Design and optimization of CO₂ pressurization system integrated with a supercritical CO₂ power cycle for the CO₂ capture and storage system

An innovative CO₂ pressurization system combined with supercritical CO₂ (sCO₂) open power cycle is proposed in this study. The combined system reduced the power demand associated with CO₂ pressurization in the CO₂ capture and storage (CCS) process as well as utilized the captured CO₂ in a sCO₂ power cycle to generate power. As the first step, conventional multi-stage compression was complemented with CO₂ liquefaction and pumping to reduce the compression power. Later, a waste heat-powered recuperative sCO₂ power cycle was employed to generate additional electric power. The vapor compression cycle (VCC) was first modeled, validated, and explored for CO₂ liquefaction and pumping. Refrigerants R717, R134a, R290, and R32 were analyzed as the VCC working fluid. An initial thermodynamic analysis was performed to identify the most influential liquefaction parameters. Then, a genetic algorithm optimization module in MATLAB was used to minimize the overall power consumption in the VCC. The VCC was integrated with a sCO₂ cycle to utilize the high pressure CO₂, and after optimizing the VCC, the performance of the sCO₂ cycle was evaluated. Results of our study revealed that integrating the sCO₂ cycle with a CO₂ liquefaction and pumping cycle reduced power consumption by 13.88% compared to conventional multi-stage compression. Finally, sensitivity analysis with respect to the crucial thermodynamic parameter was also performed.