Performance of Single and Double Shaft Disk Separators

Yazan Taamneh,Siegfried Ripperger

doi:10.1155/2008/508617

Abstract

Rotating disks separators, mounted on single and double hollow shafts, are investigated experimentally. The shaft and disks were enclosed in stainless steel housing. Many parameters were measured to study their influence on the performance of single and double shaft disk filters at various rotation speeds. These parameters are pressure inside the housing, permeate flux, and electrical power consumption. The average velocity coefficient k˜ for single and double shaft disk separators was estimated and was found to be a good criterion of module performance as well. The comparison of measured and calculated filtration flow rate at various rotation speeds was in a good agreement. The estimated average shear stress is found to be about twice in double shaft filter disk. The feasibility of double shaft disk separator in treating filtration without filter cake is highly appreciated.

Highlights

Shear-enhanced or dynamic filtration consisting of rotating disks relies on the presence of a shear stress at the filter media surface to reduce the accumulation of the particles
In the classical cross flow filtration with membrane modules, the shear stress is linked to the feed flow rate which leads to the pressure drop
We have shown that the average shear stress for the filter disk overlapping is almost twice as large as compared to the single shaft disk separator

Summary

Introduction

Shear-enhanced or dynamic filtration consisting of rotating disks relies on the presence of a shear stress at the filter media surface to reduce the accumulation of the particles. The reason for its good performance is that very high shear rates are produced with a low inlet flow, thereby resulting in low pressure drop in the module. In the classical cross flow filtration with membrane modules, the shear stress is linked to the feed flow rate which leads to the pressure drop. High shear stress is produced by increasing the tangential flow along the membrane surface and continuous circulation of the feed flow. Dynamic filters which create relative motion between the filter media and the suspension producing high shear rate are compared with conventional cross flow filtration [1].

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