FUEL CELL SYSTEM FOR REACTING HYDROCARBONS

A fuel cell system of the high temperature type includes one or more fuel cells operating with an electrolyte such as an oxygen ion conductive solid or a carbonate melt to which fresh reaction gases containing hydrocarbon fuel and oxygen respectively are fed after preheating in heat exchangers. The system may also include a separate reformer for converting the hydrocarbons into hydrogen and other gases. A portion of the exhaust gases from the fuel side of the cell is recycled through the fuel cell by entrainment with fresh fuel gas by means of the aspirating effect of a nozzle through which fresh fuel gas is injected into the cell and the remainder of the exhaust gas from the fuel side together with oxygen impoverished gas discharged from the cell are led to an after-combustion catalyst in the form of a tubular structure surrounding the fuel cells and also the reformer component if one is utilized for burning of the remaining hydrocarbon content of the fuel gas. The heat generated during the after-burning phase in the catalytic zone is mostly transferred over a very short path to the fuel cells to maintain the fuel cells at their proper operating temperature and to supply the power requirements of the reformer if the latter is utilized. The remaining heat in the exhaust gases is conducted to the exchangers for heat transfer to the incoming fresh reaction gases.