Filter Rates of Clay-Oil Slurries H. H. BIBLE,l M. A. WITTE,2 AND J. W. DONNELL University of Oklahoma, Norman, Okla.
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HERE has been a tendency on the part of chemical
engineers to disregard the filter medium resistance in comparison with the cake resistance in filtration studies. This has resulted in some cases in a n appreciable error in filter calculations. Average cloth resistances varying from 8 to 40 per cent (during a single filtering cycle) have been found when clay-oil slurries were being filtered. Almost all of the work carried out on filtration, from which the most generally accepted filtration equations have been derived, was done on slurries with relatively fine particles (e. g., chromium hydroxide) instead of slurries containing particles as large as that used in petroleum contact filtration (up to 4 0 ~ 1 ) . Moreover, most of the previous work was done on slurries having water as the dispersion medium. The variations in viscosity in these studies were necessarily small in comparison with the viscosity variation in petroleum slurries. ~
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Evidence that Poiseuille’s law does not describe closely enough for engineering calculations the rate of flow through both filter cloth and filter cake for clay-oil slurries is presented. Average cloth resistance varying from 8 to 40 per cent (during a single filter cycle) of the total pressure drop has been found. The law describing the relation of filter rate, R , to pressure drop PI through the filter cloth was R = 1
