John Sevier Combined Cycle Plant is located on 750 acres beside the Holston River near Rogersville, Tenn. The plant began commercial operation on April 30, 2012.
The 871-megawatt facility can use natural gas or no. 2 fuel oil for combustion. It consists of three trains, each with a GE gas turbine/generator and a Nooter/Eriksen heat recovery steam generator (HRSG). Each HRSG is equipped with natural gas-fired supplemental duct firing. The steam generated from the HRSGs provides steam to one Toshiba steam turbine/generator.
Plant design allows for simple cycle combustion turbine/generator operation with a summer capacity of 490 megawatts, or combined cycle operation with a capacity of 871 MW. The ability to run either in combined cycle or simple cycle mode provides voltage stability and reliability to the northeast region of the TVA system.
The simple cycle stage uses three combustion turbines similar to jet engines. Air entering each unit is compressed, mixed with natural gas and ignited. The hot flue gas then expands and flows through a gas turbine that turns a generator to produce electricity.
In combined cycle operation, heat from the gas turbine exhaust is routed through the HRSG to produce steam that generates additional electricity from a steam turbine generator.