1. What is Janssen's length doing in an agglomerator?
- Author
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Bernard Cuq, Sandra Mandato, Thierry Ruiz, Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Agence Nationale de la Recherche (ANR), and Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)
- Subjects
Materials science ,GRANULAR FLOW ,Characteristic length ,[SDV]Life Sciences [q-bio] ,General Chemical Engineering ,Mixing (process engineering) ,Context (language use) ,02 engineering and technology ,PRESSURE ,ROTATIONAL SHEAR CELL ,MIXER ,01 natural sciences ,010305 fluids & plasmas ,SILOS ,020401 chemical engineering ,0103 physical sciences ,Geotechnical engineering ,0204 chemical engineering ,POWDER ,Janssen's law ,Economies of agglomeration ,Agglomeration ,Rotational speed ,Mechanics ,Granular matter ,Overburden pressure ,PIV ,Shear (sheet metal) ,Vertical stress profile ,Agglomerate ,STRESSES ,PARTICLE IMAGE VELOCIMETRY - Abstract
In a wet agglomeration process occuring in a low shear mixer, the function of the blade is to promote emergence of stable agglomerates and to homogenize the liquid sprayed on the powder surface. The design of the bowl and the mixing blade along with the values of the process parameters (load, rotation speed, etc.) contribute to the agglomeration mechanisms. In this work a preliminary approach is conducted to study the mechanical input during agglomeration through the analysis of static and dynamic stress distributions (by force measurements) and particles' motions (by visualizations through a transparent wall) in the powder bed, using an experimental mixing cell. A characteristic depth is identified as a representative parameter of the static state of a laterally confined semolina bed. This characteristic depth is implied when the granular medium is submitted to a vertical mechanical stress. For wet agglomerates, the static distribution of vertical stresses can be approximated by the Janssen's model. Under dynamic conditions, a correlation is found between the mechanical resistance of agglomerates and the maximum vertical stress according to the water content. In the context of wet agglomeration in a mixing device, these results allow to consider the role of the characteristic length in the mixing bowl. (C) 2012 Elsevier B.V. All rights reserved.
- Published
- 2013