Determination of Filtration Characteristics Based Upon Filtration Tests Under Step-Up Pressure Conditions

Abstract

To obtain a simple method for determining filtration characteristic values as functions of the applied pressure, filtration experiments are conducted by increasing the applied pressure with time stepwise. A procedure is presented for obtaining such average values as the void ratio eavand the specific filtration resistance αav on the basis of measurements of both the hydraulic pressure within the cake and the accumulated filtrate volume. In addition, an approximate method is developed in which the characteristic values of the local void ratio e and the local specific filtration resistance a are determined as functions of the local solid compressive pressure ps from calculations based upon the overall values of eav and aav of filter cakes. The relations obtained from step-up pressure filtration are fairly consistent with those from constant-pressure filtration and C-P (compression-permeability) cell data. The filtration behavior under constant-pressure and variable-pressure conditions is well evaluated by using these relations. © 1989, The Society of Chemical Engineers, Japan. All rights reserved.