| As a solvent extraction carrier,the pulsed extraction column is widely used in the chemical industry,metallurgy,sewage treatment,and other fields because of its advantages of improving extraction efficiency,reducing production cost,and occupying a small area,and has become a first choice for the introduction and transformation of extraction equipment.However,the two-phase hydrodynamics and mass transfer behavior in pulsed extraction columns are extremely complex,and there is still a lack of an accurate scale-up model and systematic theoretical research.Additionally,the diversity and complexity of extraction systems limit the industrial popularization and application of pulsed extraction columns.At present,there are many uncertain factors in the industrial scale-up application of pulsed extraction columns,most of which are carried out by experience,and the implementation is difficult and the cycle is long.Therefore,in this paper,the two-phase hydrodynamics and mass transfer behavior in the scale-up of the pulsed disc and doughnut extraction column were studied,providing a reference for the industrial scale-up and application of the pulsed disc and doughnut extraction column.The main research contents are as follows:(1)Using 10vol% P507+90vol% kerosene as continuous phase and tap water as dispersed phase,the effects of diameter scale-up,plate spacing scale-up,equal scaleup,two-phase velocity and pulse intensity on the hydraulic properties of the pulsed disc and doughnut extraction column we re studied.Based on the experimental data and conclusions,combined with the geometric structure,physical parameters,and operating conditions of the extraction column,a mathematical prediction model was established using the least squares method,which can be used to predict hydraulic properties.The total average relative errors to predict the volume,slip velocity,characteristic velocity,and average droplet diameter of the dispersed phase are 8.38%,7.53%,3.87%,and 7.10%,respectively.The Weibull distribution function is used to predict the droplet size distribution.An empirical model is established to predict the key parameters of the Weibull distribution function model.The total average relative errors for the parameters α and β are 14.17% and 17.11%,respectively.(2)Using the axial diffusion model and the pulse tracer method,the effects of column diameter scale-up,plate spacing scale-up,two-phase velocity,and pulse intensity on the axial diffusion performance of the pulsed disc and dough nut extraction column were studied.Based on the experimental data and conclusions,combined with the influence of the geometric structure,physical parameters,and operating conditions of the extraction column,a prediction model of the continuous phase axial diffusion coefficient was established using the least squares regression method,and the total average relative error was 5.3%.(3)Using a 10vol% P507+90vol% kerosene solution and a high nickel and low cobalt solution as the extraction system,the m ass transfer performance of the pulsed disc and doughnut extraction column was studied.The effects of column diameter scale-up,phase ratio,flow rate,and pulse intensity on nickel-cobalt extraction were investigated.Under the same conditions,the extra ction rate of cobalt is 98.97%38 and that of nickel is 36.53%.Furthermore,the optimal conditions for the separation of nickel and cobalt are given as follows: In an extraction column with a diameter of 0.03 m,the flow rate of the dispersed phase and the continuous phase is 0.00125 m/s,and the pulse intensity is 0.015 m/s;In an extraction column with a diameter of 0.05 m,the flow rate of the dispersed phase and the continuous phase is 0.001 m/s,and the pulse intensity is 0.01 m/s.In this paper,the scale-up law of the pulsed disc and doughnut extraction column was studied,and the related scale-up mathematical prediction model was established,which provided a reference for the design optimization and industrial application of the pulsed disc and dou ghnut extraction column in the future. |
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