[Emission Characteristics of Chemical Composition of Particulate Matter from Coal-fired Boilers]

Samples of particulate matter from coal-fired boilers of different tons were collected in Lanzhou city, and the water-soluble inorganic ions, carbonaceous species, water-soluble organic compounds (WSOC) and polycyclic aromatic hydrocarbons (PAHs) were analyzed. The results showed that SO₄^2-, Cl^-, and Ca²⁺ were the most important water-soluble ions in the coal-fired boiler samples, accounting for 35.13%, 23.16%, and 22.20% of the total mass of water-soluble ions, respectively. The pyrolysis composition spectra of the carbonaceous species were similar among the coal-fired boilers, and organic carbon fraction (OC1, OC2, OC3, and OC4),and elemental carbon fraction (EC1, EC2, and EC3) accounted for 1.04%, 8.26%, 20.09%, 6.78%, 51.08%, 7.09%, and 5.66% of the total carbon (TC), respectively. EC1 had the highest content and was the most important carbonaceous species. The average ratios of WSOC/TC and WSOC/OC were 0.09±0.07 and 0.23±0.12, respectively, and the difference among the boilers of different tons was large. Phenanthrene (Phe), pyrene (Pyr), and benzene(k)anthracene (BkF) were the three main components of the PAHs, accounting for 16.69%, 11.93%, and 10.66% of the total PAHs, respectively. The particulate water-soluble ions, organic/elemental carbon aerosol (OCEC) and WSOC emitted from different tons coal-fired boilers were not significantly linearly related to the tonnage of the steam boiler, and low molecular weight PAHs decreased with the increase of tonnage of the steam boiler.