LIQUID EXTRACTION PROCESS Russian patent published in 1998 - IPC

FIELD: chemical engineering. SUBSTANCE: invention, in particular, is intended for use in petroleum processing (e.g. on plants for selective purification of lube fractions with various solvents), in petrochemistry, chemical, and other industries. Liquid extraction is performed involving countercurrent surface contact of raw material with selective solvent in first multistep extractor to produce first end extract solution and intermediate raffinate solution. The latter is introduced as starting material into second multistep extractor to be there in countercurrent contact with selective solvent. From the second extractor, end raffinate solution and second end extract solution are withdrawn aftr which solvent from the two end extract and end raffinate solutions is regenerated to yield two extracts and raffinate. According to invention, in the first multistep extractor, raw material is brought in contact with extract solution picked out from the zone where intermediate raffinate solution is introduced into the second extractor. EFFECT: increased raw material separation degree, reduced solvent uptake, and increased yield of desired product. 6 dwg , 6 tbl