United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/3-83-019b
October 1990
Air
Polymer
Manufacturing
Industry -
Background
Information for
Promulgated
Standards
Final
EIS
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EPA-450/3-83-019b
Polymer Manufacturing Industry
Background Information For
Promulgated Standards
Emission Standards Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
October 1990
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DISCLAIMER
This report has been reviewed by the Emission Standards Division, Office
of Air Quality Planning and Standards, Office of Air and Radiation,
Environmental Protection Agency, and approved for publication. Mention
of company or product names does not constitute endorsement by EPA.
Copies of this report are available free of charge to Federal employees,
current contractors and grantees, and non-profit organizations -- as
supplies permit -- from the Library Services Office, MD-35, U.S.
Environmental Protection Agency, Research Triangle Park, N.C. 27711; or
may be obtained, for a fee, from the National Technical Information
Services, 5285 Port Royal Road, Springfield, Virginia 22161.
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ENVIRONMENTAL PROTECTION AGENCY
Background Information and Final
Environmental Impact Statement
for Polymer Manufacturing Industry
rack R. rarmer- / (DateT
Director, Emission Standards Division
U.S. Environmental Protection Agency (MD-13)
Research Triangle Park, North Carolina 27711
1. The emission standards will limit emissions of volatile organic
compounds from new, modified, and reconstructed polymer
manufacturing facilities. The standards implement Section 111 of
the Clean Air Act (42 U.S.C. 7411), as amended, and are based on
the Administrator's determination of August 21, 1979 (44 FR 49222)
that polymer manufacturing plants contribute significantly to air
pollution which may reasonably be anticipated to endanger public
health or welfare.
2. Copies of this document have been sent to the following Federal
Departments: Labor, Health, and Human Services, Defense,
Transportation, Agriculture, Commerce, Interior, and Energy; the
National Science Foundation; the Council on Environmental Quality;
State and Territorial Air Pollution Program Administrators; EPA
Regional Administrators; Local Air Pollution Control Officials;
Office of Management and Budget; and other interested parties.
3. For additional information contact:
Fred Dinunick
Standards Development Branch (MD-13)
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Telephone: (919) 541-5625
4. Copies of this document may be obtained from:
U.S. Environmental Protection Agency Library (MD-35)
Research Triangle Park, North Carolina 27711
National Technical Information Service
5285 Port Royal Road
Springfield, Virginia 22161
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TABLE OF CONTENTS
Chapter paqe
1.0 SUMMARY i-1
1.1 Summary of Changes Since Proposal l-l
1.1.1 Definition of Intermittent Releases
to be Controlled 1-2
1.1.2 Monitoring of Vent Streams 1-3
1.1.3 VOC Weight Percent Exemption 1-3
1.1.4 Definition.of Concurrently Constructed,
Modified, and Reconstructed Affected
Facilities 1-4
1.1.5 Reduced Testing Program for PET Facilities 1-4
1.1.6 Applicable Standards and Uncontrolled
Threshold Emission Rates 1-5
1.1.7 Miscellaneous Changes 1-6
1.2 Summary of Impacts of Promulgated Action 1-6
1.2.1 Environmental Impacts of Promulgated Action 1-6
1.2.2 Energy and Economic Impacts of Promulgated
Action 1_6
1.2.3 Other Considerations 1-7
1.3 Summary of Public Comments 1-7
2.0 BASIS FOR THE STANDARDS 2-1
2.1 Coverage of Processes 2-1
2.2 Definition of Affected Facility 2-5
2.3 Model Plant Descriptions 2-21
2.4 Selection of Basis of the Proposed Standards 2-27
2.4.1 Model Plant Approach 2-27
2.4.2 Polystyrene Processes 2-30
2.4.3 Polyethylene terephthalate) Processes 2-37
2.5 Presentation of the Standards 2-39
2.6 Appropriateness and Applicability of Proposed
Standards to Current Polymer Production Processes 2-40
2.6.1 Dilute VOC Streams 2-40
2.6.2 Low Flow Streams 2-50
2.6.3 Polyolefin Plants 2-55
2.6.4 Polystyrene Plants 2-60
2.6.5 Threshold Levels 2-62
2.6.6 Emergency Vent Stream Exemption 2-66
3.0 CONTROL TECHNOLOGY - PROCESS EMISSIONS 3-1
3.1 General •» -,
3.2 Flares 3.7
3.3 Intermittent Emissions 3-12
3.4 Condensers 3_jg
3.5 Polyethylene terephthalate) Facilities 3-22
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TABLE OF CONTENTS (continued)
Chapter Page
4.0 CONTROL TECHNOLOGY - EQUIPMENT LEAKS 4-1
4.1 General 4-1
4.2 Assumptions and Effect on Emission Estimates 4-7
4.3 Cost Effectiveness 4-18
4.4 Applicability of Leak Definition 4-27
5.0 MODIFICATION/RECONSTRUCTION 5-1
6.0 MONITORING REQUIREMENTS 6-1
6.1 General 6-1
6.2 Need for Flow Monitors 6-3
6.3 Thermocouples and Flame Monitoring 6-8
6.4 Incinerators 6-11
6.5 Carbon Adsorbers 6-12
6.6 Costs 6-13
6.7 Modification/Reconstruction 6-14
7. a TEST METHODS AND PROCEDURES 7-1
7.1 General 7-1
7.2 Flares 7-2
7.3 Boilers 7-3
7.4 Condensers 7-3
8.0 ECONOMIC IMPACTS, COSTS, AND COST EFFECTIVENESS
CALCULATIONS . 8-1
8.1 Economic Impacts 8-1
8.2 Cost Impacts 8-3
9.0 REPORTING AND RECORDKEEPING REQUIREMENTS 9-1
9.1 General 9-1
9.2 Flow Rates 9-2
9.3 Pilot Light Flame 9-4
10.0 MISCELLANEOUS . 10-1
10.1 Definitions 10-1
10.2 Other 10-6
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TABLE OF CONTENTS (continued)
APPENDIX A Flow Diagrams Illustrating Procedures for Determining
Which Polypropylene and Polyethylene Emission Streams
Are to be Controlled
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LIST OF TABLES
Table Page
1-1 List of Commenters on Proposed Standards of Performance
for VOC Emissions from Polymer Manufacturing Plants 1-9
4-1 Comparison of LDAR Programs 4-14
4-2 Comparison of Emission Reduction for Various LDAR
Programs 4.15
4-3 Fugitive Emission Reduction for the Sources in Polymers
and Resins Model Plant 4-16
4-4 Fugitive VOC LDAR Program Costs 4-21
4-5 Comparison of LDAR Programs by Equipment Component 4-22
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1.0 SUMMARY
On September 30, 1987, the U.S. Environmental Protection Agency
(EPA) proposed standards of performance for volatile organic compound
(VOC) emissions from certain facilities located in polypropylene,
polyethylene, polystyrene, and polyethylene terephthalate) (PET)
manufacturing plants (52 FR 36678) under the authority of Section 111 of
the Clean Air Act. A second Federal Register notice was published on
January 10, 1989, (54 FR 890). The purpose of the second Federal
Register notice was to reopen the public comment period for purpose of
allowing public comment on a new approach for determining which process
emissions from polypropylene and polyethylene production would be
subject to the proposed standards.
Public comments were requested on the proposed standards as
presented in both Federal Register notices. There were 14 commenters on
the September 30, 1987, Federal Register notice and 11 commenters on the
January 10, 1989, Federal Register notice. All of the commenters were
either polymer manufacturers or trade associations representing polymer
manufacturers.
This summary of comments and EPA's responses to these comments
serve as the basis for the revisions made to the standards between
proposal and promulgation. The proposed standards from which revisions
are identified are those that reflect the September 30, 1987, Federal
footer n°t1ce and the January 10, 1989, Federal Register notice.
1.1 SUMMARY OF CHANGES SINCE PROPOSAL
The proposed standards, which reflect the combined proposed
standards presented in the two Federal Register notices, were revised as
a result of reviewing public comments. The primary changes were made in
the following areas:
• Definition of Intermittent Releases to be Controlled
• Monitoring Requirements of Vent Streams
• VOC Weight Percent Exemption
• Definition of Concurrently Constructed, Modified, and
Reconstructed Affected Facilities
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• Reduced Testing Program for PET Facilities
• Applicable Standard and Uncontrolled Threshold Emission Rates
for Polystyrene and Poly(ethylene terephthalate) Plants
1.1.1 Definition of Intermittent Releases to be Controlled
In the September 30, 1987, Federal Register notice, emergency vent
streams from certain polypropylene and polyethylene affected facilities
were proposed to be excluded from the control requirements for
intermittent emissions. Public comments were received that suggested
that this exemption be broadened to include other emergency releases
from other facilities. The EPA revised this exemption in the January
10, 1989, Federal Register notice. In the January 10, 1989, Federal
Register notice, the EPA proposed that decomposition emissions be
exempted and all other intermittent emissions, including those that
occur as a result of attempts to prevent decompositions, be controlled.
Commenters on this latter notice expressed strong concern that the
proposed control of certain intermittent streams under the definitions
presented would be cost ineffective, would present severe safety
problems, and could force certain plants or technologies out of
business. The commenters recommended that EPA reconsider which
Intermittent streams are to be controlled and indicated that the
September 30, 1987, proposed language was much closer to identifying
which intermittent streams are appropriate to control or not control.
The EPA has reexamined both Federal Register notices, the
information available on intermittent releases, and the nature and
causes of such releases. The EPA has carefully considered the
commenters' comments and concerns. The EPA agrees with the commenters
that the language in the September 30, 1987, Federal Register notice is
better at identifying the appropriate intermittent streams that are to
be controlled or exempted than the language in the January 30, 1989,
Federal Register notice. Therefore, the rule for determining which
intermittent emissions are to be controlled as presented in the January
10, 1989, Federal Register notice has been revised for the promulgated
standard. The revisions extend the exemption for decompositions to
other emergency type intermittent emissions. For additional information
and details, please refer to Section 2.6.6, Emergency Vent Stream
Exemption, in Chapter 2.
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1.1.2 Monitoring of Vent Streams
In the proposed standards, flow indicators were proposed to be
inserted in each vent stream going to a control device to monitor the
presence of flow. This requirement was intended to ensure that the vent
stream was ducted to the control device. This requirement has changed
in the standard. To ensure that a vent stream is ducted to a control
device, the standard requires the submittal of a detailed engineering
report depicting the piping used to vent the stream to a control device.
Any valves in the piping are to be car-sealed opened or closed, as
appropriate, for ensuring that the vent stream does not bypass the
control device. An owner or operator then elects to either: (1)
monitor the car-seals and valves on a regular basis and report any
changes in the position of the valves whenever they occur or (2) install
a flow indicator immediately downstream of each valve that when opened
would allow any portion of the vent stream to bypass the control and
vent to the atmosphere. Where flow indicators are installed, the
reporting of all times when flow is indicated is required. For
additional information and details, please refer to Section 6.2, Need
for Flow Monitors, in Chapter 6.
1.1.3 VOC Weight Percent Exemptinn
In the promulgated standard, all affected facilities may use the
Individual stream exemption that allows individual vent streams with a
VOC concentration of less than 0.1 weight percent VOC to be exempted
from control. Previously, this exemption was proposed for individual
vent streams from modified or reconstructed affected facilities only,
not for vent streams from new affected facilities. This change was
based on information supplied by the commenters and reconsideration by
EPA that there would be sufficient information available in any
situation to determine when an owner or operator is intentionally
diluting a vent stream so as to take advantage of this exemption. For
additional information and details, please refer to Section 2.6.1,
Dilute VOC Streams, in Chapter 2.
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1.1.4 Definition of Concurrently Constructed. Modified, and
Reconstructed Affected Facilities
In the January 10, 1989, Federal Register notice, it was proposed
that affected facilities that are constructed, modified, or
reconstructed within a specified period of time of each other be
considered "concurrent." By considering such facilities as concurrent
the continuous process emissions within the same, weight percent range
from all such concurrently constructed, modified, or reconstructed
affected facilities would be added together and the control/no control
determination under the new approach would then be made. In the
promulgated standard, the EPA has deleted the term "concurrent", but has
retained and expanded its concept. Under the promulgated standard, a
vent stream from an affected facility in a polypropylene or polyethylene
plant would always be subject to potential- control regardless of when
the next affected facility was constructed, modified, or reconstructed.
Once controlled to meet the standard, a vent stream would not be
considered again in the control/no control decision for other vent
streams. The EPA feels this procedure accurately reflects the new
approach's generic decision making process that is dependent on vent
stream VOC concentration and annual emissions, but not on when a vent
stream becomes subject to these standards. For additional information
and details, please refer to Section 10.1, Definitions, in Chapter 10.
1.1.5 Reduced Testing Program for PET Facilities
Where steam-jet ejectors are used to provide vacuum to the
polymerization reaction section at PET plants, the proposed standards
required daily testing of ethylene glycol concentrations in either the
cooling water of the cooling tower that provides cooling water to the
vacuum systems servicing the polymerization reactors or in the liquid
effluent exiting these vacuum systems. It is possible that some PET
plants may be operated in such a manner that the ethylene glycol
concentration would remain sufficiently below the standard (0.35 or 6.0
weight percent of ethylene glycol) so that daily testing is not
necessary to ensure that the standard is met. Therefore, the
promulgated standard identifies the specific circumstances that are
required for an owner or operator to conduct a reduced testing program.
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In the promulgated rule, the reduced testing program requires one 14
consecutive day sample program (one sample per day) over a two-month
period. The final rule also allows an owner or operator to measure an
alternative parameter, such as chemical or biological oxygen demand,
provided that the measurement of such parameter allows the owner or
operator to demonstrate compliance with the ethylene glycol
concentration standard. These provisions are found in Section 60.564(j)
of the final rule.
1'1'6 Applicable Standards and Uncontrolled Threshold Emission Rates
Several commenters pointed out that the analysis for polystyrene
and PET plants failed to consider the potential presence of moisture
that could freeze up a condenser operating at the temperatures proposed.
The EPA reevaluated the condenser system and recosted the control to
determine whether the proposed standards and uncontrolled threshold
emission rates needed to be revised for material recovery sections in
polystyrene plants and PET plants. (For a discussion on the cost
reanalysis, please refer to pages 2-32 to 2-37 in Chapter 2.)
The results of this analysis resulted in a final standard of
0.0036 kilograms of total organic compounds (minus methane and ethane)
per megagram of product (kg TOC/Mg product) for the material recovery
section from polystyrene plants or a maximum outlet gas temperature from
the final condenser of -25 degrees Celsius(°C) [-13 degrees Fahrenheit
(°F)]. These values are the same as those that were proposed. The
final standard for the material recovery section from a PET facility
using a dimethyl terephthalate (DMT) process is 0.018 kg TOC/Mg product,
which is an increase from the proposed standard of 0.0027 kg TOC/Mg
product. The corresponding maximum outlet gas temperature also
increased, from -24°C (-1TF) to +3°C (+37°F).
As a result of the new analysis, the uncontrolled threshold
emission rates for material recovery section from both types of plants
also increased. The uncontrolled threshold emission rate is 0.05 kg
TOC/Mg product for the material recovery section in a polystyrene plant
and 0.12 kg TOC/Mg product for the material recovery section in a PET
plant using a DMT process.
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1.1.7 Miscellaneous Changes
Several change were made to the calculated threshold emission
(CTE) equations presented in the January 10, 1989, Federal Register
notice. These changes reflect changes in the costing for catalytic
incinerators and flares. In addition, several definitions have been
revised. The process section definitions were revised to provide
clearer guidance on the placement of equipment in each process section.
The definition to polypropylene was also clarified by including the term
"thermoplastic."
One change was made to the application of Subpart VV to polymer
manufacturing plants since proposal. Since proposal, it was learned
that certain polymer pumps are designed to purge polymer fluid from
bleed ports, thereby allowing small quantities of VOC emissions to
escape to the atmosphere. These pumps must use the polymer fluid to
provide lubrication and/or cooling of the pump shaft. The EPA believes
that the bleed ports from such pumps should be covered by Subpart VV if
they meet the definition of a leak based on an instrument reading of
10,000 parts per million or greater, but should not be covered based on
Indications of liquids dripping from the pump seal (as that definition
of a leak would otherwise be applied to the bleed ports). Therefore,
the final rule contains a limited exemption for the bleed ports from
these types of pumps.
1.2 SUMMARY OF IMPACTS OF PROMULGATED ACTION
1.2.1 Environmental Impacts of Promulgated Action
Environmental impacts of the proposed standards were described in
the September 30, 1987, Federal Register notice and in the January 10,
1989, Federal Register notice. The revisions to the proposed standards
will have a minimal effect on the environmental impacts of the
standards.
1.2.2 Energy and Economic Impacts of Promulgated Action
The energy and economic impacts of the standards are described in
Chapters 7, 8, and 9 of the proposal background information document
(BID Vol. I). The changes made in the standards since proposal have
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essentially no effect on the energy impacts. In addition, the costs and
economic impacts for these standards have changed slightly since
proposal. Capital costs have increased for polystyrene and PET plants.
This reflects revised condenser costs. Annual costs were also revised
to reflect revised unit price costs for natural gas and electricity.
The net effect of these changes is marginal. Total nationwide capital
costs in the fifth year following the promulgation of these standards
from all four polymers is estimated to be approximately $4.3 to $4.5
million (compared to $4.5 million at proposal) and annual costs to be
approximately $1.3 million (down from $1.4 million at proposal).
The economic impacts of the promulgated standards are estimated to
be essentially the same as for the proposed standards. Adverse economic
impacts would be minor.
1-2.3 Other Considerations
1-2.3.1 Irreversible and Irretrievable Commitment of Resources.
Section 7.5.2 of the BID for the proposed standards (Docket Item III-B-1)
concludes that the standards will not result in any irreversible or
irretrievable commitment of resources. It was also concluded that the
standards should help to save resources due to the energy savings
associated with the reduction in emissions. These conclusions remain
unchanged since proposal.
1-2.3.2 Environmental and Energy Impacts of Delayed Standards.
Delay in implementation of these standards would adversely affect air
quality. Lost emission reductions for each year the standards are
delayed are estimated to be approximately 600 megagrams per year
(Mg/yr). No adverse solid waste, water pollution, or energy impacts are
expected from delaying regulatory actions.
1.3 SUMMARY OF PUBLIC COMMENTS
Letters were received from 14 correspondents commenting on the
September 30, 1987, Federal Register notice and from 11 correspondents
commenting on the January 10, 1989, Federal Register notice. A public
hearing was requested on the September 30, 1987, notice, but not on the
January 10, 1989, notice. A list of commenters, their affiliations, and
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the EPA docket numbers assigned to their correspondence are given in
Table 1-1 of this document.
This document presents comments pertaining to the preamble and
regulation resulting from the proposed standards. The comments from
interested parties and EPA's responses to those comments have been
categorized, and they are presented under the following topics:
• Basis for the Standards (Chapter 2)
• Control Technology - Process Emissions (Chapter 3)
• Control Technology - Equipment Leaks (Chapter 4)
• Modification/Reconstruction (Chapter 5)
• Monitoring Requirements (Chapter 6)
• Test Methods and Procedures (Chapter 7)
• Economic Impacts, Costs, and Cost Effectiveness Calculations
(Chapter 8)
• Reporting and Recordkeeping Requirements (Chapter 9)
• Miscellaneous (Chapter 10)
The procedure for determining which process emissions from
polypropylene and polyethylene affected facilities are to be controlled
is relatively complex. Appendix A presents several flow diagrams to
assist the reader in understanding this procedure. The flow diagrams do
not contain all of the details associated with the procedure. Thus, the
reader should refer to the final rule for additional details.
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TABLE 1-1. LIST OF COMMENTERS ON PROPOSED
STANDARDS OF PERFORMANCE FOR VOC EMISSIONS
FROM POLYMER MANUFACTURING PLANTS
Commenter and Affiliation Docket Item No.
L.G. Lund IV-D-1
HIMONT U.S.A., Inc. IV-D-40
PO Box 1687
Lake Charles, LA 70602
L.J. Tabary, II IV-D-2
Copolymer Rubber and Chemical Corp.
PO Box 2591
Baton Rouge, LA 70821
W.C. Dedeke IV-D-3
Union Carbide Corporation IV-D-42
222 Pennbright Drive, Suite 109
Houston, TX 77090
R.R. Kienle IV-D-4
Shell Oil Company IV-D-48
One Shell Plaza
PO Box 2463
Houston, TX 77001
B.F. Ballard IV-D-5
Phillips Petroleum Company IV-D-39
Bartlesville, OK 74004
P.P. Cash IV-D-6
Mobil Chemical Corp. IV-D-44
211 College Road East
Princeton Forrestal Center
Princeton, NJ 08540
6.E. Matula IV_0 7
Texas Chemical Council
1000 Brazos, Suite 200
Austin, TX 78701
G.V. Cox IV-D-8
Chemical Manufacturers Assoc. TV-n-
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TABLE 1-1. Concluded
Commenter and Affiliation Docket Item No.
C.M. Moffitt IV-D-10
Cain Chemical
Eleven Greenway Plaza
Suite 2700
Houston, TX 77046
A.T. Roy IV-D-11
Allied Fibers IV-D-41
PO Box 831
Hopewell, VA 23860
P. Meitner IV-D-12
E.I. duPont de Nemours & Co.
DuPont Building, Room 70ISA
Wilmington, DE 19898
J.C. Edwards IV-D-13
Eastman Kodak Co. IV-D-47
Kingsport, TN 37662
W.E. Tessmer IV-D-14
International Institute of Synthetic
Rubber Producers, Inc.
2077 South Gessner Road
Suite 133
Houston, TX 77063
C.T. Gonzales JV-D-46
Exxon Chemical Americas
PO Box 1607
Baton Rouge, LA 70821
S.J. Roadcap IV-D-49
Chevron Chemical Co.
PO Box 5047
San Ramon, CA 94583
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2.0 BASIS FOR THE STANDARDS
2.1 COVERAGE OF PROCESSES
Comment:
Two commenters (IV-D-2, IV-D-14) were concerned over EPA's
definition of polypropylene (PP), in which copolymers containing at
least 50 percent propylene would be covered under the standard as
proposed. Commenter IV-D-2 requested EPA to reevaluate the statement
that as long as the proportion of propylene used in the production of
polypropylene copolymers is at least 50 percent by weight in the
copolymer product, the production processes used to manufacture both the
polymer and the copolymer are essentially the same. This commenter felt
this assumption and the resulting definition of polypropylene would
include inappropriately their copolymer production facilities that
produced ethylene-propylene terpolymers rubber products, which are
considered "elastomers" under industry definitions.
Commenter IV-D-14 stated that several of their member companies
produce synthetic rubbers, which contain ethylene/propylene/diene
monomers (EDPM) in the range 50-75/25-50/0-12, using processes entirely
unlike those used for production of plastics composed of polyethylene,
polypropylene, polystyrene or polybis(2-hydroxyethyl)terephthalate. The
commenter noted that the presence of the diene monomer at low levels and
the mixing of the ethylene and propylene units in the polymer molecule
result in physical characteristics which are clearly those of a rubber
rather than a "thermoplastic." Technically, the EPDM products are well
above their glass transitions at normal service temperatures, and they
have a very low fraction of crystallinity at all temperature ranges
relative to polyethylene and polypropylene. The commenter pointed out
that none of their member companies' EPDM production .facilities were
included in the surveys conducted by EPA prior to proposal of these
rules. In view of the major differences between the polymerization and
finishing operations of the EPDM rubber plants and those of the
thermoplastic resin plants, this commenter requested that the proposed
standards for polyethylene and polypropylene apply to certain sources in
polymer manufacturing plants that produce copolymers consisting of at
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least 80 percent (rather than 50 percent) by weight of ethylene or
propylene, respectively.
Response:
The intent of these standards is to apply to certain thermoplastic
or thermoset resins. The Agency agrees that the definition of
polypropylene in the September 30, 1987, Federal Register notice would
have subjected certain elastomer and synthetic rubber producers to these
standards, because the definition did not contain the clarifying term
"thermoplastic". Therefore, the Agency has revised the definition of
polypropylene to include the term "thermoplastic."
One commenter suggested that the definition of polypropylene and
polyethylene copolymers be revised so as to require at least 80% by
weight of propylene and ethylene, respectively, before being subject to
the standards. This suggestion was made to ensure exclusion of member
synthetic rubber companies. The Agency does not believe that such a
revision is necessary because the definitions refer to thermoplastic
resins, which are not rubbers, and thus synthetic rubber producers are
already excluded.
Comment:
One commenter (IV-D-2) requested that their company be exempted
from the effects of the proposed regulation until further studies are
performed on synthetic rubber producers. This commenter felt that the
current regulation would cover their facilities, which produce products
and polymers more appropriately covered under a synthetic rubber or
rubber manufacturing industry standard, not under the currently proposed
polymer manufacturing standards. This commenter stated that the intent
of these regulations is to cover thermoplastics and their manufacturers,
and that there appears to be a lack of documentation evidencing studies
of the processes of rubber manufacturers in the Agency's published
'documentation. The commenter also noted several differences between
their processes and those described in BID Vol. I for polypropylene
production, and claimed that their processes produced a relatively small
amount of discharge and emitted certain emissions not conducive to
flaring. Thus, this commenter concluded that given, in their view, the
relatively small amount of discharge combined with the deficiency of
information relative to the synthetic rubber manufacturing industry, any
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regulation of their facilities without a more comprehensive study that
includes the specific nature of design and manufacture of synthetic
rubber producers is premature and could harm any further expansion
projects now under consideration.
Response:
The intent of these standards is to cover certain producers of
thermoplastic or thermoset resins and copolymers of these resins that
are in turn themselves thermoplastic or thermoset resins. The Agency
does not intend for these standards to cover synthetic rubber producers,
including manufacturers of thermoplastic or thermoset elastomers, such
as ethylene-propylene copolymers and terpolymers that are elastomers or
rubbers. Resins are thermoplastic or thermoset polymers that are
essentially synonymous with the term plastic. Elastomers are also
thermoplastic or thermoset polymers, but are capable of returning to
their initial form following deformation. The Agency believes that the
revision to the definition of polypropylene limits the scope of these
standards appropriately. Synthetic rubber and elastomer producers,
however, may still be regulated in the future under this standard or a
new standard should the Agency decide such regulation is warranted.
Comment!
One commenter (IV-D-1) stated that there are more alternative
polypropylene technologies than the two listed in BID Vol. I and in the
proposed regulations. This commenter assumed that the new source
performance standards (NSPS) should be applicable to all polypropylene
processes. The commenter then concluded that the NSPS should be amended
to include, at least, the "bulk (liquid-phase) polymerization
technology." The commenter stated that bulk plant technology, although
in principle a liquid-phase polymerization process, is unlike the
"traditional" slurry process and hence, conclusions drawn on the basis
of the "slurry process" do not apply directly to the bulk process.
Commenter IV-D-45 also noted that in order to determine
applicability dates for affected facilities (using Tables 1 and 2 of the
proposed regulation), one must still have a clear understanding of which
"production process" applies (the applicable model plant) and the
definition of "process section" (which equipment falls into which
process section), especially where plants have commenced construction,
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modifications, or reconstruction between the two proposed regulation
dates.
Response:
The commenter is correct in assuming that the standards proposed
in the September 30, 1987, Federal Register notice were to be applicable
to all polypropylene processes. At that time, the Agency understood
that all such processes could be described as either liquid phase or gas
phase processes and that the model plants described in BID Vol. I were
reasonable representations of those processes upon which to base
standards. Comments received on the September 30, 1987, Federal
Register notice, however, indicated that the polypropylene model plants
may not be adequate representations of all processes. As a result of
this and other comments, the Agency undertook an analysis to examine
alternative ways to determine which process emissions from polypropylene
(and polyethylene) plants should be controlled. The results of this
analysis were presented in a January 10, 1989, Federal Register notice
for public comment. The approach selected by the Agency and
Incorporated into the final rule is independent of the particular
process technology used to produce polypropylene or polyethylene. Thus,
the non-representativeness of the polypropylene, "liquid phase model
plant presented in BID Vol. I as it applies to the bulk process is no
longer a concern.
For polypropylene facilities that are constructed, modified, or
reconstructed after September 30, 1987, and on or before January 10,
1989, the owner or operator of such facilities must still determine
which process--!iquid phase or gas phase—his or her facility falls
under for purposes of determining the affected facilities. The final
rule requires an owner or operator to select one of the production
processes listed in Table 1 of the final rule to apply to his or her
facility (see Section £0.560(b)(l)(ii) of the final rule). The
determination of which emissions from these affected facilities would be
controlled is made using the new approach, which is independent of
process type, rather than the control/no control decisions that were
based on the model plant. However, an owner or operator can still use
the uncontrolled threshold emission rates proposed in the September 30,
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1987, Federal Register notice to exempt these affected facilities from
control, if he or she so elects.
2.2 DEFINITION OF AFFECTED FACILITY
Comment:
One commenter (IV-D-13) stated that the selection of process
sections as affected facilities results in unreasonable cost and gives
unfair trade advantage to patent holders of these processes which the
Agency selected as model plants. The commenter stated that the proposed
standards will require companies with existing polymer plants to divide
up their plants into process sections and process lines, creating a need
to develop expensive new accounting and recordkeeping methods and
procedures to determine if modifications occur. The commenter claimed
that the Agency recognized this problem in the preamble (52 FR 36682)
when evaluating whether the affected facility should be individual
process emission points, in "attempting to maintain records of which
process or equipment were subject to the standard ... . " The commenter
stated that plants are not designed, estimated, justified and built, and
cost centers are not usually set up by process sections. A large
polypropylene or polyethylene polymer plant may have as many as 10 to 15
affected facilities, according to the commenter, and over the course of
a year, many small changes may be made to these plants. To evaluate
whether a modification that has been made falls under the proposed
rules, the commenter stated that completely new accounting systems must
be developed and implemented. For existing polypropylene and poly-
ethylene plants, the commenter believes a more reasonable choice would
be to designate each process line as the affected facility. The com-
menter stated that a problem recognized by EPA concerning the choice of
process units, i.e., "a process line cannot be determined clearly ... ."
(52 FR 36683), is even more of a problem with the selection of process
section as the affected facility. Specifically, the commenter pointed
out, material recovery is being utilized more and more by the industry
as a means of reducing overall emissions. According to the commenter,
in the model plants studied by the Agency, material recovery occurred
primarily after the reaction section, while modern plants continue the
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recovery of raw materials throughout the process line, wherever it can
be done economically. The commenter concluded that the standards need
to be revised to a process line concept.
Response:
The main considerations in selecting the definition of affected
facility is the consideration of the application of best demonstrated
technology and the degree to which replacement equipment is brought
under the standards. As a result, narrower definitions are preferred.
This preference can be overcome if analysis concludes that a broader
designation would result in greater emission reductions or avoid
unreasonable impacts (i.e., costs, energy, or other environmental
impacts). The commenter's main point for changing the definition of
affected facility is the need by industry to develop and implement
completely new accounting systems to track costs for as many as 10 to 15
affected facilities in a large polypropylene or polyethylene plant. The
commenter also believes that defining process sections is even more
difficult than defining a process line and refers to changing practices
of material recovery in the industry.
The Agency disagrees with the commenter on both points. The
imposition of new regulations on the industry would likely require some
plants to develop new accounting systems to track modifications and
reconstructions whether the definition of affected facility is "process
section" or "process line." Furthermore, under either definition, the
owner or operator would still need to track all changes. The only
difference is the number of affected facilities that would be tracked.
On this issue, the commenter claims that 10 to 15 affected facilities is
too many. The Agency simply disagrees with this statement. The Agency
rejected designating each individual emission point as an affected
facility because a typical plant may have as many as 40 individual
process emission points; a large plant may have substantially more. In
terms of process sections, the commenter notes that a large plant may
have 10 to 15 process sections; a typical plant would likely have fewer.
The number of process lines at any plant will always be less than the
number of process sections; but, the Agency is not convinced that at
large plants 10 to 15 affected facilities is unreasonable.
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With regard to the second point, the commenter claims that the
definition of "process section" is even more of a problem than that of a
"process line." The Agency again disagrees. The example provided by
the commenter may not match the material recovery section of the model
plant, but that is irrelevant to the definition. The concept of
material recovery is the key aspect of identifying the material recovery
process section or material recovery process sections at a plant.
Further, the Agency identified a major conceptual problem with trying to
define a "process line," where equipment was shared between two
otherwise distinct process lines. The commenter offered no suggestions
as to how to deal with that problem.
In summary, the Agency finds no reason to change the definition of
affected facility for process emissions.
Comment:
'Several commenters (IV-D-43/IV-D-50, IV-D-45, IV-D-47) noted that
the current proposed regulation is based on identifying "process
sections" and continuous or intermittent emissions in "affected
facilities," and that identifying these process sections in affected
facilities requires making base assumptions that are critical for
consistent interpretation throughout the industry. Commenters IV-D-47
and IV-D-50 stated that plant technical and management personnel
continue to experience problems in discerning the specific requirements
of the proposed rules applicable to each process section and affected
facility. These commenters encouraged EPA to further clarify its
. definitions of "process section" and "affected facility" to ensure
proper compliance with the regulation.
Two other commenters (IV-D-8, IV-0-9) were concerned over
potential confusion that the definitions of the various process sections
may create in the placement of particular pieces of equipment.
Commenter IV-D-9 stated that the use of "process section" as the
definition, of affected facility may likely result in over or under.
regulation if a piece of equipment is misclassified as to the section it
belongs. Commenter IV-D-8 noted that, as currently defined, "Product
Finishing Section" means "the equipment that treats, shapes, or modifies
the polymer or resin to produce the finished end product of the
particular facility. Product finishing equipment may accomplish
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extruding, cooling and drying, blending, additives introduction, curing,
or annealing." The commenter pointed out that for many of the processes
covered by the regulation, the product finishing section should consist
of the extruder and the pelletizer. Equipment downstream of the
pelletizer includes check hoppers, blenders, and silos, which do not
"treat, shape, or modify the polymers." They are used to transfer
product for quality control, general operations, and shipping, and
according to the commenter should be a part of the product storage
section, since there is no intentional modification of the
characteristics of the polymer as specified in the "product storage
section" definition.
Both commenters noted that the use of the terms "blending" and
"blenders" can confuse the delineation of product finishing and product
storage section. In one of the commenter's process, check hoppers
collect polymer pellets as they leave the dryer and then blenders are
used to physically mix the pellets in order to obtain a homogeneous
mixture over time. This commenter points out' that these check hoppers
and blenders meet the definition of equipment in the product storage
section since there is "no intentional modification of the
characteristics of the polymer." However, the commenter argues, a
regulator could easily place the blenders under the product finishing
section because this section is defined as "equipment [that] may
accomplish extruding, cooling and drying, blending, additives
introduction, curing, or annealing." Both commenters note that
"blending" in this case is clearly the mixing of 2 or more compounds
(I.e. polymer and additives) in order to produce a product that has
different properties. Commenter IV-0-9 pointed out that if the
emissions from the product finishing section were subject to controls,
controlling these very dilute VOC streams (vents from blenders) would
not be practical or economical and believes there should be a way to
prevent this situati-on from occurring.
Both commenters suggested that this problem may be addressed by
adding a statement under the definition of product finishing which
states that "blending does not mean the physical mixing of polymer
pellets in order to obtain a homogeneous mixture over time." However,
Commenter IV-D-9 stated that this would eliminate their concern for
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their blenders, but still would not solve the overall concern of
potential over or under regulation of vents from equipment due to
misclassification of the equipment within a process section. Therefore,
the commenter urged the Agency to add a general provision to the
regulation that would allow a company to petition the Administrator to
show that controlling the emissions from a vent within an affected
process section is not technically feasible or not economical. Since
some form of incineration or carbon adsorption are typically the only
alternative controls available, the commenter suggested that a concept
like the Total Resources Effectiveness (TRE) index used in the proposed
SOCMI distillation NSPS would be appropriate as a test for cost
effectiveness, and would eliminate much of industry's concerns
associated with trying to delineate process sections.
Response:
The Agency agrees that some of the process section definitions
proposed could create some confusion as to where particular pieces of
equipment are placed. Therefore, in the definitions in the final rule,
the Agency has delineated more clearly where a process section ends and
another process section begins. In the specific example cited by the
commenters, the Agency agrees that the product finishing section ends
after the last piece of equipment that modifies the characteristic of
the polymer and that the physical mixing of the pellets to obtain a
homogenous mixture is not part of product finishing, provided such
equipment follows the last piece of equipment in the product finishing
section.
A commenter still felt that some "misclassification" may still
occur. The commenter appears to define "misclassification" in terms of
some streams being required to be controlled that are either not
technically feasible or that are uneconomical to do so. The new
approach for determining which process streams are to be controlled,
which was presented in the January 10, 1989, Federal Register notice, is
designed to take these items into consideration. All process sections
that become affected facilities either on, before, or after January 10,
1989, can use this approach and thereby exclude from control emissions
that are excluded from control when the new approach is applied.
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Comment:
One commenter (IV-D-5) stated that it is possible for equipment to
be designed to produce more than one of the polymers covered by the
proposed standards. The commenter pointed out that the preamble
indicates that merely switching production from one type of polymer to
another would not be classified as a "modification" as long as the
original equipment was designed to accommodate both products. The
commenter requested clarification as to which category of polymer
process (and thus standards) would be applicable to new facilities that
are designed to produce more than one polymer using the same process
equipment.
Response:
The situation described by the commenter had not been envisioned
by the Agency when the standards were proposed on September 30, 1987.
Where a new facility is constructed, modified, or recorvstructed after
January 10, 1989, the situation described by the commenter does not
exist because the same procedure is applied for determining control
regardless of whether a low density polyethylene (LDPE), high density
polyethylene (HOPE), or PP product is being produced. However, if a
facility is built after September 30, 1987, and cm or before January 10,
1989, the standards to be met could be different where that facility is
designed to produce more than one polymer (e.g., HOPE and LDPE) as
different process sections (and their emissions) were designated as
affected facilities depending upon whether HOPE or LDPE was being
produced. As presented in the January 10, 1989, Federal Register
notice, the new approach did not guide an operator- or owner in
determining which process sections are to be considered affected
facilities for those process sections constructed, modified, or
reconstructed before January 10, 1989, where two types of polymers
(e.g., LDPE and HOPE) are produced in the same equipment.
In addition, the uncontrolled threshold emission rate to be
applied in exempting from control emissions from an affected facility
differ depending on whether HOPE or LDPE is being produced. The
January 10, 1989, Federal Register notice allowed owners or operators
the option to exempt from control emissions that under the new approach
would require control but could be shown under the model plant approach
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to be exempt from control through the use of the uncontrolled threshold
emission rate exemption.
The Agency considered the following options to clarify which
process sections and uncontrolled threshold emission rates are to be
used where a facility is designed to produce more than one polymer using
the same process equipment:
Option 1. Apply each model plant's affected facilities and
uncontrolled threshold emission rates as each polymer
is produced.
Option 2a. Designate as affected facilities all process sections
(and the emissions) that are in either model plant and
use the most restrictive uncontrolled threshold
emission rate where there are more than one for a
process section.
Option 2b. Designate as affected facilities all process sections
(and the emissions) that are in either model plant and
use the least restrictive uncontrolled threshold
emission rate where there are more than one for a
process section.
Option 3a. Designate as affected facilities only those process
sections (and the emissions) that are common to both
model plants and use the most restrictive uncontrolled
threshold emission rate.
Option 3b. Designate as affected facilities only those process
section (and the emissions) that are common to both
model plant and use the least restrictive uncontrolled
threshold emission rate.
Option 4. Provide an applicability date for all "hybrid"
facilities of January 10, 1989.
Option 5. Have the owner/operator select one model plant (pre-
sumably the one that most closely matches the hybrid
facility) for the purpose of determining the affected
facilities with a September 30, 1987 applicability
date and use the uncontrolled threshold emission rates
for those process sections as identified in the
September 30, 1987 Federal Register notice.
Of these options, the Agency has selected Option 5. Option 1 could lead
to a process section being an affected facility on a "part time" basis,
which could lead to control devices being turned on and off depending on
which polymer is being produced. Further, it would be an inefficient
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use of control devices. For these reasons, the Agency rejected
Option 1.
Option 2 would be to identify as affected facilities all of the
process sections identified in the September 30,, 1987, Federal Register
notice as affected facilities for either polymer. Option 2 may be
overly broad in that more process sections are identified as affected
facilities than would have been identified if the facility of concern
had been specifically examined. While the Agency feels that the new
approach would not result the control of inappropriate streams, and each
affected facility could still be exempted from control by using the
uncontrolled threshold emission rate cutoff for that process section,
the Agency feels this option may treat owners or operators of such
facilities unequally compared to others.
Option 3 would be to identify those process sections as affected
facilities on the basis of being identified as affected facilities for
both types of polymers. The Agency feels that this approach is
unnecessarily restrictive in that it potentially excludes from control
emissions from process sections that would have been identified as
affected facilities had the facility of concern been specifically
examined.
Further, under both Options 2 and 3, the threshold emission rate
to be applied would need to be determined where two rates have been
identified for the same process section. Should the higher of the two
rates be used or the lower? Without specific data on each such
facility, the Agency has no technical basis for selecting one or the
other.
Option 4 essentially sidesteps the issue by allowing all such
facilities to have a January 10, 1989, applicability date. The Agency
does not believe this is necessary. Option 5 allows the owner to most
closely match one of the model plants to his or her facility. This
incorporates a'Concept from a similar comment where a modified HOPE,
solution process now produces LDPE, but the emission characteristics
remain similar to when HOPE was being produced. Thus, the Agency has
selected Option 5 (see Section 60.560(i) of the final rule).
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Comment:
One commenter (IV-D-6) requested clarification on what equipment
is to be included in the material recovery section for a continuous
process polystyrene unit. The commenter pointed out that "material
recovery section" is defined as equipment which recovers unreacted or
by-product material from any process section; "process sections" are
defined such that product finishing is separate from material recovery;
and "recovery system" is defined as units such as condensers...which are
recovering VOCs. From this, the commenter concluded that the affected
facility of a polystyrene unit under this regulation would only include
the condensers and associated equipment for cooling and recovery, and
would specifically not include the devolatilizer or preheater, which is
part of the process for product purification.
Response:
As noted in an earlier response, the Agency has clarified more
specifically the definitions of the process sections to determine which
process equipment falls into which process section. With regard to the
particular equipment referred to by this commenter, the deyolatilizer
was specifically shown in BID Vol. I as part of the material recovery
section. Although the preheater was not specifically shown in BID Vol.
I, 1t Is associated with the equipment used to "purify" the product.
None of the process sections specifically includes the concept of
"product purification." Therefore, such equipment needs to be allocated
either to a material recovery section or to product finishing. In the
polystyrene industry, the recovery of unreacted styrene is such a
critical part of the economic aspects of the process that equipment used
to separate the unreacted styrene from the product through the final
recovery of the styrene were considered part of the material recovery
process section. Thus, in this case, the devolatilizer and preheater
would be part of the material recovery section. For other processes,
where no material recovery is practiced after the polymerization
reactor, equipment that, in a sense, prepares the product for product
finishing (e.g., removes unreacted or byproduct material from the
polymer produce) would be included in the product finishing process
section.
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Comment:
One commenter (IV-D-6) requested that vapor recovery systems
servicing emergency vents in continuous polystyrene plants be excluded
from the definition of material recovery section. The commenter pointed
out that some of their facilities have emergency vent vapor recovery
systems (add-on pollution control facilities) which attempt to reduce
these intermittent emissions by spray water contact. For other design
reasons, the continuous vent from the material recovery system serving
the process devolatilizer is also passed through the same system. There
can also be material recovered from the surge vessels in this system,
although most of the material recovered will likely be from emergency
vents. The commenter then stated that a strict interpretation of the
definition of material recovery section might subject emergency vapor
recovery units of this type to the performance standards. The commenter
claimed that this would not be technically or economically feasible due
to the very large gas volumes and peak rates intermittently incurred.
Response:
The standards for polystyrene facilities apply only to continuous
emissions and not to intermittent vents. The emergency vapor recovery
systems described by the commenter are not part of the material recovery
process section considered in the analysis as they are designed
primarily to control intermittent vents that occur due to
overpressurization of process vessels relieving through rupture disks.
Such systems and the intermittent emissions that are emitted to them are
not subject to these standards. However, continuous vents from the
material recovery system, which includes the process devolatilizer, are
subject to these standards, regardless of whether or not they pass
through an emergency vapor recovery system. For new facilities, it is
up to the owner or operator to decide on whether or not to route such
streams through emergency vapor recovery systems. For existing
facilities, the Agency has determined that where such continuous
emissions are routed through an existing emergency vapor recovery
system, control to the standard level is required when the existing
emergency vapor recovery system undergoes modification, reconstruction,
or replacement. Of course, if such continuous emissions are below the
-------
uncontrolled threshold emission rate, then no additional control is
required.
Comment:
One commenter (IV-D-11) stated that the proposed regulation was
unclear as to which process section a second stage reactor would fall.
The commenter requested that the proposal be modified to clearly
indicate that second stage reactors in polyethylene wax manufacturing
facilities are to be considered a part of the "polymerization reaction
section" and not the "product finishing section." The commenter pointed
out that the model plant used as the basis of the proposed standard uses
a single fluidized bed reactor to trigger the desired chemical reaction.
The commenter noted, however, that at their polyethylene wax facility
one of the two methods used employs a second stage reactor in series
with the first reactor to produce a product that is emulsifiable in
water. The commenter states that in this process a portion of the
molten homopolymer from the initial reactor is diverted to the second
reactor where the polymer is oxidized under elevated temperature and
pressure. According to the commenter, the reaction causes a breakdown
of the molecule and the addition of functional polar groups including
carboxyls, alcohols, aldehydes and ketones, and the molten oxidized
material leaving the reactor is then sent to various finishing steps.
It is on this basis that the commenter recommends that second stage
reactors used to chemically modify the material it receives be
classified in the polymerization reaction section.
Response:
The Agency disagrees with the commenter. Information provided by
the commenter clearly indicates that there is no polymerization
occurring in the second stage reactor. Rather, the commenter clearly
indicates that the polymer undergoes a chemical reaction (oxidization)
and then proceeds to (other) product finishing steps. The oxidation in
the second stage reactor falls within the definition of "product
finishing." (This comment arose as a result of the September 30, 1987,
F^dera1 Register notice. The commenter was concerned that if this
reactor were considered part of the product finishing section, the cost
of control, based on which streams would require control under the
September 30, 1987, Federal Register, would be unreasonable. This
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concern arose, in part, because of"the model plant approach originally
used to develop these standards. Under the new approach, which was
presented in the January 10, 1989, Federal Register notice, the
determination of control/no control is based on generic emission stream
characteristics. This new approach covers the commenter's situation in
a more adequate manner and enables a more reasonable control/no control
decision to be made. As stated in their comments on the January 10,
1989, Federal Register notice (see Docket Item IV-D-41), the commenter
agreed that their concern has been alleviated.)
Comment:
One commenter (IV-0-6) stated that there are no intermittent (non-
emergency) vents from the product finishing and product storage process
sections in high pressure, low density polyethylene plants. The
commenter pointed out that continuous emissions from these two process
sections were not proposed for control. The commenter felt, therefore,
that these sections should not be considered as affected facilities.
Response:
The commenter made this comment in response to the September 30,
1987, Federal Register notice. In the January 10, 1989, Federal
Register notice, a new approach for determining which process emissions
from all polypropylene and polyethylene plants would be subject to
control. The new approach encompasses all emission streams and process
sections in these types of polymer plants as an integral part of the new
approach. It may be possible that certain processes do not have one
type of emissions from certain process sections or lack one of the basic
process sections. It is not the intent of the new approach to identify
such specific situations, thereby potentially limiting its
applicability, if not now, then in the future as processes change.
Therefore, the Agency has retained as designated affected facilities all
process sections and emissions from polypropylene and polyethylene
plants, as was presented in the January 10, 1989, Federal Register
notice.
Comment:
One commenter (IV-D-44) stated that the model plant approach,
contained in the September 30, 1987, proposal, excluded certain process
sections from being affected facilities for both continuous and
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intermittent emissions, and that the January 10, 1989 proposal appears
to provide an exemption for only facilities exempted by Table 1.
According to the commenter, it would be unfair to penalize projects
which commenced construction, modification, or reconstruction under this
September 30, 1987, guidance and on or before the January 10, 1989,
proposal, which were not designated as affected facilities in the
September 30, 1987 proposal. The commenter then stated that the Agency
recognized (54 FR 905) that certain emissions and process sections not
required to be controlled under the standards proposed on September 30,
1987, may be required to be controlled under the new approach and
therefore, the Agency proposed to resolve this potential compliance
problem by proposing a new applicability date (i.e., January 10, 1989)
for those facilities that would have been excluded under the original
proposal, but subject under the new approach. The commenter recommended
that the model plant approach (September 30, 1987, proposal) should be
the governing standard for polypropylene and polyethylene construction,
modification, reconstruction projects which can be shown to have
commenced after September 30, 1987, but on or before January 10, 1989.
Response:
The January 10, 1989, Federal Register notice does what the
commenter recommends in Table 2 of the regulation portion of that
notice. Table 2 lists all the emission and process sections that were
excluded as affected facilities in the September 30, 1987, notice and
applies a January 10, 1989, applicability date to the'se emissions and
process sections. Thus, as indicated in the January 10, 1989, Federal
Register notice and as provided for in the final rule, only those
process sections identified in the September 30, 1987, Federal Register
notice are affected facilities when constructed, modified, or
reconstructed after September 30, 1987, and on or before January 10,
1989, for the appropriate continuous or intermittent emissions. It
should be noted that the procedure for determining control or no control
of the emissions from these process sections is the "generic" or new
approach. The uncontrolled threshold emission rates proposed in the
September 30, 1987, Federal Register notice, however, can still be used
for these affected facilities, if an owner or operator so elects, to
exempt individual process sections from control.
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Comment:
One commenter (IV-D-40) stated that with the development of their
new processes since the model plant concept was first proposed several
years ago, the process sections may not always be a perfect match with
the old definitions, especially as regards the relative weight of VOC
emissions from corresponding sections. The commenter then noted that
from their point of view, they do not foresee any major difficulties in
applying the new "generic rules" to any of their existing processes, or
future modifications thereof.
Response:
The Agency agrees with the commenter that the emission
characteristics identified in BID Vol. I for the process sections in the
model plants may no longer be representative of all current stream
characteristics in the polypropylene and polyethylene segments. The new
approach for determining which process emissions are to be controlled
was designed to take this problem into account. The Agency still
believes that the five generic process sections identified under the
model plants remain a useful and representative way to describe the
industry and upon which to apply the standards.
Comment:
Two commenters (IV-D-44, IV-D-50) stated that the two columns
marked "continuous" and "intermittent" should be dropped from Table 2 of
the regulation portion in the January 10, 1989, Federal Register notice
because the definition of affected facility no longer differentiated
between continuous and intermittent sources. Commenter IV-D-50 stated
that they do not see the significance of the Table 2 designation of
continuous and intermittent sources in process sections. This commenter
noted as an example that Table 2 does not indicate a continuous emission
source in a material recovery section of a high density polyethylene
liquid phase slurry process. This commenter then asked: Does this mean
that if such sources should occur and meet all of the criteria which
would require control, that they would not actually require control
because Table 2 does not mark them as an affected facility?
Response:
The commenter is correct to state that for polypropylene and
polyethylene processes the affected facilities are the same for
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continuous and intermittent emissions. However, the distinction in
Table 2 of the regulation portion of the January 10, 1989, Federal
Register notice must be retained because it identifies those process
sections and emission combinations that have a January 10, 1989,
applicability date. This is necessary for affected facilities
constructed, modified, or reconstructed after September 30, 1987, and on
or before January 10, 1989. For example, if a new polypropylene, liquid
phase plant was constructed after September 30, 1987, and on or before
January 10, 1989, the plant would have two applicability dates for its
process sections: September 30, 1987, applicability date for the raw
materials preparation, polymerization reaction, material recovery, and
product finishing section for continuous emissions and the
polymerization reaction section for intermittent emissions; and a
January 10, 1989, applicability date for the- raw materials preparation,
material recovery, product finishing, and product storage process
sections for intermittent emissions, and the product storage process
section for continuous emissions. As explained in January 10, 1989,
Federal Register notice (54 FR 905), this distinction was necessary
because certain emissions and process sections not required to be
controlled under the standards proposed on September 30, 1987, may be
required to be controlled under the new approach. Thus, the Agency has
retained the distinction in the final rule. The Agency, however, has
replaced Table 2 from the January 10, 1989, Federal Register notice with
Section 60.560(b)(l)(i) and has revised the reference to Table 1. This
revision provides a clearer presentation of the appropriate
applicability dates.
Comment:
One commenter (IV-D-44) stated that the affected facilities
defined in Section 60.560 are not consistent with those shown in Table 2
of the regulation portion of the January 10, 1989, Federal Register
notice. The commenter stated that wording in the regulation lists
process sections as affected facilities, but Table 2 does not mark as
affected facilities some sections under continuous or intermittent.
Response:
Table 2 in the regulation portion of the January 10, 1989, Federal
identifies only those process sections and emissions that have
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a January 10, 1989, applicability date. All other process sections and
emissions are identified in Table 1 of that notice's regulation portion.
Together, these two tables identify all process sections and emissions
identified in Section 60.560 of the January 10, 1989, Federal Register
notice.
Comment:
One commenter (IV-D-40) referred to Table 2, Section 60.560(d) in
the January 10, 1989, Federal Register notice, which lists continuous
and intermittent emissions for the various process sections that will
become subject to control, and pointed out that in the category of poly-
propylene processes (liquid phase), "raw materials preparation" and
"material recovery" are not listed in the "continuous" column, although
In some of the newer processes these would be considered continuous
operations.
Response:
Polypropylene, liquid phase processes that have continuous emis-
sions from "raw materials preparation" and "material recovery" have an
applicability date of September 30, 1987. This was indicated in the
January 10, 1989, Federal Register notice by Section 60.560(b), which
said "any facility under paragraph (a) of this section which commences
construction, modification, or reconstruction after September 30, 1987,
is subject to the requirements of this subpart except as provided in
paragraphs (c) through (f) of this section," and by Table 1 of paragraph
(c). As noted in the above response, Table 2 lists those process sec-
tions and their emissions that have a January 10, 1989, applicability
date. Those process sections and emissions not shown in Table 2 are not
excluded from the standards, but have September 30, 1987, applicability
dates.
Comment:
Two commenters (IV-D-44, IV-D-50) stated that "raw materials
preparation" should be added to the list of process sections under "low
density polyethylene, low pressure process and high density poly-
ethylene, gas phase process" in Table 2 of the regulation portion of the
January 10, 1989, Federal Register notice. Commenter IV-D-50 also
stated that Table 2 does not indicate all continuous and intermittent
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emissions, and illustrated this statement by noting that no intermittent
emissions are shown from the LDPE, high pressure process.
Response:
Table 2 shows only those process sections that have a January 10,
1989, applicability date. The raw materials preparation section refer-
red to by the commenter was proposed for control in the September 30,
1987, Federal Register notice and, thus, has a September 30, 1987,
applicability date. Therefore, it would have been inappropriate to
include this process section in Table 2.
2.3 MODEL PLANT DESCRIPTIONS
Comments in this section express concern over the representa-
tiveness of the model plants presented in BID Vol. I to processes in
general and to individual plants specifically. Commenters pointed to
emission streams that may have been overlooked and to process changes
that affect emission characteristics.
Comment:
One commenter (IV-D-8) stated that the generic model plants,
proposed on September 30, 1987, do not represent plants using non-
olefinic comonomers at a wide range of concentrations. The commenter
stated that there has been a proliferation of plants using non-olefinic
comonomers and VOC emission controls for these copoVymer plants must be
tailored individually. In a follow-up exchange, this commenter
indicated that copolymers of organic acids and ethylene produce emission
streams of varying concentrations of the non-olefinic comonomers and
that these comonomers may damage certain conventional control equipment
or may not be abated by it at all.
Response:
In response to this comment, the Agency requested specific
emission stream information from the commenter that would allow specific
identification of "problem" streams and allow analysis of such streams
(see Docket Item IV-C-20). The response by the commenter (see Docket
Item IV-D-35) was general in nature and did not provide the specific
information needed to determine if special consideration beyond the
generic approach was warranted. Based on the information that was
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provided, the Agency believes the generic approach provides reasonable
control/no control decisions in all instances, and therefore has not
modified the rule in response to this particular comment.
Comment;
One commenter (IV-D-1) stated that both bulk processes and gas
phase processes used in the manufacture of polypropylene generate a
purge stream to rid the process of non-reactive impurities, and that
other "controlled" releases from the process may be combined with this
purge stream. The commenter pointed out that common practice is to
subject the purge stream to "resource recovery" •• either through direct
recovery for reuse of its components or through combustion for heat
recovery. The commenter then stated that this stream may qualify for
inclusion in the "regulatory baseline" on the basis of the definitions
used.
Response:
The Agency has decided not to revise the model plant descriptions
for polypropylene plants to incorporate this purge stream. The approach
for determining which process emissions from polypropylene plants are to
be controlled does not require this revision. For affected facilities
that are constructed, modified, or reconstructed after September 30,
1987, and before January 10, 1989, the control/no control decision is
based on the "new" approach that was presented in the January 10, 1989,
Federal Register notice. Such affected facilities may be still exempted
from control based upon the uncontrolled threshold emission rates
presented in the September 30, 1987, Federal Register notice. This was
allowed to prevent an owner or operator from being placed in a position
of having not controlled emissions based upon the September 30, 1987,
proposed standards that would now require control if the new approach
was applied. An explicit consideration of this purge stream by the
Agency at this time would not have any effect on the control/no control
decision for emissions from the affected facility.
Comment:
One commenter (IV-D-7) stated that, in many cases, the model
plants used to develop this standard do not adequately reflect current
operation of manufacturing plants. The commenter then referred to the
model plant for LOPE based on the UNIPOL process. The commenter noted
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that the model plant did not consider the modified UNIPOL process that
has a pellitizer section added and the linear LDPE solution process.
The commenter stated that emission characteristics differ significantly
from the model plant, but are controlled the same. The commenter then
stated that the gas phase process for polypropylene failed to consider
emergency atmospheric vents that are used on newer plants. Therefore,
the commenter suggests that these model plants be reviewed to ensure
that they are representative of operating plants throughout the
industry.
Response:
The Agency understands and agrees with the commenter's concern.
As a result of concerns such as this, the Agency developed a new
approach for determining which process emissions from polypropylene and
polyethylene plants would be controlled and presented this approach in a
January 10, 1989, Federal Register notice. The new approach does away
with the need to define model plants and the Agency determined it was
unnecessary to revise the model plants.
Comment!
Two commenters (IV-D-6, IV-D-8) stated that there are several
aspects of the fluid bed gas phase polyethylene process model plant
(used to describe the LDPE low pressure and HOPE gas phase processes)
that do not reflect actual current operations. These discrepancies (and
the changes suggested by Commenter IV-D-8) are identified below.
1. The process model does not include a polymer finishing section
which was consistent with the early expectations of this
process. However, the process evolution over the past seven
years has grown to include a Finishing, Extrusion, and
Blending section in essentially all plants of this type. This
important aspect of the process should be included to ensure
clarity. It is important to note that this finishing section
will continue to have the Vent "J" shown on the diagram. This
is typically a bin vent and will contain residual VOCs in a
very dilute air stream. The revisions shown in Table 3
reflect this change and shows a typical range of emission
rates with operations on HOPE and LDPE.
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Commenter IV-D-6 noted that this section takes the
granular product from storage bins (vent "J" in BID Vol. I)
and treats, shapes and modifies the polymer to the finished
palletized and product, and that there should be no
incremental emissions generated by this additional material
handling facility.
There are several changes that are required to correct the
stream "I" (Product Discharge Vent) in Table 3-9 of BID Vol. I
to reflect actual operations and to ensure clarity: (a) This
stream should be correctly indicated as intermittent in
nature; (b) This'stream has been incorrectly included in the
Process Finishing Section of the plant for process evaluation.
It is actually part of a Material Recovery section according
to the definitions included in the proposed rule, and that
process section definition should be corrected; and (c) The
magnitude of the emission rate assumed for vent stream "I" in
Table 3-9 appears to also include the recycle from the Product
Discharge system back to the Reactor system, which is not
consistent with actual operations. For clarity this emission
rate should be adjusted to reflect typical rates.
This commenter also noted that footnote "d" is the vent
stream summary in Table 3-9 in BID Vol. I incorrectly
indicates that stream "I" is not routed to a flare as part of
baseline control. This should be changed to reflect typical
plant operations.
Commenter IV-D-6 noted that Vent "I" from the Polymer
Discharge Tank, which is described as a continuous vent in the
Product Finishing section, does not exist on its own but is
routed through the Polymer Purge Tank, which is in the
Polymerization Reaction Section, and is combined with vent
"H". Also, this commenter stated that the Polymer Discharge
Tank, which was classified in BID Vol. I as product finishing,
should be part of the Polymerization Reaction Section.
Stream "H" in the process shown in Figure 3-5 of BID Vol. I
also requires several changes to reflect actual operations
according to Commenter IV-D-8: (a) A more correct name is
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"Polymer Purge Vent", rather than "Reactor Purge Vent", to be
consistent with the equipment name shown on the diagram in
Figure 3-5 of BID Vol. I; (b) This purge stream is continuous
in plant operations rather than the intermittent nature
indicated in Table 3-9 of BID Vol. I; (c) The process section
for this stream should be "Material Recovery", not
"Polymerization Reaction" as indicated in Table 3-9 of BID
Vol. I. This classification would more closely fit the
definitions included in the proposed regulation (Subpart ODD)
for this type of operation; (d) The part of the process
emitting stream "H" has typically undergone optimization since
the initial process development and may now include raw
material recovery technologies for certain LDPE applications.
This important phase of emission reductions should be noted on
the process diagram; and (e) The magnitude of this material
recovery stream emission rate is highly dependent on the type
of polymer being produced, HOPE or LDPE, and the processing or
recovery equipment employed. These aspects result in a wide
range of emissions depending on the operations. A "typical"
range is between 5.0 and 20.0 kg VOC/Mg product.
Commenter IV-D-6 stated that vent "H" from the Polymer
Purge Tank, which is described as an intermittent vent in the
Polymerization Reaction Section, is a continuous vent in
current operations, and in general is routed to a flare. In
some cases, raw materials are recovered from vent "H" prior to
it being vented to a flare system.
Finally, Commenter IV-D-8 noted that the basic processing steps in
a fluid bed gas phase process are identical for HOPE and LDPE, with only
the finer operating parameters and emission levels being different. A
range of emissions was provided by the commenter for three of the eleven
streams, resulting in a total emission rate from the entire facility
ranging from 7.36 to 22.5 kg VOC/Mg product.
Response:
The aspects of the polyethylene process described by the
commenters as being "discrepancies" reflect changes that have occurred
to the process upon which the model plant was based. It was this type
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of comment, in part, that led the Agency to adopt the "new" approach for
determining which process emissions from polypropylene and polyethylene
plants are to be controlled rather than continuing to rely on model
plants that may change. The Agency has determined that it is
unnecessary to develop new model plants or to revise those that served
as the basis of the September 30, 1987, Federal Register notice; the new
approach takes such changes into account.
Comment:
One commenter (IV-D-8) referred to the characterization of
intermittent versus continuous streams. In their initial letter, the
commenter indicated that in polystyrene plants changing processes often
change flow streams from continuous in nature to intermittent as
recovery processes are applied to those streams.. A follow-up exchange
(see Docket Item IV-D-35) indicated that the commenter was referring not
to the emission stream changing from continuous to intermittent, but to
either higher or lower levels of emissions being released as a result of
changes in the conditions of the closed system or in the raw materials
to make a product change.
The commenter also stated that the Agency accounted for such items
as start up, shutdown and maintenance purges by grouping them as
"intermittent bin vent" emissions, and that these purges can come from
any area of the process. The commenter then stated that it is unlikely,
however, that purges would come from the product storage area itself.
With regard to bin vents, the commenter stated that it is generally
agreed that bin vents are continuous when the bin is in use and that
there are no emissions when the bin is not in use. Lastly, the
commenter stated that in actuality in LDPE and HOPE units, the
intermittent process emissions (startup - shutdown and maintenance and
process emissions) for safety reasons must be separated from product
storage bin units which normally contain oxygen (air) in control device
collection systems.
Response:
These comments are directed at making explicit certain aspects of
various polymer manufacturing practices that affect emission levels and
control. None of the specific comments require the Agency to revise the
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polystyrene model plants or the approach for determining which process
emissions from polyethylene processes are to be controlled.
2.4 SELECTION OF BASIS OF THE PROPOSED STANDARDS
2.4.1 Model Plant Approach
Comment:
One commenter (IV-D-8) stated that by using reaction mechanisms as
the models for developing the NSPS control requirements EPA has tailored
the rule to these particular patented processes and that this provides
an unfair advantage for both the licensors and licensees of those
technologies because the sale of licenses is due, in part, to the
ability of a process to comply with applicable environmental standards.
The commenter pointed to the low pressure linear low density
polyethylene (LLDPE) process as the best example. The commenter stated
that when the model plant for this process was developed, the only
process in use was a fluid bed gas phase facility licensed by a major
U.S. chemical company. Since that time, the commenter continues, both a
slurry and a solution process have been revised to produce the linear
low density product, and a new gas phase facility licensed by a major
British petrochemical company is currently under construction.
According to the commenter, these newer processes differ greatly from
the low pressure process that the Agency considers state-of-the-art.
The commenter notes that if the NSPS is promulgated as written, it will
require that similar new installations, as well as existing units that
are modified or reconstructed, be equipped with emission controls
designed specifically for the fluid bed gas phase facility. The
commenter suggests that the economic penalty resulting from this action
be considered before the regulation is finalized.
This commenter then suggested that it might be more appropriate
for EPA to establish control requirements based on the system pressure
and process type rather than the specific technology used because system
pressure (not reaction mechanism) is the primary factor influencing
emissions from polyolefin manufacturing facilities and will determine
the relative ease at which unreacted raw materials are removed from
reacted mixtures. The commenter also stated that system pressure will
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also be a factor in defining the process step from which the unreacted
raw material will be emitted, noting that the higher pressure processes
tend to hold on to the unreacted materials longer, thereby yielding
greater emissions in later process steps (i.e., product storage).
The commenter illustrated this suggestion by breaking the
polyethylene processes into two broad classes - high and low pressure.
Under the low pressure classification, the commenter indicated that
there are presently three commercial processes -- (1) gas phase, (2)
liquid slurry and (3) liquid solution. According to the commenter, each
of these processes in the newer and more recently modified plants has
the capability of manufacturing both HOPE and LDPE. Under the high
pressure classification, the commenter indicated that there are
presently two commercial processes -- (1) tubular and (2) autoclave
-both of which manufacture conventional LDPE.
The commenter pointed out that under the proposed regulation, if
these low pressure solution or slurry process plants manufacture LLDPE,
then they are grouped with the gas phase model plant, while if they
manufacture HOPE, they are grouped with either the HOPE solution model
or the HOPE slurry model. The problem or inconsistency with this
result, according to the commenter, is that from a product, process, and
emissions point of view, when a solution plant manufactures LLDPE it
actually more closely resembles the HOPE solution model and when a
slurry plant manufactures LLDPE, it more closely resembles the HOPE
slurry model than the gas phase model plant. Finally, the commenter
pointed out that the product finishing areas of modern solution and
slurry LDPE plants resemble the HOPE solution and HOPE slurry model
plants much more than they do the gas phase model plant.
Response:
The Agency took this comment under consideration and as a result
of extensive analysis presented a new "generic" approach for determining
which process emission streams from polypropylene and polyethylene
plants would be subject to control. The new approach effectively deals
with the commenter's concern for process sections that become affected
facilities either before, on, or after January 10, 1989.
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Comment:
One commenter (IV-D-8) stated that the Agency failed to consider
not only a "worst case" scenario in determining the economic impacts but
also failed to consider the "real case." The commenter referred to page
36691 in the September 30, 1987, Federal Register notice in which the
Agency states that its survey was based on "economic impacts associated
with a worst case growth distribution." The commenter referred to
Tables 4, 5, and 6, in Docket A-82-19, Item II-B-92, Calculations of
Average, or Typical. Cost Effectiveness Selected as the Basis for the
Proposed Standards and The Next More Stringent Regulatory Alternatives.
which show expected growth distribution by process section, process
line, and new plants and the costs associated with the proposed
standards and the next more stringent regulatory alternatives weighted
by the expected growth distribution. The commenter states that since
this analysis was projected from 1984 to 1988, it is now possible to '
check if the worst case was actually considered. The commenter claims
that during this time period, no new polyethylene and polypropylene
process lines or plants have been brought on line and, therefore, all
capacity increases have been the result of process section
modifications. Process sections were shown to have the highest cost of
the three mechanisms considered. Since EPA in their analysis did not
weight growth by process section, the growth with the highest costs
associated with it, as heavily as they did the growth by process line or
new plants, the commenter believes the true growth distribution would
have led the Agency to the conclusion that different regulatory control
alternatives should have been chosen.
Response:
The commenter has misunderstood the use of the projected growth
distribution in relationship to the selection of regulatory alternatives
as the basis of the proposed standards in the September- 30, 1987,
Federal Register notice. The regulatory alternatives selected as the
basis of the standards were done so, in part, based on the costs and
cost effectiveness values reported in Chapter 8 of BID Vol. I, and not
on the basis of the analysis in Docket Item II-B-92. The costs in
Chapter 8 reflect costs incurred on a per process section per process
line basis. For several of the model plants, the cost effectiveness of
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the selected alternative was felt to be somewhat high if control would
be implemented by a control device dedicated to that particular process
section. The Agency considered whether emissions from these process
sections might not be controlled in a less expensive manner. For these
process sections, the Agency concluded that the emissions to a common
control device or that modifications to multiple process sections of the
same type (e.g., product finishing sections) were more likely to occur
than to a single process section (e.g., one of three product finishing
sections). These conclusions were noted in footnote b to the
appropriate tables in Chapter 8 of BID Vol. I. Furthermore, the
economic impacts reported in Chapter 9 of BID Vol. I were based on the
costs found in Chapter 8 and not in Docket Item II-B-92. Thus, the
regulatory alternatives selected were based on consideration of the
worst-case scenario (control of individual process sections) as were the
economic impacts. The purpose of Docket Item II-B-92 was to obtain
(hopefully) a more realistic picture of the impact of the already-
selected regulatory alternatives on the industry as a whole over the
next five years. While it is now possible to check how accurate the
growth distribution projection was for that document, its accuracy is
not relevant as it pertains to the selection of regulatory alternatives.
2.4.2 Polystyrene Processes
Comment:
One commenter (IV-D-8) stated that the use of refrigeration
condensers are not technically feasible for polystyrene processes and do
not meet the criteria for standards of performance as stated in the BID:
"standards of performance must (1) realistically reflect best
demonstrated control practices; (2) adequately consider the cost, the
nonair quality, health and environmental impacts, and the energy
requirement of such control; (3) be applicable to existing sources that
are modified or reconstructed as well as new installations; and (4) meet
the conditions of all variations of operating conditions being
considered anywhere in the country."
The commenter wrote that the Agency is correct in stating in BID
Vol. I that condensers are cost effective for recovery of compounds with
relatively high boiling points like styrene and that a refrigerated
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condenser is not feasible when moisture is present in the stream which
might cause freezing in the condenser. The commenter then pointed out
that the latter holds true for continuous polystyrene processes.
The commenter then gave a number of reasons why freezing will
occur. First and most important, according to the commenter, is the
water in the vent. The commenter noted that the Agency assumed that
when plants switched from steam ejectors to vacuum pumps, the freezing
problem associated with water disappeared with the steam. However, the
commenter stated, there is water entering with the raw materials and
with the air leakage into the system (especially true in hot, humid
climates). The commenter pointed out that most of the water comes from
the water content of the styrene and the rubber used in the manufacture
of high impact polystyrene (HIPS). To illustrate the level of water
content, the commenter noted one company reported an average of 0.08
weight percent or 800 parts per million (ppm) water in the feed to the
process, while another company has measured 167, 453, and 284 ppm
moisture in styrene in three different months with a maximum of 700 ppm
(saturation).
According to the commenter, the rubber used in making HIPS
typically has 0.4 percent water in it, and since rubbers can make up 5
to 10 percent of the finished product, the overall water content in the
raw materials could be as high as 0.1 weight percent. The commenter
pointed out that while some water will be driven off through the heating
reactor and any water draws, saturated water vapor in the 30-50 ppm
range will remain in the devolatilizer vent stream and cause freezing
problems at the control temperature (-25°C) proposed in the regulation.
Another potential problem with using a refrigerated condenser,
according to the commenter, is the presence of additives in the process,
some of which have high freezing points. One company reports freezing
of the primary condensers coming off the devolatilizer when they ran the
condenser's glycol system at -2 to -4«C. Thus, if certain additives are
present, the freezing is more likely to take place.
Response:
After further investigation, the Agency agrees that freezing may
be a problem at sub-zero temperatures. Therefore, the Agency has
reanalyzed the regulatory alternatives for polystyrene plants using
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spared heat exchangers with defrost capabilities and a refrigeration
system for sub-zero applications. This reanalysis is presented in
Docket Item IV-B-18.
Comment:
One commenter (IV-D-6) stated that it is inappropriate to impose
compliance by an alternate indication technique (i.e., temperature
measurement).
Response:
The Agency disagrees with the commenter. The use of condensers to
control emissions allows for an essentially equivalent standard to be
set in terms of outlet gas temperature. The Agency is directed by the
Clean Air Act to set emission limits unless otherwise impracticable to
do so. The Agency set an emission standard of 0.0036 kg TOC/Mg product.
At the same time, the Agency saw an opportunity to provide for
equivalent emission control by limiting the temperature of the outlet
gas stream from the condenser. Temperature is a good indicator of
performance in this case because at a given outlet temperature the
concentration of styrene that can be vented is essentially the same
regardless of concentration of styrene entering the condenser. As a
temperature standard allows continuous compliance determinations to be
made and is much less costly for compliance testing, the Agency feels it
is entirely appropriate to set a temperature standard as an alternative
standard for condensers.
Comment:
Two commenters (IV-D-6, IV-D-8) expressed concern over the costs
basis used to select refrigerated condensers as the basis of the
proposed standards for polystyrene plants.
Commenter IV-D-8 stated that the Agency did not adequately
determine the costs and cost-effectiveness associated with using
refrigerated condensers in the polystyrene continuous process.
Specifically, this commenter made the following points:
1. The Agency did not account for the cost of removing any water
or additives that could freeze the condenser. This cost
clearly was not considered in the justification of the
refrigerated condenser since the Agency assumed there were no
high freezing point compounds present. Figure 4-6 on page
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4-28 of BID Vol. I shows the condensation system with a
dehumidification unit in it. However, no economics were done
on this control technology.
2. The Agency grossly understated the installed capital cost of
the condenser and the refrigeration unit for the regulatory
alternative chosen. A recent cost estimate was done by
contracting a vendor to determine the overall cost for the
condenser system specified in BID Vol. I. The installed cost
for the proposed system was $15,600. The commenter believes
this number represents a more accurate installed cost than the
$1,717 cost reported in BID Vol. I.
3. Because of present State regulations for VOC emissions from
polystyrene units and the desire of companies to lower the
content of unreacted styrene in the finished product, both new
and older plants have lowered their primary condenser
temperature to pull lower vacuum and remove (condense) more
styrene. The Agency used 27'C to determine the amount of
styrene saturated in the air going to the vacuum pump. The
temperature now runs around 5 to 10'C. Therefore, less
styrene is being emitted. This establishes a new baseline to
determine cost effectiveness that should be considered before
a final rule can be determined.
4. The Agency calculated a $3,000 credit for the styrene
recovered by the use of a refrigerated condenser. This
assumes the condensate is usable. One company has chilled
condensers (2-5'C) on the discharge of the vacuum pumps.
(They also run their primary condensers at the level stated in
point 3.) This condensate consists of dimers and trimers of
styrene and other heavy materials, and is not suitable to
return to the recycle tank. The condensate is disposed of by
incineration. The commenter believes that the Agency should
not allow a credit for material that cannot be reused. The
only credit should be for the British thermal unit (BTU)
content of the condensate when it is burned.
Commenter IV-D-6 stated the cost of the refrigeration condenser
system for the model plant in BID Vol. I appears to be totally
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unrealistic and grossly underestimated and the cost of the specified
technology to achieve the indicated reductions does not appear to
justify the additional control above 0.12 kg TOC/Mg product. The
commenter pointed out the following cost factors they felt might have
been overlooked:
1. moisture content of the stream would require drying systems;
2. poor heat transfer coefficients due to the high nitrogen and
noncondensible content of the stream;
3. explosion-proof requirements must be Class I division 2;
4. refrigeration system would be non-standard (probably
propylene) due to the temperature requirements;
5. higher metallurgy (stainless steel) required due to the low
temperature requirement; and
6. cost for new process condenser and associated piping appears
not to have been considered in development of the proposal.
Existing chilled water condensers are riot rated for this low
temperature application and refrigeration service. Therefore,
new process condensers would be required.
The commenter provided cost estimates for controlling two
different existing polystyrene plants and one new plant. The
commenter's cost estimates yielded cost effectiveness values of
approximately $24,000/Mg of VOC removed for the two existing facilities.
The plants and the cost basis used by the commenter were as follows.
The first existing plant was assumed to (1) have a production rate
of 75 million pounds per year, (2) emit 0.12 kg VOC/Mg product from
the material recovery section, (3) use chilled water condenser system,
and (4) achieve compliance with the 0.0036 kg TOC/Mg product standard by
installing a new (add-on) process condenser, refrigeration/condensing
system and associated piping. The capital cost for this equipment was
estimated at $125,000. This cost was based on equipment designed for
explosion proof (Class I division 2) installation, two refrigeration/
condenser package units to ensure and maintain unit operations due to
anticipated reliability and maintenance problems with the refrigeration
units, a vent stream design basis of 5 cubic feet per minute (cfm) at
140*F, 5 to 10 ton compressor units, and a propylene refrigeration
system. The commenter stated that a non-standard refrigeration (i.e.,
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propylene system) appears to be necessary due to the low temperature
requirements. The commenter also stated that a new process condenser
would be required since the existing chiller is not rated for low
temperature applications and refrigeration service. The cost breakdown
provided by the commenter was: $60,000 for two refrigeration (propylene)
chillers; $8,000 for new process condenser; $5,000 for associated
piping; $10,000 for industrial rated controls; $18,000 for labor for
installation; $5,000 for engineering and drafting; $4,000 for freight;
$5,000 for associated expense; and $10,000 for material and labor
contingencies.
The second existing facility was assumed to produce 120 million
pounds (Ibs) of HIPS and 360 million Ibs of general purpose polystyrene
and emit 0.025 Ibs of VOC per Mg of product. The commenter estimated
that it would cost $300,000 to install the required incremental
refrigeration/condensing system in order to comply with the proposed
standard.
For the new facility, the commenter stated that an engineering
contractor has estimated the incremental, costs associated with just
complying with these new provision to be $754,000.
On the basis of these comments regarding the cost and
cost-effectiveness of refrigerated condensers, as well as the
questionable viability of the technology due to the presence of water,
Commenter IV-D-8 stated that EPA must redetermine the best technology
system for polystyrene continuous processes.
Response:
The commenters have brought up a number of points concerning the
use of and cost estimates for refrigerated condensers on emission
streams from polystyrene plants using continuous processes. For the
response to these comments, the reader is referred to Docket Item
IV-B-18. The following summarizes the Agency's response to the
commenters concerns.
The Agency agrees that consideration of subzero condenser
applications requires dealing with moisture level. Based on
conversations with a number of vendors, the Agency has Devaluated
control below 32*F using a system composed of two heat exchangers each
equipped with a defrost unit and a refrigeration unit to service both
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heat exchangers. This system now incorporates stainless steel
construction. The system previously considered noncondensibles and thus
the Agency feels proper heat transfer coefficients have been used.
Vendor contacts indicated that ethylene glycol-water solutions and Freon
502 coolants would suffice; non-standard refrigerants would not be
needed. In addition, the explosion proof requirements, which refer to
electrical wiring requirements, have been directly considered. Based on
these assumptions, the Agency has recalculated the costs of the control
alternatives.
Based on the new costs, the Agency has calculated a total
Installed capital cost of between $8,600 and $9,900 (1980$)
(approximately $11,400 to $13,100 in 1989$) for a single and a spared
condenser system, respectively. While these costs are higher than the
cost the Agency estimated at proposal, they are still substantially
below those estimates provided by the commenter. The first example
provided by the commenter had a total installed capital cost of
$125,000. This estimate was based on replacing existing process
condensers with ones that would meet the standard. After discussions
with the commenter, it became clear that while this route can be used,
ft 1s unnecessary.
The commenter reestimated the installed capital cost of this
system to be $48,000. This is still much larger than the new estimate
by the Agency. The difference is due, in part, to the costing of a
condenser that is much larger than needed (60 square feet versus a
needed 10 square feet or less) and an "exotic" refrigeration system.
Based on information from a vendor for a system nearly identical to that
being considered by the commenter, purchase costs were between $7,000
and $12,000 (1989$), for an installed capital cost of between $9,700 and
$16,700 (using an EPA installation factor of 1.39) for a single and
spared condenser system, respectively.
The commenter's cost estimate for the second existing facility
included costs for an expensive water removal system. The Agency
believes this is unnecessary, that a spared condenser system, which is
much less expensive, will handle potential freezing problems that a
single condenser might encounter. Further, the costs for the
condensers/refrigeration units appear to be again based on units much
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larger than necessary to handle the emission stream during normal
operating conditions. Finally, the commenter's cost estimate for the
third facility is not an incremental cost estimate and, when asked for
additional details, the commenter requested that the Agency "ignore"
that cost estimate in their comments.
In summary, the Agency has carefully reevaluated the condenser
system necessary to meet the standards. These costs are higher than
originally estimated because of the technical, aspects identified by the
commenters. However, the cost estimates provided by the commenters
appear, based on the information provided, to be based on systems that
are much larger than needed, that in some instances use techniques that
are more expensive than other equally effective techniques, and may
still reflect unnecessary changes to existing process or recovery
equipment. Thus, the Agency believes its costs now reflect more
accurately the costs of condenser system that would be incurred if
designed specifically to meet these standards.
Commenter IV-0-8 suggested that the Agency establish a new
baseline to determine cost effectiveness before determining the final
rule. The Agency provides for an uncontrolled emission rate threshold
level that protects against non-cost effective control of facilities
referred to by the commenter. Therefore, the Agency has retained the
baseline as presented in BID Vol. I.
2.4.3 Polyethylene terephthalate) Processes
Comment:
One commenter (IV-D-13) stated that currently highly efficient
materials recovery process technology has greatly reduced the rate and
diluted the concentration of the affected vent stream so as to reduce
the value of the condensate and cause the installation and the operating
cost of refrigerated condensers to be unreasonable.
Response:
This commenter was referring to the lower quantity of methanol
being recovered in PET plants and thus the recovery credit would be
lower. The Agency has taken into account facilities that already
substantially reduce their methanol rate by the provision of an
uncontrolled threshold emission rate. Based upon this analysis, the
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Agency has determined that additional control using refrigerated
condensers is unreasonable if uncontrolled emission rates at existing
facilities are less than 0.12 kg TOC/Mg product, but that such control
is reasonable if the emission rate is higher.
Comment:
One commenter (IV-D-11) stated that the limit of 0.04 kg TOC/Mg
product from esterification vessels for high viscosity PET using
multiple end finishers (Section 60..562-l(c)(4)(iii) of the
September 30, 1987, Federal Register notice) appears to be in error and
is not supported by BID Vol. I. The commenter stated that the
appropriate limit should be 0.15 kg TOC/Mg product.
The commenter referred to Section 3, page 3-61 of BID Vol. I where
emissions from the various PET processes were discussed, and Table 6-lib
on page 14 of Section 6 where the model plant process emissions for the
PET terephthalic acid (TPA) process using multiple end finishers are
summarized. The commenter pointed out that the information contained in
these sections of BID Vol. I show the baseline emission rate from the
raw materials preparation section of the PET-TPA multiple end finisher
process to be 0.15 kg TOC/Mg product. The commenter then referred to
the various regulatory alternatives for control of this process which
are discussed throughout Section 6 of BID Vol. I and are summarized on
page 36690 of the preamble to the September 30, 1987, Federal Register
notice. This information, the commenter pointed out, indicates that
control of emissions beyond the baseline level in the raw material
preparation section is not required. Therefore, the commenter concluded
the 0.15 kg TOC/Mg product baseline level shown in BID Vol. I should be
the limit mandated by Section 60.562-l(c)(4)(iii).
Response:
The Agency reviewed the information in BID Vol. I and the docket
concerning this comment. The sources show inconsistent treatment of
esterifiers from high viscosity PET plants using multiple end finishers.
For example, Appendix E states that baseline control costs for these
facilities were estimated assuming reflux condensers on the esterifiers,
which are associated with an emission rate of 0.04 kg TOC/Mg of product
(see page 3-63 of BID Vol. I). The commenter, who uses a different type
of condenser on their esterifiers, has stated that they would expect
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their condensers to be as efficient as reflux condensers (see Docket
Item II-B-73). While a previous estimate based on sampling conducted in
1978 at the commenter's facility showed an estimated emission rate of
0.15 kg TOC/Mg product, a more recent test conducted by the commenter
shows that the controlled emissions from the esterifiers are below 0.04
kg TOC/Mg product (see Docket Items IV-D-70, IV-E-78, and IV-E-80). In
developing the baseline control costs, the Agency incorporated reflux
condensers as baseline control. Unfortunately, this was neither stated
nor shown in Chapter 6, page 6-41, where the contradictory, and
erroneous, statement was made that baseline control consisted, in part,
of distillation columns on the esterifiers. For new plants, it was the
Agency judgement that reflux condensers represented best available
technology and should serve as baseline for new, grass roots plants. As
noted above, the more recent test by the commenter shows that their
condensers are achieving equivalent levels of control. The Agency also
conducted a new analysis specifically estimating the cost of controlling
the commenter's 0.15 kg TOC/Mg product stream to 0.04 kg TOC/Mg product
(see Docket Item IV-B-20). This analysis showed the cost of control to
be reasonable. Thus, while the commenter is correct in pointing out
discrepancies in the BID for the proposed standards, the final rule
retains the proposed standard of 0.04 kg TOC/Mg product.
2.5 PRESENTATION OF THE STANDARDS
Comment:
Two commenters (IV-D-6, IV-D-8) stated that plant technical and
management personnel in a major polyethylene plant using both high and
low pressure technology to manufacture low density polyethylene have
encountered problems in determining and understanding the specific
requirements applicable to each process unit and section. The
commenters felt that their misinterpretations appear to be from the fact
that the facility is faced with a maze of requirements which vary
between product lines, affected process sections, and type of vent. One
commenter (IV-D-8) further felt that this was complicated by the use in
BID Vol. I of a low pressure LDPE model plant that did not adequately
describe that type of facility. The commenters thus recommended that
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the regulation be simplified and made more clear. The commenters
provided an example of a table that described the specific requirements
and controls by process, affected sections, and types of emissions
(continuous vs. intermittent). One commenter (IV-D-8) believed that
this will provide the clarity needed to ensure proper interpretation,
and can be used either to clarify or replace Table 1 in Subpart ODD of
the regulation.
Response:
The Agency has revised the final rule and incorporated several
figures to help clarify the requirements applicable to each facility and
the procedures for determining which process emissions are to be
controlled. These and other similar figures are presented in Appendix A
of this document.
Comment:
One commenter (IV-D-8) suggested that the flare regulations be
referenced to the flare standard as it appears in 40 CFR Part 60 rather
than being repeated in the proposed regulation. The commenter pointed
out that by incorporating the flare standard by reference any changes
made 1n the future to the flare standard would be automatically incor-
porated into the polymer NSPS, rather, than requiring a special effort
to incorporate changes to the flare standard in this proposed rule, and
such an approach would then be consistent to the way the Agency handled
equipment leaks in Section 60.562-2 of the proposed standard.
Response:
The Agency agrees with the commenter. Therefore, the final rule
now references 40 CFR 60.18 for the specific requirements for using
flares to meet the standards.
2.6 APPROPRIATENESS AND APPLICABILITY OF PROPOSED STANDARDS TO CURRENT
POLYMER PRODUCTION PROCESSES
2.6.1 Dilute VOC Streams
Comment:
Three commenters (IV-D-6, IV-D-8, IV-D-13) expressed concern over
requiring control of dilute streams. Commenters IV-D-6 and IV-D-8
stated that the Agency has not demonstrated that using a device that is
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98 percent efficient or reducing the TOC concentration to 20 ppm by'
volume (ppmv) on a dry basis {corrected to three percent oxygen content)
is either possible or economically reasonable for dilute gas streams.
The commenters noted that control of dilute streams has become much more
significant since the industry now relies more heavily on material
recovery for control -- far less material is left to be emitted and the
remaining VOC is more dilute. In this connection, Commenter IV-D-8
stated that there has been a recent trend in the polypropylene and
polyethylene industries, which developed since EPA reviewed the industry
to reduce emissions by maximizing raw material recovery. The comment
pointed out that nowhere in BID Vol. I or in the proposed rule did the
Agency consider material recovery as a possible control mechanism for
these industries. As a result, the extent to which low concentration
(TOC) streams now exist in these processes was not anticipated and the
difficulty and expense involved in controlling these streams was not
considered by EPA.
The commenters felt that the Agency failed to address adequately
the problem of availability and cost-effectiveness of control for dilute
gas streams (TOC concentrations <2,000 ppmv). One commenter (IV-D-8)
stated that EPA gave only cursory attention to the availability and cost
of controls for these dilute streams. This commenter referred to the
preamble to the NSPS (52 FR 36696), where the Agency states that, "Data
summarized in BID Vol. I showed that 20 ppmv is the lowest VOC
concentration achievable by combustion of gas streams containing less
than 2,000 ppmv VOC." However, as the commenter continued, BID Vol. I
only dealt with one source containing an uncontrolled VOC concentration
of less than 2,000 ppmv (Table C-6); these are being one containing 950
ppmv of maleic anhydride. According to this commenter, there are
insufficient data to establish the cost and effectiveness of controlling
vent streams from polyethylene and polypropylene facilities at all
concentrations less than 2,000 ppmv. Commenters IV-D-8 and IV-D-13
concluded, that, unless EPA can establish the availability and cost
effectiveness of controls for dilute gas streams, controls should not be
required.
One commenter (IV-D-8) believed that the insufficiency of these
data is not coincidental. According to this commenter, control (of
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these dilute streams) is not currently required under any 'State or
Federal program. The commenter claims EPA alluded to this on page 4-21
of BID Vol. I where it is stated that "... most of the streams involved
in the polymers and resins industry are high enough in heating value to
self-combust without using auxiliary fuels, virtually no advantage is
achieved by using a catalytic unit and their applicability in this
industry is very limited."
This commenter (IV-D-8) also stated that if BID Vol. I did in fact
establish that 20 ppmv is the lowest VOC concentration achievable by
combustion of gas streams containing less than 2,000 ppmv VOC, then the
lowest achievable VOC concentration is controlled far greater than the
best technology system called for by Section 111 of the Clean Air Act.
One commenter (IV-D-8) pointed out that many dilute streams will require
controls due to the misclassification of various effected processes (see
previous comments on LLDPE units). However, if these processes in
question are reclassified as suggested by this commenter, then the
problem of controlling these dilute concentration streams should go
away. Finally, the commenters suggested that EPA should also establish
a procedure in the regulation that would exempt any dilute concentration
stream in any affected facility from control if it can be shown that
control of that stream is not cost effective. Commenter IV-D-8
suggested as one possible way to do this is to consider the application
of a Total Resource Effective (TRE) Index to the subject vent streams.
This was also suggested by the other two commenters. If a suitable
alternative test cannot be provided, the commenter (IV-D-8) continued,
EPA should exempt all low concentration streams from control in this
standard using the same rationale it used to exempt the continuous vent
streams from the product storage bins.
Response:
The BID for the proposed standards summarized information
contained in Docket Items II-B-4 and II-B-5. These docket items contain
the conclusions reached by EPA concerning thermal incinerator
performance over a number of tests. The Agency believes that the
conclusions reached in those docket items are still valid and support
the proposed standard. Furthermore, the new approach presented in the
January 10, 1989, Federal Register notice and adopted in the final rule
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considers a wide range of low VOC concentration streams and the cost of
their control for determining the level of emissions necessary for
control to be cost effective. The final rule incorporates a low VOC
concentration exemption for new and existing affected facilities.
With regard to specific points raised by the commenters, the
Agency encourages industry to seek ways to maximize raw material
recovery. The analysis performed by the Agency is still valid,
nevertheless, for cost-effective control of emissions that remain after
the material recovery.
One commenter (IV-0-8) suggested that 20 ppmv is more stringent
than the best technology system called for by Section 111 of the Clean
Air Act [presumably calculating 99 percent reduction (2000-20/2000 =
0.99)], which is more stringent than the 98 percent destruction. The
commenter is incorrect, but the Agency understands the confusion. In
evaluating the performance capabilities of incinerators, the Agency
examined a large number of streams that had combustion air added to them
prior to being combusted. For these streams, the tests showed a
leveling off at 20 ppmv at the outlet when the concentration of streams
with combustion air fell below 1,000 ppmv. In other words, 98 percent
destruction was still being achieved by emission streams with combustion
air that had VOC concentrations down to 1,000 ppmv. Many of the streams
examined, however, required combustion air to be added to them. The
amount of combustion air required typically reduced the VOC
concentration by one-half. Thus, 2,000 ppmv of VOC before combustion
air is required could be incinerated by 98 percent (on a weight basis).
In summary, the 20 ppmv standard does not require a greater degree of
control than the best technology system, which is 98 percent destruction
by weight.
Comment:
One commenter (IV-D-39) stated that they attempt to control all
continuous VOC streams that are available at elevated pressures and it
has been only the very low pressure, dilute VOC streams that are
continuous (i.e., dryers, pellet tanks) which have been vented to the
atmosphere. The commenter stated that the proposed regulations would
possibly bring these streams under control, but the cost/benefit would
be extremely high.
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Response:
The Agency has carefully considered the VOC reduction obtained and
control costs incurred when controlling dilute VOC streams. The
procedure presented in the January 10, 1989, Federal Register notice for
determining which process emission streams should be controlled examined
existing data on both polypropylene and polyethylene emission streams,
Including very dilute streams. The control/no control determination
procedure developed by the Agency is designed to avoid extremely high
costs when compared to the resulting VOC emission reduction. Where
other comments have identified specific instances of potential problems,
the Agency has reexamined the procedures and the cost analysis. The
final rule incorporates some changes. Nevertheless, the Agency believes
the procedures in the final rule for determining which low VOC
concentration streams should be controlled is a more than adequate
procedure for avoiding the general situation described by the commenter.
Comment:
Four commenters (IV-D-39, IV-D-43/IV-D-50, IV-D-.44, IV-D-45)
expressed concern over the lack of an exemption for streams with less
than 0.1 weight percent VOC from new affected facilities. Commenter
IV-D-39 stated that the Agency's reason for excluding new affected
facilities from the low VOC concentration exclusion was to preclude
operators from purposefully diluting streams to benefit from the
exemption. This commenter pointed out that "intentional dilution is
circumvention of control, which is already forbidden." This commenter
then stated that EPA should not promulgate rules which could possibly
Impose non-cost effective controls on some law abiding operators to
hinder those who may otherwise circumvent the regulations."
Commenter IV-D-44 stated that the Section 111 of the Clean Air Act
requires NSPS's to be economically justified. The commenter stated that
the Agency's "only justification for proposing control of sources less
than 0.10 weight percent is the difficulty in determining if dilution to
the low concentration was appropriate design or circumvention." The
commenter believes that this "difficulty" in evaluating sources does not
justify violating the Clean Air Act by imposing controls that are not
economically justified. The commenter stated further that there has
been no justification for control of low concentration sources from new
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facilities as proposed and 'that, if new sources have a different cost of
control, the minimum concentration at which controls are justified may
be less than the 0.10 weight percent VOC proposed for sources from
modified facilities, but not zero percent. This commenter concluded by
stating that low concentration streams from new facilities should meet
the same economic justification criteria (as for those streams from
modified facilities) and that, unless a difference in economic
justification is shown by new data, no sources less than 0.10 weight
percent VOC should be controlled.
Commenter IV-D-43/IV-D-50, states that EPA, in the support
material, has not provided justification or established cost
effectiveness for control of low concentration hydrocarbon emissions
from new sources. The commenter stated that if for very dilute streams
in modified plants it is true, as EPA stated, that "below 0.10 weight
percent VOC, the cost of control becomes so large that control is not
cost-effective regardless of the amount of emissions, then it should
also be true for such streams in new facilities because there is still
no real cost-effective control technology available. The commenter
states that the lack of a low concentration exemption for new sources is
a serious omission. This commenter identified several reasons as to why
very low VOC concentrations [0 to 5 percent of the lower explosive level
(LEL)] are found in the industry and stated that EPA should not require
companies to compromise safety by requiring higher VOC concentrations
when history has led industry to use more dilute levels to ensure
employee safety. This commenter also provided the following suggestions
in response to EPA's concern that new.facilities could use excessive
dilution to escape regulation:
(1) Due to the large amounts of purge air needed to operate existing
plants safely, the horsepower requirements to provide the purge
air is very large. Since it costs a great deal of money (300
to 400 horsepower units at approximately 25 to 30 dollars per
horsepower equals as much as $12,000 annually) to operate the
blowers, it is unlikely that an operator would want to
unnecessarily increase that cost.
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(2) Most new facilities are being built by companies that already
produce polyethylene. If a company wanted to intentionally
circumvent the law by using more air than needed for a new
process line or plant, it would be hard to justify if the
company were already operating an existing line at much lower
purge air flows. The EPA or the state would only have to compare
the new versus the old air flow rates. If the flows are much
different, the owner should have to justify the difference.
Commenter IV-D-45 recommended that EPA use the same procedures for
determining control of dilute VOC streams (<5.5 weight percent VOC) for
new affected facilities as it did for modified and reconstructed
facilities, and that EPA promulgate the same provisions for determining
control required for new facilities as it has proposed for modified and
reconstructed facilities. The commenter stated that not to do so would
subject the proposal to allegations that it is not representative of all
affected facilities in the categories being regulated, hence defective.
This commenter addressed EPA's request concerning excessive dilution of
streams to take advantage of a low VOC concentration cutoff for new
facilities.
Response:
The Agency has carefully considered this issue. The Agency is
still concerned that new facilities could be designed so as to "take
advantage" of a low VOC concentration cutoff, and at less expense than
the cost of controlling the streams. One commenter (IV-D-43/50)
indicated that the Agency could compare the purge air rates of a new
facility with existing rates. The Agency agrees that this could be a
useful mechanism to evaluate whether a company is trying to
intentionally dilute the stream to circumvent the rule. The Agency is
concerned that this is not necessarily applicable in all cases, either
because it is a first time facility for an owner or operator or because
it represents a sufficiently different technology that a comparison is
inappropriate. Another commenter (IV-D-45) pointed out that the nature"
of storage bin purges are such that the VOC concentration is initially
high and drops over time, and that such equipment and air purges are
designed so that the maximum concentration would be between 20 and 25 of
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the LEL. The Agency believes that recognition of this design feature is
a useful tool for evaluating whether "too much" dilution is taking
place. This again is somewhat limited in that not all dilute streams
will have VOC concentrations that vary as dramatically as might occur in
storage bins. On the other hand, designing storage bin air purge rates
so as to have maximum VOC concentrations at 20 and 25 percent of the LEL
makes it more difficult to justify streams that are diluted so that the
maximum VOC concentration is significantly below this level. By
examining these and other items (e.g., design criteria for pneumatic
conveyors), the Agency now believes that there are a sufficient number
of indicators that can be used to judge whether intentional
circumvention is being practiced at new facilities. Therefore, the
Agency has extended both the VOC concentration exemption and the
calculated threshold emission equations used for existing affected
facilities to new affected facilities (see Section 60.560(g) and
Table 3 of the final rule).
Comment:
Two commenters (IV-D-44, IV-D-50) pointed out that low
concentration continuous emission sources from modified and
reconstructed facilities in the range of 0.10 < 5.5 weight percent VOC
are required to be controlled only if the total emission from these
sources exceeds that amount calculated by the calculated threshold
emissions (CTE) formulae, but the same sources from new construction are
required to be controlled if the total emission exceeds a fixed amount
of 47 Mg/yr.
Commenter IV-D-44 stated that assuming that the CTE formulae were
derived to reflect that lesser concentrated sources are not justified to
control unless the total emissions are greater, the same should hold
true for cost analyses of economic justification regardless of whether
the source is in new or modified facilities. According to this
commenter, if control costs are different for new vs. modified
facilities, the CTE formulae may be different, but not a fixed threshold
value. Commenter IV-D-44 indicated that no economic justification was
shown in the docket items for control above the fixed limit (47 Mg/yr)
for sources in the range of 0.10 < 5.5 weight percent VOC.
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Commenter IV-D-50 supported the use of the CTE formulae saying
"such a procedure, as required by law, consider:; the cost of abatement
and the problems associated with controlling dilute VOC streams when
determining whether controls are justified." This commenter then stated
that using these formulae will not discriminate against the size of the
facility since the amount of emissions is considered in the equations.
Commenter IV-D-50 then stated that despite admitting that the emission
amount must be considered to determine whether controls are cost
effective for dilute streams (<0.60 weight percent), EPA has abandoned
the rationale previously stated for modified sources by setting a
47 Mg/yr VOC emission cutoff for all streams with a VOC concentration
< 5.5 weight percent from new plants, and that this approach does not
recognize the problems and costs associated with controlling dilute VOC
streams. According to this commenter, a 47 Mg/yr cutoff discriminates
against larger sources.
Both commenters recommended that the control of both new and
modified facility low level concentration streams (0.10 < 5.5 weight
percent) be determined by the same CTE formulae. Commenter IV-D-44
noted that this would also greatly simplify the regulation by
eliminating the difference between new and modified sources and would
satisfy the economic justification requirement of the Clean Air Act.
Response:
As noted in the previous response, the CTE formulae for existing
facilities are now applied to new affected facilities.
Comment:
One commenter (IV-D-44) stated that a new equation is needed for
calculating threshold control levels for VOC streams in the 0.10 < 0.12
weight percent range, because the upper end point calculated for this
weight percent range and the lower end point calculated for the 0.12 <
0.2 weight percent range are not the same (and they should be).
Response:
The Agency agrees that the end points of the equations referred to
by the commenter should agree. The equations presented in the final
rule have end points that agree.
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Comment:
One commenter stated that for streams containing less than
0.1 weight percent VOC concentration, control to 98 percent destruction
is not always technically feasible and is generally not economic. The
commenter then stated that catalytic incinerator vendors, for example,
will often not guarantee above 95 percent efficiency, and thermal
incinerators which can achieve 98 percent are not economic for low VOC
concentrations. The commenter then suggested that to solve the problem
of a lower weight percent cutoff for new affected facilities at
virtually the same level of environmental protection, the Agency modify
the rule to require 95 percent control for individual streams from new
process sections with more than 47 Mg/yr total combined emissions.
According to the commenter, this modification addresses the two main EPA
concerns:
-- EPA did not want to extend the 0.1 wt weight percent cutoff allowed
for modified facilities to new facilities because new designs, given
no existing baseline operating data, might simply adjust dilution to
achieve the cutoff. However, a 95 percent control would prevent
this particularly since the capital and operating costs of such
controls would increase with flowrate (dilution).
-- For environmental impact, the difference between 95 and 98 percent
control for a stream with <0.1 weight percent VOC is quite
negligible. Thus, setting the control requirement to 95 percent for
such dilute streams would allow the owner to select the most cost-
effective control (catalytic versus thermal incineration, for
example) without materially contributing to air emissions of VOC.
Response:
As noted in an earlier response, the Agency has decided to extend
the 0.1 weight percent VOC cutoff to new affected facilities, although
not for the reasons suggested by this commenter. Further, in comments
received on the January 10, 1989, Federal Register notice and in
conversations with individuals in the industry, the Agency continues to
find that catalytic incinerators can be and are designed for 98 percent
destruction. Therefore, the Agency has retained 98 percent destruction
as the standard.
Comment:
One commenter (IV-0-44) stated that the Agency's review of cost
effective controls appears to assume that all low concentration VOC
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streams are equally cost effective to control by catalytic incineration
if the sum of their emissions exceeds the CTE level. The commenter
pointed out that some streams may require additional pretreatment to
assure that particulates (polyethylene) will not foul the catalyst.
Alternate control devices (i.e., spare multi-bed systems), or allowances
for equipment defouling should be considered in the control cost
effectiveness. The commenter recommended that each potential candidate
stream for control be reviewed to see if additional cost for particulate
control and equipment spares is required, thus changing the economic
justification threshold in order for a proper cost effective evaluation.
Response:
As a result of further investigations, the Agency agrees that
additional pretreatment to ensure particulates will not foul the
catalyst is required in order to install a catalytic incinerator. The
additional investigation revealed that "primary" particulate control
equipment (e.g., baghouses) is already in place on the emission streams
of concern, so that the cost of the catalytic incinerator system would
now include filtering units to ensure that the particulates that remain
in the stream after the primary particulate equipment are reduced to
avoid fouling of the catalyst. The final rule incorporates these
additional costs for those streams that are likely to be controlled by
catalytic incinerators (i.e., streams with VOC concentrations less than
5.5 percent VOC by weight).
2.6.2 Low Flow Streams
Comment:
One commenter (IV-D-43/IV-D-50) pointed out that, under the
approach presented in the January 10, 1989, Federal Register notice,
individual continuous emission streams, with flows of 8 standard cfm
(scfm) or less, require control. The commenter stated that using a
flare to control certain 8 scfm continuous vent streams (those that
contain dangerous levels of oxygen) is not appropriate, because
introducing these vent streams into a flare can cause an explosion. The
conmenter referred to vent streams from compressor lubrication pots,
which may contain oxygen in which case they could not be sent to a flare
because of the risk of explosion. The commenter then stated that EPA
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should reconsider whether control of those continuous process streams of
8 scfm or less that could contain oxygen is appropriate.
Another commenter (IV-D-49) stated that the requirement for
control of streams with flowrates below 8 scfm (regardless of
concentration) seems to penalize owners with small emission streams
compared to those owners with larger emission streams. This commenter
then stated that control of 8 scfm streams may not be economic in all
cases: for example, if the stream is at a pressure below the flare
backpressure, or if it contains a high oxygen content. This commenter
recommended deleting the 8 scfm rule entirely.
A third commenter (IV-D-44) also stated that some streams may
contain oxygen, making them unsafe to flare, and recommended that any
stream that cannot be controlled due to safety considerations be
exempted.
Response:
The Agency has not changed the rule for low flow streams. An
analysis undertaken for the January 10, 1989, Federal Register notice
(see Docket Item IV-B-7) showed that low flow streams with air would
constitute such a small portion of the total volume of emissions being
combusted that the composition of the combined stream is changed only
marginally. Further, there are various methods available to minimize or
alleviate safety concerns, such as design features for flares,
substitute inerts as purge materials, or purging with inerts downstream.
As a generic rule, there will always be some streams that are more
costly to control as well as some streams that are less costly to
control than the typical stream. The Agency finds no reason to further
complicate the final rule with specific provision aimed at
distinguishing between low flow streams.
Comment:
One commenter (IV-D-44) recommended that the Agency include cost
effectiveness to control as site specific criteria for all continuous
8 scfm or less streams. The commenter pointed out that all streams of
8 scfm or less are required to be controlled, either by (1) 98 percent
destruction or to 20 ppmv, whichever is less stringent, or (2) in an
existing flare, incinerator, boiler or other control device located at
the plant site. The commenter then noted that the Agency determined the
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control of 8 scfm or less streams in flares to be economically
justifiable, but that no such economic justification was made for other
control devices. The commenter stated that NSPS are required to be the
best documented technology (BDT) economically achievable (less than
$2,000/Mg of pollutant removed) and asked: "What basis is the Agency
using to require control in devices other than flares?" According to
the commenter, these alternate control devices may yield less pollutant
destruction and be more expensive to gain access. The commenter then
stated that flare lines are usually readily available to tie-in
additional streams, but this would not be the case for incinerators,
boilers, and furnaces located at the plant site. According to the
commenter, costs for piping of the 8 scfm or less streams to these
devices may be significant and, as the requirement in Section .60.562-
l(3)(a)(l)(11) of the January 10, 1989, Federal Register notice
specifies that if a boiler or process heater is used to comply, the vent
stream shall be introduced into the flame zone of the bo'iler or process
heater, this provision could also be additionally expensive.
Response:
An owner or operator may elect to send such streams to any control
device that is available. As flares are the most commonly available
control devices, the Agency examined the costs to send such emissions to
them. The Agency then allowed the use of control devices other than
flares to give owners and operators specific options. The cost of using
other control devices may or may not be more expensive.
The commenter states that incinerators, boilers, and furnaces may
yield less pollution destruction. These devices can only be used to
control 8 scfm or less streams in certain situations, as explained in an
earlier response and in the January 10, 1989, Federal Register notice.
In such situations, BDT is not 98 percent destruction. Furthermore, in
such situations, the stream need not be introduced into the flame zone
as that requirement is associated with 98-percent destruction. This
latter point is clarified in the final rule.
In summary, the Agency does not need to perform cost calculations
for each and every conceivable situation. The justification of a
commonly available control technology that will work in all cases is
sufficient. The Agency believes that the cost basis used to justify
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control of all 8 scfm or less streams is reasonable. As a generic rule,
there will always be some situations where the actual cost may be higher
as well as lower. The Agency sees no compelling reason to further
complicate the rule by trying to incorporate the commenter's suggestion.
Comment:
One commenter (IV-D-50) stated that the Agency's suggestion that
there is adequate excess capacity to accept and control all 8 scfm (or
less) streams may not be true on a pi ant-by-plant basis. The commenter
recommended that EPA include cost effectiveness of control as a
criterion for controlling 8 scfm or less continuous process streams.
Response:
The Agency has not revised the final rule to incorporate a
criterion for determining when it may or may not be cost effective to
control all 8 scfm or less streams on a plant-by-plant basis. In a
sense, the problem presented by the commenter is that if there is not
sufficient excess capacity in a control device, then the cost of a new
control device to control all 8 scfm or less emission streams is not
cost effective. The Agency reexamined expected excess capacities and
the amount of excess capacity required before the threshold emissions
levels are reached for various weight percents (see Docket Item
IV-B-24). It is important to remember that (I) all streams in an
affected facility that has annual emissions equal to or greater than the
calculated threshold emissions (CTE) level for the particular weight
percent of VOC being examined are to be controlled regardless of the
flow rate of the individual stream; (2) the concern is where the total
emissions are less than the CTE level; and (3) total emissions come from
streams with flows greater than 8 scfm as well as those with flows less
than 8 scfm.
The Agency's reexamination showed that as the VOC concentration of
the combined stream of all 8 scfm or less streams decreased, the amount
of excess capacity needed increased. To illustrate this, suppose the
VOC concentration of the combined streams was 10 percent VOC by weight.
Then, an existing control device would need 12 to 19 scfm of available
excess capacity to accept this combined stream. Suppose instead, the
concentration of this combined stream was 4 percent VOC by weight. The
existing control device would now need 62 to 93 scfm of available excess
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capacity to accept the stream. If the total flow of the combined stream
is higher than that indicated for ei-ther of the two VOC concentrations,
then the total annual emission of the combined stream is greater than
the CTE level for that weight percent, and control in a new control
device is cost effective. Thus, if the existing control device did not
have the available excess capacity needed, the combined stream could be
sent to a newly constructed control device, and to do so would be cost
effective.
If the total flow of all 8 scfm or less streams is close to the
scfm that is equivalent to the CTE level, then the cost of control of
the combined stream in a newly constructed control device is only
slightly higher than that cost effectiveness used to guide the selection
of the CTE levels. If the total flow of all 8 scfm or less streams are
further away from the flow that is equivalent to the CTE level, then the
total flow is more likely to fit into available excess capacity. In
addition, the required excess capacities calculated by the Agency, in
the example above, assumed that the each stream being considered for
control in an existing control device has a flow of 8 scfm or less. The
regulation does not require control of individual streams with flows
greater than 8 scfm in affected facilities whose total emissions are
less than the CTE level. Thus, the available excess capacity that is
actually needed could be substantially less once streams with flows
greater than 8 scfm are factored out. Finally, the rule proposed and
adopted is a general rule. The commenters seek to exclude streams only
where there may be insufficient excess capacity, but do not propose to
include larger streams (e.g., all 16 scfm streams) at plants where there
may be sufficient excess capacity. If the rule were made specific, it
would also catch other streams that would be greater than 8 scfm. As a
general rule, there will be some situations in which it will be more
costly to comply and others where it will be less costly. The Agency
continues to believe that the 8 scfm or less rule is an appropriate one
that will not cause undue hardship on any one facility and has not
changed this provision in the final regulation.
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2.6.3 Polyolefin Plants
Comment:
Two commenters (IV-D-8, IV-D-9) expressed concern that the gas
phase model plant used as the basis of the proposed standards for LDPE
including linear LDPE (LLDPE) does not accurately represent plants that
produce LLDPE using the liquid solution process.
Commenter IV-D-8 stated that burning emissions from the product
finishing area of plants using a liquid phase solution process for
producing HOPE and LLDPE is not practical due to the low concentrations
of hydrocarbons in the stream. The commenter pointed out that some
plants, depending on process design or plant layout, may be able to send
these dilute VOC streams to a boiler or process heater as a part of the
air supply. If a plant must install a boiler to meet the proposed
limits for dilute streams, the commenter continued, then the energy cost
would be excessive for a small VOC reduction. Commenter IV-D-9 stated
that a solution plant manufacturing LLDPE more closely resembles the
HOPE solution model plant used to determine the regulatory alternatives
than it does the gas phase model plant. This commenter recommended that
processes that make LLDPE by the liquid phase solution process be
classified, for control purposes, with the HOPE liquid solution process
units. Commenter IV-D-9 proposed the following wording for Sections
60.560(a)(l)(v) and 60.560(a)(2)(vi) of the September 30, 1987, Federal
Register notice:
Section 60.560(a)(l)(v)
For the manufacture of high density polyethylene and low
density polyethylene (including linear) using a liquid phase
solution process: each raw material preparation section and
each material recovery section;
Section 60.560(a)(2)(vi)
For the manufacture of high density polyethylene and low
density polyethylene (including linear) using a liquid phase
solution process: Each raw materials preparation section, each
polymerization reaction section, and each material recovery
section.
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Commenter IV-D-9 stated that if this change is not made, the pro-
posed regulation would not be cost effective for LLDPE liquid solution
units. The commenter pointed out that under the proposed regulation a
plant manufacturing LLDPE is required to "achieve a 98 percent reduction
of emissions of TOC contained in the gas streams continuously discharged
to the atmosphere from each new, modified, or reconstructed raw material
preparation and product finishing section." The commenter stated that
the product finishing section in their LLDPE units, by definition,
potentially could consist of mixers, extruders, dryers, check hoppers,
blenders, and silos and their emissions would have to be controlled.
The commenter pointed out that emissions from these pieces of equipment
come from residual solvent left in the polymer which slowly exudes from
the polymer bead, and to prevent buildup of flammable hydrocarbon
mixtures, they dilute the emissions from the polymer beads with an air
purge before venting the emissions to the atmosphere. According to the
commenter, these vents have the same type emission characteristics as
vents from product storage bins, which in the proposed regulation, the
Agency determined were not practical or cost effective to control
because of their emission characteristic (VOC content is very dilute).
The commenter indicated that the Agency had determined, for the same
reasons, that the volatile organic compounds in the dilute air streams
found in the product finishing area of the HOPE liquid solution
processes need not be regulated. The commenter then concluded that
dilute vents from the LLDPE liquid solution process should not be
controlled either, and for determining proper emission controls, LLDPE
liquid solution units should be grouped with the HOPE liquid solution
model plants, not the LOPE gas phase process.
Response:
The Agency agrees with the commenters that the situation described
could result in control of emission streams that would be unreasonable
given the costs and emission reductions involved. As noted earlier, the
new approach for determining which process emissions to control resolves
these concerns.
Comment;
One commenter (IV-D-6) stated that the regulation should recognize
the existence of a polymer finishing section in many current low
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pressure low density polyethylene plants, but should not require
additional vent control because there should be no incremental emissions
generated in a plant with this additional material handling facility.
The commenter stated that the VOC emissions should be the same as shown
for vent "J" in the model plant.
Another commenter (IV-D-8) stated that in order to be consistent
with other sections of the standard, the proposal must exclude Stream J,
bin vents, in the low density gas phase polyethylene process from
regulation in Subpart ODD. The commenter noted that this exclusion
would be consistent with other process models that have similar
finishing sections in other process facilities shown in the regulation,
such as the polypropylene gas phase process.
Response:
The Agency is aware, as a result of this and other comments, that
the model plants that formed the basis of the September 30, 1987,
.Federal Register notice are outdated for certain existing plants. The
new approach presented in the January 10, 1989, Federal Register notice
addresses the concern raised by the commenters. The Agency did not
revise the model plant description because it would have no effective
impact on the application of this standard to such facilities. In other
words, suppose a product finishing section was added to the low pressure
LDPE model plant at this time and an analysis showed that control should
be required of the emissions. An applicability date of the Federal
Register notice for the final rule would have to be used. However, this
process section and its emissions already have a January 10, 1989,
applicability date. Thus, it is unnecessary to revise the model plant.
The new approach would require control of or exclude from control these
emissions as appropriate.
Comment:
One commenter (IV-D-6) stated that the uncontrolled emission limit
of 10 ppm (by weight) of VOC in Table 1 of the proposed regulation for
the Product Finishing Section in low pressure, low density polyethylene
plants should not be applicable to the product storage hoppers and bins
in the Product Finishing Section of modernized low pressure, low density
polyethylene plants because the Polymer Storage Tank (vent "I"), for
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which this uncontrolled emission limit exemption was provided, does not
exist in a modernized plant.
Response:
In this comment, the appropriateness of a specific uncontrolled
threshold emission rate from the September 30, 1987, Federal Register
notice is questioned. The Agency agrees that if the model plant
approach was retained, a reanalysis would be required based upon a
modernized LOPE, low pressure plant. However, as discussed in other
responses in this section, the Agency has determined that no useful
purpose is served by undertaking such a reanalysis. A reanalysis might
show a lower uncontrolled threshold emission rate is appropriate for the
product finishing section in a modernized LDPE, low pressure plant.
Since this would be a more stringent rule, a new applicability date
would be required. The new applicability date, however, would be after
the January 10, 1989, applicability date, which already applies to all
facilities. Thus, the new applicability date would be inappropriate.
The reanalysis might show that a higher uncontrolled threshold emission
rate is applicable. The Agency believes that this result is also
irrelevant. Under the rule for determining which process emissions are
to be controlled, the uncontrolled threshold emission rates come into
play only where the new approach shows control, but the uncontrolled
emissions from the affected facility are less than the uncontrolled
threshold emission rate exemption for that affected facility. This
applies only to affected facilities that are constructed, modified, or
reconstructed after September 30, 1987, and on or before January 10,
1989. A stream with an uncontrolled emission rate higher than the
uncontrolled threshold emission rate in the September 30, 1987, Federal
Register notice might have been exempted if its emissions are less than
the reanalysis' result. The Agency does not believe it appropriate to
extend such further potential exemptions. The new approach is the
procedure to be used for controlling appropriate streams without the
need to develop new model plants or modify existing ones. The retention
of the uncontrolled threshold emission rates was only to prevent owners
and operators who proceeded to make control/no control decisions based
on the September 30, 1987, from being penalized from an enforcement
perspective.
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Comment:
One commenter (IV-D-11) requested the Agency to more closely
review the impact of the proposed standards on the commenter's
polyethylene wax facility, if second stage reactors are to be considered
part of the product finishing section. The commenter stated that the
plant's process and products are unique to the industry, but the Agency
failed to take into account this type of facility during the development
of the proposed rule. Consequently the proposed rule, according to the
commenter, does not adequately address the unique characteristic
associated with second stage reactors and may impose unreasonable and
unrealistic standards on the plant. Therefore, the commenter believes
the Agency may need to consider developing separate standards for
polyethylene wax facilities.
Response:
As stated in an earlier response, the Agency considers the second
stage reactors described by this commenter to be a part of the
polymerization reaction section. In response to the January 10, 1989,
Federal Register notice, this commenter agreed with EPA's preliminary
decision that the model plants used in the original September, 1987,
proposal do not accurately reflect many existing polyethylene processes.
The commenter noted that the original September, 1987, proposal
classified their low molecular weight polyethylene wax manufacturing
facility as a low density low pressure polyethylene process, and that
their comments submitted characteristics associated wi'th a polyethylene
wax manufacturing facility and described the numerous differences
between their plant and EPA's model plant, which was based on Union
Carbide's UNIPOL process. The commenter then concluded by stating that
EPA's proposal to drop the model plant approach for polyethylene
manufacturing facilities is supported by the information supplied in
their original comments. Therefore, the concerns of this commenter with
regard to their specific process have been addressed in that Federal
Reqister notice, and .the Agency has not developed separate standards for
polyethylene wax facilities.
Comment:
One commenter (IV-0-3) believes that small vents from affected
sections of the UNIPOL polyethylene and polypropylene plants should not
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require control if below a deminimus level. This commenter believes
that the control of all ven-ts from affected sections of these UNIPOL
processes is unjustified because they are very small vents (containing
more than 20 ppm VOC, but only a few tons per year of VOC) that would
need to be compressed to overcome flare header pressure and therefore
represent a significant cost. The commenter suggested an allowance for
a deminimus amount of VOC, such as 5 tons per year per point source or
20 tons per year per affected section, or a deminimus allowance total of
0.15 lbs/1,000 Ibs of production.
Response:
The Agency has incorporated a deminimus level into the standards.
The deminimus level was presented for public comment on January 10,
1989, and has been retained in the final rule.
2.6.4 Polystyrene Plants
Comment:
One commenter (IV-D-6) stated that smaller polystyrene facilities
of the size assumed in the regulatory impact analyses would typically
have emission rates too low to measure if emitting less than the current
0.12 kg TOC/Mg product standard. Therefore, the commenter stated
exemption rates proposed would not be available to these facilities.
Response:
As noted elsewhere, the Agency disagrees that emission rates would
be too low to measure streams from "smaller" polystyrene facilities.
The uncontrolled threshold emission rate, however, has changed (it has
been increased to 0.05 kg TOC/Mg product) due to a cost reanalysis (see
Docket Item IV-B-18).
Comment:
One commenter (IV-D-6) claimed that the proposed emission limit of
0.0036 kg TOC/Mg product or outlet gas temperature of -25°C from each
final condenser in the material recovery section of a polystyrene plant
is not appropriate for vent gas streams that contain significant
quantities of water. The commenter stated that in their experience
moisture will be present in a polystyrene plant material recovery vent
stream and that this moisture comes from the water content of the
styrene and rubber used in HIPS manufacture. The commenter stated that
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the moisture content in the rubber used in HIPS manufacture can be as
high as 4,000 ppm, with the rubber content of HIPS ranging from 5 to 10
percent of the finished product. The commenter pointed out that, while
some of this moisture will be driven off through heat of reaction or
collected in water draws in the process, saturated water vapor (30 to 50
ppm) will remain in the devolatilizer vent stream (approximately 140°F)
and cause freezing problems at the specified refrigeration/condenser
control temperature of -25°C. Thus, the commenter concluded, the
technology and economics for which these standards were based are not
achievable without inclusion of water removal systems.
Response:
The Agency has reevaluated the regulatory options for polystyrene
emissions from the material recovery section, taking into account the
presence of water or other condensibles. The results of the new
analysis show that the proposed standard of 0.0036 kg TOC/Mg product is
still achievable at a reasonable cost considering the amount of emission
reduction (see Docket item IV-B-18). The new analysis, however, showed
that if emissions from existing plants where less than 0.05 kg TOC/Mg
product, control to 0.0036 kg TOC/Mg product would not be cost
effective. Previously, this level was found to occur at 0.016 kg TOC/Mg
product. Thus, on the basis of the new analysis, the final rule sets
the emission limit at 0.0036 Kg TOC/Mg product with an uncontrolled
threshold emission rate for exempting modified and reconstructed
affected facilities of 0.05 kg TOC/Mg product.
Comment:
One commenter (IV-E-82) requested the Agency consider allowing
emission streams from polystyrene plants the option to meet a 98 percent
destruction standard in addition to the emission limit (of 0.0036 kg
TOC/Mg product) and the outlet temperature alternatives. According to
the commenter, the emission stream from a subject facility contains
components that are not as easy to condense as styrene and the most cost
effective way to control such streams is through combustion.
Response:
The commenter has indicated the presence of certain compounds of
which the Agency had not been previously aware existed in the material
recovery emission stream for a polystyrene plant. The Agency agrees
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that for streams containing components that are difficult to condense,
the cost of meeting the current standards through the use of recovery
techniques, such as condensers, could be very expensive considering the
emission reduction achieved. In such a situation as presented by the
commenter, the owner or operator of the affected facility could
demonstrate compliance with the emission limit by ducting the emission
stream to a combustion device (e.g., a thermal incinerator), as the
standard was proposed. The owner or operator could measure the
destruction efficiency of the combustion device and apply that
destruction efficiency to the inlet emission level of the material
recovery stream to calculate the expected outlet emission level of the
stream. The Agency believes that there is little, if any, adverse
environmental impact by allowing these emission streams to meet a 98
percent reduction or to 20 ppmv standard. Therefore, the final rule
specifically adds this alternative standard for polystyrene plants.
Comment:
One commenter (IV-D-6) stated that the proposed standards for
continuous polystyrene plants should include fugitive emission
requirements only.
Response:
The Agency has determined that process emission from continuous
polystyrene plants can be controlled beyond what many plants are already
achieving. Therefore, the standard continues to require control of both
process and fugitive emissions.
2.6.5 Threshold Levels
Comment;
Three commenters (IV-D-7, IV-D-8, IV-D-13) recommended that any
existing facility that becomes modified should not have to meet the re-
quirements of Section 60.562-1 if the facility's existing emissions
(controlled or uncontrolled) are already equal to or less than the rates
in Table 1 of the proposed standards. The commenters stated that the
proposed exemption rates failed to consider that there are some existing
facilities, which will become modified, that are already achieving
significant emission reductions through existing state and PSD permits,
and that additional controls are likely to be installed on existing
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facilities as a result of State Implementation Plan revisions for ozone
nonattainment areas.
Another commenter (IV-D-47) stated that the criteria for
determining applicability should not be termed "uncontrolled emissions,"
but "federally enforceable emissions limits" in order to allow credit
for the emissions controls that have already been required by State Air
Pollution Control Agencies.
Response:
The Agency agrees that the regulation needs to take into account
emission streams that are already controlled as a result of State
regulations, especially those that are Federally enforceable. The new
approach presented in the January 10, 1989, Federal Register proposed
that "uncontrolled" emission streams be combined. The September 30,
1987, Federal Register notice proposed "uncontrolled threshold emission
rates," where uncontrolled referred to the emissions that would be
"emitted to the atmosphere in the absence of any add-on control
devices... ." The promulgated regulation requires an owner or operator
to examine the uncontrolled emissions (i.e., those that would be emitted
to the atmosphere in the absence of an add-on control device). Where an
emission stream in an affected facility is controlled by an existing
control device (i.e., one that was operating before September 30, 1987;
one that was operating between September 30, 1987, and January 10, 1989,
on emissions from a process section that was not identified as an
affected facility for those emissions in the September 30, 1987, Federal
Reqister notice), the inlet conditions to the control device would be
examined to determine whether that emission stream is required to be
controlled by BDT. Individual streams that are vented to the same
control device constitute a single stream. The following describes how
control determinations are to be made for controlled streams.
For polypropylene and polyethylene affected facilities with an
applicability date of January 10, 1989, or earlier, the inlet emission
rate is compared to the uncontrolled threshold emission rate for the
appropriate process section and type of emission (i.e., continuous or
intermittent). If the inlet emission rate is equal to or less than the
corresponding uncontrolled threshold emission rate, no further control
is required. However, if the inlet emission rate were to exceed the
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uncontrolled threshold emission rate at some time in the future, then
the new approach for determining which process emissions would be
required to meet the standards, as discussed in the following
paragraphs, would be used to redetermine whether these emissions need to
be controlled to meet the standards in the final rule. The new approach
would also be used in those instances where the inlet emission rate is
greater than the corresponding uncontrolled threshold emission rate.
For polypropylene and polyethylene affected facilities with a
January 10, 1989, applicability date and for those facilities identified
above, the new approach would be used. Under the new approach, the
annual emissions of the inlet emission stream would be compared to the
CTE level, which would be calculated based on the TOC weight percent of
the inlet stream.
If the emissions (Mg/yr) of the stream entering the control device
are greater than or equal to the CTE level, then that stream is subject
to BDT (98 percent reduction, 20 ppmv, control in flare meeting the
specified operating conditions). If the existing control device is
meeting BDT, then, no further control of the stream (or combined streams)
is required. If the existing control device is not meeting BDT (e.g.,
only achieves 90 percent reduction), then the emission stream is
required to be controlled to BDT at the next available opportunity. The
next available opportunity constitutes the next time the existing
control device is reconstructed or replaced or its operation is changed
as the result of changes in State or local requirements. At such time,
any uncontrolled emissions in the same weight percent range from any
affected facility are also required to be controlled.
If the emissions (Mg/yr) of the stream entering the control device
are less than the CTE level, BDT is not required at that time. Whenever
the existing control device is reconstructed, replaced, or changed (as
discussed above), the controlled stream is reevaluated to see if BDT is
required by combining its annual emissions (measured at the inlet) with
the annual emissions of any uncontrolled vent stream within the same
weight percent range and comparing it to the CTE level. If these
combined emissions are now equal to or greater than the CTE level, BDT
is required for the controlled and uncontrolled vent streams.
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It is important to note that the "delay" in applying BDT to a
controlled stream does not affect the timing for applying BDT to
uncontrolled emission streams. Application of BDT is required for all
uncontrolled emissions as soon as the total annual emissions for a
combined stream (or single stream) are equal to or greater than the CTE
level for the weight percent.
For all polystyrene and PET affected facilities, if the inlet
emission rate is less than the uncontrolled threshold emission rate,
then the existing control does not need to be BDT. If the inlet
emission rate is greater than or equal to the uncontrolled threshold
emission rate, then the stream is required to meet BDT at the next
available opportunity (as discussed above).
Comment:
One commenter (IV-D-1) stated that the 98 percent emission
reduction required under Section 60.562-l(a)(l)(i) would translate into
approximately 0.2 kg/Mg (see Table 1 in the proposed regulations,
"Maximum Uncontrolled Emission Rates") for a bulk plant with a purge
stream equal to 1 percent of the total propylene feed, using the
rationale for "destruction efficiencies" developed in the preamble.
This commenter recommended that the same should also apply to a gas
phase process using a feed gas stream of equal quality, unless of
course, these continuous gas streams would come under the rules for
"waste gas disposal" and thus "qualify for inclusion in the regulatory
baseline."
Response:
In a follow-up phone call to the commenter (see Docket Item IV-E-3),
it was discovered that the commenter did not fully understand Table 1
and how the numbers were developed. The commenter was identifying the
remaining emissions that would occur as a result of 98 percent destruc-
tion of purge stream for a bulk plant, which was equal to 1 percent of
the total propylene feed, and thought this was what was being reported
for the other process section emissions in Table 1. The "maximum
uncontrolled emission rates" refer to uncontrolled emissions that are
vented to the atmosphere without passing through an air pollution
control device; thus, no percent reduction in applied to these streams.
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2.6.6 Emergency Vent Stream Exemption
Many commenters commented on the exemption of intermittent
releases as proposed in the September 30, 1987, Federal Register notice
and as revised in the January 10, 1989, Federal Register notice. The
comments made were extensive. Both sets of comments are reported, in
detail, and then the Agency response is given.
Comment:
In responding to the September 30, 1987, Federal Register notice,
a number of commenters (IV-D-3, IV-D-4, IV-D-7, IV-D-8, IV-D-13)
requested that an exemption be made for emergency vent streams from
polypropylene plants. In general, the commenters; pointed out Section
60.562-l(a)(2)(i) of the September 30, 1987, Federal Register notice
requires that each vent stream that emits intermittent emissions in
affected sections of polyethylene and polypropylene plants to combust
the emissions in a flare, and that most emergency vent streams from
polyethylene plants are exempt from this requirement, but there is no
similar exemption for polypropylene plants. Three of the commenters
(IV-D-7, IV-D-8, IV-D-13) pointed out that to direct emergency vents
(i.e., relief valves and rupture discs) from the polymerization reaction
and materials recovery sections will compromise safety due to the
potential for polymer buildup in the discharge to the flare. One
commenter (IV-D-8) pointed out further that while Table 1, (page 36688
of the September 30, 1987, Federal Register notice), which shows the
vent streams that were intended by the Agency to be controlled by the
new standard, indicates control only of non-emergency intermittent vent
streams for polypropylene, gas phase and high density polyethylene,
solution and slurry processes, the regulatory language itself does not
exempt the emergency vents from these processes. To resolve this
inconsistency, this commenter suggested the exemption for emergency
vents be extended to all intermittent vents, except those for
which EPA can establish that the cost of control would meet the same
definition of economic reasonableness as is applicable to all other
controlled emission sources, and meet the necessary standards of safety
to run the facility. Therefore, polypropylene plants should be exempt
from this requirement.
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Two of the commenters (IV-D-3 and IV-D-4) believe that the control
of UNIPOL emergency reactor blowdowns from either polyethylene
production or polypropylene production is not justified. These
commenters pointed out that the proposed NSPS does not require control
of emergency reactor blowdowns from the low pressure gas phase (UNIPOL)
polyethylene process, but appears to require control of emergency
reactor blowdowns from the low pressure gas phase polypropylene process.
The commenters felt that the process evaluated by the Agency has
characteristics that are different from the UNIPOL polypropylene
process, and that the emergency blowdowns from the UNIPOL polypropylene
process are of the same nature as those from the UNIPOL polyethylene
process. The commenters estimated that the annualized cost of
controlling these emissions of about 25 tons per year of VOC would be
about $325,000, which is at a cost per ton considered unreasonable
according to the preamble discussion. Thus, these commenter believe
that the UNIPOL gas phase polypropylene plants should not be required to
control emergency reactor blowdowns.
Three commenters (IV-D-7, IV-D-8, IV-D-13) suggested that Section
60.562-l(a)(2) of the September 30, 1987, Federal Register notice 'be
revised to read as follows: "For each vent stream that emits
Intermittent emissions in an affected facility, as defined in Section
60.560(a)(2) except for emergency vent streams in low density
polyethylene plants using either a high pressure or low pressure process
and high density polyethylene plants using a gas phase or a slurry or a
solution process, or polypropylene plants: (i) combust the emission in
a flare."
Another commenter (IV-D-5) recommended that the exemption provided
emergency gas streams from low density polyethylene plants using either
a high pressure or low pressure process and high density polyethylene
plants using a gas phase process be extended to all other polymer
processes that employ multistage relief systems. This commenter felt
that requiring flare systems-to be designed to handle the very
infrequent, large volume releases would result in unreasonably large and
expensive flares. This commenter also felt that extending such an
exemption would provide control (flaring) of most releases while
enabling the safe relief of infrequent releases.
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Comment:
In responding to the January 10, 1989, Federal Register notice,
most commenters (IV-0-39, IV-D-42, IV-0-43, IV-D-44, 45, 46, 47, 48)
expressed concern over the costs of controlling certain intermittent
streams that would be incurred because of the way the types of
intermittent streams were defined in the January 10, 1989, Federal
Register notice. Commenter IV-D-39 pointed out that their HOPE and PP
plants do not contain decomposition streams, but they do have runaway
reactions. The commenter pointed out that they have in the past
installed rupture discs under pressure safety valves to vent to the
atmosphere emissions from these runaway reactions. According to the
commenter, these emissions would not be allowed to be vented to the
atmosphere under the proposed rule and significantly higher equipment
costs (e.g., flare header size) would be incurred. (IV-D-39.6)
Two commenters (IV-D-42 and IV-D-48) expressed concern that the
definition of "decomposition" does not appear to include the UNIPOL
emergency reactor blowdown. These commenters indicated that these
emergency blowdowns are very infrequent and occur as a result of a
runaway reaction. The commenter stated that the consequences of not
having an emergency blowdown are quite costly (because of a resin
meltdown in the reaction). Commenter IV-D-42 stated that the
alternative of using a very large flare to handle these very short
duration emergency blowdowns is extremely expensive,and has been
documented in their comments to the September 30, 1987, proposed rule.
This commenter then provided a description of the UNIPOL emergency
reactor blowdown:
An emergency blowdown is necessary when cooling gas
circulation in the reactor is lost - to stop the reaction, to
stop temperature rise, and to prevent meltdown of the resin.
• An emergency reactor blowdown happens because of a cycle
compressor outage predominately caused by electrical outage
and infrequently by instrument or mechanical malfunction.
False instrument readings can cause this but are rare because
of reliability of today's instrumentation.
The consequences of not taking an emergency reactor blowdown
is meltdown of the resin in the reactor into a large chunk.
This results in a 2 to 3 week shutdown costing approximately
$500,000 ($100,000 for remedial maintenance and $400,000 in
lost income).
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Commenter IV-D-42 concluded by recommending that the UNIPOL
emergency reactor blowdown be excluded from control in the same manner
as "Decompositions", and offered the following definitions for
consideration:
1. "Decomposition" means for the purposes of this standard an
event in a polymerization reactor that advances to the point
where the polymerization reaction becomes uncontrollable,
resulting in runaway temperature or pressure increase.
2. "Decomposition" means for the purposes of this standard an
event in a polymerization reactor that advances to the point
where the polymerization reaction becomes uncontrollable, or
the polymer begins to break down (decomposes), or it becomes
necessary to relieve the reactor instantaneously in order to
avoid catastrophic equipment damage or serious adverse
personnel safety consequences.
This commenter stated that based on their knowledge of
polyethylene and polypropylene processes (including the high pressure
process which is the only one that has what Union Carbide Corporation in
the past has defined as a decomposition), the first definition is
adequate, simple and to the point, while the second definition is an
alternative that contains more words, and that the commenter believes
would also include the UNIPOL emergency reactor blowdown.
Commenter IV-D-43 stated that the proposed regulation, which now
requires that intermittent vents in an affected facility be combusted by
a flare, allows an exemption for decompositions, but no longer exempts
emergency intermittent streams (Section 60.562-l(a)(2) of the
January 10, 1989, Federal Register notice). The commenter stated
that the exemption for emergency vents should be retained for reasons of
personal safety, lack of available technology, and cost.
Commenter IV-D-44 stated that the requirement that each
intermittent vent stream other than decompositions in an affected
facility be controlled does not take into account that some intermittent
streams for safety reasons cannot be controlled in a flare system. This
commenter pointed out that relief valves are extensively used in the
chemical industry for protecting pressure vessels from the over-
pressurization which may occur for a number of reasons (i.e., fire,
exothermic reaction, inadequate cooling). The commenter noted that,
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based on the definition of "Intermittent Emissions" (52 FR 36707), the
emissions from relief valves would be included as an intermittent
emission source, thus requiring control. This commenter stated that
relief valves in the polyethylene industry primarily vented to flare
systems and secondary relief devices to atmosphere are only used when
normal venting to flare is too slow to protect plant personnel from
injury or prevent mechanical damage to the plant. As an example, the
commenter noted that should for any reason the flare header become
plugged (which has happened) and a plant experiences an emergency
situation, the secondary relief valve would be the only avenue of
process relief to protect personnel and equipment. In the commenter's
opinion, to require these to be controlled would compromise the safety
and integrity of the process unit.
Commenter IV-D-44 also noted that some intermittent vent streams
may contain oxygen which is not safe to include in a flare system. As
an example, the commenter referred to the manufacture of some catalyst
grades for the UNIPOL process in which air is used to activate the
catalyst. According to the commenter, nitrogen cannot be used in these
cases and thus introducing air (oxygen) into a flare header would create
an unsafe condition. Thus, the commenter recommended that the
regulation be revised to exempt secondary emergency releases which
protect equipment and personnel from injury; and intermittent sources
which contain oxygen and are therefore unsafe to be included in a flare
system.
Commenter IV-D-44 also requested that EPA review the definitions
of "Decomposition" and "Decomposition Emissions" to clarify that the
emissions from attempting to prevent a decomposition should also be
excluded. According to the commenter, there is no system that can
distinguish between an out-of-control condition and a false indication,
therefore the same preventative measures must be taken quickly in either
case to protect equipment and personnel. The commenter also stated that
routing of other emergency vent streams, which currently utilizes an
automatic control mechanism for atmospheric venting, to a control device
may be significantly different in cost for retrofit of an existing unit
versus cost for a new unit, that the cost for retrofitting the control
and associated hardware would be excessive, and therefore the regulation
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should allow for a cost effective-justification review for retrofit
requirements.
Commenter IV-D-44 concluded by recommending that:
1. The definition of "Decomposition Emissions" include those
emissions which cannot be controlled in attempting to prevent
a decomposition, because actual and indicated decompositions
cannot be distinguished.
2. The regulation allow decomposition venting, and other
emergency venting which is necessary to prevent exposure to
decomposition hazards, or which is not economically justified,
to go directly to atmosphere; and
3. Emergency vent streams on existing units be excluded from
being required to go to a control system where the cost can be
shown to exceed that which would provide cost effective
control benefits (cost greater than $2000 per Mg/yr).
Commenter IV-D-45, which focused their comments on the high
pressure polyethylene process, requested that the Agency change the
definitions of "decomposition" and "decomposition emissions" to read as
follows:
"Decompositions" means for the purposes of this standard an event
in a polymerization reactor that advances to the point where the
polymerization reaction becomes uncontrollable and it becomes
necessary to relieve the reactor instantaneously in order to avoid
catastrophic equipment damage or serious adverse personnel safety
consequences.
"Decomposition emissions" refers to only those emissions released
from a polymer production process as the result of a
decomposition. Except for high pressure polyethylene processes,
this term does not include emissions that may occur during
attempts to prevent a decomposition.
In support of this request, Commenter IV-D-45 provided the
following information: The high pressure polyethylene process differs
from the low pressure processes in that the reaction is a free radical,
random polymerization at very high pressures. The reaction releases
about 1500 BTU/lb of polymer produced with the heat sink being the
unreacted ethylene in the reactor. The kinetics of the reaction is such
that the hotter it gets, the faster it reacts and (because of the heat
generated) the faster it reacts, the hotter it gets. Basically, you are
controlling an explosion. If the reaction runs away completely, you
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have a decomposition reaction all the way to carbon. This must be
released through emergency valves to the atmosphere.
According to the commenter, during the past decade, computer
control of the reactor has led to a minimum of decomposition reactions.
The commenter stated that one factor that has made this possible (and
that must be considered in the NSPS) is the situation where the computer
senses the onset of a potential decomposition reaction and prevents it
by releasing a minimal amount of ethylene to the atmosphere. The
commenter pointed out that this release is still considered to be under
emergency conditions since the decomposition reaction moves very fast
(less than a few seconds) and that the reason this release must be to
the atmosphere is that the only way to know to prevent the decomposition
is an immediate and complete drop of the pressure to a very low level.
The commenter indicated that the increase in volume of ethylene from
30,000 pounds per square inch (psi) to near atmospheric pressure is in
the order of several thousand times and therefore, it is not practical
to have a vessel (a line is out of the question) to depressurize into.
An additional problem pointed out by the commenter would be if, in fact,
the depressurization did not stop the decomposition, then the catch
vessel would be receiving a runaway reaction, thereby creating a severe
and totally unacceptable safety problem.
The commenter concluded by stating that industry will continue to
minimize both decompositions and the type of emergency vents described
above due to the loss of expensive monomers, damage to relief valves,
and the loss of production and by noting that normal start-up, shutdown,
and miscellaneous purges from the reactor section are contained and sent
to a destruction device.
Commenter IV-D-46 stated the control high pressure emergency
releases as would be required by the proposed procedure outlined in the
January 10, 1989, Federal Register notice would create intolerable
safety risks and the cost of such control, if achievable, would be
prohibitive. This commenter stated that the control facilities required
to capture a high pressure, non-decomposition emergency release or a
high pressure decomposition emergency release would be similar in design
and cost, the control of either would be not cost effective, and
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therefore all emergency releases should be excluded from the need to be
controlled.
This commenter also presented several safety arguments related to
the control of non-decomposition emergency vents. According to the
commenter, most decomposition (including the emergency release attempt
to prevent them) from a high pressure, low density polyethylene process,
occur in a fraction of a second and that when a decomposition has
occurred, the non-decomposition emergency release has already been
attempted, but was unsuccessful in preventing the decomposition. The
commenter pointed out that decompositions are secondary emergency
emissions (explosions) that are directed upward from the top of the
polymerization reactor pump or rupture disc stacks into the atmosphere
away from personnel for their protection.
The commenter stated that an emergency release to prevent a
decomposition occurs because emergency action is required to ensure the
safety of personnel. Requiring burning of high pressure emergency
safety releases in a flare would defeat the purpose of the safety device
because to send the high pressure emergency safety release to a flare
would slow the depressurization process down, because the high pressure
release needs to be fed to the flare at a significantly (several orders
of magnitude) slower rate than would otherwise be released to the
atmosphere. Depressurization needs to be instantaneous to avoid
compromising safety, and the technology to accomplish this is not
available.
Another safety hazard, according to the commenter, would be
created by polymer pluggage of the flare system piping. When an
emergency release occurs, the contents of the equipment is dumped, and
if the release is from the reactor, gas and polymer will be released.
Flare piping system pluggage would cause overpressurization of the flare
system and also would not allow the emergency safety vent on the
equipment (Polymerization Reaction and Material Recovery process
sections) to function properly because of backpressure. If the
emergency vent collection system feeds a common flare header that serves
other parts of the plant, pluggage in this header would cause safety
hazards in flare tie-in piping throughout the plant.
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To minimize these problem, the commenter stated that an enormous
vent collection system would be required to collect the emergency
release and feed it to a flare, and each emergency vent collection
system would require a sophisticated polymer filtering system that would
not create backpressure in the system. The commenter stated that they
were not aware of any such system in this service.
The commenter also stated that the facilities required to capture
non-decomposition emergency releases in a high pressure plant would
likely have to be designed to the criteria standards that facilities to
capture decomposition emissions would have to be designed and built to,
because decomposition emissions are going to exit through the already
opened non-decomposition emergency release system (i.e., open dump
valves or blown rupture discs). According to the commenter, a
containment system to capture a high pressure emergency release would
create an undesirable safety risk because of the enormous size of the
system and the possibility of overpressurization or internal ignition
that could cause a catastrophic explosion.
In summary, Commenter IV-D-46 stated that the exemption for
emergency vent streams found in the September 30, 1987, Federal Register
notice should be retained for all intermittent vents in polyethylene and
polypropylene plants, except those for which EPA can establish that the
cost of control would meet the same definition of economic
reasonableness as is applicable to all other controlled emission
sources, and meet the necessary standards of safety to run the facility.
Therefore, Section 60.562-l(a)(2) of the January .10, 1989, Federal
Register notice should be changed to reflect this and should therefore
read as follows:
60.562-l(a)(2) For each vent stream that emits
intermittent emissions in an affected
facility as defined in Section
60.560(a)(2), except for emergency vent
streams in polyethylene and polypropylene
plants: control the emissions according
to Section 60.562-l(a)(1) (ii} or (iii).
Commenter IV-D-46 also stated that the definition of
"Decomposition" should be changed to include the break down of raw
materials in addition to the break down of polymer since in some polymer
processes, the raw material break down is the only significant part of
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the decomposition. Therefore, Section 60.561-Definitions
"Decomposition" should be changed to read:
60.561 - Definitions
* * *
"Decomposition" means for the purposes of this standard an
event in a polymerization reactor that advances to the point
where the polymerization reaction becomes uncontrollable, the
polymer or raw materials begin to break down (decomposes), and
it becomes necessary to relieve the reactor instantaneously in
order to avoid catastrophic equipment damage or serious
adverse personnel safety consequences.
Commenter IV-D-47 stated that the distinction between
decomposition releases and planned releases to prevent decomposition is
a matter of semantics more than a technical difference as the
technological difficulties for controlling each release are similar.
This commenter stated that trying to throttle a highly pressurized
gas/polymer mixture to "control" a release is essentially a go/no go
decision to dump the reactor, the purpose of which is to moderate
pressure spikes affecting reactor life and distortion of internal parts.
According to the commenter, industry, generally, does not presently
attempt to control releases during attempts to prevent decomposition.
The commenter pointed out that the time interval between detection of a
need to release and the time that decomposition actually occurs is on
the order of one second and stated that until technology to control such
releases is developed safety concerns should mandate venting such
releases to the air.
Commenter IV-D-47 also stated that the Agency's proposed rules
should provide an exemption for upset operations emissions in the
polypropylene process. Commenter IV-D-47 noted that current
polypropylene technology is such that runaway reactions do not occur.
The commenter described the technology as self-limiting in that as
temperature increases, the reaction rate increases up to the point that
the higher temperature causes the fluidized polymer to melt. The heat
of crystallization/melting absorbs sufficient energy and provides for
coating the catalyst particles so as to quench the reaction. The
commenter noted that there is another concern. In the event of a power
failure affecting the recirculation compressors, the commenter stated
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that the reactor beds would no longer be fluidized and unless the
reactor is vented the reaction will continue to the point of making one
large polymer "chunk" in the reactor. According to the commenter, the
clean up procedure following such an occurrence would require personnel
to enter the reactor vessel where potential pockets of decomposition gas
remain. The polymer "chunk" would have to be cut into small blocks
using air-driven saws. The downtime required for this situation may
take two weeks and be very labor intensive and costly. The commenter
pointed out that while such an occurrence is very infrequent, upset
operations emissions do occur and requested that they be addressed in
the proposed regulations.
Lastly, Commenter IV-D-47 suggested that Table 3 may be an
appropriate spot to incorporate alternative control options for
intermittent emissions. Eastman Chemicals Division utilizes a catalytic
oxidation unit for emergency blowdown emissions as required by the State
Air Pollution Control Board. The commenter indicated that they would •
like to use the existing catalytic oxidation unit for the intermittent
emissions requiring control (Table 3) rather than install a new flare
system (the estimated cost of the new flare system exceeds one-million
dollars).
Response:
Intermittent releases from polymer manufacturing plants can be
among the largest sources of VOC emissions at a plant. Some of these
releases have high volumes released in very short periods of times.
Because of the high volumes, the cost of controlling such releases is
very expensive. Releases of this nature include emissions that occur
during a decomposition event, during attempts to prevent decompositions,
and during reactor dumps to minimize the adverse consequences of a
runaway reaction (other than a decomposition). Based on the information
provided by the commenters and previously by the industry as whole,
these releases are related to operating conditions that are abnormal and
abnormal to the point that the design of the process cannot return
conditions to normal operations. In at least one instance, in the case
of emissions during attempts to prevent decompositions, these releases
are triggered to prevent a decomposition from occurring although there
is no guarantee that a decomposition would actually have occurred if the
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release was not made. However, the explosive nature of a decomposition
and the rapidity with which it occurs makes it virtually impossible to
distinguish between situations.
Some polymer producers use pressure relief valves or other
mechanisms to vent emissions from process vessels as part of the process
design for operating the vessels under normal operating conditions and
for maintaining normal process conditions. Examination of the
information available indicates that these emissions have been
controlled and can be controlled cost effectively. These intermittent
releases are designed to keep the process vessel in normal operating
conditions; they are not releases that occur because of abnormal
operating conditions or because releases are necessary to prevent
equipment damage or personnel safety hazardous because the operating
conditions can no longer be returned to normal operating conditions.
The Agency would like to relate the control/no control decision
for all intermittent releases in the same manner as has been done
for continuous emissions. However, for the reasons stated in the
January 10, 1989, Federal Register notice, this approach is not
feasible. Therefore, the promulgated standard continues to define the
categories of intermittent releases that are exempt from the standards.
In the promulgated standard, the definition of "emergency vent stream"
has been revised and is used, rather than decomposition, for exempting
individual intermittent releases from control requirements. In
addition, the definition of "decomposition emissions" has been revised
to include those emissions that occur as a result of attempts to prevent
decompositions.
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3.0 CONTROL TECHNOLOGY - PROCESS EMISSIONS
3.1 GENERAL
Comment:
Four commenters (IV-D-7, IV-D-8, IV-D-10, IV-D-13/47) stated their
support for the philosophy of allowing freedom of choice of
technological methods to the manufacturer as long as emission
requirements are met, and for a performance oriented approach to all
aspects of the standards, from control devices utilized to monitoring
techniques. Commenter IV-D-8 stated that specifying the specific
control techniques that can be used is unnecessarily restrictive,
especially as the Agency recognizes that various devices are capable of
achieving essentially equivalent VOC destruction efficiency.
Two commenters (IV-D-7 and IV-D-13) expressed concern over "EPA's
growing attempts to mandate technology to industry." One commenter (IV-
D-13/47) stated that the Agency should consider technical feasibility
and reasonableness of cost during its efforts to set realistic standards
and that the equipment specifications and the process technology
employed to meet reasonable standards should be at the discretion of the
manufacturer. This commenter expressed concern over the Agency's
tendency to mandate specific technology to the polypropylene and the
polyethylene industries, stating that specifying equipment (i.e.,
flares) instead of the emissions standards discourages the development
of new processing technology and control equipment and that the Agency's
determination of where available capital must be spent tends to stymie
long-term growth and stability of the polymers industry. The commenter
then recommended leaving the freedom of choice of control or process
technology to the industry.
The commenters believe that EPA should set the emission
requirement and allow industry to choose the appropriate technology to
achieve that requirement. Examples of restrictive wording cited by the
commenters are presented below.
Three commenters (IV-D-7, IV-D-8, IV-D-13) referred to Section
60.562-l(a)(2)(i) of the September 30, 1987, Federal Register notice,
which requires vent streams from affected facilities that emit
intermittent emissions to combust the emissions in a flare. The
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commenters stated that other control options that achieve a 98
percent/20 ppm reduction of VOC should also be allowed. Commenter
IV-D-8 indicated that some existing facilities may currently use other
control devices (such as catalytic incineration or boiler fire box
combustion) to control intermittent emissions from nonemergency vent
streams.
Additionally, one commenter (IV-D-8) noted the option of control
alternatives is highly dependent on the location of the process unit to
other units. For example, if an ethylene plant is on the same site as a
LDPE unit, then the LDPE intermittent emissions could be routed back to
the ethylene plant for recovery, a solution far preferable to flare
combustion.
Commenter IV-D-8 noted that examples of this type of restrictive
working are Sections 60.562-l(a)(2); 60.562-l(a)(l)(ii)(C); 60.562-
l(c)(l)(iii), 60.562-l(c)(3)(iv); and 60.562-l(c)(4)(iv).
Specific revisions (indicated by the words underlined) suggested
by one commenter (IV-D-13) were as follows:
1. Section 60.562-l(a)(l)(ii)(C): "Flares used to comply with
provisions of this subpart shall be steam-assisted, air-
assisted, non-assisted, or pressure (kinetic) flares."
2. Section 60.562-l(a)(l)(ii)(D): ". . . .; or with the net
heating value of the gas being combusted being 7.45 MJ/scm
(200 Btu/scf) or greater if the flare is non-assisted; or
with the net heating value of the gas combusted being 5.6
MJ/scf (.15.0 Btu/scf or greater i_f the f 1 are i_s a piloted,
non- assisted flare."
3. • Section 60.562-l(a)(2), add (ii): ". . . or use another
demonstrated satisfactory method of achieving emissions
reductions of £8 percent p_r 20 ppmv VOC. ifl the final vent
stream."
4. Sections 60.563(e)(l)(ii) and 60.563(e)(2)(ii) should be
revised to state: "An organic monitoring device used to
indicate the concentration level of organic compounds based
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on a detection principle such as infrared, photoionization,
thermal conductivity, or other demonstrated equally
effective device, or monitoring scheme."
5. Section 60.563(e)(3)(i) should be revised to state: "An
organic monitoring device used to indicate the concentration
level of organic compounds based on a detection principle
such as infrared, photoionization, thermal conductivity, or
other equally effective device or monitoring scheme for the
outlet of the carbon bed."
Response:
The Agency agrees with the commenters that any control device that
meets the emission requirements of a standard should be allowed to be
used. This is in fact a part of the Clean Air Act as amended [Section
lll(h)(3)], and it was never the intent of this rule to countermand the
Clean Air Act. The Agency also agrees that any monitoring technique
that provides equivalent indication of control device performance and
provides the same reporting and recordkeeping information required by
the rule can be used subject to the approval of the Administrator. The
particular control devices and monitoring techniques specified in the
proposed rule were selected based upon the Agency's experience and
analysis as to which control devices are the most effective, and then as
to which monitoring techniques were the most appropriate for those
control devices.
One commenter is incorrect in his implication that the Agency did
not consider technical feasibility and reasonableness of cost during the
standard setting process. The Agency throughout the development of this
standard, as well as for all standards, constantly concerns itself with
the technical feasibility of control devices as they would be applied to.
emission streams associated with, in this instance, the polymer
manufacturing industry. In addition, the Agency checks and double-
checks its cost information with equipment vendors and tries to identify
industry-specific characteristics that may affect the cost of the
control devices. In most instances, the primary source of emission data
available to the Agency to assess the technical feasibility of control
is the industry itself. In the course of this information exchange,
sometimes pertinent data that affect control device feasibility and cost
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are not transmitted by the industry or are sometimes inadequately
considered by the Agency. For example, initial industry data did not
indicate the presence of water in certain polystyrene and poly(ethylene
terephthalate) emission streams that would then affect the use of
subzero refrigerated condensers. Since proposal, industry has alerted
the Agency to this potential problem, the Agency has contacted
additional information sources, and, as a result, has revised its
analysis to take this factor into account. Thus, in summary, the Agency
always considers technical feasibility and costs in its standard setting
procedures.
The Agency also disagrees, in part, with the commenters'
suggestion that the "equipment specifications and the process technology
employed to meet reasonable standards should be at the discretion of the
manufacturer." The Agency has developed much expertise over the years
on the performance capabilities of various control devices. This
expertise has been gained in part from working closely with many
different equipment manufacturers. This association allows the Agency
to consider and rely on the collective wisdom of many individual
experts. To the extent that certain types of control devices (in this
instance, flares) require equipment specifications to ensure that a
standard is met, the Agency has the experience and expertise to specify
what those equipment specifications should be and will continue to
specify such in the future as necessary. As noted earlier, the Agency
does not wish to restrict the manner in which the proposed standards are
met, whether the industry or manufacturer selects the control technique
to use, so long as the standards are met.
Five specific examples of restrictive wording are noted by the
commenters. Each of the five examples is dealt with as specific
comments latter in this document. In general, the first two suggestions
cannot be accommodated at this time because of insufficient data to show
that the standard of 98 percent reduction would be met. The last three
comments deal with specifying in the rule the allowance of equivalent
control technologies or monitoring devices and, in general, the Agency
has incorporated these suggestions into the final rule.
Comment:
One commenter (IV-D-6) wrote that the preamble states that a flare
or other combustion device is appropriate, but that the regulation
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[Sections 60.562-l(a)(l)(i) and (ii) of the September 30, 1987, Federal
Register notice] appears not to allow a flare or other combustion device
as a control mechanism by requiring 98 percent reduction or a
concentration level of 20 ppm or less of VOC be maintained. This
commenter stated that the discussions in the preamble and preamble Table
1 indicate control options for continuous emission sources from
polyethylene processes to include (1) 98 percent control efficient
device, (2) reduce to 20 ppmv, or (3) flares. The commenter then
pointed out that, in the actual regulation [Section 60.562-l(a)(l)], the
inclusion of a statement about boilers or process heaters in paragraph
(i) before the final "or" confuses the intent to include the third
option of using flares. The commenter suggested that it would be less
confusing if the boiler/process heater statement was separated as
paragraph (iii) with reference to paragraph (i).
Response:
The intent of Section 60.562-l(a)(l) is to require continuous
process emissions to be reduced by 98 percent reduction or to a
concentration of 20 ppmv, whichever is less stringent. This requirement
was stated in Section 60.562-l(a)(l)(i) of the standards proposed on
September 30, 1987. Any control device, including flares, that can be
demonstrated to meet this standard may be used to comply with the
standard. Performance tests for flares, however, are very expensive and
difficult. Through a history of flare efficiency tests conducted by
EPA, the John Zink Company, and industry, flares have been demonstrated
to achieve 98 percent reduction when operated under certain conditions'.
These conditions were spelled out in Section 60.562-l(a)(1)(ii) of the
standards as proposed and are in Section 60.18 of the General
Provisions. The intent of separating flares from Section 60.562-
l(a)(l)(i) was to delineate the operating conditions under which they
could be used to comply with the standards and not to infer that they
could not be used in complying with Section 60.562-l(a)(l)(i) as
originally proposed. This portion of the regulation has been reworded
to avoid misinterpretation (see Section 60.562-l(a)(l) of the final
rule).
Comment:
One commenter (IV-D-43) stated that the January 10, 1989, Federal
Register notice contains inconsistencies regarding flare, incinerator,
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and boiler control and that the intended extent of control is unclear.
The commenter referred to a statement in the preamble to the Federal
Register notice (54 FR 896) regarding the control of the low flow
streams (less than 8 scfm), in which EPA states "... such control can
take place in a flare, incinerator, boiler, or other control device
located at the plant site and the destruction efficiency of the device
would not be specified." The commenter recommended that the language in
the proposed rule be modified to incorporate the concepts in the
preamble.
Response:
The preamble portion of the January 10, 1989, Federal Register
notice required control of all streams with flows of less than or equal
to 8 scfm and annual emissions equal to or greater than 1.6 Mg/yr. The
level of control differed according to whether or riot the stream was
located in an affected facility whose total emissions are required to be
reduced by 98 percent. As stated in the preamble, if the former were
the situation, then the low flow stream would also be required to be
reduced by 98 percent. On the other hand, if the latter were the
situation, then the low flow stream could be vented to a control device
without regard to that control device's VOC control efficiency.
This distinction was carried over into the standard portion of the
January 10, 1989, Federal Register notice in Table 3. In that table,
under the "Control/No Control Criteria," all streams are required to be
controlled by 98 percent (or to 20 ppmv), which was indicated by
reference to Section 60.562-l(a)(l)(ii) under the column titled
"Applicable Standard," or in a flare that meets specified operating
requirement, which was indicated by reference to Section 60.562-
l(a)(l)(iii) under the column titled "Applicable Standards," if
emissions are equal to or greater than the specified calculated
threshold emission (CTE) level. If emissions are less than the CTE
level, then no control is required except for streams with flows of 8
scfm or less. The control requirements for these streams were also
indicated under the "Applicable Standard" column. Reference to Section
60.562-l(a)(l)(i) allowed these streams to be vented to a control device
located on the plant site. Section 60.562-l(a)(l)(i) does not mention
how much VOC reduction must be obtained; thus, the standard presented in
the January 10, 1989, Federal Register notice was consistent with the
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preamble and the Agency has kept this provision in the final rule (see
Section 60.562-l(a)(l)(i)(D) of the final rule).
3.2 FLARES
Comment:
One commenter (IV-D-8) suggested that the proposed standards
(Section 60.562-1) allow the use of pressure (kinetic) flares and a
section on pressure (kinetic) flares be included. The commenter
proposed the following language for Section 60.562-l(a)(l)(ii)(C) of the
September 30, 1987, Federal Register notice: Flares used to comply with
provisions of this subpart shall be steam-assisted, air-assisted,
nonassisted, or pressure (kinetic) flares.
Response:
In order to accommodate the commenter's suggestion, EPA must be
able to establish minimum heat content and maximum exit velocity
parameters for pressure (kinetic) flares that would ensure 98 percent
destruction of VOC's. Unfortunately, EPA is not able to define these
conditions for pressure assisted flares. The EPA is aware of one set of
tests of two pressure assisted flareheads (see Docket Item IV-A-2).
Neither flare was piloted. One of the flares (flare F) was able to
maintain flame stability at about 200 feet per second (ft/sec) exit
velocity (maximum velocity tested) with only 150 Btu/scf (propane - N2
mix). At 60 ft/sec, the head required about 130 Btu/scf.
The second flare tested (flare E) required much higher gas heating
value to maintain flame stability. At 60 ft/sec, this head required
about 400 Btu/scf (propane - nitrogen mix). This head was tested at
velocities up to about 900 ft/sec.
For both of these flares, combustion efficiency was correlated to
flame stability using the ratio of gas heating value to that minimum
heating value required to maintain flare stability. Combustion
efficiencies greater than 98 percent were achieved when this ratio was
greater than 1.3.
The difference in performance of these two flares is not
understood. Both were equipped with flame retention devices, yet one
required a heat content almost three times as high as the other. Other
factors (in addition to gas heating value and exit velocity) must be
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important in determining flame stability. Additional testing would be
required to define these factors. Therefore, due to the inconclusive
nature of the tests that have been done on pressure assisted flares to
date, EPA has not incorporated the commenter's suggestion.
Pressure (kinetic) flares can still be used if they can
demonstrate equivalency. The flares tested achieved at least 98 percent
reduction under certain operating conditions (see Docket Item IV-A-2).
In determining equivalency, the Agency will consider the design of the
pressure (kinetic) flare and its operating conditions. If the flare can
be demonstrated to the Agency's satisfaction to be similar in design to
one of the two flares tested and that when operating will achieve those
operating conditions that were found to achieve at least 98 percent
reduction for the similar flare, then the Agency would consider such a
flare as demonstrating equivalency. If these things cannot be
demonstrated to the Agency's satisfaction, an owner or operator can
still demonstrate equivalency by conducting a performance test.
Comment:
One commenter (IV-D-44) pointed out that the Agency is currently
evaluating comments suggesting that control devices other than flares be
allowed (54 FR 890) and that Section 60.562-l(a)(l)(ii)(C) of the
September 30, 1987, Federal Register notice states; that only air-
assisted, steam-assisted, or non-assisted flares shall be used to comply
with this standard. The commenter then stated that ground flares, which
are multi-stage, pressure-velocity assisted flare systems, are also
currently being developed and used by the polyethylene manufacturing
industry, but that this type of flare does not appear to meet any of the
above flare type definitions or their associated requirements [proposed
Sections 60.562-l(a)(ii)(0, E, F)]. The commenter stated further that
the Agency has not proposed equivalency or use of this type of flare
technology, although in the new (January 10, 1989) approach, the Agency
is specifying control of "low flow" streams in some cases in a flare,
incinerator, boiler or other control device located at the plant site
and the destruction efficiency of the control device would not be
"specified (54 FR 896 and 908). The commenter recommended that these
inconsistencies be corrected, formal guidance on acceptable control
devices be issued, and procedures for approval of new innovative and
alternate technologies be provided by the Agency.
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Response:
In the January 10, 1989, Federal Register notice, the Agency
stated that we were evaluating control devices other than flares with
regard to the control of intermittent emissions as a result of comments
received on the September 30, 1987, Federal Register in which the
proposed standards required the use of flares to control intermittent
emissions. For continuous emissions, the September 30, 1987, Federal
Register notice indicated that 98 percent destruction by weight or 20
ppm by volume was the standard. If an owner or operator elected to
comply with this standard for continuous emissions by using a flare,
then the flare would be required to be an air-assisted, steam-assisted,
or non-assisted flare meeting certain specified operating conditions.
If an owner or operator wishes to use a multi-stage, pressure- •
velocity assisted flare to control continuous emissions that require 98
percent destruction, then the owner or operator would be required to
demonstrate equivalency or perform a compliance test, as noted in the
response to the previous comment. The Agency has inconclusive and
insufficient data to prescribe those operating conditions that would
ensure 98 percent destruction using such flares. Since control of
intermittent streams and certain low flow streams can be controlled
without regard to the destruction efficiency of the control device, then
such flares can be used without the need to demonstrate equivalency to
98 percent destruction.
In conclusion, the Agency believes the standards are internally
consistent with the application of flare technology in accordance to
whether a specific VOC destruction percentage is or is not required.
Furthermore, it is impossible (and inappropriate) to identify in this
rule all procedures an owner or operator must follow to demonstrate
equivalency because each technology will have its own unique aspects and
the General Provisions allow a case-by-case determination to be made.
Comment:
One commenter (IV-D-1) stated that the requirements proposed on
September 30, 1987, for combustion of continuous gas streams in a flare
[Section 60.562-l(a)(l)(11)(A)] and for combustion of emergency releases
in a flare [Section 60.562-l(a)(2)(i)(A)] are identical to existing
rules for "visible emissions" and are straightforward enough. However,
this commenter felt that requirements (B) through (F) (for continuous
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emissions) and (B) and (C) (for intermittent emissions) do not seem to
belong in the proposed regulations as these requirements deal with the
technical operation of flares or other matters that are usually resolved
in cooperation with the flare manufacturer.
Response:
Because of the technical difficulty of testing for the VOC
reduction efficiency of flares, EPA determined a set operational
specifications that would ensure 98 weight percent reduction efficiency
for continuous emissions. These specifications are identified in 40 CFR
60.18 of the General Provisions (see Federal Register, January 21, 1986,
pp. 2701-2702).
The EPA has not identified a complete similar set of operational
specifications for intermittent emissions controlled in a flare that
would ensure 98 percent destruction. However, the Agency believes that
the destruction efficiency of a flare controlling intermittent emissions
is greater when a flame is present at all times and when the flare is
designed to maintain a stable flame than when either of these two
conditions are absent. Flares controlling continuous or intermittent
emissions could be designed or operated in a manner other than
prescribed by the regulations in the absence of these regulations. Such
flares would potentially achieve less emission reduction. Thus, the
Agency disagrees with the commenter that such provisions do not belong
in the regulations, and these provisions are retained in the promulgated
rule. (Note: The provisions for controlling continuous emissions in
flares is now incorporated in the promulgated rule by referring to 40
CFR 60.18 of the General Provisions.)
Comment:
One commenter (IV-D-8) suggested that the standard should allow
5.6 megajoules per standard cubic meter (MJ/scm) (150 Btu/scf) instead
of 7.45 MJ/scfm (200 Btu/scf) as the minimum net heating value for
nonassisted flares with pilots. The commenter supported this suggestion
by referring to flare tests performed by EER for EPA that have shown
nonassisted flares with pilots reduce TOC by at least 98 percent if the
net heating value of the flared gas is not less than 5.6 MJ/scm. The
commenter provided estimates that such a reduction could reduce energy
demand for five flares combusting five vent gas streams with a total
flow of 514.5 x 103 cubic feet per hour by 17.5 x 106 Btus per hour.
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The commenter proposed the following language for Section 60.562-
l(a)(l)(ii)(D) of the September 30, 1987, Federal Register notice:
"...; or with the net heating value of the gas being combusted being
7.45 MJ/scm (200 Btu/scf) or greater if the flare is nonassisted; or
with the net heating value of the gas combusted being 5.6 MJ/scm (150
Btu/scf) or greater if the flare is a piloted, nonassisted flare."
Response:
The EPA believes that 200 Btu/scf is the correct cut off for all
nonassisted pipe flares. The commenter refers to a series of tests
which determined the flame stability of unassisted and piloted 3 inch
pipe flares (see Docket Item IV-A-3). A plot of "Flare Exit Velocity
(ft/sec) vs Gas Heating Value (Btu/scf)," Figure 4.2 page 4.4 of Docket
Item IV-A-3, shows the "stability limit" for these conditions passes
through the 60 ft/sec line at 150 Btu/scf. The stability limit plotted
here was determined by the appearance of the flame, not by combustion
efficiency test. This plotted line corresponds to the flare operating
conditions at which point the "faint orange flicker" was observed to
disappear as gas heating value was decreased or velocity increased. The
line drawn in this figure represents the average of the points observed.
Some points are above the line and some below. The conclusion of all
the flare studies has been that flares firing gases with heating values
near the stability limits are susceptible to perturbations and poor
combustion efficiency (see Docket Item IV-A-1). Combustion efficiency
is almost surely greater than 98 percent when the ratio of the actual
heating value to the heating value required for stability is 1.2 or
above (see Docket Item IV-A-3). If the stability limit (at 60 ft/sec)
was determined to be 150 Btu/scf, the heating value of the gas combusted
must be 180 Btu/scf (150 Btu/scf x 1.2) for 98 percent efficiency. This
is in close agreement with the value of 200 Btu/scf determined in
previous studies and required for nonassisted pipe flares and provides a
small margin of protection that perturbations will not cause poor
combustion efficiency. Therefore, the Agency has retained 200 Btu/scf
as the minimum net heating value for all nonassisted pipe flares.
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3.3 INTERMITTENT EMISSIONS
Comment:
One commenter (IV-D-8) suggested that the proposed standard for
controlling intermittent emissions [Section 60.562-l(a)(2)(i) of the
September 30, 1987, Federal Register notice] have a second part added
that allows the use of other control technology for intermittent flows
provided such control technology can achieve 98 percent reduction in
emissions or 20 ppmv. The commenter suggested the following language be
added:
60.562-l(a)(2)(ii): Or use some other or provable method
achieving emissions reduction of 98 percent or 20 ppmv VOC
in the final oases.
Response:
In addition to flares, several other combustion devices have the
potential to effectively control intermittent emissions. Both
Incinerators and boilers can reduce emissions by 98 percent reduction or
to 20 ppmv if properly designed, installed, and operated. There are
capacity and safety considerations that limit the applicability of these
devices for controlling intermittent emissions. It is generally
accepted that flares can control effectively a much wider range of flow
rates than incinerators or boilers. For these reasons, EPA considered
only flares as the control technology for reducing intermittent
emissions. However, the Agency sees no reasons not to allow other,
equally effective control devices, such as incinerators, boilers, or
process heaters from being used to control intermittent emissions.
Therefore, the promulgated rule now specifies that incinerators,
boilers, or process heaters may be used to control intermittent
emissions (see Section 60.562-l(a)(2)(ii) of the final rule). Other
control technologies not specifically identified in this rule may be
used if they are demonstrated to be equivalent in emission reduction.
Although the Agency is not requiring that intermittent emissions
be shown to be reduced 98 percent (or to 20 ppmv) when controlled in a
flare, incinerator, boiler, or process heater, such devices are to be
always operated in such a manner as to achieve optimal destruction. For
example, where a flare or incinerator is used to control continuous
emissions that are subject to these standards as well as intermittent
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emissions, then the owner or operator is required to operate the flare
according to the operating parameters specified for the control of
continuous emissions or, where an incinerator is used, demonstrate that
continuous emissions are reduced by 98 percent (or to 20 ppmv, whichever
is less stringent) both with and without the intermittent emissions.
Comment;
One commenter (IV-D-39) stated that the control requirements for
intermittent emissions are clearly stated in the preamble on page 898
and in Table 3 on page 894 of the January 10, 1989, Federal Register
notice, but that there is no such clear statement in the actual proposed
rule section.
Response:
While the Agency believes the proposed rule section in the
January 10, 1989. Federal Register notice clearly presented the
requirements for intermittent emissions, the language has been revised
in the final rule and provides clearer statements of the required
controls. As discussed above, revisions have been made to the control
requirements for intermittent emissions specifying the use of certain
control devices other than flares, and these revisions are also
incorporated in the final rule.
Comment:
Several commenters (IV-D-39, IV-D-42, IV-D-48) requested that the
1.6 Mg/yr exemption be extended to intermittent vents. Commenters
IV-D-42 and IV-D-48 indicated that control of small intermittent vents
is more costly and difficult than the control of small continuous vents.
Commenter IV-D-42 identified the high temperature and the use of air
(fluidizing) as aggravating the problem of control for two small
intermittent vents in the UNIPOL process.
Commenter IV-D-39 referred to the preamble statement that control
is required for all "start-up, shutdown, maintenance purges, and other
normal process releases." This commenter then stated that venting these
streams to control devices is extremely difficult. According to the
commenter, to lower the VOC concentration to a level where maintenance
can be performed on a vessel, for example, a purge stream must be routed
to the lowest available backpressure, which is the atmosphere, and there
is a point where vessels must be purged to the atmosphere prior to
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venting. For this reason, the commenter concluded, there should be an
exemption for low level intermittent streams.
Response:
The Agency recognizes that some individual intermittent streams
may be more costly to control than individual continuous streams, and
that the same logic for providing a small stream exemption should be the
same whether the stream is continuous or intermittent. The Agency
believes, however, that there is an overriding consideration that makes
such an exemption for intermittent streams impracticable. The purpose
of the small stream exemption is to identify individual streams whose
annual emissions are sufficiently small that it is not cost effective to
send the emissions to an existing control device. In order to properly
apply this exemption, one must be able to determine accurately total
annual emissions. Because they are continuous, this can be done for
continuous emissions. For intermittent emissions, this same certainty
is lacking because the annual emissions of an intermittent vent is
determined in part on the number of vents that occur each year, which
can vary. Thus, it is possible that a small intermittent vent would
have annual emissions lower than an exemption level one year and higher
than the exemption the following year. This could result in an
inconsistent decision from one year to the next. Furthermore, the
testing of intermittent emissions to determine accurately total annual
emissions is much more complicated and costly than for continuous
emissions. For these reasons, the Agency does not believe that an
individual stream exemption for intermittent streams is practicable, and
the final rules does not contain a low annual emission exemption for
intermittent streams.
Comment:
One commenter (IV-D-8) requested that the allowable period of
visible emissions for flares controlling intermittent emissions be
increased and the period extended because intermittent gas streams are
by definition much less frequent and are more difficult or impossible to
control (reduce) safely. The commenter pointed out that intermittent
gas streams differ from continuous gas streams because they are highly
variable, including emergency vents and usually have much higher flow
rates. The commenter noted that flares controlling intermittent
emissions can be designed to operate smokelessly for most of the gas
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flow range they are expected to handle; however, there are some flows
that cannot be handled smokelessly (e.g., vents resulting from equipment
breakdown, a decomposition, or power failure). In addition, the
commenter stated that tests done by CMA, EPA, and John Zink have shown
that the carbon (smoke) emissions from the smoking flare amount to 1
percent or less of the TOCs. Therefore, according to the commenter, a
smoking flare, although more visible, will still achieve a high
reduction of emissions. The commenter suggested visible emissions could
be limited, for example, to less than 10 to 15 minutes in any 3 to 4
hour period for intermittent process emissions.
Response:
As proposed, the standards for flares controlling intermittent
emissions required, in part, that such flares be designed and operated
with no visible emissions except for periods not to exceed a total of 5
minutes during any 2 consecutive hours. The commenters are requesting
that this period following visible emissions be extended to 10 to 15
minutes in any 3 to 4 hour period because some flows cannot be handled
smokelessly. Example flows cited by the commenters were those that
result from equipment breakdown, decomposition, or power failure.
The Agency notes that each example cited by the commenter is a
type of malfunction. The General Provisions allow emissions in excess
of the level of applicable emission limits that are caused by
malfunctions without such emissions being considered a violation of the
applicable emission limit unless otherwise specified in the applicable
standard [Section 60.8(c)]. It is not the intent of these standards to
require control of emissions that occur due to power failures,
decompositions, or other process upset that require emission releases in
order to avoid catastrophic equipment damage or personnel safety
hazards. For all other types of intermittent emissions subject to these
standards, flares can be and have been designed so as to operate within
the standards as proposed. The Agency finds no reason to change the
standards.
Comment:
One commenter (IV-0-46) stated that, while it wouTd be beneficial
to allow control of intermittent emissions by devices other than flares,
particularly for energy recovery, they know of no technology to control
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high pressure emergency releases as would be required by this proposal,
whether the control device be a flare or other control device.
The commenter stated that emergency releases in high pressure
plants typically occur at 35,000 to 45,000 psi on tubular reactors and
15,000 to 30,000 psi on autoclave reactors with initial gas flow rate
(peak flow) of a non-decomposition emergency release exceeding 300,000
scfm at a peak velocity of 1 mile/sec, and at temperature exceeding
600°F. The commenter then stated that the proposed revisions to the
regulations do not take into consideration that there is no technology
available to send this magnitude of gas flow to a flare. According to
the commenter, this flow would immediately destroy the flare system and
thus an intermediate step to add a gas collection system would be
required to collect high pressure releases and then send them to a flare
and at the same time, depressure the process equipment instantaneously
to avoid compromising safety. The commenter also noted that on high
pressure process equipment where decompositions can occur in
polyethylene manufacturing facilities, the decomposition emissions are
going to exit through the already opened non-decomposition emergency
release system (i.e., open dump valves or blown rupture discs) and thus
the control system to handle non-decomposition emergency releases would
be exposed to decomposition emissions and must have the capability to
handle decomposition emissions.
The commenter also stated that since technology does not exist for
control of high pressure releases from dump valves, the proposed
regulations may result in the generation of decompositions that would
otherwise be avoidable and this would increase the net emissions to the
atmosphere because, unlike emergency releases to prevent decompositions
in which a dump valve typically may stay open for 5 to 20 seconds (small
releases), decompositions result in equipment damage and venting of the
polymerization reaction and material recovery systems until they are
empty.
Response:
One company has in the past controlled high pressure emergency
releases from a LDPE, high pressure process. 'Thus, there is technology
that not only exists, but has been used, to control such releases.
However, the Agency does not believe that the cost of controlling such
releases is reasonable given the infrequency of such releases, the high
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flows, and the resulting lower level of emissions. As noted in the
response to the previous comment, the final rule does not require the
control of emergency intermittent releases as described by the
commenter.
Comment;
One commenter (IV-D-46) stated that the requirement to capture
high pressure non-decomposition emergency releases would create safety
risks that are unacceptable and would, therefore, force a phase out of
existing high pressure processes. According to the commenter, existing
facilities would not be able to compete with other processes because
when it becomes necessary to modify or reconstruct, the existing
facilities would be required to be retrofitted to send this relatively
small quantity (the commenter estimated emergency emissions including
decompositions to be less than 10 percent of total intermittent
emissions) of non-decomposition emergency releases to a flare. New
facilities would also be required to send the non-decomposition releases
to a flare. If technology were available to do this, it would be cost
prohibitive for the typical high pressure line or plant as seen in
Docket Item IV-B-12. Typical high pressure lines have a peak flow of
50,000 scfm of 100 VOC weight percent to 300,000 scfm of 100 VOC weight
percent. Based on their experience, the 50,000 scfm lines typically
have emergency releases of less than 10 Mg/yr and the 300,000 scfm lines
typically have emergency releases of less than 40 Mg/yr. The cost
analysis in Docket Item IV-B-12 apparently has made the assumption that
technology is available to send high pressure peak flows to a flare.
Hypothetically, if one could accomplish this, then the cost developed in
Docket IV-B-12 would be approximately $15,000/Mg for the 50,000 scfm,
100 VOC weight percent lines (from Table 2 of Docket Item IV-B-12). No
data are available in that docket for the 300,000 scfm, 100 VOC weight
percent lines. According to the commenter, such costs, technological
uncertainty regarding required controls, and safety risks would likely
lead to the phase out of high pressure processes, although high pressure
process plants currently: (1) operate safely, (2) have an inherent low
percentage of fugitive emission leakers relative to other processes
because in high pressure service, even a "pin hole" leak cannot be
tolerated, (3) can effectively control continuous emissions by using
currently available technology, (4) can effectively control non-
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emergency intermittent releases (approximately 90 percent of total
intermittent releases) by using currently available technology, and (5)
offer products that cannot be produced by other processes.
Response:
As noted in the response on the previous page, the "high pressure
non-decomposition emergency releases" have been controlled by at least
one company in the past and, as far as the Agency is aware, without
incident or compromise of safety. However, as also noted in a previous
response, the Agency does not believe it is reasonable to require
control of such releases. The final rule has been clarified as to this
point. Thus, the commenter's concern has been alleviated.
Comment:
One commenter (IV-D-46) stated that the costs of control for
emergency releases ($15,000/Mg) are significantly understated because
they do not include the cost of an emergency vent collection system to
protect the flare system. The commenter estimated the preliminary cost
of the required system to be $50,000/Mg to $110,000/Mg depending on
•reactor size and stated that safety considerations lead them to believe
that even these estimates understate true costs.
Response:
The costing of the separa-te flare system to control emergency
releases from a LDPE, high pressure process included the flare, ducting,
and particulate removal equipment per information provided by the
company that was controlling these emissions at that time (see Docket
Item II-D-105). Thus, the Agency believes it has adequately included
the necessary equipment for controlling such releases. Regardless, the
Agency continues to believe that the cost of controlling these releases
is unreasonable in light of the emission reduction achieved, and has
clarified the wording in the final rule to exclude these emissions from
control.
3.4 CONDENSERS
Comment:
Two commenters (IV-D-8, IV-D-13) stated that while the control
technology exists to achieve final condenser outlet temperatures of
-24*C during steady state operation of a polyethylene terephthalate)
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plant, there are routine stages of the operation of a plant which make
this temperature unachievable. The commenters pointed out that the
composition of the vent stream during startup, shutdown, and process
upsets varies to the point that maintaining an outlet temperature of
-24*C would lead to freeze ups and further process upsets. The water
content, polymer carryover, and other contaminants in the stream during
startup or shutdown, the commenter continued, will affect the
temperature at which the condenser outlet can be operated without
freezing during this portion of the processing. Therefore, the
commenters stated, if a gas temperature is specified in the standard and
is included as a permit parameter, there will be times when the process
must perforce violate the permit and adequate recognition that the
standards do not apply during startup, shutdown, or malfunction
conditions must be given.
The commenters then suggested that the regulatory language be
changed to reflect that if refrigerated condensers are used for control,
then when the process runs at steady state the outlet gas temperature
should be -24°C. The commenters provided the following suggested
language for the following paragraphs from the September 30, 1987,
Federal Register notice:
60.562-l(c)(l)(ii): If refrigerated condensers are used for
emissions control, not allow the outlet gas temperature from
each final condenser in the materials recovery section (i.,
methanol recovery) to exceed -24'C (-ll'C), at steady state.
60.562-l(c)(3)(iv): If the dimethyl terephthalate process is
being used, not allow continuous TOC emissions from the material
recovery section (i.e., methanol recovery) to be greater than
0.0027 kg TOC/Mg product; or if refrigerated condensers are
used for emissions control, not allow the outlet gas temperature
from each final condenser in the material recovery section (i.e.,
methanol recovery) to exceed -24'C (-ll'F), at steady state.
60.562-l(c)(4)(iv): If the dimethyl terephtalate process is being
used, not allow continuous TOC emissions from the material
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recovery section (i.e., methanol recovery to be greater than
0.0027 kg TOC/Mg product; or if refrigerated condensers are
used for emissions control, not allow the outlet gas temperature
from each final condenser in the material recovery section (i.e.,
methanol recovery) to exceed -24°C (-H°F), at steady state.
Response:
Periods of startup, shutdown, and malfunction are not considered
to be in violation if they exceed the expressed emission limits, as
provided for in the General Provisions, Section 60.8(c):
"...nor shall emissions in excess of the level of the
applicable emission limit during periods of startup,
shutdown, and malfunction be considered a violation of the
applicable emission limit unless otherwise specified in the
applicable standard."
Since the proposed standards do not specify otherwise, the General
Provision section was assumed to be prevailing. However, the
alternative temperature standard does not necessarily fall within the
definition of "emission limit" as used in Section 60.8(c). The Agency
Intends the same treatment to be accorded the alternative temperature
standard as for a true emission limit. Owners and operators are,
however, required to maintain and operate any affected facility
Including associated air pollution control equipment in a manner
consistent with good air pollution control practice for minimizing
emissions, to the extent practicable, at all times including periods of
startup, shutdown, and malfunction [General Provisions, Section
60.11(d)]. Therefore, the promulgated standard includes the commenter's
suggestion.
Comment;
One commenter (IV-0-6) stated that the uncontrolled emission rate
of 0.016 kg TOC/Mg of product for continuous polystyrene plants needs to
be reconsidered to take into account the presence of water in the
material recovery condenser vent stream. The commenter stated further
that it appears inappropriate that the newest facilities built with the'
latest devolatilizing vacuum and refrigeration technologies cannot meet
this uncontrolled emission level. The commenter suggested that this
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value, if appropriate at all, needs to be in the 0.050 kg TOC/Mg product
range.
Response:
The uncontrolled emission rate for the material recovery section
from polystyrene plants has been recalculated (see Docket Item IV-B-18)
based on the new data concerning water in the material recovery
condenser vent stream. The new uncontrolled threshold emission rate has
increased to 0.05 kg TOC/Mg product. This increase reflects the use of
a spared condenser system to bypass the potential freezing problem of
using subfreezing temperatures in the condenser.
The commenter refers to the inappropriateness of the proposed
uncontrolled emission rate by referring to the newest facilities with
the latest devolatilizing vacuum and refrigeration technologies not
being able to meet that level. The commenter appears to presume a
relationship between the level of uncontrolled emissions from a facility
that installs the latest process equipment and the level of emissions
that can be achieved when air pollution control is sought. The Agency
disagrees with this apparent assumption. The uncontrolled emissions
from an industrial facility in the absence of environmental regulation
is typically determined by a different set of economic and cost criteria
than the criteria used in setting environmental standards. The lower
level of emissions required by the standards does not say anything about
the technical capabilities of th,e latest equipment installed by
industry, but reflects the use of emission control equipment that allows
further reduction in emissions. As noted above, the Agency reevaluated
the appropriateness of the control technique used and as a result of
this revaluation has increased the uncontrolled emission rate.
Comment;
One commenter (IV-D-12) stated that the vapor streams from the
material recovery (methanol recovery) section of PET processes, both
high and low viscosity dimethyl terephthalate (DMT), are laden with
water vapor. The commenter pointed out that the concentration of TOC
emissions and condenser temperature are regulated in Sections 60.562-
l(c)(l)(i) and (ii) and 60.562-l(c)(4)(iv) of the September 30, 1987,
Federal Register notice. According to the commenter, if a refrigerated
condenser were used as the final condenser in the material recovery
section, the vapor stream would have to be dried before entering the
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condenser or the condenser would freeze and plug. The commenter stated
that such a drier for that large a flow and concentration would be
prohibitively expensive in terms of capital and operating cost and
should be excluded.
Response:
The Agency has reevaluated the regulatory alternatives for the
material recovery section from PET/DMT processes to taken into account
potential freezing problems (see Docket Item IV-B-18). However, rather
than using a drier on the stream, the Agency used a lower cost approach
of analyzing the potential emission reduction and cost using a spared
condenser system. This has resulted in a revision to the standard for
this process section. Based on the revised analysis, the final rule
sets an emission limit of 0.018 kg TOC/Mg product for material recovery
sections. Alternatively, an owner or operator of an affected facility
may limit the outlet temperature of the final condenser to +3°C (+37°F).
At proposal, these limits were 0.0027 kg TOC/Mg product and -24°C
(-1TF), respectively. In addition, the uncontrolled threshold emission
rate increased to 0.12 kg TOC/Mg product.
3.5 POLYETHYLENE TEREPHTHALATE) FACILITIES
Comment:
One commenter UV-D-12) stated that several features of their PET
process technology render the proposed standards either inappropriate or
technically impossible. Specifically, the commenter referred to the
ethylene glycol vapor stream that exits the steam jets (which are used
to draw the vacuum necessary to drive the polymerization reaction to
completion) is first cooled, and then sent to process waste treatment.
The commenter indicated that this stream would be (presumably)
regulated, according to the September 30, 1987, Federal Register notice,
by Sections 60.562-l(c)(l)(iv) and (4)(ii) for DMT processes and by
Section 60.562-l(c)(2J(ii) for TPA processes.
According to the commenter, (1) no appropriate limits can be set
for the ethylene glycol condensate from the vacuum system servicing the
polymerization reaction because that condensate stream cannot be
analyzed separately from the vastly larger steam jet condensate stream,
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and (2) the very dilute ethylene glycol in the combined condensate
stream is not recovered, but is biodegraded harmlessly. As such, the
commenter continued, its release into the environment is adequately
regulated under provisions of the Clean Water Act, and its vanishingly
low vapor pressure in wastewater solutions at ambient conditions results
in insignificant air emissions from trade waste basins.
The commenter stated that distillation of such a dilute stream to
recover the ethylene glycol is economically prohibitive, and use of a
refrigerated condenser is impossible, as there is no practical way to
dry the ethylene glycol vapor stream. Therefore, the commenter
requested that this stream be excluded from the regulation because it is
already regulated by National Pollutant Discharge Elimination System
(NPDES) permits, and it is neither cost-effective nor technically
feasible to regulate it as proposed. The commenter pointed out that
their stream is analogous to the "extruder quench vent stream" excluded
in the preamble (see 52 Fed. Reg. 36691, Col. 2) for cost reasons and
should be similarly treated.
Response:
Further conversation with the commenter has clarified this comment
(see Docket Item IV-E-39). The commenter had misunderstood as to where
the ethylene glycol was to have been tested. The proper testing point
for the commenter's systems is in the vacuum system's liquid effluent
(e.g., in the hotwell) prior to the cooling tower. Thus, the commenter
agrees that the stream can be analyzed (see Docket Item IV-E-54). The
Agency points out that for plants producing high viscosity PET using
multiple end finishers this testing is only required when the effluent
is recirculated through a cooling tower or similar facility. If a once-
through (one-pass) system is used for the cooling water at these plants,
then the liquid effluent from the vacuum system is not required to be
tested. (Note, however, that the rule requires testing of the liquid
effluent at all other PET facilities, including those that produce high
viscosity PET using a single end finisher, whether or not a cooling
tower is used.)
The second point by the commenter really deals with the need for
daily testing of this stream. The Agency has reconsidered this point,
and has included in the final rule a reduced testing program for those
facilities that meet certain criteria (see Sections 60.564(j)(l)(ii) and
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(iii) of the final rule). The final rule also allows an owner or
operator to use an alternative approach that relates ethylene glycol
concentration to another parameter, such as chemical oxygen demand (COD)
or biological oxygen demand (BOD) (see Section 60.564(j)(2) of the final
rule).
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4.0 CONTROL TECHNOLOGY - EQUIPMENT LEAKS
4.1 GENERAL
Comment:
One commenter (IV-D-8) stated that in order to achieve consistency
with Subpart VV [Section 60.480(c) and Section 60.480(d)(2)], Section
60.560 should contain the fugitive equipment modification provision and
a design capacity exemption for applicability of affected facilities.
Two other commenters (IV-D-7 and IV-D-13) also recommended adding the
design capacity exemption. Commenter IV-D-8 suggested the following
paragraphs be added:
60.560(a)(3): Addition or replacement of equipment for the
purpose of process improvement which is accomplished without
a capital expenditure shall not by itself be considered a
modification under this Subpart.
60.560(a)(4): Affected Facilities with a design capacity to
produce less than 1000 Mg/yr shall be exempt from Sections
60.562-1 and 60.562-2.
Response:
The Agency is aware of no differences between the polymer
manufacturing industry and the synthetic organic chemical manufacturing
industry (SOCMI) that would form a basis for not including in these
standards the two sections recommended by the commenters as they apply
to equipment leaks. Therefore, the Agency has revised the standards to
include these two paragraphs for equipment leaks (see Sections
60.560(a)(4)(i) and (ii) of the final rule). In addition, a definition
of "capital expenditure" has been added.
Comment:
One commenter (IV-D-1) pointed out that Subpart VV does not make
any distinction between valves of different sizes and suggested that
valves 1" or less in size be exempted because there is very little
return in terms of reduced emissions for the increases in the volume of
work tagging and monitoring these size valves.
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Response:
In developing similar standards for petroleum refineries, EPA
analyzed both the emission factor dependency on valve size and the costs
of small valve repair as compared to the average repair cost estimates
(Docket Item II-B-82). These analyses indicated that the emission rates
from small valves have not proven to be lower than those for larger
valves, and that repair of small valves is no more difficult or costly
than repair of large valves. The EPA concluded that, since both the
environmental benefits and cost of control for small valves are
comparable to those for larger valves, small valves are cost effective
to control.
The above conclusion was also reached in a similar standard for
the natural gas production industry. In that project, emission source
test data were collected at six natural gas/gasoline processing plants
by EPA and industry. Valves of all sizes were monitored in these tests,
and a relationship between valve size and emissions could not be
determined. The emission factors developed for the natural gas
production industry were developed based on these data for all valves in
gas processing plants. The basis of the gas production standards for
valves included all valve sizes and was determined to be cost effective.
Therefore, the Agency does not believe an exclusion for small valves is
warranted, and such an exclusion is not in the promulgated standards.
Comment:
One commenter (IV-D-40) asked where in the proposed standards one
was to quantify fugitive emissions. The commenter noted that the EPA
standards for "equipment leaks" are now being proposed for inclusion in
the regulations (Section 60.562-2 Standards: Equipment leaks of VOC),
but these standards as such do not address the question of quantifying
the leaks or fugitive emissions in terms of kg/Mg of product. The
commenter pointed out that when submitting an application for a "permit
to construct" under individual state rules (especially Louisiana and
Texas), all emissions have to be quantified, including the fugitive
emissions. The corresponding rules for equipment leaks (Part 60--
Subpart VV) have already been applied to VOC emissions from polymer
plants in the states referred to above (in LAC Paragraph 2121 and TAC
115.271, respectively). This means, of course, that emissions defined
in Table 1, as well as leaks based on quarterly measurements (usually)
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have been declared in recent permit applications. When actual
measurements are available, they should be used for estimating overall
leak rates. Permits issued, at least by the Texas Air Control Board,
also specify compliance with the proposed "Subpart ODD" as a permit
requirement.
Response:
The application of this standard is different from procedures or
requirements associated with obtaining permits from State or local
agencies. Whereas those permits may require an owner or operator to
quantity all emissions, quantification of fugitive emissions are not
required under Subpart VV or under these standards, which adopt Subpart
VV for polymer manufacturing facilities, because the control
requirements are work practices and equipment requirements and,
therefore, do not require quantifying the emissions.
Comment:
Two commenters (IV-D-7, IV-D-8) stated that the fugitive emission
requirements should be modified to improve cost effectiveness of the
control and that the required control program should be flexible enough
to account for the effect of new technology, state regulatory programs,
and the chemical characteristics of the compounds that could be emitted.
The commenters proposed several changes to the valve monitoring
provisions in order to achieve this flexibility. Commenter IV-D-8
stated that these changes would still obtain maximum emission control
and desirable cost effectiveness. The changes proposed by the
commenters were:
1. When a facility (new, modified, or reconstructed) becomes
subject to the fugitive emissions portion of the regulation:
(1) require testing of the valves within 180 days to determine
the percentage of leakers, (2) do not allow any special or
additional maintenance (other than that normally practiced) to
be done 45 days prior to the test, and (3) use the results of
the test (percent leakers) to determine the level of future
monitoring.
2. For valves, consider a plant with less than 2 percent leakers
to be a well controlled plant and require annual monitoring.
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If during a subsequent annual test, the percent leakers exceed
2 percent, require the plant to monitor quarterly or monthly
depending on the percent leakers. If the plant has between 2
percent and 10 percent leakers, consider it to be an average
performer and require quarterly monitoring. If the plant has
more than 10 percent leakers, require it to do monthly
monitoring and follow the existing regulation. Commenter IV-
D-8 stated that the economics of the proposed regulation are
based on emissions determined through the use of average SOCMI
factors for valves. Therefore, the commenter reasoned, a
plant that has greater than 10 percent leakers should be
required to monitor valves once per month as presently
proposed (the percent of leaking valves used to determine the
average SOCMI factor was 11 percent). Finally, allow plants
exceeding 2 percent leakers to work their way to annual
monitoring by following the requirements of Subpart VV Section
60.483-2 (Alternate standard for valves--skip period leak
detection and repair).
Response:
As adopted in these standards and as promulgated under Subpart VV,
valves in gas/vapor service or light liquid service are to be monitored
monthly to detect leaks (Section 60.482-7). A valve that has not been
found to leak for 2 consecutive months may then be monitored quarterly
until a leak is detected, in which case monitoring reverts to a monthly
basis [Section 60.482-7(c)]. Alternatively, the monitoring interval can
be increased to quarterly and then to annually if the percent of leaking
valves is equal to or less than 2.0 for a specified number of detection
periods [Sections 60.483-2(b)(2) and (b)(3)]. If more than 2.0 percent
leakers are detected, the monitoring interval reverts to monthly leak
detection and repair (Section 60.482-7). Alternatively, an owner or
operator may elect to comply with an alternative standard that limits
the percent leakers to a 2.0 or less (Section 60.483-1). Monitoring
under Section 60.483-1 would be conducted annually.
The Agency believes that these standards are already flexible with
regard to specifying and adjusting monitoring intervals on the basis of
how well a plant is controlled. In contrast, the commenters are
requesting that the standards be revised so that the initial monitoring
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interval (monthly, quarterly or annually) is based upon the results of
the initial performance test. In order to avoid companies from
purposely minimizing the number of leakers and thus to start with a
longer monitoring frequency, the commenters proposed that "special or
additional" maintenance be prohibited 45 days prior to the initial
performance test.
The Agency does not believe that the initial monitoring period can
be reasonably set based on a single initial performance test. (Note
that the annual monitoring interval under Section 60.483-1 is based upon
the decision to comply with this alternative standard and not upon the
results of an initial performance test.) Some facilities may test out
at less than 2.0 percent leakers (when in fact their historical leak
rate may be higher), and the next test would not be for 12 months under
the commenters suggestion. The purpose of the skip period (Section
60.483-2) is to allow for the development of a historical basis upon
which longer monitoring intervals can be justified. The commenters
recommendations could result in an increase in emissions that would be
otherwise controlled in a cost effective manner under the standards as
currently written. Furthermore, the Agency has determined that monthly
monitoring is incrementally cost effective versus quarterly monitoring
regardless of whether the leak rate is between 2 and 10 percent or over
10 percent. The commen.ter did not provide data to show otherwise.
Thus, the Agency sees no reason to create an artificial range of 2 to 10
percent and allow initial quarterly monitoring. Finally, the current
skip period procedures require relatively few additional monitoring
periods before the intervals recommended by the commenter are reached.
For example, since quarterly monitoring may be allowed after 2
consecutive quarters showing 2 percent or less leakers, a plant showing
over 2 percent leakers in its initial test could perform just 4
additional monitoring months before-instituting a quarterly monitoring
program.
The standards do not need to try to prohibit special maintenance
prior to the performance test. If an owner or operator truly believes
his facility is so well controlled as to have less than 2 percent
leakers, then the owner or operator can comply with Section 60.483-1,
which provides for annual monitoring. It is then incumbent on the owner
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or operator to continue sufficient maintenance so as to ensure
compliance with the alternative standard.
For these reasons, the Agency has decided not to revise the
relevant portions of Subpart VV as requested by the commenters.
Comment;
Commenter IV-D-8 felt that a plant whose valve population has less
than 2 percent leakers is well controlled and should not be penalized
along with the lesser controlled plants. But if its performance slips
(has greater than 2 percent leakers among its valves), then it should be
required to correct its mistakes, not be punished by the threat of a
non-compliance penalty. In Section 60.483-2 (Alternative standard for
valves—skip period leak detection and repair)»of Subpart VV, EPA allows
a plant that has "paid its dues" (advanced to annual monitoring by first
doing monthly and quarterly monitoring) to do more frequent monitoring
if 1t fails the annual 2 percent leaker test for valves, but without
threat of non-compliance. The regulatory penalties should be the same
[for a facility] that has complied prior to regulation and one that
compiles (through the skip monitoring alternative) after promulgation of
a regulation. This commenter thus recommended that the non-compliance
part of Section 60.483-1 be eliminated.
Response:
The Agency disagrees that a plant electing to comply with Section
60.483-1 is penalized relative to a plant electing to comply with
Section 60.482-7. Both plants are subject to non-compliance penalties.
The difference lies in the basis for determining compliance/non-
compliance, which reflect the two different standards.
The Agency agrees that plants which constantly achieve a low level
of emissions should not have to bear the cost of and adhere to a
mandated inspection repair program (i.e., Section 60.482-7). The
average level below which-leak detection and repair (LDAR) is not
required is 1 percent leakers. In order to take into account test-to-
test variability, the performance level is 2 percent. The Agency is
aware of no data showing that a plant which averages 1 percent will have
a significant probability of producing test results over 2 percent.
However, if an owner or operator believes that the leak rate may exceed
2 percent, then he may select LDAR to avoid the chance of a non-
compliance penalty under Section 60.483-1.
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4.2 ASSUMPTIONS AND EFFECT ON EMISSION ESTIMATES
Comment:
Several commenters (IV-D-1, IV-D-7, IV-D-8) expressed concern over
a number of assumptions made in BID Vol. I concerning fugitive
emissions, and in turn the estimates of fugitive emissions from polymer
manufacturing plants.
Commenter IV-D-7 specifically referred to the Agency's assumption
that there are no leak detection and repair programs in place in the
polymer industry and that the SOCMI factors underestimate fugitive
emissions. According to the commenter, the Texas Air Control Board has
for several years required fugitive monitoring and repair programs on
permits for new plants and major modifications to existing plants. The
commenter noted that experience with monitoring in polymer plants and
other SOCMI plants indicates that the factors overestimate fugitive
emissions.
Commenter IV-D-1 stated that the application of Subpart VV
(fugitive emission standards) to polypropylene plants does not appear to
add any major new requirements to these plants because equipment leaks
are already regulated under Louisiana and Texas rules, which basically
follow the directives of Subpart VV, and most polypropylene plants are
located in Louisiana and Texas.
Commenter IV-D-8 indicated the following assumptions and
statements as being inaccurate:
1. The assumption that SOCMI and polymer plants are
technologically similar and that average SOCMI factors
understate emission reductions. The EPA assumes the major
monomers used in polymer production are among the chemicals
found to have the'highest leak and emission rates using the '
SOCMI fugitive data base. While it is true that the ethylene
valves and pumps leaked twice as much as the average SOCMI
plant, there are major differences between the ethylene SOCMI
plant and the entire polymer manufacturing industry.
a. Ethylene is the only compound common to both the SOCMI
studies and polymer manufacturing. There are many gases,
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monomers and solvents used in polymer processes that have
very different physical and chemical properties from
ethylene and are used more during the process. These
compounds have similar properties as other chemicals in
the SOCMI study that leaked approximately an order of
magnitude lower than ethylene.
b. Since the operating pressures for the majority of polymer
manufacturing units are much lower than for an ethylene
plant (0-400 pounds per square inch gauge (psig) vs. 1000-
2000 psig respectively), it is reasonable to expect that
they leak less. This was determined from the EPA six
plant maintenance study on SOCMI plants (including two
ethylene plants), which discovered a correlation between
line pressure and-fugitive emission rate. The EPA states
"and in almost every case examined, higher leak
frequencies (i.e., emissions) were associated with higher
line pressures." (EPA Document 450/3-82-010. "Fugitive
Emission Reductions, and Costs", p. 2-30.) On the other
hand, the high pressure LDPE processes operate at about
20,000 psi. Whenever these plants leak, the high noise
level and visibility of the escaping chemicals will result
in an almost immediate process shut down for repair.
Therefore, leaks will be detected quickly.
c. Some of the compounds used in the manufacture of polymers
have distinctive odors (i.e., styrene) which make leak
detection and equipment repair much easier. The compounds
in the 24 SOCMI plant study that had low odor thresholds
had very low emissions (<2.0% leakers vs. 23% leakers for
ethylene service). This is not taken into consideration
in the proposed rule.
On page 6-2 of BID Vol. I, EPA states that "... fugitive
emissions are proportional to the number of potential sources,
but are not related to capacity, throughput, or age." It has
been 7-9 years since testing was done to determine average
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SOCMI factors. In those 7-9 years many advances have been
made in various components to reduce fugitive emissions. This
includes better valve designs and packings, better mechanical
seals for pumps, and improved seating surfaces for safety
valves. All these advances contribute to create new
components that have a lower potential to leak. Comparisons
of screening data from old and new components in the same
service clearly confirm this.
3. The EPA states that no fugitive emissions sources are
currently subject to any sort of routine LDAR program. This
may have been true when BID Vol. I was written, but is not the
case now. Most of the states where polymer plants are located
have or will have in place a LDAR program for new and existing
polymer manufacturing plants. Most of these states require
quarterly monitoring of valves and monthly monitoring of
pumps.
For units under a State LDAR program, the proposed NSPS would
only achieve a 9.0 percent reduction in gas valve emissions
instead of the 73 percent stated in BID Vol. I (73 percent
reduction in emissions for monthly monitoring minus 64 percent
reduction in emissions for quarterly monitoring). Similarly
for light liquid valves, the reduction would only be 15
percent instead of the 59 percent EPA assumes (59 percent
minus 44 percent). There would be no emission reductions
achieved for pumps since the State programs already require
monthly monitoring of pumps. Using these percentages,
reductions in Table 8-5 of the BID results in only a
15.1 Mg/yr reduction in VOC emissions, not a 58.7 Mg/yr
reduction.
Response
For the reasons discussed below, the Agency continues to believe
that the assumptions and methodology used in the BID to estimate
emissions from the polymer manufacturing industry is a reasonable
approach. Each of the specific points made by the commenters are
addressed below.
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Applicability of SQCMI Factors to Polvmer Manufacturing Plants.
Commenters IV-D-7 and IV-D-8 basically questioned the applicability of
using SOCMI fugitive emission factors for estimating fugitive emissions
from polymer manufacturing plants. Commenter IV-D-8 identified three
specific reasons as to why it would be inappropriate to apply SOCMI
factors to the polymer manufacturing industry and how in doing so
fugitive emissions from polymer manufacturing plants are overestimated.
The points are related to: (1) the types of compounds used in polymer
plants relative to those in SOCMI plants; (2) the operating pressure of
polymer units; and (3) the distinctive odors of certain polymer
compounds. The specific points are addressed following our general
response.
General. The development of VOC emission factors for equipment leaks is
founded on the concept that for a given screening valve equipment leaks
VOC at the same rate regardless of the industry or process unit. Total
emissions or average emission rates may vary, however, based upon the
relative distribution of screening valves (i.e., components leaking at
different rates) found in different industries or process units. For
example, the original SOCMI emission factors were derived from petroleum
refineries. After further study, the SOCMI fugitive emissions data
showed a difference in the number of leaking and non-leaking sources
(leak frequency) compared to the petroleum refinery data. The original
SOCMI fugitive emission factors (which were derived from the emission
factors from the Petroleum Refinery Assessment Study) were therefore
adjusted to more accurately'reflect the number of leaking and non-
leaking sources found in the SOCMI process units tested (the SOCMI 24-
Unit study).
In gathering data on the SOCMI, EPA sampled a number of vastly
different chemical process units. Characteristics of individual
chemicals were considered in -selecting the process units sampled during
the 24-Unit Study. Hi-volume, low-priced chemicals were included, as
were lower volume, higher-priced chemicals. Chemicals with widely
divergent volatilities were included along with chemicals that are
particularly odoriferous. Not surprisingly, the frequencies of leaks
found ranged from nearly zero to thirty percent. Leak frequencies
provide an indication of the relative quantity of mass emissions and it
is apparent from this range of leak frequencies that fugitive emissions
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from some units will be higher and some lower than estimates based on
the SOCMI factors. The mass emissions estimates generated by EPA using
the average SOCMI emissions factors represent an average that is
applicable to industry-wide emissions estimates. Without conducting a
rigorous Method 21 survey to determine the leak frequency (thereby
generating average emission factors based on the leak/no-leak factor
components), the average SOCMI emission factors stand as the best
estimators of fugitive VOC emissions currently available.
The major factor affecting the percent of leaks detected (or leak
frequency) from any equipment type is the vapor pressure of the
substance in the line. This finding forms the basis for separation of
different types of equipment by service (gas, light liquid, heavy
liquid). The substance in the line does not necessarily mean the
substance produced as the final product. Thus, the primary concern is
whether or not the leak frequency distribution found in polymer
manufacturing plants is sufficiently similar to those found in the SOCMI
plants. The commenters have identified three specific areas that they
believe invalidate the use of the SOCMI emission factors. These are now
discussed. For the reasons described below, the average leak
frequencies found in the SOCMI study are considered to be representative
of frequencies in polymer manufacturing plants.
Compounds Used in the Industry. The commenters stated that
ethylene is the only compound common to both the SOCMI studies and
polymer manufacturing. This is in error. As pointed out in Table 1 of
Docket Entry No. II-B-82, Docket No. A-82-19, there are at least seven
major organic compounds used in polymer manufacturing that are listed in
SOCMI. These chemicals are ethylene, propylene, butene, isopropyl
alcohol, ethylbenzene, styrene, and vinyl acetate. As shown in Table 2
of Docket Entry No. II-B-82, leak frequencies for five of the compounds
are available. These are propylene, ethylene, ethane, propane, and
vinyl acetate (a common comonomer used in polyethylene copolymer
production). SOCMI leak frequency data are also available for three
chemical units -- ethylene, vinyl acetate, and high density polyethylene
(HPDE) -- the latter of which is a polymer manufacturing plant.
The leak frequencies for propylene and ethylene chemical types and
for ethylene and HOPE units are much higher overall than those for the
average SOCMI model unit. The leak frequencies for vinyl acetate
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chemicals and units are much lower than for the average SOCMI model
unit. Similarly, the emission factors for ethy'lene ire consistently
higher than the respective average SOCMI emission factors, while vinyl
acetate's emission factors are consistently lower. This range of leak
frequencies and emission factors for the individual chemicals found in
the polymer manufacturing industry is similar to the range of leak
frequencies and emission factors for the individual chemical components
used to derive the average SOCMI parameters.
Considering the available data on specific polymer chemicals,
there is no evidence on this basis to suggest that it is unreasonable to
use the average SOCMI leak frequencies and emission factors for the
purpose of analysis.
Operating Pressure. In the past, industry has postulated that
certain process parameters affect leak frequency and emission rates.
The three most commonly mentioned process parameters have been line
size, process temperature, and process pressure. To the extent, then,
that these parameters differ between SOCMI and polymer plants, the
appropriateness of using the SOCMI data for polymer plants may be
questionable.
As pointed out in Docket Item II-B-82, Docket No. A-82-19, EPA
data currently available on line size support the argument that line
size is unrelated to emission rates and leak frequencies and that line
temperature has been found in general to have no consistent effect on
leak frequency.
With regards to operating pressures (the factor identified by the
commenter in this instance), data available on line pressure does show
that in almost every case higher leak frequencies for fugitive emission
sources were associated with higher pressures. Operating pressures of
polymerization reactors may range from near atmospheric (in polystyrene
plants) to very high pressures (up to about 50,000 psig in high pressure
processes for low density polyethylene) with a number of processes
between 100 and 500 psig. These operating pressures in polymer plants
fall within the range of operating pressures found in SOCMI plants.
Comparison with ethylene plants only overlooks the fact that SOCMI
factors and leak frequencies are average numbers derived from data on
this wide range of operating pressures.
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Odor. The commenters imply that the low rate of leaks in
polystyrene plants is due solely to the distinctive odor of styrene that
makes leak detection and repair much easier, and refer to the 24 SOCMI
plant study. The percent leakers in a plant is due to a number of
factors, one of which may very well be odor. If odor (or other factors)
result in lower average percent leakers for a particular plant, fugitive
emissions may well be lower and the use of average emission factors may
overestimate emissions for certain facilities. Nevertheless, the cost
of the standard, on average, will be reasonable across the polymer
industry.
Advances in Equipment. The commenters stated that advances in valve
designs and packings, better mechanica.l seals for pumps, and improved
seating surfaces for safety valves have led to lower level of fugitive
emissions. The Agency agrees that such advances would be expected to
reduce fugitive emissions. Unfortunately, there is no data to quantify
the magnitude of the effects of such advances. Thus, in the absence of
site-specific Method 21 testing, the Agency believes it is using the
best data available and that these data are reasonable to estimate
emissions.
State LDAR Programs. As pointed out by the commenters, State LDAR
programs now exist that affect polymer manufacturing plants. The Agency
recognizes that where such programs are in place, actual baseline
emissions for affected plants will be reduced from that in the BID.
Thus, as a result of programs being put in place since the BID, the
emission reduction attributable to the standard is reduced.
The amount by which the projected reduction would be reduced
depends on whether the State in which the constructed, modified, or
reconstructed facility is located has a LDAR program and, if so, on the
particular State LDAR program. Table 4-1 compares the LDAR program
under Subpart VV with the LDAR program identified by Commenter IV-D-8
and the LDAR programs descri-bed in Texas' and Louisiana's -State
regulations. The expected emission reduction, in terms of percent
reduction from an uncontrolled plant, from these various LDAR programs
are shown in Table 4-2.
The Agency agrees with the commenters that where LDAR programs
exist the emission reduction attributed to these standards do decrease.
Table 4-3 shows the estimated emission reduction (from uncontrolled
4-13
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TABLE 4-1
COMPARISON OF LDAR PROGRAMS
Component
Valves
- gas service
- light liquid
service
Pump seals
- light liquid
service
Safety valves
Compressor seals
Sampling
connect ions
Open-ended lines
Reauirement
Subpart W
monthly monitoring
monthly monitoring
monthly monitoring;
weekly visual
inspections
no detectable
emissions
no VOC emissions
to atmosphere; no
detectable emis-
sions; vent to
control device
closed purge system
or closed vent
system
cap, blind flange,
plug, or second
valve
Commenter"3
quarterly
monitoring
quarterly
monitoring
same as
Subpart W
none
none
none
none
Texas"
quarterly
monitoring
quarterly
monitoring
annual
monitoring;
weekly visual
inspections
quarterly
monitoring
quarterly
.monitoring
none
same as
Subpart W
Louisiana1"
quarterly
monitoring
annua I
monitoring
annua I
monitoring;
weekly visu
inspections
quarterly
monitoring
quarterly
monitoring
none
same as
Subpart VV
As identified in Table 4, p. 23 of commenter's letter (Docket Item IV-D-8).
Texas Regulation V. Fugitive Emission Control in Synthetic Organic Chemical, Polymer, and
Resin Manufacturing Plants in Harris County. 115.271 through 115.272.
Louisiana Air Pollution Regulations. 22.21, "Fugitive Emission Control."
4-14
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TABLE 4-2
COMPARISON OF EMISSION REDUCTION FOR VARIOUS LDAR PROGRAMS
Component
Valves8
- gas service
- light liquid
service
Pump seals6
- light liquid
service
Safety valvesd
Compressor sealsd
Sampling
connections6
Open-ended linesd
Percent Emission Reduction
Subpart VV
73
59
61
100
100
100
100
Commenter
64
44
61
0
0
0
0
Texas
64
(0)b
(0)b
59
72
0
100
Louisiana
64
(0)b
(0)b
59
72
0
100
' See Table 4-12, Docket Item II-A-32.
A "negative" control efficiency was estimated for these monitoring
intervals (see Tables 4-12 and 4-19 in Docket Item II-A-32). Assumed zero
for this analysis.
c See Table 4-19, Docket Item II-A-32.
d See Table 4-21, Docket Item II-A-32.
4-15
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TABLE 4-3
FUGITIVE EMISSION REDUCTION FOR THE SOURCES IN
POLYMERS AND RESINS MODEL PLANT
Emission
Source
VALVES
Gas
Light Liquid
Heavy Liquid
PUMP SEALS
Light Liquid
Heavy Liquid
SAFETY VALVES
OPEM-ENOEO LINES
COMPRESSOR SEALS
SAMPLING CONNECTIONS
FLANGES
TOTAL
Annual
Uncontrolled
Emissions,
Mg/ypa
19.7
32.6
1.1
12.6
5.6
10.0
0
4.0
3.4
17.5
106.4
Subpart Wb
14.4
19.2
0
7.6
0
10.0
0
4.0
3.4
0
58.7
Conwenter's
LDAR Program"
12.6
14.3
0
7.6
0
0
0
0
0
0
34.6
Texas/ LA
LDAR Program
12.6
0
0
0
0
5.9.
0
2.9
0
0
21.4
From Table 8-5, BIO Vol. I, p. 8-21.
Calculated by multiplying the annual uncontrolled emissions by the percent reductions shown in
Table 4-2.
4-16
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levels) for Subpart VV, the LDAR program described by the commenter, and
the LDAR programs of Texas and Louisiana. The incremental emission
reduction attributable to these standards decreases from 58.7 Mg/yr to
approximately 24 Mg/yr where the LDAR program described by the commenter
is in place1 and to approximately 37 Mg/yr where the Texas or Louisiana
LDAR program is in place. However, as discussed in the response to the
next comment, the reduced emission reduction attributed to these
standards does not make these standards cost ineffective.
Lastly, the commenters stated that no new major requirements are
applied to polypropylene plants in Louisiana or Texas. As seen in Table
4-1, there are differences between Subpart VV and the LDAR programs
(e.g., quarterly monitoring versus monthly) described by the commenters
and in the Texas and Louisiana regulations. In addition, the main
purpose of standards of performance is to require new sources, wherever
located, to reduce emissions to the level achievable by the best
technological system of continuous emission reduction considering the
cost of achieving such emission reduction, any nonair quality health and
environmental impact, and energy requirements...[(Section lll(a)(l)].
Where State LDAR programs are already in place, the impact of the NSPS
will be smaller than calculated. The State LDAR programs and the
systems chosen as the best demonstrated technology for this industry's
standards of performance for new stationary sources are not conflicting
types of control; therefore, where State LDAR programs apply, Subpart VV
will supplement them. The EPA has determined that existing State LDAR
program-level facilities that become subject to Subpart VV (e.g.,
through modification) can achieve the additional reduction required at a
reasonable cost.
Finally, it is important to note that Subpart VV is designed to
take into account the effect of other control programs and equipment
designs. It does this by providing alternate standards for low leak rate
This estimate is higher than the 15 Mg/yr stated by the
commenter. This difference is due to an inconsistency in Table 4,
p: 58i ?f the commenter's letter. A "differential control efficiency"
of 1.0 is indicated for safety valves. This means that the standard is
100 percent more effective than LDAR program referred to by the
commenter, and the emission reduction due to additional control should
from 159tor24VMr/U? ^ ^^' ™* increases the "mmenter's estimate
4-17
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equipment and plants. Thus, even if the overall reductions are
overstated, the standards are reasonable and appropriate.
4.3 COST EFFECTIVENESS
Comment:
One commenter (IV-D-8) stated that as a result of LDAR programs
currently in place or soon to be in place the emission reduction to be
obtained under Subpart VV will be less and concluded that the
incremental cost of further reducing already controlled leaks through a
more stringent LDAR program (i.e., Subpart VV) is substantially higher
than the cost of reducing emissions by initially applying Subpart VV to
an unregulated unit. The commenter stated that the cost effectiveness
of the regulation will increase due to this decrease in estimated
reductions obtained by the proposed regulation. The commenter estimated
annualized cost to now be $35,200 due to less credit received for the
VOC recovered (credit - 15.1 Mg/yr x $528/Mg), with incremental cost
effectiveness being $2,330/Mg reduced ($35,200/yr divided by 15.1
Mg/yr). This cost, the commenter pointed out, is 11 times greater than
the $208/Mg the Agency calculated in the proposed standard and is not
cost effective.
Response:
The incremental cost effectiveness of applying Subpart VV to
polymer manufacturing plants will vary depending on whether or not there
is a current LDAR program in place. In addition, where a LDAR program
is in place, the incremental cost effectiveness of applying Subpart VV
will vary depending upon the particular program in place. The Agency
agrees that the incremental cost effectiveness of applying Subpart VV to
polymer manufacturing plants complying with a LDAR program as described
by the commenter will be higher than if no LDAR program was in place.
However, as shown in the analysis below, the Agency also found that the
incremental cost effectiveness was lower when Subpart VV was applied to
polymer manufacturing plants complying with a LDAR program as described
in Texas' and Louisiana's regulations than if no LDAR program was in
place. (This unusual result occurs because EPA's analysis shows that
annual monitoring of valves and pumps in light liquid service is
ineffective, providing no emission reduction.) In either case, the
4-18
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incremental cost effectiveness of applying Subpart VV to polymer
manufacturing facilities is still reasonable even given the LDAR
programs referred to by the commenter. Therefore, no changes to the
fugitive emission standards have been made.
Analysis. As a first step in analyzing the incremental cost
effectiveness of applying Subpart VV to polymer manufacturing plants,
EPA compared Subpart VV with the LDAR program indicated by the commenter
and the LDAR programs described in the Texas and Louisiana regulations.
(Texas and Louisiana were selected because of the large number of
polymer manufacturing facilities located in the two states.) This
comparison was shown earlier in Table 4-1. The effectiveness of these
different LDAR programs on emission reductions were also shown earlier
in Table 4-2. As noted in the previous response, EPA calculated the
incremental emission reduction for each component that Subpart VV would
achieve over the other LDAR programs. In the absence of any LDAR
program, Subpart VV was estimated to reduce fugitive emissions by
approximately 59 Mg/yr from the model plant described in BID, Vol. I.
The Incremental emission reduction attributable to these standards
decreases to about 24 Mg/yr when compared to the LDAR program described
by the commenter and to about 37 Mg/yr when compared to Texas' or
Louisiana's LDAR program.
Having identified the incremental emission reduction attributable
to these standards, EPA next evaluated the incremental costs of applying
Subpart VV. With the one apparent exception for safety valves, the
commenter appropriately calculated the incremental emission reduction
from quarterly to monthly monitoring. However, the commenter failed to
do the same appropriate calculation for costs. In calculating their
cost effectiveness, the commenter divided the cost of monthly monitoring
vs. uncontrolled baseline situation by the incremental emission
reductiorr between monthly and quarterly monitoring. This is incorrect.
The incremental costs between quarterly and monthly monitoring must be
calculated. This result is then divided by the incremental emission
reduction to calculate the incremental cost effectiveness of going from
a quarterly LDAR program to a monthly LDAR program.
The Agency calculated the costs of the LDAR programs described by
the commenter and as identified in the Texas and Louisiana regulations.
4-19
-------
(Note: All costs are in 1980$). These costs are compared with LDAR
program costs associated with the proposed standards in Table 4-4. As
seen in Table 4-4, the cost of Subpart VV's LDAR program is more
expensive ($12,200 per year) than either the commenter's LDAR program
($4,000 per year) or the Texas/Louisiana LDAR program ($6,600) (and has
a higher average cost effectiveness than the commenter's LDAR program,
but a lower average cost effectiveness than the Texas/Louisiana LDAR
program). The incremental cost attributable to Subpart VV when the
commenter's LDAR Program is in place is about $8,200/yr and about
$5,600/yr where the Texas/Louisiana LDAR program is in place.
Using the incremental costs and incremental emission reductions,
the Agency calculated an incremental cost effectiveness of about $240/Mg
for applying Subpart VV where the commenter's LDAR program is in place
and about $150/mg where the Texas/Louisiana LDAR program is in place.
In both cases, the incremental cost effectiveness is still reasonable in
the Agency's view.
The following paragraphs describe in detail the before "VOC
Recovery Credit" cost differences between Subpart VV, the commenter's
LDAR program, and the Texas/Louisiana LDAR program. These differences
are summarized in Table 4-5.
1. Gas and light-liquid valves.
The installed capital cost ($2,300) represents the
initial leak repair. Since all three LDAR programs require
initial leak repair, this cost ($400/yr on an annualized
basis) is incurred by each program and the cost is the same.
Thus, there is no incremental cost associated with going to
monthly monitoring.
The operating labor for monitoring, leak repair,
administration, and support for the monthly program was
estimated at $14,200/yr. The quarterly program would require
less frequent monitoring and a lower repair effort. For
quarterly monitoring of both valves in gas service and in
light-liquid service, this cost was calculated to be
$8,000/yr. For quarterly monitoring of valves in gas service
and annual monitoring of valves in light-liquid service, this
cost was estimated to be $6,440/yr. The incremental cost of
4-20
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TABLE 4-4
FUGITIVE VOC LDAR PROGRAM COSTS
Cost Item
1. Installed Capital Cost
2. Annual Costs
a. Operating labor
including adminis-
tration and support
b. Maintenance
c. Miscellaneous
d. Annual i zed Capital
Cost
Total
3. VOC Recovery Credit3
4. Net Annual ized Cost
5. VOC Emission Reduction,
Mg/yr
6. Average Cost
Effectiveness, $/Mg
7. Incremental Cost
C •££****&> ,£..__ ** /«• K
BID, Vol. I
$66,800
$20,800
$5,700
$2,600
$14,100
$43,200
($31,000)
$12,200
58.7
208
-
EPA Analysis
Commenter's
LDAR Proaram
$12,900
$14,500
$3,000
$400
$4,400
$22,300
($18,300)
$ 4,000
24.1
166
237
Texas/Louisiana
LDAR Proqram
$13,600
$10,500
$3,000
$400
$4,100
$18,000
($11,300)
$6,700
21.4
313
147
(NOTE: All costs are in 1980 $.)
Emission reductions from Table 4-3 times $528/Mg of VOC reduced.
Net
Vol. 1 Net Annual i zed Cost - Subject LDAR Program Net Annual i zed Cost.
(BID Vol. 1 Emission Reduction - Subject LDAR Program Emission Reduction)
For Commenter's LDAR Program: ($12,200 - $4,000)/(58.69 - 24.1)
For Texas/Louisiana LDAR Program: ($12,200 - $6,600)/58.69 - 21.4)
4-21
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TABLE 4-5
COMPARISON OF LDAR PROGRAMS BY EQUIPMENT COMPONENT
LDAR PROGRAM
Cost Item
Valves
Initial Leak Repair
- Initial cost, $
- Annual i zed cost
Operating Labor
- Labor- hours/yr
- $ (at $18/hr)
Admi ni strati on/Support
- $ at 40% of
operating labor
Subtotal
Liaht-liauid oumo seals
Installed Capital Cost
Annual ized Capital Cost
Seal replacement cost
Operating Labor
- Labor-hours/yr
- $ (at $18/hr)
Administration Support
- $ at 40% of
operating labor
Subtotal
(Subpart VV
$2,300
$400/yr
562.7
$10,100/yr .
$4,040/yr
$14,500/yr
$1,400
$230/yr
$l,650/yr
260
$4,680/yr
$l,870/yr
$8,400/yr
Commenter's
LDAR Program
$2,300
$400/yr
317
$5,700/yr
$2,280/yr
$8,400/yr
$1,400
$230/yr
$l,650/yr
260
$4,680/yr
$l,870/yr
$8,400/yr
Texas/Louisiana
LDAR Program
$2,300
$400/yr
255.2
$4,600/yr
$l,840/yr
$6,840/yr
$1,400
$190/yr
$l,330/yr
71
$l,300/yr
$510/yr
$3,300
4-22
-------
TABLE 4-5 -- continued
COMPARISON OF LDAR PROGRAMS BY EQUIPMENT COMPONENT
Cost Item
ISubpart VV
LDAR PROGRAM
Commenter's
LDAR Program
Texas/Louisiana
LDAR Program
Gas Safety/Relief Valves
Installed Capital Cost
Annualized Capital Cost
Maintenance (at 5% of
capital cost)
Miscellaneous (at 4% of
capital cost)
Operating Labor
- Labor-hours/yr
- $ (at $I8/hr)
Administration/Support
(at 40% of operating
1abor)
Subtotal
$33,730
$6,550/yr
$l,690/yr
$l,350/yr
$9,590/yr
44.8
$806/yr
$323/yr
$l,130/yr
Compressor seals
Installed capital cost
Annualized capital cost
Maintenance (at 5% of
capital cost)
Miscellaneous (at 4% of
capital cost)
Operating Labor
- Labor-hours/yr
- $ (at il8/hr)
Admi n i strat i on/Support
(at 40% of operating
labor)
Subtotal
$6,400
$l,040/yr
$320/yr
$260/yr
$l,620/yr
$720
$120/yr
42.7
$770/yr
$310/yr
$l,200/yr
4-23
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TABLE 4-5 -- continued
COMPARISON OF LDAR PROGRAMS BY EQUIPMENT COMPONENT
Cost Item
Sampling Connections
Initial Capital Cost
Annual i zed Capital Cost
Maintenance (at 5% of
capital cost)
Miscellaneous (at 4% of
capital cost)
Subtotal
Leak Monitoring Equipment
Capital Cost
Annual ized Capital Cost
Maintenance
Miscellaneous
Subtotal
TOTALS
Capital Costs/Initial
Costs
Annual ized Capital Cost
(Control equipment,
initial leak repair)
Annual operating
(operating labor, admin-
istration and support,
maintenance, monitoring)
GRAND TOTAL
(Subpart VV
$13,800
$2,200/yr
$690/yr
$550/yr
$3,490/yr
$9,200
$2,100/yr
$3,000/yr
$400/yr
$5,500/yr
$66,800
$14,200/yr
$29,000/yr
$43,200/yr
LDAR PROGRAM
Commenter's
LDAR Proqram
-
-
-
-
$9,200
$2,100/yr
$3,000/yr
$400/yr
$5,500/yr
$12,900
$4,380/yr
$17,930/yr
$22,300/yr
Texas/Louisiana
LDAR Proqram
-
-
_
_
-
$9,200
$2,100/yr
$3,000/yr
$400/yr
$5,500/yr
$13,600
$4,140/yr
$13,860/yr
$18,000/yr
4-24
-------
the monthly program is thus estimated to be $6,200/yr for the
commenter's LDAR program and $7,800/yr for the Texas/Louisiana
LDAR program. Thus, for gas and light-liquid valves, the
annualized costs from the BID Vol. I estimates decrease by
$6,600/yr ($400 for annualized capital costs and $6,200 for
annual operating labor) for the commenter's LDAR program and
by $8,200/yr for the Texas/Louisiana program.
2. Light-Liquid pump seals.
According to the commenter's LDAR program, pump seals are
already monitored monthly. Since there is no difference, the
companies are already incurring the full cost of this portion
of the standards ($8,400/yr), and no incremental cost is
attributable to these standards. (The breakdown is $1,400 for
installed capital cost; $1,800 for annualized capital cost;
and $6,600 for operating labor, administration, and support).
The LDAR program described in Texas' and Louisiana's
regulations require annual monitoring (rather than monthly
monitoring). A total annualized cost of about $3,300 was
estimated for annual monitoring ($1,400 for installed capital
cost; $1,500 for annualized capital costs; and $1,800 for
operating labor, administration, and support). The
incremental cost of the monthly program is about $5,100/yr.
3. Gas safety/relief valves.
Under the commenter's LDAR program, these valves are not
controlled. In this case, the $9,600 annual costs of control
are attributable to these standards. The Texas/Louisiana LDAR
programs do control these valves, requiring quarterly
monitoring. The cost of quarterly monitoring is about $1,130
per year (all operating labor, administration, and support).
Thus, the incremental cost of the standards is about
$8,500/yr.
4. Compressor seals.
The commenter's LDAR program does not control these
sources of fugitive emissions. Thus, the $1,600 annual costs
4-25
-------
are attributable to the standards. The Texas/Louisiana LDAR
programs do control compressor seals, requiring quarterly
monitoring. The cost of quarterly monitoring is about
$l,200/yr ($120 annualized capital costs, $1,080 for
operating, administration and support). Thus, the incremental
cost of the standards is about $400/yr.
5. Sampling connections.
Since the other LDAR programs do not address these
fugitive emission sources, no costs are attributed to their
programs, and the entire $3,500 annual costs are attributed to
these standards.
6. Leak monitoring equipment.
Since companies are currently subject to a LDAR program,
they will have already purchased leak monitoring equipment.
Thus, these programs incur the associated costs ($2,100/yr for
annualized capital cost; $3,000/yr for maintenance; $400/yr
for miscellaneous; and a capital cost of $9,200). The cost of
this equipment can not be attributed to these standards on an
incremental basis.
Comment:
One commenter (IV-D-8) requested that the monitoring frequency be
reduced for already controlled polymer plants in order to make the
regulation more cost effective. This change, the commenter said, should
specifically address those plants already covered by a state program or
that use newer technologies.
Response:
The Agency does not disagree that reduced monitoring frequencies
have, in general, lower costs. However, as seen in the response to the
previous comments, lower monitoring frequencies do not necessarily have
more favorable cost effectiveness levels. In addition, as seen in the
response above, monthly monitoring programs for each type of emission
source are incrementally cost-effective even where existing LDAR
programs are in-place. Furthermore with regards to valves in
particular, companies that use newer valve designs (and thus presumably
have very low leak frequencies) can perform annual monitoring for valves
4-26
-------
if they chose to comply with Section 60.483-1. For the reasons stated
earlier, the Agency believes the skip period provisions for valves are a
reasonable way to allow companies the opportunity to extend their
monitoring frequency if they do not wish to comply with Section 60.483-
1. Finally, Section 60.484-8 provides owners and operators with the
opportunity to demonstrate equivalent means of emission limitation for
demonstrating compliance. For these reasons, the Agency has retained
•the monitoring frequencies as currently stated in Subpart VV.
4.4 APPLICABILITY OF LEAK DEFINITION
In Section 60.482-2(b) of Subpart VV, there are two definitions of
when a leak is detected: (1) "If an instrument reading of 10,000 ppm or
greater is measured" and (2) "If there-are indications of liquids
dripping from the pump seal." Since proposal, the Agency has learned of
certain polymer pumps are designed to purge polymer fluid from bleed
ports, thereby allowing small quantities of VOC emissions to escape to
the atmosphere (see Docket'Item IV-B-25). These pumps must use the
polymer fluid to provide lubrication and/or cooling of the pump shaft.
While the Agency believes that "indications of liquids dripping from the
pump seal" should not be applied to such pumps, the 10,000 ppm or
greater definition should be retained to ensure these pumps are not
emitting significant quantities of VOC. Further, the Agency does not
believe that this exemption should be applied to "new" or replaced
pumps, because there are pumps available that do not have this designed-
in purge. Therefore, the final rule exempts purging from bleed ports in
existing pumps that must have such ports from the "indications of liquid
dripping" definition until the pump is replaced or reconstructed [see
Section 60.562-2(a)(l)].
4-27
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-------
5.0 MODIFICATION/RECONSTRUCTION
Comment:
Two commenters (IV-D-8, IV-D-10) stated that, in determining
whether a process change is considered a "modification," the emission
rate should be based on the mass of emission per mass of product. One
commenter (IV-D-10) noted that this definition should be consistently
maintained throughout the standards and the preamble. The other
commenter (IV-D-8) noted that, in the Federal Register notice on page
36700, the definition of modification is "... change to an existing
facility that increases the emission rate of any pollutant to which a
standard applies." This commenter pointed out that this wording is not
consistent with the definition of modification contained in 40 CFR Part
60, Subpart A - General Provisions, whereby the rate is not included.
The commenter noted that the use of emission rate throughout the
Preamble and Subpart ODD provides a definition of mass of emission/mass
of product for emission rate rather than mass of emission/unit time.
According to the commenter, this distinction is important in determining
an "affected facility" for process changes that may increase a unit's
production capacity without increasing the emission rates on a mass/mass
basis. To ensure clarity, the commenter suggested that the language in
the preamble and in Subpart ODD (Section 60.561 - Definitions") be
worded to include this view of emissions with the focus on rate from a
mass of VOC/mass of product produced basis.
Response:
Commenter IV-D-8 is only partially correct concerning the
inclusion or exclusion of the term "rate" in the General Provisions for
determining when a modification has occurred. "Rate" is not included
under Section 60.2, Definitions, where modification is defined, in part,
as "any physical change in, or change in method of operation of, an
existing facility which increases the amount of any air pollutant
emitted into the atmosphere ... ." However, under Section 60.14,
Modification, increases in the amount of any air pollutant is further
clarified by stating, in part "... any physical or operational change to
an existing facility which results in an increase in the emission rate
to the atmosphere of any pollutant ...." (Emphasis added.) Emission
5-1
-------
rate is then defined in Section 60.14(b) as being expressed as kilograms
per hour (kg/hr). Thus, it is the intent of the General Provisions to
have those situations where the absolute levels of a pollutant (as
expressed in terms of kg/hr) increase become subject to the applicable
NSPS.
The commenters seem to presume that the emission levels used for
determining when a modification has occurred and the emission limits
associated with a standard must be expressed in the same format (i.e.,
mass per unit of time or mass per mass of production). This is
incorrect. The formats used are based on different objectives. Under
the Clean Air Act, changes in the absolute level of emissions to the
atmosphere are an important factor for determining whether a NSPS should
be applied to an existing source. The intent is to prevent increases in
the emissions from existing sources that are increasing emissions.
Thus, a format that identifies the absolute amount of emissions being
emitted, such as kg/hr, achieves this objective. On the other hand, a
format that uses kg of VOC per kg of product, as suggested by the
commenters for this standard, would not achieve this objective, because
it would allow existing sources to increase emissions to the atmosphere
while keeping its mass emissions per mass production rate constant.
(Note that under either format, an increase in production rate of an
existing facility is not a modification if that increase is accomplished
without a capital expenditure on that facility [Section 60.14(e)(2)]).
The formats associated with performance standards, on the other
hand, are selected to reflect the performance capabilities of the
applicable control technologies. As discussed in the preamble to these
proposed standards, several formats were considered. The Agency
determined that, in some instances, a percent emission reduction format
and, in other instances, a mass VOC per mass production rate format best
reflected the performance capabilities of the applicable control
technologies. In addition, the uncontrolled threshold emission levels
were also expressed in terms of mass VOC per mass production. Since
then, the Agency has revised the threshold levels associated with the
polyolefins to reflect mass emissions per unit of time emission rate.
In summary, the emission level or limit formats associated with
determination of modifications and standards of performance do not need
5-2
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to be the same. The format suggested by the commenter for emissions for
determining whether a modification has occurred could result in less
emission reduction than provided by the General Provision's definition
and it is not the intent of these standards to do so. For these
reasons, the Agency has rejected the commenter's suggestion to redefine
modification in these standards.
Comment:
One commenter (IV-D-47) referred to 54 FR 893 in which is stated:
"Under the new approach, any existing process section that is modified
or reconstructed becomes an affected facility subject to the proposed
standards. Similarly, any newly constructed process section at an
existing plant or a new plant would be an affected facility...". The
commenter then stated that the impact of these statements is unclear
where an existing process section that is modified or reconstructed
becomes an affected facility subject to the proposed standards, yet that
modification or reconstruction results in increased emissions only in
another section. The commenter asked how the standards are to be
applied in this situation.
Response:
Modification or reconstruction to a process section only affects
that process section regardless of the effect on emissions in other
process sections. A process section is "modified" if a physical change
occurs to the facility or there is an operational change to the facility
either of which results in an increase in the emission rate. In the
example provided by the commenter, the modified process section would
not become an affected facility because there is no increase in
emissions from that process section. Assuming the other process section
is not modified, as defined, then it is not considered to be an affected
facility even though there is an increase in emissions.
A process section is "reconstructed" if the replacement of
components in the existing facility occurs so that the fixed capital
cost of the new components exceeds 50 percent of the fixed capital cost
that would be required to construct a comparable entirely new process
section and it is technology and economically feasible to meet the
applicable standards. The definition of reconstruction does not depend
on an increase in emissions. Thus, in the example provided by the
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commenter, if the first process section is reconstructed, then it
becomes an affected facility subject to the standards regardless of the
fact there has been no increase in emissions. (Note: This is also true
even if a decrease in emissions occurs.) As before, if the process
section in which emissions do increase does not undergo replacement of
components so as to constitute a reconstruction, then that process
section is not an affected facility and is not s;ubject to the standards.
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6.0 MONITORING REQUIREMENTS
6.1 GENERAL
Comment:
One commenter (IV-0-8) stated that the Agency is requiring very
specific types of monitoring devices in the proposed standards and
certain types of devices (for example, concentration monitors for carbon
absorbers) that do not have proven performance standards and their
output is not used for compliance monitoring. The commenter believes
that the choice of not only what and how to monitor but where to monitor
in the process should be left up to the owner/operator and can result in
a control strategy that anticipates and prevents mistakes, rather than
just providing for alarms or after-the-fact information gathering. The
commenter further believes that the selection of monitoring devices is
better left to the discretion of the manufacturers. In cases where
performance proven devices are required for compliance, the commenter
recommended reworking the standard to encompass a specific device of
other proven or provable technology.
Response:
The General Provisions [40 CFR 60.13(i)] state that the
Administrator may approve the use of "alternatives to any monitoring
procedures or requirements in this part... ." This is applicable to all
NSPS and the citing of specific monitoring requirements in this subpart
does not preclude an owner or operator from seeking approval of
alternative monitoring procedures or requirements.
The commenter makes several statements that need to be addressed.
First. The commenter refers to concentration monitors for carbon
adsorbers as not having proven performance standards and that their
output is not used for compliance monitoring. The commenter is correct
on both points, but misses the intent of monitoring requirements in this
Instance. If the purpose of the concentration monitors was to indicate
the compliance status of the affected facility, the Agency agrees that
it would be an inappropriate compliance monitoring technique because it
lacks proven performance standards. However, the intent of the
monitoring requirement is to provide an indication that an affected
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facility mav be out of compliance and not that it is out of compliance.
Historical monitoring data can be used to identify control devices that
may not be operating properly and this information may be used by EPA,
State, or local enforcement officials to decide when a performance test
is warranted. Given the intent of the monitoring requirement, the fact
that the output is not used for compliance monitoring is irrelevant.
Concentration monitors and their output are sufficient in quality and
type to provide an indication that an affected facility may be out of
compliance.
Second. The commenter stated that they believe the choice of
what, how, and where to monitor should be left up to the owner or
operator and that the selection of monitoring devices is better left to
the discretion of the manufacturers. The Agency has considerable
experience with the control devices that can be used for complying with
these and other standards, and with various monitoring devices that can
be used to monitor the performance of the control device. Thus, the
Agency believes it is fully capable of identifying appropriate
monitoring devices and locations. Nevertheless, new technologies come
along or unique situations occur that may not be covered by a rule. In
such situations, the owner or operator may request (as noted earlier)
for approval of alternative monitoring procedures or requirements.
Third. The commenter suggests that monitoring procedures or
requirements can be implemented by the owner or operator that anticipate
and prevent mistakes, rather than provide for "alarms or after the fact
information gathering." The Agency encourages all control schemes,
including monitoring procedures, that help prevent process equipment and
control devices from malfunctioning. However, while such control
schemes may reduce the times when a facility is out of compliance, they
may not necessarily guarantee compliance at all times. As stated
earlier, the purpose of the monitoring requirements is to provide an
indication that a facility may be out of compliance. This purpose may
not be accomplished by schemes tha-t "anticipate and prevent mistakes."
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6.2 NEED FOR FLOW MONITORS
Comment:
Four commenters (IV-D-5, IV-D-6, IV-D-7, IV-D-8) questioned the
need and desirability of requiring flow measuring devices on vents to
• control equipment. According to the commenters, this will add
significant cost, provide no useful data, and add to the burden of
recordkeeping. One commenter (IV-D-6) specifically wondered how the
flow monitoring data would affect the control of emissions. This
commenter also stated that the flare requirement portion of the fugitive
emission standard (40 CFR Part 60 - Subpart VV) does not require flow
monitoring devices.
Two commenters (IV-D-7, IV-D-8) maintained that flow measurement
on intermittent vents'will be especially valueless since it will be
difficult to differentiate between true no-flow situations and
instrument problems. Two of the commenters (IV-D-7, IV-D-8) stated that
installation of flow devices in a process flare system that also serves
as a safety flare is not a good practice from a maintenance or safety
standpoint. One commenter (IV-D-8) stated further that the temperature,
density, pressure, and fouling or corrosive characteristics of flared
gases tend to cause maintenance and reliability problems on flow
measuring elements that are placed into the flare gas line. Commenter
IV-D-8 noted that while external measurements devices are available,
they are expensive and certainly should not be required on each
individual vent stream into the flare gas header. This commenter also
claimed that measuring every flare gas vent stream flow is not possible,
with even single stream flare gas flow measurements being notoriously
difficult to measure.
One commenter (IV-D-6) stated that technical problems exist for
retrofit of modified facilities where emergency vent systems are
integrated with normal process vent streams, because the range of flow
rates makes accurate measurement of lower flows impossible without
causing excessive restrictions to emergency ventings.
Commenter (IV-D-8) suggested that Sections 60.563(a)(2), (b)(2),
and (c)(2) of the September 30, 1987, Federal Register notice, which
require the installation of a flow indicator to provide a record of the
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vent stream flow to the incinerator or flare, be deleted. All four
commenters felt that engineering estimates and design calculations of
the vent flows should be adequate to ascertain compliance with flare
flow allowable ranges.
One commenter (IV-D-5) recommended that a requirement for an
engineering piping report be substituted for the flow instrument
requirements for flares. This commenter believes that an engineering
report describing the piping arrangement for the vent streams would
provide assurance that these streams will be continuously flared. Such
a report, the commenter said, would achieve the same objective as the
flow instrument requirement by showing that the vent streams are "hard
wired" (no physical possibility of an atmospheric release prior to the
flare) without the burden of installing, operating, and maintaining a
large number of flow recorders.
Response:
The EPA considers it very important to ensure that vent streams
are continuously vented to the flare (or other control device). The
primary intent of the flow monitoring requirement was to provide a means
for Indicating when vent streams were bypassing the flare or other
control device. In the September 30, 1987, Federal Register notice,
flow indicators were proposed. Flow indicators envisioned by the Agency
would simply provide an indication of flow/no flow, and need not provide
quantitative estimates of flow rates. The Agency has reevaluated the
use of flow indicators as proposed and in light of the comments
received. This revaluation has led the Agency to the following
conclusions.
1. Flow meters, which provide quantitative estimates of flow
rates, could be one way to ensure emissions are vented to a
control device. However, as pointed out by the commenters,
there may be technical problems and less expensive ways to
achieve the same goal.
2. Flow i-ndicators located on the vent pipe between the emission
source and the control device by themselves may be
insufficient to-meet the intent (even though this was what was
proposed).
3. Engineering reports that show an emission stream is "hard
piped" to a control device is a less expensive method than
flow meters to ensure the entire flow will be vented to the
control device. Other piping arrangements can be used, but
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car seals on valves or flow indicators located immediately
downstream of each valve that could divert a portion of the
flow to the atmosphere, either directly or indirectly, become
necessary.
Considering the above conclusions, the Agency is now requiring an
engineering report that describes the piping arrangement for venting the
affected emission streams to the control device. If any valves are
present in the line between the source and the control device, the rule
requires them to be car-sealed opened. In addition, all valves that
allow emissions to bypass the control device are required to be car-
sealed closed. The monitoring requirements have been revised now that
this engineering report is required. An owner or operator may elect to
follow one of two methods for monitoring the vent system. One method
would require monthly inspection of the valves to inspect the car seals,
the reporting and recording of any time the car seals are broken, and
the recording and reporting of any time the valve position has changed.
The other method would require the installation of a flow indicator,
which gives an indication of flow/no flow, at the closest downstream
point of each valve that is required to be car-sealed closed. The owner
or operator is to record all periods of flow (which indicates a portion
of the emission stream is bypassing the control device) and report such
periods of flow.
Comment:
One commenter (IV-D-6) pointed out inconsistencies in the wording
of the proposed standard as stated in Section 60.563. The commenter
pointed out that (1) the preamble states that if a flare is used to
comply with the proposed standards, a flow indicator must be installed
and operated to provide a record of vent stream flow to the flare for
each vent stream (52 FR 36701); (2) the regulation (Section 60.563(b)(2)
of the September 30, 1987, Federal Register notice) states that a flow
indicator be provided to record vent stream flow to the flare at least
once every hour for each affected facility; and (3) the regulation
(Section 60.563(c)(2) of the September 30, 1987, Federal Register
notice) states that a flow indicator be provided to record vent stream .
flow to the flare for each affected facility. This commenter felt that
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these inconsistencies in wordings would cause considerable ambiguity and
inconsistency in application of the regulations.
Another commenter (IV-D-5) stated that the actual requirement for
the installation of an indicator of vent stream flow to continuously
monitor flow rates to a flare contradicts the preamble which says the
installation of an indicator of vent stream flow is not to continuously
monitor exit gas velocity, but rather to ensure that the vent streams
are continuously flared.
Response:
The commenters are referring to Sections 60.563(b)(2) and (c)(2)
of the proposed rule concerning monitoring requirements when a flare is
used for the installation of a "flow indicator that provides a record of
vent stream flow to the flare for each affected facility." As noted in
the previous response, the record of vent stream flow to the flare (or
other control device) is no longer required. Although the placement of
the flow indicator has been changed, the record of vent stream flow need
only be a yes/no type of indication and not a measurement of velocity or
other quantitative measurement.
Comment:
One commenter (IV-D-6) stated that the proposed vent stream
monitoring requirement under Section 60.563 specifying flow monitoring
on each vent stream at a point closest to the inlet of the control
device and before being joined with any other vent stream is ambiguous
in that it is unclear if multiple vent streams from a process section
listed as an affected facility must each be monitored or collected and
monitored, or if all vent streams from all affected facilities be
collected separately for a single point monitoring.
Response:
This comment is no longer relevant as the location of the flow
indicators has been changed. To ensure that vent streams do not bypass
the flare, the EPA now requires an engineering report depicting the
piping used to vent each affected emission stream to the flare or other
control device. This report will show, in part, all individual vents
and where they are joined. Where flow indicators are used for
monitoring, they are now placed in a different location to identify
periods when there has been flow away from the control device.
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Comment:
One commenter (IV-D-49) stated that flow monitoring requirements
need greater flexibility due to the lack of instrumentation that is
accurate over a wide range of flowrates. This commenter suggested that,
rather than hourly recordings at individual points, the Agency should
allow some choice in the placement and accuracy of the flowmeters.
According to the commenter, this would still provide EPA with the
information needed for enforcement and environmental protection, yet
give the affected plants a more practical, less-costly means of ensuring
compliance.
Response;
As noted above, engineering reports now replace flow indicators as
the primary means for ensuring emissions are vented to the control
devices. Where flow indicators are used for monitoring the vent system,
they are now located downstream of valves that could allow emissions to
bypass the control device. These flow indicators need only show a
yes/no type of indication, and not a quantitative measurement of flow.
Whether in this new location a wide range of flow rates would be
observed, "the lack of instrumentation that is accurate over a wide
range of flowrates" is not a concern.
At proposal, the Agency proposed that hourly recordings of flow to
the control device be required. In the final rule, the location of the
flow indicators has been moved so that the flow indicators provide an
indication of times when flow is being diverted to the atmosphere. The
Agency believes that more frequent collection of flow/no flow data is
appropriate when the purpose of the monitoring is to detect flow to the
atmosphere than to a control device. Thus, the final rule requires flow
indicators to be equipped to indicate and record whether or not flow
exists at least once every fifteen minutes (rather than once every
hour). If an owner or operator feels that an alternative frequency or
placement of a flow indicator is as appropriate, then the owner or
operator can petition the Administrator as provided in the General
Provisions to use an alternative monitoring scheme.
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6.3 THERMOCOUPLES AND FLAME MONITORING
Comment:
Two commenters (IV-D-6, IV-D-8) pointed out that the preamble
clearly states that thermocouples is the only acceptable monitor, while
the standard allows for a thermocouple or similar device. The
commenters requested that this confusion be eliminated from the rule.
Four commenters (IV-D-6, IV-D-7, IV-D-8, IV-D-49) requested that a
provision for any other equivalent devices capable of detecting a flame
be allowed with the regulations (Sections 60.563(b)(l) and (c)(l) of the
September 30, 1987, Federal Register notice). One commenter (IV-D-8)
referred to the general provisions of the National Emission Standards
for Hazardous Air Pollutants (NESHAP) rules where thermocouples or
equivalent devices are required. This commenter suggested that visual
inspection combined with an assessment of the reliability of the fuel
supply to the pilot be allowed as an equivalent pilot flame detection
system. The commenter also pointed out that remote sensors of various
types are available and can be used, but should not be required as these
types of sensors have reliability and citing problems as well.
Commenter (IV-D-6) stated that there are other techniques (e.g.,
flame ionization detectors and remote infrared scanners) that have been
proven to be just as reliable as thermocouples. The commenters stated
that the final rule should allow individual plants to select alternate
flame sensors as the point of the regulation should be to require a
pilot detection system (i.e., thermocouples, flame ionization detectors
and remote infrared scanners) capable of detecting a flame. Commenter
IV-D-6 pointed out that other NSPS have already allowed these options.
Commenter (IV-D-8) suggested the following language to replace the
current language in Sections 60.563(b)(l) and (c)(l) of the
September 30, 1987, Federal Register notice: The presence of a flare
pilot flame shall be monitored using a thermocouple or any other
equivalent device to detect the presence of a flame.
Response;
The preamble for the proposed rule should not have stated so
distinctly that thermocouples were the only acceptable monitor. Other
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similar devices are acceptable provided they, provide the necessary
recordkeep i ng requ i rements.
The presence of a flame is obviously critical to the operation of
a flare as a control device. The intent of the flare monitoring
regulation is to require a reliable monitoring device on the flare that
will indicate when there is no flame present and thus when the flare is
not operating; or in the case of intermittent emissions, not in a ready
state to control emissions. For flares controlling continuous
emissions, monitoring of the flare flame or pilot light flames is
appropriate to ensure the vent stream is being destroyed. For flares
controlling intermittent emissions, a flare flame will not always be
present. Thus, for these flares, it is important to monitor the pilot
light flames.
Thermocouples are generally accepted as the most reliable means to
monitor the presence of a pilot flame. For flares controlling
intermittent emissions alone, it is important to ensure that the pilot
lights are lit (i.e., have a flame present). Thus, the standards
require such flares to monitor the pilot light flames using a
thermocouple or equivalent monitoring device. For flares controlling
both intermittent and continuous emissions or continuous emissions
alone, the EPA has decided that the use of certain optical devices is
also acceptable to indicate the presence of a flame (either the flare
flame or pilot light flames). Ultra-violet or infrared beam sensors may
be used in lieu of thermocouples for these flares. These devices offer
an advantage over thermocouples because they may be installed remote
from the flare tip thereby allowing maintenance to be done without
shutting down the flare. It is important that these optical devices be
installed properly to minimize the effects of solar radiance. Although
these devices may have difficulty in distinguishing the pilot flame from
the main flame, the detection of a flame fulfills the intent of the
regulation for flares used to control both continuous and intermittent
emissions or continuous emissions alone.
The detection of flame presence by visual means or by remote video
camera is not a suitable method of monitoring. If a flame is operating
smokelessly, it can be difficult to determine if a flame is present.
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Flame ionization detectors are not considered as reliable as other
monitoring technologies. The experience of one flare manufacturer (see
Docket Item IV-0-54) showed major problems with the accumulation of
moisture on the flame rod, which tended to ground the flame rod and then
lock up the system. Further, this manufacturer found that the formation
of small amounts of carbon in the pilot flame and its accumulation
around the base of the flame rod also tended to "ground out" the flame
rod and lock up the system.
The EPA is willing to take into consideration any operating
records or test data for alternative monitoring devices.
Comment;
Four commenters (IV-D-6, IV-D-7, IV-D-8, IV-D-49)) stated that
thermocouples are known to be unreliable when placed in the severe
operating environment at the top of a flare and that the flare tip
maintenance period can typically be much longer than the service period
for a thermocouple. The commenters then asked what needs to be done
when a pilot flame thermocouple burns out. Is the flare to be shut down
prior to the regular maintenance to replace the pilot thermocouple? The
commenters pointed out that since flares are emergency relief devices,
taking a flare out of service can not usually be done without taking the
entire process which the flare services out of service and that more
emissions would undoubtedly result from premature flare maintenance
related to thermocouple burnout. Commenter IV-D-49 also stated that
thermocouples can be difficult to replace.
Response:
Recent improvements in thermocouple installation technology have
extended the operating life of thermocouples in flare monitoring
service. If a thermocouple is sheathed within a thermowell, the
thermocouple is protected from the severe flame environment, and the
thermocouple operating life can be extended to approximately the same
length of time as the flare tip maintenance period. Installing a
thermocouple with thermowell will reduce significantly the number of
times an operator must decide whether to shut down upon thermocouple
failure.
Any breakdown or malfunction of the thermocouple should be
repaired as soon as practicable as stated in Section 61.14(b) of the
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General Provisions. The operator is expected to determine the best time
to shut the flare down after considering how to minimize emissions both
for safety and environmental reasons.
6.4 INCINERATORS
Comment:
One commenter (IV-D-8) stated that the regulation should not
attempt to limit the option of using any proven or provable technique
for monitoring emissions from incinerators.
Response:
As noted earlier, the General Provisions [40 CFR 60.13(1)] state
that the Administrator may approve the use of "alternatives to any
monitoring procedures or requirements in this part...". This is
applicable to all NSPS and the citing of specific monitoring
requirements in this subpart does not preclude an owner or operator from
seeking approval of alternative monitoring procedures or requirements.
Comment:
One commenter (IV-D-7) believes that the requirement for measuring
Incinerator temperature is sufficient to ensure that the incinerator is
operating as required, and that material balance and engineering
calculations can be used to determine if residence time is sufficient.
Response:
The commenter appears to be referring to the monitoring
requirements from incinerators rather than suggesting an alternative to
the performance test. The monitoring requirements proposed for
incinerators were a temperature monitoring device and a flow indicator
In each vent stream to the incinerator. The Agency has determined that
firebox temperature alone provides an adequate indication of incinerator
performance. The final rule now requires that only the temperature of
the incinerator be monitored. An engineering report that describes the
piping arrangement for venting the vent stream to the incinerator has
replaced the placement of flow indicators within the piping that vents
the vent stream to the incinerator.
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6.5 CARBON ADSORBERS
Comment:
One commenter (IV-D-8) concurs with the concept of leaving
flexibility in the standards for case-by-case selection of alternative
for adsorbers. However, the commenter believes that since the required
organic concentration monitors with recording devices on carbon bed
adsorbers are not intended for compliance determinations, but rather as
status indicators, it makes more sense to leave the type of
concentration monitor to the owner/operator of the process. The
commenter listed such alternatives as in-line gas chromatography, bagged
grab samples, or time or flow proportional sampling as all providing
equivalent information of status of a carbon bed. The commenter stated
that these techniques can also be used for developing the required
maintenance history. The commenter also suggested along the same lines
that the record of testing and monitoring could be a recorder, lab
analysis record, etc. The commenter proposed the following language for
Sections 60.563(e)(l)(11), (e)(2)(ii), and (e)(3)(i): "An organic
monitoring device used to indicate the concentration level of organic
compounds based on a detection principle such as infrared,
photoionization, thermal conductivity, or other equally effective device
or monitoring scheme."
Response:
The Agency has revised the wording of the paragraphs referred to
by the commenter so that detection principles such as infrared,
photoionization, and thermal conductivity are identified specifically.
These paragraphs have been reduced in the final rule to a single
paragraph -- 60.563(a)(4). The Agency agrees that these types of
monitors provide equivalent information on the status of the carbon bed.
Each of the monitors would be still required to be equipped with a
continuous recorder. The Agency has not included "or other equally
effective device or monitoring scheme" in Section 60.563(a}(4) because
the General Provisions allow for such to be used upon approval by the
Administrator and it thus is unnecessary to include such language in
this subpart. Should they be demonstrated to be equally effective, the
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use of bagged grab samples or time or flow proportional sampling could
be used if shown to be equivalent as provided in the General Provisions.
6.6 COSTS
Comment:
Two commenters (IV-D-6, IV-D-8) expressed concerns over flow
monitoring costs. Commenter IV-D-6 stated that the cost justification
of providing vent stream monitoring is unclear. Commenter IV-D-8 stated
that while the cost of an individual flow monitor may be small compared
to the overall cost of controlling emissions, the cost of monitoring the
tens of vent streams that can feed an incinerator is not insignificant.
This commenter felt that the cost of monitoring flows on each vent
stream was not adequately addressed in the economic analysis of the
proposed rule because flow monitoring is not necessary for efficient
operation of an incinerator and flow indication is not used for
compliance purposes.
Commenter IV-D-8 also believes that the cost of installing flow
monitors on every vent stream entering boilers or process heaters is too
high to justify the inclusion of this requirement into the standard and
suggested that Section 60.563(d)(l) of the September 30, 1987, Federal
Register be deleted. This commenter concurred with Section 60.563(d)(3)
in that notice in which the owner/operator can use his or her own
discretion on choosing the most efficient monitoring methods for boilers
or process heaters with 150 million Btu/hr or greater heat input design
capacities.
Response;
Owners or operators are no longer required to monitor flow on each
vent stream to a control device; an engineering report is being required
instead. Under the final rule, an owner or operator may elect to
monitor the vent system through the use of flow indicators, a car-seal
monitoring program, or a combination of the two (see Section 60.563(d)
of the final rule). If flow indicators are used, they are now to be
placed downstream of each valve that could divert the emission flow away
from the control device to the atmosphere, either directly or
indirectly. In the Agency's estimation, the cost of installing such
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flow indicators is reasonable in light of the information it provides
(periods of time when flow is being diverted from the control device).
An owner or operator can elect to use an alternative method subject to
the approval of the Administrator if it is shown to be equivalent under
the General Provisions.
In establishing the monitoring requirements; for this (or any
other) NSPS, EPA had to reconcile the need to ensure the effective
operation of control and product recovery devices and compliance with
the rule with the degree of complexity and economic burden of the
monitoring systems on the industry. The Agency believes that it has
chosen the most reliable and fair methods of monitoring. Considering
the complexity of the processes involved and the burden on both EPA and
industry, the monitoring and reporting methods specified are believed to
be the least burdensome way of providing EPA with reliable information
about changes in combustion device operation or diversion of flows that
could lead to increased VOC emissions and to ensure the proper operation
and maintenance of product recovery devices.
6.7 MODIFICATION/RECONSTRUCTION
Comment;
Two commenters (IV-D-44, IV-D-50) stated that language in the
January 10, 1989, Federal Register notice appears to require monitoring
of existing continuous emission streams prior to any modifications or
reconstructions. The commenters believe that a monitoring requirement
would raise the following concerns or questions:
• Determination of emissions prior to modification by sampling
is not appropriate because emissions may vary with product
runs, and the worse case product may not be available for
monitoring within a reasonable time. These emissions can be
calculated with reasonable accuracy. (IV-D-44)
• What is the economic justification/basis for requiring testing
of existing streams as opposed to calculating? (IV-D-44, IV-
• What test method, duration, frequency and monitoring are
contemplated? (IV-D-50)
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• For processes that make a wide variety of products, what
product line emissions (different hydrocarbon constituents,
product densities, etc.) should be measured? (IV-D-50)
What is the environmental benefit of requiring testing of
existing streams? (IV-D-50)
The commenters pointed out that Table 4 "Procedure for Determining
Control and Applicable Standard for Continuous Emission Streams from
Modified or Reconstructed Polypropylene and Polyethylene Affected
Facilities" (Ref: 54 FR 908) specifies in Step 3 that calculations of
VOC concentration in the applicable weight percent range should be made
before and after any modification or reconstruction. The commenters
requested clarification of this issue (monitoring vs. calculation) and
recommended engineering calculations as specified in Table 4 of emis-
sions before and after any modification or reconstruction be used in the
procedural step in determining control requirements. The word "measure"
on Page 54 FR 895 should be changed to "calculate," according to
commenter IV-D-44.
Response:
The language in the preamble to the January 10, 1989, Federal
Register notice did not intend to imply that monitoring of existing
continuous emissions was being required, although the language was not
as precise as it should have been. In that notice, the Agency intended
that measurements rather than calculations be used to obtain the VOC
concentrations of each applicable VOC stream. Measurement of the
applicable stream would occur after a modification or reconstruction
determination has been made by the appropriate enforcement Agency, but
before any actual changes have been undertaken. This clarification
narrows the language in the preamble from "any changes to an existing
process section that could conceivably be a modification or reconstruc-
tion" to only those that are determined to be a modification or
reconstruction.
In the final rule, the requirement to measure the VOC concentra-
tion or the annual emission rate rather than calculate these values is
applied to only those individual streams that an owner or operator seek
to exempt from control through either the VOC weight percent exemption
or the low annual emissions exemption (see Section 60.564(d) of the
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final rule). As provided in the General Provisions, if an owner or
operator believes that an alternative procedure is as accurate as a
measurement, then the owner or operator may still petition the
Administrator for approval.
While the Agency would prefer actual test data, the final rule
allows an owner or operator to submit calculations calculating the
weight percent and annual emissions of each nonexempt vent stream in
lieu of .actual test data, provided such calculations can be demonstrated
to be sufficiently accurate as to preclude the necessity of a test.
In testing or calculating the weight percent and annual emissions
of a vent stream, an owner or operator is required to evaluate the
stream under representative conditions of normal operating conditions.
This may require an owner or operator to make assumptions or estimations
of how the affected facility will be operated or how emission streams
will vary during production of various products. The period during
which testing of a stream occurs, thus, need not be a "worst case"
product, but preferably a representative product. Where affected
facilities are used to produce a wide variety of products, then an owner
or operator would calculate (or measure) the emission streams that would
occur during the course of a year for each of the products. The
resulting data would be combined to identify composite streams and their
weighted average VOC concentrations and total annual emissions. Each
composite stream's VOC concentration would then be used to calculate the
threshold emission rate and a control/no control determination would be
made by comparing the calculated (or measured) annual emissions with the
threshold emission rate.
Where an owner or operator tests an emission stream, the final
rule requires the use of Test Method 18 to determine the VOC concentra-
tion and Test Method 2, 2A, 2C, or 2D, as appropriate, to determine the
volumetric flow rate. Each test shall consist of three 1-hour runs in
which either an integrated sample or four grab samples shall be taken.
In determining whether a test or calculation is to be required,
the Agency considers a number of factors such as the use of the
information, the relative cost of conducting the tests, and the
availability of alternative procedures. Because the individual stream
exemptions allow an individual stream to be exempt from control under
this NSPS, the Agency believes this decision needs to be made based on
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test data. For nonexempt streams, a no control decision may change to a
control decision as more facilities at a plant are constructed,
modified, or reconstructed. Thus, while test data are preferable for
determining the VOC weight percent concentrations, the Agency has
decided that calculations showing the VOC concentrations can be an
acceptable alternative to testing, and at greatly reduced costs.
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7.0 TEST METHODS AND PROCEDURES
7.1 GENERAL
Comment:
One commenter (IV-D-50) referred to the proposed standard of "98
weight percent, or a concentration of 20 ppmv expressed as the sum of
the actual compounds, not carbon equivalents, corrected to 3 percent
oxYqen, whichever is less stringent" and stated that the correction for
oxygen content may be appropriate for concentrated hydrocarbon streams,
but is inappropriate for dilute hydrocarbon streams. According to the
commenter, this type of correction is normally used to keep a source
from compliance by means of excess air to dilute the emissions. The
commenter then stated that when the hydrocarbon is already in an air
stream, no additional combustion air is needed or used.
To illustrate the problems created by using the oxygen correction
factor, the commenter gave the following example: assume that a vent
stream, diluted with ambient air to 1000 ppmv, is sent to an
incinerator. No combustion air is required as this stream is 20 percent
oxygen. The vent from the incinerator will be 19.9 percent oxygen;
therefore, the hydrocarbon content must be 20 ppm x (3/19.9%) or 3 ppm.
This equates to a required destruction efficiency of (1000-3/1000) x 100
- 99.7 percent. The commenter then recommended that the phrase
"corrected to 3 percent oxygen" be removed from this section for dilute
hydrocarbon streams because it creates a more stringent and less
realistic destruction efficiency than the 98 percent previously
required.
Response:
The Agency agrees with the commenter that correction to 3 percent
oxygen is unnecessary for emission streams that already contain
sufficient air so that additional combustion air is not needed or used,
and could be a potential problem for those seeking to comply with the 20
ppmv limit. Therefore, the Agency has revised the rule so that
correction to 3 percent oxygen is required only when supplemental
combustion air is used.
[The Agency points out that the correction to 3 percent oxygen
does not affect those individuals seeking to comply with the 98 weight
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percent destruction standard because the percent destruction is on a
weight basis ("Ibs in and Ibs out). If the percent destruction was
calculated on a volume basis, as used in the example by the commenter,
then the correction to 3 percent oxygen would be a problem. However,
this is not the case.]
7.2 FLARES
Comment;
One commenter (IV-D-8) suggested that the maximum permitted
velocity equation for nonassisted flares with pilots be revised based on
the test performed by EER at Irvine, CA. The commenter proposed that
Section 60.564(c)(5) of the proposed standards be rewritten as follows:
The maximum permitted velocity, V|nax, for flares complying with
Section 60.562-l(a)(ii )(E)(3) shall be determined using the
following equation for steam-assisted flares:
(v«) ' (Ht + 28.8)/31.7
and the following equation for nonassisted flares
where: HT = net heating value of the sample
Response;
The maximum permitted velocity equation suggested in this comment
describes a line that starts at the point 60 ft/sec, 150 Btu/scf. This
point is below the 60 ft/sec, 180 Btu/scf required to assure 98 percent
combustion efficiency, as demonstrated in the EER studies referred to in
Docket Items IV-A-1 through IV-A-3. The maximum permitted velocity,
VIMX' ^or nonassisted flares shall continue to be determined using the
maximum velocity equation as proposed (i.e., Log10 (VMX) = (HT + 28.8J/31.7)
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7.3 BOILERS
Comment:
One commenter (IV-D-12) suggested that alternative methods of
compliance for boilers or process heaters with a heat input of less than
150 million Btu's be provided rather than requiring just compliance
testing as implied in Section 60.564(a). The commenter indicated that
complete combustion for a boiler of less than 150 million Btu's can be
determined if one knows the boiler temperature, the organics in the gas
stream, and their combustion temperature.
Response:
The Agency has determined that boilers and process heaters with a
heat input capacity of 150 million Btu's or greater have sufficient
combustion temperatures, residence time, and mixing characteristics that
98 percent reduction is achieved without the need for conducting a
compliance test. However, for boilers and process heaters with a heat
input capacity of less than 150 million Btu's, the Agency has determined
that sufficient uncertainty exists that compliance tests for such
boilers and process heaters are necessary to show 98 percent
destruction. The commenter recommended that boiler temperature, gas
stream organics, and their combustion temperature be used to calculate
destruction efficiency for purposes of determining compliance. The
Agency does not believe that such data by themselves are sufficient as
residence time and mixing (both of which were not mentioned by the
commenter) are important contributors to destruction efficiency. If an
owner or operator wished to try to use a method other than testing to
show compliance, the owner or operator may seek to do so under the
General Provisions. However, for purposes of this rule, compliance
testing is being retained for boilers and process heaters with heat
input capacities of less than 150 million Btu's.
7.4 CONDENSERS
Comment:
One commenter (IV-D-12) pointed out that where a condenser is the
final unit in a system, a temperature recording device or an organic
monitoring device is required to indicate the level of organic
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compounds, yet the test methods for determining compliance (Section
60.564(d) of the September 30, 1987, Federal Register notice) only
addresses the use of a temperature recording device. The commenter
recommended that a test method for determining compliance where an
organic monitoring device is selected under Section 60.563(e)(2) of the
September 30, 1987, Federal Register notice should be included in
Section 60.564(d).
Response:
A test method for determining compliance where an organic
monitoring device is selected under proposed Section 60.563(e)(2)
(Section 60.563(b)(5) of the final rule) is not necessary because the
organic monitoring device is for purposes of monitoring the performance
of the condenser and not for determining compliance. The standards for
polystyrene are either: (1) meeting an emission limit in terms of kg
TOC/Mg product; (2) maintaining a maximum outlet gas stream temperature;
or (3) controlling emissions by 98 percent or to 20 ppmv. If an owner
or operator elects to comply with one of the emission limits (i.e., the
TOC/Mg product, 98 percent reduction, or 20 ppmv}, then a compliance
test is required to show that the emission limits are being met by using
the procedures specified in Section 60.564, and the monitoring equipment
once compliance is demonstrated is either a temperature recording device
or an organic monitoring device. Since these two devices are for
monitoring purposes only, test methods need not be developed for them.
If, on the other hand, an owner or operator elects to comply with the
temperature requirement, then the compliance test consists of showing
that the temperature is at or below the required temperature on a
continuous basis. In this instance, a test method using a temperature-
monitoring device is required.
Comment:
One commenter (IV-D-12) stated that the test method in Section
60.564(d) of the September 30, 1987, Federal Register notice should be
modified to include other methods of showing compliance such as material
balances or emission calculation based on exhaust rate and saturation
levels of organic compounds.
Response:
An owner or operator electing to comply with the emission limit
requirement for condensers may seek to use any alternative method to
7.0.
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demonstrate compli.ance as provided under the General Provisions. For
the purposes of this rule, the Agency has retained the use of a
compliance test (see Section 60.564(i) of the final rule).
Comment:
One commenter (IV-D-6) stated that compliance with the 0.0036 kg
TOC/Mg standard for the material recovery section at polystyrene plants
(Section 60.562-l(b)(l)(1) of the September 30, 1987, Federal Register
notice) may in some cases be impossible to measure and certify. The
commenter pointed out that the volume of vent stream from the condensers
in the material recovery section can be very small (near zero in some
cases), making proper sampling very difficult if not impossible. The
commenter stated that they have had encountered difficulty in getting
monitoring contractors who can accurately measure flow and VOC
concentration both of which are necessary to determine mass quantity of
emissions) at the current emission standard level of 0.12 kg TOC/Mg
product. The commenter concluded that it should not be the intent of
the standard to impose emission levels so small that the mass emissions
can not be directly measured and quantified.
Response:
The Agency disagrees with the commenter's contention that emission
streams in compliance with the emission limit for condensers is so small
that it is impossible to measure and certify. Method 2C is suitable for
measuring such low flows.
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8.0 ECONOMIC IMPACTS, COSTS, AND COST
EFFECTIVENESS CALCULATIONS
8.1 ECONOMIC IMPACTS
Comment:
One commenter (IV-D-8) stated that "pass through of costs for add-
on control technology, though estimated by the Agency to range from 0.13
percent to 0.44 percent overall, can be devastating to commodity product
groups with profitability that is already extremely small due to
increased market competition." This commenter offered that the "polymer
and plastics industry is highly competitive and profit margins are
generally minimal for commodity type plastics." Later, the commenter
said that the commodity markets of most concern are bottling and
insulating, and that the polymers of most concern are polystyrene and
PET (see Docket Item IV-E-14). The commenter also noted that foreign
competition and the potential new (but unspecified) health-related
Federal regulations will contribute to problems in these commodity
markets. Of the two polymers, polystyrene is of most concern to the
commenter because, it is claimed, EPA has significantly underestimated
the costs for refrigerated condensers, and because the polystyrene
industry in particular, will soon.be facing several new health and
environmental regulations (still unspecified) that could have a
cumulative significant adverse effect on competitiveness.
Response:
As a result of this comment, EPA performed an extensive analysis
of the economic impacts of the new standards on the polystyrene and PET
industries (see Docket Item IV-B-19). New control costs were estimated
in response to other comments, and condenser system costs were increased
to reflect the above comment that EPA had originally underestimated the
costs for refrigerated condensers.
With the new control costs, the maximum price impacts range from 0
to 0.09 percent. With price impacts of this magnitude, the EPA believes
that the NSPS will not adversely affect profit margins or delay
capacity expansions, especially considering the growing demand faced by
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polystyrene and PET producers. PET bottling sales have been strong,
increasing by 16 percent from 290 gigagrams (Gg) in 1986 to 336 Gg in
1987. The range of maximum price increases for PET is 0 to 0.06
percent, which should not have a significant impact on the PET market.
Sales of polystyrene insulating materials are not known. However, the
range of maximum price impacts -- 0 to 0.09 percent -- suggests that
control costs can easily be recovered through price increases.
Moreover, imports of both polystyrene and PET resins are negligible. In
1987, for example, imports of polystyrene accounted for only 1.2 percent
of domestic consumption.
Foreign competition is a factor in the PET-polyester fiber market.
In addition, this market has had declining sales since 1981, and, as a
result, has had to reduce capacity. However, as mentioned, the maximum
PET price impact is only 0.06 percent, which is not significant. A
price increase of this magnitude should not be hindered by foreign
competition or declining demand. Furthermore, it is unlikely that
capacity expansion is on the drawing board anyway because of the recent
restructuring of the textile industry, which is the primary consumer of
polyester fibers.
The EPA agrees that other regulations may have adverse impacts on
profitability in the regulated industries. For example, regulation of
chlorofluorocarbons would negatively impact the polystyrene insulation
industry. However, other regulations will have to be evaluated
individually for their costs and benefits. This applies to the current
NSPS as well. The individual impact of this NSPS, as represented by a
maximum price impact of only 0.09 percent, is minimal.
Comment;
One commenter (IV-D-8) stated that the imposition of the standard
in its present form on existing sources (modification and
reconstruction) is an unreasonable economic burden. The commenter
clarified "unreasonable economic burden" to mean that the imposition of
the standard on modified and reconstructed sources; would result in
control costs above $l,000/Mg (see Docket Item IV-D-35). The commenter
pointed out that regulatory alternatives with costs below $l,000/Mg were
selected by the Agency, while those with costs above $l,000/Mg were
rejected.
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Commenter IV-D-10 also stated that the economic impact of
individual modifications requiring retrofit should be evaluated against
the Agency's accepted guideline of $l,000/Mg of TOC controlled.
Response:
The Agency disagrees with the commenters that these standards
impose unreasonable costs. In developing an NSPS, the Agency considers
a number of factors including but not limited to the cost effectiveness
of a standard. In the past, regulatory alternatives have been selected
that encompass a range of cost effectiveness values. Typically, these
values fall between $1,000 and $2,000/Mg. The Agency has considered the
types of controls (e.g., flares, incinerators, condensers, distillation
columns) that are likely to be used in the polymer manufacturing
industry. For most of these control techniques, the Agency has
concluded that there will be little to no increase in costs due to a
retrofit in comparison to a new installation.
8.2 COST IMPACTS
Comment:
One commenter (IV-0-39) stated that the figures given for
annualized cost benefits of the "new approach" versus the model plant
approach do not include the engineering and technical costs incurred for
calculating, estimating, and verifying on a periodic basis the actual
emissions, and the figures may therefore be faulty in stating that costs
will decrease with the "new approach."
Response:
The comparison of cost impacts in Docket Item IV-B-13 involve only
expected costs for the control devices required to meet the standards.
These are the costs that are used to determine which alternative is
selected as the basis of a standard and in such calculations as cost
effectiveness. Thus, on this basis, the costs associated with the new
approach were estimated to decrease.
Costs associated with monitoring, reporting, and recordkeeping are
estimated in the Supporting Statement to SF-83. The Agency agrees that
the new approach's monitoring requirements impose greater costs on
affected owners and operators than those associated with the model plant
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approach. The Agency has determined that the increased costs are
reasonable and are, in a sense, the cost of providing industry with a
standard that avoids very expensive control of not cost effective
streams that could have occurred under the model plant analysis due to
the changes in the industry, as pointed out by the industry.
Comment;
One commenter (IV-D-43) referred to EPA's statement "Some process
sections were assumed to have their own control device..." (54 FR 893),
and stated that each process section does not necessarily have its own
control device and sometimes, several process trains share a common
control device. The commenter then stated that as a result the economic
and emissions impacts, as presented in the Federal Register, do not take
into account real-life situations. The commenter recommended that EPA
re-evaluate the application of this faulty assumption and alter
appropriately the language of the final rule.
Response:
The statement referred to by the commenter refers to the
regulatory analysis procedure used in the model plant approach for
determining which process emission streams would be controlled. At that
time, the Agency recognized that each process section does not
necessarily have its own control device and that several process
sections and lines may share a common control device. The assumption
that each process section would have its own control device was used as
an initial conservative approach for identifying the various cost
impacts. The model plant approach did examine potential sharing of
control devices as a secondary analysis for determining which process
emissions should be controlled. Under the new approach, the Agency
recognized the sharing of control devices in a much more direct manner
that is a more accurate representation of the manner in which industry
is actually likely to install control equipment.
The purpose of the discussion of the emission impacts and cost
impacts sections "Impacts of New Approach" (54 FR 904) was to compare
how the emission reduction costs incurred would differ if the new
approach was used, rather than the model plant approach, to determine
which process emissions would be controlled. These comparisons were
made by considering which emission streams would be or would not be
8-4
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controlled by the new approach vs. the model plant approach. The
changes in emission reduction represent those that are estimated to
incur as a result of assuming a more realistic application of control
equipment. The cost impacts presented refer to the costs associated
with controlling the additional emissions on an incremental cost basis
that reflected whether the emissions were going to a common control
device or a separate control device. Therefore, the emission and
economic impacts presented in the January 10, 1989, Federal Register do
reflect real-life situations and no reanalysis is necessary.
Comment:
One commenter (IV-D-47) stated that EPA proposed to control in the
January 10, 1989, Federal Register notice some emissions which in the
September 30, 1987, Federal Register notice it did not consider cost
effective to control using the same 1980-based economics. The commenter
questioned how the same 1980 economics can be used to support these
widely divergent positions.
In a similar comment, Commenter IV-D-50 stated that if controls
for the product finishing and product storage sections at new LDPE, high
pressure process plants were not cost effective to control under the
model plant approach, they are still not cost effective. This commenter
recommended that EPA rescind all control requirements for process sec-
tions determined not cost effective to control under the September 30,
1987, proposal, until cost estimates and economic justifications are
redone.
Response:
A number of emission streams and process sections were identified
as potentially being controlled when the "new" approach, which forms the
basis of the January 10, 1989, Federal Register notice, is used to
determine which process emissions are to be controlled, but would be
uncontrolled under the original approach based on a model plant
analysis, which was the basis of the September 30, 1987, Federal
Register. These emission streams and process sections were considered
"not cost effective" to control under the model plant approach. These
results were presented in Docket Item IV-B-13. The commenter questions
how these emission streams and process sections can now be cost
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effective to control when the same set of costs in 1980$ is used in the
new approach.
The basic answer to the commenter's concern lies in the
assumptions and procedures made in the model plant analysis and the need
to base control/no control decision for all affected facilities on the
basis of a model plant's emission characteristics. Three types of
"conflicting" situations arose under the approach presented in the
January 10, 1989, Federal Register notice.
First, control of low flow streams. The model plant analysis did
not consider control of individual streams within a process section.
Rather, all continuous streams were grouped together and a separate
control device was assumed to control the emissions. If control of the
entire process section was determined not to be cost effective, then no
control of any stream was considered. Under the new approach,
individual streams with flows equal to or less than 8 scfm and emissions
greater than or equal to 1.6 Mg/yr are required to be controlled. These
streams are cost effective to control, but the model plant analysis did
not consider such streams on an individual basis.
Second, low VOC concentration streams. The new approach requires
control of low VOC concentration streams if emissions are greater than
specified levels, which vary according to the VOC concentration. This
leads to control of certain product finishing and product storage
process sections under the new approach. The particular combination
(i.e., process line only) considered under the model plant analysis,
however, led to a rule that control would not be required. This
assumption of the model plant analysis was overly conservative in that
it did not reflect using a single control device for multiple process
sections at a new plant or the modification or reconstruction of
multiple process sections. In these instances, control is cost
effective if sufficient emissions are present. The new approach is
simply more flexible in identifying such situations than was the model
plant approach.
Third, intermittent emissions. Two instances were projected
whereby intermittent emissions were projected to be controlled under the
new approach but not under the model plant approach. In both instances,
these emissions were considered part of baseline control and, as such,
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would be controlled in the absence of these standards. Thus, these
emissions and their process sections were identified as affected
facilities under the model plant approach. An uncontrolled threshold
emission rate was calculated for each affected facility. The procedure
used for calculating that rate was based on a projection of future
growth -- process section, process line, and new plant. It turns out
that the procedure resulted in an uncontrolled threshold emission rate
greater than the model plant's emission rate for those emissions. Thus,
for purposes of impact analysis only, those emissions were shown as not
being controlled under the model plant analysis in Docket Item IV-B-13.
The model plant analysis, in fact, showed a similar range of cost-
effectiveness values as did the new approach. The new approach,
however, does not have a threshold level for these emissions, because
(as explained in more detail elsewhere) of the difficulty and expense of
identifying actual emission levels from intermittent emissions.
For these intermittent emissions, the Agency recognizes that there
is a trade-off between the two approaches. Under the model plant
approach, some cost effective intermittent emissions are not controlled,
because of the analytical procedure used. Under the generic approach,
some small intermittent streams may be controlled that are truly not
cost effective to control, because of the inability to accurately
measure intermittent emissions. Under either approach, individual
facilities may spend more or less money or control than at another
facility. The Agency has selected the new approach as the overall
better way to determine which emissions to control from polypropylene
and polyethylene plants.
Comment:
One commenter (IV-D-43/IV-D-50) pointed out that the EPA has not
updated control costs from the September 30, 1987, proposal (52 FR
36678) and that the only economic factor that was updated was the price
of fuel gas (that decreased), while other costs (not updated) rose. The
commenter then stated that EPA should reevaluate its projected economic
impacts.
Another commenter (IV-D-47) pointed out that the information used
by the Agency to provide the basis for the current proposals dates back
to the early 1980's and that the Agency continues to use 1980-based
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economics while abandoning the model plant approach and retaining
process section rationale.
Response:
The Agency reviewed the costs and costing procedure used in BID
Vol. I for flares, thermal incinerators, and catalytic incinerators.
The review indicated that the values were generally accurate and
consistent with other EPA projects, and the procedures for sizing and
costing control equipment were reasonable and consistent with EPA
procedures. The Agency decided to retain costs in terms of June 1980S,
While the Agency found the costs and costing procedures to be, in
general, accurate, reasonable, and consistent with other EPA projects,
there were a few exceptions. As noted in Docket Item IV-B-10, BID Vol.
I procedures and costs for incinerators have been modified somewhat to
be consistent to those found in EPA's EAB Control Cost Manual. February
1987. This manual was released after the initial cost work was
completed. Items affected were natural gas requirements calculations
and costs; heat recovery efficiency; incinerator costs, including the
use of pretreatment air filters for particulate removal; piping lengths;
and installation factors. Additional review discovered that the
electricity price of $0.049 per kilowatt hour (kWh) in 1980 dollars was
too high for estimating the cost of electricity to the polymer industry.
The 1980 industrial sector price, in 1980 dollars, for electricity was
$0.0369 per kWh, with an average industrial sector price for 1984
through 1988 of $0.0373 per kWh (adjusted to 1980 dollars using the
gross national product implicit price deflators). Thus, the cost
analysis was also revised using an electricity price of $0.037 per kWh
(see Docket Items IV-B-14 and IV-B-15). For flares, the only
modifications deemed necessary were to the calculations for estimating
natural gas requirements, the cost of natural gas, and flare piping
length.
The effect of these changes in terms of estimating costs varied
from one cost item to another and from one control devTce to another.
The overall effect generally was to decrease marginally the estimated
annualized cost of a flare for a given emission stream and to increase
the estimated annualized cost of a catalytic incinerator for a given
emission stream.
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Comment:
One commenter (IV-D-43/IV-D-50) stated that the economic analyses
in the revision to the proposal (54 FR 890) are marred by the fact that
EPA did not update emissions data. The commenter noted that since the
time of the September 30, 1987, proposal (52 FR 36678), the concept of
zero emissions from product storage sections has changed. For reasons
described by the commenter, the commenter indicated that when EPA
collected its initial data, the polymer industry reported no emissions
from storage silos in catalytic processes (any low pressure process),
but recent investigations showed that storage silo emissions were not
completely eliminated, but rather were at levels approaching the 0.1
weight percent level that EPA is now considering for exemption from
control. According to the commenter, the cost of controlling these
dilute streams far outweighs any benefits and should be reconsidered.
The commenter did note that it appears that the proposed 1.6 Mg/yr
exemption (in the January 10, 1989, Federal Register notice) will likely
exempt most of the vent streams from storage silos currently operating,
although the emission rate from storage silos is largely dependent on
the design capacity of the production facility and the product turnover
rate in the silos. According to the commenter, the trend in the
industry is to build larger process units and the exemption of 1.6 Mg/yr
may soon become inadequate. The commenter then stated that this concern
will be eliminated if new sources were able to use the calculated
threshold emissions (CTE) formulae proposed for modified and
reconstructed facilities. The commenter also recommended that EPA
reconsider emissions from product storage sections to project a more
realistic economic impact than that contained in the reproposal.
Response:
As noted in an earlier response, the Agency has decided to extend
the 0.1 weight percent exemption and the various CTE equations for low
VOC weight percent streams that were proposed for modified and
reconstructed affected facilities to new facilities. As the commenter
did not provide any new emissions data on product storage emissions, the
Agency evaluated the economic impact of the new approach based on model
plant emissions and the extension of the 0.1 weight percent exemption to
new facilities.
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Comment:
One commenter (IV-D-46) stated that Docket Item IV-B-13, titled
"Impact of New Approach Being Considered on Process Sections Subject to
Control" does not include the cost to capture and send emergency
releases to a flare. The commenter noted that, in the proposed model
plant approach (Table 1 of 52 PR 36688), all five polyethylene processes
and the polypropylene gas phase process were exempt from having to send
emergency releases ("emergency vent streams") to a flare, while under
the proposed generic approach, these six processes would now be required
to capture and send emergency releases other than decomposition
emissions to a flare. According to the commenter, this exclusion of the
cost to capture and send emergency emissions to a flare is also
reflected in the written material of Docket Item IV-B-13; for example,
on page 2, it states for low density polyethylene, high pressure, "The
primary difference is the potential control of product finishing and
product storage emissions... ." The commenter stated that the revision
to the proposed regulations (54 FR 905, January 10, 1989) did not take
into consideration the cost to capture on-decomposition emergency
releases to a flare (a minimum of $15,000/Mg) and that the $1200/Mg
abatement cost on page 905 is significantly understated because this is
the cost for abatement of emissions from Product Finishing and Product
Storage process sections only, and does not consider the cost of control
of emergency releases which would be approximately $15,000/Mg according
to Table 2 of Docket Item IV-B-12 in addition to the $1200/Mg.
Response:
The Agency believed that the definition of decomposition and
emergency emissions would cover the same set of emissions. Thus, the
impacts presented in Docket IV-B-13 are correct given that belief.
However, as pointed out elsewhere, the Agency now understands this to be
incorrect. The final rule has been revised to exclude control of such
emissions so that the impacts presented in Docket Item IV-B-13 remain
unchanged.
Comment:
One commenter (IV-D-50) stated that in the cost analyses for the
Federal Register notice reopening the public comment period, EPA only
considered the cost of controls in close proximity to the emissions
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sources. The commenter referred to Docket Item IV-B-4, Table 3, Piping
Cost for Flares, in which 70 feet of piping for a source leg and 20 feet
of piping for the compressor leg are costed. The commenter then stated
that this is an insufficient amount of pipe (90 feet total) if the
emission source and the existing control device are on opposite sides of
a polyethylene or polypropylene plant. According to the commenter 300
to 400 feet of piping is required normally to place the flare a safe
distance from the process. The commenter then concluded that EPA
underestimated the cost of piping requirements, and therefore, the costs
for flares.
Response:
The Agency reexamined Docket IV-B-4, Table 3, discovered that
footnote a was incorrect (in fact 140 feet of piping was costed, but the
wrong costs were used), and reevaluated flare costs based on a total of
400 feet of piping. This length of pipe was selected based on a similar
comment and resulting data collected in connection with the SOCMI-
Distmation project. The net effect was a small increase in the cost
(see Docket Item IV-B-16). The final rule reflects this change in
costs.
Comment:
One commenter (IV-D-50) stated that EPA incorrectly calculated the
cost effectiveness of controlling product finishing sections at new
HOPE, solution process plants and based on the corrected incremental
cost effectiveness, EPA should not control the product finishing section
of a HOPE process line, which was the same conclusion reached by EPA in
the September 30, 1987, Federal Register notice. The commenter stated
that EPA used incorrect emission reductions in Docket Item IV-B-13
("Impact of New Approach Being Considered in Process Sections Subject to
Control"), which addresses the impact of the new approach on various
process sections. The commenter states that the correct incremental
cost effectiveness is $8,850/Mg, not $3,000/Mg.
Response:
In the September 30, 1987, Federal Register notice the cost
effectiveness of control was based on an emission reduction of 44.1
Mg/yr for a single process section. The control device being used was a
catalytic incinerator. In the course of costing catalytic incinerators
8-11
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instance, one company uses a solvent, that has a boiling
point of 99 'C. This reduces the practicality of using a
stripper for this company because the temperature of
atmospheric steam is 100 *C could approach the melting point
of the copolymer charge causing agglomeration.
A company with a higher boiling solvent could go to a vacuum
system. However, for a large scale plant the cost to go to
a vacuum system will be very high due to the added
construction requirements of the stripper vessel. The EPA
has failed to account for the added costs associated with
designing such a large vessel under moderate to low vacuum
conditions.
Response:
The commenter is incorrect in stating that the annual emission
reduction is 44.1 Mg rather than 132.3 Mg. As noted in the above
response, there was an error in the original calculation, which led the
commenter to believe that the annual emission reduction was 44.1 Mg.
With regard to the commenter's statement that "EPA failed to
consider other important factors in its cost analysis by suggesting that
"all" HOPE solution plants should use a stripper", the commenter
Incorrectly suggests that EPA is requiring companies to install
strippers in order to comply with the standards. The model plant
presented in the BID was based on a U.S. HOPE solution plant using a
stripper (see Docket Item II-D-30). The presence of the stripper in the
model plant in no way implies that all companies are expected to use the
same process equipment, but that a typical company would have such a
piece of equipment. To the extent that other companies do not use
strippers, as stated by the commenter, then the model plant is not
representative of those facilities. For the "new1" approach for
determining which process streams to control, this is not a problem.
The applicable standards require 98 percent destruction or 20 ppmv.
They do not require that a company use a stripper as part of the
process. Thus, the commenters suggestions for further cost
considerations are irrelevant to the development of these standards.
8-13
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9.0 REPORTING AND RECORD.KEEPING REQUIREMENTS
9.1 GENERAL
Comment:
One commenter (IV-D-7) stated that the potential amount of record-
keeping required to determine if modifications occur is enormous. The
commenter noted that, while the designation of process section as the
affected facility allows industry to keep the process sections of
process lines separate, a company with an existing polymer plant must
divide the plant into process lines and into process sections, with a
large polymer plant having as many as 10 to 15 affected facilities. The
commenter pointed out that over the course of a year, many small changes
are normally made to polymer plants and stated that in order to evaluate
whether a modification has occurred, a company will have to set up a
completely different accounting system to track the changes to those 10
to 15 facilities. The commenter believes that this will result in an
unreasonable amount of recordkeeping.
Response:
The Polymers NSPS does not require that a separate accounting
system be kept for modifications to each process section. Records do
need to be kept in order to determine whether alterations are classified
as modifications or reconstruction. This requirement is part of the
General Provisions of 40 CFR Part 60. It is at industry's discretion to
keep these records organized as they see fit. For the purposes of
determining reconstruction, the affected facility will continue to be
the process section.
Comment:
One commenter (IV-D-5) believes that Section 60.565(f)(i) of the
September 30, 1987, Federal Register notice, which requires maintaining
records of any process changes, should be deleted because it is directly
redundant with the General Provision requirements. The commenter stated
that the NSPS General Provisions address the topics of modification and
reconstruction and require sources to consider these areas when making
process changes or additions.
9-1
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Response:
The paragraph referred to by the commenter supplements the General
Provisions [Section 60.7(a)(4)] by identifying specific items that are
to be recorded. The paragraph does not replace the General Provisions
requirements. Thus, the final rule retains this paragraph, which has
been redesignated as Section 60.565(g)(l).
9.2 FLOW RATES
Comment:
One commenter (IV-D-8) stated that Section 60.565(j)(2) of the
September 30, 1987, Federal Register notice (which requires recording
periods when the vent stream has been diverted from the control device
or has no flow rate) is ambiguous based on the definition of a vent
stream found in Section 60.561, "Definitions."
Response:
As proposed, the definition of vent stream was "any gas stream
released to the atmosphere from any polymers and resins process line."
The Agency agrees with the commenter that this definition of vent stream
could make interpretation of Section 60.565(j)(2) ambiguous, because it
may Imply that only vent streams emitted directly to the atmosphere are
being defined, and since the stream referred to in Section 60.565(j)(2)
is being sent to a control device (rather than to the atmosphere) it
does not meet the definition of "vent stream." This interpretation,
while not without some logic based on the wording in the proposed rule,
is not correct. The intent of Section 60.565(j)(2), which has been
redesignated as 60.565(k)(2) in the final rule, is simply to record
those periods of time when a gas stream being controlled by a flare or
other air pollution control device is diverted from that control device
or has no flow rate (e.g., during process shut-downs). In order to
remove this ambiguity, the Agency has revised the definition of vent
stream as follows:
"Vent stream" means any gas stream released to the atmosphere
directly from an emission source or indirectly either through
another piece of process equipment or a material recovery device
that constitutes part of the normal material recovery operations
in a polymer process line where potential emissions are recovered
9-2
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for recycle or resale, and any gas stream directed to an air
pollution control device. The emissions released from an air
pollution control device are not considered a vent stream unless,
as noted above, the control device is part of the normal material
recovery operations in a polymer process line where potential
emissions are recovered for recycle or resale.
Comment:
Two commenters (IV-D-5, IV-D-8) recommended that the provisions
requiring recordkeeping of flared vent stream flow rates (Sections
60.565(d)(l) and (2) of the September 30, 1987, Federal Register notice)
be deleted. One commenter stated that as long as the vent streams in
question have no physical possibility of being discharged to the
atmosphere prior to being flared, there is no reason to be concerned
over flow rates or lack of flow for any particular vent stream.
Response:
As noted in a response to an earlier comment, engineering piping
reports are now being required to describe the piping arrangement used
to route vent streams to the flare (or other control devices). If
valves are present in the piping, then those valves that direct the vent
stream to the control device will be required to be kept car-sealed
opened; valves that would allow the vent stream to bypass the control
device and to be emitted to the atmosphere either directly or indirectly
through another piece of equipment are to be car-sealed closed. The
final rule identifies two alternative monitoring methods (see Sections
60.563(d)(l) and (2) of the final rule). One method calls for the
monthly inspection of all car seals. For this method, records are to be
kept of all maintenance performed on car-sealed valves, of all times
when the car seals are broken, and of all times when the valve position
is changed (i.e., from opened to closed for valves in the vent piping to
the control device, and from closed to opened for valves venting
directly to the atmosphere). The other monitoring method calls for the
installation of flow indicators downstream of all valves that are
required to be car-sealed shut. At least hourly recordings of flow are
required to be recorded and reported. The Agency never intended that
flow rates be recorded, only that flow/no flow readings be obtained.
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Comment;
One commenter (IV-D-5) recommended that the reporting of no flow
conditions (Section 60.565(j)(2) of the September 30, 1987, Federal
Register notice) be deleted. This commenter based this recommendation
on their previous comments concerning the lack of a need for vent stream
flow indicators.
Response:
The engineering report now required does not need periods of no
flow to be reported because periods of flows being diverted are being
monitored. Thus, the reporting of no flow conditions has been deleted.
The requirement to record the period when the vent stream has been
diverted from the control device is retained.
9.3 PILOT LIGHT FLAME
Comment:
Two commenters (IV-D-5, IV-D-8) recommended that the requirement
for submitting continuous records of the flare pilot light flame heat-
sensing monitoring (Sections 6C.565(a)(3)(ii) and (a)(4)(ii) of the
September 30, 1987, Federal Register notice) be deleted. Commenter IV-
D-5 believes that this requirement is inefficient and is redundant with
the requirements of proposed Sections 60.565(a)(3)(iii) and (a)(4)(iii),
which require records of'all periods of operations during which the
pilot flame is absent. This commenter noted that a thermocouple, used
in this type of monitoring, senses the presence or lack of a flame and
sounds an alarm if the flame is extinguished, and as such, continuous
records would not typically exist. The commenter pointed out that the
alarms would also be triggered by a thermocouple failure. Commenter IV-
D-5 stated that the periods for which the alarms are on are noted by the
operators. The commenter believes this arrangement satisfies the
objective of determining when the flare pilots are operating without the
paperwork and expense of maintaining a continuous recorder.
Commenter IV-D-8 stated that these sections in the proposed
standards contain ambiguous instructions. The commenter asked "How can
one record the flare pilot light flame heat-sensing monitor?" This
commenter suggested that these sections read that records of checks on
the monitor should be kept.
9-4
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Response:
The EPA considers it very important that records be kept and
reported which identify those periods when the pilot flame is absent
from the flare and unburned emissions are being released to the
environment. The Agency believes that continuous records of pilot flame
heat-sensing monitoring, which can be obtained using a continuous
recorder that tracks the heat level, are necessary for enforcement
purposes. Such records allow enforcement personnel to confirm that
there is a flame present during periods that are not reported as flame
absent periods. The commenter's arrangement would not provide the
"positive" assurance that a flame is present during periods not reported
as flame absent periods. In addition, proposed Sections
60.565(a)(3)(ii) and (a)(4)(ii) require that the pilot flame monitoring
data recorded during the initial and any subsequent performance test be
submitted. These are the only times the standards require these records
to be submitted. Other sections of the standards require these records
to be kept for at least 2 years. For these reasons, the Agency has
retained these requirements (see Sections 60.565(a)(3)and (a)(5) of the
final rule).
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10.0 MISCELLANEOUS
10.1 DEFINITIONS
Comment:
One commenter (IV-D-1) suggested using the phrase "each continuous
vent stream" in lieu of "vent stream that emits continuous emissions" in
Section 60.562-l(a)(l) of the September 30, 1987, Federal Register
notice. The commenter later clarified that this suggestion was made
only to simplify the expression.
Response:
The Agency agrees that the phrase suggested by the commenter is
less cumbersome than the one used in the paragraph referred to by the
commenter, for that single usage. However, phrases used elsewhere in
the rule are better understood if the terms "continuous emissions" or
"emissions" are retained than if the term "vent stream" is used.
Therefore, the Agency prefers to retain the definitions for "vent
stream," "continuous emissions," and "intermittent emissions," and has
retained the original phrasing in Section 60.562-l(a)(l).
Comment:
One commenter (IV-D-2) requested that the term "thermoplastic" be
added to the definition of polypropylene to make all polymer definitions
consistent with one another.
Response:
The Agency has inserted the term "thermoplastic" into- the
definition of polypropylene, because it is the intent of these standards
to cover those production processes that produce thermoplastic
polypropylene and thermoplastic polypropylene copolymers.
Comment:
Several commenters (IV-D-39, IV-D-44, IV-D-50) expressed concern
over the definition of "concurrent" in the January 10, 1989, Federal
Register notice and the concept of concurrently constructed, modified,
and reconstructed affected facilities. Commenter IV-D-39 suggested that
the word "concurrent" be deleted. This commenter stated that its
purpose is unclear and that it appears to require that modifications to
existing facilities occurring within two years of each other would be
10-1
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treated as new facilities with the stricter low VOC concentration
requirements being applied.
Commenter IV-0-44 suggested that the two-year time frame in the
definition of "concurrent" be replaced with a six-month period. This
commenter stated that the definition of concurrent as proposed could
impose retroactive additional control measures and costs to projects
already completed or near completion. Commenter IV-D-44 believes that
no additional requirements should ever be imposed on projects already
completed or which have initiated construction. This commenter
illustrated their concern by stating that major projects could be
vulnerable for additional control requirements and incurred costs up to
five years (three years from commencement to completion plus two-year
concurrent period) from date of commencement. Commenter IV-D-44 stated
that this was "totally unreasonable and not cost effective." The
commenter believes that all control decisions for concurrent projects
should be made during their common planning/design phase and that
projects should not be considered concurrent unless they have a common
planning time frame. According to this commenter, two years is too long
a time frame for the definition of concurrent and is longer than most
planning cycles.
Commenter IV-D-44 also stated that the proposed use of concurrent
does not appear to exempt projects under construction, modification, or
reconstruction prior to January 10, 1989, from additional control
requirements. The commenter recommended that projects started prior to
January 10, 1989, be excluded from being considered concurrent with
other projects begun after January 10, 1989.
Commenter IV-D-50 stated that the wording of the definition of
concurrent is confusing (54 FR 895). According to this commenter, the
definition as stated now would lead to the following scenario: when a
plant commences a project "B" within two years of the commencement of a
previous project "A" at the same plant, and it commences a project "C"
within two years of the commencement of project "B," then "B" can be
concurrent with "A" and "C" can be concurrent with "B" while "C" may not
be concurrent with "A." Commenter IV-D-50 then stated that this
situation could foreseeably go on for years and makes the completion
date of each successive project irrelevant. Commenter IV-D-50
recommended that the EPA eliminate the concept of concurrent
10-2
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control, but that if the EPA feels this definition is absolutely
necessary, suggested as an alternative to the statement in the revised
proposal (54 FR 895) the following language:
"... construction, modification, or reconstruction within
a process unit (replacing, "of affected facilities") which
has commenced in the two year period prior to the commencement
date of the construction, modification, or reconstruction of
an affected facility."
Response:
Under the generic approach for determining which process emission
streams are to be controlled from polypropylene and polyethylene
facilities, the Agency proposed in the January 10, 1989, Federal
Register notice that emissions from all concurrently constructed,
modified, and reconstructed affected facilities be combined (according
to the procedures outlined in that notice) for purposes of determining
which emission streams would be controlled. When a new plant is built,
all of the process sections are (obviously) concurrent, and the generic
approach requires combining emission streams in the same weight percent
range across all process sections. This procedure formed the basis for
the development of the calculated threshold emission levels proposed in
the January 10, 1989, Federal Register notice.
The Agency extended this concept of concurrent construction to
modified and reconstructed affected facilities. If two process sections
are modified at the same time, the Agency knows of no reason not to
combine streams across the two process sections for control
determinations. In fact, the generic approach is specifically designed
to reach more reasonable control/no control determinations when this is
done then when each process section is considered individually.
Further, the Agency believes that reasonable control decisions can be
made even for affected facilities that are not "concurrent," as defined
in the January 10, 1989, Federal Register notice.
The Agency has decided that the term "concurrent" is unnecessary
to implement the generic approach and has eliminated it from the final
rule. However, the Agency has replaced it with a different and more
expansive procedure. This new procedure requires uncontrolled emission
streams from an affected facility to be examined for pollutant control
whenever a process section at the plant site is constructed, modified,
or reconstructed regardless of the time interval between the
-------
commencement or completion dates of the affected facilities. Once an
emission stream is controlled as a result of these standards, it is
never again considered for determining the control of other emission
streams.
In implementing this new procedure, the Agency disagrees with the
commenters that it is unreasonable to require control of emissions from
an affected facility that has begun operation (i.e., after it has been
completed). The generic approach was designed to identify that level of
annual emissions for a given weight percent of VOC in a single or
combined emission stream above which control is deemed to be reasonable,
regardless of the number of emission streams, the period of time when
they became subject to the standards, or the planning phases or periods .
at a plant site. In addition, the Agency disagrees that there is a need
to distinguish between those process sections that became affected
facilities before January 10, 1989, and those that become affected'
facilities after January 10, 1989. Reasonable control determinations
can be made regardless of an affected facility's applicability date.
• To illustrate how this new procedure works, the following example
is provided.
Example: At a polypropylene plant, Process Section A is
reconstructed. There are three continuous emission streams (1,2,
and 3), one in each of the three weight percent ranges. Stream 3,
which is in the 20 to 100 weight percent VOC range, has emissions
greater than the calculated threshold emissions (CTE) and, thus,
control is required. Emissions from Streams 1 and 2 are below
their respective CTEs and, thus, no control is required". Process
Section B is modified, and has two emission streams, 4 and 5.
Emission Stream 4 is in the same weight percent range as Emission
Stream 1, and Emission Stream 5 is in the same weight percent
range as Emission Stream 2. These emission streams would now be
combined (4 with 1 and 5 with 2) to determine whether emissions in
each weight percent range are greater than their respective CTEs.
Suppose the total emissions from Emission Streams 5 and 2 are
greater than the CTE for their weight percent. These two streams
would now be controlled. Suppose the other two streams (4 and 1)
remain uncontrolled (i.e., their total annual emissions are less
than the CTE for their weight percent). Finally, Process Section
10-4
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C is constructed at the plant site. Process Section C has two
emission streams, 6 and 7. Emission Stream 6 is in the same
weight percent range as Emission Streams 4 and 1. Since the
latter two streams are still uncontrolled,, they would be combined
with Emission Stream 6 from Process Section C to determine whether
controlled is required of all three streams. Suppose the total
emissions now exceed the CTE for the combined weight percent, then
all three streams would be controlled. Emission Stream 7, which
is in the 20 to 100 weight percent range, would be evaluated on
its own, since there are no uncontrolled streams from an affected
facility in this weight percent range. If the annual emissions of
Emission Stream 7 are less than the CTE, no control is required.
(Note: In all cases where control is not required, streams with
flow less than 8 scfm are still required to be controlled.)
Comment:
One commenter (IV-D-47) stated that the term "material recovery"
may actually provide a disincentive for good emissions control practice
and that the requirement that emissions control be required at a 98
percent effectiveness level may possibly encourage less waste
minimization to allow the 98 percent control to be achieved at low or no
cost.
In a follow-up conversation with the commenter (Docket Item IV-E-
66), the commenter clarified these comments. According to the
commenter, these comments were meant to convey the idea that an owner or
operator may design a plant upfront in a less-than-ideal manner (e.g.,
practice less material recovery) so that uncontrolled emissions may be
higher than if the plant was designed in a more rigorous manner as the
control requirement of 98 percent reduction in the former situation
would be less costly to achieve than in the latter situation.
Response:
The Agency believes that it is difficult to project the exact
effect these standards will have on the amount of material recovery that
an owner or operator will practice now that certain emission standards
have to be met. If an owner or operator were to reduce material
recovery (that would otherwise occur in the absence of these standards),
the resulting emission stream would be larger, thereby requiring a
larger 'and more costly control device. On the other hand, if the
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material recovery were to reduce only VOC concentrations, the cost of
control could increase if natural gas requirements increased or if a
different and more expensive control device were required. If flow was
also reduced, there may be no cost difference. These possible outcomes
are not unique to this standard. The Agency would encourage an owner or
operator to minimize generation of waste materials (i.e., air
emissions). (As a point of note, the provision of the 0.1 weight
percent VOC exemption would provide an incentive for material recovery
in certain situations.) For purposes of these standards, the Agency has
retained the use of the term "material recovery" and the 98 percent
reduction level.
10.2 OTHER
Comment
One commenter (IV-0-46) stated that the column titled "Model Plant
Based Approach/Intermittent Emissions," in Table 3 of Docket Item IV-B-
13 is Incorrect for the types of processes listed on Table 1 of 52 FR
36688 (September 30, 1987).
Response:
The Agency understands the commenter's confusion. The confusion
arises in part because of the different purposes of the two tables.
Table 1 of the September 30, 1987, Federal Register notice identifies
those process sections for continuous and intermittent emissions that
would be subject to the standards as proposed on September 30, 1987.
Table 3 of Docket Item IV-B-13 identifies those process sections and
emissions that are projected to be controlled using the stream
characteristics found in the model plants and applying the September 30,
1987 proposed standards, including the uncontrolled threshold emission
rates. Some process sections and emissions appear in the "Model Plant" '
column of Table 3 of Docket Item IV-B-13 because emissions occur from
these sections but would not be controlled because they were not
identified as an affected facility in the September 30, 1987, Federal
Recn'ster notice. In these instances, their appearance does not imply
that they were identified as affected facilities in the September 30,
1987, Federal Register notice. They are included in Table 3 of Docket
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Item IV-B-13 because under the new approach all process sections for
both continuous and intermittent emissions are affected facilities.
Some confusion may also occur because "no control" is indicated
for some emissions from certain process sections that were identified as
affected facilities in the September 30, 1987, Federal Register notice.
This occurs because these emissions were included in the baseline (would
be controlled in the absence of the standards), but their emission rates
were less than the uncontrolled emission rate threshold level thereby
potentially excluding them from control.
Comment:
One commenter (IV-D-39) stated that the overall impact of "new
approach" versus the original NSPS proposed rules; is much more effort on
industry to determine what is correct in implementing the "new approach"
rules at their individual facilities. The commenter believes that it
will be very difficult for a proposed new facility in the design phase
to provide the specific unit-by-unit data required and that the data can
only be theoretical at that point or based on pilot plant data, which
have inherent inaccuracies in scaling up.
Response:
The Agency agrees that the new approach requires more effort on
the industry's part to determine which process emissions are to be
controlled versus the approach reported in the September 30, 1987,
Federal Register notice. The Agency also feels that the new approach,
which was developed in response to specific industry comments on the
September 30, 1987, Federal Register notice, is more equitable and
appropriate in the end for controlling process emissions that should be
controlled. Thus, there is a definite trade-off to the two approaches.
Comment:
One commenter (IV-D-8) pointed out a typographical error in
Section 60.564(f)'-- reference should be to Section 60.564 not'Section
60.546.
Response:
This typographical error has been corrected in the final rule.
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APPENDIX A
FLOW DIAGRAMS ILLUSTRATING PROCEDURES
FOR DETERMINING WHICH POLYPROPYLENE
AND POLYETHYLENE EMISSION STREAMS
ARE TO BE CONTROLLED
A-l
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The promulgated standards for polypropylene and polyethylene
contain fairly complex procedures for determining which process
emissions are subject to the standards. This is the result of adopting
a generic approach. Commenters requested that the Agency clarify this
procedure and the standards that are to be met. To meet this request,
the Agency developed a series of five flow diagrams, which are presented
as Figures 1 through 3. The purpose of these figures is to provide only
an overview of the determination procedure for polypropylene and
polyethylene process emissions, and do not contain specific details
found in the final rule. The following paragraphs summarize the purpose
of each figure.
Figure 1 initiates the determination procedure for each process
section. Through this figure, affected facilities are identified and
separated according to their applicability date (between September 30,
1987 and on or before January 10, 1989, and after January 10, 1989).
This figure also includes the exemption step provided to affected
facilities with an applicability date between September 30, 1987, and
January 10, 1989, and identifies how these emissions can become subject
to the rule at a later date (see Block 1.6). For process sections that
are identified affected facilities subject to the standard, Figure 1
directs the user to Figure 2A for continuous emissions and to Figure 3
for intermittent emissions.
Figure 2A is the first of'three flow diagrams applicable to
continuous emissions. The first step in Figure 2A separates those
continuous emissions that are uncontrolled from those that are
controlled in an existing control device. This is necessary as the
determination procedure is different depending on whether the emissions
A-2
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are already being controlled. If they are, the flow diagram directs the
user to Figure 2C. For uncontrolled continuous emissions, Figure 2A
continues by showing the exemptions provided for individual emission
streams (see Block 2A.5). Note that an individual stream that is
exempted based on its annual emissions or weight; percent can become
subject to the standards at a later date if its annual emissions become
1.6 Mg/yr or greater (if exempted based on the annual emissions
exemption) or its VOC concentration becomes 0.1 weight percent or
greater (.if exempted based on the VOC weight percent exemption (see
Block 2A.6). Once qualifying individual emission streams are exempted,
the user is directed to Figure 2B.
Figure 2B outlines the procedures for combining nonexempt
uncontrolled continuous emissions and determining which emissions are to
be controlled. This figure corresponds to the steps detailed in Table 3
1n the final rule. An important feature of the rule is the "loop"
provided between Blocks 2B.12 and 2B.3. In the final rule, uncontrolled
emissions that remain uncontrolled after passing through this determina-
tion procedure are still subject to control in the future as new process
sections become affected facilities.
Figure 2C outlines the procedure for handling emissions that are
already being controlled. Note that for these emissions there are no
individual stream exemptions as fdr uncontrolled emissions. The stream
characteristics of the inlet stream to the control device are used first
to calculate the calculated threshold emission (CTE) level and second to
compare with the CTE level (Block 2C.2). Also note that uncontrolled
emissions are combined with the controlled emissions in one of two ways.
First, if the controlled stream is to meet the standards the next time
A-3
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the control device is modified, reconstructed, or replaced (Block 2C.4),
any uncontrolled emissions in the same weight percent range as the
controlled stream are also to be controlled to meet the standards.
Second, if the controlled stream's emissions are less than the CTE
level, any uncontrolled emissions in the same weight percent range are
combined with the controlled stream (Block 2C.8) if and when the control
device is modified, reconstructed, or replaced (Block 2C.7).
Lastly, Figure 3 outlines the determination procedure for
intermittent emissions. This procedure is much simpler than for
continuous emissions as it is based on stream type rather than stream
characteristics. This figure shows the exemption for emergency vent
streams and the timing for when the standards are to be met, which
depends on whether the intermittent streams are uncontrolled or
controlled in an existing control device.
A-4
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BE6IH HERE EACH TIME A PROCESS
SECTION IS CONSTRUCTED, MODIFIED,
OR RECONSTRUCTED.
WAS PROCESS SECTION CONSTRUCTED
MODIFIED, OR RECONSTRUCTED
AFTER SEPTEMBER 30, 1987?
t.i
NO
YES
PROCESS SECTION
NOT AN AFFECTED
FACILITY
1.2
WAS PROCESS SECTION CONSTRUCTED,
MODIFIED, OR RECONSTRUCTED
AFTER JANUARY 10, 1989?
1.3
NO
1
YES
IS PROCESS SECTION (AND
ITS EMISSIONS) IDENTIFIED
IN TABLE 1 OF THE RULE AS
AN AFFECTED FACILITY?
1.4
YES
YES
ARE UNCONTROLLED EMISSIONS
GREATER THAN THE UNCONTROLLED
THRESHOLD EMISSION RATE
IN TABLE 2 OF THE RULE?
1.5
GO TO FIGURE 2A, BLOCK 2A.I, FOR
CONTINUOUS EMISSIONS AND TO
FIGURE 3, BLOCK 3.1 FOR
INTERMITTENT EMISSIONS
1.7
NO
NO CONTROL IS REQUIRED AT
THIS TIME. IF AT A LATER
DATE, EMISSIONS EXCEED THE
THRESHOLD RATE OR IF MODIFIED
OR RECONSTRUCTED AFTER
JANUARY 10, 1989, THEN PROCEED
TO FIGURE 2A, BLOCK 2A.1.
1.6
Figure 1. Initial Oecisionmaking for Determining Which
Polypropylene and Polyethylene Process Sections Are
Affected Facilities Subject to the Standards
A-5
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FROM FIGURE 1
2A.1
ARE EMISSIONS CONTROLLED
IN AN EXISTING CONTROL
DEVICE?
2A.2
NO
YES
GO TO
FIGURE 2C.
2A.3
MEASURE/CALCULATE WEIGHT
PERCENT AND ANNUAL EMISSIONS
OF EACH STREAM.
2A.4
CONSIDER EACH STREAM:
IS VOC WEIGHT PERCENT
LESS THAN 0.1 OR ARE
ACTUAL EMISSIONS LESS
THAN 1.6 MG/YR?
2A.5
YES
NO
NO CONTROL IS REQUIRED
AT THIS TIME FOR THESE
INDIVIDUAL STREAMS.
IF AT A LATER DATE,
EMISSIONS BECOME OR
EXCEED 1.6 MG/YR OR
CONCENTRATION BECOMES
OR EXCEEDS 0.10 WEIGHT
PERCENT VOC, THEN
PROCEED TO FIGURE 28,
BLOCK 28.1.
2A.6
GO TO FIGURE 2B.
2A.7 .
us Emissions - Separation of Controlled from
Emissions and Individual Stream Exemptions
A-6
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FROM FIGURE 2A,
BLOCK 2A.7
ACCORDING T0
20> 20 T0 100)
.ADD IN ANY UNCONTROLLED EMISSION STREAMS
IN THE SAME WEIGHT PERCENT RANGE
FROM PREVIOUS AFFECTED FACILITIES.
a.3
CALCULATE TOTAL ANNUAL
EMISSIONS FOR EACH
WEIGHT PERCENT RANGE
ACCORDING TO THE
PROCEDURES IN TABLE 3.
a.*
20 TO 100 WEIGHT
PERCENT
CONTROL 98%, TO 20 PPMV, IN A
CONTROL DEVICE THAT MEETS SPECIFIED
OPERATING CONDITIONS, OR IN
AN EXISTING CONTROL DEVICE
28.7
ARE EMISSIONS EQUAL TO OR
GREATER THAN THE CALCULATED
THRESHOLD EMISSIONS?
ZI.S
5.5 TO 20 WEIGHT
PERCENT
0.1 TO 5.5 WEIGHT
PERCENT
YES
ARE EMISSIONS EQUAL TO OR
GREATER THAN THE CALCULATED
THRESHOLD EMISSIONS?
28 .A
SPLIT STREAMS INTO
>8 SCFM AND THOSE
<8 SCFN.
lt.9
CONTROL 98%. TO 20 PPMV, JR
IN A CONTROL DEVICE THAT MEETS
SPECIFIED OPERATING CONDITIONS
za. a
CONTROL AT THIS TIME. RETURN TO DECISIONMAKING
PROCESS NEXT TIME A PROCESS SECTION BECOMES AN
AFFECTED FACILITY OR A CONTROL DEVICE IS MODIFIED,
RECONSTRUCTED, OR REPLACED (SEE FIGURE 2C, BLOCK 2C.8).
23.12
Figure 2B. Decisionmaking Process for Uncontrolled Continuous
Emissions from Polypropylene and Polyethylene Affected Facilities
A-7
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FROM FIGURE 2A,
BLOCK 2A.3
2C.1
ARE EMISSIONS EQUAL TO OR
GREATER THAN THE
CALCULATED THRESHOLD EMISSIONS?
STANDARD DOES
NOT NEED TO BE
MET AT THIS TIME.
ZC.4
NO
" YES
CONTROL DEVICE IS MODIFIED
RECONSTRUCTED, OR REPLACED.
2C.7
DOES EXISTING CONTROL
DEVICE REDUCE EMISSIONS
BY 98 PERCENT OR TO
20 PPMV OR MEET NECESSARY
OPERATING REQUIREMENTS?
•2C.3
ADO IN UNCONTROLLED STREAMS
IN SAME WEIGHT PERCENT
RANGE FROM PREVIOUS
AFFECTED FACILITIES.
. 2C.«
ARE EMISSIONS NOW
EQUAL TO OR GREATER THAN
THE CALCUALTED THRESHOLD
EMISSIONS?
NO
YES
NO
\
YES
STANDARD IS TO BE MET NEXT
TIME THE CONTROL DEVICE IS
MODIFIED, RECONSTRUCTED, OR
REPLACED. ADO IN ANY UNCON-
TROLLED EMISSIONS IN SAME
WEIGHT PERCENT RANGE FROM
ANY AFFECTED FACILITY.
NO FURTHER
CONTROL IS
REQUIRED.
2C.S
CONTROL BY 98 PERCENT, TO 20 PPMV,
OR IN A CONTROL DEVICE THAT MEETS
SPECIFIED OPERATING CONDITIONS.
2C.10
NOTE:
SSES"FOR EMISSIONS AUEADY
Figure 2C Decisionmaking Process for Continuous Emissions Already
Controlled at Polypropylene and Polyethylene Affected Facilities
A-8
-------
FROM FIGURE 1
3.1
EXEMPT ANY EMERGENCY STREAMS
3.2
ARE EMISSIONS CONTROLLED IN
AN EXISTING CONTROL DEVICE?
3.3
NO
STANDARDS ARE
TO BE MET.
3.4
YES
DOES CONTROL DEVICE
MEET STANDARDS?
3.3
YES
NO FURTHER
CONTROL IS
REQUIRED.
3.6
NO
STANDARDS TO BE MET NEXT
TIME THE CONTROL DEVICE IS
MODIFIED, RECONSTRUCTED,
OR REPLACED.
3.7
Figure 3. Decisionmaking Process for Intermittent Emissions from
Polypropylene and Polyethylene Affected Facilities
A-9
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TECHNICAL REPORT DATA
(flense read instructions on the reverse before completing
EPA-45Q/3-83-mQh
3. RECIPIENT'S ACCESSION
IOSU8T1TU5
Polymer Manufacturing Industry - Background
Information for Promulgated Standards"
5. REPORT DATE
October 1990
i. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT N.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT
Office of Air Quality Planning and Standards
Environmental Protection Agency
Research Triangle Park, NC 27711
11 CONTRACT/GRANT NO
iGENCY NAME AND ADDRESS
DAA for Air Quality Planning and Standards
Office of Air and Radiation
U. S. Environmental Protection Agency
Research Triangle Park. NC 27711
15. SUPPLEM6NTARY NOTES
13. TYPE OF REPORT AND PERIOD COVEREC
Final
14. SPONSORING AGENCY CODE
EPA/200/04
ttalvr f
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