A Kinetic Study on Tetrahydrofuran Hydrate Crystallization

Abstract

Various aspects of crystallization of THF hydrate have been studied. It has been found that formation of THF hydrate is possible between solution concentrations of 9 and 46% by weight. Induction time for nucleation in various solutions has been determined. The results indicate that the lowest induction time for nucleation corresponds to solutions with a THF concentration of 19% by weight. This solution concentration matches with the THF composition in the crystalline hydrate. The metastable zone for primary nucleation has been investigated and concluded that for each stirrer speed, THF hydrate forms at a higher temperature when the solution concentration is 19% by weight. The next conclusion is that the higher the stirrer rate, the narrower the metastable zone. Nucleation and growth rates have been evaluated from a series of experiment by s-plane analysis. Compared with the growth rate, nucleation rate has been found to be a stronger function of the stirrer speed. Both rates increase with subcooling but in the case of the growth rate, only a slight increase has been observed at high levels of subcooling and stirrer speeds. A regression analysis resulted in derivation of kinetics correlations between the significant process variables and the consistency between the correlations and the experimental data has been examined.