August 5, 2014

Certified Mail 7013 3020 0001 6360 6130

Ms. Brenda Shine Sector Policies and Programs Division (E143

- 01) Office of Air Quality Planning and Standards United States Environmental Protection Agency Research Triangle Park, North Carolina 27711

Approval Request for the Operation of the Pressure

- Assisted Multi Point Ground Flare Technology for a Prop ane Dehydrogenation Plant and a Light Hydrocarbons Plant The Dow Chemical Company, Texas Operations

– Freeport, TX

Dear M s

. Shine :

The purpose of this letter is to further formalize our request to obtain an Alternative Means of

Emission Limitation in o rder to operate two different pressure

- assisted multi point ground flares at our Texas Operations site located in Freeport, Texas. An original request was filed with Mr. Steve Thompson at EPA Region 6 on August 20, 2013, and is included as an

attachment t o this letter.

As communicated in the August 20, 2013 request, The Dow Chemical Company (Dow) has plans to construct and operate a pressure

- assisted multi point ground flare for use with our planned pro pane dehydrogenation (PDH) plant . Dow also plans to install a second pressure

assisted multi point ground flare for use with our planned Light Hydrocarbons Plant (LHC

9) . Both plants and flare systems will be constructed and operated at our Freeport , Texas

location.

Based on our review of this flare technology, we believe that th ese flare system s will operate
with a VOC destruction and combustion efficiency greater than or equal to a flare that meets all of the requirements in 40 CFR 60.18 and 40 CFR 63.11 for traditional steam or air

assisted flares. Dow believes that this technology is the best option for controlling VOC

emissions for th ese plants.

This flare technology operates by using the pressure upstream of each individual flare tip burner to enhance mixing with air due to high exit veloc ity , which in turn ensures a high

VOC destruction and combustion efficiency. Due to the design of the flare tips, t he flare s will meet or exceed the requirements in 40 CFR 60.18 and 40 CFR 63.11 with the exception of the exit velocity restrictions contain ed in 40 CFR 60.18 (c)(3 )

– (c)( 5) and 40 CFR

63.11 (b)(6 )

– (b)( 8) . The waste gas will exit the flare tip near or at sonic velocity, which can be in excess of 1,000 feet per second.Ms. Brenda Shine, USEPA August 5, 2014 Page 2

The PDH and LHC

- 9 processes will be subject to a number of TCEQ air pollution regulations that reference the flare requirements in 40 CFR 60.18 and 63.11. In order to address the exit velocity requirements , Dow has requested approval of the technology by submitting an Alternate Means of Control (AMOC) request to the TCEQ on August 20,

2013.

In addition to TCEQ rules, t he PDH and LHC

- 9 processes will also be subject to a number of EPA air pollution control regulations under various subparts of 40 CFR 60, 61, and 63 that

also reference the flare regulatory requirements in 40 CFR 60.18 and 63.11. T he

a ttachment s provide information on the specific regulations that apply

. In order to address the exit velocity requirements, Dow is proposing the following p rovisions and is requesting approval from EPA under the Alternative Means of Emission Limitation provisions :

1. The maximum exit velocity requirements contained in 40 CFR 60.18(c)( 3 ) ,(c)(4) and (c) (5); should not be applied to these flares. Also, the max imum exit velocity requirements contained in 40 CFR 63.11(b)(6),(b)(7) and (b)(8) should not be applied to

these flares.

2. In order to ensure flame stability and a high destruction and combustion efficiency, the waste gas flowing to the flare tips should be maintained with a net heating value that is equal to or greater than values th at were determined during a detailed flare emission testing program in November, 2013. The attachments provide details on the proposed operating limits for these flares.

Therefore, for any applicable New Source Performance Standard (NSPS) in 40 CFR 60

, we respectfully request that EPA approve our request for an Alternative Means of Emission Limitation under Section 111(h)(3) of the Clean Air Act. For any applicable National Emission Standard for Hazardous Air Pollutant Standard (NESHAP) in 40 CFR 61, and a ny applicable 40 CFR 63 MACT Standards, we respectfully request that EPA approve our

request for an Alternative Means of Emission Limitation under EP A’s provisions in those respective rules and the “Use of an alternative nonopacity emission standard ” in 40 CFR 63.6(g).

If you have questions or concerns regarding this request or the attachments, please contact me at ( 361 ) 553

- 2920.

Sincerely,

Russell A. Wozniak

Russell A. Wozniak

EH&S Operations Regulatory Service

The Dow Chemical Companycc:

Andrew Bouchard, Sector Policies and Programs Division, OAQPS, USEPA, Raleigh, North

Carolina 27711

Penny Lassiter, Group Leader, Sector Policies and Programs Division, OAQPS, USEPA, Raleigh, North Carolina 27711

Attachments :1



## Table of Contents

Item Page Demonstration of Equivalency

– General Information on Rule 2

Regulatory Requirements for Propane Dehydrogenation Plant

Flare 4

Regulatory Requirements for Light Hydrocarbons Plant Flare 7

Demonstration of Equivalency

– Pressure

- Assisted Flares 11

Alternative Means of Emission Limitation Operating Conditions 1 4

August 20, 2 013

– Original Request 1 72

D emonstration of Equivalency

– General Information

The two flare systems included in this request will receive different vent gas streams that are regulated by different subparts of the Part 60, 61, and 63 air pollution regulations. In all cases, these rules reference the flare requirements located in 40 CFR 60.18 and 40 CFR 63.11. All three regulatory programs contain provisions in the rules and/or the Clean Air Act that allow EPA to approve an alternative means of emission limitation if the alternative will achieve a reduction in emissions at least equi valent to the reduction in emissions achieved under the existing regulations. The provisions for Part 60 NSPS, Part 61 NESHAP, and Part 63 MACT rules are provided below:

40 CFR 60

- NSPS Rules and Section 111(h)(3) of the Clean Air Act

If after no tice and opportunity for public hearing, any person establishes to the satisfaction of the

Administrator that an alternative means of emission limitation will achieve a reduction in emissions of any air pollutant at least equivalent to the reduction in emi ssions of such air pollutant achieved under the requirements of paragraph (1), the Administrator shall permit the use of such alternative by the source for purposes of compliance with this section with respect to such pollutant.

40 CFR 61 Subpart FF

– N ESHAP Rules, Section 61 .35 3

(a) If, in the Administrator's judgment, an alternative means of emission limitation will achieve a

reduction in benzene emissions at least equivalent to the reduction in benzene emissions from the source achieved by the applic able design, equipment, work practice, or operational requirements in §§61.342 through 61.349, the Administrator will publish in the F EDERAL
R EGISTER a notice permitting the use of the alternative means for purposes of compliance with that requirement. The notice may condition the permission on requirements related to the operation and maintenance of the alternative means.

(b) Any notice under paragraph (a) of this section shall be published only after public notice and an opportunity for a hearing.

(c) Any person seeking permission under this section shall collect, verify, and submit to the Administrator information showing that the alternative means achieves equivalent emission

reductions.

40 CFR 63.6(g)

– MACT Rules

(g) Use of an alternative nono pacity emission standard. (1) If, in the Administrator's judgment, an owner or operator of an affected source has established that an alternative means of emission limitation will achieve a reduction in emissions of a hazardous air pollutant from an

affect ed source at least equivalent to the reduction in emissions of that pollutant from that source achieved under any design, equipment, work practice, or operational emission standard, or combination thereof, established under this part pursuant to section 11 2(h) of the Act, the3

Administrator will publish in the F EDERAL R EGISTER a notice permitting the use of the alternative emission standard for purposes of compliance with the promulgated standard. Any

F EDERAL R EGISTER notice under this paragraph shall be pub lished only after the public is notified and given the opportunity to comment. Such notice will restrict the permission to the stationary source(s) or category(ies) of sources from which the alternative emission standard will achieve equivalent emission re ductions. The Administrator will condition permission in such notice on requirements to assure the proper operation and maintenance of equipment and practices required for compliance with the alternative emission standard and other requirements, including appropriate quality assurance and quality control requirements that are deemed

necessary.

The following pages contain additional details on the specific portions of the subparts that apply to these two flare system and show how these rules contain provisi ons for an Alternative Means

of Emissions Limitation.4

Regulatory Requirements for Propane Dehydrogenation Plant Flare System

T he following EPA air regulations will apply to various streams that are collected and routed to

this flare and this section discuss es how each rule allows for an Alternative Means of Emission

Limitation.

Regulation

40 CFR Subpart 6 0 Subpart VVa

Please note that this rule applies, but the plant is opting to comply with 40 CFR 63 Subpart H, as referenced by the MO N Rule 40 CFR 63 Subpart FFFF, so this requirement will likely be satisfied by following the 40 CFR 63 Subpart H regulations. To avoid any confusion with the overlap provisions in these rules, information on how an AMEL may be used to satisfy the requirem ents in Subpart VVa is provided below.

Citation i n rule that requires gas streams to be controlled by a flare meeting 40 CFR 6 0 .1 8.

Several portions of Subpart VVa point to 40 CFR 60.482

- 10a. Section 60.482

- 10a( d) requires that flares used to comply with Subpart VVa shall comply with the requirements of §60.18.

Citation in the rule or Statutory Provision that allows EPA to approve an alternative

means of emission limitation

.

40 CFR 60.484a(a) and (b) al low EPA to permit the use of an alternative means of emission limitation if the owner/operator establishes to the satisfaction of the EPA that an alternative means of emission limitation will achieve a reduction in emissions of any air pollutant at least

e quivalent to the reduction in emissions of such air pollutant achieved under the requirements of the NSPS regulation.

Regulation

40 CFR Subpart 6 0 Subpart NNN ( Distillation Operations)

Citation i n rule that requires gas streams to be controlled by a f lare meeting 40 CFR 6 0 .1 8.

40 CFR 60.662(b) contains an option for control to combust the emissions in a flare that meets the requirements of §60.18.

Citation in the rule or Statutory Provision that allows EPA to approve an alternative

means of emissi on limitation

.

Section 111(h)(3) allows EPA to permit the use of an alternative means of emission limitation if the owner/operator establishes to the satisfaction of the EPA that an alternative means of5

emission limitation will achieve a reduction in emissions of any air pollutant at least equivalent to the reduction in emissions of such air pollutant achieved under the requirements of the NSPS regulation.

Regulation

40 CFR Subpart 6 0 Subpart RRR ( SOC MI Reactor Processes)

Citation i n rule that requires gas streams to be controlled by a flare meeting 40 CFR 6 0 .1 8.

40 CFR 60. 702 (b) contains an option for control to combust the emissions in a flare that meets the requirements of §60.18.

Citation in the rule or Statutory Provision that allows EPA to approve an alternative

means of emission limitation

.

Section 111(h)(3) allows EPA to permit the use of an alternative means of emission limitation if the owner/operator establishes to the satisfaction of the EPA that an alternative means of emission limitation will achieve a reduction in emissions of any air pollutant at least equivalent to the reduction in emissions of such air pollutant achieved under the requirements of the NSPS regulation.

Regula tion

40 CFR Subpart 6 1 Subpart FF

Citation i n rule that requires gas streams to be controlled by a flare meeting 40 CFR 6 0 .1 8.

40 CFR 6 1.349(a)(2)(iii) contains an option for control to combust the emissions in a flare that meets the requirements of §60.18.

Citation in the rule or Statutory Provision that allows EPA to approve an alternative

means of emission limitation

.

40 CFR 61.353 (a) allows EP A to permit the use of an alternative means of emission limitation if the owner/operator establishes to the satisfaction of the EPA that an alternative means of emission limitation will achieve a reduction in emissions of any air pollutant at least equival ent to the reduction in emissions of such air pollutant achieved under the requirements of the regulation.6

Regulation

40 CFR Subpart 63 Subpart H (Equipment Leaks)

Citation in rule that requires gas streams to be controlled by a flare meeting 40 CF R

63.11 (b)

.

40 CFR 63.172(d) requires that flares used to comply with Subpart H shall comply with the requirements of §63.11(b) of Subpart A. §63.180) ( e) reiterates which portions of §63.11(b) apply when a flare is used comply with §63.172(d).

Citat ion in the rule that allows EPA to approve an alternative means of emission limitation or approve an alternative non opacity emission standard.

40 CFR 63.177(b)(1) allows an owner/operator to apply for permission to use an alternative

means of emission limitation under §63.6(g) of 40 CFR 63 Subpart A

.

Regulation

40 CFR Subpart 63 Subpart FFFF (Miscellaneous Organic NESHAP)

Citation in rule that requires gas streams to be controlled by a flare meeting 40 CFR

63.11 (b)

.

40 CFR 63.2450(a) requires the owner/operator to be in compliance with the emission limits and work practice standards in Table 1 through 7. Table 1 and Table 2 of Subpart F provide a control option for reducing the emissions using a flare.

40 CFR 63.24 50(e)(2) requires that vent gas streams that are routed through a closed

- vent system to a flare meet the requirements of §63.982(b), which the n requires one to meet §63.987 for flares, which requires a flare to meet the requirements in §63.11(b).

Citation in the rule that allows EPA to approve an alternative means of emission limitation or approve an alternative non opacity emission standard.

40 CFR 63.2545( b ) (1) allows EPA to approve alternatives to the non

- opacity emission limits and work practice sta ndards in §63.2450(a) under §63.6(g).7

R egulatory Requirements for Light Hydrocarbons Plant Flare System

The following EPA air regulations will apply to various streams that are collected and routed to

this flare and discuss es how each rule allows for an Alternative Means of Emission Limitation.

Regulation

40 CFR Subpart 6 0 Subpart Kb ( Storage Tanks)

Citation i n rule that requires gas streams to be controlled by a flare meeting 40 CFR 6 0 .1 8.

40 CFR 60. 112b(a)(3)(ii) contains an option for control to combust the emissions in a flare that meets the requirements of §60.18.

Citation in the rule or Statutory Provision that allows EPA to approve an alternative

means of emission limitation

.

40 CFR 60.114b allows EPA to permit the use of an alternative means of emission limitation if the owner/operator establishes to the satisfaction of the EPA that an alternative means of emission limitation will achieve a reduction in emissions of any air po llutant at least equivalent to the reduction in emissions of such air pollutant achieved under the requirements of the NSPS regulation.

Regulation

40 CFR Subpart 6 0 Subpart VVa

Citation i n rule that requires gas streams to be controlled by a flare me eting 40 CFR 6 0 .1 8.

Several portions of Subpart VVa point to 40 CFR 60.482

- 10a . Section 60.482

- 10a (d) requires that flares used to comply with Subpart VVa shall comply with the requirements of § 60.18.

Citation in the rule or Statutory Provision that allows EPA to approve an alternative

means of emission limitation

.

40 CFR 60. 484a(a) and (b) allow EPA to permit the use of an alternative means of emission limitation if the owner/operator establishes to the satisfaction of the EPA that an alter native means of emission limitation will achieve a reduction in emissions of any air pollutant at least equivalent to the reduction in emissions of such air pollutant achieved under the requirements of the NSPS regulation.8

R egulation

40 CFR Subpart 6 0 Subpart NNN ( Distillation Operations)

Citation i n rule that requires gas streams to be controlled by a flare meeting 40 CFR 6 0 .1 8.

40 CFR 60.662(b) contains an option for control to combust the emissions in a flare that meets the requirements of §60 .18.

Citation in the rule or Statutory Provision that allows EPA to approve an alternative

means of emission limitation

.

Section 111(h)( 3) allows EPA to permit the use of an alternative means of emission limitation if the owner/operator establishes to the satisfaction of the EPA that an alternative means of emission limitation will achieve a reduction in emissions of any air pollutant at l east equivalent to the reduction in emissions of such air pollutant achieved under the requirements of the NSPS regulation.

Regulation

40 CFR Subpart 6 0 Subpart RRR ( SOCMI Reactor Processes)

Citation i n rule that requires gas streams to be controlled by a flare meeting 40 CFR 6 0 .1 8.

40 CFR 60. 702 (b) contains an option for control to combust the emissions in a flare that meets the requirements of §60.18.

Citation in the rule or Statutory Provision that allows EPA to approve an alternative

means of emission limitation

.

Section 111(h)(3) allows EPA to permit the use of an alternative means of emission limitation if the owner/operator establishes to the satisfaction of the EPA that an alternative means of

emission limitation will achieve a reductio n in emissions of any air pollutant at least equivalent to the reduction in emissions of such air pollutant achieved under the requirements of the NSPS regulation.9

Regulation

40 CFR Subpart 6 1 Subpart FF

Citation i n rule that requires gas streams to be controlled by a flare meeting 40 CFR 6 0 .1 8.

40 CFR 6 1.349(a)(2)(iii) contains an option for control to combust the emissions in a flare that meets the requirements of §60.18.

Citation in the rule or Statutory Provision that allows EPA to approve an alternative

means of emission limitation

.

40 CFR 61.353 (a) allows EPA to permit the use of an alternative means of emission limitation if the owner/operator establishes to the satisfaction of the EPA that an alternative means of

emission limitati on will achieve a reduction in emissions of any air pollutant at least equivalent to the reduction in emissions of such air pollutant achieved under the requirements of the regulation.

Regulation

40 CFR Subpart 63 Subpart UU (Equipment Leaks)

Citation in rule that requires gas streams to be controlled by a flare meeting 40 CFR

63.11 (b)

.

Several portions of Subpart UU point to 40 CFR 63.1034. 40 CFR 63.1034(b)(2)(iii) requires that flares used to comply with Subpart UU shall comply with the requirements of 40 CFR 63 Subpart SS. 40 CFR 63 Subpart SS (specifically §63.982(b) and §63.987) require a flare to meet the requirements §63.11(b).

Citation in the rule that allows EPA to approve an alternative means of emission limitation

or approve a n alternative non opacity emission standard.

40 CFR 63.1021 (a)

– (d) allow EPA to issue an alternative means of emission limitation.10

Regulation

40 CFR Subpart 63 Subpart XX ( Heat Exchange Systems and Waste Operations)

Citation in rule tha t requires gas streams to be controlled by a flare meeting 40 CFR

63.11 (b)

.

This rule references portions of the 40 CFR 61 Subpart FF requirements, which in turn require a flare to meet the 40 CFR 60.18 requirements.

Citation in the rule that allows E PA to approve an alternative means of emission limitation or approve an alternative non opacity emission standard.

40 CFR 63.10 97 ( b ) (1) allow s EPA to approve alternatives to the nonopacity emission standards.

Regulation

40 CFR Subpart 63 Subpart YY ( Generic Maximum Achievable Control Technology

– Ethylene

Production )

Citation in rule that requires gas streams to be controlled by a flare meeting 40 CFR

63.11 (b)

.

Table 7 of this rule requires storage vessels, ethylene p rocess vents, and transfer racks to comply with various portions of 40 CFR 63 Subpart SS. Subpart SS (specifically §63.982(b) and § 63.987 (a) ) require that a flare meets the requirements of §63.11(b).

Citation in the rule that allows EPA to approve an alternative means of emission limitation or approve an alternative non opacity emission standard.

40 CFR 63.1 113 ( a ) allows EPA to approve an alternative means of emission limitation

. If, in the judgment of the Administrator, an alternative means of emi ssion limitation will achieve a reduction in HAP emissions at least equivalent to the reduction in emissions from that source achieved under any design, equipment, work practice, or operational standards (but not performance standards) in this subpart, the Administrator will publish in the F EDERAL R EGISTER a notice permitting the use of the alternative means for purposes of compliance with that requirement.11

Demonstration of Equivalency

– Pressure

- Assisted Flares

In order to demonstrate that the proposed pressure

- assisted flare systems will achieve a reduction in emissions at least equivalent to the level of reduction in emissions from a flare meeting the exit velocity provisions outlined in 40 CFR 60.18(c)(3 )

- (c )(5) and 40 CFR 63.11(b)(6 )

– (b)( 8), the owner or operator must demonstrate that the flare achieves a 96.5 combustion efficiency (or 98 percent destruction efficiency).

The Dow Chemical Company opted to conduct a series of emission tests at a flare vend or’s flare testing facility in order to make this demonstration. In order to capture the range of expected flow rates and gas compositions, the testing program consisted of multiple test runs where the following gas mixtures were flared:

1. Propylene ;

2. Mi xtures of propylene and nitrogen ; and

3. Mixtures of propylene, nitrogen, and natural gas (Tulsa, Oklahoma natural gas).

The purpose of the testing was to confirm a high destruction efficiency for propylene and a high combustion efficiency over a broad range of operating conditions. The test program involved both extractive sampling and analysis along with measurements made by PFTIR (Passive Fourier Transform Infrared) an alysis.

A complete copy of the emission testing report was provided to EPA on February 18, 2014. The test results are provided in the following tables from the test report.

Table JZ

- 2 from Test Report12

Table JZ

- 4 from Test Report

Test Runs and Notes:

P1 H and P1L : 100% propylene

P2 H and P2L : Mixture of propylene and nitrogen

P3 H and P2L : Mixture of 50% propylene, 50% natural gas, then diluted with nitrogen P4: 90% hydrogen / 10% natural gas

P1

- P3: At high pressure ( Tests P1 H, P2H, and P3H = highest gas flows with an exit velocity at

or near sonic velocity) and low pressure ( Tests P1L, P2L, and P3L lower gas flows representing

de

- staging). 3 tests were conducted under each condition for a duration of 20 minutes

. P2

- P3: The flare was operated at the minimum heating value that ha d flame stability, then the emission test was conducted at this point.

. P4: Test for flame stability only, 5 minutes. Detailed emission measurements were not

conducted for this test.

The test results show that the destruction efficiency of propylene was well above 98% and the overall combustion efficiency was well above 96.5%. Thus, the test results demonstrate that the

pressure

- assisted flare will achieve a destruction efficiency and combustion efficiency that is equivalent to and actually better than a flare meeting the exit velocity restrictions in 40 CFR

60.18 and 40 CFR 63.11.

Furthermore, Dow believes that the gas mixtures will be representative of the types of hydrocarbons co mbusted in each flare system as discussed below. Dow further proposes to operate each of the flare systems in accordance with the parameters included later in this

document to ensure combustion with a stable flame, thus resulting in very high destruction and

combustion efficiencies.

PDH

- 1 Flare System

The PDH

- 1 flare system will consist of 8 stages of flare tips. The first stage of flare tips will be operated in accordance with existing flare regulations in 40 CFR 60.18 and 40 CFR 63.11. Stages 2 thr ough 8 will consist of pressure

- assisted flare tips. Stages 2 through 8 will handle vent gas flows during a variety of start

- up, shutdown, maintenance, and process upset conditions. The system is controlled by a process control system that monitors the m ain header pressure. As the pressure rises (indicating more flow), the next stage is opened. Should the pressure continue to rise, the next stage opens. If the pressure falls, the staging valves close in reverse sequence. During plant start

- ups, common hydrocarbons including, but not limited to: ethane, propane, and propylene will be vented to the flare system. During plant shutdowns, common materials including, but not limited to: hydrogen, methane, ethylene, ethane, propylene, and propane will13

be ve nted to the flare system. In general, a pressure

- assisted flare burning a gas that has a wide flammability limit range is easier to stabilize than one with a narrow flammability limit range

. Due to its relatively narrow flammability limit range, and the expected venting rates, propylene was used during the testing. The table below shows the various LFL% and UFL% values. Thus, it is reasonable to expect that if mixtures of propylene, natural gas, and nitrogen burn well, that the other common hydrocarbon s should be destroyed/combusted at very similar levels.

Compound LFL % by Volume in Air UFL % by Volume in Air Propylene 2.4 11.0

Ethane 3.0 12.4 Ethylene 2.7 36.0 Hydrogen 4.0 75.0

Methane 5.0 15.0 Propane 2.1 9.5

LHC

- 9 Flare System

The LHC

- 9 flare system will consist of 13 stages of flare tips. The first stage of flare tips will be operated in accordance with existing flare regulations in 40 CFR 60.18 and 40 CFR 63.11. Stages 2 through 13 will consist of pressu re

- assisted flare tips. Stages 2 through 13 will handle vent gas flows during a variety of start

- up, shutdown, maintenance, and process upset conditions. The system is controlled by a process control system that monitors the main header pressure. As

the pressure rises (indicating more flow), the next stage is opened. Should the pressure continue to rise, the next stage opens. If the pressure falls, the staging valves close in reverse sequence.

Based on preliminary design information, common material s including, but not limited to: hydrogen, methane, ethane, ethylene, propane, and propylene will constitute the majority of the hydrocarbons vented to this flare system during plant start

- ups, shutdowns, maintenance venting, and process upset conditions.

Similar to the discussion above for the PDH

- 1 flare, it is reasonable to expect that if mixtures of propylene, natural gas, and nitrogen burn well, that other common hydrocarbons should be destroyed/combusted at very similar levels.

In order to ensure that both flare systems operate with a stable flame and operate with a destruction efficiency that is equal to or greater than 98% and a combustion efficiency that is equal to or greater than 96.5%, the operating conditions on the follow ing pages are suggested for

inclusion into the Alternative Means of Emission Limitation.14



### Alternate Means of Emission Limitation Operating Conditions

The Dow Chemical Company, Texas Operations

(RN 100225945)

1. This AM EL plan authorization shall apply at the Dow Chemical Company, Texas Operations. The facilities are covered by TCEQ Regulated Entity Number: R N

100225945.

2. A copy of the application and the AM EL Plan Authorization conditions must be kept

on

- site or at a c entralized location and made available at the request of personnel
from the TCEQ or any pollution control agency with appropriate jurisdiction. The application is defined by the AM EL application dated August 20, 2013, and
subsequent supporting documents d ated February 18, 2014 , and August 5, 2014

.

3. This authorization is granted under Title 30 Texas Administrative Code § 115.910 (30

TAC § 115.910) and addresses issues associated with the use of these flare systems for emission sources regulated by 30 TAC 115 Subchapters B through H, as
applicable, including 30 TAC § 115.722(d) and § 115.722(d)(2), and shall apply in lieu
thereof. This authorization is also granted for the use of these flare systems for emission sources regulated by applicable subparts of 40 CFR §§ 60, 61, and 63, as
approved by the United States Environmental Protection Agency. Compliance with

this AM EL is independent of Dow Chemical’s obligation to comply with all other
TCEQ permits and all other applicable EPA R egulations and TCEQ Regulations.

4. The following stationary pressure

- assisted flares are covered under this AM EL plan:

PDH

- 1 Flare (EPN OC4F9552) and LHC

- 9 flare (EPN OC2F9562) . All flare tips covered

under the AM EL plan shall be as specified in the AM EL application.

5. Flares shall be designed and operated in accordance with the following
requirements:

A. The flare systems shall be designed and operated such that the waste gas stream flowing to each pressure

- assisted flare system meets the following minimum net
heating v alue in terms of British thermal units/standard cubic foot of the gas (Btu/scf) on an hourly average basis under normal, upset, maintenance, start

- up,
and shutdown flow conditions when the flare system is operated with the

pressure

- assisted flare burners i n service. The net heating value shall be satisfied at all times during the operations authorized by this AMOC unless the
flare systems meet the 40 CFR § 60.18 specifications o f minimum heating value
and maximum tip velocity. Flare testing per 40 CFR § 60. 18(f) may be requested15

by the appropriate regional office to demonstrate compliance with these
requirements.

Flare Name EPN Waste Gas Minimum Net Heating Value (Btu/scf)

PDH

- 1 Pressure Assisted

Flare OC4F9552 800

PDH

- 1 Pressure Assisted Flare (Shutdown Steps (1)) OC4F9552 690

PDH

- 1 Pressure Assisted Flare Hydrogen Case (2) OC4F9552 270

LHC

- 9 Pressure Assisted

Flare (3) OC2F9562 690

LHC

- 9 Pressure Assisted Flare Hydrogen Case (2) OC2F5962 270

1) The shutdown case cover s certain phases of the planned shutdown where the
systems are being purged with nitrogen and methane. 2) The hydrogen case is one where the mole fraction of hydrogen in the waste gas
stream is greater than 75%. The net heating value of pure hyd rogen is approximately 270 Btu/scf, thus 270 Btu/scf is used in this case.
3) A net heating value of 690 Btu/scf is suggested for this case since the volumetric net heating value of Ethylene is 1,477 Btu/scf vs. the volumetric net heating
value of Propylene which is 2,150 Btu/scf. This value is more conservative for
ethylene gas since a net heating value of 690 Btu/scf represents a mole fraction of ethylene in nitrogen of 0.467, and a net heating value of 800 Btu/scf
represents a mole fraction of propylene in nitrogen of 0.372.

B. Each flare system shall be operated with a flame present at all times when in use. Each row of flare tips shall have at least one pilot with a constant pilot flame. The pilot flame(s) shall be continuously monitored by a thermoc ouple. The time, date, and duration of any loss of pilot flame shall be recorded. Each monitoring device shall be maintained or replaced at a frequency in accordance with the manufacturer’s specifications.

C. Each flare system shall be operated with no visible emissions except for periods
not to exceed a total of five minutes during any two consecutive hours. A video

camera can be used in order to conduct visible emission observations since operating personnel cannot enter the fenced area while the MPFG flare is
operating.16

D. Natural gas or off

- gas combusted at the flares shall be sweet natural gas or off

gas containing no more than five grains of total sulfur per 100 dry standard cubic

feet.

6. The AM EL plan authorization holder shall install and operat e an on

- line vent gas flow

meter and an on

- line gas chromatograph to measure the flow and composition of the vent gas to each flare. The holder shall comply with all applicable Monitoring
and Testing Requirements and Recordkeeping and Reporting Requiremen ts for these monitoring systems as specified in 30 TAC §§ 115.725 and 115.726, effective
December 23, 2004.17

August 20, 2013

– Original Request1819