Patent GB-644917-A (GB)
Title: Improvements in or relating to the solvent extraction of glycerides and of fatty acids derived therefrom
IPC: B01D11/04
Filed: 1947-07-21
Abstract: The solvent extraction of glycerides, or of fatty acids derived therefrom, with a selective polar solvent is carried out under an inert gas, for example carbon monoxide, carbon dioxide, nitrogen or a nitrogen-containing gas such as flue gas.  In the presence of the inert gas objectionable reactions, which impair the value of one or more of the components of the material treated and which are due to the action of atmospheric oxygen, do not take place. Among the <PICT:0644917/III/1> glycerides that may be fractionated are linseed oil, marine oils such as menhaden, sardine or whale oils, soya bean oil, perilla oil, cottonseed oil, corn oil, sunflower oil, peanut oil, olive oil, lard, tallow, palm oil and coconut oil.  The oils may be raw oils, or refined oils, such as alkali-refined oils, and they may also be bodied or unbodied.  Selective polar solvents which may be employed are furfural, furfuryl alcohol, allyl alcohol, nitroethane, nitromethane, methyl formate, methyl levulinate, propionitrile, ethyl maleate, acetaldehyde, diacetyl, glycol diacetate, ethyl oxalate, ethylene glycol monomethyl ether acetate and others mentioned in Specifications 515,468 and 18137/47 (as open to inspection under Sect. 91).  Fractionation may be effected by reason of the higher degree of solubility of the more unsaturated components of the glyceride or fatty acid mixture in the selective solvent.  Thus drying oils may be extracted from linseed, soyabean, marine and perilla oils.  Alternatively, fractionation may be effected by reason of the greater solubility of the glycerides of the shorter chain fatty acids in the selective solvent, particularly in the case of palm and coconut oils.  The oils or fatty acids may be deaerated prior to extraction by heating them and simultaneously subjecting them to vacuum or to blowing with nitrogen or other inert gas.  If the selective solvent employed is one tending to hydrolyse, the inert gas employed as blanketing agent during the extraction may be preliminarily dried.  Extraction may be carried out as a simple batch operation by mixing the oil and solvent under a blanket of inert gas in a suitable container, then allowing the resultant fractions to separate into liquid layers and drawing off the layers into separate containers for removal of the solvent. Alternatively, countercurrent extraction may be conducted in columns in which all free surfaces of the glycerides or acids are protected by a blanket of inert gas.  In the Figure, glyceride oil or fatty acid from container 21 is introduced via conduit 23 into column 10.  Solvent from container 25 enters column 10 via conduit 28.  If desired, water or other fluid at least partially miscible with the solvent but immiscible with the material to be refined is introduced into the solvent through line 32a.  Raffinate leaves the column via conduit 37 and proceeds to apparatus for the removal of solvent.  Extract is drawn off through conduit 41 which extends upwardly a sufficient height to admit of hydrostatically balancing of the liquid therein against the liquid contained in column 10.  From the head 43 of conduit 41, the extract proceeds to apparatus for the removal of solvent.  Solvent from both extract and raffinate phases may be recycled for extraction of additional mixture.  A portion of the extract with a small amount of solvent therein may be returned via conduits 62 and 64 to column 10.  Inlets for inert gas are at 32b, 37a, 43a and 59.