Hydrodynamics of a Laboratory Membrane Module

The process of pervaporation separation is promising for the separation of azeotropic, thermally unstable, and near-boiling liquid mixtures; it is an alternative to conventional separation methods. At the same time, this process is energy and resource saving, since it requires the use of only low-potential heat. Due to the compactness of the equipment and a wide variety of membrane materials, pervaporation allows for integration into existing production without significant changes in process schemes. The wide variety of membrane materials generates the need for their experimental testing with each mixture under study. An essential parameter influencing the mass transfer process is the hydrodynamics of the raw material flow on the surface of the selective layer of the membrane. The purpose of this study is to find the optimal geometrical parameters of the distributing device, allowing to increase the speed and uniformity of the raw material flow at the surface of the selective layer of the membrane, thereby improving the separation characteristics in the process of pervaporation separation. This paper presents the results of the mathematical modeling of the hydrodynamics of the membrane module of a laboratory experimental pervaporation unit with different channel geometries. The data on the average flow rate and pressure drop inside the membrane module, the data on the distribution of the velocity field near the membrane surface and the feed stream line at the flow rate of the mixture being separated are given. The flow parameters were set for an ethanol-water mixture with a concentration of 80% ethanol, at 60⁰C. Mathematical modeling was performed in the ANSYS Fluent software package using the k-ε turbulence model, the number of elements in the grid is ≈ 3 million, the grid is polyhedral, the process of pervaporation separation was not considered. The calculation was made for 4 variants of the geometry of the switchgear channels. The results of the calculation were taken as the basis for the manufacture of a modernized distribution device of the membrane module of the experimental pervaporation unit.