膜洗滤过程模型的在线优化策略及其应用

基于恒收率的时间优化模型,利用膜洗滤过程中在线反馈的数据,创新性地提出"走一步看一步"的优化策略,拓展得到了洗滤过程的即时优化模型。结果表明,采用该模型能够解决膜洗滤过程顶洗起点的在线判断问题,避免了为获取相应参数值进行的离线测试实验,能够为工业生产膜洗滤过程的在线优化与控制提供关键理论支撑。     

微滤过程阻力分析及过滤速率

以膜分离基本理论为基础,依据实验结果,研究微滤过程中微粒在膜材料上的吸附和沉积及其对膜透过液流动的影响,建立了吸附阻力和沉积层阻力随时间变化的关系式,就各项阻力对膜分离过程的影响情况进行了分析,并提出了减小这些阻力的途径。在分析膜分离阻力基础上,本文提出了计算微滤膜通量的数学模型,计算结果的平均偏差为５．９％,明显优于同类模型。     

膜淤塞对微滤的油水分离性能的影响

本文报道了用微滤分离乳化含油废水的研究，利用微滤过程中膜淤塞的特点，显著地提高了油水的分离效率，同时维持较高的水透过率。文章讨论了油水分离的机理，并根据实验结果提出流体中适当的油粒粒径分布，是获得较好分离效果的重要条件。本研究表明了在一定下，可以用水透过率较高、操作成本降低的微滤取代超滤。     

滤洗机隔膜泵使用及相应集液罐液位问题

在粉体滤洗过程中,磁力泵损坏频繁,影响了生产连续性。隔膜泵以压缩空气为动力源,具有耐腐蚀、防爆以及无须电源等优点。但气动隔膜泵的使用也导致脉冲震动对设备、管道产生冲击,造成管道焊缝、设备固定螺栓松动等问题,其中最多的故障就是集液罐液位偏高。本文对滤洗机隔膜泵使用及相应集液罐液位问题进行研究,以期为相关领域的研究提供参考。     

管式膜十字流微滤过程分析

分析了管式膜器中过滤悬浮液从膜管外壁向内壁渗透过滤的过程。以流体力学分析为基础 ,利用力平衡原理和多孔介质渗透定律 ,分析了该结构的过滤特性和滤饼形成特点及规律。     

生物絮凝-砂滤处理洗毛废水的研究

本文采用生物絮凝代替原工艺混凝气浮部分，COD、SS去除率迭80％以上，且处理费用低，无二次污染，有利于羊毛脂回收。经生物絮凝处理的洗毛污水，直接经砂滤，总COD、SS去除率可达90％以上，出水透明。     

连续微滤分离膜和硫酸铝混凝除氟的研究

天津经济技术开发区污水处理厂二级出水的氟离子质量浓度为1.8-3mg／L,研究去除二级出水中氟离子对超标的地下水或其他高氟水的开发、利用具有重要意义,作者主要研究了硫酸铝混凝除氟工艺,并提出和探讨连续微滤膜分离技术(CMF)和铝盐混凝组合除氟的新工艺。CMF系统出水中氟离子质量浓度小于1mg／L,系统出水的SDI值小于3,悬浮物质量浓度低于5mg／L,浊度低于0．5NTU,实验结果令人满意。     

压力驱动膜过程在饮用水处理中的应用

膜分离过程是一种选择性高、操作简单、能耗低、无二次污染的物理分离技术 ,近三十年来发展迅速 ,已在各个领域得到了广泛应用。本文综合介绍了国外压力驱动膜过程在饮用水处理中的应用情况     

电场作用下的十字流膜滤初探

本文根据现代膜过滤技术中膜滤速度低下的原因，提出了附加电场的初步试验结果。试验研究表明直流电场会提高膜滤速率。而且有一个临界场强Ｅ＿ｃ存在，当所加电场略高于此值时将获得最佳的膜滤速率     

旋转切向流管式膜器的参数设计与优化研究

旋转切向流强化膜微滤是近几年提出的一种新的强化方法 ,它把水力旋流器的作用原理引入到管式膜微滤中 ,从而改进了膜器结构和悬浮流体进入膜器的方式 ,提高了膜通量 ,降低了膜污染 ,本文分析和探讨了旋转切向流膜器的结构参数与操作参数 ,给出了膜器结构设计与优化方法     

Optimal design of split partial second pass reverse osmosis network for desalination applications

Reverse osmosis (RO) network design problem is presented in this study for seawater desalination. The RO pressure vessel is multiple spiral wound modules connected in series. We exploit in this study the RO pressure vessel operation by considering stream property variations within the pressure vessel itself. The design problem allows extraction of high‐quality permeates from different locations along the pressure vessel length. Superstructure optimization is adopted to model the RO network in order to find: (1) optimal arrangement of the process units, (2) optimal permeate extraction locations, and (3) production of several permeate streams with different qualities. Several case studies are presented to show the applications of the proposed mathematical programming model. In general, lower treatment cost and higher permeate recovery can be achieved by allowing permeate extraction streams from the RO pressure vessels. © 2013 American Institute of Chemical Engineers AIChE J 60: 520–532, 2014     

Concentration polarization in a narrow reverse osmosis membrane channel

Concentration polarization in a narrow reverse osmosis channel is bounded by the channel height and under the influence of variable transverse velocity. An attempt was made in this article to quantify concentration polarization in such a narrow membrane channel. The transverse velocity in the membrane channel was first determined and its impact on concentration polarization was investigated. Based on the concept of retained salt, analytical equations were developed for the wall salt concentration at an arbitrary point in the narrow membrane channel. Finally, development of concentration polarization in typical reverse osmosis channels under various conditions was numerically simulated and discussed. Interesting results on the details of concentration polarization in the narrow reverse osmosis channel that had never been reported before were revealed with this mechanistic model. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Modeling continuous electropermutation with effects of water dissociation included

The repeating unit consisting of a cell pair of one concentrate and one feed compartment of an electropermutation stack is modeled. Both the feed and the concentrate compartments are filled with an ion‐exchange textile material. Enhanced water dissociation taking place at the surface of the membrane is included in the model as a hetrogeneous surface reaction. Results from simulations of nitrate removal for drinking water production are presented and comparisons with previous experimental results are made. The influence of both conductive and inert textile spacers on the process is investigated via simulations. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

The effect of particle rotation on the motion and rejection of capsular particles in slit pores

The results from a two‐dimensional computational model describing the motion of capsule‐shaped particles in a slit pore under small Re conditions are reported. Average particle velocities and particle rejection coefficients were determined for capsules with aspect ratios of 2 and 4. Two different approaches were used to characterize particle rotation and hydrodynamic particle‐pore wall interactions. In one approach, all sterically allowed particle orientation angles had equal probability, i.e., infinite rotational diffusion was assumed. In the second approach, particles were allowed to freely rotate in the pore; particle orientations were dictated by hydrodynamic forces acting on the particle surface and rotational particle diffusion was neglected. Minimal lateral migration across the pore was observed for the freely rotating particles. Although particle alignment was observed for the freely rotating particles, rejections predicted from the two approaches were found to be in close agreement. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2828–2836, 2018     

Modeling of CO2 mass transport across a hollow fiber membrane reactor filled with immobilized enzyme

The enzyme‐based contained liquid membrane reactor to capture CO₂ from the closed spaces is a very complicated process with large numbers of interdependent variables. A theoretical and experimental analysis of facilitated transport of CO₂ across a hollow fiber membrane reactor filled with immobilized carbonic anhydrase (CA) by nanocomposite hydrogel was presented. CO₂ concentration profiles in the feed gas phase and the membrane wall were achieved by numeric simulation. The effects of CO₂ concentration, CA concentration, and flow rate of feed gas on CO₂ removal performance were studied in detail, and the model solution agrees with the experimental data with a maximum deviation of up to 18.7%. Moreover, the effect of CO₂ concentration on the required membrane areas for the same CO₂ removal target (1 kg/day) was also investigated. This could provide real‐world data and scientific basis for future development toward a final efficient CO₂ removal device. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Experimental and CFD Modeling Study of Inulin-Type Fructan Purification from a Model Solution by Diafiltration on a Pilot-Scale Unit

Nanofiltration of a model inulin-sucrose solution has been studied using a pilot cross-flow unit. The aim of this work was to evaluate two operation modes: total recycle nanofiltration and diafiltration. Experiments were performed at transmembrane pressures from 0.4 to 1.45 MPa and two inlet flow rates. It was found that inulin purification is feasible within the range of the process conditions set. Furthermore, the sucrose retention coefficient is highly affected by the transmembrane pressure but the inlet flow rate does not affect this parameter significantly. Experimental results were simulated by Computational Fluid Dynamics (CFD) and a good agreement was observed between the predicted and the experimental values.     

Effects of Membrane Parameters on Performance of Vapor Permeation through a Composite Supported Liquid Membrane

Abstract

Support liquid membranes have been used in air dehumidification due to their inherent high mass transfer rates. In this study, the effects of membrane structural parameters on vapor permeation through a LiCl solution based supported liquid membrane are investigated. To aid in the analysis, a mass transfer model has been proposed for moisture transfer through the membrane, which is composed of a supported liquid layer sandwiched by two hydrophobic protective layers. The model takes into account of the resistance in boundary layers, in the protective hydrophobic layers, and in the supported liquid layer. It is a transient model. It also reflects the distributed nature of moisture permeation through the membrane. The results found that the emission rate exhibits a non‐uniform distribution nature on the membrane surface. The structural parameters of the support and the protective layers, such as thickness, pore diameters, and porosity, have great effects on vapor permeation.     

Process Duration and Water Consumption in a Variable Volume Diafiltration for Partial Demineralization and Concentration of Acid Whey

Process duration and fresh water consumption were determined (experimentally and statistically) for variable volume diafiltration (VVD) of cottage cheese through a flat sheet membrane (0.046 m²). The VVD process was performed at two volume decreasing ratios (α = 0.75 and α = 0.5). The VVD-0.75 process lasts much longer than the VVD-0.5 process if the same concentration degree is required. The VVD-0.5 process lasts longer than the VVD-0.75 process if it is aimed to achieve the same purification degree. At low purification degrees, both processes require similar quantities of fresh water, but better demineralization is possible after higher dilution, which is typical of the VVD-0.75 process. The mathematical model applied in estimating the duration of the process proved very accurate, which cannot be said about the fresh water consumption model.