Rheological characteristics of coal hydro-liquefaction residue

Abstract

Coal liquefaction residue (CLR), coming from a direct coal liquefaction pilot plant, was used to investigate its rheological characteristics and the effects of temperature, oil and asphaltene, as well as solid content on its rheological characteristics. CLR is a kind of non-Newtonian pseudoplastic fluid, whose viscosity index decreases with increasing temperature, and approaches Newtonian fluid behavior at high temperature. The apparent viscosity of CLR drops greatly without peak as it is sensitive to temperature. After adding a little recycled oil (REC) into CLR, its apparent viscosity decreases remarkably. However, after the addition of a little asphaltene into CLR, its apparent viscosity increases at a low temperature and decreases at a high temperature. In addition, solid content is the factor of increasing the apparent viscosity all the time. All the results indicate that the apparent viscosity of CLR has a close relation with oil, asphaltene, and solid contents. The relationship between the apparent viscosity and temperature can be expressed by Arrhenius Equation. But there is a flex point during heating, and the viscous flow activation energy at the low temperature is greater than that at the high temperature.