In order to eliminate the high-temperature corrosion on water wall of a subcritical boiler after ultra low NO_x emission transformation

the atmosphere around the water wall was tested

and simulation device was employed to carry out physical and chemical analysis for the corrosion products. The results show that

the reducing atmosphere was strong at the node function area and the reducing zone between the main combustion zone and the burning-out zone. The overall secondary air volume at No.2 and No.4 corner was relatively insufficient

which increased the high temperature corrosion in the area near the two angles. The high-and low-load cycle fluctuation of the unit caused continuous deepening of high-temperature corrosion. The corrosion resistance of the pipe can be enhanced if the pipe contains a certain Cr element. In actual operation of the boiler

the non-uniformity of secondary air should be improved

and the Cr-containing pipe shall be reasonably applied in the areas with higher corrosion risk.