2 research outputs found
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Transient PrOx carbon monoxide measurement, control, and optimization
Fuel processing systems for low temperature polymer electrolyte membrane (PEM) fuel cell systems require control of the carbon monoxide concentration to less than 100 ppm to 10 ppm in the anode feed. Conventional hydrocarbon fuel processors use a water-gas shift (WGS) reactor to react CO with water to form H2 and reduce the CO concentration. The CO conversion is limited by equilibrium at the outlet temperature of the WGS reactor. The WGS outlet CO concentration can range from over 1% to 2000 ppm depending on the system and its operating parameters. At these concentrations, CO poisons low temperature PEM fuel cells and the concentrations needs to be reduced further
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Transient control of carbon monoxide with staged PrOx reactors
Fuel Processor systems generate hydrogen for fuel cell systems from hydrocarbon fuels such as gasoline for automotive fuel cell systems and natural gas for stationary fuel cell systems. These fuel processor systems must remove any contaminants to levels that won't poison the fuel cell before the outlet hydrogen-rich gas stream can be used by the fuel cell to generate electricity. Carbon monoxide is a contaminant that must be removed to levels of < 100 ppm or < 10 ppm depending on the CO tolerance of the fuel cell. Typically, the last unit operation in a fuel processor is a preferential oxidation reactor or a selective oxidation reactor, which removes CO by oxidizing it to form C02. These are catalytic reactors where the catalyst and operating conditions are selected so that the oxidation rate of the carbon monoxide is higher than the oxidation rate of hydrogen, even though the hydrogen is present at much higher concentrations (> 30%) than carbon monoxide which is present at trace concentrations (< 1%)