Modelling of Liquid-Vapour Equilibria in the H2O-CO2-Nacl and H2O-H2S-NaCl Systems to 270°C

J. Dubessy (1) , A. Tarantola (1, 2) , J. Sterpenich (1)

1 G2R - Géologie et gestion des ressources minérales et énergétiques
2 Mineralogisch-Petrographisches Institut

An unsymmetric thermodynamic model for the liquid-vapour equilibria in the H2O-CO2-NaCl and H2O-H2S-NaCl systems for temperatures below the critical point of water (250°C for H2S, 270°C for CO2) is presented. The vapour phase is described by a cubic Equation of state. The water and gas components in the liquid aqueous phase are respectively described by Raoult's law and Henry's law combined with a Redlich-Kister's model of regular solutions for the activity coefficients of these two components. After an analysis of the experimental data base, more than 80% for CO2 and 92% for H2S of predicted pressures of aqueous isopleths deviate less than 5%, which is comparable to experimental uncertainty. Although the model is not fitted on the composition of the vapour phase, the predicted values are correct above 100°C. The salt effect is modelled by a combination of the model of Pitzer for the water activity and an extension of Setchenow's law. The hypotheses behind this model makes it applicable at pressures below 300 bar.

Domaines: Physique [physics]

J. Dubessy, A. Tarantola, J. Sterpenich. Modelling of Liquid-Vapour Equilibria in the H2O-CO2-Nacl and H2O-H2S-NaCl Systems to 270°C. Oil & Gas Science and Technology - Revue d'IFP Energies nouvelles, 2005, 60 (2), pp.339-355. ⟨10.2516/ogst:2005021⟩. ⟨hal-02017197⟩