Thermodynamic Framework for Successive Flash Calculations involving mixed Clathrate Hydrates

Modelling non-stoichiometric solids such as gas hydrate from gas mixtures is quite a challenge when it comes to predict phase equilibria and volume. In this work, a non-stoichiometric flash approach to predict hydrate crystallization under non-thermodynamic equilibrium conditions in close volume is presented. Results are compared to batch experiments at low and quick crystallization rates, and to a more standard flash approach. Final pressure and hydrate volume are predicted within 5% accuracy and 20%, respectively. Moreover, simulations with no hydrate reorganization are closer to experiments at quick crystallization rate, whereas the experiments at low crystallization rate are better predicted with the homogeneous hydrate flash.