At present

high temperature corrosion of heating surface has become the main harmful factor affecting safe operation of boilers. Aiming at solving the high temperature corrosion problem of water wall in tangentiallyfired boiler of a supercritical 350 MW unit

the water wall atmosphere under typical working conditions was tested.The results showed that

the high-temperature corrosion of water wall mainly occurred in the burner areas below the over fire air(OFA) layer

and the corrosion area was distributed non-uniformly along the center line of the onesided furnace wall. Additionally

the volume fraction of H_2S on the right side of the center line of the furnace wall was significantly higher than that on the left side. After adjusting the oxygen content

peripheral air volume

and rising the temperature at outlet of the coal mill

the average H_2S volume fraction at each measuring point on the wall reduced from 0.022 6%(before adjustment) to 0.010 3%

the number of measuring point at which the H_2S volume fraction exceeded 0.02% dropped from 17(before adjustment) to 2

and the highest value of H_2S volume fraction decreased from 0.046 8% to 0.022 4%. The research results can provide a new idea for reducing the risk of high temperature corrosion of water wall through optimization of the operation of the same type of boilers.