Time-resolved characterization of a flat-base spouted bed with a high speed X-ray system

摘要

Time-resolved measurements are carried out for determining the spout shape and position in several cross sections of a flat-base spouted bed filled with 2 mm polystyrene particles. A high speed X-ray image system, consisting of 3 X-ray sources and 2 layers of 32 detectors for each source, is employed to measure the spout shape with a temporal resolution of 2500 fps. The X-ray attenuation data are analyzed by both tomographic reconstruction and raw data analysis. The averaged spout diameters show good agreement with literature. A particle circulation model is made for validating the measured data. The fluctuations of the spout diameter are analyzed from the computed power spectral density. It is shown that the spout is most stable for U/U_(ms) = 1.20-1.37. From measuring the center movement of the spout, we found an oscillation of the spout position. Its intensity is related to the bed height and gas flow rate.