SO2-NO2-NH3-H2O四元反应体系中气溶胶的生成特性  

Formation characteristics of aerosols in the SO2-NO2-NH3-H2O quaternary system

作　　者：萧嘉繁 刘鹤欣 谭厚章[1] 杜勇乐 王毅斌[1] XIAO Jia-fan;LIU He-xin;TAN Hou-zhang;DU Yong-le;WANG Yi-bin(Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, Xi’an Jiaotong University, Xi’an 710049, China)

机构地区：[1]西安交通大学热流科学与工程教育部重点实验室

出　　处：《中国环境科学》2019年第7期2721-2729,共9页China Environmental Science

基　　金：国家重点研发计划(2016YFB0601504)

摘　　要：通过烟雾箱实验,研究了SO 2-NO 2-NH 3-H2O四元反应体系在气-粒转化过程中新形成颗粒物数浓度与粒径分布的变化.研究发现,SO2-NO2-NH3-H2O四元反应体系具有显著的成核能力,且其成核强度大,持续时间短.当SO2、NO 2浓度为200mg/m^3,NH 3浓度为12×10^-6时,反应体系的气溶胶总个数浓度在2min时达到峰值2.5×10^6cm^-3.缺少任一种气体均会使气溶胶成核强度下降.SO2、NO2及NH 3浓度分别为0的工况下气溶胶总个数浓度峰值分别下降了41.0%、83.6%及98.5%.在电厂污染气体排放浓度区间内,NO 2对气溶胶生成影响大于SO2.燃煤电厂控制NO x排放浓度对改善烟囱出口气溶胶数浓度更有效.在实验基础上,对颗粒物成核特性进行拟合,反应体系在气-粒转化过程中产生的新颗粒物总个数浓度及中值粒径与气态前体物浓度线性相关;采用布朗团聚模型对气溶胶成核后的团聚过程总个数浓度及粒径变化进行模拟计算,根据给定的燃煤电厂SO2、NO2、NH 3排放浓度,给出预测气溶胶颗粒成核速率、粒径分布及总个数浓度变化的方法.The variations in concentration and diameter distribution of newly formed particulate matter,during the gas-to-solid conversion of the SO2-NO2-NH3-H2O quaternary system,were experimentally investigated with the smog chamber in this article.This quaternary system had a significant capability of nucleation,and a large nucleation intensity in such a short duration.When both 3-6 of SO 2 and NO2 concentrations were 200mg/m^3 and NH3 concentration was 12×10^-6,the total concentration of aerosols in this system 6-3 reached a peak of 2.5×10^6cm^-3over two minute.Moreover,the nucleation strength of the aerosol would be reduced lacking in any one among three gases.Like this typical condition that SO2,NO2 or NH3 concentration was zero,the maximum concentration of aerosols decreased by 41.0%,83.6%and 98.5%,respectively.Within the concentration ranges of SO2,NO2 or NH3 emitted from coal-fired power plants,the NO 2 had a greater influence than SO2 on the formation and agglomeration of newly formed particles.Based on experimental results,the fitting curves for nucleation characteristics of particulate matters were made.A linear correlation was observed between the total number concentration of newly formed particles and median particle diameter,and gaseous pollutant concentrations.The Brown agglomeration model was adopted to simulate the changes in total number concentration and particle size distribution of aerosols after nucleation in the agglomeration process.Finally,a method was proposed for predicting the change in the particle size distribution and total number concentration of aerosol particles,based on the typical emission concentrations of SO2,NO 2 and NH3 from coal-fired power plants.

关 键 词：燃煤电厂 灰霾 气溶胶 烟雾箱 成核 团聚 

分 类 号：X515[环境科学与工程—环境工程]