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气升循环分体式MBR的CFD模拟及优化

作者：张晴，樊耀波，魏源送，郁达伟，徐荣乐

单位：中国科学院生态环境研究中心，北京 100085

关键词： X703.1

DOI号：

分类号：

出版年,卷(期):页码： 2013,33(4):107-119

摘要：

基于计算流体力学（Computational Fluid Dynamics, CFD）方法，对气升循环分体式膜生物反应器（Airlift external circulation membrane bioreactor, AL EC MBR）的关键结构参数与水力学参数的相关关系进行了模拟、优化和敏感性分析。研究结果表明，增加气液混合高度和曝气元件数量可提高混合液的混合程度及膜面流速、剪切力分布的均匀性，有利于膜污染控制；曝气器位置升高会使MBR流场分布的均匀性下降；混合液粘度的增加会降低混合液循环流速，但使膜组件中气液混合流的均匀度提高。在MBR膜组件中存在着混合液流速和剪切力分布中部区域高外部区域低的不均匀性，这种不均匀性是导致膜有效利用面积降低和水处理成本升高的重要流体力学因素。
关键词：计算流体力学；气升循环分体式膜生物反应器；构型优化；敏感性分析；膜污染控制

Simulation and optimization of airlift external circulation membrane bioreactor (AL EC MBR) was performed using computational fluid dynamics (CFD) in this paper. Four cases of MBRs withdifferent configurat- ions were simulated and the sensitivity analysis of their impacts on the velocity, shear stress, circulation rate of mixture in the MBRwere presented. The results showedthat larger distance from diffusers to membrane modules(height of gas-liquid mixing zone)was helpful to improvethe velocity and shear stress at the membrane surfaces for membrane fouling control;the distribution of shear stress at the membrane surface in the membrane tank with 3 diffusers wasmore uniformthan that with2 diffusers;higher position of the diffusers wouldresult inmore fluid dead zones under the diffusers in the membrane tank.It was also notedthat higher viscosityof the mixture in the
MBR will lower the circulation rate between the membrane unit and the aeration tank, but on the contrary,the distribution of air-liquidflowingover the membrane surfaces appeared moreuniform.However, the fluid velocity and wall shear stress are always higher at the centralsheets and much lower at the side ones in membranemodule.Thenon-uniformity of gas-liquid flow though the channelsbetween the membrane sheets isone major reason to lose effectivefiltration area of membranes,to lose productivity of treated water and to result in high energy consumptionforMBR application.

基金项目：

国家自然科学基金“MBR 流场、传质与能耗的相互关系研究”（51278483)，环境模拟与污染控制国家重点联合实验室（环境水质学实验室）课题“计算流体力学（CFD）及其在膜生物反应器技术创新中的应用研究”。

作者简介：

张晴（1987—），女，湖南湘潭，硕士生，研究方向为计算流体力学（CFD）在膜生物反应器（MBR）中的研究应用。E-mail: zhangqing210@mails.gucas.ac.cn。*通讯作者，E-mail: ybfan@rcees.ac.cn

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