GB479624A - Improvements in or relating to methods of recovering solvent in dewaxing operations - Google Patents

Abstract

<PICT:0479624/III/1> After dewaxing mineral oil by chilling in presence of a diluent containing acetone or other water-soluble solvent the slack wax is freed from such solvent by heating to a controlled temperature, below an active distillation temperature for the solvent, at which the wax is dissolved in the retained solvent, by standing at such temperature to settle out water, separating the wax-oil upper layer, and distilling off or otherwise removing the solvent therefrom. Suitably, oil diluted with benzol and acetone and chilled to -10 to -20 DEG F., passes by a pipe 10 and a mixer 69 to a filter 11 connected to a surge tank 12 kept under pressure by flue gas from a pipe 13, the oil flows to storage through a pipe 14, the wax by a pipe 15 to a receiver 16. The wax is pumped through a pipe 19, a heat-exchanger 20, and a steam heater 23, and then at 88 DEG F. through a pipe 24 to a settler 25 maintained at 88 DEG F. The upper layer, wax-oil-solvent, overflows by pipe 30 to heat-exchanger 32, pipe 33, steam heater 34, and drum 36 in which most of the solvent flashes off and passes by pipe 43, heat-exchanger 32, condenser 44, and pipe 45 to a solvent receiver 46; the slack wax is pumped from the drum 36, partly to storage through a pipe 42 and a steam stripping device to remove residual solvent, partly through a pipe 38, a heating coil 39, and a pipe 40 to the upper part of the drum 36. The lower layer--water and some acetone--in the settler 25 flows to a receiver 27, whence it is pumped through pipe 51 and steam heater 52 to a steam stripping column 54; the acetone vapour passes to a condenser 58 and a drum 59, from which part flows through pipe 60 to the solvent receiver 46, and part returns by a pipe 57 to serve as reflux in the column 54. The combined solvent in the receiver 46 is pumped through pipe 21, heat-exchanger 20, chiller 65, and pipe 66 to a receiver 67 in which ice settles out; it then passes by pipe 68 to the chilled oil-solvent in pipe 10.