US 4,399,025 AGranted

Solvent extraction process for rerefining used lubricating oil

AssigneeDelta Central Refining, Inc.

InventorsLaird C. Fletcher, Richard H. O'Blasny

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Abstract

In accordance with the present invention, a process is provided for removing impurities from heavy and light lube oil fractions that have been obtained from waste lubricating oil. The impurities in the light lube oil fraction are removed utilizing tetrahydrofurfuryl alcohol in an extraction column (10). An oil-rich raffinate has the solvent removed therefrom by steam distillation and stripping at reduced pressure in a distillation tower (20). The heavy lube oil fraction is purified in a manner similar to the purification of the light lube oil fraction. Alternatively, most of the tetrahydrofurfuryl alcohol can be removed from the oil-rich raffinate by mixing the raffinate with methanol in an extraction column. The last of the tetrahydrofurfuyl alcohol is then removed from the oil by steam distillation and stripping at a reduced pressure. The finished heavy and light lube oil may then be subjected to further treatment, such as polishing steps, or additives may be blended into the lube oil product depending on the desired use.

Claims13

Dependent claims

In a process for rerefining used oil containing lubricating oil, where the used oil is rerefined into a heavy lube oil fraction and a light lube oil fraction, the improvement comprising:

(a) mixing the heavy lube oil fraction with an effective amount of tetrahydrofurfuryl alcohol for removing impurities from the heavy lube oil fraction;
(b) separating the heavy lube oil fraction and tetrahydrofurfuryl alcohol mixture into a heavy oil raffinate and a heavy oil tetrahydrofurfuryl alcohol extract;
(c) removing the tetrahydrofurfuryl alcohol from the heavy oil raffinate by mixing the heavy oil raffinate with an effective amount of an antisolvent;
(d) mixing the light lube oil fraction with an effective amount of tetrahydrofurfuryl alcohol for removing impurities from the light lube oil fraction;
(e) separating the light lube oil fraction and tetrahydrofurfuryl alcohol mixture into a light oil raffinate and a light oil tetrahydrofurfuryl alcohol extract;
and
(f) removing the tetrahydrofurfuryl alcohol from the light oil raffinate by mixing the light oil raffinate with an effective amount of an antisolvent.

4 more elements

Dependencies are inferred from the claim text.