Investigation of Rheological Characteristics of Coal-Oil Mixtures

Abstract

The present study on investigation of rheological characteristics of coal-oil mixtures was conducted at the Mechanical Engineering Department, Thapar University, Patiala. Three coal samples having different ash and moisture contents and furnace oil of grade MV2 were used for the preparation of coal-oil mixtures. Coal concentration was varied from 20 – 50 % by weight and temperature was varied from 25° - 45° C, in order to study the effect of solids concentration and temperature on the rheological properties of coal-oil mixtures. Rheological measurements were carried out using Anton Paar RheolabQC rheometer. It was observed that both apparent viscosity and yield stress of coal-oil mixture increased, with an increase in solids concentration and decreased, with an increase in temperature. The flow behavior of coal-oil mixtures was described by the Power-Law and Herschel-Bulkley models. The coal-oil mixtures up to 30 % solids concentration, behaved as a Newtonian fluid and with solids concentration more than 40 %, they behaved as a yield pseudo plastic fluid. Also the effect of various properties of coal like ash content, moisture content, particle size and particle size distribution on coal-oil mixture rheology was studied. It was found that both apparent viscosity and yield stress of coal-oil mixture decreased, with an increase in ash content of coal and increased, with an increase in moisture content of coal. As mass median diameter of coal particles increased, both apparent viscosity and yield stress of coal-oil mixture decreased. Also, with an increase in distribution modulus (n) of coal sample, both apparent viscosity and yield stress of coal-oil mixture increased.