In this study, a hybrid multi-scale model has been developed for a continuous fluid bed wet granulation process by dynamically coupling computational fluid dynamics (CFD) with a discrete element model (DEM) and population balance model (PBM). In this process, the granules are formed by spraying the liquid binder on the fluidized powder bed. The fluid flow field has been solved implementing CFD principles and the behavior of the solid particles has been modeled using DEM techniques whereas the change in particle size has been quantified with the help of PBM. The liquid binder droplets have been modeled implicitly in DEM. A detailed understanding of the process aids in the development of better design, optimization and control strategies. The model predicts the evolution of important process variables (i.e., average particle diameter, particle size distribution (PSD) and particle liquid content) over time, which have qualitative similarity with experimentally observed trends. The advantage of incorporating the multi-scale approach is that the model can be used to study the distributions of collision frequencies, particle velocity and particle liquid content in different sections of the fluid bed granulator (FBG), in a more mechanistic manner.
Article:Pradhan, S.U., Sen, M., Li, J. et al. (2 more authors) (2017) Granule breakage in twin screw granulation: Effect of material properties and screw element geometry. Powder Technology, https://doi.org/10.1016/j.powtec.2017.04.011Article available under the terms of the CC-BY-NC-ND licence (https://creativecommons.org/licenses/by-nc-nd/4.0/ eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website.
TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. survivor pellet shape visualization was used to infer that the breakage mechanism in conveying 23 elements (CE) is primarily edge chipping whereas in distributive mixing elements (DME),
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Granule Breakage in Twin Screw Granulation: Effect of Material Properties and Screw
24breakage is a combination of chipping and crushing. The maximum size of granule that could 25 remain unbroken (3mm for CE and 2mm for DME) was determined by the largest available gap 26 size in the element as measured by an analysis of the screw elements' open volume geometry.
27Below the maximum size, breakage probability varied inversely with granule strength up to 28 9kPa. For granules stronger than 9kPa DYS, breakage characteristics are independent of 29 formulation properties and depend only on screw element geometry. This helps explain why twin 30 screw granulation is more robust with respect to formulation changes compared to high shear wet 31 2 granulation. Implications for using the results for both optimizing screw element design and 1 calculating kinetic parameters for population balance modeling are discussed.2
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