Oxy-fuel circulating fluidized bed combustion in a small pilot-scale test rig

Coal combustion under the elevated partial pressure of oxygen in a circulating fluidized bed environment was investigated. The fuel used was bituminous coal. The concentration of oxygen in the air was increased to 35% per volume. Excess oxygen ranged from 1.1 to 1.3 and the temperature ranged from ca. 1073 K to 1273 K. A 0.1 MWth CFB combustor was adapted for oxy-combustion. The conversion ratios respectively studied were: carbon, sulfur and nitrogen to CO, SO2 and NOX. An increase of nitrogen and sulfur conversion ratios and a strong decrease of incomplete combustion losses were found under the oxygen-enriched conditions. Moreover, a strong increase in temperature was noticed during oxy-combustion.