Effects of methanol and ethylene glycol on the interactions between methane hydrate particles and water droplets

Abstract

Hydrate particle agglomeration is one of the main causes of hydrate blockage in pipelines. Although methanol (MeOH) and ethylene glycol (MeG) are the most used thermodynamic hydrate inhibitors, their effects on the micromechanics behavior of natural gas hydrate particle agglomeration are not clear. In this study, the effects of MeOH and MeG on the interaction force between methane hydrate particles and droplets were investigated using a self-built high-pressure hydrate microforce measuring device. The results suggest that, with the concentration increase from 1% to 7%, for the system with MeOH, the adhesion force reduced by 11% to 33%, while for MeG, the adhesion force reduced by 15% to 43%. On the one hand, the addition of inhibitors reduces the phase equilibrium temperature, which decreases the solidification rate of water in liquid bridge, and on the other hand, they reduce the interfacial tension. both reductions lead to lower adhesion force. Furthermore, in comparison with MeG, the MeOH solutions present a lower contact angle, resulting in a larger hydrate particle-droplet contact area and thus relatively higher adhesion force. The measurement and observation in the present work provide new insight into the mechanism of methanol and ethylene glycol on inhibiting hydrate agglomeration, which is important in advancing the management of hydrate formation in pipelines.