为研究低负荷工况下锅炉的稳燃能力，定义了火焰推举距离，即以900 ℃的温度作为火焰边界，以火焰边界与燃烧器出口之间的距离作为火焰推举距离。采用ANSYS Fluent模拟软件对某电厂350 MW前后墙对冲锅炉内的燃烧状况进行模拟，并根据试验确定了该锅炉的最低发电负荷为24.8%时，火焰推举距离的极限值为3.15 m。进一步分析了煤种、煤粉粒径、一次风量、二次风量、二次风温度、再循环烟气量和燃烧器燃烧方式等因素对火焰推举距离的影响，研究表明：减小煤粉粒径、减少一次风量、关闭再循环烟气量和燃烧器对冲燃烧方式，这四种因素能显著地减小火焰推举距离。最后综合这四个有利因素，将煤粉粒径减小至5.6×10-5 m，通过磨煤机和燃烧器的阀门调节把一次风量降低至60%的风量，关闭再循环烟气挡板，采用上层燃烧器冲燃烧方式，能够将该锅炉的发电负荷降低至7.39%的最低负荷，并保持安全稳定运行。

In order to study the stable burning capacity of the boiler under low load conditions,the flame pushing distance is defined as the flame boundary at 900 ℃,and the distance between the flame boundary and the burner outlet is used as the flame pushing distance.The ANSYS Fluent simulation software was used to simulate the combustion condition of the 350 MW front and rear walled boiler in a power plant under low load conditions.According to the test,the limit of the flame pushing distance was 3.15m when the generating load of the boiler was 24.8%.The effects of seven factors,such as coal type,pulverized coal particle size,primary air volume,secondary air volume,secondary air temperature,recirculated flue gas volume and burner combustion mode,on the flame lift distance were further analyzed.Studies have shown that: four factors can significantly reduce the flame push distance,including reducing the particle size of pulverized coal,reducing the amount of primary air,and closing the amount of recirculated flue gas and burner combustion mode.Finally, the four favorable factors are combined to reduce the particle size of pulverized coal to 5.6×10-5m.The air volume is reduced to 60% by the valve adjustment of the coal mill and the burner, and the recirculating flue gas baffle is closed. The hedging combustion method of layer A, B or C, D. In the case of ensuring that the pushing distance of the flame is>3.15 m，the power generation load of the boiler can be reduced to 7.39%, and the safe and stable operation is maintained.

TM611；TK16

华能国际电力股份有限公司丹东电厂科技基金项目（HN-4620-201700126-JSQT00003）