Gravity-driven thickening in a long, vertical tube

W.A. Meetsma and A.C. Hoffmann
Dept. of Chemical Engineering, University of Groningen, Nijenborgh 4
9747 AG Groningen, The Netherlands

E.L. Cox
Shell Research BV, Koninklijke/Shell Exploratie en Productie Laboratorium, Volmerlaan 5
2288 Rijswijk, The Netherlands

Abstract
The problem of gravity-drive thickening of a dispersion in a long, vertical tube of diameter larger than the dimensions of the dispersed phase particles has been treated. Inflow of the suspension takes place trhough the porous tube wall and suspension is pumped away both at the upper and lower ends. A theoretical analysis of the problem is give. A material balance over a differential element spanning the cross-section leads to a model equation that has been soved analytically and numerically. The behaviour of the model as a function of various parameters, such as the axial dispersed phase concentration profile and the ratio of flows through the upper and lower pumps, is discussed. Comparison with the experimental results obtained in an industrial system shows good agreement

Author Keywords: suspension; gravity; particle; separation; two-phase flow: model

Index Terms: Suspensions (fluids); Gravitational effects; Mathematical models; Problem solving; Composition effects; Particles (particulate matter); Phase separation; Two phase flow; Phase composition; Differential equations; Wall flow; Pipe flow; Gravity driven thickening; Material balance; Axial dispersed phase concentration profile