Compactable Porous and Fibrous Beds Formed from Dilute Pulp Suspensions

A systematic experimental investigation of the formation of compactable fibrous mats from dilute pulp suspensions (8.00 kg/m3 fiber concentration or 0.533 vol % of solid) has been performed over a range of vacuum levels (10.0−66.7 kPa). An instrumental apparatus with a computerized data-acquisition system measured the operating vacuum and filtrate flow rate. The dynamic behavior of the mat formation process, in a transparent plastic filtration cell, was observed and videotaped. Dynamic fiber concentration profiles along the mat formation direction were inferred from the standard images using a gray-scale analysis calibrated against a set of known concentrations. A modified filtration model for compactable fibrous mat formation was proposed on the basis of Tiller's filtration theory. The model captures the filtrate flux and mat thickness as functions of time and operating vacuum for a compactable mat, which have not been reported previously in the literature.