A 660 MW unit of an ultra-low emission coal-fired power plant in the Beijing-Tianjin-Hebei area was chosen for this study. The particulate matter was sampled with a Dekati low-pressure impactor (DPLI) at the inlet and outlet of flue gas cleaning devices including selective catalytic reduction (SCR), low-low temperature economizer (LLTe), electrostatic precipitator (ESP), wet flue gas desulfurization (WFGD), and wet electrostatic precipitator (WESP). A filter sampling system was also used at the inlet and outlet of the WFGD and WESP. The removal efficiencies of PM1, PM1-2.5, and PM2.5-10 from different flue gas cleaning devices were obtained after ultra-low emission modification. The results show that SCR increases the mass concentration of fine particulates and PM1 by 52.11%. The LLTe improves the removal efficiency of the ESP, especially for particles with a range of 0.1-1 μm. The high-efficiency WFGD removes both SO2 and particulates, but it increases PM1. The mass concentration of PM1 increases by 59.41% and the water-soluble Mg2+, Cl-, and SO42- in PM10 increases. The WESP has a high removal efficiency with respect to PM1, PM1-2.5, and PM2.5-10 and can further reduce the dust concentration. Based on an ultra-low emission reform, the final PM10 emission of this 660 MW unit is 2.04 mg·m-3.
Keywords: PM; coal combustion; flue gas cleaning device; ultra-low emission; water-soluble ion.