A comparative experimental study on characteristics of ultra-low NOx emission and fly ash between Fugu bituminous and its semi-coke with post-combustion

Abstract

Abstract The ultra-low emission standard will be enforced on circulating fluidized bed (CFB) boilers in the near future in China. The coordinated control of NOx and CO emission was realized on a 0.5 MWth CFB test platform by new post-combustion technology with low NOx emission. When NOx reached ultra-low emission standard (≤50\xa0mg/m3, at 6% O2), CO emissions of Fugu bituminous and its semi-coke were only 101.1 and 91.8\xa0ppm, respectively. Moreover, the influence of coal variety on NOx emission and fly ash characteristics during the post-combustion was investigated. The experimental results indicated that the post-combustion technology had a better de-NOx effect on volatile-N. The speciation of residual nitrogen in fly ash was investigated by XPS, but it could not be linked to NOx emission by the present study. The post-combustion technology had various influences on the morphology of fly ash from different fuels. In addition, the fly ash of semi-coke had a more developed pore structure, which probably led to a more intense NOx reduction reaction in the post-combustion chamber.