
o
o
o
en
-u
in
o
u
(0
3
4J
fl)
40
30 -
20 _
10 -
80 90
100
200
300
Plant Capacity (Gg/yr)
Fig. VI-5. Net Annual Cost vs. Plant Capacity for
Emission Control (Flaring of Column Vent Gases)
-------
VI-10
£*
CO-
w
0)
c
o
U
0)
W
O
U
10 _
80 90 100
200
300
Plant Capacity (Gg/yr)
(a) Acrylonitrile
(b) Total VOC
Fig. VI-6. Cost Effectivei -iss vs. Plant Capacity
for Emission Control (Flaring of Column Vent Gases).
-------
VI-11
The emissions from the deep-well pond are controlled by means of a layer of oil
maintained on the surface. Insufficient data are available at this time to
estimate the annual costs or cost effectiveness of this technique.
2. Other Processes
Data are available only for the Sohio process for producing acrylonitrile by the
ammoxidation of propylene. No data are available for other processes, which
include the addition of hydrogen cyanide to acetylene, the reaction of propylene
with nitric acid, the dehydration of ethylene cyanohydrin prepared from ethylene
oxide, and the ammoxidation of propane.
„ ENVIRONMENTAL AND ENERGY IMPACTS
D -
, Sohio Acrylonitrile Process
Table VI-3 shows the environmental impact of reducing acrylonitrile and total VOC
emissions by application of the described control systems to the model plant.
From an energy standpoint a typical uncontrolled acrylonitrile plant will require
only electrical power since enough steam is produced by the process to drive the
compressor and meet process steam requirements. ' The electrical power require-
ments are estimated to be approximately 500 kJ/kg of acrylonitrile. Individual
impacts are discussed below.
Absorber Vent — The thermal oxidizer reduces acrylonitrile emissions from the
& • — ~ ------
absorber vent by 18 Mg/yr and total VOC emissions by 18,000 Mg/yr for the model
plant. The thermal oxidizer uses natural gas as supplemental fuel, steam to
atomize the liquid-organic wastes, and electric power for the blowers, lighting,
and instruments. The total energy required to operate the thermal oxidizer is
approximately 59 GJ/hr when recuperative heat recovery is used and is 320 GJ/hr
when the heat is recovered by steam being generated in a waste-heat boiler. The
liquid organic wastes supply about 42 GJ/hr of the total energy for both cases.
For the waste-heat boiler case the steam produced is equivalent to about 260 GJ/hr.
Column Vents — The flare system reduces acrylonitrile by 890 Mg/yr and total VOC
from these sources by 1800 Mg/yr for the model plant. Generation of NO , CO, and
X
smoke from flaring these emissions can have a negative impact on the environment
if steam injection is not controlled carefully to ensure complete combustion.
-------
Table VI-3. Environmental Impact of Controlled Model Plant
Source
Absorber vent
Normal
Startup
Column vents
Storage vents
Crude acrylonitrile
Hydrogen cyanide
Acetonitrile
Acrylonitrile run tanks
Acrylonitrile storage
Hand ling
Hydrogen cyanide
Acetonitrile
a
Acrylonitrile
b
Acrylonitrile
Fugitive
Secondary
Incinerator
Deep— well pond
Total
Stream No.
(Fig. III-2)
A
A
B
C
D
E
F
G
H
J
K
L
N
P
Q
Control Device
or Technique
Thermal oxidizer
None
Flare
Water scrubber
Flare
Water scrubber
Water scrubber
Water scrubber
Flare
Water scrubber
Water scrubber
Water scrubber
Detection and cor-
rection of major
leaks
None
Lube oil cover
. _„. Emission Reduction (Mg/yr)
Reduction (%) Acrylonitrile
99 (or greater) 18
99 (or greater) 890
99 8.6
99 (or greater)
99
99 23.
99 95.
99 (or greater)
99
99 30.
99 19.
71 100.
92
1200.00
Total VOC
18,000
1,800
8.6
7.3
3.7
23.
95. <
H
to
4.7
30.
19.
210.
2,100
22,000
By tank car.
By barge.
-------
VI-13
Natural gas is required for the pilot lights, and steam is used to ensure smokeless
operation; the total energy required is approximately 500 MJ/hr. The electrical
energy required for the flare system instruments and controls is negligible.
- Other Emissions (Storage and Handling, Fugitive and Secondary) — Control methods
I* - •* "" ~* * -* •"•
described for these sources are water scrubbers and a flare for storage and
handling emissions, correction of major leaks for fugitive emissions, and main-
tenance of a lubricating oil cover on the deep-well pond for secondary emissions.
Application of these systems results in an acrylonitrile reduction of 280 Hg/yr
and a VOC reduction of 2500 Mg/yr for the model plant.
The" use of a lubricating oil cover on the deep-well pond for emission control
does not consume energy and has no adverse environmental or energy impacts.
2 Other Processes
Emission control systems for other acrylonitrile processes have not been des-
cribed.
-------
VI-14
C. REFERENCES*
1. J. W. Blackburn, IT Enviroscience, Inc., Control Device Evaluation. Thermal
Oxidation, (July 1980) (EPA/ESED report. Research Triangle Park, NC).
2. V. Kalcevic, IT Enviroscience, Inc., Control Device Evaluation. Flares and
the Use of Emissions as Fuels (in preparation for EPA, ESED, Research Triangle
Park, NC).
3. D. G. Erikson, IT Enviroscience, Inc., Storage and Handling (September 1980)
(EPA/ESED report, Research Triangle Park, NC).
4. D. G. Erikson and V. Kalcevic, IT Enviroscience, Inc. Fugitive Emissions
(September 1980) (EPA/ESED report, Research Triancle Park, NC).
5. P. R. Pujado, B. V. Vora, and A. P. Krueding, "Newest Acrylonitrile Process,"
Hydrocarbon Processing 56(5), 169--172 (1977).
6. W. A. Schwartz e_t al, Engineering and Cost Study of Air Pollution Control for
the Petrochemical Industry. Volume 2: Acrylonitrile Manufacture,
EPA-450/3-73-006-b, Research Triangle Park, NC (February 1975).
*Usually, when a reference is located at the end of a paragraph, it refers to the
entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When the
reference appears on a heading, it refers to all the text covered by that
heading.
-------
VI I-1
VII. SUMMARY
Acrylonitrile is produced in the United States exclusively by the ammoxidation of
propylene by the SOHIO process. Processes in which other raw materials are used
are no longer in operation, and any new capacity will probably be based on the
ammoxidation of propylene process.
The annual growth rate of acrylonitrile production is estimated to be 8%. The
domestic acrylonitrile capacity available in 1977 will be sufficient to meet the
growth rate through 1980. No shortage of either propylene or ammonia is expected
2
during this period.
Emission sources and uncontrolled and controlled emission rates for the model
plant are given in Table VII-1. The current emissions projected for the domestic
acrylonitrile industry based on the estimated degree of control existing in 1980
are 1080 Mg/yr for acrylonitrile and 56,700 Mg/yr for total VOC. These emission
estimates were based on engineering judgement and data from individual acryloni-
trile producers, state and local emission control agencies, and the open literature.
The following individual estimated projections were made:
1980 Emissions (Mq/yr)
Source Acrylonitrile VOC
Process 230 51,000
Storage and handling 650 700
Fugitive 200 400
Secondary 0 4,600
Totals 1080 56,700
The predominant emission points are the absorber vent and the column vents.
Emissions from the absorber vent were estimated assuming 5% propane in the propyl-
ene fed to the reactor. Because propane passes through unreacted, the purity of
1J. L. Blackford, "Acrylonitrile," pp. 607.5032B--607.5032D in Chemical Economics
Handbook, Stanford Research Institute, Menlo Park, CA (May 1978).
2D. A. Olson, "Acrylonitrile," Chemical Engineering Progress TJJ(ll), 42—45
(1977). —
3P. R. Pujado, B. V. Vora, and A. P. Krueding, "Newest Acrylonitrile Process,"
Hydrocarbon Processing 56(5), 169—172 (1977).
-------
VII-2
Table VII-1. Emission Summary Model Plant
Emission Rate (kg/hr) _
Emission Source
Absorber vent
Normal
Startup
Column vents
Storage vents
Crude acrylonitrile
Hydrogen cayanide
Acetonitrile
Acrylonitrile run tanks
Acrylonitrile storage
Handling
Hydrogen cyanide
Acetonitrile
Acrylonitrile
Acrylonitrile
Fugitive
Secondary
Incinerator
Deep-well pond
Total
Uncontrolled
Acrylonitrile VOC
2.05 2050
3.84 5.11
103 205
0.986 0.986
0.842
0.43
2.62 2.62
10.9 10.9
0.54
3.44 3.44
2.16 2.16
16.6 33.9
7.40
267
146 2590
Controlled
Acrylonitrile VOC .
0.0205 20.5
3.84 5.11
1.03 2.05
0.00986 0.00986
0.00842
0.0043
0.0262 0.0262
0.109 0.109
0.0054
0.0344 0.0344
0.0216 0.216
4.88 10.0
7.40
22. 6_
9.97 67.9
X
-------
VI I-3
the propylene has a signficant effect on the quantity of VOC out the absorber vent.
The vent gases from the absorber vent can be controlled by a thermal oxidizer, which
will reduce both the acrylonitrile and total VOC emissions by 99% or greater. The
installed cost of a thermal oxidizer for the model plant is $3.4 million with recupera-
tive heat recovery and is $4.0 million with heat recovery by use of a waste-heat
boiler. Supplemental fuel is required and liquid-organic waste can be burned in the
thermal oxidizer to supply a portion of the supplemental fuel needed. The cost effec-
tiveness for acrylonitrile is $71,000/Mg controlled and for total VOC is $71/Mg if
recuperative heat recovery is installed. With heat recovery by use of a waste-heat
boiler the cost effectiveness for acrylonitrile is $83,000/Mg or $83/Mg for total VOC.
Emissions from storage and handling vents can be controlled by water scrubbers for
acrylonitrile and acetonitrile and by sending HCN to the flare system.
Secondary emissions from the deep-well pond are significant but can be controlled by
maintaining a lubricating oil layer on the surface of the pond, reducing the VOC
emissions by 92%.
-------
A-l
APPENDIX A
Table A-l. Physical Properties of Acrylonitrile*
Synonyms 2-Propenenitrile, vinyl cyanide
Molecular fomula <'^H3N
Molecular weight 53.06
Physical state Liquid
Vapor pressure 113.8 mm Hg at 25°C
Vapor specific gravity 1.83
Boiling point 77.5°C
Melting point -83 to -84°C
Density 0.8060 g/ml at 20°C/4°C
Water solubility 7.3 wt % at 70°C
*
J. Dorigan ert ad, "Acrylonitrile," p. AI-40 in Scoring of Organic Air Pol-
lants. Chemistry, Production and Toxicity of Selected Synthetic Organic
Chemicals (Chemicals A-C), MTR-7248, Rev 1, Appendix I, MITRE Corp.,
McLean, VA (September 1976).
-------
A-2
Table A-2. Physical Properties of Acetonitrile*
Synonyms
Molecular fomula
Molecular weight
Physical state
Vapor pressure
Vapor specific gravity
Boiling point
Melting point
Density
Water solubility
Methyl cyanide, ethanenitrile, cyanomethane,
ethyl nitrile, methane carbonitrile
C2H3N
41.05
Liquid
92.8 mm Hg at 25°C
1.42
81.6°C
-45.72°C
0.786 g/ml at 20°C/20°C
Infinite
*J. Dorigan et_ _al. , "Acetonitrile," p. AI-24 in Scoring of Organic Air Pol-
lutants, Chemistry, Production and Toxicity of Selected Synthetic Organic
Chemicals (Chemicals A-C), MTR-7248, Rev 1, Appendix I, MITRE Corp., McLean,
VA (September 1976).
-------
A-3
Table A-3. Physical Properties of Hydrogen Cyanide*
Synonyms Prussia acid
Molecular formula CHN
Molecular weight 27.03
Physical state Liquid
Vapor pressure 739.36 mm Hg at 25 °C
Vapor specific gravity 0.932
Boiling point 25.7°C
Melting point -13.3°C
Density 0.6876 ay 20°C/4°C
Water solubility Infinite
*J. Dorigax et al., "Hydrogen Cyanide," p A 111-54 in Scoring of Organic Air
Pollutants f"chemistry/ Production and Toxicity of Selected Synthetic Organic
Chemicals (Chemicals F-N)_, MTR-7248, Rev 1, Appendix III, MITRE Corp.,
McLean, VA (September 1976).
-------
Table B-l. Air-Dispersion Parameters for Model Plant
with a Capacity of 180,000 Mg/yr
Source
Absorber vent (uncontrolled)
Column vents (uncontrolled)
Thermal oxidizer
Flare (on colunin vents)
Storage and handling (uncontrolled)
Crude acrylonitrile
Hydrogen cyanide
Acctonitrile
Acrylonitrile run (2)
Acrylonitrile storage (2)
Hydrogen cyanide loading
Acctonitrile loading
Acrylonitrile rail loading
Acrylonitrile barge loading
Storage and handling (controlled)
Crude acrylonitrile scrubber
Acetonitrile scrubber
Acrylonitrile scrubber
Flare (on hydrogen cyanide)
Fugitive emissions0 (uncontrolled)
Fugitive emissions (controlled)
Secondary emissions
Incinerator (uncontrolled)
Deep-well pond (uncontrolled)
Deep-well pond (controlled)
0.57
570
28.5
57.1
Emission
Rate
(Q/sec)
(acrylonitrile)
(total VOC)
(acrylonitrile)
(total VOC)
0.0057 (acrylonitrile)
7.76
0.29
0.57
0.27
0.23
0.12
0.36
1.52
0.15
0
0.95
0.60
0.0027
0.0012
0.053
0.0038
4.6
9.4
1.4
2.8
2.1
74
6.3
(total VOC)
(aery lonitr i le )
(total VOC)
(each)
(each)
(acrylonitrile)
(total VOC)
(acrylonitrile)
(total VOC)
Height
(m)
60
60
18
60
12.2
7.3
9.8
9.8
12.2
4.0
4.0
4.0
2.0
6.0
6.0
6.0
60
30
1.0
1.0
Diameter
(m)
1.0
0.1
4.5
0.06
16.2
6.1
7.0
7.0
24.4
0.1
0.1
0.2
0.5
4.5
60 X 90
60 X 90
Discharge
Temperature
(K)
280
Ambient
533
1250
Ambient
273
Ambient
Ambient
Ambient
Ambient
Ambient
Ambient
Ambient
Ambient
Ambient
Ambient
1250
1140
Ambient
Ambient
Flow Discharge
Rate Velocity
(m^/sec) (m/sec)
40 49
0-12 15.8
160 10
0.0015 0.19
0.00075 0.086
0.024 0.75
33 7 do
-------
C-l
APPENDIX C
FUGITIVE-EMISSION FACTORS*
The Environmental Protection Agency recently completed an extensive testing
program that resulted in updated fugitive-emission factors for petroleum re-
fineries. Other preliminary test results suggest that fugitive emissions from
sources in chemical plants are comparable to fugitive emissions from correspond-
ing sources in petroleum refineries. Therefore the emission factors established
for refineries are used in this report to estimate fugitive emissions from
organic chemical manufacture. These factors are presented below.
Source
Uncontrolled
Emission Factor
(kg/hr)
Controlled
Emission Factor0
(kg/hr)
Pump seals ,
Light-liquid service
Heavy-liquid service
Pipeline valves
Gas/vapor service
Light-liquid service
Heavy-liquid service
Safety/relief valves
Gas/vapor service
Light-liquid service
Heavy-liquid service
Compressor seals
Flanges
Drains
0.12
0.02
0.021
0.010
0.0003
0.16
0.006
0.009
0.44
0.00026
0.032
0.03
0.02
0.002
0.003
0.0003
0.061
0.006
0.009
0.11
0.00026
0.019
aBased on monthly inspection of selected equipment; no inspection of
heavy-liquid equipment, flanges, or light-liquid relief valves;
10,000 ppmv VOC concentration at source defines a leak; and 15 days
allowed for correction of leaks.
Light liquid means any liquid more volatile than kerosene.
*Radian Corp., Emission Factors and Frequency of Leak Occurrence for Fittings
in Refinery Process Units, EPA 600/2-79-044 (February 1979).
-------
D-l
APPENDIX D
COST ESTIMATE DETAILS
This appendix contains sample calculations showing how the costs presented in
this report were estimated.
The accuracy of an estimate is a function of the degree of data available when
the estimate was made. Figure D-l illustrates this relationship. The contin-
gency allowance indicated is included in the estimated costs to cover the unde-
fined scope of the project.
Capital costs given in this report are based on a screening study, as indicated
by Fig. D-l, based on general design criteria, block flowsheets, approximate
material balances, and data on general equipment requirements. These costs have
an accuracy range of +30% to -23%, depending on the reliability of the data, and
provide an acceptable basis to determine the most cost-effective alternative
within the limits of accuracy indicated.
A. THERMAL OXIDIZER CONTROLLING EMISSIONS FROM MODEL-PLANT ABSORBER VENT
This example is based on the estimated emissions of 80,000 scfm, with a heat
content of 25 Btu/scf going to a thermal oxidizer operated at 1600°F with
0.75-sec residence time and equipped with recuperative heat recovery. The esti-
mated emissions include the vent gases from the absorber vent and have the composi-
tion shown in Table IV-2. Liquid organic wastes are used as part of the supple-
mental fuel and supply an average of 40.3 million Btu/hr. Appendix B of the
Control Device Evaluation. Thermal Oxidation report was used to estimate the
costs as follows. On p B-20 are costs for thermal oxidizers with a residence
time of 0.75 sec and with 50% heat recovery by recuperative heat exchange and
operating at 1600°F on off-gas with a heat content of 20 Btu/scf. The fuel
costs for this case are slightly more than for the case for an off-gas with a
heat content of 25 Btu/scf. Since part of the supplemental fuel is the liquid-
organic waste from the acrylonitrile process, the utility costs are adjusted to
account for the heat supplied by the combustion of the liquid-organic wastes:
40.3 million Btu/hr X 8760 X °° = $707,000/yr.
-------
INFORMATION! USED BY ESTIMATOR
ESTIMATE. TYPE.
/xr'3/^/\/S/c?/
-------
t>-3
Since the costs are given for 50,000 and 100,000 scfm, it is necessary to estimate
the costs for 80,000 scfm by interpolation. This was done by plotting the costs
versus the scfm on log-log graph paper and reading the costs for 80,000 scfm from
the curve:
Total installed capital cost
Fixed costs
Utilities costs
Credit for liquid-organic wastes
Manpower costs
Gross annual operating cost
$3,400.000
986,000
980,000
(-707,000)
27,000
$1,286,000
From Table VI-1 of this report:
Emission reduction
Cost effectiveness
18 Mg of acrylonitrile/yr
18,000 Mg of VOC/yr
$1,286,000
18
of acrylonitrile
of voc
FLARE ON COLUMN VENT EMISSIONS
This example is based on an estimated average emission from the column vents of
1360 Ib/hr at 100°F with a molecular weight of 34.
Installed Capital Cost
The equation given in Sect. A of Appendix A of the flare report was used to cal-
culate the flare-tip diameter (2.94 in.) that would have a pressure drop of 3 in.
H 0 when the vent gases are flared as described above at 1360 Ib/hr. Figure B-l
in Appendix B of the flare report shows that the installed capital cost of a total
flare system of that size is $48,000.
Gross Annual Operating Cost
From Table VI-1 of this report the total fixed costs, including capital recovery.
are 29% of the installed capital cost:
-------
D-4
$48,000 X 0.29 = $14,000/yr.
2
From Fig. IV-4 of the flare report the natural gas used for the pilot lights is
60 scfh and for purging is 3 scfh. From Table VI-1 the cost of gas is $2.00 per
thousand ft :
(60 + 3) X 8760 X = $1100/yr.
2
From Sect. IV-A-1 of the flare report it is estimated that 0.3 Ib of steam is
required per pound of emission; from Table VI-1 the cost of steam is $2.50/
thousand Ib. The average emission is 1360 lb/hr:
0.3 X 1360 X 8760 X |~ = $8900/yr.
The annual cost summary is as follows:
Fixed $14,000
Natural gas 1,100
Steam 8,900
Total $24,000
3. Cost Effectiveness
Cost effectiveness is the gross annual operating cost, $24,000, divided by the
annual VOC or acrylonitrile destroyed at 99% efficiency. From Table VI-3 of this
report the total VOC reduction for the column vents is 1800 Mg/yr, and the total
acrylonitrile destroyed is 890 Mg/yr:
1 800° = $13/M9 of VOC destroyed.
= $27/Mg of acrylonitrile destroyed.
890
-------
D-5
c. REFERENCES*
^ J. W. Blackburn, IT Enviroscience, Inc., Control Device Evaluation. Thermal
Oxidation (July 1980) (EPA/ESED report, Research Triangle Park, NC).
2. V. Kalcevic, IT Enviroscience, Inc., Control Device Evaluation. Flares and the
Use of Emissions as Fuels (in preparation for EPA, ESED, Research Triangle Park,
NC).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
E-l
APPENDIX E
LIST OF EPA INFORMATION SOURCES
C. P. Priesing, American Cyanamid Company, letter to EPA, Feb. 1, 1978.
Donald W. Smith, E. J. du Pont de Nemours & Co., letter to EPA, Jan. 17, 1978.
Harry M. Keating, Monsanto Chemical Intermediates Co., letter to Hydroscience,
Dec. 16, 1977 (nonconfidential parts).
V. E. Stilwell, Louisiana Air Control Commission Emissions Inventory Questionnaire
for American Cyanamid Company, Mar. 26, 1976.
H. L. Dey, Texas Air Control Board 1975 Emissions Inventory Questionnaire for
E. I. du Pont de Nemours & Company Beaumont Works (nd).
W. E. Elting, Memphis and Shelby County Air Pollution Control Permit Application
for E. I. du Pont de Nemours & Co. Memphis Plant (nd).
V. E. Stillwell, EPA Questionnaire for American Cyanamid Company, July 25, 1972.
W. R. Chalker, EPA Questionnaire for E. I du Pont de Nemours & Co., Sept. 18,
1972.
Harry M. Walker, EPA Questionnaire for Monsanto Company, Apr. 28, 1972.
G. K. Doss, EPA Questionnaire for Vistron Corporation, June 13, 1972.
-------
F-l
APPENDIX F
EXISTING PLANT CONSIDERATIONS
A. EXISTING PLANT CHARACTERIZATION
Table F-l — lists emission control devices reported to be in use by industry.
To gather information for the preparation of this report two site visits were
made to manufacturers of acrylonitrile. Trip reports have been cleared by the
companies concerned and are on file at EPA, ESED, in Durham, NC; ' EPA also
has received letters in response to requests for information on air emissions
from acrylonitrile plant and in response to requests for comments on the draft
version of this report. Some of the pertinent information concerning process
emissions from existing acrylonitrile plants is presented in this appendix.
All six domestic acrylonitrile plants use the Sohio process and catalyst* and
employ multiple fluid bed reactors.
1. Du Pont - Beaumont, TX
The process was licensed from Sohio and the plant designed and constructed by
Badger, with startup taking place during 1970. A catalytic oxidizer that was
installed later to abate emissions from the absorber vent came onstream during
September 1976. Table F-2 gives data on the controlled emissions from the
catalytic oxidizer. Although the propane destruction efficiency in this unit
is only 24%, Du Pont believes that a catalytic oxidation system could have been
developed to destroy both propylene and propane. '
The emissions from the column vents are collected by the flare header system
and controlled by a 16-in. flare designed for emergency and shutdown use.
A separate 6-in. flare is used to control emissions from HCN storage and tank-
car loading. The HCN storage tanks are refrigerated to 41°F and have a refri-
gerated vent condenser that vents to the HCN flare.
The storage tanks for crude acrylonitrile, product acrylonitrile, product
analysis, and acetonitrile are blanketed with nitrogen under pressure control.
*Although Catalyst 41 is believed to be currently used, Sohio (Vistron) began
marketing a fourth-generation catalyst (Catalyst 49) during 1978 that is more
selective than Catalyst 41.
-------
Table F-l- Control Devices Currently Used by the U.S. Acrylonitrile Industryc
Control Devices at Various Emission Points
Company
Cyanamid
Du Pont
Beaumont, TX
Memphis, T^
Monsanto
Alvin, TX
Absorber Vent Column Vents Storage Tank Vents
None Flare Scrubbers
Catalytic oxidizer Flare Scrubbers, refrigerated
condenser , and flare
None Not reported Scrubber
Thermal oxidizer Flare and vent con- Not reported
Deep-Well Pond
Lube-oil cover
Lube-oil cover
Not used
Lub-oil cover
Texas City, TX Thermal oxidizer
Vistron
None
denser
Water scrubber and
flare
Flare
Water scrubber, vent
condenser, and float-
ing roof
Flare
Closed surface system with
*~3
water scrubber i
Lube -oil cover
See refs 1—11.
bSome vents go directly to the atmosphere from conservation vents.
-------
F-3
Table F-2. Emissions Trom Catalytic Oxidizers—
Du Pont Beaumont Acrylonitrile Plant3
Component Emission Composition or Flow
Nitriles 0.005 wt %
Other VOC 0.402 wt %b
Carbon monoxide 0.227 wt %
VOC flow 1130 kg/hrb
Total flow 277 Mg/hr
aSee ref 3.
85% of VOC is propane. Propane is considered as having
low photochemical reactivity and the catalytic oxidizers
were not designed to control propane; see refs 3 and 5.
-------
F-4
Conservation/emergency vent valves are piped to water scrubbers that reportedly
remove 99.9% of the VOC in the nitrogen released from the tanks before it is
emitted to the atmosphere. The water from the scrubbers serving the tanks
containing acrylonitrile is recycled to the process. The scrubber water from
the scrubber on the acetonitrile tanks goes to a deep well. The scrubber for
the product analysis tanks also is used to control the emissions caused by
loading railroad tank cars with acrylonitrile. Emissions from loading of
acetonitrile are controlled by the scrubber for the acetonitrile storage tank.
Monsanto - Alvin, TX, and Texas City, TX
The VOC emissions from the absorber vents are controlled by thermal oxidizers
at both Monsanto plants during normal operation (see Table F-l). During startup,
plants with two or more reactors connected to the same absorber vent the reactor
effluent to the atmosphere, without it going through the absorber, to prevent
the creation of a flammable mixture in the absorber. The Monsanto Texas City
plant has an absorber for each reactor, and during startup the reactor effluent
is vented to the atmosphere after passing through the absorber, where some of
the VOC is removed.12
Data on emissions from the thermal oxidizers used at Monsanto's Chocolate Bayou
Plant at Alvin, TX, are given in Table F-3. These thermal oxidizers control
the emissions from the absorber vents and also destroy the liquid-waste aceto-
nitrile, the liquid-waste hydrogen cyanide, and the product column bottoms.
Monsanto reports that normal uncontrolled emissions from the absorber contain
approximately 2 g of acrylonitrile per kg of acrylonitrile produced. They
estimate that the emissions from the column vents contain 0.19 g of acrylonitrile
g
and 1.08 g of VOC per kg of acrylonitrile produced.
Monsanto states that a water scrubber designed to remove 99% of the acrylonitrile
emitted from a storage tank requires a bl',«/er and refrigerated water and that
the scrubber water cannot be recycled to the process but is sent to a stripper
for removal of VOC and then recycled to the scrubber. They report that the
emissions from the storage tank vents at the Texas City plant are controlled by
9
a water scrubber, vent condenser, or floating roof.
-------
F-5
Table F-3. Emissions from Thermal Oxidizers—Monsanto
Chocolate Bayou Acrylonitrile Plant
Emission Composition or Flow
Component
Nitriles
Other VOC
Methane
Carbon monoxide
Nitrogen oxides
VOC flow
Total flow
First Unit
5-S ample Average
<3.0 ppmv
23.7 ppmv
0.5 ppmv
74.0 ppmv
b c
8.0 ppmv '
3.7 kg/hr
151 Mg/hr
1 Sample
<3.0 ppmv
22.0 ppmv
0.5 ppmv
89.1 ppmv
Not sampled
4.0 kg/hr
181 Mg/hr
Second
7-S ample Average
<3.0 ppmv
44.6 ppmv
0.5 ppmv
88.6 ppmv
^200 ppmv
7.4 kg/hr
163 Mg/hr
Unit
1 Sample
<3.0 ppmv
18.0 ppmv
0.5 ppmv
90.9 ppmv
Not sampled
3.4 kg/hr
182 Mg/hr
Separate identical thermal oxidizers for each of two separate acrylonitrile production
units. Samples taken during steady-state operation. See ref 6.
Two samples only.
i
'Probably erroneous analysis per Monsanto.
-------
F-6
3. Vistron - Lima, OH10
The Vistron Corporation is a subsidiary of the Standard Oil Company (Ohio) and
operates acrylonitrile production facilities located adjacent to the Sohio
refinery near Lima, OH, to produce acrylonitrile from propylene and ammonia by
the Sohio process. The plant was built by Badger in 1965, and there have been
no major modifications since 1971. An older plant at the same site is no
longer producing acrylonitrile.
The emission control systems described below are those in use in 1977. Vistron
is working toward reducing the emissions from its acrylonitrile plant in the
future. Emissions vented from the columns are controlled by flaring. A header
runs throughout the plant for the purpose of collecting vent gases from the
various equipment vents and natural gas from purge applications. From the
header the gases pass through a liquid knockout pot and travel up a flare
stack. Normal flows to the incinerators will also divert to the flare stack in
the event of an incinerator shutdown. The stack consists of a 24-in. pipe
extending 200 ft above grade.
Three product tanks, three rundown tanks, and two crude tanks are used; each is
equipped with a combination pressure-vacuum relief valve set to relieve to
atmosphere at a pressure of 4 in. HO or a vacuum of 1 in. HO. Nitrogen is
« £
fed to the three product tanks and escapes through the pressure-vacuum relief
valve to the atmosphere when the pressure exceeds the setting. The new product
tank has a continuous nitrogen purge, and the nitrogen to the east and west
product tanks is fed through a pressure regulator set to maintain a minimum
pressure of 2 in. H2O. The HCN is stored in horizontal pressure tanks that
have a totally contained vent system. The normal vent is directed to either
the flare stack or the incinerators. The gases from an emergency vent from
each tank go directly to the flare stack through a separate line. A rupture
disk designed to burst at 15 psig keeps the emergency vents closed under normal
conditions. Both the normal vents and tht emergency vents are continually
purged with nitrogen.
B. RETROFITTING CONTROLS
The primary difficulty associated with retrofitting may be in finding space to
fit the control device into the existing plant layout. Because of the costs
-------
F-7
associated with this difficulty it may be appreciably more expensive to retrofit
emission control systems in existing plants than to install a control system
during construction of a new plant.
An acrylonitrile plant will generate an excess of steam; so retrofit of a
thermal oxidizer with heat recovery to produce steam may not be economically
feasible. For instance, at most existing plants the steam-generating facili-
ties have already been provided. It may be possible to save some fuel by
idling existing boilers. However, boilers are being used increasingly for
disposal of wastes from processes, and boilers thus used could not be idled.
Further, favorable economics from an energy consumption standpoint would depend
on whether acetonitrile and/or hydrogen cyanide were sold and therefore not
available as a fuel and whether deep welling is legally allowed.
-------
C. REFERENCES*
1. C. P. Priesing, American Cyanamid Company, letter dated Feb. 1, 1978, to EPA
in response to request for information on acrylonitrile emissions for all
Cyanamid facilities (nonconfidential portion only).
2. V. E. Stillwell, American Cyanamid Co., EPA Questionnaire (July 25, 1975).
3. J. A. Key, IT Enviroscience, Inc., Trip Report To Beaumont Works, E. I. du Pont
de Nemours & Co., Beaumont, TX, Sept. 7, 1977 (on file at EPA, ESED,
Research Triangle Park, NC).
4. W. E. Elting, E. I. du Pont de Nemours & Co., Memphis and Shelby County Air
Pollution Control Permit Application (Sept. 7, 1973).
5. W. R. Chalker, E. I. du Pont de Nemours & Co., letter dated Feb. 6, 1979, to
EPA with comments on draft Acrylonitrile report.
6. H. M. Keating, Monsanto Chemical Intermediates Co., letter dated Dec. 16, 1977,
to IT Enviroscience, Inc., with information on thermal oxidizers used at the
Monsanto acrylonitrile plants at Alvin, TX (nonconfidential portion only).
7. H. M. Walker, Monsanto Co., EPA Questionnaire (Apr. 28, 1972).
8. T. W. Hughes and D. A. Horn, Source Assessment: Acrylonitrile Manufacture
(Air Emissions), EPA-600/2-77-107, Research Triangle Park, NC (September
1977).
9. M. A. Pierle, Monsanto Chemical Intermediates Co., letter dated Mar. 16,
1979, to EPA with comments on draft Acrylonitrile report.
10. J. A. Key, IT Enviroscience, Inc., Trip Report to Vistron Corporation, Lima, OH,
Oct. 4, 1977 (on file at EPA, ESED, Research Triangle Park, NC).
11. K. E. Blower, Sohio, letter dated Feb. 16, 1979, to EPA with comments on
draft Acrylonitrile report.
12. M. A. Pierle, Monsanto Chemical Intermediates Co., letter dated Aug. 10, 1979,
to EPA with information on air emissions from acrylonitrile plants during
startup periods.
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
3-i
REPORT 3
GLYCERIN AND ITS INTERMEDIATES
(ALLYL CHLORIDE, EPICHLOROHYDRIN, ACROLEIN, AND ALLYL ALCOHOL)
C. A. Peterson, Jr.
IT Enviroscience
9041 Executive Park Drive
Knoxville, Tennessee 37923
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
June 1980
This report contains certain information which has been extracted from the
Chemical Economics Handbook, Stanford Research Institute. Wherever used, it
has been so noted. The proprietary data rights which reside with Stanford
Research Institute must be recognized with any use of this material.
D33A
-------
3-iii
CONTE.TS FOR REPORT 3
Page
I, ABBREVIATIONS AND CONVERSION FACTORS I_j
II- INDUSTRY DESCRIPTION II-l
A. Introduction II-l
B. Usage and Growth II-2
C. Domestic Producers II-2
D. References 11-7
III. PROCESS DESCRIPTIONS III-l
A. Introduction III-l
B. Chlorination Process III-2
C. Oxidation Process II1-16
D. Isomerization Process 111-26
E. References 111-30
IV. EMISSIONS IV-1
A. Chlorination Process IV-1
B. Oxidation Process IV-1
C. Isomerization Process IV-3
D. References IV-6
V. APPLICABLE CONTROL SYSTEMS V-l
A. Chlorination Process V-l
B. Oxidation Process V-9
C. Oxidation Process Variation V-14
D. Isomerization Process V-15
E. References V-16
VI. IMPACT ANALYSIS VI-1
A. Control Cost Impact VI-1
B. Environmental Impact VI-1
C. Summary VI-1
D. References VI-7
-------
3-v
APPENDICES OF REPORT 3
APPENDIX A. PHYSICAL PROPERTIES OF ORGANIC RAW MATERIALS, INTERMEDIATES, A-l
END PRODUCTS, AND BY-PRODUCTS FOR THE SYNTHETIC GLYCERIN
INDUSTRY
APPENDIX B EXISTING-PLANT CONSIDERATIONS B-l
-------
3-vii
TABLES OF REPORT 3
Kumber
II-l Production and Growth, Glycerin and Intermediates II-3
II-2 Capacity of Glycerin and Intermediates II-4
IV-1 Uncontrolled Emissions for Chlorination Process IV-2
IV-2 Uncontrolled Emissions for Oxidation Process IV-4
IV-3 Uncontrolled Emissions for Oxidation Variation IV-5
V-l Controlled Emissions for Chlorination Process V-2
V-2 Controlled Emissions for Oxidation Process V-10
V-3 Controlled Emissions for Oxidation Variation V-14
VI-1 Environmental Impact from Controlled Chlorination Process VI-2
VI-2 Environmental Impact from Controlled Oxidation Process VI-3
VI-3 Environmental Impact from Controlled Oxidation Variation VI-4
VI-4 Comparison of Controlled and Uncontrolled Emissions VI-5
A-l Physical Properties A-l
B-l Control Devices and Techniques Currently Used B-2
-------
3-ix
FIGURES OF REPORT 3
Number Page
II-l Plant Locations and Products II-5
III-l.A Flowsheet, Allyl Chloride III-3
III-l.B Flowsheet, Epichlorohydrin III-6
III-l.C Flowsheet, Glycerin by Chlorination III-9
III-2 Block Flowsheet, Glycerin by Oxidation 111-17
V-l.A Flowsheet, Allyl Chloride (Repeated) V-3
V-l.B Flowsheet, Epichlorohydrin (Repeated) V-5
V-l.C Flowsheet, Glycerin by Chlorination (Repeated) V-7
V-2 Block Flowsheet, Glycerin by Oxidation (Repeated) V-ll
-------
T — 1
ABBREVIATIONS AND COWERS I ON FACTORS
tin policy is to express all ase a su resents used in agency documents in metric
units. Listed belov are the International System of Units (SI) abbreviations
and conversion factors for this report.
To Cor.vert From
Pascal (Pa)
Jcule (J)
Degree Celsius (°C)
Meter (m)
Cubic seter (m3)
Ciibic meter (n3)
Cubic raeter (n3)
Cubic iseter/second
(nj/s)
Watt (W)
Heter (a)
Pascal (Pa)
Kilogram (kg)
Jcule (J)
Atmosphere (760 sss Hq)
British thermal unit (Btu)
Degree Fahrenheit (°F)
Feet (ft)
Cubic feet (ft"3}
Barrel (oil) (bbl)
Gallon (U.S. liquid) (gal)
Gallon (U.S. liquid)/fflin
Horsepower (electric) (hp)
Inch (in. )
Pound- force/ inch2 (psi)
Pound-mass » 3'
a.aa
3.531 X 1C1
2.643 X 10-
1.585 X 10*
1.340 X I0"a
3,93? X iOl
1.450 X 1Q"4
2.205
2.778 X 10"4
Standard Conditions
63*F = :o°c
1 atsosphere = 101,325 Pascals
Prefix
T
G
M
k
at
M
Symbol
tera
giga
mega
kilo
milii
micro
Multiplication
Factor
IQ3
10"3
Example
1
1
1
1
1
1
Tg =
Gg =
Mg =
faa =
»V =
pg *
1
1
1
1
1
1
X
X
X
X
X
X
10*
10*
106
IQ3
10"
10*
2 grans
graas
grams
»*ters
3 volt
6 gram
-------
II-l
II. INDUSTRY DESCRIPTION
A. INTRODUCTION
The synthesis of glycerin from propylene was selected for consideration because
early estimates for total emissions of volatile organic compounds (VOC) from
production operations were relatively high.
Several chemical intermediates, co-products, and by-products or waste products
are manufactured in the various process steps for the synthesis of glycerin
from propylene.1'2 These intermediates, co-products, and by-products are rela-
tively volatile and can generate large amounts of emissions during their manu-
facture, handling, or consumption in subsequent processing operations (see physi-
cal property data, Appendix A).
The three major routes for the synthesis of glycerin from propylene are the
chlorination route, in which the major intermediates are allyl chloride and
epichlorohydrin,- the oxidation route, in which the major intermediates and co-
products are acrolein, allyl alcohol, and methyl ethyl ketone; the isomerization,
peracetic acid route, in which propylene oxide is isomerized to allyl alcohol
and then oxidized to glycidol and hydrolized to glycerin.1'2 A variation of
the propylene oxidation process in which excess air is present is used to pro-
duce acrolein and acrylic acid (see Sect. III.C.4).
Glycerin is a liquid with moderate viscosity and low vapor pressure (0.1 Pa) at
ambient conditions. It is a relatively bland and innocuous material with a
wide spectrum of uses, including humectants, emolients, ointments, and related
internal and external applications.1
The major intermediates, co-products, and by-products generated in the synthesis
of glycerin from propylene are liquids of low to moderate viscosity and moderate
to high vapor pressure at ambient temperature. Most of these intermediates,
co-products, and by-products are toxic and/or flammable materials; vapor release
in significant quantities or concentrations could present serious problems (see
Appendix A for typical physical properties).
-------
II-2
B. USAGE AND GROWTH (DOMESTIC)1'3'4
Table II-l shows production and growth rates for synthetic glycerin and the
principal intermediates. Synthetic glycerin has a zero to slightly negative
growth rate, since glycerin from natural sources is taking an ever larger share
of the total glycerin market. Before 1974 synthetic glycerin had 57% of the
glycerin market share, whereas natural glycerin's market share was 43%. After
1974 the increase in oil pricing caused the price of synthetic glycerin to rise
sharply, and it is now about 4<= higher than the price of natural glycerin.
Because of this price differential market shares have changed, and synthetic
glycerin now has only 49% of the total market and its market share is declining.
As a principal intermediate, acrolein is also used in the manufacture of other
products, such as methionine. Approximately 60% of the total acrolein manu-
factured is subsequently converted to synthetic glycerin. Total acrolein usage
is growing at about 2% per year.
The largest and most significant usage and growth pattern is exhibited by epi-
chlorohydrin, an alternate intermediate for synthetic glycerin. Only about 25%
of the total epichlorohydrin produced is converted to synthetic glycerin at
present. The major use, approximately 56%, of epichlorohydrin is in the manu-
facture of epoxy resins. The overall growth rate in the use of epichlorohydrin
is currently about 5.4% per year.
Propylene, the principal raw material for synthetic glycerin and its intermediates/
is currently in ample supply and is expected to remain readily available. The
past periodic shortages of chlorine, the other main raw material used in the
chlorination process, will probably continue.
C. DOMESTIC PRODUCERS1,3""7
As of 1977 there were two domestic producers of acrolein, two domestic producers
of epichlorohydrin, and three domestic producers of synthetic glycerin. Table II**
lists the producers, the plant locations, the processes being used, and the
nameplate capacity for the products being made. Figure II-l shows the plant
locations and products made at each location.
-------
II-3
Table II-l. Production and Growth (Domestic) of
Synthetic Glycerin and Major Intermediates*
Year
1969
1970
1971
1972
1973
1974
1975
1976
1977
Est 1982
Synthetic
Production
(Gg/yr)
85.3
86.6
87.0
90.3
94.3
92.0
61.7
.70.7
59.0
56.7
Glycerin
Growth
(%/yr)
1.5
0.6
3.8
4.4
-2.5
-32.9
16.2
-17.7
-4.5 Avg
-0.8
Crude Epichlorohydrin
Production
(Gg/yr)
132
129
129
138
155
166
115
144
132
172
Growth
(%/yr)
-2.3
7.0
12.3
7.1
-30.7
25.2
-8.3
5.4
Acrolein
Production
(Gg/yr)
21.8
21.8
21.8
21.3
24.9
24.0
18.6
20. '4
20.4
22.7
Growth
(%/yr)
-2.3
16.9
-3.6
-22.5
9.7
-0.8 Avg
2.0
"See refs 1, 3, and 4.
-------
Table II-2. Capacity (Domestic) of Major Intermediates and Synthetic Glycerin'
Company
Dow Chemical Co.
Shell Chemical Co.
Union Carbide Corp.
FMC Corp.
Total
Location
Freeport, TX
Deer Park, TX
Norco, LA
Norco , LA
Taft, LA
Bay port, TX
Capacity (Gg/yr)
Crude
Acrolein Epichlorohydrin
113.4
49.9^
49.9 >
24.9 J
27.2
52.1 213.2
Synthetic
Glycerin
54.4
45. 4b
18.1
117.9
Process Type
Chlorination
Chlorination
Chlorination
Oxidation
Oxidation
Propylene oxide,
peroxidation
See refs 1,
-7.
DTotal combined synthetic glycerin capacity of Deer Park, TX, and Norco, LA, plants of Shell. Capacity
breakdown for amounts of glycerin derived from epichlorohydrin vs acrolein is considered confidential by Shell.
H
M
I
-------
II-5
1. The Dow Chemical Co., Freeport, TX, epichlorohydrin and glycerin.
2. Shell Chemical Co., Deer Park, TX, epichlorohydrin and glycerin.
3. Shell Chemical Co., Norco, LA, acrolein, epichlorohydrin, and glycerin.
4. Union Carbide Corp., Taft, LA, acrolein.
5. FMC Corp., Bayport, TX, glycerin.
Fig. II-l. Plant Locations and Products
-------
II-6
Approximately 85% of the total synthetic glycerin capacity is based on the chlori-
nation process and the oxidation process. The remaining 15% is based on a
process in which propylene oxide is isomerized to allyl alcohol and the allyl
alcohol is oxidized with peracetic acid to glycidol. The glycidol is then hydroliz'
to glycerin and purified. Sales of synthetic glycerin for 1977 were only 50%
of nameplate capacity, and future markets are expected to shrink slightly from
current levels. With this small and shrinking market for synthetic glycerin,
no new synthetic glycerin plants are likely to be built in the near future, and
one or more of the existing plants will probably discontinue the production of
synthetic glycerin.
The capacity for acrolein manufacture is divided almost evenly between two manu-
facturers, but the end uses of the acrolein produced are aimed at radically
different markets. Shell Chemical Co. converts a large share of its total acrolein
production to synthetic glycerin, whereas Union Carbide does not manufacture
any synthetic glycerin but aims most of its acrolein production toward conversion
into methionine and miscellaneous uses. The production levels of acrolein for
1977 were only about 39% of nameplate capacity, and estimates of future growth
rates (2%/yr) indicate that no additional production capacity is needed in the
near future.
The capacity for epichlorohydrin manufacture is divided almost evenly between .
two manufacturers. The 1977 production levels of epichlorohydrin were about
62% of nameplate capacity, and production rates are estimated to increase at a
rate of about 5.4% per year. At this growth rate, production should reach 90%
of the nameplate capacity in 1984; so new production facilities will probably
be constructed by or before that date. Most of the epichlorohydrin produced is
consumed internally by the producers in the manufacture of such products as
epoxy resins, elastomers, synthetic glycerin, and miscellaneous uses, with only
a minor amount sold directly for use by others.
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II-7
D. REFERENCES*
1. D. Oosterhof, "Glycerin," pp. 662.5021A—662.5023E in Chemical Economics
Handbook, Stanford Research Institute, Menlo Park, CA (April 1976).
2. R. G. Muller, Glycerine and Intermediates, Report No. 58, A private report by
the Process Economics Program, Stanford Research Institute, Menlo Park, CA
(December 1969).
3> J. L. Blackford, "Epichlorohydrin," pp. 642.3021A—E and 642.3022A—V in Chemical
Economics Handbook, Stanford Research Institute, Menlo Park, CA (May 1978).
4. S. L. Soder and K. L. Ring, "Propylene," pp. 300.5405E—300.5405L and
300.5405Q—300.5405R in Chemical Economics Handbook, Stanford Research
Institute, Menlo Park, CA (August 1978).
5 C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Dow
Chemical Co. Process at Freeport, TX, Jan. 26 and 27, 1978 (on file at EPA,
ESED,.Research Triangle Park, NC).
< C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Deer Park, TX, Jan. 25, 1978 (on file at EPA, ESED,
Research Triangle Park, NC).
7 C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Norco, LA, Jan. 25, 1978 (on file at EPA, ESED,
Research Triangle Park, NC).
*When a reference number is used at the end of a paragraph or on a heading,
it usually refers to the entire paragraph or material under the heading.
When, however, an additional reference is required for only a certain portion
of the paragraph or captioned material, the earlier reference number may not
apply to that particular portion.
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III-l
III. PROCESS DESCRIPTIONS1
A. INTRODUCTION
Three major processes are used to manufacture synthetic glycerin in the United
States. Approximately 50% is made by the chlorinetion route from the intermediates
allyl chloride and epichlorohydrin. Approximately 25% is made by the oxidation
route from the intermediates acrolein and allyl alcohol. Approximately 25% is
made from the intermediates propylene oxide and allyl alcohol. The projected
growth rate for synthetic glycerin is minus 0.8% per year at present.2
Two of the processes are important because of the intermediates they produce.
The chlorination route produces epichlorohydrin, which has become a major product
as a precursor for epoxy resins and epichlorohydrin elastomers. Only about 25%
of the total epichlorohydrin domestically manufactured is currently converted
to synthetic glycerin, with the balance used for other purposes. The oxidation
route produces acrolein, which has become another major product in its own right.
About 60% of the total acrolein domestically manufactured is currently converted
to synthetic glycerin, with the balance going for other uses.2
Propylene oxide is a major commodity chemical with varied uses. Only about
1.8% of the total propylene oxide domestically produced is currently consumed
in the manufacture of synthetic glycerin by the isomerization-hydroperoxidation
route.2
The major competitor for glycerin markets is "natural" glycerin from a large
and varied list of suppliers. Natural glycerin is derived from triglycerides
of various fatty acids found in nature. The raw materials include animal fats
(tallow) and vegetable oils from various sources. About 25 different domestic
companies produce crude natural glycerin as a by-product in their processing
operations using natural fats and oils. About 12 of these domestic companies
refine their crude natural glycerin to U.S.P. glycerin. Synthetic glycerin sells
for about $0.63 per lb, and refined natural glycerin sells currently for about
$0.54 per lb as of February 1980. Given this price differential, it is obvious
why the natural glycerin is increasing its share (about 57%) of the total glycerin
*Except where indicated by another reference number, the data in this section were
taken from ref. 1 (see "References" at end of the section).
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III-2
market, whereas the market share for synthetic glycerin is shrinking.3 Because
of the complexity of the processes involved and because of the need to ensure
that process vent emissions are properly identified and quantified, process
vents are grouped and discussed in separate sections labeled as "Main Process
Vents" for each major process route. Process descriptions are somewhat
generalized and do not necessarily exactly represent the processing schemes
employed by individual producers.
B. CHLORINATION PROCESS
1. Basic Reactions and Process Description
Synthetic glycerin is produced from propylene, chlorine, and alkali in a three-step
series of reactions. Refer to Figs. III-l.A—C respectively for model-plant flow-
sheets for the intermediates allyl chloride, epichlorohydrin, and glycerin. In
the first step (Fig. III-l.A) propylene is reacted adiabatically with chlorine
in a high-temperature gas-phase reactor to produce allyl chloride. A simple
illustration of this reaction is
CH2=CH-CH3 + C12 > CH2=CHCH2C1 + HCl
This reaction is extremely rapid. The optimum peak reaction temperature is
about 500°C. Excess propylene is used to dilute the reaction and to minimize
side reactions. Peak reaction temperatures are controlled, and the reactor
configuration is designed to maximize product yield and minimize side reactions.
Some by-products that are generated in this reaction step are chloropropene,
dichloropropene, and dichloropropane. Miscellaneous tars and carbonaceous by-
products are also generated in this high-temperature reaction (see Reaction
Section, Fig. III-l.A).
When the hot gas exits the reactor, it is immediately quench cooled by a cold
stream of liquid propylene injected into the hot gas. Further cooling by propylene
evaporation condenses the allyl chloride and other chlorinated organics in the
reactor gas. This gas-liquid mixture is then fractionated to separate the HCl
and propylene from the liquid products (see Initial Separation Section, Fig. III-l-A
The propylene-HCl gas stream is then compressed, partly condensed, and fractionated
to separate pure HCl gas from the propylene. The pure HCl gas either is put
-------
III-l.A. uncontrolled Model-Plant Flowsheet for Production of Allyl Chloride
Fig
-------
III-4
into a HCl gas header for use elsewhere in the plant or is absorbed in water to
produce technical-grade hydrochloric acid for sale. The liquid propylene from
the bottom of the gas fractionation column is sent to another fractionation
column for recovery of residual higher boiling organics, which are returned to
the liquid allyl chloride stream. The propylene gas from this second fractiona-
tion column is compressed and condensed for recycle to the process and for use
as the quench cooling liquid for rapid chilling of the reactor effluent (see
Propylene Recovery Section and Acid Reclamation Section, Fig. III-l.A).
The crude allyl chloride is fed to a series of distillation columns for purifica-
tion of the allyl chloride and separation of the various waste streams and by-produc*
Dichloropropene is a valuable by-product that is recovered and sold for use as
an agricultural soil fumigant. A small amount of purified allyl chloride is
sold or used for other products, but most of the allyl chloride is used as feedstocK
for the epichlorohydrin process (see Product Purification Section, Fig. III-l.A).
The next reaction step is the synthesis of epichlorohydrin from allyl chloride.
In this process sequence chlorine gas is dissolved in a large excess of water
to form acidic hypochlorous acid as follows:
C12 + H20 < > HOC1 + HCl
The allyl chloride is blended into this dilute hypochlorous acid solution at a
low concentration (to prevent the formation of a separate oil layer) and reacts
with the aqueous hypochlorous acid to form glycerin dichlorohydrin as follows:
CH2C1-CHOH-CH2C1 (30—35%)
CH2=CH-CH2C1 + HOCl >
CH2OH-CHC1-CH2C1 (65—70%)
This reaction is influenced by pH, concentration, and temperature. The pH must
be kept below 6, preferably in the 0.4 to 1.0 region. The concentration of
allyl chloride must be kept quite low to prevent the formation of a second phase
(oil layer) since the presence of a separate oily phase promotes side reactions
and lowers the yields of the desired dichlorohydrin. Reaction temperatures are
moderate (40 to 50°C). An intense mixing zone is needed at the point where
allyl chloride is added to the aqueous hypochlorous acid to rapidly and thoroughly
-------
III-5
disperse the allyl chloride in the aqueous phase. Some of the by-products or
waste materials generated in this reaction step are trichloropropane, tetrachloro-
propyl ether, and various chlorinated aldehydes and ketones (see Reactor System,
Fig. III-l.B).
When the hypochlorination reaction is complete, the dilute reaction solution is
reacted with an alkali source (such as calcium carbonate) to neutralize the
hydrochloric acid present and to convert the glycerin dichlorohydrin to epichloro-
hydrin as follows:
CH2OH-CHC1-CH2C1
+ NaOH >• CH2-CH-CH2C1 + NaCl + H20
CH2C1-CHOH-CH2C1 \Q/
This reaction step is influenced by temperature and reactant concentration.
The reaction mixture from the chlorohydrination step is normally quite dilute
(3 to 5%) and the temperature is moderate (40 to 50°C). A slight excess (about
5%) of alkali is used to drive the epoxidation step to completion. Some of the
by-products or waste materials generated in this reaction step are glycerin
monochlorohydrin, glycidol, glycerin, and miscellaneous higher molecular weight
materials such as polyglycols and chloroethers (see Epoxidation Reactor,
Fig. III-l.B).
After the alkaline epoxidation step the epichlorohydrin is stripped from the
reaction mixture by azeotropic distillation. Since epichlorohydrin azeotropically
distills with water at 26% water and since the saturation level of water in
epichlorohydrin is only about 2%, the condensate consists of two phases. The
water layer containing dissolved epichlorohydrin is returned to the primary
azeotrope still as reflux, and the epichlorohydrin layer containing dissolved
water is fed as reflux to a secondary stripping column that azeotropically strips
the dissolved water out of the epichlorohydrin product. The overhead condensate
from the secondary stripping column also condenses as two phases; this condensate
is also separated, with the water layer going back to the primary column while
the organic layer goes to the top of the secondary'column (see Azeotrope Column
and Drying Column, Fig. III-l.B).
-------
Fig. III-l.B. Uncontrolled Model-Plant Flowsheet for Production of Epichlorohydri
-------
III-7
The bottom stream from the primary azeotrope column is a large wastewater stream
containing dissolved salt and the water-soluble organic waste materials generated
by the chlorohydrination and epoxidation reaction steps.
After azeotropic distillation, the crude epichlorohydrin stream is sent to two
distillation columns for removal of lights and distillation of refined epichloro-
hydrin. The bottoms from the epichlorohydrin distillation column contain the
residual trichloropropane and other high boilers. The refined epichlorohydrin
is either sold or transferred to another process unit for conversion to finished
products such as epoxy resin or epichlorohydrin elastomers (see Lights Stripping
Column and Epichlorohydrin Finishing Column, Fig. III-l.B).
In the glycerin processing system the epichlorohydrin is blended with a large
stream.of a dilute aqueous solution of sodium carbonate. This aqueous stream
is then heated and held at elevated temperature to hydrolyze the epichlorohydrin
to glycerin in a series of reactions as follows:
CH2-CH-CH2C1 + H20 > CH2-CH-CH2C1
0 OH OH
2CH2-CH-CH2-C1 + Na2C03 >• 2CH2-CH-CH2 + 2NaCl + C02 + H20
I' \ ^ f
OH OH OH 0
CH2-CH-CH2 + H20 >• CH2-CH-CH2
' \ / I f I
OH 0 OH OH OH
These series of reactions are temperature-dependent and so they either can be
conducted in large tanks held near the boiling point for several hours or can
take place in a few minutes in a high-temperature, high-pressure reaction coil.
A slight excess of sodium carbonate is used to assure complete conversion of
the epichlorohydrin to glycerin. Concentration of glycerin in the reactor efflu-
ent is about 20 to 25%. Impurities or by-products produced in this reaction
consist principally of higher molecular weight glycol ethers and polyglycols.
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III-8
When reaction is complete, the excess carbonate is neutralized with a small
amount of hydrochloric acid. The carbon dioxide generated by the reaction is
captured and absorbed in a gas scrubbing column, with dilute sodium hydroxide
used as the absorber fluid. The resultant aqueous sodium carbonate is then
used as the reaction solution in the glycerin hydrolysis reaction (see Glycerin
Reaction Section, Fig. III-l.C).
The raw glycerin solution from the hydrolysis step is dilute and contains a large
concentration of salt (10 to 15%). This solution is concentrated in a double-
(or triple-) effect calendria style of evaporator to distill off some of the water
from the glycerin solution. As the water is evaporated, the salt crystallizes and
comes out of solution. The resultant raw glycerin/water/salt slurry is centrifuged
to remove the salt crystals. A water rinse in the centrifuge strips residual
glycerin from the surface of the salt crystals. The washed salt crystals are
discharged from the centrifuge and collected for either disposal or reuse in an
electrolytic chlor-alkali facility. A final calendria style of evaporator concen-
trates the centrifuged glycerin solution from about 45% to about 85%, and the
residual salt that crystallizes out in this final evaporation step is also removed
by a centrifuge (see Calendria Style Double-Effect Evaporators and Calendria Style
Concentrator, Fig. III-l.C).
A series of distillation and solvent extraction columns is used to refine and
purify the concentrated raw glycerin. A flasher column takes the glycerin overhead
to separate the product from the heavy polyglycols, polyethers, and traces of
residual salt. Various distillation and/or extraction columns can be used to
strip off impurities from the refined glycerin. A solvent stripping column is
used to remove residual solvent from the solvent extracted glycerin. A final-
product column uses superheated steam as a sweep gas to take the refined glycerin
overhead for product purification. The pure refined glycerin is finally processed
through an activated carbon bed to remove trace impurities and color bodies.
The final U.S.P. glycerin from the carbon bed adsorption columns is stored for
shipment to customers (see Fig. III-l.C, p. 2).
2. Main Process Vents
a. Allyl Chloride4'5 — The following four main process vents are shown in
Fig. III-l.A:
-------
Fig. III-l.C. Uncontrolled Model-Plant Flowsheet for Production of Glycerin by the Chlorination Process
Page 1 of 2
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C W.
"*tgy
Fig. III-l.C. (Continued)
Page 2 of 2
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III-ll
HC1 absorber vent -- The HC1 absorber vent located after the vent condenser
discharges the inert gas from the chlorination process. This vent stream con-
tains about 0.0001 to 0.0002 g of VOC per g of allyl chloride product. Principal
components of the VOC in this vent stream are C3 hydrocarbons such as propane
and propylene (see Vent Aj, Fig. III-l.A).
Light-ends distillation column vent -- Low-boiling impurities are stripped out
of the crude allyl chloride in this first distillation column. The vent stream
contains about 0.05 to 0.08 g of VOC per g of allyl chloride product (see Vent
A2, Fig. III-l.A).
Allyl chloride distillation column vent — This column distills the allyl chloride
from the heavy impurities generated in the chlorination reaction. The vent
stream.can contain up to 0.0001 g of VOC per g of allyl chloride product. The
principal component of the VOC in this vent stream is allyl chloride vapor (see
Vent A3/ Fig. III-l.A).
Dichloropropene distillation column vent — This column distills the dichloro-
propane-dichloropropene fraction from the rest of the "heavy" residues and tars.
This vent stream can contain up to 0.001 g of VOC per g of allyl chloride product.
The principal component of this VOC is dichlorinated C3 hydrocarbon vapor (see
Vent A4, Fig. III-l.A).
Epichlorohydrin4'5 — The four main process vents shown in Fig. III-l.B are as
follows .-
Epoxidation reactor vent -- Dilute glycerol dichlorohydrin solution is reacted
with an alkali source in this reaction vessel to convert the dichlorohydrin to
epichlorohydrin. The vent gas from this reactor system contains chlorinated
hydrocarbon vapors, such as epichlorohydrin and related materials. This vent
stream can contain from 0.0002 to 0.02 g of VOC per g of epichlorohydrin product,
depending on the reactor design, operating conditions, and type of alkali used
(see Vent Blf Fig. III-l.B).
Azeotrope column vent -- Crude epichlorohydrin is separated from the dilute
salt solution in this distillation system. The vent gas from this column assembly
-------
111-12
contains some epichlorohydrin, as well as other low-boiling organic materials.
This vent stream contains up to 0.0008 g of VOC per g of epichlorohydrin product
(see Vent B2, Fig. III-l.B).
Lights stripping column vent — Low-boiling impurities are stripped out of the
crude epichlorohydrin in the distillation column. The vent gas from this column
contains some epichlorohydrin and lower boiling organic compounds, up to 0.008 g
of VOC per g of epichlorohydrin product (see Vent B3, Fig. III-l.B).
Epichlorohydrin finishing column vent — Refined epichlorohydrin is produced
by this distillation column. The principal organic material found in the vent
gas from this column is epichlorohydrin, up to 0.0004 g of VOC per g of epi-
chlorohydrin product (see Vent B4, Fig. III-l.B).
It is possible to combine the three vent streams from these three separate dis-
tillation systems into one single vent by piping the column outlets into one
common vent header.
c. Glycerin5 -- Seven main process vents are shown in Fig. III-l.C as follows:
Carbon dioxide absorber vent -- Inert gas, water vapor, and traces of VOC are
released from the vent after the carbon dioxide absorber. This vent gas contains
about 0.0004 g of VOC per g of glycerin product (see Vent Cl7 Fig. III-l.C,
P- 1).
Double-effect evaporator vent — This system concentrates the dilute, salty,
glycerin stream to about 45% glycerin. The vent gas from the vacuum system on
these evaporators is essentially inert gas and water vapor. It does not contain
any significant amount of VOC (see Vent C2/ Fig. III-l.C, p. 1).
Calendrial style concentrator vent — This system evaporates additional water
from the crude glycerin stream, concentrating the crude glycerin from about 45%
glycerin to about 85% glycerin. The vent gas from the vacuum system on this
evaporator is essentially inert gas and water vapor. It does not contain any
significant amount of VOC (see Vent C3, Fig. III-l.C, p. 1).
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111-13
Crude glycerin stripping column vent — This system distills the crude glycerin
overhead, leaving the polyglycols and other heavy materials in the bottoms from
the distillation column. The vent gas from the vacuum system on this evaporator
is essentially inert gas and water vapor. It does not contain any significant
amount of VOC (see Vent C4, Fig. III-l.C, p. 2).
Light-ends stripping column vent -- This system strips out the more volatile
contaminates from the distilled crude glycerin. The vent gas from the vacuum
system on this stripping column is essentially inert gas and water vapor. It
does not contain any significant amount of VOC (see Vent C5, Fig. III-l.C, p. 2).
Solvent stripping column vent -- After the solvent soluble contaminates are
extracted from the distilled crude glycerin, the glycerin from the extraction
system.contains some dissolved solvent. This solvent is recovered by the solvent
stripping column. The principal VOC contained in the vent gas from this column
is the recovery solvent (acetone). This vent stream contains about 0.0002 g of
VOC per g of glycerin product (see Vent C6/ Fig. III-l.C, p. 2).
Glycerin product column vent -- This column is used as the final-product dis-
tillation unit to produce pure glycerin. The vent from the vacuum system on
this column is essentially inert gas and water vapor. It does not contain any
significant amount of VOC (see Vent C7, Fig. III-l.C, p. 2).
3 Fugitive and Secondary Emission Sources
Fugitive leaks throughout the process can be the source of various kinds of VOC
emissions. Leaks can occur from valves, flanges, pumps, agitators, and compres-
sors. Many of the chemicals handled in this series of processes are highly
flammable and toxic; so the plant must be well maintained to minimize the expo-
sure of operating personnel to dangerous concentrations of toxic fumes or vapors.4'5
In the Glycerin Section of the process, condensate from the evaporation of water
during the concentration of glycerin is collected for reuse. Total condensate
stream is about 5 g per g of glycerin product. Some of this condensate is used
as makeup water for the cooling tower that provides cool water for the heat
exchangers in the plant. This condensate contains significant amounts of dilute
VOC (primarily acetone). This VOC in the tower cooling water is lost to the
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111-14
atmosphere. The amount of VOC emitted by this cooling tower operation is about
0.0028 g per g of glycerin product5 (see Stream K15; Fig. III-l.C, p. 2).
Waste streams from the various sections of the process can be a source of second-
ary emissions. The amount and type of emissions generated by these waste streams
depend upon the handling systems and disposal techniques used on the waste streams.
Waste streams and their normal disposal techniques for the various process sections
are as follows:
a. Allyl Chloride4'5 In the allyl chloride process three waste streams (labeled
K) are shown on Fig. III-l.A as follows:
Propylene recovery system off-gas -- Some impure gas is released from the propylen*
recovery system. This off-gas contains propane and propylene, as well as some
other volatile hydrocarbons. The prime method of disposal for this off-gas is
to inject it into the plant fuel gas manifold so that it can be used as fuel in
various plant gas-fired burners and furnaces. This gas burns cleanly and does
not result in significant VOC emissions (see Kj, Fig. III-l.A).
Light-ends liquids -- The light ends that are stripped out of the crude allyl
chloride consist principally of chlorinated C3 compounds such as chloropropenes
and isopropyl chloride. This material is usually sent to an incineration system
for destruction. VOC emissions generated during handling and incineration are
dependent on system design and oeprating conditions. This stream is fairly
large (0.05 to 0.10 g per g of allyl chloride product); so the amount of VOC
that could be emitted by poor handling practices or incomplete oxidation during
incineration could be significant (see K- , Fig. III-l.A).
Heavy-ends liquids — The heavy ends are the chlorinated residues and tars that
remain after the by-product dichloropropene and dichloropropane are stripped
out for sale as an agricultural fumigant. This heavy-ends liquid is collected
and sent to an incinerator system for descruction (see KOD, Fig. III-l.A).
£.0
b. Epichlorohydrin4'5 -- In the epichlorohydrin process three waste streams (labeled
K) are shown in Fig. III-l.B as follows:
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111-15
Wastewater stream — The wastewater stream is the bottoms from the epichlorohydrin
azeotrope column after the epichlorohydrin is stripped out of the dilute aqueous
reaction stream. This wastewater contains salt and traces of eipchlorohydrin,
along with some water-soluble glycolic and chlorinated glycolic materials.
This wastewater stream is extremely large (over 30 g of wastewater per g of
epichlorohydrin product) and has less than 0.3% of organics, usually in the
range of 0.05 to 0.1% (see K3, Fig. III-l.B). The normal disposal technique is
to send this wastewater to a biological oxidation treatment system.
Lights organic waste -- The overhead product from the lights stripping column
consists primarily of low-boiling chlorinated C3 compounds such as allyl chloride
and related materials. This material is collected and sent to an incineration
system for destruction. The stream may contain up to 0.004 g of VOC per g of
epichlorohydrin product. The amount of VOC actually emitted to the air depends
on the handling techniques used and the performance of the incinerator (see K4,
Fig. III-l.B).
Heavies organic waste -- The heavies from the epichlorohydrin finishing still
consist primarily of trichloropropane, along with other high-boiling chlorinated
C3 compounds and miscellaneous tars. Since there is a limited market for trichloro-
propane, some of this material could be recovered and purified (distilled) for
sale. It is also possible to recover some glycerin from the waste stream by
water extraction and low-temperature hydrolysis. This waste stream is fairly
large, containing up to 0.04 g of organic materials per g of epichlorohydrin
product. The primary disposal technique for this waste stream is incineration.
The amount of VOC actually emitted to the air depends on the handling techniques
used and the performance of the incinerator (see KS, Fig. III-l.B).
c. Glycerin5 — In the glycerin process there are four waste streams (labeled K)
shown in Fig. III-l.C as follows:
Condensate --Condensate is collected from the distillation of water in the
glycerin evaporators and concentrator. This wastewater stream is discussed in
Sect. III-B.3, paragraph 2.
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111-16
Salt -- The washed salt from the salt centrifuges is collected and discharged
as a waste stream from the glycerin finishing operation. The process yields
about 0.7 g of salt per g of glycerin product. This waste stream of salt contains
some water and traces of glycerin and could either be collected and recycled to
an electrolytic chlor-alkali facility or be sent to the plant wastewater disposal
facility (see K7/ Fig. III-l.C, p. 1).
Foots — The bottoms or foots from the glycerin stripping column consist primarily
of a complex mixture of polyglycerines, along with traces of water and some
residual salt. SRI data1 indicate that this stream contains about 0.06 g of
polyglycerides per g of glycerin product. The waste stream is normally collected
and sent to a plant incinerator for disposal (see K9, Fig. III-l.C, p. 2).
Bottoms — The bottoms from the solvent recovery column consist of a mixture of
polyglycols and glycol ethers. This stream of polyglycols is collected and
sold as a by-product (see Ki2, Fig. III-l.C, p. 2).
C. OXIDATION PROCESS6
1. Basic Reactions and Process Description
Synthetic glycerin is produced from propylene and oxygen in a three-step series
of reactions. Refer to Fig. III-2 for the model-plant block flowsheet. Other
materials consumed in this series of reactions include sec-butanol, aluminum
granules, hydrogen peroxide, and water.
In the first step propylene is reacted with oxygen in the presence of steam in
high-temperature, gas-phase, catalytic tubular reactors to produce acrolein and
by-product acetaldehyde. A simple illustration of this reaction is
CH2=CH-CH3 + 02 >• CH2=CH-CHO + H20
This reaction is extremely rapid and exothermic. The reaction temperature is
approximately 400°C, depending on the specific catalyst used to promote the
selective oxidation of propylene to acrolein. Steam and/or excess propylene is
used to control the process and minimize side reactions. The principal by-product
generated by this reaction is acetaldehyde. Waste products include water, carbon
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Of JC^
Av*. 2.7. 000
SEC-&JTA/JOL (eeC.YCLE\
Fig. III-2. Block Flowsheet of Oxidation Process for Uncontrolled Model Plant Producing Synthetic Glycerin
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111-18
dioxide, carbon monoxide, and minor amounts of various aldehydes, ketones, and
other oxidation products.
When the hot gas exits the reactor, it is immediately quench cooled by contacting
the hot gas with a cool aqueous stream. Hydroquinone is used as an inhibitor
to prevent polymerization of the reactive acrolein. After quench cooling, water
is used as the absorption fluid in the carbonyl absorption column to strip acrolein
and other oxygenated organics out of the gas stream (see block labeled Reaction,
Compressors, Absorber, Stripper, Fig. III-2).
The stripped gas is compressed and then cooled in a carbon dioxide stripping
column. The residual propylene and allied hydrocarbons are removed as a liquid,
and the waste carbon dioxide (containing some flammable hydrocarbons) is vented
to a flare. The liquid hydrocarbon stream from the bottom of the carbon dioxide
stripping column is recycled to the propylene purification system for reuse
(see block labeled Distillation, Refrigeration, Fig. III-2).
The aqueous acrolein stream from the carbonyl absorption system is fed to a
crude acrolein recovery column, where the acrolein is distilled out of the water.
A small stream of solvent is added to the top of the distillation column to
break the acrolein-water azeotrope and permit dry acrolein to distill overhead.
Hydroquinone is added to the acrolein to prevent polymerization. The bottoms
from the crude acrolein recovery column separate into an oily organic layer and
an aqueous layer (see block labeled Distillation on top line, Fig. III-2).
The crude, dry acrolein is sent to an aldehyde stripping column, where the acetal-
dehyde is stripped out of the acrolein. The finished acetaldehyde and the finished
acrolein are stored for shipment or in-plant use (see block labeled Distillation
on top line, Fig. III-2).
The next step in this synthesis is the conversion of acrolein to allyl alcohol.
In this process sec-butanol is first sent to a sec-butanol drying column, where
it is dry distilled with the assistance of an azeotrope-breaker solvent to separate
the sec-butanol from residual water.
-------
111-19
Some of the dry sec-butanol is reacted with aluminum granules to form aluminum
butoxide (see block labeled Catalyst Preparation, Fig. III-2). The solution of
aluminum butoxide in excess sec-butanol is used as a catalyst for the hydrogenation
reaction. A simple equation for this catalyst forming reaction is
2A1 + 6CH3-CHOH-CH2-CH3 * 2A1(OCH-CH2-CH3)3 + 3H2
CH3
Acrolein is reacted with dry sec-butanol in the presence of aluminum butoxide
catalyst to form allyl alcohol and methyl ethyl ketone. A simple equation for
this hydrogenation reaction is
CH2=CH-CHO + CH3-CHOH-CH2-CH3 catalyst > CH SQ^QJ QH + CH3-C-CH2-CH3
II
0
The hydrogenation reaction is conducted in a liquid-phase hydrogenation reactor
system at moderate temperature (about 50°C) for a moderate time (about 30 rain)
(see block labeled Reaction on second line, Fig. III-2).
Excess sec-butanol is used to drive the reaction to completion. After the hydrogena-
tion reaction is completed, water is added to the reaction stream to kill the
catalyst and precipitate the aluminum from the aluminum butoxide as aluminum
hydroxide. A simple equation for this reaction is
A1(OCH-CH2-CH3)3 + 3H20 * A1(OH)3 + 3CH3-CHOH-CH2-CH3
CH3
A filter system is then used to remove the precipitated aluminum hydroxide from
the mixed reaction stream. This filter cake is contaminated with organics from
the mixed reaction stream (see block labeled Effluent, Storage, Filters, Fig. III-2).
After filtration, the mixed reaction stream is sent to a series of distillation
columns to separate the mixture into useful fractions. Residual acrolein, as
well as traces of other low-boiling materials, are removed from the mixed reaction
stream. These low boilers are recycled by adding them to the aqueous acrolein
stream from the carbonyl absorption system. A solvent is added to the distillation
-------
111-20
column as an azeotrope breaker to assist in the dry distillation of methyl ethyl
ketone and sec-butanol. Distilled methyl ethyl ketone is separated by this
series of columns and is stored for sale as a by-product. Recovered sec-butanol
is returned to the sec-butanol storage tank for recycle in the hydrogenation
process. A concentrated solution of allyl alcohol in water is stored for use
in the next process step. Hydroquinone is added to the allyl alcohol to inhibit
polymerization. This distillation system yields a waste stream of heavies (see
the two blocks labeled Distillation on second line, Fig. III-2).
The third synthesis step is the manufacture of glycerin from allyl alcohol by
reaction with hydrogen peroxide and water. The catalyst system used to promote
the initial reaction between allyl alcohol and hydrogen peroxide is considered
to be proprietary information and has not been disclosed. The initial reaction
sequence is the oxidation of allyl alcohol by hydrogen peroxide to glycidol,
with the soluble catalyst acting as an intermediary in the reaction. The overall
equation for this two-step oxidation is as follow:
H202 + CH2=CH-CH2OH > CH2-CH-CH2OH + H20
0
Conditions that favor this reaction and minimize side reactions are dilution
with a large excess of water, reaction in the temperature range of 30 to 50°C,
and control of the pH of the system within the range of 5 to 6. A slight excess
of allyl alcohol is used to ensure complete consumption of the hydrogen peroxide
(see the block labeled Reaction on third line of Fig. III-2).
After the oxidation step the soluble catalyst is extracted from the product
stream and is recovered for recycle to the oxidation reactor system.
A light-ends stripper column is used to remove unreacted allyl alcohol and by-produ*
acrolein from the aqueous oxidation product stream. The allyl alcohol is recycled
for reuse in the process, and the low-boiling acrolein and associated impurities
are collected for disposal (see the block labeled Distillation on the third
line, Fig. III-2).
-------
111-21
After the stripping process the glycidol-water solution is heated to accelerate
the hydrolysis of glycidol to glycerin. Some conversion of glycidol to glycerin
takes place in the oxidation reaction step, but additional exposure of glycidol
to water at an elevated temperature is needed to complete the hydrolysis. The
simple equation for this hydrolysis reaction is
CH2-CH-CH2OH + H20 ^ CH2OH-CHOH-CH2OH
0
The final reaction product is a dilute solution of glycerin. This solution
also contains some higher boiling polyglycol heavy impurities and colored mate-
rials. A series of distillation columns are used to separate and purify the
glycerin from this process (see the block labeled Heavy-Ends Distillation on
line 3V- Fig. III-2).
The distilled glycerin contains some residual colored impurities. This material
is processed in a carbon bed adsorption system to remove the contaminates. The
resultant U.S.P. glycerin is stored for sale. The residual material recovered
by steam stripping of the carbon bed is recycled for recovery of the glycerin
in the residue stream (see the block labeled Distillation and Carbon Treatment
on line 3, Fig. III-).
o Main Process Vents
£• *
Acrolein — Acrolein is a volatile, highly toxic, highly irritating chemical
with a very sharp, penetrating odor. Extreme care must be exercised in any
process involving this material to prevent significant releases to the environ-
ment. This section has three process vents and one intermittent vent, indicated
on Fig. 111-2 as follows:
carbon dioxide stripping tower vent -- This vent releases the carbon dioxide
generated during the catalytic oxidation of propylene. The vent gas also con-
tains some carbon monoxide, flammable hydrocarbon gases (such as propylene) and
traces of oxidized hydrocarbons (such as acetaldehyde). This vent stream is
normally vented to a flare to destroy the carbon monoxide and hydrocarbons.
-------
111-22
This vent stream flow rate is about 0.61 g per g of acrolein product and it
contains about 0.061 g of VOC per g of acrolein product (see hi, Fig. III-2).
Refigeration vent, intermittent — When the refrigerated condenser used to con-
dense the propylene in the carbon dioxide stripping tower periodically plugs
off due to frozen moisture, this vent is opened to defrost the condenser. This
periodic venting releases an average of 0.027 g of propylene and associated Cs
hydrocarbons per g of acrolein product.
Agueous acrolein system vent — The carbonyl absorption column system discharges
the crude aqueous acrolein to run tanks that are padded with methane. The ab-
sorber and the receiver are tied together and have a common vent. A vent scrubber
is used to reduce the amount of acrolein vapor in the vent gas. The scrubber
fluid is water, and the acrolein-containing scrubber fluid is returned to the
process. After the methane vent gas is scrubbed, it still contains about 5%
acrolein vapor and is sent to a flare to destroy the methane and acrolein vapor.
The amount of vent gas from the scrubber to the flare is about 0.063 g per g of
acrolein product and the crude acrolein contained in the gas is about 0.003 g
per g of acrolein product (see A2, Fig. III-2).
Distillation system vent — The distillation system discharges refined acrolein
to finished acrolein receiver tanks padded with methane. The column condenser
and the receiver are tied together with a common vent line. The vent gas is
sent to a flare to destroy the methane and acrolein vapor. The composition of
the vent stream is about 95% methane and 5% acrolein. The flow rate of the vent
stream going to the flare is about 0.15 g per g of acrolein product and it con-
tains about 0.0075 g of acrolein per g of acrolein product (see Ag, Fig. III-2).
b. Allyl Alcohol -- Allyl alcohol is a toxic, irritating chemical with a very sharp,
penetrating odor. Extreme care must be exercised in any process involving this
material to prevent significant releases to the environment. There are six
process vents in this section (see Fig. IiI-2) as follows:
Catalyst preparation vent -- When sec-butanol is reacted with aluminum granules
in the preparation of aluminum butoxide catalyst, hydrogen is evolved and must
-------
111-23
be vented. This hydrogen vent gas contains some sec-butanol as VOC. The composi-
tion of the vent stream is about 65% hydrogen and 33% sec-butanol, with minor
amounts of inert gases. This vent stream contains about 0.225 g of VOC per g
of allyl alcohol product (see B, Fig. III-2).
Filtration system scrubber vent -- After reaction and water addition, the aluminum
hydroxide precipitate is filtered out of the reactant stream. The filtration and
cake handling system yields a vent stream that contains about 5% acrolein. The
vent gas contains about 0.06 g of inert gas and 0.0032 g of VOC per g of allyl
alcohol product (see 83, Fig. III-2).
Lights stripper column vent — After filtration, a lights stripper column is used
to remove low boiling impurities from the product stream. This column and its
associated receiver tank are padded with methane. The vent gas from this system
contains about 50% methane, 25% acrolein, and 25% acetone and is sent to a flare
to destroy the methane and other organics. The flow rate of this vent stream to
the flare is about 0.023 g per g of allyl alcohol product, and the stream con-
tains about 0.011 g of nonmethane VOC per g of allyl alcohol product (see B3,
Fig. III-2).
Distillation system condenser vents — There are three separate distillation column
condenser vents in the allyl alcohol distillation system. These distillation
columns and their associated condenser vents have characteristic vent emissions
of 0.00016 g, 0.0016 g, and 0.0095 g of VOC per g of allyl alcohol product respec-
tively (see B4/ B5, and B6/ Fig. III-2).
glycerin -- There are four main process vents indicated on the Glycerin Section
of Fig. III-2 as follows.-
Light-ends stripper vent — Residual low-boiling impurities, principally acrolein
and allyl alcohol, are stripped out of the dilute aqueous reaction mixture.
The vent gas from this stripper column is sent to a scrubber system for removal
of these toxic vapors. The vent gas to the scrubber system contains about 14%
VOC. This vent stream contains about 0.015 g of VOC per g of glycerin product
(see Cj, Fig. III-2).
-------
111-24
Concentrator column vent — The dilute glycerin stream is concentrated by the
water in the product being evaporated. The vent from this system contains very
low levels of VOC, about 0.00015 g per g of glycerin product (see C2, Fig. III-2).
Glycerin flasher column vent -- The crude, concentrated glycerin is flashed over-
head in a vacuum stripping column to strip off the glycerin from the heavy poly-
glycol materials. The vent from the vacuum system for this column contains
very low levels of glycerin as the primary VOC, about 0.00015 g per g of glycerin
product (see C3, Fig. III-2).
Product column vent — A final-product distillation system is used to purify the
raw glycerin after it is stripped from the heavy ends. Glycerin is distilled
under vacuum to separate it out as a pure concentrated product. Bottoms from
this column are recycled to the flasher column for recovery of residual glycerin.
The vent from the vacuum system on this column contains very low levels of glycerin
as the primary VOC, about 0.00015 g per g of glycerin product (see C4, Fig. III-2).
3. Fugitive and Secondary Emission Sources
Leaks throughout the process can constitute sources of fugitive VOC emissions.
They can occur from valves, flanges, pumps, agitators, and compressors. Many of
the chemicals handled in this series of processes are highly flammable and toxic;
therefore the plant must be well designed and maintained to minimize the exposure
of operating personnel to dangerous concentrations of toxic fumes or vapors. It
is common practice to use welded bonnets on valves and double mechanical seals with
flush fluid on pumps, agitators, etc., to minimize fugitive leaks or losses of
these toxic materials.
Waste streams from the various sections of the process can be a source of secondary
emissions. The amounts and types of emissions generated by these waste streams
depend on the handling systems and disposal techniques used. Information on
the specific amounts and compositions of these waste streams is considered to
be proprietary. Five types of secondary streams are generated by this series
of processes as follows:
a. Fuel-Rich Waste Gas -- This type of waste stream is generated by the propylene
purification and recovery systems associated with the acrolein step. The principal
-------
111-25
components are methane, ethane, ethylene, propane, and propylene. The principal
technique for disposing of this material is to inject it into the plant fuel
gas manifold for use as fuel (see K, Fig. III-2).
j3_ Liquid-Organic Streams — Various liquid-organic secondary streams are generated
in this process. Most of the streams contain various flammable and toxic chemicals.
Typical sources would be the heavies and lights streams generated by the various
distillation operations. The principal disposal technique is destruction by
oxidation in a plant incinerator.
c Aqueous Streams (Toxic) — Wastewater streams containing dissolved toxic, volatile,
or hazardous organics are generated at several process steps, including scrubbing
of vent gases. Where possible, these aqueous streams are disposed of by reusing
the contaminated water in the process. Those wastewater streams containing
toxic organics that are not suitable for reuse in the process are injected into
a deep-well disposal system.
* Aqueous Streams (Nontoxic) — Wastewater streams that do not contain significant
quantities of toxic organics but still contain some dilute, relatively nonvolatile
organic material are sent to the plant wastewater treatment system for bio-oxidation.
Contaminated Solid Wastes -- This process generates various solid wastes, such
6 • — ' 'r
as filter cake, spent catalyst, and filter cartridges, that are contaminated
with toxic and flammable chemicals. The principal technique for disposing of
the contaminating organics is to burn the solids in a plant incinerator. For
those solids not amenable to incineration, a chemical treatment is used to destroy
the hazardous organic material before disposing of the solid wastes in a controlled
landfill.
process Variations
*» •
The main variations on the propylene oxidation process involve the conversion of
propylene to acrolein. Variations in the catalyst used, in the reaction conditions,
and in the reactor configuration can cause significant variations in product yields
and amount and kind of by-products. The most significant variation is the use of
air instead of purified oxygen as the source of oxygen for the propylene oxidation.
-------
111-26
The use of air puts a large stream of nitrogen as an inert gas into the reactor
system.
The nitrogen must be thoroughly scrubbed to remove acrolein and other reaction
products from the gas stream before it is vented to the atmosphere. The ratio
of propylene to oxygen is shifted to an oxygen-rich system to dodge the problem
of recovering propylene from the vent gas. The use of excess oxygen changes
the product yields and promotes the oxidation of acrolein to acrylic acid. The
presence of significant quantities of acrylic acid in the aqueous acrolein product
stream makes the recovery and purification of refined acrolein more difficult.
Part or all of the combined gas-phase output stream from the oxidizer that con-
verts propylene to acrolein oxidizer can be fed directly to another gas-phase
oxidation reactor with a different catalyst to promote the conversion of acrolein
to acrylic acid when the acrylic acid is the desired end product of the oxidation
process.7
In the liquid-phase conversion of acrolein to allyl alcohol, other hydrogen
donors can be used in place of sec-fautanol; for example, ethanol, n-propanol,
isopropanol, n-butanol, or isobutanol are all useful alcohols that can be con-
verted to the equivalent aldehydes or ketones. None of these products are used
commercially at present, however, since sec-butanol is a readily available refinery
product and methyl ethyl ketone is a valuable by-product.
Acrolein can also be converted to allyl alcohol through vapor-phase hydrogen
exchange with ethanol, but this process is not used commercially in the United
States.
Allyl alcohol can be epoxidized to glycidol for conversion to glycerin by the
use of peracetic acid instead of hydrogen peroxide. This particular process
variation is practiced by the FMC Corporation in their synthesis of glycerin
from propylene oxide.
D. ISOMERIZATION PROCESS
1. Basic Reactions and Process Description
The raw material for this process is propylene oxide. In the first step propylene
oxide is isomerized to allyl alcohol in the presence of a slurry of a proprietary
-------
111-27
catalyst suspended in a high-boiling solvent. A simple equation for this process
is
CH2-CH-CH3 >• CH2=CH-CH2OH
0
The reaction takes place at high temperature (about 300°C) and elevated pressures.
Typical by-products of this reaction include propionaldehyde, acetone, n-propanol,
acrolein, and a complex mixture of high-boiling tars.
The main-product stream exits from the isomerization reactor as a vapor and
contains unreacted propylene oxide, allyl alcohol, and the low-boiling impurities.
A series of condensation and distillation operations separate this product stream
into propylene oxide for recycle, a lights waste stream, and an allyl alcohol
product. Tars accumulate in the catalyst slurry and must be removed to prevent
deactivation of the catalyst. A sidestream of catalyst slurry is removed from
the isomerization reactor for treatment to remove the tars. The catalyst slurry
is then recycled to the isomerization reactor. The tars emerge as a separate
waste stream from the catalyst treatment system.
Peracetic acid is used as the source of oxygen in the epoxidation of allyl alcohol
to glycidol. Peracetic acid is prepared by a controlled catalytic, liquid-phase
oxidation of acetaldehyde with oxygen.8 A simple equation for this reaction is
2CH3-CHO + 02 >• 2CH3-OOOH
0
Acetic acid is a by-product in this controlled oxidation process. Separation
and purification of the reaction products yield a peracetic acid stream suit-
able for use in various epoxidation reactions.
The epoxidation of allyl alcohol to glycidol by reaction with peracetic acid
takes place according to the following simplified equation:
CH2=CH-CH2OH + CH3-C-OOH > CH2-CH-CH2OH + CH3-C-OH
0 \) 0
-------
111-28
Low temperatures, short residence times, and the presence of an auxiliary sol-
vent tend to minimize the formation of by-products. Typical by-products from
this process are acetaldehyde, propionaldehyde, methyl acetate, acrolein, meth-
anol, diallyl ether, allyl acetate, and n-propanol.
After reaction, distillation columns are used to separate the reaction products
into useful components and waste streams. Excess allyl alcohol is recovered
and recycled to the epoxidation reactor. Acetic acid is recovered, purified,
and sold as a by-product. Waste streams of lights and heavies are collected
for disposal. The inert solvent is recovered and recycled to the epoxidation
reactor. The glycidol is collected and fed to the hydrolysis reactor.
Glycidol is hydrolyzed with excess water to convert it to glycerin. The simple
reaction for this step is
CH2-CH-CH2OH + H20 * O^OH-CHOH-d^OH
0
A high temperature and excess water are used to promote this reaction. The
by-products of the reaction are polyglycols and glycol ethers. After hydrolysis
a series of distillation columns and auxiliary equipment are used to concentrate
and purify the glycerin product. A waste stream of lights in water and a heavy
waste stream are generated by this refining operation.
2. Main Process Vents
a. Isomerization — The vents used in the isomerization process are those from the
various distillation columns used to purify the product and recover the solvent
from the catalyst regeneration operation. Information on the composition and
amount of VOC in these vents is not available at this time.
b. Epoxidation Using Peracetic Acid -- The vents used in the peracetic acid epoxidatio"
process are those from the various distillation columns used to purify the glycidol
product and to recover the solvent used in the epoxidation process. Information on
the composition and amount of VOC in these vents is not available at this time.
-------
m-2y
c. Glycerin — The vents used in the glycerin process using glycidol from the peracetic
acid epoxidation route are the same as those used in the glycerin process discussed
previously in which glycidol is derived from hydroperoxide epoxidized allyl alcohol.
For a detailed discussion of these vents, refer to Sect. III-C-2-c of this report.
3 Fugitive and Secondary Emission Sources
Leaks throughout the process can be sources of fugitive VOC emissions. Fugitive
emissions can occur from valves, flanges, and moving shafts. Many of the chemicals
are highly flammable and/or toxic; so the plant must be well designed and maintained
to minimize the exposure of operating personnel to dangerous concentrations of
toxic fumes or vapors.
Waste streams from the various sections of the process can be a source of secondary
emissions. The amounts and types of emissions generated by these waste streams
depend on the handling systems and disposal techniques used. Specific data on the
amount and composition of these waste streams are not available at this time.
4 process Variations
In the isomerization process for converson of propylene oxide to allyl alcohol the
specific catalyst used affects the conversion rate and the ratio of allyl alcohol
to the by-products. Vapor-phase isomerization techniques have been investigated
and patented, but the only commercial operation in the United States is the
liquid-phase isomerization process operated by the FMC Corporation at Bayport, TX.
Once allyl alcohol is produced by isomerization of propylene oxide, the rest of
the process is similar to the Shell process for conversion of allyl alcohol to
glycerin. FMC uses peracetic acid to epoxidize allyl alcohol to glycidol instead
of using hydrogen peroxide and catalyst as Shell does. The use of peracetic
acid involves the recovery of acetic acid from the glycidol product stream.
-------
Ill-30
E. REFERENCES*
1. R. G. Muller, Glycerin and Intermediates, Report No. 58, A private report by
the Process Economics Program, Stanford Research Institute, Menlo Park, CA
(December 1969).
2. S. L. Soder and K. L. Ring, "Propylene," pp. 300.5405E—300.5405L and
300.5405Q—300.5405R in Chemical Economics Handbook, Stanford Research
Institute, Menlo Park, CA (August 1978).
3. D. Osterhof, "Glycerin," pp. 662.5021A—662.5023E in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park, CA (April 1976).
4. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Deer Park, TX, Jan. 25, 1978 (on file at EPA, ESED,
Research Triangle Park, NC).
5. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Dow
Chemical Co. Process at Freeport, TX, Jan. 26 and 27, 1978 (on file at EPA,
ESED, Research Triangle Park, NC).
6. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Norco, LA, Jan. 25, 1978 (on file at EPA, ESED, Research
Triangle Park, NC).
7. F. D. Bess, Union Carbide Corp., Taft, LA, letter to EPA, Apr. 21, 1978, in
response to EPA request for information on the Union Carbide acrolein process.
8. H. J. Hagemeyer, "Acetaldehyde," pp. 100 and 109 in Kirk-Othmer Encyclopedia of
Chemical Technology, 3d ed., Vol. 1, edited by M. Grayson et al., Wiley-Interscience
New York, 1978.
*When a reference number is used at the end of a paragraph or on a heading, it
usually refers to the entire paragraph or material under the heading. When,
however, an additional reference is required for only a certain portion of the
paragraph or captioned material, the earlier reference number may not apply to
that particular portion.
-------
IV. EMISSIONS
Emissions in this report are usually identified in terms of volatile organic
compounds (VOC) . VOC are currently considered by the EPA to be those of a large
group of organic chemicals, most of which, when emitted to the atmosphere, parti-
cipate in photochemical reactions producing ozone. A relatively small number
of organic chemicals have low or negligible photochemical reactivity. However,
many of these organic chemicals are of concern and may be subject to regula-
tion by EPA under Section 111 or 112 of the Clean Air Act since there are
associated health or welfare impacts other than those related to ozone formation.
CHLORINATION PROCESS
Model .Plant
The model-plant flowsheets (Figs. III-l.A — l.C) used for this study are not
identical to either one of the existing commercial chlorination processes for
the production of allyl chloride, epichlorohydrin, and glycerin, but they are
close enough so that a study of their processes and emission points will give a
valid understanding of the commercial operations.1'2
No estimates of typical raw-material, by-product, intermediates, or finished-
product storage tank requirements have been made for this study.
Sources and Emissions
Emission factors and sources for the vents used in the chlorination process are
summarized in Table IV-1.2'3 The emission factors were derived from existing
plant data, as well as from theoretical calculations in which vapor pressure and
quantity of inert or sweep gas were used. No attempts have been made to estimate
storage and handling, fugitive, or secondary emissions. The one known fugitive
emission is included in the table.
OXIDATION PROCESS
B-
Model Plant
The model-plant block flowsheet (Fig. III-2) used for this study is a copy of
the block flowsheet furnished by Shell on their acrolein-glycerin process.4
-------
Table IV-1. Uncontrolled VOC Emissions for the Chlorination Process Model Plant
Process Step
Source
Stream
Designation
(Figs.III-l.A—C)
Emission
Ratio
(g/Mg)
Principal Components of
VOC Emission Streamsc
Allyl chloride (Fig.III-l.A)
HC1 absorber vent
Light-ends dist. column vent
Allyl chloride dist. column vent
Dichloropropene dist. column vent
Epichlorohydrin (Fig.III-l.B)
Epoxidation reactor vent
Azeotrope column vent
Lights stripping column vent
Finishing column vent
Glycerin (Fig.III-l.C, pp. 1,2)
Carbon dioxide absorber vent
Evaporator vent
Concentrator vent
Stripping column vent
Light-ends column vent
Solvent stripping column vent
Product column vent
Cooling tower
B]
B,
B.
B,
K
15
100—200
50,000—80,000
Up to 100
Up to 1000
Up to 20,000
Up to 800
Up to 8000
Up to 400
400
Less than 100
Less than 100
Less than 100
Less than 100
200
Less than 100
2800
C hydrocarbons
C chlorinated hydrocarbons
Allyl chloride
Dichlorinated C hydrocarbons
Epichlorohydrin
Epichlorohydrin
C.j chlorinated hydrocarbons
Epichlorohydrin
C chlorinated hydrocarbons
C oxygenated hydrocarbons
C oxygenated hydrocarbons
Glycerin
C oxygenated hydrocarbons
Acetone
Acetone
Acetone
f
NJ
Refer to refs 2 and 3.
Dg of total VOC per Mg of product produced.
Only those components on Wni.cn data were available are listed.
-------
IV-3
No estimates of typical raw material, by-product, intermediates, or finished-
product storage tank requirements have been made for this study.
2. Sources and Emissions
Emission factors and sources for the vents from the oxidation process are sum-
marized in Table IV-2.4 No attempts have been made to estimate storage and
handling, fugitive, or secondary emissions.
o Process Variation
Process vent information has been furnished by Union Carbide on their variation of
the oxidation process for the production of acrolein. They do not convert acrolein
to allyl alcohol or allyl alcohol to glycerin. See Sect. III-C.4, paragraphs 1
and 2, for a description of this process variation. Their emission data on acrolein
process vents is presented in Table IV-3. No attempts have been made to estimate
storage and handling, fugitive, or secondary emissions.5
c ISOMERIZATION PROCESS1
No attempt has been made to prepare model plant flowsheets or to estimate vent
emissions from this process. The isomerization step in which propylene oxide
is converted to allyl alcohol would have its own characteristic emissions. The
peracetic acid manufacturing process in which acetaldehyde is oxidized to peracetic
acid would also have its own characteristic emissions.6 The conversion of allyl
alcohol to glycidol and the hydrolysis of glycidol to glycerin would be somewhat
different with peracetic acid used as the epoxidizing agent instead of hydrogen
peroxide, but the characteristic emissions are expected to be similar to the emis-
sions found for the glycerin sequence of the oxidation process shown in Table IV-2.
-------
Table IV-2. Uncontrolled VOC Emissions for the Oxidation Process Model Planta
Stream
Designation
Process Step Source (Fig.III-2)
Acrolein
Carbon dioxide stripping tower vent
Aqueous acrolein receiver vent
Distillation system vent
Refrigeration vent, intermittent
Allyl alcohol
Catalyst preparation vent
Filtration system vent
Lights stripper column vent
Distillation system condenser vents
Glycerin
Light-ends stripper vent
Concentrator column vent
Glycerin flasher column vent
Product column vent
Al
A2
A3
I2
Bl
B2
B3
B4
B5
B6
Cl
C2
C3
C4
Emission
Ratio ,
(g/Mg)
61,000
3,000
7,500
27,000
225,000
3,200
11,000
160
1,600
9,500
15,000
150
150
150
Principal Components
VOC Emission Streams
C hydrocarbons (and carbon
Acrolein (5%; methane, 95%)
Acrolein (5%; methane, 95%)
C hydrocarbons (and carbon
sec-Butanol (33%; hydrogen,
of
c
monoxide)
monoxide)
65%)
Acrolein (5%; inert gas)
Acrolein (25%), acetone (25%) f
(methane, 50%)
sec-Butanol and methyl ethyl
Allyl alcohol
Methyl ethyl ketone
Acrolein and allyl alcohol
C oxygenated hydrocarbons
Glycerin
Glycerin
ketone
Refer to ref 4.
g of total VOC emission per Mg of product produced. VOC emissions
include higher molecular weight organic compounds.
°Only those components on which data were available are listed.
exclude methane, carbon monoxide, and hydrogen, but
-------
IV-5
Table IV-3. Uncontrolled VOC Emissions for the Union Carbide
Variation of the Oxidation Process (Acrolein Only)a
Source
Acrolein absorber vent
Stream
Designation
1
Emission
Ratio
(g/Mg)b
126,000
Principal Components
of VOC Emissions
Acrolein, 0.61%, propane, 0.40%,
Combined distillation
system vent header
2a-e
and propylene, 0.61%
38,300 Acrolein, 77.7%, and
acetaldehyde, 18.9%
See ref 5.
g of total VOC emission per Mg of acrolein produced.
-------
IV-6
D. REFERENCES*
1. R. G. Muller, Glycerin and Intermediates, Report No. 58, A private report by
the Process Economics Program, Stanford Research Institute, Menlo Park, CA
(December 1969).
2. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Dow
Chemical Co. Process at Freeport, TX, Jan. 26 and 27, 1978 (on file at EPA,
ESED, Research Triangle Park, NC).
3. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Deer Park, TX, Jan. 25, 1978 (on file at EPA, ESED,
Research Triangle Park, NC).
4. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Norco, LA, Jan. 25, 1978 (on file at EPA, ESED, Research
Triangle Park, NC).
5. F. D. Best, Union Carbide Corp., Taft, LA, letter to EPA, Apr. 21, 1978, in
response to EPA request for information on the Union Carbide acrolein process.
6. H. J. Hagemeyer, "Acetaldehyde", pp. 100, 109 in Kirk-Othmer Encyclopedia
of Chemical Technology, 3rd ed., Vol 1, edited by M. Grayson et al., Wiley-
Interscience, New York, 1978.
*When a reference number is used at the end of a paragraph or on a heading,
it usually refers to the entire paragraph or material under the heading.
When, however, an additional reference is required for only a certain portion
of the paragraph or captioned material, the earlier reference number may not
apply to that particular portion.
-------
V-l
V. APPLICABLE CONTROL SYSTEMS
A. CHLORINATION PROCESS1—3
A summary of controlled emissions for the chlorination process is given in Table V-l.
1. Allyl Chloride
a. HC1 Absorber Vent (See Vent A, Fig. V-l.A)* The stream from this vent contains
residual propylene from the propylene-HCl stripping column. Proper design and
operation of the stripping column is the key to maintaining low levels of propylene
in the vent from the HCl absorber. It would be possible to collect this vent
gas and send it to a plant flare for destruction, but the amount of VOC normally
emitted is probably too low to justify the collection system piping that would
be required. For a 113-Gg/yr plant the hourly emissions from this source would
be about 1 to 3 kg.
k Light-Ends Distillation Column Vent (See Vent A2, Fig. V-l.A) The stream from
this vent is the largest single vent stream in the allyl chloride section of
the process. For a 113-Gg/yr plant the hourly emissions from this source would
be about 650 to 900 kg. The VOCs in the stream are low-value C2-C3 organics
and chlorinated C2-C3 organics. Three possible options could be used to reduce
these emission levels: (1) Installation of a refrigerated vent condenser to
condense a large share of the VOC and return it to the condensate stream from
this column. Depending on location, design, and operating conditions a vent
condenser might remove 60 to 95% of the VOC.4 (2) Collection of the vent stream
and sending it to the plant flare system. A properly designed and operated
flare system should destroy at least 98% of the VOC contained in the vent stream,
but would cause the emission of HCl vapors to the atmosphere.5 (3) Installation
of an activated-carbon adsorption system to strip the VOC from the vent gas and
collect the recovered VOC. A properly designed and operated adsorption system
can remove at least 99% of the VOC. Vent gas incineration (flare) is probably
the most cost-effective technique for removal of this VOC if HCl vapor emission
can be tolerated. (A confined incinerator with water scrubbing could remove
HCl from the flue gas.)
*Figures V-l.A, B, and C and V-2 are duplicates of the flowsheets discussed in
Sect. III.
-------
Table V-l. Controlled VOC Emissions for the Chlorination Process Model Plant
Stream
Designation
Process Step Source (Fig.III-1)
Allyl chloride
HC1 absorber vent
Light— ends dist. column vent
Allyl chloride dist. column vent
Dichloropropene dist. column vent
Epichlorohydrin
Epoxidation reactor vent
Azeotrope column vent
Lights stripping column vent
Finishing column vent
Glycerin
Carbon dioxide absorber vent
Evaporator vent
Concentrator vent
Stripping column vent
Light-ends column vent
Solvent strippping column vent
Product column vent
Cooling tower
Al
A2
A3
A4
Bl
B2
B3
B4
Cl
C2
C3
C4
C5
C6
C7
K15
Control
Technique
None
Flare
None
Scrubber
Use of NaOH
or Ca(OH)2
Scrubber
Flare
None
None
None
None
None
None
None
None
Steam strip
wastewater
Emission
Reduction
(%)
0
98
0
50
99
84
98
0
0
0
0
0
0
0
0
95
Emission
Ratio*
(g/Mg)
100 — 200
1,000 — 1,400
Up to 100
Up to 500
200
130 ?
NJ
Up to 160
Up to 400
400
Less than 100
Less than 100
Less than 100
Less than 100
200
Less than 100
140
*q of total VOC emissions per Mg of product produced.
-------
-PaA.1 f= /G.A-r/OAt__S£C.
Fig. V-l.A. Uncontrolled Model-Plant Flowsheet for Production of Allyl Chloride
-------
V-4
c. Allyl Chloride Distillation Column Vent (See Vent A3, Fig. V-l.A) The stream
from this vent is relatively small and insignificant. For a 113-Gg/yr plant
the hourly emission rate would be less than 1.3 kg. Either a vent condenser or
a collection system for piping the vent gas to the plant flare could be used to
reduce the emission, but the cost-benefit ratio would be high. Flaring of these
vapors would result in HC1 vapor emissions.
d. Dichloropropene Distillation Column Vent (See Vent A4, Fig. V-l.A) The stream
from this vent is significant in size. For a 113-Gg/yr plant the hourly emission
rate would be less than 13 kg. Dichloropropene is toxic in both liquid and
vapor form; so the VOC emission must be reduced for protection of plant personnel-
A scrubber system, vent condenser, or vent gas incineration (to collect the gas
and pipe it to plant flare) could be used to reduce this VOC emission. Flaring
of these vapors would result in HC1 vapor emissions.
2. Epichlorohydrin
a. Epoxidation Reactor Vent (See Vent B, Fig. V-l.B) The stream from this vent
can constitute the largest single emission in the epichlorohydrin section of
the process. For a 113-Gg/yr plant the hourly emission rate could be as low as
2.6 kg or as high as 260 kg. Emission levels depend on process design, operating
conditions, and the alkali source used in the ring-closing reaction. Use of a
carbonate (such as sodium carbonate or calcium carbonate) as the alkali source
releases large quantities of carbon dioxide as a by-product of the ring-closing
reaction. The large volume of carbon dioxide then acts as a sweep gas and carri*8
a large amount of epichlorohydrin vapor along with the carbon dioxide as the
gas exits from the reactor vent. The most effective technique for reduction of
VOC from this vent would be the use of a noncarbonate alkali (such as sodium
hydroxide solution or calcium hydroxide slurry) to neutralize the hydrochloric
acid and close the epoxide ring. Other techniques that are possible include
the use of activated-carbon adsorption or vent gas incineration. Depending
on the cost of non-carbonate- versus car'>onate-containing alkali, an alter-
native technolgy such as activated carbon adsorption or vent gas incineration
may sometimes be cheaper.
-------
Fig. V-l.B. Uncontrolled Model-Plant Flowsheet for Production of Epichlorohydrin
-------
V-6
b. Azeotrope Column Vent (See Vent B2, Fig. V-l.B) The stream from this vent is
not a very large source of VOC emissions. For a 113-Gg/yr plant the hourly
emission rate is less than 10 kg. Techniques that can be used to reduce the
amount of VOC emitted by this vent include vent gas incineration, vent gas
scrubbing, or activated-carbon adsorption. Any technique used to remove VOC
from this stream would be rather expensive in terms of money spent per unit of
VOC reduced.
c. Lights Stripping Column Vent (See Vent B3, Fig. V-l.B) The stream from this
vent can be a significant source of VOC emissions. For a 113-Gg/yr plant the
hourly emission rate is less than 100 kg. The amount of VOC emitted by this
vent can be reduced by vent gas incineration, vent gas scrubbing, refrigerated
vent condenser, or activated-carbon adsorption. Vent gas incineration (flare)
is probably the most cost-effective means for removal of the VOC.5
d. Epichlorohydrin Finishing Column Vent (See Vent B4, Fig. V-l.B) The stream
from this vent is not a very large source of VOC emissions. For a 113-Gg/yr
plant the hourly emission rate is less than 5 kg. The amount of VOC emitted
by this vent can be reduced by vent gas incineration, vent gas scrubbing, refrig-
erated vent condenser, or activated-carbon adsorption. Any technique used to
remove VOC from this stream would probably not be very cost effective.
3. Glycerin
a. Carbon Dioxide Absorber Vent (See Vent C Fig. V-l.C, p. 1) The stream from
this vent is not a very large source of VOC emissions. For a 55-Gg/yr plant
the hourly emission rate is about 2.5 kg. The amount of VOC emitted by this
vent can be reduced by vent gas incineration or activated-carbon adsorption.
Because of the small amount of VOC in this vent any technique used to reduce
this VOC emission would not be very cost effective.
b. Evaporator Vent (See Vent C2, Fig. V-l.r, p. 1) The VOC content in the stream
from this vent is extremely low.
c. Concentrator Vent (See Vent C3/ Fig. V-l.C, p. 1) The VOC content in the gas
emitted from this vent is extremely low.
-------
Fig. V— l.C. Uncontrolled Model-Plant Flowsheet for Production of Glycerin by the Chlorination Process
Page 1 of 2
-------
(. vs.
Fig. V-l.C (Continued)
2 o£ 2
-------
V-9
d- Stripping Column Vent (See Vent C4, Fig. V-l.C, p. 2) The VOC content in the
stream from this vent is extremely low.
e. Light-Ends Column Vent (See Vent C5/ Fig. V-l.C, p. 2) The VOC emitted from
this vent is extremely low.
£. Solvent Stripping Column Vent (See Vent C6, Fig. V-l.C, p. 2) The VOC content
in the stream from this vent is low. For a 55-Gg/yr plant the hourly emission
rate is about 1.3 kg. The amount of VOC emitted by this vent can be reduced by
vent gas incineration, vent gas scrubbing, refrigerated vent condenser, or acti-
vated-carbon adsorption. However, because of the small amount of VOC emitted,
reduction techniques would not be very cost effective.
g. Product Column Vent (See Vent C7, Fig. V-l.C, p. 2) The VOC content in the
gas from this vent is extremely low.
h. Cooling Tower (See K15, Fig. V-l.C, p. 2) The cooling tower emits a significant
amount of VOC. For a 55-Gg/yr plant the hourly emission rate is about 17 kg of
VOC, predominantly acetone. The main source of the VOC is the aqueous condensate
from the water condenser on the product column. This contaminated water stream
is used as part of the makeup water in the cooling tower. The acetone in the
water stream from the product column has a low concentration and can best be
eliminated by being steam stripped or vacuum stripped from the product column
water condensate stream in a stripping-rectification column. In that way the
recovered acetone could be recycled to the process. A cost-effectiveness study
is needed to determine the cost associated with this method of reducing the VOC
emission.
„ OXIDATION PROCESS1'6
p •
Table V-2 summarizes the controlled emissions for the oxidation process.
- Acrolein
j- •
Carbon Dioxide Stripping Tower Vent (See Vent At, Fig, V-2) The stream from
this vent is the largest single vent stream in the acrolein section of the oxi-
dation process. For a 25-Gg/yr plant the hourly emission rate for VOC, principally
-------
Table V-2. Controlled VOC Emissions for the Oxidation Process Model Plant
Process Step
Acrolein
Allyl alcohol
Glycerin
Source
Carbon dioxide stripping tower
vent
Aqueous acrolein receiver vent
Distillation system receiver
vent
Catalyst preparation vent
Filtration system vent
Lights stripper column vent
Distillation system vents (3)
Light ends stripper vent
Concentrator column vent
Glycerin flasher column vent
Product column vent
Furnace vent
Stream
Designation
(Fig.III-2)
A
A2
A3
Bl
B2
B3
B4
B5
B6
Cl
C2
C3
C4
C5
Control
Technique
Flare
Flare
Flare
Vent condenser
Scrubber
Flare
b
None
Vent condenser
Vent condenser
Scrubber
None
None
None
None
Emission
Reduction
98
98
98
99
95
98
0
95
80
97
0
0
0
0
Emission
Ratio
(g/Mg)
120
60
150
2250
160
220
160
80
1900
450
150
150
150
150
f
g of total VOC emissions per Mg of product produced.
Process condenser keeps emissions low.
-------
&CC-
, OOO
II. 3. ff Gi
Fig. V-2. Block Flowsheet of Oxidation Process for Uncontrolled Model Plant Producing Synthetic Glycerin
-------
V-12
C2 and C3 hydrocarbons, in this stream would be about 175 kg. The most satis-
factory technique for removal of the VOC is incineration in a plant flare. A
properly designed and operated flare should reduce the VOC by at least 98%.5
b. Aqueous Acrolein Receiver Vent (See Vent A2, Fig. V-2) The discharge from the
vent scrubber on the receiver vent contains VOC. For a 25-Gg/yr plant the hourly
emission rate for the VOC, principally acrolein, would be about 8.5 kg (accompanied
by about 162 kg of methane). Since acrolein is highly toxic in both liquid and
vapor form, safety considerations would not permit its discharge to the atmosphere.
The most satisfactory technique for its removal is incineration in a plant flare.
A properly designed and operated flare should reduce the VOC by at least 98%.5
c- Distillation System Receiver Vent (See Vent A3/ Fig. V-2) The discharge from
the column receivers on the distillation system is a source of VOC emissions.
For a 25-Gg/yr plant the hourly emission rate for the VOC, principally acrolein,
in this stream would be about 21 kg (accompanied by about 400 kg of methane).
Since acrolein is highly toxic in both liquid and vapor form, safety considerations
would prohibit its discharge to the atmosphere. The most satisfactory technique
for its removal is incineration in a plant flare. A properly designed and operated
flare should reduce the VOC by at least 98%.5
2. Allyl Alcohol
a- Catalyst Preparation Vent (See Vent Bl7 Fig. V-2) This vent discharges hydrogen
and sec-butanol vapor from the catalyst preparation reactor. For a 25-Gg/yr
plant the hourly emission rate of VOC in this stream is about 640 kg. The VOC
emission can be reduced by use of vent gas incineration (flare), scrubber vent,
vent condenser, or activated-carbon adsorption.4'5
b- Filtration System Vent (See Vent B2, Fig. V-2) The vent gas from the filtration
system contains significant quantities of toxic VOC. For a 25-Gg/yr plant the
hourly emission rate of VOC in this stream is about 9 kg. Since the vapors are
toxic, safety considerations require that the VOC be removed. Removal techniques
include vent gas scrubbing, vent gas incineration, or activated-carbon adsorption.4'5
-------
V-13
c. Lights Stripper Column Vent (See Vent B3, Fig. V-2) The vent stream from this
column system is a large and significant vent stream in the allyl alcohol section
of the oxidation process. For a 25-Gg/yr plant the hourly rate of VOC emissions
in this stream is about 31 kg (accompanied by about 31 kg of methane). The VOC
emitted by this vent is about 50% acrolein, which is highly toxic in both vapor
and liquid form. Safety considerations require that this toxic VOC be removed.
Removal techniques include vent gas incineration (to flare), refrigerated vent
condenser, vent gas scrubbing, or activated-carbon adsorption.4'5
d. Distillation System Column Vents (See Vents B4, B5, and B6, Fig. V-2) There
are three individual vents from the distillation system columns and each one
contains significant quantities of VOC. For a 25-Gg/yr plant the hourly rate
of VOC emissions from these three vents is 0.46 kg, 4.6 kg, and 27 kg, respectively.
The VOC can be removed from these vent streams by vent condensers, vent gas
incineration, vent gas scrubbing, or activated-carbon adsorption.4'5
3. Glycerin
a. Light-Ends Stripper Vent (See Vent C:, Fig. V-2) The gas stream from this
vent is the largest and only significant VOC process emission stream in the
glycerin section of the oxidation process. For a 25-Gg/yr plant the hourly
rate of VOC emissions from this vent is about 43 kg. This VOC stream contains
acrolein and allyl alcohol, which are toxic in both liquid and vapor form and
therefore for safety considerations must be removed. They can be removed by a
vent condenser, a vent gas scrubber, vent gas incineration, or activated-carbon
adsorption.4'5
b Concentrator Column Vent (See Vent C2, Fig. V-2) The VOC content of the gas
emitted by this vent is extremely low.
Glycerin Flasher Column Vent (See Vent C3, Fig. V-2) The VOC content of the
stream from this vent is very low.
, Product Column Vent (See Vent C4, Fig. V-2) The VOC content in the gas emitted
by this vent is very low.
-------
V-14
e. Furnace Vent (See Vent C5, Fig. V-2) The VOC content in the stream from this
vent is very low.
C. OXIDATION PROCESS VARIATION (ACROLEIN ONLY)1'7
The controlled emissions for this oxidation process variation are summarized in
Table V-3.
1. Acrolein Absorber Vent
This stream from this vent is a source of an extremely large and significant
VOC process emission. For a 25-Gg/yr plant the hourly rate of VOC emissions
Table V-3. Controlled VOC Emissions for the Union Carbide Variation of the
Oxidation Process (Acrolein Only)
Source
Acrolein absorber vent
Combined distillation
system vent header
Stream
Designation
1
2a-e
Control
Technique
Thermal oxidation
Flare
Emission
Reduction
(%)
99
98
Emission
Ratio*
(g/Mg)_
1260
760
•
*g of total VOC emission per Mg of acrolein produced.
from this source is about 360 kg. Acrolein constitutes about 40% of the total
VOC. Since acrolein is a highly toxic material in both liquid and vapor form,
safety considerations require its removal from the vent stream. The VOC can be
removed by vent gas incineration or activated-carbon adsorption.5
2. Combined Distillation System Vent Header
This stream from this vent is a significant source of VOC process emissions.
For a 25-Gg/yr plant the hourly rate of VOC emissions, principally acrolein,
from this source is about 109 kg. Since acrolein is a highly toxic material in
both liquid and vapor from, safety considerations require that it be removed
from this vent stream. The VOC can be removed by vent gas incineration (in-plant
flare), refrigerated vent condensers, vent scrubbers, or activated-carbon adsorp-
tion.4'5
-------
V-15
ISOMERIZATION PROCESS
No data are currently available on emissions for this process, and so no estimates
on emission reduction techniques or possible amounts of emission reduction can
be made.
-------
V-16
E. REFERENCES*
1. R. G. Muller, Glycerin and Intermediates, Report No. 58, A private report by
the Process Economics Program, Stanford Research Institute, Menlo Park, CA
(December, 1969).
2. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Deer Park, TX, Jan. 25, 1978 (on file at EPA, ESED,
Research Triangle Park, NC).
3. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Dow
Chemical Co. Process at Freeport, TX, Jan. 26 and 27, 1978 (on file at EPA,
ESED, Research Triangle Park, NC).
4. D. Erikson, IT Enviroscience, Inc., Control Device Evaluation—Condensation, in
preparation.
5. V. Kalcevic, IT Enviroscience, Inc., Control Device Evaluation—Flares and Boiler!
in preparation.
6. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Norco, LA, Jan. 25, 1978 (on file at EPA, ESED, Research
Triangle Park, NC)
7. F. D. Best, Union Carbide Corp., Taft, LA, letter to EPA, Apr. 21, 1978, in
response to EPA request for information on the Union Carbide acrolein process.
*When a reference number is used at the end of a paragraph or on a heading, it
usually refers to the entire paragraph or material under the heading. When,
however, an additional reference is required for only a certain portion of the
paragraph or captioned material, the earlier reference number may not apply to
that particular portion.
-------
VI-1
VI. IMPACT ANALYSIS
f,. CONTROL COST IMPACT
No estimates of control costs or cost effectiveness have been prepared for this
abbreviated report.
B. ENVIRONMENTAL IMPACTS
1. Chlorination Process1'2
Table VI-1 lists the environmental impact of reduced VOC emissions by applica-
tion of the described control systems to the chlorination process for synthetic
glycerin and/or intermediates.
2. Oxidation3
Table VI-2 gives the environmental impact of reduced VOC emissions by applica-
tion of the described control systems to the oxidation process for synthetic
glycerin and/or intermediates.
3. Oxidation Process Variation (Acrolein Only)4
Table VI-3 shows the environmental impact of reduced VOC emissions by applica-
tion of the described control systems to the oxidation process for synthetic
acrolein.
4_ Isomerization Process
No information is available at present to permit the estimation of environmental
impacts from this process.
c SUMMARY
The emission estimates for the various model plants are summarized in Table VI-4
in terms of controlled versus uncontrolled emissions based on SRI data for 1977
production levels.1—7
Since most of the emissions produced in the manufacture of glycerin intermediates
(such as allyl chloride, epichlorohydrin, acrolein, allyl alcohol, etc.) are
volatile and toxic organics, safety requirements dictate that they be controlled
to protect operating personnel. Because of the safety hazards and the resultant
-------
VI-2
Table VI-1. Environmental Impact from Controlled
Chlorinated Process Model Plant
Process
Step
Allyl chloride
(Fig.III-l.A)
Epichlorohydrin
(Fig.III-l.B)
Glycerin
(Fig.IH-i.c,
PP. 1,2)
Stream Emission Emission
Designation Control Reduction Reduction
Source (Figs. III-l.A — C) Technique (%) Ratio (g/M95*
HC1 absorber vent
Light-ends dist.
column vent
Allyl chloride dist.
column vent
Dichloropropene
dist. column vent
Epoxidation
reactor vent
Azeotrope column
vent
Lights stripping
column vent
Finishing column
vent
Carbon dioxide
absorber vent
Evaporator vent
Concentrator vent
Stripping column
vent
Light-ends column
vent
Solvent stripping
column vent
Product column vent
Cooling tower
Al
A2
A,
3
A4
*4
B.
1
B2
B3
B4
C.
1
C2
C,
3
C4
C5
C6
C7
K15
Hone
Flare
None
Scrubber
Use of NaOH
or Ca(OH>2
Scrubber
Flare
None
None
None
None
None
None
None
None
Steam stripper
0
98
0
50
99
84
98
0
0
0
0
0
0
0
0
95
0
980—1370
0
Up to 500
19,800
Up to 670
Up to 7840
0
0
0
0
0
0
0
0
2660
*g of VOC emission reduced per Mg of product produced.
-------
VI-3
Table VI-2. Environmental Impact from Controlled
Oxidation Process Model Plant
Process
Step
jicrolein
Allyl alcohol
Glycerin
ag of total VOC
Source
Carbon dioxide
stripping tower
vent
Aqueous acrolein
receiver vent
Distillation system
receiver vent
Catalyst preparation
vent
Filtration system
vent
Lights stripper
column vent
Distillation system
vents (3)
Light-ends strip-
per vent
Concentrator
column vent
Glycerin flasher
column vent
Product column
vent
Furnace vent
emission reduced per Mg
Stream
Oesianation
Al
A
A3
Bl
B2
B3
B4
B5
B6
Cl
C2
C3
C.
4
C5
of product
Control
Technique
Flare
Flare
Flare
Vent condenser
Scrubber
Flare
b
None
Vent condenser
Vent condenser
Scrubber
None
None
None
None
produced.
Emission Emission
Reduction Reduction
( %) Ratio(q/Mq)
98 59,800
98 2940
98 7350
99 223,000
95 3000
98 10,800
90 1440
80 7600
97 14,500
Process condenser keeps emissions low.
-------
VI-4
Table VI-3. Environmental Impact from controlled Oxidation Process Variation
(Acrolein Only)
Source
Acrolein absorber vent
Combined distillation
system vent header
Stream
Designation
1
2a-e
Control
Technique
Thermal oxidation
Flare
Emission
Reduction
99
98
Emission
Redact io*
Ratio (
-------
Table VI-4. Comparison of Controlled and Uncontrolled Emissions in the Synthesis
of Glycerin and/or Intermediates at 1977 Production Levels
Process
Chlorination
Oxidation
Oxidation
variation
Isomerization
Product
Allyl chloride
Epichlorohydrin
Glycerin
Acrolein
Allyl alcohol
Glycerin
Acrolein
Allyl alcohol
Peracetic acid
Glycerin
Estimated
1977 Production
(Gg/yr)
132
132
29.5
10.6
9.8
13.6
9.8
11.2
15. lb
15.9
Emission Ratio (g/Mg)
Uncontrolled
61,250
29,200
3,900
71,500
250,500
15,600
164,300
Unknown
Unknown
Unknown
Controlled
1,950
890
1,240
33O
4,770
1,050
2,020
Unknown
Unknown
Unknown
Emission Rate
Uncontrolled
923
440
13
86.5
280.2
24.2
184
Unknown
Unknown
Unknown
(ka/hr)
Controlled
29.4
13.4
4.2
0.4
5.3
1.6
<
u
2.3
Unknown
Unknown
Unknown
g of total VOC emission per Mg of product produced.
""Additional peracetic acid is produced for use in other processes.
-------
VI-6
emission control, most production facilities for the manufacture of synthetic
glycerin and/or the intermediates produce emissions similar to those listed for
the applicable controlled model plant. Process emission estimates for the entire
domestic production of synthetic glycerin and its intermediates are presented
in Table VI-4 for 1977. By counting the intermediates as separate products,
the total production for 1977 was estimated to be 338 Gg, with process VOC emissions
constituting 490 Mg. Even though no growth is projected for synthetic glycerin,
some of the intermediates do have significant growth rates. Based on projected
growth rates, the 1979 emission level is estimated to be 537 Mg. The VOC emissions
estimate does not include fugitive, secondary, or storage emissions, which are
expected to be lower than typical for the SOCMI because of toxic considerations.
Since the emission ratios for the isomerization process are not known, production
quantities and emissions for this process are not included in the above estimates.
-------
VI-7
D. REFERENCES*
1. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Deer Park, TX, Jan. 25, 1978 (on file at EPA, ESED,
Research Triangle Park, NC).
2. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Dow
Chemical Co. Process at Freeport, TX, Jan. 26 and 27, 1978 (on file at EPA,
ESED, Research Triangle Park, NC).
3. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Norco, LA, Jan. 25, 1978 (on file at EPA, ESED, Research
Triangle Park, NC).
4. F. D. Best, Union Carbide Corp., Taft, LA, letter to EPA, Apr. 21, 1978, in
response to EPA request for information on the Union Carbide acrolein process.
5. D. Oosterhof, "Glycerin," pp. 662.5021A—662.5023E in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park, CA (May 1978).
6. J. L. Blackford, "Epichlorohydrin," pp. 642.3021A—E and 642.3022A—V in Chemical
Economics Handbook, Stanford Research Institute, Menlo Park, CA (May 1978).
7. S. L. Soder and K. L. Ring, "Propylene," pp. 300.5405E—300.5405L and
300.5405Q—300.5405R in Chemical Economics Handbook, Stanford Research
Institute, Menlo Park, CA (August 1978).
*When a reference number is used at the end of a paragraph or on a heading, it
usually refers to the entire paragraph or material under the heading. When,
however, an additional reference is required for only a certain portion of the
paragraph or captioned material, the earlier reference number may not apply to
that particular portion.
-------
Table A-l. Physical properties of Organic Ra« Materials, Intermediates, End Products, and By-Products3
Molecular
product Mane formula
kcetaldahyde Olj-CxW
Acetic .ae»d Cxij-ooon
acioUini CHj-iH-cao
Ulyl alcohol CBj-CB-CHjOa
JUlyl chloride CBj-CH-CHjCl
aec-8«anol CBj-CBOB-Olj-CHj
«ee-8»itanone CSj-CO-O^-CBj
Dichlorohyiria OjCl-CBOB-CBjCl
OjCl-OKl-CBjOB
Otchloroprooen* C1*4C12 lmi*t<1">
Bplcalorohrdria aV/"~cia|Cl
* -'
Clycecin ajCH-CBOB-CHjOB
Glyclool CaU^CB-QljO"'
o
HX../1 ethyl kounej f
0,-C-eHj-CHj
Perec.tic acid Qlj"S"al*
0
Propyleae CBiclw3lJ
rropyiene oxide ^J*"?1^8*
Molecular
44. OS
60. OS
S6.M
58.08
76. S3
74.11
72.10
128.99
110.98
»J. S3
92.09
74.08
7J.2
7*. 05
42.06
58.08
•oiling Melting
Point CC1 Point (*CI
20.4 -123. S
118.1 16.6
52.7 -87.7
97.2 -129
44.6 -134.5
99.4 -114.7
79.6 -86.9
174.3 <-20
182
116.1 -S7.1
290 18
Wt-7
79.6 -86. JJ
105 0.1
-47.7 -IBS
35
Vapor Preaaure Specific
(Pa) Gravity
1. X 10& at 20 -C 0.78
l.OS
2.8 X 10* it 29*C 0.84
2.3 X 10 J at WC 0.8!
3.9 X 10* at 20*C 0.94
0.80
o.eo
1.37
1.36
4.7 X 10J « 2l'C 1.2
2.3 X 101 at JS'C 1.18
1.36
1.11
1.2 X 104 at 2O*C 0.80S4
1.33
o.w^
0.83
Toxictty
Oral LD Vapor LC
Solubility (Hat)5 (lutl 50
in Mater IqAq) « hr at a/Cat1
Infinite
Infinite
Z8« 0.046 a
Infinite O.O64 16S
0.3t
lit 6.48
2T*
11*
13%
4« 0.140 1000
6» 0.1—0.2
Infinite 27. S
Infinite
Very soluble 3.4
Very aoluble
0.085*
2S%
Zxtree«ly fltxeuela
Irritating, toxic, flaxeuble
at high concentration
Highly toxic, very reactive.
lacrlaatat, highly llaaxufta*
Highly toxic, lacrlMtor,
reactlv*, contact poiaon.
flaavable
Toxic, irritating vapor a, con-
tact poiton, highly flaxcublei
Toxic, flaavabla
Highly flaavuble
Toxic, vapora irritating and
toxic, contact poiaon
Toxic, vapor* Irritating and
toxic, contact poiaon
Highly toxic, pungent garlic
odor
Toxic, vapor* irritating and
toxic, contact poiaon.
aenaititer
Toxic, reactive >
1
•aactivt, flawabl., can
axjloda if aeated or
contaminated
flueiable gaa
•aactlve, ajrueealy flacaubla
I of concentration eer 6g arf air.
it -47'c.
-------
A-2
Sources for Data Given in Table A-l;
1- Handbook of Chemistry and Physics. 45th ed., pp. C75—C601, edited by R. C.
Weast e_t al., The Chemical Rubber Co., Cleveland, Ohio, 1964.
2. Handbook of Chemistry, 9th ed., pp. 384—721, edited by N. A. Lange e_t al.,
Handbook Publishers, Inc., Sandusky, Ohio, 1956.
3. Chemical Safety Data Sheet SD-99, Allyl Chloride, Manufacturing Chemists Association,
Washington, D.C., 1973.
4. Epichlorohydrin—The Versatile Intermediate, Product Bulletin, Dow Chemical
- Co., Freeport, TX, 1975.
5. Physical Properties of Glycerine and Its Solutions, Product Bulletin, Dow Chemical
Co., Freeport, TX (nd).
6. J. Dorigan, B. Frieler, and R. Duffy, "Methyl Ethyl Ketone," pp AIII-192,
193 in Scoring of Organic Air Pollutants, Chemistry, Production and Toxicity
of Selected Synthetic Organic Chemicals (Chemicals F-N, MTR-7248, Rev. 1,
App. Ill (September 1976).
7. Acetaldehyde; Acrolein; Allyl Alcohol; s-Butyl Alcohol/2-Butanol; Dichloropropenej:
Dichloropropane, DP; Glycerine/Glycerol, Material Safety Data Sheets, Shell
Chemical Co., Norco, LA (nd).
-------
B-l
A. EXISTING PLANT CHARACTERIZATION
Information has been received regarding control devices or techniques from the
following three manufacturers, covering three processes for the manufacture of
intermediates and two processes for conversion of intermediates to synthetic
glycerin:
1. The Chlorination Process
a. The Dow Chemical Co., Freeport, TX, has a nominal capacity for 113.4 Gg/yr
of crude epichlorohydrin and a nominal capacity of 54.4 Gg/yr of synthetic
glycerin. The information available on this plant is summarized in
Table B-l.1
b. The Shell Chemical Co. has a nominal capacity of 49.9 Gg/yr of crude
epichlorohydrin at each of two plants, Deer Park, TX, and Norco, LA. The
combined nominal capacity of both plants for the manufacture of synthetic
glycerin was stated to be 45.4 Gg/yr (including the capacity to manufac-
ture glycerin via the acrolein route).2 The information available on
these plants is summarized in Table B-l.
2. The Oxidation Process
a. The Shell Chemical Co. has a nominal capacity of 24.9 Gg/yr of acrolein at
the Norco, LA plant.3 Total capacity for manufacture of synthetic glycerin
is 45.4 Gg/yr, as stated in item l.b.
b. The Union Carbide Corporation has a nominal capacity of 27.2 Gg/yr of
acrolein at the Taft, LA, plant, with no capacity for conversion of acrolein
to glycerin.4 The information available on this plant is summarized in
Table B-l.
B. RETROFITTING CONTROLS
The control devices and techniques discussed in Section V may not be applicable
to existing plants. Retrofitting control devices or techniques into existing
plants brings up such questions as: Is there space in the existing plant to
fit in and install the new hardware required? Do the operating characteristics
of the emission control device fit the operating characteristics of the process
equipment? Are the operating characteristics and design limitations of the
-------
B-2
Table B-l. Control Devices and Techniques Currently
Used in Synthesis of Glycerin and/or Intermediates
Process Process Steo
Chlorination Allyl chloride
•
Epichlorohydrin
Glycerin
h
Oxidation Acrolein
Allyl alcohol
Glycerin
Oxidation Acrolein
process ,
variation
*See Fig^i. V-l.A — e.
b5ee Fig. v-2.
Source
HC1 absorber vent
Light-ends distillation
column vent
Allyl chloride dist.
column vent
Dichloropropene dist.
column vent
Epoxidation reactor
vent
Azeotrope column vent
Lights stripping column
vent
Finishing column vent
Carbon dioxide absorber
vent
Evaporator vent
Concentrator vent
Stripping column vent
Light- ends column vent
Solvent stripping column
vent
Product column vent
Cooling tower
Carbon dioxide stripping
tower vent
Aqueous acrolein
receiver vent
Distillation system
receiver vent
Catalyst preparation vent
Filtration system vent
Lights stripper column
vent
Distillation system
vents (3)
Light-ends stripper vent
Concentrator column vent
Glycerin flasher
column vent
Product column vent
Furnace vent
Acrolein absorber vent
Combined dist. system
vent header
Stream
Designation
Al
A2
A3
A4
B
B2
B3
B4
cl
C2
C3
C4
C5
C6
C_
7
K15
Al
A2
£.
"5
J
B
B2
B3
B.
4
B_
5
B,
6
Cl
C2
C
C4
°5
1
2a-e
Control
By
Dow
Flare
Flare
Flare
NR (not
reported)
Thermal
oxidizer
Thermal
oxidizer
None
None
None
None
None
None
None
None
None
None
Device or Technology
By
Shell
Flare
Vent
condenser
None
Scrubber
Use of NaOK
Ca(OH)2
Scrubber
Scrubber
Scrubber
NR
NR
NR
NR
NR
NR
NR
NR
Flare
Flare
Flare
Vent
condenser
Scrubber
Flare
Nonec
Vent
condenser
Vent
condenser
Scrubber
None
Vent
condenser
None
None
By
Onion
Carbide
or
Thermal
oxidizer
Flare
Process condenser keeps emissions low.
No figure available.
-------
B-3
control device compatible with the upset or emergency conditions that might
be encountered with the process? Are the startup and shutdown characteristics
of the control device compatible with the startup and shutdown requirements of the
process? Are extensive process modifications needed to accomplish significant
emission reductions? When changes in feedstock or intermediates are needed to
reduce process emissions, are the changed feedstocks or intermediates readily
available at reasonable prices?
The specific plants investigated for this report seem to have most of their emission
sources fairly well controlled by either specific control devices or operating
techniques. No specific recommendations for retrofitting additional controls
or techniques are provided in this report.
-------
B-4
C. REFERENCES*
1. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Dow
Chemical Co. Process at Freeport, TX, Jan. 26 and 27, 1978 (on file at EPA, ESED,
Research Triangle Park, NC).
2. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Deer Park, TX, Jan. 25, 1978 (on file at EPA, ESED,
Research Triangle Park, NC).
3. C. A. Peterson, IT Enviroscience, Inc., Trip Report Covering Discussion of Shell
Chemical Co. Process at Norco, LA, Jan. 25, 1978 (on file at EPA, ESED, Research
Traingle Park, NC).
4. F. D. Best, Union Carbide Corp., Taft, LA, Letter to EPA, Apr. 21, 1978,
in response to EPA request for information on the Union Carbide acrolein
process.
*When a reference number is used at the end of a paragraph or on a heading, it
usually refers to the entire paragraph or material under the heading. When,
however, an additional reference is required for only a certain portion of the
paragraph or captioned material, the earlier reference number may not apply to
that particular portion.
-------
4-i
REPORT 4
ACRYLIC ACID AND ESTERS
J. W. Blackburn
IT Enviroscience
9041 Executive Park Drive
Knoxville, Tennessee 37923
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
December 1980
This report contains certain information which has been extracted from the
Chemical Economics Handbook/ Stanford Research Institute. Wherever used, it
has been so noted. The proprietary data rights which reside with Stanford
Research Institute must be recognized with any use of this material.
-------
4-iii
CONTENTS FOR REPORT 4
Page
I. ABBREVIATIONS AND CONVERSION FACTORS 1-1
II. INDUSTRY DESCRIPTION H-l
A. Organic Compounds Produced II-1
B. Usage and Growth of Acrylic Acid & Esters II-2
C. References II-6
III. PROCESS DESCRIPTIONS III-l
A. Acrylic Acid Production III-l
B. Lower-Acrylic-Ester Production III-9
C. Heavy-Ester Production 111-14
D. References 111-18
IV. EMISSIONS IV-1
A. Integrated Model Plant IV-1
B. Sources and Emissions IV-7
C. References IV-25
V. APPLICABLE CONTROL SYSTEMS V-l
A. Acrylic Acid from Propylene and Esters by Direct V-l
Esterification - Integrated Plant
B. Acrylic Acid by High-Pressure Modified Reppe Process V-7
C. References V-8
VI. IMPACT ANALYSIS VI-1
A. Control Cost Impact VI-1
B. Environmental and Energy Impacts VI-8
C. References VI-10
VII. SUMMARY VII-1
APPENDICES OF REPORT 4
A. PHYSICAL PROPERTIES OF ACRYLIC ACID, ETHYL ACRYLATE, BUTYL A-l
ACRYLATE, 2-ETHYLHEXYL ACRYLATE, ETHANOL, n-BUTANOL, AND
2-ETHYLHEXANOL
B. AIR-DISPERSION PARAMETERS B-l
C. FUGITIVE EMISSION FACTORS C-l
D. COST ESTIMATE SAMPLE CALCULATIONS D-l
E. EXISTING PLANT CONSIDERATIONS E-l
-------
4-v
TABLES FOR REPORT 4
Number
II-l Acrylic Acid and Esters Usage auu Growth II-3
H-2 Acrylic Acid and Ester Capacity II-3
IV-l Acrylic Acid and Esters Model-Plant Storage Requirements IV-4
IV-2 Composition of Acrylic Acid Quench—Absorber Off-Gas IV-9
in Model Plant
IV-3 Composition of Combined Waste Gas from Vents from IV-9
Acrylic Acid Atmospheric Pressure Equipment in Model Plant
IV-4 Composition of Waste Gases from Extraction and Refining IV-11
Vacuum Vents in Acrylic Acid and Esters Model Plant
IV-5 Total VOC Uncontrolled Fugitive Emissions in Acrylic IV-12
Acid and Esters Model Plant
IV-6 Total VOC Uncontrolled Storage Emissions for Fixed-Roof Tanks IV-14
IV-7 Total VOC Uncontrolled Handling Emissions in Acrylic IV-15
Acid and Esters Model Plant
IV-8 Total VOC Uncontrolled Secondary Emissions in Acrylic IV-15
Acid and Esters Model Plant
IV-9 Composition of Waste Gases from Vents from Ethyl Acrylate IV-17
Atmospheric Equipment in Model Plant
IV-10 Composition of Waste Gases from Vents from Ethyl Acrylate IV-17
Vacuum Equipment in Model Plant
IV-11 Composition of Combined Waste Gas from All Butyl Acrylate IV-20
Equipment in Acrylic Acid and Esters Model Plant
IV-12 Composition of Waste Gases from Vents from 2-EHA Atmospheric IV-22
Equipment in Acrylic Acid and Esters Model Plant
IV-13 Composition of Waste Gases from Vents from 2-EHA Vacuum IV-22
Equipment in Acrylic Acid and Esters Model Plant
IV-14 Total Uncontrolled VOC Emissions from Acrylic Acid IV-24
and Esters Integrated Model Plant
V-l Total VOC Controlled Emissions for Integrated Acrylic V-5
Acid and Ester Model Plant Acrylic Acid by Propylene
Oxidation, Esters by Direct Esterification
VI-1 Annual Cost Parameters VI-2
VI-2 Emission Control Cost Estimates and Cost Effectiveness VI-7
for Integrated Acrylic Acid and Ester Model Plant
A-l Physical Properties of Acrylic Acid, Ethyl Acrylate,
Butyl Acrylate, 2-Ethylhexyl Acrylate, Ethanol, A-l
n-Butanol, and 2-Ethylhexanol
-------
4-vii
TABLES (continued)
Number Page
B-l Air-Dispersion Parameters B_l
E-l Control Devices Currently Used by the Domestic E-2
Acrylic Acid and Esters Industry
E-2 Control Devices - Product Handling E--3
E-3 Emission Data from Rohm and Haas E-13
E-4 Acrylic Acid/Acrylate Ester Emission Factors E-14
E-5 Composition of Other Waste-Gas Streams E-15
E-6 Composition of Incinerator Flue Gas E-16
-------
4-ix
FIGURES FOR REPORT 4
Number
II-l Locations of Plants Manufacturing Acrylic Acid and Esters II-4
III-l Manufacture of Acrylic Acid from Propylene III-2
III-2 Manufacture of Lower Acrylic Acid Esters by Direct 111-10
Esterification
III-3 Manufacture of Heavy Acrylic Acid Esters by Direct 111-15
Esterification
IV-1 Model Plant for Manufacture of Acrylic Acid and IV-3
Acrylic Acid Esters by Propylene Oxide
V-l Liquid-Fume Thermal Oxidizer for Acrylic Acid and V-2
Ester Model Plants
VI-l Installed Capital Cost vs. Plant Capacity for VI-4
Integrated Model Plant Emission Controls
VI-2 Net Annual Cost vs. Plant Capacity - Liquid-Fume VI-5
Thermal Oxidation
VI-3 Cost Effectiveness vs. Plant Capacity for Integrated VI-6
Model Plant Emission Control
D-l Precision of Capital Cost Estimates D-3-
-------
1-1
ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements used in agency documents in metric
units. Listed below are the International System of Units (SI) abbreviations
and conversion factors for this report.
To Convert From
Pascal (Pa)
Joule (J)
Degree Celsius (°C)
Meter (m)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter/second
(ms/s)
Watt (W)
Meter (m)
Pascal (Pa)
Kilogram (kg)
Joule (J)
To
Atmosphere (760 mm Hg)
British thermal unit (Btu)
Degree Fahrenheit (°F)
Feet (ft)
Cubic feet (ft3)
Barrel (oil) (bbl)
Gallon (U.S. liquid) (gal)
Gallon (U.S. liquid)/min
(gpm)
Horsepower (electric) (hp)
Inch (in.)
Pound-force/inch2 (psi)
Pound-mass (lb)
Watt-hour (Wh)
Multiply By
9.870 X 10"6
9.480 X 10~4
(°C X 9/5) + 32
3.28
3.531 X 101
6.290
2.643 X 102
1.585 X 104
1.340 X 10~3
3.937 X 101
1.450 X 10"4
2.205
2.778 X 10"4
Standard Conditions
68°F = 20°C
1 atmosphere = 101,325 Pascals
PREFIXES
Prefix
T
G
M
k
m
M
Symbol
tera
giga
mega
kilo
milli
micro
Multiplication
Factor
1012
109
106
103
10"3
10"6
Example
1 Tg =
1 Gg =
1 Mg =
1 km =
1 mV =
1 ug =
1 X 10 12 grams
1 X 109 grams
1 X 106 grams
1 X 103 meters
1 X 10"3 volt
1 X 10"6 gram
-------
II-l
II. INDUSTRY DESCRIPTION
Acrylic acids and esters include three major categories of chemicals: acrylic
acid, lower esters (methyl, ethyl, and butyl), and heavy esters (2-ethylhexyl
and others). There are several processes for each of these categories. This
report is organized so that the products in each category is considered a prod-
uct in itself. However, the materials are produced at an integrated plant and
may share common storage tank equipment and/or control devices. A model plant
utilized to project organic emissions is based on an integrated acrylates
production facility.
A. ORGANIC COMPOUNDS PRODUCED
1. Acrylic Acid (AA)
Acrylic acid production was selected for in-depth study because preliminary
estimates indicated that total emissions of volatile organic compounds (VOC),
excluding methane, are relatively high and that the product growth rate is
expected to be higher than the industry average.
Acrylic acid is a colorless liquid at ambient conditions (see Appendix A for
pertinent physical properties). Compounds that are reported as organic emis-
sions in relation to AA production are formaldehyde, formic acid, ethylene,
acetaldehyde, acetic acid, propane, propylene, acetone, propionaldehyde, acro-
lein, ethyl acrylate, and others. Since a variety of solvents may be used
in AA production, there may be additions or exceptions to these organic com-
pounds, depending on the manufacturer's specific process.
2. Lower Esters
Methyl, ethyl, and butyl acrylates (MA, EA, and BA) were selected because
preliminary estimates indicated that total emissions of VOC are relatively
high, that the product growth is expected to be higher than the industry aver-
age, and that the production of acrylate esters is closely tied to acrylic acid
production.
MA, EA, and BA are colorless liquids possessing unusually potent odor prop-
erties. This has required producers to implement control devices to achieve
-------
II-2
emission reductions greater than usual for the synthetic organic chemicals
industry.
3. Heavy Esters
A number of esters have molecular weights that are higher than those of MA, EA,
and BA. They are called heavy esters and include 2-ethylhexyl acrylate (2-EHA)
among others. Some producers consider BA a heavy ester. The heavy esters are
normally liquids at ambient conditions (see Appendix A for pertinent physical
properties). Compounds emitted from heavy-ester production include AA, MA, EA,
and BA and its corresponding heavy alcohol, e.g., 2-ethylhexyl alcohol in the
production of 2-EHA.
B. USAGE AND GROWTH OF ACRYLIC ACID AND ESTERS
Table II-l shows the end uses and growth of acrylic acid and esters. The
predominant end use is the manufacture of polymers for use in surface coatings,
4
textiles, paper, polishes, leather, and other materials. Small amounts of AA
are used in the production of water-soluble resins and as a co-monomer for
other polymers. A small amount of esters is used in the manufacture of acrylic
fibers.4
The U.S. AA and ester capacity for 1976 was reported to be 618 Gg of total
acrylate (including a recent major expansion). No data are available on the
breakdown of the capacity of acrylate esters. About 66% of the 618 Gg of
domestic capacity uses catalytic oxidation technology to oxidize propylene to
acrylic acid. The remainder uses both a high- and a low-pressure modified
4
Reppe process, starting with acetylene, for acrylic acid manufacture. Recent
announcements confirm a new propylene oxidation plant to be built in 1981 with
an acrylic acid capacity of 59 Gg/yr.5
As of 1976 there were four U.S. producers of acrylic acid and esters. Table II-2
gives the producers and the processes used for the plant locations, shown in
Fig. II-l. Most production facilities react acrylic acid with alcohol to form
the lower and heavy esters at the same site at which the acrylic acid is pro-
duced. An exception to this is the Celanese Chemical Co., which transports
about 12 Gg per year of AA from its Clear Lake, TX, plant to its Pampa, TX,
4
plant, where the lower and heavy esters are made. Another is the old Rohm
-------
II-3
Table II-l. Acrylic Acid and Esters Usage and Growth*
End Use
Percent of Production
(1976)
Average Annual
Percent Growth
(1974-1980)
Acrylic acid
Esters
Other
Overall
Acrylates
Emulsion polymers
Other
Overall
86
14
75
25
10 - 12
7
9.5 - 11.3
6.8 - 8.2
8.7
7.1 - 8.4
*See ref 4.
Table II-2. Acrylic Acid and Ester Capacity2
Producer
Celanese Chemical Company
Clear Lake, TX
Pampa, TX
Dow Badische Co.
Freeport , TX
Hohm and Haas Co.
Deer Park, TX
Union Carbide Corp.
Taft, LA
Total
1976 Capacity13
(Gg/yr)
138.5
Included above
25. 9e
181.6
181.6
90.8
618.4
Process
Acrylic Acid
c
None
f
None
c
c
Esters
d
d
g
h
g
g
See ref 4.
bBased on total aerylates, i.e., acrylic acid plus esters.
°Propylene oxidation to acrylic acid.
^Unknown confidential processing.
e!981 expansion to 59 Gg/yr based on propylene oxidation to acrylic acid.
fHigh-pressure modified Reppe process for acrylic acid.
^Direct esterfication.
hLow-pressure modified Reppe process being phased out. Transesterification
is used for higher esters.
-------
II-4
1. Celanese, Clear Lake, TX
2. Celanese, Pampa, TX
3. Dow Badische, Freeport, TX
4. Rohm and Haas, Deer Park, TX
5. Union Carbide, Taft, LA
Fig. II-l. Locations of Plants Manufacturing Acrylic Acid and Esters
-------
II-5
and Haas low-pressure modified Reppe process plant, which produces the lower
esters directly and the heavy esters by transesterification.
The overall annual growth for AA for the period between 1976 and 1982 is expected
to be 8%; an annual growth for the propylene oxidation process for AA is as-
sumed to be 15% and a -4% growth is assumed for the high-pressure modified
Reppe process. Production of acrylic acid in 1974 and 1975 (including that
used in ester manufacture) was 109 Gg and 95 Gg, respectively. Total ester
production for these two years was 243 Gg and 209 Gg, respectively.
-------
II-6
C. REFERENCES*
1. R. W. Serth, D. R. Tierney, and T. W. Hughes, Source Assessment: Acrylic
Acid Manufacture State-of-the-Art (on file at IERL, EPA, Cincinnati, OH).
2. Nonconfidential information received May 1978 from Celanese Chemical Co.,
Houston, TX (on file at EPA, ESED, Research Triangle Park, NC).
3. J. W. Blackburn, IT Enviroscience, Trip Report on Site Visit to Union Carbide
Corp., South Charleston, WV, Dec. 8, 1977 (on file at EPA, ESED, Research
Triangle Park, NC).
4. J. L. Blackford, "CEH Marketing Research Report on Acrylic Acid and Esters,"
pp. 606.4031A-E, 606.4032A-Z, and 606.4033A-J in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park, CA (August 1976).
5. "Dow Badische Expands," Chemical Week 122(18), 17 (1978).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on a heading, it refers to all the text covered by that
heading.
-------
III-l
III. PROCESS DESCRIPTIONS
A. ACRYLIC ACID PRODUCTION
1. Introduction
Three processes are currently used to manufacture AA. The first, propylene
oxidation, represents 66% of the present U.S. capacity for AA. The remaining
34% represents the high- and low-pressure modified Reppe processes (181.6 Gg/yr
of this modified Reppe process is catagorized as idle capacity and is being
phased out with the addition of a new propylene oxidation plant of equal capac-
ity) . Not including the low pressure modified Reppe plant being phased out,
94% of U.S. AA capacity uses propylene oxidation technology, and 6% uses the
high-pressure modified Reppe process.
2. Propylene Oxidation Process
a. Basic Process — AA is produced by the following chemical reactions: '
(1) CH2=CH-CH3 + 02 ^ CH2=CH-CHO + H^
(Propylene) (Oxygen) (Acrolein) (Water)
(2) CH2=CH-CHO + 1/2 02 > CH2=CH-C
OH
(Acrolein) (Oxygen) (Acrylic acid)
The process flow diagram shown in Fig. III-l represents a typical process using
two-stage propylene oxidation for AA production. Single-stage oxidation is
feasible but is not as economical as a two-stage process.
Catalysts used in the oxidation of propylene to acrylic acid are the focus of
considerable patent activity. They vary in composition and may include molyb-
denum, cobalt, iron, bismuth, tin, tungsten, tellurium, sodium, and other
metallic elements. These proprietary mixtures are in the form of pellets or
2,3
are fixed on inert supports.
-------
VACUUM
SYSTEM
- PU&IT1VE EMISSlOkJ^ FROM PUMPi
RELIEF VALVe-b, AX1D PROCESS
PROPVUEVJE
___^w—•
BT PiPELrt-JE
Fig. III-l. Manufacture of Acrylic Acid from Propylene
-------
IE
«N
VACUUM
SYSTEM
r8
ACET\C ACID
A^>
OP. RE^?CLE TO<^>
VACUUM
r-HjZj—i
/.
ACRVUC ACID
DI5TIU.KTIOJ
^
ACID
STORAGE
ACRYUC ACID
TA>JK FARM
TRUCK -RMI_
LOADIIOG,
ACRVUIC AOD TO
LOWER- AUD MEH.VY-
E5TER PRODUCTiOU
- DEMOTE.^ VKCUUM 6OUIPM£VJT
)- FUGITIVE EMISSIOU^> FROM PUMPS
REUEF VA\_VE*>, A>JD PROCE.S'b
Fig. III-l. (Continued)
-------
III-4
The major differences in catalyst performance are reactor temperatures and
pressures, contact times, air-to-propylene and steam-to-propylene molar feed
ratios, conversions, and selectivities. Patent literature indicates that
reactor temperatures vary from 130 to 480°C in systems designed for acrylic
acid production by propylene oxidation; pressures vary from 5.1 to 1210 kPa,-
and contact times range from 0.001 to 46 sec. Air-to-propylene molar feed
ratios range from 0.07 to 66.7 and steam-to-propylene molar feed ratios from
0 to 50. Conversion of propylene ranges from 12.1 to 100 mole %. Wide vari-
ations in selectivity are reported.
In Fig. III-l propylene (Stream 1), air (Stream 2), and steam (Stream 3) are
fed to the oxidation reactors in proportions within the ranges discussed above.
The steam helps control the reaction temperature, conversions, and selectivities.
Since the reactions are exothermic, reactor heat-removal systems are required
to maintain the appropriate temperatures and pressures. The gaseous effluent
from the second reactor (Stream 4) is sent to a quench-absorber, where it is
rapidly quenched with water (Stream 5) to remove the organic water-soluble
compounds (Stream 7). The water stream fed to the quench-absorber includes
some aqueous effluent (Stream 14) generated later in the process and fresh
water makeup (Stream 6). The gas stream leaving the absorber (Stream 1A) is a
major process emission.
The aqueous stream containing the water-soluble organics (Stream 7) is ex-
tracted with a solvent. Many solvents can be used to extract acrylic acid from
2
water, but the specific ones used are considered to be proprietary by most
acrylic acid producers. The extraction column is a source of organic emissions
(Stream IB).
The aqueous stream leaving the extraction column is combined with other aqueous
streams from decanters (Stream 19) and is distilled to remove the solvent from
the water. Some of this stripped raffinate is sent to the quench-absorber
(Stream 14), and the remainder is sent to wastewater treatment (Stream IK).
This aqueous waste will contain water-soluble organic by-products of the propy-
lene oxidation reaction: acetaldehyde, acetic acid, maleic acid, phthalic
acid, formic acid, formaldehyde, propionic acid, propionaldehyde, acetone,
2
allyl alcohol, and others and is a source of a secondary emission. The vent
from the raffinate stripper contains organic emissions (Stream 1C).
-------
III-5
The extract stream (Stream 8) is distilled under vacuum to recover the solvent
from the crude acrylic acid (Stream 20). The solvents may carry water over-
head, requiring a decanter to separate the solvent (Stream 18) phase from the
aqueous (Stream 19). The solvent (Stream 18) not used as column reflux
(Stream 15) is combined with fresh solvent (Stream 16) and solvent from the
raffinate stripper (Stream 11) and recycled to the extraction column
(Stream 10). The vapors drawn from the extract distillation equipment by
vacuum equipment (Stream 17) are ducted to a condenser and recovered. Uncon-
densed vapors are emitted (Stream ID). Nitrogen is bled into the vacuum distilla-
tion equipment to maintain the vacuum and avoid further oxidation of acrylic
4
acid.
Crude acrylic acid (Stream 20) is sent to another vacuum distillation system —
the foreruns distillation -- where compounds more volatile than acrylic acid
are removed. The foreruns distillation effluent (Stream 22) is largely acetic
acid and can be further purified to produce glacial acetic acid as a by- prod-
uct. Most manufacturers return this stream to the extraction column feed
(Stream 7), and the acetic acid ultimately leaves the system in the stripped
raffinate wastewater. The vapors (Stream 21) drawn from the foreruns distil-
lation are ducted to a condenser. Uncondensed vapors are emitted (Stream IE).
The acrylic acid (Stream 23) is then combined with the acrylic acid from a
residue distillation (Stream 27) and is fed (Stream 24) to a vacuum distilla-
tion unit, where acrylic acid is taken overhead (Stream 29). Vapors drawn from
this equipment (Stream 28) are ducted to a condenser. Uncondensed vapors are
emitted (Stream 1G).
Bottoms from the acrylic acid distillation (Stream 25) are distilled in residue
distillation equipment, and the acrylic acid removed (Stream 27) is recycled to
the acrylic acid distillation. Emissions from this vacuum equipment are shown
as Stream IF in Fig. III-l. The residues (Stream IK) are either liquid or
solid organic wastes for disposal or by-products to be used in other acrylic
processes.
Acrylic acid (Stream 29) is stored in temporary storage or "working storage"
and then either sent to lower- and heavy-ester production or prepared for
-------
III-6
shipment by barge, truck, rail, or drum. All working tanks are shown as a
single tank on Fig. III-l. Storage emissions are labeled Stream 1H, and emis-
sions relating to packaging or shipping acrylic acid are labeled 1J.
Because of buildup of solid polymerization products of acrylic acid and aery-
lates, acrylic acid plants must be shut down for cleaning and maintenance from
4
four to twelve times a year. These polymers have to be manually removed.
Although care is taken to avoid their formation, as much as 8 m /yr or about
1200 kg/yr, of organic solids can be generated. The material is disposed of by
4,5 , ,...,.,6
incineration or landfill.
When equipment is shut down for cleaning, care is taken not to produce organic
emissions. After the organics have been removed, nitrogen is introduced into
the equipment to prevent entrance of air. Upon startup the equipment is filled
with process fluids and/or placed under vacuum,- the nitrogen displaced contains
little organic.
Fugitive losses (labeled II on Fig. III-l) can occur at valves and seals and
may contain propylene, acrylic acid, acrolein, solvent, and other organics.
Much of the process shown in Fig. III-l is under vacuum, and so the tendency is
for air to leak into the equipment rather than for organics to leak out of the
equipment. However, situations can exist where, because of the static liquid
head, the localized pressures generated can be greater than atmospheric. In
these cases it is possible for fugitive leaks to occur from equipment main-
tained under vacuum.
Storage emission sources (labeled 1H on Fig. III-l) are related to acrylic acid
and solvent storage. Both working and tank farm storages are shown.
Handling emissions (labeled 1J on Fig. III-l) arise from loading of acrylic
acid into drums, tank trucks, tank cars, or barges.
b. Process Variations -- Manufacturers of acrylic acid use a number of variations
of the process. Because the manufacture of acrylic acid is highly competitive
and the propylene oxidation process is relatively new, many producers consider
the specific details of the reaction catalysts, conditions, raw material
-------
III-7
ratios, etc., as confidential. This is also true of the design of the quench-
absorber since knowledge of the details of flow, composition, and conditions of
the entering and exiting streams can reveal details of the oxidation reactor.
Operating conditions and stream compositions and flow can vary widely, as has
been shown.
The step of extraction of acrylic acid from the aqueous quench-absorber efflu-
ent also varies widely. Many different solvents — with different molecular
weights, vapor pressures, aqueous solubilities, and distribution coefficients
2
—may be used. This is also a sensitive area from the manufacturer's view-
point. The ratio of solvent to feed varies with the solvent used, and the
extract distillation equipment must be designed with consideration of this
ratio and other factors, such as the physical properties of the chemicals. The
raffinate stripper design depends on the volume of water in the system (which
in turn depends on the amount of steam fed, the amount of water produced in the
reaction, and the amount of makeup water added) and on the aqueous solubility
of the solvent selected for use.
The design of the foreruns distillation depends on whether the manufacturer
intends to recover acetic acid (a major impurity) or to waste the foreruns in
the stripped raffinate. In a plant producing acetic acid additional equipment
may be used to purify the acetic acid or to remove other specific impurities
from the acrylic acid.
The acrylic acid distillation may consist of several pieces of distillation
equipment, generating acrylic acid of various purities. Residue distillation
is designed for the type and efficiency of polymerization inhibitor used and
the amounts of other impurities of low volatility.
In general the distillation equipment following the extraction may be highly
individualized in design. Although several stills may be used, only one is
shown in Fig. III-l.
Storage practices for acrylic acid depend on whether all acrylic acid is used
captively for ester production at a plant or whether some acrylic acid is sold
to outside consumers or transferred to different plant locations. Acrylic acid
storage requires special precautions to prevent further acrylic acid oxidation
-------
III-8
or polymerization. A variety of residual inhibitors and nitrogen blankets may
1 4
be used to minimize oxidation or polymerization of acrylic acid being stored. '
Freezing of the acrylic acid in storage must also be avoided since freezing may
cause the inhibitors to separate from the bulk of the acrylic acid.
3. Modified Reppe Processes
Rohm and Haas currently uses the low-pressure modified Reppe process, only to
meet peak product demand. This process does not produce acrylic acid since it
makes the lower esters directly. Rohm and Haas (Deer Park, TX) is phasing out
production of lower esters by this route and has recently (1977) introduced a
new propylene oxidation process.
The Dow Badische plant uses the high-pressure modified Reppe process and has a
capacity of 6% of total domestic acrylate (excluding the old Rohm and Haas
low-pressure modified Reppe process).
The high-pressure modified Reppe process is significantly different from the
low-pressure process. Since the high-pressure process is used for only a
small percentage of today's acrylate capacity and since it is expected to be
il<
9
Q
phased out when a proposed propylene oxidation plant is built in 1981, those
interested in it are referred to the literature.
4. Other Processes
Acrylic acid can also be produced by hydrolysis of acrylonitrile. This process
is unattractive because of higher capital costs and the generation of large
amounts of sulfuric acid--ammonium sulfate wastes. Acrylic acid can be produced
by pyrolysis of acetic acid or acetone to ketene, and then conversion of the
ketene to (J-propiolactone. Because p-propiolactone is a suspected carcinogen,
this reaction is not recommended. Acrylic acid can also be manufactured from
ethylene cyanohydrin. Although this was the first process commercially used
for acrylic acid production, yields are low and larger amounts of sulfuric
acid—ammonium sulfate wastes are generated.
Although there are other possible processes for acrylic acid manufacture, none
are currently used in the U.S. '
-------
III-9
B. LOWER-ACRYLIC-ESTER PRODUCTION
1. Introduction
Lower esters — methyl and ethyl acrylate — are normally produced by direct
esterification of acrylic acid with methanol or ethanol or by other, undis-
closed, processes. Low-pressure modified Reppe plants produce the lower acry-
lates without isolating acrylic acid.
2. Direct Esterification
a. Basic Process -- Methyl and ethyl acrylates are produced from acrylic acid and
methanol or ethanol by the reaction
yO X0
CH =CH-C/ + CH OH or C H-OH > CH =CH-C^ + H,0
£ \)H * £ * 2 VcH3 2
(Acrylic Acid) (Methanol) (Ethanol) (Methyl Acrylate)
or
CH2=CH-
^CH
uu_n.
'25
(Ethyl Acrylate)
This reaction involves an equilibrium relationship; a strong acid, such as
sulfuric, is often used to catalyze the forward reaction.
The process flow diagram shown in Fig. III-2 represents a typical process using
direct esterification to manufacture lower esters. Acrylic acid (Stream 1),
methyl or ethyl alcohol (Stream 2), and sulfuric acid (Stream 3) are fed to an
esterification reactor equipped for reflux distillation. Vapors leaving the
reflux distillation are condensed and form a two-phase mixture (Stream 5 and 6)
of acrylate ester, water, alcohol, and traces of acrylic acid. Organic emis-
sions can occur (Stream 3A). The aqueous layer (Stream 6) is combined with
other aqueous streams and sent to an alcohol recovery distillation (Stream 11).
Noncondensables from this equipment are organic emissions (Stream 3B). Bottoms
from the esterification reactor (Stream 8) are distilled in a bottoms stripper
-------
REACTOR
BOTTOMS
STRIPPER
ALCOHOL
REFLUX
EXTRVCTIOU
- FU&mVE EMISSIONS FROM PUMPS,
VALVES, AUD PROCESS VALVES
Fig. III-2. Manufacture of Lower Acrylic Acid Esters by Direct Esterification
-------
D&HYDRATKXJ
.<~VN
AQUEOUS
TO
RESIDUE
A
1
ESTER
WORKIKJ&
STORAGE.
TRUCK-
RAIU
M
I
/- DEMOTED VACUUM tQUIPMEUT
(31) - FUGITIVE EMISSIONS FROM PUMP<>
REUEF VA.V.VES. WJO PROCESS
Fig. IH-2. (Continued)
-------
111-12
distillation and the organic-rich overhead (Stream 9) is returned to the reac-
tor with other alcohol-containing distillates (Stream 13). Organic emissions
from uncondensed vapors in this distillation are labeled (Stream 3C).
The organic phase from the reflux distillation column (Stream 5) is extracted
with water or another extractant (Stream 10) capable of removing the alcohol
from the feed (Stream 5). The aqueous effluent from the extractor is combined
with other alcohol-containing aqueous streams and sent to the alcohol recovery
distillation (Stream 11).
The organic phase leaving the extractor (Stream 12) is sent to an ester dehydra-
tion distillation, where dissolved water is removed. The aqueous phase from
the associated decanter (Stream 14) is routed to the alcohol recovery distil-
lation along with other alcohol-containing aqueous streams.
The dehydrated ester (Stream 15) is refined by distillation and stored for
shipping (Stream 18). Residues from the refining distillation (Stream 16) are
distilled to recover ester and then incinerated (Stream 3K). Overheads from
this distillation are returned to the ester-refining column (Stream 17).
Lower-ester plants require shutdown and cleaning because of the tendency of the
esters to polymerize and because of a change of the ester being produced. This
has been estimated by one manufacturer to be from 12 to 24 times a year.
Nitrogen blankets are used to prevent air from entering the equipment, and
organics are removed as liquids. In these plants shutdown is usually performed
4
in preparation for idle standby rather than because of operational problems.
Fugitive losses (Stream 31) can occur at valves and seals and may consist of
methyl or ethyl alcohol, acrylic acid, methyl or ethyl acrylate, and other
organics. Some of the equipment shown in Fig. III-2 is under vacuum and should,
in general, have fewer fugitive emissions than atmospheric equipment. It is
still possible that some emissions can occur if the static pressure at any
point exceeds atmospheric pressure. Pumps, for instance, either receiving or
pumping against a high liquid head could be operating at pressures greater than
atmospheric and therefore Lave fugitive emissions.
-------
111-13
Storage emission sources (Stream 3H) are acrylic acid, methyl and/or ethyl
alcohol, and product methyl aerylate and/or ethyl aerylate working and tank
farm storage units. Sulfuric acid storage and water storage will create no
organic emissions. If the extractant (Stream 10) for the organic phase from
the reflux distillation column is organic, it will require storage and will
result in an organic emission.
Handling emissions (Stream 3J) will occur from loading the acrylate esters in
drums, tank cars, tank trucks, and barges.
k. Process Variations — Other acid catalysts, e.g., sulfonic acids and strong-acid
ion exchange resins, may be used for direct esterification. Manufacturers
have the option of recovering any of the acid catalysts or disposing of them
by neutralization and waste treatment. Since ion exchange resins are expen-
sive, ion exchange systems will require resin regeneration equipment.
Some manufacturers may use vacuum equipment for distillations instead of the
atmospheric equipment shown on Fig. III-2. In general the organic emissions
generated by vacuum distillations are expected to exceed those generated by
atmospheric pressure equipment, since vacuum distillations will have air leaks
in addition to the nitrogen bled into the system. These inert gases will pass
through the condensers as noncondensable gases.
Extractants other than water may be used to remove the alcohols from the over-
heads of the reflux distillations. Specific data are considered to be confi-
dential by the manufacturers.
production of Butyl Acrylates by Direct Esterification
Flow diagrams for producing butyl acrylate esters are similar to those of
Fig. III-2. However, butanol must be removed from the butyl acrylate stream
(Stream 15) by azeotropic distillation. The butanol—butyl acrylate azeotrope
would be returned to the esterification reactor. The equipment is probably
not vacuum equipment.
-------
111-14
C. HEAVY-ESTER PRODUCTION
1. Introduction
Heavy esters such as 2-ethylhexyl acrylate may be produced by direct esterifica
tion of acrylic acid with a heavy alcohol. This is the preferred method,
although plants that isolate acrylic acid may also use transesterification of a
lower ester and a heavy alcohol to a heavy ester and a lower alcohol. Plants
that produce the lower esters directly must use transesterification. With the
replacement by Rohm and Haas of the low-pressure modified Reppe process by the
propylene oxidation process, transesterification will also be phased down.
Heavy-ester plants are normally smaller, batch production plants as opposed to
the larger, continuous lower-ester plants because the lower demand for the
heavy esters necessitates higher production flexibility.
2. Direct Esterification
a. Basic Process -- Heavy acrylates are produced by direct esterification accord-
ing to the reaction
CH2=CH-0 + ROH < > CH =CH-C + H^O
OH OR
(Acrylic acid) (Heavy Alcohol) (Heavy Ester) (Water)
The process flow diagram shown in Fig. III-3 represents a typical process using
direct esterification for heavy ester manufacture. The acrylic acid (Stream 1),
the heavy alcohol (Stream 2), the acid catalyst (Stream 3), and a solvent
(Stream 4) are added to an esterification reactor-distillation, where the
reaction then proceeds. The water of reaction is removed by an entraining
solvent, and the vapors are condensed (Stream 5) and decanted. The solvent
phase is returned to the reactor-distillation, and the aqueous phase is sent to
waste disposal (Stream 5K) . Organic emission from the esterification reactor-
distillation is labeled 5A on Fig. III-3.
-------
- DewOTfD VkCUUM 60VJIPM6WT
(51) - FU&lTIVE BMlSSlOUfj FROM
VALV6% AKJO
I
t-1
Ul
Fig. III-3. Manufacture of Heavy Acrylic Acid Esters by Direct Esterification
-------
111-16
The bottoms from the esterification reactor-distillation contain the heavy
ester, unreacted heavy alcohol, unreacted acrylic acid, acid catalyst, and
other materials (Stream 6). This stream is neutralized with a base, and the
phases are separated. The aqueous phase (Stream 8) may be processed to recover
the acid catalyst (Stream 9) or sent to waste treatment (Stream 5K). Organic
emissions from the neutralizer-decanter are labeled 5B on Fig. III-3.
The organic phase (Stream 10) is dehydrated in a vacuum dehydration distil-
lation. The water removed (Stream 5K) is sent to waste treatment. Unreacted
heavy alcohol is recovered in a vacuum alcohol recovery distillation
(Stream 12) and returned to storage. The crude heavy ester (Stream 13) is then
refined in a vacuum ester refining distillation and the refined heavy ester is
stored for shipping (Stream 14).
The batch nature of the heavy-ester plants requires shutdown and cleaning at
the conclusion of each heavy-ester run. The shutdown frequency depends on how
often the heavy ester being produced is changed.
Fugitive losses (51 on Fig. III-3) can occur from valves and seals. These
emissions can contain heavy alcohols, acrylic acid, acid catalyst (if organic),
heavy ester, and entraining solvent. Some of the equipment shown in Fig. III-3
is under vacuum. As was discussed earlier, vacuum equipment should have fewer
fugitive emissions than atmospheric equipment. It is still possible that some
emissions can occur if the static pressure at any point exceeds atmospheric
pressure, e.g., at pumps either receiving or pumping against a high liquid leg.
Storage emission sources (5H on Fig. III-3) are related to acrylic acid stor-
age, heavy-alcohol storage, and catalyst storage (if organic), entraining
solvent storage, base storage (if organic), and heavy-ester storage. No organic
emissions from acid catalyst storage or base storage will occur if these are
inorganic acids and bases.
Handling emissions (5J on Fig. III-3) will occur from loading the heavy ester
in drums, tank cars, tank trucks, and barges.
-------
111-17
c. Process Variations -- The process used for heavy-ester production by direct
esterification varies according to the the specific acid catalyst, entraining
solvent, and base used. Certain acid catalysts (sulfonic acids, ion exchange
resins) may require additional equipment for recovery or regeneration. Dif-
ferent entraining solvents have varying aqueous solubilities, resulting in
different compositions of the solvents in the esterification reactor waste-
water. If the solubility is high, additional distillation equipment Bay be
used on this aqueous stream to strip the vastevater and recover the soluble
solvent.
3 . Heavy-Ester Production by Transesterif ication
a. Basic Process — Heavy esters are produced by transester if ication of lover
esters according to the reaction
CH =CHO R + R'OH < CH2=CHC02R' + ROH
where ROH is the lower alcohol and R'OH is the heavy alcohol.
The process flow diagram for transesterification is similar to that shown in
Fig. III-3 with the following exceptions: (1) the lower ester is stored instead
of acrylic acid, (2) no entraining solvent is used, {3} the distillate fro* the
esterification reactor-distillation (Stream 5) is an azeotrope of the lover
alcohol and the heavy-ester product, (4) no neutralization is required, and
(5) no dehydration distillation is required. The product from the esterifica-
tion reactor-distillation is refined in an alcohol recovery distillation and
ester refining distillation as shown.
Except for possible vacuum equipment discharges, no aqueous streams are gener-
ated in this process. Residues from the ester refining distillation and ester-
ification reactor-distillation are incinerated.
Fugitive, storage, and handling emissions are similar to these described in the
direct process.
-------
111-18
D. REFERENCES*
1. J. W. Nemec and W. Bauer, Jr., "Acrylic Acid End Derivatives," pp. 330--354 in
Kirk-Othmer Encyclopedia of Chemical Technology, 3d ed., Wiley, New York, 1978.
2. R. W. Serth, D. R. Tierney, and T. W. Huges, Source Assessment: Acrylic Acid
Manufacture, State-of-the-Art, 1978 (on file at EPA, IERL, Cincinnati, OH).
3. D. C. Thomas, "Acrylic Acid and Acrylic Esters, Supplement B, Process Economics
Program, Stanford Research Institute, Menlo Park, CA (1974).
4. J. W. Blackburn, IT Enviroscience, Trip Report on Site Visit to Union Carbide
Corp., South Charleston, WV, Dec. 8, 1977 (on file at the EPA, ESED, Research
Triangle Park, NC).
5. Nonconfidential information received May 1978 from Celanese Chemical Co.,
Houston, TX (on file at EPA, ESED, Research Triangle Park, NC).
6. J. W. Blackburn, IT Enviroscience, Trip Report on Site Visit to Rohm and
Haas Co., Deer Park, TX, Nov. 1, 1977 (on file at the EPA, ESED, Research
Triangle Park, NC).
7. F. A. Lowenheim and M. K. Moran, pp. 36-38 in Faith, Keyes and Clark's
Industrial Chemicals, 4th ed., Wiley-Interscience, New York, 1975.
8. "Dow Badische Expands," Chemical Week 122(18), 17 (1978).
9. EPA, Development Document for Effluent Limitations Guidelines and New Source
Performance Standards for the Major Organic Products Segment of the Organic
Chemicals Manufacturing Point Source Category (on file at EPA, ESED, Research
Triangle Park, NC) (April 1974).
10. J. L. Blackford, "CEH Marketing Research Report on Acrylic Acid and Esters,"
pp. 606.4031A-E, 606.4032A-Z, and 606.4033A-J in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park, CA (August 1976).
11. R. T. Morrison and R. N. Boyd, Organic Chemistry, p. 590, 2d ed., Allyn and
Bacon, Boston, 1969.
*Usually, when a reference number is located at the end of a paragraph, it
refers to the entire paragraph. If anothe reference relates to certain por-
tions of that paragraph, that reference number is indicated on the material
involved. When the reference appears on a heading, it refers to all the text
heading.
-------
IV-1
IV. EMISSIONS
Emissions in this report are usually identified in terms of volatile organic
compounds (VOC). VOC are currently considered by the EPA to be those of a
large group of organic chemicals, most of which, when emitted to the atmos-
phere, participate in photochemical reactions producing ozone. A relatively
small number of organic chemicals have low or negligible photochemical reactiv-
ity. However, many of these organic chemicals are of concern and may be sub-
ject to regulation by EPA under Section 111 or 112 of the Clean Air Act since
there are associated health or welfare impacts other than those related to
ozone formation.
INTEGRATED MODEL PLANT
With the exception of the Celanese Chemical Co. at Pampa, TX, all domestic
manufacturers of acrylates produce acrylic acid and its esters at the same
production site. Celanese at Pampa esterifies acrylic acid produced at its
Clear Lake, TX, plant and shipped to Pampa. Producers of heavy esters purchase
acrylic acid and perform esterification at other sites, but the amount of
acrylates thus produced are small and are not considered in this report.
The model plant* used in the studies is based on an integrated acrylates facil-
ity producing acrylic acid by propylene oxidation and ethyl, butyl, and
2-ethylhexyl acrylates (EA, BA, 2-EHA) by direct esterification. The model
plant has a total acrylate production capacity of 76.59 Gg/yr, broken down as
follows:
Capacity Acrylic Acid Equivalent
Product (Gg/yr) (Gg/yr)
AA 10 10
EA 38.94 33
BA 21.]* 14
2-EHA 6.51 _3
Total 76.59 60
*See p. 1-2 for a discussion of model plants.
-------
IV-2
This breakdown is based on actual acrylic acid consumption patterns for 1974
and 1975. Reaction yields are assumed to be 70 mole % based on propylene
2 3
going to acrylic acid and 85 mole % based on acrylic acid going to the esters. '
Methyl acrylate capacity is included with ethyl acrylate capacity. The amount
of methyl acrylate produced is expected to be significantly smaller than the
amount of ethyl acrylate. Emissions of the methyl ester may be slightly higher
than those of the ethyl acrylate because of the higher volatility of methanol
and methyl acrylate when compared with ethanol and ethyl acrylate.
Figure IV-1 shows the configuration of the model plant. The propylene oxi-
dation step produces 60 Gg/yr of acrylic acid, one-sixth of which is sold as
acrylic acid. The remaining five-sixths is reacted to form EA, BA, and 2-EHA
in the proportions shown above. The model plant is operated 8760 hr/yr.*
Atmospheric dispersion parameters for the model plant are given in Appendix B.
1. AA Unit of the Model Plant
The AA plant produces 60 Gg/yr of acrylic acid but does not produce acrolein or
acetic acid for sale. Propylene enters the plant by pipeline and is stored
only in temporary storage. These storage vessels have no emissions since they
are pressure vessels and store a liquefied gas. A hypothetical solvent used to
extract acrylic acid has a molecular weight of 60 and a vapor pressure of
34.5 kPa at storage conditions. These data are based on statistical analysis
of highly volatile organic compounds stored in the United States and represent
4
a statistical mean value for highly volatile solvents. Tank farm storage for
the AA-hypothetical solvent is 250 days, whereas process solvent storage is 7
days. Ten process-related tanks are shown as a single working tank on Fig. IV-1,
each of which is sized for 5 days of storage. Acrylic acid is stored at the
tank farm in four tanks, each sized for 20 days of storage. Table IV-1 sum-
marizes storage tank data. Working and tank farm storage is based on data
received from acrylic acid and ester manufacturers. '
*Process downtime is normally expected to range from 5 to 15%. If the hourly
production rate remains constant, the annual production and annual VOC emis-
sions will be correspondingly reduced. Control devices will normally operate
on the same cycle as the process. Therefore, from the standpoint of cost
effectiveness calculations, the error introduced by assuming continuous opera-
tion is negligible.
-------
(^M) . 14-H . (S-H)
I-H] (I-H)
STEAM
AlR
II! I
III I
ACRYLIC
OllT I- ACID
PROPYLEWB
©
i I ^-'U
I I
I I I
PROCE*>S>. LWlT Z-lUHIBlTORS
PROCEVa. UWIT S- ETUfL
(^-M) , (<-M) i M
-N (*-*>) I4''
3|©f f€
IQL |g
UUlT 4- BUTYL ACRYLKTE
(5-*
fe-e
I I
I I
—
Z-ETVWLHOCYL ACKVLATE
ALCOHOL, tOLVBJT
ETHAMOl. BUTAK10U
ETWVl.
BUTVU Z- ETHYL- AC.PCVUC
AC.IO
ETWYV. 4 -ERA
ACRYLIC
ACID
SOLVENT
UWlTfer TAUK FARM
UUlT
LOADIM^-UtJLOAD
".OLVBJT
6- WASTEWA.TER
DISPOSAL. .
ACID RECOV.
Fig. IV-1. Model Plant for Manufacture of Acrylic Acid
and Acrylic Acid Esters by Propylene Oxide
-------
IV-4
Table IV-1. Acrylic Acid and Esters Model-Plant Storage Requirementsa
b
Process
1
1
1
1
2 (3)d
2 (4)
2 (5)
3
3
3
3,4
3
3
4
4
4
4
4
5
5
5
5
Type of Number Volume
Storage Content of Tanks (m3)
W
w
T
T
W
W
w
w
w
w
T
T
T
W
W
W
T
T
W
T
T
T
Acrylic acid solvent
Acrylic acid
Acrylic acid solvent
Acrylic acid
Ethyl acrylate inhibitor
Butyl acrylate inhibitor
2-EH acrylate inhibitor
Ethyl acrylate solvent
Ethyl acrylate
Ethanol
EA-BA solvent
Ethanol
Ethyl acrylate
Butyl acrylate solvent
Butyl acrylate
Butanol
Butanol
Butyl acrylate
2-ethylhexyl acrylate
2-EHA solvent
2-ethylhexanol
2-ethylhexyl acrylate
1
10
1
4
4
4
4
2
4
1
1
1
1
1
10
1
1
1
8
1
1
3
90.58
0.333
981.8
128.9
8.36
4.16
0.742
27.73
55.45
55.45
8521.0
4396.0
6941.0
26.22
40.09
48.45
2921.0
3870.0
5.71
5.37
1603.0
403.7
Turnovers Bulk L#
per Year TemperatU^
52.1
73.0
1.46
18.3
122
122
73.0
365
122
365
6.08
6.08
6.08
365
243
365
6.08
6.08
209
6.08
4.06
6.08
20.3
27
20.3
27
18.7
J21
-n
20.3
18. 7
27
20.3
20.3
21.4
20.3
27
27
20.3
28.1
32.6
20.3
20.3
29.8
_^s
See refs. 5 and 6.
Process defined as follows: 1 = acrylic acid; 2 = inhibitor makeup; 3 = ethyl
4 = butyl acrylate; 5 = 2-ethylhexyl acrylate.
CW = process-related - working storage; T = tr .ik farm storage.
Numbers in parentheses indicate process to which emissions are prorated.
acr
-------
IV-5
The number of valves and pumps is discussed in Sect. IV.B. The number of
fugitive emission sources is based on data received from acrylic acid and ester
manufacturers.
EA Unit of the Model Plant
The EA model plant is based on the flowsheet in Fig. III-2 and produces
38.94 Gg/yr of ethyl acrylate. Sulfuric acid is used for the acid catalyst,
and conventional sulfuric acid recovery is assumed. Vacuum equipment is as
shown in Fig. III-2. A hypothetical solvent is used to extract ethyl acrylate
from the reflux distillation overheads. This solvent also has a molecular
weight of 60 and a vapor pressure of 34.5 kPa at storage conditions, but is not
necessarily the same solvent as that used for acrylic acid.
Solvent for ethyl acrylate production is stored for 60 days at the tank farm
and in two working tanks, each having 1 day of storage capacity. Ethanol is
stored in a single tank for 60 days at the tank farm and in a single working
tank having 1 day of storage. Ethyl acrylate is stored at the tank farm in one
tank with 60 days of storage capacity and in four working tanks, each with
3 days of storage capacity. These data are based on data received from acrylic
acid and ester manufacture
summarized in Table IV-1.
acid and ester manufacturers. ' Ethyl acrylate storage requirements are
The number of valves and pumps is discussed in Sect. IV.B. The number of
fugitive emission sources is based on data received from acrylic acid and ester
manufacturers.
BA Unit of the Model Plant
The butyl ester model plant is based on the flowsheet in Fig. III-2 with the
variations discussed in Sect. III.B.3.
The solvent used for butyl acrylate manufacture is a hypothetical solvent
having a molecular weight of 60 and a vapor pressure of 34.5 kPa at storage
conditions. This solvent is not necessarily the same as that used in acrylic
acid manufacture but is assumed to be the same as the one used in ethyl acry-
late manufacture. Therefore tank farm storage will be shared with that speci-
fied for ethyl acrylate. Solvent working storage is a single tank with 1 day
of storage capacity.
-------
IV-6
n-Butanol is stored at the tank farm in a single tank having 60 days of storage
capacity. One working tank stores n-butanol and has 1 day storage capacity.
Butyl acrylate is stored at the tank farm in a single tank having 60 days of
storage capacity. For working butyl acrylate storage there are ten tanks, each
having 1.5 days of storage capacity. The storage requirements summarized in
Table IV-1 are based on data supplied by acrylic acid and ester producers.
The number of valves and pumps is discussed in Sect. IV.B. The number of
fugitive emiss
manufacturers.
fugitive emission sources is based on data received from acrylic acid and ester
5
4. 2-EHA Unit of the Model Plant
The 2-EHA model plant is based on the flowsheet in Fig. III-3. The system
assumes a sulfuric acid catalyst with sulfuric acid recovery. A hypothetical
solvent to remove water of esterification is used. This solvent has a molec-
ular weight of 60 and a vapor pressure at storage conditions of 34.5 kPa. It
is not necessarily the same as solvents used in acrylic acid or lower-ester
manufacture. An inorganic base, such as sodium hydroxide or ammonia, is used
for neutralization of the ester mixture.
Storage for solvent used in 2-EHA manufacture requires a single tank farm tank
sized for 60 days of storage. No working tankage is needed for the solvent.
One tank is used to store 2-ethylhexanol and provides for 90 days of storage.
No working tankage is needed. 2-ethylhexyl acrylate is stored in three tank
farm tanks, each having 60 days of storage capacity. Eight working tanks
having 1.75 days of storage are used to store 2-ethylhexyl acrylate. Table IV-1
summarizes the storage requirements for manufacture of 2-EHA and is based on
data supplied by acrylic acid and ester manufacturers.
The number of valves and pumps is discussed in Sect. IV.B. The number of
fugitive emission sources is based on dat* received from acrylic acid and ester
manufacturers.
5. Inhibitor Unit of the Model Plant
A central inhibitor facility is used to store and mix the inhibitor for each
process. Individual tankage is uoed to isolate the inhibitor for each ester.
-------
IV-7
Tankage for the inhibitor model plant consists of four tanks for ethyl acrylate
inhibitor and the same for butyl acrylate and 2-ethylhexyl acrylate. The ethyl
and butyl inhibitor tanks have 3 days of storage capacity and the ethylhexyl
inhibitor tanks have 5 days of storage capacity. These data are based on in-
formation supplied by acrylic acid and ester manufacturers.
The number of valves and pumps is discussed in Section IV.B. The number of
fugitive emiss
manufacturers.
fugitive emission sources is based on data received from acrylic acid and ester
5,6
SOURCES AND EMISSIONS
Estimates of the uncontrolled emissions for the model plant are based on infor-
mation received by virtually all the manufacturers of acrylic acid and esters.
These data range from sample data for specific organics at specific process
vents to material balance calculations. Overall, the estimate for uncontrolled
emissions is expected to be accurate. Estimates of controlled emissions are
based upon sparse sampled data from acrylic acid and esters plants.
The process emissions in the model plant are of two general categories: those
emissions that vary linearly or nearly linearly with plant capacity (e.g., the
quench-absorber off-gas), and those emissions that are constant or vary nonlin-
early with capacity (e.g., losses from vacuum equipment). Vacuum equipment
losses are functions of the air leaks into the equipment or the inert gas bled
into the equipment to control the vacuum. These streams can vary from equip-
ment to equipment, based on the vacuum pressure. Emissions from vacuum equip-
ment are constant for each site since the air or inert leakage is independent
of the production rate. However, these vacuum-related emissions vary from site
to site as a function of the capacity ratio raised to the 0.65 power. This
reflects the concept that large plants have larger vacuum equipment, which
provides the same number of leak sites but a higher leak area per site.
Fugitive emissions are assumed constant regardless of production rate and plant
capacity. Storage tank working losses vary linearly with production rate and
capacity, while breathing losses are independent for capacity or production
rate.
-------
IV-8
Secondary emissions from wastewater treatment can be a significant fraction of
the total controlled emission levels. These values are based on key literature
sources reporting VOC emissions from biochemical treatment plants. Further
discussion of these calculations is presented in a separate EPA document con-
7
cernxng secondary emissions.
1. Acrylic Acid Unit of the Model Plant
a. Quench-Absorber Off-Gas — Stream 1A on Fig. III-l represents the off-gas from
the quench-absorber. This stream consists of air, propylene, unreacted organic
feed materials (propane), and organic vapors from the product (acrylic acid)
and by- products (acetic acid, acrolein, and others). Table IV-2 gives the
Q
composition of this stream from one manufacturer.
This emission is assumed to be a linear function of the production rate since
the inert-gas flow rate must be proportional to the amount of acrylic acid
D
formed. Data from one manufacturer indicate that the emission ratio of vola-
tile organic compounds (VOC) to acrylic acid produced is 0.1193. This converts
to 7157 Mg of VOC/yr for the model plant. This value is specific to a particu-
lar manufacturer but is expected to apply generally to all manufacturers of
acrylic acid using propylene oxidation technology.
b. Combined Vents for Atmospheric Equipment — Streams IB and 1C on Fig. III-l are
vents from the atmospheric pressure sections of the acrylic acid equipment.
The first, the extraction vent, has an emission relating to the normal opera-
tion of the extraction column. The second relates to noncondensables emitted
from the raffinate stripper condenser. These emissions are combined and are
assumed to be linear with production rate. Less than 9 Mg of VOC per year
arises from this source for the model plant. Composition of this stream is
shown in Table IV-3.
c. Combined Vents for Vacuum Equipment — Streams ID through 1G are all vents from
vacuum distillation equipment. Vacuum control is achieved by bleeding nitrogen
into each piece of equipment to maintain a specific pressure. This noncondens-
able gas carries some orga^c vapors with it as it leaves the condensers and
vacuum system. After-condensers, or "tail" condensers, are typically used to
-------
IV-9
Table IV-2. Composition of Acrylic Acid Quench—
Absorber Off-Gas in Model Planta
Component
Acetaldehyde
Acetic acid
Acetone
Acrolein
Acrylic acid
Ethyl acrylate
Propane
Propylene
Water
Carbon dioxide
Carbon monoxide
Nitrogen
Oxygen
Weight Percent
<0.002
0.027
0.025
0.087
0.347
0.023
1.45
0.337
1.71
5.19
2.28
86.0
2.4a
Emission Ratio
(kg/Mg)b
<0.1
1.4
1.3
4.5
18.0
1.2
75.3
17.5
88.6
269.5
118.5
4466.6
128.8
*See ref 8.
kg of component per Mg of acrylic acid.
Table IV-3. Composition of Combined Waste Gas from Vents from
Acrylic Acid Atmospheric Pressure Equipment in Model Plant*
Component Weight Percent
VOC 0.089
Carbon dioxide 18.59
Nitrogen 81.06
Carbon monoxide 0.26
Methane 0.002
*
See ref. 5
-------
IV-10
minimize organic losses to the vacuum system. Uncontrolled emissions in this
study refer to the streams leaving the vacuum system after they have been
passed through all the tail condensers.
These emissions are constant with production rate but are nonlinear functions
of plant capacity and are adjusted to conform to the model plant capacity.
Table IV-4 lists the individual compositions of these streams.
Streams ID through 1G result in VOC emissions of 227 Mg/yr. Each manufacturing
plant using the propylene oxidation process is assumed to have this emission
regardless of capacity. Solvents having differing vapor pressures can signifi-
cantly change this value.
d. Fugitive Emissions — Process pumps, process valves, and relief valves are
potential sources of fugitive emissions, even when operating on vacuum equip-
ment, if static pressures are greater than atmospheric. Ten percent of the
vacuum equipment fugitive sources are assumed to operate under positive pres-
sures, thus generating fugitive emissions. Some 5/9 of the acrylic acid proc-
essing equipment is assumed to be atmospheric equipment. Thirty-six pumps (of
which 18 are spares), 44 relief valves, and 820 process valves are assumed to
be a typical case for acrylic acid manufacture. All pumps operate on light
liquids, all relief valves operate on gases and vapors, and all process valves
operate on light liquids. The fugitive emission factors shown in Appendix C
were applied in calculating the emissions listed in Table IV-5.
e. Storage Emissions — Storage emissions for acrylic acid manufacture relate to
tank farm and working storage for the acrylic acid extraction solvent and
acrylic acid product. Propylene storage has no emissions since pressurized
tanks are used to store propylene as a liquid. A hypothetical solvent having a
molecular weight of 60 and a vapor pressure of 34.5 kPa at storage conditions
is assumed. The storage required for acrylic acid working and tank farm tankage
is presented in Table IV-1. These calculations are based on fixed-roof tanks,
one-half full, and a 12.1°C diurnal temperature variation. Emission equations
from AP-42 were used with one modification: the breathing losses were divided
by 4 to account for recent evidence that indicates the AP-42 breathing loss
9 10
equation overestimates emissions. ' Weather conditions correspond to data
-------
IV-11
Table IV-4. Composition of Waste Gases from Extraction and a
Refining Vacuum Vents in Acrylic Acid and Esters Model Plant
Component
Weight
Percent
Total
Foreruns Distillation Vent (Stream IE)
Hydrocarbon solvent 9.64
Acrylic acid 0.03
Oxygen 0.88
Nitrogen 89.31
Water 0.14
Total
Emission
Rate
(kg/hr)
Extract Distillation Vent (Stream ID)
Hydrocarbon solvent 34.15
Acrylic acid 0.03
Carbon dioxide 1.19
Oxygen 1.12
Nitrogen 63.51
63.36
4.055
0.01
0.370
37.55
0.059
42.04
Acrylic Acid Distillation Vent (Streams IF and 1G)
Hydrocarbon solvent 0.84 0.193
Carbon dioxide 0.16 0.036
Oxygen 3.45 0.795
Water 0.68 0.157
Nitrogen 94.87 21.85
Total 23.03
ee ref. 5.
Includes residue distillation.
-------
IV-12
Table IV-5. Total VOC Uncontrolled Fugitive Emissions
in Acrylic Acid and Esters Model Plant
Emission Rates (kg/hr)
Process
Unit*
1
2
3
4
5
6
Total
From
Pumps
1.68
0.48
1.80
1.80
1.08
3.12
9.96
From
Relief Valves
4.16
1.28
1.76
1.76
0.96
1.44
11.36
From
Process Valves
4.92
1.55
1.91
1.91
1.67
7 . 11
19.07
Total
10.76
3.31
5.47
5.47
3.71
11..67
40.4
*Numbers refer to Fig. IV-1 and are defined as follows:
1 = acrylic acid; 2 = inhibitor makeup; 3 = ethyl acrylate;
4 = butyl acrylate; 5 = 2-ethylhexyl acrylate; 6 = tank farm.
-------
IV-13
for the Houston, TX, area. Emissions calculated for a fixed-roof tank and
presented in Table IV-6 include working and breathing losses.
f. Handling Emissions — Handling emissions for acrylic acid manufacture include
emissions relating to loading acrylic acid in drums, tank cars, tank trucks,
9
and barges. The emissions are calculated from equations in AP-42. A break-
down of the emissions from each loading source is presented in Table IV-7.
Secondary Emissions — The following three secondary emissions relate to
acrylic acid production: the spent catalyst, which requires regeneration or
disposal; the wastewater from the quench-absorber, which is sent to a bio-
logical treatment plant; and finally, the liquid and solid organic residues,
which are incinerated.
The emissions resulting from catalyst replacement are small. Care is taken to
prevent the organic from being emitted.
The aqueous waste from acrylic acid plants has been reported to average
0.1041 g of VOC/g of acrylic acid produced and contains acrylic acid, polymers,
inhibitor, acetic acid, and solvent. The model plant will produce 11.1 Gg of
dissolved VOC per year in its aqueous waste at a liquid flow of 50.6 m /hr
(assuming a 2.5 wt % VOC concentration). VOC emissions of from 0.1 to 3.7 Mg/
yr are estimated to be produced during biooxidation of this waste. The value
shown in Table IV-8 is 0.208 kg/hr, or 1.8 Mg/yr, and represents a reasonable
level, considering the specific components. Concentrations of solvents with a
high relative volatility can markedly increase the secondary emissions from
this source.
Information about the generation of liquid residues is generally sensitive to
the acrylic acid manufacturers. These residues are often used as supplementary
o
fuel for steam-generating incineration unJts. Emissions from this source are
considered as controlled emissions in the discussion in Sect. V.
Generation of solid residues is related to a process upset, where some of the
acrylic acid polymerizes at random intervals. About 4.5 Mg/yr of solid aery-
late polymer residue is assumed to be generated by the model plant. Emissions
-------
IV-1
Table IV-6. Total VOC Uncontrolled Storage
Emissions for Fixed-Roof Tanks
Process
Unita
1
2
4
5
Total
From
Working Tanks
0.431
0.871°
0.416°
0.005°
1.72
Emission Rates (kg/hr)
From
Tank Fram Tanks
0.539
7.30d
2.62d
0.069
10.53
Total
0.97
8.17
3.04
0.07
12.3
Numbers refer to Fig. IV-1 and are defined as follows:
1 = acrylic acid; 3 = ethyl acrylate; 4 = butyl aerylate;
5 = 2-ethylhexyl acrylate.
b
Includes working and breathing losses.
c
Inhibitor working tank emissions included.
d
Single solvent storage tank emission prorated against processes 3 and 4.
-------
IV-15
Table IV-7. Total VOC Uncontrolled Handling Emissions in
Acrylic Acid and Esters Model Plant
Emission Rate (kg/hr)
Process
Unit9
1
3
4
5
Total
From c
Drums
0.0006
0.043
0.0059
0.0001
0.050
From Tank Car
and Tank Truck
0.0033
0.261
0.033
0.0006
0.298
From
Barge
0.0017
0.130
0.017
0.0003
0.149
Total
0.006
0.434
0.056
0.001
0.497
Process numbers refer to Fig. IV-l and are defined as follows: • 1 = acrylic
acid; 3 = ethyl acrylate; 4 = butyl acrylate; 5 » 2-ethylhexyl acrylate.
The following loading ratios of each product are assumed: of every 10 m of
each product loaded, 1 m3 is drummed, 3 m3 is loaded into barges, and 6 m3
is loaded into tank cars or tank trucks.
Loading losses for drumming were assumed to possess the same "saturation
factor" (see ref. 9) as those for tank car, tank truck, and barge; satura-
tion factor, S = 0.5.
Table IV-8. Total VOC Uncontrolled Secondary Emissions in
Acrylic Acid and Esters Model Plant
Emission Rate (kq/hr)
Process
Unit3
1
3,4,5
Total
From .
Wastewater
0.014 — 0.428
0.208
0.011 — 0.332
0.155
0.025 — 0.760
0.363
From
Residues
0.005
0.005
0.010
From Sulfuric
Acid Recovery**
None
41.8
41.8
Process numbers refer to Fig. IV-l and are defined as follows:
1 » acrylic acid; 3 = ethyl acrylate; 4 « butyl acrylatej 5 = 2-ethylhexyl
acrylate.
bSee ref 7.
c
Emissions from residue incineration.
dSee ref. 6.
eThis value used in data in following tables.
-------
IV-16
arising from the incineration of this material contribute 0.045 Mg of VOC per
year. The solids incinerator burning this material is a unit servicing more
than this acrylate plant. It has primary and secondary combustion chambers and
operates at 99% VOC removal.
Secondary emissions for the acrylic acid plant are presented in Table IV-8.
2. EA Unit of the Model Plant
Emissions from the model plant are discussed in the following sections. How-
ever, one manufacturer producing ethyl acrylate by a confidential process
reports total ethyl acrylate process emissions of 0.0425 g of VOC per g of
g
ethyl acrylate. Other manuf;
the model plant in emissions.
g
ethyl acrylate. Other manufacturers' processes are expected to be similar to
a. Combined Vents from Atmospheric Equipment -- Streams 3A through 3C on
Fig. III-2 represent emissions from equipment used in the production of ethyl
acrylate by direct esterification. All these emissions originate from non-
condensable gases passing through condensers in these atmospheric-pressure
distillations. These emissions together contribute 0.00054 g of VOC/g of ethyl
acrylate produced and the amount is assumed to be linear with production rate.
This converts to 21.1 Mg of VOC per year for the model plant. The composition
of this combined stream is shown in Table IV-9.
b. Combined Vents from Vacuum Equipment -- Streams 3D through 3F on Fig. III-2
result from noncondensable gases passing through condensers in vacuum distil-
lation equipment. These emissions together contribute 148 Mg of VOC per year
and are a nonlinear function of capacity. Table IV-10 shows the composition of
this combined stream.
c. Fugitive Emissions — Process pumps, process valves, and relief valves are
potential sources of fugitive emissions. Even pumps and valves operating on
vacuum equipment may contribute to fugitive emissions if they operate in loca-
tions having static pressures greater than atmospheric.
Ten percent of pumps, valves, and relief valves operating on vacuum equipment
are expected to have fugitive losses. Some 5/8 of the ethyl acrylate process
-------
IV-17
Table IV-9. Composition of Waste Gases from Vents from
Ethyl Acrylate Atmospheric Equipment in Model Plant*
Weight
Component Percent
Denaturant 0.19
Ethyl aerylate 2.43
Ethyl ether 0.20
Ethanol 1.70
Oxygen 13.00
Nitrogen 79.57
Water 1.09
Methane 1.82
*See ref. 5.
Table IV-10. Composition of Waste Gases from Vents from
Ethyl Acrylate Vacuum Equipment in Model Plant*
Component
Ethyl acrylate
Denaturant
Ethyl ether
Ethanol
Oxygen
Nitrogen
Water
Weight
Percent
0.74
1.55
2.02
0,18
2.94
91.65
0.92
Total
Emission
Rate (kcr/hr)
2.77
5.82
7.57
0.68
11.03
343.8
3.45
375.1
*See ref. 5.
-------
IV-18
equipment is assumed to be atmospheric equipment. Twenty-two pumps (11 of
which are spares), 16 relief valves, and 288 process valves are assumed to be
typical numbers for ethyl acrylate manufacture. All pumps operate on light
liquids, all relief valves operate on gases and vapors, and all process valves
operate on light liquids. Fugitive emission factors, as shown in Appendix C,
are applied to calculate the fugitive emissions shown in Table IV-5.
d. Storage Emissions — Storage emissions for ethyl acrylate manufacture relate to
tank farm and working storage for ethyl acrylate solvent, ethyl acrylate, and
ethanol. A hypothetical solvent having a molecular weight of 60 and a vapor
pressure of 34.5 kPa at storage conditions is assumed. The storage required
for ethyl acrylate working and tank farm storage is presented in Table IV-1.
Emission calculations are based on fixed-roof tanks, half full, a 12.1% diurnal
temperature variation. Emission equations from AP-42 were used with one modifi-
cation: the breathing losses were divided by 4 to account for recent evidence
9 10
that indicates the AP-42 breathing loss equation overestimates emissions. '
Weather conditions correspond to data from the Houston, TX, area. Emissions
calculated for fixed- roof tanks and presented in Table IV-6 include working
and breathing losses.
e. Handling Emissions — Handling emissions for ethyl acrylate manufacture include
emissions relating to loading ethyl acrylate in drums, tank cars, tank trucks,
9
and barges. The emissions are calculated from equations in AP-42. A break-
down of the emissions from each loading source is presented in Table IV-7.
f. Secondary Emissions — There are three secondary emissions related to acrylic
ester production: spent acid, which is recovered; other wastewater, which is
disposed of in biochemical treatment plants,- and organic liquids and solids,
which are incinerated.
Emissions from a sulfuric acid concentrator for one manufacturer are limited to
113 kg/hr by local regulations. The unit operates about 90% of the time on
acid from acrylate ester production. About 5.5 g of VOC/kg of acrylate ester
may be expected, which amounts to 366 Mg/yr of VOC from acid recovery.
-------
IV-19
Total organic carbon in the aqueous waste from acrylic ester manufacture is
12
reported as 30.8 g per kg of acrylates manufactured. If this carbon is
assumed to be a 3-carbon compound with a molecular weight of 85, then 72.7 g of
VOC/kg of total acrylate (excluding acrylic acid capacity), or 4.84 Gg/yr, is
generated from the model plant. The emissions related to this wastewater range
from 0.1 to 2.9 Mg/yr for the model plant. The expected value, estimated to be
0.155 kg/hr, or 48.4 Mg/yr, is shown in Table IV-8. Further information is
7
given in a separate EPA report.
The model plant is assumed to produce 4.5 Mg/yr of organic solids for incin-
eration. The VOC emission resulting from this material is 0.045 Mg/yr. Liquid
organic waste streams are incinerated in heat-recovery incinerators as supple-
mental fuel. This incinerator is discussed in Sect. V.
Secondary emissions are summarized in Table IV-8.
3 BA Unit of the Model Plant
Process Emissions — Process emission sources for BA are assumed to be similar
a. -
to those produced in manufacturing ethyl acrylate. A manufacturer of BA
g
reports emissions of 0.0008 g of VOC/g of BA produced. The composition of the
combined streams is shown in Table IV-11. Emissions for the model plant are
19.1 Mg/yr. It is assumed that 14% of the emissions arises from atmospheric
equipment, similar to that used in producing EA.
. Fugitive Emissions — Fugitive emissions for BA are assumed to be similar to
v • -
those in the manufacture of EA. These are shown in Table IV-5.
Storage Emissions — Storage emissions for BA manufacture relate to tank farm
c — ~ ~ ~
and working storage for BA solvent, BA, and butanol. The solvent is the same
as that used for EA manufacture and shares tank farm tankage with the EA sol-
vent. Emission calculations are based on fixed-roof tanks, half full, a 12.1°C
diurnal temperature variation. Breathing losses were modified as previously
9 10
indicated. ' Heather conditions correspond to data from the Houston, TX,
area. Emissions calculate-7 for fixed-roof tanks, presented in Table IV-6,
include working and breathing losses.
-------
IV-20
Table IV-11. Composition of Combined Waste Gas from All Butyl
Acrylate Equipment in Acrylic Acid and Esters Model Plant*
Components Weight Percent
Butyl aerylate 1.83
Butanol 1.83
Water 8.68
Air 87.60
*See ref 8.
-------
IV-21
d. Handling Emissions — Handling emissions for BA manufacture include those
relating to loading BA in drums, tank cars, tank trucks, and barges. The
emissions are calculated from equations in AP-42. A breakdown of the emis-
sions from each loading source is presented in Table IV-7.
e. Secondary Emissions — Secondary emissions for all acrylate ester manufacture
are discussed in Sect. IV.B.2.f.
4. 2-EHA Unit Model of the Plant
a. Combined Vents from Atmospheric Equipment -- Stream 5A on Fig. III-3 vents
noncondensable gases from the condensers on the esterification reactor-distil-
lation. Stream 5B on Fig. III-3 vents the neutralizer. These emissions are
assumed to be linear with production rate. The organic emission related to
these streams is 0.00488 g of VOC/g of 2-EHA. The average composition is shown
in Table IV-12. About 31.8 Mg of VOC per year arises from this source.
£ Combined Vents from Vacuum Equipment -- Streams 5C through 5E on Fig. III-3
correspond to noncondensable gases passing through the condensers on the 2-EHA
vacuum refining distillations. These emissions are assumed to be a nonlinear
function of capacity and contribute 16.6 Mg/yr of VOC. The average composi-
tions for these streams are shown in Table IV-13.
c. Fugitive Emissions -- Process pumps, process valves, and relief valves are
potential sources of fugitive emissions. Even pumps, relief valves, and valves
operating on vacuum equipment may contribute to fugitive emissions if they
operate in locations having static pressures greater than atmospheric.
It is assumed that 10% of the pumps, process valves, and relief valves opera-
ting on vacuum equipment will have fugitive losses. Two-fifths of the 2-EHA
process equipment is assumed to be atmospheric equipment. Twenty-two pumps (of
which 11 are spares), 13 relief valves, and 363 process valves are assumed to
be typical numbers for 2-EHA manufacture. All pumps operate on light liquids,
all relief valves operate on gases and vapors, and all process valves operate
on light liquids. Fugitive emission factors, shown in Appendix C, were applied
to calculate the fugitive emissions shown in Table IV-5.
-------
IV-2 2
Table IV-12. Composition of Waste Gases from Vents from
2-EHA Atmospheric Equipment in Acrylic Acid and Esters Model Plant*
Component
Weight Percent
Hydrocarbon solvents
Ethyl ether
"Light boiler"
Carbon dioxide
Argon
Oxygen
Nitrogen
Water
Methane
13.96
1.60
1.28
0.14
0.26
6.40
75.78
0.74
0.11
*See ref 5.
Table IV-13. Composition of Waste Gases from Vents from
2-EHA Vacuum Equipment in Acrylic Acid and Esters Model Plant*
Component
Several light organic unknowns
Argon
Oxygen
Nitrogen
Water
Total
(wt %)
9.47
0.61
11.56
77.48
0.61
Emissions
(kg/hr)
1.89
0.12
2.24
15.03
0^12
19.40
*See ref 5.
-------
IV-23
d. Storage Emissions -- Storage emissions for 2-EHA manufacture relate to tank
farm and working storage for 2-EHA solvent, 2-ethylhexanol, and 2-EHA. A
hypothetical solvent having a molecular weight of 60 and a vapor pressure of
34.5 kPa at storage conditions is assumed. The storage required for 2-EHA
working and tank farm storage is presented in Table IV-1. Emission calcula-
tions are based on fixed-roof tanks, half full, a 12.1% diurnal temperature
variation. Emission equations from AP-42 were used with one modification:
9 10
breathing losses were modified as previously indicated. ' Weather conditions
correspond to data from the Houston, TX, area. Emissions calculated for fixed-
roof tanks and presented in Table IV-6 include working and breathing losses.
e. Handling Emissions — Handling emissions for 2-EHA manufacture include emis-
sions relating to loading 2-EHA in drums, tank cars, tank trucks, and barges.
g
The emissions are calculated from equations in AP-42. A breakdown of the
emissions from each loading source is presented in Table IV-7.
ff Secondary Emissions -- Secondary emissions for all acrylate ester manufacture
are discussed in Sect. IV.B.2.f.
5 Inhibitor and Tank Farm Units of the Model Plant
Figure IV-1 shows an integrated acrylates facility including inhibitor makeup
and tank farm, with which fugitive emissions are related. The inhibitor model
plant has 4 pumps (of which 2 are spares), 8 relief valves, and 155 process
valves. The tank farm has 26 pumps (of which 13 are spares), 9 relief valves,
and 711 process valves.
Storage emissions in the inhibitor model plant and the tank farm are prorated
against the process that they serve.
, Total Model Plant Uncontrolled Emissions
to -
Table IV-14 shows the uncontrolled emissions for the integrated acrylate model
plant; stream designations refer to Fig. IV-1.
-------
IV-24
Table IV-14. Total Uncontrolled VOC Emissions from Acrylic
Acid and Esters Integrated Model Plant
Source
Acrylic acid quench-absorber off-gas
Combined Vents
From acrylic acid atmospheric equipment
From acrylic acid vacuum equipment
From ethyl acrylate atmospheric
equipment
From ethyl acrylate vacuum equipment
From all butyl acrylate equipment
From 2-EHA atmospheric equipment
From 2-EHA vacuum equipment
Storage
Working
Tank farm
Fugitive
Handling
Drum loading
Tank car/truck loading
Barge loading
Secondary
Wastewater
Organic residues
Sulfuric acid recovery
Stream Emission Ratio Emission I*
Designation (g/kg of product3) (kg/hr)
1A
IB, 1C
ID, IE, IF, 1G
3A,3B,3C
3D,3E,3F
4A,4B,4C,4D,4E,4F
5A,5B
5C,5D,5E
1H,3H,4H,5H
1H,3H,4H,5H
11,21,31,41,51,61
1J,3J,4J,5J
1K,3K,4K,5K
1K,3K,4K,5K
1K,3K,4K,5K
119.3
0.146
3.78*>
0.54
3.79b
0.90C
4.88
2.54b
0.20d
1.20d
4.62b
0.06d
0.04d
o.ooib
4.78d
Total
817
<1
25.9
2.41
16.9
2.18
3.63
1.89
1.72
10.5
40.4
0.050
0.298
0.149
0.363
o.oio
41.8
966
aBased on model plant capacities of each product, unless otherwise noted.
Constants or independent of production rate; .onlinear function of capacity; valid
only for model plant.
cData adjusted by assuming 14% of total corresponds to atmospheric equipment, which
varies linearly with capacity, and the remainder corresponds to vacuum equipment,
which varies nonlinearly with capacity.
dBased on total acrylates capacity (76.59 Gg/yr).
-------
IV-2 5
C. REFERENCES*
1. J. L. Blackford, "CEH Marketing Research Report on Acrylic Acid and Esters,"
pp. 606.4031 A-E, 606.4032 A-Z, and 606.4033 A-J in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park, CA (August 1976).
2. J. W. Nemec and W. Bauer, Jr., "Acrylic Acid and Derivative," pp. 330--354 in
Kirk-Othmer Encyclopedia of Chemical Technology, 3d ed., Wiley, New York, 1978.
3. R. W. Serth, D. R. Tierney, and T. W. Huges, Source Assessment: Acrylic Acid
Manufacture State-of-the-Art (on file at IERL, EPA, Cincinnati, OH) (1978).
4. D. G. Erikson, IT Enviroscience, Storage and Handling (September 1980) (EPA/
ESED report. Research Triangle Park, NC)
$. J. W. Blackburn, IT Enviroscience, Trip Report on Site Visit to Union Carbide
Corp., South Charleston, WV, Dec. 8, 1977 (on file at EPA, ESED, Research
Triangle Park, NC).
5. J. W. Bldckburn, IT Enviroscience, Trip Report on Site Visit to Rohm and Haas
Co., Deer Park, TX, Nov. 1, 1977 (on file at the EPA, ESED, Research Triangle
Park, NC).
7. J. Cudahy and R. Standifer, IT Enviroscience, Secondary Emissions (June 1980)
(EPA/ESED report, Research Triangle Park, NC).
8. Nonconfidential information received May 1978 from Celanese Chemical Co.,
Houston, TX (on file at EPA, ESED, Research Triangle Park, NC).
g. C. C. Masser, "Storage of Petroleum Liquids," pp. 4.3-6 to 4.3-11 in Compila-
tion of Air Pollutant Emission Factors, AP-42, Part A, 3d ed. (August 1977).
10. E. C Pulaski, TRW, Inc., letter dated May 30, 1979, to Richard Burr, EPA.
xl. Mgnsanto Research Corp. and Research Triangle Institute, The Industrial Organic
Chemicals Industry,Chapter 6, Part I. pp. 6-663, 6-665, EPA, Research Triangle
park, NC (n.d.).
12. EPA, Development Document for Effluent Limitations Guidelines and New Source
Performance Standards for the Major Organics Products Segment of the Organic
Chemicals Manufacturing Point Source Category (on file at EPA, ESED, Research
Triangle Park, NC) (April 1974).
*Usually, when a reference is located at 1ae end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on a heading, it refers to all the text covered by that
heading.
-------
V-l
V. APPLICABLE CONTROL SYSTEMS
A. ACRYLIC ACID FROM PROPYLENE AND ESTERS BY DIRECT ESTERIFICATION - INTEGRATED
PLANT
Thermal Oxidizer
The current practice for emission control in the manufacture of acrylic acid
and esters is the use of a liquid-fume thermal oxidizer to burn organic emis-
sions from an integrated plant. This unit typically incorporates heat recovery
and thus becomes an energy source for the acrylates processing plant or other
plants on-site. This control device has been necessary because of the
extreme odor-causing nature of acrylic acid and its esters. In addition, it is
necessary to destroy toxic materials such as acrolein that are present in the
manufacture of acrylic acid.
The integrated acrylates model plant, as shown in Fig. IV- 1, will utilize a
liquid- fume thermal oxidizer as the major applicable control device. Vents
from acrylic acid, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate,
inhibitors, and loading will be routed to an incinerator in a series of vent
manifolds. Figure V-l shows the collection system and material balance for
this control device.
Process Emissions — The major organic emission from the integrated model plant
arises from the propylene oxidation quench- absorber. This stream is a rela-
tively constant emission source and is labeled Stream 1A or I on the flow
diagram of Fig. V-l.
Emissions from atmospheric pressure equipment are combined from acrylic acid,
ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate processing units.
Stream II of Fig. V-l shows the total VOC contribution from these vents.
Emissions from vacuum processing equipment arise from the acrylic acid, ethyl
acrylate, butyl acrylate and 2-ethylhexyl acrylate processing units. These
emissions largely arise from nitrogen gas bled into the equipment to control
the vacuum pressure. Vac' ... equipment typically is designed to utilize several
condensers in series on the uncor.densed gases leaving the equipment. Secondary
-------
PRE-iAUPlE. EQUIPMEUT VE.V1TS
VACUUM EQUIPMENT VEUTS
RECOVERY
Fig. V-l. Liquid-Fume Thermal Oxidizer for Acrylic
Acid and Ester Model Plant
-------
V-3
condensers remove some additional VOC that may have passed through the main
condenser. These additional control devices are "in series" with the major
control device -- the thermal oxidizer. They are not the best control option,
since organic reduction by use of condensers alone will not abate the odor
problem; therefore combustion of the streams after the condensers is practiced.
Emissions shown on Fig. V-l as uncontrolled emissions are therefore defined as
the emissions leaving the last secondary condenser before entering the thermal
oxidizer.
Working Storage Emissions — This integrated acrylates facility has both work-
ing storage (or process tanks) and tank farm storage (for bulk storage) as
shown in Table IV-1. The working storage losses will be collected in a suction
header, combined with other emissions, and sent to the thermal oxidizer for use
as combustion air. The vent from each tank discharges into the base of a
conical pipe leading to the suction manifold. The suction is supplied by the
suction side of a blower delivering combustion air to the thermal oxidizer.
Each conical ending is individually designed to allow sufficient air to enter
the manifold to capture all the organic emission from the tank at the greatest
instantaneous flow rate of the tank emission and to dilute the organic below
the lower explosive limit. Pressure drops in all the manifold legs are con-
sidered and Lower Explosion Limit (LEL) monitors are used to maintain nonexplo-
sive conditions in the manifold. Emissions shown on Fig. V-l assume that all
streams collected in the suction manifold have VOC concentrations of 50% of the
lower explosive limit for ethyl aerylate. The LEL for ethyl acrylate is
4
reported to be 1.8 vol %.
Storage tank emissions are discussed later.
Fugitive Emissions — Fugitive emissions can occur in the integrated model
.——^™-
plant even though much of the equipment is operated under vacuum. Important
sources of fugitive losses are collected in the suction manifold discussed
above. Fugitive emissions occurring in enclosed areas, where the air flow may
be controlled are included in the suction manifold. Process sumps or equipment
inside the buildings are examples of this.
-------
V-4
Fugitive emissions shown on Fig. V-l are assumed to be controlled emissions
(major leaks detected and repaired and mechanical seals on pumps) as defined in
Appendix C. Many of the pumps, relief valves, or process valves are on equip-
ment that is located outdoors. These potential fugitive emission sources are
impractical for inclusion in the suction manifold. Therefore the collected
fugitive emissions used in Fig. V-l are assumed to be 50% of the controlled
fugitive emissions calculated as described in Appendix C. The remainder are
assumed to be emitted to the atmosphere and are shown as uncollected fugitive
emissions on Table V-l.
d. Handling Emissions — Emissions from loading acrylic acid and esters in drums,
tank cars, tank trucks, and barges are small and probably would not require
control on the basis of VOC alone. However, odor and toxicity problems require
more stringent control techniques than those mandated by VOC control alone.
In the model plant it is assumed that all loading locations are within close
proximity to the acrylic acid and esters unit so that these emissions can be
included in the suction manifold. These emissions are shown as Stream VI on
Fig. V-l.
When the loading stations are significantly distant from the thermal oxidizer,
on-site control devices such as vapor recovery, fume incineration, and other
techniques may be used for occupational health and odor control. Costs for
these devices will not be included since their use is mandated by guidelines
other than VOC reduction.
e. Secondary Emissions -- The integrated model plant produces significant quan-
tities of liquid organic wastes that are burned in the thermal oxidizer. These
wastes are shown as Stream VIII on Fig. V-l.
f. Supplementary Combustion Air and Fuel -- The oxygen needed for combustion is
supplied by the oxygen in the organic molecules and by suction manifold air.
Additional air is fed as required into the suction side of the blower dis-
charging into the thermal oxidizer.
-------
V-5
Table V-l. Total VOC Controlled Emissions for Integrated Acrylic Acid
and Ester Model Plant Acrylic Acid by Propylene Oxidation,
Esters by Direct Esterification
Source
fiuench-absorber off-gas
Atmospheric pressure
equipment vents
Vacuum equipment vents
Working storage
Tank farm storage
Collected fugitives'1
Oncollected fugitives*
Hand 1 i ng- loading
Secondary
Wastewater
Liquid organic residues
Solid organic residues
Sulfuric acid recovery
Total
Stream
Designation
(Fig. IV-1)
1A
IB, 1C
3A. 3B, 3C
4A, 4B, 4C
5A, SB, 5C
ID, IB, IF, 1G
3D, 3E, 3F
4D, 4E, 4F
5C, 5D, 5E
1H, 2H, 3H, 4H,
5H (from each
processing unit)
1H, 3H, 4H, 5H
(from processing
unit 6)
11, 21, 31, 41,
51, 61
11, 21, 31, 41,
51, 61
1H, 3H, 4H, 5H
(from processing
unit 7)
8K
9K
9K
10K
Control
Device
Thermal oxidizer
Thermal oxidizer
Thermal oxidizer
Thermal oxidizer
Covered floating-
roof tanks
Thermal oxidizer
None
Thermal oxidizer
None
Thermal oxidizer
Solid waste
incinerator
None
Emission
Reduction
(%)
99+a
99+
99+
99+
85°
99+
Nona
99+
None
99+
99+
None
Emission Ratio
(Based on Total Acrylates)
(g/Mg)
934
a
53b
2b
181b
9b
721b
1
42
1247
1
4781
Emission Rat*
(kg/hr)
8.17
0.073
0.46
0.020
1.58
0.063
6.3
0.005
0.363
10.9
b.oi
41.8
69.7
Efficiency of 99+ is calculated as 99.0 although higher efficiencies are possible.
valid only for model plant at capacity; nonlinear or constant with plant capacity.
Based on total VOC emissions for all model plant tank farm storage* 4 tanks have covered floating roofs.
Calculated based on Appendix C as "controlled fugitive losses.1
manifold.
Assumes 50% of fugitive losses are collected in suction
Assumes 50% of controlled fugitive losses cannot be collected in suction manifold.
-------
V-6
The thermal oxidizer runs at essentially constant temperature by supplying
supplementary fuel as natural gas when the VOC in the waste streams
(Streams VIII, IX, and XI on Fig. V-l) falls below that necessary to maintain
the combustion temperature. Also, when VOC surges occur, the supplementary
fuel flow is reduced to lower the combustion temperature and conserve energy.
g. Heat Recovery -- Nearly two-thirds of the heat leaving the combustion chamber
is recovered based on a flue gas calculation in which it is assumed that the
flue gas temperature is 260°C (500°F). Two percent of the heat is assumed to
be lost as radiation from the combustion chamber. The recovered heat is used
elsewhere in the acrylate plant or in other plants in the area and is shown as
Stream XIV on Fig. V-l.
2. Storage - Tank Farm
Floating-roof tanks are used to control storage tanks with 40,000 gal or larger
capacity and for storing materials with vapor pressures greater than 0.5 psig
at storage conditions. Four tanks listed in Table IV-1 are candidates under
3 3
this criterion: the 981.8-m acrylic acid solvent tank, the 8521.0-m EA-BA
solvent tank, the 4396.0-m ethanol tank, and the 6941.0-m ethyl acrylate
tank.
Because of the odor considerations the ethyl acrylate storage tank is a candi-
date for inclusion into the suction manifold and can be routed to the thermal
oxidizer. If the tank farm is in close proximity to the thermal oxidizer, all
tanks may be vented into the suction manifold, providing a second control
device in series, i.e., internal-floating-roof tanks* in series with the ther-
mal oxidizer. These varying levels of control for tank farm storage are shown
in Table E-l in Appendix E. The case of internal-floating-roof tanks alone is
shown as Stream V on Fig. IV-1 as an optional feed to the thermal oxidation
unit but is not included in the thermal oxidizer feed.
*Consist of internal floating covers or covered floating roofs as defined in
API 25-19, 2d ed., 1976 (fixed-roof tanks with internal floating device to
reduce vapor loss).
-------
V-7
3. Fugitive Sources
Controls for fugitive sources, not included in the thermal oxidizer feed, will
be included in a future EPA document that discusses fugitive emissions from the
synthetic organic chemicals manufacturing industry. Emissions from pumps and
valves can be controlled by an appropriate leak-detection system with mechani-
cal seal pumps plus repair and maintenance as needed. Repair of leaks in
acrylic acid and ester plants may already include the techniques necessary for
controlled fugitive emissions. ' Therefore controlled emissions are assumed
on Fig. V-l and Table V-l. Factors used in calculating the controlled fugitive
emissions are presented in Appendix C.
4. Secondary Sources
Secondary emissions caused by wastewater treatment of aqueous wastes in acrylic
acid and ester plants can be significant. The presence of organic compounds
possessing high relative volatilities (compared with water) and/or low aqueous
solubilities can result in emissions much larger than those shown on Table V-l.
Recovery of sulfuric acid can also generate significant organic emissions. The
value shown in Table V-l is based upon the emission rate of a sulfuric acid
recovery unit serving acrylic acid and ester and methyl methacrylate plants.
Control of secondary emissions will be discussed in a future EPA report. No
control system has been identified for the secondary emissions from the model
plant.
R ACRYLIC ACID BY HIGH-PRESSURE MODIFIED REPPE PROCESS
P •
Control devices required by the high-pressure modified Reppe process are shown
on Table V-2. The control technology is different from the propylene oxidation
process since the high-pressure modified Reppe process utilizes the highly
volatile and water-soluble solvent, tetrahydrofuran. It is anticipated that
this process will be replaced by the propylene oxidation process in the early
1980s.
-------
V-8
C. REFERENCES*
1. R. W. Serth, D. R. Tierney, and T. W. Huges, Source Assessment: Acrylic Acid
Manufacture State-of-the-Art (on file at EPA, IERL, Cincinnati, OH) (1978).
2. J. W. Blackburn, IT Enviroscience, Trip Report on Site Visit to Union Carbide
Corp., South Charleston, WV Dec. 8, 1977 (on file at EPA, ESED, Research
Triangle Park, NC).
3. J. W. Blackburn, IT Enviroscience, Trip Report on Site Visit to Rohm and Haas
Co., Deer Park TX, Nov. 1, 1977 (on file at EPA, ESED, Research Triangle Park,
NC).
4. J. W. Nemec and W. Bauer, Jr., "Acrylic Acid and Derivative," pp. 330--354 in
Kirk-Othmer Encyclopedia of Chemical Technology, 3d ed., Wiley, New York, 1978.
5. Nonconfidential information received May 1978 from Celanese Chemical Co.,
Houston, TX (on file at EPA, ESED, Research Triangle Park, NC).
6. Texas State Emission Inventory Questionnaires (1975) for Dow Badische,
Freeport, TX (on file at EPA, ESED, Research Triangle Park, NC).
*Usually, when a reference number is located at the end of a paragraph, it
refers to the entire paragraph. If another reference relates to certain por-
tions of that paragraph, that reference number is indicated on the material
involved. When the reference appears on a heading, it refers to all the text
covered by that heading.
-------
VI-1
VI. IMPACT ANALYSIS
A. CONTROL COST IMPACT
This section presents estimated costs and cost effectiveness data for control
of total VOC emissions resulting from the production of acrylic acid and esters.
Details of the integrated model plant (Fig. IV-1) are given in Sects. Ill and
IV. Cost estimate calculations are included in Appendix D.
Capital cost estimates represent the total investment required to purchase and
install all equipment and material required to provide a complete emission
control system performing as defined for a new plant at a typical location
excluding costs related to the suction manifold. They do not include the cost
of acrylic acid or ester production lost during installation or startup, of
research "and development, or of land acquisition.
Bases for the annual cost estimates for the control alternatives include util-
ities, operating labor, maintenance supplies and labor, recovery credits,
capital charges, and miscellaneous recurring costs such as taxes, insurance,
and administrative overhead. These costs are developed in the thermal oxidizer
control device evaluation. Cost factors used are itemized in Table VI-1.
I Emission Control for Process, Working Storage, Fugitive, Loading, and Liquid
Organic Wastes
Emissions from the acrylic acid, lower-, and heavy-ester plants are combined as
shown on Fig. V-l and fed to a specially designed thermal oxidizer. This unit
receives fumes from the quench-absorber off-gas, combined atmospheric equipment
vents, and combined vacuum equipment vents. A specially designed suction
manifold system collects emissions from working storage tanks and loading areas
and some fugitive sources, combines the contaminated air with fresh air, and
discharges the mixture into the combustion chamber as combustion air. It may
be possible to include tank farm storage emissions in this collection system.
In this report floating-roof tanks are the applicable control method for large
storage tanks and these storage emissions will not be fed to the thermal oxi-
dizer.
-------
VI-2
Table VI-1. Annual Cost Parameters
Operating factor
Operating labor
Fixed costs
Maintenance labor plus
materials, 6%
Capital recovery, 18%
Taxes, insurances,
administration charges, 5%
Utilities
Process water
Electric power
Steam
Natural gas
Heat recovery credits
(equivalent to natural gas)
8760 hr/yrc
$15/man-hr
29% of installed capital cost
$0.07/m ($0.25/thousand gal)
$8.33/GJ ($0.03/kWh)
$5.50/Mg ($2.50/thousand lb or
million Btu)
$1.90/GJ ($2.00/thousand ft3 or
million Btu)
$1.90/GJ ($2.00/million Btu)
Process downtime is normally expected to range from 5 to 15%. If the hourly
rate remains constant, the annual production and annual VOC emissions will be
correspondingly reduced. Control devices will usually operate on the same
cycle as the process. From the standpoint of cost-effectiveness calculation
the error introduced by assuming continuous operation is negligible.
Based on 10-year life and 12% interest.
-------
VI-3
Liquid organic wastes are burned in the thermal oxidizer and supply some fuel
value. Natural gas is used as supplemental fuel. VOC reductions of 99% are
expected for the fumes, the organic collected in the suction manifold, and the
liquid organic wastes.
Capital costs for the liquid-fume thermal oxidation unit for the acrylic acid
and ester model plant depend on the temperature of combustion and on whether it
includes heat recovery. A unit operating at 1400°F will cost $730,000 without
heat recovery and $1,050,000 with heat recovery. A unit operating at 1600°F
will cost $830,000 without heat recovery and $1,270,000 with heat recovery.
Heat recovery is a waste-heat boiler generating 250-psi steam. These values do
not include the cost for the suction manifold system to collect the working
storage, fugitive, and loading emissions. The cost of this system is dependent
on the plant configuration and is difficult to predict.
Figures Vl-1 to VI-3 present capital and net annual costs, as well as cost
effectiveness, for the thermal oxidizer as a function of plant capacity.
Table VI-2 shows the emission-control costs and the cost effectiveness data for
the thermal oxidizer in the acrylic acid and ester model plant.
Costs for internal-floating-roof tanks with contact-type double seals are
o
presented in another EPA report covering storage tanks.
Secondary Emissions
Solid Organic Wastes -- Solid organic wastes generated in the acrylic acid and
esters integrated model plant are burned in an independent solid-waste inciner-
ator with secondary combustion. This unit serves more than just the acrylic
acid and esters plants. Therefore cost analysis of this unit will not be
prepared. Organic reduction efficiency is assumed to be greater than 99%.
Wastewater — The control of emissions from wastewater will be discussed in a
•
future EPA document.
Sulfuric Acid Recovery — Emissions from sulfuric acid recovery can be a sig-
-
nificant fraction of the controlled emissions from the acrylic acid and esters
-------
VI-4
O
o
O
4J
01
o
o
O
tfl
c
H
00
r-
en
^H
•a
•H
s
2000
1000
900
800
700
600
500 -
4OO
20
30
40 50 60 70 80 90 100
200
Plant Capacity (Gg/yr)
(1) Liquid-fume thermal oxidizer with heat recovery.
(2) Liquid-fume thermal oxidizer without heat recovery.
Fig. vi-1. Installed Capital Cost vs. Plant Capacity for
Integrated Model Plant Emission Controls
-------
VI-5
1000
o
o
o
H
X
4J
W
8
4J
0)
z
500
1000
1 1
20 30 40 50 60 80 100
Plant Capacity (Gg/yr)
200
(1) Liquid-fume thermal oxidizer with heat recovery.
(2) Liquid-fume thermal oxidizer without heat recovery.
Fig. VI-2. Net Annual Cost vs. Plant Capacity - Liquid-Fume
Thermal Oxidation
-------
VI-6
tn
w
in
•H
-P
U
0)
+J
in
o
u
100
100
20 30 40 50 60 80 100
Plant Capacity (Gg/yr)
200
(1) Liquid-fume thermal oxidizer with heat recovery
(2) Liquid-fume thermal oxidizer without heat recovery.
Fig. VI-3. Cost Effectiveness vs. Plant Capacity for
Integrated Model Plant Emission Controls
-------
Table VI-2. Emission Control Cost Estimates and Cost Effectiveness for Integrated Acrylic
Acid and Ester Model Plant
Emissions
Sources
b
b
aincludes
Includes
Control Device
or Technique
Thermal oxidizer,
no heat recovery
Thermal oxidizer.
waste-heat boiler
credit for liquid waste
quench-absorber off-gas
_ ^ , Annual Operating Costs
Total
Installed (A)
(B)
Emission
Deduction
(C)
Total VOC
Capital Gross Recovery Net Total VOC Cost Effectiveness
Cost Annual Credit Annual
$ 830,000 $491,000 $ 491,000
1,270,000 643,000 $936,000 (293, 000) C
heat value.
, all combined vents , working storage vents , 50%
(Mg/yr) (%)
7,748 99
7,748 99
of fugitive sources,
(per Mg)
$63
(38) C
all handling
and liquid organic wastes.
c .
Ca\n nrr«2
vents
<
H
i
-------
VI-8
model plant. The process for performing the acid recovery can be of three
types: regeneration through the oxidation of sulfur compounds, vacuum concen-
tration, and atmospheric concentration. Organics entering these processes with
the spent acid accumulate as carbonaceous material in the equipment, are oxi-
dized to CO or CO leave with the aqueous waste streams, or leave with the
uncondensed gases as VOC emissions. Distribution of the organics entering the
different processes for acid recovery may be expected to vary considerably.
Control technology for VOC reduction includes reduction of organics entering
the equipment, optimizing the combustion of organics to CO or CO , and gas
scrubbing or other technologies to remove VOC from the waste gases. Cost
evaluation of these control methods is highly site-specific and dependent on
the acrylic ester process chemistry. Cost evaluation is not included in this
report. No control is specified at this time. Control of emissions from
sulfuric acid recovery processes will be handled as a separate product report.
4. Uncollected Fugitive Sources
Control technology for uncollected (not included in the suction manifold sys-
tem) fugitive emission sources will be discussed in a future EPA document.
5. Other Processes
The high-pressure modified Reppe process for acrylic acid uses a flare to burn
CO and acetylene waste gases from the reaction equipment. The wide use of a
volatile solvent in the process requires condensers for solvent recovery.
The esterification section associated with the high-pressure modified Reppe
process uses condensers and a water scrubber to control organic emissions. The
water scrubber operates on all the noncondensable gases passing through the
vacuum systems required for processing. VOC reduction efficiency for this unit
is reported to be 95%.
B. ENVIRONMENTAL AND ENERGY IMPACTS
Table V-l reflects the environmental impact of reducing VOC emissions by appli-
cation of the described control systems to the model plant.
-------
VI-9
2. Floating-Roof Storage
Storage emission control through the use of floating-roof tanks does not con-
sume energy and has no adverse environmental or energy impacts.
-------
VI-10
C. REFERENCES*
1. J. W. Blackburn, IT Enviroscience, Control Device Evaluation. Thermal Oxidation
(July 1980) (EPA/ESED report. Research Triangle Park, NC).
2. D. G. Erikson, IT Enviroscience, Storage and Handling (September 1980) (EPA/ESED
report, Research Triangle Park, NC).
3. Nonconfidential information received May 1978 from Dow Badische Co., Freeport,
TX (on file at EPA, ESED, Research Triangle Park, NC).
*Usually when a reference is located at the end of a paragraph, it refers to the
entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on a heading, it refers to all the text covered by that
heading.
-------
VII-1
VII. SUMMARY
Acrylic acid and its esters are produced in integrated plants using propylene
oxidation for the acrylic acid and direct esterfication for the lower and heavy
esters. The low-pressure modified Reppe process produces the lower acrylic
esters directly but is being phased out in favor of a new propylene oxidation/
direct esterification plant. One manufacturer continues to use the high-pres-
sure modified Reppe process for acrylic acid but has announced plans to replace
it in the early 1980s with a planned propylene oxidation plant. Total present
acrylates capacity is reported to be 618.4 Gg/yr.
The annual growth of acrylic acid is estimated to range from 9.5 to 11.3%, and
the growth of the acrylate esters is expected to range from 7.1 to 8.4%. New
capacity has been announced for startup in the early 1980s.
Tables IV-14 and V-l list the uncontrolled and controlled emission levels,
respectively, for the model plant. The sizing of the model plant was based upon
the relative consumption of acrylic acid to produce EA, BA, and 2-EHA and
should represent a typical acrylate facility from an emissions standpoint.
Total nationwide uncontrolled emissions for the industry are estimated at
5200 kg/hr, and considering the present level of control, current national
emissions are 520 kg/hr. This is based on an estimated 90% control at existing
plants. The acrylic acid and ester industry practice a high level of organic
emission control since the chemicals they handle possess significant odor and
toxic properties.
The major control device is a liquid-fume thermal oxidizer. If heat recovery
is included, this unit generates significant net levels of energy from waste
combustion. The model plant achieves VOC reduction efficiencies of 99% if the
liquid organic wastes are included in the calculation. Efficiencies of 97.8%
are achieved if only fumes are considered.
Control of storage losses by use of floating-roof tanks have lower reduction
efficiencies and relatively poor cost effectiveness. Combustion of these
storage emissions is an alternative control technique for storage emission
control.
-------
APPE13DIX k
Table A-l. Physical Properties of Acrylic Acid, Ethyl Acrylate, Butyl Acrylate,
2-Ethylhexyl Acrylate, Ethanol, ri-Butanol, and 2-Ethylhexanol
Physical Properties
Organic
Acrylic acidd
Ethyl acrylate
Butyl acrylate
Molecular
Formula
C3H4°2
C5H8°2
C7H12°2
2-Ethylhexyl acrylate cnH20°2
Ethanol
n-Butanol
2-Ethylhexanol
a
As nonomer.
Antoine equation
T. K. Sherwood,
CK. Verschueren,
C6H6°
C4H10°
C8H18°
Molecular
Height
72
100
128
184
46
74
130
: In (vapor pressure in ran Hg) •>
The Properties of Liquids, 3d ed.
Handbook of Environmental Data on
Physical
State*
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
A - [3/(T +
, McGraw-Hill
Vapor
Antoine A
16.5617
16.0890
18.9119
17.2160
15.3614
Pressure Coefficients'3
Antoine B Antoine C'
3319.18
2974.94
3803.98
3137.02
2773.46
C) ] , where T is temperature
, New York. 1977.
Organic Chemicals, Van
Nostrand Reinhold
-80.15
-58.15
23.06f
1.97f
-41.68
-94.43
-140.0
in Kelvin;
, New York,
Boiling
Point
(•C/kPa)
141/1016
43/13. T6
35/1. le
85/1.07®
78.4/101°
117.7/101°
183.5/101°
references :
1977.
Vapor
Specific
Gravity0
2.50
3.50
4.42
6.35
1.60
2.55
4.49
R. C. Reid,
Liquid
Density
(g/ml)
1.045°
(25/4«C)
0.92346
(20/4-C)
0.8998e
(20/4»C)
0.88526
(20/4»C)
0.789°
(20/4»C)
0.810°
(20/4°C)
0.834°
( 20/20 "C)
Water
Solubility
(mg/liter)c
Hiscible
20,000
1,600
M.006
Miscible
77,000
1,000
J. M. Prausnitz,
Melting point of acrylic acid is 13.5°C.
ej. W. Nemec and W. Bauer, Jr., "Acrylic Acid and Derivatives," pp. 330-354 in Kirk-Othmer Encylcopedia of Chemical Technology, 3d ed., Wiley, New York,
1978.
Actual vapor pressures, kPa at 100°C; from footnote e.
-------
B-l
Table B-l. Air-Dispersion Parameters
I. Model plant (uncontrolled)
A. Processing Unit 1
1A
IB, 1C
ID, IB. IF, 1C
1H
B. Processing Unit 2
3H, 4H, 5H
C. Processing Unit 3
3A, 3B, 3C
3D, 3E, 3F
3H
D. Processing Unit 4
4A, 4B, 4C
4D, 4E, 4F
4H
E. Processing Unit S
S-1, SB
5C, SD, 5E
SH
r. Processing Unit 6
1. AA hypothetical
solvent tank
2. AA tank
3. EA-BA hypothe-
tical solvent
tank
4. Ethanol tank
5. EA tank
6. Butanol tank
7. BA tank
8. 2-EHA hypothe-
tical solvent
tank
9. 2-Ethylhexanol
10. 2-EHA
G. Processing Unit 7
loading losses
Drum loading
Tank car/tank truck
Barge
H. Secondary
Haste-water treatment
Solid organic wastes
Sulfuric acid recovery
II. Model plant (controlled)
A. Liquid- ftrnw thermal
oxidiser flue gas
B. Processing Unit 6d
1. AA hypothetical
solvent tank
2. EA-BA hypothe-
tical solvent
tank
3. Ethanol tank
4. EA tank
Number
of
Sources
1
2
4
b
3
3
b
3
3
b
2
3
b
1
4
1
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
1
1
1
voc
Emission Tank Tank Stack stack Discharge Flov
Rate Height Diameter Height Diameter Temperature Rate
(g/sec) (m) (m) (m) (») (K) (nV»ec)
227 IS 0.82 293 7.98
0.28* 15 0.15 293 0.25
7.20* 15 0.048 293 0.028
0.120* b
0.018* 293
0.67* 15 0.032 293 0.012
.4.68* IS 0.083 293 0.083
0.241* b
0.075* IS 0.012 293 0.002
0.531* 15 0.031 293 0.012
0.116* b
1.01* 15 0.020 293 0.005
O.S25* 15 0.019 293 0.004
0.001* b
0.143 12.19 10.13
0.007* 7.31 4.74
2.108 12.19 29.84
0.117 12.19 21.43
0.431 12.19 26.93
0.025 12.19 17.47
0.075 12.19 20.12
0.017 2.44 1.67
0.001 12.19 12.94
0.001* 9.75 7.26
0.014 10 0.051 Ambient
.0.008 3 0.051 Ambient
0.041 3 O.OS1 Ambient
0.101 1 320 Ambient
0.033 10 1 533
11.61 IS 1 353
5.47 IS 1.15 533 IS. 9
0.022 12.19 10.13
0.316 12.19 29.84
0.018 12.19 21.43
0.06S 12.19 26.93
Discharge
Velocity
(n/sec)
15.2
15.2
15.2
IS. 2
15.2
15.2
15.2
IS. 2
15.2
IS, 2
All sources.
See Table IV-1.
cOther tank emissions are uncontrolled.
-------
C-l
APPENDIX C
FUGITIVE EMISSION FACTORS*
The Environmental Protection Agency recently completed an extensive testing program
that resulted in updated fugitive-emission factors for petroleum refineries. Other
preliminary test results suggest that fugitive emissions from sources in chemical
plants are comparable to fugitive emissions from corresponding sources in petroleum
refineries. Therefore, the emission factors established for refineries are used in
this report to estimate fugitive emissions from organic chemical manufacture. These
factors are presented below:
Source
Uncontrolled
Emission Factor
(kg/hr)
Controlled
Emission Factor'
(kg/hr)
Pump seals
Light-liquid service
Heavy-liquid service
Pipeline valves
Gas/vapor service
Light-liquid service
Heavy-liquid service
Safety/relief valves
Gas/vapor service
Light-liquid service
Heavy-liquid service
Compressor seals
Flanges
Drains
0.12
0.02
0.021
0.010
0.0003
0.16
0.006
0.009
0.44
0.00026
0.032
0.03
0.02
0.002
0.003
0.0003
0.061
0.006
0.009
0.11
0.00026
0.019
Based on monthly inspection of selected equipment; no inspection of
heavy-liquid equipment, flanges, or light-liquid relief valves; 10,000
ppmv VOC concentration at source defines a leak; and 15 days allowed
for correction of leaks.
Light liquid means any liquid more volatile than kerosene.
*padian Corp., Emission Factors and Frequency of Leak Occurrence for Fittings
-in Refinery Process Units. EPA 600/2-79-044 (February 1979).
-------
D-l
COST ESTIMATE SAMPLE CALCULATIONS
A. COST ESTIMATE DETAILS
This appendix contains sample calculations showing how the costs presented in
this report were estimated.
The accuracy of an estimate is a function of the degree of data available when
the estimate was made. Figure D-l illustrates this relationship. The contin-
gency allowance indicated is included in the estimated costs to cover the un-
defined scope of the project.
Capital costs given in this report are based on a screening study, as indicated
by Fig. D-l, based on general design criteria, block flowsheets, approximate
material balances, and data on general equipment requirements. These costs
have an accuracy range of +30% to -23%, depending on the reliability of the
data, and provide an acceptable basis to determine the most cost-effective
alternative within the limits of accuracy indicated.
B. THERMAL-OXIDIZER-CONTROLLING INTEGRATED PLANT EMISSIONS
The emissions from the integrated acrylic acid and ester model plant were
estimated to be 17,200 scfm with a heat content (including CO level) of just
under 47 Btu/scf. A heat content of 50 Btu/scf was therefore assumed. Since
the emissions contained over 2 vol% CO, the following combustion conditions
were chosen. The combustion temperature was 1600°F, and the residue time was
0.75 sec. Figure V-4 in the Control Device Evaluation^ Thermal Oxidation
report was used to estimate the capital costs of the thermal oxidizer with no
heat recovery and the thermal oxidizer using a 250-psi steam waste-heat boiler.
Then annual costs were developed by using the table on p. B-22 of Appendix B in
the cited report. Annual costs were developed for the model plant as shown in
the following calculation for the heat recovery case:
1J. W. Blackburn, IT Enviroscience, Control Device Evaluation. Thermal Oxidation
(July 1980) (EPA/ESED report, Research Triangle Park, NC).
-------
INFORMATION USED BY ESTIMATOR
. PROS.
CO«>T
5ST7MATTE.D COST
'•"WITH ALLOWANCE
MA3.PROB.
APPRO*. COST
EUG,R.4 E
-------
D-3
Fixed Costs:
Utilities:
Manpower:
Recovery Credit:
$1,270,000 X 0.29
17,200 scfm
5,000 scfm
x $169,000
17,200 scfm
5,000 scfm
x $272,000
$368,000
$581,000
$ 36,000
$936,000
In addition, there is a fuel credit for burning waste organic liquids in the
thermal oxidizer. It is estimated that the heat value of this source is
19.5 M Btu/hr. At $2.00/million Btu, then, this lowers the utility cost by
$342,000 annually. The net annual savings therefore are as follows:
Fixed costs
Utilities
Manpower
Recovery credit
$368,000
239,000
36,000
-936,000
-$293,000
From Table VI-2 of this report:
Emission reduction
Cost effectiveness
7748 Mg of VOC/yr
-293,000 _
7748
= $38 saved/Mg of VOC
-------
E-l
EXISTING PLANT CONSIDERATIONS
I. EXISTING PLANT CHARACTERIZATION
Table E-l lists emission control devices reported to be in use by industry. To
gather information for this report two site visits were made to acrylic acid
and esters manufacturers. Trip reports have been cleared by the companies con-
cerned and are on file at EPA, ESED, in Durham, NC. ' EPA also has received
letters in response to requests for information on air emissions from acrylic
acid and esters plants. Some of the pertinent information concerning process
emissions from existing acrylic and acid esters facilities is presented in
this appendix.
A- UNION CARBIDE - TAFT, LA
The capacities for the UCC acrylates facilities are about 200 million Ib/yr of
acrolein, acrylic acid, and esters. Acrylic acid comprises 130 million Ib/yr
of this total. Ethyl aerylate capacity is 90 million Ib/yr. Total heavy ester
capacities (such as 2-ethylhexyl acrylate) are 110 million Ib/yr. UCC considers
butyl acrylate to be a heavy ester.
The facility was originally built in 1969 and utilized British Petroleum tech-
nology for acrylic acid production. In 1976 the plant was converted to tech-
nology obtained under license from SOHIO.
!- Acrylic Acid
a- Process Emissions — The various process emissions are described below:
Quench absorber and acrolein distillation off-gas — The off-gas stream con-
taining unreacted oxygen, nitrogen, and organics is combined with emissions
from the acrolein distillation and routed to a thermal oxidizer that UCC calls
a "combuster" or "buster." Vent streams from the acrolein process also are
sent to this device, as is the feed. Sampled data do not exist, but have been
calculated based on reliable UCC pilot studies. The predicted design loading
on the combuster before its installation in 1975 was 4835 Ib/hr of volatile
organic compounds (VOC), not including methane. A conservative estimate of the
-------
Table E-l. Control Devices Currently Used by the Domestic Acrylic Acid and Esters Industry
Company
Celanese
Clear Lake, TX
Pampa , TX
Dow Badische
Freeport, TX
Rohm and Haas
Deer Park. TX
Union Carbide
Taft, LA
Quench-Absorber
Off-Gas
Thermal
oxidizer
b
c
Thermal
oxidizer
Thermal
oxidizer
Emission Points
Atmospheric Vacuum
Equipment Equipment Storage
Vents Vents Working Tank Farm Fugitive
Thermal Thermal Thermal Thermal Thermal
oxidizer oxidizer oxidizer oxidizer oxidizer
N.D. N.D. N.D. Collected N.D.
and flared
Flares, condensers, scrubbers Vapor N.D.
scrubbers
Thermal Thermal Thermal Thermal Thermal
oxidizer oxidizer oxidizer oxidizer6 oxidizer
Flare " Flare6 Floating roof, None
blanketing gas, vapor
recovery, conservation
vents , flare
Secondary
Liquid Solid Sulfuric
Handling- Organic Organic Acid
Loading Wastewater Residues Residues Recovery
Thermal Thermal Thermal Solids N.D.a
oxidizer oxidizer oxidizer incinerator
Vapor N.D. N.D. N.D. N.D.
recovery
Vapor N.D. Incinerator N.D. N.D.
recovery
Dedicated Thermal Thermal Landfill None
fume in- oxidizer oxidizer
cinerator
Dedicated None Thermal Solids N.D.
catalytic incinerator
incinerator
N.D. « No data.
Acrylic acid not manufactured.
cPropylene oxidation not used.
dOsed on some tetrahydrofuran and acrylic acid tanks. Most tanks have no control.'
eSome fumes only.
-------
E-3
resulting flue gas from this device yields the following organic emissions
based on capacity operation: VOC, 37 lb/hr; CO, 64 lb/hr; and NO , 60 Ib/hr.
X
UCC personnel estimate that two-thirds of this organic loading is attributable
to acrylic acid production and that the rest results from acrolein production.
This stream will vary directly with the production rate.
Feed to flare (including raffinate stripper vent -- This is a continuous stream
comprising the primary feed to a flare. Acrolein process vents and extraction
system vents are also included. The total flow rate of this stream is 60,000
Ib/day, and an estimate of the composition is shown below. This stream will
vary independently with production rate since it is largely made of nitrogen
blankets or purges.
Component Amount (wt %)
VOC 0.006
C02 18.59
N2 81.11
CO 0.25
CH4 0.002
Extract distillation vent -- Several vents from vacuum distillation equipment
are combined as this stream. Nitrogen is bled into this equipment to prevent
oxidation and to control vacuum. A makeshift water scrubber (old piece of pipe)
has been installed on the stream and the off-gas from the scrubber has been
measured. The temperature of the stream is 113°F, and the flow rate is
0.011 Ib of gas/lb of acrylic acid produced at capacity. Acrylic acid capacity
is 130 million Ib/yr. This emission rate varies independently with plant pro-
duction since the stream is vented from vacuum equipment. The composition of
the stream is given below:
-------
E-4
Component Amount (wt %)
Hydrocarbon solvent 34.15
Acrylic acid 0.03
CO 1.19
°2 X'12
N2 63.51
Foreruns distillation vent — Acetic acid is distilled in several vacuum stills,
where nitrogen is added to control vacuum and to prevent oxidation. The
measured flow rate for this stream is 0.0073 Ib of gas/lb of acrylic acid pro-
duced at capacity. This emission varies independently with production since
the stream is vented from vacuum equipment. The composition data are given
below:
Component Amount (wt %)
Hydrocarbon solvent 9.64
Acrylic acid 0.03
02 0.88
N 89.31
HO 0.14
Acrylic acid distillation vent — Acrylic acid is distilled in vacuum equipment
into which nitrogen is bled to control vacuum and to prevent oxidation. The
measured flow rate is 0.0040 Ib of gas/lb of acrylic acid produced at capacity.
This emission varies independently with production since the stream is vented
from vacuum equipment. Its composition is given below:
Component Amount (wt %)
Hydrocarbon solvent 0.84
CO 0.16
0 3.45
HO 0.68
N_ 94.87
-------
E-5
Shutdown related emissions -- The acrylic acid process requires shutdown at
varying intervals from 4 to 12 times a year. Organics are flushed from the
system and are then recovered. Nitrogen is introduced during filling and
emptying procedures. When vacuum equipment is placed under vacuum, UCC person-
nel anticipate no VOC in the vented nitrogen.
b. Secondary Emissions — Two secondary emission sources result in acrylic acid
manufacture. The first is the polymeric residues removed periodically from the
stills and equipment. Generation of this polymer is undesirable, and much care
is taken to prevent it. Still, up to 50 fiberpacks a year of material are
estimated to be removed from the equipment by hand and burned in an incinera-
tor. UCC assumes complete combustion.
The second emission is a result of heat transfer equipment at Taft. The emis-
sions from the two vents involved are shown below. The flow from vent 1 is
0.00045 Ib of VOC per pound of AA produced; the flow from vent 2 is not given.
Component
VOC
N2
CO
co
Amount
Vent 1
31.0
54.0
15.0
None
None
None
None
(wt %)
Vent 2
None
None
75.17
0.12
3.22
0.01
21.48
Fugitive Emissions -- Much of the equipment in this process is under vacuum.
Therefore emissions from seals may be much lower than those from systems at or
above atmospheric pressure. All but ten pumps are on vacuum service. Pumps in
this equipment can still be under positive pressure even though the equipment
is under vacuum.
The amount of cooling water used for acrylic acid and acrylates production is
shown below:
-------
E-6
Amount
(M gal/day)
Acrylic acid 54.4
Ethyl acrylate 8.7
Heavy acrylate 5.8
The following discussion is taken from a packet submitted to EPA by UCC on
March 17, 1978.
"Organic contamination in the cooling water system is
detected by total carbon analysis. These analyses are
performed daily on 24-hour composited samples of cooling
water entering and leaving a process unit. If the outlet
total carbon concentration exceeds the inlet, additional
cooling water samples are taken from within the unit and
analyzed to determine the source of contamination. The
necessary corrective action is then taken to eliminate the
source of contamination."
Wastewater generated in acrylic acid and ester production is sent by closed
pipe to a primary treatment plant (including oil skimming), then to an equali-
zation pond, and finally to a UNOX waste treatment plant.
d. Handling Emissions -- Acrylic acid and esters are handled by drumming, tank car
loading, and tank truck loading (see Table E-2).
e. Emission Control Devices -- Two major emission control devices are used in
acrylic acid and acrylate ester manufacture: thermal oxidizers and flares.
Thermal oxidizer (combuster) — A thermal oxidizer or combuster was installed
in 1975 to destroy acrylic acid and acrolein vapors. This unit was constructed
by John Zinc and incorporates a heat recovery unit to produce process steam at
600 psig. When or if the combuster goes down, the acrylic acid plant also goes
down.
-------
E-7
Table E-2. Control Devices - Product Handling
Air Emission Control Equipment
Acrylic Acid Acrylates
Drumming Catalytic oxidation3 None
Tank car loading Submerged fill pipe Scrubbing0 (99% eff.)
Tank truck loading Submerged fill pipe Scrubbing0 (99% eff.)
Approximately 10% of the acrylic acid is drummed at the No. 2
Drumming Building, which utilizes catalytic oxidation to destroy
organic vapors coming from the operation. Approximately 90% of
the acrylic acid is drummed at the No. 3 Drumming Building, which
is equipped with vent hoods to remove organic vapors from the work
place. The hoods are vented to the atmosphere.
Acrylate vapors are not scrubbed at the drumming facilities but
are pulled up through vent hoods to remove them from the work
place. The hoods are vented to the atmosphere.
Contaminated water, spills, and hose and pipeline washings are
collected in a chemical sump at each loading facility. The
collected wastes are pumped to a waste treatment plant that has
primary and secondary waste-treatment facilities.
The unit operates at a relatively constant feed input and supplements the vary-
ing flow and fuel value of the streams fed to it with inversely varying amounts
of fuel gas. Fuel-gas consumption averages 52.8 million Btu/hr instead of the
designed level of 36 to 51 million Btu/hr. The unit is run with 9% excess oxy-
gen instead of the designed 3 to 5% excess oxygen.
The propylene used in the acrylic acid oxidation contains about 2% propane,
which acts as an inert gas in the acrylic acid process and enters the incinera-
tor in the waste gas. With the planned startup of a new olefins plant the pro-
pane concentration in the propylene should double to 4%, thus achieving an oxi-
dation feed of 4% propane and therefore the conditions for which the conibuster
was designed.
Materials of construction of a nonreturn block valve in the 600-psig steam line
from the boiler section requires that the incinerator be operated at 650°C
instead of the designed 980°C. Residence time is 3 to 4 sec.
-------
E-8
The capital cost of this unit was $3 million in 1976. Operating costs exclud-
ing capital depreciation are reported to be $287,000/year (1976).
Flare -- Before the combuster was installed, the acrolein-containing streams
were routed to a flare. This unit still operates on streams from acrolein
production and acrylic acid production. Acrolein streams routed to the flare
include the acrolein distillation column, the acrolein unit tanks, and dis-
charges from the acrolein unit safety valves. Acrylic acid streams vented to
the flare include the acrylic acid extractor vent, the raffinate stripping
column vent, and the field acrolein tank safety-valve discharges. The vent
header from the acrolein production area can be routed to the combuster. How-
ever, the other header from the acrylic acid area can be routed only to the
flare.
2. Ethyl Aerylate
a. Process Emissions -- The three major process-related emissions involved in the
production of ethyl acrylate are described below:
Ester extraction vents — The flow rate for this stream is 0.012 Ib of gas/lb
of ethyl acrylate produced, and the annual ethyl acrylate capacity is 90 mil-
lion Ib/year. The measured composition of the stream is as follows:
Component Amount (wt %)
Denaturant 0.19
Ethyl acrylate 2.43
Ethyl ether 0.20
Ethanol 1.7
02 13.0
N2 79.57
H20 1.09
CH4 1.82
Ester refining vents -- This stream is the discharge from vacuum systems sup-
plying vacuum to the refining equipment. The flow rate is 0.083 Ib of gas/lb
of ethyl acrylate produced. The composition is shown below:
-------
E-9
Component Amount (wt %)
Ethyl acrylate 0.74
Denaturant 1.55
Ethyl ether 2.02
Ethanol 0.18
°2 2'94
N 91.65
H0 0.92
b. Shutdown-Related Emissions — This system requires shutdown from 12 to 24 times
a year. Nitrogen is introduced to the equipment during emptying and filling,
and care is taken to prevent the emission of organics to the sewer or air.
This system does not require as much polymer cleanout as acrylic acid equip-
ment. Cleanout is normally done in preparation for idle standby.
c- Secondary Emissions — Secondary emissions are generated by incineration of
about three fiberpacks of polymer a year and of the wastewater from the extrac-
tion and refining steps. About 12 times a year 20,000 Ib of water soluble
organic is wasted. Most is incinerated but some is sent to wastewater treat-
ment. Other wastewater is sent to the wastewater treatment facilities des-
cribed in Sect. I-A.l.c.
^- Fugitive Emissions -- The data on pumps, valves, and seals are discussed in
Sect. E-I.A.l.c. Cooling water usage is shown in Sect. E-I.A.l.c.
e. Handling Emissions -- Handling emissions are discussed in Sect. E-I.A.l.d; data
on control devices are given in Table E-2.
f. Control Devices -- The process vents described for ester production emit
directly to the atmosphere.
-------
E-10
3. Heavy Ester
a. Process Emissions — Heavy-ester production includes butyl and 2-ethylhexyl
acrylates. About 110 million Ib of heavy esters are produced annually at
capacity. Data on the two sources of process emissions — reactor vents and
refining vents — are given below:
Reactor vents -- The flow of the stream leaving the reactors is 0.029 Ib of
gas/lb of heavy ester produced. The composition is as follows:
Component Amount (wt %)
Hydrocarbon solvents 13.96
Ethyl ether 1.60
Light boiler 1.28
C02 0.14
Ar 0.26
02 6.40
N2 75.78
H20 0.47
CH4 0.11
Refining vents -- The flow of this stream is 0.0128 Ib of gas/lb of heavy ester
produced, and the composition is the following:
Component Amount (wt %)
Several light-organic
unknowns 9.74
Ar 0.61
02 11.36
N2 77.48
H20 0.61
b. Secondary Emissions -- Aqueous wastes and incinerable residues are generated in
this process.
-------
E-ll
c. Fugitive Emissions — Data on fugitive emissions are the same as those given in
Sect. E-I.A.I.e. The amount of cooling water used is also given in that sec-
tion.
d. Handling Emissions — Handling emissions are discussed in Sect. E-I.A.l.d.
Data on control devices are given in Table E-2.
e. Control Devices -- Process vents emit directly to the atmosphere.
B. ROHM AND HAAS - DEER PARK, TX
Acrylic esters are produced from propylene, air, and alcohols, with acrylic
acid being produced as an intermediate. Acrylic acid is produced directly from
propylene by a vapor-phase catalytic air-oxidation process. The reactions take
place in two steps, both in the presence of steam as a diluent. Propylene is
first oxidized to acrolein, which is then oxidized to acrylic acid.
A small amount of acetic acid is produced as a by-product. The reactions take
place in fixed-bed multitubed reactors that operate at high temperatures and
atmospheric pressure. The heat of reaction is removed through indirect heat
exchangers, with a cooling medium in the shell side of the reactors. This heat
is then converted to steam in a boiler. There are two trains for the reaction
step. Reactor effluent gas is sent to absorbers, where acrylic acid is
recovered in an aqueous solution. The acrylic acid is then extracted from the
aqueous stream in an extraction system common to both trains. Acrylic acid
suitable for esterification with the desired alcohol is available after solvent
recovery. Butyl, ethyl, and methyl esters are produced in a liquid-phase reac-
tion using a catalyst. The reaction product is purified in subsequent refining
operations. Excess alcohol is recovered and heavy-end by-products are
incinerated.
Five emission sources are generated in this process. The first actually
consists of two separate, closely grouped stacks having the same effluent
composition. There is one stack for each of two startup heaters, each sized to
produce about the same gas exit velocity. These heaters are used to heat the
reactor cooling medium for startup and maintain coolant temperatures during
temporary shutdowns. The normal period for continuous startup-heater operation
-------
E-12
is about three days, and startups may occur several times per year. Shutdowns
of a reaction train during normal operation may occur as often as once or twice
a week for as long as a few hours or up to a day. The fuel source will be
natural gas. Enough air will be added to produce 6 vol % 0. in the stack
effluent. Complete combustion is assumed, with the only pollutant being NO .
X
The nominal stack height and diameter have been selected that will produce the
ground level concentration (GLC) for NO. The threshold limit value (TLV) for
NO is 25 ppm.
The second emission point is the waste incinerator stack. The waste incinera-
tor is designed to burn the off-gas from the two absorbers. In addition all
process vents (from extractors, vent condensers, and tanks) that might be a
potential source of gaseous emissions will be collected in a suction vent sys-
tem and will normally be sent to the incinerator. An organic liquid stream
generated in the process will also be burned, thereby providing part of the
fuel requirement. A separate natural-gas line will supply the remainder. Air
will be added to an amount to produce about 6% 0- in the effluent. NO and a
£> X
very small quantity of unburned hydrocarbon (1.75 Ib/hr) are the only antici-
pated contaminants.
The third emission point is the suction vent gas (SVG) flare, which will be
used only to incinerate the collected suction vent gases during waste incinera-
tor maintenance shutdowns and during severe process upsets. NO is the only
A
anticipated contaminant, as the flare will be of a smokeless design.
The fourth emission point is the absorber off-gas (AOG) flare. This will also
be used only when the incinerator is shut down for maintenance. The only an-
ticipated contaminant is NO .
The fifth emission source consists of the vents from five storage tanks.
Table E-3 summarizes emission information given by Rohm and Haas.
CELANESE -- CLEAR LAKE, TX
The Clear Lake Plant of Celanese supplied the information given in Tables E-4,
E-5, and E-6 in response to an EPA information request.
-------
E-13
Table E-3. Emission Data from Rohm and Haas
Emission Rate (Ib/hr)
Emission
Source VOC NOX
Startup heaters 25
Waste incineration stack 50
Suction vent gas flare 2.02
Absorber off-gas flare None Some; quantity not reported
Storage tank 47
-------
Table E-4. Acrylic Acid/Acrylate Ester Emission Factors
Acrylic Acid Plant
(lb/1000 Ib of Acrylic Acid)
Component
Acetaldehyde
Acetic acid
Acetone
Acrolein
Acrylic acid
Ethyl acrylate
Quench Absorber
Off-Gas
<0.1
1.4
1.3
4.5
18.0
1.2
Combined Ethyl Acrylate Combined Processing Butyl Acrylate Combined Processing
Processing (lb/1000 Ib of Ethyl Acrylate) (lb/1000 Ib of Butyl Acrylate)
0.9
Butyl acrylate
Butanol
Water 88.6 0.1
Carbon dioxide 269.5
Carbon monoxide 118.5
Nitrogen 4,466.6 29.7
Oxygen 128.8 8.8
Propane 75.3
Propylene 17.5
Air
Ethane
Total 5,191.2 39.5
Operating temperature, 80°F.
Operating temperature, 120°F.
CHydrocarbons calculated as etViane.
0.4
.0.4
1.9
M
l
2.1
10.3
2.7
42.5
57.6
19.2
21.9
-------
E-15
Table E-5. Composition of Other Waste-Gas Streams
Component
Nitrogen
Oxygen
Acrylic acid
Ethyl acrylate
Butyl acrylate
Composition
Tank Farm
a
and Handling
368
Unknown
Unknown
Unknown
db/hr)
Tank Car Wash
158
Unknown
Unknown
Unknown
Ventilation Feed
126,900
33,700
Unknown
Operating temperature, 70 to 90°F.
Operating temperature, 90°F.
-------
E-16
Table E-6. Composition of Incinerator Flue Gas
Component
Volume
(mole %)
Oxygen
Carbon dioxide
Carbon monoxide
Nitrogen
Argon
Methane
Ethane plus
Hydrogen sulfide
Sulfur dioxide
Caronyl sulfide
Carbon disulfide
Nitrogen oxides
13.25
2.28
<0.001
83.51
0.81
0.1350
<0.001
<0.0021
0.0150
<0.0017
<0.0017
<0.0028
-------
E-17
DOW-BADISCHE, FREEPORT, TX
The Dow-Badische process is completely different from the processes used by the
other three manufacturers in that the high-pressure modified Reppe process is
used to make acrylic acid and direct esterification is used to make the esters.
It is planned to shut down the plant and to start up a propylene oxidation in
its place in 1981.
The emissions are reported to be the following. The absorber and reactor vent
gas is fed to a flare, and the stream typically has a total flow of 187 Ib/hr,
composed of the following: CO, 164.5 lb/hr; C H 15 lb/hr; C2H4, 3.0 Ib/hr ,-
N9, 3.0 Ib/hr; and CO,, 1.5 Ib/hr. The temperature is 13°C. 99% efficiency is
£• £•
claimed for the flare. Vacuum-jet emissions are given as 92% air and 8% water
for two sources and 77% air and 23% water for the third source. The flows are
8 scfm for the first two sources and 26 scfm for the third source. A fugitive
loss of 15 tons/yr of tetrahydrofuran is given. None of these emissions are
controlled.
wastewater comes from miscellaneous intermittent sources throughout the plants.
Organics are primarily THF and acrylic acid, which are volatile and are
disposed of through a biological treatment plant. Concentrations are 100 to
20 ppm. Organic residues are from distillation bottoms. These nonvolatile
residues are incinerated on-site or are disposed of by contract.
The acrylic esters process has process emissions arising from vacuum processes.
The emissions are scrubbed in a water scrubber prior to release. No organics
are shown to be emitted. The flow of this stream is 1450 scfm. Storage tanks
also are emission sources; however, no data are given.
Liquid wastes from the esters plant also include a distillation bottom stream,
which is disposed of by incineration. Wastewater has an organic carbon concen-
tration of 1500 to 2000 ppm (mostly butyl and 2-ethyl-hexyl acrylate) and
represents about 1 Ib/min of TOC.
-------
E-18
II. RETROFITTING CONTROLS
The primary difficulty associated with retrofitting may be in finding space to
fit the control device into the existing plant layout. Because of the costs
associated with this difficulty it may be appreciably more expensive to retro-
fit emission control systems in existing plants than to install a control sys-
tem during construction of a new plant. Because of the high level of control
already exhibited by acrylic acid and ester manufacturers, it is not
anticipated that retrofitting major thermal oxidizers will be necessary.
-------
E-19
III. REFERENCES*
3-
4-
J. W. Blackburn, IT Enviroscience, Trip Report on Site Visit to Union Carbide,
South Charleston, WV Dec. 8, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
J. W. Blackburn, IT Enviroscience, Trip Report on Site Visit to Rohm and Haas
Co., Deer Park, TX, Nov. 1, 1977 (on file at EPA, ESED, Research Triangle Park,
NC) .
Letter dated Apr. 21, 1978, from C. R. DeRose, Celanese Chemical Co., to Leslie
Evans, EPA (on file at EPA, ESED, Research Triangle Park, NC).
Letter dated May 12, 1978, from R. R. Ray, III, Dow-Badisch Co., to D. R.
Goodwin, EPA (on file at EPA, ESED, Research Triangle Park, NC).
^Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on a heading, it refers to all the text covered by that
heading.
-------
5-i
REPORT 5
METHYL METHACRYLATE
J. W. Blackburn
H. S. Basdekis
IT Enviroscience
9041 Executive Park Drive
Knoxville, Tennessee 37923
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
October 1980
This report.contains certain information which has been extracted from the
Chemical Economics- Handbook, Stanford Research Institute. Wherever used, it
has been so noted. The proprietary data rights which reside with Stanford
Research Institute must be recognized with any use of this material.
D15Q
-------
5-iii
CONTENTS OF REPORT 5
Page
ABBREVIATIONS AND CONVERSION FACTORS 1-1
INDUSTRY DESCRIPTION II-1
A. Reason for Selection II-l
B. Usage and Growth II-l
C. Domestic Producers II-2
D. References II-5
PROCESS DESCRIPTION III-l
A. Introduction III-l
B. Acetone Cyanohydrin from Acetone and Hydrogen Cyanide III-l
C. Methyl Methacrylate from Acetone Cyanohydrin III-3
D. Future Process III-7
E. References III-8
EMISSIONS AND APPLICABLE CONTROL SYSTEMS IV-1
A. General IV-1
B. Acetone Cyanohydrin Process IV-1
C. Methyl Methacrylate Process IV-4
D. Estimated Emissions for the Industry IV-5
E. References IV-7
APPENDICES OF'REPORT 5
Page
A. PHYSICAL PROPERTIES OF ACETONE CYANOHYDRIN AND A-l
METHYL METHACRYLATE
-------
5-v
TABLES OF REPORT 5
Number Page
H-l Methyl Methacrylate Capacity II-3
IV-1 Uncontrolled and Controlled VOC Emissions from Production of IV-2
Acetone Cyanohydrin
IV-2 Uncontrolled and Controlled VOC Emissions from Production of IV-3
Methyl Methacrylate
A-l Physical Properties of Acetone Cyanohydrin A-1
A~2 Physical Properties of Methyl Methacrylate A_2
FIGUKES OF REPORT 5
Number Page
IJ~1 Locations of Plants Manufacturing Methyl Methacrylate II-4
Hl-1 Flow Diagram for the Manufacture of Acetone Cyanohydrin III-2
2 Flow Diagram for the Manufacture of Methyl Methacrylate from III-4
Acetone Cyanohydrin
-------
1-1
ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements used in agency documents in metric
units. Listed below are the International System of Units (SI) abbreviations
and conversion factors for this report.
To Convert From
Pascal (Pa)
Joule (J)
Degree Celsius (°C)
Meter (m)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter/second
(m3/s)
Watt .(W)
Meter (m)
Pascal (Pa)
Kilogram (kg)
Joule (J)
To
Atmosphere (760 mm Hg)
British thermal unit (Btu)
Degree Fahrenheit (°F)
Feet (ft)
Cubic feet (ft3)
Barrel (oil) (bbl)
Gallon (U.S. liquid) (gal)
Gallon (U.S. liquid)/min
(gpm)
Horsepower (electric) (hp)
Inch (in.)
Pound-force/inch2 (psi)
Pound-mass (Ib)
Watt-hour (Wh)
Standard Conditions
68°F = 20°C
1 atmosphere = 101,325 Pascals
PREFIXES
Multiply By
9.870 X 10~6
9.480 X 10~4
(°C X 9/5) + 32
3.28
3.531 X 101
6.290
2.643 X 102
1.585 X 104
1.340 X 10"3
3.937 X 101
1.450 X 10"4
2.205
2.778 X 10"4
Prefix
T
G
M
k
m
M
Symbol
tera
giga
mega
kilo
milli
micro
Multiplication
Factor
1012
109
106
103
10~3
10"6
Example
1
1
1
1
1
1
Tg =
Gg =
Hg =
km =
mV =
H9 =
1
1
1
1
1
1
X
X
X
X
X
X
1012
109
106
103
10"3
io"6
grams
grams
grams
meters
volt
gram
-------
II-l
II. INDUSTRY DESCRIPTION
A- REASON FOR SELECTION
Methyl methacrylate (MMA) production was selected for study because preliminary
estimates indicated that total emissions of volatile organic compounds (VOC)
were high and that production growth was anticipated to be high in the period
between 1978 and 1982. However, as is discussed below, expansions of two plants
increased the capacity of MMA beyond the present demand. Acetone cyanohydrin
(ACN) is also included in this study because it is used primarily for the produc-
tion of MMA. Hydrogen cyanide (HCN) is used for the production of ACN and is
produced on-site; however, it is not included in this product report since it is
also produced for the manufacture of other organic chemicals and will be considered
as a separate organic chemical. Recent literature1 indicates that future manu-
facture of MMA will be by another process (see Sect. III-D). MMA and ACN are
liquids at ambient conditions. Their pertinent physical properties are given in
Appendix A.
B- USAGE AND GROWTH
All the MMA produced domestically is manufactured from ACN; other products produced
from ACN are methacrylic acid and its higher esters. Data on the breakdown of
ACN to each of these chemicals are not available. However, one source estimates
that between 1966 and 1969 only about 20% of ACN was used to manufacture methacrylic
acid and its higher esters and that the remainder was used for MMA production.2
Approximately 1 kg of ACN is required to produce 1 kg of MMA.2
Methyl methacrylate is used as a monomer for plastics generically referred to as
acrylics. The major uses of acrylic polymers include acrylic sheet, surface
coating resins, molding and extrustion powders, and emulsion polymers for adhesive,
leather, paper, polish, sealant, and textile applications.3
Expansions occurred in 1977 that increased the current overall capacity for MMA
to 511 Gg/yr. The demand for MMA for 1978 was projected to be 370 Gg/yr and is
expected to increase at an average rate of 7 to 8% from 1978 to 1982. If this
occurs, the production operating rate will be 84% of current capacity in 1980.3
-------
II-2
C. DOMESTIC PRODUCERS
Currently there are three domestic producers manufacturing ACN and MMA at four
plants.- CY/RO, Du Pont, and Rohm & Haas. They all start with acetone and hydro-
gen cyanide to produce ACN and react the ACN with sulfuric acid and methanol to
produce MMA. Table II-l lists the MMA producers, location, and production capaci-
ties; Fig. II-l shows the locations of the plants.
All three MMA producers have captive supplies of hydrogen cyanide and sulfuric
acid. Du Pont also has captive supplies of methanol. None of the companies
produce acetone.4
Approximately 75% of MMA production in 1975 was consumed captively. American
Cyanamid (CY/RO) uses MMA captively for cast acrylic sheets and polymethacrylate
molding powders. Du Pont uses MMA. captively to make paints, acrylic marble,
acrylic resins for surface coating, cast acrylic sheets, and polymethacrylate
molding powders. Rohm & Haas uses its MMA output for cast acrylic sheets, mold-
ing powder, and other homopolymers and copolymers.4
-------
II-3
Table II-l. Methyl Methacrylate Capacity0
Company
CY/RO Industries
Du Pont
Du Pont
Rohm & Haas
Total
Location
Fortier, LA
Belle, WV
Memphis , TN
Deer Park, TX
Production
Capacity
(Gg/yr)b
50
61
100
300
511
See ref 3.
DAs of 1979.
-------
II-4
1. CY/RO Industries, Fortier, LA
2. Du Pont Co., Bella, WV
3. Du Pont Co., Memphis, TN
4. Rohm & Haas Co., Deer Park, TX
Fig. II-1. Locations of Plants Manufacturing Methyl Methacrylate
-------
II-5
D- REFERENCES*
!• "Big changes in Store for Methyl Methacrylate," Chemical Engineering 85(15).
25—27 (1978). —
2- J. L. Blackford, "Acetone," pp 604.5032L—604.5032M in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park, CA (January 1975).
3- J. L. Blackford, "Acetone," pp 604.5031J—604.5032L in Chemical Economics
Handbook. Stanford Research Institute, Menlo Park, CA (July 1978).
4- J. L. Blackford, "Methyl Methacrylate," pp 674.4521A—674.4522G in Chemical
Economics Handbook, Stanford Research Institute, Menlo Park, CA (October 1976).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
III-l
III. PROCESS DESCRIPTION
A- INTRODUCTION
All methyl methacrylate (MMA) in the United States is manufactured from ACN.
which is made from acetone and hydrogen cyanide. MMA manufacturers usually pur-
chase acetone and ship it to the plant location but manufacture the HCN on-site.
B- ACETONE CYANOHYDRIN FROM ACETONE AND HYDROGEN CYANIDE
*• Basic Process
The reactions utilized to manufacture acetone cyanohydrin are reported1 as:
CH3 CH3 OH
\ \ /
^C=0 + HCN * .C
CH3 CH3 NCN
(acetone) (acetone cyanohydrin)
Figure III-l shows a typical process flow diagram for the manufacture of ACN.2'3
Acetone is stored in tanks before being fed to the process (Stream 1). Hydrogen
cyanide (Stream 2), usually produced elsewhere at the same plant site, may be
stored temporarily before being fed to the reactor. The catalyst (Stream 3), an
alkali such as sodium hydroxide or other bases, is also stored. Acetone recovered
iater in the process (Stream 4) is combined with the other reactants in the reactor
to form acetone cyanohydrin. The liquid-phase acetone cyanohydrin reaction is
carried out at less than 40°C, with yields above 90% usually attained.^ Acetone
cyanohydrin readily decomposes at higher temperatures.
The sodium hydroxide in the product stream (Stream 5) is neutralized with sulfuric
acid (Stream 6) to stabilize the ACN, and the solid salts formed are removed by
filtration and then backwashed with water (Stream 7), which results in a salt
waste stream.
The filtered crude reaction product enters a vacuum evaporation system for acetone
removal (Stream 11), and the acetone cyanohydrin bottoms (Stream 10) are fed to
a second evaporator. The second evaporator removes water and trace acetone (Stream 12),
Caving acetone cyanohydrin product (Stream 14). The distillate (Stream 12) is
-------
rte)
—(
SALT
TO
WASTE.WATER.
t ^p
.I_T
3 I
WATER. t_
TO
MAUUFACtURE
RECOVERED
VACUUM
*
F«> Y
EVAPORATION
M
I
ACU TO
(II
,
1 *^
NIC
ERY
OTIOW
^-v.
*
Y
TQ
TREATMENT
Fig. III-l. Flow Diagram for the Manufacture of Acetone Cyanohydrin
-------
III-3
further distilled in an acetone recovery column, and the recovered acetone
(Stream 13) is recycled (Stream 4) to the reactor. The aqueous bottoms from the
acetone recovery column are sent to wastewater treatment.
When different catalysts are used, the solubility of the alkali sulfate salt
will change, which results in various amounts of salt escaping through the filter
and ultimately remaining with the acetone cyanohydrin product. The use of a
salt with high solubilities in stream 8 would require subsequent distillation of
ACN product to remove it from dissolved solids.
c- METHYL METHACRYLATE FROM ACETONE CYANOHYDRIN
*• Basic Process
The reaction of ACN to MMA involves the formation of methacrylamide sulfate from
ACN. The methacrylamide sulfate is then reacted with methanol to form MMA. The
reactions describing this process are as follows:
CH,
•\
CH,/
OH
H2S04
CH2=C(CH3)C
(acetone cyanohydrin) (sulfuric acid)
XNH2*H2S04
(methacrylamide sulfate)
CH2=C(CH3)C
V
CH3OH
CH2=C(CH3)C
V
NH2*H2S04
OCH3
(methacrylamide sulfate) (methanol)
(MMA)
NH4HS04
(ammonium bisulfate)
Figure III-2 is a typical process flow diagram for the manufacture of MMA from
ACN.2'3'5.6 The ACN (stream I) is stored until it is to be fed to the hydrolysis
reactors. Sulfuric acid (Stream 2) is also fed to the reactor, forming methacryl-
amide sulfate. The ACN is hydrolyzed in two reactors at 130°C and the ACN—sulfuric
acid reaction is highly exothermic (250,000 joules/g-mole).4 Vapors are removed
from the product stream in a vapor-liquid separator and are combined with vapors
-------
FROM
ACU
MM»..
VAPOR-UQUIO
MCTHAKJOI-
ESTE.RIPICATIOW
rd
Oh-
I
£.
DISTlLLAJIOkJ
TO
REiOVER-Y
PLAWT
Fig. III-2. Flow Diagrciin for the Manufacture of Methyl Methacrylate from Acetone Cyanohydrin
-------
VACUUM
SYSTEVA
DlSTlULXTIOKJ
rfl
CO
VACUUM
Y
DEMOTES VACUUM
EQUIPMENT
I
Ul
Wig. III-2. (Continued)
-------
III-6
from the hydrolysis reactor vent to form stream 2A. The vapors are the carbon
monoxide formed by decomposition of ACN, traces of ACN, and acetone. The product
(Stream 3) is fed to the esterification reactor with fresh methanol (Stream 4)
and recovered methanol (Stream 14). The reactor effluent is a two-phase liquid
mixture (Stream 6).
The light phase (Stream 7) is distilled in a vent distillation column designed
to remove dissolved carbon monoxide; then, after the light phase is neutralized
with anhydrous ammonia (Stream 10), it is fed to a water extraction column. MMA
and methacrylic acid recovered later in the process (Stream 20) are also fed to
the water extraction column. The raffinate (Stream 13) from the water extraction
column contains the MMA and similar organics,- the extract (Stream 12) contains
water, ammonia bisulfate, methanol, and other water-soluble compounds.
The heavy phase (Stream 8) from the liquid-liquid separator is distilled in a
spent acid distillation column, where light organics such as methanol are removed
(Stream 14). These are combined with the extract (Stream 12) from the water
extraction column and recycled to the esterification reactor. Bottoms from the
spent acid distillation column are routed to the sulfuric acid recovery plant or
to ammonia sulfate production.
The raffinate (Stream 13) from the water extraction column is distilled in a
vacuum distillation column, where the light ends (Stream 16) are removed . This
stream is split, with some of it being recycled (Stream 18) to the water extrac-
tion column and some of it further distilled to remove the light ends to prevent
their buildup in the system. The bottoms (Stream 19) from the light-ejids distilla-
tion column are recycled to the water extraction column.
Crude MMA leaves the crude MMA distillation column as the bottoms stream (Stream 21)
which can be distilled at the production location or be transported for further
purification at other sites. The distillation proceeds under vacuum, and the
bottoms (Stream 26) are recycled to the MMA process. The distillate is pure MMA
and is stored for shipping and/or processing. ACN that is marketed (Stream 27)
is also stored in preparation for shipping.
Inhibitors are used to prevent polymerization of the MMA under purification and
storage, which vary from site to site.
-------
III-7
FUTURE PROCESSES
Recent literature indicates that no new MMA plants will use the ACN route as
described above. Companies now entering the MMA business (such as Oxirane
International and Vistron Corp.) use oxidation technology based on isobutylene,
and the established companies are actively investigating this technology. The
isobutylene route is expected to be less expensive compared with the ACN process.7
The process chemisty is described below:
OH
CH3-C-CH3 + H20 > CH3-C-CH3 (1)
II l
CH2 CH3
(isobutylene) (tert-butyl alcohol)
OH 0
I H
CH3-C-CH3 + 02 * CH2=C-C-H + 2H20 (2)
CH3 CH3
(methacrolein)
2CH2=C-C (3)
/ \
CH3 H CH3 OH
(methacrylic acid)
* »
CH2=C-C + CH3OH * CH2=C-C-0-CH3 + H20 (4)
CH3 OH CH3
(methyl methacrylate)
Reaction 1 proceeds over an acidic ion-exchange catalyst at less than 100°C.
Both reactions 2 and 3 occur at about 300°C and at about 14.1 kPa. Conversions
and selectivities of reactions 2 and 3 range from 80 to 90%. Reaction 4 occurs
at 400°C, with conversions and selectivity at 80%. The overall yield is reported
to be 58%. All steps are exothermic and reaction by-products are acetic acid
(0.05 kg/kg of MMA), acetone (0.01 kg/kg of MMA), and carbon dioxide.7
Emission information and further process details are not available at this time.
-------
III-8
E. REFERENCES*
1. W. J. Svirbely and J. R. Roth, "Carbonyl Reactions. I. The Kinetics of Cyanohydrin
Formation in Aqueous Solution," Journal of the American Chemical Society ]75
*
3106—11 (1955). Cited in: R. G. Denney, Methacrylic Acid—Methacrylic
Esters, Report No. 11, A private report of the Process Economics Program, Stanford
Research Institute, Menlo Park, CA (May 1966).
2. Rohm & Haas, Emissions Inventory Questionnaire, submitted to Texas Air Control
Board, Mar. 19, 1976.
3. J. W. Blackburn, IT Enviroscience, Inc., Trip Report on^Visit to Rohm & Haas Co.,
Deer Park, TX, Nov. 1, 1977 (on file at the ESED, EPA, Research Triangle Park, NC).
4. D. C. Thomas, Methacrylic Acid—Methacrylic Esters, Report No. 11A, A private
report of the Process Economics Program, Stanford Research Institute, Menlo Park,
CA (May 1974). .
5. J. W. Blackburn, IT Enviroscience, Inc., Trip Report on Visit to E. I du Pont de
Nemours & Co., Memphis, TN, Jan. 10, 1978 (on file at the ESED, EPA, Research
Triangle Park, NC).
6. Nonconfidential information provided to EPA on May 1978 from CY/RO Industries, Wayne,
NJ (on file at the ESED, EPA, Research Triangle Park, NC).
7. J. C. Davis, "Big Changes in Store for Methyl Methacrylate," Chemical Engineering
85(15), 25—27 (1978).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
IV-1
IV. EMISSIONS AND APPLICABLE CONTROL SYSTEMS
Emissions in this report are usually identified in terms of volatile organic
compounds (VOC). VOC are currently considered by the EPA to be those of a large
group of organic chemicals, most of which, when emitted to the atmosphere, parti-
cipate in photochemical reactions producing ozone. A relatively small number of
organic chemicals have low or negligible photochemical reactivity. However,
many of these organic chemicals are of concern and may be subject to regulation
by EPA under Section 111 or 112 of the Clean Air Act since there are associated
health or welfare impacts other than those related to ozone formation.
A- GENERAL
Emission data from the three domestic producers of MMA and ACN are presented in
Tables IV-1 and IV-2. The ACN and MMA process flowsheets (Figs. III-l and III-2)
are used as model processes, and the emission data from the three producers are
arranged to fit the flowsheets. No model-plant or average emission rate for
these processes is included in this study since data were obtained for all three
domestic producers and future increases in MMA production will involve oxidation
technology based on isobutylene.
The uncontrolled emissions from normal process vents are based on data obtained
from the producers. The controlled emissions from the normal process vents are
based on the current level of control now used in the industry and noted later
in the text.
Emissions from the plants are classified as process, storage and handling, secon-
dary, and fugitive emissions. Process and secondary emissions for the plants
are based on data obtained from plant site visits and reports submitted to the
EPA.1 — * Fugitive and storage and handling emissions are not included in this
report since emission rates and controls for the SOCMI are discussed in separate
documents.
B- ACETONE CYANOHYDRIN PROCESS (Fig. III-l, Table IV-1)
The normal .process emission occurs from the following sources:
-------
Table IV-1. Uncontrolled and Controlled VOC Emissions from Production of Acetone Cyanohydrin
Source
CY/RO Industries, Fortier, LA (36 Gg/yr)
Du Pont, Memphis, TN (109 Gg/yr)
Reactor off-gas
Recovery columns
Rohm & Haas, Deer Park, TX (300 Gg/yr)
Reactor off-gas
Acetone evaporation vaccum vent
Recovery column
*kg of VOC per Mg of acetone cyanohydrin
Stream
Designation
(Fig.III-1)
1A
1B,1C,1D
1A
IB
1C, IB
produced.
Uncontrolled
Emission
Ratio
(kg/Mg) *
No data available
0.039
1.17
No data
0.004
0.004
Control Emission
Device or Reduction
Technique (%)
Condenser 90
None
Flare
None
None
Controlled
Emission
Ratio
(kg/Mg) *
0.004
1.17
0.004
0.004
-------
Table IV-2. Uncontrolled and Controlled VOC Emissions from Production of Methyl Methacrylate
Source
CY/RO Industries, Fortier, LA (36 Gg/yr)
Reactor vent
Vent distillation
MMA and light-ends distillation
Acid distillation
MMA purification
Total
Du Pont, Memphis, TN (109 Gg/yr)
Reactor vent and acid distillation
Vent, MMA, and light-ends distillation
MMA purification
Total
Rohm & Haas, Deer Park, TX (300 Gg/yr}
Reactor vent and vent, MMA, and light-
ends distillation
Acid distillation
MMA purification
Total
Uncontrolled
Stream Emission Control Emission
Designation Ratio Device or Reduction
(Fig. 111-2} (kg/Mg}* Technique (%)
2A
2B
2C,2D
2E
2F
2A,2E 6.62 None
2B,2C,2D 4.74 None
2F 2.65 Condenser 96.7
2A,2B,2C,2D 21.0 Flare 99+
2E
2F
Current
Emission
Ratio
(kg/Mg) *
0.0
0.954
11.8
1.09
2.1
15.9
H
6.62 °*
4.74
0.087
11.4
0.007
19
19.0
*kg of VOC per Mg of methyl methacrylate produced.
-------
IV-4
1. Acetone Cyanohydrin Reactor (Vent 1A)
Information from one methyl methacrylate producer1 indicates that the reactor
off-gas rate is low. The VOC emission is composed of acetone and hydrogen cyanide
and is curently being controlled by condensers or is sent to a flare.
2. Purification and Recovery Columns (Vents IB, 1C, and ID)
To reduce the acetone loss from the product distillation columns and acetone
recovery column, condensers are used. These condensers are not considered to be
emission control devices unless they operate beyond economic optimum. CY/RO
Industries passes these vent gases through an incinerator.
3. Secondary Emissions
Secondary emissions related to ACN production are from handling of sulfate salts
and from wastewater from the acetone recovery distillation column. One manufacturer
states that there are no secondary emissions related to the manufacture of acetone
cyanohydrin.
C. METHYL METHACRYLATE PROCESS (Fig. III-2, Table IV-2)
1. Hydrolysis Reactor (Vent 2A)
The emissions from the hydrolysis reactor vent are composed primarily of sulfur
dioxide and carbon monoxide and other reaction by-products. No data are available
for emissions from this vent, since they are combined with other vent emissions.
Currently the emissions are mixed with other vent streams and are sent to a flare
or are not being controlled.
2. Distillation Vents (2B, 2C, 2D, 2E, 2F)
The gases from the vent distillation, crude MMA, light-ends, spent acid, and
product-MMA columns are composed of noncondensables that are dissolved in the
feed to the columns, of the VOC that are not condensed, and, for columns operated
under vacuum, of the air that leaks into the column and is removed by a vacuum
jet system.
The emissions are primarily controlled by condensers, which are usually included
as part of the processing condensers. Current emission rates are reported in
Table IV-2; some of the data on the uncontrolled emissions are not available.
-------
IV-5
In one case some of the vent emissions are combined and sent to a flare, which
achieves 99+% VOC reduction.2
3- Secondary Emissions
Secondary emissions related to MHA production are front organic wastes routed to
an incinerator or acid recovery unit, from intermittent aqueous wastes that are
sent to a sewer, and from spent acid and aqueous wastes that are sent to sulfuric
acid recovery.*
The organic wastes generated are polymeric material formed during MMA production,
acid recovery, or incineration. The polymeric formation rate is estimated at
0.0022 and 0.0181 (kg of polymer/kg of MMA product); the polymer goes to landfill
or incineration.
The spent acid has been reported to contain 0.5% VOC5 to 10% VOC,1 including
methyl methacrylate, methacrylic acid, methyl formate, methanol, and acetone.
Emissions from sulfuric acid recovery can be a significant fraction of the con-
trolled VOC emission levels. Little or no organic emission data exist for various
types of acid recovery units when the feed stream contains organics. These secon-
dary emission and control systems will be discussed in a future EPA report.
D- ESTIMATED EMISSIONS FOR THE INDUSTRY
At the current level of control the VOC emissions for the acetone cyanohydrin
industry are estimated at 193 Mg/yr* for the production dedicated to methyl methac-
rylate (approximately 80% of the ACN produced).
At the current level of control the VOC emissions are estimated at 6020 Mg* for
the 1978 methyl methacrylate production (domestic) of 370 Gg/yr.
If all methyl methacrylate were produced by the lowest emitting process in current
operations, the total domestic VOC emissions, including ACN production, would be
reduced from 6213 Mg/yr to 4219 Mg/yr. Most of the reduction could be accomplished
by condensing the emissions from the vacuum systems. The cost or practicality
°f incorporating additional controls to existing processes has not been evaluated
in this abbreviated product report.
*Does not include fugitive, secondary, and storage and handling emissions.
-------
IV-6
As discussed in Sect. III-D, it is anticipated that no new methyl methacrylate
processes will be patterned after the processes currently in operation.
The preceding emission estimates for the industry are based on the following
assumed criteria: Du Font's Belle, WV, plant has the same level of emission as
its Memphis, TN, plant; all the production facilities are operating at the same
percent of capacity.
-------
IV-7
E. REFERENCES*
1- J. W. Blackburn, IT Enviroscience, Inc., Trip Report on Visit to E. I. du Pont de
Nemours & Co., Memphis, TN, Jan. 10, 1978 (on file at EPA, ESED, Research
Triangle Park, NC).
2. J. w. Blackburn, IT Enviroscience, Inc., Trip Report on Visit to Rohm & Haas Co.,
Deer Park, TX, Nov. 1, 1977 (on file at EPA, ESED, Research Triangle Park, KC).
3- CY/RO Industries, letter dated May 4, 1978, in response to ura-s request for
information on emission data on methyl methacrylate production facilities.
4- Rohm & Haas Company, emissions data in Emissions Inventory Questionnaire,
submitted to Teisas Air Control Board, Mar, 19, 1976.
5- L. D. Johnson, Rohm & Haas Co., letter dated June 21, 1979, to D. R. Patrick,
EPA.
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
A-l
APPENDIX A
Table A-l. Physical Properties of Acetone Cyanohydrina
Molecular formula C.H-NO
Molecular weight 85.11
Physical state Liquid
Vapor pressure 10 mm Hg at 70 °C
or 0.3 mm Hg at 20°CC
Vapor specific gravity 2.93
Boiling point 82°C at 23 mm Hg
Melting point -20°C
'Density . 0.932 at 20°C/4°C
Water solubility Very soluble; decomposes
in H20
aFrom: J. Dorigan, B. Fuller, and R. Duffey, "Acetone Cyanohydrin," p AI-22
scoring of Organic Air Pollutants. Chemistry, Production and Toxicity of
selected Synthetic Organic Chemicals (Chemicals A-C), MTR-7248, Rev. 1,
Appendix I, MITRE Corp., McLean, VA (1976).
^According to data developed by Rohm and Haas Co.
cAccording to a Chemical Manufacturing Association member company.
-------
A-2
Table A-2. Physical Properties of Methyl Methacrylate*
Molecular formula ccH0°i
3 O £
Molecular weight 100.13
Physical state Liquid
Vapor pressure 40 nun Hg at 25.5°C
Vapor specific gravity 3.45
Boiling point 100 to 101 °C at 760 mm Hg
Melting point -48°C
Density 0.9440 at 20°C/4°C
Water solubility Slight
*From: J. Dorigan, B. Fuller, and R. Duffey, "Methyl Methacrylate,"
p AIII-204 in Scoring of Organic Air Pollutants. Chemistry,
Production and Toxicity of Selected Synthetic Organic Chemicals
(Chemicals F-N), MTR-7248, Rev. 1, Appendix III, MITRP Corp.,
Mclean, VA (1976).
-------
6-i
REPORT 6
CHLOROPRENE
S. W. Dylewski
IT Enviroscience
9041 Executive Park Drive
Knoxville, Tennessee 37923
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
September 1980
This report contains certain information which has been extracted from the
Chemical Economics Handbook, Stanford Research Institute. Wherever used, it
has been so noted.The proprietary data rights which reside with Stanford
Research Institute must be recognized with any use of this material.
-------
6-iii
CONTENTS OF REPORT 6
Page
1• ABBREVIATIONS AND CONVERSION FACTORS 1-1
II- INDUSTRY DESCRIPTION II-l
A. Reason for Selection II-l
B. Usage and Growth II-l
C. Domestic Producers II-l
D. References II-4
HI. PROCESS DESCRIPTION III-l
A. Introduction III-l
B. Chemistry III-l
C. Process Description III-2
D. Process Variations III-7
E. References III-8
IV- EMISSIONS IV-1
A. Typical Plant IV-1
B. Sources and Emissions IV-1
C. References IV-5
v- APPLICABLE CONTROL SYSTEMS V-l
A. Butadiene Dryer Vent V-l
B. Chlorination Vent V-l
C. Dichlorobutene (DCB).Distillation Vent V-l
D. Isomerization and Distillation Vent V-l
E. Chloroprene Stripper Vent V-3
F. Brine Stripper Vent V-3
G. Storage and Handling; Fugitive, and Secondary Emissions V-3
H. References V-4
Vl- IMPACT ANALYSIS VI-1
APPENDICES OF REPORT 6
A. PHYSICAL PROPERTIES OF 1,3-BUTADIENE, A-l
2-CHLORO-l,3-BUTADIENE
B. EXISTING PLANT CONSIDERATIONS B-l
-------
6-v
TABLES OF REPORT 6
Number
' Page
"! Chloroprene Usage II-2
~2 Chorpprene Capacity H_2
VOC Emissions from Uncontrolled Sources in Typical IV-2
Chloroprene Plant
VOC Emissions from Controlled Sources in Typical Chloroprene V-2
Plant
Vl-i
Environmental Impact of Controlled Sources in a Typical VI-2
Chloroprene Plant
A"a Physical Properties of 1,3-Butadiene A-l
A-?
Physical Properties of 2-Chloro-l ,3-Butadiene A-2
-i
Control Devices and VOC Emissions from Denka (Houston, TX) B-2
Chloroprene Plant
Control Devices and VOC Emissions from Du Pont (La Place, LA) B-3
Chloroprene Plant
OF REPORT 6
Page
Flow Diagram for Chloroprene from Butadiene III-3
-------
1-1
ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements used in agency documents in metric
units. Listed below are the International System of Units (SI) abbreviations
and conversion factors for this report.
To Convert From
Pascal (Pa)
Joule (J)
Degree Celsius (°C)
Meter (m)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter/second
(m3/s)
Watt (W) .
Meter (m)
Pascal (Pa)
Kilogram (kg)
Joule (J)
To
Atmosphere (760 mm Kg)
British thermal unit (Btu)
Degree Fahrenheit (°F)
Feet (ft)
Cubic feet (ft3)
Barrel (oil) (bbl)
Gallon (U.S. liquid) (gal)
Gallon (U.S. liquid)/rain
(gpm)
Horsepower (electric) (hp)
Inch (in.)
Pound-force/inch2 (psi)
Pound-mass (Ib)
Watt-hour (Wh)
Standard Conditions
68°F - 20°C
.1 atmosphere = 101,325 Pascals
PREFIXES
Multiply By
9.870 X 10"6
9.480 X 10~4
(°C X 9/5) + 32
3.28
3.'.531 X 101
6.290
2.643 X 102
1.585 X 104
1.340 X 10"3
3.937 X 101
1.450 X 10~4
2.205
2.778 X 10~4
Prefix..
T
G
M
k
m
P
Symbol
tera
giga
mega
kilo
milli
micro
Multiplication
Factor .
12
10
109
106
10*
10~3
10'6
Example
1
1
1
1
1
1
Tg =
Gg =
Mg =
km =
mV =
Mg =
1
1
1
1
1
1
X
X
X
•X
X
X
1012
109
1Q6
103
io"3
10 "6
grams
grams
grams
me.ters
volt
gram
-------
II-l
II. INDUSTRY DESCRIPTION
A. REASON FOR SELECTION
Propylene oxide production was selected for study because preliminary estimates
indicated that production of this material generated a fairly large amount of
air emissions. In addition, the manufacture of propylene oxide is a large and
growing industry.1
Many of the raw materials, intermediates, finished products, by-products, and
organic waste streams handled or generated in the manufacture of propylene
oxide have relatively high vapor pressure (low boiling points); so vents and
other emission sources are likely to discharge significant amounts of organic
vapors to the air unless appropriate emission control techniques are used.
B. PROPYLENE OXIDE USAGE AND GROWTH1'2
Table II-l shows propylene oxide production and growth rates. The predominant
use of propylene oxide is in the manufacture of polyether polyols used for the
manufacture of urethane foams. Use of propylene oxide for manufacture of poly-
ether polyols has varied from 52% to 62% of the total propylene oxide consumed
domestically in the period 1974 to 1978. The other principal uses for propylene
oxide are in the manufacture of propylene glycol (21 to 23%), dipropylene
glycol (2.5 to 2.9%), and glycol ethers (1.2 to 1.5%). Miscellaneous uses
accounted for the balance of the propylene oxide consumed.
Some propylene oxide is sold on the open market to processors that convert it to
other intermediates or finished products, but a large share of the total amount
manufactured is used by the producers to make other intermediates or finished
products. Because of this large internal consumption by integrated producers,
the production data shown in Table II-l are expected to contain some inaccuracies,
but they represent the best numbers available. The current projected growth of
5.3 to 7.1% per year is expected to continue through 1982.
C. DOMESTIC PRODUCERS
As of January 1979 four producers of propylene oxide in the United States were
operating plants at six locations. Table II-2 lists the producers, plant
capacity, and type of process used in the plant. Figure II-l shows the location
of the six domestic plants.1
-------
II-2
Table II-l. Chloroprene Usage
End-Use
Domestic Consumption for 1975*
(% of total)
Industrial rubber goods
Automotive
Wire and cable
Construction
Adhesives
Other
35
28
13
10
8
6
*See ref 1.
Table 11-2. Chloroprene Capacity
Plant
Capacity
As of 1979
(Gg/vr)
Denka Chemical Corp.
a
Houston, TX
*
E. I: du Pont de Nemours & Co., Inc.
La Place, LA
Victoria, TX
27
86C
149
262°
Formerly owned and operated by Petro-Tex Chemical Corp; see
ref 5.
See ref 3.
•*
"See ref 4.
See ref 2 . The material losses during the conversion of
Chloroprene to neoprene results in a neoprene capacity of
240 Gg/yr.
-------
II-3
2. E. I. du Pont de Nemours and Company
The plants at La Place, LA, and Victoria, TX, are both based on chlorination
of butadiene. The facilities at Victoria, TX, make both adiponitrile and chloro-
prene via chlorination of butadiene, which allows some flexibility in operation.2
-------
II-4
D. REFERENCES*
1. "Polychloroprene (Neoprene) Elastomers," pp. 525.5020A—D in Chemical Economics
Handbook,' Stanford Research Institute, Menlo Park, CA (April 1977).
2. T. F. Killilea, "Butadiene," pp. 300.5802J—L in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park, CA (October 1979).
3. A. J. Meyer, Denka Chemical Corp., letter dated Mar. 26, 1979, in response to
EPA request for information on emissions from chloroprene production facilities.
4. H. A. Smith, E. I. du Pont de Nemours and Co., letter dated Nov.-.28, 1978,
in response to EPA request for information on emissions from chloroprene pro-
duction facilities.
5. R. D. Pruessner, Petro-Tex Chemical Corp., letter dated Sept. 29, 1978, in
response to EPA request for information on emissions from chloroprene produc-
tion facilities.
^Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
ni-i
III. PROCESS DESCRIPTION
A. INTRODUCTION
Chloroprene has been produced commercially in the United States since 1932. All
chloroprene production was based on acetylene until 1970, at which time butadiene-
based production was started. Since 1972 all production has been via the butadiene-
based process.1 This report is concerned with only the butadiene-based process.
B- CHEMISTRY
The commercial route from 1,3-butadiene (butadiene) to 2-chloro-l,3-butadiene
(chloroprene) requires three chemical process steps: chlorination to form mixed
isomers of dichlorobutene, isomerization of the undesired isomer to yield only the
desired isomer, and dehydrochlorination of the desired isomer to chloroprene.2
1- Chlorination
HH Cl H H Cl
II |I11
C12 + H2C=C-C=CH2 ^— * H2C - C = C - CH2
(chlorine) (1,3-butadiene) (l,4-dichlorobutene-2)
(or 1,4-DCB)
Cl Cl H
l I I
H2C - C - C = CH2
H
(3,4-dichlorobutene-l)
(or 3,4-DCB)
In addition to the above several other products are formed in the reactor: tetra-
chlorobutane, which is formed by further chlorination of the DCBs,- HCl and chloro-
butadienes, which are formed by decomposition of the DCBs; chlorobutenes and chloro-
butanes, which are formed from impurities in the butadiene; and CO2 and H20, which
are formed from any oxygen present.2
Isomerization
Cl H H Cl Cl Cl H
I I | I I II
H2q - C = C - CH2 -c ». H2C - C - C = CH2
H
(1,4-dichlorobutene-2) (3,4-dichlorobutene-l)
(or 1,4-DCB) (or 3,4-DCB)
-------
III-2
In the presence of a catalyst 1,4-DCB is converted to 3,4-DCB, producing a
mixture that under equilibrium conditions consists of essentially equal parts
of each isomer. By the combined processes of distillation and isomerization
the undesired isomer formed in chlorination is consumed and only the desired
isomer is yielded.
During the process of isomerization small quantities of the dichlorobutenes are
decomposed to yield HC1 and chlorobutadiene. Some of the chlorobutadiene is
polymerized to nonvolatile products that are ultimately wasted, and the remain-
der is vented from the process along with the HCl that is formed and the low-boiling
chlorinated organic compounds that were formed in the chlorinator.2'3
3. Dehydrochlorination
Cl Cl H Cl H
III II
H2C - C - C = CH2 + NaOH > H2C = C - C = CH2 + NaCl + H20
H
(3,4-dichlorobutene-l) (sodium (2-chloro-l,3-butadiene) (sodium (water)
(or 3,4-DCB) hydroxide) (or chloroprene) chloride)
In the presence of sodium hydroxide solution (caustic) and under mild conditions of
.temperature the 3,4-DCB is dehydrochlbrinated to 2-chloro-l,3-butadiene (chloro-
prene). The sodium chloride brine that is formed is discarded, as is any excess
caustic.
C. PROCESS DESCRIPTION
The process flow diagram shown in Fig. III-l represents a typical continuous
process for the manufacture of chloroprene based on chlorination of butadiene.
This process was assembled from limited available sources.2—6 It does not
necessarily represent an actual chloroprene plant but typifies the processing
steps of a complete plant and its emission sources.
1. Butadiene (BD) Drying
Butadiene, received as a liquid (stream 1), is dried by azeotropic distillation,
allowing any inert gases present to be discharged at vent A. The water that is
removed is sent to wastewater treatment (discharge G). Dry, inert-gas-free,
butadiene is forwarded to chlorination (stream 2).
-------
Fig. III-l. Flow Diagram for Chloroprene from Butadiene
-------
III-4
2. Chlorination
Dry butadiene (stream 2) and butadiene recycle (stream 8) are fed to the buta-
diene heater to vaporize the butadiene and to bring it to reaction temperature
(250 to 300°C). Chlorine, received as a gas from an off-site liquid chlorine
vaporization step (stream 3), is fed to the chlorine heater to bring the chlorine
also to reaction temperature. The two preheated gas streams are fed separately
to the chlorinator, wherein good mixing is quickly imparted to prevent high
concentrations of chlorine in the presence of organic materials.
The reaction of chlorine with butadiene to form the dichlorobutenes (DCBs) is
exothermic. At elevated temperatures the rate of the decomposition reaction of
DCBs to form chlorobutadienes and HC1 is excessive. Butadiene is fed to the
chlorinator in excess to absorb some of the exotherm and to minimize the further
reaction of chlorine with DCBs to form tetrachlorobutane. In addition to
excess butadiene a controlled stream of process liquid (stream 11) is fed to
the chlorinator to moderate the reaction temperature by evaporative cooling.
The reaction products are partly condensed by cooling and are separated into a
liquid phase (stream 4) and a vapor-gas phase (stream 5).
The condensed liquid (stream 4) is stripped in the degassing column, thereby pro-
ducing an overhead stream (6) that contains inert gases, unreacted chlorine, HCl,
butadiene, chlorobutadienes and other low-boiling chlorinated organics, and a bot-
toms stream (7) that contains the DCBs and the higher boiling reaction products.
A major portion (stream 8) of the combined vapor-gas streams 5 and 6, which result
from excess butadiene in the chlorinator feed, is recycled to the chlorinator. A
small portion (stream 9) is purged and then sent to the butadiene absorber, where
chilled DCBs (stream 10) scrub butadiene from the purge stream. The butadiene-lade"
(DCB) stream (11) is returned to the chlorinator for temperature control while the
butadiene-lean overhead stream (12) is forwarded for further gas treatment.
3. Chlorinator Tail Gas Treatment
Stream 12, chlorinator tail gas, is first scrubbed with water to yield an HCl solu"
tion for industrial uses and is then scrubbed with caustic to remove the remaining
traces of HCl and the small amount of chlorine not consumed in chlorination. The
scrubbed gas, containing inert gases and VOC, is vented (vent B) to the atmosphere-
The waste brine (discharge H) is combined with other waste brine streams for suit-
able disposal.
-------
III-5
4- Dichlorobutene (DCB) Distillation
The bottoms stream (7) from the degassing column, along with the overhead stream
{13) from the high-boilers column, is fractionated in the DCB column to produce
an overhead product of mixed DCBs, A small portion of the overhead product from
the DCB column (stream 10) is chilled and sent to the butadiene absorber, while
the remainder (stream 14) is forwarded to isomerization. Inert gases, HC1, and
some chlorobutadienes (stream 15) are sent to the vacuum system. A water scrubber
is used on the tail gas from the vacuum system to absorb the HC1 before the
remaining gases are released (vent C) to the atmosphere. Wastewater (discharge I)
resulting from water scrubbing is sent to vastewater treatment.
The bottoms stream (16) from the DCB column is forwarded to the high-boilers
column, where the remaining DCBs are recovered overhead and returned (stream 13)
to the DCB column. Inert gases used in the control of vacuum operation and HC1
and chlorobutadienes from decomposition of the DCBs are forwarded to the vacuum
system through stream 17. The gases leaving the vacuum system are scrubbed with
water to remove traces of HC1 before being released (vent C) to the atmosphere.
Wastewater (discharge 1) from water scrubbing is sent to wastewater treatment.
Nonvolatile waste products formed during chlorination and distillation are removed
from the system at discharge J.
Isomerization and 3,4-DCB Recovery
Streams 14 and 18 are fractionated in the 3,4-DCB recovery column to recover 3,4-DCB
as an overhead product (stream 19) and 1,4-DCB as a bottoms product (stream 20).
The 3,4-DCB recovery column is operated under vacuum to maintain a lower temperature
in order to retard the isomerization of 3,4-DCB back to 1,4-DCB. Polymerization
inhibitors are added to retard the formation of polymers from any chlorobutadienes
resulting from breakdown of the'DCBs. The vent gas (stream 21) from the distillation
process contains HCl, chlorobutadiene, and the inert gases resulting from vacuum
operation. After passing through the vacuun system the vent gases are scrubbed
with water to absorb the HCl before they are released (vent D) to the atmosphere.
Wastewater (discharge L) is sent to wastewater treatment.
Stream 20 is mixed with catalysts in the isomerization and catalyst removal step
to enable some of the 1,4-DCB isomer to undergo rearrangement and to form 3,4-DCB.
In the process some of the DCBs decompose, forming HCl and chlorobutadienes.
Polymerization inhibitors are added to retard the formation of chlorobutadiene
-------
III-6
polymers. After isomerization the mixture of DCBs is separated from the catalyst
and wastes and is forwarded (stream 18) to the 3,4-DCB recovery column. Spent
catalyst, inhibitors, and nonvolatile organic wastes, including polymers, are
purged at discharge K.
6. Dehydrochlorination (DHC) and Chloroprene Recovery
The purpose of the dehydrochlorination (DHC) reactor process is to remove HCl from
the 3,4-DCB molecule and form 2-chloro-l,3-butadiene (chloroprene). Inhibitors
are used to retard the isomerization of 3,4-DCB back to 1,4-DCB, which would sub-
sequently dehydrochlorinate to the wrong chlorobutadiene, and to retard the for-
mation of polymers from both chlorobutadienes.
3,4-Dichlorobutene (stream 19) is fed to the DHC reactor along with caustic,
catalysts, reaction-promoting solvents, and inhibitors. The flow (stream 22)
from the DHC reactor is fed to the chloroprene stripper, where chloroprene is
recovered as the chloroprene-water azeotrope by steam distillation. After con-
densation and decantation the chloroprene product (stream 23) is sent to storage
and the water layer is sent to the brine stripper. Polymerization inhibitors
are also fed to the distillation column to inhibit the formation of polymers.
Inert gases present in the feed streams are released to the atmosphere at
vent E.
The bottoms (stream 24) from the chloroprene stripper contain large amounts of
sodium chloride brine, high-boiling solvents, unreacted DCS, and residual chloro-
prene and are sent to the decanter for separation of oils, brine, and polymer
wastes. After decantation most of the oil phase (stream 25) is returned to the
DHC reactor, while a portion (discharge M) is purged as a waste liquid. The small
amount of polymer waste that is formed is periodically removed (discharge N).
Both of these waste materials are disposed of by incineration. The organic-laden
brine layer (stream 26) and the water from the chloroprene decanter are then fed
to the brine stripper, where the solvent, unreacted DCB, and chloroprene are
recovered (stream 27) by steam distillation and returned to the DHC reactor.
This step requires vacuum distillation, and in-leakage air, along with entrained
gases, is released to the atmosphere at vent F. Disposal of the waste brine
(discharge 0) is by deep well or other appropriate means.
-------
III-7
D- PROCESS VARIATIONS
Since the process described above typifies the processing steps required for a
complete chloroprene plant but does not necessarily represent an actual facility,
variations from the typical process are therefore to be expected.
Significant variation from the typical process can occur as different catalysts
and inhibitors are used; as an example, if a less active inhibitor or higher
temperatures are used in DCB distillation, considerably more DCB will decompose
into HCl and chlorobutadiene. This may then require different operating condi-
tions and different equipment configuration to obtain an economic yield and
require different methods of emission control.
-------
III-8
E. REFERENCES*
1. T. F. Killilea, "Butadiene," pp. 300.5802J—L in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park, CA (October 1979).
2. P. L. Morse, Chloroprene, pp. 17—71, in Report No. 67, A private report by
the Process Economics Program, Stanford Research Institute, Menlo Park, CA
(December 1970).
3. A. J. Meyer, Denka Chemical Corp., letter dated Mar. 26, 1979, in response to EPA
request for information on emissions from chloroprene production facilities.
4. H. A. Smith, E. I. du Pont de Nemours and Co., letter dated Nov. 28, 1978, in
response to EPA request for information on emissions from chloroprene production
facilities.
5. W. J. Touhey, E. I. du Pont de Nemours and Co., letter dated Sept. 14, 1979,
in response to EPA request for information on emissions from chloroprene pro-
duction facilities.
6. Telephone conversation of S. W. Dylewski, IT Enviroscience, Inc., with W. J. Touhey/
E. I. du Pont de Nemours and Co., Nov. 8, 1979.
^Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
IV- 1
IV. EMISSIONS
Emissions in this report are usually identified in terms of volatile organic
compounds (VOC) . VOC are currently considered by the EPA to be those of a
large group of organic chemicals, most of which, when emitted to the atmosphere,
participate in photochemical reactions producing ozone. A relatively small
number of organic chemicals have low or negligible photochemical reactivity.
However, many of these organic chemicals are of concern and may be subject to
regulation by EPA under Section 111 or 112 of the Clean Air Act since there
are associated health or welfare impacts other than those related to ozone
formation.
TYPICAL PLANT
The typical plant developed for this study has a capacity of 86 Gg/yr based on
8760 hr of operation* per year, which is the capacity of one of the currently
operating plants.1'2
The quality of raw materials used in this study is typical of commercial materials
in current use. The composition of butadiene was taken as 99.5% 1,3-butadiene and
0.5% butenes,3 with 700 ppm of dissolved inert gas. Chlorine composition was taken
as 99.8+% C12, with 60 ppm of nonvolatiles4 and 800 ppm of dissolved nitrogen.
SOURCES AND EMISSIONS
Uncontrolled emission of volatile organic chemicals (VOC) from process sources
in chloroprene production are summarized in Table IV-1 and are discussed below.
The locations of the emission sources are shown in Fig. III-1.
Butadiene Dryer Vent
The inert gas present in the butadiene feed is released during azeotropic
drying of butadiene. The inert gas and some butadiene carried with it are
released at vent A. The quantity of emission is related to production, as
well as to the nitrogen content of butadiene raw material.
*Process downtime is normally expected to range from 5 to 15%. If the hourly
rate remains constant, the annual production and the annual VOC emissions will
be correspondingly reduced. Control devices will usually operate on the same
cycle as the process. From the standpoint of cost-effectiveness calculations
the error introduced by assuming continuous operation is negligible.
-------
IV-2
Table IV-1. VOC Emissions from Uncontrolled Sources in Typical Chloroprene Plant
Emission Source
Butadiene dryer vent
Chlorination vent
DCB distillation vent
Isoraerization and 3,4-DCB recovery vent
Chloroprene stripper vent
Brine stripper vent
Stream
Designation
(Fig.III-1)
A
B
C
D
E
P
VOC
Ratio
(gAg)a
1.216
0.237
3.92
0.144
0.156
0.156
5.829
Emissions __
Rate
(kg/hr)
11.96
2.33
38.56
1.42
1.53
__l_-.53
57.33
ag of emission per kg of Chloroprene produced.
Based on 8760-hr/yr operation.
-------
IV-3
2- Chlorination Vent
Nitrogen present in the chlorine feed and HCl formed during the reaction must
be purged from the reactor system. The purged gases carry with them butadiene,
other VQC, and some unreacted chlorine. The purged gas stream is scrubbed with
water and then with caustic, which removes the acid gases; however, the butadiene
and most of the VOC are not condensed and are ultimately emitted at vent B.
The inert content of the chlorine, the rate of decomposition of DCS to produce
HCl, and the throughput rate will affect the quantity of the emissions.
3- Dichlorobutane (DCB} Distillation Vent
The gases present in the feed, inert gases used for vacuum control, air
in-leakage due to vacuum operation, and HCl resulting from decomposition of
DCB, must be purged from the DCB distillation system. Along with these gases
low-boiling VOC, chlorobutadiene, and DCBs are also purged.. The HCl is removed
by water scrubbing but most of the VOC remain with the gas to be released at
vent C. The rate of decomposition of DCB will affect the VOC emission to a
large extent, as will the throughput rate.
4- Isomerization and 3,4-DCB Recovery Vent
The gases present in the feed, inert gases used for vacuum control, in-leakage
air due to vacuum operation, and HCl resulting from decomposition of DCB must
be purged from the DCB distillation system. Along with these purged gases low-
boiling VOC, chlorobutadiene, and DCBs are also released. The HCl is removed
by water scrubbing but most of the VOC remain with the gas to be released at
vent D. The rate of decomposition of DCB will affect the VOC emission to a
large extent, as will the throughput rate.
Chloroprene Stripper Vent
*nert gases present in the feed and in the steam used for steam distillation in
the chloroprene stripper column must be vented. These gases, as well as the
VOC that they carry, are released to the atmosphere at vent E.
Brine Stripper Vent
Jnert gases present in the feed, gases in the steam used for steam distillation,
air in-leakage due to vacuum operation, and gases used for vacuum control in
the brine stripper must be vented. These gases and the VOC that they carry are
released to the atmosphere at vent F.
-------
IV-4
7. Storage, Fugitive, and Secondary Emissions
Storage and handling, fugitive, and secondary emissions for the entire synthetic
organic chemicals manufacturing industry are covered by separate EPA documents.5—'7
-------
IV-5
C. REFERENCES*
1. H. A. Smith, E. I du Pont de Nemours and Co., letter dated Nov. 28, 1978, in
response to EPA request for information on emissions from chloroprene production
facilities.
2. W. J. Touhey, E. I. du Pont de Nemours and Co., letter dated Sept. 14, 1979, in
response to EPA reqest for information on emissions from chloroprene production
facilities.
3. A. J. Meyer, Denka Chemical Corp., letter dated Mar. 26, 1979, in response to EPA
request for information on emissions from chloroprene production facilities.
4. Telephone conversation of S. W. Dylewski, IT Enviroscience, Inc., with R. E. Wing,
Dow Chemical Co., Nov. 6, 1979.
5. D. G. Erikson, IT Enviroscience, Inc., Storage and Handling (September 1980)
(EPA/ESED report, Research Triangle Park, NC).
6. D. G. Erikson, IT Enviroscience, Inc., Fugitive Emissions (September 1980)
(EPA/ESED report, Research Triangle Park, NC).
7. J. J. Cudahy and R. L. Standifer, IT Enviroscience, Inc., Secondary Emissions
(June 1980) (EPA/ESED report, Research Triangle Park, NC).
^Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
V-l
V. APPLICABLE CONTROL SYSTEMS
A- BUTADIENE DRYER VENT
One manufacturer controls the butadiene dryer vent (vent A, Fig. III-1) emissions
with a flare,1 whereby a VOC emission reduction of 99% or greater can be attained.2
A refrigerated vent condenser may 'be used as a control device to accomplish a
VOC emission reduction of 82% (see vent A, Table V-l). The recovered butadiene
can be recycled and thereby reduce the quantity of butadiene raw material required.
The installation cost of a flare system very likely is higher than that of a
refrigerated vent condenser and does not provide resource recovery. However,
the higher cost factor may not be a consideration if the flare is needed for
other purposes.
B- CHLORINATION VENT
The VOC emission from the caustic scrubber vent (B) is mainly butadiene, which
can be reduced by 90% by the vent stream being recycled back to the process.
This can be done by releasing 10% of the stream to the atmosphere to purge it
of undesirable organic materials and compressing and condensing the remainder,
decanting the condensate, returning the organic portion to the butadiene dryer
for purge of the inert gases, and sending the aqueous portion to wastewater
treatment. The emissions from vent B can also be sent to a flare, where a reduc-
tion of 99% or greater can be attained.2
C- DICHLOROBUTENE (DCB) DISTILLATION VENT
The VOC emissions from DCB distillation vent (C) is a mixture of low-boiling
VOC, chlorobutadiene, and DCB. These emissions can be controlled by refrigerated
vent condensers at each of the distillation steps. The combined emission reduction
is estimated to be 95%. The emissions from vent C can also be sent to a flare,
where a reduction of 99% or greater can be attained.2
D- ISOMERIZATION AND DISTILLATION VENT
The emissions from the isomerization and distillation vent (D) are a mixture of
low-boiling VOC, chlorobutadienes, and DCBs. These emissions can be controlled
by a refrigerated vent condenser and will effect a 75% reduction of VOC. The
emissions from vent D can also be sent to a flare, where an emission reduction
of 99% or greater can be obtained.
-------
Table V-l. VOC Emissions from Controlled Sources in Typical Chloroprene Plant
Stream
Designation Control Device
Emission Sources (Fig.III-1) or Technique
Butadiene dryer vent
Chlorination vent
DCB distillation vent
Isomerization and 3,4-DCB recovery vent
Chloroprene stripper vent
Brine stripper vent
g of emission per kg of chloroprene produced.
A
B
C
D
E
F
Refrig.
Recycle
Refrig.
Refrigl
Refrig.
Refrig.
condenser
with 10% purge
condenser
condenser
condenser
condenser
Emission
Reduction
(%)
82
90
95
75
81
81
VOC Emissions
Ratio.
(g/kg)a
0.
0.
0.
0.
0.
0.
0.
220
024
182
036
030
030
522
Rate
(kg/hr)b
2.
0.
1.
0.
0.
0.
5.
16
23
79
35
30
30
13
f
to
Based on 8760-hr/yr operation.
-------
V-3
E- CHLOROPRENE STRIPPER VENT
The VOC emission from the chloroprene stripper vent (Vent E) is mainly chloro-
prene, which can be reduced by 81% by a refrigerated vent condenser.
F- BRINE STRIPPER VENT
The VOC emission from the brine stripper vent (F) is mainly chloroprene and can
be reduced by 81% by a refrigerated vent condenser.
G- STORAGE AND HANDLING, FUGITIVE, AND SECONDARY EMISSIONS
Methods for the control of emissions from storage and handling, fugitive, and
secondary sources for the entire synthetic organic chemicals manufacturing industry
are covered by separate EPA documents.3—5
-------
V-4
H. REFERENCES*
1. W. J. Touhey, E. I. du Pont de Nemours and Co., letter dated Sept. 14, 1979,
in response to EPA request for information on emissions from chloroprene pro-
duction facilities.
2. V. Kalcevic, IT Enviroscience, Inc., Control Device Evaluation. Flares and
the Use of Emissions as Fuels (in preparation for EPA, ESED, Research Triangle
Park, NC).
3. D. G. Erikson, IT Enviroscience, Inc., Storage and Handling (September 1980)
(EPA/ESED report, Research Triangle Park, NC).
4. D. G. Erikson, IT Enviroscience, Inc., Fugitive Emissions (September 1980)
(EPA/ESED report, Research Triangle Park, NC).
5. J. J. Cudahy and R. L. Standifer, IT Enviroscience, Inc., Secondary Emissions
(June 1980) (EPA/ESED report, Research Triangle Park, NC).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
VI-1
VI. IMPACT ANALYSIS
The environmental impact from application of the described control systems in
the typical plant would be a VOC emission reduction of 457.3 Mg/yr, as is shown
in Table VI-1.*
*Storage and handling, fugitive, and secondary emissions are not included.
-------
A-l
APPENDIX A
Table A-l. Physical Properties of 1,3-Butadiene
Synonyms
Molecular formula
Molecular weight
Physical state
Vapor pressure
Vapor specific gravity
Boiling point
Melting point
Density
Water solubility
Erythreno, biethylene, bi-
vinyl, butadiene, cx-[?>-butu-
diene, divinyl, pyrrolylene,
vinylethylene
C4H6
54.09
Gas
225.3 kPa at 25°C
1.87
-4.5°C
-109.91°C
0.621 at 20°C/4°C
Insoluble
*From: J. Dorigan et al., "1,3-Butadiene," p. Al-150 in Scoring of Organic
Air Pollutants. CTJemTstry, Production and Toxicity of Selected Synthetic
Organic Chemicals (Chemicals A-C), MTR-7248, Appendix II, Rev. 1, MITRE Corp.,
McLean, VA(September 1976).
-------
A-2
Table A-2. Physical Properties of 2-Chloro-l,3-Butadiene
Synonyms
Molecular formula
Molecular weight
Physical state
Vapor pressure
Vapor specific gravity
Boiling point
Melting point
Density
Water solubility
2-Chlorobutadiene-l , 3 , 3-chloroprene ,
chloroprene
88.54
Liquid
28.7 kPa at 25°C
3. Ob
59.4°C
0.9583 at 20°C/4°C
Slight (<10 g/liter of HO)
*From: J. Dorigan et al., "Chloroprene," p. AI-282 in Scoring
of Organic Air Pollutants. Chemistry, Production and Toxicity
of Selected Synthetic Organic Chemicals (Chemicals A-C),
MTR-7248,'Appendix II, Rev. 1, MITRE Corp., McLean, VA
(September 1976).
-------
B-l.
APPENDIX B
EXISTING PLANT CONSIDERATIONS
A. DATA SOURCES
Tables B-l and B-2 represent the data on sources of emissions obtained from
industry;1—3 however, there is uncertainty about some of the data
received.1—5 (See Table B-l footnote f and Table B-2 footnote d.) Assuming
that the emission ratios from Du Font's chloroprene plant at Victoria, TX, are
the same as those from the La Place, LA, plant the total emissions from
industry was 86 Mg/yr in 1978.
B. RETROFITTING CONTROLS
The industry appears to be adequately controlled, as is indicated by Tables B-l
and B-2. Additional reduction in VOC emissions may be achieved by reducing
possibly excessive in-leakage air in vacuum operations. One plant2—4 appears
to have less emissions because of possible use of a catalyst that allows less
severe conditions and less HC1 generation. If the other plant could be con-
verted to take advantage of this, it would further reduce emissions.
-------
B-2
Table B-l. Control Devices and VOC Emissions from Denka (Houston, TX)
Chloroprene Plant3
Emission Sources
Butadiene dryer
Caustic scrubber ,
Q
(chlorinator vent)
High boilers vent
(DCS distillation vent)
Isomerization section vent
Control Device
or Technique
None
Caustic scrubber
Refrig. condensers (2)
plus water scrubber
Refrig. condensers (2)
Emission
Reduction
ND6
96.5
99.5
Emissions
Ratio
(g/kg)b (M
0.248
0.237f
0.128
0.584
Rate
.g/yr_L,
8.3
8.0f
4.3
19.6
Chloroprene recovery and
brine stripper vent
plus oil scrubber
Oil absorber
100'
1.20
40.2
See ref 1.
g of emission per kg of Chloroprene produced.
CBased on 8760-hr/yr operation at capacity.
Items in parentheses indicate equivalent vents in typical plant.
ND = no data.
Emission stated to be 100% butadiene.
gRecovery of 100% is questionable; uncontrolled emission is 72.1 g/kg.
-------
B-3
Table B-2. Control Devices and VOC Emissions from Du Pont (Laplace, LA)
Chloroprene Plant3
Emission Sources
Butadiene dryer
Synthesis*3
(chlorination vent)
Crude storage vent
Jet vent scrubber (DCB
distillation vent)
Refined storage vent
Isomerization vent
(isomerization and
distillation vent)
Chloroprene stripper vent
Brine stripper
Control Device
or Technique
Flare
Re frig, condenser
Refrig. condenser
Refrig. condenser
Refrig. condenser
Refrig. condenser
Refrig. condenser
Emission
Reduction
(%)
100
94
93
94
94
NDf
ND
Emissions
Ratio
(g/kg)b
d
0.006
0.299
0.0008
0.0083
0.0034
0.0108
0.328
R:ito
(Mg/yr)C
d
0.6
28.6
0.1
0.8
0.4
1.0
31.5
See refs 2 and 3.
b
9 of emission per kg of chloroprene produced.
c
Based on 8760-hr/yr operation at capacity.
No vent reported.
B '
Items in parentheses indicate equivalent vent in typical plant.
ND = no data.
-------
B-4
C. REFERENCES*
1. A. J. Meyer, Denka Chemical Corp., letter dated Mar. 26, 1979, in response
to EPA request for information on emissions from chloroprene production facilities-
2. W. J. Touhey, E. I. du Pont de Nemours and Co., letter dated Sept. 14, 1979,
in response to EPA request for information on emissions from chloroprene pro-
duction facilities.
3. H. A. Smith, E. I. du Pont de Nemours and Co., letter dated Nov. 28, 1978,
in response to EPA request for information on emissions from chloroprene pro-
duction facilities.
4. Telephone conversation of S. W. Dylewsi, IT Enviroscience, Inc., with W. J. Touhey<
E. I. du Pont de Nemours and Co., Nov. 8, 1979.
5. Telephone conversation of S. W. Dylewski, IT Enviroscience, Inc., with A. J. Meyer/
Denka Chemical Corp, Dec. 6, 1979.
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
7-i
REPORT 7
BUTADIENE
R. L. Standifer
IT Enviroscience
9041 EKecutive Park Drive
Knoxville, Tennessee 37923
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
September 1980
This report contains certain information which has been extracted from the
Chemical Economics Handbook, Stanford Research Institute. Wherever used, it
has been so noted.The proprietary data rights which reside with Stanford
Research Institute must be recognized with any use of this material.
-------
7-iii
CONTENTS OF REPORT 7
Page
I- ABBREVIATIONS AND CONVERSION FACTORS 1-1
II- INDUSTRY DESCRIPTION II-l
A. Reason for Selection II-l
B. Usage and Growth II-l
C. Domestic Producers II-4
D. Reference II-8
HI. PROCESS DESCRIPTION III-l
A. Introduction III-l
B. Houdry Process for Dehydrogenation of n-Butane III-~
C. Oxidative Dehydrogenation of n-Butenes III-
D. Extraction from Ethylene Plant By-Product Streams III- 1
E. References , III-..6
IV. EMISSIONS AND APPLICABLE CONTROL SYSTEMS IV-1
A. General IV-1
B. Dehydrogenation of n-Butane (Houdry Process) IV-5
C. Oxidative Dehydrogenation of n-Butenes IV-6
D. Extraction from Ethylene Plant By-Product Streams IV-7
E. References Iv~8
APPENDICES OF REPORT 7
Page
A- PHYSICAL PROPERTIES OF BUTADIENE A-l
B- FUGITIVE-EMISSION FACTORS B-l
c- LIST OF EPA INFORMATION SOURCES C-l
D- EXISTING PLANT CONSIDERATIONS D-l
-------
7-v
TABLES OF REPORT 7
Number Page
II-l Butadiene Usage and Growth Rate II-2
H-2 Estimated Supply of Butadiene for 1983 H-3
II-3 Butadiene Capacity II-5
III-l Typical Composition of n-Butane Dehydrogenation Reactor Effluent III-4
III-2 Typical Composition of n-Butane Oxidative Dehydrogenation Reactor 111-10
Effluent
III-3 Butadiene Yields from Ethylene Production Processes 111-12
III-4 Typical Composition of Ethylene Plant C By-Product Stream from 111-12
Naphtha Feedstock
IV- l Uncontrolled and Controlled VOC Emissions from Dehydrogenation IV- 2
of n-Butane
*V-2 Uncontrolled and Controlled VOC Emissions from Oxidative IV-3
Dehydrogenation of n-Butenes
IV-3 Uncontrolled and Controlled VOC Emissions from Butadiene IV-4
Extraction from Ethylene By-Product Streams
A-l Physical Properties of 1 ,3-Butadiene A-l
D~l Control Devices Used by Butadiene Producers
D £»
D~2 Firestone Emissions
D~3 Firestone Oxo Reactor Effluent Composition
D~4 Estimates of Emission Ratios for the Exxon By-Product Butadiene D-7
Process
FIGURES OF REPORT 7
*I~1 Locations of Plants Manufacturing Butadiene II-6
Hl-1 Flow Diagram of Model Plant for n-Butane Dehydrogenation Process III-5
IH-2 Flow Diagram of Model Plant for Oxidative Dehydrogenation Process III-9
Hl-3 Flow Diagram for the Extraction of Butadiene from Ethylene 111-14
By-Product Streams
-------
1-1
ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements used in agency documents in metric
units. Listed below are the International System of Units (SI) abbreviations
and conversion factors for this report.
To Convert From
Pascal (Pa)
Joule (J)
Degree Celsius (°C)
Meter (m)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter (rn3)
Cubic meter/second
-------
II-l
II. INDUSTRY DESCRIPTION
A. REASON FOR SELECTION
The production of butadiene was selected for study because preliminary estimates
indicated that emissions of volatile organic compounds (VOC) from some current
processes are high.
Although two isomers of butadiene occur (1,2 and 1,3), only 1,3-butadiene is of
significant commercial interest. (The term butadiene in this report refers to
the 1,3 isomer unless 1,2-butadiene is specifically designated.) Butadiene is a
vapor at ambient conditions (see Appendix A for pertinent physical properties).
B- USAGE AND GROWTH1
Table II-l shows the major butadiene uses and expected growth rates. The predomi-
nant uses are for the manufacture of elastomers, adiponitrile/HMDA (intermediates
for certain nylon manufacturing processes), styrene-butadiene copolymer latexes,
and ABS (acrylonitrile-butadiene-styrene) resins. Tires and tire products account
for approximately half of the butadiene consumed. In addition to synthetic rubber
products, it is used for carpet fibers, carpet-back coatings, paper coatings,
piping, adhesives, and molded mechanical and electrical parts.
The domestic butadiene production capacity by the end of 1978 was approximately
1825 Gg/yr. Domestic production in 1978 was 1598 Gg, or about 88% of year-end
capacity. By the end of 1978 domestic heavy-liquid ethylene plants accounted
for 56% of available domestic production capacity and net imports supplied 13%
of the total demand. By 1981 imports and by-product butadiene from domestic
ethylene plants are expected to account for 85% or more of the total demand.
(Before 1968 almost all domestic butadiene requirements were supplied by domestic
production, with dehydrogenation of n-butane and n-butenes accounting for 85% or
more of the total.)
Table II-2 gives estimates for 1983 of butadiene supply sources. Production
capacity by the dehydrogenation of n-butane and n-butenes is currently estimated
at about 860 Gg/yr. Much of this equipment has been or will be shut down or
converted to the extraction of ethylene by-product butadiene; however, the capa-
bility of producing butadiene by dehydrogenation at 45 to 60% of current dehydro-
genation capacity will apparently be maintained to meet potential demand through
1981.
-------
II-2
Table II-1. Butadiene Usage and Growth Rate*
End Use
Elastomers
SBR
Polybutadiene
Polychloroprene
Nitrile
Adiponitrile/HMDA
Styrene-butadiene copolymer latexes
ABS (acrylonitrile-butadiene-styrene) resins
Other polymers containing butadiene monomer
Other uses
Average
1978
Production
(%)
44.3
19.3
6.8
2.6
10.8
7.5
5.9
1.8
1.1
Projected Average
Growth Rate (%/yr)
for 1978--1983__-
1.5--2.5
2.5 — 3.5
2.5 — 3.5
2.0--3.0
4.0--5.0
3.0--4.0
5.0--6.0
9.5--10.0
7.0--10.0
2.5 — 3.5
*See ref. 1.
-------
II-3
Table II-2. Estimated Supply of Butadiene for 1983*
Quantity
Source
Percent of
Total
By-product production
from domestic ethylene plants
Net imports
Dehydrogenation of n-butane
and n-butenes
Total supply
*See ref. 1.
1224 to 1356
317 to 408
336 to 381
1923 to 2100
68 to 69
9 to 16
16 to 22
100
-------
II-4
C. DOMESTIC PRODUCERS
As of 1977, 15 manufacturers were producing butadiene in the United States
and Puerto Rico at 19 locations. Table II-3 lists the producers, locations,
capacities, and processes,- Fig. II-l shows the plant locations.
The companies producing butadiene are listed below.
1. Atlantic Richfield Company
Until 1976 all butadiene was produced by dehydrogenation of n-butane (Houdry
process). Now it is produced from only ethylene plant by-product streams. Most
of the butadiene produced is sold.
2. Copolymer Rubber and Chemical Corporation
Butadiene is produced by oxidative dehydrogenation of refinery butylenes and is
all captively consumed for SBR and nitrile elastomer production.
3. Dow Chemical Company
Butadiene is extracted from ethylene plant by-product streams. More than 95% is
captively consumed for ABS and styrene-butadiene latex production at six domestic
locations.
4. El Paso Products Company
Butadiene is produced by dehydrogenation of n-butane (Houdry process) and sold.
A plant to produce butadiene by extraction from ethylene by-product streams is
being constructed near Corpur Christi, TX. The plant will utilize dimethyl
formamide for extractive distillation.
5. Exxon Corporation
Butadiene is extracted from ethylene plant by-product streams and sold.
6. Firestone Tire and Rubber Company
Butadiene is produced from n-butane and n-butenes, using Houdry and oxidative
dehydrogenation processes, and is captively consumed to produce SBR, polybuta-
diene, and styrene-butadiene latex.
7. Mobil Corporation
Butadiene is extracted from ethylene plant by-product streams and sold.
-------
II-5
Table II-3. Butadiene Capacity*
Producer
Capacity
(Gg/yr)
Process
Atlantic Richfield, Channelview, TX
Copolymer Rubber & Chemical, Baton
Rouge, LA
Dow Chemical, Freeport, TX
El Paso Products, Odessa, TX
Exxon, Baton Rouge, LA
Firestone Tire & Rubber, Orange, TX
Mobil, Beaumont, TX
Monsanto, Chocolate Bayou, TX
Neches Butane Products, Port Neches, TX
Petro-Tex Chemical, Houston, TX
Phillips Petroleum, Borger, TX
Puerto Rico Olefins, Penuelas, PR
Shell Chemical, Deer Park, TX
Standard Oil (Indiana) Alvin, TX
Union carbide, Seadrift, TX
Union Carbide, Taft, LA
Union Carbide, Texas City, TX
Union Carbide, Penuelas, PR
204
73
39
91
154
104
36
55
363
>227
131
118
82
20
25
30
70
1821
From ethylene plant
by-product C ' s
n-Butenes oxidative
dehydrogenation
From ethylene plant
by-product C 's
By n-butane dehydro-
genation (Houdry
process)
From ethylene plant
by-product C 's
By n-butane dehydro-
genation (Houdry
process),
n-butenes oxidative
dehydrogenation
From ethylene plant
by-product C 's
Same as above
From ethylene plant
by-product C.'s
n-butenes oxadative
dehydrogenation
Same as above
Same as above
From ethylene plant
by-product C^'s
(operation dis-
continued in 1978)
Same as above
Same as above
Same as above
Same as above
Same as above
Same as above
*See ref. 1.
-------
11-6
1,9,11,14 .^- «!j__
1. Atlantic Richfield Co., Channelview, TJ
2. Copolymer Rubber & Chemical Corp.,
Baton Rouge, LA
3. Dow Chemical Co., Bay City, MI*
4. Dow Chemical Co., Freeport, TX
5. El Paso Products Co., Odessa, TX
6. Exxon Chemical Co., Baton Rouge, LA
7. Firestone Tire & Rubber Co.,
Orange, TX
8. Mobil Chemical Co., Beaumont, TX
9. Monsanto Company, Chocolate Bayou, TX
*Operation discontinued.
10. Neches Butane Products Co.,
Port Neches, TX
11. Petro-Tex Chemical Corp.,
Houston, TX
12. Phillips Petroleum Co.,
Boryer, TX
13. Puerto Rico Olefins Co.,
Penuelas, PR*
14. Shell Chemical Co., Deer Park/
15. Standard Oil Co., Alvin, TX
16. Union Carbide Corp., Seadrift/
17. Union Carbide Corp., Taft, LA
•18. Union Carbide Corp., Texas Ci*
19. Union Carbide Corp., Penuelas,
Fig. ll-l. Locations of Plants Manufacturing Butadiene
-------
II-7
8. Monsanto Company
Butadiene is extracted from ethylene plant by-product streams. More than 95% is
captively consumed for ABS resin manufacture at two domestic locations.
9. Neches Butane Products Company
Butadiene is produced by the oxidative dehydrogenation of n-butenes and by extrac-
tion from ethylene plant by-product streams. Butadiene is consumed by B. F. Good-
rich Company and Texas—U. S. Chemical Company (joint owners of Neches Butane
Products Company) to produce SBR, polybutadiene, nitrile elastomers, ABS resins,
and styrene-butadiene latex.
10. Petro-Tex Chemical Corporation
Butadiene is extracted from ethylene plant by-product streams and produced by
oxidative dehydrogenation of n-butenes. Until early 1977 butadiene was also
produced from n-butane by the Houdry process. The butadiene product is sold.
11. Phillips Petroleum Company
Butadiene is extracted from ethylene plant by-product streams. Butadiene is
captively consumed to produce polybutadiene thermoplastic elastomers and
K-Resin®.
12. Puerto Rico Olefins Company
Butadiene is extracted from ethylene plant by-product streams and sold.
13. Shell Chemical Company
Butadiene is extracted from ethylene plant by-product streams and is primarily
sold (20% is captively consumed)'.
14. Standard Oil Company (Indiana)
Butadiene is extracted from ethylene plant by-product streams and sold.
15. Union Carbide Corporation
Butadiene is extracted from ethylene plant by-product streams and primarily sold.
-------
II-8
D. REFERENCE*
1. S. L. Soder, "Butadiene," pp. 620.5021A—620.5024D in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park, CA (June 1977)
^Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
III-l
III. PROCESS DESCRIPTION
A- INTRODUCTION
Butadiene is produced in the United States by the dehydrogenation of n-butane
(Houdry process), -by the oxidative dehydrogenation of n-butenes, and as a by-
product of ethylene manufacture. As the ethylene plant by-product streams con-
taining butadiene also generally contain significant quantities of n-butane and
n-butenes (see Table III-4 in Sect. D for typical composition), a number of pro-
ducers currently utilize combined processes, extracting the contained butadiene
and producing additional butadiene by dehydrogenation of contained n-butenes or
n-butane.2""5
Most routes require final purification of butadiene by extraction or by extrac-
tive distillation. Five different butadiene extraction or extractive distil-
lation processes are used commercially; each uses a different extraction solvent.
The processes as identified by the company licenser and the type of solvent used
are as follows:
Nippon Zeon Co., Ltd. — dimethyl formamide (DMF)
Phillips Petroleum Company — furfural
Shell Chemical Company -- acetonitrile
Union Carbide Corporation -- dimethyl acetamide
(No licenser) -- cuprous ammonium acetate solution (CAA)
The production of butadiene by the dehydrogenation of n-butane and n-butenes has
been steadily decreasing as a percentage of the total butadiene production since
more butadiene has become available from ethylene plants. This trend will con-
tinue through 1983. By that time dehydrogenation processes are expected to be
used for only 19 to 24% of the total domestic butadiene production.
Historically, butadiene has also been produced in the United States from ethanol
feedstock and as a by-product of petroleum coke production. Neither process is
now being used in the United States.
Virtually all butadiene production in Western Europe and Japan is based on ethy-
lene by-product recovery. Houdry units (n-butane dehydrogenation) are currently
operating in Argentina, Brazil, Mexico, and the USSR. The only n-butenes
-------
III-2
dehydrogenation unit outside the United States is located in Canada. Plants
that produced butadiene from ethanol in India and in the People's Republic of
China have reportedly been, shut down.
B. HOUDRY PROCESS FOR DEHYDROGENATION OF n-BUTANE
1. Basic Process
The dehydrogenation of n-butane proceeds through 1-butene and 2-butene to
1,3-butadiene and 1,2-butadiene:
-H,
(1-butene)
-H,
CH2=CH-CH=CH2
(1,3-butadiene)
CH -CH=CH-CH
(2-butene)
CH =C=CH-CH
^ >3
(1,2-butadiene)
The adjoining double bonds in 1,2-butadiene are unstable at elevated temperatures
and thus 1,2-butadiene is formed only in trace amounts. Butane may also undergo
various degradation reactions.
CH. + CH =CH-CH
4 ^ J
(methane) (propylene)
2 CH =CH + H2
(ethylene)
CH3-CH3
(ethane)
(ethylene)
Equilibrium constants for n-butane degradation to methane, ethane, ethylene, and
propylene are larger than for its dehydrogenation, and a catalyst is essential
for increasing the rate of dehydrogenation.
Finally, acetylene compounds are formed either through recombination of radicals
or by the dehydrogenation of propylene and butenes. Possible acetylenes are
methylacetylene, ethylacetylene, dimethylacetylene, vinylacetylene, and diacetyl-
ene. These acetylenes are present in butane dehydrogenation products in only
-------
III-3
very small or trace quantities. However, because they interfere with the subse-
quent polymerization of butadiene and because their similarity to other C hydro-
carbons makes their separation difficult, even amounts as low as 100 ppm can be
objectionable.
Dehydrogenation of n-butane to butadiene in the Houdry process requires tempera-
tures of about 600°C and an n-butane partial pressure of 15 to 35 kPa. The re-
action takes place in a fixed-bed reactor over a chromia-alumina catalyst. Per-
pass conversion is about 30%, with butylenes and unreacted butane being recycled
for further reaction. Overall yields are reportedly 50 to 55%, requiring about
2 kg of butane per kg of butadiene produced. The typical composition of the
reactor effluent, before product separation and purification, is shown in
Table III-l.3
The process flow diagram in Fig. III-l represents a typical n-butane dehydro-
genation (Houdry) process.2"" Butane feed (Stream 1) and recycle butane and
butenes (Stream 23) are combined and preheated to 600°C in a fuel-fired feed
preheater and passed through three or four of seven parallel catalytic reactors
(Stream 2) initially at a temperature of 650°C. The reaction is endothermic and
the catalyst beds cool gradually. The seven reactors are operated on a cyclic
basis, with three or four reactors being regenerated at all times. During the
regeneration phase the reactors are first steam purged to the quench tower (steam
purge is not shown) and then blown with air preheated to 650°C (Stream 3>; as a
result coke and deposited hydrocarbons from the catalyst beds are burned, thereby
reheating the beds to 650°C. The reactors are evacuated before air regeneration
and before being returned to service. The hot regeneration air containing a
significant concentration of VOC is a primary emission source from the process
(Stream 4) and is passed through a waste-heat-recovery boiler before it is vented
to the atmosphere through an emission control device (Vent C). Flue gas from
the feed preheater is formed from the combustion of gaseous fuels and is vented
without control (Vents A).
The hot process gas from the reactors (Stream 5) (see Table III-l for typical
composition) is cooled to approximately 200°C in the oil quench tower. The
quench oil is cooled (Stream 6) before recirculation. Following further cooling
to approximately 50°C the process gas (Stream "7) is compressed to about 1.1 MPa.
-------
III-4
Table III-l. Typical Composition of ri-Butane
Dehydrogenation (Houdry) Reactor Effluent
(Fig. III-l, Stream 5)*
Component
Hydrogen
Carbon oxides
Methane
Ethane
Ethylene
Propane
Propylene
n-Butane
Isobutane
Isobutene
1-Butene
Trans -2-butene
Cis-2-butene
1 ,3-Butadiene
C "s hydrocarbons
1 ,2-Butadiene
Propadiene
Methylacetylene
Ethylacetylene
Dimethylacetylene
Vinylacetylene
Molecular
Formula
H2
co, co2
CH,,
4
C_H,_
2 6
C2H4
C3H8
C3H6
C H
4 10
C H
4 10
C4H8
C4H8
C4H8
C4H8
C4H6
C4H6
C3H4
C3H4
C4H6
C4H6
CdH4
Composition
(wt %)
1.4
0.7
0.7
0.3
0.6
0.1
1.0
40.5
1.0
4.3
12.7
13.6
11.3
11.1
0.6
Trace
Trace
Trace
Trace
Trace
Trace
100.0
*See ref 3.
-------
I ••
b>'
<&
— — •
'<&> «T«^<^rS' (">
-P0 T^IL, >Y
Cl
<£> J
TO Hi^a-
OOlLfcZ^) C-OLUvjlKj
f
^X
UEf-US
T
^
JAfJK
Fig. III-l. Flow Diagram of Uncontrolled Model Plant for Production of Butadiene by
_n-Butane Dehydrogenation (Houdry) Process
-------
III-6
Following compression (Stream 8), the C and heavier compounds are absorbed in a
petroleum oil fraction in the hydrocarbon absorption column. The unabsorbed
"lights" (C compounds and lighter) supply the process fuel requirements (Stream 9)
The absorbed organics (Stream 10) are then removed from the absorption oil in
the hydrocarbon stripping column, and the stripped petroleum absorption oil
(Stream 11) is recirculated. Flue gas from the stripper reboiler heater (Vent B)
is the only other normal process emission source.
The remainder of the process consists of a series of fractionation columns and a
furfural extractive distillation section with no point emission sources. The
overhead stream from the hydrocarbon stripping column (Stream 12) passes to the
light-ends column, where residual C_ and lighter compounds (Stream 13) are removed
and combined with the overhead stream (Stream 9) from the hydrocarbon absorption
column. The C and heavier compounds (Stream 14) pass to the splitter column,
where a rough n-butane--butadiene separation is made. In addition to butadiene
the overhead stream (Stream 15) contains most of the 1-butene, isobutene, and
isobutane and approximately 5% of the n-butane. The bottoms stream (Stream 16)
contains most of the n-butane, trans-2- and cis-2-butenes, and all of the C<. and
heavier compounds (including residual absorber oil and polymers formed in the
process).
The overhead stream (Stream 15) from the splitter column passes to the furfural
extractive distillation column, where most of the remaining butanes and butenes
are separated from butadiene. This separation is difficult to attain by distil-
lation alone (due to unfavorable relative volatilities) and extractive distilla-
tion techniques are used in almost all commercial butadiene processes. Butadiene
(Stream 18) is removed from the rich solvent stream (Stream 17) in the butadiene
stripping column and then passes to the butadiene rerun column for final purifica-
tion, where polymer, some 2-butene, and traces of acetylenes and 1,2-butadiene
are removed in the bottoms (Stream 20). The overhead stream (Stream 19) from
the rerun column, the refined butadiene product, is stored in pressurized spheres
for distribution.
The bottoms from the splitter column (Stream 16) and from the butadiene rerun
column (Stream 20) are combined and fed to the high-boilers column, where C and
-------
III-7
heavier components, polymer, and residual absorber oil are separated. The bot-
toms fraction (Stream 24) may be used as fuel or further separated into other
product fractions.
The overhead streams from the high-boilers column (Stream 21) and from the extrac-
tive distillation column (Stream 22) are composed of butanes and butenes and are
combined and recycled to the dehydrogenation reactor (Stream 23). After the
stripped furfural solvent from the butadiene stripping column (Stream 25) is
cooled, most of it is recycled to the butadiene extractive distillation column
(Stream 26).
A small portion of the circulating furfural solvent (Stream 27) is continuously
processed in the furfural purification column to remove accumulated polymer,
with the purified furfural (Stream 28) being returned to the cycle. Furfural
makeup (Stream 29) is introduced as necessary to compensate for losses from the
cycle. Polymer removed by the furfural purification column (Stream 30) is dis-
charged as a waste stream (Source K).
Water is phase separated from the condensed overhead streams from the extractive
distillation column (Stream 32), the butadiene stripping column (Stream 33), and
the butadiene rerun column (Stream 34) and discharged as wastewater (Source M).
2
2. Process Variations
The primary process variations are in the solvent systems used in the extraction
or extractive distillation sections. Furfural, acetonitrile, and cuprous ammonium
acetate solution (CAA) are used in the current n-butane dehydrogenation processes
and in those in stand-by status. The use of alternate solvent systems results
in a number of corresponding variations in purification and solvent recovery
steps that may significantly affect process emissions.
The recycle feed stream (Stream 23) may be processed to either remove butenes or
to convert them to butanes before it is recycled.
C. OXIDATIVE DEHYDROGENATION OF n-BUTENES
1. Basic Process
The oxidative dehydrogenation of n-butenes (1- and 2-butenes) proceeds through
3 ~
the following primary reaction:
-------
III-8
CH2=CH-CH2-CH3
(1-butene)
or + H00 ^ CH =CH-CH=CH, •+ H_0
2 £•*,£•
CH3-CH=CH-CH3
(2-butene)
Per-pass conversions of 75 to 85% and overall yields of 80 to 90% are obtained;
this corresponds to consumption of 1.1 to 1.3 kg of n-butenes per kg of butadiene
formed. With higher product yields the quantities of degradation products formed
are correspondingly less than from the butane dehydrogenation process.
The process flow diagram in Fig. III-2 represents a typical n-butene oxidative
dehydrogenation process.2'3' n-Butene feed (Stream 1), recycle butenes (Stream 23)'
and steam (Stream 3) are preheated in fuel-fired preheaters and mixed with com-
pressed air (Stream 2). The combined stream (Stream 4) is passed through fixed-bed
catalytic reactors at 500 to 550°C. One catalyst system that is used is a mixture
of oxides of tin, bismuth, and boron, with phosphoric acid. The reaction is
exothermic and the reactors are operated continuously.
A typical composition of the reactor effluent (Stream 5) is shown in Table III-2.
Although the remaining process is similar to the corresponding portion of the
Houdry process, significant differences in reactor effluent composition result
in the following differences in downstream process conditions and requirements;
a. Significant quantities of water (resulting from the introduction of steam
and from the formation of water in the reaction) are present. The water,
which is removed before compression, results in the generation of additional
wastewater (Streams 6 and 7).
b. Air (nitrogen and^ excess oxygen) is removed from the process stream by the
hydrocarbon absorption column and vented (Stream, 9) to an emission control
device (Vent D). Fuel gas components (C, compounds and lighter) are present
in relatively low concentrations.
c. The quantity of recycle feed (Stream 23) is less than that from the Houdry
process because of the more complete conversion per pass attained.
-------
Fig. II1-2. Flow Diagram of Uncontrolled Model Plant for Production of
n-Butenes Oxidative Dehydrogenation Process
-------
111-10
Table III-2. Typical Composition of n-Butene Oxidative
Dehydrogenation Reactor Effluent (Fig. III-2, Stream 5)*
Component
Oxygen
Nitrogen
Carbon oxides
Water
Methane
Vs .
Vs
n-Butane
Isobutane
Isobutene
1-Butene
Trans -2-butene
Cis-2-butene
1,3-Butadiene
C5's
1 , 2-Butadiene
Propadiene
Methylacetylene
Ethylacetylene
Dimethylacetylene
Vinylacetylene
Molecular
Formula
°2
N2
co, co2
H2°
CH4
C4H10
C4K10
C4H8
C4H8
C4H8
C4H8
C4H6
C4H6
C3H4
C3H4
C3H4
C4H6
C4H4
Composition
(wt %)
1.0
15.8
3.0
65.0
0.1
0.3
0.4
0.4
0.6
1.1
1.9
1.7
1.4
7.2
0.1
Trace
Trace
Trace
Trace
Trace
Trace
*See ref 3.
-------
III-ll
The remaining process steps are essentially the same as the corresponding steps
in the Houdry process, and identical stream designations are used.
2
2. Process Variations
The alternative extractive distillation solvents listed in Sect. III-A may be
used.
With smaller quantities of butenes and very little butane present a splitter
column may be omitted. In this case the recycled butenes are separated from
butadiene by the extractive distillation column.
The recycle stream (Stream 23) may be further processed to remove isobutene and
butanes, with only n-butenes recycled to the process.
D- EXTRACTION FROM ETHYLENE PLANT BY-PRODUCT STREAMS
1. Basic Process
The amount of butadiene produced during ethylene manufacture is dependent on
both the type of feedstock and the severity of the cracking operation.6 Table III-3
summarizes typical butadiene yields from ethylene production based on various
feedstocks. The increasing use of heavy feedstocks (naphthas and gas oils) for
ethylene production has resulted in the production of much larger quantities of
butadiene from this source. A typical composition of a C^ by-product stream
from an ethylene plant using naphtha feedstocks is shown in Table III-4. The
process is similar to the separation/purification portions of the dehydrogenation
processes discussed in Sects. III-B and C; however, the following significant
differences, resulting from differences in composition (see Tables III-l and
III-4), are noted:
a. Because almost all the components heavier or lighter than C4 compounds have
been removed by the ethylene plant fractionation columns, further separation
of these components is not required in the butadiene process.
b. Because the concentrations of acetylenes (methylacetylene, dimethylacetylene,
vinylacetylene, ethylacetylene) present in the C4 streams are much higher
than those formed in the dehydrogenation processes, more extensive provisions
for acetylene removal are required.
-------
111-12
Table III-3. Butadiene By-Product Yields from
Ethylene Production Based on Various Feedstocks
Yield Ratiob
Feed (kg/100 kg)
Ethane 1.0—2.0
Refinery off-gas 5.0
Propane 5.0—8.5
n-Butane 7.0—8.5
Naphthas 13.0—18.0
Gas oils 17.6—24.7
SSee ref. 1.
kg of butadiene per 100 kg of ethylene produced.
Table III-4. Typical Composition of Ethylene Plant
C By-Product Stream from Naphtha Feedstock*
4 J
Component
n-Butane
Isobutane
Isobutene
1-Butene
Trans-2-butene
Cis-2-butene
1, 3-Butadiene
1,2-Butadiene
Propadiene
Methyl acetylene
Ethyl acetylene
Dimethyl acetylene
Vinyl acetylene
Molecular
Formula
C4H10
C4H10
C4H8
C4H8
C4H8
C4H8
••j CJ
C4H6
C4H6
C3H4
C3H4
C.H.
4 6
C.H
4 6
C.H .
4 4
Composition
(wt %)
6.8
1.6
29.0
9.6
7.5
4.7
39.3
0.08
0.53
0.65
0.05
0.08
0.11
100.0
*See ref. 3.
-------
111-13
Referring to Fig. II1-3, the C feed (Stream 1) and hydrogen (Stream 2) are com-
bined and passed through a fixed-bed hydrogenation reactor, where approximately
95% of the contained acetylenes are converted to olefins. Typical hydrogenation
conditions include a metal oxide catalyst, a temperature of 60 to 70°C, and a
pressure of about 800 kPa. The catalyst must be periodically regenerated (approxi-
mately 4 times per year) by preheated air and steam (Stream 3) being passed over
the catalyst bed, effectively burning the deposited organics. During regeneration
the reactor effluent is vented (Vent A). Combustion products from fuel gas burned
in the regeneration heat furnace are also vented (Vent B) during regeneration.
Following hydrogenation the C4 stream passes to the extractive distillation column,
where most of the butanes and butenes are separated from butadiene. The butane-
butene overhead stream from the extractive distillation column (Stream 5) is
transferred to storage. This stream may be removed as a by-product stream or be
converted to additional butadiene by dehydrogenation. Butadiene and residual
impurities are removed from the rich solvent (Stream 6) in the butadiene stripping
column and pass (Stream 7) to the methylacetylene column, where most of the residual
acetylenes not converted in the acetylene hydrogenation reactors are vented (Source C)
to an emission control device.
The bottoms stream from the methylacetylene column (Stream 9) is given a final
purification by the butadiene rerun column, where polymer, some 2-butene, and
traces of acetylene and 1,2-butadiene are removed as a residue stream (Source L).
Most of the stripped furfural solvent from the butadiene stripping column (Stream 10)
is recycled to the extractive distillation column (Stream 11). A small portion
of the circulating furfural solvent (Stream 12) is continuously processed in the
furfural purification column for removal of accumulated polymer, with the purified
furfural (Stream 13) being returned to the cycle. Furfural makeup (Stream 14)
is introduced as necessary to compensate for losses from the cycle. Polymer
removed by the furfural purification column (Stream 15) is discharged as a process
waste stream (Source K).
Water is phase separated from the condensed overhead streams from the extractive
distillation column (Stream 16), the butadiene stripping column (Stream 17), the
methylacetylene column (Stream 18), and the butadiene rerun column (Stream 19)
and is discharged as wastewater (Source M).
-------
ACfcTYUMt
^
M2
A
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T
CJ
flURpURAl,
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r
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I
Fig. Ill-3. Flow Diagram for the Extraction of Butadiene from Ethylene Plant By-Product Streams
-------
111-15
2. Process Variations
The alternative extraction or extractive distillation solvents listed in
Sect. III-A may be used. Emissions from processes using other solvent systems
may differ from those estimated for the model plant.
The contained acetylenes may be removed by solvent extraction and/or extractive
distillation instead of primarily by catalytic hydrogenation to olefins. The
separated acetylenes are generally burned as supplementary boiler fuel or in
flares.
-------
111-16
E. REFERENCES*
1. S. L. Soder, "Butadiene," pp. 620.5021A--620.5024D in Chemical Economics Handbook,
Stanford Research Institute, Menlo Park, CA (June 1977).
2. Texas Air Control Board, 1975 Emission Inventory Questionnaires; see Appendix C.
3. G. E. Haddeland, Butadiene, Report No. 35, A private report by Process Economics
Program, Stanford Research Institute, Menlo Park, CA (March 1968); see also G.
E. Haddeland, Report No. 35A1 (March 1972).
4. R. L. Standifer, IT Enviroscience, Inc., Trip Report for Visit to Arco Chemical
Company, Channelview, TX, August 16, 17, 1977 (data on file at EPA, ESED,
Research Triangle Park, NC).
5. R. L. Standifer, IT Enviroscience, Inc., Trip Report for Visit to Petro-Tex
Corp., Houston, TX, October 18, 1977 (data on file at EPA, ESED, Research
Triangle Park, NC).
6. R. L. Standifer, IT Enviroscience, Inc., Ethylene (Olefins) (in preparation for
EPA, ESED, Research Triangle Park, NC).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
IV-1
IV. EMISSIONS AND APPLICABLE CONTROL SYSTEMS
A- GENERAL
Emissions in this report are usually identified in terms of volatile organic
compounds (VOC). VOC are currently considered by the EPA to be those of a
large group of organic chemicals, most of which, when emitted to the atmosphere,
participate in photochemical reactions producing ozone. A relatively small
number of organic chemicals have low or negligible photochemical reactivity.
However, many of these organic chemicals are of concern ans may be subject to
regulation by EPA under Section 111 or 112 of the Clean Air Act since there
are associated health or welfare impacts other than those related to ozone
formation.
Current domestic butadiene is produced by n-butane dehydrogenation (Houdry process),
by the oxidative dehydrogenation of n-butenes, and by extraction from ethylene
plant by-product streams. With more of the generally lower cost butadiene from
ethylene plant by-product streams becoming available as more heavy-liquid feed-
stocks are used for ethylene production, almost all new butadiene production is
expected to be from this source. Concurrently the resulting excess dehydrogena-
tion capacity will be converted for extraction of by-product butadiene, be placed
in standby status for surge capacity, or be retired.
Estimated ratios (kg of VOC emissions/Mg of butadiene produced) of uncontrolled
and controlled VOC (volatile organic compounds) emissions for the three processes
described in Sects. III-B, C, and D are summarized in Tables IV-1 through IV-3.
The estimates of uncontrolled emissions from normal process vents are based on a
compilation of data from existing sources. The corresponding estimates of
controlled emissions from normal process vents are based on the efficiencies
2--4
reported for control devices used in the butadiene industry or for similar
applications in other process industries.
Storage and handling emissions for all three of the processes shown are approxi-
mately the same. The estimated emission ratios, which are relatively low, are
based on the use of pressurized tanks for the storage of feedstocks, intermediates,
and primary products. The recycle of vapor vented from storage tanks and transfer
operations is common in the industry and is considered to be a normal process
feature.
-------
Table IV-1. Uncontrolled and Controlled VOC Emissions from Butadiene Production by
Dehydrogenation of n-Butane (Houdry Process)
Stream
Designation
Source (Fig. III-2)
Flue gas A,B
Reactor vent C
(regeneration air)
Intermittent process E
emissions
Storage and handling F
Secondary K,M
Fugitive -
Total
Uncontrolled- Emission
Emission Ratio Control Device Reduction
(kg/Mg)a or Technique (%)
0.06
5.5
0.5
0.1
0.15
5.2
11.5
None
Catalytic or 92
thermal oxidation
Elevated flare 95
b
None
None
Detection and repair of 30
major leaks plus
mechanical seals
Controlled-
Emission Ratio
(kg/Mg)a
0.06
0.44
0.03
0.1
0.15
1.3
2.1
kg of VOC per Mg of butadiene produced.
Pressurized storage tanks vented to the process are considered to be normal process conditions, not a
separate emission control.
H
to
-------
Table IV-2. Uncontrolled and Controlled VOC Emissions from Butadiene Production by
Oxidative Dehydrogenation of n-Butenes
Source
Flue Gas
Absorption
column vent
Intermittent
process emissions
Storage and handling
Secondary
Fugitive
Total
Stream
Designation
(Fig- III-2)
A,B,C
D
E
F
k,m
Uncontrolled-
Emission Ratio
(kg/Mg)9
0.06
5.0
0.5
0.1
0.75
5.2
11.6
Control Device
or Technique
None
Catalytic or
thermal oxidation
Elevated flare
b
None
Reactor wastewater
stripper-flare
vented vapor
Detection and repair of
major leaks plus
mechanical seals
Emission
Reduction
0.
c
95
95
70
90
Controlled-
Emission Ratio
(kg/Mg)a
0.06
0.25
0.03
0,1
0.24
0.13
2.0
kg of VOC per Mg of butadiene produced.
Pressurized storage tanks vented to the process are considered a normal process condition, not a
separate emission control.
i
w
-------
Table IV-3. Uncontrolled and Controlled VOC Emissions from Butadiene Production by
Extraction from Ethylene Plant By-Product Streams
Source
Flue gas
Hydrogenation cata-
lyst regeneration
vent
Methylacetylene
column vent
Intermittent
process emissions
Storage and handling
Secondary
Fugitive
Total
Stream
Designation
(Fig. III-3)
A
B
C
E
F
K,M
Uncontrolled-
Emission Ratio
(kg/Mg)a
0.002
0.024
2.1
0.25
0.1
0.15
2.5
5.1
Emission
Control Device Reduction
or Technique (%)
None
None
Incineration or flare 95
Elevated flare 95
None
None
Detection and repair of 90
major leaks plus
mechanical seals
Controlled-
Emission Ratio
(kg/Kg)3
0.002
0.024
0.10
0.015
0.10
0.15
0.6
1.0
kg of VOC per Mg of butadiene produced.
Pressurized storage tanks vented to the process are considered normal process conditions, not a
separate emission control.
H
f
*>•
-------
IV-5
Estimates of potential fugitive emission sources are based on data from existing
facilities. The estimated emission rates were calculated, with the emission
factors shown in Appendix B, for plants annually producing 160 Gg of butadiene.
As with most organic chemical processes, leaks into cooling water can occur,
allowing VOC to escape.
Secondary emissions from wastewater (Source M) were estimated from reported waste-
water rates and the corresponding organic concentrations. Significant quantities
of process residues (polymers) are generated (Source K) and are normally diposed
of by incineration or by landfill, with relatively low emissions of VOC.
Miscellaneous intermittent emissions (Source E) include emissions resulting from
the activation of pressure-relief devices on storage tanks and process equipment
and other emissions occurring during startups, shutdowns, and abnormal situations.
Although average emissions from these sources are relatively low, abnormal situa-
tions can result in high emission rates for relatively short periods of time.
Emissions from these sources are usually controlled by an elevated flare equipped
with steam injection to provide mixing for improved combustion and smoke-free
operation.
Emission sources and the corresponding emission control devices that apply spe-
cifically to the individual processes (i.e., n-butane dehydrogenation, oxidative
dehydrogenation, extraction from ethylene plant by-product streams) are discussed
in Sects. IV-B, C, >and D.
B- DEHYDROGENATION OF n-BUTANE (HOUDRY PROCESS) (FIG. III-l, TABLE IV-1)
The normal process emissions occur from the following sources:
l- Flue Gas (Vents A, B, and C)
Emissions are composed of products generated from the combustion of primarily
gaseous fuels. VOC concentrations are relatively low and the application of
specific emission control devices is not indicated.
2- Dehydrogenation Reactor Vent (Vent D)
Emissions occur during the regeneration phase of the reactor cycle while the
effluent regeneration air is being vented. Although the average VOC concentra-
tion in the vented regeneration air is relatively low (approximately 0.005 wt %),
the extremely large quantity of vented air results in significant VOC emissions.
-------
IV-6
Emissions can be effectively controlled by thermal or catalytic oxidation. One
manufacturer using a proprietary catalytic oxidation process reports a VOC destruc-
tion efficiency of 92% without the addition of auxiliary fuel, attaining an energy
recovery efficiency of 80% from the combustion gas.
A catalytic oxidation system that processes the entire regeneration air stream
reportedly attains a VOC removal efficiency of approximately 50%.
Thermal oxidation is a potential alternative control method, possibly providing
higher VOC removal efficiencies than the catalytic oxidation systems described.
However, with the relatively low concentrations of VOC in the regeneration air
effluent streams, large quantities of auxiliary fuel would be required, with
corresponding requirements for efficient energy recovery.
C. OXIDATIVE DEHYDROGENATION OF n-BUTENES (FIG. III-2, TABLE IV-2)
1. Normal Process Emissions
a. Flue Gas (Vents A, B, and C) — Emissions are composed of products generated
from the combustion of primarily gaseous fuels. VOC concentrations are rela-
tively low and the application of specific emission control devices is not
indicated.
b. Hydrocarbon Absorption Column Vent (Vent D) — This stream, characterized by
relatively low VOC concentrations but a very high flow rate, which results in
significant VOC emissions, can be effectively controlled by catalytic or thermal
A
oxidation. One producer utilizes a thermal oxidizer to control this stream.
The oxidizer is designed to treat 100 Mg of waste gas per hour and simultaneously
generate 45 Mg of steam per hour at a pressure of 5.2 MPa. With the VOC content
of the waste gas supplying 16% of the firing energy, 84% is provided by supple-
mentary natural-gas fuel.
2. Secondary Emissions
a. Wastewater — Potential secondary emissions from wastewater are significantly
greater from the oxidative dehydrogenation process than from the other processes
-------
IV-7
described. Wastewater, which is generated from steam addition and from water
formed in the reaction, is removed from the process gas before compression
(Source M, Stream 7). Wastewater from this source contains significant quanti-
ties of VOC. One producer utilizes a stripper designed to attain 85% removal of
the contained organics by countercurrent stripping with a portion of the waste
gas described in Sect. C-l-b. The effluent gas from the stripper, containing
the removed organics, is then combined with other waste gas prior to thermal
oxidation.
b- Solid Wastes — Polymeric residues are disposed of by landfill or incineration.
No specific additional controls are indicated.
D- EXTRACTION FROM ETHYLENE PLANT BY-PRODUCT STREAMS
The normal process emissions occur from the following sources:
J- Catalyst Regeneration Vents (Vents A and B)
Concentration of VOC emitted from the hydrogenation reactor during catalyst
regeneration (Vent B) and from the flue-gas vent from the regeneration preheater
(Vent A) is relatively low and occurs infrequently (approximately 4 times per
year). No specific emission control devices are indicated.
2- Methylacetylene Column Vent (Vent C).
Most of the residual acetylenes (not converted by hydrogenation), along with
significant quantities of butadiene, are vented as a waste stream. Emissions
from this source can be effectively controlled by combustion, either in the flare
system or in an existing combustion chamber. A VOC removal efficiency of 95% is
considered to be attainable with the flare. If this stream is burned in a com-
bustion chamber, a removal efficiency of at least 99% is attainable. Flare and
incineration control efficiencies will be covered by a future EPA report on con-
trol device evaluations.
-------
IV-8
E. REFERENCES*
1. Texas Air Control Board, 1975 Emission Inventory Questionnaires and Construction
Permit^ Application; see Appendix C.
2. R. L. Standifer, IT Enviroscience, Inc., Trip Report for Visit to Arco Chemical
Company, Channelview, TX. Aug. 16, 17. 1977 (on file at EPA, ESED, Research
Triangle Park, NC).
3. R. L. Standifer, IT Enviroscience, Inc., Trip Report for Visit to Petro-Tex Chemical
Corp., Houston, TX, Oct. 16, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
4. R. D. Pruessner, Hydrocarbon Emission Reduction Systems Utilized by Petro-Tex,
presented at American Institute of Chemical Engineers 83rd National Meeting,
9th Petrochemical and Refining Exposition, Houston, TX, March 1977.
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
A-l
APPENDIX A
i
Table A-l. Physical Properties of 1,3-Butadiene
Property
Value
Molecular weight
Boiling point at 1 atm
Freezing point at 1 atm
Specific gravity, liquid at 68°F/4e>F
Specific gravity, gas (air = 1.0)
Critical temperature
Critical pressure
Critical density
Latent heat of vaporization at boiling point
Vapor pressure
At 50°F
At 75°F
At 100°F
At 125°F
Specific heat at 100°F
Liquid
Gas at 1 atm
Solubility in water at 100°F and 50 psia
Solubility of water in butadiene at 60°F
54.092
24.06°F
-164.05°F
0.623
1.877
305.6°F
42.7 atm
0.245 g/cc
179.6 Btu/lb
25 psia
40 psia
60 psia
86 psia
0.58 Btu/db) (°F)
0.36 Btu/(lb)(°F)
0.14 wt %
0.203 wt %
Azeotropes
Ammonia
Methylamine
Acetaldehyde
2-Butene
n-Butane
Boiling
Point(°F)
-35
+15
+41
+42
Min. bp
Butadiene (wt %)
45.0
58.6
94.8
76.5
*G. E. Haddeland, Butadiene, Report No. 35, A private report by
the Process Economics Program, p. 238, Stanford Research
Institute, Menlo Park, CA (March 1968).
-------
B-l
APPENDIX B
FUGITIVE-EMISSION FACTORS*
The Environmental Protection Agency recently completed an extensive testing
program that resulted in updated fugitive-emission factors for petroleum re-
fineries. Other preliminary test results suggest that fugitive emissions from
sources in chemical plants are comparable to fugitive emissions from correspond-
ing sources in petroleum refineries. Therefore the emission factors established
for refineries are used in this report to estimate fugitive emissions from
organic chemical manufacture. These factors are presented below.
Uncontrolled
Emission Factor
Controlled
Emission Factor'
Source
Pump seals fa
Light-liquid service
Heavy-liquid service
Pipeline valves
Gas/vapor service
Light-liquid service
Heavy- liquid service
Safety/relief valves
Gas/vapor service
Light-liquid service
Heavy-liquid service
Compressor seals
Flanges
Drains
(kq/hr)
0.12
0.02
0.021
0.010
0.0003
0.16
0.006
0.009
0.44
0.00026
0.032
(ko/hr)
0.03
0.02
0.002
0.003
0.0003
0.061
0.006
0.009
0.11
0.00026
0.019
Based on monthly inspection of selected equipment; no inspection of
heavy-liquid equipment, flanges, or light-liquid relief valves;
10,000 ppmv VOC concentration at source defines a leak; and 15 days
allowed for correction of leaks,
liquid means any liquid more volatile than kerosene.
**adian Corp., Emission Factors and Frequency of Leak Occurrence for Fittings
Process Units. EPA 600/2-79-044 (February 1979J.
-------
C-l
APPENDIX C
1975 Texas Air Control Board Emission Inventory Questionnaires submitted by
butadiene producers:
Atlantic Richfield Co., Channelview, TX
Dow Chemical Co., Freeport, TX
El Paso Products Co., Odessa, TX
Firestone Tire & Rubber Co., Orange, TX
Mobil Corp., Beaumont, TX
Neches Butane Products Co., Port Neches, TX
Petro-Tex Chemical Co., Port Neches, TX
Phillips Petroleum Co., Borger, TX
Shell Chemical Co., Deer Park, TX
Standard Oil Co. (Indiana), Alvin, TX
Union Carbide Corp., Seadrift, TX
Union Carbide Corp., Texas City, TX
-------
D-l
APPENDIX D
EXISTING PLANT CONSIDERATIONS
A- CONTROL DEVICES
Table D-l lists process control devices reported to be in use by industry. To
gather information for the preparation of this report two site visits were made
to manufacturers of butadiene. Trip reports have been cleared by the companies
concerned and are on file at EPA, ESED, in Durham, NC. Additional information was
received form other butadiene manufacturers when the original draft of this
report was submitted to them for comments. Some of the pertinent information
from those existing butadiene manufacturers is presented in this appendix.
1- Petro-Tex Chemical Corp. - Houston, TX
Butadiene is currently produced by extraction from ethylene plant by-product
streams and by the oxidative dehydrogenation of n-butenes. Until early 1977
butadiene was also produced from n-butane by the Houdry process. Purification
is attained by extractive distillation, with furfural used as the extraction
solvent.
The primary process emissions from the oxidative dehydrogenation process are
from the absorber column vent and the gas turbine exhaust. These emissions are
controlled by an incinerator designed to treat 235,000-lb/hr waste gas containing
about 4000-ppm organics and 7000-ppm carbon monoxide. The installed capital
cost of the incineration system is $2.5 million (1976 dollars). This incinerator
utilizes flue-gas recirculation, which permits steam generation at a constant
rate of 100,000 Ib/hr under conditions of widely varying waste-gas flow rates.
(The waste-gas flow can range from 10% to 100% of the design production rate,
with the corresponding auxiliary fuel consumed as needed to maintain a constant
steam production rate.)
Prior to the shutdown of the Houdry butane dehydrogenation process by Petro-Tex
in 1977, the dehydrogenation reactor vent (the primary Houdry process emission
source) was controlled by a proprietary catalytic oxidation process. The oxida-
tion reactors (termed "Puff" reactors by Petro-Tex) attained a VOC destruction
efficiency of 92% without the addition of auxiliary fuel and attained an energy
recovery efficiency of 80% from the combustion gas. With this process only 1%
-------
Table D-l. Control Devices Used by Butadiene Producers
Emission Source
Company
Process
Houdry Process
Reactor Vent
Oxo Process
Absorber Vent
P.urification Section
Acetylenes
Other Process Vents
Arco Chemical Co.
Firestone Synthetic
Rubber and Latex Co.
El Paso Products Co.
Exxon Chemical Co.
Monsanto Chemical Co.
Petro-Tex Chemical
Corp.
Houdry
By-product
extraction
Houdry
Oxo
Houdry
By-product
extraction
By-product
extraction
Houdry
Oxo
By-product
extraction
Catalytic oxidizer
Thermal oxidizer
Uncontrolled
Catalytic oxidizer
Uncontrolled
Thermal oxidizer
Catalytic deny- /
drogenation j
Combustion in
boiT.er
NR
Flare
Catalytic deny- , Flare, recycle to
7
K>
drogenation
(regeneration
off-gas in-
cinerated)
NR
ethylene plant
Flare
aMethylacetylene and vinylacetylene. Quantities are significant only in ethylene plant by-product
Arco's Houdry units have been shut down.
CTower relief valves vented without controls. All others vented to flare system.
NR - not reported.
GSome intermittent emissions are vented without control.
Petro-Tex's Houdry units have been shut down.
-------
D-3
of the total regeneration air flow, in which most of the VOC is concentrated
(during the transition from the production to the regeneration phase of the
cycle), was diverted through the catalytic oxidation reactors. Operation of
the oxidation reactors was cyclic. During 20% of the time cycle the oxidation
reactor was heated as combustion of vented VOC occurred. For the remaining 80%
of the time cycles air was passed through the reactor, cooling the bed and trans-
mitting the stored energy to the heat recovery boiler. The installed capital
cost (1975) of the catalytic oxidation reactors was approximately $750,000 for
each Houdry train.
2- Arco Chemical Co. - Channelview, TX
Butadiene is currently produced by extraction from ethylene plant by-product
streams, with furfural used as the extraction solvent. Until 1976 butadiene
was totally produced by the catalytic dehydrogenation of butane {Houdry process).
These Houdry units are no longer operating. Prior to the shutdown of the Houdry
units the dehydrogenation reactor vent emissions were controlled with fixed-bed
catalytic converters, which processed the entire regeneration air stream.- These
converters reportedly attained a VOC removal efficiency of approximately 50%,
with an installed capital cost (1976) of $1,030,000 per Houdry train.
3- Firestone Synthetic Rubber and Latex Co. - Orange, TX
Butadiene is currently produced by oxidative dehydrogenation of butenes and by
a modified Houdry process. Acetonitrile (ACN) and cuprous ammonium acetate
solution (CAA) are used as the respective solvents in the two processes. Other
variations between the Firestone butane dehydrogenation (Houdry) process and
the model process are (1) Firestone operates its Houdry unit to produce both
butadiene and butylenes, which reduces the butadiene yield; (2) the waste heat
recovery boiler is downstream of the emission control device; (3) the boiler
bottoms are transferred to a pressurized sphere. The Firestone Houdry/CAA
emissions based on a 1975 emissions inventory and given in Table D-2 are signifi-
cantly higher than those presented in Table IV-1.
Variations between the Firestone oxidative dehydrogenation process and the model
process are (1) acetonitrile (ACN) is used as the extraction solvent; (2) the
reactor temperatures are lower; (3) the butane feed is heated with steam so
that no flue gas is generated; (4) absorption column ("sponge oil absorber")
-------
D-4
Table D-2. Firestone Emissions
3 a
Source Emissions [tons/yr (10 g) ] Emission Ratio (kg/Mg)_
Flue gas 97.8 (88,802.4) 1.78
Reactor vent
Uncontrolled 526 (477,608)
Controlled 5.21 (4,730.7) 0.09
Intermittent process Unknown Unknown
emissions
Storage and handling 1.94 (1,761.5) 0.04
(lower than actual)
Secondary 40.55 (36,819.4) 0.74
Fugitive (low) 14.3 (12,984.4) 0.26
Total (with Houdry incinerator) = 159.8 tons/yr, or 145,098 X 10 g
Oxo/ACN/iso Process (production from April 1979 = 53,761 tons/yr, or 48,814 X 10 )
Flue gas 31.9 (28,965.2) 0.59
Absorption column vent 197 (178,876) 3.66
(uncontrolled)
Intermittent process Unknown Unknown
emissions
Storage and handling 0.02 (18.16) 0.0004
(low)
Secondary 10.75 (9,761) 0.20
Fugitive (low) 14.3 (12,984.4) 0.27
Total 254.0 (230,604.8) 4.72
a
kg of emissions per Mg of product produced.
-------
D-5
vent emissions are not controlled by catalytic or thermal oxidation, with signi-
ficantly higher emission levels (estimated emissions and emission ratios for
the Firestone Oxo/ACN/Iso process are given in Table A-2); (5) the Firestone
reactor effluent composition is somewhat different from that in Table III-2
(see Table D-3 for comparative compositions).
4. El Paso Products Co. - Odessa, TX
Butadiene is currently produced by the dehydrogenation of butane (Houdry process).
Separation and purification of butadiene are attained by a cuprous ammonium
acetate solution (CAA) liquid-liquid extraction process.
The emission ratio for the purification process (fugitive emissions only) was
estimated by El Paso to be 0.0425 kg per Mg of butadiene produced.
f). Exxon Chemical Co. USA - Baton Rouge, LA
Butadiene is currently produced by extraction from ethylene plant by-product
streams. The Nippon Zeon Co. dimethyl formamide extractive distillation process
is used. Other variations between the Exxon process and the model process are
as follows: (1) the Exxon process does not use a hydrogenation reactor to con-
vert the acetylenes to olefins; vinyl acetylene and methyl acetylene are separated
and are then diluted with natural gas and C. hydrocarbons and burned in a steam
boiler as auxiliary fuel; (2) some pressure-relief devices are vented to the
atmosphere, not to a flare.
Estimated uncontrolled and controlled emission ratios are given in Table D-4.
e. Monsanto Co. - Chocolate Bayou, TX
Butadiene is currently produced by extraction from ethylene plant by-product
streams. The primary variations between the Monsanto process and the model
process are as follows-.
1. A methyl acetylene column is not used (C,'s are removed in the ethylene
plant).
2. The mixed C4's fed to recovery are washed with water to remove carbonyl
compounds.
-------
D-6
Table D-3. Firestone Oxo Reactor Effluent Composition
Component
Oxygen
Nitrogen
Carbon dioxide j
Carbon monoxide >
Methane
C2's
C3's
n-Butane
Isobutane
losbutene
1-Butene
Trans-2-butene
Cis-2-butene
1 , 3-Butadiene
C5's
Neopentane
Hydrogen
Composition (wt %)
IT Enviroscience
2.86
45.14
8.57
0.29
0.86
1.14
1.14
1.71
3.14
5.43
4.86
4.00
20.57
0.29
100.00
Firestone '
0.04
46.20
6.80
0.26
0.04
0.10
0.05
5.60
0.02
nil
2.40
6.20
3.90
27.20
2.20
0.18
101.19
Water-free basis.
Actual Firestone analysis of June 3, 1979.
-------
D-7
Table D-4. Estimates of Emission Ratios
for the Exxon By-Product Butadiene Process
Uncontrolled
•a
Emission Ratio
Source (kg/Mg)
Vinylacetylene, methyl
acetylene column vents
Normal process emissions
(common vent)
intermittent emissions
Storage and handling
Secondary
Fugitive
Total
66.83
0.99
0.014
0.01
0.15
_°.'54
68.53
Reduction
(%)
99
95
None
None
None
None
Controlled
Emission Ratio
(kg/Mg)
0.67
0.05
0.014
0.01
0.15
0^54
1.43
of emission per Mg of butadiene produced.
-------
D-8
Specific emission controls are as follows:
1. Regeneration off-gas is incinerated.
2. Relief-valve emissions are discharged to a flare.
3. The column vents are recycled to the ethylene plant.
B. RETROFITTING CONTROLS
As is described in Sect. Ill of this report, numerous variations of the processes
for production of butadiene are possible. Some of these variations influence
the amount and rate of the emissions. Such variations and the resulting in-
fluence on emissions should be considered before it is decided to retrofit con-
trol devices into existing plants.
The primary difficulty associated with retrofitting may be in finding space to
fit the control device into the existing plant layout. Because of the costs
associated with this difficulty it may be appreciably more expensive to retrofit
emission control systems in existing plants than to install a control system
during construction of a new plant.
-------
e-i
REPORT 8
ACETIC ANHYDRIDE
R. W. Helsel
IT Enviroscience
9041 Executive Park Drive
Knoxville, Tennessee 37923
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
November 1980
This report contains certain information which has been extracted from the
Chemical Economics Handbook, Stanford Research Institute. Wherever used, it
has been so noted.The proprietary data rights which reside with Stanford
Research Institute must be recognized with any use of this material.
D25J
-------
8-iii
CONTENTS OF REPORT 8
Page
I- ABBREVIATIONS AND CONVERSION FACTORS I-1
II. INDUSTRY DESCRIPTION II-1
A. Reason for Selection II'1
B. Acetic Anhydride Usage and Growth II-l
C. Domestic Producers ll-l
D. References II"7
III. PROCESS DESCRIPTION III-l
A. Introduction III-l
B. Model Process for Manufacture of Acetic Anhydride III-l
C. Process Variation III-4
D. References m~7
IV. EMISSIONS IV~1
A. Typical Plant IV~1
B. Sources and Emissions IV-1
IV-5
C. Other Processes
D. References
V. APPLICABLE CONTROL SYSTEMS V~1
V-l
A. Reactor By-Product Gas
V-l
B. Column Vents
C. Storage and" Handling Sources v~4
D. Fugitive-Emission Sources
V-5
E. References
VI- IMPACT ANALYSIS VI~1
VI-1
A. Control Cost Impact
_ „ , VI-5
B. References
APPENDICES OF REPORT 8
Page
A. PHYSICAL PROPERTIES OF ACETIC ANHYDRIDE AND BENZENE A-l
B. EXISTING PLANT CONSIDERATIONS B"1
-------
8-v
TABLES OF REPORT 8
Number Page
II-l Commercial Acetic Anhydride Usage and Growth II-2
II-2 Acetic Anhydride Capacity II-3
IV-1 Uncontrolled Emissions of CO and VOC -- Typical Plant IV-2
IV-2 Uncontrolled Emissions of VOC and Benzene — Process Variation IV-2
IV-3 Composition of Reactor By-Product Gas IV-4
V-l VOC and CO Controlled Emissions — Typical Plant V-2
V-2 VOC and Benzene Controlled Emissions — Process Variation V-3
VI-1 Environmental Impact of Controlled Sources — Typical Plant VI-2
Vl-2 Environmental Impact of Controlled Sources — Process Variation VI-3
VI-3 Emission Ratios for Industry VI-4
A-l Physical Properties of Acetic Anhydride A-l
A-2 Physical Properties of Benzene A-l
B-l Emission Control Devices Used
B~2
B-2 "Decomp Gas" Emission Data B-3
FIGURES OF REPORT 8
II-l Locations of Plants II-4
l Acetic Anhydride Hodel Process II-3
tII-2 Acetic Anhydride Process Variation n-e>
-------
1-1
ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements used in agency documents in metric
units. Listed below are the International System of Units (SI) abbreviations
and conversion factors for this report.
To Convert From
Pascal (Pa)
Joule (J)
Degree Celsius (°C)
Meter (m)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter/second
(m3/s)
Watt (W)
Meter (m)
Pascal (Pa)
Kilogram (kg)
Joule (J)
To
Atmosphere (760 mm Hg)
British thermal unit (Btu)
Degree Fahrenheit (°F)
Feet (ft)
Cubic feet (ft3)
Barrel (oil) (bbl)
Gallon (U.S. liquid) (gal)
Gallon (U.S. liquid)/min
(gpm)
Horsepower (electric) (hp)
Inch (in.)
Pound-force/inch2 (psi)
Pound-mass (Ib)
Watt-hour (Wh)
Multiply By
9.870 X 10"6
9.480 X 10"4
(°C X 9/5) + 32
3.28
3.531 X 101
6.290
2.643 X 102
1.585 X 104
1.340 X 10"3
3.937 X 101
1.450 X 10"4
2.205
2.778 X 10"4
Standard Conditions
68°F = 20°C
1 atmosphere = 101,325 Pascals
PREFIXES
Prefix
T
G
M
k
m
Symbol
tera
giga
mega
kilo
milli
micro
Multiplication
Factor
1012
109
106
103
10"3
io"6
Example
1
1
1
1
1
1
Tg =
Gg =
Mg =
km =
mV =
M9 =
1
1
1
1
1
1
X
X
X
X
X
X
IO12 grams
IO9
IO6
IO3
10"
10"
grams
grams
meters
3 volt
6 gram
-------
II-l
II. INDUSTRY DESCRIPTION
A- REASON FOR SELECTION
Acetic anhydride was selected for consideration because preliminary estimates
indicated a large production volume with a resulting potential for significant
emissions of volatile organic compounds (VOC). Acetic anhydride is a liquid
under ambient conditions (see Appendix A for pertinent physical properties}.
The predominant VOC emissions from acetic anhydride production are ethylene,
propane, and propadiene.1"4 Benzene emissions occur from three of the seven
ope rating plants.1'5
B. ACETIC ANHYDRIDE USAGE AND GROWTH
Table II-l shows end uses and percentages of production for commercial acetic
anhydride. It is estimated that 90% of the commercially produced anhydride is
used for the production of cellulose acetate.6'7
The commercial acetic anhydride capacity in the United States is currently
920 Gg/yr,3'7'8 with the 1976 commercial production being 74% of the commercial
capacity.* The annual growth is projected to be less than 1% as the result of
a declining demand for cellulose fiber relative to other synthetic fibers.'
Therefore commercial production is expected to remain less than 80% of the current
commercial capacity through 1982. The unavailability of acetic acid feedstock
is the only possible factor that could restrict commercial acetic anhydride
production.8 No planned commercial capacity changes have been identified. In
addition to the commercial capacity, a plant owned by the United States Army has
a reported capacity of 272 Gg/yr.10
c- DOMESTIC PRODUCERS
There were three commercial companies and one government-owned plant producing
acetic anhydride at the end of 1978. Table II-2 lists the producers, locations,
capacities, and processes.1"3'7'"'12 Figure II-l shows the plant locations.
For only about 25% of the existing commercial capacity, virgin acetic acid is
used exclusively as feedstock; the remaining commercial capacity is based partly
on recovered acetic acid, a reaction by-product from cellulose acetate manufacture.7"*
The military capacity is also based on recovered acetic acid, a by-product from
-------
II-2
Table II-l. Commercial Acetic Anhydride
Usage and Growth*
End Use
Production
for 1977
Cellulose acetate 90
Other acetate esters and misc. 8.6
Aspirin 1.4
Exports Negligible
*See ref 7.
-------
II-3
Table II-2. Acetic Anhydride Capacity0
Producer
Capacity for 1977
(Gg)
Process
Celanese Chemical Co., Inc.
Pampa, TX
Celanese Fibers Co.
Narrows, VA
Rock Hill, SC
1361
113
113
asee ref 7.
separate plants; see ref 8.
Acetic acid pyrolysis
with benzene; acetic acid
pyrolysis
Acetic acid pyrolysis
with benzene
Acetic acid pyrolysis
with benzene
Tennessee Eastman Co.
Kingsport, TN
Onion Carbide Corp.
Brownsville, TX
e
Avtex Fibers, Inc.
Meadville, PA
Commercial total
Ho Is ton Army Ammunition
Plant, Holston, TN
440
91C
27
920
272f
Acetic acid pyrolysis
Same as above
Same as above
Same as above
cVirgin acetic acid used exclusively.
dSee ref 3.
previously owned by FMC Corp., plant is idle; see ref 11.
ref 10.
-------
(1) Celanese Chemical Co., Inc., Pantpa, TX
(2) Celanese Fibers Co., Narrows, VA
(3) Celanese Fibers Co., Rock Hill, SC
(4) Tennessee Eastman Co., Kingsport, TN
(5) Union Carbide Corp., Brownsville, TX
(6) Avtex Fibers, Inc., Meadville, PA
(7) Holston Army Ammunition Plant, Holston, TN
Fig. II-l. Locations of Acetic Anhydride Plants
-------
II-5
manufacture of explosives.10 Apparently all existing operating capacity is
based on pyrolysis of acetic acid to ketene.1/2/ll>12 There are usually no
co-products resulting from this process.6 However, a portion of the intermediate,
ketene, can be diverted for direct usage in preparing diketene, which is used
for a number of specialty products.13'14
Companies that produce acetic anhydride are listed below:
1. Celanese Corporation
Nearly 40% of the acetic anhydride capacity is based exclusively on the
use of virgin acetic acid.8 The remaining capacity is based partly on
acetic acid recovered as a by-product of cellulose acetate manufacture.8
The resulting acetic anhydride is used as feedstock for additional cellulose
acetate production.15 A process developed by Celanese and based on pyrolysis
of acetic acid to ketene, with benzene used as a quench and drying agent,
is used in three of their plants.1'5
2. Tennessee Eastman Company
Using a method based on a process purchased from Wacker, Tennessee Eastman
produces acetic anhydride from acetic acid recovered as a by-product of
cellulose acetate production and from captive acetic acid. The Kingsport
plant represents a number of production trains that are tied together for
materials handling and storage and waste treatment. A portion of the inter-
mediate, ketene, is used to produce diketene.3'12'14
3. Union Carbide Corporation
Acetic anhydride is produced from captive acetic acid. The plant operating
at Brownsville is based on a design licensed by Tennessee Eastman Co.2
4. Avtex Fibers, Inc.
It is assumed that, until the plant became idle, acetic anhydride was pro-
duced from acetic acid recovered from cellulose acetate production and from
purchased acetic acid.7'15 The plant is not expected to resume operations.11
The process used was pyrolysis of acetic acid to ketene; diketene was produced
as a co-product.16
-------
II-6
5. Holston Army Ammunition Plant
At this plant, which uses Tennessee Eastman Co. technology and is operated
by Tennessee Eastman Co., acetic anhydride is produced from acetic acid
recovered from an explosives manufacturing process and from purchased acetic
acid. The resulting acetic anhydride is used captively.10
-------
II-7
D- REFERENCES*
1- R. W. Helsel, IT Enviroscience, Inc., Trip Report onjyisit to Celanese Chemical Co.
Plant at Pampa, TX, Mar. 1, 1978 (on file at EPA, ESED, Research Triangle Park, NC)
2- J- A. Key, IT Enviroscience, Inc., Trip Report on Visit to Union Carbide Corp.
Plant at South Charleston, WV, Dec. 7, 1977 (on file at EPA, ESED, Research
Triangle Park, NC).
3- Tennessee State Air Permits for Tennessee Eastman Corp-
4- Responses by Tennessee Eastman (Aug. 15, 1972) to EPA request for information
on emissions from acetic anhydride manufacture.
5- Correspondence dated January 1979 from R. H. Maurer, Celanese Chemical Co., Inc.,
to R. w. Helsel, IT Enviroscience, Inc. (documentation on file at IT Enviroscience,
Inc., Knoxville, TN).
6- F. s. Wagner, Jr., "Acetic Anhydride," pp. 151—161 in Kirk-Othmer Encyclopedia
of Chemical Technology, 3d ed., Vol. 1, edited by M. Grayson et al., Wiley-Inter-
science. New York, 1978.
7- E. M. Klapproth, "Acetic Anhydride -- Salient Statistics," pp. 603.5030B,C in
Chemical Economics Handbook, Stanford Research Institute, Menlo Park, CA, (April
1977).
a- "Chemical Profile on Acetic Anhydride," p. 9 in Chemical Marketing Reporter,
Oct. 1, 1975.
9- "Manual of Current Indicators - Supplemental Data," p. 201 in Chemical Economics
Handbook. Stanford Research Institute, Menlo Park, CA (October 1978).
10• Phone conversation Sept. 7, 1978, between David Mascone, EPA, and Charles Mueller,
Holston Army Ammunition Plant (documented in EPA file).
11• Personal correspondence dated May 8, 1978, from Avtex Fibers, to D. R. Goodwin,
Emission Standards and Engineering, USEPA.
l2- R. W. Helsel, IT Enviroscience, Inc., Trip Report on Visit to Tennessee Eastman Co.
Plant at Kinqsport, TN, Jan 24. 1978 (on file at EPA, ESED, Research Triangle
Park, NC).
13' R- H. Hasek, "Ketenes," pp. 87--100 in Kirk-Othmer Encyclopedia of Chemical
Technology. 2d ed., Vol. 12, edited by A. Standen et al., Wiley-Interscience,
New York, 1967.
4- Eastman Chemical Products, "A Glimpse of Tennessee Eastman," Bulletin
No. P-13BB (April 1977).
-------
II-8
15. T. Wallace, "Cellulose Acetate and Triacetate Fibers," pp. 543.3622G--M in
Chernical Economics Handbook, Stanford Research Institute, Menlo Park, CA
(November 1976).
16. Responses by FMC Corp. (Sept. 20, 1972) to EPA for the Petrochemical Emissions
Survey Questionnaire.
*A reference located at the end of a paragraph usually refers to the entire para-
graph. If another reference relates to certain portions of the paragraph, the
reference number is indicated on the material involved. When the reference
appears on a heading, it refers to all the text covered by that heading.
-------
III-l
III. PROCESS DESCRIPTION
INTRODUCTION
Three different continuous processes for manufacturing acetic anhydride, each
one starting with a different feedstock, are described in recent literature.1 3
In one, the acetaldehyde-oxidation process, acetic anhydride is produced as a
co-product of acetic acid.3 It is assumed that this process is no longer being
used domestically but it may still be in use outside the United States.4 Another
process involves the pyrolysis of acetone.3 The third method, which is apparently
being used today for nearly all domestic acetic anhydride production, is by pyrolysis
of acetic acid.5 8 In this process, acetic acid is pyrolyzed to ketene, which is
reacted with additional acetic acid to produce the anhydride. Two process configu-
rations are employed, differing in the manner in which the ketene/acetic acid
reaction is carried out. In the predominant process configuration, developed
originally by Wacker, ketene gas is separated from the condensables by cooling
and phase separation and is then contacted with acetic acid in absorbers.3'5 This
configuration has been selected for the model plant*, since it is representative of
the majority of production. In the other process configuration, developed by
Celanese, the pyrolysis reactor effluent gas is quenched with benzene,6'9 as is
discussed in "Process Variation."
Most commercial acetic anhydride is produced in conjunction with acetic acid
production at the same site.10 Also, most commercial acetic anhydride produc-
tion is consumed at the same site for the manufacture of cellulose acetate.11
A portion of the ketene produced in the pyrolysis of acetic acid can be diverted
and used to produce other products.12 Since ketene is a very reactive gas, it
is converted immediately to the intended product rather than being stored or
shipped.12
MODEL PROCESS FOR MANUFACTURE OF ACETIC ANHYDRIDE
Acetic anhydride is produced by the following chemical reactions:
Pyrolysis of acetic acid to ketene
CH3COOH * CH2=C=0 + H20
(acetic acid) (ketene) (water)
*See p 1-2 for discussion of model plants
-------
III-2
Addition of ketene and acetic acid to produce acetic anhydride
CH3COOH + CH2=C=0 *• (CH3CO)20
(acetic acid) (ketene) (acetic anhydride)
The model process for the manufacture of acetic anhydride from acetic acid is
shown in Fig. III-l. This continuous process has been described in detail in
the literature,3 although there may be some variations in the flow patterns of
the ketene absorber and gas scrubber systems and the distillation trains.5'7
The first step in the model process is pyrolysis. Acetic acid (Stream 1) is
vaporized and fed under vacuum to the pyrolysis furnace. A catalyst, normally
triethyIphosphate, is added to the feed stream. Typically a number of pyrolysis
reactors are operated in parallel for each production unit. The reactors are
operated at about 700°C and 13,000 to 26,000 Pa at the outlet. The yield of keten«
is influenced by pressure, temperature, catalyst, and reaction time. Lower
yields result in higher amounts of by-products such as methane, ethylene, and
carbon monoxide. Ammonia can be added to the reactor effluent to neutralize
the catalyst and stabilize the ketene. The effluent (Stream 2) is cooled before
it enters a phase separator, where water of reaction and most of the unconverted
acetic acid are separated as a condensate from the ketene and reaction by-product
gas. The weak acetic acid condensate (Stream 3) is combined with dilute acetic
acid effluent from the scrubbers and acetic acid column overhead and sent to a
light-ends column.3'5'7 It is assumed that ammonium metaphosphate formed from
neutralization of the catalyst is contained in Stream 3 and ultimately is
discharged from the process in the dilute acetic acid (Stream 15).
Acetic anhydride is produced in the second process step. In this step the gaseous
ketene stream (Stream 4) from the phase separator is contacted with glacial
acetic acid liquid (Stream 5) in two absorption columns operated in series under
reduced pressure (6,600 to 20,000 Pa) and near-ambient temperature (30 to 40°C).
It has been reported that liquid-ring rotary compressors can be used in place
of absorption columns and vacuum jets for the ketene--acetic acid reaction.4
The crude acetic anhydride liquid (Stream 6) exiting the absorption columns is
collected and sent to product purification.3
-------
COMBUST lOfJ
=>TM.
FROM ACE.TIC
ACID PUAWT
ACETIC
ACID
•bTORAG,E
= iC
IT
juJ
5)
— ,
j
CATALYST
ORS
J
=1
^3
-
VACUUM EJECTOR
<=,Y«bTEM —1
CRUDE ACETIC
AKJHVDRIDE.
COUJMNJ
ACETIC
J
AkJMYt
•5TOP
1
JRIDE
AG(E
TO CEUUU'-O^E
ACETATE
PLAKJT
, t®
Fig. III-l. Flow Diagram for Uncontrolled Acetic Anhydride Model Process
-------
III-4
The absorber off-gas (Stream 7), which contains the reaction by-product gas,
acetic acid, acetic anhydride, and traces of ketene, is sent to scrubbing columns
for removal of acetic acid and acetic anhydride. The primary scrubbing solution
(Stream 8), a strong acetic acid, results from the distillation of the acetic
acid fraction (Stream 10) that is separated from the acetic anhydride in the
crude anhydride column. The final scrubber uses water as a scrubbing solution,
3'5
with the spent solution normally discharged to the sewer for wastewater treatment.
The off-gas (Stream 9) from the scrubber system, containing the reaction by-product
gas, passes through the vacuum system, which provides the required reduced pressures
throughout the reaction and absorption systems.3'5'7 Vacuum jet ejectors are
assumed to be used as the vacuum source for the model process.
Crude acetic anhydride (Stream 6), which contains about 10% acetic acid, is purified
by two atmospheric distillations. In the crude acetic anhydride column the acetic
acid is removed as an overhead stream (Stream 10) for further processing and
recycling. The acetic anhydride (Stream 11) is then distilled overhead in the
acetic anhydride refining column, with heavy impurities being removed as a bottoms
stream (Stream 12). Acetic acid removed from the acetic anhydride (Stream 10)
is concentrated in a distillation column; the strong acetic acid fraction is
recycled to the scrubber system, and the weak acetic acid overhead (Stream 13)
is combined with the phase separator condensate (Stream 3) and distilled in the
14]
light ends column. This separation removes traces of reaction by-products (Stream
before the weak acetic acid solution (Stream 15) is sent to an acetic acid recovery
unit. The acetic acid recovery unit is considered to be part of the acetic acid
production plant or the cellulose acetate production plant at the same site. This
unit is not included as part of the acetic anhydride model process.3'8'7
The bottoms stream (Stream 12) from the acetic anhydride refining column is
processed in a sludge evaporator to recover acetic acid and acetic anhydride,
which are recycled to the distillation train. The residue from the evaporator
is landfilled or used as supplemental boiler fuel.5 7
C. PROCESS VARIATION
The process variation involves a different technique for the combination and
reaction of acetic acid with ketene. This is a proprietary process developed
-------
III-5
by Celanese and is used in three of its plants.13 A simplified sketch is shown
in Fig. III-2. In the process variation the pyrolysis reactor discharge (Stream 2),
containing ketene, water, acetic acid, and by-products, is quenched with liquid
benzene (Stream 3). The benzene and water are removed from the resulting mixture
and processed for recovery of benzene for recycling. The water fraction (Stream 4)
is processed as part of waste handling. The water (Stream 5) is discharged to
a wastewater treatment plant. The dehydrated ketene and acetic acid react to
form acetic anhydride (Stream 6), which is distilled to separate unreacted acetic
acid (Stream 7) and to remove impurities (Stream 8). The weak acetic acid (Stream 7)
is sent to an acetic acid recovery unit as with the model process. The impurities
(Stream 8) are processed as part of waste handling.6'9
-------
COMBUSTlOKl
ACID RECOVERY
UKJIT
RECYCLE
ACE.TIC ACID
FUGITIVE
OVEBWJL PLAKJT
I i
WASTE.- WATtR
TR.EJVTMtKJT
H
H
H
Fig. III-2. Simplified Sketch for
Uncontrolled Acetic Anhydride Process Variation Using Benzene Quench (See Ref. 6)
-------
III-7
D- REFERENCES*
1- F. s. Wagner, Jr., "Acetic Anhydride," pp. 151--161 in Kirk-Othmer Encyclopedia
of Chemical Technology, 3d ed., Vol. 1, edited by M. Grayson et al., Wiley-
Interscience, New York, 1978.
2- J- W. Pervier e_t al., Houdry Division of Air Products, Inc., Survey Reports on
Atmospheric Emissions from the Petrochemical Industry, EPA-450/3-73-005d, EPA,
Research Triangle Park, NC (April 1974).
3- S. Takaoka, Acetic Acid and Acetic Anhydride, Supplement A, Report No. 37A, A
private report by the Process Economics Program, pp. 113—146, Stanford Research
Institute, Menlo Park, CA (March 1973).
4- G. L. Bogron and L. A. Alheritiere, "Acetic Anhydride by Direct Oxidation," Chemical
Engineering Progress 60(9), 55 (September 1964).
5- R- W. Helsel, IT Enviroscience, Inc., Trip Report on Visit to Tennessee Eastman Co.
Plant at Kinqsport, TN, Jan. 24, 1978 (on file at EPA, ESED, Research Triangle
Park, NC).
6- R- W. Helsel/ IT Enviroscience, Inc., Trip Report on Celanese Chemical Co., Inc.,
Plant at Pampa, TX, Mar. 1, 1978 (on file at EPA, ESED, Research Triangle Park,
—
7- J. A. Key, IT Enviroscience, Inc., Trip Report on Visit to Union Carbide Corp.
South Charleston, WV, Pec. 7, 1977 (on file at EPA, ESED, Research Triangle Park,
NC).
8- Phone conversation on Sept. 7, 1978, between David Mascone of EPA and Charles
Mueller of Holston Army Ammunition Plant (documentation on file at EPA, ESED,
Research Triangle Park, NC).
9- "Process No. 105," p. 6-285 in The Industrial Organic Chemicals Industry,
Chapter 6, Part I, Monsanto Research Corp., Dayton, and Research Triangle
Institute, Research Triangle Park (nd).
10 • E. M. Klapproth, "Acetic Acid — Salient Statistics," pp. 602.50202E-F in Chemical
Economics Handbook, Stanford Research Institute, Menlo Park, CA, (April 1977,
revised July 1978).
l- "Chemical Profile on Acetic Anhydride," p. 9 in Chemical Marketing Reporter,
Oct. l, 1975.
^* R- H. Hasek, "Ketene," pp. 87—100 in Kirk-Othmer Encyclopedia of Chemical
Technology. 2d ed., Vol. 12, edited by A. Standen et al., Wiley-Interscience,
New York, 1967.
• Correspondence January 1979 from R. H. Maurer, Celanese Chemical Co., Inc., to
R- W. Helsel, IT Enviroscience, Inc. (documentation on file at IT Enviroscience,
Inc., Knoxville, TN).
*A reference located at the end of a paragraph usually refers to the entire para-
graph. If another reference relates to certain portions of the paragraph, the
reference number is indicated on the material involved. When the reference
appears on a heading, it refers to all the text covered by that heading.
-------
IV-1
IV. EMISSIONS
Emissions in this report are usually identified in terms of volatile organic
compounds (VOC). VOC are currently considered by the EPA to be those of a
large group of organic chemicals, most of which, when emitted to the atmosphere,
participate in photochemical reactions producing ozone. A relatively small
number of organic chemicals have low or negligible photochemical reactivity.
However, many of these organic chemicals are of concern and may be subject
to regulation by EPA under Section 111 or 112 of the Clean Air Act since
there are associated health or welfare impacts other than those related to
ozone formation.
A- TYPICAL PLANT
The capacity of the typical plant* developed for this study .is 110 Gg/yr, based
on 8760 hr of operation per year.** Although not an actual operating plant, the
size of the plant is typical of most operating production units or trains. The
plant utilizes the model process described in Sect. III. It is representative
of today's acetic anhydride manufacturing industry, which utilizes current engi-
neering technology. For the following description of emissions a plant using
the process variation is defined as having the same capacity as the typical
plant.
B- SOURCES AND EMISSIONS
Uncontrolled emission rates of CO and VOC from the process for the typical plant
are summarized in Table IV-1 and are discussed below. Uncontrolled emission rates
of VOC and benzene from the process for a plant using the process variation are
summarized in Table IV-2 and are discussed below.
l- Reactor By-Product Gas
The largest process emission of VOC is from the vacuum jet system (Source A,
Fig. III-l), which discharges the reactor by-product gas components not removed
in the ketene absorbers or gas scrubber system. This emission contains methane,
*See p 1-2 for a discussion of typical or model plants.
**Process downtime is normally expected to range from 5 to 15%. If the hourly
rate remains constant, the annual production and annual VOC emissions will be
correspondingly reduced. Control devices will usually operate on the same
cycle as the process. From the standpoint of cost-effectiveness calculations,
the error introduced by assuming continuous operation is negligible.
-------
IV-2
Table IV-1. Uncontrolled Emissions of CO and VOC from
Typical Acetic Anhydride Plant Using Model Process
Emissions
Source
Reactor by-product gas
Column vents
Stream
Designation
(Fig. III-l)
A
B,C
Ratio
CO
7.00
(g/Jcg) a
VOC
4.50
0.700
Rate (kg/hr)
CO VOC
88.2 56.5
8.82
of emission per kg of acetic anhydride produced.
Table IV-2. Uncontrolled Emissions of Total VOC and Benzene from
Acetic Anhydride Plant Using Process Variation
Emissions
Reactor
Column
Source
by-product gas
vents
Stream
Designation
(Fig. III-2)
A
B,C,D
Ratio
Total
VOC
31.0
2.13
(g/kg)a
Benzene
4.6
0.217
Rate
Total
VOC
389
26.8
(kg/hr)
Benzene
57.8
2.73
ag of emission per kg of acetic anhydride.
-------
IV-3
CO, and C02, in addition to various VOC, that result from by-product reactions
during the acetic acid pyrolysis. Table IV-3 shows the typical composition of
the off-gas based on both measured and estimated composition data from several
sources.15 Based on these composition data approximately 3% of the acetic
acid feed to pyrolysis is converted to by-product gas. The emission quantity
and composition are related to the degree of by-product reactions, the produc-
tion rate, and the impurities, such as formic or propionic acid, that may be
contained in the acetic acid feed. At capacity operation the uncontrolled VOC
emission is estimated to be 56.5 kg/hr.
For the plant using the process variation the-VOC emission ratio was calculated
based on emission data from the plant visited and the assumption that its capacity
was one half the total capacity indicated in Table II-2 for that producing location.
At capacity operation the uncontrolled VOC emission (Source A, Fig. III-2) is
estimated to be 188 kg/hr for this plant. Benzene would be present in the by-
product gas, in addition to methane, CO, C02, and other VOC indicated in Table IV-3.
The by-product gas represents the largest source of benzene emission. The amount
of benzene will be primarily related to the amount of total by-product gas.
Based on capacity operation the uncontrolled benzene emission rate is estimated
to be 29.1 kg/hr.
Column Vents
These vents emit the dissolved gases and uncondensed VOC from the crude anhydride
(Source B, Fig. III-l) and light-ends (Source C, Fig. III-l) distillation columns
in quantities related to production. The total uncontrolled VOC emission rate
is estimated to be.8.82 kg/hr for the typical plant operating at capacity.
For the plant using the process variation it is assumed that there are three
different column vents (Sources B, C, and D, Fig. III-2). The uncontrolled
emission rates estimated for total VOC and benzene are shown in Table IV-2.
Storage and Handling Emissions
Emissions result from the storage and handling of acetic acid, acetic anhydride,
and in-process streams. Sources of losses are shown in Fig. III-l (Sources D,
E and F). Storage and handling emissions from the entire synthetic organic
chemicals industry are discussed in a separate report.6
-------
IV-4
Table IV-3. Composition of Reactor By-Product Gas
in Typical Acetic Anhydride Planta
Component
VOC
Propane
Ethylene
Propadiene
Other VCX:°
Total VOC
Other components
Methane
Carbon monoxide
Carbon dioxide
Others
Total
Composition
(wt %)
4
8
10
2
24
5
37
27
7_
100
Emission Ratio
(q/kqr
0.73
1.5
1.9
0.37
4.50
0.95
7.0
5.0
1.3
18.75
See refs. 1—5;
g of emission per kg of acetic anhydride.
£
Includes hydrocarbons such as propylene, butylene, and
butadiene.
Includes nitrogen, oxygen, and -water.
-------
IV-5
4- Fugitive Emissions
Process pumps and valves are potential sources of fugitive emissions (Source G).
Fugitive emissions are discussed in a separate report.7
Secondary Emissions
Secondary VOC emissions can result from the handling and disposal of process-waste
liquid streams and solid residues. Two potential sources (H) are indicated in
Fig. III-l for the typical plant. Evaluation of the potential emissions from
disposal of these and other wastes from the entire SOCMI are covered by a
separate EPA report.8
Secondary benzene emissions (Source I, Fig. III-2) can result similarly from a
plant using the process variation.
C- OTHER PROCESSES
No data are available on emissions from domestic processes used previously for
production of acetic anhydride or for those used outside the United States today.
-------
IV-6
D. REFERENCES*
1. R. W. Helsel, IT Enviroscience, Inc., Trip Report on Visit to Celanese Chemical
Corp. Plant*at Pampa, TX, Aug. 23, 1978 (on file at EPA, ESED, Research Triangle
Park, NC).
2. J. A. Key, IT Enviroscience, Inc., Trip Report on Vist to Union Carbide Corp.,
Plant at South Charleston, WV, Dec. 7, 1977 (on file at EPA, ESED, Research
Triangle Park, NC).
3. R. W. Helsel, IT Enviroscience, Inc., Trip Report on Visit to Tennessee Eastman Co^
Plant at Kingsport, TN, Jan. 24, 1978 (on file at EPA, ESED, Research Triangle
Park, NC).
4. Tennessee State Air Permits for Tennessee Eastman Corp.
5. Responses by Tennessee Eastman Corp. (Aug. 15, 1972) to EPA request for information
on emissions from acetic anhydride manufacture.
6. D. G. Erikson, IT Enviroscience, Inc., Storage and Handling (September 1980)
(EPA/ESED report. Research Triangle Park, NC).
7. D. G. Erikson and V. Kalcevic, IT Enviroscience, Inc., Fugitive Emissions
(September 1980) (EPA/ESED report, Research Triangle Park, NC).
8. J. J. Cudahy and R. L. Standifer, IT Enviroscience, Inc., Secondary Emissions
(June 1980) (EPA/ESED report, Research Triangle Park, NC).
*A reference located at the end of a paragraph usually refers to the entire para-
graph. If another reference relates to certain portions of the paragraph, the
reference number is indicated on the material involved. When the reference
appears on a heading, it refers to all the text covered by that heading.
-------
V-l
V. APPLICABLE CONTROL SYSTEMS
A- REACTOR BY-PRODUCT GAS
The gas that exits the vacuum system vent can be thermally oxidized for effective
control of the VOC. The amount of CO, methane, ethylene, and other hydrocarbons
present in this gas provides more than adequate fuel value. Apparently, all
operating commercial plants, including those using the model process and those
using the process variation, are practicing thermal oxidation.1 4
A reduction of 99% in VOC and CO emissions was used for the calculation of the
controlled emissions given in Table V-l. Analysis of the pyrolysis furnace
stack at one plant indicates that greater than 99% removal can be achieved.1
During startup or process upsets the reactor by-product gas may be discharged
as an uncontrolled emission. Startup would be expected to occur four to six
times a year for each furnace.1 Startup emission quantities were not calcu-
lated and are not considered in the 99% reduction assumption.
For plants using the process variation, thermal oxidation of the reactor by-product
gas will be effective for controlling benzene emissions. Table V-2 gives the
data on controlled benzene emissions. A removal efficiency of 99% was assumed,
based on interpretation of vent gas and flue gas analysis from one plant.1
B- COLUMN VENTS
The emissions from the column vents can be controlled by piping them to the
pyrolysis furnace (with the reactor by-product gas) as discussed in Sect. V.A.
The cost effectiveness of this control was not evaluated.
Analysis of column vent emissions from a plant using the process variation indi-
cates that the fuel content is very low and that the moisture content is relatively
high.1 A vent condenser would effectively reduce the water content, which repre-
sented more than half the emission quantity, if this was necessary to ensure
Proper thermal oxidation in the pyrolysis furnace. For the plant visited that
uses the process variation, column vents that emit benzene are controlled by
thermal oxidation in the pyrolysis furnace.4 A reduction of 99% was used in the
calculation of the controlled total VOC and benzene emissions given in Tables V-l
and v-2.
-------
Table V-l. VOC and CO Emissions from Controlled Sources in Typical Acetic Anhydride; Plant
Emissions
Stream
Designation
Source (Fig.III-1)
Reactor by-product A
gas
Column vents B,C
Control Device
or Technique
Thermal oxidizer
(pyrolysis
furnace)
Thermal oxidizer
(pyrolysis
furnace)
Emission
(%) CO
99 0.070
99
(g/kg)
VOC
0.045
0.007
Rate (kg/hr)
CO VOC
0.882 0.565
0.088
g of emission per kg of acetic ajnhydride.
-------
Table V-2. Total VOC and Benzene Emissions from Controlled Sources in a Plant Using the Process Variation
Emissions
Stream
Designation
Source (Fig.III-2)
Reactor by-product A
gas
Column vents B,C,D
End— ion- Ratio* (g/kg)*
Control Device Reduction Total
or Technique (%} VOC Benzene
Thermal oxidizer 99 0.31 0.046
(pyrolysis
furnace)
Thermal oxidizer 99 0.021 0.002
{pyrolysis
furnace)
Rate (kg/hr)
Total
VOC Benzene
3.89 0.578
0.268 Q.027
'g of emission per kg of acetic anhydride.
f
-------
V-4
C. STORAGE AND HANDLING SOURCES
Controls for storage and handling emissions from the entire synthetic organic
chemicals manufacturing industry are discussed in a separate EPA report.
5
D. FUGITIVE-EMISSION SOURCES
Controls for fugitive emissions from the synthetic organic chemicals manufacturing
industry are discussed in a separate EPA report.6
-------
V-5
p- REFERENCES*
1- R. W. Helsel, IT Enviroscience, Inc., Trip Report on Visit to Celanese Chemical Co.
Inc., Pampa^, TX, Mar. 1, 1978 (on file at EPA, ESED, Research Triangle Park, NC).
2- R. W. Helsel, IT Enviroscience, Inc., Trip Report on Visit to Tennessee Eastman
Co. Plant at Kingsport, TN, Jan. 24, 1978 (on file at EPA, ESED, Research Triangle
Park, NC).
3- J. A. Key, IT Enviroscience, Inc., Trip Report on Visit to Union Carbide Corp. Plant
at South Charleston, WV, Dec. 7, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
4- Correspondence dated Jan. 30, 1979, from R. H. Maurer, Celanese Chemical Co., Inc.,
to R. W. Helsel, IT Enviroscience, Inc. (documentation on file at IT Enviroscience,
Inc., Knoxville, TN).
5- D. G. Erikson, IT Enviroscience, Inc., Storage and Handling (September 1980)
(EPA/ESED report, Research Triangle Park, NC).
6- D. G. Erikson and V. Kalcevic, IT Enviroscience, Inc., Fugitive Emissions
(September 1980) (EPA/ESED report, Research Triangle Park, NC).
*A reference located at the end of a paragraph usually refers to the entire
paragraph. If another reference relates to certain portions of the paragraph,
the reference number is indicated on the material involved. When the reference
appears on a heading, it refers to all the text covered by that heading.
-------
VI-1
VI. IMPACT ANALYSIS
A. CONTROL COST IMPACT
Costs and cost-effectiveness data for control of VOC emissions and benzene emis-
sions resulting from production of acetic anhydride were not developed. All
operating commercial plants are presently utilizing thermal oxidation for the
reactor by-product gas, and it is estimated that additional capital costs for
including the column vents would be low in most cases, depending on piping costs.
Based on industry response regarding the equipment requirements for accomplishing
thermal oxidation of the reactor by-product gas, capital costs would be considered
to be low for new sources.1'2 It is assumed that labor costs, maintenance costs,
and capital charges would be low and that the recovery credits for fuel value
present in the reactor by-product gas would result in a net operating margin
for utilization of thermal oxidation for the reactor by-product gas and column
vents.
1- Typical Plant
The environmental impact of the application of the described control systems to
the typical new plant would be a CO emission reduction of 764.9 Mg/yr and a VOC
emission reduction of 566.2 Mg/yr, as shown in Table VI-1. The environmental
impact'from the described control systems for the plant using the process varia-
tion would be a total VOC reduction of 1862 Mg/yr, including a benzene reduction
of 274.6 Mg/yr, as shown in Table VI-2.
2- Industry
Emission sources, control levels, and emission ratios for the industry are sum-
marized in Table VI-3. From emission data reported by producing commercial
acetic anhydride plants1""4 the emission ratios for the industry have been esti-
mated and are also shown in Table VI-3. Secondary emissions are not considered.
These values are based on 70% of the production manufactured by processes comparable
to the model process and 30% manufactured by processes comparable to the process
variation. These values show that the industry processes are about 86% controlled
for VOC. Based on.the reactor off-gas being considered as the only CO emission
the industry processes are 99% controlled for CO. Industry processes comparable
to the process variation are about 96% controlled for benzene. With an estimated
1978 production level of 694 Gg the process emissions from industry are estimated
to be 48.6 Mg of CO, 719 Mg of VOC, and 9.4 Mg of benzene.
-------
Table VI-1. Environmental Impact of Controlled Sources in a Typical Acetic Anhydride Plant*
Source
Reactor by-product gas
Column vents
Total
Stream
Designation
(Fig.III-1)
A
B,C
Emission
~ *. -, ~ • CO
Control Device •• • ••
or Technique (%) (Mg/yr)
Thermal oxidizer 99 764.9
(pyrolysis furnace)
Thermal oxidizer
Cpyrolysis furnace)
764.9
Reduction
Total VOC
(%) (Hg/yr)
99 490.0
99 76.2
566.2
Storage and handling fugitives and secondary emissions not included.
-------
Table VI-2. Environmental Impact of Controlled Sources in
Acetic Anhydride Plant Using the Process Variation*
Source
Reactor by-product gas
Column vents
Total
Stream
Designation Control Device •• •• ••• •
(Fig.III-2) or Technique (%)
A Thermal oxidizer 99
{pyrolysis furnace)
B,C,D Thermal oxidizer 99
(pyrolysis furnace)
Emission Reduction
:al VOC Benzene
(Mg/yr) (%)
3380 99
232 99
3612
(Mg/yr)
501
23.6
524.6
Storage and handling fugitive and secondary emissions not included.
-------
VI-4
Table VI-3. Emission Ratios for Industry'
Emission Ratio (g/kg)
Emission Source
Reactor by-product gas
Column vents
a
Total
CO
0.070
0.070
VOC
0.124
0.96
1.084
Benzene
0.046
0.022
0.068
"Industry" is based on 70% of active commerical plants using processes
comparable to the model process and 30% using processes comparable to the
process variation. Secondary emissions are not included.
g of emission per kg of acetic anhydride; determined froms refs 1—3.
"Benzene emission ratio is based only on the plants using the process varia-
tion.
-------
VI-5
B. REFERENCES*
1. R. W. Helsel, IT Enviroscience, Inc., Trip Report on Visit to Celanese Chemical Co.,
Inc., Plant at Pampa, XX, Mar. 1, 1978 (on file at EPA, ESED, Research Triangle
Park, NC).
2. R. W. Helsel, IT Enviroscience, Inc., Trip Report on Visit to Tennessee Eastman
Co. Plant at Kingsport, TN, Jan. 24, 1978 (on file at EPA, ESED, Research Triangle
Park, NC).
3. J. A. Key, IT Enviroscience, Inc., Trip Report on Visit to Union Carbide Corp. Plant
at South Charleston, WV, Dec. 7, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
4. Correspondence Jan. 30, 1979 from R. H. Maurer, Celanese Chemical Co., Inc., to
R. W. Helsel, IT Enviroscience, Inc. (documentation on file at IT Enviroscience,
Inc., Knoxville, TN).
*h reference located at the end of a paragraph usually refers to the entire
paragraph. If another reference relates to certain portions of the paragraph,
the reference number is indicated on the material involved. When the reference
appears on a heading, it refers to all the text covered by that heading.
-------
APPENDIX A
Table A-l. Physical Properties of Acetic Anhydride*
Synonyms
Molecular formula
Molecular weight
Vapor pressure
Melting point
Boiling point
Density
Physical state
Vapor density
Water solubility
Acetyl oxide, acetic
oxide, ethanoic
anhydride
C4H6°3
102.09
5.09 mm at 25°C
-73.1°C
139.55°C at 1 atm
1.082 g/ml at 20°C/4°C
Liquid
3.50
Very soluble
*From: J. Dorigan et^ a_l. , "Acetic Anhydride," p. AI-18 in
Appendix I, Rev. 1, Scoring of Organic Air Pollutants. Chemistry,
Production and Toxicity of Selected Organic Chemicals (Chemicals D—E),
MTR-7248, MITRE Corp. (September 1976).
Table A-2. Physical Properties of Benzene'
Synonyms
Molecular formula
Molecular weight
Physical state
Vapor pressure
Vapor density
Boiling point
Melting point
Density
Water solubility
Benzol, phenylhydride, coal naphtha
C6H6
78.11
Liquid
95.9 mm at 25°C
2.77
80.1°C at 760 mm
5.5°C
0.8787 at 20°C/4°C
Slight (1.79 g/liter)
J. Dorigan, B. Fuller, and R. Duffy, "Benzene," p AI-102 in
Scoring of Organic Air Pollutants. Chemistry, Production and
Toxicity of Selected Organic Chemicals (Chemicals a-c), MTR-7248,
Rev 1, Appendix1I, MITRE Corp., McLean, VA (September 1976).
-------
B-l
APPENDIX B
EXISTING PLANT CONSIDERATIONS
Table B-l1—4 lists emission controls reported to be in use by industry. To
gather information for the preparation of this 'report three visits were made to
manufacturers of acetic anhydride. Trip reports have been cleared by the
companies concerned and are on file at EPA/ESED in Durham, NC.1'2'4 Some of
the pertinent information concerning process emissions from these existing
acetic anhydride plants is presented in this appendix. Also included is infor-
mation received with comments on the draft report Acetic Anhydride.5'6
A- CONTROLS AT EXISTING PLANTS
Tennessee Eastman Company, Kingsport, TN
The acetic anhydride plant was initially built in 1934 by a design purchased
from Wacker. Many modifications and additions have been made to the original
plant, the most recent one being completed in 1977. The reactor by-product gas
exits the process from the vacuum jets and is collected and normally burned as
supplemental fuel in the pyrolysis furnaces. This control method is considered
by Tennessee Eastman to be essentially 100% effective in removing organics
except during periods of startup or maintenance, when the off-gas cannot be sent
to the furnace.1
Celanese Fibers Company, Narrows, VA, and Rock Hill, SC
Both plants use the acetic acid pyrolysis process with benzene quench; in
addition, the Rock Hill plant has one operating unit using a proprietary
Celanese process. Reportedly at one plant the total VOC in the reactor by-
product gas is 31 g/kg of acetic anhydride produced and the benzene is 3.7 g/kg
of acetic anhydride produced.5
Celanese Chemical Company, Pampa, TX
The acetic anhydride plant in which benzene is used as a drying agent was built
in 1952 by a Celanese design. Gases formed in the pyrolysis reaction are
separated from the crude acetic anhydride and compressed, the condensibles are
removed by phase separation, and the noncondensibles ("decomp gas") are sent to
the pyrolysis furnaces as supplementary fuel. A typical analysis by Celanese for
the "decomp gas" (before and after control) is found in Table B-2.
-------
Table B-l. Emission Control Devices Currently Used by Some Domestic Commercial Acetic Anhydride Producers
Control Devices Used By
Source
Tennessee Eastman Co.
Kingsport, TN
Celanese Chemical Co., Inc.
Pampa, TX
Union Carbide Corp.
Brownsville, TX
Reactor by-product gas
Column vents
Storage and handling
(in-process vessels)"
Thermal oxidizer
To atmosphere
Not applicable
Thermal oxidizer
To atmosphere (nonbenzene)
Thermal oxidizer (benzene)
Thermal oxidizer
Thermal oxidizer
To atmosphere
Not applicable
See ref 1.
See refs 2 and 3.
c
See ref 4.
Oxidized in pyrolysis furnace as supplemental fuel.
eOxidized after pyrolysis furnace prior to waste heat recovery boiler.
Pressure-vacuum relief valves are used.
For'benzene-containing streams only.
DO
(o
-------
B-3
Table B-2. "Decomp Gas" Emission Data
"Decomp Gas"
Feed to Furnace
Compound
Methane
voc*
CO
co2
Benzene
so2
NO
X
Others
Partlculates
(wt %)
2.2
29.7
35.2
26.0
4.4
6.9
(Ib/hr)
19.51
265.76
315 . 3
233.3
39.25
61.53
Furnace Stack
(ppm) (Ib/hr)
6.9 0.053
1.1 0.007
1.6 0.021
0.0
91.5 2.009
(EPA factor)
(tons/yr)
0.23
0.03
0.09
8.8
0.8
*Volatile organic compounds other than methane.
-------
B-4
The other two process emission points are the steam jet ejector vents from the
dirty-product still and the anhydride finishing still, which are discharged to
the atmosphere. Typical vent analysis by Celanese for the combined emission from
the anhydride finishing column overhead jet and the DP still overhead is as
follows:
Flow (Ib/hr) 560
Composition, wt %
Acetic Acid 2.9
Benzene 0.1
Acetone 1.7
Acetic Anhydride 0.3
C02 7.8
Water 59.9
N2 0.5
N°* 0.1
Air 26.4
Union Carbide Corporation, Brownsville, TX4
Acetic anhydride is produced from acetic acid by a ketene process licensed from
Tennessee Eastman. The Brownsville plant was originally built in 1950 by
Carthage Hydrocal Co. to produce gasoline and other fuels and chemicals from
natural gas but was shut down in 1953. Standard Oil and Gas Co. acquired the
plant and made additions and modifications to it; however, because of poor
economics, it was shut down in 1957. Union Carbide purchased the facilities
and converted the equipment to produce acetic acid, acetic anhydride, etc., in
1961. The plant was expanded in 1965.
The emissions from the vacuum ejector system on the gas scrubbers in the acetic
anhydride process are controlled by burning in the process off-gas burners. The
operating conditions of the Wacker off-gas burner are as follows:
-------
B-5
Off gas flow, scfh/pph 5460/500
Off gas pressure, "H20 25
Off gas temperature, °C 49
Off gas specific gravity, with reference to air 1.22
at 14.7 psia and 70°F
Off gas composition, mole or vol % *
Allene and/or methyl acetylene 10.1
Butadiene 0-9
Carbon dioxide 22.8
Carbon monoxide 46.6
Ethane 0-4
Ethylene 8-7
Methane 8.5
Oxygen °- 5
Propylene °•6
Water 0.9
*0ff gas composition from analysis of sample taken on October 1, 1975; represented
by the unit to be a typical composition.
B- RETROFITTING CONTROLS
As discussed in Sect. V-A, apparently all operating commercial acetic anhydride
plants use thermal oxidation to control the VOC emissions in the reactor by-
product gas vented from the vacuum system. Also, several plants send the
column vent gases to the pyrolysis furnaces. The primary difficulty with
retrofitting this control technique to the plants that are not controlled may
be that the back pressure on the columns and on the vacuum systems will cause
upsets in the operation of the process or will overpressure and damage the
equipment. Because of the costs associated with preventing this difficulty it
way be appreciably more expensive to retrofit this emission control system in
existing plants than to install a control system during construction of a new
plant.
-------
B-6
F. REFERENCES*
1. R. W. Helsel, IT Enviroscience, Inc., Trip Report on Visit to Tennessee Eastman
Co. at Jan. 24, 1978 (data on file at EPA, ESED, Research Triangle Park, NC).
2. R. W. Helsel, IT Enviroscience, Inc., Trip Report on Visit to Celanese Chemical
Co., Inc. Pampa, TX, Mar. 1, 1978 (data on file at EPA, ESED, Research Triangle
Park, NC).
3. Correspondence January 1979 from R. H. Maurer, Celanese Chemical Corp., to
R. W. Helsel, IT Enviroscience, Inc. (documentation on file at IT Enviroscience,
Inc., Knoxville, TN).
4. J. A. Key, IT Enviroscience, Inc., Trip Report on Visit to Union Carbide Corp.
Plant at South Charleston, WV. Dec. 7, 1977 (data on file at EPA, ESED, Research
Triangle Park, NC).
5. J. C. Pullen, Celanese Fibers Company, letter dated Oct. 12, 1979, to J. R. Frame?'
EGA, with comments on draft report Acetic Anhydride (on file at EPA, ESED,
Research Triangle Park, NC).
6. R. H. Maurer, Celanese Chemical Company, Inc., letter dated Nov. 27, 1979,
to J. R. Farmer, EPA, with comments on draft Acetic Anhydride Report (on file
at EPA, ESED, Research Triangle Park, NC).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
9-i
REPORT 9
ACETIC ACID, FORMIC ACID, ETHYL ACETATE, METHYL ETHYL KETONE
J. A. Key
IT Enviroscience
9041 Executive Park Drive
Knoxville, Tennessee 37923
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
October 1980
This report contains certain information which has been extracted from the
Chemical Economics Handbook, Stanford Research Institute. Wherever used, it
has been so noted. The proprietary data rights which reside with Stanford
Research Institute must be recognized with any use of this material.
-------
9-iii
CONTENTS FOR REPORT 9
Page
I. ABBREVIATIONS AND CONVERSION FACTORS !>!
11. INDUSTRY DESCRIPTION II-1
A. Reason for Selection II-l
B. Usage and Growth II-l
C. Domestic Producers II-4
D. References II-7
Hi. PROCESS DESCRIPTIONS III-l
A. Introduction III-l
B. Methanol Carbonylation for Production of Acetic Acid III-l
C. Butane Oxidation Process for Production of Acetic Acid III-4
D. Acetaldehyde Oxidation Process for Production of Acetic Acid III-5
E. Ethanol Fermentation Process for Production of Acetic Acid III-6
F- Butanol Dehydrogenation Process for Production of MEK III-6
G. Esterification Process for Production of Ethyl Acetate III-6
H. Acetaldehyde Process for Production of Ethyl Acetate III-7
I. References III-8
Iv- EMISSIONS IV-1
A. Introduction IV-1
B. Methanol Carbonylation Process for Acetic Acid IV-1
C. Butane Oxidation Process for Acetic Acid IV-3
D- Acetaldehyde Oxidation for Acetic Acid IV-3
E. Butanol Dehydrogenation Process for MEK IV-8
F. Esterification Process for Ethyl Acetate IV-8
G. References IV-9
v- APPLICABALE CONTROL DEVICES V-l
A. Introduction V-l
B. Methanol Carbonylation Process for Acetic Acid V-l
C. Butane Oxidation Process for Acetic Acid V-l
D. Acetaldehyde Oxidation Process for Acetic Acid V-l
E. Butanol Dehydrogenation Process for MEK V-3
F. Esterification Process for Ethyl Acetate V-3
G. References V-4
-------
9-v
CONTENTS (Continued)
Page
IMPACT ANALYSIS VI-1
A. Environmental Impact VI-1
B. Other Impacts VI-1
C, References VI-4
APPENDICES OF REPORT 9
A- PHYSICAL PROPERTIES OF ACETIC ACID, FORMIC ACID, ETHYL A-l
ACETATE, AND METHYL ETHYL KETONE
B- EXISTING PLANT CONSIDERATIONS B-l
-------
9-vii
TABLES OF REPORT 9
Number Page
II-l Acetic Acid End Usage II-3
II-2 Production Capacity for Acetic Acid, Formic Acid, Ethyl II-5
Acetate, and Methyl Ethyl Ketone
IV-1 Uncontrolled VOC Emissions IV-2
IV-2 Composition of BASF Methanol Carbonylation Vent Gas IV-4
IV-3 Composition of BASF Methanol Carbonylation Distillation IV-5
Vent Gas
IV-4 Composition of Butane Oxidation Vent Gas IV-6
IV-5 Composition of Acetaldehyde Oxidation Vent Gas IV-7
V-l Controlled VOC Emissions V-2
VI-1 Environmental Impact of Controlled Processes VI-2
Vl-2 Current Industry Emissions VI-3
A-l Physical Properties of Acetic Acid A-l
A"2 Physical Properties of Formic Acid A-2
A-3 Physical Properties of Ethyl Acetate A-3
A-4 Physical Properties of Methyl Ethyl Ketone A-4
B-l Union Carbide Butane Oxidation Controlled VOC Emissions B~4
B-2 Celanese Acetic Acid Source Emissions B-5
FIGURES OF REPORT 9
II-l Production of Ace'tic Acid, Formic Acid, Ethyl Acetate, II-2
and Methyl Ethyl Ketone
Hl-1 Process Flow Diagram for Acetic Acid by Methanol III-3
Carbonylation
-------
1-1
ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements used in agency documents in metric
units. Listed below are the International System of Units (SI) abbreviations
and conversion factors for this report.
To Convert From
Pascal (Pa)
Joule (J)
Degree Celsius (°C)
Meter (m)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter/second
On3/s)
Watt (w)
Meter (m)
Pascal (Pa)
Kilogram (kg)
Joule (J)
To
Atmosphere (760 mm Hg)
British thermal unit (Btu)
Degree Fahrenheit (°F)
Feet (ft)
Cubic feet (ft3)
Barrel (oil) (bbl)
Gallon (U.S. liquid) (gal)
Gallon (U.S. liquid)/min
(gpm)
Horsepower (electric) (hp)
Inch (in.)
Pound-force/inch2 (psi)
Pound-mass (Ib)
Watt-hour (Wh)
Multiply By
9.870 X 10"6
9.480 X 10"4
(°C X 9/5) + 32
3.28
3.531 X 101
6.290
2.643 X 102
1.585 X 104
1.340 X 10"3
3.937 X 101
1.450 X 10"4
2.205
2.778 X 10"4
Standard Conditions
68°F = 20°C
1 atmosphere = 101,325 Pascals
PREFIXES
Prefix
T
G
M
k
m
M
Symbol
tera
giga
mega
kilo
milli
micro
Multiplication
Factor
1012
109
106
103
10"3
10"6
Example
1 Tg =
1 Gg =
1 Mg =
1 km =
1 mV =
1 }jg =
1 X 1012 grams
1 X 109 grams
1 X 106 grams
1 X 103 meters
1 X 10"3 volt
1 X 10"6 gram
-------
II-l
II. INDUSTRY DESCRIPTION
A- REASON FOR SELECTION
Acetic acid was selected for consideration because preliminary information indi-
cated that its production causes significant emissions of volatile organic com-
pounds (VOC), estimated as 1.5% of the total emissions from the synthetic organic
chemicals industry. Formic acid, ethyl acetate, and methyl ethyl ketone (MEK)
are included in the study because they are by-products from the butane oxidation
process for producing acetic acid (see Fig II-l), currently the process used in
manufacturing 28% of the acetic acid produced in the United States and that
results in the highest ratio of total VOC emitted per kg of acetic acid produced.
Acetic acid, formic acid, ethyl acetate, and MEK are liquids under ambient condi-
tions but are sufficiently volatile for gaseous emissions to occur during produc-
tion (see Appendix A for pertinent properties). The emissions from their produc-
tion consist of butane, acetaldehyde, methanol, acetic acid, ethane, methyl
acetate, ethyl acetate, formic acid, MEK, ethanol, and butanol.
B- USAGE AND GROWTH
Table II-l shows the end uses of acetic acid. The largest use is in the produc-
tion of vinyl acetate monomer, which is expected to continue to grow, as is the
production of purified terephthalic acid (PTA) and dimethyl terephthalate (DMT).
Another large end use for acetic acid results from the production of cellulose
acetate, whose precursor is acetic anhydride, which is made from acetic acid.
However, little, if any, growth is expected for cellulose acetate. Future growth
of acetic acid production is predicted to be 5% per year.1
Formic acid is used in textile dyeing and finishing, chemical synthesis, pharma-
ceutical synthesis, and tanning and leather treatment. Its usage is expected
to grow about 4% per year. The textiles industry will continue to be the largest
market for formic acid, even though it will, to some extent, be replaced by
acetic acid.2
Ethyl acetate is used primarily as a solvent, with only 3% used in chemical
synthesis. As the use of some solvents is restricted by new environmental regu-
lations, ethyl acetate production may increase slightly despite its loss to
ketones for some uses. Future growth is expected to be about 3% per year.3
-------
II-2
Methanol
Carbon Monoxide
Methanol
Carbonylation
Acetic Acid
n-Butane
Air (or oxygen)
Butane
Oxidation
Acetic Acid
Formic Acid
| By-Broducts
Ethyl Acetate
Methyl Ethyl Ketone
Other By-Products
Acetaldehyde
Air
Aceubldehyde
Oxidation
Acetic Acid
Ethanol
Ethanol
Fermentation
Acetic Acid
sec-Butyl Alcohol
Butanol
Dehydrogenation
Methyl Ethyl Ketone^
Acetic Acid
Ethanol
Esterification
Ethyl Acetate
Ally! Alcohol
Peracetic Acid
Glycerin
Synthesis
Glycerine
By-Product Acetic Acid
Acetaldehyde
Oxygen (air)
Acetaldehyde
Oxidation
Peracetic Acid
I By-Product Acetic Acid
Sulfite Pulp
Waste Liquor
By-Product
Recovery from
Haste
Wastewater
By-Product Formic Acid
By-Product Acetic Acid
Fig. II-l. Production of Acetic Acid, Formic Acid,
Ethyl Acetate, and Methyl Ethyl Ketone
-------
II-3
Table II-l. Acetic Acid End Usage*
Acetic Acid
Consumption for 1980
End Use
Vinyl acetate monomer
Cellulose acetate
Acetic esters
Terephthalic acid/dimethyl terephthalate
Miscellaneous
45
25
15
11
4
See ref 1.
-------
II-4
MEK is also used primarily as a solvent in such coatings as paints and varnishes,
which are expected to boost its growth to about 5% per year.4
Domestic production capacities for acetic acid, formic acid, ethyl acetate, and
MEK for 1980 are given in Table II-2.1—9 Acetic acid production in 1979 was
1,510,000 Mg, or about 80% of capacity.10 This capacity will be adequate for
the projected growth until 1984.x The projected demand for formic acid, ethyl
acetate, and MEK will not exceed the capacity to produce them until sometime
after 1984.2—10
C. DOMESTIC PRODUCERS
Eight producers in 1980 were operating nine acetic acid plants employing three
processes, plus three other plants that produced acetic acid as a by-product
(see Table 11-2 and Fig. II-l). Formic acid is produced as a by-product at two
acetic acid plants that use the butane oxidation process (Celanese at Pampa,
TX, and Union Carbide at Brownsville, TX) and at a Sonoco plant (Hartsville,
SC) that recovers acetic acid from sulfite-pulp waste liquor.1'2'5 MEK and
ethyl acetate are produced both as by-products and from plants that may produce
other ketones or esters, respectively.6'7
Acetic acid is produced by butane oxidation, by acetaldehyde oxidation, by methanol
carbonylation, and until recently to a small extent by ethanol fermentation.
With the recent completion of two new plants by Celanese and by USI Division of
National Distillers (both of which use Monsanto's methanol carbonylation
process) methanol carbonylation is the predominant process.1'5 Wood distillation
was the principal source of acetic acid in the United States for 75 years, but
has not been used since 1973.5fl1
Companies producing one or more of the products involved are as follows:
1. ARCO — Produces MEK at Channelview, TX, reportedly from sec-butyl alcohol.12
2. Borden -- Produces acetic acid by a methanol carbonylation high-pressure process
that uses BASF technology.13
3. Celandse — Produces acetic acid by acetaldehyde oxidation at Bay City, TX, and
Clear Lake, TX, by butane oxidation with air at Pampa, TX; started up during
-------
II-5
Table II-2. Production Capacity for Acetic Acid,
Formic Acid, Ethyl Acetate, and Methyl Ethyl Ketone
1980
Capacity (Mg/yr)
Acetic Formic Ethyl Methyl Ethyl
_ Company
ARCO
Borden
Celanese
Eastman
Exxon
PMC
Monsanto
publicker
Shell
Sonoco
union Carbide
Usi
Total
a ' • — —
See refs 1 — 9;
o
Location
Channelview, TX
Geismar, LA
Bay City, TX-
Clear Lake, TX
Pampa, TX
Kingsport, TN
Longview, TX
Bayway, NJ
Bayport, TX
Texas City, TX
Springfield, MA
Trenton, MI
Philadelphia, PA
Houston, TX
Norco, LA
Hartsville, SC
Browns vi 1 le , TX
Taft, LA
Deer Park, TX
some references give
Borden is increasing its capacity to
c
Acid Acid
52,000b
91,000
499,000
250,000 11,300
204,000
18,000°
181,000
36,000d
3,000s 450
272,000 22,700
18,000°
272,000
1,896,000 34,450
different capacities
70,000 Mg/yr (ref 1)
Acetate Ketone
29,500
C 32,000 40,800°
14,000
18,000
136,000
14,000°
7,000°
9,000d
45,400
127,000
e
C 36,000° 38,600°
130,000 417,300
for the same location.
•
By-product from processes producing other products.
publicker acetic acid and ehtyl acetate plants have been shut down and are on standby
1 and 3).
recovers acetic acid and formic acid from a waste stream; operated only to prevent
water pollution 12 to 15 days/month (ref 9}.
-------
II-6
1978 a methanol carbonylation plant at Clear Lake, TX, that uses Monsanto tech-
nology. Produces MEK, formic acid, and ethyl acetate at Pampa.4—7/i3/i
-------
II-7
D. REFERENCES*
1. "Acetic Acid," Chemical Marketing Reporter 217(14), 9 (Apr. 7, 1980).
2. "Formic Acid," Chemical Marketing Reporter 211(12), 9 (Mar. 21, 1977).
3. "Ethyl Acetate," Chemical Marketing Reporter 217(13), 9 (Mar. 31, 1980).
4. "MEK, "Chemical Marketing Reporter 210(26), 9 (Dec. 27, 1976).
5. A. K. Rafie and S. L. Sader, "Acetic Acid," pp. 602.5020A—602.5020F in Chemical
Economics Handbook, Stanford Research Institute, Menlo Park, CA (March 1979).
6. E. M. Klapproth, "Ethyl Acetate Salient Statistics," pp. 643.5030A—643.5030D
in Chemical Economics Handbook, Stanford Research Institute, Menlo Park, CA
(September 1977).
7. T. F. Killiea, "Methyl Ethyl Ketone," pp. 675.5030A—675.5030E in Chemical
Economics Handbook, Stanford Research Institute, Menlo Park, CA (December 1978).
8. Directory of Chemical Producers 1979, United States of America, SRI International,
Menlo Park, CA (November 1979).
9. C. N. Betts, Sonoco Products Company, Hartsville, SC, letter to EPA, Oct. 10,
1978, in response to EPA request for information on the air emissions from the
formic acid process.
10. "Manual of Current Indicators Supplemental Data," pp. 241, 262, and 284 in
Chemical Economics Handbook, Stanford Research Institute, Menlo Park, CA (June
1980).
11. F. S. Wagner, Jr., "Acetic Acid," pp. 124—147 in Kirk-Othmer Encyclopedia of
Chemical Technology, 3d ed., Vol 1, edited by M. Grayson et al., Wiley-
Interscience, New York, 1978.
12. P. D. Cosslett and R. T. Gerry, "Butylenes," pp. 620.5043K,L in Chemical Economics
Handbook, Stanford Research Institute, Menlo Park, CA (June 1976).
13. R. p. Lowry and A. Aguilo, "Acetic Acid Today," Hyrdocarbon Processing 58(11),
103—113 (1974). —
H. "Methanol Makers Head for Record Year," Chemical Week 122(15), 38, 39 (1978).
16. J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Union Carbide Corp.,
South Charleston, WV. Dec. 7, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
III-l
III. PROCESS DESCRIPTIONS
A. INTRODUCTION
The three major processes for commerical production of acetic acid are carbonyla-
tion of methanol, oxidation of butane, and oxidation of acetaldehyde. Until
recently the butane oxidation process, which produces several by-products, in-
cluding MEK, ethyl acetate, and formic acid, had been the major source of acetic
acid. However, more acetic acid is now produced by the methanol carbonylation
process than by any of the other processes.1'2 Very likely this process will
be used for essentially all new, world-wide, acetic acid capacity. Monsanto
claims that the manufacturing costs of their methanol carbonylation process are
lower than those for any other known acetic acid process.3—5
Ethanol fermentation is reported to have been used by Publicker for producing
acetic acid, but no data are available on this process.5
The butanol dehydrogenation process for producing MEK and the esterification of
acetic acid process for producing ethyl acetate are also covered in this section.
B- METHANOL CARBONYLATION FOR PRODUCTION OF ACETIC ACID
1- Basic Process
Acetic acid is produced by the continuous liquid-phase catalytic reaction of
methanol and carbon monoxide:
0
ii
CH3OH + CO * CH3COH
(methanol) (carbon monoxide) (acetic acid)
The catalyst used by Monsanto is a rhodium and iodine system that is very active
and very selective at 200?C and 1.6 MPa. Water and other impurities formed by
the reversible side reactions are recycled to the reactor. The main by-product
comes from the water-gas reaction:
CO + H20 * C0£ + H2
(carbon monoxide) (water) (carbon dioxide) (hydrogen)
-------
III-2
Only small amounts of by-product are formed in the Monsanto process, which is
represented in Fig III-l.3'4
Carbon monoxide (Stream 1), which has been separated from synthesis gas or some
other nearby source, and methanol (Stream 2) are fed to the reactor system.
The crude acetic acid (Stream 3) from the reactor system is fed to the light-ends
column in the purification section. Wet acetic acid (Stream 4) is taken off as
a sidestream and sent to the drying column, the light ends (Stream 5) go over-
head and are recycled to the reactor system, and the heavy bottoms (Stream 6)
also are recycled to the reactor system. In the drying column all the water
and some acetic acid go overhead as wet acetic acid (Stream 7), which is recycled
to the reactor system; dry acetic acid (Stream 8) is removed as bottoms and
sent to the product column. Small quantities of propionic and acetic acid
(Stream 9) are removed from the dry acetic acid in the product column and sent
to an incinerator. The product column overhead (Stream 10) goes to the finish-
ing column, where purified acetic acid (Stream 11) is removed as a sidestream
and sent to storage. The'finishing column overheads (Stream 12) and bottoms
(Stream 13) are recycled to the process, resulting in a 99% yield of acetic acid
based on methanol.3
The light ends (Vent A) vented from the reactor system and the vent gases (Vent
B) from the column vents are combined and sent to a proprietary scrubber system,
considered part of the process and not a control device, where essentially all
the light material (Stream 14) is removed and recycled to the reactor system.
The scrubber system is vented to a flare.3
Storage emission sources (Vents C and D) result from storage of methanol and
acetic acid. Handling emissions (Vents E and F) result from loading of acetic
acid into railroad tank cars and into barges.
Fugitive emissions (G) occur when leaks develop in valves or in pump or compressor
seals. When process pressures are higher than the cooling water pressure, VOC
can leak into the cooling water and escape as fugitive emissions from the cooling
tower.
-------
FL^RE
SCRUBBER
SYSTEM
MOKIOXIDE
BY
METUAJJOL
LKaHT-
EWD*
COLUMKl
FUGITIVE
OVERAUU PL**JT
RECVCLE TO
ACETIC
RECYCLE T<
&
REA.CTOR
TO IKJCIM6RATOR
PRODUCT
COV.UMKJ
COLUMU
TO USER
BV PlPEUKJE.
H
H
M
UJ
Fig. III-l. Process Flow Diagram for Acetic Acid by Methanol Carbonylation
-------
III-4
Incineration of the propionic and acetic acid waste stream (Stream 9), la which
VOC are emitted with the flue gases, can also be a source of secondary emissions.
2. Process Variation
In the BASF methanol carbonylation process, which was developed before the Monsanto
process, cobalt iodide is used as the catalyst at 250°C and 52 MPa. After the
light ends from the reactor are scrubbed with the feed methanol to recover methyl
iodide, they are sent to the fuel supply or are returned to the carbon monoxide
separation plant. The crude acetic acid is purified in five columns, and azeo-
tropic distillation is used for final acid purification. The entrainer used in
the azeotropic distillation is the mixture of by-products that are formed during
the reaction. By-product production in the BASF process is much higher than in
the Monsanto process, resulting in the lower yield, based on methanol, of only
90%.6—8
C. BUTANE OXIDATION PROCESS FOR PRODUCTION OF ACETIC ACID
Acetic acid is produced as the predominant product of the liquid-phase catalytic
oxidation of n-butane, with either air or oxygen used as the oxidant, by the
following reaction:
0
It
CH3CH2CH2CH3 + 02 >• CH3COH + by-products + H20
(n-butane) (oxygen (acetic acid) (water)
or air)
The catalyst can be cobalt or manganese acetate, the temperature 150 to 225°C,
and the pressure about 5.5 MPa. The by-products are many and include alcohols,
ketones, esters, aldehydes, and carboxylic acids. Of these, ethanol, MEK, ethyl
acetate, formic acid, and propionic acid are usually recovered and used or are
sold.9'10
n-Butane and compressed air or oxygen are fed to a reactor. Crude acetic acid
is separated from unreacted n-butane and inert gases, then stripped or flashed
to remove dissolved butane and inert gases, and sent to the purification section.
The unreacted n-butane is condensed and recycled to the reactor; the remaining
inert gases, which contain some hydrocarbons, are sent to an absorber, which
may use gas oil for additional butane recovery, and are then vented. If oxygen
-------
III-5
is used, refrigerated condensers may be adequate to recover the butane because
of the reduced flow of inert gases.5'9'11'12
The low-boiling organics are separated from the crude acetic acid by conventional
distillation. Azeotropic distillation is used to dry and purify the crude acetic
acid. Recovery and purification of the various by-products require several
distillation columns and involve extractive distillation or azeotrope breakers
or both. Large amounts of liquid organic wastes are burned in boilers to recover
their heat values. The aqueous waste is usually treated before being discharged.9
Process emissions are the vent gases from the reactor, which contain the nitrogen
from the air when it is used to supply the oxygen, and the vent gases from the
several distillation columns. The sources of storage and handling, secondary,
and fugitive emissions are similar to those for the methanol carbonylation process,
but the emissions may be significantly higher because of the many more volatile
by-products produced.9
D. ACETALDEHYDE OXIDATION PROCESS FOR PRODUCTION OF ACETIC ACID
Acetic acid is made by the catalytic liquid-phase oxidation of acetaldehyde as
shown by the reaction
0 0
H "
CH3CH + 1/202 > CHgCOH
(acetaldehyde) (oxygen (acetic acid)
or air)
There are several variations to the process. The catalyst may be manganese or
cobalt acetate and the reaction carried out in a large excess of acetic acid in
a continuous reactor. Temperatures may range from 55 to 80°C and pressures
from atmospheric to 520 kPa. Air or oxygen may be used as the oxidant, and
ethanol may be mixed with the acetaldehyde feed and the two components oxidized
together.5/6/9
Acetaldehyde and air or oxygen or oxygen-enriched air are fed to the reactor.
Both a liquid and a gaseous stream leave the reactor. The gaseous stream is
cooled and scrubbed several times with dilute .acid and then with water to recover
the organics, and the inert gases and unrecovered organics are vented to the
-------
III-6
atmosphere. The liquid stream is sent to the purification section, where unreacted
acetaldehyde is removed by distillation and then recycled to the reactor. The
dilute acetic acid is then distilled to remove water and impurities; the resultant
dry purified acetic acid is sent to storage.9
The process emissions are the scrubbed vent gases from the reactor and the vent
gases from the distillation columns. The sources of storage and handling, secondary/
9
and fugitive emissions are similar to those for the methanol carbonylation process-
E. ETHANOL FERMENTATION PROCESS FOR PRODUCTION OF ACETIC ACID
No information is currently available on the ethanol fermentation or oxidation
process to produce acetic acid.
F. BUTANOL DEHYDROGENATION PROCESS FOR PRODUCTION OF MEK
MEK is produced by the catalytic vapor-phase dehydrogenation of sec-butyl alcohol
by the following reaction:
OH 0
I it
(butyl alcohol) (MEK) (hydrogen)
The catalyst is zinc oxide or a zinc-copper alloy and the temperature range is
400 to 550°C. The reaction takes place at atmospheric pressure. The sec-butyl
alcohol is vaporized and preheated before it enters the reactor. The reaction
gases are condensed and may be scrubbed with water or a solvent to remove entrained
MEK and sec-butyl alcohol from the hydrogen. The hydrogen can be used, burned
in a furnace, or flared. The MEK is separated from the condensed reaction product
by distillation, and unreacted sec-butyl alcohol is sent to a recovery step for
recycle to the process.6'11
The only process emission source is vented gas from the distillation columns.6
The sources of storage and handling, secondary, and fugitive emissions are similar
to those previously described for other processes.
G. ESTERIFICATION PROCESS FOR PRODUCTION OF ETHYL ACETATE
Ethyl acetate is produced by the esterification of acetic acid and ethanol by
the following reaction:
-------
III-7
0
CH3CH2OH + CH3COH - 5- C
(ethanol) (acetic acid) (ethyl acetate) (water)
The catalyst employed is usually sulfuric acid and the process can be either
continuous or batch.6
In the continuous process, acetic acid, excess ethanol, and sulfuric acid are
mixed, passed through a preheater, anu then sent to a reactor (esterifying column)
held at 80°C and atmospheric pressure. The overhead distillate goes to a separating
column, where an azeotrope of ethyl acetate, ethanol, and water goes overhead
and is sent to a mixer for addition of water. The mixture goes to a decanter,
where it separates into two layers. The bottom layer is mostly water and is
recycled to the lower part of the separating column. The bottoms from the
separating column are recycled to the bottom section of the esterifying column,
where the alcohol is vaporized and a stream containing some sulfuric acid is
removed and sent to waste. The top layer from the decanter is mostly ethyl
acetate and goes to a drying column, where enough ethyl acetate is distilled
overhead to remove the water and alcohol; this stream is recycled to the separating
column. The bottoms of the drying column go to a finishing column, where ethyl
acetate is separated overhead and sent to storage and the bottoms are sent to
6
waste.
Process emission sources can be the reactor condenser vent, the distillation
column vents, and the decanter vent. The sources of storage and handling, secondary,
and fugitive emissions are similar to those previously discussed for other processes.
H. ACETALDEHYDE PROCESS FOR PRODUCTION OF ETHYL ACETATE
Ethyl acetate is also produced from acetaldehyde. No data are currently avail-
able on the process or its emissions.13'14
-------
III-8
I. REFERENCES
1. A. K. Rafie and S. L. Soder, "Acetic Acid," pp. 602.5020A—602.5020R in Chemical
Economics Handbook, Stanford Research Institute, Menlo Park, CA (March 1979).
2. "Methanol Makers Head for Record Year," Chemical Week 122(15), 38, 39 (1978).
3. H. D. Grove, "Lowest Cost Acetic Via Methanol," Hydrocarbon Processing 51(11),
76—78 (1972). —
4. L. F. Hatch and S. Matar, "From Hydrocarbons to Petrochemicals Part 6. Petro-
chemicals from Methane," Hydrocarbon Processing 56(10), 153—163 (1977).
5. R. P. Lowry and A. Aguilo, "Acetic Acid Today," Hydrocarbon Processing 58(11),
103—113 (1974). =
6. F. A. Lowenheim and M. K. Moran, Faith, Keyes, and Clark's Industrial Chemicals,
4th ed., Wiley, New York, 1975.
7. P. Ellwood, "Acetic Acid Via Methanol and Synthesis Gas," Chemical Engineering
76(10), 148—150 (1969).
8. H. Hohenschutz et al., "Newest Acetic Acid Process," Hydrocarbon Processing
45(11), 141—144 (1966).
9. J. W. Pervier et al., Houdry Division, Air Products and Chemicals, Inc.,
Survey Reports on Atmospheric Emissions from the Petrochemical Industry,
vol. I, EPA-450/3-73-005a, Research Triangle Park, NC (January 1974).
10. L. F. Hatch and S, Matar, "From Hydrocarbons to Petrochemicals Part 7. Petro-
chemicals from n-Paraffins," Hydrocarbon Processing 56(11), 349—357 (1977).
11. S. Takaoka, Acetic Acid, Report 37, A private .report by the Process Economics
Program, Stanford Research Institute, Menlo Park, CA (March 1968).
12. L. F. Hatch and S. Matar, "From Hydrocarbons to Petrochemicals Part 12.
Petrochemicals from n-Paraffins," Hydrocarbon Processing 57(8), 153—165 (1978).
13. F. S. Wagner, Jr., "Acetic Acid and Derivatives," pp. 124—147 in Kirk-Othmer
Encyclopedia of Chemical Technology. 3d ed., vol. 1, M. Grayson et al., editors,
Wiley-Interscience, New York, 1978.
14. G. Prendergast, Texas Eastman Company, Longview, TX, letter to EPA Jan. 26, 1979,
in response to EPA request for information on the air emissions from the ethyl
acetate process.
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
IV-1
IV. EMISSIONS
INTRODUCTION
Emissions in this report are usually identified in terms of volatile organic
compounds (VOC). VOC are currently considered by the EPA to be those of a
large group of organic chemicals, most of which, when emitted to the atmosphere,
participate in photochemical reactions producing ozone. A relatively small
number of organic chemicals have low or negligible photochemical reactivity.
However, many of these organic chemicals are of concern and may be subject to
regulation by EPA under Section 111 or 112 of the Clean Air Act since there are
associated health or welfare impacts other than those related to ozone formation.
Table IV-11—16 summarizes the estimates of uncontrolled process emissions from
the major processes producing acetic acid, by-product formic acid, ethyl acetate,
or methyl ethyl ketone. These estimates do not include emissions from storage
and handling, fugitive, or secondary sources. They are based on data from industry
or from theory, whichever is the better available source, and are not representa-
tive of actual data from any specific plant. Storage and handling, fugitive,
and secondary emissions for the entire synthetic organic chemicals manufactur-
ing industry are covered by separate EPA documents.
METHANOL CARBONYLATION PROCESS FOR ACETIC ACID
The process flow diagram for the production of acetic acid by the methanol car-
bonylation process, given in Fig. III-l, was taken from the literature and repre-
sents the Monsanto process.1—3 Both the reactor vent gases (Vent A) and the
distillation vent gases (Vents B) are sent through the scrubber system and then
to the flare. No data are available on the flow or composition of the gases
from vent A or B. The stream to the flare consists of methane, nitrogen, carbon
dioxide, carbon monoxide, and hydrogen.4
The data on uncontrolled emissions from the (older) BASF high-pressure process
used by Borden are either not available or are confidential.5 Estimates of the
composition and flow of the vent gases from the reactor off-gas scrubber and
from the light-ends distillation column, based on a theoretical material balance
-------
IV-2
Table IV-1. Estimates of Uncontrolled VOC Emissions from
Processes Producing Acetic Acid, Methyl Ethyl Ketone, and Ethyl Acetate
Process
Methanol carbonylation
Butane oxidation0
Product or
By-Products
Acetic acid
Acetic acid
Methyl ethyl ketone
Ethyl acetate
Formic acid
Total for butane oxidation
Acetaldehyde oxidation
Butanol dehydrogenation
Ethanol esterif ication
Acetic acid
Methyl ethyl ketone
Ethyl acetate
Capacity
(Mg/yr)
250,000
250,000
40,000
30,000
10,000
330,000
200,000
100,000
10,000
VOC
Ratio
(g/kg)
2b
38d
6.9
1.2
•0.3
Emissions
Rate
a (kg/hr)
57b
1400
160
14
0.3
g of emissions per kg of product produced.
Based on estimated VOC emissions from Monsanto process as reported by Monsanto
(see ref 15) .
°With oxygen; VOC emissions from the butane oxidation with air process are
estimated by Celanese to be about three times higher (see ref 16).
g of emissions per kg of total product mix produced.
-------
IV-3
for the BASF process calculated by S. Takaoka,6 are given in Tables IV-2 and
IV-3. These estimates are not meant to represent the emissions from any actual
plant.
The estimate given in Table IV-1 for uncontrolled process emissions is based on
estimates from Monsanto.15 The incineration of the heavy ends is a potential
source of secondary VOC emissions; however, no data are available on their amount
or on.the amounts of fugitive or storage and handling emissions.
BUTANE OXIDATION PROCESS FOR ACETIC ACID
The sources of emissions from butane oxidation processes include the butane
recovery vents and purification vents. Table IV-4 gives the composition of the
uncontrolled emissions from the refrigerated condensers used to recover butane
in an oxygen-based butane oxidation plant.7 The uncontrolled emissions from
the distillation columns in the purification section of the same plant are esti-
mated to contain 0.2 g of VOC per kg of total product mix produced by the plant.
Some components in the purification vent gases include methyl acetate, acetone,
methyl formate, acetaldehyde, methanol, ethyl acetate, butane, ethane, methane,
other organics, carbon dioxide, carbon monoxide, and nitrogen.8 The temperatures
of the vent streams were not included in the available data. Available data on
the emissions from the air-based butane oxidation process are difficult to inter-
pret and incomplete; so no estimate was made of the VOC emissions. The estimate
of uncontrolled emissions shown in Table IV-1 are for an oxygen-based butane
oxidation process.
ACETALDEHYDE OXIDATION FOR ACETIC ACID
The total process emissions for a process based on acetaldehyde oxidation with
air to produce acetic acid include the inert gases from the air with unrecovered
organics from the reaction section plus the vent gases from the purification
section. Table IV-5 gives the composition of the vent gases from the reaction
section.9 The total VOC emissions were estimated based on a weighted average
of reported emissions from two plants (see Table IV-1). The VOC emitted are
acetaldehyde, ethanol, ethyl acetate, ethyl formate, and n-propyl acetate. An
analysis of the data shows that the ratio of VOC emission from the reaction
section to the product produced varies with the production rate; one plant reports
that when it operates near capacity the VOC emission ratio is twice that shown
in Table IV-1.9'10
-------
IV-4
Table IV-2. Estimated Composition of Gas from Reactor
Off-Gas Scrubber Vent in a BASF Methanol Carbonylation
Plant Producing Acetic Acid
Component
Methanol
Light ends
Total VOC
Hydrogen
Carbon monoxide
Carbon dioxide
Methane
Total
Composition
(wt %)
3.5
0.6
4.1
1.5
54
37
3.4
100
Emission Ratio
(g/kg)b
12.9
2.1
15
5.5
204
141
12.8
378
a
Based on a theoretical material balance (see ref 6)
g of emissions per kg of acetic acid produced.
-------
IV-5
Table IV-3. Estimated Gas Composition, of Light-Ends
Distillation Column Vent in a BASF Methanol
Carbonylation Plant to Produce Acetic Acid
Component
Hydrogen
Carbon monoxide
Carbon dioxide
Methane
Total
Composition
(wt %)
0.28
30
67,5
2.22
100
Emission Ratio
(g/kg)b
0.079
8.59
19.3
0.63
28.6
Based on a theoretical material balance (see ref 6)
g of emissions per kg of acetic acid produced.
-------
IV-6
Table IV-4. Composition of Vent Gas from Refrigerated Butane Recovery Condensers in
Plant Using Butane Oxidation with Oxygen Process
Component
Butane
Ethane
Other organics
Total VOC
Methane
Carbon dioxide
Carbon monoxide
Nitrogen
Argon
Total
Separator
Composition
(wt %)
6.5
0.8
7.3
4.6
56
9
8.1
15
100
Condenser
"Emission Ratio
(g/kgr
22
3
25
16
190
30
26
53
340
Stripper
Composition
(wt %)
11
1
4
16
1
80
1
1
1
100
Condenser
Emission Ratio
(gAg)
9
0.8
3
12.8
0.8
65
0.8
0.8
0.8
81
See ref 7.
g of emissions per kg of total product mix produced.
-------
IV-7
Table IV-5. Vent Gas Composition from Reactor Section in an
Acetaldehyde Oxidation Plant
Component
Acetaldehyde (VOC)
Nitrogen
Carbon dioxide
Oxygen
Carbon monoxide and methane
Composition
(wt %)
0.2
96
2.8
0.6
0.4
100
Emission Ratio
(g/kg)
2
960
28
6
4
1000
aSee ref 9.
g of emissions per kg of product produced.
-------
IV-8
E. BUTANOL DEHYDROGENATION PROCESS FOR MEK
The only process emissions from butanol dehydrogenation are the VOC in the non-
condensables vented from the distillation column condensers in the purification
section as the hydrogen produced in the reactor either is burned as fuel or is
used elsewhere in the plant complex. The estimate of this emission (see Table
IV-1) is based on information from three plants and on engineering judgement.
The emissions may be continuous or periodic, depending on the method used to
purge the noncondensables from the condensers.11—13
F. ESTERIFICATION PROCESS FOR ETHYL ACETATE
The estimate of VOC emissions from the esterification process to produce ethyl
acetate (See Table IV-1) is based on limited data from one plant14 and on engi-
neering judgement. A relatively small amount of ethyl acetate is produced by
this process; most is produced as a by-product.
-------
IV-9
G. REFERENCES
1- H, D. Grove, "Lowest Cost Acetic Via Methanol," Hydrocarbon Processing 51(11),
76—78 (1972). —
2. L. F. Hatch and S. Matar, "From Hydrocarbons to Petrochemicals Part 6. Petro-
chemicals from Methane," Hydrocarbon Processing 56(10), 153—163 (1977).
3- R. P. Lowry and A. Aquilo, "Acetic Acid Today," Hydrocarbon Processing 58(11),
103—113 (1974). —
4- J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Monsanto Co., Texas
City, TX, Dec. 13, 1977 (on file at EPA, ESED, Research Triangle Park, NC).
5- J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Borden Chemical, Geismar,
LA, Mar. 3, 1978 (on file at EPA, ESED, Research Triangle Park, NC).
6- S. Takaoka, Acetic Acid, Report 37, A private report by the Process Economics
Program, Stanford Research Institute, Menlo Park, CA (March 1968).
7- J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Union Carbide Corp.,
South Charleston, WV, Dec. 7, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
8- F. D. Bess, Union Carbide Corporation, letter dated Aug. 25, 1978 to J. A. Key,
IT Enviroscience, Inc., with information on emissions from butane oxidation
system at Brownsville, TX (on file at EPA, ESED, Research Triangle Park, NC).
9- J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Celanese, Clear Lake,
TX, Oct. 12, 1977 (on file at EPA, ESED, Research Triangle Park, NC).
!0. J. C. Edwards, Tennessee Eastman Co., letter to EPA with information on Kingsport,
TN, acetic acid plant, May 15, 1978.
H- C. N. Hudson, ARCO Chemical Co., letter to EPA with information on MEK unit in
ARCO's Lyondell Plant at Channelview, TX, May 15, 1978.
12. J. A. Mullins, Shell Oil Co., letter to EPA with information on MEK plant at
Deer Park, TX, June 22, 1978.
l3- G. L. Otis, Exxon Chemical Co., letter dated June 7, 1978, to EPA with information
on MEK unit in their Bayway, NJ, Chemical Plant.
H- J. C. Edwards, Tennessee Eastman Co., letter to EPA with information on Kingsport,
TN, ethyl acetate plant, Aug. 11, 1978.
-------
IV-10
15. N. B. Gallozzo, Monsanto Plastics & Resins Co., letter dated Oct. 22, 1979, to
D. R. Patrick, EPA, with comments on draft Acetic Acid Report (on file at EPA,
ESED, Research Triangle Park, NC).
16. R. H. Maurer, Celanese Chemical Company, Inc., letter dated Oct. 10, 1979, to
D. R. Patrick with comments on draft Acetic Acid Report (on file at EPA, ESED,
Research Triangle Park, NC).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
V-l
V. APPLICABLE CONTROL DEVICES
A- INTRODUCTION
The control devices shown in Table V-l were selected for new plants because
either they are in use or they appear to be feasible based on a general knowledge
of the emissions and of similar emissions from other processes controlled by
such devices. The costs and cost effectiveness for these applications have not
been determined.
B- METHANOL CARBONYLATION PROCESS FOR ACETIC ACID
The process emissions from the reactor off-gas scrubber system in the Monsanto
process is controlled by a flare. Even though the scrubber system is part
of the process and is not considered to be a control device, the distillation
column vent gases may be sent to the scrubber system as a control technique.1
Monsanto reports an estimate of controlled VOC emissions from the flare of
0.03 g of acetic acid emission per kg of acetic acid produced, with an esti-
mated destruction efficiency of 98.5% for the flare.2
An emission reduction of 99% was used to calculate the controlled emissions
from a flare used as a control device on the emissions from the off-gas scrubber
and from all distillation vents (see Table V-l). This reduction is based on a
flare that is designed so that the normal flow is greater than 10% of design.3
The use of a flare to control emissions from a vacuum column, where air leaks
may cause an explosive mixture in the flare or header system, must be examined
carefully and proper precautions taken to prevent a hazardous condition.4
c- BUTANE OXIDATION PROCESS FOR ACETIC ACID
No control devices are given for a new butane oxidation process, because no new
acetic acid plants are expected to use the butane oxidation process as it is
very energy intensive.5 See Appendix B for retrofit considerations for existing
butane oxidation processes.
D- ACETALDEHYDE OXIDATION PROCESS FOR ACETIC ACID
An acetic acid and water scrubber was selected as a control device option for
the process emissions from an acetaldehyde oxidation process producing acetic
-------
Table V-l. Estimates of Controlled VOC Emissions from Processes Producing Acetic Acid,
Methyl Ethyl Ketone, and Ethyl Acetate
Process
Product or
By-Product
Methanol carbonylation Acetic acid
Butane oxidation Acetic acid
Methyl ethyl ketone
Ethyl acetate
Formic acid
Total for butane oxidation
Acetaldehyde oxidation Acetic acid
Butanol dehydrogenation Methyl ethyl ketone
Ethanol esterification Ethyl acetate
Capacity
(Mg/yr) Control Device
250,000 Flare
250,000
40,000
30,000
10,000
330,000
200,000 Scrubber
100,000 Flare
10,000 None
VOC
. VOC
Emission
Reduction Ratio
(%) (g/kg)£
99 0.02.
99 0.069
99 0.012
0.3
Emissions
Rate
1 (kg/hr)
0.57
NJ
1.6
0.14
0.3
g of emissions per kg of product produced.
See Appendix B for retrofit considerations for existing butane oxidation processes; no new butane oxidation plants
are likely.
-------
V-3
acid (see Table V-l). This option is based on the current use of such scrubbers
to control the emissions from acetaldehyde oxidation processes that use air as
the oxidant. A reduction efficiency of 99% (see Table V-l) was used to calculate
the controlled emissions from this process based on reported data. A conceptual
design of an acetic acid and water scrubber for this application has not been
made nor have data been developed on costs or cost effectiveness.6'7 The problems
involved with retrofitting this control to an existing acetaldehyde process are
discussed in Appendix B.
E- BUTANOL DEHYDROGENATION PROCESS FOR MEK
A flare was selected as an emission control device option for the vent gases
from the purification section condensers. An emission reduction of 99% was
used to calculate the controlled emissions (see Table V-l) based on such a
flare that is designed so that the normal flow is greater than 10% of design.3
F- ESTERIFICTION PROCESS FOR ETHYL ACETATE
No control system has been identified for this process because the estimated
emissions for the industry are small. The estimated controlled emissions are
therefore the same as the uncontrolled emissions (see Table V-l). No control
devices are used in the one plant for which data are available.8
-------
V-4
G. REFERENCES
1. J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Monsanto Co., Texas
City, TX, Dec. 13, 1977 (on file at EPA, ESED, Research Triangle Park, NC).
2. N. B. Galluzzo, Monsanto Plastics and Resins Co., letter dated Oct. 22, 1979,
to D. R. Patrick, EPA, with comments on draft Acetic Acid Report (on file at
EPA, ESED, Research Triangle Park, NC).
3. V. Kalcevic, IT Enviroscience, Inc., Control Device Evaluation. Flares and
the Use of Emissions as Fuels (in preparation for EPA, ESED, Research Triangle
Park, NC).
4. J. C. McGill and E. C. McGill, "Save Lost Hydrocarbons," Hydrocarbon Processing
56(5), 158—160 (1978).
5. A. K. Rafie and S. L. Soder, "Acetic Acid," pp 602.5020A—602.5020R in Chemical
Economics Handbook, Stanford Research Institute, Menlo Park, CA (March 1979).
6. J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Celanese, Clear Lake^_
TX, Oct. 12, 1977 (on file at EPA, ESED, Research Triangle Park, NC).
7. J. C. Edwards, Tennessee Eastman Co., letter to EPA with information on Kingsport,
TN, acetic acid plant. May 15, 1978.
8. J. C. Edwards, Tennessee Eastman Co., letter to EPA with information on
Kingsport, TN, ethyl acetate plant, Aug. 11, 1978.
*Usually, when a reference is located at the errd of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
VI-1
VI. IMPACT ANALYSIS
A- ENVIRONMENTAL IMPACT
Table VI-1 shows the environmental impact of reducing VOC emissions by applica-
tion of the described control systems (Sect. V) to typical new plants for produc-
tion of acetic acid, methyl ethyl ketone, and ethyl acetate having the capacities
indicated. The environmental impacts of controlling VOC emissions from storage
and handling, fugitive, and secondary sources are not included in the estimates
in Table VI-1 but are believed to be similar to those from other processes in
the synthetic organic chemicals manufacturing industry.
The projected production rates for 1978 are 1,240,000 Mg for acetic acid, 74,100 Mg
for ethyl acetate, and 244,000 Mg for MEK, all based on the reported 1977 produc-
tion and,estimated annual growth rate.1—4 Formic acid production was not pro-
jected because it is produced only as a by-product and data are not available
on emissions, if any, resulting solely from its recovery.5 Table VI-2 lists
the estimated current VOC emissions from each acetic acid process and for the
methyl ethyl ketone and ethyl acetate processes. These estimates are based on
the projected production of each product for 1978 adjusted by the fraction of
total production capacity for each acetic acid process before the recent expan-
sions and on an estimated current emission ratio to production for each process.
These estimates include emissions from the processes only, not those from storage
and handling, secondary, or fugutive sources. Emissions from these sources are
believed to be typical for the synthetic organic chemicals manufacturing industry.
The water effluent from scrubbers may have an adverse environmental impact unless
treated in a properly designed and operated wastewater treatment plant.
B- OTHER IMPACTS
Energy and control cost impacts have not been determined for the control devices
selected in Section V.
-------
Table VI-1. Environmental Impact of Controlled Typical Processes Producing
Acetic Acid, Methyl Ethyl Ketone, and Ethyl Acetate
Process
Methanol carbonylation
Butane oxidation
Total for butane oxidation
Acetaldehyde oxidation
Butanol dehydrogenation
Ethanol esterification
Product or
By-Products
Acetic acid
Acetic acid
Methyl ethyl ketone
Ethyl acetate
Formic acid
Acetic acid
Methyl ethyl ketone
Ethyl acetate
Capacity Control Device
(Mg/yr) or Technique
250,000 Flare
250,000
40,000
30,000
10,000
330,000
200,000 Scrubber
100,000 Flare
10,000 None
VOC Emission
Reduction9
(%) (Mg/yr)
99 495
99 1400
99 119
impact of controlling process emissions; does not include storage and handling, fugitive, or secondary
emissions.
No control devices are given, as no new butane oxidation plants are likely; see Appendix B for retrofit
cons iderations.
KJ
-------
Table VI-2. Estimate of Current Industry Emissions from Processes Producing Acetic Acid,
Methyl Ethyl Ketone, and Ethyl Acetate
Process
Methanol carbonylation
Butane oxidation
Product or
By-Products
Acetic acid
Acetic acid
Control Device
or Technique
Monsanto process
Refrigerated vent
1978 VOC Emissions (Mg) a
30b
4400°
.. ^, , _ , , ^ condensers and
Methyl ethyl ketone _n a
flare
Ethyl acetate
Formic acid
Acetaldehyde oxidation Acetic acid Scrubber 880
Butanol dehydrogenation Methyl ethyl ketone Flare 22
Ethanol esterification Ethyl acetate None 10
a
Emissions from the process only; does not include emissions from storage and handling, fugitive, or
secondary sources.
Emissions are from the BASF process; little VOC is emitted from the Monsanto process.
°The total industry emissions are estimated from the data for the butane oxidation with oxygen process only.
Refrigerated vent condensers on separator condenser and purification section vents; flare on stripper
condenser vent.
-------
VI-4
C. REFERENCES
1. "Acetic Acid," Chemical Marketing Reporter 211(15), 9 (Apr. 11, 1977).
2. "Ethyl Acetate," Chemical Marketing Reporter 211(21), 9 (May 23, 1977).
3. "MEK," Chemical Marketing Reporter 210(26). 9 (Dec. 27, 1976).
4. "Manual of Current Indicators Supplemental Data," pp. 201, 224, and 242 in
Chemical Economics Handbook, Stanford Research Institute, Menlo Park, CA
(October 1978).
5. "Formic Acid," Chemical Marketing Reporter 211(12), 9 (Mar. 21, 1977).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
A-l
Table- A-l. Physical Properties of Acetic Ac-id*
Synonyms
Molecular formula
Molecular weight
Vapor pressure
Vapor specific gravity
Boiling point
Melting point
Density
Water solubility
Methane carboxylic acid,
ethylic acid, glacial
acetic acid
C2H4°2
60.05
1.52 kPa at 20°C
2.07
117.9°C
16.6°C
1.0492 g/ml at 20°C/4°C
Infinite
*J. Dorigan et al., "Acetic Acid," p. AI-16 in Scoring of Organic
Air Pollutants, Chemistry, Production and Toxicity of Selected
Synthetic Organic Chemicals (Chemicals A-C), MTR-7248, Rev. 1,
Appendix I, MITRE Corp., McLean, VA (September 1976).
-------
A-2
Table A-2. Physical Properties of Formic Acid*
Synonyms
Molecular formula
Molecular weight
Vapor pressure
Vapor specific gravity
Boiling point
Melting point
Density
Water solubility
Methanoic acid,
hydrogen carboxylic acid
CH2°2
46.3
5.65 kPa at 25°C
1.59
100.8°C
8.3°C
1.2201 g/ml at 20°C/4°C
Infinite
*J. Dorigan et al., "Formic Acid," p. AIII-16 in Scoring of Organic
Air Pollutants. Chemistry, Production and Toxicity of Selected
Synthetic Organic Chemicals (Chemicals F-N), MTR-7248, Rev. 1,
Appendix III, MITRE Corp., McLean, VA (September 1976).
-------
A-3
Table A-3. Physical Properties of Ethyl Acetate*
Synonyms
Molecular formula
Molecular weight
Vapor pressure
Vapor specific gravity
Boiling point
Melting point
Density
Water solubility
Acetic ester, ethylacetic
ester, ethyl etharate
C4H8°2
88.10
12.3 kPa at 25°C
3.04
77.06°C
-83.578°C
0.8946 g/ml at 25°C/4°C
89 g/litar of H0
*J. Dorigan et al., "Ethel Acetate," p. AII-234 in Scoring of Organic
Air Pollutants, Chemistry, Production and Toxicitv of Selected
Synthetic Organic Chemicals (Chemicals D-E), MTR-7248, Rev. 1,
Appendix II, MITRE Corp., McLean, VA (September 1976).
-------
A-4
Table A-4. Physical Properties of Methyl Ethyl Ketone*
Synonyms 2-Butanone,
methyl acetone
Molecular formula C H O
Molecular weight 72.12
Vapor pressure 12.85 kPa at 25°C
Vapor specific gravity 2.41
Boiling point 79.6°C
Melting point -86.35°C
Density 0.8054 g/ml at 20°C/4°C
Water solubility Infinite
*J. Dorigan et al., "Methyl Ethyl Ketone," p. AIII-192 in
Scoring or Organic Air Pollutants. Chemistry, Production
and Toxicity of Selected Synthetic Organic Chemicals
(Chemicals F-N), MTR-7248, Rev. 1, Appendix III, MITRE
Corp., McLean, VA (September 1976).
-------
B-l
EXISTING PLANT CONSIDERATIONS
To gather information for the preparation of this report four site visits were
made to manufacturers of acetic acid. Trip reports have been cleared by the
companies concerned and are on file at ESED in Durham, NC.1—5 Some of the
pertinent information concerning process emissions from these existing acetic
acid plants is presented in this appendix. Other information is from letters
to EPA from companies that produce acetic acid, MEK, or ethyl acetate in response
to requests for information on process emissions from processes that produce
those chemicals.6—10 Also included is information received with comments on
the draft Acetic Acid Report.11'12
A. CONTROLS AT EXISTING PLANTS
1. Monsanto, Texas City, TX
Acetic acid is produced by carbonylation of methanol by a low-pressure, liquid-
phase process developed and commercialized by Monsanto and being licensed to
other companies. The process consists of a reaction system, a scrubber system,
and a distillation system. The emission from the scrubber system is the only
process emission and goes to a flare. All the column accumulators in the
distillation system are vented back to the scrubber system. The unit capacity
is 350 million Ib of acetic acid per year. The unit was completed in 1970 and
there have been no major modifications made since that time.1
Monsanto reports the estimated .controlled emissions from the flare to be the
following:
Rate
(q/sec)
2.25
0.19
«N*»v^>>* *»^* •• «• — - — —
ag of VOC per kg of product produced.
bBasis: nominal 50,000-lb/hr production rate.
Monsanto estimates that halogen compounds also leave the flare at a rate of 1
to 2 Ib/hr and that some VOC escapes the scrubber device to the flare. They
Flare Effluent
Carbon monoxide
Acetic acid
Ratio
(
-------
B-2
also report that the flare vendor estimates destruction of VOC (acetic acid) at
98.5%; destruction of CO is estimated to be 99%.1X
2. Borden, Geismar, LA
In the BASF high-pressure acetic acid process used by Borden at Geismar, LA,
the reactor off-gas from the high-pressure separator is recycled to the process.
The emissions from the off-gas scrubber that originate in the low-pressure
separator are sent to a" flare that also serves other processes. The emissions
from the vents on the atmospheric distillation columns go through a series of
scrubbers for recovery of organics. Chilled methanol is used in the final
scrubber, with an estimated removal efficiency of 80%, and is used as an emission
control device before the vent gases are released to the atmosphere. The
emissions from the liquid-ring vacuum pump serving the two vacuum distillation
columns go directly to the atmosphere. The Borden plant was built in about
1964, and no major modifications have been made since then.2
3. Union Carbide, Bronsville, TX
Acetic acid is produced by the liquid-phase oxidation on n-butane with oxygen.
By-products of the reaction that are recovered at the Brownsville plant are
ethanol, methyl ethyl ketone, ethyl acetate, and formic acid. Acetic anhydride
is produced from acetic acid by a ketene process licensed from Tennessee Eastman.
The Brownsville plant was originally built in 1950 by Carthage Hydrocol Co. to
\
produce gasoline and other fuels and chemicals from natural gas, but was shut
down in 1953. Standolind Oil and Gas Co. acquired the plant and made additions
and modification to it; however, because of poor economics, it was shut down in
1957. Union Carbide purchased the facilities and converted the equipment to
produce acetic acid, etc., in 1961, and added one new still. The plant was
expanded in 1965.
Process emissions from the butane oxidation with oxygen process are controlled
by refrigerated vent condensers and a flare. A refrigerated vent condenser is
used to control the VOC in the vent gases from the separator condenser and has
a reduction efficiency of 68%; the temperatures of the streams in and out of
the control device are not currently available. The flare is used as the
control device for the VOG in the emissions from the stripper vent condenser
and is sized to handle flows from other sources. Very low pressure ratings on
some vessels have prevented use of the flare on their vents. Refrigerated vent
condensers are used as control devices on the vents from the crude separation
-------
B-3
columns and the topping columns in the purification section. The available
data on the controlled emissions from these vent condensers show wide variations,
believed to be due to erratic operation of the refrigeration equipment at the
time that the data were taken. The temperatures of the streams to and from the
condensers are not currently available. An estimate of the controlled emissions
was made based on the emissions when the refrigeration equipment was believed
to be operating normally. The VOC reduction was estimated at 60% (see Table B-l).
The other columns in the purification section are not normally vented.3'4
Celanese, Clear Lake, TX5
The acetic acid unit was constructed in 1969—1970 by Brown and Root to a
Celanese design. No major modifications have been made since the unit was
constructed. The process used involves the catalytic air oxidation of liquid
acetaldehyde. The off-gases from the reactor are largely nitrogen and carbon
dioxide from the air fed to the reactor and are scrubbed with water in the
reactor vent scrubber to recover product and raw material before they are
discharged to the atmosphere. The composition and flow of these emissions
(waste gas 1) in lb/1000 Ib of acetic acid produced are given in Table B-2 for
two different production rates.
The reaction product is purified by distillation, and the gases from the vents
on the distillation column condensers and accumulators are collected and sent
through the unit vent scrubber. The composition and vent rate in scfm are
given in Table B-2 as waste gas 2.
The reactor vent scrubber was not designed to control pollution but to recover
product and raw material for economic reasons. The top temperature is 55°F in
the winter and 70°F in the summer. No acetic .acid is detectable in the emissions
from the reactor vent scrubber except during an upset. The composition of
waste gas 1 was determined by gas chromatography and is on a dry basis although
the stream is actually saturated.
The unit vent scrubber is an emission control device, with the top temperature
80°F in the winter and 95°F in the summer. No data are available on the composi-
tion, flow, etc., of the vent stream into the unit vent scrubber.
-------
Table B-l. Estimates of Controlled VOC Emissions from
the Union Carbide Butane Oxidation with Oxygen Process
Uncontrolled
VOC Emission
Source Ratio (g/kg)
Separator condenser vents 25
Stripper condenser vents 12-. 8
Purification section vents 0.2
Total 38
VOC Emission
Reduction
Control Device (%)
Refrigerated vent 68
condensers
Flare 95
Refrigerated vent 60
condensers
Controlled
VOC Emission^
Ratio (g/kg)
8
0.
0.
8.
6
08
68
See refs 3 and 4.
g of emissions per kg of total product mix produced.
Cd
-------
B-5
Table B-2. Celanese Acetic Acid Source Emissions'
Waste Gas 1
Production Rate A
Component
N2
V
°2
CO,,
2
C2H4°
CO + CE.
4
(wt %)
95.9
0.6
2.8
0.3
0.4
100.0
(lb/1000 lb)
1075.7
6.0
31.3
3.7
4.6
1121.3
b
(Wt %)
97.3
2.7
Trace
100.0
(lb/1000 lb) (wt %)
1022.2
28.8
0.3
1051.3
96.3
3.2
0.5
See ref 5.
Vent rate, ^50 scfm.
-------
B-6
5. Tennessee Eastman, Kingsport, TN
The acetaldehyde oxidation acetic acid process uses a scrubber that employs
acetic acid and water to remove VOC from the reactor off-gases, with a reported
efficiency of 99%, before they are released to the atmosphere. Tennessee
Eastman considers the acetic acid and water scrubber as an integral part of the
process and not as an air pollution control device. The emissions from this
scrubber are as follows:
Flow: 200 Ib/hr
Composition: 97.4—89.4% N2*
2.5% C02
1500 ppm CO
1 ppm acetaldehyde
1 ppm ethyl alcohol
1 ppm ethyl acetate
18 ppm ethyl formate
0—8% 02*
Temperature: 40°F
*Based on engineering estimates; all other based on gas chromatography
analysis.
One column vent has a water-cooled vent condenser as the control device, with
an estimated reduction efficiency of 99% for removing n-propyl acetate.6
6. ARCO, Channelview, TX
The process for dehydrogenation of secondary butyl alcohol (SBA) to produce MEK
uses a smokeless flare as an emission control device.7
7. Shell, Deer Park, TX
MEK is produced by dehydrogenation of secondary butyl alcohol. The uncontrolled
emissions from the purification section are as follows:
Accumulator vent from the SBA Recovery Column that processes H2 scrub water;
vent gas routed to flare 5.
-------
B-7
Flow: 0.0012 Ib/lb of MEK production
Composition (wt %): SBA, 73
H20, 27
Temperature: 190°F
The flow was determined by vane anemometers and the composition by design
calculations.
Accumulator vent gas from the MEK dehydration column is routed to flare 6;
flow occurs during hot weather or for about 4 months/yr.
Flow: 0.0035 Ib/lb of-MEK production
Composition (wt %):a C2~-C6~ 55.2
C1°-C6° 2.5
IPE 15.1
DMK 4.1
MEK 5.0
H2, N2, 02/ C02 18.1
Tempe rature: 130°F
Determined by analysis of vent and flow measurement.
Control devices used are smokeless flares 5 and 6. Each flare serves several
other process facilities in the Deer Park manufacturing complex. The flares
are sized to handle large flows under emergency conditions. Streams from the
above vents each constitute a very small percentage of the smokeless capacity
of each flare.8
8- Exxon, Bayway, NJ
Two process emission points in the MEK process are described below:
a. The distillation tower is operated under positive pressure, with SBA/
MEK-rich overhead vapors passing through two stage condensers and recycled
to the process. The noncondensables that collect in the overhead condensers
are periodically purged to two parallel blowdown drums that are integrated
with other processes. The vapors are contacted with cooling water in the
-------
B-8
blowdown drums. Noncondensable vapors from these drums are vented. The
average calculated atmospheric emissions are about 1 lb/ hr of C4 hydrocarbons
at ambient temperature..
b. The dehydration tower is also operated under positive pressure. The
overhead vapors pass through three stage condensers, with condensed vapors
recycled to the process. The noncondensables that collect in the overhead
condensers are periodically vented to the atmosphere. The average calculated
atmospheric emission is about 5 Ib/hr of MEK at 100°F. The emission
control device on vent 1 is a type of water scrubber, consisting of two
parallel, vertical blowdown drums with internal horizontal baffles and
countercurrent water flow, to condense some VOC from the column condenser
vents and from other sources.9
9. Tennessee Eastman, Kingsport, TN
Ethyl acetate is produced from acetic acid and ethyl alcohol. The emissions
from the columns and the extractor are as follows:
Stream A
Flow: 4.5 Ib/hr
Composition (wt %):3 86.4 nitrogen
11.1 ethyl acetate
0.4 carbon monoxide
0.3 ethyl alcohol
0.02 methane
0.01 acetaldehyde, acetic acid,
and methyl acetate
Temperature: Ambient
Stream B
Flow: Not detectable
Composition: No data available
Temperature: Ambient
Based on gas chromatography analysis.
No control devices are used.10
-------
B-9
RETROFITTING CONTROLS
The primary difficulty associated with retrofitting may be in finding space to
fit the control device into the existing plant layout. Because of the costs
associated with this difficulty it may be appreciably more expensive to retro-
fit emission control systems in existing plants than to install a control
system during construction of a new plant.
Another difficulty may be the possibility of overpressuring existing equipment
because of pressure drop through an emission control device such as a flare,
carbon adsorption, or scrubber. When water scrubbing is used, the scrubbing
water must be treated. If there is no treatment plant or if it is too small,
the cost of treatment of a large amount of scrubbing water from a water scrubber
retrofitted to an existing process can be very expensive.13
-------
B-10
C. REFERENCES
1. J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Monsanto Co.,
Texas City, TX, Dec. 13, 1977 (on file at EPA, ESED, Research Triangle Park, NC)
2. J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Borden Chemical Co.,
Geismar, LA, Mar. 3, 1978 (on file at EPA, ESED, Research Triangle Park, NC).
3. J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Union Carbide Corp.,
South Charleston, WV, Dec. 7, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
4. F. D. Bess, Union Carbide Corporation, letter dated Aug. 25, 1978 to J. A. Key,
IT Enviroscience, Inc., with information on emissions from butane oxidation
system at Brownsville, TX (on file at EPA, ESED, Research Triangle Park, NC).
5. J. A. Key, IT Enviroscience, Inc., Trip Report for Visit to Celanese, Clear
Lake, TX, Oct. 12, 1977 (on file at EPA, ESED, Research Triangle Park, NC).
6. J. C. Edwards, Tennessee Eastmen Co., letter to EPA with information on MEK
unit in ARCO's Lyondell Plant at Channelview, TX, May 15, 1978.
7. C. N. Hudson, ARCO Chemical Co., letter to EPA with information on MEK unit
in ARCO's Lyondell Plant at Channelview, TX, May 15, 1978.
8. J. A. Mullins, Shell Oil Co., letter to EPA with information on MEK plant at
Deer Park, TX, June 22, 1978.
9. G. L. Otis, Exxon Chemical Co., letter dated June 7, 1978, to EPA with informa-
tion on MEK unit in Exxon's Bayway, NJ, Chemical Plant.
10. J. C. Edwards, Tennessee Eastman Co., letter to EPA with information on
Kingsport, TN, ethyl acetate plant, Aug. 11, 1978.
11. N. B. Galluzzo, Monsanto Plastics & Resins Co., letter dated Oct. 22, 1979, to
D. R. Patrick, EPA, with comments on draft Acetic Acid Report (on file at
EPA, ESED, Research Triangle Park, NC).
12. R. H. Maurer, Celanese Chemical Company, Inc., letter dated Oct. 10, 1979, to
D. R. Patrick, EPA, with comments on draft Acetic Acid Report (on file at
EPA, ESED, Research Triangle Park, NC).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of
that paragraph, that reference number is indicated on the material involved.
When the reference appears on a heading, it refers to all the text covered by
that heading.
-------
10-i
REPORT 10
WASTE SULFURIC ACID TREATMENT FOR ACID RECOVERY
J. A. Key
IT Enviroscience
9041 Executive Park Drive
Knoxville, Tennessee 37923
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
February 1981
This report contains certain information which has been extracted from the
Chemical Economics Handbook, Stanford Research Institute. Wherever used, it
has been so noted.The proprietary data rights which reside with Stanford
Research Institute must be recognized with any use of this material.
D74A
-------
10-iii
CONTENTS FOR REPORT 10
I. ABBREVIATIONS AND CONVERSION FACTORS 1-1
II. INDUSTRY DESCRIPTION II-l
A. Introduction II-l
B. Sulfuric Acid Use in SOCMI II-l
C. References II-4
III- SULFURIC ACID RECOVERY TECHNIQUES III-l
A. Introduction III-l
B. Direct Evaporation III-l
C. Indirect Evaporation III-3
D. Regeneration III-4
E. Process Variations III-8
F. Recovery Trends III-8
G. References 111-10
IV. EMISSIONS IV-1
A. Current Emissions IV-1
B. Projected VOC Emissions IV-3
C. Sulfur Dioxide (S02) and H2S04 Mist Emissions IV-3
D. References IV-5
V. APPLICABLE CONTROL SYSTEMS V-l
A. Direct Evaporation V-l
B. Indirect Evaporation V-l
C. Regeneration V-2
D. Storage V-2
E. References V-3
VI. IMPACT ANALYSIS VI-1
APPENDICES OF REPORT 10
Page
A. Existing Plant Considerations A-l
-------
Number
II-l
IV-1
IV-2
10-v
TABLES OF REPORT 10
SOCMI Processes That Generate Spent Sulfuric Acid and the
Recovery Processes Used
Existing Sulfuric Acid Recovery Plant Information
Emissions from Sulfuric Acid
Page
II-2
IV-2
IV-4
Number
III-l
III-2
FIGURES OF REPORT 10
Flow Diagram for Direct-Evaporation Sulfuric Acid Recovery
Process
Flow Diagram for Indirect-Evaporation Sulfuric Acid Recovery
Process
III-3 Flow Diagram for Sulfuric Acid Recovery by Regeneration
Page
III-2
III-5
III-7
-------
1-1
ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements used in agency documents in metric
units. Listed below are the International System of Units (SI) abbreviations
and conversion factors for this report.
To Convert From
Pascal (Pa)
Joule (J)
Degree Celsius (°C)
Meter (m)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter (m3)
Cubic meter/second
(m3/s)
Watt (W)
Meter (m)
Pascal (Pa)
Kilogram (kg)
Joule (J)
To
Atmosphere (760 nun Hg)
British thermal unit (Btu)
Degree Fahrenheit (°F)
Feet (ft)
Cubic feet (ft3)
Barrel (oil) (bbl)
Gallon (U.S. liquid) (gal)
Gallon (U.S. liquid)/min
(gpm)
Horsepower (electric) (hp)
Inch (in.)
Pound-force/inch2 (psi)
Pound-mass (Ib)
Watt-hour (Wh)
Standard Conditions
68°F = 20°C
1 atmosphere = 101,325 Pascals
PREFIXES
Multiply By
9.870 X 10~6
9.480 X 10"4
(°C X 9/5) + 32
3.28
3.531 X 101
6.290
2.643 X 102
1.585 X 104
1.340 X 10"3
3.937 X 101
1.450 X 10"4
2.205
2.778 X 10"4
Prefix
T
G
M
k
m
M
ol
tera
giga
mega
kilo
mill!
micro
Multiplication
Factor
1012
109
106
103
10'3
io"6
Example
1 Tg = 1 X IO12 grams
1 Gg = 1 X IO9 grams
1 Mg = 1 X IO6 grams
1 km = 1 X IO3 meters
I1 mV = 1 X IO"3 volt
1 pg = 1 X IO"6 gram
-------
II-l
II. INDUSTRY DESCRIPTION
A. INTRODUCTION
Although sulfuric acid is an inorganic chemical, it is used by the synthetic
organic chemicals manufacturing industry (SOCMI) in the production of synthetic
organic chemicals as an acidulating agent, a catalyst, or a dehydrating agent
or in some similar function. In many of these processes substantial quantities
of spent sulfuric acid and/or sulfate salts contaminated with volatile organic
compounds (VOC) are generated. The spent acids may be used in other opera-
tions, or they may be processed for recovery of sulfuric acid for sale, for use
in other operations, or for recycle to the SOCMI process that generated the
spent acid. The spent-acid recovery process may be part of a sulfuric acid
plant that is either off-site or at the same site where the spent acid is pro-
duced, or it may be a reconcentration process that is integrated with the spent-
acid producing process. This report covers in abbreviated form the recovery
of sulfuric acid from spent acids and sludges that contain VOC and that are
generated in producing synthetic organic chemicals.
B. SULFURIC ACID USE IN SOCMI
In 1978, 36 Tg (36 million metric tons) of sulfuric acid were produced in the
United States, 90% of this acid was used for the production of fertilizers nad
other inorganic chemicals. In these processes the acid either becomes part of
the product or remains as a nonrecoverable by-product. The remaining 10 to 12%
of the domestic sulfuric acid production not used in the inorganic chemical
industry is consumed by the petroluem, petrochemical, and organic chemical
industries.
The 1976 Organic Chemical Producers Data Base reports 1270 units producing
SOCMI chemicals in the United States.3 Of the 378 SOCMI chemicals sulfuric
acid can be used in as many as 57 chemicals at some stage in their manufac-
ture.4""6 Table II-l shows the SOCMI chemicals in which sulfuric acid can be
used. Since about 15% of the SOCMI chemicals use sulfuric acid, it is assumed
that 15% of the SOCMI production units (190 units) use sulfuric acid.
These 190 organic-chemical-producing units consume around 5% of the total
domestic production of sulfuric acid, or 1.9 Tg/yr (100% sulfuric acid basis).
2
-------
II-2
Table II-l. List of SOCHI Chemicals Produced by
Processes That Can Use Sulfuric Acid3
Chemical
Chemical
Acetone
Acetonitrile
Ac etophenone
Acrylamid
Acrylic acid and esters
Acrylonitrile
Anthraquinone
Benzene disulfonic acid
Benzene sulfonic acid
n-Butyl acetate
n-Butyl aerylate
sec-Butyl alcohol
t-Butyl alcohol
jt-Butyl amine
Cellulose acetate
p_-chloro nitrobenzene
p-Chloro nitrobenzene
m-Cresol
b-Cresol
£-Cresol
Diethyl sulfate
ri,la-Dimethyl aniline
Dimethyl sulfate
Dinitrobenzoic acid
Dinitrotoluene
Dioxane
Ethyl acetate
Ethyl acrylate
Ethylene glycol
See refs 4—6.
Hydrogen cyanide
Isobutyl acetate
Isobutylene (di and tri)
Isopropyl acetate
Methacrylic acid
Methyl acetate
Methyl acetoacetate
Methyl chloride
Methyl methacrylate
Morpholne
1-Naphthalene sulfonic acid
2-Naphthalene sulfonic acid
1-Naphthol
2-Naphthol
Neopentansic acid
N itrobenzene
m-Nitrobenzoic acid
Nitrotoluene
Octyl phenol
Phenol
Phenol sulfonic acid
Phthalic anhydride
Propylene chlorohydrin
Sulfanilic acid
Tetra chlorophthalic anhydride
Toluene sulfonic acid
£-Toluene sulfonic chloride
Xylenols
-------
II-3
It is reported that production of alcohols (predominantly isopropyl and se£-
butyl alcohols) used 964 Gg, or about 2.7%, of the 1978 consumption of 36 Tg of
sulfuric acid (100% basis). This means that about 940 Gg of sulfuric acid
(100% basis) was consumed by other SOCMI processes. Of the 964 Gg of sulfuric
acid used in the production of alcohols, 818 Gg was reconcentrated and used on-
site, leaving 146 Gg of waste acid that was used in other processes off-site,
that formed a sludge that was reprocessed by sulfuric acid manufacturers, or
that was lost. As a result, an equivalent amount of virgin acid was actually
consumed. Therefore 5.6 times the amount of virgin acid consumed was recon-
centrated and recycled on-site. If this ratio holds for other SOCMI products,
then a total of about 6.1 Tg of sulfuric acid (100% basis) was reconcentrated.
-------
II-4
C. REFERENCES*
1. R. E. Davenport et al. , "Sulfuric Acid," pp. 780.1000A—G and 780.1001A—
780.1004C in Chemical Economics Handbook, Stanford Research Institute, Menlo
Park, CA (August 1979).
2- U.S. Department of Interior, Bureau of Mines, End Uses of Sulfur and Sulfuric
Acid in 1978.
3. Organic Chemical Producers Data Base Program, Volume II, Final Report, Radian
Corporation, Austin, Texas, August 1971.
4. R. N. Shreve and J. A. Brink, Jr., Chemical Process Industries, 4th ed.,
McGraw-Hill, New York, 1977.
5. F. A. Lowenheim and M. K. Moran, Faith, Keys, and Clark's Industrial Chemicals,
4th ed., Wiley, New York, 1975.
6. Morrison and Boyd, Organic Chemicstry, Allyn and Bacon, Inc., 1975.
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on a heading, it refers to all the text covered by that
heading.
-------
III-l
III. SULFURIC ACID RECOVERY TECHNIQUES
A. INTRODUCTION
Three principal methods of recovering sulfuric acid are not in general use:
(1) spent acid regeneration, (2) indirect evaporation, and (3) direct evapora-
tion. The spent-acid regeneration process invovles the decomposition of the
acid at temperatures of 1000 to 1150°C to produce sulfur dioxide, oxygen, and
water vapor. The sulfur dioxide is oxidized to sulfur trioxode, which is ab-
sorbed to produce highly concentrated sulfuric acid or oleum. The two other
processes, direct and indirect evaporation, are used to concentrate dilute sul-
furic acid. The indirect-evaporation process uses steam or other heating media
in indirect heaters to vaporize water and organics from the acid. The direct-
evaporation process uses hot flue gases directly in contact with the spent acid
to remove water and VOC.
This section describes the three processes used for spent sulfuric acid treat-
ment, along with some advantages and disadvantages of each process.
B. DIRECT EVAPORATION
1. Drum Concentrator
The recovery of sulfuric acid by direct evaporation involves contacting hot
gases, usually from combustion of fuel, with the spent acid to evaporate water
and impurities. Figure III-l is a flow diagram for a process developed in the
1920s by Chemico, now a division of Barnard and Burk, Inc., to recover sulfuric
acid from oil refinery spent acids and later used to recover sulfuric acid from
spent acid from high-explosive manufacture and from organic intermediates
nitration processes. The evaporation is performed in a drum concentrator a
horizontal cylindrical steel vessel lined with heavy sheet lead and acid-proof
brick and divided by brickwork into two compartments. The hot gases flow
countercurrent to the acid flow through the drum concentrator and a cooling
,1,2
drum.
The spent acid (stream 1) from spent-acid storage enters the cooling drum,
where gas (stream 2) at about 170 to 180°C enters through a dip pipe below the
surface of the acid and is cooled as it preheats the acid. The hot preheated
-------
M
I
Fig. III-l. Flow Diagram for Direct-Evaporation Sulfuric Acid Recovery Process
-------
III-3
acid (stream 3) flows by gravity to the intermediate-stage compartment of the
concentrator drum; the exaust gas (stream 4), which contains water vapor, acid
mist, and VOC, is treated in the venturi scrubber and separator to remove sul-
furic acid mist and is then released to the atmosphere (vent A). Water
(stream 5) is added to the venturi scrubber and separator to maintain the
proper concentration of scrubbing acid. The excess scrubbing acid (stream 6)
is bled back to the cooling drum for recovery of the acid removed previously.
In the intermediate stage of the concentrator drum, hot gas (stream 7) from the
high stage of the concentrator drum and some of the hot gas (stream 8) from the
burner are introduced below the surface of the acid and by direct contact heat
the acid and evaporate water and VOC from it. The acid (stream 9) flows by
gravity to the high-stage compartment of the concentrator drum, and the hot gas
(stream 2) containing the evaporated water vapor and VOC goes to the cooling
drum. Similarly, part of the hot gas (stream 10) from the burner is introduced
below the acid surface in the high-stage compartment to evaporate additional
water so as to produce a concentrated (93 to 94%) acid (stream 11). The acid
product flows by gravity to the acid cooler and product acid storage, while the
hot gases (stream 7) containing water vapor and VOC go to the intermediate
stage. Because the acid in the intermediate stage is less concentrated, more
water can be evaporated into the hot gases (stream 7) that leave the high stage
1 2
and that are saturated at the acid concentration existing there. '
Storage VOC emission sources (vents B) are the spent-acid storage and the prod-
uct-acid storage. Since it is expected that most of the VOC will be removed in
the concentrator, the product acid should contain little or no VOC and there-
fore the product-acid storage should emit little or no VOC emissions.
C. INDIRECT EVAPORATION
When spent acid is recovered by indirect evaporation, the heating medium, which
may be steam or hot gases or some other conventional heat transfer medium, is
separated from the spent acid by a heat exchange surface, as in a shell and
tube heat exchanger, jacketed kettle, etc. The evaporation may be carried out
under vacuum or at atmospheric pressure and may be a batch operation or a con-
tinuous operation using multiple units, depending on the spent-acid concentra-
tion, the desired concentration of the recovered acid, and the amount of spent
1--4
acid to be processed.
-------
III-4
2
Figure III-2 is a flow diagram representig the Simonson-Mantius vacuum process
for recovering sulfuric acid from spent acid. Spent acid (stream 1) from
spent-acid storage is pumped to the concentrator, where it is heated by steam
to evaporate the water and the VOC. The water vapor and VOC gases containing
traces of acid and inert gases (stream 2) go to a water-cooled condenser, where
water and most of the VOC are condensed and the liquid (stream 3) flows to the
condensate tank while the inert gases and noncondensed VOC (stream 4) are
pulled through the vacuum-jet system. Condensed steam, VOC, and inert gases
(stream 5) flow together as liquid and gas to the condensate tank, where the
inert gases and noncondensed VOC are emitted (vent A). The recovered acid
1 2
(stream 6) is cooled by the acid cooler and goes to product-acid storage. '
Storage VOC emission sources (vents B) are the spent-acid storage and product-
acid storage. It is expected that most of the VOC will be removed in the con-
centrator; therefore the product acid will contain little or no VOC and the
product- acid storage should emit little or no VOC emissions. Secondary emis-
sions (C) can occur when wastewater containing VOC is sent to disposal.
D. REGENERATION
Recovery of sulfuric acid by regeneration involves thermal decomposition of the
spent acid at high temperatures to sulfur dioxide, followed by processing of
the sulfur dioxide gases, as in the contact process, to concentrated sulfuric
acid or oleum. The reaction for the decomposition is
H2S04 > S02 + 1/202 + H20
(sulfuric acid) (sulfur dioxide) (oxygen) (water)
The reaction is endothermic and is carried out at a temperature of 1000 to
1150°C, with the heat supplied by burning fuel. Excess air is supplied to
ensure complete combustion of the fuel and any VOC.
After the water vapor is removed, the sulfur dioxide is converted to sulfur
trioxide by catalytic oxidation:
-------
SpEUT
ACID
r
COUOE.USER,
WATER
STSAM
TO
H
I
l/i
Fig. III-2. Flow Diagram for Indirect-Evaporation Sulfuric Acid Recovery Process
-------
III-6
S02 + 1/202 > S03
(sulfur dioxide) (oxygen) (sulfur trioxide)
The converter inlet temperature is about 440°C and the catalyst is vanadium
*. -j 5"8
pentoxide.
The sulfur trioxide is then reacted with water to form sulfuric acid:
S03 + H20 > H2S04
(sulfur trioxide) (water) (sulfuric acid)
The reaction occurs when the sulfur trioxide is absorbed in strong sulfuric
acid, where it combines with contained water. Both the catalytic oxidation of
sulfur dioxide and the combining of sulfur trioxide and water are exothermic;
the heat is removed by heat transfer to incoming streams for energy recovery or
to the waste-heat boiler for steam generation or is removed by cooling
6--8
water.
Figure III-3 is a flow diagram for sulfuric acid recovery by regeneration of
spent acid. The spent acid (stream 1) is pumped from spent-acid storage to the
spent-acid furnace, where it is decomposed by the heat from the hot gases
produced by burning fuel. Any VOC in the spent acid are also burned in the
spent-acid furnace to water vapor and carbon dioxide. The hot gases
(stream 2), which contain sulfur dioxide, go to the waste-heat boiler, where
they are cooled by making steam. The cooled gases (stream 3) are sent to the
gas cleaning system for scrubbing and for further cooling to remove water and
are then sent to electrostatic precipitators for mist elimination. The cleaned
gases containing sulfur dioxide (stream 4) go to the contact-type sulfuric acid
plant, where they are dried, the sulfur dioxide is converted to sulfur tri-
oxide, the sulfur trioxide is absorbed in strong sulfuric acid, and the remain-
ing inert gases are vented (A). The sulfuric acid (stream 5) produced is sent
6 7
to product-acid storage. '
The sulfuric acid plant stack (vent B) is a source of process emissions; how-
ever, no VOC are emitted because at the temperature and residence time in the
6 7
spent-acid furnace all of them are destroyed. ' Storage emission sources
-------
AIR
ACID
FUEL-
SREMT
ACID
STEAM
MEAT
BOILER
CUEAWlWQ
1
AGIO
p-AMj
PRODUCT
ACID
H
H
I
Fig. III-3. Flow Diagram for Sulfuric Acid Recovery by Regeneration
-------
III-8
(vent B) are the spent-acid storage and product-acid storage. Again, no VOC
are emitted from product-acid storage because none are detected in the product
acid.
E. PROCESS VARIATIONS
The only variation in spent acid recovery is a combination of direct evapora-
tion and regeneration. At the Rohm and Haas methyl methacrylate plant in Deer
Park, Texas, a direct-evaporation technique is used to preconcentrate the spent
acid before regeneration. In this process, hot gas contacts a waste acid
stream to preconcentrate the acid for use as a feed to a regeneration plant.
The preconcentration reduces the amount of water in the waste acid so that the
acid stream can be decomposed in a regeneration plant to produce a gas with an
9
acceptable S02 content for use in a contact sulfuric acid plant.
The Rohm and Haas recovery technique is not currently used in any other spent-
acid processing facility. Similar processes are not predicted for new plants
for several reasons. First, Prevention of Significant Deterioration (PSD)
regulations would prohibit new large VOC emissions without controls. The Rohm
and Haas unit emits annually 500 Mg of VOC with a spent-acid capacity of around
72 Gg/yr. Control costs to conform to existing PSD regulations would be high
due to volume and composition of the stack gas. Also, methyl methacrylate in
the future is expected to be produced by a different process, one that does not
require the use of sulfuric acid. Few companies are interested in entering the
9
methyl methacrylate market.
Since only one plant now exists and since it seems unlikely that new plants
will be built for using this process, the Rohm and Haas plant is not included
in the emission analysis.
F. RECOVERY TRENDS
As noted in Sect. II, an estimated 6.1 Tg/yr of sulfuric acid is processed for
recovery by regeneration, direct evaporation, or indirect evaporation. Of the
processes surveyed regeneration is used in about 30%, indirect evaporation in
40%, and direct evaporation in 27%. The percentage breakdown in terms of pro-
duction volume is not available. Due to data limitations this division is only
a rough estimate, and industry trends indicate that new plants may not have the
same breakdown.
-------
III-9
When a new plant that uses sulfuric acid is to be built, the following factors
are of concern: regulatory environment, cost of control, and quality of acid
required in the process. As chemical plants become part of large chemical
complexes with several types of units producing spent acid, regeneration
becomes more attractive. Since regeneration produces a virgin-quality acid,
the acid can be used in any process that requries sulfuric acid; the use is not
limited to those processes for which an impure (93%) sulfuric acid is accept-
able. Direct evaporation, however, is becoming less attractive because of the
regulatory environment and the cost of VOC emissions control. VOC emissions
from direct-evaporation processes are several orders of magnitude higher than
those from indirect evaporation. These high-flow, low-concentration emission
streams are costly to control.
The trend away from direct evaporation and toward regeneration as a spent-acid
recovery technique can, however, be assessed only qualitatively. This quali-
tative assessment of trends indicates that the worst case for emission analysis
is the current industry breakdown of process utilization.
-------
111-10
G REFERENCES*
1. Sulfuric Acid Concentration and Recovery, sales brochure published by Barnard
and Burk, Inc., Chemico Processes Division, Mountainside, NJ.
2. G. M. Smith and E. Mantius, "The Concentration of Sulfuric Acid," Chemical
Engineering Progress 74(9), 78—83 (1978).
3. L. P. Hughes, Mobay Chemical Corporation, letter dated Apr. 10, 1979, contain-
ing information on air emission from sulfuric acid recovery at Baytown, TX, in
response to EPA request.
4. J. P. Walsh, Exxon Chemical Company, U.S.A., letter dated Apr. 27, 1979, con-
taining information on air emissions from sulfuric acid recovery at Baton
Rouge, LA, in response to EPA request.
5. U. Sander, "Waste Heat Recovery in Sulfuric Acid Plants," Chemical Engineering
Progress 73(3), 61—64 (1977).
6. U. Sander and G. Daradimos, "Regenerating Spent Acid," Chemical Engineering
Progress 74(9), 57—67 (1978).
7. J. A. Key, IT Enviroscience, Trip Report for Visit to Dupont, Burnside, LA,
Apr. 24, 1979 (on file at EPA, ESED, Research Triangle Park, NC).
8. R. E. Davenport et al., "Sulfuric Acid," pp. 780.1000 A—G and 780.1001A—
780.1004C in Chemical Economics Handbook, Stanford Research Institute, Menlo
Park, CA (August 1979).
9. M. W. Karkanawi, EEA, Inc., Trip Report for Visit to Rohm and Haas, Texas, Inc.,
Deer Park, Texas, April 1980.
^Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on aheading, it refers to all the text covered by that
heading.
-------
IV-1
IV. EMISSIONS
The VOC emission estimates presented in this section are based on the emission
1--17
data in Table IV-1. The emission analysis is based on emission factors
and sulfuric acid processing capacity derived from industry data. Emission
projections are based on predicted worst-case trends in process utilization.
CURRENT EMISSIONS
For the plants surveyed the data on the capacity of sulfuric acid processing
plants vary widely. There is little correlation between capacity and the type
of recovery process used. For the purpose of emission analysis an estimated
total national capacity of 6.1 Tg/yr is used, representing 190 production
units.
Current VOC emission rates for the processes surveyed are shown in Table IV-1,
and calculated emission factors from recovery processes are as follows:
Indirect evaporation: 30 Mg of VOC per Tg of H2S04 (100%)
Direct evaporation: 1800 Mg of VOC per Tg of H2S04 (100%)
Regeneration: negligible
The emissions rate for indirect-evaporation processes was derived from the
Cyanamid nitrobenzene plant, and the emissions rate for direct-evaporation pro-
cesses was derived from the Allied dinitrotoluene facility (see Table IV-1).
These plants were chosen for emission rate assumptions because a more complete
data set is available for them.
As noted in Sect. II, an estimated 6.1 Tg of sulfuric acid is processed annual-
ly for recovery; 30% was by regeneration, 40% by indirect evaporation, and 30%
by direct evaporation. Based on this industry capacity and breakdown the total
nationwide VOC emission annually would be around 3.3 Gg, most of which is
emitted from direct-evaporation processes. The current emissions from sulfuric
acid processing then would be less than 1% of the total SOCHI VOC emissions of
680 Tg/yr. Because the estimate of sulfuric acid capacity is probably high,
the current total emission estimate is also probably high.
-------
Table IV-1, Existing Sulfuric Acid Recovery Plant Information
Company and Location
Doha and Haas
Deer park, TX
Allied1*
Moundavllle, WV
Rubicon
Celsnar, LA
Dupont
Beauaant, TK
Gibbstown, Nje
f
Exxon
Baton Rouge, LA
ARCO9
Chumelview, TX
Shell11
Deer Park, TK
Hobay
New Marti n«vi lie, WV
Baytown , TX
Cy*nanidk
Bound Brook, NJ
Dupont
Memphis, TN1
Burnside, LA*
stauffer11
Bay town, TX
Allied0
Klchaond* Ch
f
Beaunontf TX
Synthetic Organic Chemicals
Produced
Methylnethacryl&te and acrylic
esters
T>initrotoluene
(New plant) nitrobenzene
Nitrobenzene
Nitrobenzene
Isopropyl alcohol
sec-Butyl alcohol
sec-Butyl alcohol and
isopropyl alcohol
Mitroben z ene
Di nitroto luene
nitrobenzene
Methylraethacrylate
None (spent acid frxm off-site}
Nona (spent acid frcsi off-site)
Her*
-------
IV-3
B- PROJECTED VOC EMISSIONS
It is projected that 150 new SOCMI plants will be built during the next five
18
years. Since 15% o'f the SOCMI plants are assumed to use sulfuric acid and
process it for recovery, then 22 new plants will be sources of VOC emissions
from sulfuric acid recovery in the fifth year. Also, since the current trend
is toward the regeneration process and away from the direct-evaporation
process, the worst case that can be reasonably projected for new sources is
industry-wide additional VOC emissions of 2.5 Gg/yr. This is based on the
current estimated process breakdown of 30% by regeneration, 40% by indirect
evaporation, and 30% by direct evaporation and on 4.7 Tg/yr of additional sul-
furic acid processing capacity in the fifth year. This is a worst-case esti-
mate, and VOC emissions will probably be less.
C. SULFUR DIOXIDE (S02) AND H2S04 MIST EMISSIONS
The standards of performance for new contact-process sulfuric acid facilities
for S02 and acid mist apply to the regeneration process used for spent-acid
recovery. They do not apply to the direct- and indirect-evaporation methods of
acid concentration. The emission limitations required that no more than 2.0 kg
of S02 per metric ton of acid (100% H2S04) be emitted and that no more than
19
0.75 kg of acid mist per metric ton of acid (100% H2S04) produced be emitted.
Table IV-2 summarizes the S02 emissions and H2S04 mist emissions from the three
types of recovery methods. Some S02 will often be formed in the evaporation
processes by the reduction of H2S04 by organic components in the stream. The
S02 emissions are small; no S02 is usually detected from indirect processes and
only small amounts from direct processes.
-------
IV-4
Table IV-2. Emissions from Sulfuric Acid
Recovery
Process
Regneration
c
Direct Evaporation
Indirect evaporation
VOC
Negligible
1.8
0.033
Emission Ratio
Sulfur Dioxide
b
2.0
0.2
None detected
(g/kg)a
Sulfuric Acid Mist
b
0.075
0.3
None detected
g of emission per kg of sulfuric acid (100% basis) produced.
Based on NSRS emission limits for sulfuric acid plants.
CSee ref 2.
d
See ref 12.
-------
IV-5
D. REFERENCES*
1. M. W. Karkanawai, EEA, Inc.,. Trip Report for Visit to Rohm and Haas Texas, Inc.,
Deer Park, TX April 1980.
2. J. S. Bresland, Allied Chemical, letter dated Apr. 27, 1979, containing infor-
mation on air emissions from sulfuric acid concentrator at Moundsville, WV, in
response to EPA request.
3. C. W. Stuewe, IT Enviroscience, Trip Report for Visit to Rubicon Chemicals,
Inc., Geismar, LA, July 19,20, 1977 (on file at EPA, ESED, Research Triangle
Park, NC).
4. "Chementator," Chemical Engineering 86(14), 27 (1979).
5. C. W. Stuewe, IT Enviroscience, Trip Report for Visit to E. I. Du Pont de
Nemours & Company, Inc., Beaumont, TX, Sept. 7,8, 1977 (on file at EPA, ESED,
Research Triangle Park, NC).
6. R. C. Ott, Dupont, letter dated May 26, 1978, containing information on air
emissions from nitrobenzene process at Gibbstown, NJ, in response to EPA
request.
7. J. P- Walsh, Exxon Chemical Co., U.S.A., letter dated Apr. 27, 1979, containing
information on air emissions from sulfuric acid concentrators at Baton Rouge,
LA, in response to EPA request.
8. C. N. Hudson, Arco Chemical Co., letter dated Apr. 30, 1979, containing infor-
mation on air emissions from sulfuric acid concentrators at Channelview, TX, in
response to EPA request.
9. J. A. Mullins, Shell Oil Co., letter dated May 4, 1979, containing information
on air emissions from sulfuric acid concentrator at Deer Park, TX, in response
to EPA request.
10. C. W. Stuewe, IT Enviroscience, personal communication May 22, 1978, with D. A.
Beck, EPA, ESED, Re.search Triangle Park, NC.
ll. L. P. Hughes, Mobay Chemical Corp., letter dated Apr. 10, 1979, containing
information on air emissions from sulfuric acid concentrator at Baytown, TX, in
response to EPA request.
^2. C. Priesing, Cyanamid Co., letter dated Apr. 1, 1980, to J. R. Farmer, EPA.
13. J. W. Blackburn, IT Enviroscience, Trip Report for Visit to E. I. du Pont de
Nemours & Company, Inc., Memphis, TN, Jan. 10, 1978 (on file at EPA, ESED,
Research Triangle Park, NC).
^4. J. A. Key, IT Enviroscience, Trip Report for Visit to E. I. du Pont de Nemours &
Company, Inc., Burnside, LA, Apr. 24, 1979 (on file at EPA, ESED, Research
Triangle Park, NC).
-------
IV-6
15. J. W. Call, Stauffer Chemical Co., letter dated Aug. 6, 1979, containing infor-
mation on air emissions from spent-acid recovery process at Baytown, TX, in
response to EPA request.
16. W. M. Reiter, Allied Chemical, letter dated May 8, 1979, containing information
on air emissions from spent-acid recovery process at Richmond, CA, in response
to EPA request.
17. H. T. Emerson, Olin Corp., letter dated May 14, 1979, containing information on
air emissions from spent-acid recovery process at Beaumont, TX, in response to
EPA request.
18. E. Hurley, EEA, Inc., personal communication with B. Newman, EEA, Inc., August
1980.
19. Background Information for Proposed New Source Performance Standards for Sul-
furic Acid Plants, EPA, APTD-0711 (August 1971).
*Usually, when a reference is located at the end of a paragraph, it refers to
the entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on a heading, it refers to all the text covered by that
heading.
-------
V-l
V. APPLICABLE CONTROL SYSTEMS
A- DIRECT EVAPORATION
The venturi scrubber and separator shown on Fig. III-l for the direct-evapora-
tion sulfuric acid recovery process is an emission control device primarily
intended to remove acid mist from the vent gases (A, Fig. III-l) before they
are released to the atmosphere. Some VOC may be removed by these devices if
they are soluble in the scrubbing medium or if they are in particulate form.
No measured removal-efficiency data were reported, although one respondent
estimated that the venturi scrubber would remove 60% of the nitroaromatics from
2
the vent gases. However, it is believed that the VOC removal efficiency of
most of the reported control devices is very low. No add-on control device has
been identified that will significantly reduce the reported VOC emissions from
the direct-evaporation plants shown in Table IV-1.
One technique for emission control that was reported is the replacement of a
plant that used direct-evaporation sulfuric acid recovery with a new plant, one
which uses indirect evaporation. Two companies have started up new nitroben-
zene plants that employ new technology, including an indirect-evaporation sul-
furic acid recovery process. Data are not available on VOC emissions from the
new plants, but it is believed that there will be a net reduction if the old
direct-evaporation plants are shut down.
A possible control technique that has not been reported or investigated is
source control, which results in reduction of the more soluble VOC in the spent
acid going to the direct-evaporation process. If the VOC can be removed com-
pletely from the spent acid, then, of course, there should be no VOC emissions
from a direct-evaporation sulfuric acid recovery process.
p. INDIRECT EVAPORATION
The VOC emissons from the condensate tank (vent A, Fig. II1-2) in an indirect-
evaporation sulfuric acid recovery process may be controlled by thermal oxida-
tion, by return to the process where the spent acid was produced, or by conden-
sation in a vent condenser (see Table IV-1). A thermal oxidizer with adequate
residence time and temperature will destroy 98% or greater of the VOC emis-
sions. Separate EPA reports cover the evaluation of emission control devices
-------
V-2
and the conditions affecting their efficiency. The return of emissions to the
4
process reportedly results in 100% reduction of ei
efficiency of the vent condenser was not reported.
4
process reportedly results in 100% reduction of emissions but the reduction
C. REGENERATION
As no VOC are emitted with the vent gases (A, Fig. III-3) from a sulfuric acid
recovery by regeneration process, no control devices are needed.
D. STORAGE
VOC emissions from the spent-acid storage (B, Fig. III-3) may be controlled by
thermal oxidation. The vent on the spent-acid storage tank is connected to the
sulfur burner air intake at one sulfuric acid plant so that a portion of the
air required by the burner comes from the vapor space of the spent-acid tank.
Another plant controls the VOC emissions from the spent-acid storage by feeding
>n eJ
5,6
them to the spent-acid furnace. No data are available on the reduction effi-
ciency at these plants; however, no VOC are reported in the vent gases.
-------
V-3
E. REFERENCES*
1. G. M. Smith and E. Mantius, "The Concentration of Sulfuric Acid," Chemical
Engineering Progress 74(9), 78—83 (1978).
2. J. S. Bresland, Allied Chemical, letter dated Apr. 27, 1979, containing infor-
mation on air emissions from sulfuric acid concentrator at Moundsville, WV, in
response to EPA request.
3. "Chementator," Chemical Engineering 86(14), 27 (1979).
4. J. P. Walsh, Exxon Chemical Co., U.S.A., letter dated Apr. 27, 1979, containing
information on air emissions from sulfuric acid concentrators at Baton Rouge,
LA, in response to EPA request.
5. J. A. Key, IT Enviroscience, Trip Report for Visit to E. I. du Pont de
Nemours & Company, Inc., Burnside, LA, Apr. 24, 1979 (on file at EPA, ESED,
Research Triangle Park, NC).
6. J. W. Call, Stauffer Chemical Co., letter dated Aug. 6, 1979, containing
information on air emissions from spent-acid recovery process at Baytown, TX,
in response to EPA request.
*Usually, when a reference number is used at the end of a paragraph it refers to
the entire paragraph. If another reference relates to certain portions of that
paragraph, that reference number is indicated on the material involved. When
the reference appears on a heading, it refers to all the text covered by that
heading.
-------
VI-1
VI. IMPACT ANALYSIS
Environmental, energy, and control cost impacts have not been determined for the
control devices discussed in Sect. V.
-------
A-l
Appendix A
EXISTING PLANT CONSIDERATIONS
The controls discussed in Sect. V may not be applicable to existing plants. No
effective add-on control has been identified for the large volume of gases con-
taining VOC that are vented from a direct-evaporation sulfuric acid recovery
process. Retrofit of a thermal oxidizer to control the VOC from an existing
indirect-evaporation sulfuric acid recovery process can be very costly because
of space limitations, production lost during installation and startup, etc.,
and be appreciably greater than for a new installation. Replacement of an
existing direct-evaporation sulfuric acid recovery process with an indirect-
evaporation process may not be feasible for the same reasons. The existing
direct-evaporation processes are in older plants, which were built before VOC
emissions were of concern. For example, the Rohm and Haas plant processes
spent acid from several organic chemical production units where spent-acid
strippers are used to recover organic values before the spent acid goes to the
combined direct-evaporation and regeneration sulfuric acid recovery plant. The
feed rate to the direct- evaporation concentrators is controlled to limit
emissions of VOC to 250 Ib/hr per concentrator as required by the Texas Air
Control Board rules. The acid from the direct-evaporation concentrators is
then recovered in a regeneration process that produces 99% sulfuric acid. To
change from direct evaporation to indirect evaporation would require installa-
tion of new indirect-evaporation concentrators and probably demolition of the
existing concentrators, resulting in considerable lost production and expense.
Available data are not adequate for an estimate to be made of this cost.
-------
TECHNICAL REPORT DATA
^Please read Instructions on the reverse before completing)
EPA-450/3-80-028e
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Organic Chemical Manufacturing
Volume 10: Selected Processes
5. REPORT DATE
December 1980
6. PERFORMING ORGANIZATION CODE
7, AUTHORISI
C. A. Peterson, J. A. Key, F. D. Hobbs,
J. W. Blackburn, H. S. Basdekis, S. W. Dylewski,
R. L. Standifer, R. W. Helsel
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
IT Enviroscience, Inc.
9041 Executive Park Drive
Suite 226
Knoxville, Tennessee 37923
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-02-2577
12.
SPONSORINGAGENCY NAMEANID ADDRESS , „ .
DAA for Air Quality Planning and Standards
Office of Air, Noise, and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
13. T.XPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT
EPA is developing new source performance standards under Section 111 of
the Clean Air Act and national emission standards for hazardous air pollutants
under Section 112 for volatile organic compound emissions (VOC) from organic
chemical manufacturing facilities. In support of this effort, data were gathered
on chemical processing routes, VOC emissions, control techniques, control costs,
and environmental impacts resulting from control. These data have been analyzed
and assimilated into the ten volumes comprising this report.
This volume presents in-depth studies of several major organic chemical
products.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT i I ield/Group
13B
Ifc. D'STRIBUTiOM STATEMENT
Unlimited Distribution
19 SECURITY CLASS (THii Report!
Unclassified
21. NO. OF PAGES
578
20 SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS ED'TlON 'S OBSOLETE
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