Example Design of Hybrid Systems Using Distillation-Membrane Processes

8 EXAMPLE DESIGN OF HYBRID SYSTEMS USING DISTILLATION-MEMBRANE PROCESSES 

The example presented in this section is a condensed version of a study detailed in the book Membrane Process Design Using Residue Curve Maps [1] and has been reproduced with permission from John Wiley Sons, Inc. The example is included here to demonstrate the versatility and adaptability of the techniques discussed throughout this book. 

As an example, the separation of a butene/methanol/MTBE system is investigated. Methyl tertiary-butyl ether (MTBE) is the desired product, and hence needs to be efficiently recovered from a reactor output. Difficulty arises when separating such a mixture with conventional distillation processes, because of the binary azeotropes that exist between methanol and MTBE, as well as between methanol and butene. The driving force for separation in membrane processes differs from that in distillation, thus a membrane process will not exhibit the same azeotropic behavior. Thus, the limitations on distillation processes can be overcome by using a membrane unit. 

APPLICATION OF COLUMN PROFILE MAPS TO ALTERNATIVE SEPARATION PROCESSES 

In seeking the most efficient process possible, a designer will wish to explore a wide range of feasible designs. To make this possible, an efficient method for the synthesis and assessment of any hybrid separation process has been developed. Since both processes have been analyzed using similar mathematical backgrounds, it is possible to use residue curve maps and column profile maps for both distillation and membranes to design hybrid systems of the two. 

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