Effect of pressure on the solid–liquid equilibria of synthetic paraffin mixtures using predictive methods

The solid–liquid equilibria of paraffin mixtures are studied from low to high pressures. The liquid phase is described by a cubic equation of state. The solid phase is described by solid UNIQUAC and a pressure dependence term resulted from Clapeyron equation. The developed model accurately predicts the wax disappearance temperature of pure, binary and multicomponent paraffin mixtures for wide ranges of temperature, pressure and composition. Further, the model reasonably predicts the amount of wax precipitated and wax composition from low to high temperatures and at any pressure. When compared to other models, the developed model is in better agreement with experimental data in predicting wax disappearance temperature. In predicting wax deposit and composition, the developed model is similar to the well-known models in the literature.

► Wax precipitation depends on composition, temperature and pressure.
► With increasing pressure, wax disappearance temperature is predicted accurately using the appropriate models.
► With decreasing temperature, wax disappearance temperature is predicted less accurately.
► Equations of state can be used for describing liquid phase.
► Solid UNIQUAC can be used for describing solid phase accurately.