Ignition and Combustion of Single Particles of Coal and Biomass under O2/CO2 Atmospheres

Biomass energy with carbon dioxide capture and storage (CCS) technologies like oxy-fuel is the only way to achieve net removal of CO₂ from the atmosphere in power generation. A single particle apparatus has been developed for rapid heating and combustion of individual fuel particles in air or O₂/CO₂ atmospheres. This wire mesh apparatus was used as a heating element to heat the particle by radiation while optical access allowed particle combustion characterization by high speed camera recording. Four different biomass and a bituminous coal were used in air and 21, 30 and 40% O₂ atmospheres with balance of CO₂. High speed video image analysis showed differences in ignition and devolatilization behaviour. The influence of particle size and mass on burnout times was higher in the coal, while biomass particle size can have a greater range of sizes for the same burnout times. The 30%O2 atmosphere was enough to have less burnout time than in air atmosphere for all the samples. During biomass particle combustion, the results showed that the surface tension on the biomass char particle plays a significant role due to partial melting of the char particle. This effect modifies the char particle shape during its combustion, with particles becoming more spherical particle even for those that initially had a fibrous shape.