GB526627A - An improved process for the solvent treatment of mineral oil - Google Patents

Abstract

526,627. Fractioning oils by solvents. STANDARD OIL DEVELOPMENT CO. March 23, 1939, No. 9165. Convention date, June 15, 1938. [Class 91] In the counter-current extraction of a mineral oil with a selective solvent, a major portion of the solvent is recovered without distillation and a minor portion by distillation, and the oil is contacted first with the undistilled solvent and then with the distilled solvent, the latter being fed into the extractor at a point between the inlet for the undistilled solvent and the outlet for the raffinate. Preferably the extract is dissolved out of its solution by a second solvent immiscible with the first, so as to produce one phase mainly the first solvent, and an extract phase from which the second solvent and residual first solvent are distilled and allowed to separate. Some of the second solvent may be introduced into the first extractor as a solution in the oil and in the first solvent. A substance such as water which reduces the solvent power of the first solvent may be passed into the first extractor at a point or points below or above the oil inlet; it separates with the first solvent phase after extraction with the second solvent, and is distilled therefrom ; the recovered first solvent and the water are then returned to the first extractor. Using the apparatus shown, lubricating oil is passed by a pipe 30 into a tower 29 to absorb traces of phenol (the first solvent) and liquid hydrocarbon (the second solvent) from a current of steam entering by a pipe 27 ; the oil flows through a pipe 2 to tower 1 and passes upwards against recovered undistilled phenol introduced by a pipe 3 and recovered distilled phenol introduced by a pipe 4. The extract dissolved in phenol is passed by a pipe 6 to an extractor 7 down which it flows against liquid hydrocarbon solvent introduced by a pipe 8 ; the extract, now dissolved mainly in hydrocarbon, is taken by a pipe 9 to a stripper 19, together with a portion of the phenol solution of extract withdrawn from pipe 6 and byepassed round tower 7 through a pipe 39 so as to increase the proportion of distilled phenol relative to undistilled ; the phenol and hydrocarbon vaporized are returned by a pipe 20 ; the extract is removed by a pipe 21. The wet phenol separated in the extractor 7 is taken by a pipe 10 to a tower 11, in which the water is vaporized, and then passed by a pipe 12 to a boiler 13 in which it is dried to the desired extent ; it is then returned to the tower 1 by the pipe 3. The raffinate from tower 1 is taken by a pipe 5 to a stripper 14, in which the phenol and liquid hydrocarbon are vaporized and then withdrawn through a pipe 16. The vapours from the strippers 19, 14 are taken by pipes 20, 15 and a pipe 23 to the separating tower 11, in which the temperature is regulated to determine the water content of the phenol ; the separated hydrocarbon and aqueous phenol are run through a pipe 25 and a cooler 37 into a tank 28 ; this distilled phenol-and any phenol added to replace loss-is passed by pipe 4 to the tower 1; the hydrocarbon is taken by pipe 8 to the tower 7, and by pipes 22, 38 to the strippers 18, 14 to serve as reflex. The vapours from the tower 11 flow through a pipe 31 to a drum 26; aqueous phenol condensed is passed by a pipe 17 to the tower 1 and/or by a pipe 18 to the phenol solution of extract before it enters the tower 7, uncondensed vapours pass on through pipe 27 into the tower 29. U.S.A. Specification 1,878,022 is referred to.