Abstract
In Draft Tube (DT) crystallizers secondary nuclei are predominantly produced due to crystals colliding with the impeller. The formation step of these nuclei is a complex process depending on the local two-phase flow pattern in the vicinity of the impeller and on the attrition behavior of the crystalline material. In order to develop crystallizer models with a predictive value for different operational conditions or for different scales of operation a mechanistic description of the secondary nucleation rate is a prerequisite.
In this paper two model frameworks (Gahn et al., 1997 and Ó Meadhra et al., 1996) have been compared using experimental results obtained from a 22 liter DT crystallizer. First, both model frameworks were compared on the basis of the volumetric attrition rate. A discrepancy (factor 20) between both model frameworks was observed. In a second approach both models were tested by comparison of the trend of the predicted median crystal size, L50, with the experimental one in a dynamic experiment. Both models are in good agreement with the experimental data regarding the predicted steady-state L50. The dynamic behavior predicted by the models, however, differs from the measured behavior regarding the oscillation frequency, phase and amplitude.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Gahn, C., Mersmann, A. (1997) Theoretical Prediction and experimental determination of attrition rates, Trans IChemE, Vol 75, Part A.
Gahn, C. (1997) Die Festigkeit von Kristallen und ihr Einfluß auf die Kinetik in Suspensionskristallisatoren, Herbert Utz Verlag Wissenschaft, München
Heijden A.E.D.M. van der, Elwenspoek, M., Eerden J.P. van der (1989) Size Distribution of Empryos produced by Crystal-Rod contacts, J. Crystal Growth 98, 398
Heijden A.E.D.M. van der (1992) Secondary Nucleation and Crystallization Kinetics, PhD thesis, University of Nijmegen
Mersmann, A. (1995) Crystallization Technology Handbook, Marcel Dekker Inc., New York.
Mersmann, A., Sangl, R., Kind, M., Pohlisch, J. (1988) Attrition and Secondary Nucleation in Crystallizers, Chem. Eng. Technol. 11, 80 - 88.
Ó Meadhra, R., Kramer, H.J.M., Rosmalen, G.M. van. (1996) Model for Secondary Nucleation in a Suspension Crystallizer, AIChE Journal, Vol. 42, No. 4, 973 - 982.
Plop, R., Mersmann, A. (1989) New Model of the Effect of Stirring Intensity on the Rate of Secondary Nucleation, Chem.Eng.Technol., 12 (1989), 137 - 146.
Zacher, U. (1995) Die Kristallwachstumsdispersion in einem kontinuierlichen Suspensionskristallisator, PhD thesis, München University of Technology
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2000 Springer Science+Business Media Dordrecht
About this chapter
Cite this chapter
Neumann, A.M., Bermingham, S.K., Kramer, H.J.M., Van Rosmalen, G.M. (2000). Modeling the Attrition Process in a 22 Liter Draft Tube Crystallizer. In: Gupta, B.S., Ibrahim, S. (eds) Mixing and Crystallization. Springer, Dordrecht. https://doi.org/10.1007/978-94-017-2290-2_23
Download citation
DOI: https://doi.org/10.1007/978-94-017-2290-2_23
Publisher Name: Springer, Dordrecht
Print ISBN: 978-90-481-5410-4
Online ISBN: 978-94-017-2290-2
eBook Packages: Springer Book Archive