Investigation on condensable particulate matter emission characteristics in wet ammonia-based desulfurization system

Particulate matter emissions from ammonia-based wet flue gas desulfurization(AmmoniaWFGD)systems are composed of a filterable particulate matter and a condensable particulate matter(CPM)portion.However,the CPM part has been ignored for a long time,which results in an underestim ation of the aerosol problems caused by Ammonia-WFGD systems.In our research,the characteristics of the CPM that emits from an Ammonia-WFGD system are investigated experimentally for the first time,with the US Environmental Protection Agency Method 202 employed as the primary measurement.The influences of some essential desulfurizing parameters are evaluated based on the experimental data.The results show that CPM contributes about 68.8%to the total particulate matter emission.CPM consists mainly of ammonium sulfates/sulfites,with the organic part accounting for less than 4%.CPM is mostly in the submicron fraction,about 71.1%of which originates from the NH3-H2O-SO2 reactions.The appropriate adjustments for the parameters of the flue gas and the desulfurizing solution can inhibit CPM formation to different extents.This indicates that the parameter optimizations are promising in solving CPM emission problems in Ammonia-WFGD systems,in which the pH adjustment alone can abate CPM emission by around 49%.The opposite variations of the parameters need attention because they can cause tremendous CPM emission increase.

Suggestion on further strengthening ultra-low emission standards for PM emission from coal-fired power plants in China

China has established the largest clean coal-fired power generation system in the world by accomplishing the technological transformation of coal-fired power plants(CFPPs)to achieve ultra-low emission.The potential for further particulate matter(PM)emission reduction to achieve near-zero emission for CFPPs has become a hotspot issue.In this study,PM emission from some ultra-low emission CFPPs adopting advanced air pollutant control technologies in China was reviewed.The results revealed that the average filterable particulate matter(FPM)concentration,measured as the total particulate matter(TPM)according to the current national monitoring standard,was(1.67±0.86)mg/m^(3),which could fully achieve the ultra-low emission standard for key regions(5 mg/m^(3)),but that achieving the near-zero emission standard was difficult(1 mg/m^(3)).However,the condensable particulate matter(CPM),with an average concentration of(1.06±1.28)mg/m^(3),was generally ignored during monitoring,which led to about 38.7%underestimation of the TPM.Even considering both FPM and CPM,the TPM emission from current CFPPs would contribute to less than 5%of atmospheric PM_(2.5) concentrations in the key cities and regions in China.Therefore,further reduction in FPM emission proposed by the near-zero emission plan of CFPPs may have less environmental benefit than emission control of other anthropogenic sources.However,it is suggested that the management of CPM emission should be strengthened,and a national standard for CPM emission monitoring based on the indirect dilution method should be established for CFPPs.Those measurements are helpful for optimal operation of air pollutant control devices and continuously promoting further emission reduction.