Abstract: A procedure for starting up a fuel cell system that is disconnected from its primary load and that has air in both its cathode and anode flow fields includes a) connecting an auxiliary resistive load across the cell to reduce the cell voltage; b) initiating a recirculation of the anode flow field exhaust through a recycle loop and providing a limited flow of hydrogen fuel into that recirculating exhaust; c) catalytically reacting the added fuel with oxygen present in the recirculating gases until substantially no oxygen remains within the recycle loop; disconnecting the auxiliary load; and then d) providing normal operating flow rates of fuel and air into respective anode and cathode flow fields and connecting the primary load across the cell. The catalytic reaction may take place on the anode or within a catalytic burner disposed within the recycle loop.

Abstract: A fuel cell system includes a fuel cell stack having a first plurality of fuel cells each having an anode, a cathode and an electrolyte disposed therebetween, the first plurality of fuel cells being communicated with a source of hydrogen-containing fuel and oxidant so as to generate an electric current, an oxidant exhaust stream and a hydrogen-containing exhaust stream; the stack further having a second plurality of fuel cells each having an anode, a counter electrode and an electrolyte disposed therebetween, the second plurality of fuel cells being communicated with the electric current and the hydrogen-containing exhaust stream so as to produce a hydrogen rich stream, the first plurality of fuel cells being communicated with the second plurality of fuel cells to receive the hydrogen rich stream as at least a portion of the source of hydrogen-containing fuel.

Abstract: A fuel cell power plant system includes the ability to operate an enthalpy recovery device even under cold conditions. A bypass arrangement allows for selectively bypassing one or more portions of the enthalpy recovery device under selected conditions. In one example, the enthalpy recovery device is completely bypassed under selected temperature conditions to allow the device to freeze and then later to be used under more favorable temperature conditions. In another example, the enthalpy recovery device is selectively bypassed during a system startup operation. One example includes a heater associated with the enthalpy recovery device. Another example includes preheating oxidant supplied to one portion of the enthalpy recovery device.