Patent ID: 8602724

Claim:
A gas turbine plant including a cooler in an air system used for cooling second-stage turbine stator blades, wherein a first-stage segmented ring and a second-stage segmented ring that oppose tips of first-stage turbine rotor blades and second-stage turbine rotor blades are supported by a same blade ring, and a cooling-air for the second-stage turbine stator blades forms a cooling air flow cooling the blade ring, to control thermal expansion of the blade ring and to control a clearance with respect to the tips, wherein switching means is provided in the flow path for supplying the cooling air for the second-stage stator blades to allow the cooling air to bypass the cooler during start-up and to allow the cooling air to pass through the cooler during the load operation, so that the flow path is switched between different flow paths during start-up and during load operation, and wherein the switching means is configured to switch the flow path to flow a high-temperature compressed air introduced from an outlet of a compressor as the cooling air during start-up operation, and switches the flow path to flow a high-pressure bleed air introduced from a high-pressure stage of the compressor as the cooling air to the flow path during load operation.