| Coal is widely used in citizens'daily life due to its large quantity,extensive distribution and use without further treatment.This has resulted in the higher pollutant emission of unit mass than industrial process.Thus,it is of great significance to study the emission of fine particulate matter(PM2.5)and its chemical components in control of pollution,energy conservation and emission.Bituminous coal,anthracite and honeycomb briquette in districts,such as Shanxi,Henan,Anhui and Hubei,were studied to analyze the characteristics of coal quality such as moisture,ash,volatile component,fixed carbon and calorific value.Controlled combustion-dilution sampling integrated device was designed to obtain emission factors of PM2.5,carbon components,water-soluble ions and heavy metal elements from civil coal combustion.The emission characteristics were analyzed.The influence of combustion temperature on PM2.5 and chemical components in civil coal combustion was discussed.The components of PM2.5 were screened,and the source spectra of PM2.5 and chemical components from civil coal combustion in Shaanxi and Henan were established.Innovations have been made in the combustion-dilution sampling device and screening methods of PM2.5 identification components.The main research conclusions are as follows:?1?The self-designed controllable combustion-dilution sampling integrated device is used for the collection of PM2.5 samples of civil coal-fired combustion.This device could be used to overcome errors caused by direct sampling process and to study the emission characteristics of pollutants under different combustion conditions of civil coal.?2?The analysis results of coal quality showed that the properties of different types of coal vary greatly in different areas.For the studied 12 kinds of civil coals,the moisture content changed from 0.78%to 76.89%;ash content from high to low in order:honeycomb coal>anthracite>bituminous coal,the result showed that ash content was negatively correlated with calorific value?r=0.945?;the collected TC content of civil coal was very close to the calculated FCad content,and the former was slightly higher than the latter;TC was positively correlated with FCad?r=0.94?;the analysis results of coal quality with the same kind of civil coal burned in the same area also differed.?3?PM2.5 emission factors of different types of civil coal combustion presented significant differences and decreased with the increase of combustion temperature.The PM2.5 emission factor of bituminous coal combustion was significantly higher than that of anthracite and honeycomb coal.The PM2.5 emission factor of bituminous coal ranged from 12.95g·kg-1 to 20.82g·kg-1,that of anthracite ranged from 1.73g·kg-1 to 3.51g·kg-1,and that of honeycomb coal ranged from1.15g·kg-1 to 6.21g·kg-1.Emission factors of PM2.5 for bituminous coal and anthracite coal dropped 65.1%and 90.8%respectively,with the combustion temperature increasing from 550?to 750?.?4?Carbonaceous components were the main constitution of PM2.5 in flue gas of civil coal combustion.TC accounted for 28.3%to 49.2%of PM2.5.TC emission factor of bituminous coal is the highest,ranging from 6368.43mg/kg to8756.54 mg·kg-1,while that of anthracite and honeycomb coal ranged from488.83mg·kg-1 to 2453.00mg·kg-1.With the increase of combustion temperature,the emission factor of TC decreased.As for bituminous coal,EC is the main constitution in PM2.5,because the amount of EC1 and EC2 exceeds 80%that of TC,while OC is the main constitution in PM2.5 of anthracite and honeycomb coal.Principal component analysis and factor analysis were used to select the marked components of bituminous coal as EC1 and EC2.The marked components of anthracite and honeycomb coal were OC1.The results showed that combustion of bituminous coal contributed a lot to inorganic carbon,while that of anthracite and honeycomb coal contributed a lot to organic carbon.?5?The water-soluble ion emission factors in PM2.5 of different types of civil coal combustion were significantly different,and decreased with the increase of combustion temperature.SO42-is the most water-soluble ion in PM2.5 of civil coal combustion,and the amount of different ions was presented in order:F-<NO3-<Cl-<SO42-.Emission factor of SO42-of bituminous coal in PM2.5(average value 422.88mg·kg-1)was the largest,129 times than that of F-emission factor(average value 3.27mg·kg-1),and 1.89 times than that of honeycomb coal(average value 223.35 mg·kg-1).Emission factors of F-,Cl-,NO3-and SO42-water-soluble ions in PM2.5 from civil coal combustion decreased with the increase of combustion temperature.The SO42-emission factors in PM2.5 of bituminous coal and anthracite combustion decrease by 60%and 10%respectively with the combustion temperature rising from 550 to650?.Principal component analysis was used to screen SO42-and NO3-as the marked components of water-soluble ions in PM2.5 of civil coal combustion.?6?The emission factors of heavy metals?such as Cr,Mn,Ni,Cu,Zn,As,Cd and Pb?in PM2.5 in different regions are quite different.As a whole,the emission factors of As,Pb,Zn and Cr are higher.The principal component analysis method was used to select Pb,Cr and As as the marker components of heavy metals in PM2.5of bituminous coal combustion and Pb,Cr,Ni and Zn as the marker components of heavy metals in PM2.5 of anthracite and honeycomb coal combustion.?7?The source composition spectra of 31 components in PM2.5 of bituminous coal,anthracite and honeycomb coal combustion,such as carbon,water-soluble ions and heavy metals,were constructed.The mass reduction percentage of PM2.5chemical components ranged from 50.14%to 84.80%.The source spectrum constructed in this study can provide support of scientific basis and data for the analysis of atmospheric sources and the formulation of controlling pollution. |
PDF Full Text Request