Analysis of thermal stresses in a boiler drum during start-up

The paper presents an analytical way of calculating thermal stress distribu tions in cylindrical vessels, nonuniformly heated on their circumference. i n thick-walled vessel elements, simplified analytical formulas do not give satisfactory results. A new method for determining thermal stresses has bee n developed On the basis of temperature history measurements at several pai nts on the drum outer surface, a time-space temperature distribution in the component cross section is determined, and next, thermal stresses ape calc ulated using the finite element method (FEM). The new method, proposed for the solution of the inverse heat conduction problem, is sufficiently accura te. Knowledge of the boundary conditions an the inner surface of the norm, i.e,, fluid temperature and heat transfer coefficient, is nor necessary bec ause the transient temperature distribution in the component is obtained fr om the solution of the inverse heat conduction problem. Comparison of the t hermal distributions from FEM versus the new method demonstrate the accurac y of the new method An example application of the new method demonstrates i ts benefits over the solution of the boundary-initial problem obtained by F EM.