Reactivity during bench-scale combustion of biomass fuels for carbon capture and storage applications

Reactivities of four biomass samples were investigated in four combustion atmospheres using non-isothermal thermogravimetric analysis (TGA) under two heating rates. The chosen combustion atmospheres reflect carbon capture and storage (CCS) applications and include O2 and CO2-enrichment. Application of the Coats-Redfern method assessed changes in reactivity. Reactivity varied due to heating rate: the reactivity of char oxidation was lower at higher heating rates while devolatilisation reactions were less affected. In general, and particularly at the higher heating rate, increasing [O2] increased combustion reactivity. A lesser effect was observed when substituting N2 for CO2 as the comburent; in unenriched conditions this tended to reduce char oxidation reactivity while in O2-enriched conditions the reactivity marginally increased. Combustion in a typical, dry oxyfuel environment (30% O2, 70% CO2) was more reactive than in air in TGA experiments. These biomass results should interest researchers seeking to understand phenomena occurring in larger scale CCS-relevant experiments.