Topside process design for the liquid CO₂ Injection

Carbon capture and storage (CCS) is one of the dominant technologies to tackle the global warming issue. The transport of CO₂ for geological storage is economically feasible by ship when the storage site location is off-shore and instalment of an off-shore pipeline requires a huge capital cost. Ship transportation requires the captured CO₂ to be in liquid phase under pressurized thermodynamic conditions. The injection of liquid CO₂ into the geological reservoir involves pressurization and heating in order to maintain the safe well head operating conditions. This study presents two alternative top side injection process designs that can reduce the power requirement compared to the base case design. The base case design and alternative designs are simulated using Aspen HYSYS® in order to decide the process design variables. The study employed two-stage rankine cycle in order to extract the cold energy available from the liquid CO₂ before its injection into the reservoir. The alternative designs also proposed to utilize a vapor return line in order to maintain the vessel pressure within safe limits by performing a dynamic simulation. Finally, a sensitivity analysis has been done in order to investigate the effect of some important variables in the study.