GB707470A - Process of and apparatus for refining oils or fats - Google Patents

Abstract

<PICT:0707470/III/1> <PICT:0707470/III/2> Fatty oils and waxes of vegetable, animal or synthetic origin, for example rape seed oil, spermaceti and beeswax, are refined to remove their free fatty acid content by circulating them with a neutralizing agent in a number of consecutive stages, circulation in each stage being on the air-lift pump principle. The neutralizing agent may be a caustic alkali, an alkaline-earth hydroxide, an alkali metal carbonate, ammonia or an organic base such as triethanolamine. The neutralization may be effected under reduced pressure, and the water present may be evaporated to such an extent that a dry soap is obtained. The soap may be separated by centrifuging in one or more stages, such centrifuging being assisted by the addition of concentrated salt solutions, solutions of caustic alkali or alcohols. The salt solutions may contain sodium, potassium or ammonium chloride or sulphate or alkaline-earth metal salts. As shown, the refining vessel 6 is divided into six chambers by the partitions 16, each chamber containing a pipe 17 open at both ends and surrounded by an outer pipe 18. The chambers are divided into two sets by a partition 25, both sets being connected to vacuum lines 26, 28, and the vacuum in line 28 being greater than that in line 26. Each pipe 17 is fitted with a heat exchanger 41 and a pipe 19 for introducing the driving medium, e.g. steam. The oil is introduced into the riser pipe 17 of the first chamber through the line 5, and the neutralizing agent is introduced through the line 9. All the neutralizing agent may be added at this stage or some may be introduced at a later stage. The mixture of oil and neutralizing agent is lifted to the top of the riser 17 by the driving medium and overflows into the outer pipe 18. From there it passes through the opening 21 in partition 16 to the next chamber, where it is treated similarly in the riser pipe and passed to the next chamber. It is circulated in a similar manner in succession through each chamber, and finally emerges through line 22. The mixture of neutral oil and soap is kept in motion in vessel 23 by treatment with steam, and passed to the mixer 34. Salt solutions or alcohol may be added to the mixer 34 from vessel 35 and the resulting sludge is centrifuged in 38 to give neutral oil and soap stock.