超临界CO_2管道停输过程中安全控制研究

Research on Safety Control for Shutdown of Supercritical CO_2 Pipeline

鉴于目前对超临界CO2管道停输过程中管内温度变化及压力流量脉动冲击相关研究较少的现状,结合CO2准临界特性,研究了停输工况下超临界CO2管道内流体的变化规律,并针对停输及启输过程提出了相应的安全控制建议。研究结果表明,进入准临界区的CO2密度将在温度微小变化下发生剧烈波动,密度的剧烈波动使管内CO2流体体积波动变化,在管道固定体积约束下,剧烈波动的CO2流体将对管道产生剧烈的脉动冲击,危害管道安全;超临界CO2对管道轴向的波动变化体现为密闭管道内流体的脉动流量,管内CO2的脉动流量出现时间与脉动压力出现时间完全对应;超临界CO2管道停输时间存在危险时间范围,在危险时间范围到来之前结束停输可以避免对管道系统的冲击危害。

There are few researches on pipeline temperature change and pressure-flow pulsation impact during shutdown of the supercritical CO2 pipeline. This paper discusses the variation pattern of fluids in the supercritical CO2 pipeline under the condition of shutdown considering the pseudocritical CO2 characteristics, and proposes ap- propriate safety control suggestions for shutdown and startup. The results show that, density of CO2 in the pseud- ocritical area will fluctuate severely in case of subtle temperature change so as to change pipeline CO2 fluid volume ; under the restriction of fixed pipeline volume, sharply changed CO2 fluids will cause severe pulsating impact on the pipeline to adversely affect pipeline safety ; pulsating flow of fluids in the closed pipeline can indicate axial fluctua- tion of supercritical CO2 and the pulsating flow of CO2 in the pipeline has the same occurrence time with pulsating pressure ; shutdown of the supercritical CO2 pipeline has a range of time at risk, so the pipeline shall be shut down before the time at risk to avoid impact on the pipeline system.