Patent ID: 7998632

Claim:
A solid oxide fuel cell stack assembly comprising: a) a solid oxide fuel cell stack having anodes and cathodes, said stack producing an anode tail gas; b) a reformer for converting hydrocarbon materials into reformate fuel for consumption by said fuel cell stack; c) a passage for recycling a portion of said anode tail gas into said reformer, said passage including a controllable pump disposed in said portion between said fuel cell stack and said reformer; d) a heat exchanger disposed in said portion upstream of said pump between said fuel cell stack and said reformer, wherein said anode tail gas portion is passed through a first side of said heat exchanger and air is passed through a second side to cool said anode tail gas portion entering said pump, wherein said heat exchanger is configured to control the temperature of said anode tail gas portion exiting said heat exchanger; and e) an air diverter valve disposed ahead of said heat exchanger and configured to maintain the temperature of said anode tail gas portion entering said pump above the dewpoint of said anode tail gas portion by varying the amount of air admitted to said heat exchanger.