Emission characteristics of PM₁₀ from coal-fired industrial boiler

Through ELPI (electrical low-pressure impactor) based dilution sampling system, the emission characteristics of PM₁₀ and PM_2.5 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 PM_2.5 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 PM_2.5 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 PM_2.5 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.