- AutorIn
- Erik Löwer Technische Universität Bergakademie Freiberg
- Titel
- Development of Process Models for Multiphase Processes in the Pore Space of a Filter Cake based on 3D Information
- Zitierfähige Url:
- https://nbn-resolving.org/urn:nbn:de:bsz:105-qucosa2-780499
- Übersetzter Titel (DE)
- Entwicklung von Prozessmodellen der mehrphasigen Prozesse im Porenraum eines Filterkuchens auf Basis von 3D-Informationen
- Datum der Einreichung
- 04.11.2021
- Datum der Verteidigung
- 27.01.2022
- Abstract (EN)
- Reliable information about the micro-processes during filtration and dewatering of filter cakes allows more accurate statements about process development and design in any industrial application with solid-liquid separation units. Distributed particle properties such as shape, size, and material influence the formation of the porous network structure, which can show considerable local fluctuations in vertical and horizontal alignment in the cake forming apparatus. The present work relates to a wide range of particle sizes and particle shapes and presents their effects on integral, but preferably local, structural parameters of cake filtration. Current models for the relationship between particle properties and resulting porous structure remain inaccurate. Therefore, the central question focus on the model-based correlation between obtained tomographic 3D information and characteristic cake and process parameters. In combination with X-ray computed tomography and microscopy (ZEISS Xradia 510), data acquisition of the structural build-up of filter cakes is possible on a small scale (filter area 0.2 cm²) and a conventional laboratory scale (filter area 20 cm², VDI 2762 pressure nutsch). Thereby, the work focuses on structural parameters at the local level before, during, and after cake dewatering, such as porosity, coordination number, three-phase contact angle, characteristics of pores and isolated liquid regions, the liquid load of individual particles, tortuosity, and capillary length, and the corresponding spatial distributions. Seven different particle systems in the range of 20 and 500 µm, suspended in aqueous solutions with additives for contrast enhancement, served as raw materials for the filter cake formation. Image data processing from 16-bit greyscale images with a resolution of 2 to 4 µm/voxel edge length includes various operations with a two-stage segmentation to identify air, solid particles, and liquid phase, resulting in a machine learning-based automated approach. Subsequent modeling and correlation of measured parameters rely on experimentally verified quantities from mercury porosimetry, laser diffraction, dynamic image analysis, static and dynamic droplet contour analysis, as well as filtration and capillary pressure tests according to VDI guidelines. The tomography measurements provide microscopic information about the porous system, quantified using characteristic key parameters and distribution functions. By studying the cake structure concerning the local distribution of particle size and shape and the resulting porosity, segregation effects can be avoided by increasing the feed concentration of particles, whereby swarm inhibition of particles in the initial suspension strongly hinders or completely suppresses layer formation in the cake according to distributed particle properties (Publication A). In the subsequent dewatering of the filter cake to the irreducible saturation, the measurement of the local coordination number as well as the remaining liquid volumes at the particle contacts allows the determination of a discrete liquid load distribution by correlation with the respective particle volume (Publication B). The determination of the capillary length - shortest capillary for single-phase pore flow and capillary of least resistance for multiphase pore flow - provides modeling approaches for the cake formation from publication A as well as the dewatering process from publication B (Publication C). The parameter sets obtained also help to transfer and extend existing, theoretical models of multiphase pore flow to the application example of filter cake dewatering (Publication D). At the microscopic level, the measurement of the three-phase contact angle at isolated liquid volumes within the porous matrix provides a deeper understanding of the macroscopic models from publications C and D (Publication E).
- Verweis
- Study on the influence of solids volume fraction on filter cake structures using micro tomography
Publikation A der publikationsbasierten Dissertation
Link: https://doi.org/10.1016/j.powtec.2019.12.054
DOI: 10.1016/j.powtec.2019.12.054 - Neighborhood Relationships of Widely Distributed and Irregularly Shaped Particles in Partially Dewatered Filter Cakes
Publikation B der publikationsbasierten Dissertation
Link: https://doi.org/10.1007/s11242-021-01600-7
DOI: 10.1007/s11242-021-01600-7 - Insight into filter cake structures using micro tomography: The dewatering equilibrium
Publikation C der publikationsbasierten Dissertation
Link: https://doi.org/10.1016/j.seppur.2020.117215
DOI: 10.1016/j.seppur.2020.117215 - Network model of porous media - Review of old ideas with new methods
Publikation D der publikationsbasierten Dissertation
DOI: 10.1016/j.seppur.2020.117854
Link: https://doi.org/10.1016/j.seppur.2020.117854 - Wetting behavior of porous structures: Three-dimensional determination of the contact angle after filter cake dewatering using X-ray microscopy
Publikation E der publikationsbasierten Dissertation
DOI: 10.1016/j.advwatres.2021.103894
Link: https://doi.org/10.1016/j.powtec.2019.12.054 - Forschungsdatenverweis
- X-ray tomography scans of filter cakes (feed slurry: variation in solid volume fraction)
DOI: 10.25532/OPARA-121
Link: http://dx.doi.org/10.25532/OPARA-121 - X-ray tomography scans of filter cakes (feed slurry: variation in fraction of fines)
DOI: 10.25532/OPARA-123
Link: http://dx.doi.org/10.25532/OPARA-123 - X-ray tomography scan of partially dewatered filter cake
DOI: 10.25532/OPARA-125
Link: http://dx.doi.org/10.25532/OPARA-125 - X-ray tomography scan of partially dewatered filter cake
DOI: 10.25532/OPARA-126
Link: http://dx.doi.org/10.25532/OPARA-126 - High-resolved X-ray tomography scan of dewatered filter cakes and sessile droplets
DOI: 10.25532/OPARA-124
Link: http://dx.doi.org/10.25532/OPARA-124 - Fully saturated and dewatered filter cakes at different resolutions
DOI: 10.25532/OPARA-122
Link: http://dx.doi.org/10.25532/OPARA-122 - Freie Schlagwörter (DE)
- Kuchenbildende Filtration, Filterkuchenentfeuchtung, Röntgentomographie, dreidimensionale Charakterisierung poröser Strukturen, Bildbearbeitung
- Freie Schlagwörter (EN)
- cake filtration, filter cake dewatering, X-ray computed tomography, three- dimensional porous media characterization, image processing
- Klassifikation (DDC)
- 660
- Normschlagwörter (GND)
- Kuchenfiltration
- Entfeuchten
- 3D-Technologie
- Poröser Stoff
- Tomografie
- Bildverarbeitung
- Den akademischen Grad verleihende / prüfende Institution
- TU Bergakademie Freiberg, Freiberg
- Version / Begutachtungsstatus
- publizierte Version / Verlagsversion
- URN Qucosa
- urn:nbn:de:bsz:105-qucosa2-780499
- Veröffentlichungsdatum Qucosa
- 20.05.2022
- Dokumenttyp
- Dissertation
- Sprache des Dokumentes
- Englisch
- Lizenz / Rechtehinweis
- CC BY-NC-ND 4.0
- Inhaltsverzeichnis
List of Figures List of Tables Notation 1 Introduction 2 Multiphase Processes in Porous Media 2.1 Cake Filtration and Single Phase Porous Media Flow 2.2 Cake Dewatering 2.2.1 Particle Surface Wettability 2.2.2 Capillarity in Porous Media 2.2.3 Static Capillary Pressure 2.2.4 Dynamic Capillary Pressure 3 Acquisition of 3D Information of Porous Media 3.1 Absorption and Scattering of X-rays 3.2 X-ray Microscopy 3.2.1 Image Acquisition 3.2.2 Image Reconstruction 3.2.3 Image Quality and Artifacts 3.3 Image Post-Processing 3.3.1 Image Enhancement 3.3.2 Segmentation and Thresholding 3.3.3 Processing Binary Images 3.4 Image Measurement 4 Materials and Methods 4.1 The Solid Phase 4.2 The Liquid Phase 4.3 Suspension Stability 4.4 Experimental Design and Down-Scale for Tomography Measurements 4.5 Experimental Characterization of Filtration and Dewatering Properties 4.5.1 Cake Filtration 4.5.2 Cake Dewatering (Capillary Pressure Measurements) 5 Conclusion and Outlook Literature Publications A to E Appendix