Solvent extraction process involving the injection of hexane into the oil bearing cells of seed resulting in a mix of oil and solvent, and this mixer is called miscella.
The entire process is largely divided into three main sections as follows:
  • Seed preparatory section
  • Main extraction section
  • Meal / cake treatment section
The main extraction section is again divided into the following subsection:
  • Extraction of oil from prepared raw material
  • Desolventisation
  • Distillation / Evaporation of hexane to recover oil from miscella
  • Condensation of hexane
  • Final solvent recovery section
Preparatory section
An efficient extraction would need that every oil bearing cell of the seed comes in contact with hexane. A smaller material size gives a better penetration of the solvent into the oil bearing cells, but once too small it will prevent the solvent from percolation through the mass. Hence an optimum size is absolutely essential for efficient extraction.

The method of material preparation dose vary from material depending upon its oil content and physical properties, we group them as follows
The main extraction section is again divided into the following subsection:
  • Oil cakes
  • High oil content material (soyabean, sunflower, cotton seed, rape seed etc)
  • Floury material (rice bran)
The prepared material is transported to the main extraction section via conveyor.
The prepared material as described above is received into the extraction plant by a conveyor. The transport speed through the solvent spraying chamber can be varied easily.

This chamber contains of a number of solvent sprayer which spray a solvent over the entire bed of raw material. To view the distribution of spray, a light and sight glasses are provided

The wet meal is coming out of the spraying chamber is de- oiled material and absorbed solvent which is to be recovered in the desolventising section. The mixture of the oil and solvent called “miscella” is pumped into the miscella tank, from where it will be transported by means of special conveyor to the desolventiser.
The wet meal content 20% to 35% solvent. The basic principle involved in desolventisation is direct and indirect heating of the wet meal with steam to a temperature well above boiling point of the solvent to ensure that no solvent is left over in the meal. Solvent vapors are sent to the condenser via a scrubber where the solvent is washed from any fines.

The de- oiled and desolventised meal is transported to the bagging section withy the help of conveyor.
Miscella content 12% to 18% solvent in the case of oil cake or rice bran but 25% to 35% in the case of sunflower seed, during distillation solvent evaporates first due to its lower boiling point (64 to 67 0c) leaving clean oil behind.

Distillation is performed in three stages under vacuum to ensure that no oxygen is present when the oil is heated to high temperature. Presence of oxygen will make the oil rancid. First evaporation takes place in an economizer and is followed by a Flasher leaving practically only oil behind. This oil is further treated with open steam to ensure that no solvent stays behind.

The solvent vapors thus produced passes through an oil vapor separator to Separate out any oil particles trapped with the solvent vapors before passing on to a Condenser.
Solvent vapors are formed both in the Desolventisation section as well as in the Distillation section and need to be condensed. Special floating head types help quickly and easy removal of tubular for periodical cleaning.
Final solvent recovery
The air that is being ejected out of the system contains traces of solvent. In order to recover these traces, a special final vent air stripping column has been provided. It comprises of main Absorber to give a large contact surface. It is partly filled with Groundnut oil to adsorb the solvent vapors from the air. The oil and solvent mixture is Distilled later to recover the solvent.
Meal/Cake treatment section
The extracted and desolventised meal is transported to the bagging section by means of a Conveyor fitted with cooling arrangements.
Pricing is depended on plant size and feedstock to be processed. Please inform us about this and we will make you an offer.