| 摘要 |
PROBLEM TO BE SOLVED: To prevent the temperature of mixed steam of steam, after cooling a gas turbine and reheat steam from an exhaust heat recovery boiler from being drastically lowered beyond the suitable temperature of steam to be supplied to an IH steam turbine inlet, when a required amount of the steam flow for cooling the gas turbine is increased. SOLUTION: In the combined cycle device, having a multi-pressure type exhaust heat recovery boiler 30, a gas turbine 14 and a steam turbine 18, steam for cooling gas turbine parts, is supplied from a medium pressure part of the exhaust heat recovery boiler, and a part of steam discharged from an HP part of the steam turbine is replenished and supplied to it. Steam from a gas turbine cooling cycle and exhaust steam from the HP part of the steam turbine are joined and allowed to flow through a reheating part 50 of an HRSG. Reheat steam is supplied to an IP part inlet 22 of the steam turbine. When t e temperature of the gas turbine cooling steam is lower than that of the suitable temperature, cooling steam discharged from the gas turbine and exhaust steam from a high-pressure part of the steam turbine are allowed to flow in line to a reheating device of the HRSG, steam having the suitable temperature is supplied to the IP part of the steam turbine, and therefore net performance is improved.
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