The Research Of Helical Membrane Modules On Flow And Mass Transfer Behaviors

Membrane separation technique with low energy consumption, high separation efficiency, wide range of application, simple and compact device and working at room temperature has been widely used in petroleum chemical industry, medicine, food, electronics, biochemistry, environment and people’s life and so on. Membrane module is the core of the membrane separation technology, the performance of the membrane module depends on the efficiency of membrane separation process. One of research hot spots is to study of new type membrane module Therefore, in this paper it was studied a new type helical membrane module" flow and mass transfer behaviors, mainly including the following contents:(1) Set up a suit of helical membrane modules filtration experiment devices via filtrating silicon carbide raw material liquid to resrarch the performance of helical membrane modules.When aeration intensity was0.1m3/h, the stable filtration flux of helical membrane modules increased by45%than flat sheet membrane modules, the total filtration resistance lower20%average, cake layer resistance was the main resistance of the filtration and more than60%, clogging resistance accounted for about20%. Average mass transfer coefficient is increased by43%, membrane fouling index lower by55%, the antifouling property of helical membrane modules were suprrior to flat sheet membrane modules.(2) A3D Volume of Fluid (VOF) multiphase flow model in CFD software Fluent was employed to simulate the experimental precess at full size, obtained the velocity distribution, turbulent kinetic energy distribution, membrane surface shear stress distribution and gas holdup distribution in reactor. There were vortexs in helical membrane reactor and with the increase of helical angles; the vortexs were widely distributed in the reactor. The membrane surface shear stress of helical membrane was higher than flat sheet membrane and average shear stress increase by123%. The helical membrane modules increased the interaction of membrane surface, bubbles and liquid, and increased the collision frequency between bubbles and membrane surface so the trajectories of bubbels changed and improved gas-liquid mixing effect as well as the mass transfer was enhanced.(3) Adopted the advanced flow field testing technology PIV to measure the flow field in helical membrane reactor, obtained the velocity distribution, streamline distribution and vorticity distribution of the measurement district. It was obtained the membrane shear stress value by calculating experiment datas. Comparing the results obtained from CFD simulation with those from PIV measurements, we can see that the two results are consistent within an acceptable range of error. In PIV test area, a large circulation was formed in0°membrane reactor while in helical membrane reactor there were vortex appeared and at270°the vortex had maximux size. With the increasing of helical angle, the velocity at the membrane surface was reduced, but the angle between the vector and membrane surface increased. The vorticity value of helical membrane reactor was larger than flat sheet membrane reactor and average increased by145%and become widely distributed.