Patent ID: 6272841
Filing Date: 2001-08-14
Classification: F01K,F05B,Y02E,Y02T

Abstract:
A combined cycle power plant having a gas turbine plant and a steam turbine plant combined together, the steam turbine plant comprising at least a high-pressure turbine and a low-pressure turbine, and the combined cycle power plant comprising:an exhaust heat recovery boiler for generating steam for driving the steam turbine by using exhaust heat from the gas turbine;a steam cooling system having parallel-arranged first, second, and third steam cooling sections for cooling a high-temperature portion in the gas turbine by using steam, where superheated steam from the steam cooling system is recovered and used in the steam turbine;an exhaust steam introducing system for introducing almost all of an exhaust steam from the high-pressure turbine into the steam cooling system; anda backap steam introducing system for introducing at least one of saturated high-pressure steam and saturated medium-pressure steam output from the exhaust heat recovery boiler into the steam cooling system when the exhaust steam from he high-pressure turbine is insufficient, the backup steam introducing system including;a first backup steam-cooling section for supplying saturated high-pressure steam which is output from the exhaust heat recovery boiler and whose temperature and pressure are reduced using a desuperheater; anda second backup steam-cooling section for supplying saturated medium-pressure steam output from the exhaust heat recovery boiler through a medium-pressure superheater.