Co-combustion of anthracite coal and biomass-derived biocarbons: reaction kinetics and combustion performance indicators

This work investigates the feasibility of using biocarbon as an alternative fuel to substitute fossil fuels in industrial processes. Woody biocarbons (WBC1, WBC2) were used for this purpose. Anthracite was selected as the reference fossil fuel to be replaced and biocoke was also considered for comparison. Samples were characterized in terms of chemical composition, and physical and thermal properties. Fuel thermal stability and combustion performance were evaluated using thermogravimetric analysis. Ignition kinetics were modelled using differential scanning calorimetric-based model. The results showed that biocarbon with a lower volatile matter content presents a higher thermal stability while its behavior is close to that of anthracite. Biocoke and biocarbons showed lower ignition temperatures but a higher burning index compared to anthracite, which was shown as the most stable fuel. Kinetic parameters, namely activation energy (Ea), frequency factor (A), and oxidation rate (k), were compared for the samples of study. While oxidation rates of biocoke and biocarbons were comparable, different values were obtained for WBC samples with different volatile matter content. Synergistic effects were observed when biocarbon was mixed with anthracite, mainly due to AAEM present in the samples. To mitigate biocarbon reactivity, a 50/50 biocarbon/anthracite co-combustion was proposed, offering the advantages of higher ignition temperature and low reactivity. • Volatile matter was shown to be proportional to reactivity and explosivity index. • Biofuels whose behavior is close to that of anthracite present low volatile matter content. • Lower volatile matter content in biocarbon is correlated to higher ignition temperatures. • Biocarbon exhibited a higher burning index than anthracite. • 50/50 biocarbon/anthracite showed good performances as an alternative carbon-based fuel.