流动体系下水合物生成及其影响的CFD-PBM数值模拟

Numerical simulation of hydrate formation and influence in flowing systems by CFD-PBM

海底油气混输管线因水合物生成引起堵塞问题备受关注。基于CFD-PBM模拟海底管道实际工况下水合物的生成过程,分析水合物生成对气泡的聚并和破碎行为及各相流速的影响,结果表明:当管道的运行环境达到水合物形成条件时,在气液界面逐渐有水合物生成,并在管壁上方堆积。水合物生成消耗一定量气体,导致压降降幅增大,同时产生的水合热导致局部温度升高,但传热受阻使得流体温度提升较小。没有水合物生成时,气泡以聚并为主,气泡直径分布较窄且相对均匀。水合物生成后,气泡大小分布范围变宽,但主要集中在较小直径范围。水合物在气液界面生成并在管壁上方堆积,导致流速局部分布不均,相间滑脱加剧。研究管道流动体系下水合物生成及其影响为管输水合物浆液的稳定安全流动提供理论参考。

The plugging of submarine mixed transfer pipelines has attracted much attention due to hydrate formation.Based on the CFD-PBM model,the process of hydrate formation in the submarine pipeline was simulated.The effect of hydrate formation on the coalescence and fragmentation of bubbles and the influence of the velocity of each phase was analyzed.The results show that when the operating environment of the pipeline reaches the hydrate formation conditions,hydrate gradually generates at the gas-liquid interface and accumulate above the tube wall.Hydrate generation consumes a certain amount of gas,which results in a larger drop in pressure drop.At the same time,the heat of hydration causes a local temperature increase,but the heat transfer is hindered so that the temperature of the fluid increases little.In the absence of hydrate formation,the bubbles are mainly agglomerated,and the bubble diameter distribution is relatively narrow and uniform.After the formation of hydrates,the bubble size distribution range is widened,but it mainly concentrates in the smaller diameter range.Hydrates generate at the gas-liquid interface and accumulate on the wall of the tube,resulting in uneven local distribution of velocity and increasing slippage between phases.Study of hydrate formation and its influence in pipeline flow system provides a theoretical reference for the stable and safe flow of hydrate slurry.