Hydraulic Transport of Fly Ash Slurry (2nd Report)

Flow pressure drop of fly ash slurry containing coarse particles in pipes

Abstract

The purposes of this investigation are to measure the pipe pressure drop of fly ash slurry containing coarse particles and to measure the torque of a rotating cylinder in the packed coarse particles submerged with the fine slurry.
In order to make a comparison between flow pressure drop of the fly ash slurry and that of the fly ash slurry with coarse particles in pipes, some experiments were carried out in horizontal 2B and 4B pipe lines.
The result shows that under the same total volumetric concentration of solids the pressure drop decreases by adding coarse particles, especially at higher velocity and at higher conventration of coarse particles.
It is well known that some of fine particles as an additive to settling slurry bring the reduction of the pressure loss. Experimental results are also analyzed from this point of view.
The same result was obtained throughout the concentration of fly ash from 10 vol.% to 40 vol.% at low velocity, however, the most effective reduction of the pressure drop was achieved at lower fly ash concentration and at higher coarse particle concentration.
One the assumption that the reduction is due to the lubricant effect of fine particle, the torque of the rotating cylinder in the packed coarse particles mixed with fine slurry was measured.
The reduction of torque was very similar to the decrease of the pressure drop in pipes presented by several researchers.