Hysteresis in cloud heights during solid suspension in stirred tank reactor: Experiments and CFD simulations

Solid suspension in stirred tank reactor is widely used in process industries for catalytic reactions, dissolution of solids, crystallization, and so on. Suspension quality is a key issue in design and operation of stirred reactor and its determination is not straight forward. Cloud height measureme...

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Bibliographic Details
Published in:AIChE journal 2010-11, Vol.56 (11), p.2795-2804
Main Authors: Sardeshpande, Madhavi V, Juvekar, Vinay A, Ranade, Vivek V
Format: Article
Language:English
Subjects:
Applied sciences
Catalysis
Catalytic reactions
CFD
Chemical engineering
Chemical reactors
Chemistry
Clouds
Computational fluid dynamics
Computer simulation
Crystallization, leaching, miscellaneous separations
Exact sciences and technology
Experiments
General and physical chemistry
Hysteresis
hysteresis in cloud height
Impellers
Magnetism
Mathematical models
Mixing
Reactors
Solid suspensions
solid velocity profiles
Solids
Tanks
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
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Summary:Solid suspension in stirred tank reactor is widely used in process industries for catalytic reactions, dissolution of solids, crystallization, and so on. Suspension quality is a key issue in design and operation of stirred reactor and its determination is not straight forward. Cloud height measurements of solid suspension provide a relatively simple way to quantify quality of suspension. In this work, experiments were carried out to quantify variation of cloud heights with impeller speed and particle characteristics. These measurements were carried out using visual observations, image analysis, and ultrasound velocity profiler techniques. The obtained data demonstrated the existence of hysteresis in cloud heights with respect to impeller speed. Apart from possible applications in reducing power required for achieving desired solid suspension quality, the existence of hysteresis also provides a new way to evaluate computational fluid dynamics (CFD) simulations of solid-liquid flows in stirred vessels. An attempt was made to capture observed hysteresis in cloud heights in CFD simulations. The simulated results were compared with the experimental data. The presented models and results (experimental and computational) will be useful for simulating complex solid-liquid flows in stirred reactors. © 2010 American Institute of Chemical Engineers AIChE J, 2010
ISSN:0001-1541
1547-5905
DOI:10.1002/aic.12191