Seal structure for a cooling steam passage in a gas turbine

摘要

Gas turbine steam passage seal structure between a blade ring and a stationary blade absorbs thermal deformation to prevent occurrence of minute gaps to thereby reduce leakage of steam as cooling medium. A blade ring steam passage hole, provided in the blade ring (10), has a stepped portion formed in a middle portion thereof. A stationary blade steam passage hole, provided in the stationary blade (50) so as to oppose the blade ring steam passage hole, has a stepped portion formed in an outer peripheral portion thereof. A cooling steam supply passage connection portion is constructed comprising a seal pipe (25) provided between the blade ring and stationary blade steam passage holes so as to communicate them with each other and a seal urging guide device (44, 47) provided at each of the stepped portions of the blade ring and stationary blade steam passage holes so as to effect a seal while fixedly supporting the seal pipe (25). Leakage of the steam is reduced, temperature lowering of combustion gas is prevented, drive force of a steam turbine is increased and the entire thermal efficiency of the combined cycle power plant can be enhanced.