| Non-invasive Electrical Capacitance Electrical Tomography (ECT) measurements have been developed in this study to provide reliable and accurate quantitative results. Three calibration techniques have been proposed to substantially improve the accuracy of the ECT system. First, several liquid mixtures are used to calibrate the ECT system. Second, the relative permittivity of solid particles is obtained by immersing the solids in different fluids. The solids relative permittivity corresponds to the point where the fluid's relative permittivity matches the relative permittivity of the liquid-solid mixture. Third, the best relationship between solid holdup and electrical permittivity, over the required range of solid concentrations, is determined, for each particulate system, by suspending the particles in a viscous liquid, honey.;The phase holdup can be accurately estimated using a novel method, Model-Based Electrical Capacitance Tomography (MB-ECT). A physical model is first selected to describe the local phase hold-ups, using existing knowledge on similar hydrodynamic systems or preliminary measurements performed with other measurement methods. The approach consists of four main steps: a physical model predicts the local phase hold-up values, a model calculates the local effective permittivity from the local hold-up, a numerical technique then provides the capacitances using a finite element method, and an optimization technique adjusts the physical model parameters until calculated and measured capacitances agree.;MB-ECT has been applied to accurately estimate the annular layer thickness in the fully developed flow region in a riser, using electrical capacitance measurements. MB-ECT was experimentally verified in a two-phase riser system using a known physical model in the fully developed flow region. The values of the thickness of the annular layer obtained with MB-ECT were successfully validated using an invasive, dual-sided tribo-electric technique.;The hydrodynamic regime at two heights, within the riser, has been also investigated using three different measuring techniques including differential pressure drop, ECT measurements, and dual tribo-electric signals. A good agreement between all the techniques were obtained using different advanced signal analysis methods, which confirms that the lower level of the riser can be characterized by a perfectly mixed fluidized bed, whereas a core-annulus flow structure was observed in the upper level.;MB-ECT was also applied in a downer for two multi-phase flow systems: (a) a gas-solid system, and (b) a gas-solid-liquid system. MB-ECT was used to study the effect of different injecting nozzle configurations on the mixing quality between injected fluid and down-flowing particles in a downer. A model based on previous studies, called the flower model, was proposed to describe the contact behavior in the downer mixing chamber. The model has three parameters that must be obtained from experimental data: (a) the area of the flower, (b) solids holdup, and (c) liquid holdup. The last parameter is used only in the three-phase system. MB-ECT was found to be a very reliable and reproducible technique to determine the phase holdup distribution for each injection configuration.;Keywords. powder material, electrical capacitance, tomography, optimization, effective permittivity, multiphase flow, forward problem, core-annulus, riser, triboelectric, hydrodynamic regime, mixing chamber, downer, liquid injection, three-phase, solid-liquid mixing, model-based, signal analysis, V statistic. |
