Study On The Removal And Formation Characteristics Of Particulate Matters Of The Coal-fired Power Plant

Air pollution control is one of the important part in China environmental pollution control, and more and more attentions are given to PM2.5 in the air pollution control in recent years. The fine particulate matter in the atmosphere is mainly from the flue gas emitted from fuel combustion. The main energy supply in our country is coal, and more than 70% annual energy consumption comes from coal consumption. Therefore, the research of the formation characteristics and removal of the particulate matters will be significant.According to the flue gas conditions of one coal-fired power plant in Chongqing, the flue gas properties and the formation characteristics of fine particulate matters are respectively researched under different combustion conditions of Chongqing coal and Xinjiang coal. The effects caused by the WFGD of particulate matters removal and the change of elemental content of Ca, S, As have been researched in the experiments. Moreover, The removal effects caused by the WESP of particulate matters, OC/EC and the change of elemental content of Pb, Cu, Cd, Cr have also been researched.The researches have revealed some laws. The formation characteristics of particulate matters have been affected by the size of coal powder and the coal combustion temperature. The minimum concentration of particulate matters emitted from Chongqing coal combustion is 35547.79 mg / m3, and the combustion temperature is 950℃ and the mesh number ranges from 60 to 120. The minimum concentration of particulate matters emitted from Xinjiang coal combustion is 8348.62 mg / m3, and the combustion temperature is 850℃ and the mesh number ranges from 120 to 170. With the increasing of combustion temperature, the hydrates, the ammoniums and the nitrates will be decomposed, and the main compounds are the sodium salt and the calcium salt. The surface morphology of the particulate matters have been affected by the size of the coal powder and the coal combustion temperature. With the increasing of combustion temperature, the surface morphology of the particulate matters will be gradually transformed from the irregular shape to the spheroidal. With the mesh number of the coal powder increasing, the number of the fine particulate matters will be increased gradually.The removal effect of different size fractions is different in the WFGD. With the size of the particulate matters decreasing, the removal efficiency of the particulate matters will be worse because of the ill contact between the vapor and the particulate matters. And the maximum removal efficiency of PM5 is 37.7%. On the contrary, the efficiency is 62.3%. The main factors which can affect the particulate matters removal efficiency are the liquid-gas ratio, the flow rate, the atomization of the liquid and the contact-time between the slurry and the particulate matters.According to the research of the WESP, the removal efficiency of the PM5 is remarkable, and the maximum removal efficiency of PM2.5 is 88.1%. However, the maximum efficiency of the particulate matters larger than PM5 is 61.1%. And the maximum removal efficiency of the particulate matters larger than PM10 is 8.1%. The maximum removal efficiency of total carbon and the poisonous and heavy metal elements, such as Pb, Cu, Cd and Cr, is 88.3%. The main factors which can affect the particulate matters removal efficiency by the WESP are the fraction-mass, the flow rate, the electric field strength and the size of the particulate matters.