Clathrate hydrate equilibria in light olefins and mixed methane-olefins systems

Light olefins such as ethylene and propylene are widely used in industry and combined with water and the correct thermodynamics conditions can form hydrates. In this paper, we report the results of new experimental measurements on the locus of incipient hydrate liquid water vapour curve for pure ethylene, propylene, ethylene + propylene, methane + propylene and ethylene + ethane systems. Two different thermodynamic approaches were employed to investigate the phase behaviour of pure olefins and mixed systems: the Valderama-Patel-Teja (VPT) equation of state combined with the non-density-dependent (NDD) mixing rules and the Cubic-Plus-Association equation of state. In both cases, the hydrate-forming conditions are modelled by the solid solution theory of van der Waals and Platteeuw. The parameters of the thermodynamic model were regressed using ethylene and propylene solubility in water and the hydrate dissociation point data of simple hydrates. The developed model was used to predict the hydrate dissociation conditions of the systems investigated in this work. Predictions of the developed model are validated against independent experimental data and the data generated in this work. A good agreement between predictions and experimental data is observed, supporting the reliability of the developed model. (C) 2012 Elsevier B.V. All rights reserved.