SYSTEM OF COOLING STEAM TURBIN ROTATIVE SHAFT

摘要

PURPOSE:To reduce thermal stress in the rotative shaft and life consumption factor by controlling the temperature and rate of flow of cooled steam led to portions to be cooled at the time of the start according to the change of temperature of re- heated steam supplied to the turbine with time. CONSTITUTION:Cooled steam is led from a main steam system 21 and a high pressure exhaust system 22 through ducts 23 and 24 to a steam header 8. A steam header 8 is provided to mix steam streams from both the systems 21 and 22, and the temperature of the mixture steam is mesured by a thermo-couple 1. The temperature of a cooling chamber in a re-heated steam inlet section in a medium pressure turbine 7 is measured by a thermo-couple 10, and the measurement is coupled together with that of the output of the thermo-couple 1 to a calculating circuit 2. The calculating circuit 2 controls control valves 3 and 4. Further, the temperature of a re-heated steam system 25 is measured by a thermo-couple 11 to control a control valve 11 for controlling the rate of steam flowing from the steam header 8 through a calculating circuit 9 to a cooling chamber.