Mass Transfer Enchancement In Hollow Fiber Membrane Contactor Shell-Side With Additive

Hollow fiber membrane modules, with the advantage of small size, high loading density and unrequited supporting in the process, are widely used in membrane separation process. In addition, the shell-side mass transfer is commonly forced on due to its complicated conditions and various affecting factors. The fiber of traditional hollow fiber membrane contactor are distributed randomly which results in a loss in efficient. Therefore, the study of shell-side mass transfer performance is of great significance on application.In this paper, the dissolved oxygen was used for experiment system, and the factors such as packing density, the number of additive and L/D (the ratio of the length to diameter of the module) which influence shell-side hydrodynamic and mass transfer performance were studied by changing the structure of hollow fiber membrane modules by the method of adding spacer, baffle and spiral baffle. The main contents and findings are summarized as follows.Mass transfer enhancement in shell-side of hollow fiber module with spacer was investigated firstly. Hydrodynamics and mass transfer performance of hollow fibers membrane modules were studied with different packing density and the number of spacer. In addition, the correlation between increase of mass transfer coefficient and the presser drop and mass transfer coefficient per presser drop were also analyzed. It can be conclude that the spacer can decrease nonideal response, leading to increase of the mass transfer coefficient. The highest increase of mass transfer coefficient is up to 46% at 3 spacers. The increase of mass transfer coefficient is higher at low packing density and low Re. In addition, mass transfer coefficient per presser drop is higher than straight module at 1 and 2 spacers, while lower at 3spacers, and it is highest at 2 spacers.Mass transfer enhancement in shell side of hollow fiber contactor with different bafflers was investigated. The effects of packing density, number of baffle and L/D on hydrodynamics and mass transfer performance of hollow fibers membrane modules were further studied for mass transfer enhancement performance. In addition we obtained the correlation between increase of mass transfer coefficient and the presser drop as well as mass transfer coefficient per presser drop. It can be concluded that the baffle can increase the mass transfer coefficient. When it comes to the modules of L/D=14, the higher the packing density, the higher the mass transfer coefficient, and the highest increase is up to 37%. However, the mass transfer coefficient per presser drop is lower than straight module. Moreover, the increase of mass transfer coefficient can up from 60% to 100%, and the mass transfer coefficients per pressure drop is bigger than straight module, for the modules of L/D=4.Considering the similarity with the spiral baffle heat exchanger, the spiral baffles were further added to the shell side. The results show that the spiral baffle can also increase mass transfer performance, and it is 1.7-2.2 times than that of straight module. Under the experiment conditions, the more the number of spiral baffles, the better the mass transfer performance. The presser drop is lower and mass transfer coefficient is bigger than those of baffle at the same condition, that is mass transfer coefficient per presser drop is higher.The evaluation for the mass transfer enhancement performance for different modules was in two fields:that is mass transfer coefficient and mass transfer coefficient per presser drop. As for mass transfer coefficient, the modules with additive are bigger than straight ones, especially the spiral baffle module shows the exceptional biggest one; As for the mass transfer coefficient per presser drop, the various modules give diverse performances. The modules with one and two spacers, the baffle possessing smaller L/D, and the spiral baffle modules show better performance than straight ones. So, based on the above discussion, the spiral baffle modules, considering both mass transfer coefficient and mass transfer coefficient per presser drop, can show best mass transfer enhancement.