Program development for performance analysis of a steam turbine system with the use of overload valve

摘要

The global energy market has grown steadily as various energy technologies have been developed. Renewable energy has been used widely but conventional power plants are still used as major electric power sources, including steam turbines and gas turbines. Recently, flexible power plant operation in terms of load management has become important in the power generation industry. For flexible operation, overload valve operation has been introduced for ultra-supercritical steam turbine plants. Overload valve operation is an operation wherein some of the steam at the control valve is bypassed into the middle of the high pressure turbine. In this study, an in-house program is developed for the analysis of ultra-supercritical steam turbines using overload valve operation. A full off-design analysis is performed based on theoretical and empirical correlations. Four kinds of operations were comparatively investigated; control valve operation, sliding pressure operation, and two types of overload valve operation. The influence of the overload valve is analyzed in terms of operating characteristics and performance.