Measurement and Prediction of Surface Tension of Vacuum Distillates and Residues from Heavy Oil

Abstract

The surface tension of heavy oil and its temperature dependence were measured by the pendant drop method under atmospheric pressure in the temperature range of 30 to 250 °C. The surface tension was determined by fitting the numerical solution of the Young-Laplace equation to the image of a droplet hanging at the tip of a 1/16” stainless steel tube. The distillates and residues fractionated by vacuum distillation of atmospheric residue and bitumen were used as samples. The surface tensions of all samples decreased linearly with temperature. The fractionation of samples by column chromatography revealed that the samples, which were poor in saturates and rich in aromatics, had higher surface tension. In addition, a model on the basis of the principle of corresponding states was used to predict the surface tension of heavy oil. It was demonstrated that the model was capable of predicting the surface tension of the distillates with good accuracy, but it was insufficient to predict the surface tension of residue.