Liquid distribution in wet granulation: dimensionless spray flux

Litster, J. D., Hapgood, K. P., Michaels, J. N., Sims, A., Roberts, M., Kameneni, S. K. and Hsu, T. (2001) Liquid distribution in wet granulation: dimensionless spray flux. Powder Technology, 114 1-3: 32-39. doi:10.1016/S0032-5910(00)00259-X

Author Litster, J. D.
Hapgood, K. P.
Michaels, J. N.
Sims, A.
Roberts, M.
Kameneni, S. K.
Hsu, T.
Title Liquid distribution in wet granulation: dimensionless spray flux
Journal name Powder Technology   Check publisher's open access policy
ISSN 0032-5910
Publication date 2001-01-01
Sub-type Article (original research)
DOI 10.1016/S0032-5910(00)00259-X
Open Access Status
Volume 114
Issue 1-3
Start page 32
End page 39
Total pages 8
Editor J.P.K. Seville
Place of publication Lausanne
Publisher Elsevier
Language eng
Subject C1
290699 Chemical Engineering not elsewhere classified
670601 Chemical fertilisers
670499 Other
290000 Engineering and Technology
290600 Chemical Engineering
290602 Process Control and Simulation
Abstract This study investigates binder distribution in wet granulation and focuses on the nucleation zone, which is the area where the liquid binder and powder surface come into contact and form the initial nuclei. An equipment independent parameter, dimensionless spray flux Psi (a), is defined to characterise the most important process parameters in the nucleation process: solution flowrate, powder flux, and binder drop size. Ex-granulator experiments are used to study the relationship between dimensionless spray flux, process variables and the coverage of binder fluid on the powder surface. Lactose monohydrate powder on a variable speed riffler passed under a flat spray once only. Water and 7% HPC solution at two spray pressures were used as binders. Experiments with red dye and image analysis demonstrate that changes in dimensionless spray flux correlate with a measurable difference in powder surface coverage. Nucleation experiments show that spray flux controls the size and shape of the nuclei size distribution. At low Psi (a), the system operates in the drop controlled regime, where one drop forms one nucleus and the nuclei size distribution is narrow. At higher Psi (a), the powder surface cakes creating a broader size distribution. For controlled nucleation with the narrowest possible size distribution, it is recommended that the dimensionless spray flux be less than 0.1 to be in the drop-controlled regime. (C) 2001 Elsevier Science S.A. All rights reserved.
Keyword Engineering, Chemical
Binder Dispersion
Spray Flux
Powder Flux
Fluidized-bed Granulation
Process Variables
Q-Index Code C1
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemical Engineering Publications
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Citation counts: TR Web of Science Citation Count  Cited 83 times in Thomson Reuters Web of Science Article | Citations
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Created: Wed, 15 Aug 2007, 02:26:42 EST