Metal dusting in low-NOx recirculation burners for fuel oil

AbstractTen low sulphur fuel oils LSFO (sulphur content between 5 and 72 mg kg−1) were tested with a low-NOx burner. Metal dusting attack on flame recirculation tubes made of the Ni-base alloy Alloy 601 was observed for seven of the fuels. The concentrations of O2, CO, CO2, CxHy and H2 close to the inner surface of the flame tubes were measured during burner operation. In the region where the tubes were attacked, a high concentration of hydrocarbons was found giving a carbon activity well in excess of 1. The role of sulphur was investigated by electron probe analysis of the amount of sulphur adsorbed on the surface of the recirculation tube after operation. A low value was found and no significant differences were observed between areas that had and had not suffered from attack. It is concluded that no decisive evidence has been found for the inhibiting effect of adsorbed sulphur on the catalytic activity of surface sites.