GB374915A - Improvements in and connected with the separation of collcidal and other suspensionsfrom liquids - Google Patents

Abstract

<PICT:0374915/III/1> <PICT:0374915/III/2> Used lubricating and similar oils are freed from suspended impurities, such as colloidal carbon, by forming a fine dispersion of water in the oil under pressure and separating the coagulated impurities. Used oil passes through an inlet 4 and is forced by a pump 5 into a vessel 7 in which it is heated to about 230 DEG F. The hot oil passes through a pipe 10 to a centrifuge 1 in which it is agitated with a small amount of hot water or steam admitted through pipes 15 and 11 from a heated tank 12. The mixture of water and oil is discharged through an outlet 1<1> into a time-lag tank 2 containing baffles, in which coagulation proceeds, preferably with the aid of an electric field. The mixture then passes into a centrifuge 3, to which a trickle of water is supplied through a pipe 16. Purified oil is discharged through an outlet 17, and the separated water and impurities pass through an outlet 18 into the tank 12, containing baffles. The supernatant layer of impurities is drawn off from a trough 19. The centrifuges 1, 3 may be combined in a unit in which the dispersion is formed at the centre of a rotating drum from which it is discharged against a pile of conical discs mounted therein. In a preferred form of the centrifuge 3, a preliminary separating space is provided adjacent the central inlet, by mounting an annular ring baffle 44, Fig. 3, between the flat bottom of the bowl 41 and the lowermost cone 42, so that the outer edge of the baffle extends into the water line, and the inner edge is just outside the oil line. The mixture of oil and water descends through the inlet 40 to the separating space between baffle 44 and cone 42. The water flows around the tubes 45, mounted in the baffle, to the water space surrounding the cones, and the oil forced downwards to the space 43 from which it rises through the tubes 45 to the oil level. The cones of the centrifuge may be alternately insulated and connected to a source of direct pulsating or alternating current. Specification 282,466, [Class 23, Centrifugal machines &c.], is referred to.