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Role of porosity in filtration: XII. Filtration with sedimentation
Author(s) -
Tiller Frank M.,
Hsyung N. B.,
Cong D. Z.
Publication year - 1995
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690410511
Subject(s) - sedimentation , filtration (mathematics) , volume (thermodynamics) , porosity , flux (metallurgy) , chemistry , slurry , mineralogy , mechanics , materials science , mathematics , geology , thermodynamics , composite material , physics , metallurgy , sediment , geomorphology , statistics
Filtration on horizontal surfaces facing upward is accompanied by sedimentation. Material balances that are based solely on the volume of filtrate and neglect sedimentation flux lead to an understatement of the solids deposited in the cake and potentially large errors in calculated values of the average specific resistance α av . In a gravitational sedimentation experiment with kaolin, the value of α av neglecting sedimentation was 3.75 times greater than the value including the effect of sedimentation. In addition to errors due to neglect of sedimentation, CATSCAN studies show that the slurry concentration above the cake increases with time, contrary to usual assumptions. In a manner similar to batch sedimentation in a closed cylinder, characteristics of constant composition arose from the cake surface. Approximate predictions based on a combination of traditional sedimentation and filtration theory were in accord with the CATSCAN data. Existing filtration theory must be substantially modified to account for the effect of sedimentation.