Abstract
Pressure fluctuations and bubble frequency in fluidized beds were measured at several stages of temperature ranging from 280 K to 640 K. Four types of powders belonging to group A of Geldart''s classification were used. The quality of fluidization at various temperatures was evaluated by a uniformity index based on pressure fluctuations and by bubble size obtained from bubble frequency. The reduction both in the deviation of amplitude of pressure fluctuations and in bubble size showed that the quality of fluidization improved with increasing temperature. However, at room temperature, beds of dry particles were affected by electrostatic phenomena and thus the fluidity was decreased. The influence of the electrification decreased at elevated temperature, or at room temperature when the particles held water in the pores.
