| Atmospheric particulate matter emissions from coal-fired power plant were the main source of air pollution. Especially, the inhalable particulate (PM10) emissions during coal combustion was prominent. Inhalable particulates were not only harmful to human health and atmospheric visibility, but also could present in the atmosphere for a long time to affect the regional air quality by long-distance transmission. Currently, studies on concentration measurement and particle size distribution, chemical composition of particulate matter from coal-fired power plant based on field measurement are relatively shortage. Therefore, it’s scientific and practical significan-ces to investigate the emission characteristics and environmental impact analysis of the Particulate Matter from coal-fired power plant.This study selected a coal-fired power plant in Peking, whose scale of production capacity and pollution control facilities were relatively typical, as the research object to carry out on-site testing. The test included:Dust and particulate matter of each size was sampled in the entrance and exit of the dust cleaning equipments, such as ESP and WFGD, using low pressure impactor (LPI). Particulate matter samples were weighed, and chemical component analysis of PM was carried out subsequently. Dust emission concentration, the mass concentration and chemical composition of the particle size distribution characteristics were obtained in the studied boiler, and emission factors of the different size particles were established as well. According to the above, simulation analysis of the atmospheric particulate matter pollution dispersion of coal-fired power plant was conducted by AERMOD atmospheric dispersion model.(1) The research indicated that the emission concentration of dust and PM10, PM2.5, PM1of coal-fired boilers were below the GB emission standard limit. So electrostatic precipitator (ESP) and wet flue gas desulfurization device (WFGD) could meet the particulate matter emission control requirements of the coal-fired power plant. Particle size distribution and segregated particulate concentration was measured in the entrance and exit of the ESP and WFGD, the size-dependent capture efficiencies for particulate matters on the dust cleaning equipments were derived in this thesis. It indicated that there was a decreasing trend shown in the size-dependent capture efficiencies asthe particle size of the particulate matter turn smaller, while the ESP capture efficiencies of PM10were showing a "V" shaped variation.(2) A similar bimodal distribution of PM10with a small and a large mode at0.1p.m and4μm, respectively, was obtained in upstream of ESP, while at0.1μm and2.5μm in downstream of ESP and WFGD. The phenomenon that peak of submicron region was not obvious indicatedthat Coalescence-crushing process was the primary mechanism of the formation of particulate matter. Based on the proportion variation of PM2.5accounted for PM10, it concluded that the particulate matter emitted from coal-fired power plant mainly was PM2.5. Moreover, according to the concentration of particulate matters, the emission factors of TSP, PM10, PM2.5were established in this moment. The study provided the bases for researching and controlling the emission of particulate matter from the coal-fired power plant.(3) Chemical composition analysis indicated that inorganic elements, such as Ca, Si, Al, Fe, S, water-soluble inorganic ions, such as Ca2+, SO42", NO3-, and organic matter were the main component of PM10from coal-fired boiler. The concentration ratios of the same chemical composition in PM2.5and PM10were more than70%, indicating that the chemical composition was relatively more enriched in fine particulates. The mass size distributions for minor elements showed a bimodal mode with peaks at1-4μm, and trace elements such as Cr, Cu, Zn, Pb showed a single mode with peaks at1-2.5μm. The mass size distribution of the water-soluble inorganic ions had a peak in the submicron region substantially, and a peak at1～2.5μm in the coarse region. Water-soluble inorganic ions were mainly formed by gas-phase reaction and particle collision, broken process.(4) Based on the field measurements, source strength of atmospheric particulate matter emissions from coal-fired power plant was obtained. The average maximum ground concentration by hour and day, occurrence time and location, and the concentration contributions to environmentally sensitive points were quantified after model simulation using AERMOD. The results indicated that the emission of coal-fired power plant-TSP, PM10, PM2.5, lay a little impact on the regional environment air quality. |
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