For the fire-missing phenomenon which often appeared in certain boiler

the main reasons such as the serious slagging in boiler and the poor flame detection installation have been proposed. The further analysis shows that the change of coal quality

a high primary wind speed

the big fineness of pulverized coal

the poor pulverized coal uniformity in furnace four-corner

too much refractory belt area

large tangential burner diameter

unreasonable soot blowers’ location are the major causes of serious slagging in boiler. By improving the quality of coal

installing pulverized coal distributors at the exit of coal mills

reducing the tangential burner diameter

adjusting the flame detection installation

lowering the refractory belt area and making it segmented smaller

optimizing boiler operation mode

the fire-missing phenomenon of the boiler has been eliminated. The results can be served as reference to the same kind of problems.