Suspension of Particles from the Bottom of Pipes and Stirred Tanks by Gassed and Ungassed Flows

Abstract

Widely accepted correlations and theoretical predictions for hydraulic conveying of solids in pipelines are compared with the literature on the suspension of particles in stirred tanks. Good agreement is found between the correlations and the theoretical predictions both within and between the two fields of study. The effect on the suspension velocity of introducing gas into the pipe and the stirred tank is remarkably similar. In both cases, the shear stress remains broadly unchanged when gas is added. Since the effect of the addition of gas on shear stress is quite well understood in both cases, this is a helpful result.

CFD-DEM simulations of early turbulent solid–liquid mixing: Prediction of suspension curve and just-suspended speed

“…The particles were glass beads, which are considered spherical, with a Sauter diameter (d p,32 ) of 3.02 mm at a 10% w/w loading 125 in a Newtonian glucose solution of viscosity µ of 0.0516 Pa.s. There is some evidence that for large particle diameter to impeller tank ratio (d p /T ), the just suspended speed becomes independent of the particle diameter [50]. This could possibly be the case for this set-up.…”

Properties Important to Mixing for WTP Large Scale Integrated Testing

“…31 For specific systems, particle shape influences removal of particles from a stationary bed by a liquid. 32 For some systems, the effect of particle shape on particle suspension can be less pronounced for higher solids (i.e. 10 wt% UDS) loadings than for low solids loadings (isolated particles).…”

“…10 wt% UDS) loadings than for low solids loadings (isolated particles). 32 Particle shape is one of the factors that influence the shear strength of a settled layer. 21 This influence can be due to factors such as surface forces, friction, and solids packing.…”

Experimental and Computational Investigation of Flow Fields using Accelerated Erosion Test Ring (AETR)

“…(Khazam and Kresta, 2009) used three impellers of two diameters and compared the full baffle configuration with two partial height baffle arrangements and found that the performance of surface baffles is superior to full or half baffled configurations. (Thorpe and Stevenson, 2003) studied the mechanism of suspension of particles in pipes and stirred vessels and reported that the shear stresses, due to the suspension of particles, are comparable in both cases. (Gupta et al , 1995) used pot tester and conducted experiments to analyze the effect of sand concentration, particle size and velocity of fluid.…”