Abstract
Mitsubishi Heavy Industries (MHI) developed the 1,500deg. C class M501G and M501H heavy duty gas turbines. The M501G uses closed-loop steam cooling for the combustor, and the M501H uses closed steam-cooled for the combustor and the turbine row 1/2 blade & vane. The M501G unit went into commercial operation in 1997 at MHI in-house power plant at Takasago, Japan. The facility serves as an important test-bed for verifying long-term reliability and performance aspects of the M501G technology. With this experience, MHI developed the M501H gas turbine and successfully finished the load test including closed loop steam cooling in the combined system in March 2001. This paper presents technical features and operational experience of the M501G and M501H gas turbines.