Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
SUTHERLAND, A.P.N.; LONG, T.M.; RANDALL, E.W. and WILKINSON, A.J.. Determining concentration and velocity profiles of non-Newtonian settling slurries using electrical resistance tomography. J. S. Afr. Inst. Min. Metall. [online]. 2008, vol.108, n.10, pp. 583-590. ISSN 2411-9717.
Pipelines for transporting high concentration slurries are often designed using methods applicable to homogeneous non-Newtonian laminar flow. Many industrial slurries though comprise coarse particles in a non-Newtonian carrier fluid, and existing experimental evidence from tests with such slurries demonstrates that they are not homogeneous. Under laminar shear conditions the coarse particles settle, even in statically stable carrier fluids. To understand this better, the Institute of Materials Science and Technology (IMST) at Cape Peninsula University of Technology (CPUT) is conducting ongoing research into the flow of these high concentration non-Newtonian settling slurries. Since pressure gradient and flow rate measurements alone are insufficient to adequately model the flows, an electrical resistance tomography (ERT) instrument developed by the University of Cape Town (UCT) was incorporated into the pipe test loop to determine pipe crosssection concentration and velocity profiles. The software developed to do this is modular and allows different image reconstruction and cross-correlation algorithms to be implemented and tested without significantly changing the rest of the application. At a total frame capture rate of 566 frames/sec a 2.67 GHz Intel Celeron processor with 500 MB of RAM is fast enough to calculate and display velocity profiles in 'real-time' at an update rate of one profile every two seconds. Examples of experimental concentration and velocity profiles obtained using the system are shown and some proposed improvements/extensions to the system are listed.