Patent ID: 7998628

Claim:
A fuel cell system comprising: a fuel cell having an anode exhaust gas outlet for discharging anode exhaust gas, the fuel cell being configured to receive fuel gas; an anode exhaust gas discharge pipe which is connected to the anode exhaust gas outlet of the fuel cell and is configured to accumulate impurities contained in the anode exhaust gas of the fuel; a plurality of open/close mechanisms arranged in the anode exhaust gas discharge pipe, which can switch between open and closed; a control portion configured to (1) close a downstream-most open/close mechanism that is disposed farthest downstream, from among the plurality of open/close mechanisms, during normal operation of the fuel cell, and (2) close at least one open/close mechanism other than the downstream-most open/close mechanism, from among the plurality of open/close mechanisms, and open the downstream-most open/close mechanism, during a discharge operation of the fuel cell, so as to discharge the impurities that have accumulated in the anode exhaust gas discharge pipe together with the anode exhaust gas outside the fuel cell system; and a concentration detector which detects an impurity concentration in the anode exhaust gas discharge pipe upstream of the downstream-most open/close mechanism, wherein the control portion is configured to open the downstream-most open/close mechanism even if the fuel cell is operating normally when the impurity concentration detected by the concentration detector is higher than a first predetermined concentration.