大型褐煤锅炉煤粉再燃技术的数值模拟

Numerical Simulation of Pulverized-coal Reburning Technology for a Large-sized Lignite-fired Boiler

考虑煤焦还原NO的反应动力学模型,利用Fluent软件对元宝山电厂3号锅炉超细煤粉再燃的不同配风方式进行了炉膛整体的燃烧数值模拟。模拟结果表明,再燃燃料比例、再燃风中的风煤比、再燃区的大小等因素对燃烧效率和NOx排放具有重要影响。通过优化计算得到,当主燃区空气过量系数控制在1.1时,再燃燃料占总燃料的15%,再燃风中的风煤比为2,烟气在再燃区的停留时间为0.5 s左右的方案是一种较好的再燃组织方式。

A numerical simulation was conducted of the different combustion air-supply modes for reburning super-fine pulverized coal in an integral furnace of Yuanbaoshan Power Plant No.3 Boiler on the basis of a dynamic model featuring coal tar NO reduction reaction and by using software Fluent.The numerical simulation results show that a variety of factors,such as the proportion of fuels being reburned, air-coal ratio in the combustion air for reburning and the size of the reburning zone etc.can exercise a major influence on combustion efficiency and NO_x emissions.An optimization calculation has revealed that when the excess air factor in the main combustion zone is controlled at 1.1,a scheme with the following characteristics,namely,the fuel being reburned accounting for 15% of the total fuel amount,coal-air ratio in the combustion air for reburning being set at 2 and the residence time of the flue gas in the reburning zone being about 0.5 s,may be considered as a comparatively well organized mode for reburning.