THE EFFECT OF RADIAL DISTRIBUTION OF VOIDAGE ON THE BURNING RATE OF A CARBON SPHERE IN A FLUIDIZED BED

Abstract

The local void around a sphere in a packed bed or in the emulsion phase of a fluidized bed has been calculated theoretically; and measured as a function of the radial distance from the centre of the sphere. Effects of this distribution on the burning rate and Sherwood number have been investigated for two types of bed e.g. where inerts are of the same size as the carbon particle and where the inerts are smaller than the carbon particle. Even though the present analysis studies the effect on the diffusive component of the mass transfer alone, the results suggest that the distribution of voidage will yield Sherwood numbers higher than that calculated from the constant voidage assumption. The voidage distribution explains the increase in burning rate of carbon with increasing size of the inerts.

KEYWORDS:

• Mass transfer
• Fluidized bed
• Sherwood number
• Burning rate
• Inert size
• Voidage