Hollow fiber membrane model for gas separation: Process simulation, experimental validation and module characteristics study

Abstract

Conceptual process simulations and optimization are essential in the design, operation and troubleshooting stages of a membrane-based gas separation system. Despite this, there are few mathematical models/tools associated with a hollow fiber membrane module available in a commercial process simulator. A mathematical model dealing with the hollow fiber module characteristics that can be included within a commercial process simulator is needed to examine the performance and economics of a gas separation system. In this study, a hollow fiber membrane model was incorporated in Aspen HYSYS as a user defined unit operation for the study of carbon dioxide separation from methane. The hollow fiber membrane model was validated experimentally. The study of a double stage membrane module with a permeate recycle, which was proposed to be the optimal configuration in previous studies, was extended to consider the effects of the module characteristics (such as the fiber length, radius of the fiber bundle, diameter of the fibers, and porosity) on the process performance and economics. The gas processing cost (GPC) increased with increasing fiber length and bundle radius, and decreased with increasing outer diameter of the fibers and porosity. At the same time, the separation efficiency (product quality) was also dependent on these module parameters. Therefore, the tradeoff for the hollow fiber membrane module characteristics needs to be determined based on the minimum GPC with respect to the desired product purity.