Corrosion inhibition in hydrothermal processing

Patent metadata

Field	Value
Publication number	US-10688464-B2
Application number	US-201715613616-A
Country	US
Kind code	B2
Filing date	Jun 5, 2017
Priority date	Jun 5, 2017
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

The disclosed technology relates to methods of inhibiting corrosion in reaction chambers configured for hydrothermal reaction of feeds containing a heteroatom. An embodiment of such a method comprises providing a feed stream comprising a phosphorus-containing material, an alkali metal compound, water, and a corrosion-inhibitor. The embodiment additionally includes introducing the feed stream and oxidant into a reactor chamber and oxidizing the phosphorus-containing material at an oxidation temperature greater than about 374° C. and an oxidation pressure exceeding about 25 bar, wherein the reactor chamber has inner surfaces comprising a material that corrodes when in contact with a phosphorus compound within the reactor. The embodiment additionally includes selectively reacting the corrosion-inhibitor with phosphorus within the reactor, thereby precipitating in the reactor chamber a phosphorus-containing solid inorganic compound. The embodiment further includes forming in the reactor chamber an alkali salt melt and carrying away from the reactor chamber a mixture comprising the solid phosphorus-containing inorganic compound and the alkali salt melt.

First claim

What is claimed is:

1. A method of inhibiting corrosion in a hydrothermal system during hydrothermal treatment of a feed material, comprising:
providing a hydrothermal reactor having an inner surface that is susceptible to corrosion at a hydrothermal operating condition, the hydrothermal operating condition comprising a temperature greater than about 374° C. and a pressure greater than about 25 bar;
introducing to the hydrothermal reactor a feed stream comprising the feed material, the feed material comprising a corrosive agent that is corrosive to the inner surface of the hydrothermal reactor at the hydrothermal operating condition, the corrosive agent comprising phosphorus;
introducing to the hydrothermal reactor a corrosion inhibitor that selectively reacts with the corrosive agent to form an insoluble inorganic compound at the hydrothermal operating condition;
introducing to the hydrothermal reactor melt-forming constituents in an amount effective to form a salt melt at the hydrothermal operation condition, the salt melt comprising the insoluble inorganic compound;
operating the hydrothermal reactor at the hydrothermal operating condition for a period of time effective to treat the feed material; and
removing at least a portion of the salt melt from the hydrothermal reactor.

2. The method of claim 1 , wherein an area of the inner surface that is in contact with the feed stream during the operating corrodes at a rate of less than 1 mil per hour during the operating of the hydrothermal reactor at the hydrothermal operating condition.

3. The method of claim 1 , wherein the corrosion inhibitor comprises magnesium (Mg) or calcium (Ca).

4. The method of claim 1 , wherein the salt melt comprises a mixture of sodium salts.

5. The method of claim 4 , wherein the sodium salt comprises two or more anionic elements selected from the group consisting of Cl, S, F and P.

6. The method of claim 1 , wherein the inner surface of the hydrothermal reactor chamber comprises titanium (Ti).

7. The method of claim 1 , wherein the feed material is an organic waste that contains an organophosphorus compound.

8. The method of claim 7 , wherein the corrosive agent comprises a phosphorus-containing acid or salt formed by reaction of the organophosphorus compound at the hydrothermal operating condition.

9. A method of oxidizing a feed material, comprising:
providing a feed stream comprising water, a corrosion inhibitor, a waste feed comprising a phosphorus compound and melt-forming agents that form an alkali metal salt melt at a temperature greater than about 374° C. and a pressure exceeding about 25 bar;
introducing the feed stream and an oxidant into a reactor chamber and oxidizing the feed stream at the temperature and pressure, wherein the reactor chamber has an inner surface comprising a material which is susceptible to corrosion when in contact with a phosphorus-containing corrosive agent formed from the phosphorus compound in the reactor chamber;
selectively reacting the corrosion inhibitor with the phosphorus-containing corrosive agent, thereby precipitating in the reactor chamber a solid phosphorus-containing inorganic compound;
forming in the reactor chamber an alkali salt melt; and
flowing away from the reactor chamber a mixture comprising the solid phosphorus-containing inorganic compound and the alkali salt melt.

10. The method of claim 9 , wherein the corrosion inhibitor is a compound comprising an alkaline earth metal, and wherein selectively reacting the corrosion inhibitor with the phosphorus-containing corrosive agent comprises reacting the alkaline earth metal with the phosphorus-containing corrosive agent in the reactor chamber.

11. The method of claim 10 , wherein precipitating the solid phosphorus-containing inorganic compound comprises precipitating an alkaline earth metal phosphate.

12. The method of claim 10 , wherein the alkaline earth metal is magnesium (Mg) or calcium (Ca).

13. The method of claim 12 , wherein providing the corrosion inhibitor comprises providing a compound selected from the group consisting of magnesium nitrate (Mg(NO 3 ) 2 calcium nitrate (Ca(NO 3 ) 2 ), magnesium nitrite (Mg(NO 2 ) 2 ) and calcium nitrite (Ca(NO 2 ) 2 ).

14. The method of claim 9 , wherein the alkali salt melt is a melt of sodium (Na) salts.

15. The method of claim 14 , wherein the sodium salt melt comprises two or more anion-forming elements selected from the group consisting of Cl, S, and F, and wherein selectively reacting the corrosion inhibitor with the phosphorus-containing corrosive agent includes selectively reacting against one or more of anion-forming elements.

16. The method of claim 9 , wherein the inner surface of the reactor chamber comprises titanium (Ti).

17. A method of inhibiting corrosion in a supercritical water oxidation (SCWO) system during oxidation of an organic waste material at a SCWO operating condition, comprising:
providing a SCWO reactor having a titanium inner surface;
introducing to the SCWO reactor a feed stream comprising the organic waste material, the organic waste material comprising an organophosphorus compound;
introducing to the SCWO reactor an alkaline earth compound that selectively reacts with phosphorus of the organophosphorus compound to form an insoluble phosphorus-containing compound under SCWO conditions, the alkaline earth compound comprising at least one of magnesium and calcium;
introducing to the hydrothermal reactor sodium-containing salt constituents in an amount effective to form a salt melt at the hydrothermal operation condition, the salt melt comprising the insoluble phosphorus-containing compound;
operating the SCWO reactor at the SCWO operating condition for a residence time effective to treat the organic waste material and thereby release phosphorus; and
removing at least a portion of the salt melt from the SCWO reactor.

18. The method of claim 17 , wherein the alkaline earth compound is selected from the group consisting of calcium hydroxide, calcium carbonate, calcium chloride, calcium sulfate, calcium oxide, magnesium hydroxide, magnesium carbonate, magnesium chloride, magnesium sulfate, magnesium oxide, and mixtures thereof.

19. The method of claim 17 , wherein the sodium-containing salt constituents include one or both of sodium chloride and sodium sulfate.

Assignees

• General Atomics

Inventors

• Hong Glenn Thomas
• Downey Kevin William

Classifications

• C02F5/06

  using calcium compounds · CPC title

• C02F5/083

  Mineral agents · CPC title

• C02F5/02

  Softening water by precipitation of the hardness · CPC title

• B01J2219/0236

  Metal based · CPC title

• C02F5/08

  Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents · CPC title