Corrosion inhibitor

• US 20030230742A1
• Filed: 01/23/2003
• Published: 12/18/2003
• Est. Priority Date: 05/24/2002
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Eric Paul Mistretta, Scott David Trahan
• Inventors: Trahan, Scott David, Mistretta, Eric Paul
• Granted Patent: US 6,953,537 B2
• Time in Patent Office: Days
• US Class Current: 252/387
• CPC Class Codes: C05C 1/00 Ammonium nitrate fertilisers
• CPC Class Codes: C05C 9/00 Fertilisers containing urea or urea compounds
• CPC Class Codes: C05G 5/23 Solutions
• CPC Class Codes: C23F 11/188 containing phosphates
• CPC Class Codes: Y10S 71/04 Anti-corrosion

Abstract

A corrosion inhibitor for use with Urea Ammonium Nitrate solutions is disclosed, comprising a blend of molybdate and one or more of the inorganic phosphates (including phosphates, polyphosphates, and pyrophosphates) and organic phosphates or phosphonates. Inorganic phosphates include, but are not limited to, SHMP (Sodium Hexametaphosphate) and TKPP (Tetra-Potassium Pyrophosphate). There are numerous other inorganic phosphates that will also serve as suitable secondary inhibitors. Organic phosphates or phosphonates include, but are not limited to, HEDP (1-Hydroxyethylidine-1,1-diphosphonic acid; also known as ethanol diphosphonate, acetodiphosphonic acid, or etidronic acid), ATMP or AMP (aminotri(methylenephosphonic acid)), PBTC (Phosphonobutane tricarboxylic acid), DETPMP (Diethylenetriaminepenta(methylene phosphonic acid)), and HPA (hydroxyphosphono acetic acid). There are numerous other organic phosphates and phosphonates that will also serve as suitable secondary inhibitors. The amount of molybdate can range from 1 ppm to 500 ppm by weight of fertilizer solution, with the preferred range from 10 ppm to 200 ppm. Amounts of inorganic or organic phosphate can also range from levels as low as 1 ppm up to 500 ppm, with the preferred range being from 5 ppm to 50 ppm.

Claims

1. A corrosion inhibiting solution for use with Urea Ammonium Nitrate solutions comprising;

between 1 ppm and 500 ppm molybdate by weight of Urea Ammonium Nitrate solution, and between 1 ppm and 500 ppm of a phosphate by weight of Urea Ammonium Nitrate solution.

2. A corrosion inhibiting solution as in claim 1 wherein said phosphate is an inorganic phosphate.

3. A corrosion inhibiting solution as in claim 2 wherein said inorganic phosphate is at least one of the compounds selected from the group consisting of Sodium Hexametaphosphate and Tetra-Potassium Pyrophosphate.

4. A corrosion inhibiting solution as in claim 1 wherein said phosphate is an organic phosphate.

5. A corrosion inhibiting solution as in claim 4 wherein said organic phosphate is at least one of the compounds selected from the group consisting of HEDP (1-Hydroxyethylidine-1,1-diphosphonic acid;

also known as ethanol diphosphonate, acetodiphosphonic acid, or etidronic acid), ATMP or AMP (aminotri(methylenephosphonic acid)), PBTC (Phosphonobutane tricarboxylic acid), DETPMP (Diethylenetriaminepenta(methylene phosphonic acid)), and HPA (hydroxyphosphono acetic acid).

6. A corrosion inhibiting solution as in claim 1 wherein said phosphate is a mixture of inorganic and organic phosphates.

7. A corrosion inhibiting solution as in claim 1 wherein said molybdate is in the form of an alkali metal molybdate.

8. A corrosion inhibiting solution as in claim 1 wherein said molybdate is in the form of sodium molybdate.

1-1. A corrosion inhibiting solution for use with Urea Ammonium Nitrate solutions comprising;

between 1 ppm and 500 ppm molybdate by weight of Urea Ammonium Nitrate solution, and between 1 ppm and 500 ppm of a phosphate by weight of Urea Ammonium Nitrate solution.

9. A corrosion inhibiting solution for use with Urea Ammonium Nitrate solutions comprising;

between 10 ppm and 200 ppm molybdate by weight of Urea Ammonium Nitrate solution, and between 5 ppm and 50 ppm of a phosphate by weight of Urea Ammonium Nitrate solution.

10. A corrosion inhibiting solution as in claim 9 wherein said phosphate is at least one of the compounds selected from the group consisting of Sodium Hexametaphosphate, Tetra-Potassium Pyrophosphate, HEDP (1-Hydroxyethylidine-1,1-diphosphonic acid;

also known as ethanol diphosphonate, acetodiphosphonic acid, or etidronic acid), ATMP or AMP (aminotri(methylenephosphonic acid)), PBTC (Phosphonobutane tricarboxylic acid), DETPMP (Diethylenetriaminepenta(methylene phosphonic acid)), and HPA (hydroxyphosphono acetic acid).

11. A corrosion inhibiting solution as in claim 10 wherein said molybdate is in the form of an alkali metal molybdate.

12. A corrosion inhibiting solution as in claim 10 wherein said molybdate is in the form of sodium molybdate.

13. A method for inhibiting corrosion in ferrous metals subjected to solutions of Urea Ammonium Nitrate, including the step of adding to the solution of Urea Ammonium Nitrate during the production of the solution of Urea Ammonium Nitrate, between 1 ppm and 500 ppm molybdate by weight of Urea Ammonium Nitrate solution and between 1 ppm and 500 ppm of a phosphate by weight of Urea Ammonium Nitrate solution.

14. A method as in claim 13, wherein said phosphate is at least one of the compounds selected from the group consisting of Sodium Hexametaphosphate, Tetra-Potassium Pyrophosphate, HEDP (1-Hydroxyethylidine-1,1-diphosphonic acid;

also known as ethanol diphosphonate, acetodiphosphonic acid, or etidronic acid), ATMP or AMP (aminotri(methylenephosphonic acid)), PBTC (Phosphonobutane tricarboxylic acid), DETPMP (Diethylenetriaminepenta (methylene phosphonic acid)), and HPA (hydroxyphosphono acetic acid).

15. A method as in claim 13, wherein said molybdate is in the form of an alkali metal molybdate.