Release and dispersion behaviour of carbon dioxide released from a small-scale underground pipeline

Abstract The development of carbon capture and storage (CCS) brings challenges for safety issues regarding carbon dioxide (CO 2 ) transmission pipelines. Once a pipeline is punctured or full-bore ruptured, the leaked CO 2 is hazardous to personnel and the environment. Small-scale devices were established with the aim of studying the release and dispersion behaviour of gas and liquid CO 2 from a punctured underground pipeline. A sandbox was built to simulate the underground conditions. The parameters of the sand used in the experiments were tested. CO 2 concentrations on the ground and temperatures around the release orifice in the sand were analysed. The results indicate that in the CO 2 gas release experiments, the CO 2 concentration on the sand surface decreases with increasing horizontal distance in the form of a power function. CO 2 concentrations in upward release are slightly larger than those in horizontal release at the same location but are obviously bigger than values in downward release. The temperature-drop region is much smaller than that in air. A frozen ice ball can be generated near the release orifice during the gas phase of the CO 2 -release process. In the liquid phase of CO 2 -release experiments, a large amount of dry ice is generated near the release orifice. Dry ice can only be generated in the area close to the release orifice, especially in the near-field area.