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Weißandt-Gölzau, Germany

Borner M.,Otto Von Guericke University of Magdeburg | Borner M.,Robert Bosch GmbH | Hagemeier T.,Otto Von Guericke University of Magdeburg | Ganzer G.,Otto Von Guericke University of Magdeburg | And 4 more authors.
Chemical Engineering Science | Year: 2014

In fluidized bed granulation wetting and coating of particles depends on the atomization of a liquid binder agent. Droplet distribution and the subsequent micro-scale processes of droplet deposition on particle surfaces as well as drying of layers and liquid bonds between aggregated particles lead to a subdivision of the process space into two major compartments, a spray zone and a drying zone. By using a self-constructed, simple conductivity probe spray patterns inside the fluidized bed are located. The spatial demarcation of the compartments, which is dependent on the fluidization and spray conditions, is deduced. Particularly, nozzle height and nozzle gas flow rates influence the expansion of the spray zone and its intrusion into the bed. The presented results show by means of the particle residence time for the two considered compartments that an increased nozzle mass flow rate leads to significantly accelerated particle flow in the spray zone, and the fluidization velocity of the gas forces a faster particle re-circulation behavior in the entire fluidized bed. Consequently, process time for wetting and drying is reduced. By using a flat fluidized bed with rectangular cross section in combination with image-based acquisition techniques, particle velocities and solid volume fractions have been acquired. Comparing the results of particle circulation patterns with data obtained in cylindrical equipment shows that information can be transferred from the quasi-2D configuration to real 3D geometries. © 2014 Elsevier Ltd. Source


Mielke L.,Otto Von Guericke University of Magdeburg | Hoffmann T.,Otto Von Guericke University of Magdeburg | Henneberg M.,AVA Anhaltinische Verfahrens und Anlagentechnik GmbH | Peglow M.,IPT Pergande GmbH | And 2 more authors.
Chemical Engineering Research and Design | Year: 2016

Nowadays demands for product quality and energy efficiency are increasing due to ongoing industrial development and rising costs of resources. In case of fluidized bed layering granulation profitability mainly depends on the total energy input required for fluidization, evaporation of the sprayed liquid and drying, in balance with product quality and process efficiency. This paper is focuses on temporal separation of process steps like growth and liquid evaporation as one way of intensification of batch processing. In order to optimize both sub-processes, granulation and particle drying, are operated alternating by switching the spraying rate and other process parameters.In order to obtain the required data, experimental and model based investigations for different parameter configurations are performed. The analysis of results is carried out in comparison to a benchmark case, for batch operation this comparison is based either on equal process time or product quality. The results show significant advantages of temporal separation in batch processes with respect to energy consumption while conserving product quality. © 2016. Source


Dernedde M.,Otto Von Guericke University of Magdeburg | Peglow M.,IPT Pergande GmbH | Tsotsas E.,Otto Von Guericke University of Magdeburg
Drying Technology | Year: 2013

The present study describes the theoretical modeling of particle formation by agglomeration in fluidized beds. The model is mathematically solved by applying a stochastic Monte Carlo method. It takes into account the complete droplet history (predrying during flight, spreading, solidification and penetration after deposition on a particle) so that thermal effects such as the increase in fluidization gas mass flow or gas temperature have a physically based impact on process kinetics. Contradictions between measured and simulated particle moisture contents were found. Thus, we present a modified drying model and compare results with experimental data. © 2013 Copyright Taylor and Francis Group, LLC. Source


Rieck C.,Otto Von Guericke University of Magdeburg | Hoffmann T.,Otto Von Guericke University of Magdeburg | Buck A.,Otto Von Guericke University of Magdeburg | Peglow M.,IPT Pergande GmbH | Tsotsas E.,Otto Von Guericke University of Magdeburg
Powder Technology | Year: 2015

Particle coating experiments were performed in a lab-scale fluidized bed with varying process parameters, such as spraying rate and air inlet temperature, leading to different drying conditions. Porous (γ-Al2O3) and non-porous (glass) initial particles were sprayed with a sodium benzoate solution. For each experiment, the particle size distribution as well as the layer porosity was measured. The results show a dependency of the layer porosity on the drying conditions, represented by the drying potential of the fluidization gas. The obtained relationship is expressed as a linear correlation, which can be used in process models. Apart from the experimental results, a model based on population balances and heat and mass balances is presented. Simulations performed using the obtained empirical correlation are in good agreement with experimental data. © 2014 Elsevier B.V. Source


Hoffmann T.,Otto Von Guericke University of Magdeburg | Rieck C.,Otto Von Guericke University of Magdeburg | Schmidt M.,Otto Von Guericke University of Magdeburg | Buck A.,Otto Von Guericke University of Magdeburg | And 2 more authors.
Drying Technology | Year: 2015

In this work, experimental results for a continuous fluidized bed spray layering process are used to identify product quality influencing process parameters, such as the shell porosity. The prediction of the shell porosity is based on an empirical relation established for fluidized bed layering in batch mode. It uses gas-side properties, which are represented by the drying potential of the gas. It is shown that the shell porosities forming in the continuous mode can be deduced from this relation by comparing experimental data and simulation results. Process stability and seed formation are also discussed using the obtained experimental data. © 2015, Copyright © Taylor & Francis Group, LLC. Source

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