Patent ID: 8051654

Claim:
A combined cycle power plant comprising: a compressor; a first turbine mechanically coupled to the compressor; a second turbine mechanically to the compressor, the second turbine outputting exhaust gases; a first combustor fluidly connected to the first turbine; a second combustor fluidly connected to the second turbine; a heat recovery steam generator fluidly connected to the second turbine; a heat exchanger fluidly connected to the compressor, the first combustor, the second combustor and the heat recovery generator; and a controller selectively operating the combined cycle power plant in a first mode based on a first power output of the combined cycle power plant wherein, compressor air is passed through the heat exchanger before being delivered to the first and second combustors and exhaust gas from the second turbine is passed to the heat exchanger, the exhaust gas from the second turbine pre-heating the compressor air passing through the heat exchanger to the first and second combustors, and in a second mode based on a second power output that is greater than the first power output of the combined cycle power plant, wherein air from the compressor is delivered directly to each of the first and second combustors and exhaust gas from the second turbine is delivered to the heat recovery steam generator, transitioning between the first and second modes is based on power output from the combined cycle power plant.