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针对一台采用旋流式燃烧器的煤粉炉NOx排放质量浓度较高的问题,采用空气分级燃烧方式以降低NOx排放量,基于CFD软件平台,在额定负荷下,分别对3种不同燃尽风喷口位置的改造方案进行了炉内燃烧及污染物生成的数值模拟,并通过综合比较炉内各参数的变化确定了最佳燃尽风喷口位置.结果表明:燃尽风喷口位置的上移降低了主燃区氧气的体积分数,同时使炉膛内的最高温度降低了23～29K.燃尽风喷口位置对NOx的还原效果、出口烟气温度以及煤粉焦炭转化率的影响较大.当燃尽风喷口位置升高时,NOx质量浓度降低,炉膛出口烟气温度升高,煤粉焦炭转化率下降.经综合比较炉膛出口烟气温度、NOx质量浓度以及煤粉焦炭转化率得出,距最上层燃烧器7.7m处为最佳燃尽风喷口位置.
Aiming at the problem of high mass concentration of NOx emission in a pulverized coal fired boiler with a swirling burner, air staged combustion is adopted to reduce the emission of NOx. Based on the CFD software platform, under the rated load, three different burnout The results show that the position of the burnout air nozzle is upturned by the comparison of various parameters in the furnace. Reduced the volume fraction of oxygen in the main combustion zone and reduced the maximum temperature in the furnace by 23 to 29 K. The location of the burned out air nozzle greatly affected the NOx reduction, the outlet flue gas temperature and the coke conversion rate When the position of the exhaust air outlet increases, the NOx concentration decreases, the temperature of flue gas at the outlet of the furnace increases, and the coke conversion rate decreases. After comprehensive comparison of the outlet flue gas temperature, NOx concentration and coke conversion rate, 7.7m away from the burner at the top of the burner for the best burnout position.