Numerical simulation of the heat transfer of superheater tubes in power plants considering oxide scale

Self Cite

This paper proposes a method for predicting the creep rupture life of superheater tubes, considering the continuous increasing metal temperature and stress as a result of oxide formation. The steam-side oxide growth was assessed by the parabolic oxidation rate law, and the temperature profiles of superheater tubes was calculated combining the 3D computational fluid dynamics simulation and the 1D analytical models. Based on the estimated temperature and maximum elastic hoop stress, the parametric extrapolation technique was utilized to assess the creep rupture life. The validity of this method was confirmed by measuring the oxide thickness and the steam temperature in the field. The results found that T91 alloy in the steam outlet region and T23 alloy at the connection point was susceptible to creep rupture failure, which had the greatest cumulative damage and thickest oxide scale. The cumulative damage of superheater tubes varied significantly with tube count. Results suggested that replacement of the particular T91 alloy tubing section having the minimum creep rupture life with a better heat-resistant steel would avoid mechanical failure by creep for the subject boiler system.

Section: The Assessed Creep Rupture Lifementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Creep rupture life assessment of superheater tube with oxide formation in power plant

Jing

et al. 2020

Self Cite

“…Our previous work [25][26][27] presented a numerical simulation of the heat transfer of superheater tubes considering the oxide scale, the effect of temperature on the oxide spallation of T91 alloy superheater tubes, and the influence of local velocity components on FAC behavior at 90°elbow combining electrochemical measurement with CFD simulation. In this study, the FAC rate at 90°elbow of a carbon steel pipeline is studied by an array electrode technique and CFD simulation.…”

Section: Introductionmentioning

confidence: 99%

Investigation of corrosion behavior at elbow by array electrode and computational fluid dynamics simulation

et al. 2020

Self Cite

The present study focuses on the flow-accelerated corrosion (FAC) behavior of A106Gr.B steel at 90°elbow by electrochemical measurement and computational fluid dynamics (CFD) simulation. The FAC rates under turbulent flows with a velocity of 3 and 1.5 m/s were measured by an array electrode technique in a loop system. The experimental results reveal that the maximum FAC rate appears at the extrados of 90°elbow, consistent with the locations from the rupture of the carbon steel piping in the worst cases at elbows. In addition, an effective mass transfer coefficient in consideration of the geometric factor was used to evaluate the FAC rate at intrados and extrados of the 90°elbow by CFD simulation. The predicted results are in good agreement with the experimental values.

The role of Cr atom in the early steam oxidation of Fe‐based alloys: An atomistic simulation

Jing

Liang

et al. 2020

Self Cite

This study employed the density functional theory to capture the atomic‐level dissociation processes of steam and investigate the ions migration on Fe(001) and FeCr(001) surfaces, revealing the role of Cr atom in the early oxidation. Various coadsorption structures with different steam‐derived species have been systematically examined to find the most energetically favored surface site. The results showed that the steam dissociation on the alloy surface underwent two steps. First, H2O molecule on the top site was dissociated into OH group and H atom, which further combined with metal atoms on the bridge site and hollow site. Second, the OH group was decomposed into O and H atoms, which moved to two adjacent hollow sites and generated an oxide. On further oxidation, the Fe atom migrated outward and formed an outer Fe oxide, whereas the Cr oxide could only grow inward as O atom passed through oxide. It was found that the presence of Cr atom on the surface was thermodynamically beneficial, which could promote steam oxidation. The Cr atom could effectively block ion diffusion across the oxide scale and protect the underlying substrate from further oxidation. These results were in good agreement with experimental observation.