(93e) CFD Modelling of Bubble Column in Heterogeneous Regime:1D and 2D

Bubble column has been widely applied in many chemical industrial processes, including oxidation, hydrogenation, carbonylation, and Fischer-Tropsch synthesis etc. Depending on states of gas dispersion, two kinds of flow patterns in bubble column were classified: homogenous and heterogeneous. The homogeneous regime occurred at relatively low superficial gas velocities and with uniformly sized bubbles. The heterogeneous regime operated at high superficial gas velocities and characterized by a steep radial profiles of gas holdup and liquid velocity. In this paper, a CFD model was developed for the calculations of gas holdup and liquid axial velocity profile in bubble column in the heterogeneous regime. Two key lateral forces was considered in the model: The lateral lift force and the turbulent diffusion force. In 1D simulation, the balance of these two forces determined gas holdup profile, which was used to compute axial liquid velocity profile. CFD and experimental results agreed very well.In 2D simulation, a new method was developed to deterimine the bubble diameter ,which was used to caculate drag force. Also the two lateral forces were considered. Again, simulation results agreed very well with experimental ones.