Development of CO2 liquefaction cycles for CO2 sequestration

CO2 pressurization is a necessary component in any CO2 capture and sequestration (CCS) where enhanced oil recovery (EOR) is to be applied. The power demand for the CO2 pressurization process consumes about 4% from the power plant net power. In this paper, several CO2 pressurization methods, such as compression or liquefaction and pumping using an open cycle or closed cycles, were explored and evaluated. New CO2 liquefaction cycles based on single refrigerant and cascade refrigerants were developed and modeled using HYSYS software. The models were validated against experimental data and/or verified against other simulation software. The liquefaction parameters were optimized for minimum overall power consumption. The considered refrigerants for CO2 liquefaction are NH3, CO2, C3H8 and R134a. One of the developed liquefaction cycles that liquefies the CO2 at 50 bar using NH3 refrigerant resulted in 5.1% less power consumption than the conventional multi-stage compression cycle as well as 27.7% less power consumption than the open CO2 liquefaction cycle.