FUEL CELL SYSTEM

PURPOSE:To obtain a fuel cell system whose life is long, efficiency is high, and load response is quick by removing carbon dioxide and unreacted fuel, carbon monoxide generated in reaction, and residual moisture, and supplying pure hydrogen to a hydrogen electrode in a fuel cell main body. CONSTITUTION:Fuel such as natural gas and methanol is mixed with water vapor, and reformed in hydrogen rich gas in a reformer 1 in a fuel reformer 3, and converted into carbon dioxide and hydrogen in a shift converter 2. The converted fuel is supplied to a purification unit 8 through a purification unit inlet pipeline 9 to remove carbon dioxide, carbon monoxide, unreacted fuel, and residual moisture. The pure hydrogen is supplied to a hydrogen electrode 4a of a fuel cell main body 4 through a purification unit outlet pipeline 10. The exhaust gas generated in the purification unit 8 contains combustible gas such as hydrogen is returned to a combustion part 1b of the reformer 1 through a purification unit exhaust gas pipeline 11, and used in a part of combustion energy required to a reforming reaction. Since cell efficiency is proportional to cell voltage and hydrogen partial pressure is proportional to cell voltage, cell efficiency is increased with increase in hydrogen partial pressure, or hydrogen purity.