(24b) Transient 3-Dimensional Behavior of Gas-Solid Fluidization Measured Using Electrical Capacitance Volume Tomography (Ecvt)

The transient flow behavior in the gas-solid fluidized bed is complex. Although numerous experimental and theoretical studies have been conducted on gas-solid fluidization, understanding of real time, 3-dimensional internal flow structures of the fluidized bed is far from adequate. The common measurement techniques using probes such as the optical fiber probe or the capacitance probe can only provide the local point flow property in the bed. In contrast, the Electrical capacitance volume tomography (ECVT) recently developed by this group is capable of providing a real-time, three-dimensional volume images in a gas-solid fluidized bed. In this study, the ECVT is applied to examine the transient 3-D flow structures of a 0.1 m ID fluidized bed. The ECVT generates a real-time volume image defined in image voxels (volume pixels) of 20×20×20 resolutions from the capacitance data obtained using a 12-electrode sensor which surrounds the 3D section of 9 cm in length of a cylindrical column. Both of the Geldart Group A particles (FCC catalyst with a mean diameter of 60 mm and a density of 1400 kg/m3) and Group B particles (glass beads with a mean diameter of 200 mm and a density of 2500 kg/m3) are employed in the experiments. The interior flow structures, especially, the dynamic bubble interactive behavior and movement in a gas-solid fluidized bed in the bubbling and turbulent regimes are illustrated based on the 3D images obtained from the ECVT.