Formation of SO3 in a Noncatalytic Combustor

Abstract

The major contributor to corrosion and deposits in boilers and gas turbines has been recognized as the reaction of sulfur oxides, especially SO3, in the combustion gas with furnace elements. One way to minimize these reactions is to reduce the quantity of SO3 formed. Factors affecting SO3 formation have been studied in a noncatalytic laboratory combustor, and results of the investigation show that SO3 in the combustion gas can be reduced by: (a) Reducing excess air, (b) burning fuel with a lower sulfur content, (c) preventing air leakage into the combustion system, and (d) covering catalytic surfaces, such as superheater tubes, with less catalytic protective coatings. Some experiments showed that iron-oxide coatings, which built up on iron surfaces, were highly catalytic for the production of SO3 under boiler-furnace-simulated conditions.