Gasification kinetic modelling of Victorian brown coal chars and validity for entrained flow gasification in CO_2

The gasification kinetic modelling of two Victorian brown coal (Yallourn and Maddingley) chars and the validity for entrained flow gasification were investigated in this study. The study was conducted in a thermogravimetric analyzer (TGA) at 750–1100 ℃, 30%–90% CO₂ concentration using different char particle sizes within 20–106 µm. It was found that random pore model and modified volumetric model are applicable for TGA results, but volumetric model and grain model are not. The effect of particle size under 106 µm on gasification rate is very limited. Activation energies of Maddingley char and Yallourn char in CO₂ gasification are 219–220 and 197–208 kJ/mol, respectively. The pre-exponential factors are in the same order of magnitude, and they increased as particle size decreased. A mathematical model was developed to predict carbon conversion over time for entrained flow gasification of Victorian brown coal chars at 1000–1400 ℃.