Factors determining the durability of steam superheater chambers

Purpose: The paper presents the results of calculations of effort for the material of selected superheater chambers' constructional systems in unsteady operation conditions. Design/methodology/approach: In model tests, the influence was analysed of internal pressure and temperature gradient in the chamber wall on the distribution and value of stress . In the calculations, the process of hot start-up of a boiler was simulated, which was accompanied by short thermal shock induced by rapid cooling of the chamber inner wall. Findings: The random nature of thermal shock, which in the industrial practice may occur in any row and to any number of coil pipes, determines the value of maximal stress and the area of its occurrence. It has a significant influence on the possibility of forecasting the durability of chambers in working conditions. Research limitations/implications: The research has evidenced a link between the method of forcing thermal shock and the value of maximal stress in the area of bridges. Practical implications: The research has demonstrated the existence of connection between the way of forcing thermal shock and the stress value which, depending on the variant of cooling the chamber, ranges between 150-370 MPa. These results are very important to the industry connected with the structure of pipelines. Originality/value: It was found that the primary reason for the superheater chamber damage, leading to crack formation, are thermal shocks. A link has been shown between the method of forcing the thermal shock and the value of maximal stress in the zone of bridges.