燃煤过程矿物质形态对亚微米颗粒释放的影响

EFFECT OF THE MINERAL FORM ON EMISSION OF SUBMICRON PARTICLE DURING COAL COMBUSTION

为研究燃煤过程中亚微米颗粒的形成机理,选取了三种烟煤在沉降炉内燃烧,用X射线荧光光谱和透射电子显微镜能量色散谱仪联用对煤和亚微米灰中的矿物质进行分析,研究内生态和游离态的矿物质的转化过程.结果表明,与碳结构的结合方式决定了矿物质向亚微米颗粒的转化.游离态矿物质很少转化成亚微米灰颗粒,但其组成却影响着Si和Al的转化.

Coal ash is China＇s largest single source of solid waste, of which the submicron fly ash are particularly troublesome, since they are enriched with the toxic heavy metals and have a high probability of escaping common air pollution control devices. To investigate its formation mechanisms during coal combustion, the interaction between different minerals in the coal and its effect on the formation of the submicron fly ash were studied. Three bituminous coals were combusted in the drop tube furnace and the produced ash was collected and separated by low-pressure impaetor. The X-ray fluorescence（XRF）and the transmission electron microscopy- energy dispersion spectroscopy（TEM-EDS） are used to characterize the minerals in the coal and the submicron ash. With respect to the influence of the modes of occurrence of elements, it was investigated from the consideration of the mineral association in parent coals, i. e. , included or excluded particles. According to the experimental results, it was concluded that the association of inherent minerals with the carbonaceous matrix was primarily important for determining their transformation into submicron ash. The excluded minerals barely contribute to submicron ash formation. The transformation behaviors of Si and Al were possibly affected by the amount of excluded in raw coals.