填充沸石的大型离子交换柱内流场模拟

Flow field simulation of large ion exchange column filled with zeolite

针对沸石法海水富钾工程化放大中的关键问题,采用Fluent中多孔介质模型对填充沸石的大型离子交换柱内流场进行了模拟研究。主要考察了沸石的孔隙率和颗粒直径、海水进口速度、沸石柱长径比以及柱内形成的沸石层凹坑等条件对离子交换柱内流体流动的影响,结果发现:孔隙率和颗粒直径直接关系到沸石层内流体的速度分布,海水进口速度、沸石柱长径比等条件对沸石层内的流体流动并无显著影响;而在孔隙率和颗粒直径确定的条件下,由于海水冲击形成的凹坑对沸石层内流体影响较大,会在凹坑两侧形成滞留区,进而影响沸石对海水中钾的吸附。根据模拟结果优化了填充材料、设备结构以及工艺等参数,为沸石法海水富钾关键装备进一步扩大规模提供了理论支撑。

Aiming at the key problems in the engineering enlargement of technology for seawater potassium extraction by zeolite,the flow field in the large ion-exchange columns filled with zeolite was simulated by Fluent software with the porous medium model.The influence factors on flow field were studied,including porosity,particle diameter,inlet velocity,length-to-diameter ratio,the pit formed by seawater,and so on.The results showed that the porosity and particle diameter are directly related to the velocity distribution of the fluid in the zeolite layer,while the inlet velocity,length-to-diameter ratio and other conditions have no significant effect on the fluid flow.In addition,under the condition of constant porosity and particle diameter,the pit impacted by seawater has a great influence on the fluid in the zeolite layer by forming retention zones on both sides of the pit,which will affect the adsorption of zeolite for potassium in the seawater.Finally,according to the simulation results,the filling materials,equipment structure and process parameters were optimized.This study provides a theoretical support for the further enlargement of the seawater potassium extraction technology.