Online Optimization Based Feedback Control of Simulated Moving Bed Chromatographic Units

G. Erdem, S. Abel, M. Morari, M. Mazzotti and M. Morbidelli

Abstract
The Simulated Moving Bed (SMB) is a continuous multi–column chromatographic process that has become an attractive technology for complex separation tasks that are regularly encountered in the areas of pharmaceuticals, fine chemicals and biotechnology. Even though economic optimality of the SMB process has attracted significant amount of attention, operation of the SMB units at their optimal operating conditions is still an open issue due to the absence of proper feedback control schemes. Recently, we have developed an online optimization based feedback control scheme that can deliver the full economic power of the SMB technology despite disturbances and uncertainties in the system.1,2,3 This paper focuses on the implementation of the control concept to SMBs operating under overloaded chromatographic conditions that are characterized by nonlinear competitive adsorption isotherms. It is shown that despite the overloaded chromatographic conditions, the process can be controlled and optimized based on the linear adsorption isotherm information only. The performance and robustness of the control scheme is assessed under simulated challenging operating conditions.

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Keywords
Simulated moving bed, nonlinear chromatography, online optimization, automatic control, repetitive model predictive control