海水脱硫散堆填料塔的数值模拟及传质计算

CFD simulation and calculation of mass transfer of random packing columns within seawater desulfurization

采用体积平均法建立了描述散堆填料塔内气、液两相的流动模型;在双膜理论的基础上建立了平均体积传质模型。通过数值计算,获取了在不同液气比下塔内流体速度、孔隙率分布、压力分布及脱硫效率,并就压力损失和脱硫效率与实验值进行了对比,预测值与实验值吻合较好,趋势完全一致。分析填料塔内海水的速度分布矢量图和填料塔中间高度断面上的速度分布图发现,靠近壁面处存在着显著的壁流现象,并在沿流方向上液体有向壁区积聚的趋势,壁流现象变得更严重。由3种填料径向孔隙率分布图可看出,近壁面处的孔隙率明显高于中间区域,表明这是形成壁流的原因所在。

With the volume average method, gas-liquid two-phase flow CFD model is established to describe seawater desulfulrization in random packing column. Based on the two-film theory, the average volumetric mass transfer model is established. By numerical calculation, the flow velocity, porosity distribution, pressure distribution and desulfurization efficiency of different liquid/gas ratio are obtained. Pressure loss arid desulfurization efficiency are compared with experimental data, the prediction results and experimental results are well consistent ,which is exactly the same trend. Combination of seawater velocity vector in packed columns and the velocity profile of the section on the middle high of the paced tower, it is found there is a significant ＇wall flow＇ phenomena,and there is a accumulation trend near the wall along the direction of the liquid flow, and the wall flow becomes much more serious. According to the chart of the three kinds of filler porosity distribution on the radial direction, it can be seen that porosity near the wall is significantly higher than that of the middle region, it is stated that this is the reason for the formation of wall flow.