Corrosion Resistance of Stainless Steels During Thermal Cycling in Alkali Nitrate Molten Salts

Bradshaw, Robert w.

doi:10.2172/787885

Cited by 14 publications

(23 citation statements)

References 6 publications

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“…Other works that perform longer term exposure studies on similar alloys also show Cr dissolution and the formation of a non-protective iron oxide surface film. 7,8,39 Summary Low alloy steel (Alloy 4130) performed well in molten nitrate salt maintained at 300…”

Section: Discussionmentioning

confidence: 99%

“…Incoloy 800, aluminum and the aluminized steels saw negligible corrosion, while Inconel 600 underwent internal oxidation, titanium rapidly formed an adherent surface oxide film, and nickel experienced severe intergranular corrosion. [6][7][8] Additionally, chemical analysis of the salt following exposure studies revealed that chromium was soluble, and iron and nickel have negligible solubility. The solubility of chromate ions in molten nitrates was found to be significant and kinetically limited to amounts below solubility limits of the melt with no observed concentration above the solubility limit after 5000 hours.…”

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confidence: 99%

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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: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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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“…In a test of resistance of stainless steel during thermal cycling in molten salts, three stainless steel samples are studied with four different mixtures of nitrate salts [241,242]. In the experiment, three stainless steel coupons are immersed in crucibles that contained about 10 kg of the nitrate mixtures.…”

Section: Corrosion Aspectsmentioning

confidence: 99%

“…It is found that the three stainless steel samples have experienced thermal cycling exhibit higher corrosion rate, as compared with those isothermally immersed in the molten salt. Depending on the chloride content of the molten salt, the increase in corrosion rate is between 25 and 50 % [241,242].…”

Section: Corrosion Aspectsmentioning

confidence: 99%

Waste Thermal Energy Harvesting (III): Storage with Phase Change Materials

Kong

Hng

et al. 2014

Waste Energy Harvesting

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In last two chapters, both methods to harvest waste thermal energy through the conversion to electricity. In this chapter, energy storage (ES) as an alternative method to harvest waste thermal energy, especially by using phase change materials (PCMs), will be presented.ES, as suggested by the name, is to store a certain form of energy, which thus be used later when necessary. A device that can be used to store any form of energy is generally called an accumulator. There are various forms of energy, commonly including kinetic energy, potential energy (e.g., gravitational or chemical), electrical energy, thermal energy, and so on. All these forms of energy could be stored by using an appropriate method [1,2]. For instance, mechanical energy can be stored by using hydrostorage, compressed air storage, and flywheels, while electrical energy is stored by using various batteries and supercapacitors. Thermal energy storage (TES) is the main content of this chapter.This chapter is arranged as follows. A brief description on various TES conceptions, together with a comparison, will be presented first. Among them, PCMs for TES will be emphasized. After that, PCMs with their classification according to their composition will be discussed. Design criteria, heat transfer phenomena, configuration of various PCM TES systems, which have been reported in open literature, will be summarized. Specific attention will be paid to the exergy analysis. The main applications of the PCM storage systems will be listed, analyzed, and compared. Strategies that have been used to improve the performance of such storage systems will be thoroughly evaluated. It will be ended with concluding remarks and perspectives of development of this technology.

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“…Material degradation is one of the major concerns at HT; therefore, many efforts have been focused to reduce the effect of degradation issues such as creep damage, microstructural degradation, fatigue and creep-fatigue phenomena, erosion, thermal shocks, HT corrosion etc. [29][30][31]. Nowadays, some promising materials, both metallic and ceramic, show suitable properties to be taken into consideration for HT applications [32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Charge and Discharge Analyses of a PCM Storage System Integrated in a High-Temperature Solar Receiver

Giovannelli

Bashir

2017

Energies

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Solar Dish Micro Gas Turbine (MGT) systems have the potential to become interesting small-scale power plants in off-grid or mini-grid contexts for electricity or poly-generation production. The main challenging component of such systems is the solar receiver which should operate at high temperatures with concentrated solar radiations, which strongly vary with time. This paper deals with the design and the analysis of a novel solar receiver integrated with a short-term storage system based on Phase Change Materials to prevent sudden variations in the maximum temperature of the MGT working fluid. Particularly, the charge and discharge behavior of the storage system was analyzed by means of Computational Fluid Dynamic methods to evaluate the potentiality of the concept and the component capabilities. Achieved results were highly satisfactory: the novel solar receiver has a good thermal inertia and can prevent relevant fluctuations in the working fluid temperature for 20-30 min.

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Corrosion Resistance of Stainless Steels During Thermal Cycling in Alkali Nitrate Molten Salts

Cited by 14 publications

References 6 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

Waste Thermal Energy Harvesting (III): Storage with Phase Change Materials

Charge and Discharge Analyses of a PCM Storage System Integrated in a High-Temperature Solar Receiver

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