(476b) Process Integration for Simulated Moving Bed Reactor for Production of Glycol Ether Acetate

Authors: 
Tie, S., Georgia Institute of Technology
Sreedhar, B., The Dow Chemical Company
Donaldson, M. E., The Dow Chemical Company
Frank, T. C., The Dow Chemical Company
Bommarius, A., Georgia Institute of Technology
Kawajiri, Y., Georgia Institute of Technology
Simulated moving bed reactor (SMBR) has significant advantages over the traditional sequential reactor and separator operation in terms of improved process performance such as separation resolution, increased productivity, and reduced solvent consumption. Academic interest in SMBR operation have manifested through past investigations; however, these studies have focused on the SMBR operation in isolation from the overall process flow, and to the best of our knowledge, it has never been analyzed as a component of a process flowsheet.

This work identifies the optimal SMBR operating parameters for its integration within an overall process. The dynamic mathematical model developed in our previous work is employed in a process flowsheet in this work. The SMBR model was developed for an industrial case study for the continuous production of a solvent, propylene glycol methyl ether acetate (DOWANOLTM PMA1) through an acid-catalyzed esterification reaction of 1-methoxy-2-propanol and acetic acid. This overall process consists of the SMBR unit and two downstream units. Specifically, the extract and raffinate streams from the SMBR are further processed to improve product purity, and recycle streams leaving the downstream units return to the SMBR unit to reduce solvent consumption and waste generation.

The proposed process flowsheet is optimized in a deterministic, nonlinear dynamic optimization scheme. The overall operation is formulated as multiple objective optimization problem. The objective functions are to minimize the operating cost of the overall process indirectly through constraints on process variables and to maximize the PMA productivity. The results from this work are compared to those of an isolated SMBR unit, allowing for a detailed comparison between the SMBR operation in the overall process to that of an isolated unit. The work presented offers a more realistic and holistic overall process understanding that is representative of industrial SMBR operations.

1. Trademark of The Dow Chemical Company ('Dow') or an affiliated company of Dow.