Deodorization

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1. OBJECTIVE


The objective of deodorization is the removal of highly volatile compounds (e.g. free fatty acids) from materials (BAT in the Food, Drink and Milk Industries, June 2005).


2. FIELD OF APPLICATION


Deodorization is widely applied in the refining of edible oils and fats. Free fatty acids and other compounds can be removed from crude degummed and/or alkali refined edible oils and fats after bleaching. Deodorization is also applied in the production of decaffeinated coffee, where solvent traces from the caffeine extraction process can be removed (BAT in the Food, Drink and Milk Industries, June 2005).


3. DESCRIPTION OF TECHNIQUES, METHODS AND EQUIPMENT


Deodorization is the use of steam distillation to strip free fatty acids and other highly volatile components, under vacuum conditions, from oils, fats and other materials. The equipment used for deodorization consists of a steam distillation column, barometric condenser, demisters and scrubbers. Steam is injected into the heated material to over 200°C at the bottom of the distillation column, which is under vacuum conditions. The steam stripes compounds and other impurities from the material. The steam is condensed afterwards, using a barometric condenser of either once-through or closed circuit design (BAT in the Food, Drink and Milk Industries, June 2005). The separation of the volatile components from this steam can be enhanced by a one-stage or a two-stage scrubbing/condensation system and by demisters. Deodorization can be operated in batch or continuous deodorizing vessels (BAT in the Food, Drink and Milk Industries, June 2005).


4. COMPETITIVE TECHNOLOGIES AND ENERGY SAVING POTENTIALS


a) Changes in the process
  • Membrane distillation:
This is a separation method in which a non-wetting, microporous membrane is used with a liquid feed phase on one side of the membrane and a condensing, permeate phase on the other side. Membrane distillation is also known as transmembrane distillation, membrane evaporation, and thermo-pervaporation. Separation by membrane distillation is based on the relative volatility of various components in the feed solution. The driving force for transport is the partial pressure difference across the membrane. Separation occurs when vapor from components of higher volatility passes through the membrane pores by a convective or diffusive mechanism (McGraw Hill Access Science:
http://www.accessscience.com/Encyclopedia/4/41/Est_414210_frameset.html?doi).
Membrane distillation is widely used as a water desalination alternative technology (Novel Membrane and Device for Direct Contact Membrane Distillation based Desalination Process, New Jersey Institute of Technology Newark NJ).
Vacuum membrane distillation is a membrane-based separation process considered to remove volatile organic compounds from aqueous streams. It’s typically used for dewatering alcohols. (Wiley InterScience: http://www3.interscience.wiley.com/cgi-bin/abstract/109062827/ABSTRACT?CRETRY=1&SRETRY=0)
In food processing, membrane distillation is used to concentrate fruit juices at room temperatures (http://www.cs.cnr.it/area/posters/irmerc-ing.html).
The use of membranes in distillation processes reduces the energy consumption (Emerging Energy-Efficient Technologies in Industry: Case Studies of Selected Technologies, Ernest Orlando Lawrence Berkeley National Laboratory University of California, May 2004).


b) Changes in the energy distribution system

No information is available.


c) Changes in the heat supply system

No information is available.


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