Preparation, structure and properties of new ternary chalcogenides and germanides of the metals from the first transition series, Cr, Mn, Fe and Ni

This thesis deals with the synthesis, structure determination and investigation of the properties of Cr₂Ge₂Se₆, Mn₂GeSe₄, Fe₃GeTe₂ and Ni₃GeTe₂.<br /> Mn₂GeSe₄ crystallizes in the orthorhombic space group Pnma (a=1335,0(3) pm, b = 776,5(2) pm, c = 630,7(1) pm) is one of the rare ternary transition metal selenides representatives of the olivine ((Fe, Mg)₂SiO₄) structure – type.<br /> Fe₃GeTe₂ and Ni₃GeTe₂ are the first ternary members of the filled NiAs – structures. Both crystallize in the hexagonal group P6₃/mmc (a = b = 399,1(1) pm, c=1633,6(3) pm for Fe₃GeTe₂ and a = b = 319,1(1) pm, c=1602,2(3) pm for Ni₃GeTe₂, respectively). Their structures are characterized by alternating layer packages, each one built of five layers.<br /> Cr₂Ge₂Se₆ is a new compound belonging to the the M₂X₂Y₆ (M = transition metal, X = Si, Ge, Y = chalcogen) structure family. X – ray powder diffraction investigations find a hexagonal symmetry. The lattice constants are a = b = 629,3(3) pm, c = 1942,1(6) pm, &#947; = 120°.<br /> Magnetic properties studies show antiferromagnetic interactions in Mn₂GeSe₄ and ferromagnetic spin ordering in Fe₃GeTe₂. Ni₃GeTe₂ exhibits weak paramagnetism.Die vorliegende Arbeit befasst sich mit dem Synthese, der Strukturchemie und der Eigenschaften von Cr₂Ge₂Se₆, Mn₂GeSe₄, Fe₃GeTe₂ and Ni₃GeTe₂.<br /> Mn₂GeSe₄ ist eines der selten ternären Übergangsmetallselenide aus der Olivin Struktur Typ, kristallisiert in der orthorhombische Raumgruppe Pnma (a=1335,0(3) pm, b = 776,5(2) pm, c = 630,7(1) pm).<br /> Fe₃GeTe₂ and Ni₃GeTe₂ sind die erste ternäre Verbindungen von ausgefüllte NiAs – Strukturen. Beide kristallisieren in der hexagonale Raumgruppe P6₃/mmc (a = b = 399,1(1) pm, c=1633,6(3) pm für Fe₃GeTe₂ und a = b = 319,1(1) pm, c=1602,2(3) pm für Ni₃GeTe₂). Die Struktur belegte aus Schichtpaketen. Jeder Schichtpaket ist von fünf Schichten ausgebaut. Cr₂Ge₂Se₆ ist eine neue Verbindung der M₂X₂Y₆ Strukturtyp (M = Übergangsmetall, X = Si, Ge, Y = Chalcogen). Nach Röntgenpulverdaten kristallisiert hexagonal mit den Gitterkonstanten a = b = 629,3(3) pm, c = 1942,1(6) pm, &#947; = 120°.<br /> Die Untersuchung an magnetische Eigenschaften obengenante Verbindungen weisen antiferromagnetische Wechselwirkung bei Mn₂GeSe₄ und ferromagnetiche Spin–Orientierung in Fe₃GeTe₂. Bei Ni₃GeTe₂ ist schwaches Paramagnetismus zu beobachten

Oszillierende Verbrennung als Primärmaßnahme zur Stickoxidminderung in Rostfeuerungen

Derzeit werden von Biomassefeuerungsanlagen ca. 40 000 t Stickoxide (NOx) pro Jahr emittiert. NOx ist so wie CO2 klimawirksam. Diese Menge entspricht einem CO2-Äquivalent von 400 000 t pro Jahr. Die Grenzwerte für NOx Emissionen werden stetig verschärft. Ohne technische Innovation ist es nur mit einem größeren wirtschaftlichen Aufwand möglich, die neuen Grenzwerte (z. B. nach der Technischen Anleitung Luft (TA Luft)) von 400 mg/m³ (bezogen auf einen Volumengehalt an Sauerstoff im Abgas von 11 %. [1]) Diese Veröffentlichung präsentiert eine technische Primärmaßnahme zur NOx Minimierung, die auf einer oszillierenden Verbrennungsluftzufuhr basiert. Eine Primärmaßnahme ist im Vergleich zu einer Sekundärmaßnahme ökologisch und ökonomisch attraktiver, da sie unmittelbar in den Verbrennungsprozess eingreift. Das Verfahren ist kostengünstig realisierbar und verspricht einen Kostenvorteil von rund 50 % im Vergleich zu konventionellen Verfahren. Zugleich wird durch den entfallenden Stoff- und Energieaufwand in der Sekundärmaßnahme die Energieeffizienz des Gesamtverfahrens verbessert

Two- and Three-Dimensional Benchmarks for Particle Detection from an Industrial Rotary Kiln Combustion Chamber Based on Light-Field-Camera Recording

This paper describes a benchmark dataset for the detection of fuel particles in 2D and 3D image data in a rotary kiln combustion chamber. The specific challenges of detecting the small particles under demanding environmental conditions allows for the performance of existing and new particle detection techniques to be evaluated. The data set includes a classification of burning and non-burning particles, which can be in the air but also on the rotary kiln wall. The light-field camera used for data generation offers the potential to develop and objectively evaluate new advanced particle detection methods due to the additional 3D information. Besides explanations of the data set and the contained ground truth, an evaluation procedure of the particle detection based on the ground truth and results for an own particle detection procedure for the data set are presented

Hybrid Models for Efficient Control, Optimization, and Monitoring of Thermo-Chemical Processes and Plants

This paper describes a procedure and an IT product that combine numerical models, expert knowledge, and data-based models through artificial intelligence (AI)-based hybrid models to enable the integrated control, optimization, and monitoring of processes and plants. The working principle of the hybrid model is demonstrated by NOx reduction through guided oscillating combustion at the pulverized fuel boiler pilot incineration plant at the Institute for Technical Chemistry, Karlsruhe Institute of Technology. The presented example refers to coal firing, but the approach can be easily applied to any other type of nitrogen-containing solid fuel. The need for a reduction in operation and maintenance costs for biomass-fired plants is huge, especially in the frame of emission reductions and, in the case of Germany, the potential loss of funding as a result of the Renewable Energy Law (Erneuerbare-Energien-Gesetz) for plants older than 20 years. Other social aspects, such as the departure of experienced personnel may be another reason for the increasing demand for data mining and the use of artificial intelligence (AI)

3D Refuse-derived Fuel Particle Tracking-by-Detection Using a Plenoptic Camera System

Multiple particle tracking-by-detection is a widely investigated issue in image processing. The paper presents approaches to detecting and tracking various refuse-derived fuel particles in a industrial environment using a plenoptic camera system, which is able to yield 2D gray value information and 3D point clouds with noticeable fluctuations. The presented approaches, including an innovative combined detection method and a post-processing framework for multiple particle tracking, aim at making the most of the acquired 2D and 3D information to deal with the fluctuations of the measuring system. The proposed novel detection method fuses the captured 2D gray value information and 3D point clouds, which is superior to applying single information. Subsequently, the particles are tracked by the linear Kalman filter and 2.5D global nearest neighbor (GNN) and joint probabilistic data association (JPDA) approach, respectively. As a result of several inaccurate detection results caused by the measuring system, the initial tracking results contain faulty and incomplete tracklets that entail a post-processing process. The developed post-processing approach based merely on particle motion similarity benefits a precise tracking performance by eliminating faulty tracklets, deleting outliers, connecting tracklets, and fusing trajectories. The proposed approaches are quantitatively assessed with manuelly labeled ground truth datasets to prove their availability and adequacy as well. The presented combined detection method provides the highest F 1 -score, and the proposed post-processing framework enhances the tracking performance significantly with regard to several recommended evaluation indices

Analyse des Flug- und Abbrandverhaltens von Ersatzbrennstoffen auf Basis eines Lichtfeldkamerasystems

Heutzutage finden die aus Abfällen gewonnenen Brennstoffe eine zunehmende Verwendung bei industriellen Verbrennungsprozessen, wie beispielsweise zur Erzeugung von Wärme bei der Verbrennung in Zement Drehrohröfen. Um eine kontrollierbare und sichere Verbrennung dieses alternativen Brennstoffs zu gewährleisten, ist eine Analyse des Flug- und Verbrennungsverhaltens unerlässlich. In diesem Beitrag stellen wir Methoden zur Analyse von Bilddaten vor, die von einer Lichtfeldkamera während der Verbrennung von den aus Abfällen gewonnenen Brennstoffen in einem Drehrohr aufgenommen wurden. Das Kamerasystem liefert 3D-Informationen sowohl zu den Brennstoffpartikeln als auch zur inneren Form des Drehrohrofens. Die Analyse beinhaltet Verfahren zur Partikeldetektion unter Verwendung von 3D-Clustering-Algorithmen und Verfahren zur Partikelverfolgung unter Verwendung von Multi-Objekt-Tracking Algorithmen

Oscillating Combustion - Primary Measure to Reduce Nitrogen Oxide in a Grate Furnace - Experiments and Simulations

The emission from industries and the mobility sector is under strong legal regulations in many countries worldwide. In Germany, the amendment to the 17th BlmSchV (Federal pollution control ordinance), which has been in force for waste incineration plants since 2013, has given rise to a new limit for nitrogen oxides of 150 mg/m3 as the daily mean level from 2019 on. A similar focus is on biomass-fired plants. According to the MCP (medium combustion plant) guideline of the EU, as a consequence, existing plants are required to either increase their consumption of ammonia water for nitrogen oxide reduction (SNCR process) or back fit SCR catalysts as secondary measures, which is a costly procedure. This paper presents a novel two-stage process in which an oscillating supply of secondary air allows nitrogen oxides to be reduced by approx. 50% at a good burnout level, which may obviate the need for secondary measures. Besides experimental investigations in a fixed bed reactor, CFD simulations confirm a high potential for reduction of nitrogen oxides. Together with the company POLZENITH, this process is under development for scale-up in a biomass incineration plant as a next step

A Novel Plenoptic Camera-Based Measurement System for the Investigation into Flight and Combustion Behavior of Refuse-Derived Fuel Particles

In the past several decades, refuse-derived fuels (RDFs) have been widely applied in industrial combustion processes, for instance, in cement production. Since RDF is composed of various waste fractions with complex shapes, its flight and combustion behaviors can be relatively complicated. In this paper, we present a novel plenoptic camera-based spatial measurement system that uses image processing approaches to determine the dwell time, the space-sliced velocity in the depth direction, and the ignition time of various applied RDF fractions based on the obtained images. The image processing approach follows the concept of tracking-by-detection and includes a novel combined detection method, a 2.5D multiple particle tracking algorithm, and a postprocessing framework to tackle the issues in the initial tracking results. The thereby obtained complete spatial fuel trajectories enable the analysis of the flight behaviors elaborated in the paper. The acquired particles’ properties (duration, velocity, and ignition time) reversely prove the availability and applicability of the developed measurement system. The adequacy and accuracy of the proposed novel measurement system are validated by the experiments of detecting and tracking burning and nonburning fuel particles in a rotary kiln. This new measurement system and the provided experimental results can benefit a better understanding of the RDF’s combustion for future research