| Through ELPI (electrical low-pressure impactor) based dilution sampling system, the emission characteristics of PM10 and PM2.5 was studied experimentally at the inlet and outlet of dust catchers at eight different coal-fired industrial boilers. Results showed that a peak existed at around 0.12-0.20 μm of particle size for both number size distribution and mass size distribution of PM10 emitted from most of the boilers. Chemical composition analysis indicated that PM2.5 was largely composed of organic carbon, elementary carbon, and sulfate, with mass fraction of 3.7%-21.4%, 4.2%-24.6%, and 1.5%-55.2% respectively. Emission factors of PM10 and PM2.5 measured were 0.13-0.65 kg·t-1 and 0.08-0.49 kg·t-1 respectively for grate boiler using raw coal, and 0.24 kg·t-1 and 0.22 kg·t-1 for chain-grate boiler using briquette. In comparison, the PM2.5 emission factor of fluidized bed boiler is 1.14 kg·t-1, much her than that of grate boiler. Due to high coal consumption and low efficiency of dust separator, coal-fired industrial boiler may become the most important source of PM10, and should be preferentially controlled in China. |
