Investigation of flow characteristics of coal and oil slurry

Abstract

The present study on the coal-oil slurry rheology and its transportation performance was conducted at the Mechanical Engineering Department, Thapar University, Patiala. The rheological behaviour of three different ranked Indian coal samples were investigated by using Anton Paar RheolabQC rheometer to generate extensive rheological data with a perspective to study the effect of solids concentration, particle size distribution, blended coal-oil, temperature effect and ash content on the slurry rheology. The lower ranked coal was washed with chemical to produce ultra-clean coal. The coal oilslurry was prepared with chemically treated coal and without treated coal to study the effect of ash content present in coal. The rheological results revealed that the coal oil slurry exhibited non-Newtonian behaviour. The coal oil slurry flow behaviour was described by the Power-Law and Herschel-Bulkley models. The apparent viscosities of coal oil slurry increased with solids loading. The Particle Size Distribution affected the slurry rheology due to increase in frictional forces within particle to particle. The apparent viscosity of coal oil slurry decreases when high ranked coal is blended with lower ranked coal at all concentration. Also the apparent viscosity of slurry decreases with increase in temperature due to breakdown of oil particles. The rheological data best fitted for Herschel-Bulkley model which exhibits shear thinning behaviour.The rheological data so obtained were utilized to numerically evaluate the pressure drop characteristics of coal oil slurry flowing in 90 degreepipe bend using ANSYS FLUENT 14.0 computational fluid dynamics code. The pressure drop predictions were obtained by utilizing the rheological data and the results revealed that in 90°pipe bend, with increase in solids loading and mean flow velocities, the pressure drop increased.