Molten Salt Corrosion of Stainless Steels and Low-Cr Steel in CSP Plants

Fernández, Ángel G.; Lasanta, María Isabel; Pérez, F.J.

doi:10.1007/s11085-012-9310-x

Cited by 111 publications

(59 citation statements)

References 23 publications

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“…15 Additionally, it has been reported in previous work that increased nitrite content of the salt mixture results in enhanced oxidative behavior, and that nitrite is continuously formed as time proceeds due to thermal and electrochemical degradation. 16 Stainless steel 316 and Incoloy 800H both experienced significantly lower weight gain rates than Alloy 4130 at 400 and 500…”

Section: Exposure Study Resultsmentioning

confidence: 97%

Corrosion Behavior of Structural Materials for Potential Use in Nitrate Salts Based Solar Thermal Power Plants

Summers

Chidambaram

2017

J. Electrochem. Soc.

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Commercial and economic success of concentrated solar power (CSP) plants requires operating at maximum efficiency and capacity which necessitates the use of materials that are reliable at high temperatures. This study investigates the corrosion behavior of structural alloys in molten nitrate salts at three temperatures common to CSP plants. Corrosion behavior was evaluated using gravimetric and inductively-coupled plasma optical emission spectroscopy (ICP-OES) analysis. Surface oxide structure and chemistry was characterized using X-ray diffraction and Raman spectroscopy. Electrochemical behavior of candidate structural alloys Alloy 4130, austenitic stainless steel 316, and super-austenitic Incoloy 800H was evaluated using potentiodynamic polarization characteristics. Gravimetric and ICP-OES analysis indicated that Alloy 4130 exhibited the least corrosion resistance at 500 • C compared to SS316 and 800H. However, at 300 • C, the three alloys exhibited similar weight gain. Electrochemical evaluation of these candidate materials was observed to correlate well with the corrosion behavior observed from gravimetric and ICP-OES analysis. This study identifies that all three alloys exhibited acceptable corrosion rate in 300 • C molten salt, while elevated salt temperatures require the more corrosion resistant alloys, stainless steel 316 and 800H. Characterization of the sample surfaces revealed the presence of spinels at lower temperatures, while Fe 2 O 3 was the dominant iron oxide at higher temperatures for each alloy. Like all power plants, maximizing the conversion efficiency of solar energy in a concentrated solar power (CSP) plant is essential to minimizing cost and resources while maximizing energy output. The choice of heat transfer fluid is a fundamental parameter in maximizing efficiency of an energy source. A heat transfer fluid that can also function as an energy storage medium for solar energy while being chemically compatible with the structural components of the plant is an ideal candidate for implementation.Significant research had been performed from 1982 to 1985 on the use of molten salt as a heat transfer medium in solar power applications. Sandia National Laboratory in New Mexico conducted the Molten Salt Electric Experiment (MSEE) which was the first power tower system to use molten nitrate salt as the primary working fluid to produce electricity. This experiment proved the feasibility of using molten salt as a heat transfer medium in a central receiver design along with a two-tank storage system designed to address intermittency. 1The MSEE used a molten nitrate salt composition of 40% KNO 3 and 60% NaNO 3 by weight which is the composition used for the study presented herein.Corrosion of structural components is determined by the properties of the heat transfer fluid and corrosion resistance of the components in contact with that heat transfer fluid. Depending on the corrosion resistance of the alloy to a high-temperature, oxidizing environment, the alloy will either form an adherent, compact oxid...

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Section: Exposure Study Resultsmentioning

confidence: 97%

Corrosion Behavior of Structural Materials for Potential Use in Nitrate Salts Based Solar Thermal Power Plants

Summers

Chidambaram

2017

J. Electrochem. Soc.

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“…Therefore, the appropriate material selection and life time estimation requires intensive hot corrosion studies considering different aspects of corrosion environment and material behavior. Recently, corrosion behavior of the common structural materials such as carbon steels, low‐Cr steels, stainless steels, and in some cases Ni‐base alloys have been studied …”

Section: Introductionmentioning

confidence: 99%

High temperature corrosion in molten solar salt: The role of chloride impurities

Dorcheh

Durham

Galetz

2017

Materials & Corrosion

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The role of chloride impurities in molten NaNO3‐KNO3 (solar salt) mixture on corrosion behavior of low‐chromium ferritic‐martensitic X20CrMoV11‐1 steel (X20) and stainless steel 316 (SS316) was studied at 600 °C. Gravimetric and metallographic methods were employed to characterize the kinetics of oxidation and the resulting corrosion products. Steel X20 showed non‐protective character in both low‐ (up to 0.02 wt% Cl−) and high‐ (up to 0.25 wt% Cl−) chloride salts by forming a thick and non‐compact oxide scale. A significant increase in weight gain was observed when X20 steel was immersed in the high‐chloride‐containing salt. Furthermore, the scale underwent severe deformation. SS316 showed superior corrosion resistance in both low‐ and high‐chloride salts. Oxide scales formed on both steels included two zones: an outer Na‐rich oxide and an inner mixed oxide based on Fe2O3 and Fe3O4 structures. The morphology and composition of these zones were significantly different on X20 and SS316 steels. A passive Cr‐rich oxide layer at the metal/oxide interface was characterized as a protective layer. In the case of stainless steel 316 this layer showed even higher continuity when tested in the high‐chloride salt resulting in better protection during the isothermal test.

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“…Results were compared to baseline Solar Salt (60wt.% NaNO 3 -40wt.% KNO 3 ) properties found in the literature [8,9]. Using lithium and calcium nitrate, in small quantities (10wt.%), the salt mixture energy density increased by 19%.…”

Section: Resultsmentioning

confidence: 98%

Thermophysical properties and corrosion characterization of low cost lithium containing nitrate salts produced in northern Chile for thermal energy storage

Fernández

Gomez

Galleguillos

et al. 2016

AIP Conference Proceedings

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Molten Salt Corrosion of Stainless Steels and Low-Cr Steel in CSP Plants

Cited by 111 publications

References 23 publications

Corrosion Behavior of Structural Materials for Potential Use in Nitrate Salts Based Solar Thermal Power Plants

Corrosion Behavior of Structural Materials for Potential Use in Nitrate Salts Based Solar Thermal Power Plants

High temperature corrosion in molten solar salt: The role of chloride impurities

Thermophysical properties and corrosion characterization of low cost lithium containing nitrate salts produced in northern Chile for thermal energy storage

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