PURPOSE: To provide a drain controller for a feed water preheater, capable of reliably controlling a flow rate of an HPDP and preventing the run-out of the HPDP even when such a case where one of LCVs is erroneously closed occurs to cause pressure in a condensate system to be vaired due to variation of a condensate flow rate.
CONSTITUTION: A flow rate detection signal released from a pump outlet flow rate meter 13 is inputted into a deviation operation unit 30, and a deviation between a pump outlet flow rate of an HPDP and an HPDP run-out value 31 is operated. On the basis of the deviation thus operated, a PID control operation unit 32 produces a valve opening degree command signal and sends it to a low value selector 24. On the other hand, a valve opening degree instruction signal produced by a PID control operation unit 23 on the basis of a deviation between a drain tank water level, which is detected by a drain tank water level detector 15 and calculated by a deviation operation unit 22, and an ordinary water level, preset value 21 for the drain tank is inputted into the low value selector 24. Of these valve opening degree command signals, the one having a lower value is selected, and the opening degree of an LCV 12 is thereby controlled.
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MATSUMOTO MASAAKI
SHIOZAWA HIROMITSU
TOSHIBA SYST TECH KK