Modelling of thermal behaviour of iron oxide layers on boiler tubes

5th Symposium on the Mechanics of Slender Structures

物理学;力学

Angelo, J.D.^1 ; Bennecer, A.^2 ; Kaczmarczyk, S.^2 ; Picton, P.^2

Universidade Federal Do ABC, São Paulo, Brazil^1

University of Northampton, Northampton, United Kingdom^2

关键词: Catastrophic failures;    Constant temperature;    Insulation barriers;    Iron oxide layers;    Long-term overheating;    Microstructural changes;    Non destructive inspection;    Thermal behaviours;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/721/1/012002/pdf
DOI  :  10.1088/1742-6596/721/1/012002

学科分类：力学，机械学

来源: IOP

【 摘 要 】

Slender boiler tubes are subject to localised swelling when they are expose to excessive heat. The latter is due to the formation of an oxide layer, which acts as an insulation barrier. This excessive heat can lead to microstructural changes in the material that would reduce the mechanical strength and would eventually lead to critical and catastrophic failure. Detecting such creep damage remains a formidable challenge for boiler operators. It involves a costly process of shutting down the plant, performing electromagnetic and ultrasonic non-destructive inspection, repairing or replacing damaged tubes and finally restarting the plant to resume its service. This research explores through a model developed using a finite element computer simulation platform the thermal behaviour of slender tubes under constant temperature exceeding 723 °K. Our simulation results demonstrate that hematite layers up to 15 μm thickness inside the tubes do not act as insulation. They clearly show the process of long term overheating on the outside of boiler tubes which in turn leads to initiation of flaws.