EPA-450/3-73-006-b
FEBRUARY 1975
ENGINEERING
AND COST STUDY
OF AIR POLLUTION CONTROL
FOR THE
PETROCHEMICAL INDUSTRY
VOLUME 2: ACRYLONITRILE
MANUFACTURE
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Offi ce of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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EPA-450/3-73-006-b
ENGINEERING
AND COST STUDY
OF AIR POLLUTION CONTROL
FOR THE
PETROCHEMICAL INDUSTRY
VOLUME 2: ACRYLONITRILE
MANUFACTURE
by
W.A. Schwartz, F.B. Higgins, Jr. ,
J. A. Lee, R. Newirth, and J; W. Pervier
Houdry Division
Air Products and Chemicals, inc.
P.O. Box 427
Marcus Hook, Pennsylvania 19061
Contract No. 68-02-0255
EPA Project Officer: Leslie B . Evans
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, N. C. 27711
February 1975
-------
This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - as suppiles permit - from the Air
Pollution Technical Information Center, Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; or, for a fee, from the
National Technical Information Service, 5285 Port Royal Road, Springfield,
Virginia 22161.
This report was furnished to the Environmental Protection Agency by
the Houdry Division of Air Products and Chemicals , Inc . , in fulfillment
of Contract No. 68-02-0255. The contents of this report are reproduced
herein as received from the Houdry Division of Air Products and Chemicals,
Inc. The opinions, findings , and conclusions expressed are those of
the author and not necessarily those of the Environmental Protection
Agency. Mention of company or product names is not to be considered
as an endorsement by the Environmental Protection Agency.
Publication No. EPA-450/3-73~006-b
ii
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PETROCHEMICAL AIR POLLUTION STUDY
INTRODUCTION TO SERIES
This document is one of a series prepared for the Environmental Protection
Agency (EPA) to assist it in determining those petrochemical processes for
which standards should be promulgated. A total of nine petrochemicals produced
by 12 distinctly different processes has been selected for this type of
in-depth study. These processes are considered to be ones which might warrant
standards as a result of their impact on air quality. Ten volumes, entitled
Engineering and Cost Study of Air Pollution Control for the Petrochemical
Industry (EPA-450/3-73-006a through j) have been prepared.
A combination of expert knowledge and an industry survey was used to
select these processes. The industry survey has been published separately
in a series of four volumes entitled Survey Reports on Atmospheric Emissions
from the Petrochemical Industry (EPA-450/3-73-005a, b, c and d).
The ten volumes of this series report on carbon black, acrylonitrile,
ethylene dichloride, phthalic anhydride (two processes in a single volume),
formaldehyde (two processes in two volumes), ethylene oxide (two processes
in a single volume) high density polyethylene, polyvinyl chloride and vinyl
chloride monomer.
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ACKNOWLEDGEMENTS
The study reported in this volume, by its nature, relied on the fullest
cooperation of the companies engaged in the production of acrylonitrile. Had
their inputs been withheld, or valueless, the study would not have been
possible or at least not as extensive as here reported. Hence, Air Products
wishes to acknowledge this cooperation by listing the contributing companies.
American Cyanamid Co.
E. I. duPont deNemours & Co.
Monsanto Company
Vistron Corporation*
^Subsidiary of Standard Oil Company (Ohio), the process licensor.
Additionally, Air Products wishes to acknowledge the cooperation of the
member companies of the U. S. Petrochemical Industry and the Manufacturing
Chemists Association for their participation in the public review of an
early draft of this document. More specifically, the individuals who served
on the EPA's Industry Advisory Committee are to be commended for their
advice and guidance at these public meetings.
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TABLE OF CONTENTS
Section
Page Number
Summary
i
I.
Introduction
AN-1
II.
Process Description and Typical Material Balance
AN-2
III.
Manufacturing Plants and Emissions
AN-8
IV.
Emission Control Devices and Systems
AN-20
V.
National Emission Inventory
AN-29
VI.
Ground Level Air Quality Determination
AN-30
VII.
Cost Effectiveness of Controls
AN-31
VIII.
Source Testing
AN-3 7
IX.
Industry Growth Projection
AN-3 8
X.
Plant Inspection Procedures
AN-40
XI.
Financial Impact
AN-42
XII.
Cost to Industry
AN-46
XIII.
Emission Control Deficiencies
AN-48
XIV.
Research and Development Needs
AN-50
XV.
Research and Development Programs
AN-53
XVI.
Sampling, Monitoring and Analytical Methods for
AN-61
Pollutants in Air Emissions
XVII.
Emergency Action Plan for Air Pollution Episodes
AN-65
References AN-73
Appendix I 1-1
Appendix II II-l
Appendix III III-l
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LIST OF ILLUSTRATIONS
Figure No.
Title
PaRe Number
AN-1
AN-2
Simplified Flow Diagram
Acrylonitrile Production - Capacity
Projection
AN-3
AN-39
LIST OF TABLES
Figure No.
AN-1
AN-1A
AN-2
AN-3
AN-3A
AN-4
AN-5
AN-6
AN-7
AN-8
AN-9
AN-10
AN-11
AN-12
AN-13
AN-14
AN-15
AN-16
AN-17
AN-18
I-I
II-l
II-2
Title Page Number
Typical Material Balance AN-4
AN-6
Aerylonitrile Reactor System Heat Balance AN-7
Summary of U.S. Acrylonitrile Plants AN-9
Survey of U.S. Acrylonitrile Plants and AN-10
Atmospheric Emissions from These
Facilities (6 pages)
Typical Vent Gas Composition AN-16
CO-Boiler Emission Control System AN-21
Thermal Incinerator for Absorber Vent Stream AN-23
Thermal Incinerator Plus Waste Heat Boiler AN-24
for Absorber Vent Stream
Thermal Incinerator for By-Product Streams AN-26
Cost Effectiveness for Alternate Emission AN-32
Control Devices (2 pages)
Acrylonitrile Manufacturing Cost for a AN-43
Typical Existing 200 MM Lbs./Yr. Facility
Acrylonitrile Manufacturing Cost for a Typical AN-44
Most Feasible New 200 MM Lbs./Yr. Facility
Pro-Forma Balance Sheet AN-45
Estimated 1985 Air Emissions for Alternate AN-47
Control Systems
Detailed Costs for R&D Project A AN-54
Detailed Costs for R&D Project B AN-56
Detailed Costs for R&D Project C (2 pages) AN-59
Summary of Sampling and Analytical Methods AN-63
Reported for Pollutants (2 pages)
Financial Impact of Air Pollution Episodes on AN-71
Manufacturing Costs (2 pages)
Emission Summary (3 pages) 1-3
Number of New Plants by 1980 (Illustration) II-2
Weighted Emission Rates (Illustration) II-4
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i
SUMMARY
The acrylonitrile industry has been studied to determine the extent of
air pollution resulting from the operations of the various plants and processes
of the industry. The purpose of the work was to provide the Environmental
Protection Agency with a portion of the basic data required in order to
reach a decision on the need to promulgate air emission standards for the
industry.
Although a number of chemical routes to aerylonitrile are discussed in
the literature, only one, ammoxidation of propylene, is practiced to any
extent, anywhere in the world. In the United States, only the Sohio fluid
bed catalytic process is practiced. Therefore, this report is devoted to
the study of the Sohio version of the ammoxidation of propylene, using air
as the oxidant, for the production of acrylonitrile.
In general terms, the air emissions from the process fall into the
categories of hydrocarbons (paraffins, olefins and nitriles), carbon monoxide,
and oxides of nitrogen (primarily from waste and by-product incineration).
Some traces of particulate matter (catalyst fines) and ammonia are also
emitted, but not to a significant extent. The total amounts of all of these
materials emitted, and the ease of removing them from the effluent gas
streams are both somewhat a function of the catalyst used. The more
recent catalyst developments tend to lead in the favorable direction with
respect to both emissions and their control. The current (1974) generation
of catalyst which contains bismuth and molybdenum is gradually replacing
the older uranium (depleted) catalyst. The report has taken the effects of
this changeover into consideration in arriving at emission factors ranging
between 0.35 and 0.25 lbs./lb. of acrylonitrile produced. This amounted to
about 400 million lbs. per year of total atmospheric emissions in 1973 which
will be reduced to about 260 million lbs. per year as soon as the changeover
to new catalyst is fully effected. Of those totals, slightly more than half
is carbon monoxide, about one-fifth propylene and about four percent nitriles
(acrylonitrile, acetonitrile and hydrogen cyanide). Assuming no further
catalyst developments take place and all new plants also use the current
generation catalyst, production growth can be expected to increase total
emissions to nearly 900 million pounds/year by. 1985, if all future plants are
built as is currently typical, and if by-product incineration is practiced at
the 6ame proportionate level as has been estimated for today's operations, thus
contributing an approximate three percent or 25 million pounds per year of
nitrogen oxides to the total.
The chief source of air emissions from the process is the main vent from
the absorber. All plants employ a mist eliminator on this stream to minimize
the carryover of water (the absorbing medium) with the venting stream. However,
none of the current plant operators employ any additional air pollution control
devices on this stream. Hence, the study addressed itself to the task of
finding a "feasible" though not "demonstrated" emission control device for these
effluents. It was concluded that some form of incineration couLd be practiced
on this stream, and that the use of a thermal incinerator equipped with feed/
effluent heat exchange and supplemental fuel firing was the best technique for
achieving reductions in these emissions. It was further concluded that steam
generation by means of a waste heat boiler following the incinerator is a
feasible means of reducing the cost of emission control, provided that the steam
can be utilized. Additionally, steam generation from waste heat reduces the
impact of the supplemental fuel consumption on the overall fuel supply problems
of the U.S. and the world.
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ii
SUMMARY (continued)
Potentially, the second largest emission source from the process is the
disposal of large amounts of acetonitrile (0.1 lbs./lb. of acrylonitrile),
hydrogen cyanide (0.17 lbs./lb. of acrylonitrile) and ammonium sulfate (0.04
lbs./lb. of acrylonitrile), none of which are marketable in the quantities
and/or dilutions produced. Current practice is to incinerate all unwanted
HCN and to either incinerate the excess acetonitrile and ammonium sulfate
(the latter under emergency conditions, only) or dispose of them as dilute
water solutions in a deep well. If future ground water pollution control
regulations prevent the continued use of deep well disposal techniques,
significant air pollution as oxides of sulfur, could result from the incineration
of ammonium sulfate. Additionally, heat requirements to incinerate these
dilute water streams would be substantial. This study has concluded that
waste heat from absorber vent gas incineration is sufficient to concentrate
the waste acetonitrile to a point where it can be incinerated without
supplemental fuel. Furthermore, it appears feasible to use the effluent
from this incinerator in a spray drier to concentrate and recover the
ammonium sulfate. Obviously, the incineration of these nitrile containing
streams will result in the generation of some quantity of nitrogen oxides.
Determination of the amounts generated and the best designs for minimizing
these amounts must, by necessity, be the goal of future studies.
Minor vent streams result from product fractionation and the various
storage systems. Nearly all of these streams are currently flared or burned
in some other convenient manner.
Total air emissions from the acrylonitrile industry can be expected to
be reduced to about 40 million lbs./year in 1985 (about 0.01 lbs./lb. of
acrylonitrile) if absorber vent gas incinerators are included in all future
and existing plants. However, it has been estimated that this will result
in a 50 percent increase in the emission factor for nitrogen oxides (from
0.0067 to 0.0098 lbs./lb. of acrylonitrile) accounting for nearly 95 percent
of the total 1985 estimated emissions from the "best controlled" version
of the process. Obviously, if the proportion of by-products incinerated
changes, then the nitrogen oxide emissions will also be different from this
estimate.
The capital investment (1973 dollars) required for the installation of
a thermal incinerator on the absorber vent of a "model" 200 MM lbs./year
acrylonitrile plant has been estimated to be about $350,000. An additional
$410,000 will be required to add a waste heat boiler to the system and if a
highly reliable system is required, it might be deemed advisable to provide
multiples of one or both of these units. The annual operating cost of a
single thermal incinerator has been estimated (1973 prices) to be nearly
$136,000 and a $20,000 reduction can be effected through the addition of
a waste heat boiler.
The incinerator for by-product disposal from the model plant will require
between $200,000 and $400,000 capital investment depending upon the capacity
assigned to it and will cost between $50,000 and $70,000 per year to operate,
without provision for concentration of acetonitrile and recovery of ammonium
sulfate (or scrubbing of sulfur oxides if the salt solution is incinerated).
These are not significant costs to the industry, resulting in a reduction
of about 3 percent in net profit after taxes and a reduction in return on
total investment from 8.5 percent to about 8 percent. This is due partly to
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iii
SUMMARY (continued)
the fact that a by-product incinerator is typically part of all current plants.
These profit and ROI reductions apply to both new plants and existing plants
with retrofit incinerators.
The capital expenditure (1973 dollars) required for the industry to effect
the reduction in emissions cited above will be about $2,000,000 for all existing
plants with an additional $10,000,000 required for all future plants. This
assumes a single incinerator installed on each absorber vent gas stream and
a single waste heat boiler on all future plant incinerators.
The report cites three concepts for research that could lead to reduced
emissions from the aerylonitrile production process. Two of these could best
be undertaken by the process licensor and/or operators of the process. These
are (1) the use of oxygen rather than air feed to the reactor, with recycle
of off gases and (2) the utilization of by-product HCN and acetonitrile for
additional acrylonitrile production. The third area for research does not
require any acrylonitrile production knowledge or experience and could find
general application in any process for the production of organic nitrogen
products. It is the development of an efficient thermal incineration system
that minimizes nitrogen oxide formation.
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AN-L
I. Introduction
Although a variety of chemical routes to acrylonitrile exist, present
practice concentrates exclusively on the ammoxidation of propylene. Several
processes based on this reaction are used throughout the world, however,
only the Sohio fluid bed catalytic process, using air as the oxidant, is
employed la the United States.
Atmospheric emissions from this ammoxidation process consist of water
vapor, carbon dioxide, carbon monoxide, C3 hydrocarbons, N0X, nitriles and
nitrogen. The amount of nitrogen compounds emitted is somewhat influenced
by the amount of by-product hydrogen cyanide (HCN) and acetonitrile that can
be marketed.
A process description, industry survey of emission sources, effluent
characteristics, control practices and equipment in addition to plant
economics for the ammoxidation of propyLene process are presented in the
following sections.
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AN-2
II. Process Description and Typical Material Balance
The basic chemical equation for this process is as follows:
2 CH2=CH-CH3 + 2 NH3 + 3 02 > 2 Cl^=CH-CN + 6 H20
Approximately stoichiometric proportions of air, ammonia and propylene
are introduced into a fluid bed reactor at 5-30 psig and 750-950° F. Once-
through flow is used since conversion of propylene is virtually complete.
The reaction is exothermic so heat removal must be provided. The reaction
heat is normally used to generate steam by heat exchange and the effluent is
then sent to a water quench tower where acid is added for neutralization of
unconverted ammonia. The stream is then charged to a water absorber-stripper
system in order to reject inert gases and recover reaction products. This
operation yields a miaxure of acetonitrile, acrylonitrile and HCN which is
usually first fractionated to remove HCN. Next, acetonitrile is separated
from the HCN tower bottoms by extractive distillation (with water as the
extraction solvent). The final two steps involve drying of the acrylonitrile
stream (obtained overhead from the acetonitrile separation column) and a final
distillation to remove heavy ends. The acrylonitrile product thus obtained is
99+% pure.
Figure AN-1 shows a flow diagram for a typical plant and indicates the
various vent streams from the unit.
Primary raw material for acrylonitrile production are refrigeration
grade ammonia and propylene (>90% cf). No alternative raw materiaLs are
available for the Sohio process. Impurities in the propylene feed with less
than four carbon atmos are unaffected by the reaction, but those with four or
more participate and, therefore, are undesirable.
Acetonitrile and hydrogen cyanide are produced as by-products in the
amount of about 0.1 pound of each per pound of acrylonitrile. These products
can be produced at salable purity (99+% purity); however, it is doubtful that
the quantities produced can be marketed. Part or all of these by-products
are usually incinerated. It should be noted that four of the present
acrylonitrile producers are not listed by the U.S. Tariff Commission as being
sellers of acetonitrile.
Table AN-1 presents a typical material balance for acrylonitrile production.
The balance is based on the following yields which were derived from plant
survey data, taken while the plants were using Sohio's depleted uranium
catalyst (Catalyst 21):
These yields also approximate published values for Sohio's obsolete
bismuth/molybdenum catalyst (Catalyst A). Currently, even Catalyst 21 is
being phased out and replaced with Sohio's Catalyst 41 which achieves about
the same yields but provides better utilization of ammonia. Therefore, a
Bmaller amount of acid is required for downstream neutralization. Typical
ammonia feed rates for various catalysts currently in service vary between
0.39 and 0.56 pounds per pound of propylene feed. Catalyst 41 also requires
less excess oxygen and, therefore, less nitrogen in the vent gas.
LB./LB. Propylene Converted
Acrylonitrile
Acetonitrile
Hydrogen Cyanide
0.84
0.09
0.145
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TABLE AN-I
TYPICAL MATERIAL BALANCE FOR
SOHIO ACRYLONITRILE UNIT
PRODUCING 200 MM LBS./YR. ACRYLONITRILE (a>
Component
Particulates (b)
Carbon Dioxide
Carbon Monoxide
Asmonla
Propylene
Propane
Hydrogen Cyanide
Acrylonltrile
Acetonltrlle
Nitrogen
Oxygen
Sulfuric Acid
Ammonium Sulfate
Oxygenated Hydrocarbons
Organic Polymers
Water
Total Lbs./Hr.
Propylene
Feed
31,454
3,495
2
Ammonia
Feed
12,953
65
3
Air to
Reactor
34,949
13,018
207.204
63.002
2,945
273,151
Sulfuric Acid
to Neutrallzer
Ammonium Sulfate
Solut i on
3,708
3,708
4,994
29,541
34,535
Absorber
Vent Cae
TR '
11,171
4 ,466
1,956
3.495
30
248
95
207,056
15.664
14 191
*58,37?
Component
Part iculatee (b)
Carbon Dioxide
Carbon Monoxide
AuDonla
Propylene
Propane
Hydrogen Cyanide
Acrylonltri le
Acatonltrlle
Nitrogen
Oxygen
Sulfuric Acid
Ammonium Sulfate
Oxygenated Hydrocarbons
Organic Polymers
Water
Total Lbs./Hr.
Hydrocyanic
Acid
4,202
22
13
Make-up Water
to Product Diet.
4,239
30.306
50.30h
9
Dilute
Acetonitrlle
2,424 (c)
48.006
10.430
10
Light
Ends
47
44
50
213
63
11
Heavy
Ends
2.300
(c)
2 ,723
50
150
200
1?
Aerylonitrile
Product
?4,510
7S
7U
74
74 . f.33
(a) Based on using, Sohlo'a Catalyst 21 which le currently being phased out of all domestic aerylonltrtle plants, when operation^ with Catalyst 41, air rate is reduced
by 2u percent and ammonia feed is about eight percent lover. Improved utilization of aomonia reduces Sulfuric acid requirement and ammonium sulfate production to
25 percent of values shovn.
(b) Catalyst particles.
(c) Can be rejected as a separate stream.
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AN-5
Table AN-1 material balance is for an average size plant (200 MM lbs./yr.
acrylonitrile), utilizing Catalyst 21. However, since yields are about the
same with Catalyst 41, this balance will be used to predict the economics
of future plants (in the Model Plant Economic Studies), except that nitrogen
in the vent gas, and ammonia and sulfuric acid requirements will be appropriately
reduced. Table AN-1A presents the same material balance with quantities
expressed as tons per ton of acrylonitrile.
At present, only one producer of acrylonitrile has completely switched
over to Catalyst 41. All other producers are operating with some portion of
Catalyst 21. Catalyst 41 is an improved version of the old bismuth/molybdenum
catalyst.
Table AN-2 presents an estimated heat balance around the reactor system.
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(b)
Component
Particulate
Carbon Dioxide
Carbon Monoxide
Ammonia
Propylene
Propane
Hydrogen Cyanide
Acrylonitrile
Acetonitrile
Ni trogen
Oxygen
Sulfuric Acid
AcxDoniutn Sulfate
Oxygenated Hydrocarbons
Organic Polymers
Vater
Total, TonB/Ton AN
Propylene
Feed
1.2833
0.L426
Ammonia
Feed
0-5285
0.002 7
TABLE AN-1A
TYPICAL MATERIAL BALANCE FOR
SOtilO ACRYLONITRILE UNIT (a)
3
Air to
Reactor
1.4259
0.5312
8.4539
2.5705
0.1202
11.1446
Sulfuric Acid
to Neutralizer
Ammonium Sulfate
Solution
0.1513
0.1513
0. 2038
1.2053
1.4091
Absorber
Vent Gas
TR
0.455*
0.1822
0.0798
fl. 1426
0.0012
0.0101
0.0039
8.4478
0.6391
0.5790
10.5415
Component
Particulate C5)
Carbon Dioxide
CaTbon Monoxide
Ammonia
Propylene
Propane
Hydrogen Cyanide
Acrylonitrile
Acetonltrlle
Nitrogen
Oxygen
Sulfuric Acid
Ammonium Sulfate
Oxygenated Hydrocarbons
Organic Polymers
Water
Total Tons/Ton AN
Hydrocyanic
Acid
Make-up Water
to Product Diet.
0.1714
0.0009
0.0001
0.0005
0.1729
2.0525
2.0525
9
Dilute
Acetonltrlle
0,0989
(c)
1.9587
2.0576
10
Light
Ends
0.0020
0.0001
0.0018
0.0020
0.0087
0.Q026
0.0002
0.0938
oTirTT
11
Heavy
Ends
0.0020
0.0061
0,0081
12
AcrylonltrlLte
Product
1.0000
0.0031
0.0010
0.0010
1.0051
(a) Based on using Sohio's Catalyst 21 which is currently being phased out of all domestic acrylonitrile plants. When operating with Catalyst 41, air rate is reduced by
20 percent and ammonia feed Is about eight percent lower. Improved utilization of ammonia reduces sulfuric acid requirement and ammonium sulfate production to 25 percent
of vaLues shown.
(b) Catalyst Particles
(c) Can be rejected as a separate stream*
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AN-7
TABLE AN-2
ACRYLONITRILE REACTOR SYSTEM
HEAT BALANCE (a)
Heat Out
Steam generation
Cooling coils inside reactor
Effluent heat recovery boiler
Reactor heat losses
Quench (450o > 110° F)
Incremental effluent heat content
(b)
Total
Heat In
Exothermal heat or reaction
Aerylonitrile formation
Effluent neutralization
Feed vaporization and preheat
Total
6,733 BTU/Lb. of aerylonitrile
2,158
45 " •' "
4,091 "
1,000
12,027
9,432 BTU/Lb. of acrylonitrile
1,375
1,220 " "
12,027
NOTES:
(a) Basis
1) Table AN-1A material balance (Catalyst 21).
2) Feed preheated to 300° F.
3) Reactor outlet temperature 950° F (max.).
(b) Difference in heat content of effluent @ 110° F and feed @ 80° F (liquid)
plus air @ 100° F.
-------
AN-8
III. Manufacturing Plants and Emissions
Table AN-3 presents a list of U.S. plants producing acrylonitrile.
Approximately half of the total production capacity is located in Texas (two
producers), with the remaining acrylonitrile production in Louisiana, Ohio and
Tennessee. These plants are built within five to 15 miles of towns and cities
with population ranging between 10,000 and 625,000.
Table AN-3A shows individual plant capacity figures and atmospheric emission
data for the various acrylonitrile plants surveyed in this study while using
Catalyst 21. All of the plants included in this tabulation are about the same
size (175-250 million pounds per year acrylonitrile) and represent about 85
percent of the total U.S. installed plant capacity. Emissions from these plants
are as follows:
A. Continuous Air Emissions
1. Main Process Vent Gas
This stream, which vents from the absorber, consists of the gross
reactor effluent after neutralization and recovery of nitriles and HCN.
The process vent gas emissions presented in Table AN-3A are average
values using Catalyst 21. Actual vent gas composition varies somewhat
depending on type of catalyst and reactor operating conditions.
Table AN-4 shows a typical breakdown of components in this stream which
represents the primary air emission in the Sohio process. Vent gas
composition data is shown for both catalysts currently being employed.
When absorber column overhead temperature increases, acrylonitrile
emissions increase markedly (0.008 to 0,02 tons/ton acrylonitrile). One
manufacturer reports this occurs about once a year with the increased
acrylonitrile emissions lasting no longer than one day.
Under normal operating conditions, the quantity of absorber vent
hydrocarbon emissions (excluding propane and propylene) are primarily
influenced by the amount of air charged to the reactors. Since fluidized
bed reactors are employed, it is necessary to maintain reactor mass
flow velocity within a certain range in order to insure proper bed
expansion. Therefore, air rates to individual reactors are usually
held fairly constant. Plants normally have two to five reactors. At
reduced plant capacity, individual reactors can be removed from service,
and total absorber vent gas emissions will be reduced. Plants with
only two reactors do not have as much flexibility.
In all plants, propane, propylene and carbon monoxide emissions
from the absorber are directly related to acrylonitrile productivity.
Since propane is not converted in the reactor, virtually all propane
contained in the fresh feed will be present in the absorber vent gas.
The absorber off-gas, as is true with the other vent streams, is
essentially odorless under normal operation. However, one manufacturer
reports a slight odor of HCN from the absorber vent during reactor
start-up. None of the plant surveys reported any particulates in this
vent stream.
-------
AN-9
TABLE AN-3
SUMMARY OF U. S. ACRYLONITRILE PLANTS
Published
Company Location Capacity, MM Lbs./Yr.
American Cyanamid Co. South Kenner, La. 175
E. I. duPont deNemours & Co. Beaumont, Texas 200
Memphis, Tenn. 180
Monsanto Co. Alvin, Texas 370
Vistron Corp. Lima, Ohio 240
1,165
-------
TABLE AN-3A
SURVEY OF U. S. ACRYLONITRILE PLANTS
AND ATMOSPHERIC EMISSIONS FROM THESE FACILITIES
Sheet 1 of 6
Plane Code Number
Dace on-stream
Capacity, Tons of Aerylonitrile/Yr.
Average Production, Tons/Yr.
Range in Production, % of Max.
Operating Range, 7. of Max. Prod.
By-products (Net)
HCN, Tons/Yr.
Oils & Polymers, Tons/Yr.
Emissions to Atmosphere
Stream
Flow, (a) Lbs./Hr.
Flow Characteristic
if Intermittent - Hrs./Yr. of Flow
Composit iont Tons/Ton Aerylonitrile
Particulate
Carbon Dioxide
Carbon Monoxide
Ammonia
Methane
Ethane & Ethylene
Propylene
Propane
Hydrocyanic
Acrylonitrile (AN)
Acetonitrile (ACN)
Oxygenated Hydrocarbons
Nitrogen
Oxygen
Sulfur Oxides
Nitrogen Oxides
Water
Sample Tap Location
Date or Freq. of Sampling
Type of Analysis
Particulate
HC, CO, CO2 & Inerts
Color
Vent Stacks
Number
Height
Diameter
SCFM per stack (a)
Emission Control Device
Deniister
Condenser
Others
Total Emissions
Hydrocarbons
Particulates
mx
sox
CO
51-1
1965
100,000 (1)
100,000
No Seasonal Variation
50-100
20,000
A ,000
4,000
(b)
Absorber Vent
285,000
Continuous
Absorber Vent
(During Start-up)
62,500 <°)
Intermittent
8
0.294
0.180
TR
0.050
0.032
0.032
Product
Fractionator Vent
Incinerator
Flue Gas
Flare
110
Continuous
110.000
Continuous
¦£11.300
Variable
TR
X
0.0003
0.047
0.124
0.002
None
Smokeless
1
135'0"
6*0"
1600
24.000
X
None
Calc1d
None
Smokeles
1
275'0M
1'8"
>1500
<.265
Flare (Distillation Lt. Ends) Incinerator (By-product HCN & ACN)
0.209
TR
0.007
0. 180
-------
TABLE AN-3A
SURVEY OF U. S. ACRYLONITRILE PLANTS
AND ATMOSPHERIC EMISSIONS FROM THESE FACILITIES
Sheet 2 of 6
Plant Code Number
51-2
Date on-stream
Capacity, Tons of Acrylonitrile/Yr.
Average Production, Tons/Yr.
Range in Production, X of'Max.
Operating Range, % of Max. Prod.
By-products (Net)
HCN, Tons/Yr.
Acetonitrile, Tons/Yr.
Oils & Polymers, Tons/Yr.
Emissions to Atmosphere
Stream
Flow, Lbs./Hr.
Flow Character 1stic
if Intermittent - Hrs./Yr. of Flov
Composition, Tons/Ton AerylonitriLe
Par t icu Late
Carbon Dioxide
Carbon Monoxide
Ammonia
Methane
Ethane & Ethylene
Propylene
Propane
Hydrocyanic Acid
Aerylonitrile (AN)
Acetonitrile (ACN)
Oxygenated Hydrocarbons
Nitrogen
Oxygen
Sulfur Oxides
Nitrogen Oxides
Water
Sample Tap Location
Date or Freq. of Sampling
Type of Analysis
Particulate
HC, CO, CO2 & Inerts
N0X
Odor
Color
Vent Stacks
Number
Hei ght
Diameter
Exit Gas Temp.
SCFM per stack
Emission Control Device
Demister
Condenser
Others
Total Emissions
Hydrocarbons
Particulates
NO*
SOx
CO
1965
125.000
100,000
No Seasonal Variation
7,000
3,200
Absorber vent
200,000
Continuous
"f
0.508
0. 178
0.052
0. 144
0.0005
0.0004
0.008
7.222
0.303
Absorber Vent
Nitrogen Comp'd. once a week, others in 1971
None
CLC ^
Silver Nitrate Titration
i
200'0"
2*6"
110
50,000
Absorber Vent
(During Start-up)
140,000 <°>
Intermittent
6-8
0.080
0.040
0.026
0.027
0.034
0. 608
0.017
5. 185
0. 218
30.000
Incinerator
Flue Gas (g)
46,700
Continuous
0.282
< 0.000001
1. 251
0. 174
0.00001
0. 160
Used 130' crane
March. 1971
None
G1C 600
-------
TABLE AN-3A
SURVEY OF U. S. ACRYLONITRILE PLANTS
AND ATMOSPHERIC EMISSIONS FROM THESE FACILITIES
Sheet 3 of 6
Plant Code Number
51-3
Date on-stream
Capacity, Tons of Acrylonltrlle/Yr.
Average Production, Tons/Yr.
Range in Production, */«, of Max.
Operating Range, % of Max. Prod.
By-products (Net)
HCN, Tons/Yr.
Acetonitrile, Tons/Yr.
Oils & Polymers, Tons/Yr.
Emissions to Atmosphere
S tream
Flow,
(a)
Lbe./Hr.
Flov Characteristic
if Intermittent - Hrs./Yr. of Flow
Compos!tion, Tons/Ton Aerylonitrile
Particulate
Carbon Diojcide
Carbon Monoxide
Aranon 1 a
Methane
Ethane & Ethylene
Propylene
Propane
Hydrocyanic Acid
AeryIon!trile (AN)
Acetonitrile (ACN)
Oxygenated Hydrocarbons
Nitrogen
Oxygen
Sulfur Oxides
Nitrogen Oxides
Water
Sample Tap Location
Date or Freq. of Sampling
Type of Analysis
Particulate
HC, CO, C02 & Inerts
NO
Odor X
Color
Vent Stacks
Number
Height
Diameter
Exit Gaa Temp., °F_
SCFM per stack (®)
Emission Control Device
Demister
Condenser
Others
Total Emissions
Hydrocarbons
Particulates
N0X
SO*
CO
1965
87.500
No Seasonal Variation
16,000
Absorber Vent
225,000
Continuous
0.450
0.187
0.001
0.008
0.050
0.035
0.006
Absorber Vent
(During Start-up)
N. A. (q)
Intermittent
15
0.264
0.216
0.008
9. 133
0.856
0.383
Absorber Vent Sample
Line to Ground Level
AN once every three months, other H.C. much less frequent
None
C.C.
None
No problem
1
200*0"
2 1 6"
105
50,000
Flare
4,100
Continuous
X
None
Not Sampled
None
No problem
1
200'0"
2 '6"
Flame
< 1200
Flare (DiBtlllatlon Lt. Ends), 2 Incinerator (By-products
0.101
0.026
0.1S7
Incinerator
Flue Gas
400,000 (Max.)
Intermittent
026
X
None
Not Samples
None
No problem
104'0M
9 • 0 "
1600
88.000
(Max. )
-------
TABLE AN-3A
SURVEY OF U. S. ACRYLONITRILE PLANTS
AND ATMOSPHERIC EMISSIONS FROM THESE FACILITIES
Sheet A of 6
Plant Code Number
Date on-stream
Capacity, Tons of Aerylonitrile/Yr.
Average Production, Tons/Yr.
Range In Production, % of Max.
Operating Range, 7. of Max. Prod.
By-products (Net)
HCN, Tons/Yr.
Acetonitri Le, Tons/Yr.
Oils & Polymers, Tons/Yr.
EmlSBione to Atmosphere
Stream
Flow, (a) Lbs./Hr.
Flow Characteristic
if Intermittent - Hrs./Yr. of Flow
Composition, Tons/Ton Aerylonitrile
Particulate
Carbon Dioxide
Carbon Monoxide
Ammonia
Methane
Ethane & Ethylene
Propylene
Propane
Hydrocyanic Acid
Acrylonitrile(AN)
. Acetonitrile (ACN)
Oxygenated Hydrocarbons
Nitrogen
Oxygen
Sulfur Oxides
Nitrogen Oxides
Water
Sample Tap Location
Date or Freq. of Sampling
Type of Analysis
Particulate
HC, CO, CO2 and Inerts
N0X
Odor
Color
Vent Stacks
Number
Height
Diameter
Exit Gas Temp., °F
SCFM per stack
Emission Control Device
Demister
Condenser
Others
Total Emissions
Hydrocarbons
Particulates
NO*
SO*
CO
51.-4
1970
110,000
110.000
Virtually No Seasonal Variation
20,000
Absorber Vent
300,000
Continuous
0.350
0.167
Absorber Vent
(During Start-up)
N. A.
Intermittent
2
0.001
Incinerator
Flue Gas
98,000
Variable (1)
0.317
Product Recovery
Flare Vent
2. 500
Continuous
0.018
HCN Storage
Flare Vent
750
Continuous
0.004
0.001
0.050
0.035
0.004
0.009
0.003
0.0004 (m)
8.774
0.763
0.787
Absorber Vent Sample
Line to Grourid Level
Once a Week
None
GLC
NH3 + HCN by Titration
No problem
2.290
0.0004
0. 709
Sample Tap Avail.
Never Sampled
None
No problem
0.067
0.00001
0.005
None
Never Sampled
None
No problem
0.020
0.00001 (O
0.002
None
Never Sampled
None
No problem
1
224'0M
3 '0"
113
69,000
1
lOO'O"
7' 6"
1600
23,000 (1)
I
iso'O"
1
540
lOO'O"
6"
170
Incinerator (Distillation Lt. Ends
0.102
0.0004
0.167
(1)
), 2 Flares
-------
AN-14
Table AN-3A Footnotes Sheet 5 of 6
(a) Wet gas flow rate based on acrylonitrile average production rate if
available, otherwise based on design capacity.
(b) Assumed composition of "miscellaneous" component.
(c) Air.
(d) Only acrylonitrile (AN) in absorber vent gas is measured directly (by
gas chromatogrflph). Flow and composition are calculated values based on
measured flows of air, propylene and ammonia into the process and on
analysis of the reactor effluent. This analysis is by a combination
of wet chemistry, physical separation and chromatographic techniques.
(e) Analyzed for N0X per method 7 - Determinations of Nitrogen Oxide from
Stationary Sources, Federal Register, vol. 36, No. 247, December 23, 1971.
HCN and NH3 by Draeger tubes.
(f) Gas stream is scrubbed. Scrubber solution is anaLysed for HCN 'silver
nitrate titration) AN and ACN (by gas-liquid chromatography).
Scrubbed gas is analysed for other components by chromatograph
(N2 by difference).
(g) Flow rate and composition based on burning approximately 40% of by-product
HCN. Incinerator designed to burn all by-products and 190 gpm of waste
water. Presently all waste water (300 gpm) plus a major portion of the
by-product ACN are - sent to deep well disposal.
(h) Shell procedure for sulfur oxides.
(i) Company also has a 92,500 TPY plant at some location. Approximate emissions
for this unit are a direct proration of values shown for the slightly
larger plant.
(j) No normal flow. Incinerator only used during emergency periods when
waste wash water streams containing (Nlfy^SO^ and by-product ACN are
diverted from deep well disposal (once a year) and HCN can not be sent
to storage (almost no chance of this occurring).
(k) Maximum flow of 58,000 SCFM during emergency. This includes combustion
of feed propylene (0.331 tons/ton AN) when source of heat for propylene
vaporization is lost (occurs about once every two years for two hours).
Also during scheduled shut-down vaporizers are vented to flare. This
vent is about 25% of emergency flow.
(1) Represents normal flow from burning some by-product nitrogen compounds
rejected in product recovery section including 50 tons/month HCN.
Occasionally during process upsets total by-product HCN is sent to this
incineration. When this occurs flow is increased to 95,000 SCFM. On
an average 100 tons/month of HCN is burned in this incinerator.
(m) Composition is approximately 49 wt. % acetaldehyde, 32% acetone and 19%
acrolein.
(n) Includes 0.005 tons/ton of miscellaneous compounds not identified.
-------
AN-15
Table AN-3A Footnotes (Continued) Sheet 6 of 6
(o) This condition represents the operation during start-up of one reactor.
While flow condition and composition change during the start-up, these
data represent average values. Start-up time normally requires a maximum
of one hour. Data shown is for start-up of one reactor of a two reactor
plant. If other reactor is on-stream total vent will contain indicated
flow plus 507„ of normal absorber vent shown in preceding column. On an
average, eight reactor start-ups per year are expected.
(p) In addition, HCN is diverted from incinerators to flare about once a year.
Propylene storage tanks relieve to flare on infrequent basis.
(q) Same as comment (o) except this plant has five reactors. If other reactors
are on-stream, total vent will contain indicated flow plus 80% of normal
absorber vent shown in preceding column.
(r) Calculated value based on U. S. Dept. of HEW factors for calculating
emissions from burning natural gas.
(6) In the near future all by-product HCN will be burned.
(t) Flow based on burning all by-product HCN and ACN.
It should be noted that flow rates and compositions shown for intermittent
streams represent emissions during flowing condition and not yearly averaged
values. The total plant emission figures shown are averaged emissions for
extended periods of operation.
-------
TABLE AN-4
TYPICAL VENT GAS COMPOSITION
FOR
200 MM LB./YR. ACRYLONITRILE PRODUCTION
Operation
Catalyst
21
Catalyst
41
(a) Mol. %
Start-up
Normal Composition
Average
Flow Rate
Flow Rate
Average Flow Rate
Range-Catalyst 21
Catalyst 41 C5)
MPH
Lbs./Hr.
Lbs./Hr. (c)
MPH
Lbs./Hr.
Component
Particulate
TR
25
TR
Carbon Dioxide
1.5 - 3.7
2.6
253.9
11,171
1,593
189.6
8,342
Carbon Monoxide
1.3 - 2.0
1.5
159.5
4 ,466
882
107.0
2,996
Ammonia
392
Propylene
0.2 - 0.5
0.31
46.5
1,956
417
22.3
939
Propane
0.2 - 1.0
0.47
79.3
3,495
711
33.8
1,491
Hydrocyanic Acid
0.006 - 0.04
0.006
1.1
30
466
0.4
12
£
Aerylonitrile
0.002 - 0.13
0.0016
4.7
248
10,221
0.1
6
1
1—'
Acetonitrile
0.02 - 0.06
0.054
2.3
95
319
3.9
160
Nitrogen + Argon
78 - 84
80.9
7,394.9
207,056
84,094
5,809.9
162,677
Oxygen
3.0 - 6.8
0.1 - 2.5
489.5
15,664
5,686
60.3
1,931
Water
5.5 - 11.0
13.3
788.4
14,191
3,726
955.3
17,195
NOx
0.0003
TR
1
1 9,220.1
258,372
108,532
7,182.6
195,750
(a) Does not include start-up operation.
(b) Based on data from one producer.
(c) Represents average flow during start-up of one reactor in a two reactor system. If other reactor is on-stream, total
vent will contain indicated flow plu6 50 percent of normal flow shown in preceding column.
-------
AN-17
2. Product Fractionation Vent
This represents a small stream, which varies greatly in composition,
depending upon type of fractionation system used for product recovery.
In some cases, this stream consists of the combined vent from several
fractionators. Normally this material is sent to an incinerator or
flare but at least one manufacturer vents part of this gas, which
contains some nitriles (0.0007 tons/ton of aerylonitrile), directly
to the atmosphere.
3. Product Storage Vent
Because of the low vapor pressure of aerylonitrile and acetonitrile
at ambient temperature (3-5 PSI), storage tanks for these two products
are directly vented to the atmosphere. In some cases, conservation
type vents are employed for safety reasons but they also tend to reduce
emissions.
Since HCN is volatile (78° F boiling point), it is stored under
positive pressure and generated vapors are cooled by refrigeration for
recovery of HCN (-15 to 30° F)* Non-condensibles plus associated HCN
are normally sent to incineration.
4. By-Product Incineration
In most cases, production of acetonitrile and HCN exceeds demand
and excess production is sent to an incinerator. Based upon published
data 2,3,4 it is likely that a small portion of the chemically bonded
nitrogen contained in the incinerator feed is converted to NOx.
Therefore, the quantity of NOx production is related to the amount of
by-product HCN and acetonitrile that is burned. This contradicts
limited survey data which show NOx emissions to be low (51-1 and
51-2) and independent of feed composition (51-2).
Published data on by-product incineration by one aerylonitrile
manufacturer shows that NOx yield is one to three percent of theoretical
in their commercial incinerator operating at 1600° F.18 when similar
compounds were burned in a laboratory incinerator, NOx production
increased to eight to 17 percent of theoretical. This appears to
indicate that peak flame temperature, burner configuration and oxygen
diffusion phenomena are all important in determining the amount of
NOx produced.
B. Intermittent Air Emissions
1. Process Vent Gas
During reactor start-up, the reactor effluent may by-pass the
neutralizer and may be directly vented to the atmosphere. Table AN-4
shows a typical average composition for this vent stream during
start-up of one reactor in a two reactor system using Catalyst 21.
Actual stream composition changes during the start-up. This operation
normally requires a maximum of one hour with one plant start-up every
one or two years.
-------
AN-18
Only one of the plant surveys (51-4) showed an estimate of the
amount of particulates emitted in this stream. No data are available
regarding the size distribution of these particulates which are
catalyst fines that have passed through the reactor cyclones.
During normal on-stream operation these fines are removed in the
neutralizer and downstream absorber.
2. Emergency Relief
During plant up-set or other emergencies the following streams
are occasionally diverted to the flare stack or by-product incinerator:
(a) Propylene Storage
Propylene storage tank relief valves discharge to flare.
However, this is an infrequent occurence.
(b) Propylene Feed
Propylene is directed to the flare if the source of heat for
feed vaporization is lost and freeze-up of the vaporizer
occurs. This happens about once every two years with the
flaring lasting about two hours (hourly propylene loss
approximately 0.35 tons/ton of acrylonitrile). In addition,
during yearly scheduled shut down vaporizers are normally
sent to flare. This deliberate shut down results in flaring
about 25 percent of the amount of propylene lost during
emergency conditions.
(c) By-Product HCN
If by-product HCN is normally marketed, ah up-set in the
product fractionation system can throw the HCN off specification
In this event the HCN is not reprocessed but is usually sent
to an incinerator.
Liquid Wastes
1. Neutralizer Effluent
Normally sulfuric acid is used to neutralize the reactor effluent
(acetic acid has also been proposed for this operation). A 10 to
20 wt. 7» ammonium sulfate solution is obtained in the ammonia neutral-
ization and condensation of water from the reactor effluent. Since
market demand for ammonium sulfate is low, this stream (0.4 - 3 tons/
ton acrylonitrile) is sent to deep well disposal. Several of the
plants have by-product incinerators capable of burning some of this
material. However, such incineration may result in exceeding emission
limitations on sulfur oxides and/or particulates.
2. Product Recovery Waste Water
There are two waste water streams rejected from the product
fractionation system. Disposal of one of these streams (one to three
tons/ton acrylonitrile) is normally by the same methods used for the
neutralizer effluent. This stream is low in total cyanide content and
has essentially no acetonitrile. The second stream is much smaller
in quantity and contains up to 3 wt. % HCN and 3 to 8 percent acetonitril
-------
AN-19
This reject stream is either incinerated or disposed of via deep veil
The range in acetonitrile content of this stream depends on whether or not
acetonitrile is recovered as a by-product.
D. Solid Wastes
Solid wastes, ranging between 0.0003 to 0.008 tons/ton acrylonitrile,
are removed from waste water settling ponds. This sludge consists of
catalyst fines and polymers removed in the reactor effluent neutralizer.
In plants employing uranium catalyst, this solid waste is radio-
active (approximately two uc/lb.) and disposal is in accordance with
AEC regulations. Other types of spent catalyst are sold for metals
recovery.
-------
AN-20
Emission Control Devices and Systems
A. Emission Controls on Main Process Vent
1. Devices Currently Employed
At present most of the U.S. plants do not have any significant
emission control facilities on the absorber vent stream. All plants
incorporate a mist eliminator in the top of the absorber to prevent
liquid carryover to the atmosphere. However, thiB rather inexpensive
device does not reduce hydrocarbon emissions.
2. Combustion Devices (None Currently in use on Acrylonitrile Plants)
The most practical method of reducing the amount of CO and hydro-
carbons in the absorber vent gas is by using one of the following
combustion devices:
(a) CO-Boiler
Employing a CO-boiler is one of the more efficient methods of
removing these contaminates. However, as reported in another
volume of this series (Carbon Black - EPA-450/3-73-006a), by-
product steam credits can not usually off-set operating costs.
A large amount of steam is presently produced in the
conventional acrylonitrile plant by internal coils in the reactors
and indirect heat exchange with reactor effluent. This steam is
used to drive the air blower and provide process steam requirements.
Therefore, most if not all the steam produced in conjunction with
any pollution control device will have to be exported. If it is
decided to concentrate acetonitrile prior to incineration, about
30 percent of the CO-boiler net steam production could be used
for this fractionation; see Section C-l.
Table AN-5 presents a typical material balance for a CO-boiler
processing the absorber vent gas from a 200 MM lbs./yr acrylonitrile
plant employing Catalyst 41. In order to insure complete combustion
of pollutants, the data in Table AN-5 are based on an 1800° F
combustion zone temperature and four mol. percent oxygen (dry basis)
in the stack gas.
No existing U.S. plant employs CO-boilers or any other combustion
device on this vent stream. Therefore, it is difficult to
accurately predict equipment performance in this application.
Based upon applications in other areas, the following potential
problems exist with off-gas burning in CO-boilers:
(1) Vent gas is available at low pressure.
(2) Investment for required blowers, large diameter pipes
and valves, burning equipment, control systems and
steam utilization systems is high.
-------
AN-21
TABLE AN-5
CO-BOILER EMISSION CONTROL SYSTEM
FOR
200 MM LB./YR. ACRYLONITRILE PLANT
ABSORBER VENT STREAM
OVERALL MATERIAL BALANCE, LB./HR.
Process Comb. Natural Flue
Component Vent Gas Air Gas Gas
Carbon Dioxide 8,342 40,680
Carbon Monoxide 2,966
Methane 5,858
Ethane 1,291
Propylene 939
Propane 1,491
Hydrogen Cyanide 12
Acrylonitrile 6
Acetonitrile 160
Nitrogen 162,677 179,598 601 342,900
Oxygen 1,931 54,547 17,514
Water 17,195 3,097 39,558
Nitrogen Oxides 90
Total Lbs./Hr. 195,750 237,242 7,750 440,742
SCFM 45,370 100,550
Flue Gas
700° F
80 F
Comb. Air
Natural Gas
(Supplemental Fuel)
Process Vent Gas
(110 °F )
BF Water 123,200 Lb./Hr. (240 °F)
Steam @ 450 PSIG and 750 °F
117,300 Lb./Hr. Total
100,900 Lb./Hr. Net
Blowdown 5 ,900 Lb./Hr.
(460 °F)
-------
AN-22
(3) Because the gas has a low heating value (20 to 40
BTU/Ft.3), 25 to 70 percent of the total heat requirement
must be added as supplemental fuel in order to achieve
complete combustion.
(4) Flame control is difficult due to low heating value and
low level of incandescence, therefore, flame-outs are
common.
(b) Thermal Incinerators
Table AN-6 presents a material balance for this type of
control device. Data in this table are based on the same com-
bustion zone operating conditions used for the CO-boiler. Heat
generated from burning the process vent gas plus feed effluent
heat exchange and a small amount of supplemental fuel are required
to obtain the desired operating temperature. If heating value
of the gas differs from the 24 BTU/Ft.3.used in Table AN-6, heat
balanced operation can be obtained by adjusting the amount of
supplemental fuel.
Burning of off-gas in a conventional thermal incinerator
results in similar burning problems and combustion efficiency
anticipated for a CO-boiler.
(c) Incineration plus Steam Generation
Table AN-7 presents a material balance and sketch for a
thermal incinerator followed by a waste heat boiler. This
combination facility has an emissions control efficiency similar
to that of the CO-boiler but does not produce as much steam.
(d) Catalytic Incinerator
A catalytic incinerator could reduce pollutants to similar
levels obtained with a thermal unit. The catalytic incinerator
would operate at lower temperature (900-1200° F) and, therefore,
would probably produce somewhat less NOx. As found in the carbon
black in-depth Btudy previously mentioned, catalytic incinerator
operating costs would be higher than those projected for a
thermal unit.
(e) Flare System
This control device is different from a plume burner in that
the plume burner has a self supporting flame. It has the following
limitations:
(1) A large amount of supplemental fuel is required to sustain
combustion (180 MM BTU/hour with Catalyst 41 or 125 MM
BTU/hr. with Catalyst 21).
(2) Efficiency for removal of contaminants is less than for
other combustion devices. Based upon qualitative data
from similar control devices in the carbon black industry,
it is estimated that 90 percent of CO and hydrocarbon-
pollutants will be burned.
-------
AN-23
Component
Carbon Dioxide
Carbon Monoxide
Methane
Ethane
Propylene
Propane
Hydrogen Cyanide
Acrylonitrile
Acetonitrile
Nitrogen
Oxygen
Water
Nitrogen Oxides
Total Lbs./Hr.
SCFM
TABLE AN-6
THERMAL INCINERATOR
FOR
200 MM LB./YR. ACRYLONITRILE PLANT
ABSORBER VENT STREAM
OVERALL MATERIAL BALANCE. LB./HR.
Process
Vent Gas
8,342
2,996
939
1,491
12
6
160
162,677
1,931
17,195
1
195,750
45,370
Combustion
Air
81,529
24,757
1,408
107,694
Natural Gas
755
167
78
1,000
Flue Gas
23,398
244,315
12,301
24,353
77
304,444
69,440
950° F
Natural Gas
Stack Gas
1055° F
-v-
AA
1800° F
80° F Combustion Air
Process Vent Gas (110° F)
-------
AN-24
TABLE AN-7
THERMAL INCINERATOR PLUS WASTE HEAT BOILER
FOR
200 MM LB./YR. ACRYLONITRILE PLANT
ABSORBER VENT STREAM
OVERALL MATERIAL BALANCE. LBS./HR.
Component
Carbon Dioxide
Carbon Monoxide
Methane
Ethane
Propylene
Propane
Hydrogen Cyanide
Acrylonitrile
Acetonitrile
Nitrogen
Oxygen
Water
Nitrogen Oxides
Total Lbs./Hr.
SCFM
Process
Vent Gas
8,342
2,996
939
1,491
12
6
160
162,677
1,931
17,195
1
195,750
45,370
Combustion
Air
81,529
24,757
1,408
107,694
Natural Gas
755
167
78
1,000
Flue Gas
23,398
244,315
12,301
24,353
77
304,444
69,440
Stack Gas
700° F
Blow Down
460° F, 1,300 lbs
Natural Gas
Process Vent Gas
110° F
Comb. Air
80° F
Boiler Feed Water
27,300 lbs./hr.,
240° F
Steam @ 450 PSIG, 750° F
26,000 lbs./hr. total
19,500 lbs./hr. net
-------
AN-2 5
(3) Improper firing of the burner could result in operating
temperatures which favor NOx formation.
(4) Changes in vent gas composition could extinguish the
burner if adequate instrumentation is not provided.
(f) Limitations
Most of the above methods of contaminent removal result in
a small amount of NOx formation. In addition, if the supplemental
fuel contains sulfur compounds some sulfur oxides would also be
present in the vent stream.
B. Product Fractionation Vent Gas
Currently this stream is usually sent to a flare stack. None
of the surveyed plants have attempted to analyze the flare stack
effluent. However, it is estimated that more than 90 percent of
the combustibles are burned. Since the quantity of fractionation
vent gas is small (Table AN-3, Stream 10), there is little incentive
to use a more efficient combustion device.
C. By-Product Disposal
1. Thermal Incineration
All plants surveyed have a thermal incinerator for burning
some by-products on a continuous or intermittent basiSo At present
a major portion of by-product acetonitrile is sent to deep well
disposal. Assuming that regulations on water pollution continue
to become more stringent, it is likely that in the future other
methods for disposal of this chemical will be required.
Approximately 10 percent of by-product HCN is currently sent
to deep well disposal and about 40 percent is burned in incinerators.
Polymers and heavy ends recovered in product fractionation
section are incinerated, disposed of in deep wells or sent off-site
as solid waste.
Table AN-8 presents data for a typical plant (200 MM lbs./yr.
acrylonitrile production) burning all by-product acetonitrile (2,424
lbs./hr.), heavy ends (200 lbs./hr.) and half (2,119 lbs./hr.) of
the by-product HCN in a thermal incinerator. This incineration is
self-sufficient in heat and only requires supplemental fuel for pilots.
Data in Table AN-8 assumes acetonitrile is recovered as a concentrated
liquid in the product fractionation system. Normally, this chemical
is sent to deep well disposal, hence little effort is made to separate
it from water rejected in the product fractionation section. Under
these circumstances, the dilute stream will contain five to 10 percent
hydrocarbon.
In most cases, the by-product incinerator is designed to burn
dilute acetonitrile (Table AN-1, Stream 9) and the neutralizer waste
water stream. However, all plants surveyed normally send both of
these water streams to deep well disposal and only burn this material
during emergencies, such as injection pump failure (approximately
-------
Component
Hydrogen Cyanide
Acrylonitrile
Acetonitrile
Sulfuric Acid
Organic Polymers
Carbon Dioxide
Nitrogen
Oxygen
Water
Nitrogen Oxides
Total LBS./HR.
GPH
SCFM
AN-2 6
TABLE AN-8
THERMAL INCINERATOR
FOR
200 MM LB./YR. ACRYLONITRILE PUNT
BY-PRODUCT STREAMS (b)
OVERALL MATERIAL BALANCE, LB./HR.
Hydrocyanic
Acid
2,101
11
2,119
370
Acetonitrile
2,424
2,424
375
Heavy
Ends
50
150
200
23
Comb.
Air
36,517
11,087
629
48,233
10,600
Stack
Gas
9,154
38,425
2,111
3,160
125 (a)
52,976
11,500
Stack Gas
1800° F
Natural Gas
(Pilots)
Liquid Hydrocarbons
80 OF
(b)
1800° F
— Excess air (57,000 lbs./hr.) or
low pressure steam (34,000 lbs./
hr.) are used to limit operating
temperature to 1800° F.
Comb. Air
"80 °F
(a) Based on limited survey data.
(b) Consists of stream 11, half of stream 7 and acetonitrile from stream 9 of Table AN-1.
-------
AN-27
once a year). Deep veil disposal is more economical because of
the large amount of heat required to vaporize water and preheat
this additional material to combustion zone temperature (1600-
1800° F). If both waste water streams in addition to the Table
AN-8 hydrocarbon material are charged to the incinerator,
approximately 125 MM BTU/hr. of supplemental fuel is required.
Besides requiring more fuel, incinerating the neutralizer
effluent increases air emissions. Sulfuric acid is used by
virutally all plants for reactor effluent neutralization.
Therefore, the neutralizer waste water contains a substantial
amount of ammonium sulfate which produces sulfuric acid (about
0.0378 tons/ton of aerylonitrile production when using Catalyst
41) in the incinerator. For this reason neutralizer effluent
incineration is not desirable under any circumstances. Tankage
or ponds should be available to hold this particular reject stream
during emergencies.
Future water pollution regulations may prevent present normal
waste water dumping disposal methods. Under these circumstances,
steam produced in the absorber vent pollution control system
could be used to remove acetonitrile from the product fractionation
waste water reject by distillation. It is estimated that about
25,000 lbs./hr. of steam would be required to recover the by-product
acetonitrile shown in steam 9 of Table AN-1. The recovered stream
would contain about 20 wt. X water and could be burned in the
by-product incinerator without requiring any supplemental fuel.
The incinerator effluent could be used in a spray drier to evaporate
the neutralizer water reject stream for ammonium sulfate recovery.
The effluent NOx concentration shown in Table AN-8 is primarily
based on data provided by one aerylonitrile manufacturer (plant 51-1)
and is in agreement with published NOx yield figures (two percent of
theoretical)21. The only other surveyed plant (51-2) that has
analyzed this stream reports very low NOx production in the by-product
incineration. Insufficient data are available to determine exactly
how much NOx is produced. Based upon published data 2,3,4,21 and
other information 5, it is likely that a small portion of the
chemically bonded nitrogen contained in the feed is converted to
NOx. However, it is doubtful if NOx emissions would greatly exceed
Table AN-8 values in a properly designed commercial unit operating
at 1600-1800° F.
2. Other Combustion Devices
Obviously other types of combustion equipment, not presently
employed could be used to burn the by-products. However, most of
these would not have the flexibility to economically handle alternative
reject streams. For example, if a CO-boiler is used or a waste heat
boiler is added to an incinerator, this equipment would have to be
designed for maximum heat load. If the product fractionation waste
water stream is only sent to the facility on an intermittent basis,
economics would not favor providing this heat recovery equipment.
Assuming only the reject hydrocarbons are to be burned, catalytic
incineration would be more expensive to operate than a thermal unit.
However, if the dilute acetonitrile is to be a continuous feed,
operating cost would be less for a catalytic incinerator. This is
because the lower catalytic operating temperature (900-1200° F vs.
-------
AN-28
1800° F) results in lover supplemental fuel requirements. However,
before a catalytic unit could be recommended for this service,
performance data would be required to determine combustion efficiency
for this type of operation.
Plume burners represent a low capital investment combustion
device but are not recommended for burning the hydrocarbon reject
stream. Inefficient operating of this type of device could permit
large emissions of HCN to the atmosphere.
D. By-Product Storage Vent
In acrylonitrile plants where HCN is produced as a marketable
by-product, the HCN storage tanks are usually vented to a. flare.
This small vent stream is primarily nitrogen plus approximately
15 lbs./hour of HCN (for the typical 200 MM lbs/year aerylonitrile
plant).
None of the surveyed plants have attempted to analyze the
effluent from this flare. Combustion efficiency is probably similar
to that obatined with the product fractionation vent flare.
E. Best Pollution Control Systems
The most feasible method of reducing air emissions from
existing aerylonitrile plants would be to provide a thermal
incinerator on the absorber vent stream.
The best pollution control system for new units would include
a thermal incinerator plus a waste heat boiler on the absorber
vent. Product fractionation and HCN storage vent gas streams would
be flared and by-product hydrocarbons incinerated. If source
sampling indicates that by-product incineration in existing plants
does not produce significant NOx, it would be desirable to provide
a single incinerator for the absorber and by-product hydrocarbon
streams.
F. Industry Research Efforts
Current industry effort in air pollution control centers around
development of more selective catalysts which will reduce the
amount of by-products and increase utilization of ammonia.
-------
AN-2 9
V. National Emission Inventory
Based upon the emission factors shown in Table AN-3A, the total approximate
emissions from U. S. acrylonitrile plants are as follows (with Catalyst 21):
Component Average Emission Total Emissions
T/T of Acrylonitrile MM Lbs./Yr.
Hydrocarbons 0.1650 181.5
NOx 0.0050 5.5
CO 0.1779 195.7
0.3479 382.7
If Catalyst 41 were to completely replace Catalyst 21 on all current
plants, the.emission factors would become aB follows:
Component Average Emissions Total Emissions (k)
T/T of Acrylonitrile MM Lbs./Yr.
Hydrocarbons 0.1071 117.8
NOx 0.0050 (c) 5.5
CO 0.1222 134.4
0.2343 257.7
Since acrylonitrile production rate is fairly constant throughout the
year, there is no seasonal variation in total emissions.
The above data indicate that a reduction of about 30 percent in total air
emissions could be achieved by the use of the third generation catalyst. This
projection is based on data from a single plant.
(a) Weighted average based on individual plant emission factors and acrylonitrile
production.
(b) Based on 550,000 tonB/yr. total acrylonitrile production.
(c) Excludes NOx possibly formed in flaring product fractionation and HCN storage
tank vent streams. See Section VII.
-------
AN-30
VI. Ground Level Air Quality Determination
TableAN-3A presents a summary of air emissions data for the various
surveyed acrylonitrile plants. This table includes emissions from absorber
vent stream, flue gas from incineration of light and heavy end impurities
arid emissions from flare stack incineration or direct atmospheric venting
of non-condensable gases plus minor vapor streams from product fractionation
reflux drums, decanters and steam jet vacuum system. Information regarding
vapor losses from feed and product storage have not been included. Emissions
to the atmosphere from these storage facilities should be low for the
following reasons:
(a) Propylene feedstock and by-product HCN storage tanks include
refrigeration systems for vapor recovery. Any non-condensibles
are normally vented to the incinerator.
(b) Acrylonitrile product and by-product acetonitrile have relatively
low vapor pressure (3-5 psi) at normal storage tank operating
temperatures. These tanks usually contain conservation type vents
with vacuum breakers in order to minimize losses.
Table AN-3A provides operating conditions and physical dimensions of the
various vent stacks. The EPA may use this information together with the air
emission data to calculate ground level concentration for latter reporting.
The data of Table AN-3A were collected while the surveyed plants were
using Catalyst 21. One plant has changed (completely) to Catalyst 41 and
most of the other plants are in the process of a gradual changeover. Hence,
data modifications will probably be in order at the time when the EPA calculates
ground level concentrations.
-------
AN-31
VII. Cost Effectiveness of Controls
Table AN- 9 presents a cost analysis for the alternate methods of reducing
air pollution from the various vents. Economic data presented In this table
are for a new plant producing 200 MM lbs./yr» of acrylonltrlle and are based
on the following (using Catalyst 41):
A. Investment
Purchase cost of boilers was obtained from current vendor quotes
for similar packaged type units. Published data 2, were used to
determine incinerator costs and investment data provided in various
plant surveys were employed to estimate installed costs for plume
burners and flare stacks.
Installation costs for the various packaged units are estimated
values based on previous experience in plant construction. A major
portion of this cost represents construction labor.
B. Operating Expense
1. Depreciation - 10 year straight line.
2. Interest - 6% on total capital
3. Maintenance - Set at 47» of investment for boilers and 37<, for
incinerators. Maintenance costs for other control devices are
based on data provided in plant surveys.
4. Labor - One man per shift used for direct fired boilers and
6 hrs./day for waste heat boilers. Virtually no operating
labor is required for incinerators.
5. Utilities - Unit costs are based on typical values for the Gulf
Coast area. (1973)
Except for plume burners and flare stacks, all emission control
devices listed require induced or forced draft blowers. Power
requirements for these blowers are based on the following assumed
system differential pressures:
A P
in. H20
CO-Boiler 14
Thermal Incinerator 6
Thermal Incinerator plus
Waste Heat Boiler 14
In the case involving CO-boilers for absorber vent emissions control,
investment costs are based on providing a 1007. spare boiler. This provides a
more dependable steam supply.
Table AN-9 indicates that employing dual CO-boilers i6 not an economical
method of reducing emissions. However, if a stand-by boiler i6 not required, this
type of control device is about as economical to operate as other combustion devices
and represents one of the most efficient methods of reducing combustable emissions.
-------
Sircar:
Type of E~issioi". Control Device
:.'i:r.jer of I'nits
Capacity of Each Unit, 7.
K eetl
fotai Flow, Lbs./Hr.
SCFM
Composition, Tons/Ton AN
r:vd r oca rbons
Particulates
:;Ox
Carbon Monoxide
CQ-fioi1cr
100
TAf-LE AN-9
COSr EFFECT iVH'-'F.SS soR ALTERNATE
F.'•*; I S1 ('C<"•! RU!. Dr ( CKS
r-ASED o:: 2ov m: ifs.vk. achyli*:.iikile production
AbSOKBER VENT CAS
Thermal Incinerator
100
195,7 50
AS ,3 ;0
0.106
0.122
riicrmal Iiv: i ncrator
Sheet 1 ot 3
Waste Hear ;'-oi ler
103
iOJ
Flare System
100
Co-nbir.ed Ef f Luenc
Total Flow, Lbs,/Hr.
SCFM
Co-position, Tons/Ton AN
.--ydrocarbone
Par t icj lates
NO.-:
SON
Carbon Monoxide
Emissions Control Efficiency
CCR
SERR
InvestmentS
Purchased Cost
l:\stai iation
Total Capital.
Operating Cost, $/Yr.
Depreciation (10 years)
Interest on CaptLcal (6%)
Ma L nt enance
Labor. $4.85/Hr,
Ut i Lit ies
Power, lc/KWH
Fuel , 40c/m BTU
Boiler Feed Water, 30c/M. Gal.
Total Utilities
Total Operating Costs
Stearr. Production, 75c/M. Lbs. (450 PSIG,
750° F)
Total Annual Cost
4^0,742
100,550
0.0037
100
98
803,000
1 ,200,000
2,000,000
200,000
120,000
80,000 (4%)
39,600
497,100
36,200
533 ,300
972,900
(617.500)
355,400
304,444
G9,440
0.0031
100
.98
175,000
175 ,000
350,000
35 ,000'
21 ,000
10,500 (37.)
1 ,"D00
A ,300
64 ,100
68 .400
135,900
135,900
175,000
175,000
330,000
35 ,000
21,000
10,500 (370
1,000
4,300
64 , 100
65.400
135,900
135,900
304,444
69,440
0.0031
100
98
165,000
245,000
410,000
4 I ,003
24 ,600
16,400 (47c)
10,000
8,000
116,600
S .QjJ
100,000
(119.300)
(19,100)
, 60,000
0.0 11
0.002 5
0.012
90
89
150,000 (d>
15 ,000
9,000
8,000
•587,500
587 ,500
61.9,500
619,500
-------
Stream
Type of Emission Control Device
Number of Units
Capacity of each Unit,
Feed
Total Flov, LBS./HR.
SCFM
Composition, Tons/Ton AN
Hydrocarbons
Part leulates
NO
Carbon Monoxide
TABLE AN-9' CONTINUED
COST EFFECTIVENESS FOR ALTERNATE
¦EMISSION CONTROL DEVICES
BASED ON 200 MM LBS./YR. ACRYLONITRILE PRODUCTION"
Product Fractionation Vei-.i By-Product Disposal t°'
Fiare
1
100
423
70
0.004
Thermal Incinerator
1
100
4,743
0.1933
Sheet 2 of 3
HCN Storage Tank Vent (o)
Flare
1
100
110
25
0.0006
(e)
Combined Effluent
Total Flow. LBS./HR.
SCFM
Composition, Tons/Ton AN
Hydrocarbons
Particulates
N0X
S0X
Carbon Monoxide
Emissions Control Efficiency
CCR
SERR
Investment. S
Purchased Cost
Inst a 11 at i on
Total Capital
Operating Cost. S/Yr.
Depreciation (10 vears)
Interest on Capital (6
Maintenance
Labor, S4.85/Hr.
Utilities
Power, li/KT'H
Fuel, 40r/MM BIT
Boiler Feed V.'ater
Tota1 Ut i1i t ies
Total Operating Costs
Steam Production, 75' /M. LBS.
Total Annual Cost
(c)
30c/M.
600
0.0004
0.0014
90
72
CAL.
(450 PSIC,750° F)
75.000
7,500
4", 500
3,500
1.500
3,500
3.500
20,500
20,500 (ln)
52 976
11,500
0.005 (J)
100
99 (j)
175.000 110,000
175.000 110.000
350.000 (8.1)220.000 fbl
35,000 22.000
21,000 13,200
7,000 (2°/,) 4,400 (2'..)
3,300 3,300
2,400
2.000
2,400
2,000
"4.£00 ~7.40?
-------
AN-34
TABLE AN-9
COST EFFECTIVENESS FOR ALTERNATE
EMISSION CONTROL DEVICES
BASED ON 200 MM LBS./YR. ACRYLONITRILE PRODUCTION
FOOT NOTES Sheet 3 of 3
Based on vendor quote for similar unit.
Afterburner systems study by Shell Development Co. for EPA (Contract
EHSD 71-3).
It is likely that future fuel costs will be considerably higher than
used in this tabulation.
Based on investment data provided by carbon black manufacturers for
similar type of equipment.
See Appendix III for discussion and definition of efficiency as used
here.
Flow rates and utilities exclude waste water processing.
Excess capacity available for processing all waste water streams.
Excess capacity for product fractionation waste water disposal but
excludes capacity for neutralizer effluent.
To be confirmed by source testing.
Excludes utilities for burning waste water streams.
Excludes incinerator effluent scrubber
Based on cost data provided by acrylonitrile manufacturer's.
Based on use of Catalyst 41.
Based on use of either Catalyst 21 of 41.
-------
AN-35
Based on published information for burning fuels containing nitrogen, it
has been assumed that 50 percent of the chemically bonded nitrogen in the
CO-boiler feed goes to NOx with complete combustion of hydrocarbons and
CO.
A thermal incinerator with feed and air preheat followed.by a waste
heat boiler produces less steam for export but is more economical to operate
than the direct fired boiler which requires more fuel. It is assumed that
absorber vent gas emissions from this unit would be similar to those predicted
for CO-boilers.
Thermal incineration of the process vent gas without steam generation
has a somewhat higher operating cost than the unit including a waste heat
boiler. However, this device could be incorporated in existing or new
plants where steam can not be exported to other process areas.
Flaring of the absorber vent is impractical because of the large fuel
requirement.
It should be noted that economic data presented for the various
combustion devices are based on processing a typical absorber vent gas having
a heating value of 24 BTU/SCF. If for a particular feedstock (less propane),
air to hydrocarbon feed ratio, and catalyst (high selectivity), the vent gas
heating value is lower than this typical figuce, it would be necessary to
increase supplemental fuel usage in the combustion devices. For higher heating
value gases, less fuel and/or reduced feed-effluent heat exchange would be required.
Cost for installing the various absorber vent pollution control equipment
in existing plants would be about the same or only slightly higher than the
figures shown in Table AN-9. The actual cost differential would largely
depend on space availability and its location relative to associated process
equipment.
Table AN-9 includes economics for flaring the product fractionation and
HCN storage tank vents plus thermal incineration of the by-product acetonitrile,
heavy ends, and half the by-product HCN (see Table AN-8). The by-product
incineration data are based on limited emissions data provided by the
acrylonitrile manufacturers. However, if source testing indicate large
amounts of NOx production for this incineration, additional downstream processing
may be required.
By-product incinerator investments are shown for units sized to burn
reject liquid hydrocarbons plus part or all of the process waste water.
Incinerator utilities shown in Table AN-9 assume neither waste water stream
is being fed to the unit. It should be noted that it is not advisable to burn
the neutralizer effluent stream because of resulting air emissions. If this
stream is to be incinerated more often than just during short term emergencies,
it would be necessary to add a scrubber on the incinerator effluent. Cost of
this scrubbing facility has not been included in the economics.
Emission control efficiencies shown for flaring the product fractionation
and HCN storage tank vents are based on assuming 90 percent combustion of
combustibles with 50 percent conversion of chemically bonded nitrogen to NOx
(95 mol. % NO and 57„ NO2). Plant survey data in Table AN-3A fail to show
significant quantities of NOx in the flare effluents. It should be noted
that none of the surveyed plants actually analyze these streams. Therefore,
even though the total NOx emission based on the above assumptions is
-------
AN-36
significantLy higher than the reported values (0.0035 T/T of AN versus 0.00002
T/T for plant 51-4), there are no analytical data to indicate which of these
two values is a closer representation of the actual emissions.
Obviously, with tabulations such as presented in Table AN-9, the reader
can make a variety of adjustments to satisfy specific accounting techniques
or technical standards. Thus unit costs can be modified to be appropriate
to local situations or to account for future escalation, Similarly, different
combinations of equipment can be considered. For example, if only a single
CO-boiler were employed, the investment would drop to about $1,000,000 and
the annual operating cost would be reduced to $155,400 per year, assuming that
the reliability of steam export could assure the $617,500 estimated income.
-------
AN-37
VIII. Source Testing
It is recommended that source sampling should be performed on the
by-product incinerator feed and effluent streams at the 51-1 acrylonitrile
plant. This is the only surveyed plant vhich has sample taps available
for convenient effluent sampling. If possible, feed quantity and composition
should be varied in order to determine effect on N0X emissions.
Plant 51-1 does not send the neutralizer vaste water stream to
incineration. If combustion products from ammonium sulfate incineration are
to be determined, similar testing of either 51-2 or 51-3 incinerator vould be
necessary. If it is decided to source test the by-product incinerator in
either of these latter two plants, samples should be obtained vith and
vithout the neutralizer waste stream incineration.
It is also recommended that source sampling of the absorber vent stream
from plant 51-4 should be considered. This represents a fairly new plant
which shows average emissions. Since absorber emissions from the various units
do not vary over a wide range, it may be decided that source sampling of this
stream is not required.
-------
AN-3 8
IX. Industry Growth Projection
The U. S. annual acrylonitrile production is estimated to increase to
3.7 billion pounds by 1985, see Figure AN-2.
Approximately half of all acrylonitrile produced is ttsed in the
production of acrylic fibers. Demand in this area is expected to increase
about 12% per year during the next decade as synthetic fibers continue
to gain wider acceptance in wearing apparel and carpet manufacture.
The next largest use of acrylonitrile is in the production of plastics.
Plastic manufacture consumes about 157„ ,of U. S. acrylonitrile production and
the use of these acrylonitrile base resins is growing faster than that for
acrylic fibers. Increased utilization of plastics in automobiles could
greatly expand acrylonitrile requirements in this area.
Acrylonitrile is also used in production of oil resistant elastomers,
adiponitrile, acrylamide and other small volume chemicals.
Approximately 20% of U. S. acrylonitrile is exported. However, as more
larger foreign plants are built, these experts are expected to decline.
The projected increase in acrylonitrile production will require the
construction of approximately 13 new plants between 1972 and 1985, based on
an average plant capacity of 200 million pounds per year acrylonitrile
production. It is anticipated that most if not all of these plants will
incorporate the Sohio type of process. It is doubtful that a new more
economical process will be developed during this period.
About 45 percent of the cost of manufacturing acrylonitrile is due to
the cost of propylene feed. Therefore, acrylonitrile selling price is greatly
influenced by raw material availability. The cost of propylene in the U. S.
is expected to increase due to increased oil costs and as follows:
A. Increasing pressure to improve octane ratings of gasolines without
increasing lead content will probably mean increased consumption of
propylene for alkylate production.
B. Other chemicals such as isopropanol, propylene oxide, polypropylene
and cumene which are produced from propylene, represent fast growing
petrochemicals which mil compete for available feedstock.
C. Availability of refinery propylene is decreasing because of increased
use of hydrocrackers, which have low olefin yields, and by the use of
zeolite catalysts in cat crackers which result in lower propane and
propylene production.
D. By-product propylene production by U. S. ethylene plants is limited by
nature of the raw materials employed. Naphtha is generally unavailable
in the U. S. as a chemical feedstock because of the high demand for
gasoline. Naphtha feed yields considerably more propylene in an
ethylene unit than is obtained from propane or ethane feedstock.
Unless similar developments cause the same anticipated propylene
increase in Europe, U. S. propylene exports will terminate and may result in
some importation of acrylonitrile to meet future product demands. Anticipated
escalation in cost of other raw materials, particularly ammonia, may also
necessitate acrylonitrile price increases.
-------
AN-39
ffiqjRg: AW^
P^ODUCTjEON -
' ACRY jQN^TR[LB
ll
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-------
AN-40
X. Plant Inspection Procedures
Plant inspections will be conducted by the appropriate authorities, either
on a routine basis, or in response to a complaint. Usually the inspecting
agent will only be able to make visual observations. In some instance,
monitoring equipment may be available on the absorber vent or reactor effluent
It should be possible to sample the absorber vent stack through an accessible
sample point. This also applies to some of the by product incinerator stacks.
If the inspector has reason to suspect that emissions are excessive, some
factors that he should consider and/or discuss with plant officials are itemized
below:
A. Normally during start-up of individual reactors, the reactor effluent
is allowed to by-pass the neutralizer and absorber column and is
directly vented to the atmosphere. A record should be kept as to
when and for how long this by-passing occurs. Obviously, an
effort should be made to minimize this direct venting of catalyst
and reaction products. Process economics as well as air pollution
considerations dictate that safeguards should be taken to prevent
inadvertent opening of the by-pass valves. A discernible HCN odor
in the absorber off-gas could indicate a leaking by-pass valve.
B. Proper operation of the neutralizer and water absorber columns are
necessary to limit emissions in the absorber vent gas. This vent
stream should be essentially odorless and have the appearance of
steam with no residual plume. In addition to making these observations,
the control agent must be aware of operating and physical characteristics
of the neutralizer and absorber. The inspector should be aware that
excessive process vent gas emissions could be caused by:
1. Water flow rafres to both towers being less than design values.
2. Temperature and pressure of feed gas plus process side pressure
drop across the towers being different than normal plant operating
and design values.
3. Temperature profile in top section of absorber being higher than
design value. High temperatures which cause excessive carryover
of hydrocarbons can result from either inadequate cooling of the
absorption water or excessive tower feed.
C. Proper operation of the by-product incinerator is essential in limiting
air emissions. A visual check of the incinerator stack gas should be
made. A smoky stack Indicates malfunctioning of the combustion process.
Smoke-free combustion requires adequate time, good turbulence in mixing
the fuel and air, and sufficient temperature for the reaction to
proceed to completion and produce the desired products of oxidation.
If malfunctioning of the incinerator is suspected, log data on the
composition of stack gas should be reviewed, if available. Variance
in analytical results or general malfunction can usually be attributed
to one or more of the following factors:
1. Burner in combustion zone not in design operation.
2.
Process hydrocarbon waste feeds, atomizing steam and/or air valves
not open.
-------
AN-41
3. Combustion zone temperature not in design range.
4. The quantity of excess air may be different than design. This
might be determined by checking the air flow chart or measuring
the temperature of stack gases.
5. Variation in incinerator feed composition and flow rate.
The following measures are normally recommended by manufacturers as
methods to improve performance of a smoky incinerator.
1. Usually smoke results from low combustion zone temperature or
improper fuel to air ratio. If combustion zone temperature
is low, consider reducing the amount of excess air or increase
supplemental fuel. Variation in overall feed composition could
also result in low operating temperatures. For example, if the
feed contains a large quantity of water, the combustion temperature
could be quenched.
2. If operating temperature appears adequate and furnace still
smokes, it may be necessary to increase air rate to the
incinerator in order to insure complete combustion.
D. The above comments regarding the by-product incinerator also apply
to any incinerator provided on the absorber or other vent streams.
E. A visual check should be made of flare stacks to determine opacity.
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AN-4 2
XI. Financial Impact
All of the economic projections in this section are based on the use of
Table AN-1, Material Balance -with raw material requirements and absorber vent
gas composition revised to reflect the use of the latest catalyst (Catalyst
41).
Table AN-10 presents economics for acrylonitrile manufacture in a typical
200 MM Lbs./Yr. plant that incorporates incineration of all by-product HCN
and acetonitrile plus light and heavy ends from acrylonitrile fractionation.
Table AN-10 also presents economic data for the same unit assuming by-
product HCN and acetonitrile can be marketed at about 40 percent of the normal
selling price for these chemicals.
Table AN-10 shows that, based on 1973 cost/price levels, the manufacture
of acrylonitrile appears to be fairly profitable if by-products can be marketed.
About 8.5 percent return on investment is projected assuming no by-product value
and 14 percent ROI with the proposed by-product credit.
Table AN-11 shows estimated economics for producing acrylonitrile in an
existing plant modified to reduce emissions. The modification consists of
adding an incinerator for burning the absorber vent stream. Table AN-11 also
provides economics for producing acrylonitrile in a new most feasible unit.
This plant includes the same type of equipment employed in the modified existing
facility. In addition, a waste heat boiler is included on the absorber vent
gas incinerator effluent stream for steam generation.
The economic data indicate about a 0.06c/lb. increase in acrylonitrile
production cost for both the modified existing and new most feasible units.
Assuming an acrylonitrile selling price of 12
-------
AN-43
TABLE AN-10
ACRYLONITRILE MANUFACTURING COST
FOR A TYPICAL
EXISTING 200 MM LB./YR. FACILITY
DIRECT MANUFACTURING COST
Raw Materials
907o Propylene @ 2.8 c/lb.
Ammonia (3 L.5 c/lb.
Sulfuric Acid @ 1.5 c/lb.
Catalyst and Chemicals
Labor (8 men/shift@$4.85/hr.)
Maintenance (5% of investment)
Utilities
WITHOUT BY-PROD.
CREDIT!
C/LB.
3.99
0.74
0.06
0.50
0.17
0.60
0.90
6.96
$/YR.
WITH BY-PRODUCT
CREDIT
c/LB. $/YR.
6.96
INDIRECT MANUFACTURING COST
Plant Overhead (110% of labor)
FIXED MANUFACTURING COST
0.19
0.19
Depreciation (10 years)
Insurance & Property Taxes (2.3% of Inv.)
1.20
0.28
1.48
1.48
MANUFACTURING COST
8.63
8.63
GENERAL EXPENSES
Administration (37, of manufacturing cost)
Sales (17o of manufacturing cost)
Research (27. of manufacturing cost)
Finance (67. of investment)
Total Cost
PRODUCT VALUE
0.26
0.09
0.17
0.72
1.24
9.87
19,740,000
1.24
9.87
19,740,000
Acrylonitrile (3 L2c/lb.
HCN 0 4q/lb.
Acetonitrile (3 7c/lb.
Total
Profit before taxes
Profit after 527. tax
Cash flow
ROI (NPAT x 100/Investment)
12.00 24,000,000
12.00
0.69
0.69
2.13 4,260,000
1.02 2,045,000
4,445,000
8.52%
24,000,000
1,380,000
1,380.000
12.00 24,000,000 13.38 26,760,000
3.51 7,020,000
1.68 3,370,000
5,770,000
14.04%
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AN-44
TABLE AN-11
ACRYLONITRILE MANUFACTURING COST
FOR A TYPICAL
200 MM LB./YR. FACILITY
WITH ADDITIONAL EMISSION CONTROLS
Type of Plant
DIRECT MANUFACTURING COST
Modified
Existing Plant
C/LB. $/YR.
New ]
-------
TABLE AN-12
PRO-FORMA BALANCE SHEET
200 MM LB./YR. ACRYLONITRILE MANUFACTURING FACILITY
(NO CREDIT FOR BY-PRODUCTS)
EXISTING WITH NEW WITH INCINERATOR
TYPE OF PLANT EXISTING INCINERATOR AND WASTE HEAT BOILER
Current Assets
Cash (A)
Accounts Receivable (B)
Inventories (C)
$ 1,438,300
2,000,000
1,974,000
$ 1,448,300
2,000,000
1,988,000
$ 1,445,000
2,000,000
1,986,000
Fixed Assets
Plant 24,000,000 24,350,000 24,760,000
Buildings 100,000 100,000 100,000
Land 50.000 50.000 50.000
Total Assets $29,562,300 $29,936,300 $30,341,000
Current Liabilities (D) $ 1,278,300 $ 1,285,000 $ 1,278,300
Equity & Long Term Debt 28.284.000 28.651.300 29,062,700
Total Capital $29,562,300 $29,936,300 $30,341,000
(A) Based on one month's total manfacturing cost.
(B) Based on one month's sales.
(C) Based on 20 MM lbs. of product valued at total cost.
(D) Based on one month's total cost less fixed manufacturing and finance costs.
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AN-4 6
XII. Cost to Industry
In the typical present day plant depicted in Table AN-10, approximately
two percent of the plant investment is directly attributed to cost of air
pollution equipment. This expenditure plus associated operating costs equals
less than one percent of the aerylonitrile total production cost (0.05c/lb.).
The following items are included in this cost:
A. Flare for various product fractionation vent streams.
B. By-product incinerator.
C. HCN storage tank vent flare.
As noted in Section XI, the proposed most feasible modification of
existing aerylonitrile plants results in only a slight increase in production
cost (0.07
-------
Type of Pollution Control
Aerylonitri1e Production, Tons/Yr.
Po 1 lti t ant
Hydrocarbon
NOx
CO
TABLE AN-13
ESTIMATED 1985 AIR EMISSIONS
FOR
ALTERNATE CONTROL SYSTEMS.
(A)
Typical Present System
1,850,000
Average
Emissions
T/T
0. 1071
0.00b7
0. 1222
0.23 60
Total
Emissions
MM Lbs./Yr.
396.3
24.8
452.1-
873.2
Weighted
Emi ss ions
31,700
990
450
(D)
Most Feasible Modifications
New Plants
Existing Plants
550,000
33,140
(C)
Average
Emls6 ions
T/T
0.0005
0.0098
0.0103
1,300,000
Total
Emi s 8 ions
MM Lbs./Yr.
0.6
10.8
11.4
Average
Emissions
T/T
0.0005
0.0098
0.0103
Tot a!
Emissions
MM Lbs./Yr.
1.3
25.5
26.8
Average
Emiss ionB
T/T
0.0005
0.0098
0.0103
Tots 1
1,850,000
Total
Emissions
MM Lbs./Yr.
1.9
3b.3
38.2
Weighted
Emissions
150
1,450
1,600
(C)
(A) Based on all plants using Sohio Catalyst 41.
(B) Estimated production in 1985.
(C) SiKiificant Emission Index, which is based on the following weighting factors; Hydrocarbon = 80, NOx = 40 and CO = 1 (see Appendix II for explanation).
(D) Assumes ail existing plants modified and new plants built to incorporate thermal incinerators on absorber vent stream. New plants include a waste heat boiler.
-------
AN-48
XIII. Emission Control Deficiencies
Technical deficiencies which hinder reducing the level of emiBsions
include the following:
A. Process Chemistry and Kinetics
Production of aerylonitrile is a catalytic ammoxidation reaction.
The amount of aerylonitrile produced is influenced by relative con-
centration of feed components, reactor residence time, operating
temperature and pressure.
1. Reactor Feed
(a) Propylene
Impurities in the propylene feed vith less than four
carbon atoms are unaffected in the reactor and are primarily
rejected in the absorber off-gas. Heavier impurities react
forming undesirable by-products. Therefore, in order to
minimize air pollution and maximize productivity it is de-
sirable to limit impurities. Feed should also be sulfur free
in order to prevent catalyst deterioration.^
If an incinerator is provided on the absorber vent stream,
there is less incentive to limit ethane and lighter impurities
in the propylene feed. In addition to enhancing incinerator
operation without hurting production, lover purity propylene
could represent a cheaper feedstock,
Cb) Ammonia
Excess ammonia feed to the reactor is necessary to limit
formation of non-selective products (aldehydes, HCN and carbon
dioxide).15 In addition to improving aerylonitrile selectivity
this makes product recovery easier. Hov-ever, the excess ammonia
has to be neutralized prior to product recovery and this
neutralization normally produces an unvanted vaste product.
(c) Oxygen Concentration
All Sohio acrylonitrile plants use air as a source of oxygen.
This results in a large volume of nitrogen being vented vhich
dilutes other emissions. Because of this dilution, it is more
difficult and expensive to control the quantity of these emissions.
2. Reactor Operating Conditions
Reactor operating conditions influence propylene conversion
rate and to a certain extent the quantity of non-selective products
produced in the reactors. Since unconverted propylene is lost in
the absorber vent stream, reactor operating conditions are
adjusted to obtain high propylene conversion and maximum acrylp-
nitrile production.
3. Catalyst
The type of catalyst employed greatly influences the amount
of by-products produced and acryloritrile productivity. Even
-------
AN-4 9
vith the most selective catalyst currently employed, by-product
production exceeds market demand. This results in disposal
problems for these chemicals.
B. Process Equipment and Operations
1. Reactors
The chemical reaction for acrylonitrile production is
highly exothermic. Partly for this reason, fluidized reactors
vith internal cooling coils are emplpyed. This type of
reactor results in some catalyst carry over in the effluent
stream. Hovever, this catalyst (0.001 T'T of AN) is only
emitted to the.atmosphere during short time Deriods follo.ving
reactor start-ups vhen the neutralizer and absorber tower may
be by-passed.
2. Neutralizer
Sulfuric acid is used to neutralize excess ammonia. This
leads to a disposal problem for the resulting by-product
ammonium sulfate.
C. Control Equipment and Operations
The proposed incineration of the absorber vent gas, is the best
method of reducing air emissions from this stream. The deficiency in
this treatment is that it results in production of some N0X from nitrogen
compounds in the vent gas and consumes additional fuel.
There is some question as to hov much N0X is produced in the by-product
incinerator. If these emissions exceed air pollution limits, adjustment
in the incineration operation or additional treatment of the flue gas
for removal of contaminants would be required. See Section XIII-C of
Report No. EPA 450/3_-73-006a for a description of alternative treatment
methods.
-------
AN-50
XIV. Research and Development Needs
If the technology deficiencies discussed untfer Section XIII are to be
overcome, additional R & D is desirable in the following areas:
A. Existing Plants
1. Improved Catalyst
It would be desirable to have a more selective catalyst in order
to pro u e less unwanted by-products and improve utilization of
ammonia.
Published data for catalyst used in new Montecatini Edison
process shows less by-product HCN and acetonitrile yield for a
given acrylonitrile production than is obtained for the Sohio
catalysts.9,10 Since the type of reactor and its operating conditions
are similar for both processes, it should be possible to further
reduce these particular by-products in the Sohio process. Catalyst
development work in this area can best be handled by the process
licensor, as has been demonstrated by Sohio's past development of
Catalyst 21 and their recent work on Catalyst 41.
B. New Plants
In addition to the above R&D area which has appliation to
both new and existing plants, the following items would require new
facilities for utilization of -gained technology:.
1. Source of Oxygen
A combination of pure oxygen feed in place of air and recycle of
vent gas to. the reactors could reduce net emissions and improve feed
utilization. If the absorber vent gas is partially recycled, it is
not as critical to maintain high propylene conversion rates. Sohio
has worked in this area and believes that oxygen use results in a cost
stand-off, excluding potential emission control advantages.
If the use of pure oxygen substantially reduces the flow of gas
through the reactors, reactor design may have to be modified in order
to have adequate internal heat transfer surface and at the same time
maintain reactor mass flow velocity within a range necessary for
proper bed expansion.
2. Effluent Neutralization
Possibly, acetic acid may be used in place of sulfuric acid for
neutralizaing unconverted ammonia. The resulting ammonium acetate
could be heated for ammonia recovery. Besides reducing the net
ammonia consumption, this processing scheme eliminates production of
unwanted by-product ammonium sulfate. A literature reference to this
process modification exists.^ However, further development work on
this particular processing scheme is not justified until environ-
mental laws discourage present neutralizer waste disposal methods.
-------
AN-51
3. Utilization of By-Products
Commercially proven processes exist for converting HCN to
acrylonitrile (HCN + acetylene and HCN + ethylene oxide). Patent
literature also exists for making acrylonitrile from ethylene plus
HCN H and from acetonitr^le plus formaldehyde.1^ it is possible
that with process development and design work it may be found
economical to incorporate one or more of these processes in the
overall acrylonitrile plant as a method of eliminating net production
of by-product HCN and acetonitrile. It is also possible to recycle
HCN to the Sohio acrylonitrile reactors and thereby reduce if not
entirely eliminate net HCN production. 1*> These alternate processing
schemes would not only eliminate a possible source of pollution
from by-product incineration but also make better use of raw materials.
4. By-Prodpct Incineration
There remains a question ae to how much NOx is formed in the
by-product thermal incinerator. If source testing shows that
substantial amounts of N0X are formed, 15 & D work should be expended
in order to determine optinum incinerator operating conditions for
limiting N0X emissions. This study could also be expanded to determine
emissions from thermal incineration of the absorber vent stream.
5. Catalytic Incineration
It is possible that N0X ^missions from incineration of the absorber
off-gas and by-productB streams could be reduced by using a low
temperature catalytic incinerator. The homogenous oxidation of Nj
does not occur to any extent at 1200° F. Therefore, virtually no
NQX will be made from N2 in the f^ed and combustion air.
Inadequate experimental data is available on the catalytic oxidation
of organic nitrogen compounds. Fuel combustion studies indicate that
nitrogenous compounds are converged to NO; NO is the expected product
from decomposition of ring nitrogen compounds and the rate of catalytic
decomposition of NO is severely inhibited by the presence of oxygen.
However, simple thermodynamic arguments predict the rate of NO
formation from dissociated N and 0 atoms chemisorbed on the catalyst
surface to be low. Consequently additional direct experimental
evidence is needed to judge the N0X yield obtained on hydrocarbon
oxidation catalysts.
Textbook chemistry shows that; the hydrolysis reaction
RCN + 2 H20 RCOOH + NH3
goes to completion on acid catalysts at 800° F. Additionally, the
catalytic oxidation of NH3 occurs readily on Pt catalysts above
520° F. Thus there are easy catalytic routes to the unwanted NO.
For the above reasons, it is doubtful that catalytic incineration
would substantially reduce N0X emissions. However, experimental
data is needed on catalytic incineration of the absorber off-gas
and by-product streams to prove or disprove this supposition.
Since catalytic incineration has the following disadvantages,
-------
AN-5 2
(a) Higher operating costs than thermal incineration,
(b) Only moderate catalyst life with possible danger of catalyst
fouling and poisoning.
(c) Limited oxidation activity
any R&D work in this area should be delayed until after thermal
incineration has been proved to be an inadequate control device.
-------
AN-5 3
XV. Research and Development Programs
The following proposed programs are for projects within the general R&D
areas listed in Section XIV, These programs are limited to those R&D
projects which would have a good chance of success for obtaining methods of
reducing emissions from future acrylonitrile manufacture.
Project A
1. Title - Oxygen Feed plus Vent Gas Recycle for Reduced Emissions.
2. Object
To develop a modified acrylonitrile process using pure oxygen and vent
gas recycle to lower gas emissions.
3. Project Cost (see Table AN-14 for cost breakdown)
Capital Expenditures $ 125,000
Operating Costs
Total Manpower 130,300
Services 12,100
Materials 7,500
Contingency 47,100
Total § 322,000
4. Scope
On a laboratory scale, modify the Sohio acrylonitrile process by
replacing part or all of the air feed with pure oxygen and by
recycling absorber off-gas for dilution and improved utilization
of propylene feed. Successful completion of this project could lead
to a pilot plant demonstration utilizing the same pilot plant equipment
employed in this study.
5. Program
(a) Engineering
Process engineering effort is required to determine if thermo-
dynamic equilibrium favors recycle of vent gas as a method of
reducing net emissions.
(b) Design Construction and Checkout
This part of the project is concerned with the design, fabrication
and start-up of a laboratory scale unit. Since the Sohio acrylonitrile
process uses a fluid bed reactor, a reduction in the volume of gas
entering the system may have dramatic effects on conversion. For this
reason, the pilot plant reactor should be designed to allow as much
control as possible over temperature and residence time. In addition,
multiple reactor feed inlet nozzles should be provided.
(c) Feasibility Demonstration
This part of the program calls for operation of the unit in the
conventional manner: i.e. with air. This would give a base point
-------
AN-^54
TABLE AN-14
DETAILED COSTS
FOR
R&D PROJECT A
ENGINEERING
Process Design
Process Engineer, 2 Men - 8 Weeks (each)
Contingency
9,800
1,200
IT,000
DESIGN, CONSTRUCTION & CHECKOUT
Design Manpower: Professional - 16 Weeks
Major Equipment, Installed
Contingency
14,800
125,000
30,200
170,000
FEASIBILITY DEMONSTRATION
Operation
Manpower: Professional 4.0 Weeks
Technician - 2 Men/Shift, 3 Shifts/Day » 6 Weeks
Services: Analytical - 300 Hours
Materials
Contingency
3,700
25,800
4,400
2,500
4,600
41,000
PROCESS DEVELOPMENT
Operation
Manpower: Professional - 8.0 Weeks
Technician - 2 Men/Shift, 3 Shifts/Day - 16 Weeks
Services: Analytical - 500 Hours
Computational
Materials
Contingency
7,400
68,800
7,200
500
5,000
11,100
100,000
-------
AN-5 5
for subsequent work employing pure oxygen and recycle vent gas.
Measurements would be made for the activity and selectivity of the
process.
(d) Process Development
The process using oxygen would be developed with an attempt to
optimize the activity and selectivity of the process. Various
flow schemes could be attempted using recycled vent gases.
6; Timetable
Total time for project is estimated to be 13 months (excludes time
required for delivery and construction of pilot plant equipment).
Prpject B
1. Title - Additional Processing of By-Products.
2. Object.
To develop a modified acrylonitrile process which utilizes by-product
HCN and acetonitrile front th^ Sohio process fpr additional acrylonitrile
production.
3. Project Cost (see Table ANrl5 for cost breakdown)
Capital Expenditures $ 150,000
Operating Costs
Total Manpower 76,900
Services 7,700
Materials 5,000
Contingency 80,400
Total $ 320,000
4. Scope
This project ranges in scope from the economic analysis of various
processing schemes to the design, construction and operation of a
pilot unit.
5 j Program
Since technology already exists for processing HCN and acetonitrile to
acrylonitrile, all that is necessary is a process engineering design
study to evaluate various processing schemes. Upon completion of this
engineering study, it may be necessary to construct a pilot unit to
demonstrate opergbilj.ty and optimize operating conditions for fhe
proposed by-product processing. If commercially proven processes are
selected, pilot plant testing would not be required.
6. Timetable
Total time for project is estimated to be 16 months (excludes time
required for delivery and construction of pilot plant equipment).
If pilot plant work is not required project could be completed in about
6 months.
-------
AN-56
TABLE AN-15
DETAILED COSTS
FOR
R&D PROJECT B
ENGINEERING
Process Design and Economic Evaluation
Process Engineer, 2 men - 20 weeks (each)
Contingency
PILOT UNIT DESIGN CONSTRUCTION & CHECKOUT
Design Manpower: Professional - 16 weeks
Major Equipment, Installed
Contingency
PROCESS DEVELOPMENT
Operation
Manpower: Professional - 12 weeks
Technician - 2 men - 26 weeks
Services: Analytical - 5Q0 hours
Computational
Materials
Contingency
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AN-57
Project C
1. Title - Reduction of N0X from Combustion of By-Products.
2. Object
To outline the work required to develop a thermal combustion system
to minimize N0X emissions from the stack gases produced by combustion
of hydrocarbon by-products.
3. Project Cost (see Table AN-16 for cost breakdown)
Capital Expenditures $ 45,000
Operating Costs
Total Manpower 40,300
Services 4,200
Materials 2,900
Contingency 10,600
Total $103,000
4. Scope
Existing commercial furnace operation vould be considered initially.
Modified system designs would be explored in order to make further
significant reduction in N0X levels. Optimum operating conditions
must also be determined and the final results of this pilot in-
vestigation vould be projected to a commercial scale unit.
5. Program
(a) Preliminary
(1) Equipment selection and acquisition.
Pilot unit should be able to handle 5-10 lbs./hr. of
feed combustibles.
(2) Equipment installation and start-up.
Because of the high toxicity feed an outdoor site would
be employed and the incinerator stack gas should be
scrubbed.
(b) System Development
(1) Modelling
In view of the complexity of the system, a computer program
model would be prepared to predict optimum operating
conditions and to help point out the direction for changes
in design. Kinetic and stoichiometric data vould be
determined primarily for the combustion of HCN and acetonitrile.
(2) Investigation of existing commercial furnace operation.
A minimum of two furnace feed compositions vould be inves-
tigated : 1% and 50 wt. °L acetonitrile- in HCN.
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AN-58
(3) Investigation of new combustion systems.
An effort would be made to develop a system that would
result in low N0X emissions. A number of factors would be
explored to thermally reduce N0X emissions such as using
alternate firing and quenching stages, rapid quenching,
stack gas recirculation, low levels of excess air and
water injection.
(4) Refinement of operation for best design.
(c) Engineering Evaluation of a Projected Commercial Installation.
6. Timetable
Total time for this program is estimated to be about 10 months
(excludes time required for delivery of pilot plant equipment). It
is assumed the pilot unit would be operated on a one shift per day
basis.
7. Remarks
If during commercial plant source sampling or preliminary work on
this R&D project it becomes apparent that N0X production in by-
product incineration is not a problem, the R&D program should be
modified to include synthetic process absorber vent gas in the
incinerator feed. However, if by-product nitrogen compounds form
appreciable N0X, it would be desirable to make a separate study of
the process vent gas incineration. The R&D program and estimated
project cost for this study would be similar to those shown for the
above by-product incineration program.
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AN-5 9
TABLE AN-16
DETAILED COSTS
FOR
R&D PROJECT C Sheet L of 2
INITIAL COST
Capital Expenditure
Equipment and Instrumentation Acquisition & Installation
Manpower
Equipment Selection, Familiarization and Checkout
Professional (5 weeks)
Technician (3 weeks)
Contingency
RESEARCH & DEVELOPMENT PROGRAM
A. System Modelling
1. Operation for Kinetic & Stoichiometric Data
Manpower
Professional (2 weeks)
Technician (4 weeks)
Services
Analytical
Computational
Materials
2, Mathematical Modelling
Manpower
Professional (8 weeks)
Services
Computational
Report
Professional (1 week)
Contingency for items 1 & 2
B. System Development and Optimization
Total
Total
45,000
4,600
1,500
5,900
57,000
1,800
2,000
500
200
900
7,400
1,500
900
1,800
17,000
Manpower
Professional (12 weeks) 11,000
Technician (12 weeks) 6,100
Mechanical Craftsman (2 weeks) 700
Services
Analytical 1,000
Computational 1,000
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AN-60
TABLE AN-16 CONTINUED
DETAILED COSTS
FOR
R&D PROJECT C Sheet 2 of 2
Materials 2,000
Contingency 2,400
Total 24,200
C. Final Report
Professional (2 weeks) 1,800
Total 43,000
ENGINEERING
Economic Evaluation
Manpower
Process Engineer (3 weeks) 1,800
Mechanical Engineer (1 week) 700
Contingency 500
Total 3,000
-------
AN-61
XVI. Sampling, Monitoring and Analytical Methods for Pollutants in Air Emissions
A. Methods in Use
The principal sources of potential air contaminants from acrylonitrile
production are the product absorber and by-product incinerator stacks.
All plants surveyed analyzed the absorber gases at fairly frequent intervals,
while two of the four have analyzed the incinerator gases at some time in
the past. Depending on the recovery process, each plant has at least one
flare and in some cases other minor sources of atmospheric emissions. None
of the minor sources were sampled although calculated emissions vere
submitted in several cases.
1. Absorber Vent Gases
As may be seen in Table AN-17, the information received concerning
analytical methods was not very specific. However, all four operating
plants surveyed used the multi-column gas chromatograph for separation
of organic constituents of the absorber vent gas, and in one case for
separation of oxygen, carbon dioxide, carbon monoxide and propane,
Three plants scrub the stack gases with water or hydrochloric acid to
remove HCN for silver nitrate titration. One plant determines CC>2 and
CO by infrared analysis.
One analytical method based on an automatic sampling and mass
spectrometer analysis system was found 18, The spectrometer output
was computer analyzed to obtain a quantitative analysis of 14
compounds in a 24 minute period. The system was applied to reactor
effluent gases, but probably is applicable to absorber vent gases
as well. The plant using this technique has recently been closed, but
the analytical procedures remain of interest.
In all cases, plant personnel expressed a high degree of confidence
in the analytical results. Although specific details are lacking in
the test procedures, the basic analytical principles employed are
sound and the impression was gained that the methodology is highly
developed. It appears that the emission data obtained should probably
be regarded as sound and that independent development of sampling and
analytical methods is not warranted at the present time.
2. Incineration Exhaust Gases
Only two plants performed analyses for incinerator exhaust
components. Of the analytical techniques used, the EPA method 7 for
N0X and Shell Development method for SO2 are adequately described by
reference, but the others are essentially unknown. However, there
appears to be no reason why EPA methods for N0X and SO2 could not be
combined with absorber vent GC methods to obtain complete and accurate
data.
B. Future Methods Development
The analytical methods available for absorber vent and incinerator
exhausts are probably adeauate, but vary widely from plant to plant.
It would appear advantageous to obtain specific details of the
techniques in use and to promote greater uniformity in the industry.
An analytical package suitable for both major and minor sources at
-------
AN-62
acrylonitrile plants vould probably consist of multiple column GC
for the analysis of organics and combustion gases, supplemented
with EPA methods for SO2 and N0X analysis.
-------
AN-63
Source
TABLE AN-17
SUMMARY OF
SAMPLING AND ANALYTICAL METHODS
FOR POLLUTANTS
Plant
Material
Sheet 1 of 2
Method
Absorber Vent
51-1
51-2
Various Components
HCN
Analytical methods believed
to be the same as those
listed for plant 51-2.
Scrubber follov^d by silver
nitrate titration using a
modified Liebig-Deniges
reaction.
51-3
Aerylonitrile &
Acetonitrile
02» CO2, CO, C^Hg
Acrylonitrile
GLC using a. 2 meter x V
copper column containing
25 gms of 35% peg 200 on
one part 80 - 100 mesh
chromosorb P and 4 parts
40 - 60 mesh chromosorb P.
Double column GC vith (1)
6 ft. of V tubing containing
30% HMPA on 60 - 80 mesh
chromosorb P, and (2) 12 ft.
of V' tubing containing 13x
molecular sieve plus 60 r 80
mesh column packing.
Water scrubber-analysis
unknovn.
CH4i C H,, C2H4,
C2h8
Flame ionization GC using
one column containing
Perkin Elmer type S
sorbent.
51-4
CO, co2
HCN, NH3
Infrared.
Hydrochloric acid scriibber.
Titrate NH3 vith 0.3 N sodium
hydroxide. Titrate HCN vith
0.001 N silver nitrate.
Incinerator Exhaust
51-1
51-2
Organics
HCN, NH3
N0y
o2, co2>
NO„
CO, N„
SO--
Double column GC.
Draeger tubes.
EPA method 7 . ^
See plant 51-2 absorber vent.
Measured, but method unknovn.
19
Shell method.
-------
AN-64
TABLE AN-17 CONTINUED
SUMMARY OF
SAMPLING AND ANALYTICAL METHODS
FOR POLLUTANTS Sheet 2 of 2
Source Plant Material Me thod
Incinerator Exhaust 51-2 Organics Method unknovn.
51-3 None-
51-4
None
-------
AN-65
XVII. Emergency Action Plan (EAP) For Air Pollution Episodes
A. Types of Episodes
The alleviation of Air Pollution Episodes as suggested by the
U.S. Environmental Protection Agency is based on a pre-planned episode
emission reduction scheme. The criteria that set this scheme into
motion are:
1. Alert Status - The alert level is that concentration of
pollutants at which short-term health effects can be expected
to occur.
2. Warning Status - The warning level indicates that air quality
is continuing to deteriorate and that additional abatement
actions are necessary.
3. Emergency Status - The emergency level is that level at which a
substantial endangerment to human health can be expected. These
criteria are absolute in the sense that they represent a level
of pollution that must not be allowed to occur.
B. Sources of Emission
As outlined in the foregoing in-depth study of aerylonitrile
manufacture, there are usually four continuous and two intermittent
vent streams to the atmosphere.
1. Continuous Streams
(a) Absorber Vent Gas - This stream represents the primary potential
air emission in the Sohio acrylonitrile process and consists
of the gross reactor effluent after neutralization and
recovery of nitriles and HCN. Under normal conditions, the
quantity of absorber vent hydrocarbon emissions (excluding
propane and propylene) are primarily influenced by the
amount of air charged to the reactors. Air rates are
usually held constant to maintain catalyst fluidization.
Several plants currently have plans to install an incinerator
or catalytic device to control emissions in this vent stream.
Where this is done, it should in most cases diminish the
need to take emergency action during air pollution episodes.
(b) Product Fractionation Vent - This vent represents a combination
of several small streams, which vary greatly in composition
depending upon type of fractionation system used for product
recovery. This material is usually sent to an incinerator
or flare which reduces organic emissions.
(c) Product Storage Vent - The product storage atmospheric vent
is small due to the low vapor pressure of acrylonitrile and
acetonitrile. Vent material from HCN storage is burned- for
control of organic emissions.
(d) By Product Incineration - The second most voluminous air
emission is represneted by the by-product incinerator flue
gas. The normal emissions are the products of combustion
-------
AN-bb
plus small amounts of NQx derived from burning organics
having nitrogen in their structure. The flow characteristics
are in. some instances intermittent as indicated in Table
AN-3A. Presently, portions of the unwanted waste by-products
are diverted to deep well disposal.
2. Intermittent Air Emissions
(a) Process Vent Gas - During reactor start-up, the reactor
effluent stream exhausts directly to the atmosphere. This
occurs during heat up, the ammonia burn phase and for a
short period following the introduction of proyplene into
the reactor. The heat up is accomplished by heating air with
natural gas and consequently, the only emissions during
this period are the products of combustion. Following
the introduction of ammonia, fhe oxygen content of the
reactor effluent is allowed to drop to a low level before
propylene is admitted. Daring the ammonia burn phase, most
of the ammonia reacts with oxygen to form nitrogen and water
vapor. After introducing propylene feed, the reactor
effluent strean is routed into the neutralizer and absorber
system. Reportedly, the complete reactor start-up sequence
is completed in about one hour. However, the most significant
contaminants emitted during this period are propylene and
acrylonitrile which are emitted for periods of five to 20
minutes before the reactor effluent is routed to the quench
and recovery system.
This start-up procedure is applicable whether for one reactor
of a battery, with the other reactors operating, or for the
start-up of all reactors in a multi reactor plant. However,
the usual practice in the latter instance is to place only
one reactor into service, at any one time.
(b) Emergency Relief - During plant up-set or other emergencies,
the following streams are controlled by routing them to the
flare or by-product incinerator:
(1) Propylene Sotrage - Relief valves in this service are
routed to the flare.
(2) Propylene Feed - This is vented to the flare if the
source of heat for vaporization is lost and the vaporizer
freezes up. In addition, propylene vaporizers are vented
to the flare during scheduled plant shutdowns.
(3) By-Product HCN - This is usually sent to an incinerator
unless it is marketed. An upset in the fractionation
systems could result in it being diverted to incineration.
C. Abatement Techniques
As the various levels of the pre-planned episode emission reduction
scheme are declared (Alert, Warning and Emergency) a progressive reduction
in the amount of air pollutants must .be made. This could ultimately lead
to total curtailment of pollutant emissions if the emergency level becomes
imminent. The extent of required cutback in emissions from acrylonitrile
-------
AN-6 7
plants will depend on the relative amount of offending constituents
contributed by acrylonitrile production to the overall emissions which
resulted in the pollution episode. This plus other factors will be
used by control authorities in determining the amount of emissions to
be tolerated during various episodes. The degree of emission
curtailment should recognize plant size and location and should also
be dependent upon the extent of air contaminant emission controls
employed by the specific plants.
To obtain a partial reduction inair pollutant emissions, several
options are available to the acrylonitrile plant operator. Acrylonitrile
manufacturing facilities generally consist of single or multiple reactor
systems, with each system or plant containing separate product recovery
equipment. A multiple reactor, system provides for increased flexibility
to affect a partial reduction in air pollutant emissions during an
air pollution alert. This is possible since individual reactors can
be removed from service resulting in a reduction of total absorber
vent gas. emissions. The reactors removed, from service can either be
maintained in standby condition (by holding reactor temperature at
800° F) or taken off line and allowed to cool.
If a single reactor system must be taken off line and cooled to
near ambient conditions, it wilL require a minimum of 24 hours to heat
up the system and conduct a normal start-up. Time requirements for
start-up of single reactor systems and multiple reactor systems vary
depending on the availability of utilities (steam).
Problems which could arise in the event an episode might dictate a
complete shutdown in winter during sub-freezing temperatures. The
acrylonitrile plant uses large amounts of water circulation for product
recovery. If these circulation systems or the steam generation system
freeze, a start-up might require weeks.
A single reactor system can be taken out of service in two-three
hours if it is maintained in standby condition. To resume production
from this point would normally require two to four hours. A reactor
start-up requires additional utilities and personnel. The availability
of these might increase the time requirement by up to six hours.
Reactor "turndown" or reduction in reactant feed will proportionally
reduce the emission of unreacted hydrocarbons and carbon oxides in the
absorber vent gas. Emission to the atmosphere of the desired reaction
products would also normally be reduced. The latter reduction will
be a function of throughput and efficiency of the absorber system.
Absorber efficiency is dependent onlow temperature operation. The
absorber system is subject to fouling by polymers and tars. Therefore-,
periodic cleaning of exchange surfaces is required to maintain good
heat transfer and efficient operation. It has been reported by plant
51-2 that a turndown to 60 percent of maximum rate is possible. In an
emergency, this turndown can be accomplished in one hour.
It should be noted that reactor turndown will proportionally
decrease steam production. This reduction may adversely influence the
operation of other process units which depend on this source of steam.
This would require adjustments in the steam system which might require
shutdown or curtail operation of units not directly related to the
pollution episode.
-------
AN-68
Declaration of Alert Condition - When an alert condition is
declared the episode emission reduction plan is immediately set
into motion. Under this plan, in addition to notifying the
manufacturer of the alert condition, it may be deemed necessary
to reduce emissions from aerylonitrile manufacture somewhat to
conform in the overall reduction plan set forth by the
Environmental Protection authorities. This can be accomplished
by a reduction in acrylonitrile production which will reduce
the principal source of emissions represented by the absorber
vent.
During an alert condition it should be possible to reduce
emissions resulting from by-product incineration. Production
of by-products would be reduced if a cutback is made in
acrylonitrile production. In some plants, by-products are
presently burned on an intermittent basis. In these and.other
plants it should be possible to curtail this incineration during
an episode provided adequate by-products storage facilities or
an alternative method of disposal (deep well injection) is
available. The other sources of atmospheric emissions (product
fractionation vent and product storage vent) are more difficult
to control and, since they are minor quantities, no attempt
other than employing maximum cooling of tower overhead streams
is suggested for their reduction. The time required to effect
reductions will be from one to three hours. Usually the alert
condition can be expected to continue for 12 hours or more.
Declaration of Warning Condition - If an air pollution warning
episode is announced, a substantial reduction of air contaminants
is desirable even to the point of assuming reasonable economic
hardships in the cutback of production and allied operations.
This could involve a 50 to 60 percent decrease in acrylonitrile
production which would reduce the principal source of emission
represented by the absorber vent gas by a value approximately
equivalent to the reduction made in plant capacity. The emissions
from the product fractionation and stroage vents may decrease
to some degree by virtue of reduced acrylonitrile production.
Emergency Condition - When it appears that an air pollution
emergency is imminent, all air contaminants may have to be
eliminated by ceasing or curtailing production and allied
operations to the extent possible without causing injury to
persons or damage to equipment.
The cessation of reactor operation whether wholly or in part will
not result in increased emissions. Pn the other hand, during the
subsequent plant start-up, there is an increase in atmospheric
emissions for one hour or less. This results from the requirement
of direct atmospheric venting of reactors during start-up. On
the average,.hydrocarbon emissions during this period will be
three to seven times the normal on-stream value. This hydrocarbon,
which is primarily acrylonitrile, represents about 10 wt. percent
of the total vent stream. Because of the large quantity of
combustibles and variation in composition, it is unlikely that
all of this stream could be sent to the by-product or absorber
vent gas incinerators wihtout posing temperature control problems.
-------
AN-69
Therefore, in most instances, the partial reduction in air
emissions during an alert episode may best be accomplished
by a turndown in plant capacity. It should be noted that
in plants that incorporate absorber vent gas incineration
with steam generation, it may be necessary to use additional
supplemental fuel during plant turndown operation in order
to produce sufficient steam for other process units which are
dependent on this steam generator.
D. Economic Considerations
The economic impact on the manufacturer of curtailing operations
during any of the air pollution episodes is based on the duration and
number of episodes in a given period. It is indicated that the
normal duration of air pollution episodes that occur in various areas
of Eastern U.S. is usually from one to seven days with meteorology
episode potentials as high as 80 per year.22 The frequency of air
pollution episodes in any given area is indicated as being one to
four per year. These data do not differentiate between the episode
levels set forth in the early paragraphs of this.section. Normally
since the alert level does not require a cutback in production, it will
not influence plant economics. Therefore, in discussing economic
considerations resulting from the air pollution abatement plan, it
is only necessary to estimate the frequency and number of warning and
emergency episodes. For the economic study, it has been assumed that
three warning and no emergency episodes occur per year. Each warning
episode is assumed to require a 50 percent reduction in air contaminants
for a period of five and one half days. This then equates to a complete
loss in plant production for about eight and one half days per year.
The relative finanaical impact resulting from this loss in production
is shown in Table AN-18. This table contains comparative manufacturing
costs for an existing 200 MM lbs./year facility without extensive
pollution control (Table AN-10) and for a most feasible new facility
of the same capacity (Table AN-ll), Economics are shown for each of
these plants with and without the financial impact accredited to the
air pollution episodes. It should be noted that whereas the assumed
cutback in aerylonitrile production for emission control appears small
(2.5 percent on a yearly basis), it reduces net profit by about seven
percent.
E. Summary of Estimated Emissions
In the foregoing a reduction in air pollutant emissions was suggested
for the various air pollution levels that may be encountered. This was
predicated on existing plants which do not employ combustion devices on
the absorber vent stream. Special consideration should be made in the
EAF for Air Pollution Episode Avoidance for new and existing plants that
do employ this incineration.
The following tabulation presents estimated air emissions for a
typical present-day system without incineration and the most feasible
new plant with this type of control.
-------
AN-70
Pollutant
Typical Present System
Average Emissions,
Tons/Ton
Most Feasible New Plant
Average Emissions,
Tons/Ton
Hydrocarbon
0.1071
0.0005
NOx
0.0067
0.0098
CO
0.1222
Total Emissions
0.2360
0.0103
As noted in the above, total emissions for the most feasible new
plant has been reduced to less than five percent of that estimated for
the typical present system without absorber vent gas incineration.
However, emissions of NOx would increase by about 50 percent over
that projected for the plant not employing an incinerator.
The particular type and concentration of pollutants in the atmosphere
at the time of the episode would dictate the degree to which a reduction
would be made on the most feasible new plant. If NOx is the offending
material, then a reduction in plant production should be made as
outlined under "Declaration of Warning Condition". In this case NOx
emissions would be reduced in proportion to the reduction of aerylonitrile
production.
If the alert is called on the basis of excess hydrocarbons or CO
concentration in the ambient air, less severe cutbacks in production
need to be taken. This is especially true if incinerators are employed
for pollution control.
The primary contaminants emitted from this process are hydrocarbons,
CO and to a lesser extent, NOx. Therefore, if an alert is called on the
basis of SO2 or particulates, curtailing the aerylonitrile operation
should not be necessary.
-------
TABLE AN-18
FINANCIAL IMPACT OF AIK POLLUTION EPISODES
FOR 200 MM LBS.
ON MANUFACTURING COSTS (a)
/YEAR ACRYLONITRILE MANUFACTURING
FACILITY
(No Credit For By-Products)
Sheet 1 of 2
TYPICAL EXISTING PLANT
MOST FEASIBLE
NEW PLANT (b)
Type of Operation
No Cutback In
Production
(Table AN-10)
Assuming
8.5 Days Lost
Production
No Cutback In
Production
(Table AN-11)
Assuming
8.5 Days Lost
Production
Direct Manufacturing Cost, $/Yr.
Raw Materials
90% Propylene 8 2.8f/Lb.
Ammonia <4 1.5
-------
TA1JLE AN-lb
PAGE 2
CONTINUED -
Sheet 2 of 2
TYPICAL EXISTING PLANT
MOST FEASIBLE NEW PLANT (b)
Type of Operation
No Cutback In
Production
(Table AN-10)
Assuming
8.5 Days Lost
Production
No Cutback In Assuming
Production 8.5 Days Lost
(Table AN-11) Production
Total Manufacturing Cost, $/Yr.
General Expenses, $/Yr.
Administration, Sales, Research
and Financial
17,260,000
2,480,000
16,964,000
2,480,000
17,340,000
2,520,000
17,045,000
2,520,000
Total Cost, $/Yr.
Selling Price (Acrylonitrile 6 12*/Lb.) 24,000,000 23,400,000 24,000,000 23,400,000
Profit Before Taxes 4,260,000 3,956,000 4,140,000 3,835,000
Profit After 52% Tax 2,045,000 1,899,000 1,987,000 1,841,000
Cash Flow 4,445,000 4,299,000 4,463,000 4,317,000
R01 (NPAT X 100/Investment) 8.52% 7.91% 8.03% 7.44%
(a) Designed to show only relative effect,
(b) Includes a thermal incinerator plus waste heat boiler on the absorber vent stream.
-------
AN-73
References
1. Stobaugh, R. B. et al. "Acrylonitrile" How, "Where, Who - Future,11
Hydrocarbon Processing, Vol. 50, 109-120, January, 1971.
2. RoLke, R. W. et al. "Afterburner Systems Study", by Shell Development
Company for Environmental Protection Agency (Contract EHS-D 71-3),
3. Iya, K. Sridhar, "Reduce N0X in Stack Gases," Hydrocarbon Processing,
page 164, November, 1972.
4. "Control Techniques for Nitrogen Oxide Emissions from Stationary Sources,'.'
National Air Pollution Control Administration Publication No. AP-67,
page 4-1.
5. Private Communications regarding thermal and catalytic incinerator thesis
work currently in progress at Delaware University.
6. "Acrylonitrile Chemical Profile", Chemical Marketing Reporter, August 9, 1971
7. "Chemical Economics Handbook,1' Stanford Research Institute, December, 1969.
8. "Air Pollution Survey Production of Seven Petrochemicals," MSA Research
Corporation for Environmental Protection Agency (Contract No. EHSD 71-12,
Mod. I, Task I), July 23, 1971.
9. Heath, Andrew, "Improved Catalyst Boosts Acrylonitrile Route," Chemical
Engineering, page 80, March 20, 1972.
10. Caporali, Giorgia, "How Montedison Makes Acrylo," Hydrocarbqn processing,
page 144, November, 1972.
11. TJ. S. Patent 2,386,586 (1945), J. H. Rrant and R. L Hasche (to Eastman
Kodak Co.).
12. U. S. Patent 2,445,693 (1948), I. Porter and G. A. Nesty (to Allied
Chemical).
13. Dunn, B. E., "Acrylonitrile Process Analyzer System," papar presented
at the 27th Annual Conference of the Insturment Society of America,
New York, October, 1972.
14. Sittig, Marshall, "Acrylonitrile", Chemical Process Monograph No, 14,
Noyes Development Corporation, Park Ridge, N. J., 1965.
15. Dalin, M. A. et al., "Acrylonitrile", Technomic Publishing Co. Inc.,
Westport, Conn., 1971.
16. U. S. Patent 3,050,546 (August, 1962), E. C. Milberger (to Standard Oil
Co. of Ohio).
17. French Patent 1,336,342 (1963), (Societe d'Electro-Chimie, d'Electro-
Metallurgie et des Acieries Electriques d'Ugine).
-------
AN-74
References (Continued)
18. Dunn, B. E., "Acrylonitrile Process Analyzer System", Proceedings of the
27th Annual Conference of the Instrument Society of America, October, 1972.
19. "Atmospheric Emissions from Sulfuric Acid Manufacturing Processes" Public
Health Service Publication, No. 999-AP-13, 1965.
20. "Standards of Performance for Nev Stationary Sources", Federal Register,
Vol. 36, No. 247, 24876-24895, December 23, 1971,
21. Walker, H. M., "NOx Formation During the Incineration of Nitrogenous
Residues", paper presented at 74th National Meeting of AICHE, New Orleans,
Louisiana, March 12, 1973.
22. "Guide for Air Pollution Episode Avoidance Environmental Protection
Agency, Office of Air Programs, Publication No. AP-76, June, L971.
-------
APPENDIX I
BASIS OF THE STUDY
I. Industry Survey
The study which led to this document was undertaken to obtain information
about selected production processes that are practiced in the Petrochemical
Industry. The objective of the study was to provide data for the EPA to use
in the fulfillment of their obligations under the Clean Air Amendments of 1970.
The information obtained during the study includes industry descriptions,
air emission control problems, sources of air emissions, statistics on quantities
and types of emissions and descriptions of emission control devices currently
in use. The principal source for these data waB an Industry Questionnaire
but it was supplemented by plant visits, literature searches, in-house back-
ground knowledge and direct support from the Manufacturing Chemists Association.
More than 200 petrochemicals are currently produced in the United States,
and many of these by two or more different processes. It was obvious that
the most immediate need was to study the largest tonnage, fastest growth
processes that produce the most pollution. Consequently, the following 32
chemicals (as produced by a total of 41 different processes) were selected
for study:
Acetaldehyde (two processes)
Acetic Acid (three processes)
Acetic Anhydride
Acrylonitrile
Adipic Acid
Adiponitrile (two processes)
Carbon Black
Carbon Disulfide
Cyclohexanone
Ethylene
Ethylene Dichloride (two processes)
Ethylene Oxide (two processes)
Formaldehyde (two processes)
Glycerol
Hydrogen Cyanide
Maleic Anhydride
Nylon 6
Nylon 6,6
"Oxo" Alcohols and Aldehydes
Phenol
Phthalic Anhydride (two processes)
Polyethylene (high density)
Polyethylene (low density)
Polypropylene
Polystyrene
Polyvinyl Chloride
Styrene
Styrene - Butadiene^Rubber
Terephthalic Acid (1)
Toluene Di-isocyanate (2)
Vinyl Acetate (two processes)
Vinyl Chloride
(1) Includes dimethyl terephthalate.
(2) Includes methylenediphenyl and polymethylene polyphenyl isocyanatea.
The Industry Questionnaire, which was used as the main source of information,
was the result of cooperative efforts between the EPA, Air Products and the
EPA's Industry Advisory Committee. After receiving approval from the Office of
Management and Budget, the questionnaire was sent to selected producers of
most of the chemicals listed above. The data obtained from the returned
questionnaires formed the basis for what have been named "Survey Reports".
These have been separately published in four volumes, numbered EPA-450/3-73-005a,
b, c, and d and entitled "Survey Reports on Atmospheric Emissions from the
Petrochemical Industry - Volumes I, II, III, and IV.
-------
1-2
The purpose of the survey reports was to screen the various petrochemical
processes into the "more" and "less - significantly polluting processes".
Obviously, significance of pollution is a term which is difficult if not
impossible to define because value judgements are involved. Recognizing this
difficulty, a quantitative method for Significant Emission Index (SEI) was
developed. This procedure is discussed and illustrated in Appendix II of
this report. Each survey report includes the calculation of an SEI for the
petrochemical that is the subject of the report. These SEI's have been
incorporated into the Emission Summary Table that constitutes part of this
Appendix (Table I). This table can be used as an aid when establishing
priorities in the work required to set standards for emission controls on
new stationary sources of air pollution in accordance with the terms of the
Clean Air Amendments of 1970.
The completed survey reports constitute a preliminary data bank on each
of the processes studied. In addition to the SEI calculation, each report
includes a general introductory discussion of the process, a process description
(including chemical reactions), a simplified process flow diagram, as well as
heat and material balances. More pertinent to the air pollution study, each
report lists and discusses the sources of air emissions (including odors and
fugitive emissions) and the types of air pollution control equipment employed.
In tabular form, each reports summarizes the emission data (amount, composition,
temperature, and frequency); the sampling and analytical techniques; stack
numbers and dimensions; and emission control device data (types, sizes, capital
and operating costs, and efficiencies).
Calculation of efficiency on a pollution control device is not necessarily
a simple and straight-forward procedure. Consequently, two rating techniques
were developed for each type of device, as follows:
1. For flares, incinerators, and boilers a Completeness of Combustion Rating
(CCR) and Significance of Emission Reduction Rating (SERR) were used.
2. For scrubbers and dust removal equipment, a Specific Pollutant
Efficiency (SE) and a SERR were used.
The bases for these ratings and example calculations are included in
Appendix III of this report.
II. In-Depth Studies
The original performance concept was to select a number of petrochemical
processes as "significant polluters", on the basis of data contained in
completed questionnaires. These processes were then to be studied ''in-depth".
However, the overall time schedule was such that the EPA requested an initial
selection of three processes on the basis that they would probably turn out
to be "significant polluters". The processes selected in this manner were:
1. The Furnace Process for producing Carbon Black.
2. The Sohio Process for producing Acrylonitrile.
3. The Oxychlorination Process for producing 1,2 Dichloroethane
(Ethylene Dichloride) from Ethylene.
-------
TABLE I
EMISSIONS SUMMARY
Page 1 of 3
ESTIMATED CURRENT
AIR EMISSIONS,
MM LBS./YEAR
Hydrocarbons
Particulates
Oxides of Nitrogen
Sulfur Oxides
Carbon Monoxide
Total
Total Vele
Acetaldehyde via Ethylene
1.1
0
0
0
0
1.1
86
via Ethanol
0
0
0
0
27
27
27
Acetic Acid via Methanol
0
0
0.01
0
0
0.01
1
via Butane
40
0
0.04
0
14
54
3,215
via Acetaldehyde
6. 1
0
0
0
1.3
7.4
490
Acetic Anhydride via Acetic Acid
3.1
0
0
0
5.5
8.6
253
Acrylonitrile (9)
183
0
5.5
0
196
385
15,000
Adtpic Acid
0
0.2
29.6
0
0.14 •
30
1,190
Adiponitrile via Butadiene
11.2
4.7
50.5
0
0
66.4
3,200
via Adipic Acid
0
0.5
0.04
0
0
0.54
30
Carbon Black
156
8.1
6.9
21.6
3,870
4,060
17,544
Carbon Disulfide
0.15
0.3
0.1
4.5
0
5.1
120
Cyclohexanone
70
0
0
0
77.5
148
5,700
Dimethyl Terephthalate (+TPA)
91
1.4
0.1
1.0
53
146.5
7.460
Ethy Lene
15
0.2
0.2
2.0
0.2
17.6
1,240
Ethylene Dichloride via Oxychlorination
95.1
0.4
0
0
21.8
117.3
7,650
via Direct Chlorination
29
0
0
0
0
29
2,300
Ethylene Oxide
85.8
0
0.3
0.1
0
86.2
6,880
Formaldehyde via Silver Catalyst
23.8
0
0
0
107.2
131
1,955
via Iron Oxide Catalyst
25.7
0
0
0
24.9
50.6
2,070
Glycerol via Epichlorohydrin
16
0
0
0
0
16
1,280
Hydrogen Cyanide Direct Process
0.5
0
0.41
0
0
0.91
56
leocyanates
1.3
0.8
0
0.02
86
88
231
Maleic Anhydride
34
0
0
0
260
294
2,950
Nylon 6
0
1.5
0
0
0
1.5
90
Nylon 6,6
0
5.5
0
0
0
5.5
330
Oxo Process
5.25
0.01
0.07
0
19.5
24.8
440
Phenol
24.3
0
0
0
0
24.3
1,940
Phthalic Anhydride via O-Xylene
0.1
5.1
0.3
2.6
43.6
51.7
422
via Naphthalene
0
1.9
0
0
45
47
160
High Density Polyethylene
79
2.3
0
0
0
81.3
6,400
Low Density Polyethylene
75
1.4
0
0
0
76.4
6,100
Polypropylene
37.5
0.1
0
0
0
37.6
2,950
Polystyrene
20
0.4
0
1.2
0
21.6
1,650
Polyvinyl Chloride
62
12
0
0
0
74
5,700
Styrene
4.3
0.07
0.14
0
0
4.5
355
Styrene-Butadlene Rubber
9.4
1.6
0
0.9
0
12
870
Vinyl Acetate via Acetylene
5.3
0
0
0
0
5.3
425
via Ethylene
0
0
TR
0
0
TR
TR
Vinyl Chloride
17.6
0.6
_0
J)
0
18.2
1.460
Totals
1,227.6
49.1
94.2
33.9
4,852.6
6,225-9
110,220
(1) Inmost Instances numbers are based on less than 100% survey. AIL based on engineering judgement of best current control. Probably has up to 107. lov bias.
(2) Assumes future plants will employ best current control techniques.
(3) Excludes methane, includes H2S and all volatile organics.
(6) Includes non-volatile organics and inorganics.
(5) Weighting factors used are: hydrocarbons - 80, particulates - 60, N0X - 40, S0X - 20, and CO - 1.
(6) Referred to elsewhere in this study as "Significant Emission Index" or "SEI".
(7) Totals are not equal across and down due to rounding.
(9) Emissions based on what is now an obsolete catalyst. See Report No. EPA-450/3-73-006 b for up-to-date information.
-------
TABLE 1
EMISSION SUMMARY
Page 2 of 3
ESTIMATED ADDITIONAL (2) AIR EMISSIONS IN L980. MM LBS./YEAR
Hydrocarbons
Part iculates
<4>
Oxides of Nitrogen
Sulfur Oxides
Carbon Monoxide
Total
Total Weighted
Acetaldehyde via Ethylene
1.2
0
0
0
0
1 .2
96
via Ethanoi
0
0
0
0
0
0
0
Acetic Acid via Methanol
0
0
0.04
0
0
0.04
2
via Butane
0
0
0
0
0
0
0
via Acetaldehyde
12.2
0
0
0
2.5
14.7
980
Acetic Anhydride via Acetic Acid
0.73
0
0
0
1.42
2.15
60
Acrylonitrile (9)
284
0
8.5
0
304
596
23 *000
Adipic Acid
0
0.14
19.3
0
0.09
19.5
779
Adiponitrile via Butadiene
10.5
4.4
47.5
0
0
62.4
3,010
via Adipic Acid
0
0.5
0.04
0
0
0.54
30
Carbon Black
64
3.3
2.8
8.9
1,590
1,670
7,200
Carbon Disulfide
0.04
0.07
0.03
1.1
0
1.24
30
Cyclohexanone
77.2
0
0
0
85.1
162
6,260
Dimethyl Terephthalate (+TPA)
73,8
1.1
0.07
D. 84
42.9
118.7
6,040
Ethylene
14.8
0.2
0.2
61.5
0.2
77
2,430
Ethylene Dichloride via Oxychlorination
110
0.5
0
0
25
136
8,800
via Direct Chlorination
34.2
0
0
0
0
34.2
2,740
Ethylene Oxide
32.8
0
0.15
0.05
0
33
2,650.
Formaldehyde via Silver Catalyst
14.8
0
0
0
66.7
81.5
1,250
via Iron Oxide Catalyst
17.6
0
0
0
17.0
34.6
1,445
Clycerol via Epichlorohydrin
8.9
0
0
0
0
8.9
700
Hydrogen Cyanide Direct Process
0
0
0
0
0
0
0
Isocyanates
1.2
0.7
0
0.02
85
87
225
Maleic Anhydride
31
0
0
0
241
272
2,720
Nylon 6
0
3.2
0
0
0
3.2
L94
Nylon 6,6
0
5.3
0
0
0
5.3
318
Oxo Process
3.86
0.01
0.05
0
14.3
18.2
325
Phenol
21.3
0
0
0
0
21.3
1,704
Phthalic Anhydride via O-Xylene
0.3
13.2
0.8
6.8
113
134
1,100
via Naphthalene
0
0
0
0
0
0
0
High Density Polyethylene
210
6.2
0
0
0
216
17,200
Low Density Polyethylene
262
5
0
0
0
2 67
21,300
Polypropylene
152
0.5
0
0
0
152.5
12,190
Polystyrene
20
0.34
0
1.13
0
21.47
1,640
Polyvinyl Chloride
53
10
0
0
0
63
4,840
Styrene
3.1
0.05
0.1
0
0
3.25
225
Styrene-Butadiene Rubber
1.85
0.31
0
0.18
0
2.34
170
Vinyl Acetate via Acetylene
4.5
0
0
0
0
4.5
360
via Ethylene
0
0
TR
0
0
TR
TR
Vinyl Chloride
26.3
0.9
0
_0
0
27.2
2.170
Totals
1,547.2
55,9
79,5
80.5
2,588
4,351.9
134,213 O)
(1) In most instances numbers are based on
less than 1007, survey.
All based cn
engineering judgement of beE
»t current control
Probably has up
to 107„ low
bias.
(5.6)
(2)
(3)
(4)
<5>
(6)
(7)
(9)
Asaunes future plants wll.1 employ best current control techniques.
Excludes methane, includes H2S and all volatile organics.
Includes non-volatile organics and inorganics.
Weighting factors used are: hydrocarbons - 80, particulates - 60, NO*
Referred to elsewhere in this study as "Significant Emission Index" or
Totals are not equal across and down duw to rounding.
See sheet I of 3.
- 40, S0X - 40
"SEI".
and CO - 1.
-------
TABLE I
EMISSIONS SUMMARY
Page 3 of 3
Emissions (2) , MM Lbs./Year Total Estimated Capacity
Estimated Number of New
Plants
MM Lbs./Year
Total by 1980
Total Weighted (5) bv
1980
(1973 - 19801
Current
Bv 1980
Acetaldehyde via Ethylene
2.3
182
6
1, 160
2,460
via Ethanol
27
27
0
966
966
Acetic Add via MetiianoL
0.05
3
4
400
1 ,800
via Butane
54
3,215
0
1 ,020
500
via Acetaldehyde
22
1,470
3
875
2,015
Acetic Anhydride via Acetic Acid
10.8
313
3
1,705
2,100
Aerylonitrile (9)
980
38,000
5
1, 165
3,700 (B)
Adipic Acid
50
1,970
7
1 ,430
2,200
Adiponitrile via Butadiene
128.8
6,210
4
435
845
via Adipic Acid
1.1
60
3
280
550
Carbon Black
5,730
24,740
13
3 ,000
5,000 (8)
Carbon Disulfide
6.3
150
2
871
1,100
Cyclohexanone
310
11,960
10
1,800
3 ,600
Dimethyl Terephthalate (+TPA)
2 65
13,500
8
2,865
5,900
Ethylene
94
3,670
21
22,295
40,000
Ethylene Dichloride via Oxychlorination
253
16,450
8
4,450
8,250 (8)
via Direct Chlorination
63
5,040
10
5,593
11,540
Ethylene Oxide
120
9,530
15
4,191
6,800 (8)
Formaldehyde via Silver Catalyst
212.5
3,205
40
5,914
9,000
via Iron Oxide Catalyst
85
3,515
12
1,729
3,520 (8)
Glycerol via Epichlorohydrin
25
2,000
1
245
380
Hydrogen CyanLde Direct ProcesB
0.5 (10)
28 (10)
0
412
202
Isocyanates
175
456
10
1,088
2,120
Maleic Anhydride
566
5,670
6
359
720
NyLon 6
4.7
284
10
486
1,500
Nylon 6,6
10.8
650
10
1,523
3,000
Oxo Process
43
765
6
1,727
3,000
Phenol
46
3,640
11
2,363
4,200
Phthalic Anhydride via O-Xylene
186
1,522
6
720
1,800 (8)
via Naphthalene
47
160
0
603
528
High Density Polyethylene
297
23,600
31
2,315
8,500
Lov Density Polyethylene
343
27,400
41
5,2 69
21,100
Polypropylene
190
15,140
32
1,160
5,800
Polystyrene
43
3,290
23
3,500
6,700
Polyvinyl Chloride
137
10,540
25
4,375
8,000
Styrene
7.4
610
9
5,953
10,000
Styrone-Butadlene Rubber
14
1,040
4
4,464
5,230
Vinyl Acetate via Acetylene
9.8
785
1
206
356
via Ethylene
TR
TR
4
1,280
2,200
Vinyl Chloride
45
3.630
10
5,400
13,000
Totals
10,605
244,420 <7>
(I) In most Instances numbers are based on
less than 100% survey.
All based on engineering
judgement
of best current control.
Probably
has
-------
1-6
In order to obtain data on these processes, the operators and/or
licensors of each were approached directly by Air Products' personnel.
This, of course, was a slow and tedious method of data collection because
mass mailing techniques could not be used, nor could the request for data
be identified as an "Official EPA Requirement". Yet, by the time that OMB
approval was given for use of the Industry Questionnaire, a substantial
volume of data pertaining to each process had already been received. The
value of this procedure is indicated by the fact that first drafts of these
three reports had already been submitted to the EPA, and reviewed by the
Industry Advisory Committee, prior to the completion of many of the survey
reports.
In addition, because of timing requirements, the EPA decided that three
additional chemicals be "nominated" for in-depth study. These were phthalic
anhydride, formaldehyde and ethylene oxide. Consequently, four additional
in-depth studies were undertaken, as follows:
1. Air Oxidation of Ortho-Xylene to produce Phthalic Anhydride.
2. Air Oxidation of Methanol in a Methanol Rich Process to produce
Formaldehyde over a Silver Catalyst. (Also, the subject of a
survey report.)
3. Air Oxidation of Methanol in a Methanol-Lean Process to
produce Formaldehyde over an Iron Oxide Catalyst.
4. Direct Oxidation of Ethylene to produce Ethylene Oxide.
The primary data source for these was the Industry Questionnaire,
although SEI rankings had not been completed by the time the choices were
made.
The Survey Reports, having now been completed are available, for use in
the selection of additional processes for In-depth study.
-------
INTRODUCTION TO APPENDIX II AND III
The following discussions describe techniques that were developed for
the single purpose of providing a portion of the guidance required in the
selection of processes for in-depth study. It is believed that the underlying
concepts of these techniques are sound. However, use of them without sub-
stantial further refinement is discouraged because the data base for their
specifics is not sufficiently accurate for wide application. The subjects
covered in the Appendix II discussion are:
1. Prediction of numbers of new plants.
2. Prediction of emissions from the new plants on a weighted
(significance) basis.
The subject covered in the Appendix III discussion is:
Calculation of pollution control device efficiency on a variety of
bases, including a weighted (significance) basis.
It should be noted that the weighting factors used are arbitrary.
Hence, if any reader of this report wishes to determine the effect of
different weighing factors, the calculation technique permits changes in
these, at the reader's discretion.
-------
APPENDIX II
Number of New Plants*
Attached Table 1 illustrates the format for this calculation.
Briefly, the procedure is as follows:
1. For each petrochemical that is to be evaluated, estimate what
amount of today's production capacity is likely' to be on-stream
in 1980. This will be done by subtracting plants having marginal
economics due either to their size or to the employment of an
out-of-date process.
2. Estimate the 1980 demand for the chemical and assume a 1980
installed capacity that will be required in order to satisfy
this demand.
3. Estimate the portion of the excess of the 1980 required capacity
over today's remaining capacity that will be made up by
installation of each process that is being evaluated.
4. Estimate an economic plant or unit size on the basis of today's
technology.
5. Divide the total required new capacity for each process by the
economic plant size to obtain the number of new units.
In order to illustrate the procedure, data have been incorporated
into Table I, for the three processes for producing carbon black, namely
the furnace process, the relatively non-polluting thermal process, and
the non-growth channel process.
*The format is based on 1980, but any future year may be selected.
-------
Table
1. Number of
New Plants
by 1980
Chemical
Process
Current
Capacity
Marginal
Capacity
Current
Capacity
on-stream
in 1980
Demand
1980
Capacity
1980
Capacity
to be
Added
Economic
Plant
Size
Number of
New
Units
Carbon Black
Furnace
4,000
0
4,000
4,500
5,000
1,000
90
11 - 12
Channel
100
0
100
100
100
0
30
0
Thermal
200
0
200
400
500
300
150
2
Notes: 1. Capacity units all in MM lbs./year.
2. 1980 demand based on studies prepared for EPA by Processes Research, Inc. and MSA Research Corporation.
-------
II—3
Increased Emissions (Weighted) by 1980
Attached Table 2 illustrates the format for this calculation.
However, more important than format is a proposal for a weighting basis.
There is a wide divergence of opinion on which pollutants are more noxious
and even when agreement can be reached on an order of noxiousness, dis-
agreements remain as to relative magnitudes for tolerance factors. In
general pollutants from the petrochemical industry can be broken down into
categories of hydrogen sulfide, hydrocarbons, particulates, carbon monoxide,
and oxides of sulfur and nitrogen. Of course, two of these can be further
broken down; hydrocarbons into paraffins, olefins, chlorinated hydrocarbons,
nitrogen or sulfur bearing hydrocarbons, etc. and particulates into ash,
catalyst, finely divided end products, etc. Itwa6felt that no useful
end is served by creating a large number of sub-groupings because it would
merely compound the problem of assigning a weighting factor. Therefore,
it was proposed to classify all pollutants into one of five of the six
categories with hydrogen sulfide included with hydrocarbons.
There appears to be general agreement among the experts that carbon
monoxide is the least noxious of the five and that N0X is somewhat more
noxious than S0X. However, there are widely divergent opinions concerning
hydrocarbons and particulates - probably due to the fact that these are
both widely divergent categories. In recent years, at least two authors
have attempted to assign tolerance factors to these five categories.
Babcock (1), based his on the proposed 1969 California standards for
one hour ambient air conditions with his own standard used for hydrocarbons.
On the other hand, Walther (2), based his ranking on both primary
and secondary standards for a 24-hour period. Both authors found it
necessary to extrapolate some of the basic standards to the chosen time
period. Their rankings, on an effect factor basis with carbon monoxide
arbitrarily used as a reference are as follows:
Babcock
Walther
Hydrocarbons
Particulates
NOv
S0X
CO
2.1
107
77.9
28.1
1
Primary
125
21.5
22.4
15.3
1
Secondary
125
37.3
22.4
21.5
1
Recognizing that it is completely unscientific and potentially subject
to substantial criticism it was proposed to take arithmetic averages of the
above values and round them to the nearest multiple of ten to establish a
rating basis as follows:
Average Rounded
Hydrocarbons 84.0 80
Particulates 55.3 60
N0X 40.9 40
S0„ 21.6 20
CO 11
-------
Table 2. Weighted Emission Rates
Chemi c a 1
Process
Increased Capacity
Increased Emissions
Pollutant Emissions, Lbs./Lb. Lbs./Year
Hydrocarbons
Particulates
N0X
S0X
CO
Weighting
Factors
Weighted Emissions
Lbs./Year
80
60
40
20
1
Total
-------
II-5
Increased Emissions (Weighted) by 1980 (continued)
This ranking can be defended qualitatively, if not quantitatively for
the following reasons:
1. The level of noxiousness follows the same sequence as is obtained
using national air quality standards.
2. Approximately two orders of magnitude exist between top and bottom
rankings.
3. Hydrocarbons should probably have a lower value than in the
Walther analysis because such relatively non-noxious compounds
as ethane and propane are included.
4. Hydrocarbons should probably have a higher value than in the
Babcock analysis because such noxious (or posionous) substances
as aromatics, chlorinated hydrocarbons, phenol, formaldehyde, and
cyanides are included.
5. Particulates should probably have a higher value than in the
Walther analysis because national air standards are based mostly
on fly ash while emissions from the petrochemical industry are
more noxious being such things as carbon black, phthalic anhydride,
PVC dust, active catalysts, etc.
6. NOx should probably have a higher value than in the Walther
analysis because its role in oxidant synthesis has been neglected.
This is demonstrated in Babcock's analysis.
Briefly, the procedure, using the recommended factors and Table 2, is
as follows:
1. Determine the emission rate for each major pollutant category in
terms of pounds of pollutant per pound of final product. (This
determination was made, on the basis of data reported on returned
questionnaires,in the Survey ReportsJ.
2. Multiply these emission rates by the estimate of increased production
capacity to be installed by 1980 (as calculated while determining
the number of new plants), to determine the estimated pounds of
new emissions of each pollutant.
3. Multiply the pounds of new emissions of each pollutant by its
weighting factor to determine a weighted pounds of new emissions
for each pollutant.
4. Total the weighted pounds of new emissions for all pollutants to
obtain an estimate of the significance of emission from the process
being evaluated. It was proposed that this total be named
"Significant Emission Index" and abbreviated "SEI".
It should be pointed out that the concepts outlined above are not
completely original and considerable credit should be given to Mr. L. B. Evans
of the EPA for setting up the formats of these evaluating procedures.
-------
II-6
Increased Emissions (Weighted) by 1980 (continued)
Babcock, L. F., "A Combined Pollution Index for Measurement of Total
Air Pollution," JAPCA, October, 1970; Vol. 20, No. 10; pp 653-659
Walther, E. G., "A Rating of the Major Air Pollutants and Their Sources
by Effect", JAPCA, May, 1972; Vol. 22, No. 5; pp 352-355
-------
Appendix III
Efficiency of Pollution Control Devices
Incinerators and Flares
The burning process is unique among the various techniques for
reducing air pollution in that it does not remove the noxious substance
but changes it to a different and hopefully less noxious form. It can be,
and usually is, a very efficient process when applied to hydrocarbons,
because when burned completely the only products of combustion are carbon
dioxide and water. However, if the combustion is incomplete a wide range
of additional products such as cracked hydrocarbons, soot and carbon
monoxide might be formed. The problem is further complicated if the
hydrocarbon that is being burned is halogenated, contains sulfur or is
mixed with hydrogen sulfide, because hydrogen chloride and/or sulfur oxides
then become products of combustion. In addition, if nitrogen is present,
either as air or nitrogenated hydrocarbons, oxides of nitrogen might be
formed, depending upon flame temperature and residence time.
Consequently, the definition of efficiency of a burner, as a pollution
control device, is difficult. The usual definition of percentage removal of
the noxious substance in the feed to the device is inappropriate, because
with this definition, a "smoky" flare would achieve the same nearly 100
percent rating, as a "smokeless" one because most of the feed hydrocarbon
will have either cracked or burned in the flame. On the other hand, any
system that rates efficiency by considering only the total quantity of
pollutant in both the feed to and the effluent from the device would be
meaningless. For example, the complete combustion of one pound of hydrogen
sulfide results in the production of nearly two pounds of sulfur dioxide, or
the incomplete combustion of one pound of ethane could result in the
production of nearly two pounds of carbon monoxide.
For these reasons, it was proposed that two separate efficiency rating
be applied to incineration devices. The first of these is a "Completeness
of Combustion Rating" and the other is a "Significance of Emission Reduction
Rating", as follows;
1. Completeness of Combustion Rating (CCR)
This rating is based on oxygen rather than on pollutants and is
the pounds of oxygen that react with the pollutants in the feed to
the device, divided by the theoretical maximum number of pounds that
would react: Thus a smokeless flare would receive a 100 percent
rating while a smoky one would be rated somewhat less, depending upon
how incomplete the combustion.
In utilizing this rating, it is clear that carbon dioxide and water
are the products of complete combustion of hydrocarbons. However, some
question could occur as to the theoretical completion of combustion
when burning materials other than hydrocarbons. It was recommended
that the formation of HX be considered complete combustion of halogenated
hydrocarbons since the oxidation most typically does not change the
valence of the halogen. On the other hand, since some incinerators will
be catalytic in nature it was recommended that sulfur trioxide be
considered as complete oxidation of sulfur bearing compounds.
-------
III-2
Efficiency of Pollution Control Devices
1. Completeness of Combustion Rating (CCR) (continued)
Nitrogen is more complex, because of the equilibria that exist
between oxygen, nitrogen, nitric oxide, nitrogen dioxide and the
various nitrogen radicals such as nitrile. In fact, many scientists
continue to dispute the role of fuel nitrogen versus ambient nitrogen
in the production of NO*. In order to make the CCR a meaningful
rating for the incineration of nitrogenous wastes it was recommended
that complete combustion be defined as the production of N£, thus
assuming that all N0X formed comes from the air rather than the fuel,
and that no oxygen is consumed by the nitrogen in the waste material.
Hence, the CCR becomes a measure of how completely the hydrocarbon
content is burned, while any NOx produced (regardless of its source)
will be rated by the SERR as described below.
2. Significance of Emission Reduction Rating (SERR)
This rating is based primarily on the weighting factors that
were proposed above. All air pollutants in the feed to the device
and all in the effluents from the device are multiplied by the
appropriate factor. The total weighted pollutants in and out are
then used in the conventional manner of calculating efficiency
of pollutant removal, that is pollutants in minus pollutants out,
divided by pollutants in, gives the efficiency of removal on a
significance of emission basis.
Several examples will serve to illustrate these rating factors,
as follows:
Example 1 - One hundred pounds of ethylene per unit time is burned
in a flare, in accordance with the following reaction:
3C2H4 + 7 O2 ~ C + 2 CO + 3 C02 + 6 H20
Thus, 14.2 lbs. of particulate carbon and 66.5 lbs. of carbon
monoxide are emitted, and 265 lbs. of oxygen are consumed.
Theoretical complete combustion would consume 342 lbs. of oxygen
in accordance with the following reaction:
C2H4 + 3 02 ~ 2 CO2 +2 H2O
Thus, this device would have a CCR of 265/342 or 77.5%
Assuming that one pound of nitric oxide is formed in the reaction
as a result of the air used for combustion (this is about equivalent to
100 ppm), a SERR can also be calculated. It should be noted that the
formation of this NO is not considered in calculating a CCR because it
came from nitrogen in the air rather than nitrogen in the pollutant
being incinerated. The calculation follows:
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III-3
Efficiency of Pollution Control Devices
2. Significance of Emission Reduction Ratine (SERR) (continued)
Weighting Pounds in Pounds out
Pollutant Factor Actual Weighted Actual Weighted
Hydrocarbons 80 100 8000 0
Particulates 60 0 14.2 852
NOx 40 0 1 40
SOx 20 0 0
CO 1 0 66.5 66.5
Total 8000 958.5
SERR = 8000 - 958.5
8000
x 100 = 887„
Example 2 - The same as Example 1, except the hydrocarbons are
burned to completion. Then,
CCR = 342 ^
3^2 x 100 = 100%
and
SERR = 8000 - 40
8000
= 99.5%
Example 3 - One hundred pounds per unit time of methyl chloride is
incinerated, in accordance with the following reaction.
2 CH3CI + 3 02 E 2 CO2 + 2 H20 + 2 HC1
This is complete combustion, by definition, therefore, the CCR is
1007.. However, (assuming no oxides of nitrogen are formed), the SERR
is less than 1007. because 72.5 lbs. of HC1 are formed. Hence,
considering HC1 as an aerosol or particulate;
SERR = 100 x 80 - 72.5 x 60 ™
100 x 80
The conclusion from this final example, of course, is that it is
an excellent combustion device but a very poor pollution control device,
unless it is followed by an efficient scrubber for HC1 removal.
Example 4 - The stacks of two hydrogen cyanide incinerators, each
burning 100 pounds per unit time of HCN are sampled. Neither has any
carbon monoxide or particulate in the effluent. However, the first is
producing one pound of NO* and the second is producing ten pounds of
NOx in the same unit time. The assumed reactions are:
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III-4
Efficiency of Pollution Control Devices
2. Significance of Emission Reduction Rating (SERR) (continued)
4 HCN + 5 02 ' ¦ 1 ~ 2 H20 + 4 C02 + 2 N2
N2 (atmospheric) + X02 1111 1 ~ 2 N0X
Thus, CCR^ = 100% and CCR2 = 100% both by definition.
However, SERRn = 100 x 80 - 1 x 40 inn _ QO ...
100 x 80
and SERRo = 100 x 80 - 10 x 40
2 100 x 80 x 100 = 95^
Obviously, if either of these were "smoky" then both the CCR and
the SERR would be lower, as in Example 1>
Other Pollution Control Devices
Most pollution control devices, such as bag filters, electrostatic
precipitators and Bcrubbers are designed to physically remove one or more
noxious substances from the stream being vented. Typically, the efficiency
of these devices is rated relative only to the substance which they are
designed to remove and for this reason could be misleading. For example:
1. The electrostatic precipitator on a power house stack might be
997» efficient relative to particulates, but will remove little
or none of the SOx and N0X which are usually present,
2. A bag filter on a carbon black plant will remove 99 + % of the
particulate but will remove none of the CO and only relatively
small amounts of the compounds of sulfur that are present.
3. A water scrubber on a vinyl chloride monomer plant will remove
all of the hydrogen chloride but only relatively small amounts
of the chlorinated hydrocarbons present.
4. An organic liquid scrubber on an ethylene dichloride plant will
remove nearly all of the EDC but will introduce another pollutant
into the air due to its own vapor pressure.
For these reasons, it was suggested again that two efficiency ratings be
applied. However, in this case, the first is merely a specific efficiency as
is typically reported, i.e., "specific to the pollutant (or pollutants) for
which it was designed", thus:
SE = specific pollutant in - specific pollutant out
specific pollutant in x
The second rating proposed is an SERR, defined exactly as in the case
of incinerators.
Two examples will illustrate these ratings.
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III-5
Efficiency of Pollution Control Devices
Other Pollution Control Devices (continued)
Example 1 - Assume that a catalytic cracker regenerator effluent
contains 100 pounds of catalyst dust, 200 lbs. of
carbon monoxide and 10 pounds of sulfur pxides per unit
time. It is passed through a cyclone separator where
95 pounds of catalyst are removed. Therefore,
SE =100-5
1Q0 x 100 = 95%
and SERR = (100 x 60 + 10 x 20 4- 200 x 1) - (5 x 60 + 10 x 20 + 200 x 1) x 100
(100 x 60 + 10 x 20 + 200 x 1)
= 6400 - 700 x 100 = 89%
6400
Example 2 - Assume that an organic liquid scrubber is used to wash a
stream containing 50 pounds of SO2 per unit time. All
but one pound of the SO2 is removed but two pounds of
the hydrocarbon evaporate into the vented stream. Then
SE 5°5o 1 xl0° = 981
and SERR = (50 x 20) - (1 x 20 + 2 x 80)
(50 x 20) x 100
= 1000 - 180 x 10Q = g27o
1000
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 . REPORT NO.
EPA-450/3-73-006-b
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Engineering and Cost Study of Air Pollution Control
5. REPORT DATE
February 1975
for the Petrochemical Industry, Volume 2: Acrylonitrile
Manufacture
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
W. A. Schwartz, F. B. Higgins, Jr., J. A. Lee,
R. Newirth, J. W. Pervier
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Houdry Division/Air Products and Chemicals,
P. 0. Box 427
Marcus Hook, Pennsylvania 19061
Inc.
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-02-0255
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Air Quality Planning & Standards
13. TYPE OF REPORT AND PERIOD COVERED
Final Report
Industrial Studies Branch
Research Triangle Park, N. C. 27711
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This document is one of a series prepared for the Environmental Protection
Agency (EPA) to assist it in determining those petrochemical processes for which
standards should be promulgated. A total of nine petrochemicals produced by
twelve distinctly different processes has been selected for this type of in-depth
study. Ten volumes, entitled Enqineerinq and Cost Study of Air Pollution Control
for the Petrochemical Industry (EPA-450/3-73-006-a through j) have been prepared.
A combination of expert knowledge and an industry survey was used to select
these processes. The industry survey has been published separately in a series of
four volumes entitled Survey Reports on Atmospheric Emissions from the Petrochemical
Industry (EPA-450/3-73-005-a
, b, c, and d).
This volume covers the manufacture of acrylonitrile. Included is a process
and industry description, an engineering description of available emission control
systems, the cost of these systems, and the financial impact of emission control
on the industry. Also presented are suggested air episode procedures and plant
inspection procedures.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution
Carbon Monoxide
Hydrocarbons
Acrylonitriles
Ni triles
Cyanides
Nitrogen Oxides
Petrochemical Industry
7A
7B
7C
11G
13B
13H
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
103
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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