Automated corrosion monitoring and control system for molten salt equipment

Patent metadata

Field	Value
Publication number	US-2021310132-A1
Application number	US-202016837568-A
Country	US
Kind code	A1
Filing date	Apr 1, 2020
Priority date	Apr 1, 2020
Publication date	Oct 7, 2021
Grant date	—

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 metal in a first nonreactive state to the molten salt to create a mixture; b. measuring a redox state of the mixture; and c. transforming the metal in situ to a second reactive state when the redox state indicates corrosion of the material is about to occur.

2 . The method as recited in claim 1 wherein the second reactive state of the 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.

4 . The method as recited in claim 1 wherein the redox state is measured by monitoring salt potential and salt composition using a voltammetry sensor.

5 . The method as recited in claim 1 wherein the metal has a lower reduction potential than the material.

6 . The method as recited in claim 1 wherein the material and 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 reactive 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 a cathode immersed within the molten salt.

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

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

14 . A system for preventing corrosion of structural alloys in molten salt environments, the system comprising:
a) a vessel defining a void containing the molten salt; b) a voltammetry sensor inserted into the molten salt; c) an electrically isolated first cathode inserted into the molten salt; and d) a first anode inserted into the molten salt, whereby the cathode and anode are in electrical communication with an electrical power source.

15 . The system as recited in claim 14 further comprising an electrode connecting the first cathode to the vessel.

16 . The system as recited in claim 14 wherein an electrical bridge selected from the group consisting of a relay, a switch, and combinations thereof connects the first cathode to the vessel.

17 . The system as recited in claim 16 wherein the electrical bridge is adapted to be actuated when reactive metal is available on the sacrificial anode to provide corrosion protection.

18 . The system as recited in claim 14 further comprising a means for evacuating gas generated at the anode.

19 . The system as recited in claim 14 wherein the vessel provides a means for preventing fluid exchange between its void and an ambient atmosphere.

20 . The system as recited in claim 14 further comprising additional anodes specific for removing specific salt impurities.

Assignees

• Uchicago Argonne Llc

Inventors

• Hoyt Nathaniel C
• Guo Jicheng
• Williamson Mark A

Classifications

• C25C7/06

  Operating or servicing · CPC title

• C23F13/04 Primary

  Controlling or regulating desired parameters · CPC title

• C25C3/34

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

• C25C3/26

  of titanium, zirconium, hafnium, tantalum or vanadium · CPC title

• C25C3/02 Primary

  of alkali or alkaline earth metals · CPC title