Claims
- 1. A method of removing clay deposits from surfaces in contact with the water of a cooling water system comprising the steps of:
- (a) maintaining the pH of said water within the range of from about 7 to about 11 throughout the entire method;
- (b) adding to said water a chelant selected from the group consisting of ethylenediaminetetraacetic acid and citric acid;
- (c) subsequently adding to said water a phosphonate or phosphate compound; and
- (d) blowing down said cooling water to remove said deposits.
- 2. The method as recited in claim 1 wherein said phosphonate compound is 1-hydroxyethylidene-1,1-diphosphonic acid or hydroxyphosphonoacetic acid.
- 3. The method as recited in claim 2 wherein from about 300 to 20,000 parts of phosphonate compound is added per million parts of water.
- 4. The method as recited in claim 1 wherein said phosphate compound is tetrapotassiium pyrophosphate, sodium tripolyphosphate or sodium hexametaphosphate.
- 5. The method as recited in claim 4 wherein from about 300 to 20,000 parts of phosphate compound is added per million parts of water.
- 6. The meethod as recited in claim 1 wherein said surfaces in contact with the water of a cooling water system comprise plastic cooling tower fill.
- 7. A method of removing clay deposits from surfaces in contact with the water of a cooling water system consisting essentially of the steps of:
- (a) adding to said water from about 0.002-0.016 moles per liter of a chelant selected from the group consisting of ethylenediaminetetraacetic acid and citric acid;
- (b) subsequently adding to said water from about 300-20,000 parts per million of a phosphonate or phosphate compound; and
- (c) blowing down said cooling water to remove said deposits,
- the pH of said water being within the range of from about 7 to about 11.
- 8. The method as recited in claim 7 wherein said phosphonate compound is 1-hydroxyethylidene-1,1-diphosphonic acid or hydroxyphosphonoacetic acid.
- 9. The method as recited in claim 8 wherein about 600 to 1000 parts of phosphonate compound is added per million parts of water.
- 10. The method as recited in claim 7 wherein said phosphate compound is tetrapotassium pyrophosphate, sodium tripolyphosphate or sodium hexametaphosphate.
- 11. The method as recited in claim 10 wherein about 600 to 1000 parts of phosphate compound is added per million parts of water.
- 12. The method as recited in claim 9 wherein said surfaces in contact with the water of a cooling water system are non-metal surfaces.
Parent Case Info
This is a continuation of application Ser. No. 07/992,194, filed Dec. 17, 1992, now abandoned.
US Referenced Citations (12)
Continuations (1)
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Number |
Date |
Country |
Parent |
992194 |
Dec 1992 |
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