Modeling of Hydrate Dissociation Curves with a Modified Cubic-Plus-Association Equation of State

A modified cubic-plus-association equation of state (CPA EoS) has been presented in recent works that enforces the representation of the pure component critical point, is based on an extended Mathias-Copeman alpha fiinction, and uses a volume shift to improve liquid densities. In this work, this same version of the CPA model is applied together with the hydrate van der Waals and Platteeuw model for the description of hydrate dissociation curves. The model is applied to the description of both single and mixed guest hydrates, the results being compared with the available experimental data, and the predictions obtained using the commercial hydrates model from the Multiflash software. This analysis shows that, for most cases, this approach is accurate, with results similar to those of Multiflash. The accuracy of the model for describing the three phase compositions in hydrate + liquid + gas systems is also discussed.