Correlation and prediction of properties of Karamay naphthenic vacuum fourth distillates during solvent refining
Density and refractive index as essential data in the design of solvent refining process are fundamental physical properties of oils.Solvent extraction of Karamay naphthenic vacuum fourth distillates by dimethyl sulfoxide(DMSO)was carried out to investigate the effects of extraction temperature and solvent-oil ratio.Furthermore,the relationship between density and refractive index as well as the quantitative variation of these properties with temperature during solvent refining were examined and evaluated in order to check the reliability of different correlations in property prediction.The results indicate that the aromatic content of the extracts can reach over 80%in the case of DMSO,and the modified quadratic correlation adequately describes the relationship between density and refractive index of naphthenic oils.Additionally,the density and refractive index of the naphthenic oils illustrates an approximately proportional relationship with temperature.Nonetheless,the proportional relationship is weakened with increasing temperature.The relationship between density/refractive index and temperature proposed by Yarranton et al.precisely predicts the density and refractive index of raffinates at different temperatures.