Effect of oxy-firing on corrosion rates at 600°C

Replacing air with oxygen in coal-fired boilers (i.e. oxy-firing) combined with flue gas recirculation is a leading strategy to concentrate CO ₂ in the flue gas and assist in carbon capture for subsequent sequestration. A significant area of concern is the fireside corrosion with oxy-firing due to the higher CO ₂ levels in the combustion gas and potentially higher SO _x and H ₂O levels. In order to investigate this complicated issue, laboratory experiments are being conducted with and without synthetic ash to assess the potential effect of oxy-firing on fireside corrosion rates. The initial results of this project focus on commercial and model Fe-base alloys at 600°C. Without ash, a 50%H ₂O-50%(CO ₂-0.15O ₂) environment was the most aggressive condition, requiring higher Cr contents than 100% H ₂O or Ar-50%CO ₂. With the specimens covered in ash, several gas compositions were examined including different levels of H ₂O and. SO ₂ to simulate various oxy-firing strategies. Box plots were used to present the data for several laser cladding compositions for protecting tubes.