This article presents a troubleshooting analysis of a steam boiler which serves for steam overheating. Operating of this boiler is accompanied by unexpected difficulties – repetitive crack occurring on a boilers collector (Figure 1). Therefore, the substantial part of this paper is focused on identifying of the main reason of damaging. The first step in damage identification was static, respective quasi-static FEM (finite element method) analyses. These analyses did not confirm the cause of damaging. Therefore, it was approached to analytical calculations (thermal – hydraulic and vibration calculations) which were used for additional boundary conditions estimation. The vibration analytical analyses predicted vortex excitation. The occurrence of vortex excitation behind the tube (Figure 6) was subsequently confirmed by CFD (computational fluid dynamics) and FSI (fluid structure interaction) analyses. These analyses revealed the cause of tube bundle damaging, which was fluid induced vibration. Significant part of this article is devoted to discussion about used computational models, boundary conditions and results of analyses. The last part of this article is targeted at proposing corrective action.
