Build-up is a fouling process in which a small fraction of a powder becomes a film adhered to a surface. Specifically buildup in auger fillers which is the focus of this thesis is a significant problem for industry leading to equipment downtime for cleaning, drives tripping due to high torque and reduced powder quality. The work presented in this thesis shows that for a unblended powder with a particle size similar to that of the auger fillers auger/tube clearance, build-up will be formed when powders have b-1 Kawakita parameter of less than 0.5 MPa and tablet strengths below 0.6 MPa post compression to 58 MPa. It is proposed based upon results the work of Crutchley and Bridgewater [29] and Calvert et al. [30] that powders which form build-up due so due to the stresses they experience as they pass through the auger/tube clearance. Additionally this stress is a function of the ratio of the powder’s particle size to the magnitude of the auger/tube clearance C. Work presented in Chapter 8 supports this conclusion showing that once C/D90 is greater than 3.5, build-up is not formed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:690821 |
| Date | January 2016 |
| Creators | Hewitt, Christopher David |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/6851/ |
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