(652a) Compressible Nutsche Cake Filtration – Retarding Effect of Residual Base-Cake | AIChE

(652a) Compressible Nutsche Cake Filtration – Retarding Effect of Residual Base-Cake

Authors 

McGough, P. - Presenter, Corteva Agriscience, a division of DowDupont
Chappelow, C., Corteva Agriscience, a division of DowDupont
Kodam, M., Corteva Agriscience
Production scale filtration of fine needle morphology crystalline solids is often challenging, since needles tend to give rise to compressible, slower filtering cakes. In this study, a slurry comprised of needles that has a difficult Nutsche filtration at production scale was studied in a laboratory setting to better explore the factors that affect this filtration. Laboratory filtration was accomplished on a 1L “pocket” Nutsche filter. The filtration was characterized by measuring the inherent cake resistance and media resistance under different conditions. Increasing the driving pressure showed limited improvement in filtration rate, indicating a moderately high level of compressibility. Filtration at colder temperatures showed a retardation from both increased viscosity and a higher inherent cake resistance. However, while these filtration experiments were insightful, scale-up calculations were under-predicting the filtration times at production scale. Further investigation focused on base-cakes, which are thin 1 – 2 cm heels left behind on many production filters, including the agitated Nutsche used in this process. A thin residual base-cake increased filtration times 2X and then nearly 3X in successive filtrations as the base-cake resistance increased. Incorporating these base-cake resistances into the scale-up calculations resulted in predictions that nearly match the production scale results. Removal of the base-cake in this application holds significant potential to increase productivity of the filtration unit operation.