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The design of multiphase reaction and separation processes, such as for example catalytic hydrogenations, distillation and absorption processes, extraction processes, wastewater treatment, and many more, require a profound understanding of the multiphase fluid dynamics inside reactors and contactors. As Computational Multiphase Fluid Dynamics is still not fully mature to simulate complex two-phase and three-phase flow with overlaying heat and mass transfer as well as chemical reaction with sufficient accuracy there is a constant need for advanced experimental and measurement techniques; may it be for the provision of operational, design or thermodynamic parameters or for the validation of codes. In this talk we report on three different novel measurement techniques for this purpose. The presentation shall exemplarily demonstrate how advanced measurement and imaging techniques can be used to study opaque two-phase and three-phase flows in lab environment and potentially also in the field. We report on a) the use of ultrafast X-ray tomography and wire-mesh sensors for the study of reactive bubbly flow in a bubble column, b) the application of a large flow profiler in studying two-phase flow on a distillation column tray, and c) a method to obtain gas dispersion parameters in gas-liquid contactors using modulated gas flow.

Hydrodynamics and mass transfer characteristics are analyzed in a bubble column subjected to simulated ship motions using a hexapod robot with six-degree-of-freedom motions. Wire-mesh sensors have been used for collecting local gas holdup and flow patterns under non-reactive conditions. Additionally, the electrical conductivity of the liquid phase during CO2 uptake was extracted to determine hydroxide ion consumption rates as an indicator of mass transfer. The two-phase flow patterns in the bubble column operating under offshore conditions deviate significantly from the stationary ones due to the buoyancy-driven lateral migration of bubbles. The consumption rates of hydroxide ions during the chemical absorption of CO2 revealed that the amplitude of oscillations imposed on the bubble column is the dominant factor for the mass transfer in moving columns. Contrarily, the effect of the oscillation frequency is negligible, which is attributed to bubble coalescence and bubble flow maldistribution in the bubble column subjected to rotational oscillations. Bubble-free zones are formed in the liquid phase because of the buoyancy effects in the column tilted from the vertical axis, while the frequency of the oscillations does not add any additional effects to the bubble kinematics. The latter is attributed to the low shear rates maintained over the range of frequencies simulating marine swells.

This data set contains the processed data of the wire-mesh sensor, obtained in a flow loop with inner diameter of 50 mm with a vertical section of 3 m length. The dimension of the sensor is 16x16 wires and a lateral wire distance of 3.125 mm. Each file contains data of 60 s measurement time with 10 kHz samling frequency. The set up was operated with pressurized air and deionized water. The experimental matrix contains meausrements at different superficial velocities of the gas and the liquid. Thus different flow pattern are observed. For injection of the gas two different types have been used. In the first set of experiments (files 1- 61, *injection1*) the gas was injected with a small tube with inner diameter of 9 mm. In the second set of experiments (files 101 - 151, *injection2*) the gas was injected with a small pipe of 25 mm inner diameter. An overview of the experimental conditions for the two sets of experiments are summarized in the excel file. The corresponding *.zip files contain the processed data. These are void files, which contain the gas holdup in each crossing point and for all time steps of the measurement stack. Additionally the time averaged cross sectional gas holdup distribution (*.epsxy), the time averaged radial gas holdup (*.epsrad_20) and the cross sectional average gas holdup at each time step (*.epst) is provided

The cost-effective production of large amounts of green hydrogen using a new generation of proton exchange membrane (PEM) electrolyzers generates very high gas fractions, resulting from the high current densities. Hence, the shift of operating membrane conditions in the anode circuit into new and hitherto incomprehensible areas occurs. The mass fraction of oxygen prevails over the mass fraction of hydrogen by a factor of 8. Thus, the space and material requirements for conventional separators are very high. The main goal for the separation process of oxygen from the two-phase flow mixture is a completely gas-free operation fluid before the water enters the heat exchanger. This requires the optimization of oxygen separation technologies. For this purpose, a vertically arranged separator on the pilot scale was built up at Helmholtz -Zentrum Dresden – Rossendorf, which is based on the principle of swirl separation. This contribution provides results on the experimental study of different types of swirl geometries, which have the main impact on the separation efficiency of the process. Different types of swirl geometries are investigated and the development of the gas core and its stability are analyzed for single and two-phase flow at various flow rates of the gas and the liquid. Project The authors acknowledge the financial support by the Federal Ministry of Education and Research of Germany in the programme ”H2GIGA. Project identification number: 03HY123E.

The cost-effective production of large amounts of green hydrogen using a new generation of proton exchange membrane (PEM) electrolyzers generates very high gas fractions in the anode circuit, resulting from the high current densities. The volume fraction of oxygen prevails over the volume fraction of hydrogen by a factor of 20. The main goal for the separation process of oxygen from the two-phase flow mixture is a completely gas-free operation fluid before the water enters the heat exchanger. Furthermore, the local instantaneous oxygen fraction represented by partially fine dispersed bubbles related to the full oxygen amount in the anode circuit is still unknown and should be investigated. Due to the development of new separation concepts with high separation efficiency, the measurement of gas holdup and bubble size are carried out using a capacitance wire-mesh sensor (WMS), optical channel body flow sensor, and optical microscope. This poster was prepared for the H2Giga status conference and provides an overview of measurement techniques used in the project. Project The authors acknowledge the financial support by the Federal Ministry of Education and Research of Germany in the programme ”H2GIGA”. Project identification number: 03HY123E.

The design of bubble column reactors require a comprehensive understanding of the fluid dynamics. The type of gas distributor has a main impact on bubble size distribution and flow regime. With increasing gas flow rate, the interaction of the bubble increases and the dispersion of the bubbles changes. Although these effects play an important role also on the mass transfer in bubble columns, the distance parameters of bubbles in dense swarms has been poorly investigated so far. This contribution presents an experimental study carried out with ultrafast X-ray CT (UFXCT) on a dense bubbly flow. Experiments were conducted in a bubble column of 10 cm inner diameter and for gas superficial velocities up to 3.5 cms-1. UFXCT allows for non-invasive plane measurement of the phase distribution at different scanning heights of the column. Based on the extracted coordinates of the bubble centers the distances of nearest neighbors of all bubbles were computed. In addition, pair correlation function has been applied to reveal information on the near order of bubbles. The Sauter Mean Diameter was found to have a remarkable influence on the clustering characteristics and the near order of the bubbles.

Instrumented flow-following sensor particles have been developed for investigation of hydrodynamic and biochemical processes in chemical reactors and bioreactors, where standard measurement techniques are not applicable. The sensor particles allow autonomous long-term measurement of spatially distributed process parameters in the chemically and mechanically harsh environments of e.g. agitated industrial vessels. Each sensor particle comprises of an on-board measurement electronics that logs the signals of the embedded sensors. A buoyancy control unit enables automated taring to achieve neutral buoyancy of the sensor particles. Moreover, controlled floating of the sensor particles is possible to expose them for recovery from the liquid surface. Macro-flow tracking of the sensor particles is validated with circulation time reference measurements by means of salt tracer experiments in a stirred model reactor and CFD simulations. Moreover, process characterization with sensor particles is demonstrated in three further applications, namely a biogas pilot digester, an air-water column and a biological wastewater treatment basin. Acquired data were used to fit mixing model parameters, namely effective circulation time, circulation number, degree of suspension and Péclet number.

Swarm effects in bubble columns result from the interaction of the bubbles at higher gas holdup. The flow around individual bubbles in a swarm influences the movement of the following bubbles and this has a feedback on the flow regime on a larger scale. That is, hydrodynamics that can no longer be described with models for single rising bubbles. The experimental investigation of the multiscale hydrodynamics in three-dimensional bubble columns was so far limited by the available measurement techniques. In this study, ultrafast X-ray tomography (UFXCT) was applied on bubbly flows in a lab scale bubble column to determine inter-bubble distances and clustering characteristics for different gas holdups and bubble diameters. Applying the pair correlation function reveals a pronounced vertical clustering for large bubbles with Eo ≥ 3.82, whereas no clustering has been observed for bubbles of lower Eo. It was found that clustering orientation mainly depends on deformability of the bubbles but not on gas holdup.

The chemical absorption reaction of CO2 in a circular bubble column reactor was simulated with an Euler/Lagrange CFD method and results were compared with data from a laboratory scale bubble column. The experimental data comprises gas holdup and bubble size distributions obtained with ultrafast X-ray tomography and hydroxide ion conversion obtained with a wire-mesh sensor. Large Eddy Simulation (LES) is used for calculating the fluid flow and modelling the turbulence in the continuous phase, considering the effect of sub-grid-scale (SGS) turbulence on bubble motion, and also SGS turbulence modification by bubbles. Lagrangian bubble tracking is conducted considering all relevant forces, bubble oscillation via stochastic generation of eccentricity and motion angle and consequently non-steady mass transfer via a dynamic Sherwood number. The comparison of experimental and simulation results shows very good agreement for the given data.

The main focus of this project was the experimental investigation of hydrody-namics and mass transfer characteristics together with a chemical reaction in a bubble column at higher gas holdup. Experiments were performed for chemical absorption of CO2 in alkaline solution of different pH, at homogenous bubbly flow conditions and up to 17% gas holdup. Ultrafast electron beam X-ray to-mography (UFXCT) has been used to obtain local gas holdup data and bubble characteristics and a wire-mesh sensor was used to measure species concentra-tion fields in the liquid bulk. In addition, experiments with the reactive system FeII(edta)/NO were carried out and a new a fiber optical probe was employed for local measurement of product concentration in the bubble wake.

Reactive bubbly flows are found in many chemical and biochemical process-es. They are characterized by complex hydrodynamics that govern global mass transfer and reaction rates. Effects, which have to be taken into account when modelling and simulating the reaction progress are enhanced bubble-bubble interaction and bubble-induced turbulence as well as swarm-induced macro-convection. This poses great challenges on both, experimental analysis and numerical simulation. Bubble swarms at higher gas fractions are opaque, which limits the use of optical flow measurement techniques. Moreover, simu-lations at industrial scale are only feasible with point-bubble-based Euler-Euler or Euler-Lagrange approaches. Such approaches require closure relations, which account for all relevant interfacial forces as well as bubble-induced tur-bulence and coalescence including swarm effects. This chapter describes the progress in the experimental analysis and CFD simulation of reactive bubbly flows achieved during the time of the DFG Priority Programme SPP 1740. Ex-perimental studies in bubble columns reported in this Chapter were carried out at TU Dresden and OVGU Magdeburg. CFD model development and simula-tion has been carried out at OVGU Magdeburg using the Euler-Euler and Euler-Lagrange method and at TU Kaiserslautern and Helmholtz-Zentrum Dresden-Rossendorf using the Euler-Euler approach. As reaction systems the chemi-sorption of CO2 in NaOH solution and the reaction of FeII(edta) with NO were studied.

This data set contains the processed data from ultrafast X-ray tomography measurements in a bubble column. Measurements were performed in a bubble column with 100 mm inner diameter and with deionized water and nitrogen as liquid and gas phase, respectively. This data set contains the measurement from the measurement height located 0.7m above the gas sparger.  Hydrodynamic data, such as bubble size distribution and gas holdup distribution are provided. Furthermore, inter-bubble distances of gas bubbles (distance of the nearest neighbours) are given. Further detailes on the experiments and the processed data is provided in the corresponding journal paper.

This data set contains gas phase hydrodynamic data obtained from ultrafast X-ray tomography measurements in a bubble column. Global and local gas holdups, as well as bubble size distributions are given for I) non reactive conditions with nitrogen (gas) and sodium hydroxide solution (liquid) and II) reactive conditions with carbon dioxide (gas) and sodium hydroxide solution (liquid). Additionally the data set contains the corresponding consumption rates obtained from wire-mesh sensor measurements. Furhter details on the experiments are explained in the corresponding journal paper.

For the investigation of bubble column hydrodynamics an experimental study using ultrafast electron beam X-ray tomography (UFXCT) has been carried out. Local hydrodynamic parameters were measured in a DN100 bubble column using two types of capillary gas sparger, which are named as 'Type A' and 'Type B' . Nitrogen is used as gas phase and deionized water as liquid phase. For Type B sparger additionally, experiments with sodium hydroxide of different concentrations are given. Experiments were carried out at two different measurement heights, which are located at 10 (L/D = 1) and 70 cm (L/D = 7) above the gas sparger An additional readme.txt file provides all required information and is necessary for the interpretation of the experimental data.

BACKGROUND: The nutrition and physical activity self-assessment for childcare (NAP SACC) intervention has demonstrated effectiveness in the USA. A feasibility randomised controlled trial was conducted in England to adapt the intervention to the UK context. An embedded process evaluation focused on three key questions. 1. Was it feasible and acceptable to implement the intervention as planned? 2. How did the intervention affect staff and parent mediators? 3. Were the trial design and methods acceptable? METHODS: Twelve nurseries in south-west England were recruited and randomised to intervention or control. The intervention comprised: NAP SACC UK Partner (Health Visitor) support to nurseries to review practice and policies against best practice, and then set goals to improve physical activity, nutrition and oral health; two staff training workshops; and a web-based parent support element. The process evaluation comprised: observations of Partner training (n = 1), Partner/manager meetings (n = 5) and staff workshops (n = 10); semi-structured interviews with Partners (n = 4), managers (n = 12), staff (n = 4) and parents (n = 20); analysis of self-assessment forms, goal setting forms and Partner logbooks; and assessment of staff and parent knowledge, motivation and self-efficacy mediators. RESULTS: Overall, NAP SACC UK was feasible to implement and acceptable to nursery staff, managers, Partners and parents. The intervention was implemented as planned in five of the six intervention nurseries. Partners and managers appreciated the opportunity to review and improve nursery practices and valued the relationship forged between them. Staff rated the training workshops highly, despite attending outside of working hours. Most goals set by nurseries were achieved. However, Partners raised concerns about Health Visitors' capacity to deliver the intervention in any subsequent roll out. Mediator scores improved in all but two areas in intervention staff and parents, with decrease

Bubble column reactors are widespread in the chemical industry [1]. Hydrodynamics and mass transfer processes in bubble column reactors are difficult to predict, as they occur at different length and time scales. Thus, numerous parameters affect the performance of bubble column reactors in terms of yield and selectivity. These are the gas holdup, bubble size, bubble interfacial area, liquid-phase velocity, and mass transfer coefficients. In addition, the kinetics of the chemical reactions in a bubble column and the mixing of the reactants play a significant role and may even feedback on mass transfer and hydrodynamics. Within a German DFG Priority Programme we investigate the coupling between hydrodynamics, mass transfer and reaction in bubbly flows across the scales and with real chemical reaction systems [2]. Within this framework, our group studies the macroscale processes in laboratory bubble columns with selected experimental techniques. In our presentation, we will introduce two different ways for time-resolved local chemical species concentration measurement, i.e. the analysis of OH- consumption during chemisorption of CO2 in alkaline solution by electrochemical analysis using a wire-mesh sensor as well as chemical conversion of NO in Fe(II) (EDTA) solution with a fiber optical photospectrometry technique.

Topics of current research activities within the DFG priority program SPP 1740 “Reactive Bubbly Flows” are studies on local mass transfer and reaction processes in order to gain a deeper understanding about the coupling of hydrodynamics, mass transfer and reaction kinetics in reactive bubbly flows as well as its influence on yield and selectivity in case of complex chemical reactions. Precondition for experimental investigations is the availability of sensors for local concentration measurements of components in the liquid phase. Due to limitations of currently available non-invasive measuring techniques, local concentration measurements in dense bubbly flows at technical scale pose technological challenges. Therefore, a minimal-invasive photometer probe have been qualified to measure concentrations of intermediates and products within the liquid phase of dense bubbly flows with high temporal and spatial resolution. This work was supported by the German Research Foundation (DFG), reactive bubbly flows (SPP 1740).

Bubble columns are widely applied reactors in the chemical process industry due to their excellent heat and mass transfer properties as well as their simple design and easy manufacturing without any moving part. Fischer-Tropsch and methanol syntheses are typical processes carried out in such columns. Most of the involved reactions are highly exothermic and require an efficient heat removal, for example, via internal tube bundle heat exchangers. Heat exchangers, with up to 60 m2 m-3 surface area, can be installed as dense tube bundles covering up to 60 % of the cross-sectional area, which accordingly, alter hydrodynamics, flow patterns, mixing and mass transfer significantly. Therefore, this study aims at revealing the influence of common tube bundle layouts, i.e. triangular and square pitches, at various tube diameters at approx. 25 % cross-sectional area coverage. The studies were carried out using narrow and pilot-scale bubble columns with 100 and 400 mm diameter, respectively, operated with air and water. Ultrafast X-ray tomography as well as wire-mesh sensors were applied to study the columns’ hydrodynamics as well as the flow in individual sub-channels. In particular, holdup and bubble size distributions were measured and compared for both columns. Furthermore, it is discussed to which extend hydrodynamic parameters, such as radial holdup profiles and gas velocity profiles etc., can be utilized for scale-up purposes based on hydrodynamic similarity at both reactor scales.

Blasensäulenreaktoren zählen aufgrund ihrer einfachen Bauweise und ihres ausgezeichneten Wärme-und Stofftransportverhaltens zu einem der häufig genutzten Reaktortypen in der chemischen Industrie. Gegenstand aktueller Forschungsarbeiten innerhalb des DFG Schwerpunktprogramms 1740 „Reaktive Blasenströmungen“ ist die Untersuchung lokaler Transportprozesse, um das Verständnis über die Kopplung von Hydrodynamik und Stofftransport bei reaktiven 2-Phasenströmungen in Blasensäulen zu verbessern. Aufgrund limitierter Messtechnik stellt die Ermittlung von lokalen Konzentrationsfeldern und Stofftransportraten in dichten Blasenströmungen eine besondere Herausforderung dar. In diesem Beitrag werden experimentelle Untersuchungen zum Stofftransport am Beispiel der chemischen Absorption von CO2 vorgestellt, bei der die am HZDR entwickelte Gittersensormesstechnik zur Ermittlung der Konzentration und der Umwandlung ionischer Spezies eingesetzt wird. Für diesen Zweck konnte der Gittersensor anhand eines theoretischen Modells und Validierungsexperimente erfolgreich qualifiziert werden. Die experimentellen Ergebnisse der Stofftransportuntersuchungen in einem Blasensäulenreaktor zeigen die Stofftransportraten für verschiedene Eingangsparameter (z.B. Eingangskonzentration der Natronlauge und Gasdurchsatz des CO2) sowohl in Abhängigkeit des Radius als auch in verschiedenen Höhen des Reaktors.

In this paper we report for the first time on the utilization of the wire-mesh sensor for the measurement of chemical species conversion during the chemical absorption of carbon dioxide in sodium hydroxide solution. The wire mesh-sensor obtains cross-sectional images of the liquid phase conductivity which changes with the conversion of hydroxides during the reaction. A theoretical model has been applied to verify the use of conductivity as indicator for the reaction progress. Demonstration experiments have been carried out in a lab-scale bubble column reactor using two wire-mesh sensors in different reactor heights. Results obtained from reactor model and experimental data show a very good agreement. The results demonstrate the potential of this imaging instrument to follow the course of a chemical reaction via ionic species concentration even in a dense bubbly flow. This way, a better understanding of the coupling of hydrodynamics, mass transfer and reaction in bubble columns and other reaction devices can be gained.

Design and operation of bubble columns are of main importance, since they strongly influence yield and selectivity of chemical reactions. In order to improve the process efficiency, a fundamental understanding of flow phenomena in bubble columns is necessary. A lot of research has been carried out for the investigation of hydrodynamics of bubble columns. Nonetheless, hydrodynamics is changing in the presence of a chemical reaction (e.g. shrinkage of bubbles due to mass-transfer processes). Hence, there is a strong interaction of hydrodynamics, mass-transfer and chemical reaction within bubble columns, which has been investigated in the past, amongst others, using the reaction of sodium hydroxide and carbon dioxide. However, most works are restricted to low gas holdups or provide only single point information due to the use of local probes (e.g. pH measurement). This contribution comprises the experimental investigation of the reaction of sodium hydroxide and carbon dioxide, applying Wire-Mesh Sensors for determining the locally occurring reaction steps at different operating conditions (e.g. gas flow rate of carbon dioxide, initial concentrations of sodium hydroxide). In turn, experimental results are compared with concentration profiles derived from known reaction kinetics. The application of Wire-Mesh Sensors for this purpose allows the visualization of the concentration distribution within the cross-section of the bubble column. Additionally, ultrafast X-ray computer tomography is used simultaneously to study the change of hydrodynamics during the reaction.

Wire-mesh sensors (WMS) are today well established measurement tools to obtain both temporally and spatially highly resolved structural information as well as averaged phase fraction and phase fraction distribution data in air-water and steam-water two-phase flow experiments. Those data, with a spatial resolution of down to 0.5 mm and frame rates up to 10,000 frames per second are suitable to validate CFD code developments. During the last decade, the technology has widely spread in research laboratories all over the world and has been more and more developed towards a turnkey machine for researchers. In this work we summarize the most recent developments in hardware for high temperature and high pressure applications, new electronics with integrated void fraction calculations and flow pattern identification for industrial applications and latest software developments for data analysis and visualization. A big issue for the application of wire-mesh sensor technology to high pressure high temperature facilities is the complicated pressure-proven and temperature-resistant insulated support and feedthrough of the measuring electrodes. Our new development facilitates a compact metallic body with flanges on both sides with a slot in sensor unit consisting of ceramic insulators and a stainless steel frame. The feedthrough of the wires is realized by commercially available multiple feedthrough fittings. The most common and proved codes for WMS data analysis have been capsulated in our wire-mesh sensor data processing FrameWork. The tool has got a new, user friendly graphical interface and allows the implementation of new algorithms by the end user. The resulting data and profiles can be visualized within the software and a batch processing tool allows automated “over the weekend” jobs. The wire-mesh sensor technology so far is a scientific tool for researchers. The huge amount of data, several gigabytes for one measurement of a couple of seconds, has to be stored and proce

Wire-Mesh Sensors (WMS) are applied in many research applications to determine the distribution of the phase fraction and to visualize the flow behavior within a pipe. However their application in industries is restricted due to the procedure of data acquisition. Here a new design of Wire-Mesh Sensor for monitoring void fraction and flow pattern behavior is presented. As result of online data evaluation cross-sectional void fraction information is provided in almost real-time. Additionally, the present flow pattern is determined by statistical analysis of recorded data of a time period of 10 s. This is the first time a Wire-Mesh Sensor was used for this purpose. With the help of fuzzy methodology a distinction of the four main flow patterns of vertical upward gas-liquid flow is possible. Furthermore transition regions can be identified. The algorithm is based on the evaluation of statistical void fraction distribution as result of Wire-Mesh Sensor data. Validation experiments of the new adopted algorithms are carried out in a 50 mm-ID two-phase air-water flow-loop at Tulsa University Horizontal Well and Artificial Lift Projects (TUHWALP).

Bubble columns are a favored reactor type for the operation of gas-liquid reactions (e.g. oxidation and hydrogenation processes) in chemical industries. The improved design and operation of bubble column reactors requires a detailed understanding of the flow phenomena as well as mass transfer processes within these reactors. This study presents the experimental investigation the gas liquid mass transfer in a bubble column on the basis of the chemical absorption of CO2. This contribution presents ultrafast X-ray CT measurements within a bubble column. The mass transfer has been determined by the analysis of the decrease of gas the gas phase, especially the shrinkage of the CO2 bubbles.

Blasensäulenreaktoren bieten aufgrund ihrer einfachen Bauweise und ihres ausgezeichneten Wärme- und Stofftransportverhaltens einen häufig genutzten Reaktortyp in der chemischen Industrie. Besonders die Beschreibung der Hydrodynamik und der Geschwindigkeitsprofile der unterschiedlichen Phasen, sowie deren radiale Verteilung haben einen erheblichen Einfluss auf den Stofftransport und chemische Reaktion. In diesem Beitrag sollen die Ergebnisse der Untersuchung zur Flüssigphasengeschwindigkeit in Blasenströmungen vorgestellt werden. Die Anwendbarkeit von Heißfilmsonden ist bei Vorliegen einer Mehrphasenströmung stark begrenzt. In Blasensäulen beinhaltet das gemessene Geschwindigkeitssignal Anteile der Gas- und Flüssigphase. Zur Untersuchung der Umströmung von Blasen und zur Bestimmung von Turbulenzparametern ist es notwendig diese Anteile voneinander zu trennen. Ausschließlich bei geringen Gasgehalten bietet der charakteristische Signalverlauf bei der Interaktion von Blase und Sonde eine Möglichkeit dazu. In dieser Arbeit kann mit Hilfe der Zwei-Ebenen Tomographie, die genaue Position der Heißfilmsonde und die vorliegende Phase an dieser Stelle in der Blasensäule bestimmt werden. Weiterhin können neben der Flüssigphasengeschwindigkeit auch Parameter der Hydrodynamik der Gasphase, wie Blasenform, Blasengröße bestimmt werden und in Abhängigkeit zur Flüssigphasengeschwindigkeit gestellt werden.

Within the development of an industrial type of Wire-Mesh Sensor (WMS) algorithms for flow pattern identification were developed. Based on the statistical evaluation of gas holdup distribution, the distinction of the main flow patterns in gas-liquid flow is carried out. Experimental validation of the algorithm was carried using experimental flow loop from The University of Tulsa Horizontal Well and Artificial Lift Project (TUHWALP).

In der chemischen und biochemischen Industrie werden oftmals Blasensäulenreaktoren für Mehrphasenprozesse eingesetzt. Sie zeichnen sich durch ihren einfachen Aufbau, sowie gute Stoff-und Wärmeübertragungseigenschaften aus. In der Literatur sind umfangreiche Studien zur Auslegung und Dimensionierung solcher Reaktoren zu finden. Zur weiteren Prozessoptimierung ist zunehmend die Aufklärung der lokalen Mechanismen innerhalb des Reaktors, insbesondere die Interaktion von Hydrodynamik, Stofftransport und chemischer Reaktion, erforderlich. Die ortsaufgelöste Untersuchung von Hydrodynamik und Stofftransport in Blasenströmungen erfolgt bisher vornehmlich mit Hilfe optischer Verfahren, wie z.B. der Particle Image Velocimetry (PIV), Laser Doppler Anemometrie (LDA) und laserinduzierter Fluoreszenz (LIF). Während diese Messtechniken für die Untersuchung von Blasenströmungen geringen Gasgehaltes gut geeignet sind, stoßen sie bei hohen Gasgehalten an ihre Grenzen. Ziel dieses Beitrages ist es, eine Übersicht über den aktuellen Stand der Technik in Hinblick auf experimentelle Studien zur Hydrodynamik und gekoppelter Vorgänge, wie Stofftransport und Reaktion in Blasensäulenreaktoren zu geben. Dabei sollen die Notwendigkeit künftiger Studien in diesem Bereich und damit einhergehend die Anforderungen an die Messtechnik aufgezeigt werden.

Die Bearbeitung des vorliegenden Beleges umfasste eine umfassende Literaturrecherche zur Untersuchung und Charakterisierung von Mischvorgängen in Rührkesselreaktoren. Zudem wurden experimentelle Arbeiten mit Nadelsonden in einem bestehenden Versuchsbeh¨alter und im Zusammenhang damit Drehzahl- und Leistungsmessungen am Rührwerk durchgeführt. Weiterhin wurden CFD Simulationen für den Rührbehälter betrieben. Diese umfasste neben dem Aufbau der Geometrie und Diskretisierung des Gitters, die Durchführung eines Particle-Tracks. Abschließend wurde ein Vergleich der ermittelten Daten zwischen Simulation, Experiment und vorhandenen Daten der autonomen Sensorpartikel angestellt.