DESIGN METHODOLOGY FOR THE OPTIMIZATION OF MEMBRANE SEPARATION PROPERTIES FOR HYBRID VAPOR PERMEATION-DISTILLATION PROCESSES

Abstract

Hybrid processes of distillation and vapor permeation are considered promising alternatives to azeotropic and extractive distillation. The research is directed toward developing membranes with improved separation properties and longer life times. We show that membranes with very high selectivities are not desirable when a very high purity of the retentate is required. A design methodology was developed to calculate the optimum separation properties for the membranes within hybrid processes. The results of the simulation encourage the use of low-selectivity membranes, especially if the membrane step is coupled to a distillation step. The method is applied to an ethanol dehydration process. However, it can be applied to other membrane separation processes as well.

Keywords:

• Vapor permeation
• Hybrid
• Distillation
• Process design
• Optimization

ACKNOWLEDGMENTS

Alaa Fahmy expresses his gratitude for the support provided by the Institut für Chemie of the GKSS Forschungszentrum. Dipl.-Ing. Olaf Stange is especially acknowledged for providing experimental data.

Notes

Another common separation index is the Rony's extent of separation [30], which was refined by Sirkar [31] for single entry barrier separation processes. This index has been extensively used for the characterization of gas separation stages 32-33 and pervaporation [34].