The paper presents an analytical way of calculating thermal stress distributions in cylindrical vessels, nonuniformly heated on their circumference. In thick-walled vessel elements, simplified analytical formulas do not give satisfactory results. A new method for determining thermal stresses has been developed. On the basis of temperature history measurements at several points on the drum outer surface, a time-space temperature distribution in the component cross section is determined, and next, thermal stresses are calculated using the finite element method (FEM). The new method, proposed for the solution of the inverse heat conduction problem, is sufficiently accurate. Knowledge of the boundary conditions on the inner surface of the drum, i.e., fluid temperature and heat transfer coefficient, is not necessary because the transient temperature distribution in the component is obtained from the solution of the inverse heat conduction problem. Comparison of the thermal distributions from FEM versus the new method demonstrate the accuracy of the new method. An example application of the new method demonstrates its benefits over the solution of the boundary-initial problem obtained by FEM.
Purpose
The purpose of this paper is to present a method for monitoring transient thermal stresses. This paper also presents the analysis of thermal stresses of boiler pressure element heating during the start-up in real conditions. The inverse methods are used to determine the wall temperature, whereas the commercial software ANSYS is used to determine the thermal stresses in the pressure component.
Design/methodology/approach
The method is based on the solution of the inverse heat conduction problem. Thermal stresses are determined indirectly taking into account the measured temperature values at selected points on the outer wall of a pressure component. First, the transient temperature distribution in the entire pressure element is calculated, and then, thermal stresses are determined by the finite element method. Measured pressure changes are used to determine the stresses resultant from the internal pressure.
Findings
The obtained stresses and temperature in the thick-walled pipe are illustrated and compared with experimental data. Satisfactory agreement was found between computational and experimental results.
Originality/value
The method can be used in the monitoring of thermal and mechanical stresses during the boiler’s start-up and shut-down. Because the temperature distribution at each time level is determined, it can be applied as a thermal load during the structural analysis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.