Mobil Oil Corporation

Albert R Nitsch

William F Heaney

Ronald M Gould

Howard E Spencer

A process for solvent dewaxing petroleum feedstock to separate crystallized wax from lubricant oil by filtration of a wax/oil/solvent mixture. The feedstock is sequentially cooled and mixed with cold polar solvent to form a wax crystal phase and oil-solvent phase, and-the oil-solvent filtrate stream is contacted with solvent permeable selective membrane at low temperature to recover an internal circulating permeate solvent stream and an oil-rich retentate stream containing dewaxed oil product and residual solvent. Improved operation is achieved by splitting the internal circulating solvent stream into a multiple cold solvent recycle streams and injecting a plurality of the cold solvent recycle streams into the waxy petroleum feedstock during sequential cooling and mixing. By initially injecting a cold recycle solvent stream in to the waxy petroleum feedstock at a small temperature differential near the wax crystallization temperature, shock cooling and excess small wax crystal formation is avoided.

Lubricating oil dewaxing with membrane separation of cold solvent

A process for solvent dewaxing a waxy oil feed to obtain petroleum oil lubricating stock comprising the steps of contacting a warm waxy oil feed by indirect heat exchange first with cold filtrate, then with refrigerant to crystallize and precipitate the wax in the oil feed to form an oil/solvent/wax mixture. The oil/solvent/wax mixture is diluted with cold solvent to adjust the viscosity of the mixture and the mixture is fed to a filter which filters and removes the wax from the cold oil/solvent/wax mixture. A cold wax cake is recovered and a cold oil/solvent filtrate stream is recovered. The cold oil/solvent filtrate stream is fed, at the filtration temperature, to a selective permeable membrane. The membrane selectively separates the cold filtrate into a cold solvent permeate stream and a cold filtrate stream which contains the dewaxed oil and the remaining solvent. The cold solvent permeate stream at the filtration temperature is recycled to the filter feed stream. The cold filtrate stream is then contacted with the warm waxy oil feed by indirect heat exchange. After heat exchange with the warm waxy oil feed, the filtrate is sent to an oil/solvent separation operation in which the remaining solvent is removed from the dewaxed oil and recycled to the dewaxing process and the wax free lubricating oil stock product is recovered.

Lubricating oil dewaxing using membrane separation of cold solvent from

A fractionation method and apparatus is disclosed for separating and recovering condensed and absorbed coke vapor from residual material leaving a coker combination tower to thereby obtain increased distillate yield. A resid flash down tower is positioned between the coker combination tower and a delayed coke furnace and operated to recover the higher value liquid product from the residual material containing absorbed coke vapor.

Heavy oil distillation system

A fractionation method and apparatus is disclosed for separating and recovering condensed and absorbed coke drum vapor from residual material leaving a coker combination tower to thereby obtain increased distillate yield. A resid flash down tower is positioned between the coker combination tower and a delayed coke furnace and operated to recover the higher value liquid product from the residual material containing absorbed coke drum vapor.

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Princeton, NJ, United States of America

Albert R Nitsch