(422d) Global Optimization of Multicomponent Membrane Cascade

Membranes have been playing an important role in chemical industry. Especially in the past decades, substantial advancements have been achieved on membrane materials which makes membrane one of the most promising separation technologies in the future. However, a single membrane permeator is still economically infeasible for some real-life applications, especially those requiring high recovery and purities of the products. This limitation could potentially be overcome using a membrane cascade, in which multiple membrane stages are connected to perform the separation. However, determining the optimal membrane cascade configuration and the optimal operating condition is challenging due to the complexity of the cascade structure and the membrane model itself. The prior literature that reports global optimal solutions assumes simpler mixing models such as well-mixing¹, which our simulations show deviates significantly in its predictions from experimental results. The research that has used more accurate crossflow model has either failed to derive global optimal solutions or only applies to the binary case².

In the current work, a global optimization algorithm has been developed to determine the optimal membrane cascade in terms of energy consumption. Given the feed composition, permselectivity of each of the components, product purity, and recovery requirement, the optimal membrane cascade and the optimal operating condition can be easily determined. The algorithm is tested over several real-life applications such as NGL recovery, H₂ recovery from hydrocarbon mixture, and acid gas removal from shale gas to evaluate the performance of the algorithm.

Reference

1. Alicia Aliaga-Vicente, Jose A Caballero, and Maria J Fernandez-Torres. Synthesis and optimization of membrane cascade for gas separation via mixed-integer nonlinear programming. AIChE Journal, 63(6):1989–2006, 2017.
2. Qi and M.A. Henson. Optimization-based design of spiral-wound membrane systems for CO₂/CH₄ separations. Separation and purification technology, 13(3):209–225, 1998.