无烟煤高温火焰贫氧区喷氨降低NO_(x)排放试验  

Experimental study on nitric oxide reduction by urea solution injection into low-oxygen zone of anthracite coal combustion flame

作　　者：许芸 朱志祥 董月红 张乾 徐静馨 张忠孝[2] 李子祥 乌晓江[2] XU Yun;ZHU Zhixiang;DONG Yuehong;ZHANG Qian;XU Jingxin;ZHANG Zhongxiao;LI Zixiang;WU Xiaojiang(Science and Technology Research Institute Co.,Ltd.,CHN Energy,Nanjing 210046,China;School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]国家能源集团科学技术研究院有限公司,南京210046 [2]上海交通大学机械与动力工程学院,上海200240

出　　处：《环境工程》2025年第1期167-174,共8页Environmental Engineering

基　　金：低碳智能燃煤发电与超净排放全国重点实验室开放课题(D2021FK058)。

摘　　要：W火焰炉是燃用低挥发分煤种的主要炉型,其NO_(x)排放远高于常规煤粉锅炉,如何减排成为亟待解决的关键问题。在高温沉降炉试验平台上详细研究了无烟煤燃烧过程中过量空气系数、氨氮摩尔比(NH_(3)/NO_(x))、温度等因素对高温富燃料区直喷尿素溶液降低NO_(x)排放的影响。结果表明:过量空气系数由1.05降低至0.75时,空气分级燃烧可以降低约30%的NO_(x)排放。在空气分级基础上向高温富燃料区通入尿素溶液可以进一步降低NO_(x)排放,较低的过量空气系数和较高的温度有利于提高尿素溶液的NO_(x)还原效率。1400℃或氧化性气氛下,最佳氨氮摩尔比为1.5;此时过量空气系数为0.75,高温富燃料区直喷尿素溶液可在空气分级基础上实现32.47%的NO_(x)还原效率,炉膛出口NO_(x)排放浓度最低可降至438.30 mg/Nm3。而在较低温度、还原性气氛下,最佳氨氮摩尔比为2.0。研究结果验证了燃无烟煤W火焰炉采用高温富燃料区直喷尿素溶液在降低NO_(x)排放方面的有效性。Down-fired boilers are designed to burn low-volatile coal,of which the NO_(x)emission is much higher than that of conventional coal-fired boilers.With the proposal of ultra-low emission standards for thermal power units,the efficient and low-cost reduction of NO_(x)emission in down-fired boilers has become a key issue to be solved urgently.Experiments were conducted in a high-temperature drop tube furnace to investigate the effects of excess air ratio(λ),NH_(3)/NO_(x)molar ratio(NSR),temperature,etc.on the NO_(x)reduction characteristics during anthracite coal combustion by urea solution injection into the high-temperature fuel-rich zone.The experimental results indicated that air-staging combustion could lower approximately 30%of NO_(x)emissions when the excess air ratio was decreased from 1.05 to 0.75.NO_(x)emissions could be further lowered by urea solution injection into a high-temperature reduction zone based on air-staging combustion,and a lower excess air ratio and higher temperature were conducive to the NO_(x)reduction efficiency of urea solution.The optimal NH_(3)/NO_(x)molar ratio was 1.5 under 1400℃or oxidizing atmosphere.However,the optimal NH_(3)/NO_(x)molar ratio was shifted to 2.0 under relatively lower temperatures and a reducing atmosphere.Urea solution injection into a high-temperature fuel-rich zone could reduce 34.27%of NO_(x)emissions and achieve a minimum NO_(x)emission of 438.30 mg/Nm3 under the optimal experimental conditions,i.e.,temperature of 1400℃,excess air ratio of 0.75,NH_(3)/NO_(x)molar ratio of 1.5.Our findings verify the effectiveness of urea solution injection into the high-temperature fuel-rich zone in lowering NO_(x)emission in downfired boilers burning anthracite coal.

关 键 词：无烟煤燃烧 过量空气系数 氨氮摩尔比 温度 NO_(x)排放 

分 类 号：X701[环境科学与工程—环境工程]