Empirical correlations of the ash fusion temperatures and temperature of critical viscosity for coal and biomass ashes

Empirical correlations have been derived by regression analysis to calculate the ash fusion temperatures under reducing conditions and the temperature of critical viscosity from the ash chemical composition. The data-base used in this work includes about 300 ash samples from coals of different sources and biomasses. The standard deviation, σ, for these equations are generally about 45-80 °C. These fall within the experimental errors of the measurements. These correlations: (1) provide a tool for calculating the thermal properties of the ash from its chemical composition; (2) provide a method to predict the effect of adding minerals (such as CaO) normally used to modify the slag behaviour.