600MW燃用褐煤新型墙式切圆锅炉燃烧性能分析

Combustion Performance Analysis of a New Type 600 MW Lignite-Fired Wall Tangential Boiler

针对某台采用墙式切圆燃烧的600 MW超临界褐煤锅炉在实际运行中出现的水冷壁结焦、超温爆管等问题,采用冷热态计算机数值模拟方法进行了研究,并通过现场参数测试及系统优化调整对模拟结果的合理性进行验证。结果表明:锅炉炉膛出口左右侧存在速度与烟温偏差,燃尽风的投切对炉膛出口气流速度分布影响很大,具有很好的消旋作用。计算机数值模拟及现场的参数测试揭示了炉膛内部存在一个直径较大且稳定旋转的“高温火环”,一方面提高了锅炉高水分褐煤点火和稳燃性能,另一方面过高的一次风率和过大的切圆直径导致了水冷壁结焦和局部超温爆管,影响机组的安全稳定运行。研究结果和方法对同类型锅炉优化设计及运行提供了参考,为高效利用低热值、高水分、易结焦褐煤提供了新的思路。

This paper aims to investigate the causes of problems such as slagging on water walls and tube failure due to overheating in the actual operation of a 600 MW supercritical lignite-fired wall-tangential boiler.The author conducts cold and hot-state numerical simulations and validates the simulation results through on-site parameter testing and system optimization adjustments.The results show persistent differences in velocity and temperature imbalance between the left and right sides of the furnace outlet.Feeding and cutting off SOFA significantly affects the air velocity distribution,thus effectively reducing residual swirl.Computer numerical simulations and on-site parameter testing reveal the existence of a largediameter and stable rotating "high-temperature fire ring" inside the furnace.It facilitates the ignition of high-moisture lignite and improves combustion stability,but the high primary air ratio along with the large diameter cause slagging and local overheating,thus imperiling the safe and stable operation of the unit.The results and methods of this paper provide a reference for optimal design and operation of similar boilers and offer new ideas for the efficient utilization of high-moisture lignite,which has low heat value and tends to cause slagging.