Effect of particle size distribution on pressure drop and concentration profile in pipeline flow of highly concentrated slurry

Solids concentration profiles and pressure drop in pipeline flow of multisized particulate slurries

The behavior of horizontal solid−liquid (slurry) pipeline flows was predicted using a transient three-dimensional (3D) hydrodynamic model based on the kinetic theory of granular flows. Computationa...

Hydrodynamic Simulation of Horizontal Slurry Pipeline Flow Using ANSYS-CFX

The well-known two-layer model for predicting friction losses for pipeline flows of settling slurries has been extended to solids concentrations above 35% by volume. This has been achieved by incorporating new experimental results to account for increases in friction which have been observed with “settling” slurries at high concentrations. The kinetic (fluid-like) friction appears to increase with solids concentration in a manner which suggests that particle-wall contact plays an important role. The experiments also suggest that the fraction of the total solids which contributes Coulombic (velocity insensitive) friction also increases to some extent at high concentrations. This effect is expressed in a tentative correlation which employs a slurry Reynolds number. In addition, new experimental measurements of delivered and in-situ concentrations have been used to test predictions made with the previous version of the model. The measurements show that the interracial friction factor proposed recently by Wilson and coworkers is preferable for slurries of coarse particles.



Le modele a deux couches bien connu pour la prediction des pertes par frottement dans les ecoulements des boues de decantation dans les conduites a ete etendu aux concentrations de solides superieures a 35% en volume. Ceci a ete realise en introduisant de nouveaux resultats experimentaux afin de tenir compte des augmentations de frottement qui ont ete observers avec des boues de “decantation” a de fortes concentrations. Le frottement cinetique (semblable a un fluide) semble augmenter avec la concentration de solides d'une facon qui laisse penser que le contact particules-paroi joue un role important. Les experiences semblent egalement montrer que le fraction des solides totaux qui contribue au frottement de Coulomb (insensible a la vitesse) augmente egalement dans une certaine mesure a de fortes concentrations. Cet effet est exprimee dans une correlation provisoire basee sur un nombre de Reynolds des boues. En outre, on a eu recours a de nouvelles mesures experimentales de concentrations indirectes et in situ pour tester les predictions realisees a l'aide de la version precedente du modele. Ces mesures montrent que le facteur de frottement interracial recemment propose par Wilson et ses collegues est preferable pour des suspensions de particules grossieres.

Modelling high concentration settling slurry flows

https://ctflab.mae.cornell.edu/papers/Capecelatro,%20Desjardins.%202013.%20Eulerian-Lagrangian%20modeling%20of%20turbulent%20liquid-solid%20slurries%20in%20horizontal%20pipes.pdf

Eulerian–Lagrangian modeling of turbulent liquid–solid slurries in horizontal pipes

Experiments have been conducted to assess the effect of particle shape on pipeline friction in turbulent flow, using laboratory pipelines of nominal diameter 50 mm and 150 mm. The experiments were intended to examine the extent to which a fluid model is appropriate for slurries of this type, especially at high solids concentrations. The experiments confirm that fluid friction at low and moderate solids concentrations is proportional to slurry density, with particle shape being of minor importance. At high solids concentrations, additional increases in friction are observed and these depend upon the ratio of the solids concentration to the maximum settled concentration. Although this friction increase is qualitatively similar to that which would result from increased slurry viscosity, the evidence suggests that particle-wall contact is the mechanism. However, the transition from turbulent to laminar flow indicates that an effective viscosity should be used in calculating critical Reynolds numbers.



Afin d'evaluer l'effet de la forme des particules sur le frottement dans les pipelines en regime turbulent, des experiences ont ete menees avec des pipelines de laboratoire d'un diametre nominal de 50 mm et de 150 mm. Le but de ces experiences etait de voir jusqu'a quel point un fluide modele est approprie pour ce type de suspensions, en particulier a de fortes concentrations de solides. Les experiences confirment que le frottement du fluide a des concentrations de solides faibles ou moyennes est proportionnel a la masse volumique des suspensions, la forme des particules etant de peu d'importance. A de fortes concentrations de solides, on observe un accroissement supplementaire du frottement qui est lie au rapport entre la concentration de solides et la concentration sedimentee maximum. Bien que cette augmentation du frottement soit d'un point de vue qualitatif semblable a ce qu'il reulterait d'une viscosite accrue des suspensions, selon toutes les apparences le mecanisme reside dans le contact particules-paroi. Cependant, la transition de l'ecoulement turbulent a l'ecoulement laminaire indique qu'une viscosite effective devrait ##etre utilisee dans le calcul des nombres de Reynolds critiques.

The effect of particle shape on pipeline friction for newtonian slurries of fine particles

In this contribution both new and previously published deposition velocity data for aqueous Newtonian slurries are incorporated in a correlation which complements the earlier predictions of Durand, Wilson and A.D. Thomas. Most of the new data has been obtained for slurries of narrowly sized sand particles of median diameter ranging between 90 and 420 μm, in pipes of diameter between 0.05 and 0.5 m. The data were obtained in laboratory investigations under isothermal flow conditions.



Dans ce travail de contribution, de nouvelles donnees et des donnees publiees anterieurement sur la vitesse de deposition de suspensions newtoniennes aqueuses sont introduites dans une correlation qui vient completer les predictions anterieures de Durand, Wilson et A.D. Thomas. La plupart des nouvelles donnees ont ete obtenues pour des suspensions de particules de sable presque monodisperses dont le diametre varie entre 90 et 420 μm, dans des conduites d'un diametre compris entre 0,05 et 0,5 m. Ces donnees ont ete obtenues lors de recherches en laboratoire dans des conditions d'ecoulement isothermes.

Deposition velocities for newtonian slurries in turbulent flow

Experiments conducted with water slurries of 1 mm particles of specific gravity 1.59 in a laboratory pipeline 0.105 m in diameter have provided evidence of a change in the friction mechanism at velocities above 3 m/s. These flows were stratified and at low velocities the frictional pressure gradients were in satisfactory agreement with the predictions of the conventional two-layer model. However at higher velocities the friction is substantially lower than predicted. Measurements of concentration and velocity distributions within the pipe show that no major change in flow regime occurs concurrently with the change in the friction mechanism. It appears that the effect is due to a change in the nature of the particle-wall interaction, of a type which suggests that an inward-acting force affects the particles adjacent to the wall.

Jason Schaan

Papers

The effect of particle shape on pipeline friction for newtonian slurries of fine particles

Deposition velocities for newtonian slurries in turbulent flow

Anomalous friction in slurry flows