Investigation of Flow Characteristics of Coal Water Slurry

Abstract

The present study on the coal-water slurry rheology and its transportation performance was conducted at the Mechanical Engineering Department, Thapar University, Patiala. The rheological behaviour of Indian coal sample was investigated by using Anton Paar RheolabQC rheometer to generate extensive rheological data with a perspective to study the effect of solids concentration, temperature, and fraction of coarse particles. The rheological data obtained was used to evaluate the pressure drop of coal water slurry flowing through straight pipe using ANSYS FLUENT 14.5 computational fluid dynamics code. The slurry flow behaviour was found to be shear thinning above 30 % solids concentration (by weight) with viscosity decreasing with an increasing shear rate. The shear stress-strain rate data were fitted into the rheological models to calculate the model parameters for Power-Law fluid and Herschel-Bulkley fluid. The rheological study was conducted to investigate the effect of solids concentration, temperature, fraction of coarse particles in fine particles. It was found that the slurry viscosity increased with an increase in solids concentration. It was found that with increase in temperature the apparent viscosity of the slurry decreases. The coarse particles were also added to relatively finer coal particles to determine the effect of addition of fraction of coarse particles and it was observed that the slurry viscosity decreased with the addition of coarse particles until an optimum ratio of coarse. An increase in slurry viscosity was found at coarse/fine ratio greater than the optimum coarse/fine ratio. It was also found that with increase in temperature the apparent viscosity decreases first but after a particular temperature the apparent viscosity increases with increase in temperature.