Optimización

G Model CEP-6183; No. of Pages 14

ARTICLE IN PRESS
Chemical Engineering and Processing xxx (2012) xxx–xxx

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Chemical Engineering and Processing: Process Intensification
journal homepage: www.elsevier.com/locate/cep

Optimisation-based design method for membrane-assisted separation processes
Katharina Koch a,∗ , Daniel Sudhoff a ,Stefan Kreiß a,1 , Andrzej Górak a,b , Peter Kreis a,2
a b

TU Dortmund University, Department of Biochemical and Chemical Engineering, Laboratory of Fluid Separations, Emil-Figge-Straße 70, 44227 Dortmund, Germany Technical University of Lodz, Faculty of Process and Environmental Engineering, Lodz, Poland

a r t i c l e

i n f o

a b s t r a c t
This paper presents a design method formembrane-assisted separation processes based on the concept of process superstructure optimisation, which should be applied to the separation of azeotropic mixtures. The main features of the proposed method are as follows: (i) detailed rate-based modelling of all unit operations; (ii) experimental model identification for membrane separation; (iii) application of an evolutionary algorithm. This methodallows the simultaneous determination of optimal process configuration, equipment design and operating conditions for membrane-assisted separation processes. A case study for the separation of a ternary mixture of acetone, isopropyl alcohol and water in a hybrid pervaporation-distillation process is presented using the optimisation-based design method. Detailed rate-based models for the unitoperations involved were implemented in a generic process model and necessary membrane model parameters were determined experimentally in a laboratory-scale device for the hydrophilic polymeric membrane PervapTM 2201D from Sulzer Chemtech. After the identification of an appropriate process superstructure, the process configuration, dimensions of equipment and operating conditions required for the optimalhybrid pervaporation-distillation process were determined simultaneously. The optimisation criterion was the cost for purifying one ton of acetone. The results show that the developed method can be applied successfully for this complex mixed-integer non-linear optimisation problem. © 2012 Elsevier B.V. All rights reserved.

Article history: Received 4 April 2012 Received in revised form 17September 2012 Accepted 18 September 2012 Available online xxx Keywords: Hybrid process Distillation Pervaporation Experimental membrane characterisation Rate-based modelling Evolutionary optimisation

1. Introduction The separation of azeotropic multicomponent mixtures is an inherent part of biochemical and chemical processes and still remains a challenging issue in terms of process design andidentification of selective separations. Well-known separation processes such as extractive, heteroazeotropic and pressure swing distillation often require high investment and energy costs. Membrane processes such as pervaporation and vapour permeation can be regarded as an alternative to established separation processes due to their high selectivity and their potential to achieve significant energy savings.However, membrane processes are not often used as stand-alone processes on the industrial scale because of high costs or low throughput. The most promising process concept for

Abbreviations: ACE, acetone; ACM, Aspen Custom Modeler® ; FID, flame ionisation detector; GC, gas chromatograph; H2O, water; IPA, isopropyl alcohol; MINLP, mixed-integer non-linear programming; PAN, polyacrylonitrile;PVA, polyvinyl alcohol. ∗ Corresponding author. Tel.: +49 2317556265; fax: +49 2317553035. E-mail address: katharina.koch@bci.tu-dortmund.de (K. Koch). 1 Present address: Evonik Industries AG, Goldschmidtstraße 100, 45127 Essen, Germany. 2 Present address: Evonik Industries AG, Paul-Baumann-Straße 1, 45772 Marl, Germany. 0255-2701/$ – see front matter © 2012 Elsevier B.V. All rights reserved....