Experimental investigation on effects of solid concentration, chemical additives, and shear rate on the rheological properties of bottom ash (BA) slurry

ABSTRACT

An experimental analysis is done for understanding the effect of various parameters like shear rate, solid concentration, and particle size on rheological behavior of bottom ash slurry. The coarser-sized bottom ash slurry has the settling characteristics and that leads to sedimentation of solid particles during the flow of slurry in the pipeline. This effect results in high pressure drop and also the sedimentation bed needs more power for flow in pipeline. In the current study, rheological behavior of bottom ash slurry is experimentally analyzed with and without addition of chemical additives. Cetyl Trimethyl Ammonium Bromide (CTAB) with Sodium Salicylate (NaSal) is used as chemical additives with a range 0.1%–1.0% by mass of total slurry sample. It is observed that all the BA slurry samples at 30% and 40% solid mass concentration shows non-Newtonian nature and follows Herschel-Bulkley model with shear thickening behaviors. It is also observed from the experimental result that the rheological properties of BA slurry are very much affected by shear rate. Combined effect of various range of BA solid mass concentration, shear rate, and dosages of chemical additives were investigated and get encouraging results.

KEYWORDS:

• Slurry transportation
• sedimentation
• rheological behavior
• chemical additive
• shear rate

Nomenclature

$\tau$ =	=	Shear stress
${\tau }_o$ =	=	Yield stress,
n=	=	flow behavior index
$K$ =	=	Consistency index
$\gamma$ =	=	Shear rate
Sg =	=	Average specific gravity
d50 =	=	Mean diameter of FA particles
Cw =	=	Solid particle concentration by weight
PSD =	=	Particle size distribution