Remaining Life Estimation Of 300MW Boiler High Temperature Tubes Of Huaibei Power Plant

The tubes of superheater and reheater are the main component of the heat exchangers in power plant boilers. Whether they run safely and stably or not is directly count for much the safe of the whole plant operation. And the frequent tube leakage of heat surface impact upon the economy benefits and the society benefits of the power plant. This paper evaluates the life of the 300MW high temperature boiler tubes that have been being used in Huaibei power plant.The dissertation goes deep into the tube failure mechanism and the reliability theory in order to improve the diagnosis and monitor veracity and tone up the operation reliability. The parameters of the tube life lapse is expressed by the Larson-Miller function and the effect of the parameters on the life is derived. And it is confirmed the operation temperature and the pressure and the service time are the main factors of the life lapse.Then because the real operation temperature of the tube is the critical factor for predicting the tube lifetime, we heat some unused tubes in the lab. Then we measuer the rigidity of them and find the relationship between the hardness and heat - intensity parameter. The paper analylizes and caculates the operation temperature of the tube through the methods of the inner oxide scale thickness and rigidity. On this basis the paper calculates the remain life of the experimental tubes.It is researched that the influence on the tube lifetime of the metallographic structure and the alloy element by testing the superheater and reheater tube which is made of 12Cr2MoWVTiB steel. The metallographic change and the distribution of alloy elements after the tube has run in the high temperature condition for longtime is more believable and franker to evaluate the tubes remain life time.In the end of the dissertation, the lifetime of the experimental superheater and reheater tubes that have been used is evaluated by the methods of sress computation and the metallographic tests.