Patent ID: 8158298

Claim:
A fuel cell system, comprising: a fuel cell for generating electrical power after causing an anode to receive a hydrogen-containing anode gas and causing a cathode to receive an oxygen-containing cathode gas; a discharge valve provided downstream of the fuel cell in an anode system flow path that supplies and discharges the anode gas to and from the fuel cell; a pressure raising device for raising gas pressure within the anode system flow path; and a control device programmed to operate the discharge valve and the pressure raising device so as to increase the gas pressure for at least part of a period when the discharge valve is open in exhaust gas treatment that involves detecting or estimating an impurity concentration within the anode system flow path and opening the discharge valve when the impurity concentration reaches a prescribed value for a prescribed period, wherein the control device is further programmed to operate the pressure raising device so as to increase a pressure upstream of the fuel cell anode to a first target pressure prior to opening the discharge valve, and to operate the pressure raising device so as to decrease the pressure upstream of the fuel cell anode to a second target pressure, which is lower than the first target pressure, a predetermined time after opening the discharge valve and prior to closing the discharge valve, wherein the increasing the pressure upstream of the fuel cell anode to the first target pressure increases a pressure differential between upstream and downstream of the fuel cell anode, and wherein the predetermined time is closer to the opening of the discharge valve than to the closing of the discharge valve.