Experimental Study On Integrated Desulfurization And Denitrification Of Sintering Flue Gas Based On Oxidation Method

The iron and steel metallurgy industry is not only an important basic industry of my country’s national economy,but also the largest polluter after the thermal power industry,and one of the sources of increasing environmental load.Therefore,the state has continuously increased the types of air pollutants in the iron and steel industry,and the emission standards,especially the emission requirements of SO₂ and NO_x,have become increasingly strict.At present,the mainstream"one-to-one"flue gas treatment method not only covers a large area,but also has high investment and operating costs,and will also bring huge environmental protection costs to iron and steel enterprises.Therefore,for the sintering process that emits the most air pollutants in the iron and steel metallurgical industry,it is of great practical significance to research and develop a new technology integrating desulfurization and denitrification with high efficiency and energy saving.In this paper,the sintering flue gas is taken as the research object,and the effect of simultaneous desulfurization and denitrification by NaClO₂ wet oxidation method is firstly studied by using a bubbling reactor,as well as the effect of absorption liquid temperature,initial p H value of absorption liquid,simulated flue gas composition and flue gas flow on desulfurization and denitrification.effect on efficiency.The experimental results show that the higher the initial concentration of NaClO₂absorption solution,the higher the simultaneous removal rate of NO and SO₂,the absorption solution is more conducive to the removal of NO under acidic conditions,but when the initial p H value of the absorption solution is particularly small,it will inhibit NO and SO₂.SO₂ removal.The initial concentrations of O₂ and CO in the sintering flue gas have no significant effect on the simultaneous desulfurization and denitrification efficiency of the NaClO₂ wet oxidation method.There is a synergistic effect and a competitive relationship between NO and SO₂.When the initial concentration of NaClO₂ in the absorption solution is 0.02 mol/L,the initial p H value of the absorption solution is 4,the reaction temperature is 40°C,the initial concentration of NO is 400 ppm,the initial concentration of SO₂ is 400 ppm,the initial concentration of O₂ is 16%,and the initial concentration of CO is 400 ppm.When the flue gas flow rate is 3500 ppm and the flue gas flow rate is 1 L/min,the desulfurization and denitrification effect is the best at the same time,the average removal rate of NO within 30min is 100%,and the removal rate of SO₂ is 98.98%.This paper also summarizes four reaction equations in the NaClO₂ wet simultaneous desulfurization and denitrification process,and calculates theΔG°,K°andΔH°of the reaction through the laws of thermodynamics.The calculation results show that the reaction standard Gibbs functionΔG°under different conditions is far less than-40 k J/mol,and the reaction standard equilibrium constant K°is far greater than 0,so it can be judged that the four reactions can proceed forward.And the reaction limit is very deep.Acidic conditions are more conducive to the reaction of NaClO₂ wet denitration,which is consistent with the experimental results;theΔH°of the four reactions are all far less than 0,and the reactions are all exothermic reactions.The experimental results are consistent.Finally,an exploratory study is carried out on whether the sintering flue gas can be simultaneously desulfurized and denitrified by oxidation in the dielectric barrier（DBD）arrester.The experimental results show that when the O₂ concentration in the simulated flue gas is 0,a reduction reaction occurs in the DBD arrester,the desulfurization rate is only 3%;the NO removal rate increases with the increase of the input voltage,and the highest can reach 91.06%;when simulating the sintering flue gas,the DBD discharge process will occur due to the high oxygen content of the sintering flue gas.Oxidation reaction occurs,Oxidizes SO₂ and NO to SO₃ and NO₂.With the increase of the input voltage,the SO₂ removal rate increased continuously,and the highest energy reached 20.71%;the NO₂ concentration increased first and then decreased,and the highest reached 283 ppm.