Study on a Numerical Model of Hydrate Bed Critical Velocity in Solid–Liquid Two-Phase Flow Pipelines

Abstract

A hydrate bed critical velocity model is developed, including a hydrate bed limit deposition velocity model and a hydrate bed suspension velocity model. The innovation of this paper is to consider the hydrate bed pressure and liquid bridge force on hydrate particles when building the limit deposition velocity model and to modify Dai’s model by using hydrate experimental and simulation data when building the suspension velocity model. The hydrate bed critical velocity model is negatively correlated with the particle size and positively correlated with the pipe diameter, particle density, and particle volume fraction. The accuracy of the model is demonstrated by validation. The hydrate bed critical velocity model can be used to calculate the hydrate fixed-bed and moving-bed height under different conditions, based on which the flow pattern map of hydrate particles and the hydrate blockage risk classification method are established, which is a certain guidance to ensure the safety of hydrate flow in the pipeline.

Rheology of Methane-Hydrate-Slurry Flow in 100% Water Cut System and Influence of Turbulent–Laminar Transition

“…Although models based on the three-layer concept are sometimes employed in hydrate studies, , our images of hydrate-slurry flow do not appear to match the three-layer model of Doron and Barnea, which does not consider the cohesive force between particles. This model assumes cubic packing (52% of the solid concentration) for bedding layers: under this assumption, 3.7 vol % of hydrate can only occupy about 7.1 vol % (≈ 3.7 vol %/0.52) of the system.…”