Solvent deasphalting with two light hydrocarbon solvents

Claim 2

A process of separating a petroleum residue containing feed stock into asphalt and deasphalted oil in a contacting tower formed with an internal chamber, said contacting tower including a series of vertically disposed compartments in said internal chamber and a rotor with a series of blades disposed within each of said compartments, said process comprising the steps of: conveying said feed stock into one of said compartments; conveying a high-molecular-weight solvent in a liquid phase into one of said compartments which is located below the compartment receiving said feed stock, said high-molecular-weight solvent selected from the group consisting of alkane hydrocarbons and alkene hydrocarbons containing from four through seven carbon atoms inclusive and combinations thereof; conveying a low-molecular-weight solvent in a liquid phase into one of said compartments which is located above the compartment receiving said feed stock, said low-molecular-weight solvent selected from the group consisting of alkane hydrocarbons and alkene hydrocarbons containing from three through six carbon atoms inclusive and combinations thereof and having at least one less carbon atom than said high-molecular-weight solvent; and agitating said feed stock and solvent in said internal chamber whereby said high-molecular-weight solvent takes a relatively large portion of deasphalted oil into solution at the bottom of said internal chamber and said low-molecular solvent takes a relatively small portion of said deasphalted oil into solution at the top of said internal chamber.