To study the influence of cyclic stress caused by peak shaving on the water wall of a supercritical circulating fluidized bed boiler

numerical simulation is carried out to calculate the temperature and thermal stress of the water wall for a 350 MW supercritical circulating fluidized bed boiler based on the results of hydrodynamic calculation. Utilizing the obtained stress distribution map

critical points susceptible to fatigue failure are identified. The stress amplitude is calculated and modified with the principal stress interpolation method and Goodman formula. Subsequently it is converted into an equivalent life. Finally

the S-N life curve is adopted to predict the fatigue life of the water wall. The results indicate that significant stress concentration is observed in partial areas of the inner tube wall and the fin root on the fire side

which is primarily attributed to the expansion and compression caused by non-uniform heating between the fins and the water wall tube. The stress on the inner tube wall is mainly governed by the working fluid pressure

whereas the stress at the fin root is more significantly influenced by thermal stress. Fatigue life prediction for critical points reveals a lifespan below 106 cycles

which fails to meet the fatigue limit requirement

indicating that the water wall will suffer additional fatigue damage. This paper compares and analyzes the differences in stress response across various regions

elucidating the respective contributions of pressure and thermal stress to fatigue damage. The findings provide a theoretical foundation for the safe operation of boilers under deep peak shaving conditions.