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Theoretical and Experimental Investigation of Breakage Kinetics in Particle Suspensions

English title Theoretical and Experimental Investigation of Breakage Kinetics in Particle Suspensions
Applicant Mazzotti Marco
Number 121882
Funding scheme Project funding (Div. I-III)
Research institution Institut für Verfahrenstechnik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Chemical Engineering
Start/End 01.10.2008 - 31.03.2010
Approved amount 146'753.00
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Keywords (11)

crystallization and precipitation; crystal breakage; population balance equation (PBE); multidimensional PBE; computational fluid dynamics; suspensions; breakup; crystallization; population balance equations; particles; crystals

Lay Summary (English)

Lead
Lay summary
Breakage in particulate systems is a key phenomenon determining the evolution of the particle size and particle properties during processing. This project focuses on the breakage of particles in stirred suspensions where special interest is given to crystal particles formed in solution crystallization. In the latter, breakage is believed to render the crystal particles to be more spherical, and it is considered to cause the formation of fines and to some extent also secondary nucleation (that is, nucleation caused by the presence of other crystal particles). Breakage may thereby be caused by collisions of the particles with the stirrer or the vessel wall or other suspended particles (impact breakage), or it may be caused by hydrodynamic forces due to the fluid flow in the dispersant (shear breakage). The governing mechanism depends thereby strongly on the particle inertia determined by its mass (or size), as well as on material and suspension properties.In this project we aim at developing a model that allows for a detailed description of breakage in particulate processes and solution crystallization. In particulate systems breakage is a stochastic process and its description therefore calls for a probabilistic model. Such are provided by population balance equation models where breakage enters as rate process. The breakage rate is thereby given by the product of the frequency with which a certain event occurs (i.e., an impact of a particle or the encounter of a particle with an intense turbulent event) and the probability that breakage occurs during such an event. This principle will be applied to both impact breakage and shear breakage and based on this rate expression for both mechanisms will be developed. Combining the resulting breakage model with other phenomena, i.e., nucleation, growth, and agglomeration, will thus provide a tool for simulating the entire crystallization process. Well designed experiments using a crystalline organic compound will be conducted to produce input for model development and, eventually, such experiments will serve for model validation.
Direct link to Lay Summary Last update: 21.02.2013

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