Fuel reforming system

A fuel reforming system, comprising:

• a reformer which generates reformate gas containing hydrogen by a reforming reaction and a partial oxidation reaction using an oxygen-containing gas and raw fuel,
• a carbon monoxide oxidizer containing a carbon monoxide oxidation catalyst which removes carbon monoxide contained in the reformate gas by a shift reaction between carbon monoxide in the reformate gas and water, and a preferential oxidation reaction which oxidizes a remaining carbon monoxide not oxidized in the shift reaction using the oxygen-containing gas, and supplies the reformate gas from which the carbon monoxide has been removed to a fuel cell,
• a cooling device which cools a heat liberated by the shift reaction and preferential oxidation reaction in the carbon monoxide oxidizer by a coolant, and
• a controller functioning to:
• determine whether the carbon monoxide oxidizer is in a marginal operation state where a processing performance of the carbon monoxide oxidation catalyst has reached a limit, and
• perform an avoidance processing to avoid the marginal operation state of the carbon monoxide oxidation catalyst.