Method and device for operating a fuel cell system having a recirculation blower disposed in a fuel circuit of the fuel cell system

1. A method for operating a fuel cell system ( 1 ) having a fuel supply line for supplying fuel to the anode side of the fuel cell system ( 1 ), an anode exhaust recirculation circuit, a recirculation blower ( 11 ) disposed in the anode exhaust gas recirculation circuit of the fuel cell system ( 1 ), a drive turbine ( 12 ) connected to drive the recirculation blower ( 11 ), a motor driven air compressor ( 5 ), piping connecting the outlet of the air compressor ( 5 ) to the cathode side ( 4 ) of the fuel cell system, piping connecting the outlet of the compressor ( 5 ) to the drive turbine ( 12 ) bypassing the cathode side ( 4 ) of the fuel cell system, said method comprising:

impacting an air-driven drive turbine ( 12 ) with compressed air (vL) supplied directly from the motor driven compressor ( 5 ) to drive the air-driven drive turbine ( 12 ), and

using the air-driven drive turbine ( 12 ) to drive the recirculation blower to resupply the fuel (BS) exiting the fuel cell system ( 1 ) downstream of the anode side back into the fuel supply line upstream of the anode side.

2. A method for operating a fuel cell system ( 1 ) having a recirculation blower ( 11 ) disposed in a fuel circuit of the fuel cell system ( 1 ), said method comprising:

impacting an air-driven drive turbine ( 12 ) with compressed air (vL) supplied directly from a source of compressed air to drive the air-driven drive turbine ( 12 ), and

using the air-driven drive turbine ( 12 ) to drive the recirculation blower to resupply the fuel (BS) exiting the fuel cell system ( 1 ) on the anode side back into the fuel supply line,

wherein the drive turbine ( 12 ) is impacted with compressed air (vL) of an air supply unit ( 5 ) of the fuel cell system ( 1 ) bypassing the cathode side of the fuel cell .

3. A method for operating a fuel cell system ( 1 ) having a fuel supply line for supplying fuel to the anode side of the fuel cell system ( 1 ), an anode exhaust recirculation circuit, a recirculation blower ( 11 ) disposed in the anode exhaust gas recirculation circuit of the fuel cell system ( 1 ), a drive turbine ( 12 ) connected to drive the recirculation blower ( 11 ), a motor driven air compressor ( 5 ), piping connecting the outlet of the air compressor ( 5 ) to the cathode side ( 4 ) of the fuel cell system, piping connecting the outlet of the compressor ( 5 ) to the drive turbine ( 12 ) bypassing the cathode side ( 4 ) of the fuel cell system, said method comprising:

impacting an air-driven drive turbine ( 12 ) with compressed air (vL) supplied directly from the motor driven compressor ( 5 ) to drive the air-driven drive turbine ( 12 ), and using the air-driven drive turbine ( 12 ) to drive the recirculation blower to resupply the fuel (BS) exiting the fuel cell system ( 1 ) downstream of the anode side back into the fuel supply line upstream of the anode side

wherein a charge-air cooler ( 6 ) is connected between the air supply unit ( 5 ) and the cathode side ( 4 ) of the fuel cell system, and wherein the compressed air (vL) is taken out between the air supply unit ( 5 ) and a charge-air cooler ( 6 ).

4. The method according to claim 1 wherein the drive turbine ( 12 ) is additionally impacted with cathode exhaust gas (KG) of the fuel cell system ( 1 ) exiting on the cathode side.

5. The method according to claim 4 , wherein the cathode exhaust gas (KG) is cooled prior to the impacting of the drive turbine ( 12 ).

6. The method according to claim 1 , wherein the drive turbine ( 12 ) and the recirculation blower ( 11 ) are coupled by means of magnetic coupling.