Microscopic morphology evolution of the crystal structure of tetrahydrofuran hydrate under flowing condition

Abstract The evolution of the hydrate particle structure during growth and agglomeration under flowing condition affects the particle as well as flow characteristic, which plays an important role in the flow assurance as well as heat transfer in refrigeration systems. Therefore, this article conducts experiments to study and observe the growth and agglomeration process in the main forming stage of hydrate. It was found that the growth of tetrahydrofuran hydrate was anisotropic and in a layered growth pattern. Single crystals generally transformed from octahedral structure to octahedral skeleton structure with growth, however some single crystals also deformed into plate type particles. The thickness of the plate type particles increased gradually during growth, and the edge part increased earlier than the middle part. During agglomeration, the hydrate particles contacted and sintered together. Sand as the impurity didn’t serve as the nucleation center but affected the agglomeration of hydrate particles by collisions. In addition, the effect increased as the sand size decreased. Finally, a microstructure model for hydrate growth and agglomeration was proposed, which showed the hydrate structure evolution in these processes and could lay a foundation for studying the flow assurance of hydrate slurry.