Patent ID: 9564646
Date: 2017-02-07
CPC Classifications: H01M,Y02E

Claim:
1. A method of operating a fuel cell system including a fuel cell that generates electric power using fuel gas and oxygen-containing gas and combusts fuel gas remaining unused for generation of electric power, a fuel gas supply line that supplies the fuel gas to the fuel cell, and an on-off valve that is disposed in the fuel gas supply line, the method comprising: when the on-off valve of the fuel gas supply line is closed and the fuel cell undergoes emergency shutdown, a first step of continuously supplying for a predetermined time the fuel gas in the fuel gas supply line downstream from the on-off valve to the fuel cell at a flow rate smaller than that at a time of generation of electric power; a second step of intermittently supplying the fuel gas at the smaller flow rate after the first step, wherein intermittently supplying the fuel gas includes alternating between a time period in which the fuel gas is supplied and a time period in which the fuel gas is not supplied, for more than one cycle, wherein the fuel gas is ignited using an ignitor during the time period in which the fuel gas is supplied; and a third step of stopping the supply of the fuel gas to the fuel cell after the second step.