Fuel cell system combustor

In a fuel cell system comprising (a) a stack of H2—O2 fuel cells discharging an H2-containing anode effluent and an O2-containing cathode effluent, (b) a fuel reformer for converting a hydrogen-containing fuel selected from the group consisting of alcohols and hydrocarbons to H2 for fueling said cells, (c) a heat exchanger operatively associated with said reformer for heating said reformer, and (d) a combustor fueled by said anode and cathode effluents providing hot exhaust gas to said heat exchanger for heating said fuel reformer during the reformation process, and wherein said combustor comprises a housing having a input chamber receiving and combining said anode and cathode effuents together into a burnable mixture, an exhaust outlet emitting hot combustor exhaust gas to said heat exchanger, and a catalyst bed intermediate said chamber and said exhaust outlet for burning said mixture to generate said combustor exhaust gas, the improvement comprising:

• a turbulator intermediate said input chamber and said catalyst bed and providing a multiplicity of tortuously-pathed channels therethrough for inducing turbulent mixing of said mixture before it contacts said catalyst bed, said turbulator comprising a first porous bed having a first porosity profile downstream of said input chamber, a second porous bed downstream of said first porous bed, said second porous bed having a second porosity profile that is coarser than said first porosity profile, and an open space separating said first and second porous beds each from the other for homogenizing the gas emanating from said porous bed before it enters said second porous bed.