Recent Development of Steam Turbines With High Steam Temperatures

Higher thermal efficiency of the power plant has been always essential and indispensable in order to decrease the impact on the environments. In this regard, enhancement of the steam conditions is the most fundamental and effective measure to achieve the goal of higher thermal efficiency. Recent steam conditions in Japan range from 593 to 610 degree C owing to the technological development. There are many aspects and areas of technology for the realization of such steam conditions, for instance, material development, cooling design, steam path development, casing design, and so on. Not only the research and development but also the accumulation of operational results is of importance to achieve a breakthrough in turbine design. Since the reliability is another dominant factor for steam turbines, reflection of manufacturing experience and operational results should be taken into consideration. In this paper, recent development of steam turbines with high temperatures will be presented focusing on their design features, material selections, operational results, etc. Furthermore, this paper deals with continuous efforts targeting even higher steam conditions, which are promising for future development of steam turbine technology.