旋转流强化管式膜微滤的研究评述

浓差极化和膜污染是阻碍微滤广泛应用的关键难题 ,在认识理解颗粒迁移沉积和过滤速率下降的基础上 ,本文对旋转流管式膜微滤进行了一定的探讨分析。     

旋转流强化管式膜微滤过程中分离因数研究

分离因数是影响旋转流强化管式膜微滤过程的关键操作变量之一。本文首先对管式膜分离器内分离因数的分布特征进行了研究,然后,不仅从理论上研究了分离因数对过滤过程行为的影响,而且进行了探讨分离因数对过滤性能影响的试验研究。结果表明,管式膜分离器内分离因数沿轴向从顶部到底部呈迅速减小的分布特征;分离因数的增大,可使过滤过程推动力提高,并使外旋流时过滤过程中固相颗粒不易向膜面迁移并沉积,但加剧了内旋流时过滤过程中固相颗粒向膜面迁移并沉积的趋势;在悬浮液固相浓度保持一定时,过滤通量随分离因数的增大而提高     

管式膜微滤处理电厂循环冷却水的应用研究

结合工程实例,介绍了微滤技术处理电厂循环冷却水的工艺过程和所采用的装置,并重点分析了出水浊度和SD I两个水质指标。工程运行实践证明,微滤技术处理电厂循环冷却水,在技术、经济和社会效益方面均具有明显的优越性。     

肇转流强化管式膜微滤过程中分离因数研究

分离因数是影响旋转流强化管式膜微滤过程的关键操作变量之一,本文首先对管式膜分离器内分离因数的分布特征进行了研究,然后,不仅从理论上研究了分离因数对过滤过程行为的影响,而且进行了探讨分离因数对过滤性能的影响的试验研究,结果表明,管式膜分离器内分离因数没轴向从顶部底部呈迅速减小的分布特征;分离因数的增大,可使过滤过程推动力提高,并使外旋流时过滤过程中固相颗粒不易向膜面迁移并沉积,但加剧了内旋流时过滤过     

旋转切向流PA管式膜微滤试验研究

实验研究了旋转切向流聚丙烯PA管式膜微滤。通过建立的旋转切向流强化微滤实验装置系统，测定了旋转直线切向流和旋转圆弧切向流PA管式膜在不同SiO2悬浮液农度和不同流体压力下的膜通量随时间的变化曲线。实验研究结果表明，旋转切向流强化微滤不但节能，而且系统结构简单。     

十字流微滤过滤机理研究评述

近年来，膜分离过程中的十字流微滤机理研究在国外非常活跃，在预测过滤速率，动态滤饼的形成，提出了一些新观点和新的机理，加深了对十字流过滤通量下降和膜污染的认识和理解。本文介绍了这些理论和实验研究的成果。     

强化十字流微滤研究进展及评述

膜污染是阻碍十字流微滤广泛应用的关键难题,在认识理解过滤速率下降和颗粒迁移沉积的基础上,本文介绍了近年来国内外在强化十字流微滤方面的研究状况和成果。     

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     

微滤,超滤过程中的膜污染与清洗

本文综述了在微滤和超滤过程中，膜污染的影响因素，防止膜污染的措施的清洗方法的选择，指出料液粒子或溶质尺寸，膜结构以及膜与溶质间的相互作用都和膜污染程度有关；通过膜孔径，膜材料，膜结构，组件结构，料液温度，流速和压力的控制可以减轻或控制污染。     

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。     

Migration and Deposition of Submicron Particles in Crossflow Microfiltration

Abstract

The migration and deposition of submicron particles in laminar crossflow microfiltration is simulated by integrating the Langevin equation. The effects of operating conditions on the particle trajectories are discussed. It is found that the Brownian motion of particles plays an important role in particle migration under a smaller crossflow velocity of suspension or a smaller filtration rate. Based on the simulated trajectories of particles, the transported flux of particles arriving at the membrane surface can be estimated. The particle flux increases with an increase of filtration rate and with a decrease of particle diameter; however, the effect of crossflow velocity on the particle flux is not obvious. The forces exerted on particles are analyzed to estimate the probability of particle deposition on the membrane surface. The probability of particle deposition increases with an increase of filtration rate, with a decrease of crossflow velocity, with a decrease of particle diameter, or with an increase of zeta potential on the particle surfaces. The simulated results of packing structures of particles on the membrane surface at the initial stage of filtration show that a looser packing can be found under a larger crossflow velocity, a smaller filtration rate, or a smaller diameter of filtered particles. Crossflow micro-filtration experiments are carried out to demonstrate the reliability of the proposed theory. The deviation between the predicted and experimental data of filtration rate at the initial period of filtration is less than 10% when the Reynolds number of the suspension flow ranges from 100 to 500.     

Dimensional Analysis of Crossflow Microfiltration Data

Abstract

A new approach to correlating crossflow microfiltration (CFMF) data based on dimensional analysis is presented. The steady state flux was assumed to be a function of the trans‐membrane pressure (ΔP), the crossflow velocity (u), the particle concentration (c), filtrate viscosity (μ), and membrane resistance (R _m). Correlations of the form J/u=K(ΔP/cu ²) ^a (ΔP/μuR _m) ^b were tested on three sets of published data: one for CFMF of dried yeast suspensions in a laminar flow hollow fiber module, one for dried yeast suspensions in a turbulent flow tubular module and one for suspensions of latex particles in a laminar flow flat sheet module. The R ² values for the fits of the correlations to the data were 0.98, 0.94, and 0.91 respectively.     

颗粒粒径和膜孔径对陶瓷膜微滤微米级颗粒悬浮液的影响

通过测定颗粒悬浮液通过陶瓷微滤膜时的参透通量及污染阻力,确定了陶瓷膜处理微米级颗粒悬浮液时,颗粒粒径和膜孔径对微滤过程的影响和膜污染机理,获得了微米级颗粒悬浮液微滤过程中膜孔径的选择方法。     

Cross-Flow Microfiltration of Bacillus Subtilis Broths under Various Culture Times

Bacillus subtilis broths under different culture times are filtered in a cross-flow microfilter. The operating condition effects, such as cross-flow velocity, transmembrane pressure, and broth culture time, on the filtration flux, cake properties, and extracellular polymeric substances (EPS) transmissions are discussed thoroughly. The culture broths contain B. subtilis cells and EPS which is characterized as polysaccharides (hydrocarbons) and proteins. An increase in broth culture time leads to higher concentrations of cells, soluble and extractable EPS. The total protein to polysaccharide concentration ratio in the broths is ca 0.2. However, the soluble polysaccharide concentration is 10-fold higher than that of soluble proteins. The filtration flux increases with increasing cross-flow velocity or transmembrane pressure. However, the impact of cross-flow velocity is more significant. The filter cake resistance formed by B. subtilis cells and EPS flocs plays the most important role in determining the overall filtration resistance. The mass and average specific filtration resistance of cake can be estimated using a force balance model and empirical equations. The cake structure and thickness are analyzed using SEM. A thicker and more compact cake may be formed under longer broth culture time. Most soluble polysaccharide and protein molecules have the opportunity to penetrate through the cake and membrane into the filtrate because the solute transmissions are measured as high as 0.75–1.0. The influences of operating conditions on the polysaccharide and protein transmissions are negligible. Therefore, to enhance filtration flux by increasing transmembrane pressure or cross-flow velocity is beneficial to improve separation efficiency, especially by increasing cross-flow velocity.     

Microfiltration of Emulsified Oil Wastewater

Hydrophilic polyvinylidenefluoride (PVDF) membranes were employed for emulsified oil wastewater treatment. The best operating conditions for optimum flux of water, which penetrates through the membrane and rejection (prevention of oil droplets from passing though the membrane) were obtained. Concentration and pH effects on flux and rejection were determined. Increase of weight concentration caused flux decline due to the formation of a thick layer on the membrane surface. However increasing the concentration increased rejection. The pH effects were complex. By increasing the acidity of the feed, rejection was reduced.     

陶瓷微滤膜制备水包油型乳液的研究

乳液制备一直是化工领域中的一个重要的研究课题,本文选择水－正丁醇实验体系,以十二烷基碘酸钠为乳化剂,分别采用０．２μｍ和０．８μｍ的陶瓷膜为分散介质制备水包油型乳液。实验研究了压力、连续相流量等因素对乳液粒径大小、分布和分散相通量的影响。结果表明,用微滤膜可以制得分布均匀的乳状液。微滤膜的孔径较小时,连续相流量和膜两侧压差对于乳液粒径和粒径分布没有明显的影响;当膜孔径增大后,乳液滴的直径分布变宽,     

Effect of membrane morphology on rising properties of filtration resistance in microfiltration of dilute colloids

The effect of membrane morphology on the flux decline behaviors in dead‐end unstirred microfiltration of very dilute colloids of polystyrene latex was examined using mixed cellulose ester and cellulose acetate membranes with interconnected tortuous pores and track‐etched polycarbonate membranes with uniform straight cylindrical pores. The plots of reciprocal filtration rate against the filtrate volume per unit membrane area for the former two membranes exhibit concave downward curves in the initial period when the membrane pore blocking is significant, whereas the plot for the latter shows a concave upward curve in that period. The former results were described by a serial resistance model consisting of the initial membrane pore blocking followed by filter cake growth, and the latter was represented by a parallel resistance model in which the pore blocking and cake growth develop simultaneously from the beginning of filtration. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3511–3522, 2017