Pressurized fuel cell system

DETAILED DESCRIPTION We claim: 1.
A fuel cell power plant system comprising: (a) a fuel cell stack having anode means, cathode means and stack cooling means adapted to use a water coolant; (b) turbocompressor means operably connected to said cathode means for supplying compressed air to said cathode means; (c) first conduit means operably connected to an exhaust side of said cathode means and to said turbocompressor means, said first conduit means being operable to supply moist cathode exhaust gases to said turbocompressor means to drive the latter; (d) separator means; (e) second conduit means operably connected to an exhaust side of said cooling means and to said separator means, said second conduit means being operable to supply a water/steam coolant exhaust mixture from said cooling means to said separator means; (f) third conduit means operably connected to said separator means and to said turbocompressor means for ducting steam from said separator means to said turbocompressor means; and (g) control means including a sensor means and valve means cooperating to control the flow of steam from said separator means to said turbocompressor means, said sensor means being disposed on an output side of said turbocompressor means and being operable to sense a characteristic of the compressed air flowing from said turbocompressor means to said cathode means, and said valve means being disposed in said third conduit means and normally closed to block flow of steam from said separator means to said turbocompressor means, said control means further including actuating means operable to open said valve means to allow flow of steam from said separator means to said turbocompressor means at such times as said sensor means indicates, by virtue of said sensed compressed air characteristic, that said turbocompressor means requires additional energy, over and above that being supplied by the cathode exhaust gases, to operate at its designed level.
2.
The system of claim 1 wherein said sensor means is a pressure sensor