||This presentation will provide an overview of the assessment of the impacts of oxy-°©‐combustion retrofit with designed firing configuration in existing coal-°©‐fired boilers based on CFD modeling of air-°©‐fired and oxygen-°©‐fired operation. The two boilers that were used for this study where PacifiCorp's Hunter Unit 3 and DTE's River Rouge 3. The model evaluation was performed following an extensive research program focused on the development multi-°©‐scale data sets and computational mechanisms describing the flame characteristics, waterwall corrosion, and ash properties (slagging, fouling) in oxy-°©‐firing. The modeling was performed with the intent to optimize the oxy-°©‐firing system such that the air-°©‐fired heat duties would be matched, the combustion efficiency would be maximized and surface impacts would be minimized, including corrosion, slagging and fouling. The resulting upgrades to the CFD model included: advanced models for radiation, char oxidation, soot formation, slagging and corrosion. Parametric investigations were performed involving different flue gas recycle properties, firing system configurations and fuels. Predicted temperatures, heat transfer, deposition and corrosion rates in the lower and upper furnace were reviewed and steam-°©‐side impacts were also evaluated.