The influence of particle properties on filtration
The influence of particle properties on filtration
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DOI：
10.1016/j.seppur.2007.03.018
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发表时间：
2007-12-15
影响因子：
8.6
通讯作者：
Wakeman, Richard
中科院分区：
文献类型：
--
作者：
Wakeman, Richard
如果可以为过滤指定颗粒特性，则目标特性将是颗粒具有尽可能大的尺寸，尽可能接近球形，并且具有单尺寸分布。它们的大可以最大限度地减少颗粒-液体界面的相互作用，最大限度地减少老化的影响，有效地消除许多与布有关的问题，如出血和致盲以及需要非常频繁的清洗，允许高流体流速通过滤饼，并减少滤饼排出时保留的液体体积。在实践中，进料总是由一个粒度分布组成，而分布中最小的颗粒控制着过滤周期的许多方面。最小的颗粒是在过滤的初始阶段通过滤布渗出的颗粒，它们积聚在最靠近滤布的滤饼层中，它们对颗粒的比表面和滤饼的比阻力贡献最大，并且它们与溶液中的离子或其他物质（例如聚合物）相互作用最强烈，以产生可压缩性效应。对表征过滤最重要的粒径很少是分布中的平均粒径（50%粒径）；分布中较细的颗粒通常“控制”过滤，当比较粒径对过滤的可能影响时，比较5%或10%的粒径是可取的。即使这些细颗粒数量的微小增加也会显著降低过滤速率。因此，有各种与操作相关的原因来消除饲料中的细粒，因为它们对过滤、洗涤和脱水的速度有减缓作用，并且是滤饼中水分含量较高的原因。(c) 2007 Elsevier B.V.版权所有
If the particle proper-ties could be specified for a filtration, the target properties would be for the particles to have as large a size as possible, be as near to spherical as possible, and have a monosize distribution. Their largeness would minimise the interactions at the particle-liquid interface, minimise the effects of ageing, effectively eliminate many cloth related problems such as bleeding and blinding and the need for very frequent cleaning, allow high fluid flow rates through the cake, and reduce the liquid volume retained in the cake when it is discharged.In practice, the feed is invariably composed of a size distribution and the smallest particles in the distribution control many aspects of the filter cycle. The smallest particles are the ones that bleed through the filter cloth in the initial stages of filtration, they accumulate in the cake layers nearest to the filter cloth, they contribute most to the specific surface of the particles and to the specific resistance of the filter cake, and they interact most strongly with ions or other substances (for example, polymers) in the Solution to create the compressibility effect. The particle size that is most important for characterising a filtration is rarely the mean size (50% size) in a distribution; the finer particles in the distribution usually "control" the filtration, and when comparing the likely effects of particle size on filtration it is preferable to compare the 5 or 10% sizes. Even small increases in the number of these finer particles can significantly reduce filtration rates.So there are a variety of operational related reasons to eliminate the fines in the feed, due to their slowing effect on the rates of filtration, washing and deliquoring and being a cause of higher moisture contents in filter cakes. (c) 2007 Elsevier B.V. All rights reserved.