Development of an Air Cooled G Class Gas Turbine (the M501GAC)

Abstract

Mitsubishi Heavy Industries (MHI) G series gas turbine is the industry pioneer in introducing steam cooling technology for gas turbines. The first M501G unit started commercial operation in 1997 and to date, with 62 G units sold, MHI G fleet is the largest steam cooled fleet in the market. The existing commercial fleet includes 35 commercial units with more than 734,000 accumulated actual operating hours, and over 9,400 starts. Upgraded versions have been introduced in the 60 and 50Hz markets (M501G1 and M701G2 respectively). On a different arena, MHI is engaged since 2004 in a Japanese National Project for the development of 1,700°C (3092°F) class gas turbine. Several enhanced technologies developed through this Japanese National Project, including lower thermal conductivity TBC, are being retrofitted to the existing F and G series gas turbines. Retrofitting some of these technologies to the existing M501G1 together with the application of an F class air cooled combustion system will result in an upgraded air-cooled G class engine with increased power output and enhanced efficiency, while maintaining the same 1500°C (2732°F) Turbine Inlet Temperature (TIT). By using an open air cooling scheme, this upgraded machine represents a better match for highly cyclic applications with G class efficiency, while the highly reliable and durable steam cooled counterpart is still offered for more base-loaded applications. After performing various R&D tests, the verification process of the air cooled 60 Hz G gas turbine has moved to component testing in the in-house verification engine. The final verification test prior to commercial operation is scheduled for 2009. This article describes the design features and verification plan of the upgraded M501G gas turbine.