Numerical simulation of hydrate particle behaviors in gas-liquid flow for horizontal and inclined pipeline

Gas hydrates can form in gas-liquid flow in the submarine natural gas production process, enormously challenging the flow safety. In this paper, a mathematical model is developed to describe the turbulent gas-liquid-hydrate multiphase flow system in horizontal and upward inclined pipeline. The population balance model is coupled for predicting the birth and death of hydrate particles, mainly concerning the collision, agglomeration and breakage mechanisms. Then, the effects of gas flow velocity, slurry flow velocity, hydrate volume fraction and pipeline inclination on the flow pattern and particle size distribution are analyzed. Moreover, considering the flow pattern transferred from stratified flow to slug flow, particle behaviors at slug body are also discussed. The results indicate that hydrate particles incline to agglomerate and locate at the bottom layer of pipe. Increase of hydrate volume fraction and hydrate slurry flow velocity will induce the flow pattern transition and intensification of particle agglomeration. Hydrate particle size distribution is more symmetrical at upward inclined part and eventually achieving a balanced state of agglomeration and breakage. The results can provide suggestions for avoiding gas hydrate blockage induced by agglomeration of hydrate particle in practical gas production.

Automated summary

This study develops a mathematical model to describe the turbulent gas-liquid-hydrate multiphase flow system in pipelines during natural gas production, analyzing the effects of gas flow velocity, slurry flow velocity, hydrate volume fraction, and pipeline inclination on flow pattern and particle size distribution. The study also discusses particle behaviors during the transition from stratified flow to slug flow, and indicates that increasing hydrate volume fraction and slurry flow velocity can lead to flow pattern transition and intensified particle agglomeration.