Method of shutting down fuel cell system

A method of shutting down a fuel cell system including a fuel cell for generating electricity from an electrochemical reaction between an oxygen-containing gas supplied to a cathode and a fuel gas 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 method comprising:

• a first step of supplying the oxygen-containing gas and the fuel gas to the fuel cell to cause the fuel cell to generate electricity;
• and
• a second step of stopping supply of the fuel gas while supplying the oxygen-containing gas to the fuel cell to cause the fuel cell to generate electricity upon detection of a command to shut down the fuel cell,
• wherein, in the second step, when the pressure of the fuel gas at the anode is lowered to a preset lower-limit value based on an anode pressure, which actually is measured, the fuel cell is caused to stop generating electricity, and wherein, in the second step, the anode pressure is measured, a water vapor partial pressure is calculated, and the pressure of the fuel gas is calculated by subtracting the water vapor partial pressure from the anode pressure.

A method of shutting down a fuel cell system including a fuel cell for generating electricity from an electrochemical reaction between an oxygen-containing gas supplied to a cathode and a fuel gas supplied to an anode, an oxygen-containing gas supply device for supplying the oxygen-containing gas to the fuel cell, a fuel gas supply device for supplying the fuel gas to the fuel cell, and an electric storage device connectable to the fuel cell, the method comprising:

• a step of supplying the oxygen-containing gas and the fuel gas to the fuel cell to cause the fuel cell to generate electricity;
• a step of stopping supply of the fuel gas and supplying the oxygen-containing gas to the fuel cell at a low oxygen stoichiometry, which is lower than the oxygen stoichiometry in a normal electric generation mode of the fuel cell, to cause the fuel cell to generate electricity upon detection of a command to shut down the fuel cell;
• and
• a step of supplying the electricity generated by the fuel cell to the electric storage device
• wherein when a voltage of the electricity generated by the fuel cell drops to a preset voltage or lower, supply of the electricity generated by the fuel cell to the electric storage device is stopped, and the electricity is supplied only to a pump of the oxygen-containing gas supply device.

A method of shutting down a fuel cell system including a fuel cell for generating electricity from an electrochemical reaction between an oxygen-containing gas supplied to a cathode and a fuel gas supplied to an anode, an oxygen-containing gas supply device for supplying the oxygen-containing gas to the fuel cell, a fuel gas supply device for supplying the fuel gas to the fuel cell, and an electric storage device connectable to the fuel cell, the method comprising:

• a step of supplying the oxygen-containing gas and the fuel gas to the fuel cell to cause the fuel cell to generate electricity;
• a step of stopping supply of the fuel gas and supplying the oxygen-containing gas to the fuel cell at a low oxygen stoichiometry, which is lower than the oxygen stoichiometry in a normal electric generation mode of the fuel cell, to cause the fuel cell to generate electricity upon detection of a command to shut down the fuel cell, wherein the low oxygen stoichiometry is set to a value that becomes higher as the ambient air temperature is lower;
• and
• a step of supplying the electricity generated by the fuel cell to the electric storage device.

A method of shutting down a fuel cell system including a fuel cell for generating electricity from an electrochemical reaction between an oxygen-containing gas supplied to a cathode and a fuel gas supplied to an anode, an oxygen-containing gas supply device for supplying the oxygen-containing gas to the fuel cell, a fuel gas supply device for supplying the fuel gas to the fuel cell, and an electric storage device connectable to the fuel cell, the method comprising:

• a step of supplying the oxygen-containing gas and the fuel gas to the fuel cell to cause the fuel cell to generate electricity;
• a step of stopping supply of the fuel gas and supplying the oxygen-containing gas to the fuel cell at a low oxygen stoichiometry, which is lower than the oxygen stoichiometry in a normal electric generation mode of the fuel cell, to cause the fuel cell to generate electricity upon detection of a command to shut down the fuel cell;
• and
• a step of supplying the electricity generated by the fuel cell to the electric storage device;
• wherein the oxygen-containing gas supply device includes a discharge passageway for discharging the oxygen-containing gas, which has been used, from the fuel cell, the discharge passageway being connected to a normally closed back pressure control valve for regulating the pressure of the oxygen-containing gas, and wherein after a shutdown process is finished, the normally closed back pressure control valve closes the discharge passageway.

A method of shutting down a fuel cell system including a fuel cell for generating electricity from an electrochemical reaction between an oxygen-containing gas supplied to a cathode and a fuel gas supplied to an anode, an oxygen-containing gas supply device for supplying the oxygen-containing gas to the fuel cell, a fuel gas supply device for supplying the fuel gas to the fuel cell, a coolant supply device for supplying a coolant to the fuel cell, and an electric storage device connectable to the fuel cell, the method comprising:

• a first step of supplying the oxygen-containing gas and the fuel gas to the fuel cell to cause the fuel cell to generate electricity;
• and
• a second step of stopping supply of the fuel gas and supplying the oxygen-containing gas to the fuel cell at a low oxygen stoichiometry, which is lower than the oxygen stoichiometry in a normal electric generation mode of the fuel cell, to thereby cause the fuel cell to generate electricity, and supplying the electricity generated by the fuel cell to the electric storage device upon detection of a command to shut down the fuel cell;
• and
• a third step of stopping supply of the oxygen-containing gas at the low oxygen stoichiometry to the fuel cell, thereafter causing the fuel cell to generate electricity only with gases that remain in the fuel cell, and supplying the electricity generated by the fuel cell to the coolant supply device;
• wherein a voltage of the electricity generated by the fuel cell is lowered by a downverter, and thereafter the voltage is supplied to the coolant supply device.