Cover Picture

Free Access

Cover Picture: Chem. Eng. Technol. 5/2020

  • Pages: 783
  • First Published: 23 April 2020
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CFD-DEM simulation of a draft plates-stabilized spouted bed in comparison to experimentally observed flow pattern. Copyright: Paul Kieckhefen

Spouted beds are common apparatuses used for coating and granulation of particles. While often classified as a special form of fluidized beds, their pneumatic characteristics differ greatly due to the presence of an unfluidized bulk in the annulus zone. The complex hydrodynamic behavior of spouted beds can be accurately described using the coupled CFD-DEM (computational fluid dynamics-discrete element method) simulation method. Individual particles are tracked through a fluid field and exchange momentum, heat, and mass with it. This image shows the result of an optimization study where the stabilizing influence of draft plates in a three-dimensional prismatic spouted is evaluated. While mixing is suppressed, the flow in the spout is much denser and leads to lower overspray rates. This may be exploited for the purpose of chemical conversion of a gaseous phase or when the injected coating liquid is very valuable.

Editorial Board

Free Access

Editorial Board: Chem. Eng. Technol. 5/2020

  • Pages: 784
  • First Published: 23 April 2020

Overview

Free Access

Overview Contents: Chem. Eng. Technol. 5/2020

  • Pages: 785
  • First Published: 23 April 2020

Highlights

Highlights: Chem. Eng. Technol. 5/2020

  • Pages: 786-787
  • First Published: 23 April 2020

Research Articles

Open Access

Characterization of Lyophilization of Frozen Bulky Solids

  • Pages: 789-796
  • First Published: 25 February 2020
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Lyomicroscopy and neutron imaging are introduced to evaluate the primary freeze-drying behavior of bulky solids. The applicability of both methods to visualize the evolution of the sublimation front is demonstrated for maltodextrin particles with different sizes and solid concentrations. Exemplary results for both methods and their suitability to study freeze-drying behavior of bulk solids are described.

Open Access

Formation of Aluminum-Doped Zinc Oxide Nanocrystals via the Benzylamine Route at Low Reaction Kinetics

  • Pages: 797-803
  • First Published: 07 February 2020
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The performance of cost-effective functional thin films using aluminum-doped zinc oxide (AZO) nanocrystals depends on the adjustability of the particle properties during synthesis. A time-resolved access for measuring the nanoscale particle properties was developed at low process speeds and used to investigate the effects of essential process parameters on the process and particle properties of AZO.

Open Access

Measurement of Residence Time Distributions in a Continuously Operated Spouted Bed

  • Pages: 804-812
  • First Published: 04 March 2020
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The residence time behavior in a continuously operated prismatic spouted bed was determined with and without insertion of separation plates between the different chambers. The shape of the residence time distribution is influenced by the separation plates, but plates with an inclined plane should be used if particle backmixing needs to be further reduced.

Open Access

Control of Particle Size and Porosity in Continuous Fluidized-Bed Layering Granulation Processes

  • Pages: 813-818
  • First Published: 07 February 2020
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Particle size and particle porosity are key product characteristics in continuous fluidized-bed layering granulation. An innovative control concept of this process with external sieve mill cycle is proposed for simultaneous automatic control of both properties in order to stabilize the process operation and achieve the desired product specifications in the presence of unforeseen disturbances.

Open Access

Modeling the Electrical Conductive Paths within All-Solid-State Battery Electrodes

  • Pages: 819-829
  • First Published: 14 February 2020
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In the context of all-solid-state batteries, a numerical method is implemented to model the electrical conductivity considering the outcome of discrete-element method simulations and based on a pathfinding algorithm. The results are calibrated and validated with experimental data of real manufactured electrodes. The ionic conductivity is also determined in view of the cathode microstructures.

Numerical Investigation of Funicular Liquid Bridge Interactions Between Spherical Particles

  • Pages: 830-837
  • First Published: 14 February 2020
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Interparticle liquid bridges play a role in unit operations such as agglomeration, granulation, coating, sintering, and drying. Validated numerical simulations were used to study funicular liquid bridges, interaction forces, and rupture conditions as functions of liquid volume, gas-liquid pressure difference, interparticle distance, and contact angle for regular three- and four-sphere arrangements.

Open Access

Comminution of Wood – Influence of Process Parameters

  • Pages: 838-847
  • First Published: 14 February 2020
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The influence of process parameters, such as moisture content and mesh width of the internal classifying screen, on the comminution process of wood in a hammer and cutting mill was investigated. The results clearly demonstrate that lower moisture content leads to a finer product. The type of mill also indicated a significant influence on the particulate properties of the comminution products.

Open Access

Verification and Validation of Spatially Averaged Models for Fluidized Gas-Particle Suspensions

  • Pages: 848-858
  • First Published: 21 February 2020
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The problem of coarse-grid simulations of gas-solid fluidized beds is investigated. Two different approaches are discussed, compared and applied to large-scale gas-solid flows. The spatially averaged two-fluid model is based on generalizing the concepts of large eddy simulation to gas-particle flows, whereas the unresolved terms were modeled by an approximate deconvolution method.

Reconstitution of Food Powders Granulated with Oil-in-Water Emulsions

  • Pages: 859-868
  • First Published: 21 February 2020
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Instant vegetable soups have been obtained by wet granulation using oil-in-water emusions as liquid binder. Three different soup formulations with different starch-to-soluble sugar ratios (SSR) have been produced. Experiments demonstrated the positive effect of the emulsion as binder and the role of SSR in eliminating the formation of lumps during the reconstitution process.

Open Access

Jet Dispersion of Multiwall Carbon Nanotubes and Correlation with Suspension Rheology

  • Pages: 869-878
  • First Published: 26 March 2020
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Dispersion and rheology of carbon nanontubes (CNTs) are investigated. A novel jet dispersion technique is proposed which enables excellent CNT dispersion by high exfoliation even at very low pressure drops. CNT suspensions are characterized and a dispersion model based on a dimensionless dispersing parameter is developed. The influence of dispersion on the rheological behavior is discussed.

Open Access

In Situ Monitoring of Particle Formation with Spectroscopic and Analytical Techniques Under Solvothermal Conditions

  • Pages: 879-886
  • First Published: 25 March 2020
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A reactor equipped with multiple and simultaneous analytical and spectroscopic techniques was designed to unravel the fundamentals of solid formation under hydro- and solvothermal conditions. An overview of the results obtained with the metal-organic framework MIL-53(Al), ZnO mesocrystals, and carbon dots is provided. This strategy paves the way for the rational design of a wide range of material systems.

Open Access

Contact Behavior of Microcrystalline Cellulose Pellets Depending on their Water Content

  • Pages: 887-895
  • First Published: 12 March 2020
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The material behavior of wet microcrystalline cellulose pellets is highly dependent on their water content. In static compression tests, the strong influence of the water content on the deformation behavior of the cylindrical extrudates and spherical pellets is experimentally investigated. Dynamic loading is studied by a setup consisting of three high-speed cameras to record the pellet-wall collisions.

Open Access

Model-Based Optimization of Ripening Processes with Feedback Modules

  • Pages: 896-903
  • First Published: 25 March 2020
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Time-dependent optimization of complex process dynamics requires efficient numerical methods, especially when feedback modules occur in the synthesis process. For this, an optimization tool based on population balance equations models, depicting the ripening processes, and on gradient information is presented and applied for different reaction dynamics and optimization goals.

Open Access

Influence of the Temperature on Coccolith-Containing Systems from Emiliania huxleyi Cultivations

  • Pages: 904-912
  • First Published: 04 March 2020
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Thermogravimetric analysis data were acquired for a coccolith-containing biogenic broth to improve subsequent separation processes of such a biogenic system. During heating, organic matter was removed from the samples. However, due to crystallinity alterations, the differences in the decomposition temperatures of the diverse compounds were considered not suitable for separation.

Multiscale Modeling of Superheated Steam Drying of Particulate Materials

  • Pages: 913-922
  • First Published: 04 March 2020
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Superheated steam drying is an economical and environmentally friendly drying technique. Herein, a packed-bed drying model that incorporates a kinetic drying model of single porous particles was developed. Both packed-bed and single-particle drying models were successfully validated by comparison with experimental data. The process parameters of solid and vapor phases were accurately predicted.

Open Access

One-Piece Stainless-Steel 3D Printed Minichannel Evaporators using Flow Boiling Carbon Dioxide

  • Pages: 923-932
  • First Published: 11 February 2020
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Stainless-steel 3D printing proved to be a promising technology for the manufacture of one-piece minichannel evaporators using flow boiling CO2 as working fluid. Such evaporators are particularly interesting for the refrigeration of surfaces exhibiting complex geometries. They are manufactured as a one-piece element and can be easily integrated in two-phase accumulator controlled loop.

Open Access

Triboelectric Charging and Separation of Fine Powder Mixtures

  • Pages: 933-941
  • First Published: 17 February 2020
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For increasingly finer powders, the material-specific separation at high loadings is a challenging task, for example, in recycling processes. The combination of triboelectric charging and electrostatic separation was investigated for powder mixtures of talcum and calcite. Although bipolar charge distributions were observed within the pure materials and mixtures, an enrichment of the materials was possible.

Effectiveness of Amine Concentration and Circulation Rate in the CO2 Removal Process

  • Pages: 942-949
  • First Published: 27 January 2020
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Amine absorption is still considered a state-of-the-art technology for gas industries. A technical analysis of gas-sweetening processes for natural gas with amine absorption has been conducted. An optimal point between amine concentration and circulation rate offers a great potential in this area for reducing the possibility of corrosion and foaming in the CO2 removal system.

Modeling of Ethylene Glycol Production from Glucose in a Semi-Continuous Reactor

  • Pages: 950-963
  • First Published: 30 January 2020
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A combined kinetic model for the conversion of glucose into ethylene glycol (EG) allows analyzing the influence of operating conditions on the reaction yields. The kinetic parameters of the hydrogenation rate laws were adjusted to the temperature range which enhances EG production. The developed numerical model was applied to evaluate glucose conversion and selectivity in a semi-batch reactor.

Open Access

Experimental Investigation of Decentralized Process Control for Reactive Dividing-Wall Columns

  • Pages: 964-973
  • First Published: 17 January 2020
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The reactive dividing-wall column is a highly integrated apparatus that permits great savings in investment costs as well as in energy consumption. A control scheme for this apparatus is proposed and experimentally tested on a pilot plant for different operation scenarios. A final comparison of simulation data of a rigorous process model with the obtained experimental data shows good agreement.

Removal of Cu2+ from Water Using Liquid-Liquid Microchannel Extraction

  • Pages: 974-982
  • First Published: 13 January 2020
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A new microchannel device was used to extraxt Cu2+ from water, by employing di-(2-ethylhexyl)phosphoric acid as extractant and kerosene as solvent. The extraction efficiency increased with increasing temperature, extractant concentration, organic/aqueous phase ratio, and pH. The volumetric mass transfer depended on the total flow rate, the phase ratio, and the pH.

Biological Water Treatment by a Hybrid Fluidized-Bed Bioreactor: Theoretical Study

  • Pages: 983-994
  • First Published: 17 January 2020
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A quantitative analysis of steady-state properties of a hybrid fluidized-bed bioreactor for water purification was performed using a mathematical model developed for a double-substrate aerobic microbiological process. The effect of essential parameters on the bioreactor performance was evaluated, including substrate concentration, aeration intensity, liquid residence time in the bioreactor, and bed height.

Effect of Surface Tension on Hydrodynamics and Mass Transfer Coefficient in Airlift Reactors

  • Pages: 995-1004
  • First Published: 17 January 2020
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The surface tension influences hydrodynamics parameters as well as the volumetric mass transfer coefficient and consequently the performance of airlift reactors. The gas-phase holdup and volumetric mass transfer coefficient correlated empirically in terms of dimensionless numbers and can be applied to evaluate these parameters for similar types of reactors.

Design and Computational Fluid Dynamics Analysis of a Three-Phase Decanter Centrifuge for Oil-Water-Solid Separation

  • Pages: 1005-1015
  • First Published: 17 January 2020
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For the separation of oil, water, and solids, the flow field and separation performances in an innovative three-phase decanter centrifuge with vertical boards and annular liquid separation plate were investigated. The application of the computational fluid dynamics software Fluent with Euler-Euler three-phase flow model provided a basis for the improvement and optimization of the centrifuge.

Communications

Open Access

Influence of the Mineral Content on the Emissivity of Hydrothermal Char

  • Pages: 1016-1020
  • First Published: 25 February 2020
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The emissivity of burning particles of synthetic char is presented. Particles in the size of 100 μm were measured in-flight with a special test rig. The results show that mineral doping with SiO2 or a mixture of SiO2 and Fe2O3 affects the char emissivity, clarifying the contributions of specific minerals to the char emissivity.

Overview

Free Access

Overview Contents: Chemie Ingenieur Technik 5/2020

  • Pages: 1021
  • First Published: 23 April 2020