O sub(2)/CO sub(2) coal combustion characteristics in a 50 kW sub(th) circulating fluidized bed

Combustion experiments of two Chinese coals were conducted in a 50 kW sub(th) circulating fluidized bed (CFB) combustor in air and O sub(2)/CO sub(2) atmospheres, and the effects of atmosphere and O sub(2) staging on combustion characteristics including temperature distribution profiles, combustion efficiency, gaseous pollutant emission and desulfurization efficiency were investigated. Results show that O sub(2) enrichment in the atmosphere elevates the temperature level in the riser and improves the combustion efficiency. Without limestone addition, O sub(2) enrichment in the atmosphere augments SO sub(2) and NO emission and reduces CO emission. The desulfurization efficiency under higher O sub(2) concentration is higher with the same Ca/S molar ratio in O sub(2)/CO sub(2) atmosphere. O sub(2) staging provides more operation flexibility for oxy-fuel CFB combustion. As O sub(2) concentration in the primary gas increases, combustion efficiency and desulfurization efficiency are improved. O sub(2) staging can reduce the NO emission to a large extent in O sub(2)/CO sub(2) atmosphere.