煤粉锅炉氮氧化物排放影响因素的数值模拟

来源期刊:中南大学学报(自然科学版)2010年第5期

论文作者:夏小霞 王志奇 徐顺生

文章页码:2046 - 2052

关键词:煤粉锅炉;数值模拟;NOx排放;配风方式

Key words:pulverized coal boiler; numerical simulation; NOx emissions; air distribution type

摘    要:针对1台35 t/h煤粉锅炉,应用数值模拟的方法,研究配风方式、煤粉粒径以及空气过量系数对NOx排放的影响。模拟结果表明:在计算的几种工况中,束腰型送风方式生成的NOx浓度最低,倒塔型的次之,而均匀型的最大;相比均匀型配风方式,束腰型配风方式的NOx排放浓度可降低15.6%;当三次风比例从20%增大到25%时,NOx排放浓度可降低20.5%;锅炉NOx排放随着煤粉粒径的减小而明显降低;与设计工况相比,当煤粉粒径由90 μm降低至50 μm时,NOx的排放浓度可降低14.3%;随着过量空气系数的减小,锅炉出口处的NOx浓度减小,合适的过量空气系数为1.1,此时NOx排放浓度可降低5.8%。

Abstract: The effects of air distribution, particle size and excess air rate on NOx emissions for a 35 t/h pulverized coal boiler were researched by numerical simulation. The results show that the concentration of NOx produced by girdled air distribution is the lowest, among the several combustion conditions, followed by the reverse-tower type, and the type of equal air distribution produces the highest concentration. There is a 15.6% decrease in NOx emissions of girdled air distribution compared with the equal type. When the rate of third air increases from 20% to 25%, concentration of NOx decreases by 20.5% compared with equal type. The concentration of NOx decreases obviously with the decrement of pulverized coal size. Compared with the original condition, it can decrease by 14.3% when the average diameter of pulverized coal is 50 μm. The concentration of NOx decreases with the decrement of excess air rate. The proper excess air ratio is 1.1 for the boiler. In this condition, the concentration of NOx can decrease by 5.8% compared with the original condition.

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