Method of operating a fuel cell system

Abstract

A method of operating a fuel cell system including stopping power generation of a fuel cell which generates electric power using a fuel gas and an oxidizing gas, filling and keeping a combustible gas in a cathode of the fuel cell after said step, supplying the oxidizing gas to the cathode, supplying the combustible gas discharged from the cathode in response to the previous step to a combustor capable of heating a fuel generator for generating the fuel gas or an exhaust pipe connected to the combustor via a branch passage branching from an oxidizing gas passage located downstream of the cathode, diluting the combustible gas supplied to the combustor or the exhaust pipe with air supplied to the combustor or exhaust gas supplied to the exhaust pipe such that the combustible gas has a concentration lower than a combustion lower limit, and discharging the diluted combustible gas to atmosphere.

Dependencies are inferred from the claim text.