Hydrodynamics and mass-transfer characteristics analysis of vapor-liquid flow of dual-flow tray

摘要

In the present study, the behavior and details of vapor-liquid contact on the dual-flow trays (DFTs) were investigated using a 3D CFD model within the two-phase Eulerian framework. The simulation provided good agreement with experimental results, which verified the reliability of the model. Firstly, the operation range was divided into four regimes having different characteristics of flow phenomena, and most attention was paid to the hydrodynamic behavior of froth regime and fluctuating regime due to its importance in operation and structure improvement. Then, the liquid flow characteristics of these two regimes were revealedwith the analysis of velocity profiles and liquid phase distribution contour. Meanwhile, some in-depth picturing of local events of hydrodynamics and mass-transfer performance was also presented through the discussion of cyclohexane liquid volume fraction distribution and vapor-phase mole fraction distribution. The froth regime was proved to have higher and homogeneous point efficiency at bulk zone around the plate center area than the fluctuating regime. Thus, the improvement of DFT should be focused on the restriction of "free-flow" to prolong the froth regime and delay the formation of vortex flow with circulation cells. Finally, an orthogonal wave tray (OWT) was designed and compared with DFT for evaluation of the effect of proposed modifications on the enhancement of tray hydraulics, mass-transfer efficiency and stability.