Simulation of the deasphalting process of crude oils: Models development and extraction conditions analysis

Abstract

Heavy crude oils are under constant investigation due to light oil exhaustion. So, its use is compulsory to meet the world energy demand. Heavy crude oils present several drawbacks as high content of metals, heteroatoms, and asphaltenes, and, therefore, upgrading processes are becoming essential. A deasphalting process, conventionally used for vacuum residue upgrading, can be an interesting pretreatment to eliminate the heavier phases and ease the crude processing in conventional refining facilities.

Most of the models developed for deasphalting simulation show problems to be implemented in simulation software packages. In this work, a versatile deasphalting simulation method is developed, composed by the definition of a synthetic crude oil model, formed by discrete pseudo components, and a deasphalting model approaching the process to a liquid-liquid extraction based on the thermodynamic model modified UNIFAC (Dortmund). Both models were satisfactorily validated. The deasphalting method was used to explore the solvent/crude ratio, extraction temperatures, and alternative solvents in substitution of conventional light paraffins. Higher extraction temperatures did not enhance remarkably the deasphalting process and the optimum solvent to crude ratio depends on the solvent type. Alcohols were found as promising compounds as their use is recommended by some studies and they showed great deasphalting results.