Method of refining oil with a selective solvent

Claim 1

IN THE SOLVENT SEPARATION OF FEED OIL CONTAINING AT LEAST A SMALL PROPORTION OF CONSTITUENTS HAVING TRUE BOILING POINTS IN THE RANGE OF THE SOLVENT BOILING TEMPERATURE AND BELOW WHEREIN THE FEED OIL IS SUBJECTED TO CONTACT IN AN EXTRACTION ZONE WITH AN ORGANIC SOLVENT LIQUID PARTIALLY MISCIBLE WITH WATER, EXTRACT AND RAFFINATE PHASES ARE FORMED, AND SEPARATELY REMOVED FROM THE EXTRACTION ZONE, THE STEPS COMPRISING DISTILLING FROM AT LEAST ONE OF SAID PHASES IN A PRIMARY FRACTIONATING ZONE A DISTILLATE OF SOLVENT VAPOR CONTAINING SMALL AMOUNTS OF OIL AND LEAVING A LIQUID RESIDUE OF OIL SUBSTANTIALLY FREE FROM SOLVENT, DISCHARGING SAID SOLVENT-FREE OIL, CONDENSING SAID DISTILLATE, SUBJECTING RESULTING CONDENSATE TO SETTLING IN THE PRESENCE OF WATER IN A PRIMARY SETTLING ZONE, FORMING IN SAID PRIMARY SETTLING ZONE OIL-RICH, WATER-RICH AND SOLVENT-RICH LIQUID LAYERS RESPECTIVELY, SEPARATELY WITHDRAWING LIQUID FROM EACH OF SAID PRIMARY LAYERS, RECYCLING A PORTION OF WITHDRAWN PRIMARY WATER-RICH LIQUID TO SAID PRIMARY FRACTIONATING ZONE, PASSING ANOTHER PORTION OF WITHDRAWN PRIMARY WATER-RICH LIQUID TO A SECONDARY FRACTIONATING ZONE, PASSING WITHDRAWN PRIMARY SOLVENT-RICH LIQUID TO A TERTIARY FRACTIONATING ZONE, DISTILLING FROM SAID SECONDARY AND TERTIARY FRACTIONATING ZONES DISTILLATES CONTAINING SOLVENT, WATER AND OIL, DISCHARGING WATER AS A RESIDUAL FRACTION FROM SAID SECONDARY FRACTIONATING ZONE, WITHDRAWING SUBSTANTIALLY DRY SOLVENT AS A RESIDUAL LIQUID FRACTION FROM SAID TERTIARY FRACTIONATING ZONE, RECYCLING WITHDRAWN DRY SOLVENT TO SAID EXTRACTION ZONE, CONDENSING SAID SECONDARY AND TERTIARY DISTILLATES, SUBJECTING RESULTING SECONDARY AND TERTIARY CONDENSATES IN THE PRESENCE OF EACH OTHER TO SETTLING IN A SECONDARY SETTLING ZONE, FORMING IN SAID SECONDARY SETTLING ZONE SECONDARY OIL-RICH, WATER-RICH AND SOLVENT-RICH LIQUID LAYERS RESPECTIVELY, SEPARATELY WITHDRAWING SAID SECONDARY LAYERS, RECOVERING OIL FROM WITHDRAWN SECONDARY OIL-RICH LIQUID, PASSING WITHDRAWN SECONDARY SOLVENT-RICH LIQUID TO SAID TERTIARY FRACTIONATING ZONE, AND PASSING WITHDRAWN SECONDARY WATER-RICH LIQUID TO BOTH SAID SECONDARY AND TERTIARY FRACTIONATING ZONES.