Alkali-refining batch

Both alkali and physical refining have been used for FFA removal (5). With alkali refining, batch or continuous methods may be used. Oil may be pretreated with phosphoric or organic acid for phospholipid hydration. The oil is then treated with 16-30 baume (Be ) caustic with 20-40% excess. The soaps settle and may be recovered as soapstock or foots (47). 

Alkali refining is also carried out in a semi-continuous manner, the Zenith Process (Young, 1981). In this process small batches of oil are measured and treated with phosphoric acid in a pretreatment unit. From this unit the oil is pumped continuously via a centrifuge which removes dirt and denatured phosphatides to one of two neutralizer vessels which are used alternately. The oil enters the... 

A typical batch refining installation is described by Norris (1964). Briefly, it consists of an open tank, or kettle, holding about 30 tons of oil (one tank car). The kettle is equipped with a two-speed paddle agitator, steam coils, and a cone bottom. Sparging pipes are arranged in a grid in the head space of the tank for the addition of the alkali solution and wash-water. Agitator speeds are usually 40 and 8 rpm. 

The MA is recovered as a solid 4- liquid in switch condensers. After the condensers are switched, MA is melted for refining by batch distillation. Recovery is 90%, the remaining 10% MA being removed in a two-stage scrubber with water and dilute alkali. 

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