燃尽风率对燃煤锅炉NO_x生成特性影响的数值模拟  

Numerical Simulation of Effect of Over-fire Air Ratio on NO_x Formation in Coal-fired Boiler

作　　者：孙保民[1] 王顶辉[1] 段二朋[1] 郭永红[1] 白涛[1] 张守恒[2] 

机构地区：[1]华北电力大学电站设备状态监测与控制教育部重点实验室 [2]绥中发电有限责任公司

出　　处：《电站系统工程》2013年第1期9-12,共4页Power System Engineering

摘　　要：为了研究燃尽风率对锅炉燃烧及NOx排放的影响,利用CFD方法通过恰当的物理模型和数学方法对某800 MW超临界锅炉进行了不同燃尽风率下的数值计算。对温度场及相关组分场进行了详细的分析,结果表明燃尽风率越大,主燃区温度和氧浓度均有所降低,CO浓度明显升高,NOx浓度明显降低。空气分级燃烧降低NOx排放的同时,不可避免地对燃料的燃尽及出口烟温产生不利影响。在计算的燃尽风率范围内,炉膛出口NOx浓度随燃尽风率增加基本呈线性递减规律。当燃尽风率在15%～20%范围内变化时,其负面影响相对较小,但在较高燃尽风率下,其负面影响开始凸显。To investigate the effect of over-fire air ratio on combustion and NOx formation in the furnace,numerical simulations based on reasonable physical model and calculation method were conducted for an 800MW ultra-supercritical utility boiler with different over-fire air ratio.Temperature field and related species field in the furnace were analyzed in detail,the results showed that the larger over-fire air ratio,the lower temperature and oxygen concentration in primary combustion zone,which made an obvious reduce on NOx concentration.While staged-air combustion technology can reduce NOx emission,it also brings some adverse effects on coal burn-out and outlet gas temperature.In over-fire air ratio range 15% to 25%,NOx concentration at the furnace outlet shows linear decrease.Adverse effects were relatively small in over-fire air ratio range 15% to 20%,but were highlighted at higher over-fire air ratio.This conclusion can give reference for practical operation.

关 键 词：燃煤锅炉 空气分级燃烧 燃尽风率 NOx 数值模拟 

分 类 号：TK224[动力工程及工程热物理—动力机械及工程]