Patent ID: 6964820

Claim:
A water recirculation device for a fuel cell power plant, the power plant being provided with a fuel cell stack and a heat exchanger, comprising: a water tank; a recirculation passage connecting the fuel cell stack, the heat exchanger and the water tank, the recirculation passage comprising a water inlet and a water outlet respectively connected to the fuel cell stack in order to recirculate water in the fuel cell stack; a water pump recirculating water in the recirculation passage; a heater which heats water in the water tank; a water temperature sensor detecting a water temperature of the recirculation passage; a differential pressure sensor which detects a differential pressure of water between the water inlet and the water outlet; and a programmable controller programmed to: recirculate water in the recirculation passage by operating the water pump when the water temperature is less than a first predetermined temperature; and activate the heater when the water temperature is less than a second predetermined temperature which is lower than the first predetermined temperature and the differential pressure is larger than a predetermined value.