The pretreatment involves removing of impurities. Depending on the properties of
the feedstock, either water degumming is applied, or regular bleaching where a
small amount of phosphoric acid is added and intensively mixed with oil to
precipitate the gums and impurities which will then be removed along with
Oil and hydrogen react at low pressures, in order to remove the unsaturation.
The hydrogenated oil will yield more stable products in the further processing
and avoid the fatty acids hydrogenation step.
The desmet ballestra oleo splitting is characterised by the very high splitting
degree and the very low carry over of fatty matter in the sweet water and free
glycerol in the crude fatty acids.
This latter feature avoids the splitting degree reversion in the storage.
The unique design of our splitter is that the upper heat and mass transfer
section is foul proof avoiding then the need for the frequent stop over for
The crude fatty acids are normally dehydrated, while the sweet water are
preconcentrated and passed through an in-line settling vessel to separate to the
maximum extent the fatty matter.
Many of our plants operate without chemical treatment of the sweet water, matter
of fact De Smet and Ballestra were the first to operate in this way since 1989;
nevertheless we can supply a fully continuous treatment whereas required.
Chemical treatment of spent lyes, on the contrary of sweet water, is unavoidable
and is carried out in a continuous, fully automatically controlled unit.
The unit is tailored to the capacity, the available utilities and the specific
customer preferences in up to four effects. Both natural and forced circulation
units are supplied.
Maximum heat recovery is achieved by feed effluent heat exchangers and thermo
For spent lyes concentration, the unit differs from the one for sweet water for
the salt separation recovery and drying section. Also the materials of
construction are different from the ones for sweet water. Due to the presence of
salt only the forced circulation alternative is viable.
This unit can also handle, when required, bio-diesel diluted glycerine.
The distillation is based on a packed tower where the glycerine is distilled,
fractionated to separate both heavy and light boiling impurities and condensed.
Yellowish glycerine is condensed in a separate scrubber. Deodorisation can be
supplied according to the material being processed.
Refining is continuous on three in line bleachers.
In case of spent lyes or bio-diesel glycerine a salt squeezing section is added.
Fatty acids distillation
The distillers are towers with structured packing to fractionate heavy and light
boiling impurities and to ensure that the fatty acids are distilled at the
lowest possible temperature.
Squeezing of the residue is carried out in a separate distiller.
Condensation can be carried out inside the tower over packing with cooling of an
external pump around or outside the tower in shell and tubes condensers.
In both cases heat is recovered generating low pressure steam.
Canned pumps with falling film reboilers or centrifugal pumps with suppressed
vaporisation reboilers are proposed according to the case.
Fatty acids fractional distillation
The single or multi towers plants are based on towers with structured packing.
Typical design of the towers foresees three products outlets (top, sidedraw and
Of course all features of the distillation apply to the fractionation.
Fatty acids dry fractionation
Controlled cooling/crystallising followed by pressure membrane filtration is
used for the production of oleic acid.
Dry fractionation process leading to clean and simple operation guaranteeing a
lower operating and investment cost.
Fatty acids hydrogenation
The unit is designed to hydrogenate in a semi-continuous way either the neutral
oil or the fatty acids.
The hydrogenation is carried out in a reactor with a jet mixer.
Heat of reaction is utilised to generate low pressure steam in an external
exchanger; to further improve the overall heat balance feed /effluent heat
exchangers are foreseen.