LUBRICATING OIL DEWAXING USING COLD SOLVENT RECYCLE PROCESS

摘要

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 filtered to remove 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 ail/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.