Texaco Inc.

Herbert J Pitman

Charles W Harrison

Avilino Sequeira, Jr

John D Begnaud

Glenn A Senters

Jerry E Quasny

A process for dewaxing a petroleum oil stock with a liquid solvent employing direct heat exchange cooling of solvent-oil mixture with an immiscible liquid chilling medium.

Solvent dewaxing process

An improved method for solvent dewaxing oils in which a portion of the oil-solvent mixture is chilled to a temperature above its cloud point and a further portion is chilled to a temperature below its cloud point, the portions are combined to produce a mixture substantially at the cloud point, and the combined mixture further cooled to dewaxing temperature at which wax crystals are separated from the solvent and refined oil.

A process wherein a light waxy petroleum distillate stock, having a viscosity less than about 200 SUS at 100.degree. F, is heated for melting any wax therein, wherein said heated waxy stock is incrementally mixed with a flowing stream of dewaxing solvent, having a temperature in the range of 40.degree.-80.degree. F, for forming an oil/solvent mixture at a temperature 5.degree.-10.degree. F below the depressed cloud point, and wherein the oil/solvent mixture is cooled at a uniform rate in the range of 1.degree.-8.degree. F/min. to a separation temperature in the range of +25.degree. to -40.degree. F for precipitating wax from said mixture.

A process for dewaxing heavy distillate and residual petroleum oil stocks wherein a waxy oil stock, prediluted with 1-2.5 volumes dewaxing solvent, is cooled to about the depressed cloud point, wherein the cooled, prediluted waxy oil stock is treated with dewaxing solvent, in increments of 0.3-1.5 volumes each to a total dilution of 3.5 to 4 volumes solvent, under conditions of good mixing and cooling at about 1.degree.-8.degree. F/min, to a desired separation temperature for precipitating wax crystals and producing a dewaxed oil.

A process for dewaxing a waxy petroleum distillate charge stock, wherein a mixture of waxy oil and solvent, heated for dissolving all solid wax therein, is cooled to a first temperature about 40.degree.-50.degree. F (22.degree. to 28.degree. C) above a selected separation temperature, and is held at such first temperature for a period of 1-2 minutes for equilibrating wax crystallization, wherein said oil-solvent mixture, at said first temperature, is cooled to a second temperature about 15.degree.14 20.degree. F (8.degree.-11.degree. C) above said separation temperature and is held at said second temperature for 1-2 minutes for equilibration of wax crystallization, wherein said oil-solvent mixture, at said second temperature, is cooled to said separation temperature, and wherein solid wax is separated from oil-solvent mixture at said separation temperature.

A method of dewaxing oil which employs the application of reversing electromotive force to the oil while it is being chilled, in order to prevent adherence of the wax crystals. An apparatus combination for dewaxing oil. It includes an elongated container for chilling a body of waxy oil as it flows through. The container acts as one of a pair of electrodes for applying a reversable electromotive force to the oil in order to prevent any adherence. The wax may be recovered by separation following the application of the electrical force.

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Nederland, TX, United States of America

Herbert J Pitman