Large proportion burning high-alkali coal will cause serious contamination to the heating surface of the boiler

and threat the device security and stable production of the power plant. The article compared flue gas temperature changes of three types of boilers burning Xinjiang Naomaohu high-alkali coal

XRD phase analysis and chemical composition analysis of ash slag was also performed. Analysis results indicate the composition of the ash block developed by short-term bonding is close to that of coal ash

and the texture is loose

and the heating surfaces can be kept clean by soot blowing optimization. The shell-like slag formed by long-term contamination is rich in SO_3 and Na_2O

the degree of sintering is high

and the texture is hard

controlling the flue gas temperature of the heating surface inlet can effectively reduce the fouling and slagging of the tube panel. The flue gas temperature at the convection heating surface inlet with tube panel gaps of about 50 mm should be controlled below 800 ℃

when the gaps are above 200 mm

the flue gas temperature should be controlled below 1 000 ℃. The results of the research can be used as a reference for the same type of boiler burning high-alkali coal.