Combustion of syngas and natural gas in a 300 W chemical-looping combustor

Tests with syngas and natural gas were performed in a continuously operated laboratory reactor system for chemical-looping combustion (CLC). Two different nickel-based oxygen-carriers were used. The CLC system was operated successfully and high conversion of both syngas and natural gas were obtained. One oxygen-carrier composed of NiO and MgAl2O4 was tested with syngas, and the conversion of the fuel was high, often exceeding 99%, with outlet hydrogen and carbon monoxide concentrations close to thermodynamic equilibrium. The highest fractions of hydrogen and carbon monoxide were 1.8% and 2% based on dry flue gas. Both oxygen-carriers were used in combustion tests with natural gas. For natural gas, high conversion of the fuel was found for both oxygen carriers, around 99%. The NiO/MgAl2O3 oxygen-carrier gave no methane out from the fuel reactor, and the fraction of carbon monoxide was in the range 0.5-3%. For the second NiO based oxygen-carrier, the fraction of methane varied between 0.5 and 1.5% while the fraction of CO was about 0.5% for all tests, i.e., close to thermodynamic equilibrium.