GB1392159A - Dewaxing of oils - Google Patents

Abstract

1392159 Dewaxing oils TEXACO DEVELOPMENT CORP 3 Aug 1973 [1 Sept 1972] 37077/73 Heading C5E A process of separating wax from an oil 10 comprises the steps (a) mixing the oil with a dewaxing solvent 11 and a liquid refrigerant 12; (b) reducing the pressure to produce a volatilized high pressure refrigerant vapour (in lines 23, 23a, 23b and 23c), and to cool the mixture so that a slurry of wax in the oil-solvent mixture is formed; (c) further reducing the pressure to produce a volatilized low pressure refrigerant vapour (in lines 28, 28a, 28b and 28c), and to further cool the mixture and crystallize additional wax; (d) filtering the slurry at 38 to form a filter cake of slack wax containing occluded oil-solvent mixture and a filtrate 64 containing dewaxed oil and solvent; (e) cooling the volatilized high pressure refrigerant vapour at 46<SP>1</SP> by indirect heat exchange against the first filtrate 64; (f) condensing the cooled high pressure refrigerant from (e) and (g) at 50; recycling the condensed refrigerant from (f) to step (a). The filter cake from step (d) can be slurried in additional solvent and then filtered at 47 to separate de-oiled wax and a filtrate 52 which is used to further cool the high pressure refrigerant from step (e) by indirect heat exchange. The process is used to separate wax from mineral oils, such as a solvent refined vacuum distillate, and is stated to be useful for the separation of waxes from animal or vege-. table oils. Suitable dewaxing solvents are methyl ethyl ketone, methyl isopropyl ketone and methyl isobutyl ketone and can contain benzene or toluene. The refrigerant can be ethane, ethylene, propane, butene, dichloromethane, difluoromethane or ammonia. The figure illustrates a process in which a plurality of chillers 22, 22a, 22b and 22c are operated in sequence.