Fuel gas production system for fuel cells

The technique of the present invention enhances the separation efficiency and the production efficiency of hydrogen in a hydrogen production system for fuel cells, while reducing the size of the whole fuel gas production system. In the fuel gas production system of the present invention, a hydrocarbon compound is subjected to multi-step chemical processes including a reforming reaction, a shift reaction, and a CO oxidation to give a hydrogen-rich fuel gas. Gaseous hydrogen produced through the reforming reaction is separated by a hydrogen separation membrane having selective permeability to hydrogen. The residual gas after the separation of hydrogen has a low hydrogen partial pressure and undergoes the shift reaction at the accelerated rate. The hydrogen-rich processed gas obtained through the shift reaction and the CO oxidation joins with the separated hydrogen and is supplied to fuel cells. A purge gas for carrying out the hydrogen is introduced into a separation unit of hydrogen, in order to lower the hydrogen partial pressure and thereby enhance the separation efficiency of hydrogen. The residual gas after the separation of hydrogen undergoes combustion and is subsequently used as the purge gas