JPS6488008A - Steam turbine plant - Google Patents

Abstract

PURPOSE: To stably control a water level in a deaerator without generating a flooding by providing a pipe for flowing back from the deaerator to a condenser and setting a valve travel for controlling the water level based on signals outputted from a deaerator water level detector, a condensate flow-rate detector, a water-supply flow-rate detector, and a detector for the amount of condensate reflux. CONSTITUTION: A pipe 46 for reflux for allowing one portion of condensate to flow back from a deaerator 35 to a condenser 34 is provided, and the pipe 46 for reflux has an adjustment valve 47 of the amount of condensate reflux. A deaerator level signal 301 from a water- level detector 49 of the deaerator 35, a steam condensate flow-rate signal 302 from a condensate flow-rate detector 50, a water-supply flow-rate signal 303 from a water-supply flow-rate detector 51, and an amount-of-condensate-reflux signal 304 from an amount-of-condensate-flow- rate detector 52 are inputted to a control device 48, addition/subtraction and proportional integration operation are performed based on the signal, and a control signal 305 is outputted to a deaerator level adjustment valve 41. When an air extraction steam from a steam turbine 32 cannot be fully supplied to the deaerator 35, the adjustment valve 47 is opened and 4-element control including the amount-of-condensate-reflux signal 304 is performed, so that a high-temperature steam condensate in the deaerator 35 flows back to the steam condenser 34, thus making uniform a water temperature.