SO_2 effects on CO oxidation in a CO_2 atmosphere, characteristic of oxy-fuel conditions

摘要

SO_2 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 SO_2 on CO oxidation in a CO_2 atmosphere, found in oxy-fuel combustion, in comparison to a N_2 dilution characteristic of air combustion. A flow reactor experimental and kinetic modeling study of the gas-phase interaction of SO_2 with the radical pool during CO oxidation under CO_2 and N_2 diluted conditions has been carried out for different stoichiometries in the 800-1800 K temperature range.rnThe presence of SO_2 is seen to inhibit the oxidation of CO in both atmospheres for all the stoichiome-tries studied, although the inhibition is significantly higher as the stoichiometry becomes more reducing. The inhibiting effect of SO_2 in the CO_2 atmosphere is caused by similar radical recombination mecha-nisms than those occurring with N_2. Under fuel-rich conditions, the inhibition is governed by the SO_2/ HOSO inter-conversion and is less pronounced as the CO_2 concentration increases. However, as the con-ditions are more fuel-lean, the SO_2 inhibiting effect is comparable in both atmospheres due to the higher importance of the SO_2 + 0 recombination. As the SO_2 concentration increases, its interaction with the rad-ical 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 con-ditions analyzed.