A method to predict nuclei size distributions for use in models of wet granulation

• Published in: Advanced powder technology : the international journal of the Society of Powder Technology, Japan Vol. 20; no. 4; pp. 293 - 297
• Main Authors: Hapgood, Karen P., Tan, Melvin X.L., Chow, Darren W.Y.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-07-2009
• Subjects: Agglomeration; Drop size; Flowrate; Granulation; Liquid addition; Modeling; Nucleation; Spray flux; Liquid addition; Flowrate; Nucleation; Granulation; Agglomeration; Drop size; Spray flux; Modeling
• ISSN: 0921-8831; 1568-5527
• DOI: 10.1016/j.apt.2008.09.004

Models of granulation and agglomeration are becoming more sophisticated and accurate, but nucleation is poorly understood. Models of granulation processes typically either use simplistic nucleation assumptions; complex multi-phase simulations or deliberately focus on the final granulation stages only. Here, we validate a simple method to generate nuclei size distributions using the dimensionless spray flux parameter, for future use in granulation models in the drop controlled regime.
Dimensionless spray flux describes the spray density in the spray zone, which is closely related to the Poisson distribution. A simple model to estimate the nuclei size distribution at a range of spray flux conditions was compared with data generated in a previous study. The simulations were in reasonable agreement with experimental data at low penetration time and low spray flux (
Ψ
a
<
0.3) but diverged when either the spray flux was >0.5. For a longer penetration time system, the simulations and experimental results agreed up to
Ψ
a
=
0.5. Multi-modal experimental results could not be modeled. Spray flux derived models of nuclei size distributions are useful nucleation granulation models, provided that the simulations are restricted to the drop controlled regime (
Ψ
a
<
0.1) and extended to higher spray fluxes with caution.