Analysis of Multistage Membrane and Distillation Hybrid Processes for Propylene/propane Separation

Abstract

The membrane based processes have been considered as a new and alternative processes for mixture separation offering lower energy requirements. It has advantageous features like low energy, modular design, easy operation, and low maintenance for a wide variety of commercial and industrial gas separation applications. In this study, membrane/distillation hybrid processes with heat pump integration for propylene/propane separation were investigated to reduce the energy and cost. The effects of the membrane on the system were confirmed by modifying different variables. The four schemes have been proposed by combining membrane and distillation with recompression heat pump satisfying the separation target of 99.6 wt% C3H6 purity and 99 % C3H6 separation recovery ratio. We compared the economic efficiency of the systems versus a conventional distillation process using various technical and economic indicators based on the membrane performance such as selectivity, permeability, stage-cut and pressure ratio. The results showed that the hybrid system yielded considerable energy and cost savings. Furthermore, it indicates that the percentage of cost savings depends on the permeability and selectivity of the membrane.