Process for regenerating exhausted oils
AssigneeSnamprogetti S.p.A.
InventorsSergio Antonelli, Michele Borza
Life of this patent
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Abstract
For refining spent motor oils in order to recover lubricating bases to be reused, the stock to be refined is first stripped of water and light hydrocarbons, then a first extraction with a solvent (preferably a lower paraffin), heating the oil stripped of the solvent, distilling it under vacuum to separate light, medium and heavy lubricating bases, heating the heavier lubricating base and then extracting it with the same solvent as aforesaid, and sending the lubricating bases, separately and individually, to a hydrofinishing stage. The recycle to solvent extraction of the heavy bases affords the advantage of important heat savings and the possibility of adopting blander working conditions in the hydrofinishing of the heavier lubricating bases.
Claims9
A process for regenerating spent oils, characterized by comprising the steps of:
- (a) Heating the oil in a first oven,
- (b) Sending the heated oil to a pre-distillation column and separating at the column head the water and the light hydrocarbons,
- (c) Recovering from the bottom of the pre-distillation column the oil which is sent to a solvent-extraction section to remove from the oil the major fraction of the impurities contained therein,
- (d) Heating the oil raffinate exiting the extraction section after having stripped the solvent therefrom in a second oven,
- (e) Feeding the oil from the heating stage to a stage of distillation under vacuum with a bottom temperature higher than 300.degree. C., to separate from the column side the lubricating bases having the lower viscosity and deprived of impurities and discharging from the bottom the heavier lubricating bases in which the remaining impurities have been concentrated,
- (f) Subjecting the heavier lubricating fraction to a heat treatment at a temperature from 300.degree. C. to 450.degree. C. under adiabatic conditions for a time varying from 1 to 120 minutes,
- (g) Subjecting the heavier lubricating fraction, after the heat treatment, to a second extraction with solvent, and
- (h) Sending the heavy lubricating base raffinate and the other bases having a lower viscosity, separately, to a hydrofinishing stage.
Dependencies are inferred from the claim text.