Thermal Stress Analysis of 600MW Steam Turbine Rotor in Different Governing Modes

At present, there are still some imported steam turbines which are originally designed to operate in throttling governing, which leads to the low efficiency when the steam turbine is working with part load. In order to enhance economical performance of steam turbine, it has to be transformed into nozzle governing. After changing throttling governing to nozzle governing for the steam turbine, the temperature variation of the front gland seal and stages of high pressure rotor are increased. The higher temperature makes them to be the most dangerous parts and affects the security and the velocity of load change. The computational object is intercepted from hp-ip rotor of the 600 MW steam turbine in this paper. The distribution of the temperature and thermal stress in the governing stage and the first stage of high pressure cylinder is calculated two-dimensionally. The changes of the temperature and stress in different governing modes are analyzed. The result of calculation provides a reliable basis for on-line monitoring of the rotor thermal stress, which ensures the security and economical operation of steam turbine units.