Analysis, modeling and simulation of quasistatic compressive stressing behavior of bonded model pellets
Final Report Abstract
The main objective of this project was to investigate experimentally and simulate the influence of pelletising process parameters on the compression behaviour of model-pellets with different structures, sizes and shapes. Pelletising is applied in many industry branches for improving the flow and dosage behaviour and for regulating the bulk density of various materials. Its wide use creates the need to investigate the pellets and their properties in depth. In order to gain better understanding about pellet properties and the behaviour of pellets under loading, model pellets were produced in a laboratory pelletizing plate. The primary particles used were aluminium oxide (gamma-Al2O3) and zeolite 4A granules of various sizes. Their properties are well known and can be taken as a reference. Water solution of hydroxypropylmethyl cellulose(HPMC) having various concentrations was used as a binder. During production, the process parameters of rotation speed, process duration and binder content were varied in order to analyze their influence on the properties of the pellets produced. Upon completing the manufacturing process, the model pellets were allowed to dry in atmospheric conditions. The pellets were divided into two fractions - tetrahedra (regular) and blackberry aggregates (irregular). The two fractions were studied separately to investigate the influence of the structure. Properties such as particle size distribution, density and porosity, internal spatial structure and behaviour of the pellets under load were examined in detail. The results obtained were further used for carrying out DEM simulations of the fracturing process during loading of the pellets. Tomographic data for primary particle number and spatial coordinates allow for a very accurate replication of the pellets in the simulation software. Virtual compression tests were performed on the simulated pellets and the results were compared with the experimental data. Pellet characterization has shown that the process parameters are of decisive importance for the formation and shape of the pellets. The detailed tomographic analysis has though proven that the process parameters influence only the binder distribution, not the arrangement and structure of the pellets. The experimental compression tests could be simulated using DEM and the results have been compared. For some of the simulations there is no possibility to realistically represent the solid bridges with their defects and micro-porosity in the DEM tool, so that the results deviate. The replication of experiments by means of DEM simulations is not possible in these cases.
Publications
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Influence of the pelletizing process parameters on the mechanical properties of the received alumina oxide pellets, 7th International Granulation Workshop, Sheffield, UK, 01.-03.07.2015
Z. Radeva, J. Tomas
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Influence of the pelletizing process parameters on the mechanical properties of zeolite pellets, 10th European Congress of Chemical Engineering, Nice, France 27.09–1.10.2015
Z. Radeva, P. Müller, J. Tomas
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Untersuchung des Einflusses der Prozessparameter auf die Bruchfestigkeit von Zeolith 4A Pellets, 7. Symposium „Produktgestaltung in der Partikeltechnologie“, Berlin, Germany, 23.-24.04.2015
Z. Radeva, P. Müller, J. Tomas
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Untersuchung des Einflusses der Prozessparameter auf die Bruchfestigkeit von Zeolith 4A Pellets, in: Produktgestaltung in der Partikeltechnologie, Band 7, Hrsg. Ulrich Teipel, Fraunhofer Verlag 2015, Congress: 7. Symposium „Produktgestaltung in der Partikeltechnologie“, Berlin, Germany, 23.- 24.04.2015, p. 299-311, ISBN: 978-3-8396-0877-7
Z. Radeva, P. Müller, J. Tomas
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Untersuchung des Einflusses der Prozessparameter auf die Bruchwahrscheinlichkeit von Zeolith Pellets, Jahrestreffen der Fachgruppen Agglomerationsund Schüttguttechnik, Magdeburg, Germany, 16.-18.03.2015
Z. Radeva, P. Müller, J. Tomas
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Influence of the pelletizing process parameter on the fracture strength of zeolite 4a pellets, Partec 2016, International Congress on Particle Technology, Nürnberg, Germany, 19.–21.04.2016
Z. Radeva, P. Müller, J. Tomas
