Ignition and NO Emissions of Coal and Biomass Blends under Different Oxy-fuel Atmospheres

Abstract

The effect of co-firing coal and biomass on the ignition behaviour and NO emissions was evaluated under both air and O2/CO2 (21-35% O2) atmospheres. The results showed a worsening of the ignition properties in the 21%O2/79%CO2 atmosphere in comparison with air. Furthermore, in order to obtain similar or better ignition properties, the oxygen concentration in the O2/CO2 mixture must be 30% or higher. A decrease of the ignition temperature was observed with the addition of biomass in air and oxy-fuel conditions. The results also indicate that NO emissions in the 21%O2/79%CO2 atmosphere were lower than under air-firing conditions, although they increased in the 30%O2/70%CO2 and 35%O2/65%CO2 atmospheres. The addition of biomass resulted in lower NO emissions in all cases.