Numerical Simulation Study Of Liquid-solid Flow Behaviour In The Stirred Tank

Mixing equipment is a kind of mechanical equipment which is widely used in engineering at present.It plays an important role in petrochemical,mechanical processing,pharmaceutical manufacturing and other fields.Mixing equipment can mix a variety of substances evenly,promote heat and mass transfer,and improve the treatment efficiency of engineering process.In general,the medium in the mixing equipment is not unique,and there will be two or more phases,so the research of the mixing equipment is also very important in the multiphase hydrodynamics.In this paper,numerical simulation of liquid-solid two-phase flow in a stirred tank equipped with a six pitched blades turbine(PBT6)is studied.The Euler-Euler two fluid model is adopted,and the impeller is treated by MRF method.The numerical simulation results are compared with the experimental data,and the trend is in good agreement,proving the reliability of the simulation method.Then it will be used to discuss the effect of material parameters and structural parameters in the stirred tank on the state of solid-liquid suspension and stirring performance.In this paper,the material parameters(particle diameter,particle density,liquid viscosity)and structural parameters(impeller diameter,impeller clearance,impeller type)are changed for numerical simulation.The effects of the changes of relevant parameters on the velocity distribution,particle concentration distribution and particle granular temperature distribution in the stirred tank are analyzed and discussed.The stirring system with particle diameter of0.087 mm can achieve good suspension effect.With the increase of particle diameter,the particle deposition increases.With the increase of particle density,the particle deposition increases at the bottom of the impeller hub.With the increase of liquid viscosity,the particle concentration distribution is more uniform,and the particle suspension performance is better.With the increase of impeller diameter,the particle suspension effect is better,and the particles with small diameter gather at the bottom of the stirred tank.The higher the clearance of the impeller,the better the suspension of particles above the impeller,but the more deposition at the bottom of the tank.The stirring performance of a Rushton turbine(RT6)is better than that of a six pitched blades turbine(PBT6)and a six flat blade turbine(FBT6),and the stirring effect is more uniform.