Prediction of Solubility in Heavy Ends by Means of PHCT

The paper deals with the possibility of predicting phase behavior of oil solutions in light hydrocarbon solvents. Such mixtures contain very many components: one or two well defined light alkanes (solvents) and one poorly defined continuous oil. Having significantly different molecular size, they can exhibit very non ideal phase bahavior. We consider a heavy end (residue) which is similar to the feed for deasphalting processes. The fraction is characterized on the basis of Henry's constant data measured by gas liquid chromatography of light hydrocarbons in the heavy end. The heavy end is represented using pseudo-components. The Henry's constant gives all the information relative to the interactions between the light hydrocarbons (solvent) and the model components of the heavy oil. The procedure is tested on gas solubility data at low and high pressure. The perturbed hard chain equation (PHCT) coupled with flash algorithm is used for the calculations. As a result the mixtures considered are described by the thermodynamic model chosen through the pseudo-components used, thus allowing the optimization of deasphalting and solvent recovery processes.