Gas, liquid and powder flow in the lower part of a blast furnace is complex phenomena. In order to understand the aerodynamics of the blast furnace properly, these phenomena must be included in their advanced form. Previous studies have shown that the conditions of blast furnace resemble the cold model experiments which have been done in decreasing gas velocities. Also, the recent studies have shown that liquid flow in a blast furnace can be represented more realistically considering it discrete in nature. In the current study, both the phenomena have been considered along with the injection of powder through a nozzle while studying the fluid flow behaviour in a packed bed. The situation resembles the lower part of an ironmaking blast furnace. In this study, gas flow has been modelled using k-ε turbulent model and has been coupled with previously developed stress model to calculate the raceway size. Coal powder is treated as continuum and has been modelled in the similar way as gas flow. After this gas and powder flow model were coupled with previously developed discrete liquid flow model. Liquid flow model has been considered for structured bed only. The governing equations for gas phase were discretized. Finite Volume method was used for the solution. Co-located grid is used for the simulation. Blending of upwind difference scheme and central difference scheme (deferred correction approach) is used to achieve the stability of upwind scheme and accuracy of central difference scheme. Similar treatment was employed for powder phase. For the solution of volume fraction of powder, powder phase continuity equation was used along with pseudo time step scheme. Results obtained from gas and powder models have been validated against published experimental data. Similarly, gas-liquid flow results have been validated against published experimental data on gas-powder flow. Results obtained by gas-powder-liquid model could not be validated against any experimental or theoretical data as they are not available in the literature. The effect of various parameters on the fluid flow (gas/liquid/powder) behaviour have been studied like the effect of increasing and decreasing gas velocities, flow rates of liquid, gas and powder, size of powder and packing etc. It is found that the above mentioned phenomena have significant effect on the fluid flow behaviour in a packed bed.

La diffraction des rayons X apparait comme une modalité prometteuse pour l'inspection non invasive de bagages. Par comparaison aux techniques traditionnelles d'imagerie par transmission, cette technique permet de révéler davantage d'informations caractéristiques sur les matériaux, comme les distances inter-réticulaires pour les matériaux cristallins ou la fonction d'interférence moléculaire pour les matériaux amorphes. La méthode de diffraction par énergie dispersive (EDXRD), qui travaille à angle fixe avec un faisceau polychromatique et un détecteur résolu en énergie, est plus particulièrement adaptée à la problématique de contrôle de bagages, car elle permet d'envisager une architecture parallélisée pour imager un bagage complet en un temps raisonnable. Les travaux proposés dans cette thèse ont donc pour but d'étudier un système EDXRD utilisant un détecteur spectrométrique CdZnTe multi pixels pour l'identification des matériaux illicites dans les bagages. Une première étape a consisté à prendre en main cette technique à la fois expérimentalement avec un banc de diffraction mis à disposition et théoriquement par le biais du développement d'un outil de simulation élaboré. La confrontation entre l'expérimentation et la simulation a permis de bien comprendre la physique d'un tel système et de mieux analyser ses faiblesses pour pouvoir les corriger. En nous appuyant sur ces deux outils, nous avons ensuite étudié et mis en oeuvre de nouveaux concepts pour améliorer les performances du système EDXRD, en termes de résolution, d'intensité et de stabilité des pics de diffraction. Ainsi, une architecture novatrice, s'appuyant sur un traitement des signaux transitoires délivrés par les détecteurs CdZnTe, est proposée afin d'améliorer le compromis entre la résolution des pics de diffraction et leur intensité. Cette architecture est basée sur la sur-pixellisation du détecteur par la méthode de localisation barycentrique et sur une adaptation géométrique du système collimateur/détecteur. Enfin, le problème d'instabilité des pics de diffraction, due à l'effet d'orientation des grains des matériaux cristallins, est également traité. / X-ray diffraction is becoming a prevailing technique for non invasive inspection of luggage. Compared to traditional techniques of transmission imaging, the diffraction technique can extract more characteristic information of materials, such as the Bragg peaks for crystalline materials or the molecular interference function for amorphous materials. The method of energy dispersive X Ray diffraction (EDXRD), which works at a fixed low scatter angle but with a polychromatic X-ray beam and a energy resolved detector, is particularly suited to the problem of luggage control as it allows parallelized architectures to inspect an entire object in a reasonable time. The work proposed in this thesis is to study an EDXRD system using a multi-pixelated CdZnTe detector to identify illicit materials in baggage. A first step has been to take control of this technique both experimentally with a diffraction bench and theoretically through the development of an elaborate simulation tool. The comparison between experiment and simulation has allowed to understand the physics of such a system and to better analyze its weaknesses to correct them. Relying on these two tools, we studied and implemented new concepts to improve performances of EDXRD systems, in terms of resolution, intensity and stability of the diffraction peaks. Thus, an innovative architecture, based on a dedicated treatment of transient signals delivered by the CdZnTe detectors, is proposed to significantly improve the compromise between the resolution of the diffraction peaks and their intensity. This architecture is based on an over-pixelation (1D) of the detector by an electronic positioning method and on a geometric adaptation of the system collimator/detector. The problem of instability of the diffraction peaks due to the effect of grain orientation in crystals is also handled.