SMB Operation Strategy−Partial Feed

An operation strategy, partial feed, is developed to increase SMB separation efficiency. With the partial-feed mode of operation, the feed and raffinate flow rates vary with time. The separation of Dextran T6 and raffinose, which have linear isotherms, is modeled with the Aspen Chromatography simulator in a four-zone SMB for both normal-feed and partial-feed operations. Partial-feed operation significantly improved the separation with one column per zone. Either the purity and the recovery or the productivity could be increased. Partial feed introduces two additional degrees of freedom, namely, feed length and feed time. The optimum values for these parameters were determined. The improved separation is explained using local equilibrium theory.