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Solvent Extraction Plant
The purpose of solvent plant extraction,
oil solvent extraction is to remove most of the oil contained in a seed.
Extraction is conducted on prepared seeds or, generally in the case of high
oil content seeds, the cakes obtained by the pre-pressing. Solvent
Extraction consists of a sequence of five operations, i.e. :
- Preparation of Seeds for Extraction which includes pre pressing for
high oil content seeds.
- Extraction of oil from the prepared material with the aid of food
- Desolventising-toasting of the de-oiled seed /meal- often combined
with drying and cooling of the said meal.
- Distillation, to remove the solvent from the extracted oil.
- Recovery of solvent, which is reused again and again at extractor
Veendeep supplies the most advance, high performance Oil Solvent Extraction
plants which are able to process seeds like soyabeans, sunflower, cotton
seeds, rapeseeds and floury material like rice bran.
Solvent Extraction Process includes the following
An efficient Extraction would need that every oil
bearing cell of the material is in contact with the solvent. In other words,
the smooth preparation prior to main extraction is very vital to comply with
this contact, smaller the material size, better the penetration of the
solvent into the oil bearing cells, but too fine a size will prevent the
solvent from percolation through the mass. Hence an optimum size is
absolutely essential for efficient extraction.
The method of material preparation does vary from material to material
depending upon its oil content and physical properties. We group them as
- Oil Cakes
- Oil Bearing Seeds (Soybeans, Sunflower, Rape Seed, Canola)
- Floury Materials (Rice Bran)
In the case of oil cakes, being big pieces, has to be reduced to proper
size and without fail, ensuring that there are no fines. OILTEK
Cake Sizer and Cake Cracker are the finest to this process.
In case of high oil content seeds like soybean, sunflower, rapeseed, canola
it passes through, the well proven OILTEK Expander after cracking, cooking &
flaking. Seeds like sunflower, rapeseed, canola will pass through the
squeezomatic attachment for squeezing the oil before the collects goes to
extraction, passing through updated OILTEK Drier Cooler.
In case of Floury materials like rice bran, etc. any of the above equipment
are not workable. Hence an OILTEK Pelletiser or Expander with conditioning
arrangement has been used to form pellets before extraction.
The prepared material is transported to the Main Extraction Section via an
The prepared material is received into the OILTEK
Extractor by an OILTEK Conveyor via an OILTEK Air seal in the raw material
receiver section, which has an arrangement for controlling the level of
material received by the Extractor.
The design of OILTEK Extractor is such that its speed is adjusted
automatically depending upon the capacity being processed by means of level
controllers coupled with variable frequency drive to its motor.
The Extractor chamber consists of a number of solvent sprayers which in
uniform, sprays the solvent over the entire bed of raw material. The length
and breadth is designed to give sufficient time for intimate contact,
penetration and percolation of solvent into raw material. The Extractor is
also designed with light and sight viewing glasses to view the spray
The material coming out of the spraying chamber is de-oiled material with
solvent which is to be recovered in the Desolventising section where it is
transported by means of a special OILTEK Solvent Seal Conveyor . The mixture
of the oil and solvent called Miscella is collected in the
Miscella tank from where it is pumped to distillation section.
The de-oiled meal contains about 20% - 35% solvent by weight depending on
the material. The meal must be desolventised.
The basic principal involved in Desolventation is direct heating of
material with steam to a temperature well above boiling point of the solvent
and thus ensuring no solvent is left over in the material. Toasting is also
heating the material with direct and indirect steam to remove the remaining
hexane and as well toast the meal.
Vapours of solvent are then sent to OILTEK Condensers via OILTEK Scrubber
where the solvent vapour is washed, and particulars of fines are not carried
to the condensers.
The OILTEK Air seals are provided at inlet and outlet of OILTEK
Desolventisers to ensure an air tight arrangement. This is essential to keep
the solvent loss figure down. The de-oiled and de-solventised meal thus
obtained is then transported to Bagging Section.
Veendeep takes great care in designing and sizing the Desolventiser as to
minimize the steam and power consumption.
Mixture of oil and solvent obtained in the OILTEK Extractor is known as miscella
and it normally contains 12%-35% depending on the material used. During
distillation, solvent evaporates first due to its low boiling point (64 to
67 deg C) thus 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 a high temperature.
Presence of Oxygen will exercise the oil, making it unsuitable. First
evaporation takes place in Economizer and concentrates in the Evaporator,
Pre Heater and Final Heater. After each step of evaporation the oil passes
through Oil Vapour Separator, which separates the evaporated vapour leaving
practically only oil behind. This oil is further treated with open steam in
OILTEK Stripper and then finally dried in OILTEK Drier to ensure that no
solvent finds its way along with the oil. The oil is finally cooled in
OILTEK Oil Cooler to below 60° C before sending it to storage.
The solvent vapours thus produced by passing through OILTEK Oil Vapor
Separator to separate out any oil particles trapped with solvent vapors and
are then passed on to OILTEK Condenser for condensation.
Solvent vapours are formed both in Desolventisation Section as well as in
Distillation Section and these are to be condensed. Special floating head
type OILTEK Condensers are provided. The floating head type OILTEK
Condensers help in quick and easy removal of tubular bundles for periodical
cleaning. Adequate surface area have been provided for OILTEK condensers for
complete condensation of solvent vapour.
Final Solvent Recovery
In spite of providing adequate Condensers, the air that is being injected
out of the system contains traces of solvent. In order to recover the
traces, a special final vent air stripping column has been provided. It
comprises of a main OILTEK Absorber to give a large surface of contact. It
is partly filled with mineral oil which is a suitable absorbing media that
absorbs the solvent vapours from the air. The oil and solvent mixture is
stripped to recover the solvent.
The deoiled meal from the desolventiser toaster is transported to bagging
section via OILTEK conveyors with cooling arrangements. In this section the
meal is cooled in OILTEK Meal Cooler which comes with blowers for cooling
and cyclone for arresting dust particles.
The cooled meal from outlet of the cooler is then screened in a
Screener/Grader for separating any large particles which are reduced to
smaller fines in OILTEK lump grinder. The meal is then bagged in OILTEK
Automatic Bagging Machine.