Co-combustion of brewer's spent grains and Illinois No. 6 coal: Impact of blend ratio on pyrolysis and oxidation behavior

• Activation energy for pyrolysis non-additive function of blend composition
• Blends oxidize in separate volatile/char oxidation stages for each fuel component
• GC–MS pyrolysis of blends shows evidence of chemical reaction synergism

Co-combustion of locally available biomass in existing coal-fired power plants is an attractive option to increase the share of renewable fuels in the energy market with minimal capital investment. Utilizing existing coal-fired combustion equipment for blends requires knowledge of pyrolysis and combustion characteristics. This study presents thermal evolution profiles (decomposition rates, apparent activation energies and devolatilized compounds) of coal–biomass blends to probe the effect of blend ratios on pyrolysis and combustion behavior. The global rate of pyrolysis of Illinois No. 6 coal and brewer's spent grains (BSG) is a function of fuel composition, though analysis of evolved gases suggests the presence of both potential additive and synergistic interactions on a molecular level. For oxidation, a rapid decrease in peak conversion rate is seen as the percentage of BSG increases from 0% to 20%, becoming less pronounced as the percentage of BSG increases above 20%.