ARKANSAS DEPARTMENT OF POLLUTION CONTROL AND ECOLOGYDIVISION OF AIR POLLUTION CONTROL

Summary Report Relative to Permit Application

Submitted By:

CSN: 470268

Arkansas Western Gas CompanyAssociated Natural Gas LNG Plant0.4 miles north of Yarbro

Yarbro, Arkansas 71845Contact Person: Mr. Ron G. Carver

Manager, Environmental AffairsTelephone # (501) 521-5400

Permit No.: 1551-A Date Issued: 10/17/94

Submittals: May 12, 1994; July 7, 1994; July 13, 1994; July 27, 1994; August 8, 1994

Summary

Arkansas Western Gas Company, hereafter known as AWG, proposes to permit an existingAssociated Natural Gas LNG Plant located near Yarbro, Arkansas. This is the first airpermit for the facility. This facility is not subject to 40 CFR Part 60 Subparts Ka and KKK- Standards of Performance for Storage Vessels and Equipment Leaks of VOC From OnshoreNatural Gas Processing Plants because the facility was constructed in 1971.

The primary operations at the Liquefied Natural Gas (LNG) plant are the purification of feednatural gas, the liquefication of purified natural gas, and the vaporization of liquefied naturalgas.

A brief description of the primary operations at the facility are described below:

Purification: Natural gas is taken from the pipelines during summer or when therequirement is low and is purified for non-hydrocarbon compounds in the feed stream,mostly water (H20) and carbon-dioxide (C02), to avoid any crystallization upon thesubsequent processing of the feed natural gas. Non-hydrocarbon compounds in the feedstream are reduced by employing an adsorption process. Three adsorbent towers are used atthe facility. In each tower a fixed bed of molecular sieve (grade 4A, 1/16" pellets coatedwith 20 percent inert clay binder) is used as an adsorbent. During the adsorption cycle, theadsorption bed is maintained at high pressure and low temperature to increase the adsorptioncapacity. Adsorption of adsorbates on the molecular sieve depends on the polarity of themolecules. The molecular sieve preferentially adsorbs the compounds in the following order:water, carbon-dioxide, methane, and ethane etc. The saturation of the adsorbent bed isdetermined when the carbon-dioxide concentration in the effluent gas starts rising to a criticalvalue. At this time the feed stream is switched to another adsorption tower.

Installation: N/ A

Reviewed By: Srinivas BandaruApplicable Regulation: Air Code, SIP

Operation: ExistingApproved By: J.B. Jones

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Arkansas Western Gas CompanyAssociated Natural Gas LNG PlantPermit # 1551-ACSN: 470268

When an adsorption bed is completely saturated, it is regenerated to desorb the adsorbedcompounds. Regeneration is performed by sending a clean tail gas flowing up through thesaturated bed. This upward flow of a clean tail gas in a direction opposite to the flow of thegas during adsorption enhances the desorption rate. The regeneration gas is heated in anindirect, gas fired, molten salt bath heater (SN-09). At the end of regeneration process, thebed is hot and at a higher pressure than operating pressure. Before returning the tower tothe adsorption cycle, the bed is depressurized and cooled with clean tail gas. In normaloperation, the processes taking place in the three towers are adsorption, regeneration, andcooling.

Liquefication: The liquefication of natural gas is accomplished in three phases of cooling.They are: precooling, liquefication, and subcooling. Natural gas is precooled by chilledwater, halocarbon refrigerant (R-22), and cold flash and boil off gases. After precooling, thefeed (natural gas) is totally condensed in a Sterling Liquefier, then flashed and subcooled.The liquefied natural gas, which is under pressure, is then sent to the LNG storage tank.The following equipment is used in the liquefication of natural gas.

Water Chiller: The water chiller (York Model HT Hermetic Turbopak) is a single stagewater cooling system similar to those used in large air conditioning systems. The refrigerant(R-ll) vapor produced in the evaporator cools the water tube bundle to 50 to 40 degrees P.

Halocarbon Refrigeration System: Liquefied natural gas production at maximum design rate,cannot be met unless the halocarbon refrigeration system is on line. The halocarbonrefrigeration system is a two stage refrigeration system (low and high stage) usingchlorodifloromethane refrigerant, commercially known as R-22. In low and high stages, thesystem delivers -750p and 60oP. In case of a catastrophic accident an amount of 14 tons ofR-22 refrigerant may be released into the ambient air.

Sterling Liquefier or Cryogenerator: The total condensation or liquefaction from the feed gasstream is done in two liquefiers referred to hereafter by their trade name "cryogenerators."Each cryogenerator is a cold source based on the Sterling refrigeration cycle using heliumgas as the working medium.

Boil Off and Flash Gas Compressors: The function of these two electric belt drivencompressors is to recompress the gas returning from the LNG tank, "boil off gas" and "flashgas" returning from the heat exchanger in the cold box and the flash drum.

The final temperature of the liquid natural gas is approximately at 260 degrees P below zero.The liquefaction takes place in the following order: compression, Joule-Thompson (J-T)expansion, and heat transfer steps.

The liquefied natural gas is stored in a large insulated pressure tank. The storage tank is anabove ground metal tank and consists of essentially two metal tanks, one inside the other.

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Arkansas Western Gas CompanyAssociated Natural Gas LNG PlantPermit # 1551-ACSN: 470268

The inner tank, which is directly in contact with the liquefied natural gas and cold gas vapor,has a minimum liquid capacity of 55,000 barrels contained between the tank bottom and 12inches below the top of the tank shell. The storage tank is protected by pressure reliefvalves and vacuum relief valves. The storage tank relief valves and the other relief valveson the other equipment/processes may release a combined amount of 15 million standardcubic feet of natural gas/methane per year.

Vaporization: Liquefied natural gas is vaporized in direct fired LNG vaporizers (SN-04,05, 06, and 07) at a rate of 259 gpm of LNG to 600p gas at a maximum pressure of 465psig. Vaporized LNG is routed back to pipeline transmission and distribution. Natural gasis used as a fuel in the vaporizers.

A steam generator (SN-08) supplies saturated steam to the liquefication building andliquefied natural gas pumps. An oil tank with vent (SN-ll), 3.5 feet diameter by 8 feetlong; is used to collect used motor oil in bulk to give it to the recycling marketers. The flareequipment consists of three (3) flare pilots (SN-19, 20, and 21) and one (1) flare burner(SN-22). The flare equipment is used for complete burning of emergency and waste fuelsgenerated at the facility. The flare burner is utilized for a clean burning of hydrocarbons orfor the emergency relief system, where no steam or other medium for smokeless flaring isavailable.

Emergency electric power is provided by a diesel fired engine (SN-03) with diesel tank vents(SN-Ol and 02). Water supply for the plant is obtained from Yarbro Rural Water Districtthrough metered service. Backup water supply and firewater supply is provided using a waterpump engine (SN-25) with vents (SN-23 and 24).

Emissions from the facility consist of particulate matter (PM/PMIO), volatile organiccompounds (VOC), oxides of nitrogen (NOx), and carbon monoxide (CO). This facility willbe regulated under the Arkansas Plan of Implementation for Air Pollution Control (SIP). Acomplete list of emission limits can be found in Table I of this permit.

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Arkansas Western Gas CompanyAssociated Natural Gas LNG PlantPermit # 1551-ACSN: 470268

Specific Conditions

1. Emissions shall not exceed the emission limits set forth in Table I. Emissionsfrom any point source not specifically listed in Table I of this permit shall be aviolation of this condition.

2. Visible emissions, as measured by EPA Method 9, shall not exceed the opacity valuesspecified in Table I.

3. Operations shall not be conducted in a manner which would cause visible emissions toextend beyond the property line of the affected facility or which would interfere withthe attainment of the National Ambient Air Quality Standards. Non-compliance withthis condition shall be considered a violation of mass emission limits set forth inSpecific Condition #1 above.

4. AWG shall use only natural gas as a fuel for all four (4) vaporizers (SN-04, 05, 06,and 07). Natural gas usage shall not exceed a combined value of 172,000 standardcubic feet per hour, or 740.6 million standard cubic feet per year. For each vaporizer,the permittee shall maintain a record of natural gas consumption per hour based on themonthly natural gas usage and the hours of operation of each vaporizer per month,subject to all the conditions specified in Table I. This record shall be updated eachmonth and shall be made available to Department personnel upon request.

5. AWG shall limit the generator engine (SN-03) to 1,200 revolutions per minute, andannual hours of operation to 1,000 hours.

6. AWG shall limit the water pump engine (SN-25) to 1,800 revolutions per minute, andannual hours of operation to 604 hours.

7. The permittee shall maintain a monthly record of the hours of operation of sourcesSN-03 and SN-25. This record shall be updated each month and shall be madeavailable to Department personnel upon request.

8. As described in the permit application, the tanks used for the storage of methane andnatural gas shall be limited only for the storage of methane and natural gas.

9. Any modifications, construction, or reconstruction shall be reported to theDepartment in advance.

10. The permittee shall operate all equipment and associated control devices within designspecifications as described in the permit application at all times.

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ArKansas Western Gas CompanyAssociated Natural Gas LNG PlantPennit # 1551-ACSN: 470268

TABLE I

ex>

ALLOW ABLE EMISSION RATESSN

Description ControlHours of Pollutant

EquipmentOperation Per

PM/PMlO

VOCNOxCOOpacityYearlb/hr

tpylb/hrtpylb/hrtpylb/hrtpy

01

Diesel Tank Vent None8736---0.1----5%

#1 (East)02

Diesel Tank Vent None8736---0.1----5%

#2 (West)03

Generator (Diesel) None10000.20.10.20.117.58.83.01.515%

04

Vaporizer #A None43200.61.30.20.36.013.01.53.35%

05

Vaporizer #B None43200.61.30.20.36.013.01.53.35%

06

Vaporizer #C None43200.61.30.20.36.013.01.53.35%

07

Vaporizer #D None43200.61.30.20.36.013.01.53.35%

08

Steam Generator None87360.10.40.10.40.20.90.10.410%

(Natural Gas)09

Salt Bath Heater None87360.10.40.10.40.10.40.10.45%

11

Oil Tank Vent None8736---0.1----5%

\.0

ArI<.ansasWestern Gas CompanyAssociated Natural Gas LNG PlantPermit # 1551-ACSN: 470268

TABLE I

ALLOW ABLE EMISSION RATESSN

DescriptionControlHours of Pollutant(lb/hr)Equipment

Operation PerPM/PM 10

VOCNOxCOOpacityYearIb/hr

tpyIb/hrtpyIb/hrtpyIb/hrtpy

19

Flare Pilot # 1None87360.10.40.10.40.10.40.10.45%

20

Flare Pilot #2None87360.10.40.10.40.10.40.10.45%

21

Flare Pilot #3None87360.10.40.10.40.10.40.10.45%

22

Flare Burner None101.30.1100.11250.7250.25%

23

Diesel Tank Vent #1None8736---0.1----5%

24

Diesel Tank Vent #2None8736---0.1----5%

25

Water Pump Engine None604--0.60.25.01.548.21515%

(Diesel)

Total PM/PMlO: 4.4 Ib/hr; 7.4 tons/yr. Total VOC: 12.11b/hr; 4.1 tons/yr. Total CO: 82.7 Ib/hr; 31.9 tons/yr.Total NOx: 172.1 Ib/hr; 65.5 tons/yr.

CERTIFICATE OF SERVICE

I, James B. Jones, Jf., hereby certify that a copy of this permit has been

mailed by first class mail to Arkansas Western Gas Company - Associated Natural

Gas LNG Plant, Post Office Box 1288, Fayetteville, Arkansas 72702-1288, on

this /7 t1v day of Dc- f 0 ,6t'R , 1994.