Abstract: A combined cycle power plant having a steam turbine, a gas turbine, a heat recovery steam generator, a deaerator and a condenser includes a heat exchanger for controllably exchanging heat between relatively cool condensate from the condenser and relatively warm feedwater from the deaerator in order to recover additional heat from the heat recovery steam generator and, thereby, improve overall efficiency of the combined cycle power plant.

Abstract: The efficiency of a combined cycle power plant is improved by preheating fuel supplied to a combustion turbine. The flow rate of feed water through an economizer section of a heat recovery steam generator is increased, and the excess flow, over that required to sustain saturated steam production in an evaporator section, is flowed through a heat exchanger to preheat the fuel.

Abstract: A deaerating subsystem in a combined cycle power plant includes a deaerator and a storage tank coupled to the deaerator, the deaerating subsystem being adapted for isolation of the deaerator when it is defective even while the overall combined cycle power plant is operating. Blind flanges are provided in a downcomer and in vapor risers between the deaerator and the storage tank for such isolation. Also provided is a condensate bypass for preventing the reception of the condensate by the deaerator, and for enabling the storage tank to receive the condensate directly. Thermal energy is input into the storage tank such that controlled amounts of heated condensate from the steam generator, and controlled amounts of dry steam can be input to the storage tank while the deaerator is isolated for repairs.