CO2水合物在管道中的生成及堵塞特性

为明确CO₂水合物在管道中的流动及堵塞特性，通过高压可视水合物环路研究了不同持液量下的水合物生成及堵塞特性，研究结果表明：水合物生成诱导时间随着持液量的增大出现非线性变化，呈V形，先减小后增大；管道持液量越大，水合物生成量越少，水合物发生堵塞时的临界体积分数降低，如在持液率86.6%下，堵塞时水合物体积分数为4.32%，持液率为66.7%时，堵塞时水合物体积分数为7.45%。通过可视管路发现当CO₂水合物大量生成后，管道中压降将突然增大，颗粒之间快速聚集生长，流速迅速降低，CO₂水合物快速充满管道使管道发生堵塞，水合物颗粒不断生长及在聚集层处的聚集导致流动阻力的增加是其产生堵塞的根本原因。研究结果可为CO₂水合物浆液流动保障提供技术支撑。

CO2 hydrate formation in pipeline and its plugging characteristics

In order to clarify the flow and plugging characteristics of CO₂ hydrates in the pipeline, the hydrate formation and plugging characteristics under different liquid holdups were studied through a high-pressure visible hydrate loop. The results showed that the induction time of hydrate generation was consistent with the liquid retention. The increase of the quantity appeared a non-linear change, showing a V-shape, which decreased first and then increased. The greater the liquid holding capacity of the pipeline, the less the amount of hydrate formation and the critical volume fraction when the hydrate was clogged. For example, in the liquid holding rate at 86.6%, the volume fraction of hydrates was 4.32% when the plugged, while in the liquid holdup of 66.7%, the hydrate volume fraction was 7.45% when plugged. Through the visual pipeline, it was found that when a large amount of CO₂ hydrate was generated, the pressure drop in the pipeline would suddenly increase, the particles rapidly accumulate and grow, the flow rate decrease rapidly, CO₂ hydrate quickly fill the pipeline, the pipeline be blocked, and the hydrate particles continue to grow. The increase in flow resistance caused by the aggregation at the accumulation layer was the main reason of the blockage. The research results can provide technical support for the protection of CO₂ hydrate slurry flow.