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Emission Characteristics of Particulate Matter from Two Ultralow-Emission Coal-Fired Industrial Boilers in Xi’an, China

Ruan, Renhui, Xu, Xinwei, Tan, Houzhang, Zhang, Sicong, Lu, Xuchao, Zhang, Peng, Han, Ruiwu, Xiong, Xiaohe
Energy & fuels 2019 v.33 no.3 pp. 1944-1954
aerodynamics, air pollution control, alkalinity, boilers, calcium, cations, coal, emissions factor, fabrics, flue gas desulfurization, fluidized beds, ion exchange chromatography, particulates, pollution, power plants, scanning electron microscopy, sodium, sulfates, water solubility, China
The air pollution control devices (APCDs) of industrial boilers in China are backward compared to coal-fired power plants, enhancing serious particulate matter (PM) pollution. The PM removal characteristics of APCDs from two industrial boilers [a circulating fluidized bed (CFB) boiler and a chain-grate boiler (CGB)] with ultralow emission were studied in this research. PM was sampled at the inlet/outlet of the fabric filter (FF), wet flue gas desulfurization (WFGD), and wet electrostatic precipitator (WESP) through the cyclone-filter sampling system. The morphology and water-soluble ions of PM were analyzed by scanning electron microscopy (SEM) and ion chromatography (IC). The results show that the concentrations of PM with aerodynamic diameters of ≤1, 2.5, and 10 μm (PM₁, PM₂.₅, and PM₁₀, respectively) at the precipitator inlet of CFB are much higher than those of CGB. The PM removal efficiency of FF in the CFB boiler is 98.12–99.56%, while that of CGB is only 90.0–93.6%. WFGD can increase the alkalinity of PM, and the combined PM removal efficiency of WFGD coupled with WESP is 46.75–62.77%. SO₄²– is the most abundant water-soluble anion in PM, while the water-soluble cations are richest in Ca²⁺ and Na⁺. After ultralow-emission retrofit, the emission factors (EFs) of PM₁₀, PM₂.₅, and PM₁ are 0.028–0.033, 0.025–0.028, and 0.014–0.017 kg/tonne, respectively. The percentage of PM₂.₅ in PM₁₀ is 85.2–88.6% at the WESP outlet. These results are significant to the understanding of emission characteristics for atmospheric fine particles from industrial boilers with ultralow emission in China.