METHOD FOR SELECTIVE PURIFICATION OF LUBE FRACTIONS Russian patent published in 1999 - IPC

FIELD: petroleum processing. SUBSTANCE: purification is carried out by bringing lube fractions into counter-current contact with selective solvent added to fractions before their entering extraction apparatus. Method is distinguished by that oil stock containing 5 to 95% of solvent (N- methylpyrrolidone or furfurol) required for extraction and 1 to 3% water is subjected to heat treatment at temperature superior to critical solution temperature, after which single-phase solution is cooled to temperature below critical solution temperature but not below temperature of freezing of one of phases and resulting thermally treated mixture is fed into extraction apparatus. EFFECT: increased recovery of raffinate due to increased efficiency of separation of oil stock components and reduced amount of solvent required for extraction. 12 ex