50-kWth methane/air chemical looping combustion tests with commercially prepared CuO-Fe2O3-alumina oxygen carrier with two different techniques

CuO-Fe2O3/alumina oxygen carriers were manufactured using two different techniques (i.e., spray drying and wet granulation). The spray drying method produced porous, spherical particles in the range of 100-200 mu m. The wet granulation, or tumbling method, produced particles in the range of 200-600 mu m. Both batches of material showed good gas conversion and particle durability during tests in NETL's 50-kWth chemical looping circulating fluidized bed combustor unit at 700-900 degrees C. No agglomeration was observed, even though the oxygen carrier had a high CuO concentration (30%). The particle losses with 200-600 mu m batch were significantly lower than that with the 100-200 mu m batch. The oxygen carrier materials in the 200-600 mu m range were circulated for approximately 3.1 days in the target temperature range (700-850 degrees C) and a total of approximately 40 h of chemical looping combustion testing was conducted during that time. The average fuel reactor temperatures ranged from 760 to 815 degrees C for the chemical looping combustion test periods, and the average air reactor temperature ranged from 840 to 915 degrees C. The fuel conversion from natural gas to CO2 ranged from 50 to 80%. Approximately 1.6 h of continuous operation was achieved with no gas preheat and no natural gas augmented heating. During this test period, the average fuel reactor temperature ranged from 780 to 825 degrees C, the air reactor temperature ranged from 930 to 960 degrees C, and the natural gas to CO2 conversion ranged from 50 to 65%. Analysis of the oxygen carrier after the test indicated that there were no significant changes in the particle size or the surface morphology.