Abstract:

In order to investigate the leakage and dispersion patterns of gas-phase CO₂ transport pipelines with different hole sizes, outdoor CO₂ leakage test with apertures of 50 mm, 100 mm and 233 mm were carried out based on industrial pipelines. Firstly, according to the pressure drop experiment, the variation law of the pressure in the pipe with the leakage time was analyzed. Then, based on the established theoretical model, the leakage flow and pressure drop changes were predicted and verified by experiments. Finally, the variation of CO₂ volume fraction at different positions of the leakage port was studied. The result shows that the pressure drop rate in the first stage of leakage is the largest. Among them, the pressure drop rate of the three leakage hole sizes is 93.4-1967.5 kPa/s. It takes 14.2-149.8 s for the pressure in the pipe with three leakage hole sizes to drop to the ambient pressure. With the increase of the leakage hole size, the pressure drop process tends to be a cliff type drop. According to the established theoretical model, the relative error between the calculated leakage quality and the experimental actual release is 0.25%-4.54%. The pressure drop curve obtained based on the predictive model is generally slightly lower than the experimental pressure drop curve. However, the variation trend and duration of pressure drop are very close to the experimental results. It shows that the established theoretical method for predicting leakage quality and pressure drop is reliable. In the range of 5-17 m from the leakage port, the peak volume fraction increased significantly with the increase of the leakage hole size. The peak volume fraction of different leakage hole size outside the range of 17 m approaches the same. The dispersion distance of 5% volume fraction of gaseous CO₂ leakage is 26 m.

Key words: leakage hole size, carbon dioxide pipeline, pressure drop, dispersion, leakage quality, leakage test