Anode exhaust gas dilution method and apparatus in PEM fuel cell powered system

摘要

The present invention discloses a fuel cell system that reduces a hydrogen content of anode effluent exhausted by a fuel cell stack without the use of a tail gas combustor. The fuel cell system reduces the hydrogen content in one or more stages to a level suitable for venting to the environment. A first stage reduction is provided by mixing a portion of the cathode effluent with a controlled quantity of the anode effluent in the presence of a catalytic bed. The resulting stream has a reduced hydrogen content which can then be supplied to the cathode inlet side of the fuel cell stack for further hydrogen content reduction. The fuel cell system also provides a storage device to store the anode effluent to minimize pressure fluctuations between the anode and cathode sides of the fuel cell stack during a purging operation.