Studies on Characteristics of Size Distribution and Heavy Metal Content Distribution of Superfine Particles from Coal-fired Boiler

摘要

A seven-stage impact dust classifiers was used to sample fine participates of fly ash in the entrance and exit of a cyclone dust catcher. The aerodynamic diameters of sampled fly ash ranged from 1.3 μm to 14.7 μm. The experimental results showed that in the exit of the cyclone dust catcher, the mass radios of PM2.5 and PM10 in total fly ash were 82.8% and 26.5% respectively. It demonstrated that the mass ratios had increased markedly in contrast to those of the dust catcher entrance. The efficiency of dust catcher was low for fine fly ash, which could be illustrated by the collection efficiencies of PM2.5 and PM10 being 3% and 47.3% respectively. Furthermore, the heavy metal contents of Pb, Cd, Cu, Zn, Ni and Cr in the sampled fly ash were determined by AAS (Atomic Absorption Spectrophotometry). Consequently, we reached a preliminary conclusion of enrichment principle of some hazardous heavy metal contents in fine particulates.