Enhancing efficiency and economic viability in Rectisol system with cryogenic liquid expander

Cryogenic liquid expanders have emerged as a potential energy-saving alternative to Joule–Thomson (JT) valves in cryogenic processes. The potential impact of incorporating a liquid expander into the Rectisol process has not been quantitatively evaluated. This study seeks to assess the effectiveness of replacing the JT valve with a liquid expander in the Rectisol process through the development of thermodynamic models for each component and conducting simulations using the ASPEN software. Additional analyses, including energy, CO₂ footprint, exergy, and economic evaluations, are performed for the Rectisol system. Utilizing an expander has been shown to lower energy usage by 2.52% and boost CO₂ capture by 5.55%, resulting in a 7.65% decrease in energy expenditure per unit CO₂ and a 1.29% rise in total exergy efficiency. Lower expander outlet temperatures and the green power output generated by the expander are the main reasons for these benefits, and the CO₂ footprint analysis explains how they work. The application of an expander in the Rectisol process is an economical and low-risk solution; the payback period is 0.32 years, and the lifetime profit is 53 folds of the investment.