微米级高分子精密过滤技术及其在精细化工、水处理与环保领域的应用

微米级高分子精密过滤既能澄清过滤 ,也能滤饼过滤 ,还能卸干滤饼 ,过滤介质能高效再生 ,耐化学性能好 ,是一种使用寿命长的新型过滤技术。主要介绍了该技术的组成特点及其在精细化工、水处理及环保领域的主要应用。     

二次盐水过滤用的超精密澄清过滤技术

分析了３类可用于二次盐水过滤的超精密澄清过滤技术,介绍了刚性微孔聚乙烯管压滤机连续多年在盐水二次过滤的使用中所取得的主要效果。     

MATHEMATICA在过滤实验数据处理中的应用

在过滤实验中为了从一系列“滤液量-过滤时间”数据(V-θ数据)中获得过滤常数K、Ve,传统的方法是将V-θ数据转化为(△θ/△V-V)数据,再用作图法回归出其线性关系驻兹驻V=驻2KA2 V+KA22 Ve,进而求出相应的过滤参数。将介绍一种新的计算方法,即借助数学软件MATHEMATICA,直接根据V-θ的原始数据回归出二次关系曲线V2+2VeV=KA2兹,从而确定出参数K和Ve的值。本方法比传统方法更精确(尤其是对于有噪音的数据)、简便。     

高效脱水的进展

在查阅大量文献资料的基础上 ,分析了国内外高效脱水技术与设备的发展动态 ,分析了今后的发展趋势。     

新型过滤介质与材料的发展

叙述了目前几种典型的高效新型的过滤介质与材料的结构特性、工作机理和生产工艺,分析了它们各自的优点和应用领域。     

几种常见液固过滤方法的能耗与物耗及改进方向

液固过滤过程中能耗与物耗相当可观,对我国节能减排任务的负面影响不可忽视.分析了四种常见的过滤方法(循环过滤、多级过滤、真空过滤和错流过滤)的高能耗与三种常见的过滤装置与方法(手动板框压滤机,分散的深层过滤器与助滤过滤)的高物耗的概况,并简单叙述了改造的大致方向.     

滤床过滤系数的确定方法

过滤系数λ是表征深层过滤性能的重要参数,用试验的方法测定滤床过滤系数较为复杂。通过试验法和数学模拟法对不同粗细的滤料滤床进行研究,确定其λ的具体值,通过比较两者的结果发现,利用数学模拟法替代复杂的试验方法来确定实际滤床的过滤系数和预测运行状况是简便可行的。     

不同过滤方式下过滤速率衰减模型研究

对真空死端过滤、气压死端过滤、轴向流十字流过滤、旋转流十字流过滤等不同过滤方式下的过滤速率衰减行为进行了系统的研究,建立了相应的过滤速率衰减模型、以及相应模型系数与悬池液浓度、操作压力、雷诺数和欧拉数等影响因素的关系式。结果表明,死端过滤速率衰减模型中过滤速率与时间呈幂函数关系、而十字流过滤速率衰减模型中过滤速率与时间则呈一次函数关系,死端过滤时悬浮液浓度和气压过滤压力对其过滤速率衰减模型系数的影响均呈三次函数关系,在十字流过滤时悬浮液浓度、操作压力以及雷诺数对模型系数ｂ的影响均呈线性关系,轴向流十字流过滤速率衰减模型系数ｂ与欧拉数呈反比,而旋转流十字流过滤时则模型系数ａ与欧拉数呈反比关系。十字流过滤中,旋转流方式同轴向流方式相比,过滤速率衰减趋势较陡,但其初始通量高,在较长时间内都能以高于轴向流过滤通量的状态运行。     

高分子精密微孔过滤机在化工生产上的应用

高分子精密微孔过滤机是一类过滤、排渣、再生与耐腐蚀等性能很优异的新型精密过滤机。本文叙述该类过滤机的主要特点,并系统介绍了其在化工生产上的各种精密滤饼过滤、精密澄清过滤以及各种化工生产废水等领域的主要应用。     

动态膜的形成机理及其水处理性能研究

以陶瓷管为载体,对高岭土动态膜的形成及其污水处理性能进行了详细的研究.实验中采用错流过滤方式涂膜,考查了跨膜压差、涂膜液浓度、错流速度及涂制时间等对动态膜形成的影响.通过对实验数据分析可知,动态膜形成初期10～13 min,膜的形成过程可用标准过滤模型描述,在此期间颗粒堵塞载体膜管孔道,致使渗透液通量急剧减小;之后,膜的形成过程符合滤饼过滤模型,这一阶段颗粒主要在载体膜管内壁面沉积,渗透液通量缓慢下降直至基本稳定.制备的动态膜可用于处理城市污水厂二级出水,动态膜对浊度去除率基本上为100%,对COD也有一定的去除作用.     

An assessment of the conventional cake filtration theory

An assessment of the viability and utility of the conventional cake filtration theory was made by comparing the results based on the conventional theory with those obtained from more exact numerical analyses. The validity of the assumptions on which the conventional theories are based, such as negligible solid motion, constant liquid velocity through a cake and constant and time-invariant wet to dry cake mass ratio was examined. Based on the comparisons, a more accurate procedure of applying the conventional theory was presented.     

离心动态运滤机特性的研究

本文研究了离心动态过滤机的转动速度和过滤速度之间的关系,计算了不同转速下的过滤阻力,提出了离心动态过滤机的过滤方程,对找到离心动态过滤机的最佳工作条件具有指导意义     

HYDRODYNAMIC MODEL AND EXPERIMENTS FOR CROSSFLOW MICROFILTRATION

Crossflow microfiltration, in which a suspension is passed through a pressurized open-ended tube or channel having microporous membrane walls, is an effective means of filtering fine particles from a liquid and is finding increasing application in separations involving microbial suspensions and products. The particles, which are carried toward the walls with the filtrate cross-flow, form a thin cake layer on the membrane surface which does not accumulate substantially but is rather swept along the channel by the tangential flow of suspension. This paper presents a stratified-flow model of this phenomenon which predicts the steady-state permeation flux, and the velocity, pressure, and concentrated particle layer thickness profiles, as functions of the system parameters. In addition, the results of laboratory experiments which used a crossflow microfiltration channel with glass sides are reported. The measured steady-state thickness of the cake layer as a function of distance from the channel entrance shows good agreement with the theory, except for the case of a relatively thick layer when it is believed that a stagnant sublayer had formed beneath the flowing cake layer.     

HYDRODYNAMIC MODEL AND EXPERIMENTS FOR CROSSFLOW MICROFILTRATION

Crossflow microfiltration, in which a suspension is passed through a pressurized open-ended tube or channel having microporous membrane walls, is an effective means of filtering fine particles from a liquid and is finding increasing application in separations involving microbial suspensions and products. The particles, which are carried toward the walls with the filtrate cross-flow, form a thin cake layer on the membrane surface which does not accumulate substantially but is rather swept along the channel by the tangential flow of suspension. This paper presents a stratified-flow model of this phenomenon which predicts the steady-state permeation flux, and the velocity, pressure, and concentrated particle layer thickness profiles, as functions of the system parameters. In addition, the results of laboratory experiments which used a crossflow microfiltration channel with glass sides are reported. The measured steady-state thickness of the cake layer as a function of distance from the channel entrance shows good agreement with the theory, except for the case of a relatively thick layer when it is believed that a stagnant sublayer had formed beneath the flowing cake layer.     

微孔陶瓷膜过滤(三)——陶瓷膜的使用寿命、再生方法、预敷操作及其与有机膜的对比

以平板陶瓷膜为过滤介质的动态旋叶压滤机进行微滤实验，对陶瓷膜的使用寿命、阻塞情况、再生效率、预敷效果等进行了探讨，提出了有效的再生方法，并与有机膜进行了对比实验，得到了对工程实际有指导意义的一些初步结论，显示了用陶瓷膜作为动态旋叶压滤机过滤介质的优越性。     

A MODEL FOR FREENESS MEASUREMENT OF PAPERMAKING SUSPENSIONS

In the pulp and paper industry, it is often necessary to characterize the drainage capability or a pulp on the paper machines. The industry uses a standard measure called the freeness to represent this and other properties for papermaking pulps.

The freeness is the total volume of water discharged from a side orifice of a specific configuration while the pulp suspension drains freely under gravity. In this paper, a model for the gravity filtration of pulp suspensions forming a compressible pulp mat is along with some empirical treatment of the flow is used to model the freeness test. The gravity drainage process is assumed to be described by a cake filtration process with the pressure at each instant being given by the gravity head.

From the model, the critical parameters governing the freeness of a pulp suspension are shown to be the specific surface area and the specific volume of the pulp fibers in addition to the compressibility of the pulp mat. When these parameters are available from independent gravity drainage measurements, the freeness itself can be estimated. Estimated freeness values are in agreement with experimental measurements for pulps which are reasonably free of fines. When fines are present however, they get entrapped within the pulp mats decreasing their permeability. The model predictions are higher than experimental measurements in this case.     

Effect of coagluant dosage and grain size on the performance of direct filtration

The performance of flocculation in direct depth-filtration was assessed in relation to the shear rate and the floc size in the filter pore. Quantitative measurements of the pressure drop of bed, as well as the turbidity and the floc size in the filtrate, and estimation of the shear rate in the filter during filtration were made to investigate the effects of chemical doses and grain sizes on the performance of direct filtration. Furthermore, a method was suggested to determine the porosity in the deposited layer. In this study, the product was estimated to be two to three times that in the initially clean bed after a 6 h operation of the filter using 50–100 ppm of alum. It was also found that the porosity of the deposited layer is very high up to a range of 0.93–0.99. The porosity decreased with the filtering time and filtration rate, and increased with the alum dosage. However, it was only slightly affected by the grain size used in the study.     

砂滤技术在水处理研究中的进展

对砂滤技术进行了简要的概述。从级配、滤料种类、特殊水质等方面对影响过滤的几个重要因素进行了论述。从除浊、除氨氮、除铁锰、除藻等方面详细的论述了砂滤技术的应用现状。对砂滤工艺中存在的问题,从滤料改性、微絮凝过滤、生物强化过滤等方面总结了强化过滤的措施和发展趋势。     

Gas filtration in granular moving beds — an experimental study

An experimental study was conducted of gas filtration in cross-flow moving-bed granular filters. Variables examined included both the gas and solid velocities as well as filter-grain size. The triboelectric effect was found to play an important role in determining the extent of particle collection.     

多级结构静电纺纳米纤维膜在空气过滤领域研究进展

静电纺纳米纤维膜具有纤维直径小、比表面积大、孔隙率高等优势,使其在空气过滤领域具有广阔的应用前景。相比特殊结构的纳米纤维膜,常规的静电纺纤维膜堆积密度大、过滤阻力高,增加了在实际使用中的能源消耗。从静电纺纤维膜结构和过滤性能的角度探讨了高效低阻空气过滤纳米纤维膜的构筑,介绍了珠粒、突起和多孔结构纤维膜在空气过滤领域的研究进展,指出了多级结构静电纺纳米纤维膜是高效低阻空气过滤膜的重点研究方向。