Ash deposition and collapse at the burner arch severely affect the safe and stable operation of boilers.This paper analyzes the causes of ash deposition in the burner arch of a specific boiler and identifies the main contributing factors as flue gas backflow in the burner arch region

velocity differences between flue gas streams on both sides

and significant residual rotation in the furnace flue.To address these issues

adjustments are made to the tilt angle of the separated over-fire air(SOFA) nozzles.The results show that ash deposition and collapse occur when the tangential momentum inside the furnace is either too large or too small.After appropriately adjusting the nozzle angle

the tangential momentum within the furnace is optimized

residual rotation at the furnace outlet is eliminated

and the flue gas temperatures on both sides are balanced.After appropriately adjusting the nozzle angle

the tangential momentum inside the furnace was optimized

residual swirl at the furnace outlet was eliminated

and flue gas temperatures on both sides were balanced.These adjustments effectively resolved the ash accumulation and collapse issue in the burner arch area.