GB680728A - Method of and apparatus for the solvent extraction of oils and fats - Google Patents

Abstract

In the solvent extraction of oils and fats from solid materials, such as oil seeds, in solvent-filled containers through which the solvent successively passes, the total quantity of extract solution is withdrawn from the bottom of each container through sieves or similar devices and is conducted through an overflow determining the liquid level in each container before proceeding to the next container. In the form shown, the container 1 has a perforated pipe 2 arranged at its bottom and is connected with a pipe system comprising a rising pipe 4, descending pipe 5, and a horizontal perforated pipe 3, an air inlet being provided between pipes 4 and 5. An optional perforated pipe 6 may be used having openings allowing only a part of the solution to pass therethrough. A number of such containers may be used in an extraction apparatus, Fig. 4, of the paternoster type. The containers 8 move in the direction indicated, being charged with the solid material from a feeder 9 and discharging the same into a removal device 10. Fresh solvent is supplied to the top rising container and the solution collected at the bottom on the rising side of the extraction chamber 7 is supplied through pipe 14 by pump 19 to the top falling container; the separately collected solution at the bottom on the falling side of the extraction chamber is supplied through pipe 15 by pump 16 to a settling <PICT:0680728/III/1> <PICT:0680728/III/2> <PICT:0680728/III/3> <PICT:0680728/III/4> tank 12 having a filter 13 in its upper part. The filtered miscella is removed at 20 and the settled liquid containing fines from the solid material is drawn off through pipe 21 and recycled to the first container, the solid material therein acting as a filter therefor. In a modification of the extraction apparatus, the containers are carried by a wheel and moved in a circle within a cylindrical extraction chamber. The solvent may be removed from the filtered solutions obtained in a column still comprising a film evaporator unit c, Fig. 7, arranged between upper and lower sections a, d, containing baffle plates. The solution is supplied by pipe 41, steam by a pipe 51, the vapours are removed through 46 to a condenser 47, the oil freed of solvent is withdrawn through 43. The solution flows from the upper section a to a rotating distributer b from which it is evenly fed over the pipes of the evaporator c which is heated at constant temperature. An agitating device e is provided. In a plant incorporating the above column still, the latter is provided with a second film evaporator unit c. Vacuum-steam heating is used for the evaporators to keep the temperature below the column temperature. The plant includes a preheater for the solutions and steam-jet apparatus for venting the various condensers used. In a further plant incorporating the column still, the evaporator units thereof are heated by the water-washed vapours driven off the extracted solid residues from the extraction process. These residues are heated in a series of jacketed conveyers to remove the solvent as vapour therefrom. In another drying plant for removing the solvent from the extracted solid residues, the latter is fed at 110, Fig. 9, to the drier 111 which consists of a system of ascending and descending ducts. Solvent vapours from the same plant, passing through a heater 112, are used as the drying agent and convey the residues upwardly and then into a separator 115 from which the heavier, still solvent-bearing material is returned to the drier. The dried part of the material is further carried by the vapours to a cyclone separator 119 from which the dried material falls to a final drying apparatus 121. Part of the vapours sucked from the cyclone 119 are returned through pipe 126 to the heater 112 and the drying plant. The final drying apparatus 121 may be a usual column dryer divided into sections having heated bottoms, the material falling from section to section. The column is operated under vacuum and steam is supplied to each section.