Comparison Between Combustion Behavior of Solid Fuels and Their Chars Under Oxy-Fuel Conditions

Abstract

The combustion characteristics of petcoke and imported coal and their respective chars under oxy-fuel (21% O₂/79% CO₂) and oxygen-enriched oxy-fuel (30% O₂/70% CO₂) environments were investigated by using non-isothermal thermogravimetric method coupled with a Fourier transform infrared spectrometer. Experimental results reveal that at elevated oxygen levels, profiles shift to lower temperature zone, peak and burnout temperatures decrease, weight loss rate increases significantly, and complete combustion is achieved at lower temperatures. The ignition, peak, and burnout temperatures of chars are found to be higher than those of their parents due to absence of volatile matter and higher ash content left in the char.

An Arrhenius-type kinetic model was used to determine the values of the kinetic parameters of the combustion of the fuels and their chars. Values of activation energies and Arrhenius constants predicted by the model show that chars are less reactive than their parent fuels due to the absence of volatiles.

Keywords:

• Char
• Coal
• Kinetics
• Oxy-fuel combustion
• Petcoke
• TGA-FTIR