Abstract: In the process of solid⁃state mining of deep⁃sea natural gas hydrates, when the balance of temperature and pressure is broken, the hydrate slurry in the production pipeline changes from liquid⁃solid (hydrate, seawater) two⁃phase to gas⁃liquid⁃solid (natural gas, hydrate,seawater). The three⁃phase flow of particles and seawater is the main research object in gas⁃liquid⁃solid three⁃phase flow. The Fluent simulation of the hydrate slurry flow in the vertical production pipe is performed using the CFD⁃PBM model, and the model is verified. The simulation results are in good agreement with the experimental values. The results show that the distribution of flow patterns simulated by PBM model is relatively uniform, and the size of bubbles in the flow process is mainly from small to large， the initial velocity of bubbles has a great influence on the hydraulic lifting speed of the pipeline， the turbulent kinetic energy in the slurry is 0.5 m2/s3. When the content is 0.3, bubbles will appear to be secondarily broken and broken. The bubble size distribution in the hydrate slurry system can be predicted by CFD⁃PBM to better predict the flow characteristics of the hydrate slurry after it is decomposed by natural gas.

Key words: Natural gas hydrate, Vertical tube, Population balance model, Multiphase flow, Bubble aggregation and crushing

摘要： 　深海天然气水合物在固态开采过程中，当温度、压力平衡被打破时，开采管路中的水合物浆液由液固（水合物颗粒、海水）两相变为气液固（天然气、水合物颗粒、海水）三相的流动。以水合物浆液的气相为主要研究对象，采用CFD-PBM模型对气泡行为变化进行Fluent模拟，并对该模型进行了验证，模拟结果与实验值吻合度较高。结果表明，PBM模型模拟的浆液流态分布较为均匀，气泡的大小在流动过程中主要从小气泡到大气泡；气泡的初始速度对管道水利提升速度影响较大；在浆液湍动能为0.5 m2/s3、气含率为0.3时，气泡会出现二次聚并破碎。通过CFD-PBM计算得到水合物浆液体系中气泡大小分布能够较好的预测水合物颗粒分解出气相后的浆液流动特性。

关键词: 天然气水合物, 垂直管, 群体平衡模型, 多相流, 气泡聚并与破碎