3. Deodourization
• Deodourization is a vaccum stripping process
in which neutral oil is treated to remove
malodorous compound ( volatile compound in
general) to obtain fully refined oil.
• This process is similar to steam refining of
neutral oil where along with malodorous
compound even fatty acids are also
removed.The above process is then known as
steam deodourization.
5. Deodorization Technology
• Deodorization is a multi-step process
comprising de-
aeration, heating, deodorization-
deacidification, and cooling of the oil.
• General overview of Deodorization plant can
be shown as
6.
7. Deaeration
• Carried out in order to avoid oxidation and
hence avoid risk of polymerization.
• Oil is heated to 800c and sprayed in a
tank, which is kept at a pressure below 50
mbar.
• Lower the pressure lower is residual air left in
the oil.
8. Heating and Cooling
• The subsequent heating of the oil is usually
accomplished in two stages.
• In the first stage, the incoming oil is heated
counter currently in an oil-oil heat exchanger
(economizer), with the finished oil leaving the
deodorizer.
• Finally, the oil is heated under reduced
pressure to the final deodorization
temperature with a high-temperature source.
9. Heating and Cooling
• Source of Heating in the final stages are
1) High-pressure steam boilers
2) Thermal Oil Heaters
3) Downtherm A (diphenyl/diphenyloxide)
• The net heating energy required for a
deodorization system can be calculated as:
H= [ O.c.(T2-T1).fL.fR ]
11. Heating and Cooling
• In industrial practice, heat recovery has
become an important factor because it
minimizes the cost of additional heating of the
oil to the deodorization temperature.
• For above purpose Heat exchangers have been
evolved and they are classified as follows
1) External Heat Exchanger
2) Internal Heat Exchanger
12.
13. Heating and Cooling
• Heat recovery can be done directly by
exchange of heat between the two oil stream
at different stream ( e.g.. Bleached oil Vs
Deodorized oil)flowing in counter current
direction through the exchangers or indirectly
by steam production.
14. Heating and Cooling
• Final cooling of the oil is usually conducted under
reduced pressure to prevent the possible
production of degradation by products.
• As a result of the technological complexity and
for cost reasons, cooling under vacuum is usually
applied only in a large capacity deodorizer. Small
capacity plants often make use of external oil–oil
heat-exchanging devices.
15. Steam Stripping
• Amount of stripping agent is proportional to its
molecular weight.
• Hence steam is being used for stripping.
• But N2 is being experimented to be used as stripping
agent.
• studies have indicated that color, residual
FFA, oxidative stability, as well as the formation of
trans-fatty acids and the stripping of tocopherols are
not affected by the nature of the stripping agent.
• Stripping agent must be dry and free from oxygen.
16. Steam Stripping
• Deodorization only occurs at the vapor-liquid
contact zone where the lowest operating
pressure exists.
• Hence there are different Deodorizer design
which attempt to provide the best contact
between the gas phase and the oil phase by
creating a large contact surface, together with
an optimal sparge steam distribution.
20. Vapor scrubbing system
• Composition of vapor phase
- Volatile components (FFA, odor components)
- Stripping steam
- Non condensable gases (air,…).
• The volatile substances are condensed by
creating an intimate contact between the
vapor and the fatty acid distillate circulating in
the scrubber.
21. Vapor scrubbing system
• Condensation of vapour phase is achieved by
series of sprayers or packed bed in vacuum
duct.
Installation of demister at the top.
improved scrubbers operating at two
different temperatures (so-called dual
condensation principle) have been introduced.
23. Vacuum systems
• Combination of steam jet ejectors (boosters),
vapor condensers and mechanical (liquid-ring)
vacuum pump
• High motive steam consumption (60-85% of
total steam).
25. Batch Deodorization
• Batch deodorization is especially suitable for
small capacities (<50 ton/day), irregular
production, or in processing small batches of
different oils that demand minimum cross-
contamination.
• Batch deodorizers mainly consist of a single-
shell welded vertical cylindrical vessel
26. Batch Deodorization
• Advantages :
very simple
construction and low capital cost
• Disadvantage:
Low capacities
high operating costs (high steam consumption, very
low heat recovery),
relatively long processing times (sometimes up to 8 h)
27.
28. Semi Continous Deoderisation
• Suitable for Large capacity.
• Used when frequent feedstock changes of oil
sensitive to cross contamination.
• Allows efficient Heat Recovery
• Steam produced in the bottom deodorized oil-
cooling section is sent in a closed
thermosiphon loop to the top bleached oil-
heating section to heat the incoming oil.
• Main advantage is shorter hold up time.
29. Continuous Deodorization
• Several configuration of continous
Deoderisation are
horizontal vessels
vertical tray-type deodorizers
packed columns
33. Continuous Deodorization
• Advantages :
Low utilities cost (high heat recovery)
Short residence time
Excellent control of all parameters
• Disadvantage: Contamination during
feedstock change
34. Improved Deodorization Technology
• Dual temperature deodorization
- Deodorization at two different temperatures
• Integration of packed columns
- for specific application only
- efficient stripping - lower steam consumption
• Dual condensation
- Condensation at two different temperatures
- Higher added value of deodorizer distillate (physical refining)
• Dry-Ice condensing
- Lower deodorizing pressure (1 mbar)
- Allows milder refining (lower temp)
35. REFERENCE
• Various Search results on www.google.com
• Lipid Library
• Oils and Fats by Alton Bailey
• Chemistry and Technology of Oils and Fats by
M.M Chakrabarthy.
• Dr A V JOSHI (ICT) & Dr AMIT PRATAP (ICT) for
giving advise.
Editor's Notes
where O is the amount of oil (kg), T1/T2 is the incoming and final temperature of the oil (C), c is the average specific heat capacity of vegetable oils (typically 2.2– 2.4 kJ/kgC), fL is the heat loss factor from radiation (typically 1.05–1.15), and fR is the heat recovery factor [1-(%heat recovery/100)].
Nitrogen has the advantage of being an inert andnoncondensable gas. Theoretically, its use will result in lower loss (no hydrolysis)and a more pure deodorizer distillate. Although it is possible to work with nitrogen under the commonly applied process conditions, experiments have shown that the profitability is very uncertain, depending on the existing installations in the factory and the nitrogen supply
The distillate is usually circulated at the lowest possible temperature (just above the melting point) to obtain the best possible condensation of thefatty matter present in the vapor phase that leaves the deodorizer.
