Green Country gets permit for upgrade of Oklahoma power plant

The Oklahoma Department of Environmental Quality on Aug. 10 went out for comment on Green Country Energy LLC‘s requested second renewal of the Title V permit for a power plant located in Jenks, Okla.

This facility began operations in 2002 and consists of three combined cycle gas turbines, each with a heat recovery steam generator (equipped with duct burners) powering a steam turbine. There are two operating scenarios; combustion turbines (CTs) operating with duct burners and CTs operating without duct burners.

The department noted that on June 27, it separately issued a Tier I construction permit in which the applicant received authorization to make the following modifications to the facility:

  • Install the General Electric OpFlex modification, which involves both new process control software and replacement or modification to some components of the turbine gas path. This upgrade will increase the nominal heat input rating of each turbine from 1940 MMBTUH to 2010 MMBTUH, and also improve turbine efficiency, enabling the facility to recover generating capacity that has been lost since it commenced operation.
  • Install additional duct burners to increase duct firing capacity for each heat recovery seam generator (HRSG) from 265 MMBTUH to 325 MMBUTH. The facility has requested a new permit limit such that the additional duct firing capacity be utilized not more than 2,500 hours per year for each turbine, based on historical data on utilization of duct burners. 

The plant operates three combined-cycle gas turbines firing only natural gas. Maximum total combined rating of the entire facility is 800 MWe. Each gas turbine is paired with a steam turbine powered by steam produced in a HRSG using exhaust gas from the gas turbine. Exhaust gas from each turbine can be further heated by duct burners located in the HRSG, providing additional steam to the steam turbine. Low pressure exhaust steam is condensed; the waste heat is rejected through mechanical draft counter-flow cooling towers. An auxiliary boiler provides heat to facilitate start-up for all turbines by preheating the steam turbines. An emergency generator serves all three units as backup in the event of a power outage.

The gas turbines are GE Model PG7241FA, each with a nominal output of 199 MWe (increased from 194.4 MWe) at base conditions of 0°F, with a nominal higher heat value (HHV) input of 2010 MMBTUH (increased from 1940 MMBTUH).

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.