In the process of CFB boiler banked fire,some problems may occur,such as fast temperature drop of the material layer,less heat storage,and excessive pollutant discharge. These problems pose a threat to the safety,environmental protection,and operation of a power plant. Taking the 350 MW supercritical CFB boiler as the research object,the field test and numerical simulation of the CFB boiler banked fire process were carried out. The simulation results of the supercritical CFB boiler are in good agreement with the measured data. The simulation can accurately predict the pressure,temperature,and gas component distribution in the furnace. The average errors of pressure,temperature,O 2 concentration,NO x concentration,and SO 2 concentration are 5.6%,2.3%,6.3%,5.7%,and 8.5%,respectively,which verifies the accuracy of the numerical model. [JP+1]During the process of banked fire,the boiler enters the closed state. The oxygen is stable at 19.5%,the bed temperature drops to 905 K,and the cooling rate is 2 K/min. The bed material at the bottom of the furnace is static,and the stratification phenomenon occurs. The bottom bed material with an 85% fraction is the lower bed material,and the accumulation height of the lower bed material is about 1 m. The most influential factor of the bed material stratification is the particle size. The lower layer is large particle bed material,the average particle size is 1.2 mm. The middle layer is small particle bed material,the average particle size is 0.5 mm. The mass fraction of the upper bed material is only 5%,dopes with large and small particles,and particles in a suspension state,in the closed furnace suspension height remains unchanged. The NO x concentration is negatively correlated with the volume fraction of particles. The average NO x concentration of the lower bed material is 31 mg/m 3,the average NO x concentration of the middle bed material is 60 mg/m 3,and the average NO x concentration of the upper bed material is 121 mg/m 3. The furnace enters the closed state,and the SO 2 concentration remains unchanged with the completion of bed material falling back. The average SO 2 concentration in the upper part of the furnace is 756 mg/m 3,while the SO 2 concentration in the lower part of the furnace is also affected by bed material stratification. The SO 2 concentration in the upper bed material is the highest,which is 1 680 mg/m 3. In the process of banked fire,the average concentration of NO x in the furnace is about 100 mg/m 3,and the average concentration of SO 2 is about 1 160 mg/m 3.