FAST X-RAY TOMOGRAPHY OF A BUBBLING FLUIDIZED

This paper presents results of a train of bubbles moving through a fluidized bed imaged with an X-ray Tomographic Scanner. The scanner consists of three X-ray sources equipped with 2*30 CdWO4 detectors each. The fluidized bed has a diameter of 23cm and is filled with polystyrene particles (mean diameter 560μm). The bed is set at minimal fluidization and additional gas is released from a single capillary, forming a train of bubbles moving upwards through the bed. The scanner measures the shape, size and velocity of the bubbles passing the measuring plane. We present data showing that the scanner can quantify for each bubble its size and velocity. The smallest bubbles detected have an equivalent diameter of less than 3cm

Time-Resolved X-Ray Tomography of a Fluidized Bed of Geldart A Particles

This paper discusses the influence of fines on the size of bubbles moving through a 23 cm ID fluidized bed of Geldart A particles imaged with an X-ray Tomographic Scanner. In earlier work [1], the bubble distribution in a fluidized bed of Geldart B particles was shown. The current study using Geldart A particles is more challenging to the reconstruction algorithm, since there are more bubbles, and they are smaller in size. We study the influence of adding fines (i.e. particles \u3c= 45 micron) to the system. When adding a mass fraction of fines of 24%, we find a decrease of the average bubble of 40% of the size for the original powder, in line with earlier results from pressure probes and optical probes [2]. We find that the entire distribution of the bubble sizes shifts to smaller values