TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred System: The fuel cell system processor further comprises a second reactor; a combustion heater outputting a heated exhaust stream (32); a start vaporizer (80); a spray vaporizer (72); and a run vaporizer (96). The first reactor is a shift reactor. The second reactor is disposed between the first reactor and the fuel cell stack. It further reduces carbon monoxide levels of the reformate exiting the first reactor. It is a preferential oxidation reactor. The combustion heater is a combustion burner that is operably coupled to the combustor. The start vaporizer is disposed downstream from the combustion burner. It is exposed to the heated exhaust stream for vaporizing an inlet fluid to produce a steam. The steam from the start vaporizer is directed to a heat exchanger element associated with the preferential oxidation reactor. The spray vaporizer selectively injects a cooling fluid into the heated exhaust stream to reduce the fluid temperature of the spray vaporizer.The run vaporizer is exposed to an exhaust flow of the heat exchanger region of the shift reactor for vaporizing an inlet fluid to produce a steam. The steam from the run vaporizer is directed to an inlet of the reformer. A flow through the combustion burner, the spray vaporizer, the start vaporizer, the shift reactor and the combustor is reversible to alternately position the combustion burner, the spray vaporizer and the start vaporizer upstream and downstream from the shift reactor.Preferred Controller: The controller comprises a cathode control valve system disposed between the fuel cell stack and the combustor. The cathode control valve system is operable to direct the cathode effluent to the combustor to control its temperature as a function of the H2 content of the anode effluent. It comprises a first control valve fluidly coupled between the fuel cell stack and the combustor, and a second control valve fluidly coupled between the fuel cell stack and an exhaust passage. The first control valve is selectively actuated between an opened position to enable flow of the cathode effluent to the combustor and a closed position to prevent flow of the cathode effluent to the combustor. The second control valve is selectively actuated between an opened position to enable exhausting of the cathode effluent and a closed position to provide a back pressure to facilitate flow of the cathode effluent through the first control valve.    TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: The method of rapidly starting the fuel processing system further comprises:(a) injecting water into the heated gas stream to control the temperature of the heated gas stream;(b) adjusting the heating device as a function of the temperature of the first or second reactor;(c) generating a second heated gas stream in a second heating device, and directing the second heated gas stream through the reformer to heat the first reactor at a third rate of heating;(d) heating the reformer with the steam stream; and(e) directing the reformate stream through a first side of a second heat exchanger, and directing the steam stream through a second side of the second heat exchanger.