Patent ID: 8512904

Claim:
A fuel cell system comprising: a stack formed of a plurality of cells in which electricity is generated using hydrogen; a fuel processing unit that processes a hydrocarbon from a fuel source to generate hydrogen to be supplied to the stack; a process burner that operates with hydrogen that is not consumed by the stack or with a hydrocarbon from the fuel source and that generates a process burner discharge gas; a plurality of cooling separators installed between the cells in the stack, wherein each cooling separator comprises a metal thin plate having a first flow path and a second flow path formed in a complementary pattern on first and second opposing surfaces, respectively, of the metal thin plate; a cooling water circulating unit including a main cooling water line that circulates cooling water to the second flow path of the cooling separators to reduce the temperature of the stack; a discharge gas temperature raising unit that raises the temperature of the stack by passing the process burner discharge gas through the first flow path on the first surface of the cooling separators; and a cooling water temperature raising unit that raises the temperature of the stack by heating cooling water of the cooling water circulating unit by heat exchange with the process burner discharge gas and passing the heated cooling water through the second flow path on the second surface of the cooling separators wherein each cell comprises an anode, a cathode, an electrolyte layer between the anode and the cathode, a hydrogen flow path plate on the anode for supplying hydrogen to the anode, and a oxygen flow path plate on the cathode for supplying oxygen to the cathode, and the cooling separator is placed between the first hydrogen flow path plate and the oxygen flow path plate.