Viscosity Analysis of Indian Origin Coal by Using FactSage at Different Temperatures

Abstract

Slagging of the ash inside the furnace boiler causes operational problems such as furnace shutdowns and low heat exchange efficiency. To avoid this problem, ash fusion temperature (AFT) parameter has been well accepted for determining the ash fusion characteristics since many years. In this paper, an extensive study has been conducted on the deposition characteristics of ash particles based on the viscosity and phase transformation properties in boiler operation. The FactSage thermodynamic software package is utilized for the phase transformations and viscosity predictions of coal ash in furnace operating temperatures. The effect of solid or crystalline fractions in slag phase on the viscosity is calculated by using the Roscoe equation. Calculations show that an increase in solid fractions increases the viscosity of the slag phase. AFT analysis of coal samples for the present study shows that their IDT and FT values are higher than 1340 °C and 1470 °C, respectively. The reason for the high IDT and FT in Indian origin coals is the formation of high-temperature-stable phases—tridymite and sillimanite. Furthermore, the numerical viscosity models developed by using the Roscoe viscosity equation are correlated with the experimental AFT results.