A Study on Ash Fusibility Temperature of Domestic Thermal Coal Implementing Thermo-Mechanical Analysis

The slagging which generated from ash deposition on furnace wall and tube in boiler reduces the heat transfer efficiency and damages to safety of boiler. The slag flow behavior in boiler is affected by melting temperature which is related to ash compositions. In this study, the behavior of slag is researched by using ash fusibility test, called TMA (Thermo-Mechanical Analysis). The technique measures the percentage shrinkage as the function of temperature, T25%, T50%, T75%, T90%. These temperatures indicate different stages of melting. Then, the effect of ash chemical compositions measured from XRF (X-ray Fluorescence Spectrometer) to ash fusion temperatures is discussed. Among the chemical compositions, refractory and fluxing influence on ash fusibility is described. High levels of refractory com- ponent and limited amount of fluxing components (Fe2O3, K2O, CaO) increase overall melting temperatures. High SiO2/ Al2O3 ratio decrease high melting temperatures (T75%, T90%). Meanwhile, the presence of reasonable levels of fluxing components reduces overall melting temperature. A presence of fluxing component such as K2O and CaO is found to decrease the T25% values significantly. From this research, it is possible to make a reasonable explanation and predic- tion of ash fusion characteristic from analysis of TMA results and ash chemical compositions.