The Texas Commission on Environmental Quality posted to its website on Nov. 18 a Nov. 16 notice about plans to approve air permitting for an addition to an existing facility in San Patricio County being sought by Corpus Christi Liquefaction Stage III LLC.
This application was submitted to the TCEQ on March 22. The commission’s executive director has determined that the emissions of air contaminants from the existing facility which are subject to PSD review will not violate any state or federal air quality regulations and will not have any significant adverse impact on soils, vegetation, or visibility.
Corpus Christi Liquefaction LLC (CCL) owns and operates a liquefied natural gas (LNG) terminal, located near Gregory in San Patricio County. The facility has the capability to liquefy natural gas from the pipeline system for export as LNG or import LNG and regasify it to send it out into the pipeline system.
CCL requests this new authorization for the Corpus Christi Liquefaction Terminal Stage III Project (CCL Stage III), which will consist of two new LNG trains, Train 4 and 5. Trains 4 and 5 will consist of 12 natural gas compressor turbines, two thermal oxidizers, two sets of flares each comprised of one wet gas flare and one dry gas flare, two amine surge tanks, three diesel generators, three fire-water pump diesel engines, six fixed roof diesel storage tanks, and piping components.
Each new train will consist of six General Electric LM2500+G4, dry-low NOX (DLN), natural gas- or boil off gas-fired compressor turbines for a total of 12 turbines. Each of the trains will consist of six turbines, two methane, two propane, and two ethylene refrigeration turbines. All turbines will operate continuously (8,760 hours per year) and will be permitted to operate at full load.
Because these gas turbines will be used for compression, they will have variable operating characteristics with hotter and cooler exhaust temperatures and therefore different emission rates associated with each turbine.
Two sets of flares, each set comprised of one wet flare and one dry flare, will be constructed. Vent flows to the wet/dry flares will result from gas flow of small amounts of refrigerant from compressor seal leakage, and intermittent flow resulting from planned inspection and maintenance activities.
As for refrigeration compressor turbine NOx emissions, the control technology review showed three control options were technically feasible: dry low NOX (DLN) combustor technology achieving 25 parts per million by volume dry (ppmvd) at 15% oxygen (%O2 ), water or steam injection which achieved the same emissions as DLN combustor technology, and selective catalytic reduction (SCR) achieving 80% control of the dry or water-injected turbine (5 ppmvd at 15% O2 ).
A database search has concluded that while no LNG plants have operated with SCR, turbines of this size have been operated with SCR in power plants and cogeneration facilities. Two LNG plants which are currently under construction, Freeport LNG Pretreatment in Texas and Cove Point LNG in Maryland, were subject to non-attainment review for NOx and subject to LAER requirements and will use SCR. The applicant was required to investigate the feasibility of installing SCR. It determined the cost of NOx reduction by using the EPA Cost Control Manual with all direct and indirect costs to calculate a cost in dollars per ton to reduce NOx from 25 ppmvd to 5 ppmvd. The cost of the SCR system was found to be about $21,000 per ton of NOX emission reduction for the turbines. This cost is not considered economically reasonable and SCR is rejected from further consideration. As a result, DLN combustor technology achieving 25 ppmvd at 15% O2 is BACT for NOx.