Liquid flow behavior, such as velocity distribution, in the packed column is of considerable importance in determining column performance. Using the volume-averaged method, a computational fluid dynamics(CFD) model was proposed to describe the liquid flow behavior in a structured packing column where the gas phase is stationary.A column packed with Mellapak 350Y had an inside diameter of 150 mm and a height of 1000 mm was simulated by solving the flow equations.A commercial CFD code, PHOENICS 3.3, was used to predict the fluid dynamics behavior of the liquid phase flow.The simulated profiles of pressure, velocity and concentration of the tracer were presented.The axial backmixing coefficients evaluated by the CFD results were presented and compared with the experimental data and the relative deviation was 3.8%—36.8%.
It has long been recognized that the flow pattern,especially the velocity distribution of the fluid,is of great importance in determining the performance of the equipment using structured packing as its internals.By using three-dimensional laser Doppler velocimetry(LDV),the liquid velocity distribution of the glycerol aqueous solution was measured in a typical unit of structured packing(Mellapak 350Y).Time averaged three-dimensional velocity distributions of the unit were measured at different flow rates.The experimental data showed that the liquid velocity profile of the single phase flow was complex because of the special geometry of the unit of structured packing.In the central region of the unit,the liquid was mixed strongly and re-distributed.It was the main cause generating the vortexes and secondary flow.
