Shortcut design methods for hybrid membrane/distillation processes for the separation of nonideal multicomponent mixtures

In conceptual process design many alternatives can arise for the separation of multicomponent mixtures. Shortcut methods can be used to evaluate and compare all variants in a first step. In this work shortcut methods for hybrid membrane/distillation processes are presented. The distillation is addressed by the rectification body method recently developed by the authors, providing the minimum energy demand of a separation and the optimal sidestream composition. The membrane unit is evaluated using the minimum membrane area. It is a lower bound for the actual membrane area and can be used to estimate the real membrane area and thus the investment cost of the membrane process. The novel method overcomes limitations of previous methods: It can be applied to multicomponent nonideal mixtures and to general:flux laws for any membrane. The stated methodology is applied to the purification of ethanol and to the separation of the reactor output stream in methyl tert-butyl ether production.