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Effect of Kinetic Hydrate Inhibitor Polyvinylcaprolactam on Cyclopentane Hydrate Cohesion Forces and Growth

Wu, Reuben, Aman, Zachary M., May, Eric F., Kozielski, Karen A., Hartley, Patrick G., Maeda, Nobuo, Sum, Amadeu K.
Energy & Fuels 2014 v.28 no.6 pp. 3632-3637
cohesion, droplets, organic compounds, temperature
The effect of Polyvinylcaprolactam (PVCap), a commonly used kinetic hydrate inhibitor (KHI), on the cohesion force between cyclopentane hydrate particles was measured using a micromechanical force apparatus. The presence of PVCap in the aqueous bulk phase reduced the average hydrate cohesive force by 54% (from 1.49 to 0.69 mN/m). However, the cohesion forces did not vary significantly as a function of either the PVCap concentration (0.005–0.5 wt %) or the temperature (from 1.1 to 7.2 °C). When a layer of PVCap solution was applied to the surface of a pure cyclopentane hydrate particle in a bulk liquid cyclopentane phase, the interparticle cohesive force was reduced by 45% (from 4.3 to 2.4 mN/m). Hydrate growth on droplets of PVCap solutions was also studied by contacting a water droplet with a cyclopentane hydrate particle in a bulk cyclopentane phase. In cases where PVCap was absent, complete conversion of the water droplet to hydrate occurred within 30 s. However, when a water droplet of PVCap solution was brought into contact with a hydrate particle, hydrate film growth was significantly slowed, requiring over 2 h for complete conversion.