锅炉低NO_x燃烧中的三次风运行优化  

Tertiary air operation optimization aiming at low NO_x combustion in boiler

作　　者：杨卫娟[1] 周志军[1] 刘茂省[1] 秦岭[1] 刘建忠[1] 周俊虎[1] 岑可法[1] 

机构地区：[1]浙江大学能源清洁利用国家重点实验室,浙江杭州310027

出　　处：《浙江大学学报（工学版）》2008年第7期1227-1230,1270,共5页Journal of Zhejiang University：Engineering Science

基　　金：新世纪优秀人才支持计划资助项目(NCET-04-0533)

摘　　要：针对一台410 t/h乏气三次风、热风送粉的中储式燃煤锅炉,采用Fluent软件进行数值模拟,得到了炉内切圆和烟气中NOx气体质量浓度随炉膛高度的变化趋势.计算结果表明,高速喷入的三次风使炉内切圆在三次风喷口处缩小,同时引起当地炉膛截面上的NOx质量浓度增加.锅炉大修时,进行了低NOx燃烧技术改造的同时,进行了三次风系统改造,并就改造后三次风运行进行了优化试验.试验结果表明,磨煤机运行方式不同可造成NOx排放质量浓度相差63.8%,差值高达148 mg/m3.锅炉双磨运行时NOx排放随三次风量增加而略有增加.无磨运行工况的NOx排放最低,其次是单磨运行工况,双磨运行时NOx排放最高,且双磨运行时飞灰含碳量较高.B磨单磨运行是最佳运行方式,可使得NOx排放和飞灰含碳量处于较佳状态.Fluent software was used to simulate pulverized coal （PC） combustion in a 410 t/h boiler which had a PC bin and used hot air as PC carrier air and exhaust flow of mills as tertiary air. The tangential circle and the NOx concentration in furnace flow were obtained. Simulation showed that the high velocity tertiary air spray decreased the tangential circle diameter and increased the NOx concentration near the tertiary air ports level. During the boiler overhaul period, the tertiary air system was retrofitted and the coal reburning technology was applied to realize low NOx combustion. The tertiary air operation was optimized after the retrofit. Experimental results indicated that NOx emission was affected remarkably by the tertiary air operation mode and the NOx emission difference was 63.8% relatively and 148 mg/m^3 absolutely. NOx emission increased as tertiary air flow increasing when both mills run. NOx emission was lest at no mill running, less at single mill running and highest at both mills running. And unburnt carbon （UBC） was highest at both mills running. The optimal operation condition was mill B running, on which NOx emission and UBC in fly ash can be kept in good range.

关 键 词：锅炉 三次风 煤粉 燃烧 NOx 数值模拟 

分 类 号：X511[环境科学与工程—环境工程]