To obtain accurate values of filtration characteristics as the ratio mof wet to dry cake massand the average specific filtration resistance aav, constant-pressure filtration experiments were conducted using a filter having a hole at the top of the filter chamber. The relation between the cake thickness L and the filtrate volume v per unit medium area, which serves as a basis of the determination of m and aav, can be obtained on the basis of the principle of sudden reduction in the filtration area of the cake surface. The constant-pressure filtration characteristics obtained by this method were fairly consistent with the estimated values based on compression-permeability cell data. The values of m and aav are influenced by filtration pressure and by slurry concentration. However, these values remain constant during any one constant-pressure filtration experiment. On the basis of the constant-pressure filtration data obtained by this method under various pressure conditions, the local porosity s and the local specific filtration resistance a can be determined approximately.
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 experimentswereexecuted. Slurries of Hyflo Super-Cel in sodium polyacrylate-deionized water solutions were filtered, the slurry concentration s being 0.18. The flow behavior index Nof 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 rav 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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.