To control a condensate flow rate so as to exercise restraind on the permissible variation of NPSH (the suction pressure of a pump in the downstream of a deaerating equipment) to be max.
Control change-over means (6, 11, 12, 13, 14, 15, 31 and 32) changing-over the control of a control means 7 are provided so that the control means 7 controls a control valve based on the condensate flow rate control deviation when a correspondence value based on a condensate flow rate control deviation becomes larger than the correspondence value based on a drum water level control deviation and, after that the control means 7 controls the control valve based on the water level control deviation when the correspondence value based on the drum water level control deviation becomes larger than the correspondence value based on the condensate flow rate control deviation and also controlled permissible variation of suction pressure becomes larger than a prescribed value ΔNPSH.
MITE YUUICHI
SHIMIZU YUJIRO
