Wet Removal Of Sulfur Dioxide And Nitrogen Oxides From Simulated Flue Gas By Ca?ClO?₂ Solution

Along with the implement of the new air quality standards and atmospheric pollutants emission standards, more strict laws have been put forward to the emission of sulfur dioxide and nitrogen oxides. Environmental management of China has achieved a certain effect on atmospheric pollution control in recent years,however, the control of SO₂ and NO_x is still an important subject in atmospheric pollution control.Calcium hypochlorite, which is also called bleaching powder, is a cheap and practical absorbent. As a mature chemical product with steady quality, strong oxidizing ability and wide source, it has been widely used in waste water treatment.However, it was rarely used in flue gas treatment. Based on reading a lot of desulfurization and denitration literatures, summarizing desulfurization and denitration technology status at home and abroad, calcium hypochlorite solution was used as absorbent to remove SO₂ and NO_x by wet method in this study. The mass transfer mechanism of calcium hypochlorite solution desulfurization and denitration were analyzed, the feasibility of the desulfurization and denitration by thermodynamic calculation were demonstrated, the reaction mechanism of simultaneous removal of SO₂ and NO_x were analyzed through the analysis of the chemical equation of the reaction process. At the same time, a large number of experiments were performed to explore the rule of desulfurization and denitration by calcium hypochlorite solution: first, the preliminary experiments showed that calcium hypochlorite solution was able to completely remove sulfur dioxide, but the removal efficiency of nitrogen oxides was poor. To find the optimum reaction conditions of denitration by calcium hypochlorite solution, the effect of different reaction conditions were studied. The results showed that the optimum reaction conditions were: the flue gas flow rate of 400 mL·min^-1, liquid layer height of 80 cm,Ca?ClO?₂ solution concentration of 0.1 wt %, the reaction temperature of 60 ?, the initial pH of 12, oxygen content of 8%, NO concentration of 800 mg·m^-3, and SO2 concentration of 2000 mg·m^-3; Second, the experimental results of additives on the denitration efficiency showed that KMnO₄ could largely promote the denitration efficiency. Under the optimum reaction conditions with additives for simultaneous removal of SO₂ and NO_x by calcium hypochlorite solution, the experimental results showed that the desulfurization efficiency achieved 100%, denitration efficiency upto 85%; Finally, the products of the absorbent have been analyzed by the ion chromatography method, it showed that main product of simultaneous desulfurization and denitration by calcium hypochlorite solution were SO₄^2- and NO₃^-. The economic analysis revealed that simultaneous desulfurization and denitration by Calcium hypochlorite solution has a prospect of future application.