Concentration profiling of a horizontal sedimentation tank utilising a bespoke acoustic backscatter array and CFD simulations

Hunter, Timothy N.; Peakall, Jeff; Egarr, D. A.; Cowell, David M. J.; Freear, Steven; Tonge, Alastair S.; Horton, Lucy; Rice, Hugh P.; Smith, Iain; Malone, Kevin F.; Burt, David; Barnes, Martyn; Randall, G; Biggs, Simon; Fairweather, Michael

doi:10.1016/j.ces.2020.115560

Cited by 17 publications

(21 citation statements)

References 73 publications

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“…The measurement of supernatant turbidity has long been used to evaluate the extent of flocculation, but the relationship between turbidity of the supernatant and the properties of the aggregates is not well defined [16]. A recent work has improved upon acoustic backscatter technology for solids concentration measurement using an ultrasonic backscatter instrument with a transducer array to generate concentration profiles for a large-scale horizontal sedimentation tank [17]. Floc chord length distributions, measured with the focused beam reflectance measurement technique (FBRM), are useful for evaluating flocculation or aggregation in flowing suspensions [18].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Kaolin Flocculation in Seawater by Optical Backscattering Measurements: Effect of Flocculant Management and Liquor Conditions

Jeldres

MacIver

et al. 2020

Minerals

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Optical backscattering (OBS) signal values were used to evaluate the flocculation of kaolin slurries and seek the implications of using seawater. Two anionic flocculants were applied to kaolin suspensions at several dosages and in water of varying pH and electrolyte concentration. An OBS height scan method was used to estimate the degree of aggregation, supernatant quality, and solids concentration of the sediments. The residual solids of the supernatant depended of the extent of particle coagulation before flocculant was added, where the pH and salinity displayed a significant impact on flocculation. The OBS results were highly sensitive to the presence of fine particles, which was estimated in parallel from the focused beam reflectance measurements (FBRM.) In seawater, without flocculant added, the samples had increased root-mean-square scattering (Frms) values and larger final sediment volume than samples prepared in water with lower electrolyte concentration. This indicates a higher initial state of aggregation of the particles in seawater. Then, the aggregation degree was best linked to the square-weighted chord length distribution of the FBRM data, which intensifies the sensitivity to coarse aggregates.

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Section: Introductionmentioning

confidence: 99%

Analysis of Kaolin Flocculation in Seawater by Optical Backscattering Measurements: Effect of Flocculant Management and Liquor Conditions

Jeldres

MacIver

et al. 2020

Minerals

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“…5 as basis. Their primary applications have been geared towards sediment flows/transport and in a recent endeavour, an array of acoustic backscatter systems was deployed in profiling a large-scale laboratory experiment (Hunter et al 2020). However, as argued by Saint-Michel et al (2017), the validity of Eq.…”

Section: Work(s)mentioning

confidence: 99%

Ultrasonic particle volume fraction profiling: an evaluation of empirical approaches

2021

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We discuss empirical techniques to extract quantitative particle volume fraction profiles in particle-laden flows using an ultrasound transducer. A key step involves probing several uniform suspensions with varying bulk volume fractions from which two key volume fraction dependent calibration parameters are identified: the peak backscatter amplitude (acoustic energy backscattered by the initial layer of the suspension) and the amplitude attenuation rate (rate at which the acoustic energy decays with depth owing to scattering losses). These properties can then be used to reconstruct spatially varying particle volume fraction profiles. Such an empirical approach allows circumventing detailed theoretical models which characterize the interaction between ultrasound and suspensions, which are not universally applicable. We assess the reconstruction techniques via synthetic volume fraction profiles and a known particle-laden suspension immobilized in a gel. While qualitative trends can be easily picked up, the following factors compromise the quantitative accuracy: (1) initial reconstruction errors made in the near-wall regions can propagate and grow along the reconstruction direction, (2) multiple scattering can create artefacts which may affect the reconstruction, and (3) the accuracy of the reconstruction is very sensitive to the goodness of the calibration. Despite these issues, application of the technique to particle-laden pipe flows shows the presence of a core with reduced particle volume fractions in laminar flows, whose prominence reduces as the flow becomes turbulent. This observation is associated with inertia-induced radial migration of particles away from the pipe axis and is observed in flows with bulk volume fractions as high as 0.08. Even transitional flows with low levels of intermittency are not devoid of this depleted core. In conclusion, ultrasonic particle volume fraction profiling can play a key complementary role to ultrasound-based velocimetry in studying the internal features of particle-laden flows. Graphic abstract

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“…CaCO3 is non-hazardous test material with a similar structure to common fine sludges [4]. It has also been extensively utilized as an analogue for nuclear wastes in experiments [5], which limits the risk of working with active sediment in non-controlled environments [6].…”

Section: Introductionmentioning

confidence: 99%

“…For a more industrially relevant system, this work considers aggregated and flocculated CaCO3 suspensions, using high molecular weight anionic polymers [9]. Addition of flocculant changes the suspension d50 to more than seven times its original value (from ~7 μm to 54 μm) [5] allowing analysis of suspensions with different size distributions. The specific ABS used is a commercial ultrasonic velocity profiler (UVP) [10].…”

Section: Introductionmentioning

confidence: 99%

Characterizing Flocculated Suspensions with an Ultrasonic Velocity Profiler in Backscatter Mode

Hussain

Peakall

Barnes

et al. 2021

2021 IEEE International Ultrasonics Symposium (IUS)

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Concentration profiling of a horizontal sedimentation tank utilising a bespoke acoustic backscatter array and CFD simulations

Abstract: This is a repository copy of Concentration profiling of a horizontal sedimentation tank utilising a bespoke acoustic backscatter array and CFD simulations.

Cited by 17 publications

References 73 publications

Analysis of Kaolin Flocculation in Seawater by Optical Backscattering Measurements: Effect of Flocculant Management and Liquor Conditions

Analysis of Kaolin Flocculation in Seawater by Optical Backscattering Measurements: Effect of Flocculant Management and Liquor Conditions

Ultrasonic particle volume fraction profiling: an evaluation of empirical approaches

Characterizing Flocculated Suspensions with an Ultrasonic Velocity Profiler in Backscatter Mode

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