Study Of The Flow Mechanism And CFD Simulation On Flow-Guided Tray

In this paper, the development and current situation of flow-guided trays and the development and application of CFD simulation were summarized. A multiscale CFD model was established to simulate the macroscopic and microcosmic hydrodynamics. And the accuracy and reliability of the CFD model was verified by hydrodynamic experiment.An Euler-Euler multi-phase model and an RNG k-ε turbulent model were adopted to build the 3D CFD model. Meanwhile, the momentum source item was analyzed to demonstrate the mathematical expression. Also, reasonable boundary conditions were set in the CFD model. This CFD model not only simulate the macroscoptic hydrodynamics, such as pressure drop, weeping, entrainment, clear liquid height, but also could get the microcosmic parameters, such as the momentum transfer coefficient of flow-guided holes, general resistance coefficient between liquid and tray plate. In order to verify the accuracy and reliability of the CFD model, a hydrodynamic experiment with water-air system was carried out in an inner diameter 476mm with 450mm distance between plates. The macroscopic hydrodynamic parameters were measured in this cold model experiment.The commercial CFD software ANSYS Fluent 15.0 was employed to simulate CFD model built above by setting rational initial conditions to get flow-guided sieve tray’s (FGST) simulated hydrodynamics. The simulated data was in good agreement with experimental results. The deviation of dry pressure drop between simulated and experimental data was lower than 5%, and the wet pressure drop’s deviation was lower than 10%. Furthermore, the silmulated clear liquid height was slightly over-predicted than experimental data within 10% error. CFD simulated data confirmed the liquid diretional pushing effect and found the main area of yielding weeping. With these basic facts, section monitors were set in the control volume to get data for the liquid momentum conservation calculation. The momentum transfer coefficient of bubble promoter, the momentum transfer coefficient of flow-guided holes and the general resistance coefficient between liquid and tray plate were obtained by this method with data from CFD simulation. These microcosmic parameters were in good agreement with the data got from experimental measurement by Tianjin University. All these mentioned above could prove the accuracy and reliability of this CFD model to replace experiments to optimize the FGST’s geometric construction. Finally, mathematical formula was offered to calculate the average resident time of liquid flowing across the plate to direct the FGST’s design work in industry.In conclusion, a 3D multi-phase model was built from theoretical research for FGST to get macroscopic and microcosmic hydrodynamics, and the accuracy and reliability of this model was verified by experiments. This model and simulated data could offer effective method for FGST’s flow field simulation, and also provide theoretical instruction for optimizing structure and industrial application.