Influence of feeding position and post-combustion air arrangement on NOx emission from circulating fluidized bed combustion with post-combustion

Abstract

To explore the influences of different feeding position and post-combustion air (PCA) arrangement on combustion and original NOx emission characteristics of Shenmu semi-coke, the experiments were carried out on a new circulating fluidized bed (CFB) test platform, which was composed of a CFB and a post-combustion chamber (PCC). The experimental results showed that the feeding position of loop seal could effectively reduce original NOx emission and CO emission concentration in comparison to the conventional coal feeding position of furnace. The NOx emission concentration was 60.3 mg/m3 with single stage PCA. As the grading number of PCA increased, NOx emission can be gradually reduced, eventually falling to 49.6 mg/m3 with triple stages PCA. However, for CO emission, the double stages PCA were able to minimize CO emission. In addition to grading number of PCA, an appropriate injection position of PCA was also helpful for CO burnout. For double stages PCA, the two PCA nozzles should be arranged in the middle of the PCC. According to the above research results, the best feeding position and PCA distribution mode to achieve ultra-low original NOx emission (<50 mg/m3) were obtained.