Experiments were conducted using a 100 mm diameter pipe loop to investigate the deposition velocity (V c ) of settling slurries in inclined pipe flows up to 208 (36.4 %). Slurries which comprised silica sand or gravel (0.1-8 mm) and water were tested at solids concentrations between 6-40 % by volume (
Experiments were performed in a 265 mm diameter pipe loop with sand‐in‐water slurries (d50 = 0.371 mm). In situ solids volumetric concentrations ranging from 20–40 % by volume (0.20–0.45 L/L) and mixture velocities up to 6 m/s were tested. Measurements of the instantaneous and average solids velocity and turbulent intensity profiles across the centreline diameter of the pipe were obtained using a particle velocity probe. A CFD package, ANSYS CFX 14, was used to perform numerical simulations. Solids turbulent intensities were found to be greater near the bottom of the pipe where solids concentrations are typically higher and significant particle‐pipe wall interactions occur. The agreement between the numerical results and the experimental data was found to be concentration dependent, with relatively closer agreement at lower concentrations.
In this study a state-of-the-art gamma-ray tomography (GRT) unit was used to measure the solids concentration distributions of high density, high attenuation clay/water/sand slurries in a 4 in. (100 mm) diameter recirculating pipe loop. The presence of neighbouring radiation sources on the GRT results in a scattered radiation contribution to the total intensity measured at each detector. The scattered radiation decreases the signal-to-noise ratio of the measured radiation intensity and introduces error in the measured tomography data and the reconstructed tomograms (Maad et al 2008 Meas. Sci. Technol.
19 6). Because of the high attenuation of the materials being measured, the scatter contribution was a significant fraction of the total radiation measured at each detector. To correct for the scattered radiation contribution in the measurements, a test campaign was undertaken to characterize and model the scattering behaviour of the GRT at the Saskatchewan Research Council. The scattered radiation was measured experimentally from empty pipe, water filled pipe and a number of flowing clay/water/sand slurries at densities ranging from 1206 kg m−3 to 1580 kg m−3. A semi-empirical scatter correction model has been developed which allows the scattered contribution at each detector to be calculated iteratively based on the measured uncorrected attenuated radiation intensity. This article is an extension of the work presented at the 9th World Congress for Industrial Process Tomography (Spelay et al 2018 Proc. 9th World Congress Industrial Process Tomography p 14).
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