Constant rate and variable pressure-variable rate filtration of power-law non-newtonian fluids.

Abstract

Constant rate and variable pressure-variable rate filtration operations, which may be more frequently encountered in industrial filtrations involving centrifugal pumps, are investigated by using so-called power-law non-Newtonian fluids. Filtration pressure was manually controlled so that constant rate or variable pressure-variable rate filtration experiments were executed. Slurries of Hyflo Super-Cel in sodium polyacrylate-deionized water solutions were filtered, the slurry concentration s being 0.18. The flow behavior index N of the filtrate was about 0.3. Based upon the theories for constant pressure filtration of power-law non-Newtonian fluids presented in the previous paper, methods are presented for analyzing constant rate and variable pressure-variable rate filtration operations. The methods can be used for evaluating not only the overall filtration characteristics of the average specific resistance γav for filtration of power-law fluids and the ratio m of wetto-dry cake mass but also the detailed internal structures of the filter cake during filtration operations. It is also shown that good agreement exists between theories and experiments.