Investigating the flow structures in semi-cylindrical bubbling fluidized bed using pressure fluctuation signals

摘要

Hydrodynamic characteristics of a gas-solid semi-cylindrical fluidized bed was experimentally investigated and compared with that of a cylindrical bed by analysis of pressure fluctuations. Pressure fluctuations were analyzed in time and frequency domains using standard deviation, power spectral density function and discrete wavelet transform methods. Experiments were carried out in two semi-cylindrical and cylindrical fluidized beds of 14 cm in diameter each, operating in the bubbling fluidization regime at ambient pressure and temperature. Both beds were filled with glass beads of various sizes (120, 290 and 450 mm). The superficial gas velocity was varied in the range of 0.2-0.8 m/s. Results showed that although the minimum fluidization velocity is influenced by the particle size, it is not affected by the geometry of the bed. It was shown that the hydrodynamics of both beds are very similar and the difference is negligible. Number of large bubbles is slightly larger in the semi-cylindrical bed as compared with the cylindrical bed. Also, increase in the particle size and superficial gas velocity result in a greater difference between the number of large bubbles in both beds and the number of large bubbles in the semi-cylindrical bed increases slightly faster than in the cylindrical bed. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.