烧结烟气中NO_(x)减排进展

Progress and exploration of NO_(x) emission reduction in sintering flue gas

铁矿石烧结是钢铁工业生产的重要一环,同时也是大气中NO_(x)污染物的主要排放源。随着人们对大气环境的要求越来越高,烟气排放标准日益严格,如何高效、低成本脱除烧结烟气中的NO_(x)已经成为了钢铁企业面临的一个巨大挑战。首先介绍了烧结工序烟气NO_(x)的排放规律及现状,然后从烟气中NO_(x)生成机理出发,深入解析了煤燃料在热解和燃烧中氮的氧化还原机制,详细阐述了温度、氧及某些金属对煤中氮转化的不同影响,再结合NO_(x)的理化属性进一步指出了氧化/还原脱硝路径,并介绍了现阶段根据这2条路径开发的各种源头、末端和过程烟气治理手段;同时,结合不同的脱硝路径,深入分析了SCR催化还原机制、催化氧化机制和铁酸钙催化还原脱硝机制,全面总结对比了近期常见的各种NO_(x)减排举措的研究进展,其中铁酸钙催化过程脱硝以其低成本、显著的脱硝效果和不增加任何气、固污染物的特点而展示出巨大的潜力。最后,结合国家超低排放新的要求和钢铁企业烧结生产的现状,指出了当前钢铁工业烧结烟气高效、经济脱硝所面临的研究挑战,并展望了铁酸钙催化过程脱硝的应用前景和发展方向。

Iron ore sintering is an important part of the production of iron and steel industry,and it is also the main source of NO_(x) pollutants in the atmosphere.As people's requirements for the atmospheric environment getting higher and higher,and flue gas emission standards becoming more and more stringent,how to remove NO_(x) from sintering flue gas efficiently and at low cost have become a huge challenge for iron and steel enterprises.This paper firstly introduces the emission law and current situation of NO_(x) in flue gas during sintering process,and then starts from the formation mechanism of NO_(x) in flue gas,deeply analyzes the redox mechanism of N in coal pyrolysis and combustion,expounds the influence of temperature,oxygen and some metals in the transformation process of N.Combining with the physical and chemical properties of NO_(x),the various treatment methods corresponding to the oxidation/reduction two routes are introduced,and the various source,end and process flue gas treatment methods developed according to these two paths at these routes are introduced too.At the same time,Combining different denitration paths,the SCR catalytic reduction,catalytic oxidation mechanism and catalytic mechanism of calcium ferrite are deeply analyzed,the recent research progress of various NO_(x) emission reduction measures is comprehensively summarized and contrasted.Among them,calcium ferrite catalytic denitrification shows great potential due to its low cost,remarkable denitrification effect and no new gas and solid pollutants.Finally,according to the new national ultra-low emission requirements and present situation of sintering production in iron and steel enterprises,this paper point out the research challenges faced by the efficient denitrification and current economic,and prospect the application prospect and development direction of calcium ferrite catalytic denitrification.