Fuel cell system and water draining method of fuel cell system

A water draining method of a fuel cell system that includes:

• a fuel cell stack including a fuel electrode layer to which a fuel gas is supplied, an oxidizer electrode layer to which an oxygen-containing gas is supplied, and a cooling layer to which a cooling water is supplied;
• a fuel-gas flow path configured to allow the fuel gas from the fuel electrode layer of the fuel cell stack to pass therethrough;
• an oxygen-containing-gas flow path configured to allow the oxygen-containing gas from the oxidizer electrode layer of the fuel cell stack to pass therethrough;
• a cooling-water flow path configured to allow the cooling water from the cooling layer of the fuel cell stack to pass therethrough;
• a first bypass pipe configured to guide water in the fuel-gas flow path to the cooling-water flow path;
• a second bypass pipe configured to guide water in the oxygen-containing-gas flow path to the cooling-water flow path;
• a suction pump provided in the cooling-water flow path on a downstream side of a connecting portion between the cooling-water flow path and the first bypass pipe and a connecting portion between the cooling-water flow path and the second bypass pipe;
• and
• a shutoff valve provided on each of pipes forming the fuel-gas flow path, the oxygen-containing-gas flow path, the cooling-water flow path, the first bypass pipe, and the second bypass pipe and configured to open/close a flow path in each of the pipes, the method comprising:
• a first pressurizing step of controlling predetermined ones of the shutoff valves on the fuel-gas flow path and the first bypass pipe and pressurizing the fuel-gas flow path with the fuel gas;
• a first draining step of controlling predetermined ones of the shutoff valves on the fuel-gas flow path, the cooling-water flow path, and the first bypass pipe and pushing out water in the fuel-gas flow path at a pressure obtained by pressurization in the first pressurizing step;
• a first suction step of controlling predetermined ones of the shutoff valves on the fuel-gas flow path, the cooling-water flow path, and the first bypass pipe and sucking out water in the fuel-gas flow path via the first bypass pump by the suction pump;
• a second pressurizing step of controlling predetermined ones of the shutoff valves on the oxygen-containing-gas flow path and the cooling-water flow path and pressurizing the oxygen-containing-gas flow path and the cooling-water flow path with the oxygen-containing gas;
• a second draining step of controlling predetermined ones of the shutoff valves on the oxygen-containing-gas flow path, the cooling-water flow path, and the second bypass pipe and pushing out water in the oxygen-containing-gas flow path at a pressure obtained by pressurization in the second pressurizing step;
• and
• a second suction step of controlling predetermined ones of the shutoff valves on the fuel-gas flow path, the cooling-water flow path, and the second bypass pipe and sucking out water in the oxygen-containing-gas flow path and the cooling-water flow path via the second bypass pipe by the suction pump.

A water draining method of a fuel cell system that includes:

• a fuel cell stack including a fuel electrode layer to which a fuel gas is supplied and an oxidizer electrode layer to which an oxygen-containing gas is supplied;
• a fuel-gas flow path configured to allow the fuel gas from the fuel electrode layer of the fuel cell stack to pass therethrough;
• an oxygen-containing-gas flow path configured to allow the oxygen-containing gas from the oxidizer electrode layer of the fuel cell stack to pass therethrough;
• a bypass pipe configured to guide water in the fuel-gas flow path to the oxygen-containing-gas flow path;
• a suction pump provided in the oxygen-containing-gas flow path on a downstream side of a connecting portion between the oxygen-containing-gas flow path and the bypass pipe;
• and
• a shutoff valve provided on each of pipes forming the fuel-gas flow path, the oxygen-containing-gas flow path, and the bypass pipe and configured to open/close a flow path in each of the pipes, the method comprising:
• a first pressurizing step of controlling predetermined ones of the shutoff valves on the fuel-gas flow path and the bypass pipe and pressurizing the fuel-gas flow path with the fuel gas;
• a first suction step of controlling predetermined ones of the shutoff valves on the fuel-gas flow path, the oxygen-containing-gas flow path, and the bypass pipe and, along with pushing out water in the fuel-gas flow path at a pressure obtained by pressurization in the first pressurizing step, sucking out water in the fuel-gas flow path via the bypass pump by the suction pump;
• a second pressurizing step of controlling predetermined one of the shutoff valves on the oxygen-containing-gas flow path and pressurizing the oxygen-containing-gas flow path with the oxygen-containing gas;
• and
• a second suction step of controlling predetermined ones of the shutoff valves on the oxygen-containing-gas flow path and the bypass pipe and, along with pushing out water in the oxygen-containing-gas flow path at a pressure obtained by pressurization in the second pressurizing step, sucking out water in the oxygen-containing-gas flow path by the suction pump.