Monte Carlo modeling of binder‐Less spray agglomeration in fluidized beds

Abstract

Fluidized bed spray agglomeration is used in the industry to increase the particle size and to improve several properties, for example, bulk density, flowability, and dissolution behavior of particulate products. Usually, a binder liquid is sprayed on a particle bed. If amorphous materials are used, spraying of pure water may cause agglomeration due to glass transition at wet spots on the particle surface. As no process models covering binder‐less spray agglomeration currently exist, a model based on a Monte Carlo method is presented. In this method, the process is described by events and processes on the single particle scale. Additionally, agglomeration experiments in a lab‐scale fluidized bed using three different maltodextrins are presented. For each experiment, a simulation was performed. The simulation results are compared with the obtained experimental data. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3582–3594, 2018

Estimation of the dominant size enlargement mechanism in spray fluidized bed processes

“…In these cases a normal distribution was used as well, where the standard deviation was set to 10% of the mean diameter. The collision velocity was calculated for each simulation using the method proposed by Dernedde as described above. In a study presented by Rieck et al, the collision velocities calculated with this method were in the same range as values which had experimentally been obtained by Jiang et al using particle tracking velocimetry.…”

“…Note that at this stage the calculated collision velocity is kept constant (i.e., it is not adjusted according to changing particle properties during the simulation). A more detailed description of this method is also given by Rieck et al in the frame of Monte Carlo modeling. Note that the values given for the mass‐transfer coefficient in Table correspond to the initial values since β decreases over time due to size enlargement.…”

“…Note that at this stage the calculated collision velocity is kept constant (i.e., it is not adjusted according to changing particle properties during the simulation). A more detailed description of this method is also given by Rieck et al 49 in the frame of Monte Carlo modeling.…”

Forschungsarbeiten am Institut für Verfahrenstechnik der Otto‐von‐Guericke‐Universität Magdeburg

“…Das Standard‐Modell zur Auslegung von Festbettreaktoren mit Wandeffekten wurde – in Kooperation mit der Gruppe von Vortmeyer aus München und auf entsprechenden Vorarbeiten aufbauend – am Lehrstuhl entwickelt 16. Auf dem Gebiet der Wirbelschichttechnik wurden nicht nur die Standard‐Methoden zur Auslegung von Wirbelschichttrocknern entwickelt, die heute in den bekanntesten Simulationsumgebungen implementiert sind und weltweit genutzt werden, sondern u. a. auch diverse Monte‐Carlo‐Modelle für Sprühwirbelschichten, welche mitunter sogar die Agglomeration weicher Stoffe ohne Binder beschreiben können 17. Bei Granulation und Coating ermöglicht z.…”

Parameter Identification For Continuous Fluidized Bed Spray Agglomeration

“…The emerging heterogeneity significantly affects the process and thereby the overall product properties. As an alternative to Monte-Carlo modeling approaches [5][6][7] the framework of population balance modeling (PBM) [8] can be used to account for the aforementioned heterogeneity in particle formation processes such as granulation (see [9][10][11] and the references therein) or agglomeration. Detailed modeling of all involved mechanisms would results in multi-dimensional population balance equations, which are in general multi-dimensional partial integro-differential equations and thus challenging to solve numerically (see [12,13] for an example).…”