Vapor-hydrate two-phase and vapor-liquid-hydrate three-phase equilibrium calculation of THF/CH4/N2 hydrates

Tetrahydrofuran (THF) is a popular thermodynamic promotor for gas hydrates. Nonetheless, the phase equilibrium calculations of THF hydrates are limited given the abundant experimental data. In this work, we successfully applied the Chen-Guo hydrate model to the THF/CH4/N-2 system with different compositions of CH4/N-2 gas mixtures. In consideration of various reaction conditions, we proposed the vapor-hydrate two-phase and vapor-liquid-hydrate three-phase models for the equilibrium separations of THF/CH4/N-2 via hydrate formation. The hydrate formation condition and equilibrium separation of CH4/N-2 in 6 mol% THF solution were calculated and compared with experimental results. The average absolute relative deviations between the experimental and calculated data for hydrate formation pressure and equilibrium separation compositions are 6.86% and 7.56%, respectively. This demonstrates that the Chen-Guo model has relatively high accuracy for the equilibrium calculation of THF/CH4/N-2 hydrates. This work provides an effective approach to predict the thermodynamic phase behavior of hydrates containing promotors or inhibitors. (C) 2015 Elsevier B.V. All rights reserved.