燃煤锅炉SCR对颗粒物排放特性影响  

Effect of SCR on particulate matter emissions from a coal-fired boiler

作　　者：刘芳琪 于敦喜[1] 吴建群[1] 雷煜 温昶[1] 徐明厚[1] LIU Fangqi;YU Dunxi;WU Jianqun;LEI Yu;WEN Chang;XU Minghou(State Key Laboratory of Coal Combustion,Huazhong University of Science&Technology,Wuhan 430074,Hubei,China)

机构地区：[1]华中科技大学煤燃烧国家重点实验室,湖北武汉430074

出　　处：《化工学报》2018年第9期4051-4057,共7页CIESC Journal

基　　金：国家重点研发计划项目(2016YFB0600601);国家自然科学基金项目(51520105008;51676075)~~

摘　　要：我国电厂多数采用选择性催化还原(SCR)脱硝技术降低电厂NOx排放,目前关于电厂中SCR对颗粒物排放特性的影响研究十分匮乏。本研究对一热电联产锅炉SCR前后颗粒物和飞灰进行取样,分析颗粒物质量粒径分布以及化学成分。采用计算机控制扫描电镜(CCSEM)对飞灰进行分析,获得颗粒物单颗粒成分。结果表明SCR前后PM10均呈双峰分布。经过SCR后,PM0.21浓度降低约62%(质量),而PM_(0.21-1)浓度升高19%(质量);PM1中SO_2相对含量增加约6%(质量),SiO_2和Al_2O_3相对含量降低,而CaO相对含量没有明显变化;经过SCR后,PM_(1-10)浓度降低约17%(质量),成分基本没有变化,但是颗粒成分变得更均一,说明经过SCR后,PM_(1-10)发生交互作用。因此经过SCR后PM_(1-10)浓度降低不仅由于颗粒物在SCR中发生沉积,更有可能是颗粒物之间交互作用导致。Selective catalytic reduction(SCR)technology is usually used in coal combustion power plant to reduce NOx emission.The effects of SCR DeNOx on PM emission are still unclear.In this work,PM and fly ash before and after SCR was sampled.Particle size distribution(PSD)and chemical composition of PM was analyzed.Computercontrolled scanning electron microscope(CCSEM)was used to analyze the fly ash and obtain the composition distribution property of individual PM particles.The effect of SCR DeNOx on PM emission characteristic and its mechanism was investigated.The results show that PM is bimodal distribution before and after SCR.After the flue gas flows through the SCR,PM0.21 decreases 62%(mass)and PM0.21-1 increases 19%(mass).The relative amount of SO2 in PM1 increases 6%(mass)and SiO2 and Al2O3 decrease,while the variation of CaO is insignificant after SCR.The amount of PM1-10 decreases 17%(mass)after SCR.Insignificant change of its chemical composition is observed after SCR.However,the chemical composition distribution of individual PM1-10 particle becomes more homogeneous after SCR.It suggests that significant interaction between PM10 has happened in or after SCR.Therefore,decrease of PM1-10 after SCR is not only because of PM10 deposition in the SCR,but also because of particle interaction.

关 键 词：煤燃烧 颗粒物 粒度分布 选择催化还原 排放特性 CCSEM 

分 类 号：X513[环境科学与工程—环境工程]