Premature Grade 91 failures — worldwide plant operational experiences

Fabricius, Andreas; Jackson, Peter S.

doi:10.1016/j.engfailanal.2016.04.024

Cited by 8 publications

(3 citation statements)

References 3 publications

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“…Superheaters not only suffer from fatigue damage but also face the risk of exceeding their design temperature during low-load and cycling operations, leading to creep damages. 6 It has been reported that superheater damage contributes to about 40% of all boiler unplanned outages, 7 which, in turn, increases the plant equivalent forced outage rate and/or operation and maintenance cost. Thermal fatigue and creep-fatigue interaction can be considerably damaging and can lead to highly localized damages, such as ligament cracking.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Among the critical components, superheaters operating at the highest temperatures are particularly affected by cycling operations. Superheaters not only suffer from fatigue damage but also face the risk of exceeding their design temperature during low-load and cycling operations, leading to creep damages . It has been reported that superheater damage contributes to about 40% of all boiler unplanned outages, which, in turn, increases the plant equivalent forced outage rate and/or operation and maintenance cost.…”

Section: Introductionmentioning

confidence: 99%

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Design and Multiobjective Dynamic Optimization of Superheaters for Load-Following Operation in Pulverized Coal Power Plants

Le,

Ma,

Bhattacharyya

et al. 2023

Ind. Eng. Chem. Res.

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Pulverized coal power plants are increasingly participating in aggressive load-following markets, therefore necessitating the design and optimization of primary superheaters for flexible operations. These superheaters play a critical role in maintaining the final steam temperature of the steam turbine, but their high operating temperatures and pressures make them prone to failure. This study focuses on the optimal design of future-generation primary superheaters for a fast load-following operation. To achieve this, a detailed first-principles model of a primary superheater is developed along with submodels for stress and fatigue damage. Two single-objective optimization problems are solved: one for minimizing metal mass as a measure of capital cost and another for minimizing pressure drop on the steam side as a measure of operating cost. Since these objective functions conflict, a multiobjective optimization problem is executed using a weighted metric methodology. Results from these optimization studies show that the base case design can violate stress constraints during the aggressive load-following operation. However, by optimizing the design variables, it is possible to not only satisfy tight stress constraints but also achieve the desired number of allowable cycles and adhere to the steam outlet temperature constraint. In addition, the optimized design reduces either the metal mass or the steam-side pressure drop compared to that of the base case design. Importantly, this approach is not limited to primary superheaters alone but can also be applied to similar high-temperature heat exchangers in other applications.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Design and Multiobjective Dynamic Optimization of Superheaters for Load-Following Operation in Pulverized Coal Power Plants

Le,

Ma,

Bhattacharyya

et al. 2023

Ind. Eng. Chem. Res.

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“…Welding residual stress is one of the key causes for stress corrosion cracking of weldments [6]. Tensile residual stress is considered to be the critical factor in increasing the sensitivity of fatigue damage of welded joints [7]. Premature failure and fracture of welded joints caused by welding residual stress usually occurred [8,9].…”

Section: Introductionmentioning

confidence: 99%

Optimization Study of Post-Weld Heat Treatment for 12Cr1MoV Pipe Welded Joint

Liu

Zheng³

et al. 2021

Metals

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In order to clarify the role of different post-weld heat treatment processes in the manufacturing process, welding tests, post-weld heat treatment tests, and finite element analysis (FEA) are carried out for 12C1MoV steel pipes. The simulated temperature field and residual stress field agree well with the measured results, which indicates that the simulation method is available. The influence of post-weld heat treatment process parameters on residual stress reduction results is further analyzed. It is found that the post weld dehydrogenation treatment could not release residual stress obviously. However, the residual stress can be relieved by 65% with tempering treatment. The stress relief effect of “post weld dehydrogenation treatment + temper heat treatment” is same with that of “temper heat treatment”. The higher the temperature, the greater the residual stress reduction, when the peak temperature is at 650–750 °C, especially for the stress concentration area. The longer holding time has no obvious positive effect on the reduction of residual stress.

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