CFD modeling of mass-transfer processes in randomly packed distillation columns

The volume-averaged equations for velocity and concentration fields have be en used to simulate the hydrodynamics and mass-transfer processes in random ly packed distillation columns. This approach is regarded as a second-gener ation computational fluid dynamics (CFD) based model, and a significant dep arture from the traditional one-dimensional, first-generation models. The m odel has ability to capture radial and axial variations in flow and mass-tr ansfer conditions. The spatial variation of void fraction has been included to take into account the effect of bed structures. The simulation results have been compared with experimental data reported by Fractionation Researc h, Inc. (FRI) which performed their tests in a 1.22-m-diameter column with a packed bed height of 3.66 m. For validation, we have used data obtained w ith 15.9-, 25.4-, and 50.8-mm metal Pall rings at various operating conditi ons. Good agreement between CFD predictions and published experimental data has been obtained. This is regarded as an encouraging sign that CFD models can play a useful role in studying separation processes.