10 results
Now showing1 - 10 of 10
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Dynamics of spray granulation in continuously operated horizontal fluidized beds(Springer, 2020-06-21); ; ; ; This chapter presents new findings on process and product design in continuous spray layering granulation in horizontal fluidized beds. The results are achieved by a multi-scale approach, combining single-particle characterization of the influence of drying conditions on layer formation and properties with meso-scale information of particle flowand recirculation between process chambers separated by weirs. On the macro-scale, population balance modeling is used to describe the overall process dynamics taking into account apparatus design and process conditions. New process regime maps are presented along with control concepts to guarantee stable and safe operation as well as desired particle properties.Publicationtype: Book Part124 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Particle dynamics in a multi-staged fluidized bed: Particle transport behavior on micro-scale by discrete particle modelling(2019-10); ; ; ; This work studies the particle exchange rates in horizontal fluidized beds equipped with different weir designs between compartments. These particle exchange rates provide information on the axial dispersion of the solid material within the process. For this purpose discrete particle modelling (DPM) was used to determine the particle exchange on microscopic level. This method uses a coupled CFD-DEM approach to observe particle dynamics in a fluid field. The model was validated against exchange rates in a lab-scale setup as determined by Particle Tracking Velocimetry (PTV) with very good quantitative agreement, showing the suitability of the method for the evaluation of weir designs. Simulations were performed for different weir designs and under variation of the hold-up mass, the feed rate and gas velocity to predict their transport behavior in a pilot-scale 3D horizontal fluidized bed. The results indicate that the solids transport behavior is strongly dependent on the used weir design and the main driving force for the particle transport that can be influenced by the process conditions. The installation of weirs between two compartments induces a transport resistance, while the base type without the installation of a weir between the two chambers represents the fastest possibility for mixing the particles of a two-compartment system. It has been observed that the general trend shows higher particle recirculation rates for the overflow weir and base configuration (no weir), whereas the underflow and sideflow weir applications improve the solids transport through the horizontal fluidized bed.Publicationtype: Journal Article75 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , On the dynamics and control of continuous fluidized bed layering granulation with screen-mill-cycle(Elsevier, 2019-05-22); ; ; ; This paper is concerned with an experimental and theoretical study of dynamics and control of fluidized bed layering granulation with external screen mill cycle. To achieve quantitative agreement between model calculations and experiments an extended dynamic process model is proposed. In contrast to previous work by Dreyschultze et al. [1] specific plant characteristics are taken explicitly into account including a more detailed model of the milling process and a classifying particle withdrawal from the granulation chamber. The model is then used to develop new control strategies. First, a novel bed mass controller is designed and validated. Afterward, a second control loop is introduced to dampen the oscillatory behavior of the particle size distribution. It is shown that the new control concepts achieve stable steady-state operation within a short time and thereby improve the process dynamics significantly. Theoretical predictions and experimental results are shown to be in good agreement.Publicationtype: Journal ArticleScopus© Citations 24 272 340 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Investigation of the Dynamic Behaviour of the Spray Granulation in Continuously Operated Horizontal Fluidised BedsPublicationtype: Conference Paper14 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Tailor-Made Particles by Fluidized and Spouted Bed Spray Granulation: Opportunities and Recent Advancements(Curran Associates, Inc., 2019-05); ; ; Publicationtype: Conference Paper39 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Influence of process conditions on the product properties in a continuous fluidized bed spray granulation process(2018-11); ; ; ; This work focuses on continuously operated spray granulation processes in horizontal fluidized beds highlighting the influence of process conditions on the particle properties of the resulting product granules. The drying process has a decisive influence on the kinetics of the growth rate and thus also on the properties of the particles, such as the morphological structure, particle moisture content and porosity as well as density, compression strength and the wetting behavior. This influence has been considered in this study in more detail on the basis of the model material sodium benzoate. In order to compare the produced granules at different drying conditions and spray rates of the suspension an external product classification was used to achieve a certain product granule size. The obtained experimental results show a deep influence of the thermal conditions onto granule morphology and structural properties, which is in qualitative agreement with recent experimental observations (Rieck et al., 2015; Hoffmann et al., 2015a; Schmidt et al., 2017b). The overall trend of the results reveal smoother product granules with decreasing spray rates of the suspension and increasing drying temperatures. These smoother surface morphologies lead to a more homogeneous layering which has as a consequence that the internal particle porosity is decreasing while the solids density and the compression strength of the particles are increasing at the same time. In this study the purely qualitative classification of the surface texture from previous experimental studies was extended by the topographic analysis of the product granules, giving the possibility to quantify the morphological structure by means of roughness measurements. This makes the morphological design accessible as product property and permits the utilization of models that describe the morphology according to the process conditions.Publicationtype: Journal Article142 - Some of the metrics are blocked by yourconsent settings
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 , Untersuchung des dynamischen Verhaltens der Sprühgranulation in kontinuierlich betriebenen Wirbelschichtrinnen(Wiley-VCH, 2016-08-29); ; ; ; Publicationtype: Journal Article188 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Influence of mill characteristics on stability of continuous layering granulation with external product classification(Elsevier, 2016-06-25); ; ; ; Dynamic stability of continuous fluidized bed spray granulation processes with sieve mill cycle is analyzed. For this purpose a black box model of the mill was identified from experimental data. In the range of interest, the data show a trimodal particle size distribution, which strongly depends on the power input to the mill but hardly on the mass flow through the mill. Stability maps are generated from the new mill model in combination with a two zone model of the granulation chamber and the effect of the most important process parameters on process stability is discussed.Publicationtype: Conference Paper127 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Influence of operation parameters on process stability in continuous fluidised bed layering with external product classification(Elsevier, 2016-04-02); ; ; ; Several studies—theoretical and experimental—show that continuous fluidised bed layering granulation with external classification can show instability in the form of self-sustained oscillations. Recent results show that the process stability does not only depend on product-related process parameters but also on the formation of functional zones in the fluidised bed chamber, especially the formation of a spray and drying zone. In this work a systematic evaluation of zone formation in different apparatus designs (e.g., top- and bottom-spray in cylindrical apparatuses) and its influence on process stability is performed, resulting in a stability regime map for the different apparatus designs and key operation parameters.Publicationtype: Journal Article159