Dynamic response and flexibility analyses of a membrane-based CO2 separation module

Renewable energy sources and fossil-fueled power plants integrated with carbon capture technologies are expected to play an important role in sustainable energy supply in the future. In this regard, this study aims to improve the flexibility of membrane-based CO2 capture units as a promising technology for CO2 capturing by analyzing the system's transient behavior. A rigorous dynamic model for a single-stage membrane separation system is developed, which includes differential equations of transport phenomena across the membrane, mass balances, and pressure distributions. The model is utilized to investigate the dynamic performance of a single stage counter-current membrane module for separating CO2 from the flue gas of a power plant, including up to 13 vol% of carbon dioxide. Step-changes in feed pressure, feed flow rate, feed composition, and retentate recycling are considered for the analysis. The results show that by step increase in feed pressure from 5 to 8 barg, undershoot behavior is detected, and the membrane module requires about 7 s to reach a steady-state condition. In contrast, by step decrease in feed pressure, there is an overshoot, and the module requires 11 s for new steady. Also, the membrane module responds slowly to step-changes in feed composition and retentate recycling (similar to 20 s) compared to other step-changes in operating conditions. This paper provides new insights into the dynamics analysis of the membrane process as well as the flexible operation of membrane-based carbon capture systems.