Thesis (MTech (Chemical Engineering))--Cape Technikon, Cape Town,1996 / The handling of solid-liquid suspensions is an important concern within the chemical and
processing industries and many theoretical models have been proposed to try and explain and
predict turbulent flow behaviour. However, the prediction of turbulent flow from only the
viscous properties of non-Newtonian suspensions has over the years been questioned by
researchers. This thesis considers theoretical models well established in the literature and
the Slatter model, which uses both the rheology of the suspension and the particle size
distribution of the solids. These models are used to analyze the experimental data and the
effect that particle size and the particle size distribution has on turbulent flow behaviour.
The literature concerning the rheological fundamentals relevant to fluid flow in pipes has
been examined. The Newtonian turbulent flow model as well as the non-Newtonian models
of Dodge & Metzner, Torrance, Kemblowski & Kolodziejski, Wilson & Thomas and Slatter
have been reviewed.
Test work was conducted at the University of Cape Town's Hydrotransport Research
Laboratory using a pumped recirculating pipe test rig. The test apparatus has been fully
described and calibration and test procedures to enable collecting of accurate pipeline data
have been presented. Three slurries were used in test work namely kaolin clay, mixture I
(kaolin clay and rock flour) and mixture 2 (kaolin clay, rock flour and sand) with ad,s
particle size ranging from 24/Lm to 170/Lm.
The yield pseudoplastic model has been used to model and predict the laminar flow of the
suspensions that were tested and the meth9J adopted by Neill (1988) has been used to
determine the rheological constants. The pipeline test results have been presented as pseudoshear
diagrams together with the theoretical model lines providing a visual appraisal of the
performance of each model. The Slatter model predicts the test data best with the other
theoretical models that were considered tending to under predict the head loss. The reason
the Slatter model performs better than the other theoretical models is because this model can
account for the wall roughness and particle roughness effect. Evidence to support this
statement has been presented.
This thesis highlights the fact that the particle size distribution is a vitally important property
of the suspension and that it does influence turbulent flow behaviour. It shows that
turbulence modelling using the particle roughness effect (eg Slatter, 1994) is valid and can
be adopted for non-Newtonian slurries. It is concluded that the particle size distribution must
be used to determine the particle roughness effect and this effect must be incorporated in the
turbulent flow analysis of non-Newtonian slurries.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:cput/oai:localhost:20.500.11838/896 |
| Date | January 1996 |
| Creators | Thorvaldsen, Gary Sven |
| Publisher | Cape Technikon |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | http://creativecommons.org/licenses/by-nc-sa/3.0/za/ |
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