Experiment study on production and emission characteristics of PM_2.5 from industrial boilers

The emissions of PM_2.5 in two bituminous coal-fired industrial boilers in Harbin were investigated by using Electric Low Pressure Impactor (ELPI). The results showed that the curves of particles number and mass size distributions of PM_2.5 presented one single peak. The peak of the particles number appeared between 0.12 μm and 0.2 μm, mainly submicron particles formed by vaporization-condensation of mineral matter and soot particles transformed from unburnt volatiles. The peak for mass concentration appeared at 0.32 μm, mainly submicron particles produced by soot and super-micron particles formed by residual ash particles. Meanwhile, it was found that cyclone and wet scrubber had a significant effect on the removal of PM_2.5, and the removal efficiency of PM_2.5 for cyclone and wet scrubber combined dust was higher than that for a single wet srcubber. The wet flue gas desulfurization (WFGD) system also decreased PM_2.5 obviously. This was because the demister could not remove all the small droplets, a big number of solid particles and water-soluble substances in droplets were dried or crystallized, resulted in the number concentration of PM_0.32 increased and the PM_0.32~2.5 reduced, with the total mass concentration also reduced.