Also known as: Solvent deasphalting, Demex, ROSE, Residual oil supercritical extraction
The SDA unit removes asphaltenes from vacuum resid, producing an asphalt product and a de-asphalted oil that can be used for base oil manufacturing or FCC feed.
Extraction is done using a light hydrocarbon, such as propane or butane, and it is done in stages to remove asphaltenes and resins separately. By varying temperature, extraction can be done selectively, separating asphaltenes and resins from the resid and from each other by taking advantage of their different supercritical temperatures (temperature at which they precipitate out of solution).
There are two common processes licensed by UOP (DEMEX) and Kerr McGee (ROSE).