Flow characteristics and dispersion during the leakage of high pressure CO2 from an industrial scale pipeline

Pressurized pipelines represent a key way of transporting CO2 from emitter to storage site. Leakage of CO2 through a small puncture is the most common form of pipeline failure during normal operation; such failures could lead to fracture. The study of pipeline depressurization and dispersion behavior is of paramount importance for assessing the possibility of fracture propagation and the impact of CO2 releases on the surrounding environment. A large-scale pipeline (258 m long, 233 mm i.d.) was constructed to study the flow characteristics and dispersion of gaseous, dense and supercritical phase CO2 during vertical leakage through a 15 mm diameter orifice. The fluid pressures, fluid temperatures and wall temperatures along the pipeline were recorded to study the pressure responses, phase transitions and thermodynamic properties during the release. Video cameras and CO2 concentration sensors were used to monitor the formation of the visible cloud and the concentration distribution in the far-field. There was a two cold, intermediate hot phenomenon during the vertical leakage in the dense and supercritical release due to the dry ice particle accumulation near the orifice. The intersection of the jet flow and settling CO2 mixture resulted in complex visible cloud forms in dense CO2 release.