Migration Characteristics Of Chlorine In Coal-fired Power Plants And Its Synergistic Treatment

Chlorine produced by coal combustion will cause serious corrosion to equipment in coal-fired power plants.The research on the migration characteristics and collaborative treatment of chlorine in coal-fired power plants is an important part of exploring the distribution and migration law of chlorine in various products of coal-fired power plants,and provides a reference for solving a series of problems caused by excessive chlorine concentration caused by chlorine release in coal-fired power plants.This paper takes three units in three coal-fired power plants in Anhui Province as the research object,according to the existing national standards,carries out industrial analysis and element analysis on raw coal used in coal-fired power plants,and explores the formation mechanism of chlorine in raw coal.The chlorine content of coal-fired power plant is analyzed to study the migration law of chlorine in coal-fired power plant,and the content of chlorine in various by-products is studied by mass conservation method.Taking the chlorine content in raw coal as the total chlorine,the collaborative treatment efficiency of pollutant control devices such as dust remover and desulfurization tower in coal-fired power plant is studied.Through the above research,this paper mainly obtains the following research results.(1)The chlorine content of 21 kinds of coal samples was analyzed.It is found that the chlorine content of Suzhou coal is the highest,followed by Huainan coal,and then Fengtai coal;the chlorine content of Yunnan coal is the lowest,and the chlorine content of Russian coal and Indonesian coal is higher than that of four coal producing areas in China.(2)Correlation analysis and P / CL mass ratio method were used to study the possible occurrence forms of chlorine in coal.It is found that chlorine in coal is not related to ash,but is inversely correlated with the content of fixed carbon in coal,that is,the content of chlorine in coal decreases with the decrease of fixed carbon content;there is no linear correlation between phosphorus content and chlorine content in coal;the ratio of P / CL further indicates that chlorine in coal does not exist in the form of chlorapatite and hydroxyapatite;the chlorine content in coal has no relationship with s content in coal In view of the fact that fluorine and chlorine often coexist in the form of isomorphism in minerals,there is no correlation between chlorine and fluorine in coal.(3)Through the analysis of chlorine content of coal-fired by-products in coal-fired power plants,it is found that the coal-fired power plants use medium and low chlorine coal,and the high chlorine content in raw coal does not mean that the chlorine content in the bottom ash is certain to be high.It is speculated that the occurrence form of chlorine in coal and the slagging form of raw coal after combustion may be different.There is no enrichment of chlorine in desulfurization gypsum.There is no enrichment of chlorine in fly ash.(4)The migration law of chlorine in coal-fired power plant and the synergistic treatment efficiency of pollutant control device in coal-fired power plant were investigated by mass conservation method.It was found that 1.17%-3.37% of chlorine remained in the bottom ash of three coal-fired power plants,that is,the chlorine released from coal combustion accounted for 96.63%-98.83% of the total chlorine.In the study of the influence of SCR denitration device on chlorine,it is found that before and after the denitration device,the change content of particulate chlorine is almost unchanged,but the chlorine in the form of HCl in the flue gas becomes less,and the concentration of Cl2 in the flue gas shows an upward trend.It is concluded that the denitration device in coal-fired power plant has no synergistic effect on chlorine treatment.In coal-fired power plants,part of chlorine adheres to the surface of fly ash or has complicated physical and chemical changes with chlorine.This part of chlorine is removed with the removal of fly ash.The chlorine content in fly ash accounts for 9.82%-15.99% of total chlorine in coal %The results show that the dust removal equipment has a certain synergistic treatment effect on chlorine in coal-fired power plant,and through the change of chlorine content in flue gas,the collaborative treatment efficiency of dust removal equipment for chlorine is basically consistent with the conclusion of mass conservation method.The wet desulfurization technology has a very high synergistic treatment efficiency for chlorine,accounting for 10.36%-17.00% of the total chlorine.The chlorine content in the desulfurization wastewater is the highest,accounting for66.46%-72.64% of the total chlorine in coal.That is to say,the wet desulfurization technology has a good synergistic treatment efficiency for chlorine in coal,and the collaborative treatment efficiency is 79.17%-88.11% %The results show that the wet desulfurization technology has a high synergistic treatment efficiency for chlorine in coal-fired power plants.In the end,0.822%-1.037% chlorine entered the atmosphere with the flue gas.