THE OLEOCHEMICAL PROCESS

Fat splitting

Two continuous processes are normally proposed by CMB for Oils & Fats splitting. Both processes are based on high temperature/pressure hydrolytic splitting.

Multi tower splitting

This process is used for capacities up to 40-50 tons per days. The splitting towers operate at a pressure of approx.
30 bar and adopt the principle of the countercurrent flow of water and fat in a number of autoclaves in series.

This system allows highly concentrated sweet waters to be obtained and offers the following advantages:

High splitting degree
Low water, steam and power requirements
Easy operation
Flexibility of operation

Flash steam is reutilized to pre-concentrate the sweet water in a single or double effect. By this system the sweet water concentration is about 40% and then a small final effect is enough to concentrate the glycerine up to 88%. Furthermore, the flashed steam condensate is re-used as process water, thus reducing the water make up and consequently the treated water consumption. CMB plant can be designed to utilize as heating medium diathermic oil or high pressure steam according to client’s requirements; splitting degree obtainable is in the range of 96/98% according to the raw material. Sweet water concentration upstream of the preconcentration unit is in the range of 14-16%.

Single tower high pressure (60 bar) splitting

The single tower operates at a pressure of 60 bar and is composed of three main sections:

A central section where splitting occurs
A top selection of heat exchange where the outgoing fatty acids preheat the incoming water
A bottom section acting as a hold-up for sweet water and as a heat exchange section where the outgoing sweet water preheats the incoming fat.

Heating is by direct steam injection under automatic temperature control. Splitting degree is normally above 99% and the sweet water concentration is in the range of 20-25% after the preconcentration.

Fatty acids distillation and fractionation

The CMB fatty acid distillation plant contemplates a very compact design which incorporates condensation and scrubbing in the distillation column itself. High quality fatty acids are obtained thanks to the washing stage, which allows to produce high quality products even with lower grade raw materials. Operating temperatures are kept to a minimum due to the very low pressure drop of the tower. High flexibility is achieved by means of external pumparounds with a comprehensive automatic control system. Maximum heat recovery is achieved by generating low pressure steam, which is used for the vacuum system. The distiller is a structured packing tower, with three packing layers (washing, condensation and scrubbing) and the vacuum system installed directly on the top of the tower. A separate distiller is included for pitch stripping. According to the raw material, the process may contemplate a pre-cut column, of the packing type (random or structured according to the product handled). The pre-cut tower, too, includes an internal condensation stage with external pumparound. Fatty acids of different chain length are fractionated under high vacuum in order to the maximum extent the distillation temperatures. All CMB fractionation columns are provided with structured packing of various types and various specific surfaces. All process variables are under full automatic control. Heat recovery may be pushed to the maximum possible extent, generating low pressure steam that is used for the vacuum system. Like the fatty acids straight distillation, the condensation and scrubbing sections make use of structural packing and are included in the tower itself. The vacuum system is directly connected to the tower(s). Column Reboiler(s) are of the forced circulation suppressed vaporization type, which reduces the local overheating and consequently the colour degradation of the product. A pre-cut tower can be contemplated upstream of the fractional distillation tower (s) according to the product. Materials of construction are carefully selected according to the fatty acid chain length.

Glycerine

The CMB glycerine distillation process is based on a very compact design composed of a single tower distiller , which incorporates the washing, rectification, main condensation and final condensation stages, with the vacuum system installed directly on top of the tower. High flexibility and possibility of coping with different grade raw materials are achieved by means of comprehensive automatic control system of all process variables.

High quality glycerine is obtained thanks to the washing stage which, due to the scrubbing effect, allows to produce very high quality glycerine even with lower grade raw materials.

Glycerine concentration of up to 99.8% is guaranteed by means of the rectification stage. The operating temperature is kept to a minimum thanks to the very low pressure drop, and consequently operating pressure, achieved by means of structured packing and specially designed draw-off plates.

A fully continuous in-line bleaching unit is contemplated . A wiped film evaporator is provided for as a secondary distiller on glycerine from spent lyes or from transesterification.

Miscellanea

In addition to the units detailed previously, CMB offers the following plants

Fat oil purification

By acid treatment or by bleaching according to the product.

Hydrogenation

Loop reactor for both total and selective hydrogenation of neutral oil and fatty acids. Total heat recovery generating low pressure steam and pre-heating the next batch.

Sweet water purification

Single or double step, semi-continuous or continuous.

Sweet water evaporation

One to four effects according to the capacity.

Spent lyes evaporation

Up to three effects with centrifuge or salt box for maximum glycerine recovery. Manufactured according to client’s requirements, in CS, or SS 2205 or copper nickel.