Title : Design of a highly efficient natural gas fuel processor for residential PEM fuel cells
Abstract:
A scalable heat and system integrated coaxial cylinder type fuel processor is designed and fabricated. The unit process consists of desulfurizer, steam reforming with metallic structured catalyst, water gas shift(WGS), preferential oxidation and auxillary components(water pump, blower, heat exchanger and controller). The basic principle for scalability is explained to maintain the similarities in heat and mass flux. Since the strong endothermic steam reforming reaction of natural gas accompanies a very rapid surface reaction due to strong pore diffusion limitations with very low value of effectiveness factor decreasing from the reactor inlet below 0.1, as an alternative to conventional ceramic based pellet catalysts, a newly designed metallic structured catalyst with ruffled-fin type configuration using a FeCr alloy plate as a substrate to maximize geometric surface area per unit volume is applied. Subsequently, Ru, as an active reforming catalyst, is uniformly coated and highly dispersed onto the metallic substrate by deposition-precipitation method. The system reveals the fuel processing efficiency of ca. 80%(LHV) and the durability of up to 1,000 hrs with no decay in catalytic performance implying stable activity of the Ru on metallic structured surfaces is verified. The system volume including insulation is very compact with 12.5L/kW. In addition, Aspen+ commercial process simulation software is employed to optimize the heat exchange network of a fuel processor.
