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Item type:Publication, Access status: without files , Investigation of the granulation process in a multi-staged continuous fluidized bed: Influence of the process conditions on the product properties(2017-05); ; ; ; This work focuses on the particle properties of sodium benzoate granules, which are produced by fluidized bed spray granulation during different process conditions. The drying process has a decisive influence on the kinetics of the growth rate and thus also on the properties of the particles, like the morphological structure, particle moisture and porosity. This influence has been considered in this project in more detail. In order to compare the produced granules while varying the drying conditions an external product classification is used to achieve a certain product size. The results show that the drying conditions significantly affect the granule morphology and structural properties. Hence, higher spray rates of the suspension and lower drying temperatures lead to higher jaggedness of the product particles.Publicationtype: Conference Paper90 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , CFD-DEM modeling of particle coating in a prismatic spouted bed and improvement of spouting stabilityIn this contribution coupled CFD-DEM simulations of a three-dimensional prismatic spouted bed for coating purposes were performed. The simulations were validated by means of pressure drop fluctuations and flow pattern with respect to experimental data. In order to increase the spouting stability, draft plates were inserted into the process chamber. To investigate the influence of flow stability on coating quality, droplets were injected in a post-processing step and deposited on colliding particle parcels. By means of that tool the time-dependent cumulative distribution function of the particle liquid loading was calculated and compared for different process configurations.Publicationtype: Conference Paper127 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Capacitance probes for the investigation of the fluid dynamics of turbulent fluidized bedsAn investigation of the turbulent fluidized bed regime was carried out using Group B particles according to Geldart's classification. The experimental plant was a CFB pilot-scale cold model (diameter: 0.4 m, height: 15.6 m). As bed material quartz sand (Sauter Mean the fluidized bed riser probe measurements were carried out at heights between 1.5 m and 8.34 m above the air distributor. A detailed validation of capacitance probe measurements in a fluidized bed system has been done by comparison with suction probe and pressure drop measurements. The gas velocity was varied in a range between 2 and 4 m/s. Results show a good agreement of solids concentrations measured by capacitance probe and pressure measurements. A typical core-annulus flow structure was observed. The results of the local solids circulation rate determined by capacitance probe were found to be different from suction probe measurements.Publicationtype: Conference Paper149 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Reaction kinetics for flowsheet modeling of chemical looping combustion in fluidized bed reactors(2017-05); ; ; ; Werther, JoachimChemical Looping Combustion (CLC) is an alternative combustion process for the separation of carbon dioxide during the conversion of fuels. The process itself may be carried out in a system of interconnected fluidized bed reactors with a solid oxygen carrying material is circulated between them. CLC reaction kinetics differ sharply from regular air-fired combustion in terms of gas concentrations inside the two reactors and that the oxygen is transported between those reactors by a solid oxygen carrier. Further, they are strongly dependent on the hydrodynamics inside the fluidized bed reactors. For a predictive simulation of CLC, reaction kinetics of the oxygen carrier's reduction and oxidation, as well the conversion of solid fuels has to be known. To keep complexity low, overall reactions schemes are mostly used to describe chemical reactions. Various research groups measured the reactivity of the oxygen carrier with TGA, neglecting the effects of fluidization on the chemical conversion. In this work, the lab scale bubbling bed facility (diameter = 53mm) at Hamburg University of Technology was used for experiments on the behavior of copper oxide carriers on the basis of Al2O3. The conversion behavior was modeled with solid reaction models proposed in the literature and checked which one fits best to the experimental data from the plant. Additionally, the solid fuel lignite was investigated with regard to the conversion behavior under CLC conditions inside the lab scale fluidized bed. The oxygen carrier's gas-phase reactions are hard to capture with the typical Arrhenius type reaction rates inside the fluidized bed reactor. It is shown that several competing reactions take place, which does not lead to steadily increasing reaction rates with higher temperatures. Devolatilization of lignite is fast compared to its gasification. The gasification of lignite could be tracked over a broad temperature and particle size spectrum and modeled with particle reaction models and Arrhenius type reaction rates.Publicationtype: Conference Paper82 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Coating of fine Aerogel particles using spouted bed technologyAerogels are porous and light-weighting materials with high inner surface area. Their properties enable to use them in many fields, e.g. as acoustic and thermal insulation materials, catalyst, adsorber or drug carriers. However, open pore structure does not allow their application in different areas because of change of the structure caused by liquid-contact. Therefore there is a protective layer on their surface needed, which provides new fields of application, e.g. in food products. In this work coating of the protein-based aerogel microspheres (dP < 100 μm) with shellac using spouted bed technology was performed. This method enables applying of dense, uniform and thin coating layer on fine particles. To improve the uniformity of the coating layer the specific surface area before and after the coating procedure was measured and showed clear decrease after longest coating time. To investigate the behavior ofaerogels in water containing medias the particles were exposed to water drops using sessile drop protocol. The coating protects the aerogel particles from water influence.Publicationtype: Conference Paper168 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Using a spouted bed spray granulation process to study the influence of aspect ratio on fracture toughness in composites(2017-05); ; ; In this work the fracture toughness of copper-composite materials was studied. The volume fraction of copper was between 69 and 76 %. The study was carried out with two types of composites. The first type were composites containing spherical copper particles. The second type were composites with copper particles, which were rolled before they were pressed to a bulk material. The analysis of fracture toughness shows, that the composites with spherical particles have a mean fracture toughness of 1.69 MPam 1/2 . The composites with higher aspect ratios of particles have a fracture toughness of 2.66 MPam 1/2 . It corresponds to an increasing of approximatively 55 % for the toughness referred to composites with spherical particles.Publicationtype: Conference Paper88