Patent ID: 6514635
Filing Date: 2003-02-04
Classification: H01M,Y02E

Abstract:
A procedure for shutting down an operating fuel cell system, wherein, during operation of the fuel cell system, a continuous flow of oxidant is being provided to a fuel cell cathode from an oxidant source through a cathode flow field on one side of an electrolyte, and a continuous flow of hydrogen containing fuel is being provided to a fuel cell anode from a primary fuel source through an anode flow field on the other side of the electrolyte, and an electric current is being generated by the fuel cell within an external circuit and is operating a primary electricity using device in the external circuit, the procedure including the following steps:(A) disconnecting the primary electricity using device from the external circuit and stopping the flow of fuel from the primary fuel source into the anode flow field; and, then (B) catalytically reacting hydrogen in the anode flow field with oxygen by recirculating the anode exhaust through the anode flow field in a recycle loop into contact with a catalyst within the recycle loop to catalytically consume hydrogen, and continuing such recirculation and catalytic consumption of hydrogen until substantially all the hydrogen in the anode flow field has been removed.