(647g) Superstructure Optimization of Pressure Vacuum Swing Adsorption Processes

The performance of a pressure vacuum swing adsorption (PVSA) process depends on two factors, the adsorbent media and the PVSA process cycle. With the advent of metal organic frameworks, the potential pool of adsorbents has exponentially grown over the past decade. They provide the process designers with a diverse set of equilibria and other tunable properties to choose from¹. Detailed dynamic models required to accurately capture the adsorption behavior exist but are computationally expensive to solve. Each PVSA cycle configuration has a large set of decision variables such as the pressure envelop, the feed flowrate, etc. There are potentially multiple cycle configurations for any adsorbent that one can choose to meet the desired separation objectives². To achieve the true potential of a given adsorbent, the operating conditions of each cycle configuration must be optimized. Optimizing the PVSA cycle configuration and the operating conditions is not computationally scalable. Thus typically, the performance of a small set of user-defined process cycle configuration are chosen for optimization.

This work presents a superstructure model of a PVSA process as a method to design the best cycle configuration. To highlight the potential of such an approach, the case study of post-combustion CO₂ capture is presented in this work. The superstructure model presented in the work covers over a dozen possible PVSA cycle configurations. The scale of the proposed model leads to a potentially large input search region. A novel optimization strategy is also proposed to optimize the set of decision variables involved. Multiple case studies are evaluated to identify the best configurations for different processes and operational constraints.

¹Yamil J. Colón and Randall Q. Snurr, High-throughput computational screening of metal-organic frameworks, Chem. Soc. Rev., 2014,43, 5735-5749.

²Shivaji Sircar, Basic Research Needs for Design of Adsorptive Gas Separation Processes, Ind. Eng. Chem. Res. 2006, 45, 16, 5435–5448.