GB454690A - Improvements in or relating to processes for refining hydrocarbon oils - Google Patents

Abstract

In the extraction of mineral oils with a selective solvent for constituents of low viscosity-index (naphthenic components), to form a solvent-extract phase and a raffinate phase, the raffinate is freed from the solvent-extract phase retained therein by washing with a different solvent which completely dissolves this phase but has no solvent action on the raffinate, consisting of high viscosity-index (paraffinic) constituents. The distillation of the raffinate to remove solvent is thereby avoided. Lubricating - oil fractions which may contain wax are treated. Selective solvents specified are, furfural, nitrobenzene, aniline, benzaldehyde, benzophenone or dichlorethyl ether. The washing solvent may be low-boiling aliphatic alcohols or ketones such as ethyl alcohol, acetone or methyl ethyl ketone. A wax distillate is fed into a mixer 2 to which furfural containing some oil is admitted from a later stage. Extraction temperatures of 150 to 250 DEG F., are used The mixture passes to a separating vessel 4 from which the extract is drawn off into a still 34 to recover the furfural. The raffinate is led into a second mixer 6 together with a further amount of furfural and the mixture passes to a second separating vessel 9. The extract is removed and used in the first extraction stage. The raffinate passes to the bottom of a tower 11 and is washed in countercurrent with acetone which is admitted at the top. The acetone extract passes to a still to recover the acetone and the oil residue containing furfural passes to the mixer 2. The washed raffinate containing some acetone passes to a mixer 15 where a further amount of acetone and some benzol are added from the tank 16. The mixture is led to a chiller 18 where the temperature is lowered to 0 DEG F., or below. The resulting mixture containing precipitated wax is forced through a filter 20 and the de-waxed oil is led into a tank 21. The oil is freed from de-waxing solvents in a stripper 23 and the finished oil passes to a tank 26. A final treatment with filter clay may be used.