埋地CO2管道运行过程中,因人为或其他因素发生管道泄漏,管内因相变和节流形成的低温区域可能引发管道本体韧脆转变,造成脆性断裂,同时会在泄漏口附近区域形成冻土,可能造成更严重的影响,目前缺乏针对埋地CO2管道泄漏管壁低温分布规律的研究。现针对埋地CO2管道的运行,研究了两种相态、不同管内运行压力、不同泄漏孔径、不同泄漏孔径与主管管径比、不同流动状态以及不同孔隙率的埋地CO2管道泄漏对管壁温度分布规律的影响。研究结果表明:密相CO2管道运行比超临界相CO2管道运行更加危险,发生泄漏后密相管壁温度更低,低温影响管段距离更长;在模拟条件下,密相CO2管道泄漏过程中,低压力、小泄漏孔径比、大土壤孔隙率时为最危险工况,管壁最低温度约-48.8 ℃。研究成果可为CO2管道选择及泄漏管道维抢修提供参考。

 During the operation of buried CO2 pipeline, pipeline leakage occurs due to human factors or other reasons, and the low-temperature zones formed inside the pipe by phase change and throttling can induce a ductile-to-brittle transition in the pipeline material, resulting in brittle fracture. Meanwhile it can lead to the formation of frozen soil near the leak site, potentially causing more severe impacts. At present, there is a lack of research on the low-temperature distribution patterns on the pipe wall during leakage in buried CO2 pipelines. This study investigates the effects of two phase states, various internal operating pressures, different leak aperture sizes, different ratios of leak aperture to main pipe diameter, different flow regimes, and varying porosities on the temperature distribution of buried CO2 pipelines during leakage. The research results show that the operation of dense-phase CO2 pipeline is more hazardous than that of supercritical CO2 pipeline. After leakage, the temperature of dense-phase pipe wall is lower, the low-temperature affected section is longer. Under the simulated conditions in this paper, in the leakage process of dense-phase CO2 pipeline, the most critical conditions for dense-phase CO2 pipeline leakage are low pressure, small leak aperture ratio, and big soil porosity, with the minimum temperature of pipe wall reaching approximately -48.8 ℃. The research results can provide reference for CO2 pipeline selection as well as maintenance and emergency repair of leaking pipelines.