Gravitational discharge of fine dry powders with asperities from a conical hopper |
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| Authors: | Hui Lu Jia Zhong Gui‐Ping Cao Hai‐Feng Liu |
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| Affiliation: | 1. UNILAB, State Key Lab of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, People's Republic of China;2. Key Laboratory of Coal Gasification and Energy Chemical Engineering of Ministry of Education, East China University of Science and Technology, Shanghai 200237, People's Republic of China;3. Shanghai Engineering Research Center of Coal Gasification, East China University of Science and Technology, Shanghai 200237, People's Republic of China |
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| Abstract: | The effects of particle properties, especially the surface roughness and particle type, on the gravity discharge rate and flow behavior of fine dry powders from a conical hopper are studied in detail. The van der Waals force is considered to dominate the discharge of small particles, while the empty annulus effect dominates the discharge of large particles. To predict the van der Waals force between two rough spherical particles, a model based on Rumpf theory is adopted. The effect of surface roughness can be reflected by Bond number Bog which is correlated with discharge rate. By modifying the powder bed porosity and Beverloo constant, the discharge rates of fine dry powders can be well predicted by an empirical correlation. Finally, not only the ratio of hopper outlet size to particle size D0/dp but also the Bond number Bog is found to be an important indicator to determine the powder flowability. © 2017 American Institute of Chemical Engineers AIChE J, 64: 427–436, 2018 |
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| Keywords: | fine dry powders surface roughness van der Waals force Bond number powder flowability |
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