Study On The Hydrodynamics Of Ionic Liquid-Solid Particle In Stirred Reactor

As new solvents with many excellent physical and chemical properties,ionic liquids are expected to be used in the chemical industry as solvents and media.As a common mixing and reaction equipment,multi-phase stirring reactor is widely used in chemical,metallurgical,biological and other industries.The in-depth study about the flow characteristics of ionic liquids in multi-phase stirred tanks will provide an important basis for the design of new processes and equipment of green reaction and separation.In order to study the ionic liquid-particle tow-phase flow in a stirred,a combination of experimental and simulated methods is used in the thesis.The main contents and results are listed as follow:(1)Study on the drag coefficient of single particle in ionic liquids.The drag coefficient of single particle in the ionic liquids was measured experimentally.It was found that the classical drag coefficient models cannot be directly used to predict the drag coefficient in an ionic liquid system.Using the dimensionless analysis,two new drag coefficient models were established,and the prediction accuracy is improved greatly.Then the influence of the surface properties on the drag coefficient was also investigated.(2)A numerical simulation model for ionic liquids-particle system was established using Euler-Euler multiphase flow model combined with the new drag coefficient for ionic liquid systems.Compared with the experimental results,the simulated results show that the new model is more accurate(the maximum experimental and simulation error is 8.89%).The maximum levitation height of the particles is positively related to the rotation speed of the stirring blades,and almost coincides with the boundary line where the axial velocity of the two-phase velocity field is zero.In addition,the standard deviation method was used to evaluate the suspended state of solid particles,and the uniform suspension speed of the two-phase stirred tank of the ionic liquid system was predicted.(3)A FCCS-CFD coupled method for ionic liquid-particle systems was established by combining thermodynamics and computational fluid dynamics methods.The liquid-solid two-phase flow in a stirred tank was studied by the FCCS-CFD coupled method.The effects of different temperatures and types of ionic liquids on the liquid-solid two-phase flow were investigated.The results showed that the distribution of the particles in the reactor was inversely proportional to the viscosity of the liquid medium at different rotation speeds.When the ionic liquid with high viscosity at room temperature is used as the liquid phase,the reduction of viscosity can be performed by pre-heating.Meanwhile,the reduction of viscosity could increase the uniformity of distribution of the catalyst particles and improve the homogeneity of the flow field.