In China

Xinjiang province has vast reserves of high alkali coal resources. However

in coal-fired boilers

fouling and slagging on heating surface caused by alkali metals significantly limit the efficient utilization of the coals. Based on gas-phase alkali metal detection

combined with flue gas temperature monitoring

heat transfer calculation and other methods

slagging monitoring was carried out on the heating surface of a tangentially-fired boiler burning high alkali coal. The influence of air distribution on flame temperature

gas-phase alkali metal mass concentration and heating surface heat transfer in the furnace was analyzed

and a quantitative relationship between the gas-phase alkali metal mass concentration and the heating surface heat transfer was established. Preliminary monitoring of fouling and slagging on the heating surface was also conducted. The results indicate that

slag sample on the water wall side was quite different from that on the flue gas side. The covered water wall surface was loose and porous

while the flue gas side was dense and hard black coke. Significant macroscopic differences were observed

with sodium crystalline phases mainly in the form of feldspar. The highest alkali metal concentration were observed in the main combustion zone of the boiler. The higher the ratio of upper to lower secondary air

the higher the temperature and gaseous alkali metal concentration in the furnace.An increase in the average gaseous alkali metal concentration by 1 mg/m~3 resulted in a decrease in the heat transfer of the water wall by 0.82×10~8 kJ at 300 MW on a tangentially-fired boiler burning high alkali coal.