Experimental Results for Oxy-fuel Combustion with High Oxygen Concentration in a 1MWth Pilot-scale Circulating Fluidized Bed

Combustion experiments with the fuel of Chinese bituminous were conducted in air and O2/recycle flue gas (RFG) atmospheres in a 1MWth pilot-scale oxy-fuel circulating fluidized bed (CFB). The effects of atmospheres on combustion characteristics including temperature profiles, combustion efficiency, and gaseous pollutant emission are investigated. The highest concentration of oxygen in the experiment is increased to 50% per volume. It is shown that CFB combustor under high oxygen concentration condition is very stable and the transition from air to the oxy-fuel firing mode is smooth, presenting little or no operational difficulty, CO2 concentrations in flue gas can reach near 80% on a dry basis. Compared with the air firing mode, the temperature level in the bed is similar, and combustion efficiency is improved under O2/RFG firing mode. Emission in mg/MJ unit such as NO and CO are lower while SO2 are much higher than that under the air firing mode.