Compact selective oxidizer assemblage for fuel cell power plant

A selective oxidizer assembly for reducing carbon monoxide in a stream of a fuel gas and oxygen mixture to a concentration which is less than about ten parts per million without significantly decreasing the hydrogen content of the fuel gas, so as to condition said fuel gas for use in a fuel cell power plant, said oxidizer assembly comprising:

• a) a fuel gas inlet line for directing a mixture of the fuel gas and oxygen into said assembly, said inlet line leading to a gas flow section in said assembly for receiving a stream of the fuel gas and oxygen mixture, said gas flow section being formed from first and second spaced-apart plates with a plurality of separate catalyst-coated gas passages sandwiched between said first and second plates;
• b) a coolant inlet line for directing a coolant into said assembly, said coolant inlet line leading to a coolant section in said assembly, said coolant section being adjacent to said gas flow section and said coolant section being formed from said first plate and a third plate which is spaced-apart from said first plate on a side thereof opposite said second plate, said coolant section further including a plurality of coolant passages sandwiched between said first and third plates, said first plate providing heat transfer from gas flowing through said gas passages to coolant flowing through said coolant passages, said coolant being maintained at an inlet temperature which is less than about 220.degree. F. and at an outlet temperature which is less than about 360.degree. F. whereby said fuel gas and oxygen mixture is cooled within the assembly from an inlet temperature of about 360.degree. F. to an outlet temperature of about 170.degree. F.