Drying of Microparticle Slurry and Salt-Water Solution by a Powder-Particle Spouted Bed

Abstract

Adhesion and agglomeration between fine particles and coarse particles are very strong for fine particles under several microns in diameter. The powder-particle spouted bed (P-PSB) was developed as a new type of dryer for continuous drying of microparticles under several microns in diameter. The powder-particle spouted bed dryer is a cone-bottomed fluidized bed without a gas distributor. Coarse particles were loaded into the dryer and the hot gas was fed to it from the cone-bottom so that coarse particles were fluidized violently, and a microparticle slurry and a salt-water solution were continuously fed to it.
Continuous drying of a microparticle slurry and a salt-water solution were carried out by using the powder-particle spouted bed, and the drying characteristics were investigated. The moisture content of the microparticles dried by this process from the submicroparticle (under 1 μm in diameter) slurry and the salt-water solution were nearly equal to their equilibrium moisture content over the range of the experiment. When the drying efficiency was above 60%, agglomerates were observed in the bed. The relative humidity of the outlet gas and the drying efficiency can be calculated by mass and heat balances across the bed.