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Air classification
Additional effects Due to the high velocities of the particles electrostatic charging can occur.
Author WikiSysop  +
Companies Hosokawa Alpine + , Hosokawa Micron +
Completed by Wageningen UR - FBR +
Consumer aspects None.
Database search history Web of Knowledge: ‘air classification’ and document type ‘review’ (303 results) <br />Scopus: ‘air classification’ and document type ‘review’ (10 results)
Environmental aspects The dry process will consume less energy compared with wet separation including drying.
Important process parameters Air flow, rotational classifier speed +
Important product parameters Particle size, density +
Innovation source Other +
Institutes Wageningen UR - FBR +
Key words and relations separation  + , dry powder  + , particle size  + , density  + , air  +
Latest version 20 December 2010  +
Legal aspects None.
Match with potential needs/short comings This method saves a lot of drying energy when the process replaces a wet separation method. Moreover, reduction of functionality of protein can be avoided.
Maturity Air classification is available at pilot and industrial scale.
Modularity Air classification can be inserted in an existing production line. Note that a lot of air is used and equipment to generate that must also be implemented.
Operation Separation +
Operations Separation
Other limitations None.
Primary objective of technology or innovative tool The aim of air classification is to separate (milled) powders into fractions.
Principle Physical +
Product Dry powders (<1mm), flours, dry mixtures
References 1. Ratnayake W.S., Hoover R., Warkentin T. 1. Ratnayake W.S., Hoover R., Warkentin T. Pea starch: Composition, structure and properties - A review (2002) Starch/Staerke, 54 (6), pp. 217-234. 2. Chavan J.K., Kadam S.S. Nutritional enrichment of bakery products by supplementation with nonwheat flours. (1993) Critical reviews in food science and nutrition, 33 (3), pp. 189-226. 3. Vose, J.R., Basterrechea, M.J., Gorin, P.A.J., Finlayson, A.J., Youngs, C.G., 1976. Air classification of field peas and horsebean flours. Chemical studies of starch and protein fractions. Cereal Chem. 53, 928–936. 4. R. D. Reichert, C. G. Youngs: Nature of the residual protein associated with starch fractions from air-classified field pea starches. Cereal Chem. 1978, 55, 469–480. 5. R. T. Tyler, C. G. Youngs, F. W. Sosulski: Air classification of legumes. I. Separation efficiency, yield and composition of the starch and protein fractions. Cereal Chem. 1981, 58, 144–148. fractions. Cereal Chem. 1981, 58, 144–148.
Restricted products Liquids, gases, large solids (>1mm, incl. packed products). Sticky and wet powders.
Review document Template:Review document +
Review status Template:Review status +
Risks or hazards If electrostatic charging occurs, there is a risk of a dust explosion. This can be avoided/minimised by using an inert gas (e.g. nitrogen or carbon dioxide).
Subtask 2.2.1 +
Technology class Air classifiers  +
Title Air classification  +
Working principle The separation is based on the aerodynamic The separation is based on the aerodynamic behaviour of small particles. On one hand the rotational speed results in a centrifugal force. on the other hand the airflow results in a drag force. Due to different particle sizes there is an imbalance between the drag force and the centrifugal force. [[file:Imbalance.jpg|none|400px]] A dust cloud is created from the feeded powder. Due to under-pressure inside air flows through the rotating classifier. Smaller particles are removed from the cloud by the air flow. The large pasticles remain outside the classifier. Both fractions are collected in bins. [[file:multimolen_1.jpg|none|400px]] bins. [[file:multimolen_1.jpg|none|400px]]
Creation dateThis property is a special property in this wiki. 28 February 2012 12:01:24  +
Categories Technology Sheet  +
Modification dateThis property is a special property in this wiki. 17 May 2015 20:11:10  +
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