The present paper has been developed during a research focused on innovative methods to manage combined cycle power plants which, nowadays, are more and more subjected to frequent transient conditions. Cycling operations cause the degradation of the components operating at high temperatures, in particular the gas turbine, the steam turbine, the reheater and the high pressure superheater and steam drum in the heat recovery steam generator (HRSG). The study, here presented, is focused on the analysis of the high pressure steam drum which is subjected to large thermal and mechanical stresses. The paper describes the model that has been developed to evaluate the life consumption of the steam drum subjected to low-cycle fatigue due to the transient operating conditions. The calculation has been effected following the guidelines proposed by both the EN13445 and the UNI EN 12952 standards and applied to both the welded and unwelded zones of the steam drum, considering real typical transient conditions for the combined cycle power plant. The main innovation of the developed life consumption model consists in the double approach used to estimate the stress concentration factors; furthermore, the model has been successfully validated and it can be implemented on power plant regulators.

Thermal Stress in Steam Drums: Life Consumption Model

BRACCO, STEFANO
2011

Abstract

The present paper has been developed during a research focused on innovative methods to manage combined cycle power plants which, nowadays, are more and more subjected to frequent transient conditions. Cycling operations cause the degradation of the components operating at high temperatures, in particular the gas turbine, the steam turbine, the reheater and the high pressure superheater and steam drum in the heat recovery steam generator (HRSG). The study, here presented, is focused on the analysis of the high pressure steam drum which is subjected to large thermal and mechanical stresses. The paper describes the model that has been developed to evaluate the life consumption of the steam drum subjected to low-cycle fatigue due to the transient operating conditions. The calculation has been effected following the guidelines proposed by both the EN13445 and the UNI EN 12952 standards and applied to both the welded and unwelded zones of the steam drum, considering real typical transient conditions for the combined cycle power plant. The main innovation of the developed life consumption model consists in the double approach used to estimate the stress concentration factors; furthermore, the model has been successfully validated and it can be implemented on power plant regulators.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/632181
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