Modelling lubricating oil fractions by means of a pseudo-component model
Advancing the chemical engineering fundamentals
Thermodynamics (T2-1P)
Keywords: liquid-liquid equilibrium, modelling, aromatics extraction, simulation, lubricating oil
Modelling lubricating oil fractions by means of a pseudo-component model
B. Coto*, R. van Grieken, J.L. Peña**, J.J. Espada
Chemical and Environmental Technology Department. Universidad Rey Juan Carlos. E-28933 Móstoles, Madrid (Spain)
*Corresponding author: baudilio.coto@urjc.es; Telephone: +34 91 4887089;
Fax: +34 91 4887068;
**Alfonso Cortina Technology Centre, Repsol-YPF, E-28933 Móstoles, Madrid, Spain.
One of the key steps in the lube oil manufacturing process from crude oil vacuum distillates is the aromatic compounds reduction by solvent extraction, commonly furfural. To correctly design and operate this process, a good knowledge of the liquid-liquid equilibrium (LLE) for that system is necessary. Recently, a generalized model has been reported to correctly describe the LLE in the extraction operation and the physical properties of the obtained mixtures. The only three pseudo-components considered, based on the chemical structure, were saturates, aromatics and polars. The physical properties of such pseudo-components and the NRTL binary interactions between them have been linearly correlated with the average boiling point (T50%) within the range SPD (light lubricating oil)-HND (heavy lubricating oil). The accuracy of the model is shown by modelling the aromatics extraction by furfural from SPD and HND lubricating oils with T50% values of 378°C and 528°C, respectively. Different extraction experiments, using SPD and HND lubricating oils as feed and furfural as solvent, were carried out by modifying temperature and solvent/feed ratio. Physical properties (density and refractive index at 70°C and sulfur content) were experimentally determined by ASTM standard test methods for raffinates and extracts. Extraction operation was simulated using AspenTech by a decanter and the generalized model. Physical properties of the involved mixtures were calculated by means of a mixing rule using the pseudo-component properties and the composition calculated by simulation. Obtained values were compared to the experimental ones, obtaining good concordance. The accuracy of such calculated values was checked by comparison to those obtained using other methods reported in the literature. Such methods allow to calculate physical properties of petroleum mixtures from previously available information using different correlations. In all cases, no remarkable discrepancies were found between the values obtained by the generalized model and those obtained by other methods.
Presented Monday 17, 13:30 to 15:00, in session Thermodynamics (T2-1P).
