Kazuo Ikeuchi

DEVELOPMENT OF 40-INCH TURBINE BLADES USING TITANIUM ALLOYS

The Chubu Electric Power Co., Inc. and Hitachi, Ltd., jointly developed a 40-in long blade, capable of use at 3600rpm, to provide improved efficiency of the next-generation 700MW class steam turbines. The 40-in blade could improve the performance of steam turbines of the 700MW class about 1.6%. 12Cr-Ni-Mo-V steel, which is used in the previous longest 33.5-in blade and which cannot withstand the centrifugal force of a 40-in blade, was replaced with a titanium alloy of a small specific gravity to reduce the stress of the blade itself and the rotor to support it. Performance and reliability of the 40-in blade were evaluated by conducting demonstration runs using a full scale test turbine (2-stage) and a 1/2.5 scale model turbine (3-stage). The erosion resisting characteristics and the rupture strength of the blade root were determined by conducting basic tests.