超超临界锅炉炉内燃烧过程的数值模拟

采用计算流体力学软件PHOENICS，选择合理的数学模型，对1台1000 MW超超临界单炉膛双切圆煤粉炉内的燃烧过程进行数值模拟．着重研究了单炉膛双切圆燃烧特性、炉内焦炭燃烧特性及NO生成特性。结果表明：燃烧器前后墙布置导致炉内气流呈椭圆形，NO生成总体水平较低，焦炭燃尽效果较好，但在炉膛高度方向40m以上的区域，烟气高温区及大量未燃尽焦炭偏向前墙附近，且未燃尽焦炭在辐射屏区逐渐燃尽。针对这一问题提出了解决方案，结果表明：改进后的工况明显提高了焦炭的燃烧速度．使其在屏区以下基本燃尽，NO2排放量也有所降低。

Numerical Simulation of Combustion Processes in an Ultra Supercritical Boiler

With the CFD(computational fluid dynamics) software PHOENICS and a reasonable mathematical model,numerical simulations of combustion processes in a double-tangential firing single furnace boiler of a 1000 MW ultra supercritical unit has been performed.Particularly studied were the characteristics of double-tangential firing,of coke firing and those of NOx emission.Test results show that the arrangement of burners,on the front and rear wall,cause gas flow in the furnace to assume an elliptical shape,with little NO_x emission in toto and high burn out efficiency in case of coke.However,the high temperature gas zone as well as a lot of unburned coke veer towards the front wall at a furnace height above 40 m,with the remaining coke gradually burning out in the radiation platen zone.A solution of the problem is proposed,trial application of which remarkably raised the coke's combustion speed and made the coke basically burn out before reaching the platen zone,with somewhat reduced NO_x emission.Figs 8,tables 3 and refs 11.