Numerical simulation of hydrate slurry flow behavior in oil-water systems based on hydrate agglomeration modelling

Hydrate agglomeration in oil-water systems could lead to pipeline hydrate plugging. Dynamic modeling of pipeline hydrate particle agglomeration is of great importance to hydrate management. For this purpose, a dynamic model of hydrate agglomeration was established based on population balance equation, which took both hydrate agglomeration and hydrate breakage into consideration. The calculation methods of collision frequency, agglomeration efficiency, breakage frequency and particle size distribution function of the sub particles resulting from particle breakage were given and fully discussed in the dynamic model. Then, combined with several traditional solid-liquid flow models, the dynamic model was solved by the CFD software FLUENT 14.5 to simulate the influences of flow rate and hydrate volume fraction on pipeline hydrate slurry flow behavior in oil-water systems. The simulation results show that hydrate particle size distribution in pipeline flowing systems can be well described by log-normal distribution. Hydrate particle diameters and hydrate volume concentrations in the near wall region are larger than that in the center region of the pipeline. The proportion of large hydrate particles and the mean hydrate particle diameter in pipeline increase with the increase of flow rate and hydrate volume fraction. Hydrate particle diameter and pressure gradient in oil-water systems are larger than that in water systems.