Stress and fatigue life monitoring of high temperature bearing elements based on the solution of inverse conduction problem

The stress and fatigue life monitoring of high temperature bearing elements is of great significance for the safe and economic operation of thermal power plant. The calculation of temperature distribution is the fundamental of the stress and fatigue life analysis. In order to improve the precision of the temperature distribution, a method for stress and fatigue life analysis of boiler drum, which is the biggest high temperature bearing elements of boiler, based on the solution of inverse conduction problem is presented. On the basis of energy conservation and control volume method, the general equations for calculating the boiler drum temperature distribution by the inverse conduction problem were derived. The life expectancy of the boiler drum is then calculated according to ASME Code. The cold start-up process of one 300 MW boiler is analyzed by this method. The results show that the temperature distribution in the drum cross section can be determined based on the temperature measurements at several points on the drum outer surface, which can avoid the errors caused by assumption of the boundary conditions on the inner surface of the drum. This method can be used for the on-line analysis of the drum fatigue life.