DRYING OF POWDERY MATERIALS IN A PULSED FLUID BED DRYER

ABSTRACT

Drying of recycled polypropylene powder was studied experimentally in a laboratory pulsed fluid bed dryer (PFB) with relocated air stream. It was proved that fluidization of fine particles having a large specific surface area and a broad size distribution is technically feasible when using the composite supporting grid. Drying and hydrodynamic characteristics for a pulsed fluid bed of fine particles are found to be similar to the ones for coarse particles. Equations for minimum pulsed fluidization velocity, pressure drop, and surface and volumetric heat transfer coefficients are given.

Key Words and Phrases:

• drying kinetics
• hydrodynamics
• heat transfer
• pressure drop
• polypropylene
• reduced moisture content
• size distribution