MINIMUM FLOW CONTROL DEVICE FOR FEED WATER PUMP

摘要

PURPOSE:To perform a safe operation without damaging a well-balancedness and a controllability of a turbine driven feedwater pump by a method wherein even if a fast M/T changing-over time occurs, a minimum flow valve is released to open until the number of revolution of a feedwater pump driven turbine reaches more than a predetermined value. CONSTITUTION:A feedwater pump driven turbine 10a is provided with a sensor 20 for sensing the number of revolution. A signal for the number of revolution of a feedwater pump driven turbine 10a detected is also inputted to a minimum flow valve control device 17. Then, as the minimum flow valve for a turbine driven feedwater pump is opened, a flow rate of condensate flowing in the turbine driven water supply ing pump is increased, and a suction pressure of the turbine driven feedwater pump is decreased. In this way, even if a suction flow rate of the turbine driven feedwater pump is more than an allowable value after changing-over of M/T, the minimum flow valve for the turbine driven feedwater pump is continued to open until the number of revolution of the feedwater pump driven turbine has a sufficient number of revolu tion in respect to a dangerous number of revolution and then the operation of the feedwater pump driven turbine is not carried out in a range near the dangerous number of revolution.