煤粉燃烧火焰区域内形成的亚微米颗粒电镜研究  

THE ELECTRON MICROSCOPY STUDY OF PMI IN THE PULVERIZED-COAL FLAME

作　　者：卓建坤[1] 李水清[1] 宋蔷[1] 姚强[1] 

机构地区：[1]清华大学热能工程系,热科学与动力工程教育部重点实验室,北京100084

出　　处：《工程热物理学报》2008年第5期871-875,共5页Journal of Engineering Thermophysics

基　　金：国家重点基础研究发展规划资助项目(No．2002CB211606);国家自然科学基金(No．50776054)

摘　　要：煤粉燃烧火焰区域是燃烧过程中温度最高的区域,同时也是温度梯度、组分浓度梯度最高的地方,以及还原和氧化气氛交错存在等复杂环境,这种环境对亚微米颗粒初始形成阶段有着重要的影响,对该区域形成的PM_1进行研究有助于深入理解PM_1的形成机理.本文基于25 kW一维下行炉内对自维持燃烧的煤粉火焰区域,通过两级稀释水冷等速取样系统和ELPI(荷电低压撞击分离器)系统对颗粒物进行分级收集,以及电镜分析技术,获得PM_1的质量和数浓度粒径分布,以及各粒径主要成分分布,并进行单颗粒分析.结果表明火焰区域中形成的亚微米颗粒以含碳物质为主.碳烟、碱金属和硫对超细颗粒有富集的趋势.该区域的亚微米颗粒同时存在多种复杂的形成机理.The highest flame temperature, temperature field, constituents gradient and coexist of oxidation and reduce conditions, make an important effect on the formation of submicron particles （PM1）. In this paper, the PM1 generated from a pilot-scale 25 kW down-fired combustor was extensively investigated by using a nitrogen-aspirated, water-cooling isokinetic probe with two-stage dilution. A 13-stage Electric Low Pressure hnpactor （ELPI） was used to deposit particles. Among which the last eight stages（PM1） are selected for the further analysis by the EM（electron microscopy） technology. The particle size distribution of mass and number concentration obtained from ELPI, the species distributions in each stage of ELPI and individual particle analysis obtained from EM analysis, show that alkalie, sulfur and soot have the tendency to partitioning to the finer particles in the PM1. Further study show these two portions are formed from different sources.

关 键 词：煤粉燃烧火焰区域 亚微米颗粒 电镜分析 

分 类 号：TK16[动力工程及工程热物理—热能工程] X51[环境科学与工程—环境工程]