燃煤电厂湿法脱硫对细颗粒物的脱除特性

摘要

Size-segregated fine particulate matters were sampled by Dekati Gravimetric Impacter (DGI) before and after wet flue gas desulfurization (WFGD) in four coal-fired units.The variations of mass concentration,size distribution and elemental composition of the fine particulate matters were analyzed.The results showed that peak values of fine particulate matters concentration was in the range of 0.20-0.40 μm before WFGD among the four units,while they decreased slightly to 0.20-0.30 μm after WFGD.After the process of wet desulfurization,the mass concentrations of PM2.5,PM1,PM0.5 and PMo.2 increased by 13.28％,19.57％,28.79％ and 33.51％,respectively.The mass concentration of Si and Al reduced with the decrease of the particle size both before and after desulfurization,while Fe showed the opposite tendency,indicating its enriching property.After WFGD,the mass concentration of Si and Al decreased to varying degrees,while the mass concentration of Ca increased significantly from 18.86-51.47 iμg/m3 to 41.87-84.83 μg/m3.After WFGD,the fraction of Si and Al,as the main elements in PM2.5,decreased from 59％-72％ to 43％-59％,while Ca in PM2.5 showed the opposite trend,increasing from 8％-13％ to 17％-26％.%应用DGI承重撞击器对四台燃煤机组湿法脱硫前、后细颗粒物进行采集,分析细颗粒物的粒径分布、元素组成以及脱硫系统的脱除效率.结果表明:脱硫前细颗粒物粒径峰值出现在0.20～0.40μm处,脱硫后峰值出现在0.20～0.30 μ,m处.经过湿法脱硫系统后P(PM2.5)、ρ(PM1)、ρ(PM0.5)、ρ(PM02)出现不同程度的增长,平均增长率分别为13.28％、19.57％、28.79％、33.51％.分粒径颗粒物中ρ(Si)、ρ(Al)在脱硫前、后均随着颗粒物粒径的减小呈递减趋势,并且脱硫后ρ(Si)、ρ(Al)均有不同程度的降低,ρ(Fe)随颗粒物粒径的减小呈增加趋势,表现出一定的富集特性;湿法脱硫后Ca在PM1中的质量浓度出现明显的增长,ρ(Ca)由18.86 ～51.47 μg/m3增至41.87 ～ 84.83 μg/m3.Si、A1是PM2.5中的主要元素,经过湿法脱硫后ρ(Si)、ρ(A1)由59％ ～ 72％降至43％ ～59％;而Ca在PM25中表现出相反的变化趋势,ρ(Ca)由8％～13％升至17％ ～ 26％.