Fuel cell system and method for stopping power generation in fuel cell system

A method for stopping power generation in a fuel cell system, wherein the fuel cell system comprises:

• a fuel cell that generates electric power through an electrochemical reaction between an oxygen-containing gas, which is supplied to a cathode, and a fuel gas, which is supplied to an anode;
• an oxygen-containing gas supply device for supplying the oxygen-containing gas to the fuel cell;
• and
• a fuel gas supply device for supplying the fuel gas to the fuel cell,
• the oxygen-containing gas supply device comprising:
• an oxygen-containing gas supply flow passage that communicates with an oxygen-containing gas inlet of the fuel cell;
• an oxygen-containing gas discharge flow passage that communicates with an oxygen-containing gas outlet of the fuel cell;
• a compressor disposed in the oxygen-containing gas supply flow passage;
• a supply flow passage sealing valve disposed in the oxygen-containing gas supply flow passage at a location downstream from the compressor;
• a discharge flow passage sealing valve disposed in the oxygen-containing gas discharge flow passage;
• and
• a discharge fluid circulation flow passage that communicates with the oxygen-containing gas discharge flow passage at a location upstream from the discharge flow passage sealing valve, while also communicating with the oxygen-containing gas supply flow passage at a location upstream from the compressor,
• the method for stopping power generation comprising the step of, when power generation of the fuel cell is stopped, raising the pressure on a side of the cathode above ordinary pressure by narrowing a degree of opening of the discharge flow passage sealing valve to thereby consume all of an oxygen component.