Vapor pressure and thermal properties of heavy oil distillation cuts

The vapor pressure, liquid heat capacity, and heat of combustion were measured for distillation cuts obtained from several heavy oils using a deep vacuum fractionation apparatus. Derivatives of fitted vapor pressure equations were used to determine heats of vaporization based on the Clausius–Clapeyron equation. Existing correlations were evaluated against these data and new correlations were proposed including a generalized Cox vapor pressure correlation (as a function of molecular weight and boiling point temperature) and a correlation for the heat of vaporization based on the generalized Cox equation. Two versions of Tsonopoulos correlations were developed for liquid heat capacity: one using the Watson Factor and another using the H/C ratio. In general, the new correlations improved the prediction of heavy cut properties compared with correlations from the literature and performed similarly for light cuts (both for the development dataset and for independent test datasets). In addition, the heats of combustion of some cuts were measured and used to validate the elemental analysis based correlations from the literature.