Study On The Change Characteristics Of Total Particulate Matter In Flue Gas From Coal-fired Power Plants Before And After Wet Desulphurization And Wet Electric Dust Removal Facilities

At present,energy consumption is dominated by coal in China,and coal would still play an important role in the future.As is known to all,the coal-fired power industry is one of the important coal resources.A large number of pariculate matters are generated and emitted in the production of power plants.In the atmospheric environment,these particles would experience some processes such as growing,aging,and depositing,then play a more important role in the explosive growth of PM_2.5 and increase the probability of haze weather.Therefore,it is necessary to improve the conversion characteristics and formation mechanism of particulate matters to control the emission of particles effectively.The particulate matters emitted by coal-fired power plants essentially includes filterable particulate matter?FPM?and condensable particulate matter?CPM?.At present,the research on the monitoring methods and emission characteristics of particulate matters has been relatively mature,but the research on the conversion characteristics and formation mechanism is still insufficient.This study constructed a sampling device independently for FPM and CPM,selected four ultra-low emission coal-fired power plants for sampling and analysis.Several characteristic factors of particulate matters,such as mass concentrations,inorganic water-soluble ions,and organic matters composition,have been comprehensively investigated before and after wet flue gas desulfurization?WFGD?and wet electrostatic precipitator?WESP?.Finally,a relatively complete characteristics of particle formation and transformation was obtained.This research showed that CPM and FPM in flue gas were removed effectively by WFGD and WESP,and the mass concentrations of FPM and CPM decreased significantly than that before the ultra-low emission reformation.But relatively speaking,the removal rate of FPM reached 69.39%-96.95%,resulting in CPM as the dominant position accounting for 57.74%-91.79%of PM_2.5 emissions.In addition,WFGD and WESP were more effective in removing organic component than inorganic component,crude particles than fine particles in FPM.However,there was no obvious regular in removing organic or inorganic component of CPM before and after WFGD and WESP.The determination of water-soluble ions showed that the inorganic solutions of TFPM and CPM were both acidic,and the mass concentration of cations was relatively lower.In the TFPM,the mass concentration of Cl^-was the highest,and the distribution of water-soluble ions was significantly affected by the ultra-low emission facilities.The WESP had a good effect of removing water-soluble ions.After WFGD without collaborative dust removal capability,the mass concentration of some cations increased significantly,such as Ca²⁺,SO₄^2-,K⁺,Na⁺,Mg²⁺.In the CPM,the highest mass concentration of water-soluble ion was the SO₄^2-.Most ions could be effectively removed by WFGD and WESP except SO₄^2-and NO₃^-in WESP,which indicated that the changes of acid system were closely related to the formation of CPM.The organic matters composition of particulate matters was abundant,covering alkanes,amides,alcohols,esters,ketones and phenol,etc.And the kind of alkanes and amides was relatively more abundant.Through qualitative measurement of organic components in TFPM and CPM,most of the organic compounds were distributed from C10 to C27.At same sampling power plant and sampling site,the organic matters composition of TFPM and CPM was similar,but it was defferent between different power plants.The reasons may be attributed to the difference between the types of coal,the burning conditions,or the flue gas purification facilities,which all had some significant effects on organic components.