SO3 formation during oxy-coal combustion - Presentation

In oxy-coal combustion, an oxygen and carbon dioxide mixture, rather than air, is used to burn the coal. Many studies to date have focused on the formation of NOx under oxy-coal combustion conditions; however, the formation of sulfur species, particularly sulfur trioxide, is currently not a wellunderstood problem in oxy-coal combustion. In conventional combustion with air, fuel-bound sulfur species are oxidized primarily to sulfur dioxide, with a small fraction being converted to sulfur trioxide. Due to the increased oxygen concentration in oxy-fuel combustion, it is possible that a greater fraction of the sulfur dioxide can be oxidized to sulfur trioxide in the flue gas. Because sulfur trioxide is very corrosive and can form sulfuric acid with water vapor in flue gas, it is important to understand and to be able to predict the amount of sulfur trioxide formed during oxy-fuel combustion. The purpose of this study is to investigate the effects of increased oxygen and carbon dioxide concentration on the formation of sulfur trioxide during oxy-coal combustion. ASTM method D3226-73T (also called the Controlled Condensation Method) was used to measure sulfur trioxide in pilot-scale experiments, for both air- and oxy-fired conditions, and the results are compared with anticipated performance based on thermochemical and kinetic calculations.