COMBINED CYCLE GENERATING PLANT

摘要

PROBLEM TO BE SOLVED: To effectively cool the high temperature section of a gas turbine and hence to use material with reduced heat-resistant performance for the high temperature section of the gas turbine to reduce cost by supplying the high pressure steam turbine exhaust cooled by gas turbine fuel to the high temperature section of the gas turbine as cooling steam. SOLUTION: When a gas turbine plant 10 is operated, high pressure exhaust supplied from a high pressure turbine 41 via a cooling steam supply passage 14 is cooled by fuel supplied to a combustor 13 by a fuel heater 16 and then part of the exhaust is supplied to the combustor 13 via a branch passage 15 to cool a cylinder end cooling section 13a and the remaining exhaust is supplied to a gas turbine 11 to cool a high temperature section 11a. The steam after cooling the high temperature section 11a is recovered by a second intermediate pressure reheater 28 via a recovery passage 37. The steam after cooling the cylinder end cooling section 13a is guided to the outlet side of the second intermediate pressure reheater 28 via a recovery passage 38 and is mixed with the other steam heated via the reheater 28 and is supplied to an intermediate pressure turbine 42 to do work.