天然气水合物三相流段管道压力损失分析

Analysis of pressure loss in three-phase flow segment of natural gas hydrate

徐海良,孙思聪,杨放琼

XU Hailiang, SUN Sicong, YANG Fangqiong

中南大学机电工程学院，湖南 长沙 410012

School of Mechanical and Electrical Engineering, Central South University, Changsha 410012, China

水力输送系统是海底天然气水合物绞吸式开采系统的核心设备之一，输送管道的工作性能决定了整个采矿系统的工作效率。文中主要研究了天然气水合物绞吸式开采管道输送过程中，水合物分解后管道三相流段的压力损失规律。基于计算流体力学和FLUENT软件，采用欧拉模型配合CFD￣PBM模型分析了管径、流速、固相和气相体积分数、粒径、气泡平均直径对管道压力损失梯度的影响。结果表明：管道压力损失梯度随着管径增加而减小，在管径大于300 mm后压力损失梯度减小缓慢并开始趋于稳定，在450 mm处压力损失梯度骤降，500 mm以后再次趋于稳定；随着浆体流速增大，管道三相流段压力损失梯度先减小后增大，存在一个最优流速，且最优流速随着粒径增大而增大；固相体积分数和颗粒直径都与压力损失梯度成正比，但体积分数的影响较大，粒径的影响较小；气相体积分数在0.3以内与压力损失梯度成反比，表明了少量气体的减阻效应；气泡平均直径过大会减小有效管径，导致压力损失梯度增大。

The hydraulic conveying system is one of the core equipment of the cutter-suction mining in submarine natural gas hydrate exploitation, the working capacity of the pipeline determines the working efficiency of the entire mining system. The pressure loss of the three-phase flow section of the pipeline after the decomposition of hydrates was studied in the process of gas pipeline hydrate cutter-suction mining. Based on computational fluid dynamics and FLUENT software, Euler model and CFD-PBM model were used to analyze the effects of pipe diameter, flow velocity, volume fraction of solid phase and gas phase, particle diameter and the average bubble diameter on the gradient of pressure loss. The results show that the pipeline pressure loss gradient decreases with the increase of pipe diameter. After the pipe diameter is greater than 300 mm, the pressure loss gradient decreases slowly and tends to be stable. When the pipe diameter reaches 450 mm, the pressure loss gradient drops sharply. After the pipe diameter is greater than 500 mm, the gradient is gradually becoming steady; As the slurry flow rate increases, the pressure loss gradient in the three-phase flow section of the pipe decreases first and then increases. There is an optimal flow velocity, and the optimal flow velocity increases with the increase of the particle diameter; both the solid particle volume fraction and the particle diameter are positively correlated with the pressure loss gradient, but the volume fraction has a greater effect and the particle size has less effect. The gas phase volume fraction is negatively correlated with the pressure loss gradient within 0.3, indicating the drag reduction effect of a small amount of gas; when the average bubble diameter is too large, the effective diameter decreases and the pressure loss gradient increases.

10.6056/dkyqt202105016