| CPC H01M 8/04462 (2013.01) [H01M 8/04097 (2013.01); H01M 8/04201 (2013.01); H01M 8/0447 (2013.01); H01M 8/04761 (2013.01)] | 9 Claims |

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1. A method for operating a fuel cell system (1), the method comprising:
supplying a hydrogen-containing anode gas to a fuel cell (2) via an anode gas path (3),
recycling the hydrogen-containing anode gas exiting from the fuel cell (2) via a recirculation path (4), wherein a flush valve (5) arranged in the recirculation path (4) is opened and the recirculation path (4) is flushed for reduction of a proportion of nitrogen contained in the anode gas, and
providing the hydrogen-containing anode gas to a waste gas turbine (14) arranged in a cathode waste gas path (8) directly connectable to the recirculation path (4) via the flush valve (5) in a flush path (7) or indirectly connectable to the recirculation path (4) via the flush path (7),
wherein a hydrogen content of the hydrogen-containing anode gas is determined with the aid of a sensor (6) and is used as a control variable in controlling the flushing of the recirculation path (4).
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