Characterization of the pneumatic behavior of a novel spouted bed apparatus

Recently the importance of spouted bed technology has significantly increased in the context of drying processes as well as granulation, agglomeration or coating processes. Particulate systems concerning very fine or non spherical particles that are difficult to fluidize, often cannot be treated in conventional fluidized beds. In contrast to those fluidized beds, the spouted bed technology with its specific flow structure offers the opportunity of stable fluidization under controlled conditions. Within this work the fluid dynamics of a novel spouted bed with two adjustable gas inlets is investigated. By analysis of gas fluctuation spectra by means of a fast Fourier transformation algorithm, different operation regimes are identified and depicted graphically. Furthermore, continuum CFD-modeling of the granular solid phase motion by means of an Euler/Euler approach and comparisons with experimental obtained velocity vector fields by means of particle image velocimetry (PIV) measurements will be presented in this work

Discrete element modeling and fibre optical measurements for fluidized bed spray granulation

Spout fluidized beds are frequently used for the production of granules or\ud particles through granulation. The products find application in a large variety of\ud applications, for example detergents, fertilizers, pharmaceuticals and food. Spout fluidized\ud beds have a number of advantageous properties, such as a high mobility of the particles,\ud which prevents undesired agglomeration and yields excellent heat transfer properties. The\ud particle growth mechanism in a spout fluidized bed as function of particle-droplet\ud interaction has a profound influence on the particle morphology and thus on the product\ud quality. Nevertheless, little is known about the details of the granulation process. This is\ud mainly due to the fact that the granulation process is not visually accessible. In this work\ud we use fundamental, deterministic models to enable the detailed investigation of\ud granulation behaviour in a spout fluidized bed. A discrete element model is used\ud describing the dynamics of the continuous gas-phase and the discrete droplets and\ud particles. For each element momentum balances are solved. The momentum transfer\ud among each of the three phases is described in detail at the level of individual elements.\ud The results from the discrete element model simulations are compared with local\ud measurements of particle volume fractions as well as particle velocities by using a novel\ud fibre optical probe in a fluidized bed of 400 mm I.D. Simulations and experiments were\ud carried out for two different cases using Geldart B type aluminium oxide particles: a\ud freely bubbling fluidized bed and a spout fluidized bed with the presence of droplets. It is\ud demonstrated how the discrete element model can be used to obtain information about the\ud interaction of the discrete phases, i.e. the growth zone in a spout fluidized bed. Eventually\ud this kind of information can be used to obtain closure information required in more coarse\ud grained model

3-D-Bewegungsorganisation der lumbalen Wirbelsäure beim Heben

Wirbelsäulenbewegungen bei alltäglichen Bewegungen sind nicht hinreichend untersucht. In dieser Arbeit wurden mittels einer Hautmarkermethode unter Verwendung infrarotlicht-basierendem Motion-Capturing Bewegungen der Lendenwirbelsäule von 11 Versuchs-personen gemessen. Die Hautmarkermethode wurde mittels offenem MRT validiert. Die erhaltenen Koordinaten wurden zu 3-D-Winkeln (Cardan-Winkel) transformiert. Es konnten innerhalb der Probandengruppe unterschiedliche Bewegungsmuster der Lendenwirbelsäule bei Benutzung unterschiedlicher Hebetechniken festgestellt werden (Knieheber vs. Rücken-heber). Schlussfolgernd kann ausgesagt werden, dass das lumbale Bewegungsmuster der hier klassifizierten Knieheber eine Möglichkeit zur Belastungsreduktion der Lendenwirbelsäule ist

Comparison of fibre optical measurements and discrete element simulations for the study of granulation in a spout fluidized bed

Spout fluidized beds are frequently used for the production of granules or particles through granulation. The products find application in a large variety of applications, for example detergents, fertilizers, pharmaceuticals and food. Spout fluidized beds have a number of advantageous properties, such as a high mobility of the particles, which prevents undesired agglomeration and yields excellent heat transfer properties. The particle growth mechanism in a spout fluidized bed as function of particle-droplet interaction has a profound influence on the particle morphology and thus on the product quality. Nevertheless, little is known about the details of the granulation process. This is mainly due to the fact that the granulation process is not visually accessible. In this work we use fundamental, deterministic models to enable the detailed investigation of granulation behaviour in a spout fluidized bed. A discrete element model is used describing the dynamics of the continuous gas-phase and the discrete droplets and particles. For each element momentum balances are solved. The momentum transfer among each of the three phases is described in detail at the level of individual elements. The results from the discrete element model simulations are compared with local measurements of particle volume fractions as well as particle velocities by using a novel fibre optical probe in a fluidized bed of 400 mm I.D. Simulations and experiments were carried out for three different cases using Geldart B type aluminium oxide particles: a freely bubbling fluidized bed; a spout fluidized bed without the presence of droplets and a spout fluidized bed with the presence of droplets. It is demonstrated how the discrete element model can be used to obtain information about the interaction of the discrete phases, i.e. the growth zone in a spout fluidized bed. Eventually this kind of information can be used to obtain closure information required in more coarse grained models

Unusual evolution of a catalytic core element in CCA-adding enzymes

CCA-adding enzymes are polymerases existing in two distinct enzyme classes that both synthesize the C-C-A triplet at tRNA 3′-ends. Class II enzymes (found in bacteria and eukaryotes) carry a flexible loop in their catalytic core required for switching the specificity of the nucleotide binding pocket from CTP- to ATP-recognition. Despite this important function, the loop sequence varies strongly between individual class II CCA-adding enzymes. To investigate whether this loop operates as a discrete functional entity or whether it depends on the sequence context of the enzyme, we introduced reciprocal loop replacements in several enzymes. Surprisingly, many of these replacements are incompatible with enzymatic activity and inhibit ATP-incorporation. A phylogenetic analysis revealed the existence of conserved loop families. Loop replacements within families did not interfere with enzymatic activity, indicating that the loop function depends on a sequence context specific for individual enzyme families. Accordingly, modeling experiments suggest specific interactions of loop positions with important elements of the protein, forming a lever-like structure. Hence, although being part of the enzyme’s catalytic core, the loop region follows an extraordinary evolutionary path, independent of other highly conserved catalytic core elements, but depending on specific sequence features in the context of the individual enzymes

European Drying Conference -EuroDrying

Abstract: The fluidized bed extraction using superheated steam can be used for the production of volatile ingredients (essential oils) from plant materials. Depending on its properties the plant material must be pretreated. Some experimental investigations of this process and their results are presented. A simple model to describe and calculate the oil release from the plant material and the oil concentration in the steam is also represented

Core–shell catalyst pellets for effective reaction heat management

Catalyst research is concerned with synthesizing increasingly active materials, leading to safety issues at reactor scale, unless the reaction heat release is controllable. Computational studies predict that core–shell pellets with catalytically active core and inert shell are beneficial for this purpose, compared to established concepts such as catalyst pellet dilution. At high temperatures, reactant diffusion through the shell becomes rate-determining, resulting in a well-controllable heat release rate, which prevents further temperature increase. Here, industrial catalyst pellets were coated in a fluidized-bed pilot plant, demonstrating large-scale production feasibility. The obtained pellets were characterized via Dynamic Image Analysis, Scanning Electron Microscopy and X-ray Computed Tomography. Conducted CO2 methanation experiments confirm the predicted trends, if the applied shell is fully closed. Furthermore, mathematical and experimental studies demonstrate, that the inert shell shifts selectivity. Based on this work, safer and yet economical reactor operation is anticipated also for other reaction systems

Investigation of 3D particle flow in a flighted rotating drum

[EN] o validate the particle motion in flighted rotating drum (FRD), a laboratory FRD was built and operated at 15% filling degree and 10 rpm rotation speed using plastic balls as bed material. The particle tracking velocimetry (PTV) and magnetic particle tracking (MPT) techniques were applied to investigate the particle flow behavior. The 3D particle flow was modeled by Discrete Element Method (DEM) with LIGGGHTS. The height of the barycenter of all overall particles and particle instantaneous velocity were calculated from PTV and DEM data. The 3D time-averaged particle velocity distributions obtained from MPT experiment and DEM simulation were compared.Zhang, L.; Weigler, F.; Jiang, Z.; Idakiev, V.; Mörl, L.; Mellmann, J.; Tsotsas, E. (2018). Investigation of 3D particle flow in a flighted rotating drum. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 253-260. https://doi.org/10.4995/IDS2018.2018.7389OCS25326