The Establishment Of Model And Simulation Study Of Microfiltration For Dispersions Using Tu Bular Membrane

Crossflow microfiltration is a constantly developing technique in the field of water and wastewater treatment. A major problem often encountered in the application of microfiltration is the dramatic reduction in filtration flux with time. The key of the problem are concentration polarization and fouling. Despite various mechanism model had been proposed to describe the process of microfiltration in recent years,which appeared some defaults. This thesis investigated the aspects of microfiltration for dispersions using carbon membranes, a mathematical model for time dependent permeate flux was established, and the result is used to compare to the experiment data.The entire filtration course can be divided into three stages. At the beginning of filtration, the first stage started with a rapid initial drop from the flux of pure water filtration. The second stage followed by a long-term gradual flux decrease The third stage was ended with a steady state flux. In order to provide a smooth transition from the pore blockage to cake filtrate regimes during the course of the filtration, introducing the conception of the time of model transformation. At the same time, introducing a variable cake porosity function in the third stage,In this thesis, the filtration equipment was conducted by tu bular carbon membrane. Experiments was carried out using carbon membrane, with a feed of titanium dioxide dispersions. On the base, a membrane permeation flux prediction model was built and was used to predict the permeation flux under different flow rates, pressures and concentrations. The model calculations was shown to be in excellent agreement with the experiment data. The practicability and validity of the models was confirmed. Some key parameters such as critical diameter, cake resistance, cake porosity and cake height variable with time were also successfully obtained. Furthermore, a simulation using variable and invariable porosity was carried out, and we can find from thecompared results of calculating and experiment, calculation was performed according to the method applied by introducing a variable porosity. Moreover was proved useful by the model of Altmann, through the calculations the model was found to reveal behaviors that were consistant with the observed phenomena of crossflow microfiltration,the advantage of model can be farther validated.This thesis is the first one in which the time of model transformation is proposed, and using a variable porosity instead of invariable porosity is introduced. Conclusion of this thesis:the model proposed might be used for the the prediction of flux, the design of membrane process, process optimization, Which used in every domain will also shown importmant instructive value.