1981 Volume 14 Issue 5 Pages 365-371
Wet particles of activated alumina were dried in batch and continuous packed fluidized beds with open-end cylindrical screen packings. The drying characteristics of the packed fluidized bed dryers was investigated.
The drying rate in the constant drying rate period can be estimated by the empirical equation for gas-particle heat transfer coefficient obtained by Kato et al.1), and the drying rate in the falling drying rate period is proportional to the free moisture content in the particles. Both overall drying rate in the continuous packed fluidized bed dryer and outlet gas temperature from the bed were affected by superficial gas velocity, bed height, inlet gas temperature, average residence time of particles in the bed and packing size.
The drying characteristics of a continuous packed fluidized bed dryer is analyzed by the plug flow model for the gas flow pattern and the plug flow model or the perfect mixing model for the particle flow pattern in the bed.
If the packing size is smaller than 2.5 cm, and the average residence time of particles is less than 30 minutes, the drying characteristics in the bed can be analyzed by the plug flow model for the particle flow pattern in the bed and the plug flow model for the gas flow pattern.
