SciELO - Scientific Electronic Library Online

vol.108 issue10Applications of electrical tomography to improve the performance of crystallization, precipitation and mixing processes author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Journal of the Southern African Institute of Mining and Metallurgy

On-line version ISSN 2411-9717
Print version ISSN 0038-223X

J. S. Afr. Inst. Min. Metall. vol.108 n.10 Johannesburg Oct. 2008




Determining concentration and velocity profiles of non-Newtonian settling slurries using electrical resistance tomography



A.P.N. SutherlandI; T.M. LongII; E.W. RandallIII; A.J.WilkinsonII

IDepartment of Civil Engineering, Cape Peninsula University of Technology
IIDepartment of Electrical Engineering, University of Cape Town
IIIDepartment of Chemical Engineering, University of Cape Town




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.



“Full text available only in PDF format”




ADLER, A. and LIONHEART, W.R.B. Uses and abuses of EIDORS: an extensible software base for EIT. Physiological Measurement, vol. 27 no. 5, 2006. pp. S25-S42.         [ Links ]

BARBER, D.C., BROWN, B.H. and FRESTON, I.L. Imaging spatial distributions of resistivity using applied potential tomography. Electronics Letters, vol. 19, 1983. pp. 993-995.         [ Links ]

CHENEY, M., ISAACSON, D., NEWALL, J.C., SIMSKE, S. and GOBLE, J. NOSER: An algorithm for solving the inverse conductivity problem. International Journal of Imaging Systems and Technology, vol. 2 no. 2, 1990. pp. 66-75.         [ Links ]

COOKE, R. Laminar flow settling: the potential for unexpected problems. Proc: 15th Int. Conf. on Hydrotransport, Banff, Canada, 2002. pp. 121-133.         [ Links ]

DENG, X., DONG, L., XU, L.J., LIU, X.P. and XU, L.A. The design of a dualplane ERT system for cross correlation measurement of bubbly gas/liquid pipe flow. Measurement Science and Technology, vol. 12 no. 8, 2001. pp. 1024-1031.         [ Links ]

DYAKOWSKI, T., JEANMEURE, L.F.C. and JAWORSKI, A.J. Applications of electrical tomography for gas-solids and liquid-solids flows - a review. Powder Technology, vol. 112, 2000. pp. 174-192.         [ Links ]

FFTW (The Fastest Fourier Transform in the West),         [ Links ]

HENNINGSSON, M., OSTERGREN, K. and DEJMEK, P. Plug flow of yoghurt in piping as determined by cross-correlated dual-plane electrical resistance tomography. Journal of Food Engineering, vol. 76 no. 2, 2006. pp. 163-168.         [ Links ]

HUA, P. and WOO, E. Electrical Impedance Tomography. The Adam Hilger Series on Biomedical Engineering. Bristol: IOP Publishing Ltd. 1990. pp. 97-136.         [ Links ]

LONG, T.M. The development of an online velocity flow profiling system using electrical resistance tomography. Master's thesis, University of Cape Town. 2006.         [ Links ]

LONG, T.M., WILKINSON, A.J., RANDALL, E.W. and SUTHERLAND, A.P.N. An Online Real-time Velocity Profiling System using Electrical Resistance Tomography. Proceedings of 5th World Congress on Industrial Process Tomography, Bergen. 2007.         [ Links ]

LUCAS, G.P., CORY, J., WATERFALL, R.C., LOH, W.W. and DICKIN, F.J. Measurement of the solids volume fraction and velocity distributions in solids-liquid flows using dual-plane electrical resistance tomography. Flow Measurement and Instrumentation, vol. 10 no. 41, 999. pp. 249-258.         [ Links ]

MATOUSEK, V. Research Developments in Pipeline Transport of Settling Slurries. Proc: 12th Int. Conf. on Transport and Sedimentation of Solid Particles, Prague (Czech Republic), 2004. pp. 19-34.         [ Links ]

MOSOROV, V., SANKOWSKI, D., MAZURKIEWICZ, L. and DYAKOWSKI, T. The 'bestcorrelated pixels' method for solid mass flow measurements using electrical capacitance tomography. Measurement Science and Technology, vol. 13 no. 12, 2002. pp. 1810-1814.         [ Links ]

POLYDORIDES, N. and LIONHEART, W.R.B. A MATLAB toolkit for threedimensional electrical impedance tomography: a contribution to the electrical impedance and diffuse optical reconstruction software project. Measurement Science and Technology, vol. 13 no. 12, 2002. pp. 1871-1883.         [ Links ]

PULLUM, L. and GRAHAM, L.J.W. A new high-concentration pipeline test loop facility. Proc: 14th Int. Conf. on Slurry Handling and Pipeline Transport, Maastricht, The Netherlands, 1999. pp. 504-514.         [ Links ]

PULLUM, L. and GRAHAM, L.J.W. Predicting fine particle suspension performance - the case for pipe tests. Proc: 15th Int. Conf. on Hydrotransport, Banff, Canada, 2002. pp. 109-120.         [ Links ]

RANDALL, E.W., WILKINSON, A.J., LONG, T.M. and SUTHERLAND, A.P.N. The UCT Electrical Resistance Tomography Instrument and Its Applications. The Southern African Institute of Mining and Metallurgy, Tomographic Symposium, 25 July 2008.         [ Links ]

WANG, M. Inverse solutions for electrical impedance tomography based on conjugate gradients methods. Measurement Science and Technology, vol. 13 no. 1, 2002. pp. 101-117.         [ Links ]

WANG, M., MA, Y., HOLLIDAY, N., DAI, Y., WILLIAMS, R. and LUCAS, G. A high performance EIT system. IEEE Sensors Journal, vol. 5 no. 2, 2005. pp. 289-299.         [ Links ]

WILKINSON, A.J., RANDALL. E.W., CILLIERS, J.J., DURRETT, D., NAIDOO, T. and LONG. T.M. A 1000-measurement frames/second ERT data capture system with real-time visualization. IEEE Sensors Journal, vol. 5 no. 2, 2005. pp. 300-307.         [ Links ]

wxWidgets,         [ Links ]

YANG, W.Q. and BECK, M.S. An intelligent cross correlator for pipeline flow velocity measurement. Flow Measurement and Instrumentation, vol. 8 no. 2, 1998. pp. 77-84.         [ Links ]

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License