A fuel cell system and associated method allows for continuous operation of the
fuel cell system with fuel recirculation, without the necessity for periodic purging.
A portion of the anode exhaust is not recirculated but is continuously bled from
the anode exhaust line. Preferably, less than 5% by volume of the anode exhaust
is allowed to bleed continuously from the anode exhaust. The bleed line may be
connected to a catalytic reactor which combusts the unused fuel. The cathode exhaust
may be used as the oxidant for the catalytic reactor. The flow of exhaust to the
catalytic reactor may be controlled to ensure that the concentration of hydrogen
in the catalytic reactor is no higher than 50% of the lower limit of inflammability
for hydrogen.
