Molten chloride salts for next generation CSP plants: Electrolytical salt purification for reducing corrosive impurity level

Ding, Wenjin; Gomez-Vidal, Judith; Bonk, Alexander; Bauer, Thomas

doi:10.1016/j.solmat.2019.04.021

Title: Molten chloride salts for next generation CSP plants: Electrolytical salt purification for reducing corrosive impurity level

Abstract

In this study, electrolysis with a Mg anode is presented to purify the molten chloride salt (MgCl₂/KCl/NaCl 60/20/20 mol.%) for reducing its corrosivity. Using a Mg anode, the production of toxic gases like Cl₂ on an inert anode (e.g., tungsten) can be avoided. Moreover, compared to an inert anode, a lower over-potential is required to remove the corrosive impurity MgOH⁺ in the molten salt due to the high reactivity of Mg. In order to evaluate the effect of the salt purification, the cyclic voltammetry (CV) method developed in our previous work is used to in-situ measure the concentration of the corrosive MgOH⁺ impurity in the molten salt. The CV measurements indicate that the corrosive impurity is efficiently removed by electrolysis. For decreasing the cathode inactivation due to produced MgO on the surface, a pulsed potential applied on the tungsten cathode during electrolysis shows to be promising. This electrochemical salt purification method has shown to be promising by efficiently controlling the corrosivity of the molten chloride salt. The potentiodynamic polarization (PDP) measurements on a commercial high-temperature alloy (Incoloy 800 H) immersed in the molten salt indicate that the corrosion rate of the alloy is significantly reduced due to the salt purification.more »« less

Authors:

Ding, Wenjin ^[1]; Gomez-Vidal, Judith ^[2]; Bonk, Alexander ^[1]; Bauer, Thomas ^[3]

German Aerospace Center (DLR), Inst. of Engineering Thermodynamics, Stuttgart (Germany)
National Renewable Energy Lab. (NREL), Golder, CO (United States). Building and Thermal Sciences Center
German Aerospace Center (DLR), Cologne (Germany). Inst. of Engineering Thermodynamics

Publication Date:: 2019-09-01

Research Org.:: National Renewable Energy Lab. (NREL), Golden, CO (United States)

Sponsoring Org.:: USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:: 1543119

Alternate Identifier(s):: OSTI ID: 1636908

Report Number(s):: NREL/JA-5500-74320
Journal ID: ISSN 0927-0248

Grant/Contract Number:: AC36-08GO28308; AC36-08-GO28308

Resource Type:: Accepted Manuscript

Journal Name:: Solar Energy Materials and Solar Cells

Additional Journal Information:: Journal Volume: 199; Journal Issue: C; Journal ID: ISSN 0927-0248

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 14 SOLAR ENERGY; 47 OTHER INSTRUMENTATION; concentrated solar power (CSP); corrosion control; corrosive impurity; cyclic voltammetry (CV); electrolysis; potentiodynamic polarization (PDP)

Citation Formats


                    Ding, Wenjin, Gomez-Vidal, Judith, Bonk, Alexander, and Bauer, Thomas. Molten chloride salts for next generation CSP plants: Electrolytical salt purification for reducing corrosive impurity level.  United States: N. p., 2019. 
        Web.  doi:10.1016/j.solmat.2019.04.021.

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                    Ding, Wenjin, Gomez-Vidal, Judith, Bonk, Alexander, & Bauer, Thomas. Molten chloride salts for next generation CSP plants: Electrolytical salt purification for reducing corrosive impurity level.  United States.  doi:https://doi.org/10.1016/j.solmat.2019.04.021

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                    Ding, Wenjin, Gomez-Vidal, Judith, Bonk, Alexander, and Bauer, Thomas. Sun .  
        "Molten chloride salts for next generation CSP plants: Electrolytical salt purification for reducing corrosive impurity level".  United States.  doi:https://doi.org/10.1016/j.solmat.2019.04.021.  https://www.osti.gov/servlets/purl/1543119.

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@article{osti_1543119,

  title        = {Molten chloride salts for next generation CSP plants: Electrolytical salt purification for reducing corrosive impurity level},

  author       = {Ding, Wenjin and Gomez-Vidal, Judith and Bonk, Alexander and Bauer, Thomas},

  abstractNote = {In this study, electrolysis with a Mg anode is presented to purify the molten chloride salt (MgCl2/KCl/NaCl 60/20/20 mol.%) for reducing its corrosivity. Using a Mg anode, the production of toxic gases like Cl2 on an inert anode (e.g., tungsten) can be avoided. Moreover, compared to an inert anode, a lower over-potential is required to remove the corrosive impurity MgOH+ in the molten salt due to the high reactivity of Mg. In order to evaluate the effect of the salt purification, the cyclic voltammetry (CV) method developed in our previous work is used to in-situ measure the concentration of the corrosive MgOH+ impurity in the molten salt. The CV measurements indicate that the corrosive impurity is efficiently removed by electrolysis. For decreasing the cathode inactivation due to produced MgO on the surface, a pulsed potential applied on the tungsten cathode during electrolysis shows to be promising. This electrochemical salt purification method has shown to be promising by efficiently controlling the corrosivity of the molten chloride salt. The potentiodynamic polarization (PDP) measurements on a commercial high-temperature alloy (Incoloy 800 H) immersed in the molten salt indicate that the corrosion rate of the alloy is significantly reduced due to the salt purification. It could also lead to a reduction of the cost of the conventional salt purification step, structural container materials, and piping in next generation concentrated solar power (Gen3 CSP) plants.},

  doi          = {10.1016/j.solmat.2019.04.021},

  journal      = {Solar Energy Materials and Solar Cells},

  number       = C,

  volume       = 199,

  place        = {United States},

  year         = {2019},

  month        = {9}

}

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DOI: https://doi.org/10.1016/j.solmat.2019.04.021

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Works referencing / citing this record:

Review of supercritical CO 2 power cycles integrated with CSP
journal, December 2019

Yin, Jun‐Ming; Zheng, Qiu‐Yun; Peng, Zhao‐Rui
International Journal of Energy Research
DOI: 10.1002/er.4909

Review of supercritical CO 2 power cycles integrated with CSP
journal, December 2019

Yin, Jun‐Ming; Zheng, Qiu‐Yun; Peng, Zhao‐Rui
International Journal of Energy Research
DOI: 10.1002/er.4909

Enabling chloride salts for thermal energy storage: implications of salt purity
journal, January 2019

Kurley, J. Matthew; Halstenberg, Phillip W.; McAlister, Abbey
RSC Advances, Vol. 9, Issue 44
DOI: 10.1039/c9ra03133b

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Title: Molten chloride salts for next generation CSP plants: Electrolytical salt purification for reducing corrosive impurity level

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