Enhanced Hydrate Inhibition by Plant-Based Polysaccharides as Synergists with Kinetic Hydrate Inhibitors

Three plant-based polysaccharides, pectin, k-carrageenan, and guar gum, are investigated as synergists with four kinetic hydrate inhibitors (KHIs), polyvinylpyrrolidone, polyvinylcaprolactam, Luvicap55w, and HIOP. The enhancement in the hydrate inhibition performance is characterized by measuring the increase in the delay/induction time (IT) taken for hydrate nucleation and the reduction in hydrate growth after nucleation. Standardized constant cooling rate hydrate formation tests are performed. Experimental results provided by 0.5 wt % aqueous solutions of reference KHIs are compared with the results of aqueous solutions made with combining 0.25 wt % reference KHI with 0.25 wt % polysaccharide synergist. K-carrageenan showed exceptional inhibition synergy with all KHIs with ITs enhanced around 20–35% with different reference KHIs and reduced hydrate growth rates up to 90%. Guar Gum did not increase the IT provided by reference KHIs. However, it decreased hydrate growth rates by 77–90% of all KHIs. Pectin showed exceptional hydrate inhibition synergy with HIOP (commercial KHI), boosting its IT by 45%.