US4623399A
Expired / Lapsed
US
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Solvent for removing iron oxide deposits
Assignee: General Electric Co
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Filing: 1985-02-04
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Granted: 1986-11-18
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Expires: 2005-02-04
Abstract
Abstract Liquid and foam formulations useful for removing iron oxide deposits, for example from heat transfer equipment, comprising an organic solution or foam of N-hydroxylethyl ethylenediamine triacetic acid and an organic acid (for example, formic acid); and a method of removing iron oxide deposits from encrusted equipment surfaces by injecting the liquid or foam formulation, preferably also containing a corrosion inhibitor, into equipment to be cleaned, and circulating the liquid or foam formulation.
Inventors
- 👤 Wayne W. Frenier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:17
CPC Classifications
C; C23; C23G; C23G1/00; C23G1/02; C23G1/08; C23G1/088
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
78 words
An improved aqueous acid composition to dissolve iron oxide deposits, comprising: (a) N-hydroxyethyl ethylenediamine triacetic acid, and (b) an organic acid selected from the group consisting of water soluble aliphatic monocarboxylic, aliphatic polycarboxylic, and aliphatic hydroxylated mono- or polycarboxylic acid, in an amount effective to increase the rate of dissolution of iron oxide deposits beyond the rate of dissolution thereof by the composition absent said organic acid, said aqueous acid composition having a pH less than about 3.
Claim 2
Dependent Claim
78 words
An improved aqueous acid composition to dissolve iron oxide deposits, comprising: (a) N-hydroxyethyl ethylenediamine triacetic acid, and (b) an organic acid selected from the group consisting of water soluble aliphatic monocarboxylic, aliphatic polycarboxylic, and aliphatic hydroxylated mono- or polycarboxylic acid, in an amount effective to increase the rate of dissolution of iron oxide deposits beyond the rate of dissolution thereof by the composition absent said organic acid, said aqueous acid composition having a pH less than about 3.
Claim 3
Dependent Claim
13 words
The aqueous acid composition set forth in claim 1, including a corrosion inhibitor.
Claim 4
Dependent Claim
13 words
The aqueous acid set forth in claim 2, wherein (b) is formic acid.
Claim 5
Dependent Claim
13 words
The aqueous acid set forth in claim 2, wherein (b) is acetic acid.
Claim 6
Dependent Claim
13 words
The aqueous acid set forth in claim 2, wherein (b) is propionic acid.
Claim 7
Dependent Claim
13 words
The aqueous acid set forth in claim 2, wherein (b) is fumaric acid.
Claim 8
Dependent Claim
13 words
The aqueous acid set forth in claim 2, wherein (b) is maleic acid.
Claim 9
Dependent Claim
13 words
The aqueous acid set forth in claim 2, wherein (b) is citric acid.
Claim 10
Dependent Claim
13 words
The aqueous acid set forth in claim 2, wherein (b) is glycolic acid.
Claim 11
Dependent Claim
13 words
The aqueous acid set forth in claim 2, wherein (b) is lactic acid.
Claim 12
Dependent Claim
28 words
The aqueous acid composition set forth in claim 2, wherein (b) is a water soluble aliphatic carboxylic acid having one to four carbon atoms in its longest chain.
Claim 13
Dependent Claim
99 words
A process for dissolving iron oxide deposits on a ferrous metal surface, comprising: contacting said iron oxide deposits with an aqueous acid composition comprising N-hydroxyethyl ethylenediamine triacetic acid, and an organic acid selected from the group consisting of water soluble aliphatic monocarboxylic, aliphatic polycarboxylic, and aliphatic hydroxylated mono- or polycarboxylic acid, in an amount effective to increase the rate of dissolution of iron oxide deposits beyond the rate of dissolution thereof by the composition absent said organic acid said aqueous acid composition having a pH less than about 3 for a time sufficient to dissolve said iron oxide deposits.
Claim 14
Dependent Claim
99 words
A process for dissolving iron oxide deposits on a ferrous metal surface, comprising: contacting said iron oxide deposits with an aqueous acid composition comprising N-hydroxyethyl ethylenediamine triacetic acid, and an organic acid selected from the group consisting of water soluble aliphatic monocarboxylic, aliphatic polycarboxylic, and aliphatic hydroxylated mono- or polycarboxylic acid, in an amount effective to increase the rate of dissolution of iron oxide deposits beyond the rate of dissolution thereof by the composition absent said organic acid said aqueous acid composition having a pH less than about 3 for a time sufficient to dissolve said iron oxide deposits.
Claim 15
Dependent Claim
32 words
The process set forth in claim 12, including dissolving said iron oxide deposits in said aqueous acid composition until said ferrous metal surface is at least substantially free of iron oxide deposits.
Claim 16
Dependent Claim
33 words
The process set forth in claim 13, including passivating said ferrous metal surface at least substantially free of iron oxide deposits with an alkaline liquid having an oxidant dissolved, dispersed, or entrained therein.
Claim 17
Dependent Claim
21 words
The process set forth in claim 13, wherein said alkaline liquid has a pH of from about 8 to about 10.
Claim 18
Dependent Claim
21 words
The process set forth in claim 13, wherein said oxidant is gaseous oxygen or gaseous air, and an alkali metal nitrite.
Claim 19
Dependent Claim
30 words
The process set forth in claim 13, wherein said aqueous acid composition contacts and dissolves said iron oxide deposits at a temperature from about 70° C. to about 85° C.
Claim 20
Dependent Claim
29 words
The process set forth in claim 14, wherein said alkaline liquid and oxidant passivate said ferrous metal surface at a temperature from about 65° C. to about 70° C.
Claim 21
Dependent Claim
18 words
The process set forth in claim 14, wherein said oxidant is ferric salt of N-hydroxyethyl ethylenediamine triacetic acid.
Claim 22
Dependent Claim
15 words
The process set forth in claim 12, wherein said aqueous acid composition is a liquid.
Claim 23
Dependent Claim
15 words
The process set forth in claim 12, wherein said aqueous acid composition is a foam.
Claim 24
Dependent Claim
18 words
The process set forth in claim 12, wherein the pH of the composition is no greater than 2.5.
Claim 25
Dependent Claim
24 words
The process set forth in claim 13, wherein the pH of the composition is no greater than 2.5 and is at least about 1.5.
Claim 26
Dependent Claim
27 words
The process set forth in claim 22, wherein the ratio by weight of said organic acid to N-hydroxyethyl ethylenediamine triacetic acid, is between 1/2 to about 1/1.
Claim 27
Dependent Claim
19 words
The process set forth in claim 23 wherein, said organic acid is formic acid, citric acid or glycolic acid.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-11-17 | 1990-05-19 | 1990-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-17 | 1994-05-19 | 1994-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-17 | 1998-05-19 | 1998-11-18 | $7700.00 | Window Closed / Lapsed |