GB599595A - Improved method of refining glyceride oils - Google Patents

Abstract

<PICT:0599595/III/1> Crude glyceride oils are refined by mist-mixing the oil with a water-adsorptive agent selected from the group consisting of salts containing water-adsorptive anions, (e.g., sodium silicate), colloidal silica (e.g., silica jelly) and mixtures thereof and with an aqueous caustic alkali solution, e.g., 20 to 30 per cent. which neutralizes the free fatty acids in the oil to form soapstock, and separating the soapstock from the oil, the amount of caustic alkali used being in sufficient excess of that required to neutralize the free fatty acids to ensure that some of it is present at the time of separation, and the agent being used in such an amount as substantially to reduce the proportion of neutral oil retained by the soapstock and to retard the saponification of the neutral oil. The crude oil is heated in tank 1 by coils 2 and/or in heat exchanger 11 to, for example, 44 DEG to 71 DEG C. The water-adsorptive agent is distributed throughout the caustic soda solution in tank 16 by means of the agitator 18 and the mixture may be heated to the desired reaction temperature by means of coil 17. The oil and refining solution are delivered to a centrifugal atomizing and mixing head 131 in exactly the desired proportions by means of variable delivery pumps 7 and 22 controlled by means of hand wheels 8 and 23, the rate of oil and reagent flow being observed by means of flow meters 12 and 25. The oil and reagent delivered to the head 131 are instantaneously mist-mixed and projected radially as a homogeneous mist-mixture, and flow as a film down the collecting walls of the closed reaction chamber 14, initially as an emulsion which is then broken by imparting to it a temperature of, for example, 60 DEG C to 83 DEG C, chamber 14 being jacketted for this purpose. The mixing head 131 is driven by a belt 15. The broken emulsion is discharged into receiver 30 and may either be delivered direct to the refining centrifuge 35 by means of pump 31 or preferably to 35 via a combined agitating and heating device 36. The occurrence of free soapstock in the centrifuge discharge is thereby eliminated or greatly reduced, so that the oil from 35 may be delivered direct to the clarifying centrifuge 49. Cloud may be removed from the oil in the clarifying centrifuge 49 by bye-passing the agitator 36 and pumping the oil from the refining centrifuge 35 through the combined cooler and agitator 44 where it is cooled to a temperature preferably below 33 DEG C. The soapstock previously dissolved in the hot oil is thereby thrown out of solution and coagulated, being thus readily separable from the oil. Alternatively the oil from the centrifuge 35 may be delivered into tank 51 and cooled therein either spontaneously or by means of the coil 52. After precipitation of the dissolved soapstock particles by this cooling they are coagulated by operation of the agitator 53 and the oil then delivered to the clarifying centrifuge 49. Specification 571,973 is referred to.