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

Abstract

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.