DRYING OF PULP AND PAPER SLUDGE IN A PULSED FLUID BED DRYER

ABSTRACT

Hydrodynamics and drying kinetics for the pulp and paper primary sludge dried in a pulsed fluid bed dryer with relocated air stream are presented. Batch experiments have indicated that drying of disintegrated sludge to the required 12% moisture content takes place during the first drying period at practically constant material temperature close to the wet bulb temperature with respect to the inlet air conditions. Equations were developed for pressure drop, minimum pulsed-fluidization velocity, dynamic bed height, and volumetric mass transfer coefficient. Continuous experiments under drying conditions determined from the average residence time concept have confirmed that transportation of disintegrated sludge along the dryer follows the plug flow model.

©Her Majesty the Queen in Right of Canada, represented by the Minister of Natural Resources, 2002.

Keywords:

• Drying kinetics
• Drying time
• Heat transfer coefficient
• Material temperature
• Pressure drop
• Plug flow
• Reduced moisture content

ACKNOWLEDGMENT

Contribution of Dr. Samson Sotocinal from Department of Agricultural Engineering of McGill University to design and testing of the sludge disintegrator is highly appreciated.

Notes

©Her Majesty the Queen in Right of Canada, represented by the Minister of Natural Resources, 2002.