An experimental study on the flow characteristics during the leakage of high pressure CO2 pipelines

Abstract

High pressure pipeline transportation is dominant mode for economically transporting large amounts of CO2. However, potential leakage is one of the main risks associated with pressurized CO2 pipeline transportation. Thus, to investigate the leakage behavior of high pressure CO2 and to de-risk such transportations, a new laboratory scale experimental setup (total length of 14.85 m and the inner diameter of 15 mm) was constructed. Leakage experiments for pure CO2 and CO2 mixtures containing various N2 concentrations were carried out for different initial phase states (supercritical, liquid and gaseous respectively). The pressure and temperature characteristics and phase transitions of high pressure CO2 were then studied following pipeline leakage through small diameter nozzles. The results show that a minimum temperature occurs during the leakage process of various initial phase states; while the temperature characteristics of supercritical and gaseous CO2 leakage were rather different from that of liquid CO2 leakage. Impacts of impurity (N2), initial inner pressure and nozzle sizes on the leakage behavior were investigated, and two minimum temperature lines, based on N2 concentrations and initial inner pressures were obtained, respectively. These findings will ascertain that the pipeline is operated above the ductile-brittle transition temperature.