过滤介质滤饼可剥落性研究

本文通过实验研究，考察了滤饼的颗粒性质、饱和度、厚度、操作压差、滤布性质等因素对这过滤介质卸饼性能的影响，提出了评定过滤介质滤饼可剥落性实验方法的建议。     

同质增强型PMIA中空纤维膜污染及其MBR工艺处理城市生活污水

以碳酸钙悬浮液、活性污泥混合液及蛋白溶液作为过滤介质,采用标准堵塞过滤和沉积过滤数学模型预测3 h内膜污染类型,结合膜孔径分布、过滤介质粒径分布和污染阻力分布,研究同质增强型聚间苯二甲酰间苯二胺（PMIA）中空纤维超滤膜污染机理。将同质增强型PMIA中空纤维膜应用于MBR系统处理城市生活污水,监测其长期运行的出水水质;借助场发射扫描电镜和特征X射线能谱仪对比分析水洗和化学清洗效果。研究结果表明,当过滤介质为蛋白时,t-t/V线性相关系数为0.9940,膜污染符合标准堵塞模型;当过滤介质为碳酸钙悬浮液和污泥混合液时,V-t/V线性相关系数分别为0.9733、0.9994,二者较为符合沉积模型。应用于MBR中的同质增强型PMIA中空纤维膜对COD、NH₄⁺-N、TP的平均去除率分别为97.78%、96.71%、49.81%,出水水质较好。经化学清洗后膜表面元素接近于原膜,清洗效果较佳。     

旋管动态过滤的实验研究

在自行开发的小型旋管压滤实验装置上 ,以清水和白刚玉微粉为物料 ,对旋管动态过滤进行了实验研究。结果表明 ,提高旋管转速反向离心压差增大 ,使清水的透过速率减小 ,转速的变化还会影响沉积滤饼层的厚度和比阻     

Preparation of PVDF hollow‐fiber membranes via immersion precipitation

Porous polyvinylidene fluoride (PVDF) hollow‐fiber membranes with high porosity were fabricated using the immersion precipitation method. Dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidone (NMP) were used as solvent, respectively. In addition, polyvinylpyrrolidone (PVP), lithium chloride, and organic acids were employed as nonsolvent additives. The effects of the internal and external coagulation mediums on the resulting membrane properties were also investigated. The resulting hollow‐fiber membranes were characterized in terms of maximum pore radius, mean pore radius, effective surface porosity as well as wetting pressure. The structures of the prepared hollow fibers were examined using a scanning electron microscope. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1643–1653, 2001     

聚醚砜中空纤维膜的制备

讨论了在二次成形聚醚砜(PES)中空纤维膜的制备中,PES浓度和不同的填充液对中空纤维膜结构和性能的影响。结果发现:随着PES浓度的增大,中空纤维膜的水通量呈下降的趋势,确定了二次成形PES中空纤维膜制备中PES最佳浓度为24%;不同填充液与溶剂之间的相互扩散速率不同,得到了具有不同结构的聚醚砜中空纤维膜。随着填充液压力的提高,纤维的内径、外径增加,壁厚减小,水通量增大,一般填充液压力为0.020MPa。     

循环过程中陶瓷滤材内粉尘沉积规律实验研究

The penetration and deposit of particles within the medium is thought to be one reason that the residual pressure drop of the rigid ceramic filter increase with cycle number. In this study, the change in the microstructure of a single layer ceramic filter candle during filtration-cleaning cycle was observed by scanning electron microscope (SEM) and the resistance property of the filter was monitored accordingly. The experimental results show that there exists a serious dust deposit within the filter medium, especially at the surface region. This should be responsible for the decrease of the filter permeability. The deposit law of dust in the filter medium during filtration-cleaning cycle was then studied by measuring the deposit depth, the deposit amount, the particles distribution within the medium, the size distribution of deposited particles, and so on. Particles migration and fine particles penetration were found to be the main reasons, for which dust deposit within the filter medium became aggravated with cycle number. Based on a differential form of Ergun equation, an expression for the pressure drop of a used ceramic filter was developed with a good agreement with experimental results. Then, the effect of dust deposit on the residual pressure drop was studied at the different face velocities and dust sizes. It was found that face velocity and dust size significantly influence dust deposit within filter medium, and then the operation performance of the filter.     

The Permeability Distribution (PD) Method for Filter Media Characterization

Cake filtration is frequently used for the removal of particulate solids from fluids in industrial processes. The build up of a filter cake is usually accompanied by a decrease in overall permeability of the filter leading to an increased pressure drop over the filter medium. For an incompressible filter cake that builds up on a homogeneous filter cloth (surface filtration mode), a linear pressure drop profile is expected over time. However, occasionally experiments show curved pressure drop profiles. Whereas pressure drop profiles with increasing slope are generally ascribed to cake compression and/or depth filtration, pressure drop profiles with decreasing slopes are only ascribed to inhomogeneities in the filter. Such inhomogeneities can arise due to filter cake patches and/or an inhomogeneous filter cloth itself. In this work a method is proposed that transforms the pressure drop profile of a filter into a permeability distribution (PD) of the filter medium, thus accounting for possible inhomogeneities of the medium. The determination of the PD is looked at as an inverse problem of an integral transformation. The method is applied to experimental filter pressure drop data of laboratory scale jet-pulse cleaned bag filter plants. It is found that even clean filter media can exhibit a significant permeability profile.     

金属丝网过滤器过滤初期阶段压力特性的研究

对5μm刚性金属丝网滤筒过滤初期阶段的压力特性,选用高密度聚乙烯粉料进行了实验研究,主要考察过滤速度和入口浓度对滤袋筒压降的影响。实验结果表明在过滤初期阶段滤筒的过滤压降上升趋势很明显,这种压降的增大主要来自于残余压降。滞留在滤筒内的粉尘改变了丝网内部的流道结构,从而导致了滤筒残余压降的不断升高。过滤速度和入口浓度的增加均可使残余压降增大。最后通过压降组成的分析,提出了滤筒总压降的计算模型。     

NUMERICAL ANALYSIS OF MEDIUM COMPRESSION AND LOSSES IN FILTRATION AREA IN PLEATED MEMBRANE CARTRIDGE FILTERS

A computer model has been developed to simulate the fluid flow in pleated filter cartridges. This model has been used to evaluate the performance and design of pleated cartridge membrane filters. The effects of medium compression, pleat deformation, and pleat crowding are analyzed. At higher flow rates due to the exerted fluid pressure the medium is deformed, which leads to a reduction in the material permeability. Further, due to pleating and bending there is a loss in effective filtration area. The combined effects of compression and reduction in filtration area cause deviations from Darcy's law. To interpret such deviations, permeability models based on the data obtained from the flat sheets of the filter material used in cartridge fabrication have been developed. The incorporation of the permeability model within the main hydrodynamic model determines the percentage loss in filtration area, percentage medium compression, and the pressure drop across the filters. Results of this study have been presented for fiberglass medium. The simulated results have been compared against experimental industrial data for purposes of model validation. The developed simulation tool offers a robust, cost-effective, and user-friendly design and analysis tool for pleated cartridge membrane filters, which can be easily used by engineers in industry.     

一种新型滤料──炉渣滤料性能研究

针对炉渣滤料的过滤性能作了系统的实验研究。实验表明，炉渣滤料具有较大的悬浮物脱除效率和截泥量，且系废料利用，因而具有很大应用价值。在实验的基础上，得到了炉渣滤料阻力损失的模型和过滤模型中的参数，并开发了过滤过程模拟计算软件，可作为新型滤料工艺设计或核算之用。     

Pressure Slip Casting of Graded Coarse Grained Oxide Ceramics for Refractory Applications

In the present study the fabrication of graded coarse grained ceramic bodies for refractory applications was investigated using a pressure filtration cell,which uses pressurized air as the pressure medium. The pressure filtration cell was used to examine the influence of different ceramic raw materials,two dispersants,and of the particle size distribution on the filtration behavior and on the filter cake surface quality. Pressure slip casting of spinel based slips resulted in crack-free filter cakes,while alumina based slips resulted in filter cakes,which always stuck on the used PMMA filter medium. Furthermore,citric acid as an electrostatic dispersant resulted in a much lower filtration cake resistance and hence shorter filtration times than an electrosteric dispersant. A broader particle size distribution with a higher addition of the finest particle fraction caused an increase in the filter cake resistance but also yielded much better surface qualities. Finally,graded filter cakes with three layers of alumina rich magnesium aluminate spinel with a maximum grain size of 3 mm,1 mm,and 0. 5 mm,respectively,were fabricated. The computed X-ray analyzes indicated a perfect bonding between the three layers,which is a significant improvement to previous studies. However,the graded filter cakes exhibited frequently cracks at the bottom,which was probably caused by tensile stresses from the friction of the filter cakes with the pressure filtration cell. This will be further investigated in subsequent studies. The achieved results demonstrate thefeasibility to produce coarse grained oxide ceramics for refractory applications by pressure slip casting,which eventually allows the production of composites with tailored compositions,microstructure and functionality.     

The influence of pleat geometry on the pressure drop in deep-pleated cassette filters

In air filtering applications, a filter's pressure drop at a defined collection efficiency constitutes an important parameter. This paper discusses the variables influencing the pressure drop in air filters featuring deep-pleated filter media. For cassette-type fine filters in accordance with EN 779 or for HEPA/ULPA filters in accordance with EN 1822, the most commonly used media are paper-like materials with a thickness of less than 1 mm, which offer a relatively high resistance to the air flowing through them. Manufacturers accordingly endeavour to accommodate a maximum of filter medium area in a small space. To enable the pressure drops customary in intake, exhaust and re-circulated air filtration to be assured, the filter medium is therefore arranged in narrow, deep pleats. Particularly when large quantities of air are being handled per filter element, it is advantageous to pleat the filter medium in depths of 150 mm to 280 mm. The conversion technique and the resultant pleat geometry exert a crucial influence on the pressure drop concerned.     

对苯二酚生产脱色过程中固液分离技术的应用

针对对苯二酚生产中脱色这一生产环节的过滤过程,在分析了对苯二酚过滤分离的特点基础上,通过系统的实验测定了被分离物料的基本性质,探讨了其过滤分离的方法,并根据生产工艺条件的要求结合加压过滤试验对过滤介质进行了筛选,为生产中选择合适的过滤介质提供了实验依据。     

Impurity diffusion and microstructure in diamonds deformed at high pressures and temperatures

Results of a comprehensive study of the influence of deformation at high-pressure and high-temperature conditions on diamond microstructure and nitrogen diffusion are presented. Selection of the pressure medium allows the introduction of different types of extended defects (dislocations, mechanical twins). Despite clear differences in microstructure of diamonds deformed in variable pressure mediums, the relationship between the deformation and the rate of aggregation of the C to A nitrogen defects is still not clear. In some cases the deformation apparently increases the aggregation rate; in others no effect or even a decrease in the conversion rate was observed.     

聚醚砜中空纤维膜的成形条件与形态结构研究

采用扫描电镜探讨经双向拉伸聚醚砜(PES)中空纤维膜的纺制工艺条件与结构之间的关系。在膜的中部通入填充液,随着填充液压力的增大,中空纤维膜的壁厚明显减小,同时纤维膜表面的孔明显增多。随着凝固浴质量分数的增加,中空纤维膜表面的孔径先减小后增大,而中空纤维膜接近外表面的皮层逐渐变厚。随着凝固浴拉伸率的提高,中空纤维膜在外径不变的情况下壁厚减小,内表面积增加;纤维变薄而且更为致密。     

高分子精密过滤在化工领域中的应用

高分子微孔过滤技术既可适用于高效精密滤饼过滤,也可用作高效精密澄清过滤,它从微孔过滤介质、微孔过滤机结构、精密过滤计算方法等方面改革了传统的精密过滤作业。它具有过滤效率高、可反吹再生、耐腐蚀、操作简单、使用寿命长等特点,在许多化工装置中已获得应用,并取得了显著的经济效益。     

The analysis and design of a both open ended hollow fiber type RO module

The use of seawater desalination plants using RO technology has spread and the scale of the plants has increased. In such a situation, a larger‐sized RO module has been strongly required. The conventional hollow fiber type RO element is a single open‐ended (SOE) structure. That is, one side of the hollow fibers in the modules is opened and the other side is closed. In this SOE structure, the increase in the flow pressure loss of the permeated water which flows in the bore side of the hollow fibers prevents development of a large‐sized (longer) RO element. In this work, a both open‐ended (BOE) element was devised which can reduce the flow pressure loss of the permeated water. It has been confirmed by analysis and experiment that the permeate flow rate of BOE is greater by about 30% than that of SOE. Furthermore, the large‐sized RO module with high volume efficiency was designed using the performance analysis method that was confirmed to be applicable to BOE. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

高温陶瓷过滤管性能退化建模及实时寿命预测

高温陶瓷过滤管由内部孔径较大的支撑体和外部孔径较小的过滤膜双层结构构成,在实际应用中,存在大量粒径较小的粉尘颗粒,会穿过过滤膜沉积到支撑体内部,脉冲反吹无法有效清除. 因支撑体内颗粒沉积及管壁外残余粉尘层不断压缩,使陶瓷过滤管渗透率不断下降,残余压降逐渐增加。本工作基于高温陶瓷过滤管壁内颗粒沉积特性及残余粉尘层压缩不可直接观测的特点,结合贝叶斯估计理论,利用过滤管运行期间采集的残余压降数据,提出一种基于状态空间模型的过滤管性能退化建模方法。该方法能融入最新采集到的残余压降数据,实时对模型参数进行更新,可对陶瓷过滤管的剩余寿命进行实时预测,同时对陶瓷过滤管剩余寿命的失效概率密度分布及陶瓷过滤管的退化状态变化率进行预测。对某高温试验装置及壳牌煤气化装置中的陶瓷过滤管残余压降分析表明,预测剩余寿命准确率随残余压降数据增加而逐渐增加,后期预测准确率高于95%,且陶瓷过滤管退化状态变化率逐渐变小,与陶瓷过滤管残余压降前期增加快后期增加慢的现象一致。     

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。     

低压稳流核桃壳过滤器的开发及在油田废水处理中的应用

为了解决现有核桃壳过滤装置反冲洗憋压、跑料、滤料再生困难的问题,经过分析,根据反冲洗理论,对过滤器进行改造,开发出低压稳流核桃壳过滤器。通过现场测试,证明低压稳流核桃壳过滤器反冲洗压力可以由原来的0.15~0.40 MPa降低到0.03~0.06 MPa,且能够实现罐群水反冲洗,反冲洗效果好,滤料再生效果好。干净的滤料使进水压力由原来的0.15~0.30MPa降到0.10~0.20 MPa,改善了出水水质,含油质量浓度平均<10 mg/L。