WIT Press

A Contribution To The Problem Of The Continuous Dewatering Process


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J. Mls


Because of its energetic efficiency, gravity thickening is one of the most convenient processes of lowering the volume of suspensions. One of the problems that has to be solved when designing equipment for, say, a digestion tank for the continuous process of suspension dewatering, is to determine the optimum height of the compression zone of the given suspension. This paper presents a solution for this problem. The suspension is considered as a two-phase continuum where both the phases are independently movable. The behaviour of such a system can be described by a set of partial differential equations of general Darcian mechanics. Making use of the known hydromechanical characteristics of the investigated two-phase system, a problem with a set of two ordinary differential equations and related boundary conditionswas formulated and numerically solved. The unknown functions of the problem are the liquid-phase pressure and the solid-phase concentration. The method of solution is described and the achieved results are visualized and presented. 1 Introduction The process of compression of a suspension has to be studied in detail when various industrial technologies are designed, particularly when the optimum height of the compression zone of sedimentation tanks has to be determined, e.g. Tuˇcek and Kon´ıˇcek [6]. The previous reduction of the suspension volume minimizes, for example, the space of digestion tanks and improves the efficiency of filtration or centrifugation. The gravity thickening is, because of its low energetic demands, one of the most convenient processes of lowering volume of suspensions and significantly increasing the concentration of their solid phase.