SO2 effects on CO oxidation in a CO2 atmosphere, characteristic of oxy-fuel conditions

SO2 is an important pollutant formed during many combustion processes which may affect the oxidation of the fuel. The current work focuses on the evaluation of the effect of the presence of SO2 on CO oxidation in a CO2 atmosphere, found in oxy-fuel combustion, in comparison to a N2 dilution characteristic of air combustion. A flow reactor experimental and kinetic modeling study of the gas-phase interaction of SO2 with the radical pool during CO oxidation under CO2 and N2 diluted conditions has been carried out for different stoichiometries in the 800–1800 K temperature range. esence of SO2 is seen to inhibit the oxidation of CO in both atmospheres for all the stoichiometries studied, although the inhibition is significantly higher as the stoichiometry becomes more reducing. The inhibiting effect of SO2 in the CO2 atmosphere is caused by similar radical recombination mechanisms than those occurring with N2. Under fuel-rich conditions, the inhibition is governed by the SO2/HOSO inter-conversion and is less pronounced as the CO2 concentration increases. However, as the conditions are more fuel-lean, the SO2 inhibiting effect is comparable in both atmospheres due to the higher importance of the SO2 + O recombination. As the SO2 concentration increases, its interaction with the radical pool is enhanced and the inhibition of CO oxidation is higher. An updated kinetic mechanism is used for calculations and provides a very good description of the experimental results for all the operating conditions analyzed.