The Flow And Mass Transfer Coupled Model For The New Fixed Valve Trays

In view of the shortcomings in the current fixed valve tray, such as uneven flow distribution and small operational flexibility, our group has developed a new, streamlined and high efficient guided fixed valve tray. We carried in-depth study of gas-liquid two-phase fluid flow and mass transfer behavior for this new type tray using a combination of experimental and computational fluid dynamics methods. In this paper, we built two-phase flow model considering gas-liquid interaction and mass transfer coupling model based on the double Euler two phase flow model, and applied the model in the simulation. Then verified the results through hydromechanics experiments and mass transfer experiments, and finally forecasted the fluid mechanical behavior and operation elasticity of large tower.We ultimately determined using the SST turbulence model to describe the gas-liquid two-phase turbulent flow after comparing a variety of turbulence models, in which interphase momentum and mass transfer sources were added to account for the interaction between the two phases, and the effect of phase volume fraction on the gas-liquid two-phase flow state was considered. In order to verify the accuracy of the models, we conducted the gas liquid two phase flow field simulation and compared the simulation results with the experimental data, the calculated results were found to be in good agreement with the experimental data, thus the accuracy of the model was proved.We first simulated single-phase flow on the tray and investigated the composition of dry plate pressure drop and the gas flow distribution, and then discussed the actual gas-liquid two-phase fluid flow behavior of the new fixed valve tray using the two-phase model, explored the influence of various operating parameters and structural parameters on the flow field and performance. Finally we investigated the mass transfer process on the plate by simulating gas liquid two-phase concentration field for the new fixed valve tray using coupled flow and component transfer, we studied the gas-liquid two-phase velocity field, and concentration as well as mass transfer distribution on the tray, and predicted the mass transfer efficiency.In order to be closer to the real situation, we improved the original physical model, and established a model with downcomer and gas pre distribution plates. We also simulated gas liquid two phases flow field for the new fixed valve trays in the full range of operations including leakage, normal operation and entrainment using the improved new model. Our research results indicated that the improved physical model is not restricted by operating status, thus it can be used to simulate two phase flow field under full range of operating conditions. We carried on the research on the operating performance of the tower plate based on the three-dimensional two-phase flow model, and obtained the correlation equation between the pressure drop, liquid leakage and entrainment for the tower plate. We also studied gas-liquid two-phase contact state and optimum operating range for large tower by using hydrodynamic methods at the same time, provided guidance for industrial operations and trays enlargement.The model built in the paper can be used for further research and analysis of gas-liquid two phase flow and mass transfer mechanism on the plate, this research can also provide theoretical support for the structure optimization and engineering enlargement.