Kinetic study on the process of CHClF2 (R22) hydrate formation in the presence of SDS surfactant based on chemical affinity

The experimental and theoretical investigations were performed for two systems containing pure water and a sodium dodecyl sulfate (SDS) aqueous solution of 822 gas hydrate. Herein, we proposed a kinetics model based on chemical affinity to describe the crystal growth process for R22 hydrate in a stirred batch reactor at a constant volume. The kinetic experiments were conducted at different temperatures of 276.15, 278.65, 280.15, 281.65, 283.15 and 285.15 K; and in the same driving force of pressure about 3.5 bar. Additionally; the stirred speed was adjusted to 400 and 910 rpm at a constant temperature of 285.15 K to explore the relationship between the stirred speed and the rate of hydrate formation. The experimental results show that SDS accelerates R22 hydrate formation, both at higher temperatures and lower stirred rates. The parameters of kinetic model, A(r)/RT and t(K), were obtained for each experiment both with and without surfactant. Based on the results, A(r)/RT has a constant value of approximately -0.9. Then, the modeling parameters were used to predict the experimental results as the pressures variation during time of process. The good agreement was found between the predicted and the experimental data. So this model is able to predict of 822 hydrate formation conditions. (C) 2014 Published by Elsevier B.V.