Description et modélisation des structures globale et locale des lits fluidisés en régime turbulent

✍ Scribed by A. Chehbouni; J. Chaouki; C. Guy; D. Klvana

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 777 KB
• Volume: 61
• Category: Article
• ISSN: 0923-0467
• DOI: 10.1016/0923-0467(95)03029-8

✦ Synopsis

In order to study the structure of turbulent beds, local instantaneous and time-averaging suspension densities were determined with a needle capacitance probe. The probe can be moved radially across the bed at different axial locations in two experimental set-ups (an (82 \mathrm{~mm}) and a (200 \mathrm{~mm}) i.d. stainless-steel column). The measured density fluctuation signals were analyzed by means of average amplitude, standard deviation and dominant frequency. It is shown that the turbulent fluidized bed presents an intermediate structure between the bubbling and the fast fluidized bed regimes. The profile of the void fraction presents an important radial gradient but only a slight axial variation. The spectral density of local void fluctuations increases from the axis of the column to the near wall. This is related to the gradual increase in the solid aggregate size. Two new correlations which predict respectively an average and a local void fraction in turbulent fluidized beds are developed.