Abstract
Double-layer simulated moving bed chromatography introduced for the complete ternary separation problems utilizes parallel column configurations. The inlet and outlet streams of paired columns need to be properly split and merged to realize parallel operations with the packed bed columns. To make a pair of split streams, at least one flow control unit is additionally required. Therefore, the double-layer simulated moving bed chromatography that consists of six zones with parallelized two columns required at least 10 pumps to control five internal flow splits and five external inlet and outlet flows. In this work, two alternative layer configurations of the double-layer simulated moving bed were introduced to simplify the internal flow patterns. Applying an orthogonal parameter screening method, the design parameters of the double-layer simulated moving bed processes were optimized. The simplified layer configurations were compared with the standard parallel double-layer configuration in terms of process performances and system pressure decrease.
Highlights
Since the simulated moving bed (SMB) technology was introduced in the 1960s for binary and pseudo-binary separation problems, many modified SMB processes have been developed to improve the process performances for complex mixture separations.[1,2] By modulating the internal and external flow rates of the conventional four-zone SMB process, two wellestablished variations were introduced
The design parameters the length of the upper-layer column, the column connection of the paired double-layer zones, the ratio of the flow-focusing step, and the position of the flowfocusing step were screened on the basis of the standard design parameters
Since the same operating conditions are applied in each separation case, the feed and solvent throughputs are all the same
Summary
Since the simulated moving bed (SMB) technology was introduced in the 1960s for binary and pseudo-binary separation problems, many modified SMB processes have been developed to improve the process performances for complex mixture separations.[1,2] By modulating the internal and external flow rates of the conventional four-zone SMB process, two wellestablished variations were introduced. The first one was called the outlet stream swing (OSS) operation.[3] In the OSS operation, the outlet flows were consecutively on and off to enhance the product qualities. Katsuo and Mazzotti introduced the intermittent-SMB with a two-step operation.[4] Lee et al expanded this advanced operation concept to a generalized three-step flow-focusing operation.[5] Since the OSS and flowfocusing operations have more degrees of freedom in the operational aspect, these operations provided better performances than the conventional operation.[5]
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