Hydrogen generator, fuel cell system, and method for operating hydrogen generator

Abstract

The possibility of carbon deposition from a raw material gas is made lower than before in a pressure compensating operation carried out after stopping the stop process of a hydrogen generator and a fuel cell system including the hydrogen generator. The hydrogen generator includes: a raw material supply unit () configured to function to block supply of a raw material; a steam supply unit () configured to function to block supply of steam; a reformerincluding a reforming catalystand configured to generate a hydrogen-containing gas by using the raw material supplied from the raw material supply unit and the steam supplied from the steam supply unit; a closing unitconfigured to block at least a gas passage provided downstream of the reformer; and a controllerconfigured to execute a pressure compensating operation in which: during stop of the hydrogen generator, with hydrogen contained in the reformer, the supply of the raw material from the raw material supply unit and the supply of the steam from the steam supply unit are blocked, and the closing unit is closed; and to compensate a pressure decrease in the reformer due to a temperature decrease in the reformer after the closing of the closing unit, with the hydrogen contained in the reformer, the steam is supplied from the steam supply unit to the reformer.