Dewaxing process
AssigneeMobil Oil Corporation
InventorsPatrick E. Fowles, Gerald L. Shoemaker, Tsoung-Yuan Yan
Life of this patent
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Abstract
A dewaxing process for reducing the pour point of waxy oils in which the oil is cooled by direct contact with a liquid autorefrigerant such as propane. The wax which separates upon cooling is removed by flotation assisted by the bubbles of vaporized autorefrigerant which rise through the oil to form a frothy slurry of wax which can be decanted and the wax recovered from it. A dewaxing solvent such as methyl ethyl ketone may be used to assist separation of the wax.
Claims20
A dewaxing process for producing dewaxed oil from waxy oil which comprises:
- contacting in a flotation column the waxy oil with a liquid autorefrigerant to cool the oil by vaporization of the autorefrigerant thereby causing crystallization of wax from the oil, and separating the wax from the oil by flotation to produce wax crystals and dewaxed oil wherein most of the wax separated from the oil by flotation is crystallized by vaporation of said liquid autorefrigerant and removed from an upper portion of said column wherein said dewaxed oil is removed from said column as a separate stream, substantially free of wax crystals, from a withdrawal point below the point of removal of said wax crystals.
A solvent dewaxing process for reducing the pour point of a waxy oil feedstock, comprising the steps of:
- (i) forming a mixture of the waxy oil feedstock with a dewaxing solvent,
- (ii) pre-cooling the mixture of oil and dewaxing solvent,
- (iii) contacting in a flotation column the pre-cooled mixture of oil and dewaxing solvent with a volatile liquid autorefrigerant to cause the liquid autorefrigerant to vaporize and further cool the pre-cooled mixture thereby causing wax in the oil to crystallize and separate, wherein most crystallization is caused by vaporization of said liquid autorefrigerant,
- (iv) removing the separated wax from an upper portion of said column by flotation from the cooled mixture, and
- (v) recovering dewaxed oil of lower pour point from the cooled mixture from a withdrawal point below the point of removal of said wax crystals.
Dependencies are inferred from the claim text.