Heat transfer deterioration of supercritical circulating fluidized bed(CFB) boiler in operation causes cracks in water wall

which increases the probability of tube bursting and leakage of water wall. Taking an ultrasupercritical CFB boiler under construction as the research object

a two-dimensional finite element calculation model for membrane water wall is established to analyze the influences of different heat transfer deterioration degrees on the temperature and thermal stress of water wall. The results show that

the changes of the inner and outer wall temperatures of the water wall tubes with azimuth angle θ are consistent between normal heat transfer and heat transfer deterioration. When heat transfer deterioration occurs

the temperature of water wall rises as a whole

and the highest temperature shifts from the middle point of fin to the top of fire side of the water wall tubes.The change trend of deformation of the water wall tube towards fire side is the same as that of temperature. When the heat transfer deteriorates

the temperature and thermal stress of the water wall will exceed the allowable temperature and yield strength of the material

and repeated heat transfer deterioration is an important factor leading to tube bursting of the water wall.