Rheological properties of high-temperature melts of coal ashes and other silicates

• Published in: Progress in energy and combustion science 2001-03, Vol.27 (3), p.237-429
• Main Authors: Vargas, S., Frandsen, F.J., Dam-Johansen, K.
• Format: Article
• Language: English
• Subjects: Applied sciences; Coal ash; Combustion of solid fuels; Combustion. Flame; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Silicates; Theoretical studies. Data and constants. Metering; Viscosity
• ISSN: 0360-1285; 1873-216X
• DOI: 10.1016/S0360-1285(00)00023-X

This paper reviews the 20th century advances within the field of the measurement and the prediction of the rheological properties of high-temperature (T>1000 K) silicate melts at atmospheric pressure with a focus on coal ashes and other melts of compositions relevant to coal ashes. Theoretical considerations are represented firstly by a synopsis of definitions and flow-regimes and secondly by an outline of the ruling network theory and the notations used therein. The influence of different cations on viscosity is discussed thoroughly. Experimental points include a listing of the most common apparatus for viscosity measurements on high-temperature liquids and a summary of existing experimental data. Viscosity vs temperature is reported in tables as well as graphically for melts composed of major amounts of one or more of the species: SiO 2, Al 2O 3, FeO x , CaO, MgO, Na 2O, K 2O, Li 2O, MnO, TiO 2, B 2O 3. For each experimental source, relevant information is listed (apparatus, sensor material, atmosphere). With a basis in both theory and experimental data, general equations for liquids, are presented, relating viscosity to temperature and/or concentration of dispersed solids, as are more specific mathematical models, relating the viscosity of silica melts and glasses to temperature and composition.