Oil Modification

Hydrogenation

Hydrogenation is an oils and fats modification process.It is mainly used on vegetable oils like soya, rape, cotton or sunflower to increase their oxidative stability and to improve their melting properties by reducing their degree of unsaturation. As a result, these oils or fats reach a consistency that is ideal for use as margarine or shortening components

Hydrogenation is a reaction involving the use of a catalyst, most generally nickel, and is also an exothermic reaction.

Careful and precise hydrogenation requires that the constituents – oil, gaseous hydrogen and solid catalyst – should be mixed perfectly. This is done in a closed vessel, by agitation of the catalyst – fatty material suspension in contact with hydrogen.

The purpose of agitation is to promote hydrogen absorption and to maintain a permanent flow of fatty material through the pores of the catalyst. To do this, we use the Hydrogenator, in which hydrogen is forced into the oil and remains in it until the gas is fully consumed. The hydrogenator is batch type. It is equipped with several features to control and master reaction pressure, reaction temperature and the quantity and flow of hydrogen injected, all of which are essential to guarantee selective hydrogenation.

The feedstock used for hydrogenation is usually caustic refined and bleached oil. With the improvement of the degumming processes, there is a tendency to hydrogenate degummed oils. After hardening, those oils are bleached and physically refined.

Main Advantages of this process are:

• Improved gas dispersion;
• Low specific energy consumption;
• Steam production
• Fully automated plant and reliable controls;
• No venting required as hydrogen is entirely consumed at the end of the reaction

Fractionation

The process of fractionation consists of the separation of the liquid part (olein) from the solid part (stearin). In principle the process is very simple, involving:

• Keeping the fat at a controlled temperature to allow crystallization.
• Separate the formed crystals

Veendeep has adopted the dry fractionation process operating batch wise, as opposed to centrifugal separation with the aid of detergents or solvent fractionation. With this process oil is kept at a controlled temperature in large tanks with slow stirrers. Crystals form and build into aggregates of several millimetres in diameter. The slurry is pumped through a membrane-filter press for separation of the olein and stearin fraction.

The stearin cake obtained from the membrane filter press is melted in the stearin-melting tank below the press, which also acts as a stearin intermediate tank, prior to storage or packaging.