Patent ID: 7563528

Claim:
A fuel cell system comprising: a fuel cell having a cathode and an anode, the fuel cell generating power with an oxidant gas supplied to the cathode and a fuel gas supplied to the anode; an oxidant gas passage for supplying the oxidant gas to the cathode; a cathode off-gas passage for discharging a cathode off-gas of the cathode; a fuel gas passage for supplying the fuel gas to the anode, said fuel gas passage being free of a humidifier; a circulation passage for circulating an anode off-gas to the anode; an anode off-gas passage for discharging the anode off-gas; a fuel shutoff valve for shutting off supply of the fuel gas to the fuel gas passage; a supply device for supplying a scavenging gas, which is for scavenging the fuel cell, to the anode and the cathode; a humidifier disposed in the oxidant gas passage for humidifying the scavenging gas; and a control device programmed to control the supply device when the fuel cell is turned off by: switching the fuel shutoff valve to shut off the fuel gas supplied to the anode; supplying the scavenging gas from the supply device to the cathode, wherein the scavenging gas supplied to the cathode is conducted through the humidifier; and supplying the scavenging gas from the supply device to the anode, wherein the scavenging gas supplied to the anode bypasses the humidifier.