A new X-ray computed tomography technique for the purpose of imaging fluidized beds is presented. It consists of an experimental set-up with three stationary X-ray source and flat panel detector pairs, a geometric calibration and data processing workflow, and an image reconstruction algorithm. The technique enables sparse-angular tomographic reconstruction in large 3D regions of fluidized beds at framerates up to 200 Hz, and therefore images bubbles along their whole trajectories through the volume. It allows for a unique analysis of bubble dynamics in fluidized beds, including bubble velocities, bubble transformations, i.e., time evolution of the bubble distributions in space, and bubble–bubble interactions. In this article, we first analyze the main limitation of the technique, the sparse angular resolution, through numerical simulations. We then test the experimental set-up through imaging a series of phantoms. Lastly, we demonstrate results from a Geldart B bubbling fluidized bed.

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Powder Technology
Mathematics and Algorithms for 3D Imaging of Dynamic Processes

Graas, A., Wagner, E., van Leeuwen, T., van Ommen, R., Batenburg, J., Lucka, F., & Portela, L. (2024). X-ray tomography for fully-3D time-resolved reconstruction of bubbling fluidized beds. Powder Technology, 434, 119269:1–119269:14. doi:10.1016/j.powtec.2023.119269