Please use this identifier to cite or link to this item: http://hdl.handle.net/11189/2613
Title: A system to estimate coarse particle velocities at the pipe wall in settling slurry flow
Authors: Kotzé, Michal
Sutherland, Andrew
Kotzé, Reinhardt
Keywords: settling slurry;deposition probe;particle (bed) velocity;cross-correlation;non-Newtonian
Issue Date: 2013
Source: Kotzé, M., Sutherland, A., & Kotzé, R. (2013). A system to estimate coarse particle velocities at the pipe wall in settling slurry flow. Flow Measurement and Instrumentation, 32, 63-70.
Abstract: Understanding and modelling of coarse particle (settling) slurries in laminar flow in pipes is still not complete. Better analytical procedures will enable more efficient pipeline operation which could result in significant power savings in the transport of coarse materials. The depth and velocity of the settled bed significantly affect the pressure gradients required to pump these slurries and knowledge of these parameters is of importance. Existing measurement techniques that can be used for monitoring of these complex fluid systems are either very expensive, not easy to implement or mostly used under controlled laboratory conditions. A new measurement system was developed that is capable of detecting the deposition of solids, the depth of a settled bed and the velocity of coarse particles at the pipe wall, around the pipe circumference. Particle velocities were determined by cross-correlating modulated signals from pairs of electrodes mounted flush with the pipe wall, in contact with the slurry. Tests were conducted using a mixture of acetal beads in water, at bulk velocities between 0.5 and 4 m/s. Estimated particle velocities from the cross-correlation analyses were compared with those obtained using a 30 fps video camera combined with visual inspection, and found to be within ±6%, thus validating the viability of the system. Particle velocity resolution using the cross-correlation technique is limited by block size, sample rate and the measurement distance between electrode pairs. Further test work with a range of real slurries (different particle sizes, solids concentrations and rheologies) needs to be conducted, along with more extensive verification of the results, to establish the limits of the system. Initial testing and evaluation of the system, which is capable of coarse particle flow monitoring in real time, showed significant potential for development of a new commercial sliding bed detector that can be used in a wide range of industrial applications in which particles are transported hydraulically.
URI: http://hdl.handle.net/11189/2613
Appears in Collections:Eng - Journal articles (DHET subsidised)

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