Model Predictive Control of Simulated Moving Bed Chromatographic Processes Using Conservation Element/Solution Element Method

Simulated moving bed chromatographic (SMB) processes are used for difficult separations in pharmaceutical, biotechnological and petrochemical industries. Due to high sensitivity to disturbances these processes are usually operated in open-loop mode under suboptimal conditions. In the present work, operation of such processes based on the online optimizing model predictive control (MPC) using the full blown chromatographic model is proposed. For the fast and accurate solution of the underlying model described by a system of partial differential algebraic equations, the so-called space-time conservation element/solution method (CE/SE) is used. As an application example, the separation of racemic mixture of bicalutamides, one of which is a valuable active pharmaceutical component, is considered. To evaluate the performance of the controller, reference tracking (change of the purity requirements) and disturbance rejection (change of the composition of the feed mixture) scenarios are simulated. Since there is no plant-model mismatch, the controller is able to follow the change of the reference from complete to reduced purity separation closely. However, the results of the disturbance rejection simulation shows that the controller requires an adaption mechanism in order to efficiently reject the disturbance.