Fluid Dynamics Simulation And Membrane Module Optimization In Membrane Separation And Mass Transfer Process

Membrane separation technology has been widely used in the fields of food, pharmaceutical, biotechnology, environmental protection, chemical industry, metallurgy, energy, petrolem, water treatment, electronics and bionics because of the functions of separation, concentration, purification, refining, and the features of efficiency, energy-saving, environmental protection, molecular level filtration, and the simple and easy to control filtration process. It has generated huge economic and social benefits and become one of the most important means of separation sciences. Spiral wound membrane module becomes widely used because of the feature of compact structure and large effective membrane area in unit volume. But membrane fouling and concentration polarization limit the further development and application of membrane separation technology.Membrane fouling and concentration polarization can be mitigated by three means:(1) pretreatment or online processing;(2) increase the degree of turbulence in order to reduce the thickness of boundary layer;(3) reduce membrane flux. But, these methods will increase the total cost. Therefor, optimizing the system to reduce membrane fouling or concentration polarization without additional costs is very important.The paper uses Fluent to optimize spiral wound membrane module, especially the spacer. The study mainly studies the effect of diameter, spacing, cross-sectional shape and arrangement of filament, and the size of particles in fluid on fluid dynamics in membrane separation and mass transfer process, especially the effect on membrane flux. The paper shows that when the equivalent diameter of the particles in the fluid is2μm, the diameter of top layer spacer filament is0.3mm, and the diameter of bottom layer spacer filament is0.1mm, distance of top layer spacer filament is4mm, and distance of bottom layer spacer filament is4mm, the angle between crossing filaments θ is90°and the flow attack angle a is45°, the membrane flux is the largest. In addition, the roughness of the spacer, the operating condition of spiral wound membrane separator and parameters of porous-jump model all have important impact on membrane flux. The experiment study shows that membrane material, operating pressure, fluid temperature, recycle ratio and the operating time are all important to the outlet flow.