Influencing Factors Of SO₂/SO₃ Conversion Rate In SCR Catalytic Process

Selective catalytic reduction denitration technology?SCR?is still the most widely used,most mature technology flue gas denitrification technology,while the widespread application of SCR denitration also brought a series of problems,of which SO₃ because of its harm,not easy Many features such as detection and absorption have become prominent issues in recent years.When the SO₃ in the flue gas reaches a certain concentration,it combines with water to generate sulfuric acid vapor to increase the dew point of the flue gas and cause corrosion of the equipment.Studies have shown that sulfuric acid aerosol is one of the causes of haze and can form fine particles in the atmosphere?PM2.5?cause air pollution.However,the main source of SO₃ in coal-fired power plants is the conversion of SO₂ in flue gas.The"Emission Standard of Air Pollutants for Thermal Power Plants"issued by China in 011 clearly stipulates that the limit of nitrogen oxides emission of newly built power plants is 100 mg/m³,The generation mechanism of SO₃ is more and more important.Therefore,it is of great significance to study the factors of transformation between SO₂and SO₃.In this paper,the factors influencing the conversion of SO₃ in SCR catalytic denitrification process are studied.The effects of each component of flue gas and SCR catalyst on the conversion of SO₂/SO₃ are mainly discussed,which are shown as follows:the improvement of working conditions and the optimization of catalyst structure SO₃ production provides a theoretical support.The main results are as follows:1,the amount of SO₂ in both simulated flue gas and working condition flue gas is much less than that of O₂,and the conversion of SO₂/SO₃ remains stable within the range of 0.90%-1.00%under the condition of sufficient oxygen.The change of oxygen content SO₂/SO₃ conversion almost no effect.NH₃ can promote the oxidation of SO₂/SO₃ obviously.When the NH₃ in the flue gas reaches a certain amount,the conversion will obviously increase,even up to double the standard value of conversion.Therefore,the flue gas should be controlled NH₃ content,to avoid the increase in the content of NH₃ to cause SO₂/SO₃ conversion rate increases.NO is not involved in the catalytic oxidation reaction of SO₂ because of its stable chemical nature,SO it does not have much effect on the conversion rate.NH₃ can promote the oxidation of SO₂.However,when NH₃ and NO both coexist and NH₃content is lower than NO,NO can inhibit NH₃ to a certain extent,thus preventing NH₃ from catalyzing the oxidation of SO₂.However,when NH₃ accumulates to a certain amount and is greater than the amount of NO,NH₃ will continue to promote the oxidation reaction process of SO₂ to increase the conversion rate.2,TiO₂ as the main component of the catalyst,a large share of the quality and catalytic effect is limited,by reducing the mass fraction of TiO₂ to reduce the conversion rate of the method needs further exploration.The increase of the mass of V₂O₅ can obviously promote the catalytic oxidation of SO₂ to SO₃,and the conversion increases with the mass of V₂O₅ in the mass fraction of vanadium in the catalyst.In order to reduce the increase of SO₃ and ensure the denitrification efficiency,the content of V₂O₅ can be reduced as much as possible without affecting the denitrification efficiency.SiO₂ can effectively inhibit the oxidation of SO₂/SO₃ to reduce the conversion rate of SO₂,and when the two elements of vanadium and silicon coexist,the oxidation of SO₂/SO₃ is inhibited with the increase of SiO₂ content,especially for the vanadium content The higher the catalyst,the more the content of V,the higher the conversion of SO₂/SO₃,the more obvious the inhibition of SiO₂.BaO has a slight inhibitory effect on the oxidation reaction of SO₂,and the inhibition is limited to the left and the right.WO₃ promoted the conversion of SO₂/SO₃ to a certain extent,but the promotion effect was very limited and almost negligible.The effect of WO₃ can not be taken into consideration when reducing the amount of SO₃ produced by optimizing the composition of the catalyst.