洁净煤技术

2020, v.26;No.129(05) 64-69

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水泥分解炉中CO还原NO试验研究
Experimental study on NO reduction by CO in cement precalciner

李森;方立军;孙立超;赵砣;
LI Sen;FANG Lijun;SUN Lichao;ZHAO Tuo;State Key Laboratory of High-temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences;School of Energy & Mechanical Engineering,North China Electric Power University;

摘要(Abstract):

水泥窑炉是典型的高污染排放的工业窑炉,水泥行业已成为第三大氮氧化物排放源。目前,国内外对燃料分级技术在电站锅炉上的应用进行了大量研究,而对水泥窑炉上应用燃料技术涉及较少。针对水泥分解炉高钙环境分级燃烧特点,在流化床反应器上开展了还原气体CO脱除NO的试验研究,研究了CO浓度、CaO和温度对CO脱硝过程的影响机制,采用一维柱塞流反应器模拟分析了CO还原NO反应路径。研究结果表明:CO在还原气氛中具有较强的脱硝作用,CO体积分数对脱硝具有较大影响,随着CO浓度增加,脱硝效率提高;随CO浓度提升可有效降低NO排放,当CO浓度由1%增加到5%,NO脱除效率提高了37.8%;CO脱硝过程中产生NH和H等中间产物,NH和H对CO还原NO具有重要作用;HCN可吸附于CaO表面并与CaO反应,在还原气氛中,NH_3吸附到—CaO表面并发生反应生成Ca(N),最终生成N_2。NO主要通过4条路径被还原为N_2,其中NO→N_2O→N_2和NO→HNO→NH→N_2为最主要反应路径。在试验温度范围内,温度升高促进了CO还原脱硝;CaO对CO脱硝具有较强的正催化作用,且在850~1 050℃,CaO均具有催化作用。CO体积分数为4%、温度大于900℃时,CO脱硝效率明显提高,说明在高温区域,CaO具有显著的催化作用;在1 050℃,脱硝效率提高7.56%。
Cement kiln is a typical industrial furnace with high pollution emission,and the cement industry has become the third largest source of NO_xemission.At present,a lot of research has been done on the application of fuel staged combustion technology in utility boilers at home and abroad,but less on cement kiln.According to the characteristics of staging combustion for high calcium environment in cement precalciner,the experimental study on NO removal by reducing gas CO was carried out in fluid bed reactor,and the effects of CO concentration,Ca O and temperature on the denitrification process of CO were studied.The reaction path of NO reduction by CO was simulated in a one-dimensional plug flow reactor.The results indicate that CO has a strong denitrification effect in reducing atmosphere,and CO concentration has a great influence on denitrification.With the increase of CO concentration,the NO reduction efficiency increases.The NO emission is effectively reduced with the increase of CO concentration,and when the CO concentration increases from 1% to 5%,the efficiency of NO reduction increases by 37.8%.During NO reduction by CO,the intermediate products such as NH and H are produced,and NH and H play an important role in the NO reduction by CO.HCN can be adsorbed on Ca O surface and reacts with Ca O.In reducing atmosphere,NH_3adsorbs on Ca O surface and reacts to form Ca(N) and finally forms N_2.NO is reduced to N_2mainly through four pathways,and the paths of NO→N_2O→N_2 and NO→HNO→NH→N_2 are the most important reaction paths.In the experimental temperature range,the increase of temperature promotes the reduction and denitrification of CO.Ca O has a strong positive catalysis on CO denitrification at 850℃

关键词(KeyWords): 水泥分解炉;CO;CaO;NO还原
cement precalciner;CO;CaO;NO reduction

Abstract:

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基金项目(Foundation): 国家重点研发计划资助项目(2016YFB0601503)

作者(Author): 李森;方立军;孙立超;赵砣;
LI Sen;FANG Lijun;SUN Lichao;ZHAO Tuo;State Key Laboratory of High-temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences;School of Energy & Mechanical Engineering,North China Electric Power University;

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DOI: 10.13226/j.issn.1006-6772.IF20080607

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