Numerical simulation and life prediction on T22 boiler tubes with steam-side and fire-side oxide scale

In this study based on Larsen-Miller empirical formula, two simulation models of T22 boiler tube of a super-heater are analyzed by Finite Element Method (FEM). Model one only considers the steam-side oxide scale, and model two considers both the steam-side and the fire-side oxide scale. The results show that the average temperature and Von Mises stresses of the tube increase gradually due to the existence of the steam-side and fire-side oxide scale, in which the effect of fire-side oxide scale is more remarkable. Based on the simulation results, Kachanov-Rabotnov creep damage model was employed to assess the creep life of the tube. It was found out that at the initial stage of the service time the fire-side oxide scale can protect the tube and delay the creep damage obviously, and the critical creep damage of the tube is only about 0.5 before failure occurs.