Dissociation equilibrium height and friction coefficient in pipeline transportation of gas hydrate-bearing sediment particles

Abstract

Compared with traditional fossil fuels, gas hydrates have vast reserves, cause little pollution, and are an essential strategic energy resource. Pipeline transportation is critical to realize the development and utilization of natural gas hydrate resources. The Eulerian multiphase flow model within the computational fluid dynamics software FLUENT was employed to calculate gas–liquid–solid flow, taking into account phase interactions, heat transfer, and collision among particles. Pipeline transportation of gas hydrate-bearing sediment (GHBS) particles was studied based on dimensional analysis and numerical simulation. First, the essential dimensionless numbers controlling multiphase flow and hydrate dissociation were deduced. Further, the obtained simulation results clearly indicate that when the system was in a stable state, there was a dissociation equilibrium height above which hydrate dissociated completely. The influences of the dimensionless numbers on the dissociation equilibrium height and friction coefficient in the pipe were determined, and power-law correlations for the dissociation equilibrium height and friction coefficient were obtained from the numerical data. Finally, an analytical expression of dissociation equilibrium height was derived by decoupling the solid–liquid flow and gas hydrate dissociation, and the validity of the power-law correlation for the dissociation equilibrium height was verified by the analytical expression.