GB704232A - Improvements in or relating to method and apparatus for deodorizing oils and fats - Google Patents

Abstract

<PICT:0704232/III/1> Fatty oils and fats are deodorized in sequential batch treatment by passing the batch of oil to a preliminary heating zone where it is heated to a point below effective deodorization temperature and also deaerated, then to a series of zones where heating at the effective deodorization temperature is effected and in one of which a stripping medium is passed therethrough to effect deodorization, and finally to a cooling zone, the batch remaining in each zone for the same time interval. Each zone of treatment may be subjected to vacuum. Preferably, five zones are used to effect (1) deaeration at a temperature below effective deodorization temperature, (2) heating to deodorization temperature, (3) deodorization, (4) deodorization, and (5) cooling. Suitable apparatus employing the five zones comprises a cylindrical column 33 with the five zones 1 . . . . 5 defined by superposed square trays 36 having side walls 37, each provided with steam stripping inlets 12 . . . . 16, and zone 1 having steam heated coils 17, zones 2 and 4 having diphenyl and diphenyl oxide vapour heated coils 20 and 21, and zone 5 having a cooling coil 28. The batch of oil is supplied to the top of the column through an inlet 43 and flows from tray to tray through delivery pipes 47, 49, 51, 53 to a final discharge pipe 55 each provided with valves 46, 48, 50, 52, and 54. Reduced pressure is maintained within the column by a steam jet ejector system connected at F1. A system of baffles is provided at the top of each tray comprising a number of open square plates 18, 19 nested one within another and interconnected in spaced relationship by angle pieces, to provide a tortuous path for the escape of vapours therefrom and to splatter the oil which is thrown upwardly against them by the stripping steam, the normal oil level being indicated at L. In an example, cottonseed oil is treated for half hourly periods with stripping steam in each zone, at 320 DEG F., in zone 1 to preheat and remove air which flows out through F1, at 460 DEG F, in zones 2 and 4 with interposed stripping alone in zone 3 the odorous vapours also flowing out through F1, and finally at 130 DEG F. in zone 5 to cool it below oxidation temperature stripping steam still being supplied. Soya bean oil and lard are also exemplified. The trays and associated parts coming in contact with the oil may be made of nickel or aluminium, and the shell of the column may be made of ordinary carbon steel. The process also removes free fatty acids from the oil being treated. Specifications 505,810, 510,852 and 704,298 are referred to.