燃烧中铅元素排放特性的实验研究  

Experimental Study on the Emission Characteristics of Lead During Combustion

作　　者：张小锋[1] 姚强[1] 宋蔷[1] 李水清[1] 

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

出　　处：《中国电机工程学报》2007年第32期18-23,共6页Proceedings of the CSEE

基　　金：国家重点基础研究发展规划基金项目(2002CB211606)~~

摘　　要：使用一维炉实验台对铅颗粒的空气动力学粒径分布、化学成分、微观形貌等排放特性进行了实验研究,并对铅颗粒的形成机理和途径进行了分析探讨。铅以醋酸铅溶液的形式通过空气雾化引入到液化石油气燃烧区。按照美国EPA标准方法使用Andersen撞击器对颗粒物进行等动量采样以获得颗粒粒径分布。研究结果表明:约2/3的铅颗粒空气动力学粒径小于480nm,质量浓度呈单峰分布且峰值在0.2～0.6μm,颗粒的化学成分是PbO;存在氯元素时,铅颗粒粒径分布没有发生显著变化,但颗粒的化学成分变为PbCl2,表明氯与铅有非常强的反应性。对铅颗粒微观形貌的观察发现了一种基本颗粒,其特征为粒径在50nm左右且边界清晰,是构成整个颗粒团的基本单元。基本颗粒连接形成链状,颗粒链又交织形成网状,最终形成粒径数百纳米的颗粒团,这是铅颗粒排放时的主要形态。根据对微观形貌的观察将铅颗粒形成途径进行了细化,指出基本颗粒可能是颗粒形成过程中的一个重要的界点。The emission characteristics of lead, such as aerodynamic particle size distribution （PSD）, chemical composition and morphology, were investigated experimentally using a laboratory one-dimension furnace. Also the formation mechanisms and pathways of lead particles were analyzed and discussed. Aqueous solution of lead acetate was introduced into furnace through a liquefied petroleum gas flame via air atomization. PSDs were obtained by isokinetic sampling using Thermo Andersen impactor according to standard method of U.S. EPA. The results show that： About 2/3 of lead particles have the aerodynamic diameter less than 480nm, mass concentration distribution is a single modal PSD with peak between 0.2-0.6μm, and the chemical composition of particles is PbO; In the presence of chlorine, the PSD of lead particles is not obviously change, the chemical component of particles becomes to PbCl2, it indicates that chlorine has highly reactivity with lead. It is found from micrographs of lead particles that there exist some basic particles, having about 50nm size and clear boundary, which are basic units composing one whole particle group. These basic particles link together and become a chain. The chains cross with each other and become a network. Ultimately, a particle group having several hundreds nanometer size come into being, which is the main configuration of lead particle released. The formation pathways of lead particles were specified according to the observation of micrographs. The basic particles may be an important point during the particle formation process.

关 键 词：铅 排放特性 颗粒物 粒径分布 颗粒形成 

分 类 号：TK16[动力工程及工程热物理—热能工程] X513[环境科学与工程—环境工程]