THE EFFECT OF TEMPERATURE ON FLUIDIZED BED BEHAVIOUR

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Abstract
Most published correlations for the minimum fluidizing gas velocity have been derived from tests under ambient conditions and increasing discrepancy is found in their application over wider ranges of operating conditions. Up to 1000°C the Ergun equation is reliable but it requires a knowledge of the particle shape factor and bed voidage for its application. Bed voidage is found to vary with temperature for laminar gas flow conditions. Paralleling changes in gas flow conditions with operating temperature are changes in bed-to-surface heat transfer coefficients. There is a distinct transition from the interphase gas convective to the particle convective component of heat transfer being the dominant mechanism as the operating temperature increases and Remf reduces through 12,5 at Ar ∼ 26000. This is thought to be a consequence of change in bed bubbling behavior.