CFD研究短导流筒对鼓泡塔流体动力学的影响

Influence of Short-Draft Tube on Fluid Dynamics in Bubble Column with CFD

采用双流体模型及k-ε湍流模型模拟研究了短导流筒内构件对鼓泡塔流体力学性能的影响。共模拟了4种鼓泡塔,即简单鼓泡塔和3种安装有导流筒的鼓泡塔,塔径D均为190 mm,导流筒离底距离分别为0.5D、1.0D、1.5D,导流筒直径为0.7D,长度为1.0D。结果表明,简单鼓泡塔模拟结果与文献实验值吻合较好;安装导流筒后,导流筒下游气含率和轴向液相速度径向分布更为均匀,并且在不降低整体气含率的情况下,显著提高了鼓泡塔底部的液相轴向脉动速度,将有利于三相鼓泡塔内的固体颗粒悬浮。

Numerical simuulations of gas-liquid flow in a cylindrical bubble column of 190 mm in diameter were conducted to investigate the effect of short-draft tube and its location on hydrodynamic properties using two-fluid model and modified k-ε turbulence model.In the simulations,four cases were assessed.One was a simple bubblecolumn without draft tube while the other three had short draft tubes of 0.7D in diameter,1.0D in length and the clearance from bottom of bubble column of 0.5D,1.0D and（1.5D）,respectively.The simulation results demonstrate that the predicted data from the simple bubble column coincide with the experimental data in literatures.The draft tube flats the radial profiles of the local time-averaged gas holdup and time-averaged axial liquid velocity in the downstream of draft-tube.It is also indicated that the draft tube significantly increases the RMS（root mean square） axial liquid fluctuating velocity at the bottom of the bubble column,which would be beneficial to the solid suspension.