| With the rapid development of social economy,the problems of energy and environmental protection have become increasingly prominent,and higher requirements have been put forward for the treatment of flue gas pollutants in coal-fired power plants.At present,coal-fired power plants meet the requirements of deep removal of SO2,NOx and PM through the upgrading of a single technology,which lacks the overall consideration of the whole process,and there is a great space for energy saving.In this paper,the characteristics of simultaneous desulfurization and denitration based on ozone preoxidation were studied by using the spray-and-scattered-bubble experimental system with ammonia water as absorbent.A regression model of removal efficiency based on response surface method was established,and the effects of interaction of various factors on the removal efficiency were analyzed.The emission characteristics of particulate matter in the removal process were studied.The specific work is as follows:（1）The experiments of simultaneous desulfurization and denitrification by ozone preoxidation of ammonia were carried out with spray-and-scattered-bubble tower.The oxidation performance of SO2 and NO and the influence on desulfurization and denitrification efficiency under different O3/NO molar ratios were studied.The simultaneous desulfurization and denitrification performance under spray-and-scattered-bubble technology,spray technology,bubble technology were compared.The effects of SO2 concentration,NO concentration,liquid-gas ratio and immersion depth on the simultaneous desulfurization and denitrification performance during the operation of spray-and-scattered-bubble tower were investigated.The results show that the increase of O3/NO molar ratio can significantly improve the denitration efficiency.The increase of SO2 concentration will promote the removal of NOx.The desulfurization and denitration efficiency can be improved with the increase of liquid-gas ratio and immersion depth.When the mole ratio of O3/NO is 1,the liquid-gas ratio is 6 L/m3,the leaching depth is 50mm,and the mass fraction of ammonia water is 0.06%,the desulfurization and denitration efficiency of spray-and-scattered-bubble technology can reach 99.6%and 82.5%,respectively.The removal efficiency of spray-and-scattered-bubble technology is higher than that of spray technology and bubbling technology under the same condition.（2）Based on the response surface method,the regression model of desulfurization and denitration efficiency was established,and the influence of multiple operating parameters and desulfurization and denitration efficiency in the process of simultaneous desulfurization and denitration by ozone preoxidation in ammonia process was explored.The effects of O3/NO molar ratio（A）,SO2 concentration（B）,liquid-gas ratio（C）,leaching depth（D）and the interaction terms of each factor on desulfurization and denitration efficiency were investigated.The linear order of significance of desulfurization efficiency was D>C>B>A,and the interaction order of significance was CD>BD>BC>AD>AC=AB.The linear terms of the effect of denitration efficiency were ordered by significance in order of D>A>C>B,and the interaction terms were ordered by significance in order of CD>AC>AD>AB>BC>BD.（3）By sampling the particulate matter after the spraying and bubbling tower,the emission characteristics of the particulate matter during the simultaneous desulfurization and denitration under the pre-oxidation of ozone were studied.The effects of common operating parameters such as SO2 concentration,NO concentration,liquid-gas ratio and immersion depth on the emission of particulate matter were discussed.The emission characteristics of the particulate matter only spraying and bubbling were compared.The results show that the particle size distribution is unimodal,and the particle emission of spray-and-scattered-bubble technology is lower than that of spray technology,especially under the condition of simultaneous desulfurization and denitrification,the decrease rate is about 20%.The increase of SO2 concentration will increase the emission level of particulate matter.With the addition of NO,the emission level of particulate matter increased significantly,increasing by about 57%.The increase of liquid-gas ratio and immersion depth will decrease the emission level of particulate matter. |
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