Select thermodynamic models for process simulation
A Practical Guide to a Three Steps Methodology

Example 4-9: Formation of hydrates

To illustrate the fact that various model can lead to the same description of thermodynamic behaviour, figure 1 shows the pressure dissociation curve of methane hydrates as a function of temperature. Two models are compared with data of Verma (1974)[1]. Both models use the Kihara parameters in the Van der Waals and Platteeuw theory, but for the vapour phase, Parrish and Prausnitz use a modified Redlich-Kwong equation of state (EoS), while Youssef et al. employ the Cubic plus Association (CPA) EoS that explicitly takes into account the association of water by hydrogen bouding.

image Figure 1: Dissociation conditions in PT diagram for methane hydrate (solid curve by Parrish and Prausnitz, 1972 [2]; dashed curve by Youssef et al. 2009[3]).

References

[1] VERMA V.K., Gas Hydrates from liquid Hydrocarbon-Water Systems, 1974.

[2] PARRISH W.R., PRAUSNITZ J.M., Dissociation Pressure of Gas Hydrates Formed by Gas Mixtures, Industrial & Engineering Chemistry Process Design and Development, 1972, 11, n°1, p. 26-35. http://dx.doi.org/10.1021/i260041a006

[3] YOUSSEF Z., BARREAU A., MOUGIN P., JOSE J., MOKBEL I., Measurements of Hydrate Dissociation Temperature of Methane, Ethane, and CO2 in the Absence of Any Aqueous Phase and Prediction with the Cubic Plus Association Equation of State, Industrial & Engineering Chemistry Research, 2009, 48, n°8, p. 4045-4050. http://dx.doi.org/10.1021/ie801351e