基于液体弥散理论的规整填料塔液体扩散数值模拟

Numerical simulations of liquid spreading in structured packed column based on liquid dispersion

规整填料塔内液体弥散规律的研究对于气液吸收塔的布液装置设计、填料高度确定以及填料类型优选具有重要理论意义,目前关于液体弥散机理的理论描述和模型建立较为有限,本文为实现填料塔内液体扩散现象的准确预测,引入液体弥散机理。规整填料采用多孔介质简化,在考虑了机械弥散力、气液拖曳力、多孔介质阻力等基础上建立了二维CFD模型,模拟结果与实验结果吻合较好。在此基础上研究了液体扩散系数S、气体入口速度和液体入口速度对液体分布的影响。通过研究得出液体弥散机理中毛细管弥散作用影响较小,主要以机械弥散作用为主;液体扩散系数和液体入口速度对液体分布的影响显著,S/Dr的最佳比例为2,气体入口速度对液体分布影响很小。研究结果对其他类型填料的模拟研究有重要借鉴作用。

It is of great theoretical importance to study on liquid dispersion in structured packed columns in the design of liquid distributing devices,the height of the packed beds and the optimum choice of packing types. However,the theoretical description and mathematical model about liquid dispersion are limited. In order to predict liquid spreading in packed column accurately,the liquid dispersion mechanism was introduced. The porous media model was used to simplify the complex structured packing geometry to a homogeneous porous material and a 2D axisymmetric CFD model considering mechanical dispersion force,inter-phase drag force and porous resistance force was presented. The numerical simulations were in good agreement with the experimental results. Then,the effects of liquid spreading factor S,gas inlet velocity and liquid inlet velocity on liquid flow distribution were analyzed. Mechanical dispersion played a key role in liquid dispersion and capillary dispersion can be neglected. Liquid spreading factor and liquid inlet velocity were crucial to liquid distribution in packed columns and the best radio S/Dr was 2. However,gas inlet velocity will not impact liquid distribution in packed column. This study demonstrated its great importance in the numerical simulations in structured packed columns filled with other packing types.