| Due to the economic benefits of shipping industry,the development of international maritime trade is very rapid in recent years,but at the same time,the harm of ship exhaust is also very serious,in which SO2 has great harm to the atmospheric environment and human body.IMO has issued many regulations to control the amount of SO2 emitted from ships.Compared with low sulfur fuel control SO2 technology,the installation of wet flue gas desulfurization equipment is more long-term.The sodium alkali desulfurization technology has the advantages of navigation in the whole sea,high desulfurization efficiency and no secondary pollution,so it is very feasible to use this method for desulfurization.In this thesis,the current situation of desulfurization technology at home and abroad is described,and the process of SO2 absorption by sodium alkali solution is analyzed the structure of the spray tower was designed with the parameters of flue gas volume and so on.The solid works software was used to draw the three-dimensional solid model,which was imported into ICEM for mesh generation.The Fluent software was imported to carry out the numerical simulation research on the three-dimensional spray tower model.According to the double membrane theory,the C++ language program was written as the SO2 mass transfer model,which was loaded into the Fluent software through the interpretive UDF,so as to analyze the velocity flow field and pressure flow field the parameters of the spray tower were optimized by comparing the flow field of SO2 concentration with the field of field.The absorption process of SO2 in diesel exhaust gas by sodium lye was explored through the experimental platform,which provided engineering reference for the actual operation of spray tower.The conclusion of this thesis is as follows.(1)The spray tower is designed with three layers of conical nozzles with a diameter of2.5 m and a height of 5.5m.(2)Numerical simulation results in spray tower: when the tower is empty,the upward phenomenon of flue gas sticking to the wall is very serious,and the arrangement of spray layer has a good rectification effect on flue gas.Under other conditions,the more spray layers in spray tower,the better the rectification effect on flue gas and the higher the desulfurization efficiency.The relationship between desulfurization tower efficiency and tower diameter first presents inverse proportion function and then positive proportion function,so the calculation of tower diameter should be considered comprehensively.The smaller the particle size of alkali liquor is,the higher the desulfurization efficiency is.However,the particle size is restricted by the nozzle structure,and too small will increase the burden of the demister,resulting in a waste of resources.(3)Simulation results of spray tower Optimization: three layers of spray layer are arranged alternately,which can improve the desulfurization efficiency of spray tower.The nozzle angle of 120° is suitable.4m/s is recommended for spray speed.When the concentration of SO2 in ship flue gas is small,in order to save the consumption of spray alkali,the 1 and 3 spray layers can be opened.The arrangement of three guide plates at the bend is conducive to uniform flow in the tower and effectively improve the desulfurization efficiency.(4)The experimental results show that the temperature of sodium lye is inversely proportional to the desulfurization efficiency of spray tower,It is suggested that the temperature of alkali liquor should be below 40 ℃.There is a positive proportional function relationship between the p H of sodium alkali solution and desulfurization efficiency.The experimental results show that the efficiency of desulfurization can be effectively improved by setting guide plate in the bend,the error between experiment and simulation is very small. |
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