Mobil Oil Corporation

Howard E Spencer

Ronald M Gould

William F Heaney

Albert R Nitsch

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.

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Titusville, NJ, United States of America

Howard E Spencer