Analysis and estimation/prediction of the disk stack centrifuge separation performance – Scaling from benchtop fixed rotor type to disk stack centrifuges

Abstract

ABSTRACT A mathematical model is proposed to calculate the total separation effectiveness in terms of GT for a disk stack centrifuge taking account of the variation of the centrifugal force with a position in the disk. In practice, the centrifuge ability/force is often referred as Relative Centrifugal Force (RCF) or G number, which is a multiple of the centrifugal acceleration over the gravitational acceleration. As the radial velocity varies it is important to integrate the relative centrifuge force, here in terms of the G number along the path taking account of the change in velocity. The separation effectiveness, GT is defined as an integrated product of local G number, G(x) and local residential time (dt), where dt is the time taken for the bulk fluid to traverse a distance from r to r+ dr. The GT value calculated for a disk type centrifuge can be compared with the GT value of others and compared with a bench top fixed rotor centrifuge. An industrial centrifuge would be expected to be able to deliver similar separation performance to a pilot or a lab scale one, if operated at the same/similar value of GT. This would allow the performance of a full-scale clarifier to be predicted. This model is, in essence, a simple alternative to the Sigma concept.