Clathrate hydrate formation and crystal growth with additives

Abstract

Surfactant and hydrophobic materials are often used to accelerate hydrate formation. The effects of Tween80, decanoic acid (S10) and dodecyl alcohol (C10) on hydrate crystal growth after the nucleation of hydrate are investigated in this work. The droplets with HCFC-141b enhances hydrate formation. In the cycling procedure of formation and dissociation of hydrate, the hydrate formation with Tween80 has better stability than the system without Tween80. Additives alter the growth mode of hydrate crystal. The hydrate crystals grow at almost the same rate everywhere along the crystal growth direction in the presence of the mixture of decanoic acid and dodecyl alcohol (S10-C10) or S10-C10 + Tween80. However, hydrates grow at different rates at different sites when only Tween80 is used as additive. The hydrate lateral average growth rate (HLAGR) of crystals in the presence of 1 wt% S10-C10 and 1 wt% Tween80 is higher than that in the presence 1 wt% S10-C10. The influence of additives on hydrate crystal morphology is also studied. Clathrate hydrate crystal plates is scattered when S10-C10 is added in this work. When surfactant Tween80 is added in the experimental system, there is only one big clathrate hydrate crystal plate. There are some spicules crystals on the big crystal plate surface in the system of HCFC-141b + Tween80 + H2O.