基于水泥窑脱硝的碳基还原NO_(x)研究进展  

Research progress of NO_(x)reduction by carbonaceous substances for denitration in cement kiln

作　　者：李东泽 张祥 田键[2,3] 胡攀 姚杰 朱林 卜昌盛 王昕晔 LI Dongze;ZHANG Xiang;TIAN Jian;HU Pan;YAO Jie;ZHU Lin;BU Changsheng;WANG Xinye(School of Energy and Mechanical Engineering,Nanjing Normal University,Nanjing 210023,Jiangsu,China;School of Materials Science and Engineering,Hubei University,Wuhan 430062,Hubei,China;Tianshu New Energy Material Industry Research and Design Institute of Hubei University,Wuhan 430062,Hubei,China;State Power Environmental Protection Research Institute,Nanjing 211800,Jiangsu,China;School of Energy Science and Engineering,Nanjing Tech University,Nanjing 211816,Jiangsu,China)

机构地区：[1]南京师范大学能源与机械工程学院,江苏南京210023 [2]湖北大学材料科学与工程学院,湖北武汉430062 [3]湖北湖大天沭新能源材料工业研究设计院有限公司,湖北武汉430062 [4]国电环境保护研究院有限公司,江苏南京211800 [5]南京工业大学能源科学与工程学院,江苏南京211816

出　　处：《化工进展》2023年第9期4882-4893,共12页Chemical Industry and Engineering Progress

基　　金：国家自然科学基金(52176115);江苏省重点研发计划(BE2019701);江苏省生态环境科研课题(2020002)。

摘　　要：随着水泥行业“超低排放”的推进,NO_(x)排放要求逐步向100mg/m^(3)甚至50mg/m^(3)看齐。水泥窑碳基脱硝通过控制煤粉燃烧产生焦炭和CO还原NO_(x),具有无须添加脱硝剂、避免氨逃逸、与生产流程结合良好、改造和运行成本低的优势,可作为水泥行业实现“超低排放”的辅助工艺。本文首先介绍了碳基脱硝的主要实施方式,包括回转窑低氮燃烧、分解炉分级燃烧和增设还原区等。然后讨论了焦炭和CO还原NO_(x)的特性和机制。焦炭还原效果与其比表面积和活性位点有关。CO还原反应可在无催化条件下发生,但CO体积分数小于1%时效果可以忽略。焦炭、CaO和煤灰等可作为催化剂,将CO还原NO的温度窗口下限从900℃降低至600~800℃。最后综述了CO对选择性非催化法(SNCR)的影响及其机制,认为碳基脱硝与氨基脱硝具有耦合协同潜质。水泥窑碳基脱硝的进一步研究可以关注以下方面:在更为全面和系统的工况下评价脱硝特性,试验和理论结合明确脱硝机制,开发碳基与氨基协同脱硝技术等。With the popularization of“ultra-low emission”standard in cement industry,the NO_(x)emission limit is gradually reduced to 100mg/m^(3)or even 50mg/m^(3).The carbonaceous denitration in cement kiln is carried out by controlling pulverized coal combustion to produce coke and CO as the NO_(x)reducing agent.It has the advantages of no additional denitration agents,no ammonia emission,good compatibility with the cement production processes and low cost of technical revamp and operation,providing the auxiliary processes for the cement industry to achieve the“ultra-low emission”standard.In this paper,the main implementations of carbonaceous substance denitration were introduced,including the low nitrogen oxide burning in rotary kiln,the staged combustion in decomposition furnace and the addition of reduction zone.Then,the characteristics and mechanism of NO_(x)reduction by coke and CO were discussed.The reduction effects of coke are related to its specific surface area and reactive sites.The CO reduction can occur without catalysis,but the efficiency could be ignored when CO concentration is less than 1%.Coke,CaO and coal ash act as catalysts to reduce the lower temperature window limit of NO reduction by CO from 900℃to 600-800℃.Finally,the influence of CO on SNCR and its mechanism were summarized.It is considered that carbonaceous denitrification and amino denitrification could be coupling and work together.Further research on carbonaceous denitration in cement kilns could focus on the following aspects:evaluating the denitration characteristics under more comprehensive and systematic conditions,clarifying the denitration mechanism by combining experimental and theoretical investigation,and developing the combined technology of carbonaceous denitrification and amino denitrification.

关 键 词：水泥窑 脱硝 焦炭 一氧化碳 催化 氧化钙 飞灰 

分 类 号：TQ172[化学工程—水泥工业]