Rockwood Generating Station is part of Imperial Irrigation District’s fossil fuel power generation system with 50 Megawatts (MW) of installed capacity. The Rockwood Gas Turbine plant consists of two Pratt & Whitney FT4C-3F Gas Turbine Unit 1 and Unit 2 generating units commissioned in 1978. Rockwood Generating Station Units 1 and Unit 2 are industrial aero derivative type turbines originally designed by United Technologies rated at 25,000 KW.
Turbine output and efficiency of the gas turbine engines are reduced during periods of high ambient temperature. All this has an effect on gas turbine output. As ambient temperatures rise, gas turbine output decreases. Each 10°F (-12.2°C) rise in temperature can result in as much as a 3-4% decrease in output and a 1% rise in heat rate (The heat rate is the amount of energy used by an electrical generator/power plant to generate one kilowatt-hour [kWh] of electricity). This creates an incentive to attempt to overcome the inherent loss of gas turbine power output during periods of high ambient temperature by using high-pressure inlet fogging.
Fog intercooling which has been applied from the early days of gas turbine and jet engine technology (injection of water into the axial flow compressor) is a technique that consists of over-injecting fog into the inlet air stream (i.e., spraying more fog than will evaporate under the given current ambient temperature and humidity conditions). The desired quantum of unevaporated fog is carried with the air stream into the compressor where it evaporates and gives an intercooling effect. The resulting reduction in the work of compression can result in a significant additional power boost. The compression process consumes as much as 66% of the total work produced by the gas turbine and therefore any means of reducing the work of compression will enhance the power output of the gas turbine.
MeeFog Systems, Inc. will install fog intercooling at the Rockwood unit 1 and unit 2.