Influence of Low‐Dosage Hydrate Inhibitors on Methane Clathrate Hydrate Formation and Dissociation Kinetics

Abstract

AbstractThis work investigates the effect of low‐dosage hydrate inhibitors (LDHIs) on methane hydrate formation and dissociation. The hydrate inhibitors used in this study were the sodium salt of polyacrylic acid, a polysaccharide chitosan, and the linear sulfated polysaccharide i‐carrageenan; the inhibiting behavior of these additives were compared with that of the commonly used hydrate inhibitor polyvinylpyrrolidone for methane hydrate formation. A LDHI concentration of 1 wt % was found to increase the induction time relative to that at a LDHI concentration of 0.1 wt %. Chitosan was found to be better than the others in reducing nucleation and the growth rate of the hydrate at a concentration of 1 wt %. At a lower concentration of 0.1 wt %, nucleation inhibition was minimal, however, growth inhibition was significant. The effect of these inhibitors on the decomposition rate of the hydrate was also studied, and the decomposition kinetics at a constant driving force in excess of three‐phase equilibrium is reported.