减压填料塔内件流体力学模拟及压力降计算分析

Fluid dynamic simulation for internals of vacuum packed tower and analysis of its pressure drop based on CFD

常减压蒸馏装置减压塔的压力降对产品收率和分离效率具有重大影响。除填料的压力降外,塔内件的压力降也是全塔压力降的主要影响因素。文章以某炼油厂的工艺参数为基础,利用计算流体力学软件Ansys12的Fluent模块对塔内件进行流体力学模拟,得到集油箱和槽盘式分布器等塔内件计算流体力学模拟的一般方法。模拟得到的迹线图很好地反映了槽盘式分布器和集油箱内的流体流动情况,塔内件气相动能因子与压力降之间符合二次方阻力模型ΔP=aF2,分析结果表明塔内件的开孔率、槽宽和V型挡板等结构参数是阻力系数a的主要影响因素,在减压塔通常操作条件下,气相黏度对阻力系数的影响可以忽略。该文提供的方法可以分析内件压力降的影响因素,指导塔内件设计,并且计算结果可用于提高减压塔流程模拟的准确性。

In the vacuum distillation unit, the pressure-drop of the vacuum tower has a great impact onproduct yields and separation efficiency. In addition to the structured packing, internals also play a role in pressure drop of vacuum tower. A general method for the computational fluid tion on internals is developed with commercial CFD software significant dynamics （CFD） simula- Ansysl2 Fluent module based on process parame- ters of a commercial vacuum distillation unit （VDU）. Trajectories from simulation have satisfactorily describedthe behaviors of the fluid flow in the distributor and the oil collector. A quadratic resistance model （ △P=aF^2） between F-factor and pressure-drop is established, where the coefficient ＂ a＂ is resistance factor. The results show that the structural parameters of internals （including porosity, slot size and V shape baffle） aremain impact factors of ＂a＂, while in vacuum tower, impact of gas viscosity is negligible. The method benefits the analysis of pressured drop of internals and internals＇ design, and the results can be used to improve process simulation of vacuum tower.