Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-III-32ON THE ANALYSIS OF PACKED BED STRUCTURE OF SPHERICALPARTICLES IN CYLINDRICAL CONTAINERSW.I. Salvat 1 , N.J. Mariani 1,2 , O.M. Martínez 1,2 , G.F. Barreto 1,21 Departamento de Ingeniería Química, Facultad de IngenieríaUniversidad Nacional de La Plata, La Plata, ArgentinaE-mail: ommartin@ing.unlp.edu.ar2 Centro de Investigación y Desarrollo en Ciencias Aplicadas «Dr. J. J. Ronco» (CINDECA)CONICET- Universidad Nacional de La PlataCalle 47 No. 257, CP B1900AJK, La Plata, ArgentinaIntroduction and objectiveCylindrical packed beds are widely used in almost all chemical process industries.Catalytic fixed bed reactors with either single or two phase flow are one of most importantexamples. In such type of units catalytic particles can have sizes fairly different from finepowders, often reaching several millimeters. The model employed to simulate the reactordetermines the degree of information required about packed bed structure. For the nowadaysincreasing use of the computational fluid dynamics technique -CFD- it is necessary to statethe positions of all particles [1]. Therefore, the knowledge of packed bed structure is ofparamount importance.In a previous paper [2], we have developed an algorithm to simulate the structure of acylindrical container filled with spherical particles of uniform size. The approach employed iscalled soft spheres algorithm. It allows some degree of interpenetration between particles. Theforce balance accounts for gravity and a contact force (to take into account theinterpenetration) and neglect the friction force between particles. The result obtained from thealgorithm is the position of each sphere in the container. From this information, all the packedbed structure properties can be calculated. The results obtained with the simulation werecontrasted with the experimental data for overall void fractions. The comparison was verysatisfactory [2].The objective of this contribution is to present additional results obtained throughsimulation. Particularly, the radial and axial void fraction profiles and contact points betweenparticles and between particles and the wall were analyzed. Taking into account the algorithmcharacteristics, a wide range of values of aspect ratio (i.e. tube to particle diameter ratio) hasbeen studied. In this way, some special features at low aspect ratios can be assessed.Results and discussionTaking into account that the results obtained from the algorithm are the position of eachsphere in the container, to calculate the void fraction at each radial or axial position the363