生物质再燃脱硝特性的试验研究

采用锅炉燃烧模拟装置试验研究了4种生物质的再燃脱硝性能，以及工况参数对脱硝效率的影响.借助热分析法研究了生物质燃烧特性.结果表明：明显影响脱硝性能的燃烧特性参数包括着火点、挥发分燃烧温度及其放热量.着火温度低、挥发分放热大的草本类生物质对应最佳再燃温度较低，脱硝性能较好.得到生物质再燃适宜的工况参数：再燃温度为950～1 050 ℃，再燃比为15%～25%，再燃过量空气系数为0.6～0.8，停留时间为1 s左右.在一定工况下，减小燃料粒径，增加停留时间、较高的初始氮氧化物浓度都会相应提高脱硝效率.再燃比15%的典型工况下，生物质再燃脱硝效率达到54%～67%.

Experimental study on characteristics of nitrogen oxides reduction by biomass reburning

The performances of four species of biomass reburning processes and the effect of operating parameters on NOx removal efficiency were studied using the boiler simulator facility. The combustion characteristics of the biomass were investigated by thermogravimetic analysis method. The results show that combustion characteristics parameters to affect the performance significantly include ignition temperature, volatiles combustion temperature and exothermic capacity. The herbaceous biomass shows better performances at the lower optimal injection temperature for its lower ignition temperature and bigger volatiles combustion exothermic capacity. The optimum operating parameters for biomass reburning include reburn zone temperature of 950~1 050 ℃, reburn heat input of 15%~25%, reburn zone stoichiometric ratio of 0.6~0.8 and residence time about 1 s. Reducing particle diameter of fuel, increasing residence time and keeping higher initial NOx concentration can enhance NOx removal efficiency respectively at the certain operating conditions. Under the typical operating conditions with reburn heat input of 15%, NOx removal efficiency of 54%~67% is achieved by biomass reburning.