|Title:||CFD analysis on the effect of calendering of filter cloth on transient characteristics of cake filtration||Authors:||Tung K.-L.||Issue Date:||2007||Journal Volume:||7||Journal Issue:||2||Start page/Pages:||109-112||Source:||Filtration||Abstract:||
The effects of a filter fabric calendering treatment and the permeability of filaments with regard to the particle deposition phenomena onto or into filter fabrics at the initial stage of filtration are conducted quantitatively using a microscopic forces analysis. The flow pattern and the resistance to fluid flow in the calendered interstices were obtained numerically using the fluid flow software FLUENT?. Based upon numerical data for the continuous phase, a program was devised to simulate the transient behaviours of pore clogging and cake formation by way of the Lagrangian approach. This estimates the change of filtrate clarity during the initial stage of filtration for various calendered fabric porosities and various filament permeabilities. Results show that in the case of tightly woven filter cloths the flow is predominantly through the yarns of the cloth, while flow will generally be directed around the yarns of a loosely woven cloth, especially if the yarn is twisted tightly. Therefore, filtrations with tightly woven but loosely twisted yarn can increase the unfavourable, but inevitable, clogging problem. The simulated results further show that although the filtration resistance of woven filter fabric increases after calendering, the permeability is rectified and the clogging of the filter pores is also improved. After the calendering of the filter fabric has taken place, only the cake formation mode (in accordance with the law of blocking for all types of pore) is evident. The criticial concentration proposed by previous investigators is not observed for calendered filter fabrics.
|Appears in Collections:||化學工程學系|
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