United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/4-91-031
November 1991
Air
©EPA Guideline Series
Control of Volatile Organic
Compound Emissions from
Reactor Processes and
Distillation Operations Processes
in the Synthetic Organic
Chemical Manufacturing Industry
DRAFT
-------
EPA-450/4-91 -031
DRAFT
Guideline Series
Control of Volatile Organic Compound
Emissions from Reactor Processes and
Distillation Operations Processes in the
Synthetic Organic Chemical Manufacturing Industry
Emiuion Slanda,ds DI 4sion
U.S. ENVIRONMENTAL PROTECTION AGENCY
Offla of A r and RadIa on
OlfIc. of A OuaiIty Planning and Standarda
R.s.arcl, Trlangl. Park, North Carolina 27711
Nov.mb.r 1991
-------
GUIDELINE SERiES
The guideline series of reports is issued by the Office of Air Quality
Planning and Standards (OAQPS) to provide information to State and local air
pollution control agencies; for example, to provide guidance on the
acquisition and processing of air quality data and on the planning and
analysis requisite for the maintenance of air quality. Mention of trade
names or commercial products is not intended to constitute endorsement or
recommendation for use. Reports published in this series will be
available - as supplies permit - from the Library Services Office (MD-35),
U. S. Environmental Protection Agency, Research Triangle Park,
North Carolina 27711, or for a nominal fee, from the National Technical
Information Service, 5285 Port Royal Road, Springfield, Virginia 22161.
gep.002 ii
-------
CONTENTS
Figures
Tables
1. Introduction
2. Industry Characteristics and Emissions
2.1 General Industry Information
2.2 Reactor Processes
2.2.1 Scope of Reactor Processes
2.2.2 Chemical Reaction Descriptions
2.2.2.1 Alkylation
2.2.2.2 Ammonolysis
2.2.2.3 Carboxylation/Hydroformylation
2.2.2.4 Cleavage
2.2.2.5 Condensation
2.2.2.6 Dehydration
2.2.2.7 Dehydrogenation
2.2.2.8 Dehydrohalogenation
2.2.2.9 Esterification
2.2.2.10 Halogenation
2.2.2.11 Hydrodealkylation
2.2.2.12 Hydrohalogenation
2.2.2.13 Hydrolysis/Hydration
2.2.2.14 Hydrogenation
2.2.2.15 Isomerization
2.2.2.16 Neutralization
2.2.2.17 NitratIon
2.2.2.18 Oligomerization
2.2.2.19 Oxidation
2.2.2.20 Oxyacetylation
2.2.2.21 Oxyhalogenation
2.2.2.22 Phosgenation
2.2.2.23 Pyrolysis
2.2.2.24 Sulfonation
2.3 DIstillation Operations
2.3.1 Types of Distillation .
2.3.2 Fundamental Distillation Concepts
2.4 Reactor VOC Emissions . . . . . . . . . .
2.5 VOC Emissions from Distillation Units . .
2.6 References . . . . . . . . . . . . . . .
3. Emission Control Techniques . .
3.1 Combustion Control Devices .
3.1.1 Flares . . . . . . .
.
. vi
viii
1-1
2-1
2-2
2-7
2-7
2-7
2-7
2-10
2- I l
2-12
2-12
2-13
2-14
2-15
2-15
2-16
2-17
2-17
2-18
2-19
2-20
2-20
2-20
2-21
2-21
2-22
2-22
2-23
2-23
2-24
2-24
2-25
. . . . 2-27
. . . 233
. . . . 239
. . . 248
. . . . 31
. . 31
* . * . 31
* . 31
. * 34
. . 36
3.1.1.1
3.1.1.2
3.1.1.3
Flare Process Description .
Factors Affecting Flare Efficiency
EPA Flare Specifications
gep. 002
iii
-------
CONTENTS, Continued
Applicability of Flares
incinerators
Thermal Incinerator Process Description
Thermal incinerator Efficiency
Applicability of Thermal Incinerators
1 Boilers/Process Heaters
Industrial Boiler/Process Description
Process Heater Description
Industrial Boilers and Process Heater
Control Efficiency
3.1.3.4 Applicability of Industrial Boilers and
Process Heaters
3.1.4 Catalytic Oxidizers
3.1.4.1 Catalytic Oxidation Process Description
3.1.4.2 Catalytic Oxidizer Control Efficiency
3.1.4.3 Applicability of Catalytic Oxidizers
3.2 Recovery Devices
3.2.1 Adsorption
3.2.1.1 Adsorption Process Description
3.2.1.2 Adsorption Control Efficiency
3.2.1.3 Applicability of Adsorption
3.2.2 Absorption
3.2.2.1 Absorption Process Description
3.2.2.2 Absorption Control Efficiency
3.2.2.3 Applicability of Absorption
3.2.3 Condensation
3.2.3.1 Condensation Process Description
3.2.3.2 Condenser Control Efficiency
3.2.3.3 Applicability of Condensers
3 . 3 Summary . . . . . .
3.4 References
4. Environmental Impacts of Reasonably Available Control
Technology (RACT) . . . . .
4.1 AIr Pollution Impacts .
4.1.1 VOC Emission Impacts
4.1.2 Other Effects on Air Quality
4.2 Water Pollution Impacts . . .
4.3 SolId Waste Disposal Impacts . . .
4.4 Energy Impacts .. . . . . . . . . . . . . .
4.7 References
5. Cost Analysis
5.1 Introduction . . . . . . . . .
5.2 Cost Methodology for Incinerator Systems .
3.1.1.4
3.1.2 Thermal
3.1.2.1
3.1.2.2
3.1.2.3
3.1.3 Industria
3.1.3.1
3.1.3.2
3.1.3.3
3-6
3-6
3-6
3-11
3-12
3-12
3-13
3-14
3-14
3-15
3-16
3-16
3-17
3-19
3-19
3-19
3-19
3-21
3-21
3-23
3-23
3-24
3-26
3-26
326
3-26
3-28
3-28
. . . . 330
4-1
4-1
41
43
0 0 4 4
4-6
4-6
. . 47
. . . . 51
5-1
5-1
gep. 002
iv
-------
CONTENTS, Continued
. . . 5-1
. . . 5-3
. . . 5-3
. . 5-4
. . . 5-5
. . . 5-6
. . . 5-6
. . 5-6
....5-6
. . 5-6
. . 5-9
. . 5-9
. . . 5-11
* . 5-12
. . 5-12
. . 5-12
. . 5-12
. . 5-12
5-12
. . 6-1
. 6-1
. 6-2
. 6-3
. 6-4
. 6-4
. 6-4
. 6-5
6-8
7-1
7-1
. 7-1
. 7-2
7-3
7-5
. 7-5
7-5
. 7-7
. 7-7
. 7-7
5.2.1 Thermal Incinerator Design Considerations
5.2.1.1 Combustion Air Requirements
5.2.1.2 Recuperative Heat Recovery
5.2.1.3 Incinerator Design Temperature
5.2.2 Thermal Incinerator Capital Costs
5.2.3 Thermal Incinerator Annualized Cost
5.2.3.1 Labor Costs
5.2.3.2 Capital Charges
5.2.3.3 Utility Costs
5.2.3.4 Maintenance Costs
5.3 Cost Methodology for Flare Systems
5.3.1 Flare Design Considerations
5.3.1 Development of Flare Capital Costs
5.3.2 Development of Flare Annualized Costs
5.3.3.1 Labor Costs
5.3.3.2 Capital Charges
5.3.3.3 Utility Costs
5.3.3.4 Maintenance Costs
5.4 Comparison of Control System Costs
6. Selection of RACT
6.1 Background
6.2 Technical Basis for RACT
6.3 Approach for Applying RACT
6.3.1 Approach A - Concentration Cutoff .
6.3.2 Approach B - Flowrate Cutoff
6.3.3 Approach C - Concentration with Flowrate
6.4 RACT Impacts on Example Vent Streams
6.5 References
7. Ract Implementation
7.1 Introduction
7.2 Definitions
7.3 Applicability
7.4 Format of the Standards
7.5 Compliance Testing
7.6 Monitoring Requirements
7.6.1 Incinerators
7.6.2 Flares
7.6.3 Boiler or Process Heater
7.7 Reporting/Recordkeeping Requirements
Cutoff
gep.002
V
-------
FIGURES
Number Page
2-1 The interwoven nature of feedstocks for the organic chemicals
manufacturing industry 2-4
2-2 Chemical derivatives made from the feedstock ethylene 2-5
2-3 Flash distillation 2-6
2-4 A conventional fractionating column 2-28
2-5 General examples of reactor-related vent streams 2-34
2-6 Process flow diagram for the manufacture of nitrobenzene . . . . 2-35
2-7 Process flow diagram for the manufacture of ethylbenzene . . . . 2-36
2-8 Process flow diagram for the manufacture of acetone 2-37
2-9 Potential VOC emission points for a nonvacuum distillation
column 2-42
2-10 Potential VOC emission points for a vacuum distillation column
using steam jet ejectors with barometric condenser 2-43
2-11 Potential VOC emission points for a vacuum distillation column
using steam jet ejectors with barometric condenser 2-44
2-12 Potential VOC emission points for vacuum distillation column
using a vacuum pump 2-45
3-1 Two stage regenerative adsorption system 3-3
3-2 Discrete burner, thermal oxidizer 3-8
3-3 Distributed burner, thermal oxider 3-9
3-4 Catalytic oxidizer . . . . . . . 3-18
3-5 Two stage regenerative adsorption system 3-22
3-6 Packed tower for gas adsorption 3-25
3-7 Condensation system 3-27
gep. 002
vi
-------
Number
2-1 Feedstock Chemical for Chemical Production Processes .
2-2 Estimated Production and Chemical Coverage for Various
Production Levels
2-3 Ranking of Chemical Reaction Types
2-4 Summary of Reactor-Related VOC Emission Factors, Vent Stream
Heat Con ents, and Flow Rate Prior to Combustion
2-5 Overview of the Distillation Operations Emissions Profile
4-1 Air and Energy Impacts for Distillation and Reactor Model
Vent Streams
5-1 Incinerator General Design Specifications
5-2 Capital Cost Factors for Thermal Incinerators
5-3 Annual Operating Cost Basis for Thermal Incinerators . .
5-4 Flare General Design Specifications
5-5 Annual Operating Costs for Flare Systems
5-6 Cost Results for Model SOCMI Vent Streams
6-1 Impacts of RACT Options on Example Facilities--Nonhalogenated
Streams
6-2 Impacts of RACT Options on Example Facilities--Halogenated
Streams
TABLES
Page
. 2-1
. 2-6
. 2-8
2-40
. 2-47
. 4-1
. 5-2
. 5-7
. 5-8
5-10
5-14
5-16
. 6-6
. 6-7
gep. 002
vii
-------
1. INTRODUCTION
The Clean Air Act (CAA) amendments of 1990 require that State
Implementation Plans (SIPs) for certain ozone nonattainment areas be revised
to require the implementation of reasonably available control technology
(RACT) for control of volatile organic compound (VOC) emissions from sources
for which EPA has already published Control Techniques Guidelines (GIGs) or
for which EPA will publish a CTG between the date of enactment of the
amendments and the date an area achieves attainment status.
Section 172(c)(1) requires nonattainment area SIPs to provide, at a minimum,
for such reductions in emissions from existing sources in the area as may be
obtained through the adoption, at a minimum, of reasonably available control
technology... As a starting point for ensuring that these SIPs provide for
the required emission reduction, EPA in the notice at 44 FR 53761
(September 17, 1979) defines RACT as: The lowest emission limitation that a
particular source is capable of meeting by the application of control
technology that Is reasonably available considering technological and
economic feasibility. EPA has elaborated in subsequent notices on how States
and EPA should apply the RACT requirements (See 51 FR 43814, December 4,
1989; and 53 FR 45103, November 8, 1988).
The CTGs are intended to provide State and local air pollution
authorities with an information base for proceeding with their own analyses
of RACT to meet statutory requirements. The CTGs review current knowledge
and data concerning the technology and costs of various emissions control
techniques. Each CTG contains a presumptive norm for RACT for a specific
source category, based on EPAs evaluation of the capabilities and problems
general to that category. Where applicable, EPA recommends that States adopt
requirements consistent with the presumptive norm. However, the presumptive
norm is only a recommendation. States may choose to develop their own RACT
requirements on a case-by-case basis, considering the economic and technical
circumstances of an individual source. It should be noted that no laws or
regulations preclude States from requiring more control than recommended as
gep.002 1-1
-------
the presumptive norm for RACT. A particular State, for example, nay need a
more stringent level of control in order to meet the ozone standard or to
reduce emissions of a specific toxic air pollutant.
This CTG Is one of at least 11 CTGs that EPA Is required to publish
within 3 years of enactment of the CAA amendments. It addresses RACT for
control of VOC emissions from two types of process vents used at plants in
the Synthetic Organic Chemical Manufacturing Industry (SOCMI): reactors
(other than those Involving air oxidation processes) and distillation
columns. This document is currently in draft form and Is being distributed
for public comment. Public comments will be reviewed and incorporated as
judged appropriate before EPA finalizes the CTG.
Other emission sources at SOCMI plants, such as air oxidation vents,
storage vessels, equipment leaks, and wastewater, are addressed by CTG
documents either already published or planned.
gep.002 1-2
-------
2. INDUSTRY CHARACTERISTICS AND EMISSIONS
The synthetic organic chemical manufacturing industry (SOCMI) is a large
and diverse industry producing hundreds of major chemicals through a variety
of chemical processes. A process is any operation or series of operations
that causes a physical or chemical change in a substance or mixture of
substances. A process unit is the apparatus within which one of the
operations of a process is carried out. Materials entering a process unit
are referred to as feedstocks or inputs, while materials leaving a process
unit are called products or outputs.
The major processing steps employed in organic chemical manufacturing
plants can be classified in two broad categories: conversion and separation.
Conversion processes are chemical reactions that alter the molecular
structure of the compounds involved. Conversion processes comprise the
reactor processes segment of a SOCMI plant.
Separation processes typically follow conversion processes and divide
chemical mixtures into distinct fractions. Examples of separation processes
are distillation, filtration, crystallization, and extraction. Among these,
the predominant separation technique used in large scale organic chemical
manufacturing plants is distillation. Distillation is a unit operation used
to separate one or more inlet feed streams into two or more outlet product
streams, each having constituent concentrations different from the
concentrations found in the inlet feed stream.
This chapter describes the use of reactor processes and distillation
operations in the SOCMI. Section 2.1 focuses on general industry
information, while Sections 2.2 and 2.3 discuss basic concepts of reactor
processes and distillation operations, respectively. In the final sections
of this chapter, the characteristics of typical reactor process and
distillation operation vent stream emissions are summarized. Section 2.4
examines reactor emission characteristics, while Section 2,5 presents
distillation emission characteristics.
gep.002 2 -1
-------
2.1 GENERAL INDUSTRY INFORMATION
Most organic chemicals are manufactured in a multi-faceted system of
chemical processes based on about 15 feedstocks that are processed through
one or more process levels and result in hundreds of intermediate or finished
chemicals. These feedstocks (presented in Table 2-1) originate from three
basic raw materials: crude oil, natural gas, and coal. Figure 2-1 shows the
highly integrated supply system for these feedstock chemicals from the three
basic raw materials.
The chemical industry may be described in terms of an expanding system
of production stages. Refineries, natural gas plants and coal tar
distillation plants represent the first stage of the production system. As
illustrated in Figure 2-1, these industries supply the feedstock chemicals
from which most other organic chemicals are made. The organic chemical
industry represents the remaining stages of the system. Chemical
manufacturers use the feedstocks produced in the first stage to produce
intermediate chemicals and final products. Manufacturing plants producing
chemicals at the end of the production system are usually smaller operations
since only a narrow spectrum of finished chemicals Is being produced. The
products from ethylene shown in Figure 2-2 are an example of a system of
production stages from a feedstock chemical. The production of feedstock
chemicals is an extremely dynamic Industry that may quickly change its
sources of basic raw materials depending upon availability and costs.
The estimated total domestic production for all synthetic organic
chemicals in 1988 was 124 x 106 Mg (273 x ib). This production total
includes over 7,000 different chemicals. A study conducted in the early
1980s indicated that a relatively small number of chemicals dominate industry
output, as illustrated In Table 2-2. The table shows the number of chemicals
with production output above various production levels (l,e., chemicals with
total national production greater than the listed production level). A
national production level of 45,400 Mg/yr (100 million lb/yr) was used to
define the segment of the organic chemical manufacturing industry covered by
this CTG. The scope includes approximately 220 chemicals estimated to
account for about 90 percent of the total domestic chemical production. 2 The
220 chemicals are listed in Appendix A.
gep.002 2-2
-------
TABLE 2-1. FEEDSTOCK CHEMICALS FOR CHEMICAL PRODUCTION PROCESSES
Benzene Ethylene Pentane
Butane Isobutane Propane
1-Butene Isopentane Propylene
2-Butene Methane Toluene
Ethane Naphthalene Xylenes
gep.002 2-3
-------
Coal
Crud. Oil
Natural Gas
Major Sourcs
Minor Sourcs
Figure 2-1.
The interwoven nature of
manufacturing industry.
feedstocks for the organic chemicals
Msthan
Benzeni
Toluene
Xyieri.
I -But. , ,.
2-But.n.
Ethan.
Butan.
Propan.
Ethyl .n.
Propyi.n.
gep. 002
2-4
-------
Ethylene Dichioride Ethanol
Ethylene
Other Chemicals Ethylbenzene
Other Chemicals Ethylene Oxide Ethanolamines
Ethylene Glycol Acetate EthYlent Glycol tex Paints
Polyester Fiber
Figure 2-2. Chemical derivatives made from the feedstock ethylene.
gep.002 2-5
-------
TABLE 2-2. ESTIMATED PRODUCTION AND CHEMICAL COVERAGE
FOR VARIOUS PRODUCTION LEVELS
Producti
(million
on level Mg/yr
lb/year)
Number of
chemicalsa
Percentage of
production
national
covered
453,600
(1,000)
63
N/A
226,800
(500)
102
N/A
113,400
(250)
155
N/A
45,400
(100)
219
92
27,200
(60)
283
94
13,600
(30)
410
N/A
9,100
(20)
506
N/A
4,500
(10)
705
97
aThIS number signifies the number of chemicals with national production
greater than the production level considered.
gep.002 2-6
-------
2.2 REACTOR PROCESSES
2.2.1 Scope of Reactor Processes
The term reactor processes refers to means by which one or more
substances, or reactants (other than air or oxygen-enriched air), are
chemically altered such that one or more new organic chemicals are formed. A
separate control techniques guideline (CTG) document has already been
developed for air oxidation processes; thus, chemicals produced by air
oxidation are not included in the scope of this study. It is estimated that
of 220 high-volume chemicals listed in Appendix A, only 176 involve reactor
processes .3
2.2.2 Chemical Reaction Descriptions
Between 30 and 35 different types of chemical reactions are used to
produce the 176 high-volume chemicals. 4 Some of these chemical reactions are
involved in the manufacture of only one or two of the 176 chemicals while
others (such as halogenation, alkylation, and hydrogenation) are used to make
more than a dozen chemicals. Table 2-3 identifies most of the chemical
reaction types and the number of chemicals produced by each type. In
addition, some of the chemicals produced by reactions listed in Table 2-3 do
not result in process vent streams. In this document, a process vent stream
means a gas stream ducted to the atmosphere directly from a reactor, or
indirectly, through the process product recovery system.
This section briefly describes the major SOCMI chemical reactions
involving reactor processes. Only descriptions of the larger volume
chemicals are included in this discussion. Each chemical reaction
description contains a discussion of the process chemistry that characterizes
the reaction and the major products resulting from the reaction. In
addition, process vent stream characteristics are presented for chemicals
where industry data are available. 5 The emission data profile (EDP) for
reactor processes is included in Appendix B. Descriptions of the major
large-volume chemical reactions are presented in alphabetical order in the
remainder of this section. 6
2.2.2.1 klkylation . Alkylation is the introduction of an alkyl radical
into an organic compound by substitution or addition. There are six general
types of alkylation, depending on the substitution or addition that occurs:
substitution for hydrogen bound to carbon;
gep.002 2-7
-------
TABLE 2-3. RANKING OF CHEMICAL REACTION TYPES
Number of
chemicals
Ranka Chemical reaction type produced
I Pyrolysis 7
2 Alkylation 13
3 Hydrogenation 13
4 Dehydration 5
5 Carboxyl ation/hydroformyl at ion 6
6 Halogenatlon 23
7 Hydrolysis/hydration 8
8 Dehydrogenation 4
9 Esterification 12
10 Dehydrohalogenation I
11 Ammonolysis 7
12 Reforming 4
13 Oxyhalogenation 1
14 Condensation 12
15 Cleavage 2
16 Oxidation 4
17 Hydrodealkylation 2
18 Isomerization 3
19 Oxyacetylation 1
20 Oligomerization 7
21 Nitration 3
22 Hydrohalogenation 2
23 Reduction 1
24 Sulfonation 4
25 Hydrocyanation 2
26 Neutralization 2
27 Hydrodimerization 1
28 Miscellaneous 6
29 P4onreactor processesb 26
aRanking by amount of production for each chemical reaction type.
bChemicals produced solely by air oxidation, distillation, or other
nonreactor processes.
gep.002 2-8
-------
substitution for hydrogen attached to nitrogen;
addition of metal to form a carbon-to-metal bond;
substitution for hydrogen in a hydroxyl group of an alcohol or
phenol;
addition of alkyl halide, alkyl sulfate, or alkyl sulfonate to a
tertiary amine to form a quaternary ammonium compound; and
miscellaneous processes such as addition of a alkyl group to sulfur
or silicon.
The major chemical products of alkylation reactions are ethylbenzene and
cumene. The single largest category of alkylation products is refinery
alkylates used in gasoline production. Other chemical products of alkylation
processes include linear alkylbenzene, tetramethyl lead, and tetraethyl lead.
In general, based on data for production of ethylbenzene, cumene, and
linear alkylbenzene, reactor VOC emissions from alkylation processes appear
to be small compared to other unit processes. The commercial synthesis of
ethylbenzene from ethylene and benzene is an example of the first type of
alkylation reaction described above. The reaction can be carried out in two
ways. One production process involves a low pressure liquid-phase reaction
method using an aluminum chloride catalyst, while the other operates in the
vapor phase at high pressure with various solid catalysts. Data from one
plant that produces ethylbenzer e by liquid-phase alkylation indicate that
reactor Voc emissions are relatively small. (Although no emissions data are
available for the vapor-phase alkylation process, the associated VOC
emissions are expected to be small due to the high operating pressure.)
Reactor offgas from the liquid-phase alkylator is vented to a VOC scrubber
where unreacted benzene is removed from the gas stream and recycled to the
reactor. According to data contained In the EDP, the scrubber vent stream
contains inerts and a small amount of VOC and is vented to the atmosphere at
a rate of approximately 0.5 scm/rn (17 scfm). The estimated heat content of
the vent stream is 6.7 MJ/scm (191 Btu/scf). The VOC emissions to the
atmosphere from the gas scrubber are estimated to be 2.7 kg/hr (16 lb/hr).
Cumene is produced by the vapor-phase catalytic alkylation of benzene
with propylene. The reaction takes place at 690 kPa (100 psia) in the
presence of a phosphoric acid catalyst. No reactor streams are vented, and
thus, no reactor VOC emissions to the atmosphere are associated with this
gep.002 2-9
-------
process at the five cumene plants included in the EDP. Excess benzene
required for the alkylation reaction is recovered by distillation in the
cumene product purification process and recycled to the reactor.
Oodecylbenzenes, also referred to as linear alkylbenzenes (LAB), are
produced by alkylation of mono olefins or chlorinated n-paraffins with
benzene. VOC emissions from both processes are small or nonexistent. In the
case of the mono-olefin production route, only high purity raw materials can
be used, thus eliminating the introduction of dissolved volatiles.
Furthermore, the HF catalyst used in the process is a hazardous chemical and
a potential source of acidic emissions that must be minimized. As a result,
operators of one mono-olefin production route for LAB indicate that process
vent streams have little or no flow associated with them. The alkylation
reaction producing LAB from chlorinated n-paraffins generates HC1 gas and
some VOC by-products. Benzene and HC1 are removed from the process vent
stream before discharging to the atmosphere. Data from a plant producing LAB
from chlorinated n-paraffins indicate that the processes vent stream
following the scrubber is intermittent and emits no VOC to the atmosphere.
2.2.2.2 Ammonolysis . Ammonolysis is the process of forming amines by
using ammonia or primary and secondary arnines as aminating agents. Another
type of ammonolytic reaction is hydroammonolysis, in which amines are formed
directly from carbonyl compounds using an ammonia-hydrogen mixture and a
hydrogenation catalyst. Ammonolytic reactions may be divided into four
groups:
Double decomposition--NH . is split into -NH , and -H; the -NH 2
becomes part of the amine while the -H reacts with a radical such
as Cl that is being substituted;
Dehydration--NH 3 serves as a hydrant, and water and amines result;
Simple addition--both fragments of the NH molecule (-NH and -H)
become part of the newly formed amine; an
Multiple activity--NH 3 reacts with the produced amines resulting in
formation of secondary and tertiary amines.
The major chemical products of ammonolysis reactions are acrylonitrile
and carbamic acid. Reactor emissions from acrylonitrile production involve
air oxidation processes, so they are not discussed here. Two other
categories of ammonolysis products are ethanolamines and methylarnines.
gep.002 2-10
-------
Based on information on ethanolainine production, ammonolytic processes
appear to be a negligiblesource of reactor VOC emissions. Ethanolamines,
including mono-, di-, and triethanolamines, are produced by a simple addition
reaction between ethylene oxide and aqueous ammonia. According to
information on two process units producing ethanolamines, no reactor VOC are
emitted to the atmosphere from this process. The reactor product stream is
scrubbed to recover the excess ammonia required for the reaction before
proceeding to the product finishing unit.
The manufacture of methylamines involves a vapor-phase dehydration
reaction between methanol and ammonia. In addition to methylamines, di- and
trimethy]amjnes are also formed by the reaction. Although no process unit
data for this process are included in the EDP, available information suggests
that reactor VOC emissions from the process are small or neglig-1e. Staged
distillation immediately follows the reactor to separate the coproducts. As
a result, all potential VOC emissions to the atmosphere are associated with
distillation operations and are not reactor related.
2.2.2.3 Carboxylation/Hydroformylation . Carboxylation/hydroformylation
reactions are used to make aldehydes and/or alcohols containing one
additional carbon atom. Carboxylation is the combination of an organic
compound with carbon monoxide. Hydroformylation, often referred to as the
oxo process, is a variation of carboxylation in which olefins are reacted
with a mixture of carbon monoxide and hydrogen in the presence of a catalyst.
Major chemical products of carboxylation/hydroformylation reactions are
acetic acid, n-butyraldehyde, and methanol. -
Carboxylation/hydroformylation processes typically generate relatively
large process vent streams with high heat contents, compared to other unit
processes. Thus, process vent streams from these reactions are normally
combusted.
One carboxylatlon process for acetic acid manufacture reacts liquid
methanol with gaseous carbon monoxide at 20 to 70 MPa (2,900 to 10,200 psia)
in the presence of a catalyst. At one plant that produces acetic acid by
this high pressure process, the reactor products are passed through two gas
liquid separators. The vent from the first separator, consisting primarily
of carbon dioxide and carbon monoxide, is scrubbed and sent to carbon
monoxide recovery. The vent from the second separator is scrubbed to recover
excess reactant and then combined with other waste gas streams and flared.
gep.0 02 2-11
-------
No data are available on the VOC content of the two vent streams. However,
the only point where reactor VOC are potentially emitted to the atmosphere is
the vent from the second separator, which is ultimately discharged to a
fI are.
In the oxo process for producing n-butyraldehyde, propylene is reacted
with synthesis gas (CO and H 2 ) in the liquid phase at 20 to 30 MPa (2,900 to
4,400 psia). An aromatic liquid such as toluene is used as the reaction
solvent. A relatively large amount of VOC is contained in the process vent
stream for this reaction. Industry information suggests that this process
has generally been replaced by an unnamed, low VOC-emitting process. No
data, however, are available for this process. Information from one plant
producing n-butyraldehyde by the oxo process indicates that the reactor vent
stream consists of hydrogen, carbon monoxide, and VOC and is used as fuel in
an industrial boiler. Prior to combustion, the estimated vent stream flow
rate at this plant is 21 scm/rn (730 scfm) and the heating value is 46 MJ/scm
(1,233 Btu/scf). The VOC flow rate prior to combustion is approximately
1,100 kg/hr (2,394 lb/hr).
2.2.2.4 Cleavage . Acid cleavage is the process by which an organic
chemical is split into two or more compounds with the aid of an acid
catalyst. This chemical reaction is associated with production of two major
chemicals, phenol and acetone.
Production of phenol and acetone begins with oxidation of cumene to
cumene hydroperoxide. The cumene hydroperoxide is usually vacuum distilled
to remove impurities, and is then agitated in 5 to 25 percent sulfuric acid
until it cleaves to phenol and acetone. The mixture is neutralized to remove
excess sulfuric acid, phase separated, and distilled. One process unit
producing phenol and acetone from cumene hydroperoxide reports little or no
flow in the process vent stream at the cleavage reactor. High purity of the
cumene hydroperoxide intermediate is the major reason for this no flow
vent.
2.2.2.5 Condensation . Condensation is a chemical reaction in which two
or more molecules combine, usually with the formation of water or some other
low-molecular weight compound. Each of the reactants contributes a part of
the separated compound. Chemical products made by condensation include
acetic anhydride, bisphenol A, and ethoxylate nonyiphenol.
gep.002 2-12
-------
Reactor emissions to the atmosphere from condensation processes are
expected to be small. Available data indicate that emissions from acetic
anhydride production are minimized by combustion of the process vent stream.
There are no reactor VOC emissions from bisphenol, or ethoxylated nonyiphenol
production. (Bisphenol A has emissions from distillation operations only.)
Acetic anhydride is produced by the condensation of acetic acid and
ketene. Ketene for the reaction is made by pyrolysis of acetic acid. After
water removal, the gaseous ketene is contacted with glacial acetic acid
liquid in absorption columns operated under reduced pressure. The process
vent stream from the absorber contains acetic acid, acetic anhydride, traces
of ketene, and any reaction by-product gases generated. The VOC content of
the vent stream is particularly dependent on impurities that may be contained
in the acetic acid feed, such as formic or propionic acid, that cause side
reactions to occur. Scrubbers are normally used to remove acetic acid and
acetic anhydride from the vent stream. At two process units producing acetic
anhydride, the vent streams are burned as supplemental fuel in pyrolysis
furnaces. No data on the vent stream characteristics or VOC content were
provided for one of these process units; however, data from the other source
on acetic anhydride production identify the major components of the process
vent stream after scrubbing to be carbon monoxide, carbon dioxide, and VOC.
The typical VOC flow rate of the vent stream after scrubbing was estimated to
138 kg/hr (305 lb/hr), based on assumptions about the purity of the
reactants.
Bisphenol A is produced by reacting phenol with acetone in the presence
of HC1 as the catalyst. The reaction produces numerous by-products that must
be eliminated in order to generate high purity bisphenol A. Removal of these
by-products requires distillation and extraction procedures, and thus no
reactor vents, to the atmosphere are associated with this process.
2.2.2.6 Deiivdration . Dehydration reactionsa are a type of
decomposition reaction in which a new compound and water are formed from a
single molecule. The major chemical product of dehydration is urea.
aihis process refers to chemical dehydration and does not include physical
dehydration in which a compound is dried by heat. Stucco produced by
heating gypsum to remove water is an example of physical dehydration.
gep002 2-13
-------
Commercial production of urea is based on the reaction of ammonia and
carbon dioxide to form ammonium carbamate, which in turn is dehydrated to
urea and water. The unreacted ammonium carbarnate in the product stream is
decomposed to ammonia and carbon dioxide gas. A portion of the ammonia is
urea and water. The unreacted ammonium carbamate in the product stream is
removed from the process vent stream, leaving primarily carbon dioxide to be
vented to the atmosphere. No data are included in the EDP for VOC emissions
from urea production, but one study indicates that VOC emissions from urea
synthesis are negligible. 7 Urea Is the only chemical of those that use
dehydration to be included in the EDP.
2.2.2.7 Dehycirpgenation . Dehydrogenatlon is the process by which a new
chemical is formed by the removal of hydrogen from the reactant. Aldehydes
and ketones are prepared by the dehydrogenation of alcohols. Chemicals
produced by dehydrogenation processes include acetone, bivinyl,
cyclohexanone, methyl ethyl ketone (MEK), and styrene.
In general, dehydrogenation processes produce relatively large,
hydrogen-rich process vent streams that are either used as a fuel in process
heaters or industrial boilers or as a hydrogen feed for other processes. The
two process units for which data are available have high heat content process
vent streams. These occur as a result of the hydrogen generated in the
dehydrogenation reaction. Although these process vent streams can be quite
large, there is generally little VOC contained in them.
Acetone and MEK are produced by similar processes involving the
catalytic dehydrogenation of alcohols. The emissions profile contains four
process units in the EDP that produce MEK via the dehydrogenation of
sec-butanol. In all cases a hydrogen-rich process vent stream is produced.
One process unit uses a VOC scrubber to remove MEK and sec-butanol from the
process vent stream prior to flaring. In all four process units, reactor VOC
emissions are well controlled or nonexistent. One acetone production process
unit has an additional reactor process vent stream on a degasser directly
following the reactor. This degasser reduces the pressure on the product
stream to allow storage of the product at atmospheric pressure. The pressure
reduction step causes dissolved hydrogen and low boiling point VOC to escape
from the liquid-phase product. This purge stream, which is relatively small,
is routed to a water scrubber to remove some VOC before it is released to the
atmosphere. This is the only acetone production process unit in the EDP that
gep.002 2-14
-------
stores the acetone as an intermediate product, and as a result, it is the
only plant with a degasser process vent stream.
Two process units in the EOP manufacture styrene via the hydrogenation
of ethylbenzene. One plant produces a hydrogen-rich (90 percent by volume)
process vent stream that is normally combusted to recover the heat content.
The other plant produces a process vent stream that is first condensed and
then combusted in a flare system. The vent stream flow rate is relatively
large [ 16 scm/rn (574 scfm)]; the stream contains 23 percent VOC including
toluene, benzene, ethylbenzene, and styrene. The heat content is estimated
to be 11 MJ/scrn (300 Btu/scf), which would support combustion without the
addition of supplemental fuel.
2.2.2.8 Dehydrohalogenation . In the dehydrohalogenation process, a
hydrogen atom nd a halogen atom, usually chlorine, are removed from one or
more reactants to obtain a new chemical. This chemical reaction is used to
produce vinyl chloride, vinylidene chloride, and cyclohexene.
Vinylidene chloride is made by dehydrochiorinating 1,1,2-trichioroethane
with lime or aqueous sodium hydroxide. The reactor product is separated and
purified by distillation. The process vent stream at one vinylidene chloride
process unit is incinerated and then scrubbed with caustic before discharging
to the atmosphere. Before incinerating, the vent stream flow rate is
estimated to be 0.28 scm/rn (10 scfrn) and the heat content is 22 MJ/scm
(660 Btu/scf). The VOC emission rate of the vent stream is approximately
19 kg/hr (41 lb/hr). At a second plant producing vinylidene chloride, no
reactor vent streams are used. The process vent streams are associated with
distillation operations.
2.2.2.9 Esterjfjcptipn . Esterificatlon is the process by which an
ester is derived from an organic acid and an alcohol by the exchange of the
ionizable hydrogen atom of the acid and an organic radical. The major
chemical product of esterification Is dimethyl terephthalate. Other
esterificatlon products Include ethyl acrylate and ethyl acetate.
VOC emissions associated with esterification processes are small, based
on information on the production of methyl methacrylate, ethyl acrylate, and
ethyl acetate.
Ethyl acrylate is produced by the catalytic reaction of acrylic acid and
ethanol. The vent stream flow rate from reactor equipment producing ethyl
acrylate in one process unit is reported to be 2.1 scm/rn (75 scfm). The heat
gep.002 2-15
-------
content for this stream is estimated to be 3.8 MJ/scm (102 Btu/scf). The VOC
emission rate of the vent stream is 2.8 kg/hr (6.1 lb/hr).
Methyl methacrylate is produced by esterifying acetone and hydrogen
cyanide with methanol. Limited information is available on reactor VOC
emissions from this process. The EDP includes one plant producing methyl
methacrylate; the process vent stream at this plant is combusted in an
incinerator. Although the incinerator is used primarily to destroy VOC in
offgases from another plant process, combustion of the methyl methacrylate
process vent stream in the incinerator allows the plant to use less
supplemental fuel by recovering the heat content of the vent stream. No vent
stream flow rate or heat content data are available for this plant; however,
the VOC emission rate is estimated to be very low [ 0.05 kg/hr (0.1 lb/br)].
Ethyl acetate production involves an esterification reaction between
acetic acid and ethanol. Two process units producing ethyl acetate are
included in the EDP. Following condensation of the process vent stream to
recover product, both process units discharge the vent stream to the
atmosphere. Vent stream data reported by one of the process units indicate
the VOC content of the vent stream to be low, i.e., 0.2 kg/hr (0.5 lb/hr).
2.2.2.10 Halogenation . Halogenation is the process whereby a halogen
(chlorine, fluorine, bromine, iodine) is used to introduce one or more
halogen atoms into an organic compound. (Reactions in which the halogenating
agent is halogen acid, such as hydrochloric acid, are included in a separate
unit process called hydrohalogenation.) The chlorination process is the most
widely used halogenation process in industry; fluorination is used
exclusively in the manufacture of fluorocarbons. The major products of
halogenation reactions are ethylene dichioride, phosgene, and chlorinated
methanes and ethanes.
Reactor VOC emissions from halogenation reactions vary from no emissions
to 51 kg/hr (113 lb/hr). Most chlorination reactors vent to scrubbers or
condensers where HC1 generated in the chlorination reaction is removed. Some
VOC reduction occurs along with HC1 removal by these devices. Also, some
vent streams are combusted prior to discharge to the atmosphere. Purity of
the feed materials (including chlorine) is a major factor affecting the
amount of reactor VOC emissions vented to the atmosphere.
Ethylene dichioride can be produced by direct chlorination of ethylene
or by oxychiorination of ethylene. Most ethylene dichioride is currently
gep.002 2-16
-------
made by a balanced process that combines direct chlorination of ethylene
and oxychiorination of ethylene. The direct chlorination process reacts
acetylene-free ethylene and chlorine in the liquid phase. The
oxyhalogenation process using oxygen for the manufacture of ethylene
dichioride is included in the reaction description for oxyhalogenation.
Reactor VOC emissions from ethylene dlchloride production by direct
chlorination vary according to process vent stream treatment. HC1 is
generated by the chlorination reaction and is typically removed from the
process vent stream by a caustic scrubber. The vent stream following the
scrubber may be discharged to the atmosphere, recycled to the reactor, or
incinerated. The EDP contains information on three ethylene dichioride
plants that use the direct chlorination process as part of the balanced
process. The process vent stream characteristics for the three plants
indicate a range of gas flow rates of 1.1 to 7.6 scm/rn (40 to 267 scfm) and a
range of heat contents of 1.5 to 46 MJ/scm (40 to 1,228 Btu/scf). The
process vent stream with the highest heat content (i.e., 46 MJ/scm) is
incinerated before venting to the atmosphere.
The fluorination reactions producing dichiorodifluoromethane and
trichiorotrifluoroethane involve the replacement of a chlorine in carbon
tetrachioride with fluorine. At two plants surveyed, no reactor VOC
emissions are associated with these fluorination processes. The two plants
report no process vent stream discharges to the atmosphere. Instead, process
vent streams occur from distillation operations.
2.2.2.11 Hydrodealkylation . Hydrodealkylation is the process by which
methyl groups, or larger alkyl groups, are removed from hydrocarbon molecules
and replaced by hydrogen atoms. Hydrodealkylation is primarily used in
petroleum refining to upgrade products of low value, such as heavy reforinate
fractions, naphthalenjc crudes or recycle stocks from catalytic cracking. In
particular, hydrodealkylatlon is used in the production of high purity
benzene and naphthalene from alkyl aromatics such as toluene.
The EDP contains no information on emissions from hydrodealkylation
processes. In the case of benzene production, the process vent stream
containing unconverted toluene is recycled to the reactor, and no reactor VOC
emissions are vented. 8
2.2.2.12 Hydrohaippenation , Hydrohalogenation is the process in which
a halogen atom Is added to an organic compound using a halogen acid, such as
gep.002 2-17
-------
hydrogen chloride. The major chemical products of this reaction are methyl
chloride and ethyl chloride.
The predominant share of methyl chloride is produced by the vapor-phase
reaction of methanol and hydrogen chloride. 9 In three process units the
process vent stream is condensed to remove excess HC1; some VOC is also
removed by the condensers. Of the nine plants that manufacture methyl and
ethyl chloride included in the EDP, five have no reactor process vent
streams, one discharges the noncondensibles directly to the atmosphere, and
three route the noncondensible stream to combustion devices. The VOC content
of a methyl chloride vent stream is 76 kg/hr (168 lb/hr).
2.2.2.13 Hydrolysis/Hydration . Hydrolysis is the process in which
water reacts with another substance to form two or more new substances.
Hydration is the process in which water reacts with a compound without
decomposition of the compound. These processes are a major route in the
manufacture of alcohols and glycols, such as ethanol, ethylene glycols, and
propylene glycols. Another major product of hydrolysis is propylene oxide.
Propylene oxide is produced by hydrolysis of propylene chiorohydrin with
an alkali (usually NaOH or CA(OH) 2 ). The product vent stream is condensed to
remove the propylene oxide product and the noncondensibles are discharged to
the atmosphere. Data from a process unit that produces propylene oxide
indicate the flowrate of the vent stream following the condenser to be about
2.8 scm/m (99 scfm) and the estimated VOC emissions to the atmosphere to be
0.05 kg/hr (0.1 lb/hr).
Sec-butyl alcohol is produced by absorbing n-butenes in sulfuric acid to
form butyl hydrogen sulfate that is then hydrolyzed to sec-butyl alcohol and
dilute sulfuric acid. The reactor product is steam stripped from the dilute
acid solution and purified by distillation. Information on the sec-butyl
alcohol production at one process unit does not indicate any specific process
vents. All process vents at this process unit are reported to be flared so
that any reactor VOC emissions would be combusted.
In general, production of chemicals by hydrolysis/hydration processes
generate little or no reactor VOC emissions. Based on production information
for ethylene glycol and propylene glyco1, these hydration reactors do not
have process vent streams associated with them. Ethylene glycol and
propylene glycol are produced by hydrating ethylene oxide and propylene
oxide, respectively. The reactions for both chemicals result in production
gep.002 2-18
-------
of di- and tri-glycols as coproducts. Following the reactor, the glycols are
separated and purified by distillation. No reactor VOC emissions are vented
to the atmosphere from the glycol process units in the EDP.
2.2.2.14 Hydrogenation . Hydrogenation is the process in which hydrogen
is added to an organic compound. The hydrogenation process can involve
direct addition of hydrogen to the double bond of an unsaturated molecule,
replacement of oxygen in nitro-containing organic compounds to form amines,
and addition to aldehydes and ketones to produce alcohols. The major
chemical products of hydrogenation reactions include cyclohexane, aniline,
n-butyl alcohol, hexamethylene diamine, 1,4-butanediol, cyclohexanone, and
toluene diamine.
In general, reactor VOC emissions from hydrogenation reactions appear to
be small in comparison with other chemical reactions. However, combustion
devices are typically associated with the vent streams of hydrogenation
processes. Excess hydrogen in these vent streams makes them suitable for
combustion in most cases.
Hexamethylene diamine is made by hydrogenation of adiponitrile. Reactor
VOC emissions from hexamethylene diamine production are small according to
information on three process units in the EDP. Excess hydrogen used in the
reaction is recovered from the vent stream and recycled to the reactor. At
two of these process units, the process vent streams are used as fuel in a
plant boiler. The average vent stream flowrate following hydrogen recovery
at the three process units is 14.0 scm/m (496 scfm) and the average heat
content is 21 MJ/scm (562 Btu/scf). The VOC content of the noncombusted vent
stream at the process unit that does not use combustion is approximately
3 kg/hr (6.6 lb/hr). The VOC content of the combusted streams at the other
two process units is estimated to be negligible prior to combustion.
Cyclohexane is produced by the liquid-phase hydrogenation of benzene.
In this process, both cyclohexane and hydrogen are recovered from the process
vent stream. Information from one cyclohexane plant Indicates that there is
usually no flow in the vent stream following product and hydrogen recovery.
The process vent stream after these recovery systems is discharged to the
atmosphere only during emergencies, and the stream is vented to the flare
system for VOC destruction during such upset conditions.
Cyclohexane, 1,4-butanediol, and toluene diamine production involve the
hydrogenation of phenol, 2-butyne-1,4-diol, and 2,4-dinitrotoluene,
gep.002 2-19
-------
respectively. The process vent stream for these hydrogenation reactions are
ultimately combusted in incinerators, boilers, or flares. Precombustion vent
stream characteristic data are available for only one of these vent
streams--n-butyl alcohol.
2.2.2.15 Isomerization . During isomerization, organic compounds are
converted by heat and a catalytic reaction that changes the arrangement of
atoms in a molecule, but not the number of atoms. Catalysts include aluminum
chloride, antimony chloride, platinum, and other metals. Temperatures range
from 400 to 480°C (750 to 900°C), and pressures range from 7 to 50 atm.°
Isomerizatlon is used in petroleum refining to convert straight-chain
hydrocarbons into branched-chain hydrocarbons. An example Is the conversion
of n-butane to isobutane. Emissions from this process would be expected to
be small, as with other high-temperature and high-pressure reactor processes
in the EDP.
2.2.2.16 Neutralization . Neutralization is a process used to
manufacture linear alkylbenzene; benzenesulfonic acid, sodium salt;
dodecylbenzene sulfonic acid, sodium salt; and oil-soluble petroleum
sulfonate, calcium salt. Diagrams of all of the production processes show no
reactor process vent streams. 12
2.2.2.17 Nitration . Nitration is the unit process in which nitric acid
is used to introduce one or more nitro groups (NO 2 ) into organic compounds.
Aromatic nitrations are usually performed with a mixture of nitric acid and
concentrated sulfuric acid. Nitrobenzene and dinitrotoluene are the major
products of nitration reactions.
Nitrobenzene production involves the direct nitration of benzene using a
mixture of nitric acid and sulfuric acid. Only a small quantity of
by-products, primarily nitrated phenols, are produced by the reaction. The
reaction is normally blanketed with nitrogen gas to reduce fire and explosion
hazards. At one process unit producing nltrobenzene, waste acid is removed
from the reactor product stream by a separator followed by recovery of excess
benzene by distillation. Vent streams from the reactor and separator are
combined and discharged directly to the atmosphere. Industry Information
suggests that a new, but unnamed, process without reactor process vents is
now in operation. No data, however, are available for this process. The
main components of the combined vent streams are nitrogen and benzene. The
EDP nltrobenzene nitration process has a combined vent stream flowrate
gep.002 2-20
-------
estimated to be 0.38 scm/rn (13 scfm) and an approximate heat content of
16 MJ/scm (434 Btu/scf). VOC emissions to the atmosphere from the vent
streams are 8.6 kg/hr (19 lb/hr).
Dinitrotoluene is produced by nitration of toluene in two stages using
different acid mixtures. As In the case of nitrobenzene production, the
waste acid is separated and recycled. Two process units producing
dinitrotoluene operate scrubbers on the reactor vent streams to remove VOC.
Following scrubbing, one plant discharges the vent stream to the atmosphere
while the other incinerates the vent stream. No data are available on the
characteristics of the incinerated vent stream. The flow rate of the
nonincinerated vent stream following the scrubber is estimated to be 23 scm/ni
(822 scfm). Heat content of the vent stream is negligible. Estimated VOC
emissions to the atmosphere are 0.05 kg/hr (0.1 lb/hr).
2.2.2.18 Oligomerization . In the oligomerization process, molecules of
a single reactant are linked together to form larger molecules consisting of
2 to about 10 of the original molecules. Oligomerization is used to make
several chemicals including alcohols, dodecene, heptene, nonene, and octene.
Typically, it is a high-temperature, high-pressure process. 3 14 Diagrams
for all of the chemical production processes show no reactor process vent
streams 5 - 7 Other chemical unit processes with similar high-pressure
characteristics, such as pyrolysis, emit little or no VOC.
2.2.2.19 Oxidation . Oxidation of organic chemicals is the addition of
one or more oxygen atoms into the compound. The oxidation processes
considered here include pure oxygen oxidation and chemical oxidation. An
example of pure oxygen oxidation is the production of ethylene oxide using
pure oxygen and ethylene. The production of adipic acid from nitric acid is
an example of chemical oxidation.
Ethylene oxide can be produced by oxidation using air or pure oxygen.
In the pure oxygen process, ethylene, oxygen and recycled gas are reacted
under pressures of 1 to 3 MPa (150 to 440 psla). Two reactor process vent
streams are reported by one process unit that produces ethylene oxide by pure
oxygen oxidation. At this plant, the reactor effluent is sent through an
ethylene oxide absorber. The offgas from this absorber is routed to the
carbon dioxide removal system. A portion of the vent stream from the carbon
dioxide absorber system is recycled to the reactor while the remainder is
used as fuel in industrial boilers. The carbon dioxide absorber liquid is
gep.002 2-21
-------
regenerated, and the removed carbon dioxide is vented to the atmosphere. The
portion of the vent stream from the CO 2 absorber that is sent to a boiler has
an approximate flow rate of 176 scm/rn (6,200 scfm) and a heat content of
13 MJ/scm (340 Btu/scf). The estimated discharge rate to the atmosphere from
the CO 2 absorber liquid regenerator vent is 345 scm/rn (12,187 scfm), and the
heat content is 0.15 MJ/scf (4 Btu/scf). Prior to combustion in the boiler,
the VOC flow rate of the first vent stream is 0.59 kg/hr (1.3 lb/hr). For
the uncontrolled vent stream, VOC emissions to the atmosphere are estimated
to be 59 kg/hr (130 lb/hr).
In adipic acid production, an alcohol ketone mixture is oxidized using
nitric acid. Adipic acid from the reactor is stripped of nitrogen oxides
produced by the reaction and then refined. Of the three process units
producing adipic acid included in the EDP, two of the process unit discharge
the stripper offgas to the atmosphere. Vent stream flow rates at the three
process units are estimated to range from 24 to 132 scm/rn (848 to
4,653 scfm). The heating values of all three vent streams are negligible and
there are no VOC emissions from any of these process units.
2.2.2.20 Oxyacetylation . Oxyacetylation is the process in which oxygen
and an acetyl group are added to an olefin to produce an unsaturated acetate
ester. Oxyacetylation is used in a new commercial process to make vinyl
acetate.
Vinyl acetate is produced from ethylene, acetic acid, and oxygen.
Reactor VOC emissions from one vinyl acetate production process unit are
small. The estimated vent stream flow rate and heating values are 0.2 scm/rn
(7 scfm) and 15 MJ/scm (407 Btu/scf), respectively. The VOC flow rate prior
to combustion is approximately relatively low (0.1 lb/hr).
2.2.2.21 Oxyhalogenation . In the oxyhalogenation process, a halogen
acid is catalytically oxidized to the halogenated compound with air or
oxygen. The main oxyhalogenation process is oxychiorination, in which
hydrogen chloride is catalytically oxidized to chlorine with air or oxygen.
(Oxychlorination processes using air are included in the analyses for air
oxidation processes.) The oxychlorination process is used in the production
of ethylene dichioride.
As described previously, most ethylene dichioride is produced by the
balanced process that combines oxychiorination and direct chlorination of
ethylene. In the oxychiorination reaction, ethylene, hydrogen chloride, and
gep.002 2-22
-------
oxygen or air are combined. Emissions from air oxychiorination reactions
used in ethylene dichioride production are regulated by the air oxidation
processes NSPS. Only emissions from oxygen oxychiorination reactions are
considered here. At one process unit producing ethylene dichioride by
oxychiorination using oxygen, the reactor effluent is condensed, and excess
ethylene is recycled to the reactor. A small portion of the recycle stream
is vented to prevent a buildup of impurities. The vent stream is incinerated
in order to comply with State Implementation Plans (SIPs) and to reduce vinyl
chloride emissions that are regulated under a NESHAP. The vent stream flow
rateprior to incineration is approximately 8.5 scm/rn (304 scfm) and the
estimated heat content is 27 NJ/scm (713 Btu/scf). The VOC flowrate in the
vent stream is estimated to be 340 kg/hr (748 lb/hr). Following
incineration, the estimated VOC emissions to the atmosphere are 6.8 kg/hr
(15 lb/hr).
2.2.2.22 Phosgenation . Phosgenation is the process in which phosgene
(COd 2 ) reacts with an amine to form an isocyanate, or with an alcohol to
form a carbonate. Toluene diisocyanate is the major chemical product of this
chemical unit process.
Toluene diisocyanate is produced by phosgenating toluene diamine. At
one process unit, the reactor vent is routed through distillation columns for
product/by-product recovery and purification. Thus, no reactor VOC emissions
are vented to the atmosphere from the process. 8
2.2.2.23 Pyrolysis . Pyrolysis is a chemical reaction in which the
chemical change of a substance occurs by heat alone. Pyrolysis includes
thermal rearrangements into Isomers, thermal polymerizations, and thermal
decompositions. The major use of this process is In the production of
ethylene by the steam pyrolysis of hydrocarbons. Other pyrolysis products
include ketene (a captive intermediate for acetic anhydride manufacture) and
by-products of ethylene production such as propylene, bivinyl, ethylbenzene,
and styrene.
Ethylene and other olef ins can be produced from a variety of hydrocarbon
feeds, including natural gas liquors, naphtha, and gas-oil. Maximum ethylene
production is achieved by adjusting furnace temperature and
steam-to-hydrocarbon ratios. Pyrolysis gases from the furnace are cooled,
compressed, and separated into the desired products. As In refinery
operations, the economics of olefins production make recovery of gaseous
gep.002 2-23
-------
products desirable. Thus, process vent streams to the atmosphere are
minimized. The ethylene process unit included in the EDP reports no process
vent streams to the atmosphere.
The first step in the manufacture of acetic anhydride is production of
ketene. Ketene and water are produced by pyrolysis of acetic acid. At two
plants producing acetic anhydride, the pyrolysis products are cooled and
separated prior to acetic anhydride formation. No process vent streams are
associated with the pyrolysis reaction to produce ketene.
2.2.2.24 Sulfonation . Sulfonation is the process by which the sulfonic
acid group (SO 2 OH), or the corresponding salt, or sulfonyl halide is attached
to a carbon atom. Sulfonatlon can also be used to mean treatment of any
organic compound with sulfuric acid, regardless of the nature of products
formed.
Isopropyl alcohol is made by sulfonation of propylene to isopropyl
hydrogen sulfate and subsequent hydrolysis to isopropyl alcohol and sulfuric
ac I d.
Many detergents are made by the sulfonation of mixed linear
alkylbenzenes. These include benzenesulfonic acid and dodecylbenzene
sulfonic acid. To manufacture these, the linear alkylbenzenes are sulfonated
with SO 3 or oleums of various strengths. One process uses diluted SO 3 vapor
in a continuous operation. The reaction and heat removal occurs in a thin
film on a cooled reactor surface. The process forms almost entirely the
p-sulfonic acid. 9
The EDP contains emissions data on one sulfonation process unit
controlled only with a caustic scrubber. It has extremely low uncombusted
VOC emissions (0.05 kg/hr or 0.1 lb/hr) even though the vent stream flow rate
is relatively large (52 scm/rn or 1,863 scfm).
2.3 DISTILLATION OPERATIONS
Distillation is the most comonly used separation and purification
procedure in refineries and large organic chemical manufacturing plants. The
fundamental operating principles for a distillation column are the same
regardless of the application. This section brIefly discusses some of the
fundamental principles involved In distillation to provide a better
understanding of operating characteristics of distillation units and causes
of VOC emissions from these units.
gep.002 2-24
-------
2.3.1 Tv es of Distillation
Distillation is an operation separating one or more feed strearn(s)b
into two or more product streams, each product stream having component
concentrations different from those in the feed stream(s). The separation is
achieved by the redistribution of the components between the liquid- and
vapor-phase while the less volatile components(s) concentrate in the
liquid-phase. Both the vapor- and liquid-phase originate predominantly by
vaporization and condensation of the feed stream.
Distillation systems can be divided into subcategories according to the
operating mode, the operating pressure, the number of distillation stages,
the introduction of inert gases, and the use of additional compounds to aid
separation. A distillation unit may operate in a continuous or a batch mode.
The operating pressures can be below atmospheric (vacuum), atmospheric, or
above atmospheric (pressure). Distillation can be a single stage or a
multistage process. Inert gas, especially steam, is often introduced to
improve separation. Finally, compounds are often introduced to aid in
distilling hard-to-separate mixture constituents (azeotropic and extractive
distillation).
Single stage batch distillation is not common in large scale chemical
production but is widely used in laboratories and pilot plants. Separation
is achieved by charging a still with material, applying heat and continuously
removing the evolved vapors. In some instances, steam is added or pressure
is reduced to enhance separation.
Single stage continuous distillation is referred to as flash
distillation (Figure 2-3). It is generally a direct separation of a
component mixture based on a sudden change in pressure. Since flash
distillation is a rapid process, steam or other components are not added to
improve separation. A flash distillation unit is frequently the first
separation step for a stream from the reactor. The heated products from a
reaction vessel are pumped to an expansion chamber. The pressure drop across
the valve, the upstream temperature, and the expansion chamber pressure
govern the separation achieved. The light ends quickly vaporize and expand
away from the heavier bottom fractions, which remain in the liquid-phase.
b
For batch distillation, the word charge should be used in place of
stream t , wherever applicable.
gep.002 2-25
-------
Feed
Figure 2-3. Flash distillation.
Ov.rh.ads (Os .) Qr
LJght Ends
Pressure Control
Valve
Flash Distillation
Column
Bottoms (Uquld) or
Heavy Ends
gep.002
2-26
-------
The vapors rise to the top of the unit and are removed. Bottoms are pumped
to the next process step.
Fractionating distillation is a multistage distillation operation. It
is the most commonly used type of distillation unit in large organic chemical
plants, and it can be a batch or a continuous operation. At times, inert
carriers (such as steam) are added to the distillation column. Fractionating
distillation is accomplished by using trays, packing, or other internals in a
vertical column to provide multiple intimate contact of ascending vapor and
descending liquid streams. A simplified block flow diagram, of a
fractionation column is shown in Figure 2-4. The light end vapors evolving
from the column are condensed and collected in an accumulator tank. Part of
the distillate is returned to the top of the column so it can fall
countercurrent to the rising vapors. For difficult separations, additional
compounds may be added to achieve the desired separation. This is commonly
referred to as extractive distillation and is typically used in lubricant oil
refining. A desorption column is very similar to a fractionating
distillation column except that it does not use a reflux condenser.
2.3.2 Fundamental Distillation Conceots
The emissions from distillation units are dependent on the size,
operating conditions and types of components present. Therefore, the design
parameters and selection of operating conditions are discussed in this
section to provide a better understanding of the emissions.
The separation of a mixture of materials into one or more individual
components by distillation is achieved by selecting a temperature and
pressure that allow the coexistence of vapor and liquid phases in the
distillation column. Distillation is described as a mass-transfer operation
involving the transfer of a component through one phase to another on a
molecular scale. The mass transfer Is a result of a concentration difference
or gradient stimulating the diffusing substance to travel from a high
concentration zone to one of lower concentration until equilibrium is
reached. The maximum relative concentration difference between distillation
materials in the vapor- and liquid-phases occurs when a state of equilibrium
is reached. The equilibrium state is reached when the concentrations of
components in the vapor-phase and liquid-phase, at a given temperature and
pressure, do not change regardless of the length of time the phases stay in
contact.
gep.002 2-27
-------
LO
V I
V2
Li
V3
F..d V4
L
V5
ye
VVapor _________
LaUqu d
VS
Li R1 ux
Coolar*
Ru dus u or
_.nkD
(Bottom Producti)
D .
Hasting Midlum (Ov.rh.ad Products)
(8oltom Products)
Figure 2-4. A conventional fractionating column.
gep.002 2-28
-------
For an ideal system, the equilibrium relationship is determined using
the law of Dalton and Raoult. Daltons law states that the total pressure of
a mixture of gases is equal to the sum of the partial pressures of each gas
constituent:
Pt E p 1 (2.1)
I
where:
Pt Total pressure.
p 1 Partial pressure of each gas constituent.
n Number of constituents.
Daltons Law further states that the partial pressure of each ideal gas
constituent is proportional to the mole fraction (relative percentage) of
that gas in an ideal solution:
P 1 Pt (2.2)
where:
y = Mole fraction.
Raoults Law states the relationship for ideal solutions between the partial
pressure of a mixture constituent in the vapor phase and its composition in
the liquid-phase in contact. When the vapor phase is at equilibrium with the
solution, the partial pressure of the evolved component is directly
proportional to its vapor pressure (at the same temperature) and its mole
fraction in the solution:
p 1 x 1 p, (2.3)
where:
x Mole fraction In the solution.
p 1 Vapor pressure of the pure substance at the same temperature.
These statements may be combined to given an equilibrium vaporization ratio
(K value). A simplified expression for this ratio is:
K It (2.4)
This equilibrium constant is used to evaluate the properties that affect
gas-liquid equilibrium conditions for Individual components and mixtures.
The K value represents the distribution ratio of a component between the
gep.002 2-29
-------
vapor and liquid-phase at equilibrium. The K value for various materials may
be calculated using thermodynamic equations of state or through empirical
methods (suitably fitting data curves to experimental data). This constant
is an extremely important tool for designing distillation units (determining
required temperatures, pressures, and column size).
Another basic distillation concept is the separation factor or relative
volatility a ) of system components. This is the equilibrium ratio of the
mole fractions of component i to some component j in the vapor and liquid
phase:
z / y. (2.5)
ii x 1 x
This is expressed as the ratio of the vapor pressures for an ideal mixture:
P. (2.6)
au =
3
The ratio is a measure of the separability of the two components to be
separated and is very important in designing distillation equipment. In the
case of a binary system, the two components to be separated are the two
components present in the feed. In a multicomponent system, the components
to be separated are referred to as heavy key and light key. The heavy
key is the most volatile component desired to be present in significant
quantities in the bottom products or the residue. Similarly, light key is
the least volatile compound desired to be present in significant quantities
in the overhead products. Generally, separation by distillation becomes
uneconomical when the relative volatility of the light key and heavy key is
less than 1.05.20
The operating temperature and pressure in a distillation unit are
interrelated. A decision made for the value of one of these parameters also
determines the value of the other parameter. Essentially, the pressure and
gep.002 2-30
-------
temperature are chosen so that the dewpointC condition for the overhead
products and the bubble 01 td conditions for the bottom products can be
present inside the distillation unit. The actual decision on these two
conditions is predicated upon economic considerations and is made after
evaluating the following items:
The relative volatility, au, of the components. A lower pressure
in the column increases the value of a and improves separation.
This would result in a shorter fractioti ting column.
The effect of pressure on vapor volume in the distillation unit.
The vapor volume increases as the pressure decreases, requiring a
larger diameter vessel.
The effect of pressure on column wall thickness. Higher pressures
require increased wall thickness and raise costs.
Cost of achieving desired temperature and pressures. The cost of
changing the pressure and that of changing the temperature are
considered independently since these two costs are not
proportional.
CThe dew-point temperature is the temperature at which the first droplet of
liquid is formed as the vapor mixture is coiled at constant pressure, and
the dew-point pressure is that at which the first droplet of liquid is
formed as the pressure is increased on the vapor at constant temperature.
Mathematically, the dew point is defined by:
E x 1 1.0 E 1 (2.7)
dlhe bubble-point temperature is the temperature at which the first bubble
of vapor is formed on heating the liquid at constant pressure. The
bubble-point pressure is the pressure at which the first bubble of vapor is
formed on lowering the pressure on the liquid at constant temperature.
Mathematically, the bubble point is defined by:
n
y. * 1.0 E K 1 x 1 (2.8)
1
gep.002 2-31
-------
The thermal stability limit of the compounds being processed. Many
compounds decompose, polymerize, or react when the temperature
reaches some critical value. In such cases it is necessary to
reduce the design pressure so that this critical reaction
temperature is not reached at any place in the distillation unit.
Data on the use of vacuum during distillation were compiled for a number
of major chemicals to predict the use of vacuum for distillation. The
physical properties of the compounds using vacuum during distillation were
compared with those of compounds not using vacuum, with the following
conclusions:
Compounds with a melting point less than -10°C and with a boiling
point greater than 150°C are likely to be distilled under vacuum.
If the boiling point of a compound is less than 50°C then it is
likely to be distilled at or above atmospheric pressure.
For the separation of compounds with boiling points between 50°C
and 150°C, the use of vacuum depends on the thermal operable limit
of the compound (i.e., temperature ra e in which the compound does
not decompose, polymerize, or react).
In designing a distillation system, once the operating temperature and
pressure are established, the type of distillation is considered. Flash
distillation is preferred for separation of components with a high relative
volatility. Steam is the most frequently used heat source for column
distillation since using a direct fired heater (although used in some
instances) could create a dangerous situation. Steam is also used for
distilling compounds that are thermally unstable or have high boiling points.
Azeotropic and extractive distillation are used to separate compounds that
are difficult to separate. For example, benzene is sometimes added in a
distillation process to achieve separation of an alcohol-water mixture.
For a flash unit, the design of the flash vessel size is relatively
straightforward. In the case of a fractionating unit design, once the column
pressure and temperature are determined, the reflux ratio (fraction of total
overhead condensate returned to column) is selected to ensure an adequate
liquid phase in the distillation column for vapor enrichment. The number of
trays (or weight of column packing), column diameter, and auxiliary equipment
(pumps, condenser, boiler, and instruments) are then determined. The final
decision on all these items Is based on engineering Judgment and economic
gep.002 2-32
-------
trade offs. More detailed discussion on the design of distillation units is
readily available in various chemical engineering texts. 22 - 24
2.4 REACTOR VOC EMISSIONS
Reactor VOC emissions include all VOC in process vent streams from
reactors and product recovery systems. Process product recovery equipment
includes devices such as condensers, absorbers, and adsorbers, used to
recover product or by-product for use, reuse, or sale. Not included in
product recovery equipment are product purification devices involving
distillation operations.
Reactor processes may be either liquid-phase reactions or gas phase
reactions. Four potential atmospheric emissions points are shown in
Figure 2-5 and include:
direct reactor process vents from liquid-phase reactors;
vents from recovery devices applied to vent streams from liquid
phase reactors (raw materials, products, or by-products may be
recovered from vent streams for economic or environmental reasons);
process vents from gas-phase reactors after either the primary or
secondary product recovery device (gas-phase reactors always have
primary product recovery devices); and
exhaust gases from combustion devices applied to any of the above
streams.
Some chemical production processes may have no reactor process vents to the
atmosphere, while others may have one or more vent streams. Specific
examples of the first three vent types described above are presented in
Figures 2-6, 2-7, and 2-8. Each figure represents one of the 173 reactor
process chemicals covered within the scope of this document.
The production of nltrobenzene by a nitration process is shown in
Figure 2-6 and is an example of a liquid reaction with an uncontrolled vent
stream (Vent Type A). Benzene is nitrated at 55°C (130°F) under atmospheric
pressure by a mixture of concentrated nitric and sulfuric acids in a series;
reactor vents are the largest source of VOC In nltrobenzene plants. It
should be noted, however, that a new process without vents may now be in use.
The production of ethylbenzene is an example of a liquid-phase reaction
of continuous stirred-tank reactions. The crude reaction mixture flows to a
gep.002 2-33
-------
Uquid-Phase Reactor
Gas
Gas-Phase Reactor
Process Vents Controlled by Combustion
Process Vent Str.ans
from A, B, or C
Figure 2-5. General examples of reactor-related vent streams.
V.nt Type 0
Gas
Vent Type A
Product/By-product
Recovery Device
Vent Type B
R.cov.r,d
Produ
Uquld
Uquid
Gas
Vent Type C
Uquid
Gas
gep. 002
2-34
-------
To Atmosphere
To Atmosphere
Figure 2-6. Process flow diagram for the manufacture of nitrobenzene. 7
0
Nitric
Sutfwic
Product
to
Storage
gep. 002
2-35
-------
To Atrnoepher.
Bnz.r e
Ethy .n.
Figure 2-7. Process flow diagram for the manufacture of ethylbenzene.
gep.002 2-36
To Atmoepher.
Ethylb.riz.n.
-------
To Atmosphere
To Atmosphere
Figure 2-8. Process flow diagram for the manufacture of acetone.
0
Isopropyl
Alcohol
Cetalyat
Ac one
Product
gep. 002
2-37
-------
separator, where the organic phase is decanted from the aqueous waste acid.
Emission streams from the reactors and separator are combined and emitted to
the atmosphere without any control devices (Vent 1). Available data
indicates that controls are not typically applied to this process, and that
where the vent stream is passed through a VOC recovery device before it is
discharged to the atmosphere (Type B). Figure 2-7 depicts an alkylation unit
process used to produce ethylbenzene. Ethylene and benzene are combined in
the alkylation reactor to form crude ethylbenzene. The process vent stream
from the reactor goes through three types of scrubbers before discharging to
the atmosphere. The first scrubber recovers the excess benzene reactant from
the vent stream and recycles it to the reactor. The second scrubber removes
any ethylbenzene product in the vent stream and recycles it to the reactor.
Finally, traces of acidic catalyst in the vent stream are removed by a water
scrubber before the vent stream is discharged to the atmosphere. Vent I in
the figure designates the only reactor vent stream for this example. The
crude ethylbenzene product stream from the reactor is purified by
distillation. The vent stream from the product purifications operations
(Vent 2) is associated with distillation operations and, therefore, is not
considered to be a reactor-related vent stream.
Figure 2-8 shows a dehydrogenation process used to produce acetone.
Although this is not the most widely used process to make acetone, it
provides a good example of a vapor-phase reaction and its associated vent
streams (Type C). In this process, isopropyl alcohol is catalytically
dehydrogenated to acetone in a vapor-phase reaction to 400 to 500°C (750 to
930°F). The crude acetone then passes through a condenser or primary VOC
recovery device. The overheads or process vent stream from the primary
condenser then goes through a VOC scrubber and is released to the atmosphere
(Vent 1). Acetone is further refined and emissions from the refining process
(Vent 2) are again not considered to be reactor related. Other processes
used to manufacture acetone have no reactor process vent streams to the
atmosphere.
As indicated in Section 2.2, the characteristics of reactor vent streams
(i.e., heat content, flow rate, VOC control) vary widely among the numerous
chemicals and chemical reactions in the SOCMI. In addition, the numerous
possible combinations of product recovery devices and reactors introduce
gep.002 2-38
-------
another source of variability among various process units using the same
reaction type.
Data included in the reactor processes emissions profile (see
Appendix B) have been grouped by chemical reaction type. Table 2-4
summarizes the VOC emission characteristics of reactor processes using 30 of
the 35 chemical reactions considered here. These data represent the process
vent stream characteristics following the final gas treatment device
(condenser, absorber, or adsorber) but prior to any combustion device.
There is a wide variability in the VOC emission characteristics
associated with the various chemical reactions. For example, VOC emission
factors range from 0 kg/Gg of product for pyrolysis reactions to
120,000 kg/Gg of product for hydroformylation reactions. Wide variability
also exists tn the emission characteristics associated with process units
using the same chemical reaction. For example, process units using
chlorination reactions have VOC emission factors that range from 292 to
9,900 kg/Gg. The variability in process vent stream flow rates and heating
values is not as pronounced as the VOC emission factors. Flow rates range
from 0 to 537 scm/mm and heating values range from 0 to 58.8 MJ/scm.
Although process vent stream characteristics are variable, there are
some general observations evident in Table 2-4. First, process units using
11 of the 30 reaction types included in Table 2-4 were reported to have no
reactor process vents. These reactions include: arnmination, ammonolysis,
cleavage, etherification, fluorination, hydration, neutralization,
oligomerization, phosgenation, pyrolysis, and sulfurization.
A second general observation evident in Table 2-4 is that the process
units using six of the reaction types included in there were reported to have
the largest VOC emission factors. The reactions include: hydroforrnylation,
chlorination, dehydrogenation, condensation, oxychlorination, and
hydrochlorination. The vent streams from process units using these reactions
also tend to have both high heating values and a high percentage application
of combustion devices.
2.5 VOC EMISSIONS FROM DISTILLATION UNITS
The discussions on distillation column operating theory and design show
the basic factors of column operation. Vapors separated from the liquid
phase in a column rise out of the column to a condenser. The gases and
gep.002 2-39
-------
TABLE 2-4. SUMMARY OF REACTOR-RELATED VOC EMISSION FACTORS, VENT STREAM HEAT
CONTENTS, AND FLOW RATE PRIOR TO COMBUSTION
Chemical
reaction type
Range (or singLe
value) of reactor
VOC emission
factorsa b, kg/Gg
Range (or single
vaLue) of vent stream
VOC contentb , g/scm
Percent of
process Islits with
vent streams using
contustion control
Range (Or
sing l e value)
of fLow rates°,
scm/m m
Range (or
Single value) of
vent stream heat
contentb, NJ/scm
Atkytation 5.95-78.1 3.07-252 33.3 0.24-0.48 0.15-6.74
Amination 00 00 00 Od
ArmnonoLysis 00 00 00 0
CarbonyLation 443 1.06 100 53 11.0
Catalytic reforming DNA 1.72 100 36.5 7.63
Chlorination 292-9,900 0.209-118 44.4 1.13-342 0-45.7
CLeavage 00 Od 00 0
Condensation 8,900 554 100 4.16 39
Dehydrat ion DNA DNA 0 DNA DNA
Dehydrogenation 11,400-12,600 36.5-75.0 85.7 16.3-147 10.4-11.2
DehydrochLorination 4,790 1,097 100 0.283 22.3
Esterification 4.38-594 5.34-21.8 16.3 0.06-2.12 3.8
Etherification 0 0 0 a 01
FLuorination 00 00 00 00 0
Hydration 0 00 0 o
Hydrogenation 0-943 0-1,638 83.3 0.09-36.9 12.0-58.8
llydrochLorination 2,000-14,700 28.1-2,247 80 0.566 18.6-47.9
HydroforrwyLation 120,000 878 100 20.6 459
Hydrodirnerization 1,310 6.69 0 30.6 2.61
HydroLysis 2.5 0.27 33.3 2.80 0
0 0 0
NeutraLization 0 0 0 0 0
Nitration 9.95-1,350 0.03-390 33.3 0.37-23.3 0-16.2
0 1 0
OLigomerization 0 0 0 0 0
Oxidation 3,900 0-2.85 25 24-345 0-0.15
(Pure 0,)
Oxyacetytation 2.20 3.82 0 0.198 15.2
Oxychtorinstion 7,180 658 100 8.61 26.6
(Pure 0,)
o 0 0 0
Phosgenation 0 0 0 0 0
Pyrotys is 00 00 00 O Q l
SuLfonation 29.2 0.014 0 52.7 0
0 0 0 0
SuLfurization 0 0 0 0 0
(Vapor Phase)
Emission factors are expressed in terms of Kg of VOC emitted per Gg of chemical produced and represent emissions to the
atmosphere from the final gas treatment device (if used), but before con ustion (if used).
Ranges are due to (1) different chemicals produced by the chemical process and (2) different controLs used at the process units.
ALL vaLues represent emission stream characteristics after the final product recovery device and before coli ustion (if used).
No reactor vent streams are associated with chemicals manufactured by this chemical process.
LittLe or no flow reported for this vent stream.
DNA data not avaiLabLe.
2-40
gep. 002
-------
vapors entering the condenser can contain VOC, water vapor, and
noncondensibles such as oxygen (02), nitrogen (N 2 ), and carbon dioxide (C0 2 ).
The vapors and gases originate from vaporization of liquid feeds, dissolved
gases in liquid feeds, inert carrier gases added to assist in distillation
(only for inert carrier distillation), and air leaking into the column,
especially in vacuum distillation. Most of the gases and vapors entering the
condenser are cooled enough to be collected as a liquid-phase. The
noncondensibles (02, N 2 , C0 2 , and other organics with low boiling points), if
present, are not usually cooled to the condensation temperature and are
present as a gas stream at the end of the condenser. Portions of this gas
stream are often recovered in devices such as scrubbers, adsorbers, and
secondary condensers. Vacuum generating devices (pumps and ejectors), when
used, might also affect the amount of noncondensibles. Some organics can be
absorbed by condensed steam in condensers located after vacuum jets. In the
case of oil-sealed vacuum pumps, the oil losses increase the VOC content of
the noncondensibles exiting the vacuum pump. The noncondensibles from the
last process equipment (condensers, pumps, ejectors, scrubbers, adsorbers,
etc.) constitute the emissions from the distillation unit unless they are
controlled by combustion devises such as incinerators, flares, and boilers.
The most frequently encountered emission points from fractionation
distillation operations are illustrated for several types of distillation
units in Figures 2-9 to 2-12. These emission points are indicated as follows
by the numbers in parenthesis: condenser (1), accumulator (2), hot
wells (3), steam jet ejectors (4), vacuum pump (5), and pressure relief
valve (6). Emissions of VOCs are created by the venting of noncondensible
gases that concurrently carry out some hydrocarbons.
The total volume of gases emitted from a distillation operation depends
upon air leaks into the vacuum column (reduced pressure increases leaks and
increased size increases leaks), the volume of inert carrier gas used, gases
dissolved in the feed, efficiency and operation conditions of the condenser
and other process recovery equipment, and physical properties of the organic
constituents. Knowledge of the quantity of air leaks and dissolved gases in
the column in conjunction with Information on organic vapor physical
properties and condenser operating parameters allows estimation of the VOC
emissions that may result from a given distillation unit operation.
gep.002 2-41
-------
Vnt to Atmosph.r.
Prsssurs R.IIef
Vatvs (6)
Figure 2-9.
Potential VOC emission
col umn.
points for a nonvacuum distillation
Phas.
Accumulator
(2)
Ovsrhud Product
Distillation
Column
gep. 002
2-42
-------
Steam Jet
Ejector (4)
Figure 2-10. Potential VOC emission points for a vacuum distillation column
using steam jet ejectors with barometric condenser.
Vapor Phue
Steam Jet
Ejector (4)
Pressure RelIef
Valve (6)
Accumulator
(2)
Steam
Overhead Product
DIst Illat Ion
Column
Vent
Vent
(3) Hot woO
Wastewater
gep. 002
2-43
-------
Stam
Accumulator
(2)
Figure 2-11.
Potential VOC emission points for a vacuum distillation column
using steam jet ejectors with barometric condenser.
Vapor Phasi
Stsam Jet
Ejctor (4)
Watsr
Accumulator
(2)
Cond.ns,i
(1)
Vent
Overhead Product
Waste Watsr
Distillation
Column
gep. 002
2-44
-------
Vim
Figure 2-12.
Potential VOC emission points for vacuum distillation column
using a vacuum pump.
Viper Phasi
Condsnsir (1)
Vacuum Pump (8)
Accumulator (2)
Uquid Rsfiux
Ov.th.ad Product
Distillation
Column
gep. 002
2-45
-------
The operating parameters for the industry vary to such a great extent
that it is difficult to develop precise emission factors for distillation
units. However, an extensive data base was gathered for organic chemical
industry distillation units. The data base contains information on operating
characteristics, emission controls, exit flows, and VOC emission
characteristics. 25 This data base is presented in Appendix B.
The distillation emission profile contains information on the type of
distillation involved, the produced recovery and VOC control equipment, the
vent stream characteristics, and the other distillation units in the plant.
The vent stream characteristics listed for each column in the profile
(determined downstream of product recovery devices, but upstream of
combustion devices) are: (1) volumetric flow rate, (2) heat content, (3) VOC
emission rate, (4) VOC concentration, and (5) chlorine concentration. A
summary of the distillation emissions profile is presented in Table 2-5.
gep..002 2-46
-------
TABLE 2-5. OVERVIEW OF THE DISTILLATION OPERATIONS EMISSIONS PROFILE
OperatinQ Characteristics of the Distillation Emission Profile
Average offgas flow rate, m 3 /min (scfm) 1.0 (36)
Flow range, m 3 /min (scfm) 0.001-18 (0.005-637)
Average VOC emission rate, kg/hr (lb/hr), 36 (78)
precontrol 1 eda
Average VOC emission rate, kg/hr (lb/hr), 5.9 (13)
control 1 edb
.VOC emission range, kg/hr (lb/hr), .0-1,670 (0-3668)
precontrol 1 ed
aCalculated downstream of adsorbers, absorbers, and condensers, but upstream
of combustion devices.
bcontrolled VOC emission rates were estimated using a 98 percent destruction
efficiency for flares, boilers, and incinerators (where it was indicated
that control devices were being used).
gep.002 2-47
-------
2.6 REFERENCES
1. U.S. International Trade Commission. Synthetic Organic Chemicals,
United States Production and Sales. USITC Publication 2219. 1989.
p. 1-7.
2. Letter from Farmer, JR., U.S Environmental Protection Agency, CPB, to
Jonnard, A., U.S. International Trade Commission. June 12, 1981.
Request for additional list of organic chemicals.
3. Memo from Lesh, S.A., and Piccot, S.D., Radian Corporation, to
Evans, L.B., U.S. Environmental Protection Agency. June 22, 1984.
Revised list of high-volume reactor process chemicals.
4. Memo from Fidler, K., Radian Corporation, to L.B. Evans,
U.S. Environmental Protection Agency. July 6, 1983. Identification of
chemical production routes and unit processes expected to be used in the
future to manufacture the chemicals considered in the Carrier Gas
Project.
5. Memo from Read, B.S., Radian Corporation, to Reactor Processes File.
May 28, 1985. Summary of the emission data profile.
6. Reference 4.
7. U.S. Environmental Protection Agency. Urea Manufacturing
Industry - Technical Document. Research Triangle Park, N.C.
U.S. Environmental Protection Agency Publication No. 450/3-81-001.
January 1982. p. 3-8.
8. Faith, W., et al. Industrial Chemicals 4th Edition. John Wiley & Sons,
New York. 1975. p. 129-130.
9. Chemical Products Synopsis. Mannsville Chemical Products.
Cortland, New York. May 1984.
10. Herrick, E.G., et al. (Mitre Corporation). Unit Process Guide to
Organic Chemical Industries. Ann Arbor, Michigan, Ann Arbor Science
Publishers, Inc., 1979. pp. 120-121.
11. Reference 10.
12. Reference 5.
13. Waddams, A.L. Chemicals from Petroleum, 4th Edition. Houston, Texas,
Gulf Publishing Company, 1978. p. 24, 145-146, 173-174, 221-222.
14. U.S. Environmental Protection Agency. Industrial Process Profiles for
Environmental Use: Chapter 6. Research Triangle Park, N.C.
U.S. Environmental Protection Agency Publication No. 6 00/2-77-023f.
February 1977. p. 667.
gep.002 2-48
-------
15. C 6 -C 8 Olefins (Dimersol X). Hydrocarbon Processing. Q(11):192.
November 1981.
16. Alpha Olefins. Hydrocarbon Processing. (11):128. November 1979.
17. C,-C 8 Olefins (Dimersol Process). Hydrocarbon Processing. (11:17O.
N vember 1977.
18. U.S. Environmental Protection Agency. Organic Chemical Manufacturing,
Volume 7: Selected Processes. Research Triangle Park, N.C.
Publication No. EPA-450/3-80-028b. December 1980. Section 1-1,
p. I ll-i to 111-4.
19. Reference 10.
20. Van Winkle, M. Distillation. New York, McGraw-Hill, 1967.
21. Letter from Desai, T., EEA to Beck, 0., U.S. Environmental Protection
Agency, August 11, 1980.
22. King, C.J. Separation Processes. New York, N.Y. McGraw-Hill, 1971.
23. Faust, A.S., et al. Principles of Unit Operations. New York,
John Wiley & Sons, 1960.
24. Treybal, R.E. Mass Transfer Operations, 2nd edition, New York,
McGraw-Hill, 1968.
25. U.S. Environmental Protection Agency. Distillation Operations in
Synthetic Organic Chemical Manufacturing Industry--Background
Information for Proposed Standards. OAQPS. Research Triangle
Park, N.C. EPA-450/3-83-005a. March 1983.
gep.002 2-49
-------
3. EMISSION CONTROL TECHNIQUES
This chapter dIscusses the volatile organic compound (VOC) emission
control techniques that are applicable to distillation and reactor process
vent streams. The control techniques discussed are grouped Into two broad
categories: (1) combustion control devices, and (2) recovery devices.
Combustion control devices are designed to destroy the VOC in the vent stream
prior to atmospheric discharge. Recovery devices limit VOC emissions by
recycling material back through the process.
The design and operating efficiencies of each emission control technique
are discussed in this chapter. The conditions affecting the VOC removal
efficiency of each type of device are examined, along with an evaluation of
their applicability for use to reduce emissions from distillation vents and
reactor vents. Emphasis has been given to combustion control devices due to
their wide applicability for the control of VOC In 50CM! vent streams.
3.1 COMBUSTION CONTROL DEVICES
Combustion control devices, unlike noncombustion control devices, alter
the chemical structure of the VOC. Combustion is complete if all VOC are
converted to carbon dioxide and water. Incomplete combustion results in some
of the VOC being totally unaltered or being converted to other organic
compounds such as aldehydes or acids.
The combustion control devices discussed in the following four
subsections include flares, thermal incinerators, catalytic incinerators, and
boilers/process heaters. Each device is discussed separately with respect to
its operation, destruction efficiency, and applicability to reactor process
and distillation vent streams.
3.1.1 Flares
3.1.1.1 Flare Process DescriDtion . Flaring is an open combustion
process In which the oxygen required for combustion is provided by the air
around the flame. Good combustion in a flare is governed by flame
temperature, residence time of components in the combustion zone, turbulent
gep.002 3 1
-------
mixing of the components to complete the oxidation reaction, and the amount
of oxygen available for free radical formation.
Flare types can be divided into two main groups: (1) ground flares and
(2) elevated flares, which can be further classified according to the method
to enhance mixing within the flare tip (air-assisted, steam-assisted, or
nonassisted). The discussion in this chapter focuses on elevated flares, the
most common type in the chemical industry. The basic elements of an elevated
flare system are shown in Figure 3-1. The vent stream is sent to the flare
through the collection header (1). The vent stream entering the header can
vary widely in volumetric flow rate, moisture content, VOC concentration, and
heat value. The knock-out drum (2) removes water or hydrocarbon droplets
that could create problems in the flare combustion zone. Vent streams are
also typically routed through a water seal (3) before going to the flare.
This presents possible flame flashbacks, caused when the vent stream flow
rate to the flare is too low and the flame front pulls down into the stack.
Purge gas (N 2 , C0 2 , or natural gas) (4) also helps to prevent flashback
in the flare stack (5) caused by low vent stream flow. The total volumetric
flow to the flame must be carefully controlled to prevent low flow flashback
problems and to avoid a detached flame (a space between the stack and flame
with incomplete combustion) caused by an excessively high flow rate. A gas
barrier (6) or a stack seal is sometimes used just below the flare head to
impede the flow of air into the flare gas network.
The VOC stream enters at the base of the flame where It is heated by
already burning fuel and pilot burners (7) at the flare tip (8). Fuel flows
into the combustion zone, where the exterior of the microscopic gas pockets
Is oxidized. The rate of reaction is limited by the mixing of the fuel and
oxygen from the air. If the gas pocket has sufficient oxygen and residence
time in the flame zone, It can be completely burned. A diffusion flame
receives its combustion oxygen by diffusion of air Into the flame from the
surrounding atmosphere. The high volume of flue gas flow in a flare requires
more combustion air at a faster rate than simple gas diffusion can supply.
Thus, flare designers add high velocity steam injection nozzles (9) to
Increase gas turbulence in the flame boundary zones, drawing in more
combustion air and improving combustion efficiency. This steam injection
promotes smokeless flare operation by minimizing the cracking reaction that
gep.002 3-2
-------
Vent Stream
Figure 3-1. Steam assisted elevated flare system.
Steam Nozzles Flare Tip
(9) (8)
Pilot Burners
(7)
Gas Barrier
(6)
Gas Collection Header
(1)
Steam Un.
Ignition
Device
AirLine
Gas Line
gep.002
3-3
-------
forms carbonaceous soot. Significant disadvantages of steam use are
increased noise and cost. The steam requirement depends on the composition
of the gas flared, the steam velocity from the injection nozzle, and the tip
diameter. Although some gases can be flared smokelessly without any steam,
typically 0.01 to 0.6 kg of steam per kg of flare gas is required.
Steam injection is usually controlled manually by an operator who
observes the flare (either directly or on a television monitor) and adds
steam as required to maintain smokeless operation. Several flare
manufacturers offer devices such as infrared sensors that monitor flame
characteristics and adjust the steam flow rate automatically to maintain
smokeless operation.
Some elevated flares use forced air instead of steam to provide the
combustion air and the mixing required for smokeless operation. These flares
consist of two coaxial flow channels. The combustible gases flow in the
center channel and the combustion air (provided by a fan in the bottom of the
flare stack) flows in the annulus. The principal advantage of air-assisted
flares is that they can be used where steam is not available. Air assist is
rarely used on large flares because air flow is difficult to control when the
gas flow is intermittent. About 90.8 hp of blower capacity is required for
each 100 lb/hr of gas flared. 2
Ground flares are usually enclosed and have multiple burner heads that
are staged to operate based on the quantity of gas released to the flare.
The energy of the gas itself (because of the high nozzle pressure drop) is
usually adequate to provide the mixing necessary for smokeless operation and
air or steam assist is not required. A fence or other enclosure reduces
noise and light from the flare and provides some wind protection.
Ground flares are less numerous and have less capacity than elevated
flares. Typically they are used to burn gas continuously while steam
assisted elevated flares are used to dispose of large amounts of gas released
in emergencies. 3
3.1.1.2 Factors Affecting Flare Efficiency. 4 Flare combustion
efficiency is a function ofmany factors: (1) heating value of the gas,
(2) density of the gas, (3) flammability of the gas, (4) auto-ignition
temperature of the gas; and (5) mixing at the flare tip.
The flammability limits of the gases flared influence ignition stability
and flame extinction. The flammability limits are defined as the
gep.002 3-4
-------
stoichiometric composition limits (maximum and minimum) of an oxygen-fuel
mixture that will burn indefinitely at given conditions of temperature and
pressure without further ignition. In other words, gases must be within
their flammability limits to burn. When flammability limits are narrow, the
interior of the flame may have insufficient air for the mixture to burn.
Fuels with wide limits of flammability (for instance, H 2 ) are therefore
easier to combust.
The auto-ignition temperature of a fuel affects combustion because gas
mixtures must be at high enough temperature and at the proper mixture
strength to burn. A gas with a low auto-ignition temperature will Ignite and
burn more easily than a gas with a high auto-ignition temperature.
The heating value of the fuel also affects the flame stability,
emissions, and flame structure. A lower heating value fuel produces a cooler
flame that does not favor combustion kinetics and also is more easily
extinguished. The lower flame temperature will also reduce buoyant forces,
which reduces mixing. The density of the gas flared also affects the
structure and stability of the flame through the effect on buoyancy and
mixing. By design, the velocity in many flares is very low; therefore, most
of the flame structure is developed through buoyant forces as a result of
combustion. Lighter gases therefore tend to burn better. In addition to
burner tip design, the density of the fuel also affects the minimum purge gas
required to prevent flashback for smokeless flaring.
Poor mixing at the flare tip or poor flare maintenance can cause smoking
(particulate). Fuels with high carbon to hydrogen ratios (greater than 0.35)
have a greater tendency to smoke and require better mixing if they are to be
burned smokelessly.
Many flare systems are currently operated In conjunction with baseload
gas recovery systems. Such systems are used to recovery VOC from the flare
header system for reuse. Recovered VOC may be used as a feedstock In other
processes or as a fuel in process heaters, boilers or other combustion
devices. When baseload gas recovery systems are applied, the flare is
generally used to combust process upset and emergency gas releases that the
baseload system is not designed to recover. In some cases, the operation of
a baseload gas recovery system may offer an economic advantage over operation
of a flare alone since sufficient quantities of useable VOC can be recovered.
gep.002 3-5
-------
3.1.1.3 EPA Flare SDecificatipns . The EPA has established flare
combustion efficiency criteria (40 CFR 60.18) which specify that 98 percent
combustion efficiency can be achieved provided that certain operating
conditions are met: (1) the flare must be operated with no visible emissions
and with a flame present, (2) the net heating value of the flared stream must
be greater than 11.2 MJ/scm (300 Btu/scf) for steam-assisted flares, and
7.45 MJ/scrn (200 Btu/scf) for a flare without assist, and (3) steam assisted
and nonassisted flares must have an exit velocity less than 18.3 rn/sec
(60 ft/sec). Steam assisted and nonassisted flares having an exit velocity
greater than 18.3 rn/sec (60 ft/sec) but less than 122 rn/sec (400 ft/sec) can
achieve 98 percent control if the net heating value of the gas stream is
greater than 37.3 MJ/scm (1,000 Btu/scf). Air-assisted flares, as well as
steam-assisted and nonassisted flares with an exit velocity less than
122 rn/sec (400 ft/sec) and a net heating value less than 37.3 MJ/scrn
(1,000 Btu/scf), can determine the allowable exit velocity by using an
equation in 40 CFR 60.18.
3.1.1.4 ADplicabjljty of Flares . Most of the SOCMI plants are
estimated to have a flare. 5 Flares are usually designed to control either
the normal process vents or emergency upsets. The latter involves the
release of large volumes of gases. Often, large diameter flares designed to
handle emergency releases are used to control continuous vent streams from
various process operations. In refineries, many process vents are usually
combined in a common gas header that supplies fuel to boilers and process
heaters. However, excess gases, fluctuations in flow in the gas line, and
emergency releases are sometimes sent to a flare.
Flares have been found to be useful emission control devices. They can
be used for almost any VOC stream, and can handle fluctuations in VOC
concentration, flow rate, and Inerts content. Some streams, such as those
containing high concentrations of halogenated or sulfur-containing compounds,
are not usually flared due to corrosion of the flare tip or formation of
secondary pollutants (such as SO 2 ).
3.1.2 Thermal Incinerators
3.1.2.1 Thermal Incinerator Process DescriDtion . Any VOC heated to a
high enough temperature in the presence of enough oxygen will be oxidized to
carbon dioxide and water. This Is the basic principle of operation of a
thermal incinerator. The theoretical temperature required for thermal
gep.002 3-6
-------
oxidation depends on the structure of the chemical involved. Some chemicals
are oxidized at temperatures much lower than others. However, a temperature
can be identified that will result in the efficient destruction of most VOC.
All practical thermal incineration processes are influenced by residence
time, mixing, and temperature. An efficient thermal incinerator system must
provide:
a chamber temperature high enough to enable the oxidation reaction
to proceed rapidly to completion;
enough turbulence to obtain good mixing between the hot combustion
products from the burner, combustion air, and VOC; and
sufficient residence time at the chosen temperature for the
oxidation reaction to reach completion.
A thermal incinerator is usually a refractory-lined chamber containing a
burner (or set of burners) at one end. As shown in Figure 3-2, discrete dual
fuel burners (1) and inlets for the offgas (2) and combustion air (3) are
arranged in a premixing chamber (4) to thoroughly mix the hot products from
the burners with the process vent streams. The mixture of hot reacting gases
then passes into the main combustion chamber (5). This chamber is sized to
allow the mixture enough time at the elevated temperature for the oxidation
reaction to reach completion (residence times of 0.3 to 1.0 second are
common). Energy can then be recovered from the hot flue gases in a heat
recovery section (6). Preheating combustion air or offgas is a common mode
of energy recovery; however, it is sometimes more economical to generate
steam. Insurance regulations require that if the waste stream is preheated,
the VOC concentration must be maintained below 25 percent of the lower
explosive limit to remove explosion hazards.
Thermal incinerators designed specifically for VOC incineration with
natural gas as the auxiliary fuel may also use a grid-type (distributed) gas
burner 6 as shown in Figure 3-3. The tiny gas flame jets (1) on the grid
surface (2) ignite the vapors as they pass through the grid. The grid acts
as a baffle for mixing the gases entering the chamber (3). This arrangement
ensures burning of all vapors at lower chamber temperature and uses less
fuel. This system makes possible a shorter reaction chamber yet maintains
high efficiency.
gep.002 3-7
-------
At&dllwy
Fu Bum.r
(Dlscr.t.)
(1)
Figure 3-2. Discrete burner, thermal oxidizer.
gep.002 3-8
Wast. Gas
Inlit
(2)
Prsmbcing
(3) Chambir
(4)
Combustion Chambir
(5)
-------
Figure 3-3.
Distributed burner, thermal oxider.
Burner P at.
(2)
Flame Jets
(1)
Wait.
Gas
Inlet
(Natursi Gas)
A dllary Fuel
Optlonel Heat
R.covery
(4)
gep.002
3-9
-------
Other parameters affecting incinerator performance are the vent stream
heating value, the water content in the stream, and the amount of excess
combustion air (the amount of air above the stoichiometric air needed for
reaction). The vent stream heating value is a measure of the heat available
from the combustion of the VOC in the vent stream. Combustion of the vent
stream with a heating value less than 1.9 MJ/scm (50 Btu/scf) usually
requires burning auxiliary fuel to maintain the desired combustion
temperature. Auxiliary fuel requirements can be lessened or eliminated by
the use of recuperative heat exchangers to preheat combustion air. Vent
streams with a heating value above 1.9 MJ/scm (50 Btu/scf) may support
combustion but may need auxiliary fuel for flame stability.
Other parameters affecting incinerator performance are the vent stream
heating value, the water content in the stream, and the amount of excess
combustion air (the amount of air above the stoichiometric air needed for
reaction). The vent stream heating value is a measure of the heat available
from the combustion of the VOC in the vent stream. Combustion of the vent
stream with a heating value less than 1.9 MJ/scm (50 Btu/scf) usually
requires burning auxiliary fuel to maintain the desired combustion
temperature. Auxiliary fuel requirements can be lessened or eliminated by
the use of recuperative heat exchangers to preheat combustion air. Vent
streams with a heating value above 1.9 MJ/scm (50 Btu/scf) may support
combustion but may need auxiliary fuel for flame stability.
A thermal incinerator, handling vent streams with varying heating values
and moisture content, requires careful adjustment to maintain the proper
chamber temperatures and operating efficiency. Since water requires a great
deal of heat to vaporize, entrained water droplets in an offgas stream can
increase auxiliary fuel requirements to provide the additional energy needed
to vaporize the water and raise It to the combustion chamber temperature.
Combustion devices are always operated with some quantity of excess air to
ensure a sufficient supply of oxygen. The amount of excess air used varies
with the fuel and burner type but should be kept as low as possible. Using
too much excess air wastes fuel because the additional air must be heated to
the combustion chamber temperature. Large amounts of excess air also
increases flue gas volume and may increase the size and cost of the system.
Packaged, single-unit thermal incinerators can be built to control streams
gep.002 3-10
-------
with flow rates in the range of 0.14 scm/sec (300 scfm) to about 24 scm/sec
(50,000 scfm).
Thermal oxidizers for halogenated VOC may require additional control
equipment to remove the corrosive combustion products. The halogenated VOC
streams are usually scrubbed to prevent corrosion due to contact with acid
gases formed during the combustion of these streams. The flue gases are
quenched to lower their temperature and are then routed through absorption
equipment such as packed towers or liquid jet scrubbers to remove the
corrosive gases.
3.1.2.2 Thermal Incinerator Efficiency . The VOC destruction efficiency
of a thermal oxidizer can be affected by variations in chamber temperature,
residence time, inlet VOC concentration, compound type, and flow regime
(mixing). Test results show that thermal oxidizers can achieve 98 percent
destruction efficiency for most VOC compounds at combustion chamber
temperatures ranging from 700 to 1,300°C (1,300 to 2,370°F) and residence
times of 0.5 to 1.5 seconds. 7 These data indicate that significant
variations in destruction efficiency occurred for Cj to C 5 alkanes and
olefins, aromatics (benzene, toluene, and xylene), oxygenated compounds
(methyl ethyl ketone and isopropanol), chlorinated organics (vinyl chloride),
and nitrogen-containing species (acrylonitrile and ethylaniines) at chamber
temperatures below 760 0 C (1,400°F). This information, used in conjunction
with kinetics calculations, indicates the combustion chamber parameters for
achieving at least a 98 percent VOC destruction efficiency are a combustion
temperature of 870 (1,600°F) and a residence time of 0.75 seconds (based
upon residence in the chamber volume at combustion temperature). A thermal
oxidizer designed to produce these conditions In the combustion chamber
should be capable of high destruction efficiency for almost any
nonhalogenated VOC.
At temperatures over 760°C (1,400°F), the oxidation reaction rates are
much faster than the rate of gas diffusion mixing. The destruction
efficiency of the VOC then becomes dependent upon the fluid mechanics within
the oxidation chamber. The flow regime must ensure rapid, thorough mixing of
the VOC stream, combustion air, and hot combustion products from the burner.
This enables the VOC to attain the combustion temperature in the presence of
enough oxygen for sufficient time so the oxidation reaction can reach
completion.
gep.002 3-11
-------
Based upon studies of thermal oxidizer efficiency, it has been concluded
that 98 percent VOC destruction or a 20 ppmv compound exit concentration is
achievable by all new incinerators. The maximum achievable VOC destruction
efficiency decreases with decreasing inlet concentration because of the much
slower combustion reaction rates at lower inlet VOC concentrations.
Therefore, a VOC weight percentage reduction based on the mass rate of VOC
exiting the control device versus the mass rate of VOC entering the device
would be appropriate for vent streams with VOC concentrations above
approximately 2,000 ppmv (corresponding to 1,000 ppmv VOC In the incinerator
inlet stream since air dilution is typically 1:1). For vent streams with VOC
concentrations below approximately 2,000 ppmv, It has been determined that an
incinerator outlet concentration of 20 ppmv (by compound), or lower, is
achievable by all new thermal oxidizers. 8 The 98 percent efficiency estimate
is predicated on thermal incinerators operated at 870 0 C (1,600°F) with
0.75 seconds residence time.
3.1.2.3 ADDlicabilitv of Thermal incinerators . In terms of technical
feasibility, thermal incinerators are applicable as a control device for most
SOCMI vent streams. They can be used for vent streams with any VOC
concentration and any type of VOC, and they can be designed to handle minor
fluctuations in flows. However, excessive fluctuations in flow (i.e.,
process upsets) might not allow the use of incinerators and would require the
use of a flare. Presence of elements such as halogens or sulfur might
require some additional equipment such as scrubbers for acid gas removal.
Thermal incinerators are currently used to control VOC emissions from a
number of process operations, including reactors and distillation operations.
3.1.3 industrial B ilers/Prpcess _ Heaters
Industrial boilers and process heaters can be designed to control VOC by
incorporating the reactor process or distillation vent stream with the Inlet
fuel or by feeding the stream into the boiler or heater through a separate
burner. The major distinctions between industrial boilers and process
heaters are that the former produces steam at high temperatures while the
latter raises the temperature of process streams as well as superheating
steam, typically at temperatures lower than with an industrial boiler. The
process descriptions for an industrial boiler and a process heater are
presented separately in the following two sections. The process descriptions
gep.002 3-12
-------
focus on those aspects that relate to the use of these combustion devices as
a VOC control method.
3.1.3.1 Industrial Boiler/Process DescriDtion . Surveys of industrial
boilers show that the majority of industrial boilers used in the chemical
industry are of watertube design. Furthermore, over half of these boilers
use natural gas as a fuel. 9 In a water tube boiler, hot combustion gases
contact the outside of heat transfer tubes, which contain hot water and
steam. These tubes are interconnected by a set of drums that collect and
store the heated water and steam. The water tubes are of relatively small
diameter, 5 cm (2.0 Inches), providing rapid heat transfer, rapid response to
steam demands, and relatively high thermal efficiency. 0 Energy transfer
from the hot flue gases to water In the furnace water tube and drum system
can be above 85 percent efficient. Additional energy can be recovered from
the flue gas by preheating combustion air in an air preheater or by
preheating incoming boiler feed water in an economizer unit.
When firing natural gas, forced or natural draft burners are used to
thoroughly mix the incoming fuel and combustion air. If a SOCMI vent stream
is combusted in a boiler, it can be mixed with the incoming fuel or fed to
the furnace through a separate burner. In general, burner design depends on
the characteristics of either the fuel mix (when the SOCMI vent stream and
fuel are combined) or on the characteristics of the vent stream alone (when a
separate burner is used). A particular burner design, commonly known as a
high intensity or vortex burner, can be effective for vent streams with low
heating values (i.e., streams where a conventional burner may not be
applicable). Effective combustion of low heating value streams is
accomplished in a high intensity burner by passing the combustion air through
a series of spin vanes to generate a strong vortex.
Furnace residence time and temperature profiles vary for Industrial
boilers depending on the furnace and burner configuration, fuel type, heat
Input, and excess air level. 11 A mathematical model has been developed that
estimates the furnace residence time and temperature profiles for a variety
of industrial boilers. 12 This model predicts mean furnace residence times of
from 0.25 to 0.83 seconds for natural gas-fired water tube boilers in the
size range from 4.4 to 44 MW (15 to 150 X 106 Btu/hr). Boilers at or above
the 44 MW size have residence times and are generally operated at
temperatures that ensure a 98 percent VOC destruction efficiency. Furnace
gep.002 3-13
-------
exit temperatures for this range of boiler sizes are at or above l , 200 °c
(2,200°F) with peak furnace temperatures occurring in excess of 1,540C
(2,810°F).
3.1.3.2 Process Heater 0escriotio . A process heater is similar to an
industrial boiler in that heat liberated by the combustion of fuels is
transferred by radiation and convection to fluids contained In tubular coils.
Process heaters are used in chemical manufacturing to drive endothermic
reactions such as natural gas reforming and thermal cracking. They are also
used as feed preheaters and as reboilers for some distillation operations.
The fuels used in process heaters include natural gas, refinery offgases, and
various grades of fuel oil. Gaseous fuels account for about 90 percent of
the energy consumed by process heaters. 3
There are many variations in the design of process heaters depending on
the application considered. In general, the radiant section consists of the
burner(s), the firebox, and a row of tubular coils containing the process
fluid. Most heaters also contain a convection section in which heat is
recovered from hot combustion gases by convective heat transfer to the
process fluid.
Process heater applications in the chemical industry can be broadly
classified with respect to firebox temperature: (1) low firebox temperature
applications such as feed preheaters and reboilers, (2) medium firebox
temperature applications such as stream superheaters, and (3) high firebox
temperature applications such as pyrolysis furnaces and steam-hydrocarbon
reformers. Firebox temperatures within the chemical industry can range from
about 400 0 C (750°F) for preheaters and reboilers to 1,260°C (2,300°F) for
pyrolysis furnaces.
3.1.3.3 Industrial Boilers and Process Hea gr Control Efficiency . A
boiler or process heater furnace can be compared to an incinerator where the
average furnace temperature and residence time determines the combustion
efficiency. However, when a vent gas is injected as a fuel into the flame
zone of a boiler or process heater, the required residence time Is reduced
due to the relatively high flame zone temperature. The following test data,
which document the destruction efficiencies for Industrial boilers and
process heaters, are based on injecting the wastes identified Into the flame
zone of each combustion control device.
gep.002 3-14
-------
An EPA-sponsored test was conducted to determine the destruction
efficiency of an industria.l boiler for polychiorinated biphenyls (PCBs). 14
The results of this test indicated that the PCB destruction efficiency of an
oil-fired industrial boiler firing PCB-spiked oil was greater than 99 percent
for a temperature range of 1,361 to 1,5200C and a range of residence time of
2 to 6 seconds. This efficiency was determined based on the PCB content
measured by a gas chromatograph In the fuel feed and flue gas.
As discussed in previous sections, firebox temperatures for process
heaters show relatively wide variations depending on the application (see
Section 3.1.3.2). Tests were conducted by EPA to determine the benzene
destruction efficiency of five process heaters firing a benzene offgas and
natural gas mixture. 1517 The units tested are representative of process
heaters with low temperature fireboxes (reboilers) and medium temperature
fireboxes (superheaters). Sampling problems occurred while testing one of
these heaters, and as a result, the data for that test may not be reliable
and are not presented. 18 The reboiler and superheater units tested showed
greater than a 98 percent overall destruction efficiency for Cj to C 5
hydrocarbons. 19 Additional tests conducted on a second superheater and a hot
oil heater showed that greater than 99 percent overall destruction of C 1 to
C 5 hydrocarbons occurred for both units. 20
3.1.3.4 A plicabilitv of Industrial Boilers and Process Heaters .
Industrial boilers and process heaters are currently used by industry to
combust process vent streams from distillation operations, reactor
operations, and general refinery operations. These devices are most
applicable where high vent stream heat recovery potential exists.
Both boilers and process heaters are essential to the operation of a
plant. As a result, only streams that are certain not to reduce the devices
performance or reliability warrant use of a boiler or process heater as a
combustion control device. Variations In vent stream flow rate and/or
heating value could affect the heat output or flame stability of a boiler or
process heater and should be considered when using these combustion devices.
Performance or reliability may be affected by the presence of corrosive
products in the vent stream. Since these compounds could corrode boiler or
process heater materials, vent streams with a relatively high concentration
of halogenated or sulfur-containing compounds are usually not combusted in
boilers or process heaters. When corrosive VOC compounds are combusted, the
gep. 002
3-15
-------
flue gas temperature must be maintained above the acid dew point to prevent
acid deposition and subsequent corrosion from occurring.
The introduction of a vent stream into the furnace of a boiler or heater
could alter the heat transfer characteristics of the furnace. Heat transfer
characteristics are dependent on the flow rate, heating value, and elemental
composition of the vent stream, and the size and type of heat generating unit
being used. Often, there is no significant alteration of the heat transfer,
and the organic content of the process vent stream can In some cases reduce
the amount of fuel required to produce the desired heat. In other cases, the
change in heat transfer characteristics after introduction of a vent stream
may affect the performance of the heat-generating unit, and increase fuel
requirements. For some vent streams there may be potential safety problems
associated with ducting reactor process or distillation vents to a boiler or
process heater. Variation in the flow rate and organic content of the vent
stream could, in some cases, lead to explosive mixtures within a boiler
furnace. Flame fluttering within the furnace could also result from
variations in the process vent stream characteristics. Precautionary
measures should be considered in these situations.
When a boiler or process heater is applicable and available, they are
excellent control devices providing at least 98 percent destruction of VOC.
In addition, near complete recovery of the vent stream heat content is
possible. However, both devices must operate continuously and concurrently
with the pollution source unless an alternate control strategy Is available
in the event that the heat generating capacity of either unit is not required
and is shut down.
3.1.4 Catalytic Oxidizers
3.1.4.1 Catalytic Oxidation Process Descriotion . Catalytic oxidation
is the fourth major combustion technique examined for VOC emission control.
A catalyst Increases the rate of chemical reaction without becoming
permanently altered itself. Catalysts for catalytic oxidation cause the
oxidizing reaction to proceed at a lower temperature than Is required for
thermal oxidation. These units can also operate well at VOC concentrations
below the lower explosive limit, which is a distinct advantage for some
process vent streams. Combustion catalysts include platinum and platinum
alloys, copper oxide, chromium, and cobalt. 21 These are deposited in thin
layers on inert substrates to provide for maximum surface area between the
gep.002 3-16
-------
catalyst and the VOC stream. The substrate may be either pelletized or cast
in a rigid honeycomb matrix.
A schematic of a catalytic oxidation unit is shown in Figure 3-4. The
waste gas (1) Is introduced into a mixing chamber (2) where it is heated to
about 316°C (600°F) by contact with the hot combustion products from
auxiliary burners (3). The heated mixture is then passed through the
catalyst bed (4). Oxygen and VOC migrate to the catalyst surface by gas
diffusion and are adsorbed in the pores of the catalyst. The oxidation
reaction takes place at these active sites. Reaction products are desorbed
from the active sites and transferred by diffusion back into the waste gas. 22
The combusted gas may then be passed through a waste heat recovery device (5)
before exhausting into the atmosphere.
The operating temperatures of combustion catalysts usually range from
316 to 650°C (600 to 1,200°F). Lower temperatures may slow down and possibly
stop the oxidation reaction. Higher temperatures may result in shortened
catalyst life and possible evaporation or melting of the catalyst from the
support substrate. Any accumulation of particulate matter, condensed VOC, or
polymerized hydrocarbons on the catalyst could block the active sites and,
therefore, reduce effectiveness. Catalysts can also be deactivated by
compounds containing sulfur, bismuth, phosphorous, arsenic, antimony,
mercury, lead, zinc, tin, or halogens. 23 If these compounds exist in the
catalytic unit, VOC will pass through unreacted or be partially oxidized to
form compounds such as aldehydes, ketones, and organic acids.
3.1.4.2 Catalytic OxiciizerControl Efficiency . Catalytic oxidizer
destruction efficiency is dependent on the space velocity (the catalyst
volume required per unit volume gas processed per hour), operating
temperature, oxygen concentration, and waste gas VOC composition and.
concentratiofl. A catalytic unit operating at about 450°C (840°F) with a
catalyst bed volume of 0.014 to 0.057 m 3 (0.5 to 2 ft 3 ) per 0.47 scm/sec
(1,000 scfm) of vent stream passing through the device can achieve 95 percent
VOC destruction efficiency. However, catalytic oxidizers have been reported
to achieve efficiencies of 98 percent or greater. 24 These higher
efficiencies are usually obtained by Increasing the catalyst bed
volume-to-vent stream flow ratio.
gep.002 3-17
-------
Opttonei Heat
Recovery
(5)
Figure 3-4.
Catalytic oxidizer.
To Atrnosphr.
Stack
Auxiliary Fuel
Bumere
(3)
Mixing Chanib.r
Auxiliary Fu.l (2)
Bum.rs
gep.002
3-18
-------
3.1.4.3 ADDlicability of Catalytic Oxidizers . The sensitivity of a
catalytic oxidizer to VOC inlet stream flow conditions and its inability to
handle high VOC concentration offgas streams limit the applicability of
catalytic units for control of VOC from many processes. However, some
catalytic units have operated successfully on reactor process vent streams
from air oxidation processes. 25
3.2 RECOVERY DEVICES
The recovery devices discussed in this section include adsorbers,
absorbers, and condensers. These devices are generally applied to recover
reactant, product, or by-product VOC from a vent stream for use as a product
or to recycle a compound. The chemical structure of the VOC removed is
usually unaltered.
3.2.1 Adsorotion
3.2.1.1 Adsorption Process DescriDtion . Adsorption is a mass-transfer
operation involving interaction between gaseous- and solid-phase components.
The gas phase (adsorbate) is captured on the solid-phase (adsorbent) surface
by physical or chemical adsorption mechanisms. Physical adsorption is a
mechanism that takes place when intermolecular (van der Waals) forces attract
and hold the gas molecules to the solid surface. 26 Chemisorption occurs when
a chemical bond forms between the gaseous- and solid phase molecules. A
physically adsorbed molecule can readily be removed from the adsorbent (under
suitable temperature and pressure conditions) while the removal of a
chemisorbed component is much more difficult.
The most commonly encountered industrial adsorption systems use
activated carbon as the adsorbent. Activated carbon is effective in
capturing certain organic vapors by the physical adsorption mechanism. In
addition, the vapors may be released for recovery by regeneration of the
adsorption bed with steam or nitrogen. Oxygenated adsorbents such as silica
gels, diatomaCeouS earth, alumina, or synthetic zeolites exhibit a greater
selectivity than activated carbon for capturing water vapor rather than
organic gases. Thus, these adsorbents would be of little use for the high
moisture gas streams characteristic of some SOCMI vents. 27
The design of a carbon adsorption system depends on the chemical
characteristics of the VOC being recovered, the physical properties of the
offgas stream (temperature, pressure, and volumetric flow rate) and the
gep.002 3-19
-------
physical properties of the adsorbent. The mass quantity of VOC that adheres
to the adsorbent surface is directly proportional to the difference in VOC
concentration between the gas-phase and the solid surface. In addition, the
quantity of VOC adsorbed Is dependent on the adsorbent bed volume, the
surface area of adsorbent available to capture VOC, and the rate of diffusion
of VOC through the gas film at the gas- and solid-phase Interface. Physical
adsorption is an exothermic operation that Is most efficient within a narrow
range of temperature and pressure.
A schematic diagram of a typical fixed bed, regenerative carbon
adsorption systems Is given In Figure 3-5. The process offgases are
generally filtered and cooled (1) before entering the carbon bed. The inlet
gases to an adsorption unit are filtered to prevent bed contamination. The
gas is cooled to maintain the bed at optimum operating temperature and to
prevent fires or polymerization of the hydrocarbons. Vapors entering the
adsorber stage of the system (2) are passed through the porous activated
carbon bed.
Adsorption of Inlet vapors usually occurs until the outlet VOC
concentration reaches some preset level (the breakthrough concentration).
The dynamics of the process may be illustrated by viewing the carbon bed as a
series of layers or mass-transfer zones (3a, b, C). Gases entering the bed
are adsorbed first in zone (a). Because most of the VOC is adsorbed in
zone (a), very little adsorption takes place in zones (b) and (c).
Adsorption in zone (b) Increase as zone (a) reaches equilibrium with organics
and proceeds through zone (C). When the bed is completely saturated
(breakthrough), the Incoming VOC-laden offgases are routed to an alternate
bed while the saturated carbon bed is regenerated.
Regeneration of the carbon bed is accomplished by heating the bed or
applying vacuum to draw off the adsorbed gases. Low pressure steam (4) is
frequently used as a heat source to strip the adsorbent of organic vapor.
After steaming, the carbon bed Is cooled and dried typically by blowing air
through It with a fan; and the steam-laden vapors are routed to a
condenser (5) and on to a solvent recovery system (6). The regenerated bed
is put back into active service while the saturated bed Is purged of
organics. The regeneration process may be repeated numerous times, but
eventually the carbon must be replaced.
gep.002 3-20
-------
Vent to
VOC -Laden Atmosphere
Vent Stream
(1) ari 1 o rig -
(3)
ose J
( Adsorber I
(Adsorbing)
Fan
Closed_____________________ Open
\ Ste
P e (4) ___________
Adsorber 2
(Regenerating)
(5)
( Condense )
( 6 ) Recovered
Decentor and/or Solvent
Dlstllilng Tower Water
Figure 3-5. Two stage regenerative adsorption system.
gep.002 3-21
-------
3.2.1.2 Adsorption Control Efficiency . Many modern, well-designed
systems achieve 95 percent removal efficiency for some chemicals. 28 The VOC
removal efficiency of an adsorption unit is dependent upon the physical
properties of the compounds present in the offgas, the gas stream
characteristics, the physical properties of the adsorbent, and the condition
of the regenerated carbon bed.
Gas temperature, pressure and velocity are important in determining
adsorption unit efficiency. The adsorption rate in the bed decreases sharply
when gas temperatures are above 38°C (100°F). 29 30 High temperature
increases the kinetic energy of the gas molecules, causing them to overcome
van der Waals forces. Under these conditions, the VOC are not retained on
the surface of the carbon. Increasing vent stream pressure and temperature
generally will improve VOC capture efficiency; however, care must be taken to
prevent solvent condensation and possible fire.
3.2.1.3 AoDlicabilitv of Adsorotion . Although carbon adsorption is an
excellent method for recovering some valuable process chemicals, it cannot be
used as a universal control method for distillation or reactor process vent
streams. The conditions where carbon adsorption is not recommended are
present in many SOCMI vent streams. These include streams with: (1) high
VOC concentrations, (2) very high or low molecular weight compounds, and
(3) mixtures of high and low boiling point VOC.
The range of organic concentrations to which carbon adsorption safely
can be applied is from only a few parts per million to concentrations of
several percent. 31 Adsorbing vent streams with high organic concentration
may result in excessive temperature rise in the carbon bed due to the
accumulated heat of adsorption of the VOC loading. However, streams with
high organic concentrations can be diluted with air or inert gases to make a
workable adsorption system.
The molecular weight of the compounds to be adsorbed should be in the
range of 45 to 130 gm/gm-mole for effective adsorption. Carbon adsorption
may not be the most effective application for compounds with low molecular
weights (below 45 gm/gm-mole) owing to their smaller attractive forces or for
high molecular weight components (130 gm/gm-mole) which attach so strongly to
the carbon bed that they are not easily removed. 32
Properly operated adsorption systems can be very effective for
homogenous offgas streams but can have problems with a multicomponent system
gep.002 3-22
-------
high molecular weight components (130 gm/gm-mole) which attach so strongly to
the carbon bed that they are not easily removed. 32
Properly operated adsorption systems can be very effective for
homogenous offgas streams but can have problems with a multicomponent system
containing a mixture of light and heavy hydrocarbons. The lighter organics
tend to be displaced by the heavier (higher boiling) components, greatly
reducing system efficiency. 33
3.2.2 AbsorDtion
3.2.2.1 Absorotion Process DescriDtion . The mechanism of absorption
consists of the selective transfer of one or more components of a gas mixture
into a solvent liquid. The transfer consists of solute diffusion and
dissolution into a solvent. For any given solvent, solute, and set of
operating conditions, there exists an equilibrium ratio of solute
concentration in the gas mixture to solute concentration in the solvent. The
driving force for mass transfer at a given point in an operating absorption
tower is related to the difference between the actual concentration ratio and
the equilibrium ratio. 34 Absorption may only entail the dissolution of the
gas component into the solvent or may also involve chemical reaction of the
solute with constituents of the Solution. 35 The absorbing liquids (solvents)
used are chosen for high solute (VOC) solubility and include liquids such as
water, mineral oils, nonvolatile hydrocarbon oils, and aqueous solutions of
oxidizing agents like sodium carbonate and sodium hydroxide. 36
Devices based on absorption principles include spray towers, venturi and
wet impingement scrubbers, packed columns, and plate columns. Spray towers
require high atomization pressure to obtain droplets ranging in size from
500 to 100 m in order to present a sufficiently large surface contact
area. 37 Although they can remove particulate matter effectively, spray
towers have the least effective mass transfer capability and thus, are
restricted to particulate removal and control of high-solubility gases such
as sulfur dioxide and ammonia. 38 Venturi scrubbers have a high degree of
gas-liquid mixing and high particulate removal efficiency but also require
high pressure and have relatively short contact times. Therefore, their use
is also restricted to high-solubility gases. 39 As a result, VOC control by
gas absorption is generally accomplished in packed or plate columns.
Packed columns are mostly used for handling corrosive materials, liquids
with foaming or plugging tendencies, or where excessive pressure drops would
gep.002 3-23
-------
inadequately wet the packing.40
A schematic of a packed tower is shown in Figure 3-6. The gas to be
absorbed is introduced near the bottom of the tower (1) and allowed to rise
through the packing material (2). Solvent flows in from the top of the
column, countercurrent to the vapors (3), absorbing the solute from the
gas-phase and carrying the dissolved solute out of the tower (4). Cleaned
gas exits at the top (5) for release to the atmosphere or for further
treatment as necessary. The solute-rich liquid is generally sent to a
stripping unit where the absorbed VOC is recovered. Following the stripping
operation the absorbing solution is either recycled back to the absorber or
sent to water treatment facility for disposal.
The major tower design parameters to be determined for absorbing any
substance are column diameter and height, system pressure drop, and liquid
flow rate required. These parameters are derived by considering the waste
gas solubility, viscosity, density, and concentration, all of which depend on
column temperature; and also the total surface area provided by the tower
packing material, and the quantity of gases to be treated.
3.2.2.2 Absorption Control Efficiency . The VOC removal efficiency of
an absorption device is dependent on the solvent selected, and on proper
design and operation. For a given solvent and solute, an increase in
absorber size or a decrease in the operating temperature can increase the VOC
removal efficiency of the system. It may be possible in some cases to
increase VOC removal efficiency by a change in the absorbent.
Systems that use organic liquids as solvents usually include the
stripping and recycling of the solvent to the absorber. In this case the VOC
removal efficiency of the adsorber is dependent on the solvents stripping
efficiency.
3.2.2.3 ApplIcability of Absorption . Absorption is an attractive
control option if a significant amount of VOC can be recovered for reuse.
Although absorption is applicable for many SOCMI vent streams, it cannot be
universally applied. It is usually not considered when the VOC concentration
is below 200-300 ppmv. 41
3.2.3 Condensation
3.2.3.1 Condensation Process DescriDtion . Condensation is a process of
converting all or part of the condensable components of a vapor phase into a
liquid phase. This is achieved by the transfer of heat from the vapor phase
gep.002 3-24
-------
Absorbing
Liquid In
Figure 3-6. Packed tower for gas absorption.
(1) vOc Laden
Gas In
T Gas Out
Inal Control Device
or to Atmosphere
(4)
AbsorbingUqu ld
wIth VOC Out
To Disposal or VOCiSOIv nt Recovery
gep.002
3-25
-------
to a cooling medium. If only a part of the vapor phase is condensed, the
newly formed liquid phase and the remaining vapor phase will be in
equilibrium. In this case, equilibrium relationships at the operating
temperatures must be considered. The heat removed from the vapor phase
should be sufficient to lower the vapor-phase temperature to at or below its
dew point temperature (temperature at which first drop of liquid is formed).
Condensation devices are of two types: surface condensers and contact
condensers. 42 Surface condensers are typically shell-and-tube type heat
exchangers. The coolant and the vapor phases are separated by the tube wall
and they never come in direct contact with each other. As the coolant passes
through the tubes,the VOC vapors condense outside the tubes and are
recovered. Surface condensers require more auxiliary equipment for operation
but can recover valuable VOC without contamination by the coolant, minimizing
waste disposal problems. Only surface condensers are considered in the
discussion of control efficiency and applicability since they are used more
frequently in the chemical industry.
The major equipment components used in a typical surface condenser
system for VOC removal are shown in Figure 3-7. This system includes a
dehumidifier (I), surface condenser exchanger (2), refrigeration unit (3),
and VOC storage tanks and operation pumps (4). Most surface condensers use a
shell-and-tube type heat exchanger to remove heat from the vapor. 43 The
coolant selected depends upon the saturation temperature of the VOC stream.
Chilled water can be used down to 7 C (45 0 F), brines to -34°C (-30°F), and
chiorofluorocarbons below-34°C (-30°F). 44 Temperatures as low as _620C
(-80°F) may be necessary to condense some VOC streams. 45
3.2.3.2 Condenser Control Efficiency . The VOC removal efficiency of a
condenser is dependent upon the type of vapor stream entering the condenser,
and on condenser operating parameters. Efficiencies of condensers usually
vary from 50 to 95 percent. 46
3.2.3.3 ADDlicability of Condensers . A primary condenser system is
usually an integral part of most distillation operations. Primary condensers
are needed to provide reflux In fractionating columns and to recover
distilled products. At times additional (secondary) condensers are used to
recover more VOC from the vent stream exiting the primary condenser.
Condensers are sometimes present at accessories to vacuum generating devices
gep.002 3-26
-------
Cleaned Gas Out
To Primary Control Flare,
Afterburner, Etc.
(2)
(4)
To Process
Or Disposal
Figure 3-7.
Condensation system.
VOC Laden
Gas
(1)
Dehumidification
Unit
To Remove Water
and
Prevent Freezing
in Main Condenser
Coolant
Return
Condensed
VOC
(3)
3-27
gep. 002
-------
(e.g., barometric condensers). Condensers are also commonly used product
recovery devices on reactor process vent streams.
The use of a secondary condenser to control VOC emissions may not be
applicable to some vent streams. Secondary condensers used as supplemental
product recovery devices are not well suited for vent streams containing VOC
with low boiling points or for vent streams containing large quantities of
inerts such carbon dioxide, air, and nitrogen. Low boiling point VOC and
inerts contribute significantly to the heat load that must be removed from
the vent stream, resulting in costly design specifications and/or operating
costs. In addition, some low boiling point VOC cannot be condensed at normal
operating temperatures. For example, process units producing chlorinated
methanes have vent streams with substantial amounts of methane, methyl
chloride, and methylene chloride. These compounds are not readily condensed
and, as a result, are usually vented to the atmosphere or destroyed in a
combustion device. However, some difficult-to-condense vapors can be
compressed upstream of the condenser, thereby making them easier to recover
in the condenser.
3.3 SUMMARY
The two general classifications of VOC control techniques discussed in
the preceding sections are combustion and noncombustion control devices.
This section summarizes the major points regarding control device
applicability and performance.
The combustion control devices considered include flares, industrial
boilers, process heaters, thermal incinerators, and catalytic oxidizers.
With the exception of catalytic units, these devices are applicable to a wide
variety of process vent stream characteristics and can achieve at least
98 percent destruction efficiency. Combustion devices are generally, capable
of adapting to moderate changes in process vent stream flow rate and VOC
concentration, while control efficiency is not greatly affected by the type
of VOC present. This is generally not the case with noncombustion control
devices. In general, combustion control devices may require additional fuel,
except in some cases where boilers or process heaters are applied and the
energy content of the vent stream is recovered. Since boilers and process
heaters are important in the operation of a chemical plant, only process vent
streams that will not reduce boiler or process heater performance and
gep.002 3-28
-------
reliability warrant use of these systems. Application of a scrubber prior to
atmospheric discharge may be required when process vent streams containing
high concentrations of halogenated or sulfonated compounds are combusted in
an enclosed combustion device. The presence of high concentrations of
corrosive halogenated or sulfonated compounds may preclude the use of flares
because of possible flare tip corrosion and may preclude the use of boilers
and process heaters because of potential internal boiler corrosion. 47 The
presence of a halogen acid, such as HC1, in the atmosphere may cause adverse
health effects and equipment corrosion.
The noncombustion control devices discussed include adsorbers,
absorbers, and condensers. In general, although noncombustion devices are
widely applied in the industry, no one device is universally applicable to
SOCMI vent streams because of the many restrictions applying these devices
across a broad category of reactor process and distillation operation vent
streams. For example, adsorbers may not always be applicable to vent streams
with: (1) high VOC concentrations, (2) low molecular weight, and
(3) mixtures of low and high molecular weight compounds. These conditions
exist in many reactor process vent streams. Absorbers are generally not
applied to streams with VOC concentrations below 200 to 300 ppmv, while
condensers are not well suited for application to vent streams containing low
boiling point VOC or to vent stream with large inert concentrations. Even
though these restrictions exist, many condensers and absorbers are applied to
distillation and reactor process vent streams in the synthetic organic
chemical manufacturing industry to recover VOC. Control efficiencies for the
noncombustion devices considered vary from 50 to 95 percent for condensers
and absorbers and up to 95 percent for adsorbers.
gep.002 3-29
-------
3.4 REFERENCES
1. U.S. Environmental Protection Agency, OAQPS. Organic Chemical
Manufacturing Volume 4: Combustion Control Devices. Report 4.
Publication No. EPA-450/3-80-026. December 1980.
2. Klett, M.G. and J.B. Galeski. (Lockhead Missiles and Space Co.,
Inc.) Flare Systems Study. (Prepared for U.S. Environmental
Protection Agency.) Huntsville, Alabama. Publication
No. EPA-600/2-76-079. March 1976.
3. U.S. Environmental Protection Agency, OAQPS. Evaluation of the
Efficiency of Industrial Flares: Background-Experimental
Design-Facility. Research Triangle Park, N.C. Publication
No. EPA-600/2-83-070. August 1983.
4. Reference 1.
5. Letter from Matey, J.S., Chemical Manufacturers Association, to
Beck, 0., EPA. November 25, 1981.
6. Reed, R.J. North American Combustion Handbook. North American
Manufacturing Company, Cleveland, Ohio. 1979. p. 269.
7. Memo and attachments from Farmer, J.R., EPA:ESD to distribution.
August 22, 1980. 29 p. Thermal incinerator performance for NSPS.
8. Reference 7.
9. Devitt, T., et al. Population and Characteristics of Industrial
Boilers in the U.S., EPA Publication No. 600/7-79-178a.
August 1979.
10. U.S. Environmental Protection Agency. Fossil Fuel Fired Industrial
Boilers - Background Information Document, Volume 1: Chapters
1 - 9. Research Triangle Park, North Carolina. Publication
No. EPA-450/3-82-006a. March 1982. p. 3-27.
11. U.S. Environmental Protection Agency. A Technical Overview of the
Concept of Disposing of Hazardous Wastes in Industrial Boilers.
Cincinnati, Ohio. EPA Contract No. 68-03-2567. October 1981.
p. 44.
12. Reference 11, p. 73.
13. Hunter, S.C. and S.C. Cherry. (KVB.) NOx Emissions from Petroleum
Industry Operations. Washington, D.C. API Publication No. 4311.
October 1979. p. 83.
14. U.S. Environmental Protection Agency. Evaluation of PCB
Destruction Efficiency In an Industrial Boiler. Research Triangle
Park, North Carolina. Publication No. EPA-600/2-81-055a.
April 1981. pp. 4 - 10, 117 - 128.
gep.002 3-30
-------
15. u.s. Environmental Protection Agency. Emission Test Report on
Ethylbenzefle/StYrene. Amoco Chemicals Company (Texas City, Texas).
Research Triangle Park, North Carolina. EMB Report No. 79-OCM-13.
August 1979.
16. u.s. Environmental Protection Agency. Emission Test Report.
El Paso Products Company (Odessa, Texas). Research Triangle Park,
North Carolina. EMB Report No. 79-OCM-15. April 1981.
17. U.S. Environmental Protection Agency. Emission Test Report.
LJSS Chemicals (Houston, Texas). Research Triangle Park,
North Carolina. EMB Report No. 80-OCM-19. August 1980.
18. Reference 15.
19. Reference 16.
20. Reference 17.
21. Reference 1, Report 3.
22. U.S. Environmental Protection Agency. Office of Air and Waste
Management. Control Techniques for Volatile Organic Emissions from
Stationary Sources. Research Triangle Park, North Carolina. EPA
Publication No. EPA450/278002. May 1978. p. 32.
23. Kensori, R.E. Control of Volatile Organic Emissions. MetPro Corp.,
Systems Division. Bulletin 1015. Harleysville, Pennsylvania.
24. Reference 1, Report 3.
25. Phthalic Anhydride Emissions Incinerated Catalytically. Chemical
Processing. j (14):94. December 1982.
26. Reference 22. p. 53.
27. Stern, A.C. Air Pollution, Volume IV, 3rd Edition, New York, N.Y.:
Academic Press, 1977. p. 336.
28. Barnett, K.W. (Radian Corporation). Carbon Adsorption for Control
of VOC Emissions: Theory and Full Scale System Performance.
(Prepared for U.S. Environmental Protection Agency.) Research
Triangle Park, N.C. EPA Contract No. 68-02-4378. June 1988.
p. 3-52.
29. Reference 27, p. 356.
30. Reference 28, p. 3-30.
31. u.s. Environmental Protection Agency, OAQPS. Organic Chemical
Manufacturing Volume 5: Adsorption, Condensation, and Absorption
Devices. Report 2. Publication No. EPA-450/3-80- 027.
December 1980. p. 11-15.
gep.002 3-31
-------
32. Reference 31, p. 1-4.
33. Staff of Research and Education Association. Modern Pollution
Control Technology. Volume I, New York, Research and Education
Association, 1978. pp. 22-23.
34. Reference 31. p. 11-15.
35. Perry, R.H., and Ctiilton, C.H. Eds. Chemical Engineers Handbook.
6th Edition. New York. McGraw-Hill. 1984. p. 14-2.
36. Reference 22, p. 76.
37. Reference 27, p. 24.
38. Reference 22, p. 72.
39. Reference 31, p. Il-I.
40. Reference 35, p. 14-1.
41. Reference 31, p. 111-5.
42. Reference 31, Report 2, p. lI-i.
43. Reference 22, p. 84.
44. Reference 31, Report 2, p. IV-1.
45. Reference 31, Report 2, pp. 11-3.
46. Reference 31, Report 2, p. 111-5.
47. Reference 1, Reports 1 and 2.
gep. 002
3-32
-------
4. ENVIRONMENTAL IMPACTS
The environmental impacts associated with applying reasonably available
control technology (RACT) to SOCMI distillation and reactor process vent
streams are analyzed in this chapter. As discussed further in Chapter 6, the
recommended RACT is based on the combustion of certain SOCMI reactor and
distillation process vent streams to achieve a 98 weight percent voc
reduction. The requirements of RACT can be achieved at distillation and
reactor process facilities by either thermal incinerators or flares.
Therefore, the environmental impacts analysis assumes that RACT is
represented by thermal incineration and flaring.
The environmental impacts analysis considers effects on air quality,
water quality, solid waste and energy consumption. Ten model vent streams
derived from the emissions profiles presented in Appendix B are used to
assess these impacts. The model vent streams represent the range of flow
rates and heating values typical of SOCMI distillation and reactor process
vent streams. Table 4-1 presents the environmental impacts for the ten model
vent streams. Calculated impacts are based on the lowest costs control
technique (thermal incineration versus flares) for nonhalogenated streams and
on a thermal incinerator/scrubber system for halogenatecj streams.
4.1 AIR POLLUTION IMPACTS
Section 4.1.1 presents the uncontrolled VOC emissions from each model
vent stream and the expected VOC emission reductions from the application of
RACT. Section 4.1.2 discusses additional air quality impacts that may be
observed in applying RACT to specific reactor and distillation process vents.
Also included is discussion on possible impacts from the inefficient
operation of the control devices used to meet RACT requirements,
4.1.1 VOC Emission Impacts
The VOC emissions (Mg/yr) for the distillation and reactor model vent
streams in Table 4-1 were estimated using an assumption of 8,760 working
hours per year. Controlled emissions were calculated using a
98 weight-percent VOC reduction efficiency.
gep.002 4-1
-------
TABLE 4-1. ENVIRONMENTAL IMPACTS FOR DISTILLATION AND REACTOR MODEL VENT STREAMS
Air 1a acts
Energy I acts
Water Inpacts
Scrubber
wastewater flo F
(gal/yr)
Auxiliary
fuel use 0
(MMBtu/yr)
Electrical
demand per ventb
(Kw-hr/yr)
Model vent
stream typea
Uncontrolled
VOC eimissions 1
(Mg/yr)
Control ted
(Mgfyr)
Secondary NO
enissj sb.c
(Mg/yr)
Secondary Co
enjssjonsb.d
(Mg/yr)
Distillation
LFIH
5.2
0.1
0.07
0.011
1,125
16,180
57,392
IFHH
160
3.3
0.12
0.047
620
16
0
HFLH
490
9.8
0.62
0.139
9,009
7,033
0
HFHH
12,100
240
5.30
2.103
5,514
1,192,754
4,135,340
Average
1,600
32
0.35
0.141
641
426
0
Reactor
IFIH
16
0.3
0.06
0.010
289
13,033
46,237
LFHH
670
13
0.42
0.126
436
92,230
325,212
NFIH
110
2.2
7.37
0.370
1,114
9,016
0
HFHH
16,000
320
50.21
20.084
1,918
37,098
0
Average
640
13
2.07
0.828
862
3,918
0
aLFLH - low flow low heating value
LFHH - Low flow high heating value
NFLH - high flow low heating value
HFHH high fLow high heating value
Average average flow, average heating value
bf ηacts are based on the lower cost control technique (thermal incineration versus flaring) for nonhatognated sreasm ada on a thermal incinerator/scrubber
system for halogenated streams.
Cg ( ) emission factors used:
Incinerators: 200 pη in exhaust for -streams contraining nitrogen coepo&rids, and 21.5 pηm NO on all other streasni (based on test data).
flares: 0.05 lbfNNBtu (based on EPA 600/2-83-052)
dco emissions based on 20 tb/P scf (AP-42).
gep.002
-------
Uncontrolled VOC emissions from the distillation vent streams range from
about 5 Mg/yr for the Low Flow Low Heat (LFLH) model, to 12,000 Mg/yr for the
High Flow High Heat (HFHH) model. Uncontrolled VOC emissions from the
average distillation vent stream are 1,600 Mg/yr. The controlled VOC
emissions from the distillation vent streams range from 0.10 Mg/yr (LFLH) to
240 Mg/yr (HFHH), with 32 Mg/yr representing the average.
Uncontrolled VOC emissions from the reactor model vent streams range
from 16 Mg/yr (LFLH) to 16,000 Mg/yr (HFHH), with 640 Mg/yr representing the
average model vent stream. The controlled VOC emissions from the reactor
model streams range from 0.3 Mg/yr (LFLH) to 320 Mg/yr (HFHH), with 13 Mg/yr
representing the average.
4.1.2 Secondary Air Impacts
Other air quality impacts from the application of incinerator or flare
control technologies include secondary pollutants produced from the
combustion of vent streams containing VOC. Possible by-product emissions
from VOC combustion include NOx, SO 2 , CU, PM. Generally, the only
combustion-related secondary pollutants of any potential concern are NO and
co. Data are not available on CO emissions from thermal incinerators and
flares. However, a reasonable estimate can be made using the AP-42 factor
for natural gas combustion. Test data on NO emissions from thermal
incinerator and flares are available as discussed below.
Incinerator outlet concentrations of NOx are generally below 100 ppm
except for cases where the vent stream contains nitrogenous compounds. Test
data for a toluene diisocyanate process unit in the reactor processes
emissions profile showed a NOx concentration of 84 ppmv. 2 Testing at a
polymer and resin process unit using an incinerator for VOC control measured
NOx concentrations ranging from 20.2 to 38.6 ppmv. 3 The fuels tested were
mixtures of natural gas, waste gas, and/or atactic waste; incineration
temperatures ranged from 980 to 1,100°C (1,600 to 2,000°F). In a series of
seven tests conducted at three air oxidation process units, incinerator
outlet NOx concentrations ranged from 8 to 200 ppmv. 4 The maximum outlet NO
concentration was measured at an acrylonitrile (air oxidation) process unit,
which has a vent stream containing nitrogenous compounds. The NO
concentration measured at the other process units, where the vent streams do
not contain nitrogenous compounds, ranged from 8 to 30 ppmv, with a median
value of 21.5 ppm.
gep.002 4-3
-------
The use of flares for combustion may also produce NOx secondary air
pollution impacts. NOx concentrations were measured at two flares used to
control hydrocarbon emissions from refinery and petrochemical processes. One
flare was steam-assisted and other air-assisted, and the heat content of the
fuels ranged from 5.5 to 81 M/scm (146 to 2,183 Btu/scf). The measured NOx
concentrations were somewhat lower than those for incinerators, ranging from
0.4 to 8.2 ppmv. The ranges of relative NOx emissions per unit of heat input
are 7.8 to 90 g/GJ (0.018 to 0.208 lbs/10 6 Btu) for flares. 5
Table 4-1 presents the secondary air impacts for the ten model vent
streams. As shown, NOx emissions range from 0.06 Mg/yr for the LFLH
distillation vent stream to 50 Mg/yr for the HFHH Reactor vent stream. The
CO emissions range from 0.01 Mg/yr for the LFLH Reactor vent stream to
20 Mg/yr for the HFHH Reactor vent stream.
In addition to NOx and CO emissions, combustion of halogenated VOC
emissions may result in the release of halogenated combustion products to the
environment. Generally, streams containing halogenated VOC would not be
controlled by a flare. Incinerators are generally more capable of tolerating
the corrosive effects of halogenated VOC and its combustion by-products. In
addition, scrubbing is used to remove these halogenated compounds from an
incinerators flue gas. Generally, incineration temperatures greater than
870°C (1,600°F) are required to ensure 98 percent destruction of halogenated
VOC. For example, when incinerating chlorinated VOC at temperatures of
980 to 1,100°C (1,800 to 2,000°F), almost all chlorine present exists in the
form of hydrogen chloride (HC1). The HC1 emissions generated by thermal
oxidation at these temperatures can be efficiently removed by wet scrubbing. 6
As discussed further in Chapter 5, the cost of the scrubber was added to the
overall thermal incinerator system cost.
4.2 WATER POLLUTION IMPACTS
Control of VOC emissions using combustion does not typically result in
any significant increase in wastewater discharge. That is, no water
effluents are generated by the combustion device. However, the use of an
incinerator/scrubber system for control of vent streams with halogenated VOC
does result in slightly increased water consumption. In this type of control
system, water is used to remove the acid gas contained in the Incinerator
outlet stream. In most cases, any Increase in total process unit wastewater
would be relatively small and would not affect plant waste treatment or sewer
gep.002 44
-------
capacity. Table 4-1 presents the water pollution impacts for the ten model
vent streams. Scrubber wastewater flow ranges from less than 0.001/MGD
(million gallons per day) for the LFLH Reactor vent stream to 0.01 MGD for
the HFHH Distillation vent stream.
The absorbed acid gas may cause the water leaving the scrubber to have a
low pH. This acidic effluent could lower the pH of the total plant effluent
if it is released into the plant wastewater system. The water effluent
guidelines for individual states may require that industrial sources maintain
the pH of water effluent within specified limits. To meet these guidelines,
the water used as a scrubbing agent would have to be neutralized prior to
discharge to the plant effluent system. The scrubber effluent can be
neutralized by adding caustic (NaOH) to the scrubbing water. The amount of
caustic needed depends on the amount of acid gas in the waste gas. For
example, approximately 1.09 kg (2.4 pounds) of caustic (as NaOH) are needed
to neutralize 1 kg (2.2 pounds) of HC1.
The salt formed in the neutralization step must be purged from the
system for proper disposal. The methods of disposal include direct waste
water discharge into sewer systems, salt water bodies, brackish streams,
freshwater streams, deep well injection, and evaporation. Use of the latter
disposal method is not widespread, and data show that most plants currently
incinerating halogenated streams have state permits to dump the brine or use
on-site wells to dispose of salty wastewater at a relatively low cost. 7 The
increased water consumption and caustic costs were included in the projected
operating costs for control of halogenated vent streams using an
incinerator/scrubber system. The costs associated with the disposal of the
salty wastewater were judged not to be significant in comparison to the
control costs and, therefore, were not included in the projected cost impacts
presented in Chapter 5 8
An alternative to brine disposal is to use the brine as feed to chlorine
production. Such a use would be site specific, where there was a need for
the chlorine in subsequent syntheses, and where quantities of brine either
alone or in combination with other brine sources were adequate for economical
production.
The use of scrubbers to remove HC1 from the incinerator flue gas also
has the potential to result in small increases in the quantities of organic
compounds released into plant wastewater. However, only small amounts of
gep.002 4-5
-------
organics are released into the scrubber wastewater; the flow of wastewater
from the scrubber is small compared to total plant wastewater, especially in
installations where there are multiple chemical processing units using a
central wastewater treatment facility. Therefore, the increase in the
generation of organics in plant wastewater is not likely to be significant.
4.3 SOLID WASTE DISPOSAL IMPACTS
There are no significant solid wastes generated as a result of control
by thermal oxidation. A small amount of solid waste for disposal could
result if catalytic oxidation, instead of thermal oxidation, were used by a
facility to achieve RACT requirements. The solid waste would consist of
spent catalyst.
4.4 ENERGY IMPACTS
The use of incineration to control VOC from reactor and distillation
process vent streams requires fuel and electricity. Supplemental fuel is
frequently required to support combustion. Electricity is required to
operate the pumps, fans, blowers and instrumentation that may be necessary to
control VOC using an incinerator or flare. Fans and blowers are needed to
transport vent streams and combustion air. Pumps are necessary to circulate
absorbent through scrubbers that treat corrosive offgases from incinerators
combusting halogenated VOC. Fuel and energy usage requirements for
incinerators and flares are discussed in detail as part of the overall cost
methodology in Chapter 5.
Table 4-1 presents the estimated energy impacts associated with each
model vent stream from reactor and distillation units. These energy values
include both fuel and electricity usage estimates. As shown, auxiliary fuel
use ranges from zero for several vent streams to 5,514 MMBtu/yr for the HFHH
Distillation vent stream. Electrical demand per vent ranges from 16 Kw-hr
per year for LFHH Distillation vent stream to 92,230 Kw-hr per year for the
LFHH Reactor vent stream. Electricity generally accounts for a small
fraction of the total energy impacts, while fuel use accounts for the
remainder. Heat recovery systems may substantially affect fuel usage
requirements for incinerators.
gep.002 4-6
-------
4.7 REFERENCES
1. U.S. Environmental Protection Agency. Organic Chemical Manufacturing,
Volume 4: Combustion Control Devices. Office of Air Quality Planning
and Standards. Research Triangle Park, N.C. Publication
No. EPA-450/3-80-026. December 1980. P. 11-4, 11-6.
2. U.S. Environmental Protection Agency. Reactor Processes in Synthetic
Organic Chemical Manufacturing Industry - Background Information for
Proposed Standards. Research Triangle Park, N.C. EPA-450/3-90-016a.
3. Lee, K.W., et al., Radian Corporation. Polymers and Resins NSPS.
Volatile Organic Compound Emissions from Incineration. Emission Test
Report. ARCO Chemical Company, laPorte Plant, Deer Park, Texas.
Volume I: Summary of Results. Prepared for U.S. Environmental
Protection Agency. Research Triangle Park, N.C. EMB Report
No. 81-PMR-1. March 1982. p. 12-15.
4. U.S. Environmental Protection Agency. Air Oxidation Processes in
Synthetic Organic Chemical Manufacturing Industry - Background
Information for Proposed Standards. Research Triangle Park, N.C.
Publication No. EPA-450/3-82-OOla. January 1982. p. C-22.
5. McDaniel, M., Engineering Science. Flare Efficiency Study, Prepared for
U.S. Environmental Protection Agency. Washington, D.C. Publication
No. EPA-600/2-83-052. July 1983. 134 p.
6. Reference 4, p. 111-15.
7. Memo from Piccot, S.D., and Lesh, S.A., Radian Corporation, to Reactor
Processes NSPS file. August 29, 1984. 3 p. and attachments. Brine
Solutions from Chemical Manufacturing Processes: Alternatives for
Disposal
8. Memo from Stelling, J.H.E., Radian Corporation, to Distillation
Operations NSPS file. September 2, 1982. 1 p. Caustic and salt
disposal requirements for incineration.
gep.002 4-7
-------
5. COST ANALYSIS
5.1 INTRODUCTION
This chapter presents the costs associated with control options for
reducing volatile organic compound (VOC) emissions from distillation column
and reactor process vents. Control system elements, design assumptions, and
costing equations are provided for Incinerator and flare control systems.
For streams containing halogenated VOCs, the incinerator control system cost
includes a packed tower scrubber system to remove acidic vapors from the
incinerator flue gas.
Since SOCMI processes encompass a wide range of emission parameters, a
model stream approach was used to present example control system costs. Ten
model systems were selected from the distillation and reactor process
emission profiles to represent a broad spectrum of possible vent streams.
The model vent stream characteristics are presented in Appendix B. Because
flow rates, heating values, and VOC concentrations of the model streams vary
considerably, there is a large variation in system costs and cost
effectiveness values.
5.2 COST METHODOLOGY FOR INCINERATOR SYSTEMS
This section presents the methodology used to develop VOC control system
costs for incinerators and scrubbers. Incinerator costs were developed using
Chapters 2 and 3 of the OAQPS Control Cost Manual (OCCM). 1 Scrubber costs
were based on the procedure outlined in EPAs Handbook on Control
Technologies for Hazardous Air Pollutants (HAP), 2 with equipment costs
updated from recent technical journal information. 3
5.2.1 Thermal Incinerator Desl n Considerations
The thermal incinerator system consists of the following equipment:
combustion chamber, instrumentation, recuperative heat exchanger, blower,
collection fan and ductwork, quench/scrubber system (If applicable), and
stack. The OCCM contains further discussion of Incinerator control system
design. Control system elements and design assumptions specific to SOCK!
vent streams are discussed below. General incinerator design specifications
are presented In Table 5-1.
gep.003 5-1
-------
TABLE 5-1. INCINERATOR GENERAL DESIGN SPECIFICATIONS
Item Specification
Emission control efficiency 98 percent destruction
Minimum incinerator capacitya 500 scfm
Maximum incinerator capacity 50,000 scfm
Incinerator temperature
- nonhalogenated vent streams 870CC (1,600°F)
- halogenated vent streamsb 1,100°C (2,000°F)
Chamber residence times
- nonhalogenated vent streams 0.75 sec
- halogenated vent streamsb 1.00 sec
Auxiliary fuel requirement Natural gas required to maintain
incinerator temperature with 3 mole
percent excess oxygen in flue gas
Scrubber system Used when halogenated VOC is
present to remove corrosive
combustion by-products
- type Packed tower
- packing type 2-inch rings, carbon steel
- scrubbing liquid Water
- scrubber gas temperature 100°C (212°F)
aFor capital cost purposes. A minimum flow rate of 50 scfm was used for
determining operating costs.
bUsed when halogenated VOC are present due to the difficulty of achieving
complete combustion of halogenated VOC at lower temperatures.
gep.003 5-2
-------
5.2.1.1 Combustion Air Requirements
The amount of oxygen in the waste gas or that provided by the VOC is
important because it establishes the auxiliary combustion air required, which
has an impact on both the capital and operating costs of the thermal
oxidizer. This cost analysis assumes that the waste gas does not contain
free oxygen and that, therefore, auxiliary combustion air must be added. (In
other words, the vent-stream is essentially a mixture of VOC and an inert gas
such as nitrogen.) After combustion, the design excess oxygen content in the
incinerator flue gas is assumed to be 3 mole percent, which is based on
commonly accepted operating practice.
In order to calculate the amount of combustion air required to ensure a
flue gas 02 concentration of 3 mole percent, a complete stoichiometric
equation must be balanced for each compound present in the waste gas stream.
In many cases, the complete chemical composition of the waste stream is not
known. Thus, for the purpose of costing Incinerator systems for typical vent
streams encountered in the SOCMI, a design molecule approach was used for
halogenated and nonhalogenated waste gas streams.
The design molecule was based on a survey of typical values for carbon,
hydrogen, oxygen, sulfur and chloride ratios for group of 219 organic
compounds.. 4 For nonhalogenated streams, the average VOC molecular
composition of 68.3 percent carbon, 11.4 percent hydrogen and 20.3 percent
oxygen was used to calculate combustion air requirements. These weight
ratios correspond to a molecular formula of C2.88H 57 0 063 . For halogenated
streams, component averages of 34.3 percent carbon, 4.7 percent hydrogen, and
6.1 percent chlorine were used to predict combustion air requirements. This
corresponds to a molecular formula of C 2 86 H 4 7 Cl 171 . In both cases,
assuming zero percent 02 in the waste stream, a dilution ratio (mole of air
per mole of VOC) of approximately 18:1 Is required to achieve 3 percent 02 in
the incinerator flue gas.
5.2.1.2 Dilution Air Requirements . After the required combustion air
is calculated and added to the total vent stream flow, the overall heat value
(Btu/scf) of the stream is recalculated. Addition of combustion air will
effectively dilute the stream and lower the heat content of the combined
stream fed to the incinerator. However, if the heat content of the vent
stream is still greater than 98 Btu/scf for nonhalogenated streams or greater
than 95 Btu/scf for halogenated streams, then additional dilution air must be
gep.003 5-3
-------
added to ensure these maximum heat content levels are not exceeded. The
imposition of a maximum heat content level prevents the temperature In the
incinerator from exceeding the design specifications.
The minimum flow rate to the Incinerator is 50 scfm. It is assumed that
vent streams smaller than 50 scfni will be mixed with air to achieve this
minimum flow rate. The maximum Incinerator flow rate is 50,000 scfm. Flow
rates greater than this will be handled by multiple Incinerators In this cost
analysis.
5.2.1.3 Recu eratlve Heat Recovery . Halogenated vent streams are not
considered candidates for heat recovery systems, and are costed assuming zero
percent heat recovery. This conservative design assumption is imposed
because of the potential for corrosion in the heat exchanger and
incinerator. If the temperature of the flue gas leaving the heat exchanger,
Tf 0 , were to drop below the acid dew temperature, condensation of acid gases
would result. Significant corrosion can lead to shortened equipment life,
higher maintenance costs, and potentially unsafe working conditions.
Nonhalogenated vent streams are considered candidates for recuperative
heat recovery. The extent of heat recovery depends on the heat value of the
vent stream after dilution. Four different heat recovery scenarios are
evaluated for nonhalogenated streams. The cost algorithm includes systems
with 0, 35, 50 and 70 percent heat recovery. The extent of heat exchange to
be utilized is decided by an economic optimization procedure with the
following restrictions. No heat recovery is allowed for vent streams with a
heat value greater than 25 percent of the lower explosive l.imit (LEL), due to
the possibility of explosion or damaging temperature excursions within the
heat exchanger. This limit typically corresponds to a heat content of
13 Btu/scf. Therefore, if the heat content of the total vent stream, even
after addition of required combustion and dilution air, is still greater than
13 Btu/scf, no heat recovery for the entire stream is allowed. For streams
with a heat content less than 13 Btu/scf, the entire stream Is preheated in
the recuperative heat exchanger, allowing for maximum energy recovery.
However, for streams with a heat content greater than 13 Btu/scf, the
flammable vent gas stream cannot be preheated, but the combustion/dilution
air stream can. In this case, the cost optimization procedure evaluates the
Option of preheating only the air stream, and combines the VOC stream with
the preheated air stream in the incinerator.
gep.003 5-4
-------
AU allowable heat recovery percentages are evaluated and the calculated
total capital and annual costs are based on the most cost effective
configuration. The tradeoff between the capital cost of the equipment and
the operating cost (fuel) of the system determines the optimum level of
energy recovery.
5.2.1.4 Incinerator Design Temperature . The destruction of VOC is a
function of incinerator temperature and residence time In the combustion
chamber. The design VOC destruction efficiency is 98 weight-percent, which
can be met by well-designed and well-operated thermal incinerator systems.
Previous EPA studies show that 98 weight-percent destruction efficiency can
be met in a thermal incinerator operated at a temperature, of 1600°F and
a residence time of 0.75 second. Thermal oxidation of halogen containing VOC
requires higher temperature oxidation to convert the combustion product to a
form that can be more readily removed by flue gas scrubbing. For instance,
chloride-containing waste gases are burned at high temperature to convert the
chlorine to HC1 instead of to Cl 2 , since HC1 is more easily scrubbed.
Available data indicate that a temperature of 2,000 0 F and residence time of
I second are necessary to achieve 98 weight-percent VOC destruction
efficiency for halogen-containing waste gas streams. Chapter 3 contains
additional details on thermal incinerator performance.
5.2.2 Thermal Incinerator Capital Costs
The costing analysis follows the methodology outlined in the OCCM.
Equipment cost correlations are based on data provided by various vendors;
each correlation is valid for incinerators in the 500 to 50,000 scfm range. 5
Thus, the smallest incinerator size used for determining equipment costs was
500 scfm and for flow rates above 50,000 scfm additional incinerators were
costed.
Purchased equipment costs (PEG) for thermal incinerators are given as a
function of total volumetric throughput, Qtot , in scfm. Four equations were
used In the costing analysis, each pertaining to a different level of heat
recovery (HR):
PEG 10294 Qtot 02355 HR 0%
PEC - 13149 Qtot 02609 HR 35%
PEC 17056 Qtot 02502 HR 50%
gep.003 5-5
-------
PEC 13149 Qtoto.2500 HR 70%
The cost of ductwork (not included in PEC) was calculated based on
1/8 carbon steel with two elbows per 100 feet, using the equation in
Reference 6. The length of duct was assumed to be 300 feet. Collection fan
costs were developed using methods in Reference 7. The duct and fan costs
are added to the total equipment cost and installation factors applied to
this total.
Installation costs are estimated as a percentage of total equipment
costs. Table 5-2 lists the values of direct and indirect installation
factors for thermal incinerators.
5.2.3 Thermal Incinerator Annualized Cost
Annualized costs for the thermal incinerator system include direct
operating and maintenance costs, as well as annualized capital charges. It
should be pointed out that vendor contacts indicate that an incinerator
turndown ratio of 10/1 is available. 8 Consequently, the minimum flow rate
for determining operating costs Is assumed to be 50 scfm. Additional
dilution air is added where necessary to raise the fuel-waste gas-air mixture
to 50 scfm. The bases for determining thermal incinerator annualized costs
are presented in Table 5-3. Each cost parameter is reviewed below.
5.2.3.1 Labor Costs . The operating labor requirements vary depending
on the components of the overall system. Incinerator systems not employing a
scrubber require the least amount of operating labor (548 hrs/yr or 0.5 hours
per 8 hour shift). Systems employing a scrubber require an additional
548 hrs/yr operating labor. Maintenance labor requirements are assumed to be
identical to operating labor requirements, i.e., 548 hrs/yr for the
incinerator and 548 hrs/yr for the scrubber. Supervisory cost Is estimated
to be 15 percent of the operating labor cost. The maintenance labor hourly
rate is assumed to be 10 percent higher than the operating labor hourly rate.
5.2.3.2 Capital Charges . Return on investment for the incinerator
system is not included, but the cost of the capital Investment Is accounted
for in evaluating total annual costs. The capital recovery factor (0.163) is
based on a 10 percent interest rate and a 10-year life for the equipment.
Taxes, insurance, and administrative costs are assumed to be 4 percent of the
total capital investment. Overhead Is estimated to be 60 percent of the
total labor and maintenance costs.
gep.003 5 -6
-------
TABLE 5-2. CAPITAL COST FACTORS FOR THERMAL INCINERATORSa
Cost item
Direct Costs
Factor
Purchased equipment costs
Incinerator (EC) + auxiliary equipmentb
Instrumentat I onC
Sales taxes
Freight
Purchased equipment cost, PEC
Direct installation costs
Foundations and supports
Handling and erection
Electrical
Piping
Insulation for ductworkd
Painting
Direct installation cost
As estimated, A
0.10 A
0.03 A
0.05 A
B 1.18
A
0.08
B
0.14
B
0.04
B
0.02
B
0.01
B
0.01
B
0.30 B
Site preparation
Buildings
Total Direct costs, DC
As required, SP
As required., Bldg .
1.30 B + SP + Bldg.
Engineering
Construction and field expenses
Contractor fees
Start-up
Performance test
Conti ngencies
Total Capital investment DC + 1C
1.61 B + SP + Bldg.
included with unit furnished
the incinerator, and thus
Indirect Costs (Installation )
Total Indirect Cost, IC
0.10
0.05
0.10
0.02
0.01
0.03
B
B
B
B
B
R
0.31 B
aReference 1.
bOuctwork and any other equipment normally not
by incinerator vendor.
Cjnstrumentation controls often furnished with
often included in the EC.
djf ductwork dimensions have been established, cost may be estimated based
on $10 to $12/ft 2 of surface area for field application. Fan housings and
stacks may also be insulated.
gep. 003
5-7
-------
TABLE 5-3. ANNUAL OPERATING COST BASIS FOR THERMAL INCINERATORS
Direct Operating Cost Factors
Hours of operation (hrs/yr)
Operating labor (manhours)
Incinerator (0.5 hrs/8 hr shift)
Incinerator with scrubber (1 hr/S hr shift)
Maintenance labor (manhours) per Incinerator
Incinerator (0.5 hr/8 hr shift)
Incinerator with scrubber (1 hr/S hr shift)
Labor rates ($/hr) based on 1990 data
Operating labor
Maintenance labor
Supervisory cost
Maintenance materials cost
Utilities (1990 $)
Electricity ($11,000 kWh)
Natural Gas (4/106 Btu)
Indirect Operating Cost Factors
Equipment life (years)
Interest rate (percent)
Capital recovery factor
Taxes, insurance, administration (percent of total
installed cost)
Overhead
8,760
548
1,096
548
1,096
15.64
17.21
15% of Operating Labor
Cost
100% of Maintenance
Labor Cost
59.0
3.30
10
10
0.163
4
60% of Total Labor and
Maintenance Costs
gep.003
5-8
-------
5.2.3.3 Utility Costs . The utilities considered in the annual cost
estimates include natural gas and electricity. The procedures for estimating
electricity and supplemental fuel requirements are described in Chapter 3 of
the OCCM.
5.2.3.4 Maintenance Costs . Maintenance labor costs are discussed
above. Maintenance material costs are assumed to be equal to maintenance
labor costs.
5.3 COST METHODOLOGY FOR FLARE SYSTEMS
This section presents the methodology used to develop VOC control
system costs for flares. Flare design aspects and costs are based on
Chapter 7 of the OCCM.
5.3.1 Flare Design Considerations
The flare design consists of an elevated, steam-assisted, smokeless
flare. Elements of the flare system include knock-out drum, liquid seal,
stack, gas seal, burner tip, pilot burners, and steam jets. For flare system
sizing, correlations were developed relating process vent stream flow rate
and heat content value to the flare height and tip diameter. The general
design specifications used in developing these correlations are discussed
below and presented in Table 5-4.
Flare height and tip diameter are the basic design parameters used to
determine the installed capital cost of a flare. The tip diameter selected
is a function of the combined vent stream and supplemental fuel flow rates,
and the assumed tip velocity. Supplemental fuel requirements and tip
velocity values are shown in Table 5-4. DeterminatIon of flare height Is
based on worker safety requirements. The flare height is selected so the
maximum ground level heat intensity Including solar radiation Is 2,525 W/m 2
(800 Btu/hr ft 2 ). Vendor contacts indicate the smallest elevated flare
commercially available is 30 feet high and 1 inch In diameter. For vent
streams requiring smaller flare systems, this Is the minimum flare size used.
After flare tip diameter (D) and flare height (H) are determined, the
natural gas required for pilots and purge, and the mass flow rate of steam
required are calculated. Pilot gas Consumption is a function of the number
of pilots and, In turn, of the tip diameter as shown In Table 5-4. The
number of pilots is selected based on the tip diameter. The pilot gas
gep.003 5-9
-------
TABLE 5-4. FLARE GENERAL DESIGN SPECIFICATIONS
Spcification
98 percent destruction
Elevated, steen assisted
Smokeless flare
300 Btu/scf of gas being contusted
2.5 cm (1.0 inch)
9.1 m (30 ft)
2,525 U/rn 2 (800 gtu/hr ft 2 )
MV 11.2 (300): v a 18.3 m /s (60 ft/a) + natural gas
to 11.2 Li/Mu? (300 Btu/scf)
11.2 (300) < HV 37.3 (1,000): Log(V) (MV + 1,214)/852
MV > 37.3 (1,000): V 122 rn/s (400 ft/s)
0.3
Nurter of Pilots Tip Diameter
1
D 25
(DS10)
2
25D 61
(10Ds24)
3
61D 152
(24D 60)
4
0>152
(0>60)
2.0 m 3 /hr (70 scf/hr) of natural gas per pilot
0.4 kg steam/kg vent gas
Watural gas added to maintain a mininur fLare tip veLocity of
0.01 rn/s (0.04 ft/s)
NaturaL gas required to maintain vent strewn MV of 11.2 NJ/Mn 3
(300 Btu/scf for V 18.3 rn/s (60 ft/s)
alr L 4ing solar radiation of 300 Btu/hr ft 2 .
bhV = Heat content value of process vent stream, NJ/Mn? (Btu/scf). A flare tip velocity equal to 80 percent of the
maxini.ir smokeless velocity (18.3 rn/s (60 ft/sJ) is used in the costing equations.
C 0 tip diameter, cm (inch).
ddv flare tip velocity, rn/s (ft/s).
Emission control efficiency
General flare design
mininLr net heating valve
- mininun flare tip diameter
miniurn.r flare height
maxim r gourd Level heat lntensitya
fLare tip vetocitiesb
emissivity
nurter of pitots
pilot gas requirement
- steam requirement
purge gas requirement
SuppLemental fueL requirementd
gep.003
5-10
-------
consumption is calculated based on an energy-efficient model of 70 scf/hr per
pilot burner. The purge gas requirement is also a function of the tip
diameter and the minimum design purge gas velocity of 0.04 ft/sec at the tip,
as shown in Table 5-4. A design flare tip velocity (48 ft/sec) equal to
80 percent of the maximum smokeless velocity is used in the costing
equations. Steam use is that flow which maintains a steam to flare gas ratio
of 0.4 kg steam/kg vent gas.
5.3.1 Development of Flare Capital Costs
The capital cost of a flare is based on vendor supplied information as
described in the OCMM cost equations are developed from a regression analysis
of the combined data set over a range of tip diameters and flare heights.
Flare equipment costs (CF) are calculated based on stack height, H, (ft) and
tip diameter, D, (in), according to support type as follows:
Self Support Group:
CF [ 78.0 + 9.14(D) + 0.749(H)) 2
Guy Support Group:
CF [ 103 + 8.68(0) + 0.470(H)] 2
Derrick Support Group:
CF [ 76.4 + 2.72(0) + 1.64(H)] 2
The flare equipment cost includes the flare tower (stack) and support, burner
tip, pilots, utility piping from base, utility metering and control, water
seal, gas seal, and galvanized caged ladders and platforms as required. The
material of construction basis is carbon steel, except for the upper 4 feet
and burner tip, which is 310 stainless steel.
Vent stream piping costs, Cp, are a function of pipe, or flare,
diameter, D, and length of piping.
C 508 (D) l. 21 (where 1 < 0 < 24 )
C 556 (D) 1 .° 7 (where 30 < D < 60)
These costs include 400 feet of straight piping and are directly proportional
to the distance required.
gep.003 5-11
-------
Knock-out drum costs CK, are a function of drum diameter, d (in) and
drum thickness, t (in).
CK 14.2 ((d)(t)(h + 0.812(d)]° 737
Total flare system equipment cost is the sum of flare, piping, and
knock-out drum costs.
EC CF + CK + Cp
Purchased equipment cost, PEC, is equal to equipment cost, EC plus factors
for ancillary equipment (i.e., instrumentation at 0.10, sales taxes at 0.03,
and freight at 0.05). Installation costs are estimated as a percentage of
total equipment costs. The total capital investment, TCI, Is obtained by
multiplying the purchased equipment cost, PEC, by an Installation factor
of 1.61.
5.3.2 Development of Flare Annualized Costs
The annualized costs include direct operating and maintenance costs, and
annualized capital charges. The assumptions used to determine annualized
costs are presented in Table 5-5, and are given in first quarter
1990 dollars. Direct operating and maintenance costs include operating and
maintenance labor, replacement parts, and utilities.
5.3.3.1 Labor Costs . The operating labor requirements are 500 hrs/yr
for typical flare systems. Supervisory labor is estimated to be 15 percent
of the operating labor cost. Maintenance labor is assumed to be 10 percent
higher than the operating labor cost.
5.3.3.2 Capital Charges . The capital recovery factor (0.1314) is based
on a 10 percent interest rate and a 15-year life for the equipment. Taxes,
insurance and administrative costs are assumed to be five percent of the
total capital investment.
5.3.3.3 Utility Costs . The utilities considered in the annual cost
estimates include natural gas and electricity. The procedures for estimating
electricity and supplemental fuel requirements are described In Chapter 4 of
the OAQPS Cost Manual.
5.3.3.4 Maintenance Costs . Maintenance labor costs are discussed
above. Maintenance material costs are assumed to be equal to maintenance
labor costs.
gep.003 5-12
-------
TABLE 5-5. ANNUAL OPERATING COSTS FOR FLARE SYSTEMS
Direct Annual Costs
Operating Labor
Supervision
Maintenance
Mal ntenance
Natural Gas
Indirect Annual Costs
Overhead
Capital Recovery Factor
General and Administrative,
Taxes, and Insurance
Factor/Basis
630 manhours/yr
15% of operating labor
1/2 hour per shift
equal to maintenance labor
)
)
) All utilities equal to:
)consumption rate * hours/yr *
) unit cost
)(Natural Gas $330/106 Btu)
)(Electricity $59.0/1,000 kWh)
)(Steam $5.30/1,000 ib)
60% of total labor costs
01314 (assuming 15 year life at 10%)
(4% of total Installed capital)
Labor
Materials
- Pilot Gas
- Auxiliary Fuel
- Purge Gas
Steam
Electricity
gep .003
5-13
-------
54 COMPARISON OF CONTROL SYSTEM COSTS
This section presents and discusses the capital costs, annualized costs,
average cost effectiveness, and natural gas costs for the application of
incinerators or flares to representative SOCMI vent streams. These costs are
determined by applying the costing methodology, developed In the previous
sections, to the 10 model vent streams described in Appendix B.
For a specific combustion control system, capital and annualized costs
vary with vent stream flow rate and heat content. Therefore, five reactor
process vent streams and five distillation vent streams are. used as examples
to show how the costs of control vary for vent streams with a wide range of
vent stream characteristics. These example cases are selected from the
emission profiles in Appendix B and represent the range of vent stream
characteristics found. Stream characteristics for the 10 example cases are
as follows:
Case 1 - reactor process - low flow rate, high heat content - (R-LFHH);
Case 2 - reactor process - low flow rate, low heat content - (R-LFH);
Case 3 - reactor process - high flow rate, high heat content - (R-HFHH);
Case 4 - reactor process - high flow rate, low heat content - (R-HFLH);
Case 5 - reactor process - medium flow rate and medium heat content -
(R-AVG);
Case 6 - distillation - low flow rate, high heat content - (D-LFHH);
Case 7 - distillation - low flow rate, low heat Content - (D-LFLH);
Case 8 - distillation - high flow rate, high heat content - (D-HFHH);
Case 9 - distillation - high flow rate, low heat content - (D-HFLH);
Case 10 - distillation - medium flow rate and medium heat content -
(D-AVG);
Table 5-6 presents the results of the costing analysis for the
10 example SOCMI vent streams. The values presented are the lower cost
control option (thermal incineration versus flaring) for nonhalogenated
streams. For halogenated streams, the values in the table represent the cost
of a thermal incineration/scrubber system.
Table 5-6 shows that average cost effectiveness for each control system
varies with the vent stream characteristics. The lowest COSt-effectiveness
gep.003 5-14
-------
TABLE 5-6. COST RESULTS FOR MODEL SOCMI VENT STREAMS
Total
Source
ID
Halogenation
status
Control device
Total
inlet flow
(scfn,)
Inlet VOC
flow rate
(lb/hr)
Inlet
Pieat value
(Btu/scf)
amissions
rethiction
(Ng/yr)
Natural
gas cost
(S/yr)
Capital
cost
( 5/yr)
Annual
cost
( 5/yr)
Cost
effectiveness
(S/Mg re,aoved)
R-LFNH
H
Incin + Scrtkber
20
168
1,286
653.5
1,432
127alO
124,859
191
R-LFLH
H
mom + Scrt.th er
40
3.6
40
14.0
953
120,931
118,092
8,433
R-HFHN
NH
FLare
5,429
4,046
776
15,738
6,318
191,009
180,606
11
R-NFLH
NH
Thenaet Incineration
1,080
27
70
105
3,677
110,317
72,501
690
i-AVG
NH
Flare
574
161
300
626
2,841
72,886
66,746
107
D-LFNN
NH
FLare
2.6
41
2,870
160
2,046
29,089
55,384
347
0-1 11 1 1
H
Incin + Scri4 er
2.6
1.3
62
5
3,715
121,342
121,132
23,954
0-111MM
H
Incin + Scrtg,ber
535
3,050
804
11,864
18,190
240,026
232339
20
D-NF IH
NH
Theri L Incineration
637
123
19
478
29,733
104,572
97.258
203
D-AVG
NH
FLare
63
63
649
247
2,114
37,422
56,834
230
gep.003
-------
value shown occurs for the vent stream (Case 3) with the highest vent stream
energy flow (i.e., (flow rate) x (heat content), in NJ/mm). The cost
effectiveness for Case 3 Is about $10/Mg. In general, the low cost
effectiveness values for high energy content vent streams are a result of the
large mass of VOC available to support combustion and, subsequently, the low
supplemental fuel costs. Also, relatively large VOC emission reductions
occur for these streams, which greatly decreases cost effectiveness.
Table 5-6 also shows the highest cost effectiveness occurs for vent
streams with a low energy flow (Case 7). This occurs even though this type
of stream does not have extremely high annualized costs. For Case 2, cost
effectiveness is $21,770/Mg with incinerations. Application of controls to
this low heat content stream results In moderately low costs but very low
emissions reductions. A relatively small amount of VOC is controlled because
of the low VOC content and low flowrate associated with this vent streams.
gep.003 5-16
-------
5.5 REFERENCES
1. U.S. Environmental Protection Agency. OAQPS Control Cost Manual.
Office of Air Quality Planning and Standards. Research Triangle Park,
North Carolina. EPA-450/3-90-006. January 1990.
2. U.S. Environmental Protection Agency. Control Technologies for
Hazardous Air Pollutants. Air and Energy Engineering Research Lab.
Research Triangle Park, North Carolina. EPA-625/6-86-014.
3. Vatavuk, William. Chemical tngjneering . May 1990.
4. U.S. Environmental Protection Agency. Organic Chemical Manufacturing
Series. Volume 4: Combustion Control Devices. Office of Air Quality
Planning and Standards. Research Triangle Park, North Carolina.
EPA-450/3-80-026d.
5. Reference 1.
6. Vatavuk, William. Chemical Engineering . May 1990.
7. Richardson Engineering Services, Inc. The Richardson Rapid System
Process Plant Cost Estimating Standards. Volume 3, 1988.
8. Telecon. Stone, D.K., Radian Corporation with E. David, ARI Technology.
January 18, 1990. Incinerator sizes and turndown.
gep.003 5-17
-------
6. SELECTION OF RACT
This chapter provides State and local regulatory authorities with
guidance on the selection of reasonably available control technology (RACT)
for VOC emissions from SOCMI reactor processes and distillation operations.
Background on the regulatory authority and goals for establishment of RACT is
discussed in Section 6.1. The technical basis for R.ACT is discussed in
Section 6.2, while the approach for applying RACT is described in
Section 6.3. Section 6.4 presents the impacts of RACT on example vent
streams. Finally, Section 6.5 provides an overall summary of RACT for this
source category.
6.1 BACKGROUND
The Clean Air Act Amendments 0 f 1990 mandate that State Implementation
Plans (SIPS) for certain ozone nonattainment areas be revised to require the
implementation of RACT to limit volatile organic compound (VOC) emissions
from sources for which EPA has already published a control techniques
guideline (CTG) or for which it will publish a CTG between the date the
amendments are enacted and the date an area achieves attainment status.
Section 172(c)(1) requires that nonattainment area SIPs provide for the
adoption of RACT for existing sources. As a starting point for ensuring that
these SIPs provide for the required emissions reduction, EPA has defined RACT
as ...the lowest emission limitation that a particular source is capable of
meeting by the application of control technology that is reasonably available
considering technological and economic feasibility. RACT for a particular
industry is determined on a case-by-case basis, considering the technological
and economic circumstances of the individual source category. l EPA has
elaborated in subsequent notices on how RACT requirements should be
appi ied. 2 3
The CTG documents are intended to provide State and local air pollution
authorities with an information base for proceeding with their own analysis
of RACT to meet statutory requirements. These documents review existing
gep.003 6-1
-------
information and data concerning the technical capability and cost of various
control techniques to reduce emissions. Each CTG document contains a
recommended presumptive norm for RACT for a particular source category,
based on EPAs current evaluation of capabilities and problems general to the
source category. However, the presumptive norm is only a recommendation.
Where applicable, EPA recommends that regulatory authorities adopt
requirements consistent with the presumptive norm level, but authorities may
choose to develop their own RACT requirements on a case-by-case basis,
considering the economic and technical circumstances of the individual source
category.
6.2 TECHNICAL BASIS FOR RACT
The technology underlying RACT for SOCMI reactor process and
distillation operations is combustion via either thermal incineration or
flaring. These techniques are applicable to all SOCMI reactor processes and
distillation operations and can generally achieve the highest emission
reduction among demonstrated VOC control technologies. Thermal incinerators
can achieve at least 98 weight-percent reduction of VOC emissions (or
reduction to 20 ppmv) for any vent stream if the control device is well
operated and maintained. Likewise, EPA has presumed that flares can achieve
at least 98 weight-percent control of VOC emissions if the design and
operating specifications given at 40 CFR 60.18 are met. (Chapter 3 contains
more detail on the performance capabilities of thermal incinerators and
flares as applied to SOCMI vent streams.) Although the control level
representing RACT is based on the application of thermal incineration or
flaring, it does not specify these techniques as the only VOC control methods
that may be used. Any combustion device can be used to comply with RACT
requirements as long as the 98 weight-percent destruction or 20 ppmv emission
limit is met.
Other VOC control technologies were considered in the RACT evaluation,
including catalytic incinerators, carbon adsorbers, condensers and absorbers.
However, for several reasons these technologies were rejected as the basis
for the recommended presumptive norm for RACT. Catalytic incinerators cannot
achieve 98 weight-percent control in all cases. Also, they cannot be applied
to all SOCMI vent streams because certain compounds that may be present in
the vent stream (i.e., heavy metals) can deactivate the catalyst. Likewise,
gep.003 6-2
-------
carbon adsorbers cannot achieve 98 weight-percent control in all cases and
may not be applicable to certain vent streams (i.e., containing sulfur
compounds or heavy metals) due to problems with carbon bed fouling. Finally,
secondary condensers and absorbers, while effective for certain SOCMI vent
streams, cannot achieve 98 weight-percent control In all cases because they
are highly dependent on the type and concentration of organic compounds
present in the vent stream. As explained in Section 6.5, recovery devices
such as adsorbers can be used as pollution prevention techniques to meet the
cutoffs described in Section 6.3.
In summary, the control level for RACT is represented by a VOC emission
reduction of 98 weight-percent or reduction to 20 ppmv. The next section
discusses how to determine which vent streams should apply control.
Facilities may opt to install product recovery devices to reduce emissions
below the cutoff levels instead of controlling emissions by 98 weight-percent
or to 20 ppmv.
6.3 RACT SIZE CUTOFFS
Vent streams from reactor processes and distillation operations can vary
widely in flow rate, VOC concentration, heating value, and VOC emission rate.
Therefore, the uncontrolled emissions, emission reductions and control costs
can also vary considerably for different vent streams. Accordingly, it may
not be reasonable from a technical or economic standpoint to apply controls
to all distillation and reactor vent streams.
Important vent stream parameters in determining the emission reduction
and cost impacts of control are flow rate, heating value, and VOC emission
rate. Flow rate determines control device sizing and, therefore, equipment
cost. Vent stream heating value determines how much supplemental fuel is
necessary to support combustion. The VOC emission rate determines the amount
of emissions that can potentially be reduced. It should be noted that
heating value is closely related to VOC concentration. Similarly, VOC
emission rate is dependent on the flow rate and VOC concentration. In
general, as flow rate and VOC concentration Increase, the VOC emission
reduction achievable by controlling these streams increases and they become
more cost effective to control. Alternatively, if the flow rate and VOC
concentration are low, the achievable VOC emissions reduction is low and the
cost effectiveness of control is high.
gep.003 6-3
-------
Several basic approaches are available for determining which vent
streams to control. These approaches are based on an analysis of VOC
emission reduction and control cost Impacts as a function of the following
parameters: (1) VOC concentration cutoff, (2) vent stream flow rate cutoff,
and (3) flow rate and concentration cutoff. It is important to note that
minor variations in the basic approaches are possible. For example, heating
value can be substituted for VOC concentration as the key cutoff parameter
(see Approach A). Also, VOC emission rate can be substituted for flow rate
and VOC concentration (see Approach C).
6.3.1 A oroach A - Concentration Cutoff
One approach to determining which vent streams to control is to make the
decision to control based only on the VOC concentration of the vent stream.
The concentration of volatile organic compounds would be defined as the
amount of total organics detected using EPA Reference Method 18. All vent
streams exceeding the VOC concentration cutoff would require control
regardless of the flow rate. This approach has the advantage of requiring
measurement of only one parameter-the VOC concentration. It also ensures
that all highly concentrated VOC streams are controlled, A concentration-
only approach could potentially achieve a high degree of emission reduction;
however, it would likely do so by requiring control of vent streams with low
flow rates that have relatively low VOC emissions and are less cost effective
to control. In this approach there could also be some high flow rate vent
streams with relatively high VOC emissions that would be reasonable to
control, but escape control because of low concentrations of VOC.
6.3.2 ADoroach B - Flow Rate Cutoff
Another approach to determining which vent streams to control is to make
the decision to control based only on the flow rate of each vent stream. All
individual streams exceeding the flow rate cutoff would require control.
This approach has the advantage of requiring measurement of only one
parameter-flow rate. A flow rate-only approach could potentially achieve a
high degree of emission reduction; however, it would likely do so by
controlling vent streams with low concentrations of VOC that have relatively
small VOC emissions and are less cost effective to control. In this approach
there could also be some vent streams with high concentrations of VOC and
relatively high VOC emission potential that would be cost effective to
control, but escape control because they have a low flow rate.
gep.003 6-4
-------
6.3.3 ADoroach C - Concentration with Flow Rate Cutoff
A third approach to determining which vent streams to control is to
establish a combination of a minimum VOC concentration and minimum flow rate.
The VOC concentration and flow rate would be determined for each individual
vent stream. Any vent stream exceeding both the VOC concentration and flow
rate would be required to control. This approach would reduce the number of
low flow rate (and, therefore, low emission rates) streams that would have to
be required controlled under the concentration-only approach. It would also
reduce the number of vent streams with low VOC concentrations (and,
therefore, low emission rates) that would have required control under the
flow rate-only approach.
6.4 IMPACTS OF APPLYING VARIOUS CONCENTRATION/FLOW RATE CUTOFFS
This section describes the impacts of applying various concentration and
flow rate cutoffs to SOCMI reactor process and distillation vent streams.
Options for the recommended presumptive norm for RACT have been identified
using Approach C; that is, the cutoff points are established using a
combination of flow rate and VOC concentration. Thus, the impacts analysis
assumes that any vent stream having both a flow rate and VOC concentration
above the selected cutoff points would be required to reduce emissions by
98 weight-percent (or to 20 ppmv) via thermal incineration or flaring.
Table 6-1 summarizes the impacts of various options for the recommended
presumptive norm for RACT. These impacts were calculated for a population of
model vent streams that represents a subset of SOCMI reactor process and
distillation facilities. National impacts were calculated by scaling up
impacts that would be incurred by a typical population of facilities for this
source category.* A discussion of the procedure for estimating impacts
incurred by the model vent stream population is contained in Reference 5.
After reviewing the impacts in Table 6-1, EPA has selected a cutoff of
0.05 weight percent VOC and 0.1 scfm as the recommended presumptive norm for
RACT. This cutoff level would reduce an estimated 99 percent of the
*In order to avoid double-counting, national impacts include only those
impacts resulting from control after the implementation of the Hazardous
Organics NESHAP has occurred. The SOCMI CTG and HON Process Vents
regulatory actions will affect many of the same vents at SOCMI plants. In
addition, only facilities in nonattainment areas are considered subject to
the CTG.
gep.003 6-5
-------
TABLE 6-1. SOCMI RACT IMPACTS---HALOGENATED AND NONHALOGENATED VENT STREAMSa
Nat lanai
NatIonal se ioeiary National
Strew VOC eulission eIetssIons secondary
Flow rate VOC weight controi td reductionC of NO. , (Mlut)d eunssions of toe National jupectsC
*,tiOfl (scf,u) ( ) (X) (Mg yr) (Mgtyr) (NgIyr) ( 5/yr)
Average eulsaion
re(SKt ion per vent in
Average CE lncrem.ntal CE incraapnt controlled
(S/Mg) (S /Mg) (NO/yr)
Average
COSt Pei vent in
increment contro( led 9
(If yr)
100
4,800
162
(47)
70
5 1 100 ,000
1,220
0.1
0.05
89
4,700
91
(47)
40
3,400,000
700
0.5
1
69
3,600
27
(8)
11
1,400,000
380
I
4
62
3.100
19
(8)
7
570,000
160
2
5
61
2,700
13
(3)
5
513,000
190
10
10
59
1,800
7
3
242,000
140
10
15
56
1,600
5
2
138,000
100
s27
>.5 Mg/yr
57
500
4
1
85,000
110
110 9
alt is .saused th.t 95 percent control on all stre S lbs/hr reflects current level of control due to state regulations.
b epre,ents the ni er of vent atre controlled at a particular cutoff level divided by the totel nI er of model vent strem in the data base.
Cit Is assted that 60 percent of the facUlties are nonattai, ent areas.
I0, e.iseion factors used:
incinerators: 200 ppa in exhaust for stre containing nitrogen co.qoi,ids, and 21.5 q NO, on all other strew (bused on test data).
Flareg: 0.05 Ib/iliUtu (lased on EPA 60012-83-052).
C0 emissions based on 20 lbfllbcf (AP-42).
ie re.ents the addition& e saion reduction divided by the a itionel nc er of vent stre controlled at a particular cutoff level relative to the next least stringent cutoff level.
8 lspresents the additianst cost divided by the additional rester of vent utre controlled at a perticul.r cuto(f level relative to the next least stringent cutoff level.
49,000 3 144,600
1,800 35 63,800
1,500 74,500
130 430 56,000
300 300 90,300
300 170 51,600
80 660 53,700
1,000
gep. 003
-------
available VOC emissions and would require controls on an estimated 89 percent
of the vent streams for a typical population of facilities. At the
recommended cutoff level, there are no technical reasons why controls could
not be applied. In fact, many facilities with reactor process and
distillation operations are already controlling streams of this size. The
EPA recognizes that the Impacts estimation procedure includes certain average
assumptions for variables that affect emission reduction and cost. For
example, assumptions have been made regarding the piping distance to the
control device, excess capacity within existing control devices to
accommodate additional vent streams, use of a dedicated control device for
each vent stream, and availability of space within existing facilities to
accommodate new control devices. However, it is the EPA s judgment that even
if the characteristics of any individual facility were to deviate somewhat
from the assumed characteristics, the feasibility and costs of control would
remain reasonable.
6.5 RACT SUMMARY
The recommended presumptive norm for RACT is the reduction of VOC
emissions by 98 weight-percent or to 20 ppmv in any vent stream that has both
a VOC concentration above 0.05 weight percent and a flow rate above 0.1 scfm.
This cutoff should be applied on both an individual and combined vent stream
basis. In other words, if a process unit has more than one vent stream, then
the cutoff applies to each individual stream as well as to the combination of
all streams in the process unit. Therefore, controls would have to be
installed at a process unit with multiple vents if either an individual vent
stream or the combined vent streams meet the cutoff criteria.
Several additional considerations In applying RACT warrant mention.
First, any vent stream for which an existing combustion device is employed to
control VOC emissions should not be required to meet the 98 weight-percent
destruction or 20 ppmv emission limit until the combustion device is
replaced. In other words, no facility would be required to upgrade or
replace an existing combustion device. This approach would avoid penalizing
those facilities which have already undertaken efforts to control VOC
emissions through combustion, but whose control device is not designed to
achieve the 98 weight-percent/20 ppm level of control.
Second, it is important to note that the presumptive norm for RACT
provides incentives for pollution prevention by letting each facility
gep.003 6-7
-------
consider the trade-offs between process modifications and add-on controls.
Specifically, as an alternative to installing an add-on control device,
facilities can choose to improve product recovery equipment so that the VOC
concentration or flow rate falls below the cutoff level. In this manner, the
facility would be limiting VOC emissions via process changes and would
thereby avoid having to install an add-on combustion device.
Another consideration in applying RACT is the production of secondary
air pollutants such as CO and NOx as a result of combustion. Table 6-1 shows
expected national emissions of NOx and, in parentheses, the maximum annual
emissions of NOx at a single facility. In order to meet the recommended
RACT, some facilities may generate enough secondary emissions of NOx to
trigger New Source Reviews Whether the VOC emissions decrease is worth the
NOx increase for a given situation is highly dependent on the conditions in
the specific geographical area where that source is found. Depending on
local air quality and meteorology, some states may select a less stringent
level of control as RACT.
Finally, other regulatory initiatives under Title I (Nonattainment) and
Title III (Air Toxics) provisions of the Clean Air Act Amendments of 1990 may
result in the application of controls to vent streams with a flow rate and
VOC concentration below the RACT cutoff points. For example, maximum
available control technology (MACT) requirements for the Process Vents
portion of the Hazardous Organics NESHAP currently in the draft stage may
impact SOCMI vents more stringently than would the presumptive norm for RACT
as described above. Furthermore, all revised ozone SIPs (except for
marginal areas) must demonstrate a total net reduction in VOC emissions in
accordance with a specified percentage reduction schedule. This requirement
could also result in more stringent control of SOCMI reactor process and
distillation vents than would be required by the presumptive norm for R.ACT.
gep.003 6-B
-------
6.6 REFERENCES
1. Federal Register . Volume 44:53761.
2. Federal Register . Volume 51:43814.
3. Federal Register . Volume 53:45103.
4. Code of Federal Regulation. Volume 40. Part 60. Appendix A.
5. Memorandum. Barbour, W. J. and Pandullo, R. F., Radian Corporation, to
L. Evans, EPA:CPB. March 29, 1991. Reasonably Available Technology
(RACT) Impacts for the SOCMI CTG.
gep.003 6-9
-------
7. RACT IMPLEMENTATION
7.1 INTRODUCTION
This chapter presents information on factors air quality management
agencies should consider when developing an enforceable rule limiting
volatile organic compound (VOC) emissions from Synthetic Organic Chemical
Manufacturing Industry (SOCMI) reactor processes and distillation operations.
Information is provided on important definitions, rule applicability,
emission limit format, performance testing, monitoring, and
reporting/recordkeeping. Where several options exist for implementing a
certain aspect of the rule, each option is discussed along with its
advantages and disadvantages relative to the other options. In some cases,
there may be other equally valid options. The State or other implementing
agency can exercise its prerogative to consider other options provided the
options meet the objectives prescribed in this chapter.
For each aspect of the rule, one option is identified as the preferred
option. This guidance is for instructional purposes only and, as such, is
not binding. Appendix 0 contains an example rule that incorporates the
guidance provided in this document. The example rule provides an
organizational framework and sample regulatory language specifically tailored
for reactor processes and distillation operations. As with- the preferred
option, the example rule is not intended to be binding, either. The State or
other implementing agency should consider all information presented in this -
Control Technique Guideline (CTG) together with additional information about
specific sources to which the rule will apply. The reasonable available
control technology (R.ACT) rule should address all the factors listed in this
chapter to ensure that the rule is enforceable and has reasonable provisions
for demonstrating compliance.
7.2 DEFINITIONS
The RACT rule should accurately describe the types of sources that would
be affected and clearly define terms used to describe the SOCMI Industry or
applicable control methods. This section offers guidance to agencies -In
gep.003 7-1
-------
selecting terms that need clarification when used in a regulatory context.
This section presents example definitions of pertinent terms (or cites
sources where definitions may be found) the agency may refer to when drafting
RACT regulations for these source categories.
Two important terms that should be defined are reactor processes and
distillation operations. An example definition of the first term might be
unit operations in which one or more chemicals or reactants other than air
are combined or decomposed in such a way that their molecular structures are
altered and one or more new organic compounds are formed. An example
definition of the second term might read as: an operation separating one or
more feed streams into two or more exit streams, each exit stream having
component concentrations different from those in the feed streams. The
separation is achieved by the redistribution of the components between the
liquid- and vapor-phase as they approach equilibrium within the distillation
unit. A detailed discussion of these terms can be found in Sections 2.2 and
2.3 of this document.
Certain types of equipment associated with reactor processes may need
further clarification, such as the terms process unit or product.
Certain descriptors for reactor processes or distillation operations may be
helpful to define, such as batch reactor process, batch distillation
operation, vent stream, or halogenated vent stream. A discussion of
these terms is found in Chapter 2 of this document.
Other terms requiring definition are those used to describe emission
control techniques such as recovery device, incinerator, flare,
boiler, and process heater. A discussion of flares and incinerators is
presented in Section 3.1. A discussion of recovery devices is found In
Section 3.2. A description of boilers is given in Section 3.2.3.1 and a
description of process heaters is given in Section 3.2.3.2. It may also be
useful to define terms pertaining to equipment used in monitoring and
recording emissions, such as continuous recorder and flow indicator.
7.3 APPLICABILITY
Because most industrial plants are comprised of numerous pieces or
groups of equipment that may be viewed as sources of air pollutant
emissions, It is helpful to define the specific source or affected facility
that will be regulated. A possible definition for affected facility is an
gep.003 7-2
-------
individual reactor or distillation column with its own individual recovery
system (if any) or the combination of two or more reactors or distillation
columns and the common recovery system they share. Reactors or distillation
units operated in a batch mode are excluoed from this definition since this
CTG focuses on reactor processes and distillation operations that are
continuous.
Other facilities to consider exempting from RACT requirements include
reactor or distillation processes in plants with very low capacities. Most
research and development facilities or laboratory-scale facilities are not
designed to produce more than 1 gigagram (Gg) of chemicals per year. These
facilities generally operate on an intermittent basis making control
techniques that apply to industry-scale production facilities may not
inappropriate for these operations. For these same reasons, it may also be
appropriate to exempt facilities with vent stream flow rates below a
specified level. It would be appropriate, however, to require initial
measurements and reports of the low flow rate to verify that these facilities
are entitled to the exemption. It may also prove valuable to require owners
and operators of both low capacity and low flow rate facilities to report if
a process or equipment change occurs that increases the production capacity
or flow rate above the specified cutoff levels.
It should be noted that this RACT implementation guidance would apply
only to sources described in this document. Although recommendations have
been given for types of sources that may be exempt from the RACT
requirements, the final decision should be made by the governing air quality
agency. The agency may also wish to include any additional sources in its
rule that it deems appropriate.
7.4 FORMAT OF THE STANDARDS
Several formats are available for RACT regulations covering these source
categories. Because emissions can be measured from reactor process and
distillation operation vents and from applicable control devices, an emission
limitation (performance) standard, rather than an equipment standard, Is
recommended.
Possible emission limitation formats would include a mass emission rate
limit, a concentration limit, or a percent reduction level. A percent
reduction format best represents performance capabilities of control devices
gep.003 7-3
-------
used to comply with the RACT regulation. Alternate formats (such as mass
emission rate or concentration limit) are not preferred because they could
cause greater control than is required by RACT at some sources versus others
and less control than is required by RACT at others. For example, under a
mass emission rate or concentration format, the required control efficiency
is greater for streams with higher emission rates or higher vent stream
concentrations. Furthermore, the required control level for vent streams
with a low mass emission rate or concentration would not reflect the
capabilities of RACT.
A weight-percent reduction standard is feasible when applied to
Incinerators, boilers, and process heaters because emission rates can be
measured readily from the control device inlet and outlet. As discussed in
Chapter 3 of this document, new incinerators can achieve at least
98 weight-percent reduction in total organics (minus methane and ethane),
provided that the total organic (minus methane and ethane) concentration of
the process vent stream is greater than approximately 2,000 pmv. For vent
streams with organics concentrations below 2,000 ppmv, a 98 weight-percent
reduction may be difficult to achieve, but an incinerator outlet
concentration of 20 ppmv is achievable. Therefore, the recomended option is
an emission limitation format based on a combination weight-percent reduction
standard and a volume concentration standard. This recommended standard
would demonstrate a 98 weight-percent reduction in total organic compounds
(minus methane and ethane) or a reduction to 20 ppmv total organic compounds
(minus methane and ethane), whichever is less stringent.
Available data indicate that boilers and process heaters with design
heat input capacity greater than ISO million Btu/hr can achieve at least a
98 weight-percent reduction provided the waste stream is introduced into the
flame zone where temperatures are highest (2,800°F to 3,000°F). Therefore,
vent stream combustion in a boiler or a process heater of this size makes
performance testing unnecessary. However, to ensure sufficient destruction
of the VOC, the regulation must require that the vent stream be introduced
into the flame zone.
Flares differ from boilers, process heaters, and incinerators because
combustion occurs in the open atmosphere rather than in an enclosed chamber.
For this reason, it is difficult to measure the emissions from a flare to
determine flare efficiency. However, EPA test data indicate that if certain
gep.003 7-4
-------
design and operating condition are met, flares can be presumed to be in
compliance with the 98 percent/20 ppmv emission limit. These conditions are
found in 40 CFR 60.18.
7.5 PERFORMANCE TESTING
When the owner or operator of an affected facility conducts either an
initial or subsequent performance test, It is recommended that the facility
be running at full operating conditions and flow rates. Performance tests
needed to achieve the specified RACT requirements are an initial test for a
facility demonstrating either compliance with the 98 percent/20 ppmv emission
limit, or maintenance of vent stream flow rate and VOC concentration at
levels below the cutoff points.
The best available procedure recommended for determining emissions from
reactor process and distillation facilities is EPA Method 18. This method
has the advantage of being able to detect and measure individual organic
compounds. Details concerning the use of this method, Including sampling,
analysis, preparation of samples, calibration procedures, and reporting of
results are discussed in Reference Method 18. All of the reference methods
mentioned in this section are found in Appendix A of 40 CFR 60.
7.5.1 Incinerators
For the owner or operator of a facility using an incinerator to achieve
the suggested PACT emission limit, Reference Method 18 is recommended for
determining compliance during any performance test. Reference Method 1 or 1A
is recommended for selecting the sampling site. To determine the reduction
efficiency, it is recommended that the control device inlet sampling site be
located prior to the control device inlet and following the product recovery
device. Reference Methods 2, 2A, 2C, or 20 are recommended for determining
the volumetric flow rate, and Reference Method 3 is recommended for
determining the air dilution correction, based on 3 percent oxygen in the
emission sample.
7.5.2 Flares
The recomended compliance test for a flare includes measuring exit
velocity and stream heat content to verify compliance with the operating
specifications listed in 40 CFR 60.18.
gep.003 7-5
-------
7.5.3 Boiler or Process Heater
The performance test requirements for a small boiler or process heater
(less than 150 million Btu/hr) are identical to those for incinerators. For
a large boiler or process heater, the initial performance test could be
waived. It is EPAs judgment that a boiler or process heater of this size
would be able to meet the 98 percent/20 ppmv emission limit provided that the
vent stream is introduced into the flame zone of the boiler or process
heater.
7.5.4 Recovery Devices
A facility may choose to comply with R.ACT requirements by maintaining
its product recovery system in such a manner that the vent stream flow rate
and VOC concentration are below the cutoff points. Calculation of flow rate
and VOC concentration must be immediately downstream of all product recovery
equipment and prior to the introduction of any nonaffected stream. It is
recommended that the volumetric flow rate be determined according to
Reference Methods 2, 2A, 2c, or 2D, as appropriate. Molar composition of the
vent stream should be measured via Reference Method 18.
7.6 MONITORING REQUIREMENTS
7.6.1 Thermal Incinerators
To maintain and operate an incinerator properly so as to comply with the
suggested RACT emission limit, there are two possible monitoring methods:
continuous emission monitoring and continuous combustion control device
monitoring. Continuous combustion control device inlet and outlet monitoring
is preferred because it would give a continuous, direct measurement of actual
emissions. However, no continuous monitor measuring total organics has been
demonstrated for incinerators because each of the many diverse types of
compounds in process vent streams would have to be identified separately and
the concentrations of each determined. Continuous monitoring of all the
individual compounds would be too expensive to be practical.
The other possible monitoring method is continuous combustion control
device measurement. Certain parameters, such as temperature and flow rate,
when measured, can reflect the level of achievable control device efficiency.
It has been demonstrated that lower temperatures can cause significant
decreases in control device efficiency. Because temperature monitors with
strip charts are relatively inexpensive and easy to operate, it is
gep.003 7-6
-------
that the owner or operator of an affected facility should be
install, calibrate, maintain, and operate a temperature
measurement device according to manufacturers instructions.
Flow indicators are also relatively inexpensive and easy to operate.
Flow indicators determine control device efficiency by indicating whether or
not organic-laden streams are being routed for destruction. It is
recommended that the owner or operator of an affected facility should be
required to install, calibrate, maintain, and operate a flow indicator
according to the manufacturers specifications. It is recommended that the
flow indicator be installed at the combustion device inlet.
7.6.2 Flares
In order to meet the recommended RACT requirements for continued
compliance (see Section 7.4), flares must be operated in accordance with
40 CFR 60.18. Visual inspection is one method of determining whether a flame
is present; however, if the flare is operating smokelessly, visual inspection
would be difficult. An inexpensive heat sensing device, such as an
ultra-violet beam sensor or a thermocouple, is recommended for use at the
pilot light to indicate continuous presence of a flame. Measuring combustion
parameters (as recommended for incinerators), such as temperature and flow
rate, is not feasible for flares because these parameters are more variable
in an unenclosed combustion zone.
It is also recommended that flow rate and heat content of the flared
stream be determined by a flow indicator in the vent stream of the affected
facility. This should be performed at a point closest to the flare and
before the stream is joined with any other vent stream.
7.6.3 Boiler or Process Heater
To ensure that a boiler or process heater is operating properly as a
combustion control device, it is recommended that the owner or operator
maintain steam production (or equivalent) records. The owner or operator
should also install and operate a flow Indicator that provides a record of
vent stream flow to the boiler (or process heater). It is recommended that
temperature be monitored for boilers and process heaters of less than
150 million Btu/hr design heat input capacity.
7.6.4 Recovery Devices
If the facility has chosen to meet RACT by maintaining product recovery
devices, a procedure is needed to ensure that the measured flow rate and VOC
recommended
required to
gep. 003
7-7
-------
concentration have not changed since the time of the initial performance
test. To accomplish this the facility owner or operator should monitor
product recovery device parameters that correlate with proper operation of
the device. The type of parameters to be monitored depends on the final
device in the product recovery system.
For an absorber, two operating parameters are recommended as adequate
indicators of performance: absorbing liquid temperature and specific gravity
(or some other parameter used by a facility to measure absorbing liquid
saturation). For a condenser, the exit stream temperature is recommended as
the main indicator of performance. For a carbon adsorber, the carbon bed
temperature (after regeneration and completion of any cooling cycle) and the
quantity of steam used to regenerate the carbon bed are recommended as the
main indicators of performance.
As an alternative to monitoring the above parameters, EPA recommends
that a vent stream (post-recovery system) organic monitoring device with a
continuous recorder be allowed.
7.7 REPORTING/RECORDKEEPJNG REQUIREMENTS
Each facility subject to the RACT requirements should keep records of
certain key parameters that would indicate compliance. First, the facility
should identify the control method selected to meet the RACT requirements.
Next, the results of any performance testing results (discussed in
Section 7.5) should be recorded. Further, the facility should record all
parameters monitored on a routine basis to indicate continued compliance with
the RACT emission limit. These parameters (listed in Section 7.6) differ
depending on the means by which the RACT requirements are met. Any
exceedances of the monitored parameters listed in Section 7.6 should also be
recorded along with any corrective actions.
The air quality management agency should decide which of the recorded
data should be reported and what the reporting frequency should be.
gep.003 7-8
-------
APPENDIX A
LIST OF HIGH-VOLUME SOCMI CHEMICALS
-------
TABLE A-i. LIST OF HIGH-VOLUME SOCMI CHEMICALS
Chemical Common name(s)
Acetal dehyde
Acetic acid
Acetic acid, anhydride
Acetic acid, butyl ester
Acetic acid, ethenyl ester
Acetic acid, ethyl ester
Acetic acid, magnesium salt
Alcohols, C-li or lower, mixtures
Alcohols, C-12 or higher, mixtures
2 -Ami noethanol
Benzenami ne
Benzene
1 ,3-Benzenedicarboxyl ic acid
1 ,4-Benzenedicarboxyl Ic acid
1,2-Benzenedicarboxylic acid,
bis (2-ethylhexyl) ester
I, 2-Benzenedicarboxyl ic acid
butyl, phenylmethyl ester
1 ,2-Benzenedicarboxyl Ic acid
di-n-heptyl-n-nonyl undecyl ester
1,2-Benzenedicarboxylic acid
diisodecyl ester
1,2-Benzenedicarboxylic acid
diisononyl ester
(1) Acetic anhydride
(2) Acetic oxide
n-Butyl acetate
Vinyl acetate
Ethyl acetate
Magnesium acetate
Ethanol amine
(1) Aniline
(2) Phenylarnine
Benz o 1
Isophthalic acid
Terephthalic acid
(1) Bis (2-ethyihexyl) phthalate
(2) Dioctyl phthalate
(3) Di (2-ethyl hexyl) phthalate
Butyl benzyl phthal ate
Di-n-heptyl-n-nony1 undecyl phthalate
Di-isodecyl phthalate
Di - I sononyl phthal ate
(continued)
gep. 004
A-i
-------
TABLE A-I. (Continued)
Chemical Common name(s)
1,4-BenzenedicarboxyliC acid,
dimethyl ester
Benzenesulfonic acid
Benzenesulfonic acid,
mono-C 1 1 -alkyl derivatives,
sodium a1ts
Benzoic acid, tech.
1, 1-Biphenyl
2,2-Bis (hydroxymethyl )-
1 ,3-propanediol
I ,3-Butadiene
Butadiene and butene fractions
Butanal
Butane
Butanes, mixed
1,2 (and 1,3) Butanediol
1 ,4-Butanediol
Butanoic acid, anhydride
1 -Butanol
2- Butanol
2-Butanone
2 -Butenal
1 -Butene
(1) Terephthalic acid, dimethyl ester
(2) Dimethylterephthalate
(3) DMT
Diphenyl
Pentaerythri tol
(1) Bivinyl
(2) Divinyl
Butyral dehyde
n-Butane
Butylene glycol
Butyric anhydride
n-Butyl alcohol
sec-Butyl alcohol
Methyl ethyl ketone
(1) Crotonaldehyde
(2) B-Mehtylacrolein
a-ButyI ene
(conti nued)
gep. 004
A-2
-------
TABLE A-i. (Continued)
Chemical
Common name(s)
2-Butene
Butenes, mixed
2-Butenoic acid
2 -Butoxyethanol
2-Butyne-1 ,4-diol
Carbamic acid, monoamrnonium salt
Carbon disulfide
Carbonic dichioride
Chl orobenzene
2-Chloro-1 ,3-butadiene
Chl oroethane
Chioroethene
6-Chloro-N-ethyl -N -
(1-methyl ethyl )-1,3,5-
triazine-2,4-diamine
Chioromethane
(Chloromethyl) benzene
(Chioromethyl) oxirane
1-Chloro-4-ni trobenzene
2-Chi oro- 1 -propanol
3-Chi oro- 1 -propene
(1) 13-Butylene
(2) Pseudo-Butylene
Butylenes (mixed)
Crotonic acid
Butyl CellosolveR
Phosgene
Chi oroprene
Ethyl chloride
Vinyl chloride
(1) 2-Chloro-4-(ethylamino)-
6- (1 sopropylamino) -s-
tn azine
(2) AtrazineR
Methyl chloride
(1) Benzyl chloride
(2) a-Chlorotoluene
Epi chi orohydri n
(1) p-Chloronitrobenzene
(2) p-Nitrochlorobenzene
(1) 2-Chioropropyl alcohol
(2) Propylene chiorohydrin
(1) 3-Chioropropene
(2) Allyl chloride
(continued)
gep.004
A-3
-------
TABLE A-i. (Continued)
Chemical Common name(s)
Coconut oil acids, soldium salt
Cyclohexane
Cyclohexane, oxidized
Cyci ohexanol
Cyclohexanone
Cyclohexanone oxime
Cyclohexene
I ,3-Cyclopentadiene
Cyci opropane
1, 2-Di bromoethane
Dibutanized aromatic concentrate
1 ,4-Dichloro-2-butene
3, 4-Dichioro- 1 -butene
Di chl orodi fi uoromethane
Dichiorodimethyl silane
1, 2-Dichioroethane
1, 1-Dichloroethene
Di chi orofi uoromethane
Di chi oromethane
1 ,3-Dichloro-2-propanol
Di ethyl benzene
Hexahydrobenzene
(1) Hexalin
(2) Hexahydrophenol
Pimelic ketone
1,2,3,4-Tetrahydrobenzene
Trimethyl ene
(1) Ethylene dibromide
(2) Ethylene bromide
1 ,4-Dichlorobutene
Freon 12
Dimethyldichl orosi lane
(1) Ethylene chloride
(2) Ethylene dichioride
Vinylidene chloride
Freon 21
Methylene chloride
c -Dichlorohydrin
(continued)
gep. 004
A-4
-------
TABLE A-i. (Continued)
Chemical Common name(s)
1,3-Diisocyanato-2-(and 4-)
methylbenzene (80/20 mixture)
Dimethylbenzenes (mixed)
1,2 -Dimethyl benzene
1, 3-Dimethyl benzene
1, 4-Dimethyl benzene
1,1-Dimethylethyl hydroperoxide
2,6-Dimethyl phenol
1-Dodecene
Dodecyl benzene, linear
Dodecylbenzene, noni inear
Dodecylbenzenesul fonic acid
Dodecylbenzenesulfonic acid,
sodium salt
1,2-Ethanediol
2,2-(i,2-Ethanediylbis (oxy))
bisethanol
Ethanol
E t hene
Ethenone
Ethenyl benzene
2-Ethoxyethano l
Toluene-2,4-(and 2,6)-
diisocyanate (80/20 mixture)
Xylenes (mixed)
o-Xylene
m-Xyl ene
p-Xylene
tert-Butyl hydroperoxide
(1) m-Xylenol
(2) 2,6 Xylenol
(1) Dodecene
(2) Tetrapropyl ene
Alkylbenzene
Ethylene glycol
Triethylene glycol
Ethyl alcohol
(1) Ethylene
(2) Elayl
(3) Olefiant gas
Ketene
Styrene
(1) Ethylene glycol monoethyl ether
(2) Cellosolve
(continued)
gep.004
A-S
-------
TABLE A-I. (Continued)
Chemical Common name(s)
2-Ethoxyethyl acetate
Ethyl benzene
2-Ethyl hexanal
2-Ethyl -1-hexanol
(2-Ethyihexyl) amine
Ethyl methyl benzene
6-Ethyl -1,2,3,4-tetrahydro
9, lO-anthracened lone
E thy n e
Fatty acids, tall oil, sodium salt
Formaldehyde
2,5-Furandione
D-Glucitol
Heptane
Heptenes (mixed)
Hexadecyl chloride
Hexahydro-2H-azepi n-2 -one
Hexane
1, 6-Hexanedi amine
1,6-Hexanediamine adipate
(1) Ethylene glycol monoethyl ether
acetate
(2) Cellosolve acetateR
2-Ethyihexyl alcohol
(1) Acetylene
(2) Ethine
(1) Formalin (solution)
(2) Methanal (gas)
Maleic anhydride
Sorbi tol
n-Heptane
Caprol actam
Hexamethylene diamine
(1) Hexamethylene diamine adipate
(2) Nylon salt
(continued)
gep. 004
A-6
-------
TABLE A-i. (Continued)
Chemical Common name(s)
Hexanedini tn 1 e
Hexanedioic acid
2-Hexenedinitrile
3-Hexenedinitri le
Hydrocyanic acid
3-Hydroxybutyral dehyde
4-Hydroxy-4-niethyl -2-pentanone
2 -Hydroxy- 2-methyl propaneni tn 1 e
2-Hydroxy-l,2,3-
propanetricarboxyl ic acid
2,2 -Iniinobisethanol
Jodo-methane
1,3-Isobenzofurandione
Isodecanol
Linear alcohols, ethoxylated, mixed
Linear alcohols, ethoxylated and
sulfated, sodium salt, mixed
Linear alcohols, sulfated, sodium
salt, mixed
Methanami ne
Methanol
(1) Adiponitrile
(2) 1,4-Dicyanobutane
Adipic acid
1, 4-Di cyano- I -butene
(1 ) 1,4-Dicyanobutene
(2) Di hydromucononi tn 1 e
(3) 1,4-Dicyano-2-butene
Hydrogen cyanide
(1) Aldol
(2) Acetaldol
Diacetone alcohol
(1) Acetone cyanohydrin
(2) 2-Methyllactonitrile
Citric acid
(1) Diethanolamjne
(2) 2,2-Aminodiethanol
Methyl Iodide
Phthal Ic anhydride
Isodecyl alcohol
Methyl amine
(1) Methyl alcohol
(2) Wood alcohol
(continued)
gep.004
A- 7
-------
TABLE A-I. (Continued)
Chemical Common name(s)
2-Methoxyethanol
Methyl benzene
4-Methyl-I ,3-benzenediamine
ar-Methyl benzenedi anli ne
2-Methyl -1,3-butadiene
2-Methyl butane
2-Methyl -2-butene
2-Methyl butenes, mixed
Methyl tert-butyl ether
1-Methyl -2,4-dinitrobenzerie
(and 2-Methyl-1,3-dinitrobenzene)
1-Methyl -2,4-dinitrobenzene
(1-Methyl ethyl) benzene
4,4- (1-Methyl ethyl idene)
bi sphenol
6-Methyl -heptanol
N-Methyl methanami ne
Methyl oxi rane
2-Methyl pentane
4-Methyl -2-pentanone
4-Methyl -3-penten-2-one
(1) Ethylene glycol monomethyl ether
(2) Methyl CeiiosoiveR
Tol uene
(1) Toluene-2,4-dianiine
(2) 2,4-Diaminotoluene
(3) 2,4-Tolylenediarnine
Isoprene
Isopentane
Amylene
Amylenes, mixed
MTRE
2,4 (and 2,6)-Dinitrotoluene
2,4-Dinitrotoluene
Cumene
(1) 4,4-Isopropylidenediphenol
(2) Bisphenol A
(1) Isooctyl alcohol
(2) Isooctanol
(1) Dimethylamine
Propylene oxide
(1) Isopropyl acetone
(2) Methyl Isobutyl ketone
(conti nued)
gep. 004
A-8
-------
TABLE A-i. (Continued)
Chemical
Common name(s)
1-Methyl-1-phenylethyl hydroperoxide
2-Methyl propanal
2-Methyl propane
2-Methyl -1 -propanol
2-Methyl -2-propanol
2-Methyl -1 -propene
2-Methyl -2-propenenitrile
2-Methyl-2-propenoic acid,
methyl ester
1-Methyl -2-pyrrol idinone
Naphthalene
2,2 ,2 t -Nitrilotrisethanol
Ni trobenzene
1 -Nonanol
I -Nonene
Nonyl phenol
Nonyiphenol, ethoxylated
Octe n e
Oil-soluble petroleum sulfonate,
calcium salt
Cumene hydroperoxide
(1) Isobutyraldehyde
(2) Isobutylaldehyde
Isobutane
Isobutyl alcohol
(1) tert-Butyl alcohol
(2) t-Butanol
(1) Isobutylene
(2) 2-Methyl propene
Methacrylonitri 1 e
(1) Methacrylic acid methyl ester
(2) Methyl methacrylate
1-Methyl -2-pyrrol idone
(1) Naphthene
(2) Naphthalin
(1) Triethanolamine
(2) Triethylolamine
Ni trobenzol
(1) n-Nonanol
(2) Nonyl alcohol
Tn propylene
(continued)
gep.004
A-9
-------
TABLE A-i. (Continued)
Chemical
Common name(s)
Oil-soluble petroleum sulfonate,
sodium salt
Oxi rane
2,2-Oxybisethanol
Pent ane
3- Peneteneni tn 1 e
Pentenes, mixed
Phenol
1-Phenylethyl hydroperoxide
Propanal
Propane
1, 2-Propanediol
Propanen I tril e
1,2,3-Propanetriol
Propanoic acid
1- Propanol
2- Propanol
2-Propanone
1 - Pro pene
2-Propenenitrile
2-Propenoic acid
Ethylene oxide
Diethylene glycol
n- Pentane
(1) Carbolic acid
(2) Hydroxybenzene
Prop I onal dehyde
Dimethyl methane
Propylene glycol
(1) Propionitrile
(2) Ethyl cyanide
(1) Glycerol
(2) Glyceryl
(3) Glycerin
Propionic acid
Propyl alcohol
Isopropyl alcohol
(1) Acetone
(2) Dimethyl ketone
Propylene
Acrylonitri 1 e
Acrylic acid
(continued)
gep. 004
A-b
-------
TABLE A-I. (Continued)
Chemical Common name(s)
2-Propenoic acid, butyl ester
2-Propenoic acid, ethyl ester
Propyl benzene
Sodium cyanide
Tallow acids, potassium salt
Tallow acids, sodium salt
1 ,3,5,7-Tetraazatricyclo
(3,3,1,13,7)-decane
Tetrabromomethane
1 , 1,2,2 -Tetrachi oroethane
Tetrachl oroethene
Tetrachl oromethane
Tetraethyl p1 umbane
Tetrahydrofuran
Tetra (methyl-ethyl) plumbane
Tetramethyiplumbane
1,3,5-Triazine-2,4,6-triamine
In bromomethane
1,1,1 -Tribromo-2-methyl -2-propanol
1,1, 1-Trichioroethane
1,1, 2-Trichioroethane
Butyl acrylate
Ethyl acrylate
Phenyl propane
Cy a nog ran
(1) Hexamine
(2) Hexamethylene tetraamine
Carbontetrabromi de
(1) Tetrachloroethylene
(2) Perchioroethylene
Carbon tetrachloride
Tetraethyl lead
TH F
Tetra (methyl-ethyl) lead
Tetramethyl lead
(1) Melamine
(2) 2,4,6-Triamino-s-triazjne
Bromoform
(1) Tribronio-t-butyl alcohol
(2) Acetone-bromoform
(3) Brometone
Methyl chloroform
Vinyl trichioride
(continued)
gep. 004
A- i l.
-------
TABLE A-i. (Continued)
Chemical
Common name(s)
Trichi oroethene
In cM orofi uoromethane
Tn chi oromethane
2,4,6-Trichloro-1,3,5-triazine
l,1,2-Tnichloro-1,2,2-
tn fi uoroethane
2, 6,6-Triniethyl bi cyci o
(3,1,1) hept-2-ene
Ure a
Urea anirnonium nitrate
Trichi oroethyl ene
(1) Freon 11
(2) Fluorotrichioroniethane
Chi orofonin
(1) Cyanuric chloride
(2) 2,4,6-Tnichloro-s-tniazjne
(I) Trichlorotrifluoroethane
(2) Fluorocarbon 113
a-Pinene
(1) Carbamide
(2) Carbonyldiamide
gep. 004
A- 12
-------
APPENDIX B
EMISSION DATA PROFILES
-------
TA11IJ B -I. REACTOR PROCESS VI NTS EMISSION I)ATA PROHL1
PRODUCE
PROCESS
FLOW RATE
HEAT CONTENT
VOC FLOWRATE
PROCESS
I IESCR IrrION
(SCFM)
( lflhJ/SCF)
LI3IHR)
Dutyl Acetate Estenf,cat,on 2 102 0.1
IThoctyl phthalate Esterification 5 102 (LI
Vinyl Acetate Oxyacetylation 7 407 0.1
Ethyl Acetate Esterilication 7 102 0.5
Ethylene Glycol Monoethyl ether acetate Estenu ication 8 102
Ethylbcnzenc Alkylation 8.7 4
Butynediol Ethyny lation 9.2 747 19.8
Vinylidene Chloride Dehydrochlorination 10 600 41
Nitrobenzene Nitration 13 434 19
Ethyibenzene Alkylation 17 181 16
Ethyl Chloride U y droctslonnation 20 1286 168
Methyl Chloride Hydmchlorination 20 500 2.1
Ethylene Dichlonde Chlorination 40 40 3.6
Chlorobenzene Chlorination 55 0 4
Ilexamethyl diamine Hydrogenation 70 323 6.6
Ethyl Aetytate Esterilication is 102 6.1
Propylene Oxide Hydrolysis 99 0 0.1
Hexamethyl diamine Hydrogenation 113 900 0
Acetic Anhydride Condensation 147 1069 305
Ethylene Dichloride Chlorination 167 163 74
Ethylene Dichloride Chlorination 267 1228 113
Ethylene Dichioride Oxychlorination 304 713 748
Styrene Dehydrogenation 574 300 161
Butyraldehyde Hydroformybtion 729 1233 2394
Dinitrotoluenc Nitration 822 0 0.1
Adipic Acid Oxidation 848 0 0
Adipoititn le Hydmdimenzation 1080 70 27
Bcnzenc Catalytic Reforming 1289 205 8.3
Hcxamcthylene Diaminc Hydrogenation 1304 462 0
Dodecylbcnzcne sulfonic acid Sulfonation 1863 0 0.1
Adipic Acid Oxidation 2800 0 0
Adipic Acid Oxidation 4653 0 0
Styrenc Dehydrogrnation 5208 280 711
n-Butyl Alcohol Ilydrogenat ion 5429 776 4046
1,4-flichionde Chlonnarion 9195 0 7.2
Ethylene Oxide Oxidation 12187 4 130
Methanol Cartony lation 18950 295 75
a 1 data taken front Appendix C of Reactor Processes in Synthetic Organic Chemical Manufacturing Industry - Background Information for Proposed Standards
(EPA 450/3-85-005a).
bflata not reported.
-------
TABLE B-2. DISTILLATION EMISSION DATA PROFIL
NUMBER OF
PRODUC F
COLUMNS AND
PLO WRATh.
HEAT CONTENT
VOC FLOW RATE
PROCESS
OP RA11NG
CONDITIONS
(SCFM)
(BTIJ/SCF)
(LB/HR)
Chlorobenzene 1 NV 0.005 133 0.004
Aniline 1 V 0.007 3752 0.11
Chlorobenzene 1 NV 0.012 374 0.025
Chlorobcnzenc 1 NV 0.015 755 0.034
Aniline 1 V 0.02 3047 0.29
Chlorobenzenc I NV 0.02 432 0.031
Terephihalic Acid 1 NV 0.02 169 0.02
Confidential 1 CO 0.02 0 0
Ethylbcnzcne I NV 0.063 7 0
Methyl Methacrylatc 1 NV 0.1 1Q56 0.4
84 2NV 0.1 834 0.25
Acetone 1 V 0.1 360 0.2
Acetone 2 NV 0.1 36 0,2
Acetic ACId 1 NV 0.18 207 0.08
Chloroprene 1 NV 0.2 2778 2
Malic Arthydride 3 V 0.2 0 0
Confidential 1 CO 0.26 1375 1.83
Dimethyl Terephthalate 1 V 0.3 4918 4.9
Ch loroprene 1 V 0.4 2224 4.9
Acetic Anhydnde 1 CO 0.48 1024 133
Phthalic Anhvdnde 1 V 03 3602 113
Ethylacetate I NV 0.7 680 0.4
Ethyldichloride 1 V 0.9 1024 14
Alkyl Beazenc I NV 1.2 3643 15
Acetic Anhydndc 1 CO 1.2 1024 3.81
Pcrchlorocthylcne 1 NV 1.3 143 3.4
Acetone I NV 1.39 966 6.04
Acetone 1 V 1.39 966 6.04
Acetic Acid η r 1.45 903 1.6
Acetone 1 NV 13 1225 10.4
Nitrobenzene 1 V 13 352 1.8
Methyl Methacrylate 1 NV 1.7 14.83 13.6
Chloroprene 2 V 1.8 858 4,9
Dichloroben.zene 1 V 1.8 651 8.1
Acetic Acid I CO 1.94 68 0.8
Diphenylamine 1 V 2 0 0.003
Methyl Ethyl Ketone 1 NV 2.2 1183 . 10
Ethylene Oxide I NV 2.3 1191 13.8
Ethylacetate 1 NV 2.3 1012 6.4
Vinyl Acetate 1 NV 2.3 781 5.2
Ethyldichloride 1 NV 2.4 1024
Phthalic Anhydndc 1 V 2.4 260 4
Terephthalic Acid 1 NV 2.5 114 1.9
Methyl Methacrylate 1 V 2.6 2870 41
Dichlorobenzcnc 1 V 2.6 62 1.3
86 1NV 3.3 90 28.8
Acetic Anhydride I CO 3.66 1024 11.61
Dimethyl Terephihalate 1 NV 4.2 180
Ethanolaminea 1 V 2.3 0 0
Acetone Cyanohydride I NV 4.4 190 4
Ethyldich loride 1 V 4.8 53 3.9
Methyl Ethyl Ketone 1 NV 4.9 2003 32.68
Acetic Anhydnde 1 CO 4.98 1024 15.81
Ethyldich londe 2 NV 6 727 63.9
Malic Anhydnde I V 63 0 0
Ethylbenzene 1 NV 63 1286 3
Ethyldichlonde 1 NV 6.94 fl7 55
Dime thy! Terephthalate 1 NV 7 0 10
Methyl Methacrylate 1 NV 7.4 439 12
AcaylicAcid 1V 7.4 0 0
Ethyldichioride I NV 8.1 91 6.6
Acetic Anhydndc 4 CO 8.16 1024 25.88
-------
TABLE 8-2. DISTILLATION EMISSION DATA PROF1L (Continued)
NUMBER OF
PRODUCr
COLUMNS AND
FLOWRATE
HE T j j r
VOC FLOWRATE
PROCESS
OPERATING
coNDmoNs
(SCFM)
(BTU/SCF)
(LB/FIR)
Dimethyl Terephthalate 1 NV 8.4 236 13
Dimethyl Tcrephthalatc 2 V 8.9 47 2.2
Vinyl Acetate 1 NV 9 34.8
Phthalic Anhydnde 1 V 9.5 690 42.7
hlorobenzene 1 V 9.9 177 6
Dichlorobenzene 1 V 9.9 177 2
Chloroprene 1 V 10 3 0.2
Acrylonitrile 1 NV 10.2 379 15.8
Vinyl Acetate 1 NV 103 74 15.2
Ch lomprcne 2 V 11.0 1.1
Acetone I V 12.13 0 0
Ethyldich loride 1 NV 123 727 988
Formaldehyde 2 V 12.5 9 0.8
Ethyldichlonde 1 V 13 183 32.3
Phthalic Anhydride 1 V 13.2 979 84.1
Actylic Acid 2 V 13.2 8 0.6
Perchloroethylene 1 NV 13.6 6 2.1
Dimethyl Tcrcphthalate 1 NV 15 236 12
Vinyl Acetate 1 NV 15 149 6.6
Dimethyl Terephthalate 2 V 15 47 5
85 4 NV 16.7 14.64 0.1
Dimethyl Tercphthalatc I NV 17.4 1282 120.5
Phthalic Anhydride 1 V 17.9 69 8
Acetone 1 NV 18 0 0
Methyl Methacrylate 1 V 18.3 2870 289
Ethanolaiminca 3 V 19.5 0 0
Ethylbenzene 1 V 19.7 0 0
Acrylic Acid 2 V 20 0 0
Acetone 1 NV 21,13 2592 170.2
Butadiene 1 NV 22.5 1453 100.5
Acrylic Acid 1 V 22.6 92 103
Acrylonitnle 1 V 22.7 439 44
Cyclohexanone/cvclohexanol 3 V 22.701 18 15
Cbloroprene 1 NV 23.6 0 0
Acrylonitrile 1 V 25.6 346 37.9
Chlorobenzcne 1 V 26.1 346 43.1
Phthalic Anhydride 2 V 27 505 100
Ethyl Acrylate 2 V 27.2 69 5.6
Acrylic Acid 2 V 27.6 400 55.8
Acetone Cyanohydride 1 NV 313 1916 289
Acrylic Esters 3 V 33.9 168 1.5.7
Chlorobenzcne 1 NV 34.9 495 59
85 7 V 36.701 123 15.498
Acetone Cyanohydnde 1 V 39.2 4 0.18
Confidential 3 CO 4039 0 o.o9
Confidential 4 CO 49.6 0 036
Acetic Acid 3 NV 50 4 1.1
Acetone I NV 50.4 70 16.9
Dimethyl Terephthalate 2 V 54.6 47 17
Methanol I NV 63,4 449 3993
Cyclohexanone/cyclohexanol I V 687 72 26.3
Methyl Methacrylate 1 V 72.9 66 263
Adiponitrile 9 V 75 0 o
Ethylene Glycol 6 V 73.1 0 0
Confidential I Co 77.32 6 1.36
Dimethyl Terephthalate 1 NV 793 1453 601
86 1NV 80 9 19.6
Hexamcihyiene Diamine 7 V 81.1 0
Alk)l Benzene 1 V 85.9 104 30.6
Methyl Methacrylate 1 V 96.2 295 148.8
-------
TABLE B-2. DISTILLATION EMISSION DATA PROFILE (Continued)
NUMBER OF
PRODUCT
COLUMNS AND
FLOWRATE
HEAT CONTENT
VOC FLOWRATE
PROCESS
OPERATING
(SCFM)
(BTUJSCF)
(LB/1- IR)
CONDITIONS
Ethyidichlonde 1 NV 100 6 8.3
Acetone Cyanohydnde 2 V 101.2 4 1.8
Dimethyl Terephthalate 1 NV 123.8 768 628.2
Methyl Methacrylate 2 NV 126.4 155 116.2
ChioropreneMethyl 3 V 145 12 7.2
Methacrylate 1 V 152 13 9.8
Dimethyl Trephthatate 2 V 176 47 57
Methyl Methacrylate I NV 1783 1316 1300
Ethyl Aciylate 2 V 219 45 454
Dimethyl Tcrephthalate 1 NV 281 768 1426
Acetic Acid I NV 358 333 375
Acrylic Acid I NV 364 150 289
Ethvldichloridc 1 NV 5353 804 so
Methanol 1 NV 5613 1258 3668
Acetic Acid I NV 575 gcj
Isophihalic Acid 1 NV 637 19 123
Acetaldehyde 2 NV 647.3 293 183
6NV 656 6 19
8 Emissions data taken from Appendix C of Distillation Operations in Synthetic Organic Manufacturing - Background Information
for Proposed Standards (EPA-450/3-.83-OOSa).
-------
TABLE 11-3. REACIi)R PROCESS ANI) DIS11ILA11ON MOI)EI. VENT STREAMS
PARAMgFER
TYPE
LOW FLOWRATE
LOW HEATING
VALUE
LOW FLOWRATE
IHCJH HEAliNG
VALUE
111011 FLOWRATE
LOW HEATING
VALUE
HIGH FLOWRATE
HIGH HEATING
VALUE
AVERAGE
Flow Rate (scfm)
heating Value (Btu/scf)
VOC Emission (lb/hr)
Flow rate (scfm)
heating Value (Rtu/scf)
VOC Emission Rate (Ib/hr)
Distillation
Distillation
Distillation
Reactor Process
Reactor Process
Reactor Process
2.6
62
1.3
40
40
4
2.6
2870
41
20
1286
168
637
19
123
1080
70
27
536
804
3050
5429
776
4046
63
449
399
574
300
161
-------
APPENDIX C
COST CALCULATIONS
-------
1. Hand Calculations for the VENTCOST Program - Incineration Procedure
Used to assess control equipment costs for the SOCMI CTG for
Reactor Process and Distillation Vents.
Calculations based on OAQPS Control Cost Manual, Chapter 3.
The stream costed in this example is model stream R-LFHH. Its
characteristics are as follows:
VOC to be controlled: Ethyl Chloride*
MW : 64.5 lb/lb mole
Flow rate (total) : 20 scfm
VOC flow rate : 168 lb/hr
Heat value : 1,286 Btu/scf
Oxygen content : 0%
Inert content : Assume all N 2
*Most of the following calculations are based on the actual
compound in the SOCMI Profile. However, the combustion and
dilution air calculations are based on the design molecule
C 285 H 57 0 063 , which represents the average ratio of carbon,
hydrogen, and oxygen. The molecular weight of this design
molecule is 50 lb/lb.mole.
I. SIZING CALCULATIONS FOR INCINERATOR
A. Check to see if the stream to be controlled is halogenated--yes,
ethyl chloride contains chlorine. Since the stream is halogenated,
the following applies.
1. No heat recovery is allowed for halogenated streams.
2. A scrubber will be required to remove acidic vapors from the
flue gas following combustion. Scrubber sizing and costing
calculations for this vent stream immediately follow the
incinerator calculations.
B. Calculate total moles of the vent stream, and quantify moles of
VOC, 02 and inerts.
1. VOC moles:
VOC moles (168 lb/hr)(hr/60 min)(lb.mole/64.,5 ib)
0.0434 lb.moles/min
gep.004
c-i
-------
2. Total vent stream moles:
Vent moles = (20 scfm)(lb.mole/392 scf)
0.051 lb.moles/min
3. Oxygen moles:
02 moles 0
4. Inert moles:
Inert moles Vent moles - VOC moles - 02 moles
(0.051 - 0.0434 - 0) lb.mole/min
0.0076 lb.mole/min
C. Calculation of Molar Ratio of Air to VOC
Please note that the combustion and dilution air calculations are
based on the design molecule C 285 H 57 0 063 , which represents the
average ratio of carbon, hydrogen, and oxygen. The molecular
weight of this design molecule is 50 lb/lb.mole.
Assume 3.96 moles of 02 are required for each VOC mole.
1. Since no oxygen is present in the stream, additional
combustion air must be added, to insure proper combustion.
2. Calculate the ratio of 02 to VOC required for combustion.
02 theory 3.96 - 02 ratio already in streani*
*Additional air is not required if sufficient oxygen is already
present in the vent stream.
3. Since air is 21% 02 the necessary ratio of ir to VOC is:
Air ratio (3.96)/0.21 18.86 moles air/mole VOC
D. Calculation of molar ratios of inert moles to moles VOC
1. Inert ratio inert moles/VOC moles
* 0.0076/0.0434
0.175 moles inert/mole VOC
E. In order to ensure sufficient 2 is present in the combustion
chamber, enough air must be added to provide 3% 02 in the exhaust
(flue) gas stream after combustion. The 02 material balance is
(Initial 02%)(vent stream) + (0.21)(dllution air) (0.03)(exhaust)
gep.004 C-2
-------
Initial 02% = 0; therefore,
(0.21)(Dilution air) (0.03)(exhaust stream)
(0.21)(Dilution air) (0.03) (dilution air + vent stream)*
*Assume no increase in moles after combustion
(0.21)(Dilution air) (0.03)(dilution air) + (0.03)(vent stream)
Dilution air (0.03) 1(0.21 - 0.03) (Vent stream flow)
*Thjs factor will be used later.
F. Exhaust gas consists of noncombustibles (N 2 ) + CO 2 + H 2 0 (see
Combustion Stoichiometry Memo)
1. Exhaust ratio (0.79)(air ratio) + 2.85 + 2.85
20.6 moles exhaust/mole VOC
2. Dilution ratio = 0.03/(0.21 - 0.03)
(Inert ratio + Exhaust ratio)
G. Calculate flows of stream components based on calculated ratios
1. Dilution ratio (0.1667)(0.175 + 20.6)
= 3.46
2. Dilution air flow = (Dilution air ratio)(VOC moles)
(392 scf/lb.mole)
Dilution air flow = (3.46)(0.0434)(392)
= 58.92 scfm
3. Combustion air flow = (Air ratio)(VOC moles)(392)
( 18 . 86) (0. 0434) (392)
320.86 scfm
Combined air flow Combustion air + Dilution air
(320.86 + 58.92)
= 380 scfm
4. Inert gas flow (Inert ratio)(VOC moles)(392)
(0.175)(0.0434)(392)
3 scfm
5. Total flow = Combined air flow + Initial vent stream flow
+ Inert gas flow
380 + 20 scfm
New flow 400 scfm
gep.004 C-3
-------
H. Recalculate heat value of the stream after adding air streams
(prior to combustion)
1. Heatval (Initial flow * Initial heatval)/New flow
(20 * 1,286)/400
64.30 Btu/scf
I. Check the heat value of the precombustion vent stream, to see if it
is acceptable from a safety perspective
1. Streams containing halogens must have a heat value
< 95 Btu/scf, nonhalogens < 98 Btu/scf.
64.3 < 95
*Streams would be diluted as necessary to insure that heat
contents are below maximums.
J. Minimum incinerator flow is 50 scfm, Streams less than 50 scfm
will be increased by addition of air.
400 scfm > 50 scfm
K. Establish temperature that incinerator operates:
Halogenated: 2,000°F
Nonhalogenated: 1,600°F
L. Nonhalogenated streams are potential candidates for heat recovery.
If addition of air flows results in lowering the heat value of the
entire vent stream below 13 Btu/scf ( 25% LEL) then the entire vent
stream is eligible for heat (energy) recovery in a heat exchanger.
High heat value streams cannot be heated in a preheater because of
combustion/explosion concerns, but the VENTCOST program will
calculate economic options that allow preheating of the air stream
only.
The Energy recovery equations are weighted to account for the mass
of the heated streams since the flows being preheated may be
smaller than the exhaust (flue) gas flows.
No calculations are presented here since the example stream is
halogenated, and therefore, heat recovery is not allowed.
gep.004 C-4
-------
i. Calculate the auxiliary fuel (Qaf) requirement
Qaf [ 0.0739 * new flow * [ 0.255 * (1,1 * incinerator temperature
- temperature gas - 0.1 * 77) - (heatval/0.0739))] χ
[ 0.0408 * [ 21,502 - (1.1 * .255 * (incinerator temperature
- 77))]
- Incinerator Temperature 2,000°F
*See OAQPS Control Cost Manual, Incinerator Chapter for Derivation
and Assumptions.
[ .0739 * 400 * (.255 * (1.1 * 2,000 -
Qaf 77 - 0.1 * 7fl - (64!.073gu11
[ 0.0408 * [ 21,502 - (1.1 * 2.55 * (2,000 - 77)]]
Qaf f.0739 * 400 *J _ 327) ]
855.27
Qaf -11.3 scfm
Negative value indicates no auxiliary fuel is theoretically needed.
Therefore, set Qaf = 0.
N. Calculate sufficient auxiliary fuel to stabilize flame (5% of TEl).
1. Thermal Energy Input (TEl) 0.0739 * (new flow + Qaf) *
(0.255 * (incinerator
temperature - 77)
TEl = 0.0739 * (400 + 0) * 0.255 * (2,000 - 77)
= 14,495.2
2. Qaf = (0.05 * 14,495.2)/(0.0408 * 21,502)
= 0.826 scfm 0.8 scfm
0. Calculate the total volumetric flow rate of gas through the
incinerator, Qf . Include auxiliary air for the natural gas.
1. Qt new flow + Qaf + combustion air for fuel
2. Assuming the fuel is methane, CH 4 , the combustion reaction is:
CH 4 + 202 CO 2 - CO 2 + 2H 2 0
So two moles of 02 are required for each mole of fuel. Since
air is 21% 02.
2/0.21 9.5 moles air/mole of fuel
Combustion air for fuel = (Qaf * 95)
gep.004 C-5
-------
3. Qfj = New flow + Qaf + (Qaf * 95)
= 400 + 0.8 + (0.8 * 95)
408 scfm
II. COST ANALYSIS - ESTIMATING INCINERATOR TOTAL CAPITAL INVESTMENT
A. The equipment cost algorithms are only good for the range of
500 scfm to 50,000 scfm. The minimum design size is 500 scfm, so
capital costs are based on 500 scfm and annual operating costs are
based on cal cul ated Qf 1
1. Design Q 500 scfm
B. For 0% heat recovery, equipment cost, EC, is:
EC = 10,294 * (Design Q. 2355 ) * (# incinerators) *
(CE INDEX/340.1)
EC 10,294 * (500.2355) * * (355.6/340.1)
EC $46,510.
C. Add duct cost. Based on an article in Chemical Engineering (5/90)
and assuming 1/8 carbon steel and 24 diameter with two elbows per
100
Ductcost [ (210 * 24A0.839) + (2 * 4.52 * 24%1.43) *
(length/100) * (CE INDEX/352.4)]
Ductcost $11,722.52 (for length of 300 feet)
D. Add auxiliary collection fan cost, based on 1988 Richardson Manual.
Fancost (79.1239 * Design Q O. 5612 ) * 355.6/342.5
2,687
E. Total Equipment Cost, ECT 0 I, Is given by:
ECTOT = EC + Ductcost + Fancost
46,510 + 11,723 + 2,687
$60,920
F. Purchased Equipment Cost, PCE, is:
PCE 1.18 *
$71,885.6
gep.004 C-6
-------
G. Estimate Total Capital Investment, TCI
if Design Q > 20,000, installation factor 1.61
if Design Q < 20,000, installation factor 3.25
IC! = 1.25 * PCE
= 1.25 * $71,885.6
$89,857.
III. CALCULATING ANNUAL COSTS FOR INCINERATORS
A. Operating labor including supervision (15%)
1. Assume operating labor rate $15.64/hr (1/2 hour per shift)
Op labor (Q.5 * Op hours)/8 * ($15.64/hr)(1.15)
(Op hours = 8,760)
Op labor $9,847.34/yr
B. Maintenance labor and materials
M labor (0.5/8 * 8,760) * ($17.21/hr)
= $9,422.48
Materials M labor = $9,422.48
C. Utilities = Natural Gas & Electrical Costs
Assume value of natural gas $3.30/1,000 scf
1. Natural gas (3.30/1,000) * Qaf * 60 mm/hr * Op hours
Natural gas = (3.30/1,000) * 0.826 scfm * 60 * 8,760
= $1,432/yr
2. Power (1.17 * * Q i * 4)/0.60
Power = (1.17 * 3Q4 * 408.7 * 4)/0.60
0.3188 kW
3. ElecCost (0.059 S/kWh) * (0.3188) * (8,760)
$164.77
D. Total Direct costs, TOC
1. TOC Op_Labor + M_Labor + Material + NatGas + ElecCost
= (9,847 + 9,422 + 9,422 + 1,432 + 165)
$30,288/yr
E. Overhead 0.60 * (Op-Labor + M-Labor + Material)
gep.004 C-7
-------
$17,214.6/yr
F. Administrative 2% of TCI, Tax = 1% of TCI
Admin (O.02)(89,857)
$1,797/yr
G. Tax $898.6/yr
H. Insurance 1% of TCI
Ins = 0.01 * TCI
$898.6/yr
I. Annualized Capital Recovery Costs, Anncap, is:
AnnCap = 0.16275 * $89,857
$14,624.23/yr
J. Total Indirect Capital Cost, IC, is:
IC overhead + administrative + tax + insurance + Anncap
= (17,215 + 1,797 + 899 + 899 + 14,624) $/yr
= 35,434 $/yr
K. Total Annual Cost, TAC, is:
TAC = IC + DC
= 35,434 + 30,288
= 65,722 $/yr
2. Hand Calculations for the Ventcost Proaram Scrubber Procedure
Stream to be costed is R-LFHH as it exists after combustion in
incinerator
I. SIZING CALCULATIONS FOR SCRUBBER
Calculate stream parameters after combustion. Assume 98 percent
VOC destruction
- Ethyl chloride is the VOC in stream R-LFHH. There is one mole
of Cl for every mole of VOC. Therefore, for every mole of VOC
destroyed, one mole of HC1 is created.
gep.004 C-8
-------
VOC destroyed = (initial VOC flow-ib/hr)(0.98) + VOC MW
= (168 lb/hr)(0.98)/(64.5 lb/lb.mole)
= 2.55 lb.mole/hr
HC1 created = 2.55 lb.moie/hr
HC1 (lb/hr) (2.55 lb.mole/hr)(36.5 ib/lb.rnoie)
93.08 lb/hr
Calculate inlet halogen concentration
HC1 (scfm) = (93.08 lb/hr)(36.5 lb/lb.mole) * 392 scf/lb.mole *
1 hr/60 mm
16.66 scfm/min
HC1 (ppm) (16.66 scfm)/Qf 1 * 10A6
= (16.66/408) * 10A6
= 40,833 ppm (inlet concentration)
The halogen is chlorine, therefore
Molecular weight (Hal MW) = 35.5
Slope of operating curve (slope) = 0.10
Schmidt No. for HC1 in air (SCG) = 0.809
Schmidt No. for HC1 in water (SCL) = 381.0
Calculate the solvent flowrate. Account for increase in flow due
to quench chamber adding water vapor.
Newflow (l.7)(Qfj)
(1.7)(408 scfm)
694 scfm
Gas moles (694 scfm)(.075 lb/ft 3 )(lb.mole/29 lb)(60 min/hr)
(694) (0. 155)
107.7 lb.moie/hr
Liquid moles = (slope of operating curve)(adsorption factor AF)
(gas moles)
= (0.1)(1.6)(107.7)
17.23 lb.niole/hr
Liquid flow (gal/mm) = (17.23 lb.mole/hr)(18 lb/i b.mole)/
(62.43 lb/gal)/60 mm/hr * 7.48 gal/ft 3
Liquid flow = 0.62 gal/mm
gep.004 C-9
-------
Liquid flow (lb/hr) = (.62 gal/hr)(8.34 lb/gal)(60 rnin/hr)
310.2 lb/hr
Calculate Column Diameter
Density of air 0.0739 lb/ft 3 (from ideal gas law)
Density of liquid 62.2 lb/ft 3
MW of gas stream MW HCL x Volume Fraction + MW Air x Volume
Fraction
MW stream 36.5 * (40,833/10 6) + 29 * [ (10A6 40,833)/10 6]
36.5 * .040831 + 29 * 0.95917
29.31 lb/lb.mole
- Column diameter based on correlation for flooding rate in
randomly packed towers (see HAP manual)
ABSCISSA (liquid lb/hr)/(gas lb/hr) *
(density of gas/density of liquid O. 5
ABS (310.2/107.7 * 29) * (0.0739/62.2)AU.5
ABS 0.00342
IF ABS < 0.30
ORD = 10A [ 0.41402 * (log (ABS)/log (10)] - 1.40587)
ORD 10(1,92985 - 1.40587)
ORD = 10A( 0.385)
ORD 0.4122
Calculate GArea (lb/ft 2 .sec) based on column cross sectional area
at flooding conditions.
G_Area [ (ORD * density air * density liquid * 32.2 ft/sec 2 )
[ (packing factor constant)(viscosity of liquid) 0 )] 0 . 5
(0.91209)AO.5
= 0.955
Correct G_Area by f, the fraction of the flooding velocity
appropriate for the proposed operation
GArea (F)(0.955)
Assuming f 0.60
G_Area (0.60)(0.955)
= 0.57
gep.004 C-10
-------
Calculate the Area of the Column
Area of column (MW stream * gas moles)/(3,600 * G_Area)
Area (ft 2 ) (29.31 * 107.7)/(3,600 * 0.57)
Area (ft 2 ) 1.5 ft 2
Calculate Diameter of Column
D_col ((4/ ) Area]AO.S
= 1.13 (Area)AO. 5
1.40 ft
Calculate liquid flux rate
LL (lb/hr.ft 2 ) = (liquid flow lb/hr)/Area
LL (310.2)/(1.5)
206.8
Calculate the number of gas transfer units (NOG) (Assume 98%
removal efficiency)
NOG = Ln [ (Hal concentration/(0.02 * Hal concentration))
(1-(1/AF)) + (1/AF)]/(1/AF))J
NOG = Ln [ (40,833/0.02 * 40,832))(1-1/1.6) + (1/1.6)11(1-1/1.6)
= Ln [ (50)(0.375) + (0.625)]/(0.375)
In [ (19.375)]/(3.375)
= 2.964/0.375
= 7.904
Calculate the height of the overall gas transfer unit (HOG) using:
HOG Hg + (1/AF) H 1
where
HG Height of a single gas transfer unit (ft)
HL Height of a liquid transfer unit (ft)
Based on generalized correlations:
H 0 [ b * (3,600 * G_Area) C/(LVd))(SCG)AO.S
HL V * (IL/liquid viscosityy S*/(SCL)AO. 5 assuming 2 inch ceramic
raschig rings for packing
gep.004 C-li
-------
b = 3.82
c = 0.41
d = 0.45
s = 0.22
V = 0.0125
-, To convert from centipoise to lb/hreft 2
Liquid viscosity 0.85 * 2.42
g = 11.13
r 0.00295
Therefore,
HG = [ 3.82 * (3,600 * 0.57) 0.41/(206.8A0.45)] * SCL° . 5
= 7.9 x 0.809A0.5 7.113
HL = (0.0125) * (206.8/2.42)A0.22 * SCL 05
= 0.033 * 38V 0 . 5 = 0.649
Solving for HOG:
HOG = Hg + (1/AF) * HL
= 7.113 + (1/1.6) * 0.649
= 7.52
Calculate the height of the packed column from HOG and NOG. Allow
for 2 of freeboard above and below the packing for gas
disentanglement, and additional height based on column.
Height (Ht) (NOG)(HOG) + 2 + 0.25 * Diam. Col
= (7.9) (7.50) + 2 + 0.25 * 1.4
= 62 ft
Calculate Volume of Column
Volume (ir/4)(Diam col) 2 X Ht
(0.785)(1.4)A2 x 62
95 ft 3
gep.004 C-12
-------
Calculate Pressure Drop
DeFPa = (g x lO8) * iloA(r * LL/liquid density)] *
[ (3,600 * GArea) 2 )/gas density
DelPa (11.13 x 10-8) * (10 (0.00295 * 206.8/62.2)) *
((3600 * 057)A2)/00739
DelPa 6.48
Del Ptot DelPa * Ht/5.2
a 6.48 * 62/5.2
77.26
Total Cost of Tower is:
iCost 448.5714 * Diani * 12 + 1,514.285
= 448.5714 * (1.4) * 12 + 1,514.285
= 9,050.28
Cost of Packing
Packcost Volume of column * 20
_ 95 * 20
a 1,900
Asswne Cost of Duct Work and Fan
Duct cost 50 * 100
a 5,000
Fan cost 5,000
Caftulate Platform Cost. For columns less than 3 ft in diameter
design diam (DO) 3.
Platform Cost a 233 * DDA0 .74 * Ht 0707
233 * 3A0.74 * 62A0.707
a 9,719.56
Assun e Stackcost a 5,OQO
Calculate Total Capital Investment (TCI)
a (towercost + packcost + ductcost + fancost + platform cost +
stackcost)
gep.004 C-13
-------
TCI (9,050 + 1,900 + 5,000 + 5,000 + 9,720 + 5,000) *
CE Index/336.2
$35,670 * 355.6/336.2
$37,728
Calculate Water Costs
Water (liquid flow lb/hr)/8.34 lb/gal * price per 1,000 gal *
8,760 hr/yr
Water (310.2)/(8.34) * 0.22/1,000 * 8,760
Water 71.68
Calculate Electrical Costs Based on Pressure Drop
Elec = 0.0002 * new flow * DeiPtot * 8,760 * elec cost $/KW.Hr
0.0002 * 694 * 77.26 * 8,760 * 0.061
5,730.31 S/yr
Calculate Cost of Labor, Supervision, Maintenance
Op labor (1/2 hour per 8 hour shift ) *
(Annual operating hours) * (Op labor rate)
Op labor 0.5/8 * 8,760 * 15.64
Op labor = 8,563 S/yr
Supervision 0.15 * Op_Labor
Supervision 0.15 * 8,563 1,284.44
Maintenance labor 0.5/8 * 8,760 * 17.21
Maintenance labor 9,422.48 S/yr
Maintenance materials 9,428.48 $/yr
Calculate Direct Operating Costs
Dir Op Cost Water + electric + op_labor + supervision +
main labor + maintenance materials
gep.004 C-14
-------
Dir Op Cost 71.68 + 5,730.31 + 7,227 + 1,084.05 +
7,938.75 + 7,938.75
Dir Op Cost = 29,991 S/yr
Calculate cost of overhead, tax, insurance, administrative, and
capital recovery costs
Tax 0.01 * TCI 377.28
Insurance 0.01 * TCI 377.28
Administrative 0.02 * Id 754.56
CRC 0.16275 * TCI 6,140.23
Overhead 0.6 * (op_labor + supervision + main_La + maint)
Overhead = 17,215.44
Calculate indirect operating costs
md Op Cost = Overhead + Tax + Insurance + Administrative + CRC
17,215.44 + 377.28 + 377.28 + 754.56 + 6,140.23
= 24,864.79
Annual Operating Cost, Anncost
Anncost 29,991 + 24,864.79
Anncost = 54,856 S/yr
gep.004 C-15
-------
3. Hand Calculations for the VENTCOST Program - Flare Procedure
Used to assess control equipment cost for the SOCMI CTG
Calculations based on OAQPS Control Cost Manual, Chapter 7
The stream costed in this example is model stream D-HFLH. Its
characteristics are the following:
VOC to be controlled: Isophthalic acid
MW : 166 lb/lb mole
Flow Rate (total) : 637 scfm
VOC flow rate : 123 lb/hr
Heat value : 19 Btu/scf
Oxygen content : 0%
I. SIZING FOR FLARES
A. Flare tip diameter is generally sized on a velocity basis. Flare
tip sizing is governed by EPA rules defined in the
Federal Register . For flares with a heat value less than
300 Btu/scf the maximum velocity is 60 ft/sec.
1. The net heating value of vent stream 19 Btu/scf
2. Thus maximum velocity (Vmax), = 60 ft/sec. (It is standard
practice to size flares at 80 percent of VMAX).
3. Calculate the heat released by combustion of the vent stream
heatrel (Btu/hr) Vent flow * heat value * 60 mm/hr
637 scfm * 19 Btu/scf * 60
726,180 Btu/hr
4. Flare height (ft) Is determined using Equation 7-3 in OAQPS
SOCMI flares chapter.
Height (TFQ/r,rk) 05
where
T Fraction of heat intensity transmitted
F Fraction of heat radiated
Q Heat release (Btu/hr) 726,180 Btu/hr
k allowable radiation, (500 Btu/hr-ft 2 )
Assuming a) no wind effects, b) center of radiation at the
base of the flare, and c) thermal radiation limited at base of
the flare.
gep.004
C-16
-------
1=1
F = 0.3
k = 500
Substituting and simplifying,
Height ((heatrel) 05 )./144.72
(Note that this assumes allowable radiation 500 Btu/hr.ft 2 )
Height 5.88 ft
The minimum flare height is 30 ft. Therefore,
Height 30 ft
5. Calculate the auxiliary fuel flow required to sustain a stable
flame. A minimum heat value of 300 Btu/scf is required by
40 CFR, Section 60.18. Therefore, the auxiliary fuel flow,
Qaf (scfm) is:
Qaf Vent flow * (300 - heat value)/(1000-300)
637 * (300-19)/(1000-300)
255.71 scfm
6. Calculate total stream flow, QTot (scfm):
Qtot Vent flow + Qaf
637 + 255.71
893 scfm
7. Calculate minimum flare tip diameter, D, (inches) by
D = 12 [ 4/ir * (Qtot/60)/0.8 VMAX]° 5
= 12 [ 4/,r * 893/60)48]0.5
= 12(0.395)0.5
7.54 inches
Since the calculated diameter is rounded up to the next
commercially available size, available in two inch increments,
the diameter would be D 8 inches.
B. Purge Gas Requirement - Purge gas is used to maintain a minimum
required constant flow through the system. Using the conservative
value of 0.04 ft/sec (gas velocity) and knowing the flare diameter,
the annual P volume can be calculated.
1. P(Mscf/yr) = (0.04)(3,600)(8,760)( )/4 * (02)/144
P 6.88 x 02 (Mscf/yr)
P = 247.68 Mscf/yr
gep.004 C-li
-------
C. Pilot Gas Requirement
1. Since the number of pilot burners (n) is based on flare size
(flare diameter 1-10 1 pilot burner) this stream would
require I burner (our flare tip is 8)
2. Pilot gas flow (fp)
Fp (70 scf/hr) x N x (8,760 hr/yr)
613.2 Nscf/yr
D. Steam Requirement
The steam requirement depends on the composition of the vent gas
being flared, the steam velocity from the injection nozzle, and the
flare tip diameter.
1. The steam requirement can be calculated based on steam - CO 2
weight ratio of 0.68 (see Equation 7-7, OCCM Flares chapter).
Wsteam = WVOC (0.68 - 10.8/MW)
where
MW molecular weight of the VOC
Wsteam steam, (lbs/hr)
WVOC VOC (lb/hr)
thus
Wsteam = 123 (0.68 - 10.8/166)
75.64 lb/hr
E. Knockout Drum
The dropout velocity, U, of a particle in a stream, or the maximum
design vapor velocity, is calculated by:
1. U K X ((Pi - Pv)/Pv) 05 ft/sec
where
k design vapor velocity factor .2 assumed as
representative of the k range of 0.15 to 0.25
P 1 37 liquid density, assumed
0.1125 vapor density, assumed
gep.004 C-18
-------
U = 3.62
F. The maximum vessel cross-sectional area, A, can be calculated by:
A Qtot (ft 3 /min)/(60 x U (ft/sec), ft 2
Qtot 893 scfm,
A 893/(60 x 3.62)
A 2.93 ft 2
G. Calculate vessel diameter
1. The vessel diameter, dmjn, is calculated by:
dnjn = 12 (in/ft) x (4 x A (ft 2 )/ir)O. 5 , inches
dmin 12 X (4 X 2.93/ir)05
23.18 inches
2. In accordance with standard head sizes, drum diameters in
6-inch increments are assumed so:
d = dmjn to the next largest 6 inches
d = 24 inches
3. The vessel height, h, is determined by:
h =3 xd, inches
h = 3 x 24 = 72 inches
II. COST ANALYSIS - ESTIMATING TOTAL CAPITAL INVESTMENT FOR FLARES
(*Assuming March 1990 Dollars)
A. Flare costs (Cf) are calculated as a function of stack height, H
(ft) and tip diameter, D, (in), and are based on support type.
Derrick support group was not considered since the stack height is
< 100 ft.
1. Self Support Group
Cf = [ 78 + 9.14 (D) + .75 (H)] 2
gep.004 C-19
-------
Cf [ 78 + 9.14 (8) + .75 (30)32
Cf 30,144
2. Guy Support Group:
Cf (103.17 + 8.68(8) + .47 (30)]2
Cf 34,861
Since Self Support is < Guy Support, the cheaper is chosen.
B. Cost for 100 ft of transfer and header pipe, C , assuming
400 length needed.
C = (119.4 x Dl 155 ) x 4
= (119.4 x 81.155) x 4
CP = 5,274
C. Cost for knockout drum, Ck, is a function of drum diameter, d (ft)
and height (ft)
Ck 555 x [ d x t x (h + 0.08116 x d)) 0 737
where
t vessel thickness (in)
vessel thickness is determined based on drum diameter. Since
Drum diameter, d 24 inches 2.0 ft and
Drum height, h 72 inches 6.0 ft,
Drum thickness, t 0.25 inches.
ti 6
Ck 555 x [ 2 x 0.25 x (6 + 0.8116 x 2)]0.737
Ck 1,271.97
0. Collection Fan Cost
Cfan (79.1239 X 893 scfm 0561168 ) x 354.6/342.5
3,709
Collection Fan Cost based on 1988 Richardson Manual; see Chris
Bagleys March 9, 1990 calculation placed In the polystyrene file.
gep.004 C-20
-------
E. Flare system equipment cost, EC, is the total of the calculated
flare, knockout drum, manifold piping, and collection fan cost.
Ec Cf + Ck + Cp + Cfan
Ec 30,144 + 1,272 + 3,709 + 5,274
Ec 40,399
F. Purchased equipment cost, PEC, is equal to equipment cost, EC, plus
factors for instrumentation (.10), sales taxes (0.03) and freight
(0.05) or
PEC EC x (1 + 0.10 + 0.03 + 0.05)
PEC = 1.18 x 40,399
PEC = 47,671
G. Installation Costs: The total capital investment, TCI is obtained
by multiplying the purchased equipment costs, PEC, by an
installation factor of 1.92
TCI 1.92 x PEC
TCI = 1.92 x 47,671
id 91,529
gep.004 C-21
-------
III. ANNUAL COST FOR FLARES
A. Direct Annual Cost
1. Total natural gas cost, Cf, to operate a flare system includes
pilot, C , auxiliary fuel, Ca, and purge cost
Cf Cp + Ca +
where C is equal to the annual volume of pilot gas, f ,
multiplied by the cost per scf
C , ($/yr) f (scf/yr) x ($/scf)
Assume price of natural gas 3.30 $/Mscf
C (613.2 Mscf/yr) x (3.30 $/Mscf)
$2,024/yr
2. Annual Purge gas cost Cpu 247.68 x D 2 (Mscf/yr) *
(3.3 $/Mscf)
Annual Cpu $817.3/yr
3. Auxiliary Gas Cost Ca
134,401 Mscf/,yr x 3.3 $/Mscf = $443,523/yr
4. Cf 2,024 + 817.3 + 443,523 $446,364/yr
B. Calculate Steam Cost (Cs) required to eliminate smoking
C ($/yr) 8,760 (hr/yr) x steam use (ib/yr) x (Sub)
C 5 8,760 x 75.64 x 4.65 x
C $6,590
C. Calculate operating labor cost, based on 630 manhours/yr
Operator labor 630 x $15.64 9,853
Supervisor labor 9,853 x .15 1.478
11,331
0. Maintenance labor cost and materials
gep.004 C-22
-------
Maintenance labor ($/yr) (1/2 hr/8 hrs shift) x 8,760 hr/yr x
$17.21/hr $9,422/yr
Materials assumed equal to maintenance labor $9,422/yr
E. Overhead Cost
= 0.60 x (op labor + m + labor + materials)
0.60 x 30,175 18,105
F. Capital Recovery Factor: Assume 15 year life and 10% interest
so CRF = 0.1314
Capital recovery cost 0.1414 x IC!
= 0.1314 x 91,529
= $12,034
G. General and Administrative, Taxes, and Insurance Costs
Assume 4% of total capital investment
4% of 91,529
= 3,661
H. Utilities - Power consumption based on actual minimum flow
power = (1.17 x x 893 x 4/.60)
power = .7 kw
I. Elec cost power x op hours x elec price (S/1000 kW.hrs)
(0 . 70) (8, 760) (0. 061)
= 372
J. Calculating total Annual Costs (Indirect and Direct)
1. Direct Annual Cost
Direct Cost = Cost electricity + materials +
maintenance labor + supervisors +
operation labor + steam cost + fuel cost
gep.004 C-23
-------
Direct cost 372 + 9,422 + 9,422 + 1,478 + 9,853 +
6,590 + 443,523
480,660
2. Indirect Annual Cost
IAC = general + capital recovery cost + overhead
IAC 3,661 + 12,034 + 18,105
IAC 33,800
K. Annual Cost = Direct cost + Indirect Cost
= 480,660 + 33,800
514,460
gep.004 C-24
-------
APPENDIX D
SOCMI CTG EXAMPLE RULE
-------
EXAMPLE ONLY
APPENDIX 0
SOCMI CTG EXAMPLE RULE
0.1 INTRODUCTION
This appendix presents an example rule limiting volatile organic
compound (VOC) emissions from reactor processes and distillation operations.
The example rule is for informational purposes only and, as such, is not
binding on the air quality management authority. The purpose of the example
rule is to provide information on all the factors that need to be considered
in writing a rule to ensure that it is enforceable.
Two points concerning implementation of the recommended RACT in
Chapter 6 warrant special mention. First, Chapter 6 recommended that any
reactor process or distillation vent stream for which an existing combustion
device is employed to control VOC emissions should not be required to meet
the 98 percent destruction or 20 ppmv emissions limit until the combustion
device is replaced for other reasons. Second, Chapter 6 recommended. that the
flow rate and VOC concentration cutoff points be applied on both an
individual and combined vent stream basis for a given process unit.
Therefore, in accordance with this recommendation, controls would be
installed at a process unit with multiple vents if either an individual vent
stream or the combined vent streams exceed the cutoff criteria.
The remainder of this appendix constitutes the example rule. Sections
are provided on the following rule elements: applicability, definitions,
control requirements, performance testing, and reporting/recordkeeping.
D..2 APPLICABILITY
(a) The provisions of this rule apply to any vent stream originating
from a process unit in which reactor process or distillation operation is
located.
(b) Exemptions from the provisions of this rule are as follows:
(1) Any reactor process or distillation operation that is designed and
operated in a batch mode is not subject to the provisions of this rule.
(2) Any reactor process or distillation operation operating in a
process unit with a total design capacity of less than I gigagrarn per year
(Gg/yr) for all chemicals produced within that unit is not subject to the
gep.004 0-1
-------
EXAMPLE ONLY
provisions of this rule except for the reporting and recordkeeping
requirements listed in 0.7(e).
(3) Any vent stream for a reactor process or distillation operation
with a flow rate less than 0.011 scm/mm is not subject to the provisions of
this rule except for the performance testing requirement listed in 0.5(d) and
the reporting and recordkeeping requirements listed in 0.7(d).
D.3 DEFINITIONS
Batch distillation operation means a noncontinuous distillation
operation in which a discrete quantity or batch of liquid feed is charged
into a distillation unit and distilled at one time. After the initial
charging of the liquid feed, no additional liquid is added during the
distillation operation.
Batch process means any noncontinuous reactor process which is not
characterized by steady-state conditions and in which reactants are not added
and products are not removed simultaneously.
Boiler means any enclosed combustion device that extracts useful energy
in the form of steam.
By compound means by individual stream components, not carbon
equivalents.
Continuous recorder means a data recording device recording an
instantaneous data value at least once every 15 minutes.
Distillation operation means an operation separating one or more feed
stream(s) into two or more exit stream(s), each exit stream having component
concentrations different from those in the feed stream(s). The separation is
achieved by the redistribution of the components between the liquid and
vapor-phase as they approach equilibrium within the distillation unit.
Distillation unit means a device or vessel In which distillation
operations occur, including all associated internals (such as trays or
packing) and accessories (such as reboiler, condenser, vacuum pump, stream
jet, etc.), plus any associated recovery system.
Flame zone means the portion of the combustion chamber In a boiler
occupied by the flame envelope.
Flow indicator means a device which indicates whether gas flow is
present in a vent stream.
gep.004 D-2
-------
EXAMPLE ONLY
Halogenated vent stream means any vent stream determined to have a total
concentration (by volume) of compounds containing halogens of 20 ppmv (by
compound) or greater.
Incinerator means any enclosed combustion device that is used for
destroying organic compounds and does not extract energy in the form of steam
or process heat.
Process heater means a device that transfer heat liberated by burning
fuel to flu ids contained in tubes, including all fluids except water that is
heated to produce steam.
Process unit means equipment assembled and connected by pipes or ducts
or produce, as intermediates or final products, one or more of the chemicals
in (see Appendix A of the CTG). A process unit can operate independently if
supplied with sufficient feed or raw materials and sufficient product storage
facil ities ..
Product means any compound or chemical listed in (see Appendix A of the
CTG) which is produced for sale as a final product as that chemical, or for
use in the production of other chemicals or compounds. By-products,
co-products, and intermediates are considered to be products.
Reactor processes are unit operations in which one or more chemicals, or
reactants other than air, are combined or decomposed in such a way that their
molecular structures are altered and one or more new organic compounds ar
formed.
Recovery device means an individual unit of equipment, such as an
adsorber, carbon adsorber, or condenser, capable of and used for the purpose
of recovering chemicals for use, reuse, or sale.
Recovery system means an individual recovery device or series of such
devices applied to the same vent stream.
Total organic compounds (TOC) means those compounds measured according
to the procedures in 0.5. For the purposes of measuring VOC weight percent
to determine compliance with 0.4(c), the definition of the TOC excludes the
following compounds: methane; ethane; 1,1,1-trichioroethane; methylene
chloride,. trichiorofluoromethane; dichiorodifluoromethane;
chlorodifl.uoromethane; trifluoromethane; trichiorotrifluoroethane;
di chi orotetrafi uoroethane; and chioropentafi uoroethane.
Vent stream means any gas stream discharge directly from a distillation
facility ta the atmosphere or indirectly to the atmosphere after diversion
gep.004 0-3
-------
EXAMPLE ONLY
through other process equipment. The vent stream excludes relief valve
discharges and equipment leaks including, but not limited to, pumps,
compressors, and valves.
0.4 CONTROL REQUIREMENTS
For individual vent streams within a process unit, or for all vent
streams in aggregate within a process unit, having a flow rate above
_____ scfm and a TOC concentration above _____ weight percent shall comply
with paragraphs (a) or (b) of this section.
(a) Reduce emission of TOC (less methane and ethane) by
98 weight-percent, or to 20 ppmv, on a dry basis corrected to 3 percent
oxygen, whichever is less stringent. If a boiler or process heater is used
to comply with this paragraph, then the vent stream shall be introduced into
the flame zone of the boiler or process heater.
(b) Combust emissions in a flare. Flares used to comply with this
paragraph shall comply with the requirements of 40 CFR 60.18.
(c) For individual vent streams with a process unit, or for all vent
streams in aggregate within a process unit, having a flow rate below
scfm and a TOC concentration below _____ weight percent shall maintain
a vent stream flow rate below _____ scfm or a vent stream TOC concentration
below _____ weight percent without the use of a VOC combustion control
device.
0.5 PERFORMANCE TESTING
(a) For the purpose of demonstrating compliance with the control
requirements of this rule, the process unit shall be run at full operating
conditions and flow rates during any performance test.
(b) The following methods in 40 CFR 60, Appendix A, shall be used to
comply with the emission limit or percent reduction efficiency requirement
listed in D.4(a).
(I) Method I or 1A, as appropriate, for selection of the sampling
sites. The control device inlet sampling site for determination of vent
stream molar composition or TOC (less, methane and ethane) reduction
efficiency shall be prior to the inlet of the control device and after the
recovery system.
(2) Method 2, 2A, 2C, or 2D, as appropriate, for determination of gas
stream volumetric flow rate.
gep.004 0-4
-------
EXAMPLE ONLY
(3) The emission rate correction factor, integrated sampling and
analysis procedure of Method 3 shall be used to determine the oxygen
concentration (% 0 2d) for the purpose of determining compliance with the
20 ppmv limit. The sampling site shall be the same as that of the TOC
samples and samples shall be taken during the same time that the TOG samples
are taken. The TOG concentration corrected to 3 percent 02 (Cc) shall be
computed using the following equation:
c = TOG
20.9 - % 0 2d
where:
C = Concentration of TOC corrected to 3 percent 02, dry basis, ppm
by volume.
CTOC = Concentration of TOC, dry basis, ppm by volume.
% 0 2d = Concentration of 02, dry basis, percent by volume.
(4) Method 18 to determine the concentration of TOC in the control
device inlet and outlet when the reduction efficiency of the control device
is to be determined.
(i) The sampling time for each run shall be 1 hour in which either an
integrated sample or four grab samples shall be taken. If grab sampling is
used then the samples shall be taken at 15-minute intervals.
(ii) The emission reduction (R) of TOC (minus methane and ethane) shall
be determined using the following equation:
R =E1 _E0xJOO
Ei
where:
R Emission reduction, percent by weight.
Mass rate of bC entering the control device, kg TOC/hr.
= Mass rate of TOC discharged to the atmosphere, kg TOC/hr.
gep.004 0-5
-------
EXAMPLE ONLY
(iii) The mass rates of bC (E 1 , E 0 ) shall be computed using the
following equations:
n
E 1 K 2 ( E Cj,jMjj) Qj
j.4
n
= K 2 ( CojMoj) Q.j
jal
where:
CTOC = Concentration of sample component j of the gas stream at
the inlet and outlet of the control device, respectively, dry
basis, ppm by volume.
M 0 = Molecular weight of sample component j of the gas stream
at the inlet and outlet of the control device, respectively,
g/g-mole (lb/lb-mole).
Q , Q 0 = flow rate of gas stream at the inlet and outlet of the
control device, respectively, dscm/min (dscf/min).
Ks = 2.494 x 10-6 (1/pm)(g-mole/scm)(kg/g)(mifl/hr), where standard
temperature for (g-mole/scm) is 20°C.
(iv) The TOC concentration (CTOC) is the sum of the individual
components and shall be computed for each run using the following equation:
n
C 10 1 E C
j 1
where:
ClOG = Concentration of bC (minus methane and ethane), dry basis, ppm
by volume.
C j Concentration of sample component i, dry basis, ppm by volume.
n Number of components in the sample.
gep.004 D-6
-------
EXAMPLE ONLY
(5) When a boiler or process heater with a design heat input capacity
of 44 MW (150 million Btu/hr) or greater is used to comply with the control
requirements, the requirement for an initial performance test is waived.
(c) When a flare is used to comply with the control requirements of
this rule, the flare shall comply with the requirements of 40 CFR 60.18.
(d) The following test methods shall be used to determine compliance
with the flow rate and concentration cutoff points listed in D.4(c).
(1)(i) Method I or 1A, as appropriate, for selection of the sampling
site. The sampling site for the vent stream molar composition determination
and flow rate prescribed in D.5(d)(2) and (d)(3) shall be, except for the
situations outlined in paragraph (d)(1)(ii) of this section, prior to the
inlet of any control device, prior to any post-rector introduction of
halogenated compounds into the process vent stream. No traverse site
selection method is needed for vents smaller than 4 inches in diameter.
(ii) If any gas stream other than the reactor vent stream is normally
conducted through the final recovery device:
(A) The sampling site for vent stream flow rate and molar composition
shall be prior to the final recovery device and prior to the point at which
any nonreactor stream or stream from a nonaffected reactor is introduced.
(B) The efficiency of the final recovery device is determined by
measuring the TOC concentration using Method 18 at the inlet to the final
recovery device after the introduction of all vent streams and at the outlet
of the final recovery device.
(C) The efficiency of the final recovery device shall be applied to the
TOC concentration measured prior to the final recovery device and prior to
the introduction of any nonreactor stream or stream from a nonaffected
reactor to determine the concentration of TOG in the reactor vent stream the
from the final recovery device. This concentration of TOC is then used to
perform the calculations outlined in D.5(d)(5).
(2) The molar composition of the vent stream shall be determined as
follows:
(1) Method 18 to measure the concentration of TOC including those
containing halogens.
(ii) ASTM D1946-77 to measure the concentration of carbon monoxide and
hydrogen.
(iii) Method 4 to measure the content of water vapor.
gep.004 0-7
-------
EXAMPLE ONLY
(3) The volumetric flow rate shall be determined using Method 2, 2A,
2C, or 2D, as appropriate.
(4) The emission rate of TOC in the vent stream shall be calculated
using the following equation:
n
2 E CjM Qs
ill
where:
ETOT = Emission rate of TOC in the sample, kg/hr.
K 2 Constant, 2.494 x 10-6 (l/ppm)(g-mole/scm)(kg/g)(mifl/hr), where
standard temperature for (g-mole/scm) is 200C.
Cj Concentration on a basis of compound j in ppm as measured by
Method 18 as indicated in D.5(b)(4).
= Molecular weight of sample j, gig-mole.
= Vent stream flow rate (scm/mm) at a temperature of 20°C.
(6) The total process vent stream concentration (by volume ) of
compounds containing halogens (ppmv, by compound) shall be summed from the
individual concentrations of compounds containing halogens which were
measured by Method 18.
(e) Each owner or operator of an affected facility seeking to comply
with D.4(c) shall recalculate the flow rate and bC concentration for that
affected facility whenever process changes are made. Examples of process
changes include changes in production capacity, feedstock type, or catalyst
type, or whenever there is replacement, removal, or addition of recovery
equipment. The flow rate and VOC concentration shall be recalculated based
on test data, or on best engineering estimates of the effects of the change
to the recovery system.
(1) Where the recalculated values are above the cutoff values listed in
0.4(c), the owner or operator shall notify the Agency within 1 week of the
recalculation and shall conduct a performance test according to the methods
and procedures required by D.5.
gep.004 0-8
-------
EXAMPLE ONLY
0.6 MONITORING REQUIREMENTS
(a) The owner or operator of an affected facility that uses an
incinerator to seek to comply with the TOC emission limit specified under
0.4(a) shall install, calibrate, maintain, and operate according to
manufacturers specifications the following equipment.
(1) A temperature monitoring device equipped with a continues recorder
and having an accuracy of ±0.5°C, whichever is greater.
(i) Where an incinerator other than a catalytic incinerator is used, a
temperature monitoring device shall be installed in the firebox.
(ii) Where a catalytic incinerator is used, temperature monitoring
devices shall be installed in the gas stream imediately before and after the
catalyst bed.
(2) A flow indicator that provides a record of vent stream flow to the
incinerator at least once very hour for each affected facility. The flow
indicator shall be installed in the vent stream from each affected facility
at a point closest to the inlet of each incinerator and before being jointed
with any other vent stream.
(b) The owner or operator of an affected facility that uses a flare to
seek to comply with 0.4(b) shall install, calibrate, maintain and operate
according to manufacturers specifications the following equipment:
(1) A heat sensing device, such as a ultra-violet beam sensor or
thermocouple, at the pilot light to indicate continuous presence of a flame.
(2) A flow indicator that provides a record of vent stream flow to the
flare at lease once every hour for each affected facility. The flow
indicator shall be installed in the vent stream from each affected facility
at a point closest to the flare and before being joined with any other vent
stream.
(c) The owner or operator of an affected facility that uses a boiler or
process heater to seek to comply with 0.4(a) shall install, calibrate,
maintain, and operate according to the manufacturers specifications the
following equipment:
(1) A flow indicator that provides a record of vent stream flow to the
boiler or process heater at least once every hour for each affected facility.
The flow indicator shall be installed in the vent stream from each affected
facility at the point closest to the inlet of each boiler or process heater
and before being joined with any other vent stream.
gep.004 0-9
-------
EXAMPLE ONLY
(2) A temperature monitoring device in the firebox equipped with a
continuous recorder and having an accuracy of ±1 percent of the temperature
being measured expressed in degrees Celsius or ±0.5CC, whichever is greater,
for boilers or process heaters of less than 44 MW (150 million Btu/hr) design
heat input capacity.
(3) Monitor and record the periods of operation of the boiler or
process heater if the design heat input capacity of the boiler or process
heater is 44 MW (150 million Btu/hr) or greater. The records must be readily
available for inspection.
(d) The owner or operator of an affected facility that seeks to
demonstrate compliance with the flow rate and TOC concentration cutoff points
listed in 0.4(c) shall install, calibrate, maintain, and operate according to
manufacturers specifications the following equipment:
(1) Where an absorber is the final recovery device in the recovery
system:
(1) A scrubbing liquid temperature monitoring device having an accuracy
of ±1 percent of the temperature being monitored expressed in degrees Celsius
or ±0.50C, whichever is greater, and a specific gravity monitoring device
having an accuracy of ±0.02 specific gravity unit, each equipped with a
continuous recorder, or
(ii) An organic monitoring device used to indicate the concentration
level of organic compounds exiting the recovery device based on a detection
principle such as infra-red photoionization, or thermal conductivity, each
equipped with a continuous recorder.
(2) Where a condenser is the final recovery device in the recovery
system:
(i) A condenser exist (product side) temperature monitoring device
equipped with a continuous recorder and having an accuracy of ±1 percent of
the temperature being monitored expressed in degrees Celsius or ±O.5 0 C,
whichever is greater, or
(ii) An organic monitoring device used to Indicate the concentration
level of organic compounds exiting the recovery device based on a detection
principle such as infra-red, photoionization, or thermal conductivity, each
equipped with a continuous recorder.
(3) Where a carbon adsorber is the final recovery device unit in the
recovery system:
gep.004 0-10
-------
EXAMPLE ONLY
(i) An integrating steam flow monitoring device having an accuracy of
±10 percent, and a carbon bed temperature monitoring device having an
accuracy of ±1 percent of the temperature being monitored expressed in
degrees Celsius or ±0.5°C, whichever is greater, both equipped with a
continuous recorder, or
(ii) An organic monitoring device used to indicate the concentration
level of organic compounds exiting the recovery device based on a detection
principle such as infra-red, photolonization, or thermal conductivity, each
equipped with a continuous recorder.
D.7 REPORTING/RECORDKEEPING REQUIREMENTS
(a) Each reactor process or distillation operation subject to this rule
shall keep records of the following parameters required to be measured during
a performance test required under 0.5, and required to be monitored
under D.6.
(1) Where an owner or operator subject to the provisions of this
subpart seeks to demonstrate compliance with D.4(a) through use of either a
thermal or catalytic incinerator:
(i) The average firebox temperature of the incinerator (or the average
temperature upstream and downstream of the catalyst bed for a catalytic
incinerator), measured at least every 15 minutes and averaged over the same
time period of the performance testing, and
(ii) The percent reduction of TOG determined as specified in 0.5(b)
achieved by the incinerator, or the concentration of TOG (ppmv, by compound)
determined as specified in 0.5(b) at the outlet of the control device on a
dry basis corrected to 3 percent oxygen.
(2) Where an owner or operator subject to the provisions of this
subpart seeks to demonstrate compliance with 0.4(a) through use of a boiler
or process heater:
(1) A description of the location at which the Vent stream is
introduced into the boiler or process heater, and
(ii) The average combustion temperature of the boiler or process heater
with a design heat input capacity of less than 44 MW (150 million Btu/hr)
measured at least every 15 minutes and averaged over the same time period of
the performance testing.
gep.004 0-11
-------
EXAMPLE ONLY
(3) Where an owner or operator subject to the provisions of this
subpart seeks to demonstrate compliance with 0.4(b) through use of a
smokeless flare, flare design (i.e., steam-assisted, air-assisted or
nonassisted), all visible emission readings, heat content determinations,
flow rate measurements, and exit velocity determinations made during the
performance test, continuous records of the flare pilot flame monitoring, and
records of all periods of operations during which the pilot flame is absent.
(4) Where an owner or operator subject to the provisions of this
subpart seeks to demonstrate compliance with D.4.(c):
(1) Where an absorber is the final recovery device in the recovery
system, the exit specific gravity (or alternative parameter which is a
measure of the degree of absorbing liquid saturation, if approved by the
Agency), and average exit temperature of the absorbing liquid, measured at
least every 15 minutes and averaged over the same time period of the
performance testing (both measured while the vent stream is normally routed
and constituted), or
(ii) Where a condenser is the final recovery device the recovery
system, the average exit (product side) temperature measured at least every
15 minutes and averaged over the same time period of the performance testing
while the vent stream is routed and constituted normally, or
(iii) Where a carbon adsorber is the final recovery device in the
recovery system, the totals team mass flow measured at least every 15 minutes
and averaged over the same time period of the performance test (full carbon
bed cycle), temperature of the carbon bed after regeneration (and within
15 minutes of completion of any cooling cycle(s)), and duration of the carbon
bed steaming cycle (all measured while the vent stream is routed and
constituted normally), or
(iv) As an alternative to D.7(b)(4)(i), (b)(4)(ii) or (b)(4)(iii), the
concentration level or reading indicated by the organics monitoring device at
the outlet of the absorber, condenser, or carbon adsorber, measured at least
every 15 minutes and averaged over the same time period of the performance
testing while the vent stream is normally routed and constituted.
(v) All measures and calculations performed to determine the flow rate
and VOC concentration of the vent stream.
gep.004 0-12
-------
EXAMPLE ONLY
(b) Each reactor process or distillation operation subject to this rule
shall provide a report identifying the following exceedances of monitored
parameters and corrective measures, if any, taken.
(1) Where a thermal incinerator is used to comply with D.4(a):
(I) All 3-hour periods of operation when the average firebox
temperature is more than 280C (50°F) below the temperature measured during
the most recent performance test.
(ii) All periods when the vent stream is diverted from the incinerator.
(2) Where a catalytic incinerator is used to comply with D.4(a):
(I) All 3-hour periods operation during which the average temperature
of the vent stream immediately before the catalyst bed is more than 28°C
(50°F) below the temperature measured during the most recent performance
test.
(ii) All 3-hour periods of operation when the average difference in
temperature between downstream and upstream of the catalyst bed is less than
80 percent of the average difference measured during the most recent
performance test.
(iii) All periods when the vent stream is diverted from the catalytic
incinerator.
(3) Where a boiler or process heater is used to comply with D.4(a):
(I) For boiler or process heaters less than 150 million Btu/hr, all
3-hour periods of operation when the average firebox temperature is more than
28°F (50°F) below the temperature measured during the most recent performance
test.
(ii) Whenever there is a change in the location at which the vent
stream is introduced into the flame zone.
(iii) All periods when the vent stream is diverted from the boiler or
process heater.
(iv) All periods of operation of the boiler or process heater (examples
of such records could include records of stem use, fuel use, or other
monitoring data).
(4) Where a flare is used to comply with D.4(b):
(1) All periods of operation when the pilot flame is absent.
(ii) All periods when the vent stream is diverted from the flare.
(5) When an absorber is used to comply with D.4(c):
gep.004
D- 13
-------
EXAMPLE ONLY
(I) All 3-hour periods of operation during which the average absorbing
liquid temperature was more than 11°C (20°F) above the average absorbing
liquid temperature during the most recent performance test, or
(ii) All 3-hour periods of operation during which the average absorbing
liquid specific gravity was more than 0.1 unit above, or more than 0.1 unit
below, the average absorbing liquid specific gravity during the most recent
performance test (unless monitoring of an alternative parameter, which is a
measure of the degree of absorbing liquid saturation, is approved by the
Administrator, in which case he will define appropriate parameter boundaries
and periods of operation during which they are exceeded).
(6) Where is a condenser is the final recovery device in a system, and
where an organic compound monitorin.g device is not used, all 3-hour periods
of operation during which the average exist (product side) condenser
operating temperature was more than 6°C (11°F) above the average exit
(product side) operating temperature during the most recent performance test.
(7) Where a carbon adsorber is the final recovery device in a system,
and where an organic compound monitoring device is not used:
(1) All carbon bed regeneration cycles during which the total mass
steam flow was more than 10 percent below the total mass steam flow during
the most recent performance test, or
(ii) All carbon bed regeneration cycles during which the temperature of
the carbon bed after regeneration [ and after completion of any cooling
cycle(s)] was more than 10 percent greater than the carbon bed temperature
(in degrees Celsius) during the most recent performance test.
(8) Where an absorber, condenser, or carbon adsorber is the final
recovery device in the recovery system and where an organic monitoring device
is used, all 3-hour periods of operation during which the average organic
compound concentration level or reading of organic compounds in the exhaust
gases is more than 20 percent greater than the exhaust gas organic compound
concentration level or reading measured by the monitoring device during the
most recent performance test.
(c) Each reactor process or distillation operation seeking to comply
with D.4(c) shall also keep records of the following Information.
(1) Any changes in production capacity, feedstock type, or catalyst
type, or of any replacement, removal, and addition of recovery equipment or
reactors and distillation units.
gep.004 D-14
-------
EXAMPLE ONLY
(2) Any recalculation of the flow rate or bC concentration performed
according to D.5(e).
(d) Each reactor process or distillation operation seeking to comply
with the flow rate exemption level in D.2(b)(3) shall keep records to
indicate that the stream flow rate is less than .011 scm/mm.
(e) Each reactor process or distillation operation seeking to comply
with the production capacity exemption level of I Gg/yr shall keep of any
changes in equipment or process operation that may affect design production
capacity of the affected process unit.
gep.004 D-15
-------
APPENDIX E
ENVIRONMENTAL IMPACTS CALCULATIONS
-------
APPENDIX E
ENVIRONMENTAL IMPACTS CALCULATIONS
E.1 CALCULATION OF SECONDARY AIR IMPACTS
Calculations will be based on model stream R-LFHH, the same stream used
as an example in Appendix C.
E.2 ESTIMATING CO EMISSIONS
Calculate total heat input of the stream to be combusted.
(1) H 1 Initial heat input of waste stream
H 1 (flowrate)(heat value)
(400 scfm)(64.3 Btu/scf)
= 25,720 Btu/min x (60 min/hr) x (8,760 hr/yr) x (MMBtu/10 6 Btu)
13,518 MMBtu/yr
(2) H 2 = Heat input from auxiliary fuel
H 2 = (flowrate)(heat value)
= (0.8 scfm)(1,000 Btu/scf)
= 800 Btu/min
= 420 MMBtu/yr
(3) Total heat input = Hj + H 2
= (13,518 + 402) MMBtu/yr
13,938 MMBtu/yr
Calculate CO emissions using AP-42 factor of 20 lb CO/MMscf of fuel.
(1) Convert MMBtu/yr to equivalent fuel flow (QF)
QF (13,938 MMBtu/yr)(scf/1,000 Btu)
13.9 MMscf/yr
(2) COem = (13.9 MMscf/yr)(20 lb/MMscf)(Mg/2,207 ib)
= 0.126 Mg/yr of CO
E.3 ESTIMATING NOx EMISSIONS
Determine method of control (flare or incinerator). Model stream R-LFHH
is cheapest to control using incinerator with scrubber (see Appendix.C for
costing analysis).
For incinerators, two NOx emission factors are used; one for streams
containing nitrogen compounds, and one for streams without nitrogen
gep.004 E-1
-------
compounds. Inert nitrogen gas (N 2 ) is not included. The NOx factors for
incinerators are as follows:
with nitrogen compounds: 200 ppm in exhaust
without nitrogen compounds: 21.5 ppm in exhaust
The model stream R-LFHH has not nitrogen, so 21.5 ppm will be used. These
factors reflect testing data that was gathered for the Air Oxidation Reactor
processes CTG and the Polymers and Resins CTG.
Calculate total outlet flow, as explained in Appendix C. As shown on
page C-9, the total outlet flow exiting the incinerator/scrubber system is
694 scfm.
(1) NOx emissions (694 scfm)(2].5/10 6 )/(392 scf/lb.mole) x
(46 lb/lb.mole)
NOx emissions = (0.00175 lb/mm) x (60 min/hr) x (8,760 hr/yr) x
(Mg/2,207 ib)
- 0.42 Mg/yr
(2) If the total outlet flow rate from the incinerator is not known,
the following emission factors may be used to calculate NOx emissions:
with nitrogen compounds: 0.41 lb NO /MMBtu
without nitrogen compounds: 0.08 lb NOx/MMBtu
As calculated in E.2 (3), the total heat input is 13,938 MMBtu/yr.
Therefore, the NOx emissions estimated using this factor are calculated by:
NOx emissions (913,938 MMBtu/yr)(O.08 lb NOx/MMBtu) X (Mg/2,207 ib)
- 0.51 Mg/yr
gep.004 E-2
------- |