PERMIT MEMORANDUM NO. 2007-210-O DRAFT Page 14
OKLAHOMA DEPARTMENT OF ENVIRONMENTAL QUALITY
AIR QUALITY DIVISION
MEMORANDUM June 24, 2008
TO: Phillip Fielder, P.E., Permits & Engineering Group Manager,
Air Quality Division
THROUGH: Kendal Stegmann, Sr. Environmental Manager, Compliance & Enforcement
THROUGH: Jian Yue, P.E., Engineering Section
THROUGH: Phil Martin, P.E., Engineering Section
THROUGH: Peer Review
FROM: Iftekhar Hossain, P.E., Engineering Section
SUBJECT: Evaluation of Permit Application No. 2007-210-O
Mustang Gas Products LLC
Covington Compressor Station
Section 19, Township 22N, Range 3W, Garfield County, Oklahoma.
Latitude: 36.368oN, Longitude: 97.567oW
Directions: From Covington, North on SH-74 3.5 Miles, East on County
Road 1 Miles, North 0.5 Mile.
INTRODUCTION
Mustang Gas Products LLC (Mustang) has requested a minor source operating permit for Covington Compressor Station (SIC 1311). The facility is currently operating under Permit No. 2003-116-TVR (M-3) issued June 20, 2007. In this application, the permittee seeks to incorporate the following:
· Installation of air-fuel ratio controls (AFRC) and a catalytic converter (CC) on engines CM-7 and CM-19.
· Incorporate into the permit a new 0.5 MMBTUH in-line heater which was constructed as an insignificant activity under Permit No. 2003-116-TVR (M-3) dated June 20, 2007, in accordance with the notification submitted February 4, 2008.
· Conduct pilot test (to last no more than 90 days) to observe the system performance and avoid frequent condensate loading from the pressurized tanks. The pressurized condensate is a high specific gravity condensate. The pilot test will increase the temperature of the condensate (with a new heater), resulting in the high end components becoming a gas when routed to the inlet separator. The liquids and gasified high end components will be routed to the inlet of the facility at the inlet separator where gases are sent to compression and liquids are sent to the existing atmospheric storage tanks (TK-1, TK-2, and TK-4). This will stabilize the system, maximize the amount of gas compressed, and facilitate condensate loading from the atmospheric tanks. Current VOC emission rate limits and condensate throughput limits at the atmospheric tanks will be met during the test.
· In the event the pilot test is successful, installation of a vapor recovery unit (VRU) on the atmospheric condensate tanks, TK-1, TK-2, and TK-4, will be completed within 90 days following the conclusion of the pilot test. Once the VRU is installed and operational, neither the condensate throughput limit nor the VOC emission limit from the atmospheric tanks will be required.
· In the event the pilot test does not achieve desired results, Mustang requests a revised condensate throughput and emission limitation be in place for all the atmospheric condensate tanks.
· Correct emission estimates for the glycol dehydration unit reboiler in accordance with AP-42 Chapter 1.4 (7/98).
After incorporating the requested changes, the worst-case (if VRU is not installed) total emissions from the facility are 98.31 TPY NOx, 97.91 TPY CO, and 80.85 TPY VOC, and the facility becomes a “synthetic minor” source. This permitting action will be reviewed as a significant modification of the current Part 70 operating permit; therefore, the permit will be processed under Tier II procedures.
PROCESS DESCRIPTION
The above-referenced facility is a natural gas compression station with two separate inlets to the facility, a low pressure inlet and a high pressure inlet. Natural gas enters the low pressure inlet to the facility through an inlet separator. The gas from the inlet separator is sent to compression split between compressor engines CM-7 (Unit 2842), the 1,100 hp White Superior 8GTL-825, and CM-11.2 (Unit 2820), the 1,235 hp Waukesha L7042GSI. Liquids from the inlet separator are sent to the atmospheric condensate tanks where generated condensate is trucked out.
Following compression from CM-7 and CM-11.2 the gas is sent to the glycol dehydration unit to remove water. Generated liquids from the first stage compressor scrubbers are sent to the atmospheric condensate tanks and generated liquids from the second and third stage compressor scrubbers are sent to the pressurized condensate tanks. The glycol dehydration unit is equipped with a flash tank and condenser on the still vent. Off gases from the flash tank and uncondensed vapors from the still vent are sent to the reboiler for use as fuel or recycled for recompression. The dried natural gas exiting the glycol dehydration unit is sent to sales or to a processing plant. Liquids generated from the condenser on the still vent and the condensed water at the reboiler are sent to the skimmer where any left over condensate, if present, is sent to the atmospheric storage tanks.
The high pressure inlet of the facility is a completely separate operation from the rest of the facility. High pressure natural gas enters compressor engine CM-19 (Unit 2800), the 600 hp Caterpillar G398 TA. The compressed natural gas is discharged from the facility.
A pig receiver is also located on-site. Liquids generated by the pigging operation are sent to the pressurized condensate tanks along with the condensate generated by the second and third stage compressor scrubbers. Liquids are either pressure trucked out or pipelined out of the facility. All vapors generated at the pressure tanks are routed back to the low pressure inlet separator. Vapors generated during the pressurized trucking are sent back to the pressurized tanks. There are no emissions from the pressurized condensate tanks during normal operation.
As discussed in the Introduction above, a pilot test is being conducted at the facility. The condensate from the pressurized condensate tanks will be heated up in an in-line heater. Rather than pressure trucking or pipelining the pressurized condensate out of the facility, the heated pressurized condensate will be routed to the inlet separator where gas is routed to compression and the liquids are routed to the atmospheric condensate tanks. If the pilot test is successful, a vapor recovery unit (VRU) will be installed on the atmospheric condensate tanks.
PERMITTING STATUS
The facility is a natural gas gathering compressor station responsible for gas dehydration and compression into a pipeline. The facility was originally exempt from permitting requirements based on construction prior to 1971 and permitting policies in effect at the time of construction of additional sources. The facility did receive construction permits in 1979 and 1991 for modifications.
In 1995, the facility was converted to a booster station by shutting down engines and combustion equipment. In place of the removed equipment, two compressor engines were installed and one engine was removed and reinstalled. Construction Permit No. 91-041-C (M-3) was issued on July 2, 1997 to address these modifications which were unpermitted.
In 1997, the applicant requested another modification to add two engines, to replace the glycol dehydrator with a larger one, and to increase the horsepower of two existing engines. This modification was authorized by Construction Permit No. 91-041-C (M-3). A JATCO vapor recovery system was later added to the dehydrator. Exhaust gases from the still vent are condensed to recover BTEX. Uncondensed vapors are routed to the reboiler for fuel. The JATCO unit has a minimum control efficiency of 97%.
In recent years, two compressor engines were shut down and removed from the plant. The shutdown was intended to be permanent, but the facility only recently removed those engines from the facility permit.
EQUIPMENT
A. Permitted Compressor Engines
EU ID # / Description / HP / Serial # / Construction DateCM-7 / White-Superior 8GTL825
4-cycle, lean burn / 1,100 / 275679 / 1995
CM-11.2 / Waukesha L7042GSI
4-cycle, rich burn / 1,232 / 180507 / 1997
CM-19 / Caterpillar G-398TA
4-cycle, rich burn / 600 / 73B1171 / 1993 (construction)
6/2007 (installation)
B. Glycol Dehydrator
EU ID # / Description / Construction DateEU-TEGV-1 / Glycol Dehydrator / 2003
C. Firetube Reboiler
EU / Description / MMBTUH / Construction DateTEGH-1 / Firetube Reboiler / 0.6 / 2003
D. In-Line Heater
EU / Description / MMBTUH / Construction DateHTR-1 / In-line heater / 0.5 / 2008
E (a) Condensate Tanks
EU / Point / Description / Capacity (gallons) / Construction DateTK-1 / EU-TK-1 / Condensate Tank / 8,820 / 1988
TK-2 / EU-TK-2 / Condensate Tank / 8,820 / Early 1980s
TK-4 / EU-TK-4 / Condensate Tank / 8,820 / 2004
E (b) Other Storage Tanks
EU / Point / Description / Capacity (gallons) / Construction DateTK-3 / EU-TK-3 / Process water / slop oil / 8,820 / 1980
TK-5 / EU-TK-5 / Condensate (pressurized) / 42,000 / 1952
TK-6 / EU-TK-6 / Condensate (pressurized) / 42,000 / 1952
TK-7 / EU-TK-7 / Glycol / 500 / Unknown
TK-8 / EU-TK-8 / Antifreeze / 250 / Unknown
TK-9 / EU-TK-9 / Antifreeze / 500 / Unknown
TK-10 / EU-TK-10 / Antifreeze / 750 / Unknown
TK-11 / EU-TK-11 / Antifreeze / 750 / Unknown
TK-12 / EU-TK-12 / Lube oil / 7,500 / 1985
TK-13 / EU-TK-13 / Waste oil / 8,600 / Unknown
TK-14 / EU-TK-14 / Methanol / 8,820 / 1982
TK-15 / EU-TK-15 / Methanol / 500 / Unknown
TK-16 / EU-TK-16 / Methanol / 1,000 / 1971
TK-17 / EU-TK-17 / Solvent / 500 / Unknown
TK-18 / EU-TK-19 / Lube Oil / 752 / 2007
TK-19 / EU-TK-19 / Antifreeze / 752 / 2007
TK-20 / EU-TK-20 / Methanol / 500 / 2007
TK-21 / EU-TK-21 / Waste Oil Pit / 900 / Unknown
Note: TK-21 is a waste oil pit, not a tank. A water-skimmer (TK-22) tank is also located on-site below grade. An accurate size is unknown and emissions are considered negligible.
F. Miscellaneous-Process Piping Fugitives (estimated component count)
Component / Service / Components #Valves / Gas / 835
Valves / Light Liquid / 160
Valves / Heavy Liquid / 208
Pump Seals / Light Liquid / 6
Flanges / Gas / 1,929
Flanges / Light Liquid / 197
Flanges / Heavy Liquid / 628
Relief Valves / All / 73
G. Equipment Blowdowns
EU / Point / Equipment / MMSCF/Yr / Construction DateATMV-1 / ATMV-1 / Atmospheric Vent / -- / 1971
H. Condensate Loading
EU / Point / Equipment / Volume, bbl/yr / Construction DateTL-1 / TL-1 / Condensate Loading / 19,963 / 1971
EMISSIONS
- Emission factors for NOx, CO, and VOC for engines are based on operator’s experience. Emission factors for formaldehyde are based on AP-42 (07/00), Chapter 3.2, Tables 3.2-2 and 3.2-3.
EU ID # / Engine Specification / NOxg/hp-hr / CO
g/hp-hr / VOC
g/hp-hr / Formaldehyde lb/MMBTU
CM-7 / 1,100-hp White-Superior 8GTL825 / 4.90 / 3.75 / 0.60 / 0.0528
CM-11.2 / 1,232-hp Waukesha L7042GSI / 2.0 / 3.0 / 0.40 / 0.0205
CM-19 / 600-hp Caterpillar G-398TA / 3.75 / 3.75 / 0.60 / 0.0205
- Reboiler and in-line heater combustion emissions are based on AP-42 (3/98), Section 1.4.
- Glycol dehydrator vent emissions are based on the GRI-GLYCalc program using a gas throughput of 7.5 MMSCFD and a glycol circulation rate of 1.5 GPM. An overall 97% control was used for condensing and venting uncondensed gases to the firebox or facility inlet.
- Fugitive VOC emissions are based on EPA’s 1995 Protocol for Equipment Leak Emission Estimates (EPA-453/R-95-017) and an estimated number of components and VOC content including a 25% safety factor.
- Loading emissions are based on AP-42 Chapters 5.2 (1/95) and 7.1 (9/97), using a condensate throughput of 19,963 bbl/year, molecular weight of 66, and a vapor pressure of 5.4 psia
- Emissions from storage tanks were estimated using the EPA software TANKS4.09 using a condensate throughput of 19,963 bbl/year per tank, molecular weight of 66, and a vapor pressure of 6 psia. Flash emissions were calculated using the Vazquez-Beggs correlation using default parameters
- Atmospheric vent emissions were based on an annual gas volume vented of 430,000 SCF with 20% VOC and include a 30% safety factor.
Table 1A: Criteria Pollutant Emissions
A. Pre-Modification Emissions
EU ID # / NOx / CO / VOClb/hr / TPY / lb/hr / TPY / lb/hr / TPY
EU-CM-7 / 43.65 / 191.19 / 14.55 / 63.73 / 4.85 / 21.24
EU-CM-11.2 / 5.45 / 23.87 / 8.17 / 35.78 / 1.09 / 4.77
EU-CM-19 / 19.67 / 86.15 / 12.76 / 55.50 / 2.38 / 10.41
EU-TEGH-1 / 0.06 / 0.26 / 0.01 / 0.04 / - / -
EU-TEGV-1 / - / - / - / - / 0.09 / 0.40
EU-TK-1 / - / - / - / - / - / 18.90*
EU-TK-2 / - / - / - / - / -
EU-TK-4 / - / - / - / - / -
EU-FUG-1 / - / - / - / - / 1.84 / 8.08
ATMV-1 / - / - / - / - / - / 4.91
TL-1 / - / - / - / - / - / 1.07
Totals / 68.83 / 301.47 / 35.49 / 155.05 / 10.25 / 69.78
*Combined emissions from working and breathing losses and flash emissions.
B. Post-Modification Emissions: If a VRU is installed and pressurized condensate from tanks TK-5 and TK-6 is sent through HTR-1 to the inlet separator where liquids are sent to the atmospheric tanks (TK-1, TK-2, and TK-4) and gas is sent to compression.
Table 1B: Post-Modification Emissions (with VRU)
EU ID # / NOx / CO / VOClb/hr / TPY / lb/hr / TPY / lb/hr / TPY
EU-CM-7 / 11.88 / 52.19 / 9.09 / 39.94 / 1.46 / 6.39
EU-CM-11.2 / 5.43 / 23.86 / 8.15 / 35.79 / 1.09 / 4.77
EU-CM-19 / 4.96 / 21.79 / 4.96 / 21.79 / 0.79 / 3.49
EU-TEGH-1 / 0.06 / 0.26 / 0.05 / 0.22 / 0.01 / 0.01
EU-TEGV-1 / - / - / - / - / 0.09 / 0.40
EU-HTR-1 / 0.05 / 0.22 / 0.04 / 0.18 / 0.01 / 0.01
EU-TK-1 / - / - / - / - / 0.00 / 0.00
EU-TK-2 / - / - / - / -
EU-TK-4 / - / - / - / -
EU-FUG-1 / - / - / - / - / 4.45 / 19.56
ATMV-1 / - / - / - / - / 1.12 / 4.91
TL-1 / - / - / - / - / 0.49 / 2.14
Totals / 22.38 / 98.31 / 22.29 / 97.91 / 9.49 / 41.68
NET CHANGES / -46.43 / -203.15 / -13.18 / -57.15 / -6.42 / -28.10
C. Post-Modification Emissions: If only low pressure condensate is sent to atmospheric tanks and a VRU is not installed.