THERMOMECHANICAL FINITE ELEMENT ANALYSIS OF HOT WATER BOILER STRUCTURE by

The paper presents an application of the finite elements method for stress and strain analysis of the hot water boiler structure. The aim of the research was to investigate the influence of the boiler scale on the thermal stresses and strains of the structure of hot water boilers. Results show that maximum thermal stresses appear in the zone of the pipe carrying wall of the first reversing chamber. This indicates that the most critical part of the boiler are weld spots of the smoke pipes and pipe carrying plate, which in the case of significant scale deposits can lead to cracks in the welds and water leakage from the boiler. The non-linear ef-fects were taken into account by defining the bilinear isotropic hardening model for all boiler elements. Temperature dependency was defined for all relevant ma-terial properties, i. e. isotropic coefficient of thermal expansion, Young’s mod-ulus, and isotropic thermal conductivity. The verification of the FEA model was performed by comparing the measured deformations of the hot water boiler with the simulation results. As a reference object, a Viessmann-Vitomax 200 HW boi-ler was used, with the installed power of 18.2 MW. CAD modeling was done within the Autodesk Inventor, and stress and strain analysis was performed in the ANSYS software. Key words: thermomechanical analysis, hot water three-pass fire tube boiler, finite elements analysi