| The structured packing distillation column is widely applied in industrial process for its multiple advantages like large capacity, high separation efficiency, large elasticity of operation, low pressure drop and and low liquid holdup. Unfortunately, till now the physical phenomena of the gas-liquid two-phase flow in distillation column are not well understood, which impedes the further increase of separation efficiency. The paper focuses on the hydrodynamics simulation of gas-liquid counter-current flow within the structured packings with commercial CFD software package FLUENT6.3. And based on simulation, the influences of gas flow rate, liquid physical properties, structure of packing surface are studied and analyzed.The main contents are as follows:1.A CFD model for the simulation of gas-liquid two-phase flow in structured packings was developed and validated. CFD models for three kinds of structured surface presented in literature were developed, simulations were carried out according to the experimental cases. And simulation results were compared with the experimental results, which proved the accuracy of the CFD model.2.Influences of gas flowrate on the hydrodynamics of gas-liquid two-phase flow in structured packings. Simulation models for four different gas flowrates were developed and CFD calculations were conducted. According to the results, the dynamic distribution characteristics of liquid film flow were analyzed, and variations of pressure fields, velocity fields, liquid holdup and effective interfacial area with the gas flowrate were studied.3.Influences of liquid physical properties on the hydrodynamics of gas-liquid two-phase flow in structured packings. Simulation models for four different liquid density, viscosity and surface tension were developed and CFD calculations were conducted. According to the results, in the variation ranges of liquid properties considered, a stable liquid film flow can form over packing surface, and the gas flow fields are similar. At the same time the dynamic distribution characteristics of liquid film flow were analyzed, and variations of pressure fields, velocity fields, liquid holdup and effective interfacial area with the liquid physical properties were studied.4.Influences of packing structure on the hydrodynamics of gas-liquid two-phase flow in structured packings. Simulation models for three different packing structure were developed and CFD calculations were conducted. According to the results, the variations of flow field, pressure fields, velocity fields, liquid holdup and effective interfacial area with the packing structure were studied. |
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