球团烟气SNCR与嵌入式SCR耦合脱硝新技术  

Innovative coupled denitrification technology of SNCR and embedded SCR for pelletizing flue gas

作　　者：刘臣 胡兵[1,2] 胡佩伟 温荣耀[1,2] 叶恒棣[1,2] 魏进超 LIU Chen;HU Bing;HU Pei-wei;WEN Rong-yao;YE Heng-di;WEI Jin-chao(Engineering Center of Sinter Pellet and Direct Reduction,Zhongye Changtian International Engineering Co.,Ltd.,Changsha 410205,Hunan,China;National Engineering Research Center of Sintering and Pelletizing Equipment System,Changsha 410205,Hunan,China;School of Resources and Environment Engineering,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China)

机构地区：[1]中冶长天国际工程有限责任公司烧结球团及直还工程技术中心,湖南长沙410205 [2]国家烧结球团装备系统工程技术研究中心,湖南长沙410205 [3]武汉科技大学资源与环境工程学院,湖北武汉430081

出　　处：《钢铁》2022年第3期133-141,共9页Iron and Steel

基　　金：湖南省自然科学基金资助项目(2019 JJ51007);湖南创新型省份建设专项资金资助项目(2020GK4055)。

摘　　要：在中国大力推动绿色低碳发展的形势下,钢铁行业全面实施烧结、球团工业大气污染物超低排放,球团NO_(x)减排迫在眉睫,减排效果将关乎球团行业的生存与发展。针对国内主流的链箅机-回转窑球团生产工艺NO_(x)排放质量浓度高的问题,在系统分析球团烟气特性与NO_(x)分布的基础上,开展了选择性非催化还原法脱硝技术(SNCR)与嵌入式选择性催化还原法脱硝技术(SCR)的耦合脱硝技术研究。研究结果表明,在链箅机源头的预热二段,球团烟气具有高温(烟罩内850~1000℃、风箱内350℃)、高NO_(x)浓度(400~600 mg/m^(3))、小流量的特性,有助于SNCR法与嵌入式SCR法协同耦合治理技术应用。当采用氨水作还原剂、烟气温度为830~930℃、氨氮物质的量比为1.0~1.5时,SNCR法脱硝率达40%~60%。在链箅机上装配风流平衡板可解决串风问题,预防NO_(x)无序扩散;采取NO_(x)集中处理,同时实施还原剂喷加量精准调控,可综合提升还原剂利用效率及SNCR脱硝率。采用FLUENT数值模拟方法对SCR反应器的圆锥形扩散板进行结构优化发现,当扩散板水平夹角由90°倾斜至65°~75°时,进入整流格栅的烟气流速与氨还原剂分布更加均匀;优化的球团烟气SNCR与嵌入式SCR耦合脱硝技术路线合理、技术经济性能优越、工程产业化推广前景广阔,是中国球团烟气氮氧化物超低排放技术的一大创新。Under the situation of vigorously promoting green and low-carbon development in China,iron and steel industry comprehensively implements ultra-low emission of air pollutants from sintering and pelletizing.At present,the NO_(x) emission reduction in pelletizing is imminent,which is related to the survival and development of pellet industry.Aiming at the problem of high NO_(x) emission concentration in the domestic mainstream grate-kiln process of pelletizing production,research on coupled denitrification technology of selective non-catalytic reduction denitrification technology(SNCR)and embedded selective catalytic reduction denitrification technology(SCR)was conducted on the basis of system analysis for flue gas features and NO_(x) distribution.The results show that pelletizing flue gas has the characteristics of high temperature(850-1000℃in the hood,350℃in the bellows),high NO_(x) concentration(400-600 mg/m^(3))and small flow at the preheating stage of grate source,which is conducive to the collaborative coupling technology application of SNCR and SCR methods.When ammonia hydroxide is used as reducing agent,flue gas temperature is 830-930℃and ammonia nitrogen mole ratio is 1.0-1.5,the denitrification rate of SNCR method can reach 40%-60%.The assembly of air balance plate on the grate can solve the cross air problem and prevent the disorderly diffusion of NO_(x).Then adopting NO_(x) centralized treatment and implementing precise control of reducing agent dosage,can comprehensively improve the utilization efficiency of reducing agent and SNCR denitrification rate.Optimizing the structure of conical diffusion plate in SCR reactor was made by FLUENT numerical simulation method.When the horizontal angle of diffusion plate was tilted from 90°to 65°-75°,the distribution of flue gas velocity and ammonia reducing agent into the rectifier grid were more uniform.The optimized pelletizing flue gas SNCR coupling embedded SCR denitrification technology has a reasonable route,superior technical and economic performanc

关 键 词：链箅机-回转窑 超低排放 SNCR法 嵌入式SCR法 NO 减排 

分 类 号：X701[环境科学与工程—环境工程]