New Approach to the Combined Removal of NOx and SO2 for Circulating Fluidized Beds

Post-combustion technology is a new kind of low-nitrogen combustion technology. To achieve the combined removal of nitrogen oxides (NOx) and sulfur dioxide (SO2) emissions, the post-combustion technology combined with the sorbent injection in the furnace and post-combustion chamber is proposed. Experiments investigating the effects of the sorbent addition in a post-combustion chamber and post-combustion air arrangement on NOx and SO2 emissions were conducted in a 0.1 MWth circulating fluidized bed test platform. In addition, a comparative analysis of the NOx and SO2 emissions under both combined removal methods was also performed. The results indicated that adding sorbent to the post-combustion chamber can reduce SO2 emissions, but further increasing the amount of sorbent will not significantly improve the desulfurization effect. The injection position of the post-combustion air will affect the emissions of NOx and SO2 in the flue gas. When the three-stage distribution of post-combustion air is adopted, the further back the third nozzle is distributed, the lower the temperature in the post-combustion chamber, which is beneficial to the control of NOx and SO2 emissions. Compared with the conventional combined removal method, the NOx emissions were significantly reduced under the new combined removal method. Through secondary desulfurization in the furnace and post-combustion chamber, oxygen-deficient combustion in the furnace can achieve the combined removal of NOx and SO2.