燃煤排放可吸入颗粒物的显微结构与物质组成研究

Microstructure and composition of inhalable particulate matter (PM_(10)) from coal-fired power plants in Southwest China

对我国西南地区三个火电厂排放的可吸入颗粒物(PM_(10))的显微结构、矿物和化学组成等的研究表明,在PM_(10)中,随着粒径的减小,非球形颗粒的比例增加;同原状飞灰相比,PM_(10)以实心结构为主,多孔和空心结构较少;场发射扫描电子显微镜下,多数PM10颗粒的表面并不光滑,而是布满了次级微细颗粒;PM_(10)的物相组成与燃煤煤种密切相关,小龙潭电厂PM_(10)主要矿物包括石英、石灰、石膏和赤铁矿,而贵阳电厂PM_(10)则以莫来石和石英为主;据单个PM_(10)颗粒化学组成,将PM_(10)分为硅质、铁质、Ca-铝硅质、Fe-铝硅质、Ca-Fe-铝硅质和硫酸钙六种颗粒类型;从不同采样点PM_(10)元素组成看,从静电除尘器(ESP)前到ESP,PM_(10)化学成分变化不大,到ESP后,元素Fe、Ca、Mg和Al的含量急剧减少,而Na的含量则迅速增高。

The microstructure, mineral phase and chemical composition of inhalable particulate matter （PM10） from three coal-fired power plants in Southwest China were studied by two types of scanning electron microscope （SEM）, electron probe, X-ray diffraction （XRD） and inductively coupled plasma mass spectrometer （ICP-MS）. The results indicate that the number of non-spherical particle increases with decreasing grain size of PM10. There are more solid spheres and less porous and hollow spheres in PMlo compared with original fly ash particles. The surface of PM10 is normally coated with a layer of ultra-fine particles. The main minerals of PM10 from Xiaolongtan power plant include quartz, lime, gypsum and hematite, but mullite and quartz are the main crystalline phases of PM10 from Guiyang power plant. Six types of single particle, namely, silicon, ferruginous, Ca-aluminosilicate, Fe-aluminosilicate, Ca-Fe-aluminosilicate and calcium sulfate were identified according to their chemical composition. From electrostatic precipitator （ESP） inlet to ESP, the main element contents of PM10 have little variety, however, the contents of Fe, Ca, Mg and Al decrease significantly and the content of Na increases markedly on ESP outlet.