Automated corrosion monitoring and control system for molten salt equipment

Patent metadata

Field	Value
Publication number	US-12043904-B2
Application number	US-202016837568-A
Country	US
Kind code	B2
Filing date	Apr 1, 2020
Priority date	Apr 1, 2020
Publication date	Jul 23, 2024
Grant date	Jul 23, 2024

Abstract

The invention provides an in situ method for protecting material exposed to molten salt, the method having the steps of supplying metal in a first nonreactive state to the molten salt to create a mixture; measuring a redox state of the mixture; and transforming the metal to a second reactive state when the redox state indicates corrosion of the material is about to occur. Also provided is a system for preventing corrosion of structural alloys in molten salt environments, the system having a vessel defining a void containing the molten salt; a voltammetry sensor inserted into the molten salt; a first cathode inserted into the molten salt; and a first anode inserted into the molten salt, whereby the cathode and anode are in electrical communication with an electrical power source.

First claim

The embodiment of the invention in which an exclusive property or privilege is claimed is defined as follows:

1. An automated method for protecting material exposed to molten salt, the method comprising:
a. supplying a first metal in a first nonreactive state to the molten salt, which is residing in a vessel to create a mixture;
b. monitoring a redox state of the mixture; and
c. using a noble liquid metal cathode which is confined to an electrically isolated container within the vessel, to transform the first metal in situ to a second reactive state when the redox state indicates corrosion of the material is about to occur, wherein the metal in the second reactive state combines with the noble liquid metal in specific ratios to provide specific reduction potentials of the noble liquid metal cathode.

2. The method as recited in claim 1 wherein the second reactive state of the first metal reduces impurity species out of the molten salt.

3. The method as recited in claim 1 wherein the transforming step is initiated by electrolysis that generates a liquid metal alloy and gaseous products.

4. The method as recited in claim 1 wherein the redox state is measured by monitoring salt potential and salt composition using a dynamic reference electrode built into a voltammetry sensor combined with an electrolysis cell to maintain the specific reduction potentials within a prescribed range.

5. The method as recited in claim 3 wherein the generated liquid metal alloy has a lower reduction potential than the material.

6. The method as recited in claim 1 wherein the material and the molten salt are in constant physical contact.

7. The method as recited in claim 1 wherein the method is made continuous with supplying additional metal in the first nonreactive state into the molten salt.

8. The method as recited in claim 1 wherein the method is conducted at temperatures from 200° ° C. to 1500° C.

9. The method as recited in claim 3 wherein transformation occurs at the noble liquid metal cathode immersed within the molten salt.

10. The method as recited in claim 4 wherein the voltammetry sensor initiates electrolysis to transform the first metal in the first nonreactive state to the second reactive state at the noble liquid metal cathode immersed within the molten salt.

11. The method as recited in claim 1 wherein the reactive first metal in the first nonreactive state is the cation of a salt selected from the group consisting of alkali metals, alkali earth metals, transition metals, lanthanide metals, actinide metals, and combinations thereof.

12. The method as recited in claim 1 wherein the first metal in the first nonreactive state is the cation of a salt selected from the group consisting of LiCl, KCl, NaCl, BeCl 2 , MgCl 2 , CaCl 2 , BaCl 2 , LiF, KF, NaF, BeF 2 , MgF 2 , CaF 2 , BaF 2 , ZrCl 4 , ZrCl 2 , ZrF 2 , ZrF 4 , UCl 3 , UF 3 , PuF 3 , and combinations thereof.

13. The method as recited in claim 1 wherein the first metal in the second nonreactive state is a metal selected from the group consisting of Li, K, Na, Be, Mg, Ca, Ba, and alloys thereof.

14. The method as recited in claim 3 wherein the gaseous products are immediately treated with the first metal in the second reactive state to form an inert product.

15. The method as recited in claim 1 wherein the liquid cathode is electrically isolated from, but in ionic contact with the molten salt when the redox state of the mixture is measured, wherein the electrical isolation is reversible via an electrical bridge.

16. The method as recited in claim 2 wherein the metal in the second reactive state is generated within the container in stoichiometric amounts relative to the impurity species.

17. The method as recited in claim 16 wherein he second reactive metal is confined to the container but in electrical communication with structural metals residing in the molten salt bath to precisely prevent corrosion of the structural metals.

Assignees

• Uchicago Argonne Llc

Inventors

• Hoyt Nathaniel C
• Guo Jicheng
• Williamson Mark A

Classifications

• C23F13/06

  Constructional parts, or assemblies of cathodic-protection apparatus · CPC title

• C23F13/04 Primary

  Controlling or regulating desired parameters · CPC title

• C25C7/06

  Operating or servicing · CPC title

• C25C7/02

  Electrodes (consumable anodes for the refining the metals C25C1/00 - C25C5/00); Connections thereof · CPC title

• C25C3/34

  of metals not provided for in groups C25C3/02 - C25C3/32 · CPC title