Combustion and air emissions from co-firing a wood biomass, a Canadian peat and a Canadian lignite coal in a bubbling fluidised bed combustor

The effects of particle size, fuel blending ratio, moisture content and excess air ratio on combustion efficiency and air emissions (CO ₂, CO, SO ₂ and NO _x) from the co-combustion of white pine or peat with a Canadian lignite coal, were examined in a pilot-scale bubbling fluidised bed combustor. Pelletising was important for the efficient combustion of wood due to its high volatile content. Co-firing lignite and pine pellets gave a proportional reduction in SO ₂ and NO _x emissions with blending ratio, while co-firing of peat and lignite resulted in increased SO ₂ emissions, but decreased NO _x emissions. Moisture promotes combustion but with increased CO emissions, and results in increased NO _x emissions, and decreased SO ₂ emissions. High excess air decreased CO, but moderately increased SO ₂ and NO _x emissions.