基于合成纤维过滤技术的评述

概要评述了国内外合成纤维过滤技术的研究现状和应用前景，从积泥形态学阐述了纤维滤料的过滤机理，比较了纤维滤料与传统石英砂滤料的过滤特性。通过分析滤料形状和过滤器的结构讨论了各类纤维过滤装置的特点。报导了纤维过滤技术在工业给水，地下水，工业废水处理中的应用结果。实践证明；纤维滤料比传统的石英砂滤料具有质地软，强度高，水的阻力小，过滤速度快，截污容量大，易清洗等特点，对今后的研究工作提出了一些建议。     

纤维过滤技术在水处理中的研究进展综述

作为一种新兴的水处理过滤技术,纤维过滤技术凭借诸多优点逐渐成为研究热点。从纤维过滤技术特点和常见的纤维过滤器两个方面,介绍了纤维过滤技术的基本情况。再从工业污水、市政污水、饮用水、海水淡化四个方面详细论述了纤维过滤技术在水处理中的应用。最后从改进滤料和改进纤维过滤器两个方面论述了纤维过滤技术的研究趋势。     

长纤维高速过滤器的运行特性与性能优势

通过对净水厂沉淀出水和长江源水的过滤试验,并与传统砂滤及已在实践中应用的两类纤维过滤器进行对比,证实了自行研制的长纤维高速过滤器的性能优势。该型过滤器在结构上的突破性改进,使纤维过滤技术更趋成熟和高效,对推动纤维过滤技术的发展和提高我国水处理水平均具有重要意义。     

YG Ⅳ型浮动纤维高效过滤器的应用

ＹＧⅣ浮动纤维高效过滤器是一种新型的无囊纤维过滤器,内部结构简单,滤料采用丙纶膨化变形长丝。该设备集“逆粒度”深层过滤和横流过滤的特性为一体。该过滤器入口水浊度≤２０ｍｇ／Ｌ时,出口水浊度≤１ｍｇ／Ｌ;正常运行流速３０－６０ｍｇ／ｈ;在入口浊度５０ｍｇ／Ｌ左右,流速３０ｍｇ／Ｌ时,运行周期为２４ｈ以上。     

高效纤维过滤器积泥形态学的研究

根据高效纤维过滤器滤料滤层的特点,分析了其变空隙滤层形成的原因,并借助扫描电子显微镜对纤维束滤料的泥形态进行了研究,发现了纤维的积泥“壳层”结构和“树枝”构型,对积泥表面结构特征的观测,提出了过滤后期的渗透现象,最后对积泥孔隙率进行了测定。     

佛山恒益发电有限公司GXF-型纤维过滤器改造设计

该公司纤维过滤器未能考虑滤料的污染,导致其纤维密度在运行时均匀,反洗效果不明显,对处理设备造成一定影响,需进行改造成GXF-型纤维过滤器。     

均匀设计法在滤料过滤性能研究中的应用

以滑石粉作为试验粉尘,以1#、3#中空纤维滤料作为过滤介质,对高效纤维过滤器的性能进行了研究。采用均匀设计法考察了气体含尘浓度、过滤风速、滤料压缩率和过滤时间四个因素对过滤器阻力降和过滤效率的影响。利用DPS数据回归处理方法建立数学模型,确定出试验范围内的优化工艺条件:对于1#滤料,在气体含尘浓度0.68 g/m3,过滤风速0.5 m/s,滤料压缩率16.7%,过滤时间10.3 min时,阻力降为172 Pa,过滤效率为99.993%;对于3#滤料,在气体含尘浓度0.5 g/m3,过滤风速0.5 m/s,滤料压缩率15.4%,过滤时间3 min时,阻力降为493 Pa,过滤效率为99.992%。     

上海石化水厂工艺的改进与生产优化

针对受污染河水有机物、氨氮、锰含量高的特点,采用新型的涡旋混凝技术、沉淀墙技术及纤维束滤料过滤技术与传统工艺和均质滤料过滤技术进行平行对比。实验显示,涡旋混凝＋沉淀墙沉淀＋纤维束滤料过滤的组合工艺对类似水厂的工艺改造能达到较为理想的水处理效果。     

静电增强纤维过滤技术的研究进展

综述了静电增强纤维过滤技术的发展历史以及国内外研究进展;介绍了Apitron静电袋式过滤器、TRI棒帷电极电场增强袋滤器、中心电场袋式除尘器、混合式电袋除尘器、静电增强空气过滤器的结构、特点及其应用;指出静电增强纤维过滤技术是一种高效低阻的过滤除尘方式,但在处理高浓度的工业烟尘时,粉尘的积聚使静电作用产生负效应,限制了该技术的发展及应用。建议通过提高静电增强作用,提高过滤材料的静电性能和过滤性能,保持过滤材料高效的驻极状态,应用高效清灰方式,来进一步拓展静电增强纤维过滤技术的应用。     

纤维滤料与石英砂过滤海水的对比试验

预处理在海水淡化过程中占有重要地位,在海水淡化的预处理工艺中,过滤过程一般不可省略,目前海水过滤工艺中应用最多的仍是传统的石英砂滤料,存在滤速低、易堵塞、过滤周期短等缺点。本文采用纤维球和彗星式纤维滤料进行直接过滤海水试验,通过与石英砂滤料对比,考察纤维滤料在海水过滤净化中的使用效果。试验结果表明：对于石英砂滤料,当滤速为15 m/h时,过滤出水浊度小于5.0 NTU;当滤速增大到20 m/h时,过滤水头损失快速增高,过滤周期仅为2 h。对于纤维滤料,当滤速为20 m/h时,过滤出水水质稳定,出水浊度小于2.0 NTU,过滤周期可达50 h以上。相对于石英砂滤料,纤维滤料在比表面积、过滤阻力、截污能力等方面都优于传统滤料,更适用于海水的高效净化处理。     

Filtration Efficiency of Non-Uniform Fibrous Filters

Although theoretical models of the filtration efficiency of fibrous filters are typically based on a single type of fiber in an ordered array, many actual fibrous filters comprises fibers that are inherently randomly distributed. It is desirable to be able to estimate the filtration efficiency of such non-uniform fibrous filters from their composition arrangement and the filtration property of individual fibers. Toward that end, we approximate the filter system as a series of cells comprising individual fibers with random distribution, deviating from the homogeneity assumption in the classical models. With better characterization of the filter structure based on the Voronoi diagram, we theoretically revisit filtration efficiency by the top-down (TD) approach and the bottom-up approach. The proposed models are compared with the existing experimental and numerical results under different fiber volume fractions, indicating the high accuracy of the TD model for the filtration of submicron aerosol particles. The influence of the degree of randomness of fiber distribution on filtration efficiency is also quantified.

Copyright 2015 American Association for Aerosol Research     

Application of nanofibers to improve the filtration efficiency of the most penetrating aerosol particles in fibrous filters

Conventional, mechanical fibrous filters made of microfibers exhibit a local minimum of fractional collection efficiency in the aerosol particle size-range between 100 and 500 nm, which is called the most penetrating particle size (MPPS). Simple theoretical calculations predict that this efficiency may be significantly increased using nanofibrous media. The main objective of this paper is an experimental verification of these expectations and simultaneously checking whether this anticipated gain in the filtration efficiency is not overpaid with an excessive pressure drop. For this purpose we developed a modified melt-blown technology, which allowed us to produce filters composed of micrometer as well as nanometer sized fibers. One conventional microfibrous filter and five nanofibrous filters were examined. The complete structural characteristics, pressure drop and efficiency of removal of aerosol particles with diameters 10-500 nm were determined for all media. The results of the experiments confirmed that using nanofibrous filters a significant growth of filtration efficiency for the MPPS range can be achieved and the pressure drop rises moderately. Simultaneously, we noticed a shift of the MPPS towards smaller particles. Consequently, the quality factor for bilayer systems composed of a microfibrous support and a nanofibrous facial layer was considerably higher than this one for a conventional microfibrous filter alone. Additionally, it was found that utilization of many-layer nanofibrous filters combined with a single microfibrous backing layer is even more profitable from the quality factor standpoint. Comparing experimental results with theoretical calculations based on the single-fiber theory we concluded that for microfibrous filters a fairly good agreement can be obtained if the resistance-equivalent fiber diameter is used in calculations instead of the mean count diameter determined from the SEM images analysis; in the latter case, filtration efficiency computed theoretically is slightly overestimated. This is even more evident for nanofibrous media, suggesting that in such case a structural filter inhomogeneity has a strong influence on the filter efficiency and its resistance and one should strive for minimization of this effect manufacturing nanofibrous filters as homogeneous as possible. We can finally conclude that fibrous filters containing nanofibers, which are produced using the melt-blown technique, are very promising and economic tools to enhance filtration of the most penetrating aerosol particles.     

Penetration of Monodisperse,Singly Charged Nanoparticles through Polydisperse Fibrous Filters

The article presents experimental results and theoretical analysis of aerosol nanoparticle penetration through fibrous filters with a broad fiber diameter distribution. Four fibrous filters were produced using the melt-blown technique. The analysis of the filters’ SEM images indicated that they had log-normal fiber diameter distribution. Five kinds of proteins and two types of silica particles were generated by electrospraying and were then classified using a Parallel Differential Mobility Analyzer to obtain well-defined, monodisperse, singly charged challenge aerosols with diameters ranging from 6.3 to 27.2 nm. Particle penetration through the filters was determined using a water-based CPC. Experimental results were compared first with predictions derived from the classical theory of aerosol filtration. It is demonstrated that it is inappropriate to apply it to the arithmetic mean fiber diameter, as this results in turn in a huge underestimation of nanoparticle penetration. A better, but still unsatisfactory agreement is observed when that theory was used together with the pressure drop equivalent fiber diameter or when the Kirsch model of nonuniform fibrous media was applied. We show that the classical theory applied to any fixed fiber diameter predicts a stronger dependence of nanoparticle penetration on the Peclet number as compared to experimental data. All these observations were successfully explained by using our original partially segregated flow model that accounts for the filter fiber diameter distribution. It was found that the parameter of aerosol segregation intensity inside inhomogeneous filters increases with the increase in particle size, when the convective transport becomes more pronounced in comparison to the diffusive one.     

Hydraulic resistance of a deformable layer of fibrous material

Filtration of spinning solutions, spinning bath, and finishing solutions through a layer of fibrous material is widely used in different chemical fiber plants. In finishing of textile fibers on spools and cakes, the liquid is filtered through a layer of fiber attached by winding. At the same time, filtration is through a layer of unattached, freely packed fibrous material with random orientation of the individual fibers or through layers of nonwoven material in filtration on filters with a metal — gauze — asbestos gravity layer, in fiber finishing or modification processes, and in processes involving ion-exchange, chemisorption, and catalytically active fibrous materials.Moscow State Textile Academy. Translated from Khimicheskie Volokna, Vol. 25, No. 1, pp. 13–15, January–February, 1993.     

原液着色腈纶工业化生产技术

介绍了原液着色腈纶工业化生产技术,从着色剂的调配、分散、贮存、过滤,着色剂与原液的共混, 有色原液的脱泡、过滤、纺丝,有色污水的处理等方面进行了阐述,探讨了原液着色腈纶质量的影响因素,指 出应大力研究原液着色腈纶技术并开发具有高附加值的原液着色腈纶。     

纤维材料过滤理论的研究进展

以单纤维模型为基础,介绍了纤维过滤理论的研究方法,阐述了单纤维过滤机理,综述了国内外纤维过滤理论的发展及其最新进展,给出了过滤材料的效率与压降计算公式,分析了理论研究过程中存在的问题,并对纤维理论的发展趋势做了初步预测。     

COMPARISON OF DATA FROM MODEL FIBER FILTERS WITH DIFFUSION, INTERCEPTION AND INERTIAL DEPOSITION MODELS

Experiments are carried out using special filters with known structural characteristics to study the stationary phase of filtration of liquid aerosols by fibrous filters in the diffusion, interception and inertial regimes. In the domains of diffusion and interception, a comparison made with published models has enabled the selection of two relationships correctly describing these mechanisms both in the slip and continuum regimes. On the other hand, in the inertial domain, an empirical correlation has been established for the single fiber impaction efficiency for viscous flows. All our results have been validated by measurements on an industrial filter.     

短纤维增强复合过滤管的制备

以硅酸铝纤维和硅灰石为主要原料,硅溶胶为粘结剂,通过真空抽滤成型,低温干燥,制成短纤维过滤管。用SEM、XRD等测试方法对短纤维过滤管进行表征。结果表明:所制备的短纤维过滤管孔径在20～50μm;气孔率≥75%;具有良好的透气性能;抗热震性能强。     

纤维过滤介质过滤压力损失理论计算

为便于计算纤维过滤介质过滤压力损失,对目前各种纤维过滤介质过滤压力损失理论计算公式及半经验公式进行分析计算,将理论计算结果与实验测试结果进行对比分析发现各种理论计算结果普遍相偏大,需要对纤维的非均匀分布进行修正,修正后的大部分计算结果与实验结果基本吻合,同时对理论计算公式的鲁棒性进行了分析。计算结果准确性和鲁棒性兼顾的理论计算公式,较适宜于实际过滤材料压力损失的预测。     

静电纺丝法制备聚合物功能纤维的研究进展

静电纺丝是一种可以直接、连续制备聚合物纳米纤维的新方法。通过静电纺丝法制备的直径在几纳米到几百纳米的纤维在很多领域都有潜在的应用。简单介绍了静电纺丝的原理、发展以及在各领域的应用前景,综述了静电纺丝纤维作为功能材料在吸附过滤、导电导热和保温隔热等方面的应用,并对静电纺丝技术在制备聚合物纳米纤维功能材料方面的发展前景作出了展望。