Characterization of the pressure, temperature, and phase evolution during pipeline leakage in full-size ethane high-pressure gas pipeline

A leak may occur in the ethane transport pipeline during operation, which brings serious pipeline transportation risks. Exploring the pressure, temperature and phase evolution during pipeline leakage is the basis for constructing pipeline safety technology. To this end, a full-scale ethane pipeline experimental platform was established to carry out leakage experiments at different diameters, and the pressure, temperature, and phase changes of the ethane inside the pipeline and the temperature changes of the pipeline outer wall were investigated. The experimental results show that during the ethane injection process, the turning point of the pressure increase rate is 4.26 MPa; the turning point of the temperature decrease rate is 14.26 °C and 12.07 °C. During the overall process of leakage, the ethane temperature showed the trend of “near hot and far cold” from the leakage port position. The critical diameter for the maximum temperature-difference and phase change time difference between the near and far ends of the leakage port is 15 mm, and the temperature-difference reaches 5.49 °C, the time difference of 121 s, which show a tendency of increasing and then decreasing when leakage diameter increase. In addition, the temperature of the outer wall of the pipeline shows the trend of “near cold and far hot” from the leakage port position, and the temperature of the center point of the pipeline is higher. The temperature-trough difference between different monitoring points shows a tendency to increase with the increase of leakage diameter, reaching a maximum of 5.81 °C. The conclusion of the study provides guidance for the investigation of the changing characteristics including temperature, pressure and phase state in the process of ethane pipeline leakage, which is helpful for the construction of pipeline safety technology system.