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Patent US4454046A successfully refreshed from Google Patents.
US4454046A
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Boiler scale prevention employing an organic chelant
Assignee: Dow Chemical Co
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Filing: 1982-09-07
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Granted: 1984-06-12
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Expires: 2002-09-07
Abstract
Abstract An improved method of treating boiler water which employs an oxygen scavenging compound and a compound to control pH together with a chelating agent, wherein the chelating agent is hydroxyethylethylenediaminetriacetic acid.
Inventors
- 👤 Steven L. Wallace
- 👤 Freddie Griffin, Jr.
- 👤 Thorwald J. Tvedt, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:33
CPC Classifications
C; C02; C02F; C02F5/00; C02F5/08; C02F5/10; C02F5/12; C23; C23F; C23F11/00; C23F11/08
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
127 words
In a process for the prevention of scale and corrosion in boilers from water containing Fe ++ , Ca ++ , or Mg ++ ions wherein the boiler water is treated with an effective amount of hydrazine as an oxygen scavenger, ammonium hydroxide as a pH control compound and a chelating compound, and wherein the pH is controlled at a value of from about 7 to about 12, the temperature is from about 100° to about 374° C., and the pressure is from about 15 to about 3200 psia the improvement which comprises adding to the boiler water as the chelating compound hydroxyethylethylenediaminetriacetic acid in an amount of from about 1 to about 10 moles of chelant per mole of scale or corrosion producing metal ions present.
Claim 2
Dependent Claim
127 words
In a process for the prevention of scale and corrosion in boilers from water containing Fe ++ , Ca ++ , or Mg ++ ions wherein the boiler water is treated with an effective amount of hydrazine as an oxygen scavenger, ammonium hydroxide as a pH control compound and a chelating compound, and wherein the pH is controlled at a value of from about 7 to about 12, the temperature is from about 100° to about 374° C., and the pressure is from about 15 to about 3200 psia the improvement which comprises adding to the boiler water as the chelating compound hydroxyethylethylenediaminetriacetic acid in an amount of from about 1 to about 10 moles of chelant per mole of scale or corrosion producing metal ions present.
Claim 3
Dependent Claim
26 words
The process of claim 1 wherein the hydroxyethylethylenediaminetriacetic acid is added in the form of an alkali metal, ammonia or amine salts or a combination thereof.
Claim 4
Dependent Claim
17 words
The process of claim 2 wherein the pH of the boiler water is from 9 to 10.
Claim 5
Dependent Claim
27 words
The process of claim 1 or 2 wherein the chelating agent is employed in a ratio from about 1.2 to 2 for each mole of metal ion.
References Cited (Backward Citations)
US1997256A
Cited
US3099521A
Cited
US3235324A
Cited
US3492240A
Cited
US3463730A
Cited
US3549538A
Cited
US3527609A
Cited
US3684720A
Cited
US4011171A
Cited
US4306991A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-06-12 | 1987-12-12 | 1988-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-06-12 | 1991-12-12 | 1992-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-06-12 | 1995-12-12 | 1996-06-12 | $7700.00 | Window Closed / Lapsed |