CFD Gas-liquid Simulation Of Combined Oriented Valve Tray

Due to the good performance like high operating flexibility, large throughput etc., combined oriented float valve tray has been widely applied in industrial separation process in recent years. The flow state on tray is directly related to separation efficiency, and through the rational design of internals shape, arrangement etc., non-ideal flow on tray could be effectively improved. So accurately investigation of the two phase flow on tray is essential, and the method of computational flow dynamics (CFD) to make research in this field has been attached much attention. According to the structural characters of trapezoidal and rectangular oriented float valve, the gas-liquid flow on combined oriented float valve tray was simulated with CFD method. The results are as follows:1) Based on the experimental data, liquid volume fraction correlation of combined oriented float valve tray was fitted, which was further applied to establish momentum source for CFD simulation. The correlation is the following:2) Euler-Euler model and (Realizable) k-ε turbulence model were chosen for simulations. On the basis of structural characteristics of trapezoidal and rectangular float valve, the physical model with 0.7m diameter (float valve state assumed to be fully open) was established, and was meshed by mixed grid. Then simulations were performed under air-water system. Clear liquid layer height was applied to verify the correctness of the simulation, and the predicted liquid height from CFD simulation was in good agreement with the results of pressure drop and volume fraction correlations.3) Simulation results of the clear liquid layer height under different conditions were demonstrated and analyzed from X and Y direction. It was found that there were an obvious decline of clear liquid layer height at section of guiding hole and an apparent increase at the anterior and posterior wall of float valve. Under different gas velocity, liquid load and weir height respectively, it was shown that at the region of lower liquid load, liquid load exerted more effect on the liquid layer, an at the region of higher gas velocity, gas velocity exerted less effect on the liquid layer. In addition, the liquid velocity distribution in the X, Y, Z three directions were obtained, and the guiding function of guiding hole to liquid flow was revived and analyzed. Meanwhile, it demonstrated that the float valve locating to arched wall near the outlet weir produced bigger reverse gas momentum, which was not conducive to reduce the liquid layer difference.In this paper, the two-phase flow of combined oriented valve tray was studied and analyzed. The results were expected to provide a reference for the design and optimization of the combined oriented valve trays.