Depressurization and heat transfer during leakage of supercritical CO2 from a pipeline

The carbon capture, utilization and storage (CCUS) technology can effectively improve global climate change. Extensive pipelines are used in CCUS to transport large amounts of pure and impure supercritical CO2(S‐CO2) from captured sites to storage, owing to pipelines being an economical and efficient means of transportation. In the event of an accidental rupture of a supercritical CO2 pipeline, causing substantial economic losses and catastrophic consequences to surroundings. Hence, it is necessary that the study of the pressure variation and temperature distribution of CO2 during pipeline blowdown contributes to understanding fracture initiation and propagation, as well as designing reliable pipelines. A laboratory‐scale setup is used to investigate the evolution of leakage behaviours and analyze heat transfer of pure and impure supercritical CO2 with different release orifices. The depressurization process, variation of inner and wall of pipeline temperature were measured. Results show that the larger is the leakage orifice, the lower is the minimum temperature of the inner pipeline. The larger is the concentrations of nitrogen (N2) in supercritical CO2 mixture, the lower is the minimum temperature of the inner pipeline, and the higher is the risk of pipeline brittle fracture. During the entire release process, the Nusselt number (Nu) was determined based on measurements to discuss the process of heat transfer between the CO2 mixture and pipeline wall. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.