Process for humidifying a gaseous fuel stream

Claim 1

In a process for operating a fuel cell powerplant, the powerplant comprising a fuel cell stack including anode gas compartments and cathode gas compartments, wherein a gas stream comprising a gaseous fuel for the stack requires humidification, the steps of: (a) passing the gas stream requiring humidification through a saturator; (b) directing the humidified gas stream from the saturator into and through the anode gas compartments of the stack; (c) directing at least a portion of the exhaust from the anode gas compartments through a condenser; (d) circulating a mass of liquid water, in a loop, alternately through the saturator of step (a) and the condenser of step (c) in direct contact with the gas streams passing therethrough, the liquid water cooling the gas stream within the condenser and causing condensation of a portion of the water vapor therein, which condensate is picked up by the circulating water stream along with sensible heat and the heat of condensation given up by the gas stream in the condenser, wherein as the heated liquid water stream from the condenser passes through the saturator, a portion of the liquid water evaporates into the gas stream within the saturator to provide all the water vapor necessary to humidify the gas stream to the level required, substantially all of the heat of vaporization in the saturator being provided by the heat of condensation transferred from the anode exhaust gas stream to the circulating liquid water stream in the condenser.