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Weimar, Germany

Zarekar S.,Otto Von Guericke University of Magdeburg | Buck A.,Otto Von Guericke University of Magdeburg | Jacob M.,Glatt Ingenieurtechnik GmbH | Tsotsas E.,Otto Von Guericke University of Magdeburg
Powder Technology | Year: 2016

Fluidized beds operated at sub-atmospheric pressure can be employed for granulation and drying of thermo-sensitive materials in the food and pharmaceutical industries. However, the hydrodynamics of vacuum fluidized beds has not been extensively investigated. Some authors argue that at low pressures, the slip flow of gas is the major factor influencing the hydrodynamic behavior. The influence of change in gas properties on the hydrodynamics due to reduction in pressure has not been clearly distinguished. In this contribution, the individual effects of gas properties and slip flow on the hydrodynamic behavior, particularly on the minimum fluidization velocity, of vacuum fluidized beds are quantified. This has been achieved by expanding the classical minimum fluidization velocity correlation, valid under atmospheric pressure, to include the slip flow term. The results obtained describe a critical Knudsen number which indicates when the slip term begins to significantly influence the flow behavior. The derived correlation is compared with correlations reported in literature as well as validated with experimental data. © 2015 Elsevier B.V. Source

Mueller S.B.,Ludwig Maximilians University of Munich | Kueppers U.,Ludwig Maximilians University of Munich | Ayris P.M.,Ludwig Maximilians University of Munich | Jacob M.,Glatt Ingenieurtechnik GmbH | Dingwell D.B.,Ludwig Maximilians University of Munich
Earth and Planetary Science Letters | Year: 2016

Explosive volcanic eruptions can release vast quantities of pyroclastic material into Earth's atmosphere, including volcanic ash, particles with diameters less than two millimeters. Ash particles can cluster together to form aggregates, in some cases reaching up to several centimeters in size. Aggregation alters ash transport and settling behavior compared to un-aggregated particles, influencing ash distribution and deposit stratigraphy. Accretionary lapilli, the most commonly preserved type of aggregates within the geologic record, can exhibit complex internal stratigraphy. The processes involved in the formation and preservation of these aggregates remain poorly constrained quantitatively. In this study, we simulate the variable gas-particle flow conditions which may be encountered within eruption plumes and pyroclastic density currents via laboratory experiments using the ProCell Lab System® of Glatt Ingenieurtechnik GmbH. In this apparatus, solid particles are set into motion in a fluidized bed over a range of well-controlled boundary conditions (particle concentration, air flow rate, gas temperature, humidity, liquid composition). Experiments were conducted with soda-lime glass beads and natural volcanic ash particles under a range of experimental conditions. Both glass beads and volcanic ash exhibited the capacity for aggregation, but stable aggregates could only be produced when materials were coated with high but volcanically-relevant concentrations of NaCl. The growth and structure of aggregates was dependent on the initial granulometry, while the rate of aggregate formation increased exponentially with increasing relative humidity (12-45% RH), before overwetting promoted mud droplet formation. Notably, by use of a broad granulometry, we generated spherical, internally structured aggregates similar to some accretionary pellets found in volcanic deposits. Adaptation of a powder-technology model offers an explanation for the origin of natural accretionary pellets, suggesting them to be the result of a particular granulometry and fast-acting selective aggregation processes. For such aggregates to survive deposition and be preserved in the deposits of eruption plumes and pyroclastic density currents likely requires a significant pre-existing salt load on ash surfaces, and rapid aggregate drying prior to deposition or interaction with a more energetic environment. Our results carry clear benefits for future efforts to parameterize models of ash transport and deposition in the field. © 2015 The Authors. Source

Stresing A.,Otto Von Guericke University of Magdeburg | Morl L.,Otto Von Guericke University of Magdeburg | Khaidurova A.,Otto Von Guericke University of Magdeburg | Jacob M.,Glatt Ingenieurtechnik GmbH | Walther K.,EMA TEC GmbH
Chemie-Ingenieur-Technik | Year: 2013

A new contactless method for supplying energy to a fluidized bed is presented. An electromagnetic field supplies power to electro conductive inert particles. This technique is characterized by high energy densities and fast heating rates as well as high efficiency. It is essential in the metal processing industry. The experimental results show that the advantages of inductive heating can also be used for fluidized bed applications. The key aspect here is the determination of the time response and its parameters. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Boerefijn R.,PURAC Biochem B.v. | Orlovic M.,PURAC Biochem B.v. | Reimers C.,SolidSim Engineering GmbH | Pogodda M.,SolidSim Engineering GmbH | Jacob M.,Glatt Ingenieurtechnik GmbH
Chemical Engineering Science | Year: 2013

The present work describes the study of a continuous fluidized bed granulation process involving a solution spray as binder. The study entails the employment of a flux number as an extension to an existing flowsheet model (SolidSim). The agglomeration kernel used here is based on the Equi-Kinetic Energy principle and has been derived and proven for fluidized bed granulation processes using reactive and melt binders, but not for solution binders. This kernel has been correlated in the past to the flux number, which contains the main characteristics of the fluidized solids and the spray-on, such as the binder flux, the particle density and the fluidization gas velocity, in combination with population balances. This correlation was derived for a few liquid/solids systems only, notably small scale batch processes with melt binders, and a first attempt to the generalization of this correlation is shown here by its application to a completely different system, notably a continuous large pilot using a solution binder. The validated SolidSim flowsheet is useful for parameter variations and sensitivity analyses, showing a strong effect of the flux number exponent and the cut size of the screen on the product size distribution and recycle rate. Such quantitative relations between process conditions and product quality allow for significant savings in cost and time for process and product development and optimization. © 2012 Elsevier Ltd. Source

Neuwirth J.,TU Hamburg - Harburg | Antonyuk S.,TU Hamburg - Harburg | Heinrich S.,TU Hamburg - Harburg | Jacob M.,Glatt Ingenieurtechnik GmbH
Chemical Engineering Science | Year: 2013

In this work, the fluid and particle dynamics in a rotor granulator system (fluid bed rotor processor) are investigated. The mathematical model is based on a three-dimensional Computational Fluid Dynamics (CFD) approach for the gas phase coupled with a Discrete Element Method (DEM). The physical properties and collision behaviour of test particles are investigated experimentally and incorporated in a viscoelastic particle contact model. The influence of several process parameters, e.g. air gap velocity and rotor speed, on the particle motion and collision behaviour is investigated. In order to check applicability and limitations of the simulation model, a novel non-intrusive Magnetic Particle Tracking (MPT) technique was used for the continuous measurement of the particle position and orientation of a single tracer particle. Thus particle trajectories as well as translational and angular velocities are obtained. The simulation model shows a good agreement with the experimental results. © 2012 Elsevier Ltd. Source

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