Modeling F1 Valve Tray Hydraulics Using Computational Fluid Dynamics

In distillation process, distillation trays are established as gas and liquid contacting devices. An impasse that has hindered the further improvement of these devices is the fact that little is known about the flow phenomena prevailing inside a tray for given geometry and operating conditions. Computational fluid dynamics (CFD) is widely applied to study hydrodynamics of sieve tray. But for F1 valve tray, which is used widely in practice, there isn't any CFD simulation reported.In this paper, a transition CFD model was developed to predict the hydraulics of a full open valve tray. The model considered the three-dimensional two-phase flow of gas and liquid in the Eulerian framework, in which each phase was treated as an interpenetrating continuum with separate transport equations. The empirical correlation of Schiller et al. was applied to calculate the drag force, the interphase momentum transfer term between two phases, and provide a closure relation to the model. Present study, the standard k ?εturbulence model was used to simulate two phases turbulence flow. In the model, using finite volume method was used for numerical solution, the pressure-velocity coupling phase coupling SIMPLE algorithm was adopted, time items were calculated using implicit method and convection was solved by an order upwind method.Several simulations were carried out for a rectangular tray (0.5×0.35×0.3m) full open valve tray with varying superficial gas velocities, weir heights and liquid weir loads. In order to verify the simulations, an experiment was carried out in the same rectangular tower, and clear liquid height was measured by using air and water when F1 valves were full open. It showed that the predicted clear liquid heights were in good agreement with the experimental data. The CFD simulations reflect chaotic tray hydrodynamics and reveal that there are two level Eddies in the liquid exit and below weir position and a vertical eddy in the liquid exit。The simulation results indicated that CFD could be used as a powerful tool in the tray design and analysis.