CFD Simulation Of Hydrodynamics And Mixing Characteristics In Structured Packing Unit

Hydrodynamics of the fluid is of great importance in determining the reaction or mass transfer efficiency for chemical process carried out in static mixer or distillation column which using structured packing as their internals. Up still now, very few reports have been found in literature to investigate the flow behavior, mixing behavior in the structured packing from representing unit scale.Because of the complicated structure in structured packing, it will definitely be unattained to simulate the fluid flow of the whole column with structured packing on the present conditions. In this paper, computational fluid dynamics (CFD) method was used to simulate the velocity distribution in the typical unit of structured packing. Commercial CFD package, FLUENT, was used to solve the proposed model where the special configurations of the structured packing was considered and multi-block body-fitted mesh was used. A single-fluid CFD model, based on Navier-Stokes equation, was used to numerically predict the velocity distribution inside the structured packing unit. Experimental data for liquid flow in a represent unit of the structured packing was collected using Laser Doppler Velocimetry (LDV) method. In the experiment, glycerol aqueous solution was selected as the tested liquid to minimize the refractive effects of Plexiglas packing. Different turbulent models were compared and the RNG k-εmodel was found in good agreement with experimental data. It has a lot of similarities when we investigated several units with this model.The dispersion characteristics of the structured packing unit can be determined reasonably well with RNG k-εmodel. Comparison of the RTD measured in the two different outlets with different inlet velocities lead to the conclusion that superficial velocity has great effects on axial dispersion coefficient without regard to the different outlets.