NOVELTY - A reforming fuel cell system comprises: (i) a reformer to produce a hydrogen-containing reformate with carbon monoxide; (ii) a first reactor to reduce the level of carbon monoxide of the reformate; (iii) a fuel cell stack to generate electrical energy from the reformate; (iv) a combustor with a catalyst bed; (v) a heat exchanger; and (vi) a controller for metering air flow to the combustor.    USE - For the production of hydrogen.    ADVANTAGE - The system is capable of heating the fuel processor components quickly to achieve proper operating temperatures for startup. It maximizes this heat input into the fuel processor while minimizing the tendency to form carbon. It is capable of heating the fuel processor components while minimizing the use of electrical energy during startup and the reliance on catalytic reactions. It enables the potential usage of inexpensive copper-zinc (CuZn) catalyst only without the need for an additional coolant loop. The tight control of temperatures within the fuel processor enables the optimization of reactor size and catalyst usage resulting in reduced active metal costs. The system provides improved transient carbon monoxide concentration performance.    DETAILED DESCRIPTION - A reforming fuel cell system comprises:    (i) a reformer (14) converting a hydrogen (H2)-containing fuel to produce an H2-containing reformate having a level of carbon monoxide;    (ii) a first reactor to reduce the level of carbon monoxide of the reformate;    (iii) a fuel cell stack (22) generating electrical energy from the reformate and discharging an H2-containing anode effluent and an oxygen-containing cathode effluent;    (iv) a combustor (26) having a catalyst bed for burning the anode effluent to generate an exhaust gas;    (v) a heat exchanger (16) thermally coupled to the first reactor to control its temperature, and having an input fluidly coupled to the combustor to receive the exhaust gas; and    (vi) a controller operable for metering air flow to the combustor to control its combustion temperature.    INDEPENDENT CLAIMS are included for:    (a) a method of controlling the reforming fuel cell system, comprising generating the H2-containing reformate in a the reformer; passing the reformate through the first reactor to reduce the level of carbon monoxide; reacting the reformate with oxygen in the fuel cell stack to create electrical energy and an anode effluent; inputting the anode effluent into a combustor to generate an exhaust stream; adjustably inputting an oxidant into the combustor to control the temperature of the exhaust stream; and transferring heat from the exhaust stream to the first reactor such that the temperature of the first reactor is maintained within an operating range; and    (b) a method of rapidly starting a fuel processing system having the reformer breaking down a hydrocarbon fuel into an H2-containing reformate stream and first and second reactors disposed downstream of the reformer for reducing the level of carbon monoxide in the reformate stream, comprising generating a heated gas stream in a heating device; directing the heated gas stream through a first side of a heat exchanger; directing water through a second side of the heat exchanger to produce a steam stream; heating the first reactor with the heated gas stream at a first rate of heating; heating the second reactor with the steam stream at a second rate of heating; and controlling the heating device to adjust the heated gas stream, thus controlling the first and second rates of heating.    DESCRIPTION OF DRAWING(S) - The figure is a schematic view illustrating a fuel processor.    Reformer (14)    Heat exchanger (16)    Fuel cell stack (22)    Combustor (26)    Heated exhaust stream (32)    Spray vaporizer (72)    Start vaporizer (80)    Run vaporizer (96)