三次风摆角影响W火焰锅炉低负荷燃烧及NO_(x)排放特性的试验研究  

Experimental study on the effects of tertiary air angle on the combustion and NO_(x) emission characteristics of a down-fired boiler under low load

作　　者：曾令艳 李晓光[2] 张宁[2] 陈智超[2] 李争起[2] ZENG Lingyan;LI Xiaoguang;ZHANG Ning

机构地区：[1]上海电机学院,上海201306 [2]哈尔滨工业大学,黑龙江哈尔滨150001

出　　处：《电力科技与环保》2021年第6期18-23,共6页Electric Power Technology and Environmental Protection

基　　金：国家自然科学基金项目(51576055)。

摘　　要：为优化锅炉燃烧系统和运行,采用工业试验方法研究三次风摆角(0°、15°和25°)变化对一台采用多次引射分级燃烧技术的350 MW超临界机组W火焰锅炉低负荷下燃烧及NO_(x)排放特性的影响,旨在得出最佳的三次风摆角。测量参数包括浓煤粉气流着火特性,下炉膛温度分布,近燃烧器区域和近三次风区域的烟气组分浓度,炉膛出口飞灰可燃物含量和NO_(x)排放浓度。研究表明:三次风摆角由0°增大到15°时,下炉膛火焰温度及燃烧器区域温度升高;浓煤粉气流着火距离由2.40 m缩短至2.07 m;靠近燃烧器区域O_(2)浓度减小,CO和NO浓度增大;靠近三次风区域NO浓度减小。三次风摆角为15°时,在燃烧器下方区域,O_(2)浓度低至8.5%,而CO浓度高达2619μL/L,NO浓度达到452μL/L;飞灰可燃物含量最低,为4.83%。三次风摆角由15°增大到25°时,下炉膛火焰中心降低,冷灰斗区域温度升高;飞灰可燃物含量明显升高,达到5.72%。三次风摆角变化对NO_(x)排放浓度影响较小,NO_(x)排放浓度在660~681 mg/m^(3)(6%O_(2))之间,综合考虑煤粉着火、燃烧和NO_(x)排放特性,推荐最佳三次风摆角为15°。Aiming to optimize boiler combustion system and operation,in-situ trials were carried out to study the effects of tertiary air angle(0°,15°and 25°)on the coal combustion and NO_(x) emission characteristics in a 350 MW supercritical down-fired boiler under low load.The purpose is to get the optimal tertiary-air angle.The measured parameters include the ignition characteristics of fuel-rich coal/air flow,the temperature distribution of lower furnace,the gas concentrations near the burner and tertiary air areas,the carbon in fly ash and NO_(x) emissions at the furnace outlet.The result shows that as the tertiary air angle increased from 0°to 15°,the gas temperature in the lower furnace and in the burner area rose.Besides,the ignition distance of the fuel-rich coal/air flow decreased from 2.40 m to 2.07 m.At the tertiary air angle of 15°,in below-burner area,the O_(2) concentration was as low as 8.5%,while the CO and NO concentrations were as high as 2619μL/L and 452μL/L,respectively.In addition,the carbon in fly ash was the lowest at 4.83%.On changing the tertiary air angle from 15°to 25°,the flame kernel moved downward,the temperature in the hopper area rose,and the carbon in fly ash increased obviously to 5.72%.The change of tertiary air angle has little effect on NO_(x) emissions(660~681 mg/m^(3) at 6%O_(2)).Based on optimizing pulverized coal ignition,combustion and NO_(x) emission characteristics,an optimal tertiary air angle of 15°is recommended.

关 键 词：超临界W火焰锅炉 工业试验 低负荷 三次风摆角 煤燃烧 

分 类 号：TK221[动力工程及工程热物理—动力机械及工程] TM621.2[电气工程—电力系统及自动化]