IMPROVEMENTS RELATING TO THE SEPARATION OF WAX FROM OIL

1,267,491. Separating wax from oils. BRITISH PETROLEUM CO. Ltd. 22 Dec., 1970 [7 Jan., 1970], No. 795/70. Heading C5E. In the separation of wax from oil by centrifuging at 30‹ C., or below, a wax-oil mixture which would normally be solid at the centrifuging temperature is agitated to render it mobile, without reducing the wax crystals to below 50 microns, and the mobile mixture is then centrifuged. The oils dewaxed are atmospheric or vacuum gas oils or wax distillate fractions boiling in the range 250-550‹ C. and can contain a diluent such as a gas oil boiling in the range 250-400‹ C. The oil is cooled at 1-14‹ C. per hour to the centrifuging temperature before the agitation or it can also be cooled during and/or after the agitation. The agitation can involve both a beating or whisking action and a stirring action and can be carried out for 1- 120 minutes; N 2 , CO, CO 2 , H 2 or air can be entrained during the agitation in an amount which increases the volume of the mix by 5- 20% so as to increase the mobility of the mixture and improve the separation of wax from the oil. The wax is separated from the oil by a filtration centrifuge or a sedimentation centrifuge in a residence time between 5 seconds and 15 minutes at 150-3500 G. The dewaxing process can be carried out in one, two or more stages.