Study On Simulation Of Fluid Flow In Multilevel Cross Flow Rotating Packed Bed

The high gravity rotating packed bed is the key equipment in the chemical strengthening process.The transfer principle,reaction principle and related balance characteristics between the materials are comprehensively used to improve the strengthening rate of the chemical process.According to the different forms of gas-liquid contact,the rotating packed bed is divided into counter-current,co-current and cross-current.The cross-flow rotating packed bed is more suitable for the atmospheric mass transfer process.However,the cross-flow rotating packed bed is insufficient in enhancing the gas-liquid mixing process of gas-phase resistance control.The unique structure of the multilevel cross flow rotating packed bed can solve the above problems.The design idea is to design the single-layer packing of the cross-flow rotating packed bed into three layers of packing,which is divided into two rotating rotors and a stator in the middle.It has the effect of strongly disturbing the airflow,which can reduce the cyclone and strengthen the mass transfer of the gas phase.However,due to the strict and complex internal structure of the multilevel cross flow rotating packed bed and the high gas velocity,it is difficult to use the existing technology to analyze the internal flow field qualitatively and quantitatively,and the research on the mass transfer mechanism is insufficient.Therefore,this paper takes the multilevel cross flow rotating packed bed as the research object,uses computational fluid dynamics technology to establish a 3D physical model,uses the standard RSM turbulence model and the SIMPLE algorithm,regards the actual packing as a porous medium,and uses the porous medium model to use the CFD method simulates its internal gas-phase flow field and liquid-phase flow field,and explores the internal liquid flowcharacteristics of the cross-flow bed and the influence of the stator and rotor on the gas flow.It provides theoretical guidance and data support for the study of the internal flow field of the multilevel cross flow rotating packed bed,and at the same time establishes a foundation for the subsequent study of the complex gas-liquid mass transfer effect.The main results are as follows:(1)In the gas flow field,the influence of gas flow and different speeds on different parameters including turbulent kinetic energy,turbulent dissipation rate,turbulent viscosity,pressure and other parameters of the multilevel cross flow rotating packed bed is simulated.The results show that with the increase of speed,the turbulent kinetic energy inside the multilevel cross flow rotating packed bed at low speed gradually increases,and the turbulent kinetic energy at high speed reaches its maximum value at 1400 rpm.From the overall point of view,the turbulent viscosity and turbulent dissipation rate are the largest when the internal speed of the rotating packed bed reaches 1400 rpm;as the gas volume increases,the turbulent kinetic energy and turbulent dissipation rate of the first layer of packing decrease first and then increase,while the third layer of packing keeps on increase.The turbulent viscosity of the second and third layers is stable,while the turbulent viscosity of different positions inside the first layer of packing will first decrease with the change of gas velocity and then become stable.As the gas volume increases,the overall pressure drop first decreases and then tends to level off.The changing laws of the parameters of the multilevel cross flow rotating packed bed at different radial positions and different axial positions are simulated.The results show that the change of the axial position shows that the turbulent kinetic energy of the first layer of packing is obviously greater than that of the other layers,the turbulent viscosity is obviously the largest in the second layer of packing,and the comparison of pressure is that the third layer of packing is the largest;As the position increases,the turbulent kinetic energy will gradually increase,and the pressure will decrease first and then increase from the inside to the outside of the packing;the turbulent dissipation rate increases significantly at the edge of thepacking than the inside of the packing,and the turbulent viscosity is larger than the inside of the packing.The effect of the intermediate stator packing on the parameters of the multi-layer cross-flow bed is simulated.The results show that the existence of the packed stator can effectively enhance the turbulent kinetic energy,turbulent dissipation rate,turbulent viscosity and pressure inside the packing,and enhance the strengthening effect of the packed bed.At the same time,a qualitative analysis was carried out on the parameter cloud graph.The results show that from the Contours inside the multilevel cross flow rotating packed bed,the packed stator can enhance the turbulent kinetic energy,pressure and turbulent viscosity of the gas flow inside the rotating packed bed.(2)In the liquid flow field,the influence of liquid velocity and different rotation speeds on the parameters of the multilevel cross flow rotating packed bed is simulated.The results show that with the increase of the rotational speed,the turbulent kinetic energy of the liquid inside the multilevel cross flow rotating packed bed first increases and then decreases,reaching the maximum value at 800 rpm.From the overall point of view,the turbulent viscosity and turbulent dissipation rate are the largest when the internal rotation speed of the rotating packed bed reaches 1400 rpm.At 600 rpm,the turbulent dissipation rate and turbulent viscosity are the smallest;as the inlet liquid velocity increases,the turbulent kinetic energy,turbulent dissipation rate,and turbulent viscosity of the liquid reach the minimum at 3.0m/s,and the pressure will reach the maximum.The change law of the parameters of the multi-layer cross-flow bed at different axial positions is simulated.The results show that with the change of the axial position,the turbulent kinetic energy is very large inside the moving rotor packing,and the turbulent dissipation rate is very large when it is close to the liquid inlet and outlet.The turbulent viscosity will be greatest at the liquid inlet of the first layer of packing.At the same time,a qualitative analysis was carried out on the parameter cloud graph.The results show that from the Contours inside the multilevel cross flow rotating packed bed,the packed stator has the functions of stabilizing the turbulent kinetic energy,pressure,and turbulent viscosity of the liquid flow inside the rotating packed bed,and can redistribute the liquid.It is proved that the intermediate static packing layer of the multilevel cross flow rotating packed bed can effectively reduce the cyclone,strengthen the disturbance of the gas flow field,and redistribute the liquid to enhance the gas-liquid contact.The multilevel cross flow rotating packed bed can enhance the gas-liquid mass transfer.