Modelling and simulation of particle grinding in a stirred tank using CFD-PBE coupled approach
Résumé
Wet grinding is a common unit operation in many industrial processes. A better understanding and modelling of the physical mechanisms inside the grinder will provide benefits in terms of time, energy saving and up-scaling. In the present study, we investigate by numerical simulations a stirred tank with a central impeller used for the grinding of a particulate powder dispersed in a liquid. The numerical simulations are based on a multi-fluid Eulerian approach coupled with Population Balance Equation (PBE) [1]. Eulerian-Eulerian approach is used to simulate the two-phase flow: an equivalent fluid (composed of the carrier fluid and the powder to be grinded) and grinding beads. The rotating part of the geometry is taken into account by the approach proposed by [2]. The PBE describes the spatial-temporal variations of the particle size-distribution using the class method. The breakage function and the breakage kernel are essential ingredients of the model to successfully account for the physical mechanisms. However, the breakage probability, capture probability, bead collision frequency are predicted by CFD simulations. The validation of the hydrodynamics is done by comparison with the experimental data of [3]. Moreover, time record of the granulometric distribution of the powder during grinding will be carried out to confirm the good accuracy of the model. Influence of operating conditions and physical properties of the solid phases, and process conditions will be investigated in order to gain a better physical understanding for up-scaling.
REFERENCES
[1] E. Bilgili et G. Guner, AAPS PharmSciTech, vol. 22, no 1, p. 2, janv. 2021, doi: 10.1208/s12249-020-01876-w.
[2] L. Bennani, H. Neau, C. Baudry, J. Laviéville, P. Fede, et O. Simonin, Chemical Engineering Research and Design, vol. 120, p. 333‑347, avr. 2017, doi: 10.1016/j.cherd.2017.01.028.
[3] R. Angst et M. Kraume, Chemical Engineering Science, vol. 61, no 9, p. 2864‑2870, mai 2006, doi: 10.1016/j.ces.2005.11.046.