Experimental Study On Oxidation-Absorption Of SO₂,NO_x And Hg⁰ In Flue Gas Based On Compound Absorbent

With the increasing emphasis on ecological and environmental protection,the emission indicators of various pollutants have become more and more stringent.Therefore.methods for removing multiple pollutants need to be further developed and improved.The traditional desulfurization,denitration and mercury removal methods are limestone/gypsum desulfurization,selective catalytic reduction denitrification,and activated carbon adsorption demercury.However,this hierarchical treatment method has large equipment footprint and high cost,and it is easy to cause ammonia to escape.And other additional pollution problems,so the process route based on the integrated removal of multiple pollutants was further studied.In this paper,based on a large number of literature references,using a self-made bubble reactor liquid phase oxidation method,a large number of oxidants such as Na2S2O8,H2O2,NaClO2,NaClO,etc.,supplemented by absorbent Ca(OH)2,are used for integrated desulfurization,denitration and mercury removal.According to the respective removal efficiency,chemical cost,and the advantages and disadvantages of the reaction process,the compounding research is carried out,and the Na2S2O8/H composite oxidation absorbent is finally determined as the research object,and under the same influencing factor experiment,it is determined that 0.6M:0.2 M is the most economical and efficient ratio.Then the best experimental conditions for this system are found through single factor conditions,that is,the temperature is 60℃,the pH value is 10,and the gas velocity is 1L/min.When the initial concentration of SO2,NO,and Hg0 are 2000mg/m3,500mg/m3,80μg/m3,the desulfurization,denitrification and mercury removal efficiencies reached 93.2%,83.2%,and 67.3%,respectively.In addition,the effects of flue gas components NO,SO2,coexisting gases O2,CO2,and additive ions Cl-,SO42-,CO32-ions on the integrated removal efficiency are also studied.The results show that the moderate increase in NO and SO2 concentrations and Appropriate addition of Cl-and SO42-can promote the efficiency of mercury removal to a certain extent.Characterize the reactants before the reaction and the absorbent after the reaction by XRD,XPS,ion chromatography and other characterization methods.It is deduced that the main role in the system is SO4·-,OH,O2·-and other strong oxidizing free Base,and proved the synergy between different oxidants.According to the XRD pattern after the reaction,the main substance is CaSO4,and the XPS pattern shows NO3-SO42-、CO32-、Hg2+ plasmas.Ion chromatography qualitatively detects NO3-and SO42-.Quantitative analysis shows that the N atom material is conserved.It can be concluded that NO is oxidized to NO3-,SO2 is oxidized to SO42-.Hg0 is oxidized to Hg2+.