PREVENTIVE MEASURE AGAINST EXCESSIVE SPEED OF STEAM TURBINE

摘要

PURPOSE:To lessen wear of a thrust bearing by throttling a steam regulating valve before an intercept valve is quickly closed at a time when the load of a steam turbine is rapidly reduced. CONSTITUTION:An intercept valve 6 is quickly closed when both the number of revolution and acceleration of revolution exceed the specified values at a time when the load is rapidly reduced at a power generating plant where a thrust bearing 12 is arranged between a medium pressure turbine 7 and a low pressure turbine 9. On this occasion, a steam regulating valve 3 is allowed to be throttled before the intercept valve is quickly closed. This enables change in a thrust force accompanied with the quick closing of the intercept valve 6 to be restrained permitting wear of the thrust bearing to be lessened.