The preparation of any oil bearing material for subsequent
extraction is an important step. The raw material is cooked,
steamed and make into pellets & then fed to the extraction
process. The cakes are first passed into cracker where
the bigger pieces are broken into smaller pieces. Cooking
and conditioning are carried out as it break down the
cell-walls of the oil.
Extraction
The cracked cakes enter the extractor through a bin at
the bottom of which is fixed a rotary valve which takes
the material into the extractor. The extractor is the
heart of the entire process. It is designed to suit a
number of stages of equilibrium required for extraction
of oil by solvent hexane. All the extractors are gravity
percolation type. Equilibrium stages upto 10 to 12 are
quite common. The hexane, while percolating through the
cake bed, dissolves the oil and form miscella which is
subsequently taken to heaters for separating hexane from
oil in three to four stages.
Desolventisation
The extracted material emerging out of the extractor contains
solvent called Marc and has to be desolventised. The Marc
is passed through Desolventisers (or Desovlentiser toasters)
of vertical multipan construction. The entering material
passes from stage to stage while being agitated/rotated
with an agitator shaft fitted with blades. Each compartment
ahs a double shaft fitted with blades. Each compartment
has a double bottom for steam heating. Direct/open steam
is also passed to make the operation more efficient and
also to maintain certain moisture level in the meal.
Miscella
Distillation
As stated above, the hexane, after percolation, dissolves
the oil from the cake and the solution so formed is called
Miscella. The two liquids of the miscella must be separated.
This is done by evaporation of hexane, having a boiling
point of 63 degree Celsius from which oil has a b.p. of
350 degree Celsius. The distillation is generally carried
out in vacuum conditions since it increases the efficiency
of evaporation and does not alter the oil characteristics.
After carrying out distillation in two or three stages
(where miscella carrying tubes are heated by steam), the
miscella is finally taken to stripping column where from
the oil is taken to storage. The solvent & water mixture
is passed to solvent water separators which work on the
principle of hydrostatic balancing of columns of two liquids
differing in densities and which are not miscible.
Market & Demand
Analysis
Oil is the main product whereas De-oiled Extractions are
by-product. The demand for oils and fats has been growing
continuously along with the grown in population as well
as improvement in the standard of living, though the per
capita consumption in the country is as low as 6 Kg per
annum as against the world average of over 20 Kg per annum.
Moreover, this is an Export Oriented Industry, as De-oiled
Extractions finds a good export market in the foreign
countries.
The preparation of any oil bearing material for subsequent
extraction is an important step. The raw material is cooked,
steamed and make into pellets & then fed to the extraction
process. The cakes are first passed into cracker where
the bigger pieces are broken into smaller pieces. Cooking
and conditioning are carried out as it break down the
cell-walls of the oil. 
As stated above, the hexane, after percolation, dissolves
the oil from the cake and the solution so formed is called
Miscella. The two liquids of the miscella must be separated.
This is done by evaporation of hexane, having a boiling
point of 63 degree Celsius from which oil has a b.p. of
350 degree Celsius. The distillation is generally carried
out in vacuum conditions since it increases the efficiency
of evaporation and does not alter the oil characteristics.
After carrying out distillation in two or three stages
(where miscella carrying tubes are heated by steam), the
miscella is finally taken to stripping column where from
the oil is taken to storage. The solvent & water mixture
is passed to solvent water separators which work on the
principle of hydrostatic balancing of columns of two liquids
differing in densities and which are not miscible. 