Patent ID: 6338241
Filing Date: 2002-01-15
Classification: F01K,F02C,F05D,Y02E

Abstract:
A combined cycle power generation plant, which comprises a gas turbine plant including a high temperature section, a steam turbine plant including high, intermediate and low pressure turbines connected through a common shaft, and an exhaust heat recovery boiler including a reheater, and high, intermediate and low pressure superheaters, said combined cycle power generation plant further comprising:a low temperature reheat steam system for supplying a turbine exhaust steam from the high pressure turbine of the steam turbine plant to the reheater of the exhaust heat recovery boiler; a cooling steam supply system which branches from the low temperature reheat steam system and supplies the turbine exhaust steam to the high temperature section of the gas turbine plant as a cooling steam; an intermediate pressure superheater steam system which is connected to the cooling steam supply system and adapted to join a steam supplied from the intermediate pressure superheater of the exhaust heat recovery boiler together with the turbine exhaust steam; a reheat steam system connecting the reheater of the exhaust heat recovery boiler and the intermediate pressure turbine of the steam turbine plant; a cooling steam recovery system which recovers a steam after cooling the gas turbine high temperature section to the reheat steam system; a bypass system which branches a superheat steam pipe connecting an outlet of a first high pressure superheater of the exhaust heat recovery boiler and an inlet of a second high pressure superheater thereof, a main steam system which supplies a steam from the bypass system to the high pressure turbine of the steam turbine plant; and wherein the low temperature reheat steam system includes a low temperature reheat flow control valve for controlling a flow rate of a turbine exhaust steam supplied from the high pressure turbine to the reheater.