One-column chromatograph with recycle analogous to simulated moving bed adsorbers: Analysis and applications

A single chromatography column with tanks (the "analogue") can be made analogous to a simulated moving bed (SMB) configuration with the appropriate recycle pattern. The analogues and the corresponding SMBs were simulated using Aspen Chromatography. Typically, the analogue produces a lower purity product because of mixing in the tanks. For the linear system of dextran T6-fructose, the use of a large number of tanks to approach plug flow improved the separation in the analogue so that it asymptotically approached the SMB separation. Because the analogue would be useful in short campaigns, a start-up analysis was performed for both a linear system of dextran T6-fructose and the nonlinear system of binaphthol enantiomers. Correct start-up conditions can reduce the time needed to reach steady state by 50%. A shutdown analysis for the linear system was also performed, and several strategies were suggested that reduce the time and amount of desorbent used during shutdown. The concept of the one-column analogue was successfully applied to various three-zone SMB configurations for the linear system of dextran T6-raffinose and to the VARICOL process for the dextran T6-fructose system.