López, A, Vivacqua, V, Hammond, R et al. (1 more author) (2020) Analysis of screw feeding of faceted particles by discrete element method. Powder Technology, 367. pp. 474-486. ISSN 0032-5910
Abstract
Reliable and consistent powder flow in screw feeders is of great interest to a wide range of industries, particularly for continuous manufacturing of pharmaceutical powders. However, analysis of flow of cohesive powders with sharp corners and edges, as commonly found in the case of crystalline solids, presents a great challenge due to complexity of shape and its influence on flow. In the present work, the influence of particle shape and cohesion on phenomena such as cohesive arching in hoppers and screw feeder pitches is analysed by numerical simulations using the Discrete Element Method, and their impact on the outlet mass flow rate is evaluated. Faceted and spherical particles with different cohesion levels are generated and allowed to settle in a hopper on top of a screw feeder. The screw is then rotated, thus feeding the particles through the barrel. Particle interactions are analysed numerically for the hopper region, a predominantly slow-flow regime, and for the pitches of the screw feeder, where a speed-dependent regime prevails.
Paracetamol crystal shape is taken as a model faceted shape. Its parameters such as the coefficients of restitution and friction, needed for the simulations, are calibrated by experimental work.
Transient arching occurs as the level of cohesion is increased. The frequency of formation and collapse of arches within the hopper region increases, and eventually, permanent arching is observed. Analysis of stress and strain rate in the screw barrel region shows that the shear stress is a weak function of the shear rate with a power index of around 0.3, which is independent of particle shape. The flow rate is influenced considerably by particle shape, whilst increased cohesion causes an increase in void fraction and affects transient arching.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 Elsevier B.V. All rights reserved.. This is an author produced version of an article published in Powder Technology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | DEM; Screw feeder; Cohesion; Faceted particles; Powder flow |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) |
Funding Information: | Funder Grant number Innovate UK fka Technology Strategy Board (TSB) 14060 |
Depositing User: | Symplectic Publications |
Date Deposited: | 06 Apr 2020 14:18 |
Last Modified: | 03 Apr 2021 00:38 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.powtec.2020.03.064 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:159188 |
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