Mitsubishi completed design development and verification load testing of a steam-cooled M501H gas turbine at a combined cycle power plant at Takasago, Japan in 2001. Several advanced technologies were specifically developed in addition to the steam-cooled components consisting of the combustor, turbine blades, vanes, and the rotor. Some of the other key technologies consisted of an advanced compressor with a pressure ratio of 25:1, active clearance control, and advanced seal technology. Prior to the M501H, Mitsubishi introduced cooling-steam in “G series” gas turbines in 1997 to cool combustor liners. Recently, some of the advanced design technologies from the M501H gas turbine were applied to the G series gas turbine resulting in significant improvement in output and thermal efficiency. A noteworthy aspect of the technology transfer is that the upgraded G series M701G2 gas turbine has an almost equivalent output and thermal efficiency as H class gas turbines while continuing to rely on conventional air cooling of turbine blades and vanes, and time-proven materials from industrial gas turbine experience. In this paper we describe the key design features of the M701G2 gas turbine that make this possible such as the advanced 21:1 compressor with 14 stages, an advanced premix DLN combustor, etc., as well as shop load test results that were completed in 2002 at Mitsubishi’s in-house facility.

Aoki, S., “Trend and Key Technologies for Gas Turbine Combined Cycle Power Generation in a Globally Competitive Market and Environmental Regulations,” IJPGC2000-15084, 2000.
Koeneke, C., Kallianpur, V., Arimura, H. et al., “Maintaining Long Term Steam Cooling Reliability in Mitsubishi Advanced Industrial Gas Turbines: Approach, Technology & Field Experience,” PowerGen 2002.
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