一种过滤回收PTA氧化阶段母液中固体颗粒的方法和应用该方法的过滤器

<正>大连凯信石化科技有限公司开发出一种过滤回收PTA氧化阶段母液中固体颗粒的方法和应用该方法的过滤器。它包括对母液进行过滤,使母液中的固体颗粒积聚成滤饼,使滤饼与母液分离,对滤饼进行干燥处理等步骤。其中滤饼与母液分离时通入气体保证滤芯两侧的压差使滤饼附着于滤芯表面,用于对母液进行过滤的过滤介质包括所述滤芯。该技术方案可一     

Efficiency of wood cellulose filtration

木浆纤维素作为助滤剂应用广泛,其过滤性能亟待研究。不同的过滤条件对木浆纤维素滤饼层的过滤性能会有很大影响。本文通过单因素法考察了过滤压力对滤饼层截留精度和平均滤速的影响,并通过正交实验法考察了木浆悬浮液黏度、木浆浓度、木浆添加量、悬浮液含水对滤饼层截留精度和平均滤速的影响。实验表明木浆纤维素属于中等可压缩性物料,其过滤性能随过滤条件变化呈规律性变化。通过对实验结果的分析,确定了优化方案。研究结果为木浆纤维素过滤的小型工业试验提供参考。     

航天炉灰水处理系统滤饼干燥工艺比选

滤饼是航天炉将煤高温气化燃烧反应及湿法除渣后的产物,具有粒度小、比表面积大、含水量高等特点,其燃烧性能远不及原煤,对于工厂而言,消纳滤饼的可靠方式是锅炉掺烧,而滤饼含水量远大于锅炉燃料煤,故降低滤饼水分成为消纳滤饼的关键环节。通过对多种滤饼干燥工艺进行分析与比选,认为滚筒干燥工艺是较为可行的方案,并建议将滤饼干燥后得到的粉煤采用粘结剂、压球机制成煤球,通过锅炉燃烧予以综合利用。经济核算表明,此举可获得良好的经济效益和社会效益。     

陶瓷膜微滤骨架镍催化剂的膜污染机理分析

用孔径为0.2μm的陶瓷膜过滤骨架镍催化剂悬浮液,研究膜污染机理。结果表明,膜污染主要是骨架镍催化剂在膜表面上形成的滤饼层,当操作压力循环变化时滤饼层表现出不可逆性。工业上用过的污染膜和滤饼层的组分分析表明,污染物主要是骨架镍催化剂。应用结果也表明了膜污染原因是骨架镍催化剂在膜表面形成了不可逆性滤饼层。     

滤饼结构的分形研究

概括地介绍了分形理论在滤饼结构研究中的应用 ,并采用电子扫描与计算机图象处理技术 ,并根据分形理论对以平板陶瓷膜为过滤介质的十字流微滤稳态阶段的滤饼结构进行了理论及实验研究。     

等压滤饼过滤过程中五个基本理论问题之探讨 ——等压滤饼过滤过程中单位过滤面积的滤液体积与过滤时间的通用数学模型

简要叙述了过滤过程中,滤饼层中发生的一系列现象。提出了滤饼的分类可分为局部比阻均布滤饼与局部比阻非均布滤饼两大类,同时给出了等压滤饼过滤过程中单位过滤面积的滤液体积与过滤时间的通用数学模型。     

低渗透油田注水井井底滤饼渗透性影响因素研究

针对低渗透油田注水井井底滤饼堵塞,本文通过模拟井底滤饼的形成过程,根据达西定律,测定在高温高压滤失仪中形成的滤饼的渗透率,研究了固相颗粒中值粒径、滤饼厚度及压力对注入井井底滤饼渗透率的影响。结果表明:固相颗粒粒径中值越大,形成的滤饼渗透率越大;形成的滤饼厚度越大,滤饼渗透率越小;滤饼随注入压力的增大,滤饼渗透率降低。     

滤饼颗粒物性对滤饼特性影响的分析

介绍颗粒的物性及滤饼的特性,通过对形成滤饼的颗粒物性的分析,论述了颗粒的尺寸、颗粒尺寸分布、颗粒密度、颗粒形状和颗粒间附着力对滤饼特性的影响,证实了滤饼的特性与其颗粒物性之间有着密不可分的联系,不同的颗粒物性将直接影响滤饼的特性（尤其是对滤饼比阻）的不同,从而影响过滤的效果。     

利用副产品碳酸钙分解制石灰的工程化分析

文章论述了利用碳酸钙滤饼分解制石灰,目的是解决磷石膏综合利用的二次污染问题,只有先解决了碳酸钙产品的出路才能确保硫酸铵装置的顺利实施。根据滤饼的特性,从生产原理和技术方案比选,认为选用回转窑煅烧分解制石灰是可行的,同时也阐明了随着杂质的带入对煅烧分解工程化技术和最终产品质量可能会产生一定的影响,需采用切实有效的对策措施。     

过滤过程中滤饼比阻及其影响因素的研究

滤饼过滤过程中,滤饼比阻是滤饼主要特性之一,其大小是衡量过滤难易程度的重要参数。通过叙述滤饼比阻的定义、测量方法,以及对其影响因素的研究,揭示了滤饼比阻与滤饼颗粒物性、过滤压差、料浆浓度、溶液的pH、过滤速率和过滤时间之间的关系。     

Avoiding filter cake cracking: Influence of consolidation on desaturation characteristics

In cake filtration processes with an air-blowing step, cracking is an undesirable phenomenon as it leads to deterioration of the filtration process by highly increasing gas throughput. This leads to higher residual moisture if the pressure difference cannot be maintained and an increase in overall cost. Crack formation can be avoided by compacting the filter cake before desaturation. While this action will make the separation process applicable by highly reducing gas consumption, there are also potential negative effects. Compaction increases filter cake resistance and might therefore slow down desaturation kinetics. Therefore, the authors investigated how the filter cake characteristics governing desaturation change from the nonconsolidated to the consolidated state of the filter cake and compared these findings to the actual dewatering kinetics. The results showed that for the case where cracking could be oppressed, dewatering kinetics of the consolidated cake are actually faster than for the nonconsolidated cake, despite higher resistance of the consolidated cake. Thus, compaction is an appropriate action when dealing with filter cake cracking.     

Experimentelle und theoretische Untersuchungen zur Filtration mit überlagerter Sedimentation in Drucknutschen

Sedimentation superimposed on industrial cake filtration leads to longer filtration times and often has a detrimental effect on subsequent process steps such as washing and demoisturing. The influence of sedimentation is seldom recognised in laboratory filtration experiments. Methods are presented for evaluation of pressure filter experiments with superimposed sedimentation which avoid the error made in the usual evaluation methods. For the case of zone sedimentation the article presents a graphical evaluation and a numerical method of modelling permitting scale up to any desired cake height. In superimposed classifying sedimentation simultaneous measurement of filtrate volume and cake height provide information about local variation in filter cake resistance. It is shown for a model system that, owing to sedimentation, the cake resistance shows a minimum at mean cake height and increases rapidly towards greater heights. The local cake resistance corelates with particle size distributions measured for layers of a horizontally cut filter cake. The method of evaluation presented permints determination of the flow resistance of the uppermost layers of a cake and hence estimation of the gas pressure necessary for demoisturing. The profiles of local filter cake resistance show that the relative cake layering is largely independent of the level of suspension filling. A scale-up model is presented for use in those cases where classifying sedimentation cannot be suppressed.     

Distributions of age, thickness and gas velocity in the cake of jet pulsed filters—application and validation of a generations filter model

Different imperfections are observed with jet pulsed filters. They manifest themselves most obviously in the curve of the pressure drop versus time. A convex pressure drop curve indicates cake compaction. But jet pulsed filters frequently show a concave rise of the pressure drop curve. This phenomenon is due to a strongly nonuniform cake area load on the filter and it is generally attributed to incomplete cake removal. Incomplete cake removal takes place when only a fraction of the total filter area is cleaned at the end of a filter cycle or when patchy cleaning prevails. Patchy cleaning means that a jet pulse removes the entire filter cake of only a fraction of the exposed filter area except for a thin adhesive dust layer.In this paper a filter model is proposed in which the different classes of cake thickness are understood to result from different cake generations. A cake becomes one generation older when it survives the jet pulse cleaning at the end of a filtration cycle, although the area that is occupied by the cake on the filter medium is diminished by the jet pulse.This generations filter model can be used to find the distributions of age, thickness and gas velocities in the cake from steady-state operational data. The steady-state, periodic model provides a complete basis for the simulation of heterogeneous gas/solid reactions in the cake of jet pulsed filters.In the model intermediate cake build up during the cleaning procedure is considered. There redeposition of removed filter cake also takes place, and its extent is estimated. The model can also serve to determine from macroscopic process data, if the cleaning system of a filter installation operates in the undesirable mode of patchy cleaning.Experiments from a pilot plant for dry flue gas cleaning are presented and the generations filter model is validated with the experimental data.     

气压过滤的成饼动力学及其滤饼的分形结构

用自制的实验室型气压过滤机并结合滤饼内部结构的测试,研究了气压过滤的成饼动力学及其滤饼结构的分形特征。结果表明,气压过滤条件下,虽然过滤压差较大,但成饼阶段仍遵循Darcy定律;气压过滤的滤饼结构为一分段Sierpinski分形,其分维数值介于1.775～1.885之间。     

Measurements and evaluation of concentration distributions in filter cake formed in dead-end ultrafiltration of protein solutions

To clarify the internal structures of the filter cake formed on the membrane surface in protein ultrafiltration, a method has been developed for measuring the variations of protein concentration across the filter cake on the basis of the principle of inclined ultrafiltration, where the membrane was inclined and a large amount of filter cake was formed, and the results were compared with the calculations based on a compressible cake filtration model, which explicitly took the non-homogeneity and the compressibility of the filter cake into account. The experimental results obtained from ultrafiltration of bovine serum albumin (BSA) solutions under constant pressure conditions clearly demonstrated that the filter cake tended to have a much more compact structure at the membrane in comparison with a relatively loose condition at the surface. It was also found that the thickness of the filter cake formed on the membrane increased as the filtration progressed. Further, the effects of pH and the solute concentration in the feed solution on the structure of the filter cake have been examined experimentally. The measured concentration distributions accorded well with the calculated results based on a compressible cake filtration model. This study revealed that the dynamic deposition behaviors of the protein molecules in dead-end ultrafiltration could be accurately described by a compressible cake filtration model.     

A model analysis on the reasons for unstable operation of jet-pulsed filters

Various physically based models are available to describe an uneven distribution of the filter cake on the filter area of jet-pulsed bag filters. Such an uneven distribution is intrinsically present, when only segments of the filter are cleaned at a time but not the entire filter. Moreover, also patchy cleaning causes an uneven filter cake loading, since only a fraction of a filter cake is removed by a jet pulse while the other fraction remains basically intact on the filter cloth. Unstable filter operation can be defined by a continuous or periodic reduction of the filtration time per cleaning pulse. The operation of a jet-pulsed filter was mathematically simulated and, by systematically altering model parameters, unstable operation was obtained. Three situations were investigated: a continuous increase of the filter cake resistance parameter, a continuous increase of the filter cloth resistance parameter, and a particular cake detachment function where, after a filter cake survived some filter cycles, it can hardly be removed. The transient pressure difference simulation results reveal characteristic patterns: Taking normal stable operation as a reference, an increase of the filter cake resistance leads to shorter filtration and somewhat longer cleaning intervals (i.e., more cleaning pulses). An increase of the filter cloth resistance causes longer filtration and also considerably more cleaning pulses. Deficient filter cleaning gives shorter filtration periods and extremely long cleaning intervals. A comparison between model simulations and pilot plant results shows that there, the experimentally observed unstable operation can most likely be attributed to problems with cake detachment. Hence appropriate measures for avoiding unstable operation were successfully introduced.     

颗粒沉积量对细颗粒层清灰力和清灰效率的影响

采用中径3.31 mm的细颗粒在PPS普通滤料和涤纶覆膜滤料表面形成不同沉积量的颗粒层,用缓慢增加反吹气流和低压脉冲清灰的方法进行清灰测试. 随着颗粒层沉积量增加,颗粒层低压脉冲清灰的效率均提高,缓慢反吹的清灰力也呈减小趋势. 涤纶覆膜滤料表面颗粒层沉积量从200 g/m2增长到401 g/m2时,平均清灰应力从350 N/m2降到100 N/m2,比PPS滤料低90 N/m2以上. PPS滤料上低压脉冲清灰效率随颗粒层沉积量的增加线性增加,涤纶覆膜滤料上颗粒层沉积量超过200 g/m2时非线性快速增加,缓慢反吹产生的颗粒层碎片均随着颗粒层沉积量增加而增大.     

Measurements of Growth Rate of Filter Cake in Vertical Single-Pass Ultrafiltration Using Hollow Fiber Membrane Module

Vertical ultrafiltration experiments of silica colloid and bovine serum albumin solution were conducted in the single-pass mode by using a hollow fiber membrane module and beneficial in measuring the time evolution of the growth rate of the filter cake during filtration. The extremely small mass flux of the concentrate enabled us to highly concentrate the feed solution on the principle of vertical ultrafiltration in which the filter cake formed on the membrane surface is exfoliated continuously. Both growth and re-entrainment rates of the filter cake formed in vertical ultrafiltration were evaluated from the experimental data of the filtration rate and the mass fraction ratio of the concentrate on the basis of the mass balance within the hollow fiber membrane module. As a consequence, it was found that the re-entrainment rate of the filter cake increased almost linearly with the filtration time in the initial period of filtration and then tended to rapidly approach a constant value. The filter cake stopped growing under this dynamically balanced condition. The variations of the average specific resistance of the filter cake with time were also determined from the time evolutions of both the filtration rate and the growth rate of the filter cake.     

覆尘滤袋综合渗透率的分形求解

基于分形理论计算滤袋及滤饼构成的综合渗透率,描述其渗流特性。结合滤饼扫描电镜实验与图像处理技术分析滤饼孔隙结构;利用改进的毛细管模型近似模拟滤饼孔隙通道,根据流体动力学原理得到了滤饼渗透率的分形表达式,并由达西定律计算得覆尘滤袋综合渗透率,并用其对袋式除尘器流场压力分布进行数值模拟。结果表明,滤饼孔隙结构具有自相似特点。覆尘滤袋综合渗透率为(1.615~4.784)×10?12 m2,模拟所得的滤袋内外压差与实验结果的相对误差小于26%。覆尘滤袋综合渗透率计算方法合理,可较好地描述复合多孔介质的渗流特性。