On Improving Scale-Up Procedures for Dense-Phase Pneumatic Conveying of Powders

Abstract

This article presents results of an ongoing effort toward improving the modeling and scale-up procedures for the dense-phase pneumatic conveying of fine powders through pipes. Two new approaches are employed in this study. One approach, derived by modifying an existing reliable dilute-phase model to make it suitable for the dense-phase, has resulted in relatively stable predictions for diameter and length scale-up for two types of fly ash, ESP dust, pulverized brown coal and fly ash/cement mixture. Although some over-predictions still remain for the cases of diameter scale-up, there seems to be a substantial relative improvement in the overall accuracy of predictions (compared to the existing design methods). Another method has been derived using the concept of “two-layer” slurry flow modeling (suspension flow occurring on top of a non-suspension moving layer), and this has also resulted in similar improvements. Although the “two-layer” technique is believed to be more representative of the actual flow conditions under dense-phase conveying, the simpler “modified” method appears to be adequate for practical design purposes.

Keywords:

• dense-phase
• pneumatic conveying
• scale-up
• solids friction
• “two-layer” modeling

Acknowledgments

S. S. Mallick would like to thank the University of Wollongong for the International Tuition Fee Exemption Scholarship and the University Post Graduate Award (UPA), which have enabled him to undertake Ph.D. studies.

Notes

*d₅₀ : median particle size.