Study On Sulfur Precipitation Mechanism In Sintering Flue Gas Desulfurization Process

In the flue gas purification technology,the wet method has always been paid attention to by the researchers.In our country,this kind of technology has been widely used in the purification of coal-fired flue gas.Ionic liquid circulation flue gas desulfurization of flue gas desulfurization is a new technology development in China in recent years,using ionic liquid as the absorbent,the absorbent has good absorption and desorption ability of SO₂ gas,high pure SO₂ gas and absorbent regeneration produced excellent raw material liquid SO₂,sulfuric acid,sulfur and the sulfur chemical products,recycling value is high and good market prospects.In the process of purifying SO₂ by the ion liquid sintering gas,a certain degree of sulfur is produced.This situation not only causes the problem of equipment clogging,but also seriously reduces the desulfurization efficiency of the desulfurization system.This topic mainly analyzes the production and transformation of sulfur?S?in the process of sintering and in the process of purification by using ionic liquid to absorb the SO₂ gas of the sintered flue gas.The effects of reaction temperature,pressure,solution p H,anion(SO₃^2-,S₂O₃^2-,SO₄^2-)and cations(Mn²⁺,Fe³⁺,Fe²⁺)on sulphur formation were investigated.The quality changes of sulphur and the variation of sulphur concentration in the solution were analyzed by weighing and ion chromatography respectively.The reactant and the product were analyzed by Fourier transform infrared spectrometer,X-ray photoelectron and X ray diffraction.The main conclusions are as follows:?1?With the increase of pH,the amount of sulphur is reduced and sulfur is not produced at pH>5.With the increase of temperature,sulphur production is also increasing,and sulfur is not formed before 125.Sulfur formation increases first and then decreases with the pressure increasing.The best conditions to prevent sulphur formation are:pH is 5,the temperature is 125 C,the smaller the pressure is,the better.?2?SO₃^2-and S₂O₃^2-promote the formation of sulfur,and S₂O₃^2-had a more prominent effect on sulfur generation.But SO₄^2-has a inhibitory effect.Fe³⁺?Mn²⁺and Fe²⁺all inhibit the formation of Sulphur,The inhibitory effect of Mn²⁺is more obvious than that of Fe³⁺and Fe²⁺on sulfur release.?3?Combined with the characterization of XRD,XPS,Fourier transform infrared spectroscopy and ion chromatography,sulfur is produced in the process of analysis.The reactant of sulfur formation reaction is bisulfite,the products are S8,thiosulfate and sulfate ion,and the reaction mechanism is deduced.The structure and thermodynamic properties of sulfurous acid,sulfuric acid and thiosulfate are calculated by Gaussian 09 quantum chemistry calculation software.It is proved that sulfite self oxidation and sulfur precipitation can be carried out.According to the relationship of enthalpy change with temperature,the temperature is 393.15K⁴33.15K,?rH°m?T?were all positive,and with the increase of temperature and become self correction,sulfite oxidation reduction is endothermic reaction.By the relationship between Gibbs free energy and temperature,rG^min 393.15K⁴33.15K when the total value is less than zero,indicating the sulfite conversion reaction at low temperature?<150??can happen.