화학공학소재연구정보센터
Industrial & Engineering Chemistry Research, Vol.49, No.14, 6599-6611, 2010
Simultaneous Momentum, Mass, and Energy Transfer Analysis of a Distillation Sieve Tray Using CFD Techniques: Prediction of Efficiencies
Conventional models for distillation columns are based on equilibrium and nonequilibrium stage concepts. Although equilibrium and nonequilibrium stage models provide useful results, they neglect the fluid dynamics phenomena by assuming a perfect mixture on the plates in each phase. However, the flow pattern on a distillation tray is of great importance in terms of the mass and energy transfer mechanisms, and this influence can only be analyzed by carrying out a fluid dynamics study. The main objective of this study is to obtain experimental data of clear liquid height in a distillation sieve tray apparatus operating with air and water, and to apply a computational fluid dynamics (CFD) model in a Eulerian-Eulerian framework for gas-liquid flows that is able to predict the momentum, mass, and thermal phenomena of multiphase flows. A two-phase, three-dimensional and transient model with chemical species, energy, and momentum conservation balances was applied to predict the volume fraction, velocity, pressure, temperature, and concentration fields of two-phase flows on distillation sieve trays. The mathematical model was applied in the CFD commercial code for numerical studies, with the construction of a particular numerical grid and with its own subroutines in Fortran language for the closure equations of the model. The hydrodynamic model was compared with experimental data and presented good agreement. The results of the model show the volume fraction, velocity, temperature, and concentration profiles as a function of time and the position on the distillation sieve tray. The model implemented in this study allows direct application to predict efficiencies in distillation plates, more specifically point, plate, component, and global efficiencies.