Fuel cell system

A fuel cell system comprising:

• a fuel cell stack formed by stacking a plurality of fuel cells, said fuel cells each being formed by stacking an electrolyte electrode assembly and a separator, said electrolyte electrode assembly including an anode, a cathode, and an electrolyte interposed between said anode and said cathode;
• a heat exchanger for heating an oxygen-containing gas using a heat medium before the oxygen-containing gas is supplied to said fuel cell stack;
• a reformer for reforming a raw fuel chiefly containing hydrocarbon to produce a fuel gas to be supplied to said fuel cell stack;
• a combustor for burning a raw fuel and an exhaust gas discharged from said fuel cell stack after consumption in power generation reaction to produce a combustion gas as the heat medium;
• a heat retention chamber provided to cover opposite ends of said fuel cell in the stacking direction for accommodating the exhaust gas as a heat source for maintaining a temperature of said fuel cell stack, before the exhaust gas is supplied to said combustor, and
• a casing at least containing said fuel cell stack, said heat exchanger, and said reformer, wherein:
• said casing includes a fluid unit at least including said heat exchanger and said reformer at one end of said fuel cell stack in the stacking direction, and said heat retention chamber is formed in said casing;
• and
• said heat retention chamber and said combustor are connected through an exhaust gas path.