Simulation On Mass Transfer Efficiency Of Perforated Plate Lifting Pervaporation Membrane Module

Part of the energy consumed in chemical production comes from the purification of raw materials.Pervaporation membrane separation technology is widely used in chemical industry by overcoming the restriction of thermodynamic vapor-liquid balance and has the advantages of energy saving,environmental protection and high separability.The unique phase transition and vacuum conditions in pervaporation process require higher structure of membrane modules.This paper uses Computational Fluid Dynamics to analyze the internal flow fields of different membrane modules to simulate the mass transfer efficiency of a perforated plate lifting membrane module.The main research conclusions are as follows:(1)The convection-diffusion method was used to conduct two-dimensional and three-dimensional simulation of different tubular membrane modules,and the internal changes of the flow field and the influence of mass transfer before and after inserting the perforated plate were studied.In the single tubular film module,the perforated plate improves the mass transfer coefficient by increasing the local flow rate and reducing the boundary layer thickness.The liquid mass transfer coefficient increases by 15% at different feed speeds.In the multi-membrane module,the perforated plate makes the fluid flow distribution relatively uniform by slowing down the fluidic phenomenon,and enhances the material exchange process of permeable modules,thus improving the permeable performance of the multi-membrane module.At a feed flow rate of 0.0001 m/s,the penetration performance of the perforated channel is improved by approximately 50%.(2)Three-dimensional simulation of two kinds of multi-tubular membrane modules under industrial design was carried out to study the changes in the internal flow field of membrane modules before and after the insertion of axial and radial perforated plates.Both kinds of perforated plates can reconverge the escaping fluid and distribute it to the perforated area.On the one hand,the membrane surface velocity is increased and the local mass transfer is enhanced.On the other hand,the flow dead zone is reduced,and the uniform distribution within the membrane modules is realized on the whole.When the cutting degree of radial baffle is 40 mm,the axial perforated plate is staggered and the axial perforated plate is 15 mm,the flow uniformity and mass transfer efficiency of membrane modules are the best.In addition,by simulating the height of membrane modules under different conditions,the uniformity of flow field and the enhancement effect of mass transfer caused by perforated plate can be guaranteed.(3)Three-dimensional simulation of the hollow fiber membrane under industrial design was carried out to study the changes of the flow field inside the membrane module before and after the insertion of the radial perforated plate.The perforated plate reconcentrates the escaping fluid and distributes it to the perforated area,and makes full contact with the hollow fiber membrane unit at a high velocity.Compared with the membrane module without baffle,the membrane surface flow velocity and wall shear force are 3.8 times and 1.5 times higher,respectively.In addition,when the filling density is increased by 1.4 times,the flow field uniformity and mass transfer can be guaranteed,which has a wider application in industrial production.