What Is Dense Phase CO2?
The physical state of CO2 varies depending on pressure and temperature. It can exist as a solid, liquid, vapor (gas) or a supercritical fluid, as presented in Figure 1. The term “dense phase” is a collective term for CO2 when it is in either the supercritical or liquid states. For most CCS projects economics will drive the need to transport CO2 in its dense phase since vapor phase transmission would require considerably larger diameter pipelines for the same mass flow rate. Figure 1: CO2 phase diagram, as a function of temperature and pressure. There is relatively little experience worldwide in managing the risks associated with CO2, compared with oil and gas. The major accident hazards presented by handling high-pressure CO2 offshore or onshore need to be considered. Material Compatibility Dense phase CO2 is highly invasive and capable of dissolving materials. This property means that the selection of materials for seals, instruments, controls and other safety-critical components shou
