Patent ID: 7419518

Claim:
A hydrogen generator comprising: a hydrogen generating portion having a reformer configured to generate a hydrogen-rich reformed gas by causing a material containing an organic compound comprised of at least carbon and hydrogen to react with steam with the use of a catalyst: a heater configured to heat at least said reformer; a material supply portion configured to supply the material to said hydrogen generating portion; a water supply portion configured to supply water that is evaporated into the steam to said hydrogen generating portion; and a controller configured to control at least said heater, said material supply portion, and said water supply portion; said controller being configured to stop heating in said heater at a start of a stop operation, and to perform an internal gas replacement operation to replace the hydrogen-rich gas within said hydrogen generator with a replacement gas in the stop operation by flowing the replacement gas through said hydrogen generator, wherein: in the internal gas replacement operation, the material supplied from said material supply portion, the steam generated from the water supplied from said water supply portion, air supplied from outside of said hydrogen generator, an inert gas supplied from outside of said hydrogen generator, or a gas mixture containing two or more of the material, the steam, the air, and the inert gas is used as said replacement gas; a composition of the replacement gas used according to a temperature condition of said hydrogen generator in the stop operation including at least the temperature of said reformer is pre-set in said controller; and said controller is configured to, in the stop operation, determine the temperature condition of said hydrogen generator, and to, in the stop operation, control said heater, said material supply portion, and said water supply portion so as to perform the operation to replace the hydrogen-rich gas using the replacement gas selected based on the determination and the pre-setting.