Filtration of non-Newtonian fluids.

Abstract

In view of increasing usage and importance of non-Newtonian fluids in the chemical industries and in scientific research, an investigation into the filtration of non-Newtonian fluids was undertaken. During the course of the present investigation, filtration equipment was designed and constructed to conduct experiments to substantiate the theoretical analysis for the filtration of incompressible, time independent non-Newtonian fluids. The fundamental relationship formulated for filtration in the course of this investigation, which incorporates recent modifications of Tiller and Shirato and of Shirato et al., accounting for the variation of the superficial velocity of the liquid through the cake and the velocity of the particles of the cake associated with cake compaction, was experimentally verified and confirmed. Also experimental data were obtained to establish the viability and efficiency of an improved method of treatment in which the filtration is considered to be comprised of an initial stage and the main filtration stage yielding a convenient means of characterization of the initial stage of filtration and of its effects on filter medium and cake characteristics. Further, the usefulness of the concepts and relationships developed for filtration in the interpretation and processing of experimental data is demonstrated utilizing the data collected in the constant pressure and constant rate filtration of slurries of calcium carbonate in water and in hydroxyethyl cellulose (Natrosol 250) solutions. The filtration area of the apparatus was 4.51 x 10-2 sq. ft. and the calcium carbonate content of the slurries was 2.5 per cent by weight. The applied filtration pressure and flow rate in the constant pressure and constant rate experiments ranged between 50 to 350 psi and 2. 24 x 10-4 to 3. 29 x 10-3 ft. sec., respectively.