Direct prediction of fall velocities in non-Newtonian materials

Wilson, Kenneth; Horsley, R. R.; Kealy, Timothy; Reizes, John; Horsley, Michael

doi:10.1016/s0301-7516(03)00027-9

Cited by 43 publications

(75 citation statements)

References 12 publications

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“…A new criterion was established that relates the ratio of the average surficial particle shear stress,  p , to the wall shear stress,  w . The average surficial particle shear stress (Wilson et al 2003 and the ratio are defined by the equations below. et al (2007) conclude that "a slurry's proclivity to experience laminar flow settling is greatly reduced when  w / p >60 and nearly eliminated when  w / p >100.…”

Section: The Second Reason For the Decreasing Flow In The Melter Feedmentioning

confidence: 99%

Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines

Poloski

Adkins

Abrefah

et al. 2009

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Executive SummaryThe External Flowsheet Review Team (EFRT) expressed concern about the potential for Waste Treatment and Immobilization Plant (WTP) pipe plugging. Per the review's executive summary, "Piping that transports slurries will plug unless it is properly designed to minimize this risk. This design approach has not been followed consistently, which will lead to frequent shutdowns due to line plugging." To evaluate the potential for plugging, critical-velocity tests were performed on several physical simulants to determine if the design approach is conservative. Critical velocity is defined as the point where particles begin to deposit to form a moving bed of particles on the bottom of a straight horizontal pipe during slurry transport operations. The critical velocity depends on the physical properties of the particles, fluid, and system geometry.This report gives the results from critical-velocity testing and provides an indication of slurry stability as a function of fluid rheological properties and transport conditions that are typical of what the plant will see. The experimental results are compared to the WTP design guide on slurry-transport velocity in an effort to confirm minimum waste-velocity and flushing-velocity requirements as established by calculations and critical-velocity correlations in the design guide. The major findings of this testing are as follows:Experimental results indicate that for Newtonian fluids, the design guide is conservative. The design guide is based on the Oroskar and Turian (1980) correlation, a traditional industry-derived equation that focuses on particles larger than 100 m in size. Slurry viscosity has a greater effect on particles with a larger surface area to mass ratio, i.e. smaller particles. The increased viscous forces on small particles result in a smaller critical velocities. Since the Hanford slurry particles generally have large surface area to mass ratios, the reliance on such equations in the 24590-WTP-GPG-M-0058, Rev 0 design guide (Hall 2006) is conservative. Additionally, the use of the 95% percentile particle size as an input to this equation is conservative. The design guide specifies the use of the d 95 density, this term is ambiguous and needs clarification in the design guide. Nonetheless, this value is interpreted to mean the density of the d 95 particle. This density value is irrelevant for critical velocity calculations. Often this value is unknown, and Equation 1 of the 24590-WTP-GPG-M-0058, Rev 0 design guide (Hall 2006) will be used for design purposes. This equation calculates an average or composite density of all solids in the slurry. However, test results indicate that the use of an average particle density as an input to the equation is not conservative. Particle density has a large influence on the overall critical-velocity result returned by the correlation. The viscosity correlation used in the WTP design guide has been shown to be inaccurate for Hanford waste feed materials. Additionally, the recommendation of a 30% minimum margi...

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Section: The Second Reason For the Decreasing Flow In The Melter Feedmentioning

confidence: 99%

Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines

Poloski

Adkins

Abrefah

et al. 2009

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“…However, when the same mixture is transported by pipeline, coarse-particle settling is observed. Recently, Wilson et al (2003) and Wilson and Horsley (2004) presented a concise and compelling analysis of the fall velocity of particles suspended in nonNewtonian fluids. Their analysis shows unequivocally that the same particle will have a greater fall velocity in a sheared medium than in an unsheared one.…”

Section: Settling In Laminar Flowmentioning

confidence: 99%

“…Gillies et al (2007) established a new criterion that relates the ratio of the wall shear stress,  w , to the average surficial-particle shear stress. The average surficial-particle shear stress (Wilson et al 2003(Wilson et al , 2004 and the ratio are defined by the equations below. Gillies et al (2007) conclude that "a slurry's proclivity to experience laminar flow settling is greatly reduced when  w / p >60 and nearly eliminated when  w / p >100.…”

Section: Copper Tailingsmentioning

confidence: 99%

Deposition Velocities of Non-Newtonian Slurries in Pipelines: Complex Simulant Testing

Poloski¹,

Bonebrake²,

Casella³

et al. 2009

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“…To cover both Newtonian and non-Newtonian cases, the method described by Wilson et al [6] and Wilson and Horsley [7] uses as dimensionless variables the ratio of fall velocity to shear velocity and the shear Reynolds number of the particle. The shear Reynolds number of the particle Re Ã is written as follows:…”

Section: Revised Particle Settling Model By Wilson and Horsleymentioning

confidence: 99%

“…The models based on variants of this analysis include those by Shook and others at the Saskatchewan Research Council (for comparison, see Wilson et al [5] ). Among others, the friction model used in the GIW Industries Inc. short course initially relied on particle fall velocity as a metric for friction losses, but the classical method of determining fall velocity, which involves inconvenient iteration, has now been replaced by a non-iterative method developed by Wilson et al [6] and Wilson and Horsley [7] as detailed in the following section.…”

mentioning

confidence: 99%

Developments in slurry flow modelling in a historical perspective

Wilson¹,

Sellgren

2016

Can J Chem Eng

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Durand's slurry flow model attempted to find a single formula for sand-size particles and larger, but Babcock's data showed that a single formula could not apply. A subsequent group of models is based on Wilson's layered force-balance analysis of slurry flows applied to friction losses and deposition limit. Models based on variants of this analysis include those by Shook and others at the Saskatchewan Research Council (SRC). Early versions of Wilson's model relied on particle fall velocity to find friction losses, but the classical iterative method of finding fall velocity has now been replaced by a direct method. This is based on the shear Reynolds number of the particle, which can be expressed in terms of the better known Archimedes number. Thus, calculations of slurry friction and limit of deposition involve two principal parameters: the Archimedes number and the diameter ratio d/D.

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Direct prediction of fall velocities in non-Newtonian materials

Cited by 43 publications

References 12 publications

Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines

Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines

Deposition Velocities of Non-Newtonian Slurries in Pipelines: Complex Simulant Testing

Developments in slurry flow modelling in a historical perspective

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