Study of the Microscopic Effect of PVCap on CO₂ Hydrate Generation and Adhesion

In the transportation of carbon dioxide through pipelines, the formation of hydrates presents a significant challenge, potentially obstructing the pipeline flow and compromising operational safety. One of the effective hydrate inhibition strategies to mitigate economic losses is adding poly(N-vinylcaprolactam) (PVCap). This study aims to investigate the effect of PVCap on hydrate inhibition performance using a high-pressure visualization stirring reactor to conduct experiments on CO2 hydrate generation characteristics. Employing microscopic equipment, the study assesses PVCap's influence on various parameters including the induction time of hydrate generation, gas consumption rate, and adhesion between hydrate particles. The experimental results indicate that PVCap can effectively inhibit the generation of carbon dioxide hydrate compared to a pure water system. The inhibition effect of PVCap on hydrate increases within the concentration range of 0-1.5 wt %. However, this effect diminishes at higher concentrations (2 wt %), attributed to PVCap's adsorption onto the cage structure of hydrates. Consequently, the increased adsorption interferes with mass transfer at the gas-water interface. In addition, PVCap influences the surface roughness of hydrate particles, reducing particle adhesion within the 0-1.5 wt % concentration range but exacerbating at higher concentrations (2 wt %). This investigation sheds light on PVCap's role in hydrate inhibition, crucial for ensuring the secure flow of hydrates in pipeline operations.