CA1269229A - Method for prevention of phosphonate decomposition by chlorine - Google Patents
Method for prevention of phosphonate decomposition by chlorineInfo
- Publication number
- CA1269229A CA1269229A CA000517001A CA517001A CA1269229A CA 1269229 A CA1269229 A CA 1269229A CA 000517001 A CA000517001 A CA 000517001A CA 517001 A CA517001 A CA 517001A CA 1269229 A CA1269229 A CA 1269229A
- Authority
- CA
- Canada
- Prior art keywords
- acid
- chlorine
- ppm
- waters
- decomposition
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
- C02F5/10—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances
- C02F5/14—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances containing phosphorus
Abstract
ABSTRACT OF THE DISCLOSURE
The decomposition of phosphonates by chlorine in industrial process waters can be diminished or prevented by treating such waters with certain water-soluble nitrogen-containing compounds.
The decomposition of phosphonates by chlorine in industrial process waters can be diminished or prevented by treating such waters with certain water-soluble nitrogen-containing compounds.
Description
- 1~
INTRODUCTION
The use of phosphonates for scale control in recirculating cooling water is widely practiced as is the use of chlorine for microbiological control. However, the use of these two practices simultaneously can cause problems. Chlorine has been demonstrated to break down many phosphonates to a significant extent. When this happens in a field application, the effectiveness of the phosphonate as a scale control agent is degraded and the orthophosphate which is a product of this reaction can contribute to scaling problems. Even some reputedly chlorine-resistant phosphonates such as l,l-hydroxyethylidsne diphosphonic acid (HEDP) are not sufficiently stable for some industrial applications where continuous chlorination is practiced. Under carefully controlled conditions where the free chlorine residual is kept at a low constant level, breakdown of HEDP is minimal. However, under the less well controlled environment found in a typical plant cooling circuit, excessive chlorine levels are frequently observed. Under these conditions, HEDP or other phosphonates can break down to a sufficient degree to cause problems. Additionally, a number of dissolved ions typically found in cooling waters have been found to catalyze the breakdown of phosphonates.
Prior Art It is well known that sulfamic acid, ammonia and amines and amides are effective as chlorine stabilizers. There are several publications and patents relating to this application, particularly for swimming pool applications. U.S. 3,170,883 describes the use of sulfamic acid in cooling towers as a chlorine stabilizer.
~ 9~ ~ 66530-415 The use of phosphonates in cooling towers for scale control is also well known. There is a large body of literature on this topic. However, no prior art on the concurrent use of chlorine and chlorine stabilizers in conjunction with phosphonates to reduce their decomposition has been found.
Description of the Invention It has been unexpectedly found that the use of a compound which reversibly reacts with chlorine can greatly reduce the extent of decomposition of phosphonates by chlorine.
This compound acts as a buffer for chlorine, providing a reserve of combined chlorine and a continuously available low level of free chlorine. The invention, therefore, consists of the use of a "stabilizer" in conjunction with a "phosphonate"
in an aqueous system to which chlorine or hypochlorites are added. These stabilizers are water-soluble nitrogen-containing compounds such as sulfamic acid, ammonia, amines, urea, and others. The combination of the stablizer and the phosphonate therefore gives more effective scale control in the presence of chlorine than does the phosphonate by itself.
The Invention The invention provides a method of preventing the decomposition of phosphonates from the group consisting of:
l,l-hydroxyethylidene diphosphonic acid; tris aminomethane phosphonic acid; l-phosphonoglycolic acid; ethylene diamine tetra(methylenephosphonic acid): Hexamethylene diamine tetra(methylenephosphonic acid); and, diethylene triamine penta(methylenephosphonic acid); which are present in an effective amount to prevent scale in industrial cooling waters which contain an effective amount of chlorine for micro-~ - 3 -~69~Z9 66530-415 biological control which comprises treating said waters with at least 1/4 ppm of sulfamic acid for each ppm of C12 present in these waters.
. ~ - 3a -~,, ~ 1'~
¦ The invention is capable of treating industrial cooling ¦waters having a pH within the range of between 3 - 12 and ¦preferably 6 - 9.
¦ The Phosphonates ¦ Phosphonates which are relevant to the invention include any phosphonate which is degraded by chlorine, but especially:
(1) l,l-hydroxyethylid~ne diphosphonic acid (HEDP);
INTRODUCTION
The use of phosphonates for scale control in recirculating cooling water is widely practiced as is the use of chlorine for microbiological control. However, the use of these two practices simultaneously can cause problems. Chlorine has been demonstrated to break down many phosphonates to a significant extent. When this happens in a field application, the effectiveness of the phosphonate as a scale control agent is degraded and the orthophosphate which is a product of this reaction can contribute to scaling problems. Even some reputedly chlorine-resistant phosphonates such as l,l-hydroxyethylidsne diphosphonic acid (HEDP) are not sufficiently stable for some industrial applications where continuous chlorination is practiced. Under carefully controlled conditions where the free chlorine residual is kept at a low constant level, breakdown of HEDP is minimal. However, under the less well controlled environment found in a typical plant cooling circuit, excessive chlorine levels are frequently observed. Under these conditions, HEDP or other phosphonates can break down to a sufficient degree to cause problems. Additionally, a number of dissolved ions typically found in cooling waters have been found to catalyze the breakdown of phosphonates.
Prior Art It is well known that sulfamic acid, ammonia and amines and amides are effective as chlorine stabilizers. There are several publications and patents relating to this application, particularly for swimming pool applications. U.S. 3,170,883 describes the use of sulfamic acid in cooling towers as a chlorine stabilizer.
~ 9~ ~ 66530-415 The use of phosphonates in cooling towers for scale control is also well known. There is a large body of literature on this topic. However, no prior art on the concurrent use of chlorine and chlorine stabilizers in conjunction with phosphonates to reduce their decomposition has been found.
Description of the Invention It has been unexpectedly found that the use of a compound which reversibly reacts with chlorine can greatly reduce the extent of decomposition of phosphonates by chlorine.
This compound acts as a buffer for chlorine, providing a reserve of combined chlorine and a continuously available low level of free chlorine. The invention, therefore, consists of the use of a "stabilizer" in conjunction with a "phosphonate"
in an aqueous system to which chlorine or hypochlorites are added. These stabilizers are water-soluble nitrogen-containing compounds such as sulfamic acid, ammonia, amines, urea, and others. The combination of the stablizer and the phosphonate therefore gives more effective scale control in the presence of chlorine than does the phosphonate by itself.
The Invention The invention provides a method of preventing the decomposition of phosphonates from the group consisting of:
l,l-hydroxyethylidene diphosphonic acid; tris aminomethane phosphonic acid; l-phosphonoglycolic acid; ethylene diamine tetra(methylenephosphonic acid): Hexamethylene diamine tetra(methylenephosphonic acid); and, diethylene triamine penta(methylenephosphonic acid); which are present in an effective amount to prevent scale in industrial cooling waters which contain an effective amount of chlorine for micro-~ - 3 -~69~Z9 66530-415 biological control which comprises treating said waters with at least 1/4 ppm of sulfamic acid for each ppm of C12 present in these waters.
. ~ - 3a -~,, ~ 1'~
¦ The invention is capable of treating industrial cooling ¦waters having a pH within the range of between 3 - 12 and ¦preferably 6 - 9.
¦ The Phosphonates ¦ Phosphonates which are relevant to the invention include any phosphonate which is degraded by chlorine, but especially:
(1) l,l-hydroxyethylid~ne diphosphonic acid (HEDP);
(2) tris aminomethane phosphonic acid (AMP);
(3) l-phosphono glycolic acid (PGA);
(4) ethylene diamine tetra(methylenephosphonic acid) (ENTP);
(5) hexamethylene diamine tetra(methylenephosphonic acid) (HMTP);
(6) diethylene triamine penta(methylenephosphonic acid)~
As indicated, the phosphonates are well known materials and are described in the following patents: U.S. 3,214,454, U.S.
4,026,815, U.S. 3,336,221, and U.S. 3,278,446. They all may be used as the free acid or their water-soluble salt form.
The Stabilizers The stabilizer can be any compound which reacts reversibly with chlorine, sodium or calcium hypochlorite or hypochlorous acid. These are all considered as chlorine for the purposes of this disclosure. Compounds which have been identified as being particularly effacacious for this application are:
~X~j9~X5~
(a) water-soluble primary and secondary amines or amides;
(b) ammonia;
(c) sulfamic acid and its water-soluble salts;
(d) water-soluble amides.
The sulfamic acid may be used as such or it may be used as its water-soluble salts, e.g. alkali metal ammonia or amine salts.
The water-soluble primary or secondary amines may be selected from a large number of compounds. Typical are methylamine, dimethylamine, ethylamine, diethylamine, propylamine, dipropylamine, methylethylamine, mono and diethanolamines, morpholine, pyrridine, and any other amine that is capable of reacting as a chlorine stabilizer.
The Water-Soluble Amides The water-soluble amides may be selected from a wide group of compounds. The preferred amides are urea, hydantoin, and cyanuric acid. Other water-soluble amides such as acetamide may be used.
Evaluation of the Invention Experimental Procedures The experimental procedures used fall into three categories.
Benchtop Bottle Tests Test solutions containin9 a synthetic cooling tower water were prepared in 200 ml amber bottles. These solutions were prepared from deionized water and reagent grade salts.
~ 1~6~29 ¦Appropriate commercial grade phosphonates, candidate chlorine stabilizers and chlorine were then added to the solution. The final composition of the test solutions were:
Calcium 500 ppm (CaC03) Magnesium 200 ppm (CaC03) Bicarbonate 300 ppm (CaC03) pH 8.5 Phosphonate 5.0 ppm (P04) Chlorine 12 ppm (C12) Stabilizer varied The solution described above was prepared, stored at room temperature for 48 hours and analyzed for total phosphate and (organic + ortho phosphate). The degree of decomposition was then determined from the amount of orthophosphate generated.
Pilot Cooling Tower Test The use of sulfamic acid for phosphonate stabilization was then tested in a pilot cooling tower (PCT) apparatus. This device is described in the article:
"Small-Scale Short-Term Methods of Evaluating Cooling Water Treatments. . . Are They Worthwhile?," D. T. Reed and R.
Nass, Nalco Chemical Company, International Water Conference, Pittsburgh, PA, Nov. 4-6, 1975. The PCT test was used to determine:
(1) decomposition of phosphonate by chlorine in the absence of any stabilizer;
(2) the effect of sulfamic acid in reducing this decomposition.
The composition of the water in the pilot cooling tower was four concentrations of synthetic lake water. No pH control 69;~
was used and the water was allowed to reach the equilibrium pH
value of 9.û - 9.2. Chlorine was introduced into the system by a constant feed of 7.25% sodium hypochlorite. A scale control program containing 6% of HEDP for scale control was fed to the tower at a rate proportional to the blowdown, resulting in a constant theoretical level of HEDP in t~e tower. The concentration ratio of the tower was held constant by a conductivity controller. A complete analysis of the composition of the tower water was done on a daily basis. rhe experiment was conducted in two phases:
1. With all other factors held constant, the rate of addition of sodium hypochlorite was steadily increased and the effect on the HEDP and orthophosphate residuals observed.
2. Once a steady state of HEDP decomposition was obtained in the tower, feed of sulfamic acid was commenced and the effect on HEDP and orthophosphate levels observed. The extent of decomposition was deduced from these data.
Field Evaluation A field evaluation of this invention was conducted at a midwest polyethylene plant. This plant has a large cooling tower system which contains over a million gallons of water. The holding time of this system is exceptionally long. This plant has been using a product containing HEDP for some time and has also been practicing continuous chlorination. It has had a history of operating problems which have been related to HEDP
breakdown. The field evaluation was conducted in two phases:
1. The plant was run using its normal operating practices and baseline analytical data were collected and chlorine consumption rates were logged.
~ ~X~i9~2~
¦ 2. Sulfamic acid was added to the cooling tower ¦ water and data continued to be collected.
¦ The Drawin~s ¦ Fig. 1 shows decomposition of HEDP as a function of ¦time, with and without a stabilizer.
¦ Fig. 2 compares two phosphonates and two stabilizers.
¦ Fig. 3 shows a ten-day test in the pilot cooling tower.
¦ Fig. 4 shows the field results testing sulfamic acid.
l Results and Discussion ¦ Bottle Tests ¦ A series of bottle tests were done using the procedure described above. In the first series of tests, the mole ratio of sulfamic acid to chlorine was varied and the decomposition was measured as a function of time. Fig. 1 shows the results of this series. When the mole ratio of sulfamic acid (SA) was as low as .5, significant stabilization was obtained. At a mole ratio of 1 mole of sulfamic acid/chlorine, the decomposition of HEDP was completely eli~inated.
A second series of bottle tests illustrates the effect of two stabilizers, sulfamic acid (SAA) and cyanuric acid (CYA), on the decomposition of two phosphonates (1-hydroxyethylid~ e l,l-diphosphonic acid and phosphono glycolic acid). As can be seen from Fiy. 2, both of these stabilizers gave inhibition of decomposition of both phosphonates. However, sulfamic acid was substantially superior to cyanuric acid.
1 1;~69~29 Pilot Coolinq Tower Results l Some relevant data from the pilot cooling tower test is ¦shown in Fig. 3. The first lû days of the test were used to establish a baseline condition for decomposition in this experiment. After an initial buildup period, substantial levels of orthophosphate were generated, indicating that the HEDP
component of the treatment formulation was being decomposed. On the tenth day of the test, addition of 20 ppm of sulfamic acid (SAA) was begun. The orthophosphate level immediately fell to and was maintained at a much lower level than had been observed in the baseline period.
Field Evaluation Results The results of the field evaluation are summarized in Figs. 4 and 5. Fig. 4 shows the effect of 20 ppm of sulfamic acid on chlorine consumption. Throughout the evaluation, chlorine addition rates were such that a free residual of .2 to .4 was maintained. The addition of sulfamic acid significantly reduced the amount of chlorine required to give this residual of free chlorine. Sulfamic acid feed was commenced on the eighth day of the trial. After sufficient time had elapsed for the tower to turn over the water content, the orthophosphate content of the tower water decreased from the range of 2.5 to 3.û ppm to an average level of 1.2 to 1.8 ppm. This field evaluation clearly shows the efficacy of sulfamic acid in reducing phosphonate degradation under field conditions.
As indicated, the phosphonates are well known materials and are described in the following patents: U.S. 3,214,454, U.S.
4,026,815, U.S. 3,336,221, and U.S. 3,278,446. They all may be used as the free acid or their water-soluble salt form.
The Stabilizers The stabilizer can be any compound which reacts reversibly with chlorine, sodium or calcium hypochlorite or hypochlorous acid. These are all considered as chlorine for the purposes of this disclosure. Compounds which have been identified as being particularly effacacious for this application are:
~X~j9~X5~
(a) water-soluble primary and secondary amines or amides;
(b) ammonia;
(c) sulfamic acid and its water-soluble salts;
(d) water-soluble amides.
The sulfamic acid may be used as such or it may be used as its water-soluble salts, e.g. alkali metal ammonia or amine salts.
The water-soluble primary or secondary amines may be selected from a large number of compounds. Typical are methylamine, dimethylamine, ethylamine, diethylamine, propylamine, dipropylamine, methylethylamine, mono and diethanolamines, morpholine, pyrridine, and any other amine that is capable of reacting as a chlorine stabilizer.
The Water-Soluble Amides The water-soluble amides may be selected from a wide group of compounds. The preferred amides are urea, hydantoin, and cyanuric acid. Other water-soluble amides such as acetamide may be used.
Evaluation of the Invention Experimental Procedures The experimental procedures used fall into three categories.
Benchtop Bottle Tests Test solutions containin9 a synthetic cooling tower water were prepared in 200 ml amber bottles. These solutions were prepared from deionized water and reagent grade salts.
~ 1~6~29 ¦Appropriate commercial grade phosphonates, candidate chlorine stabilizers and chlorine were then added to the solution. The final composition of the test solutions were:
Calcium 500 ppm (CaC03) Magnesium 200 ppm (CaC03) Bicarbonate 300 ppm (CaC03) pH 8.5 Phosphonate 5.0 ppm (P04) Chlorine 12 ppm (C12) Stabilizer varied The solution described above was prepared, stored at room temperature for 48 hours and analyzed for total phosphate and (organic + ortho phosphate). The degree of decomposition was then determined from the amount of orthophosphate generated.
Pilot Cooling Tower Test The use of sulfamic acid for phosphonate stabilization was then tested in a pilot cooling tower (PCT) apparatus. This device is described in the article:
"Small-Scale Short-Term Methods of Evaluating Cooling Water Treatments. . . Are They Worthwhile?," D. T. Reed and R.
Nass, Nalco Chemical Company, International Water Conference, Pittsburgh, PA, Nov. 4-6, 1975. The PCT test was used to determine:
(1) decomposition of phosphonate by chlorine in the absence of any stabilizer;
(2) the effect of sulfamic acid in reducing this decomposition.
The composition of the water in the pilot cooling tower was four concentrations of synthetic lake water. No pH control 69;~
was used and the water was allowed to reach the equilibrium pH
value of 9.û - 9.2. Chlorine was introduced into the system by a constant feed of 7.25% sodium hypochlorite. A scale control program containing 6% of HEDP for scale control was fed to the tower at a rate proportional to the blowdown, resulting in a constant theoretical level of HEDP in t~e tower. The concentration ratio of the tower was held constant by a conductivity controller. A complete analysis of the composition of the tower water was done on a daily basis. rhe experiment was conducted in two phases:
1. With all other factors held constant, the rate of addition of sodium hypochlorite was steadily increased and the effect on the HEDP and orthophosphate residuals observed.
2. Once a steady state of HEDP decomposition was obtained in the tower, feed of sulfamic acid was commenced and the effect on HEDP and orthophosphate levels observed. The extent of decomposition was deduced from these data.
Field Evaluation A field evaluation of this invention was conducted at a midwest polyethylene plant. This plant has a large cooling tower system which contains over a million gallons of water. The holding time of this system is exceptionally long. This plant has been using a product containing HEDP for some time and has also been practicing continuous chlorination. It has had a history of operating problems which have been related to HEDP
breakdown. The field evaluation was conducted in two phases:
1. The plant was run using its normal operating practices and baseline analytical data were collected and chlorine consumption rates were logged.
~ ~X~i9~2~
¦ 2. Sulfamic acid was added to the cooling tower ¦ water and data continued to be collected.
¦ The Drawin~s ¦ Fig. 1 shows decomposition of HEDP as a function of ¦time, with and without a stabilizer.
¦ Fig. 2 compares two phosphonates and two stabilizers.
¦ Fig. 3 shows a ten-day test in the pilot cooling tower.
¦ Fig. 4 shows the field results testing sulfamic acid.
l Results and Discussion ¦ Bottle Tests ¦ A series of bottle tests were done using the procedure described above. In the first series of tests, the mole ratio of sulfamic acid to chlorine was varied and the decomposition was measured as a function of time. Fig. 1 shows the results of this series. When the mole ratio of sulfamic acid (SA) was as low as .5, significant stabilization was obtained. At a mole ratio of 1 mole of sulfamic acid/chlorine, the decomposition of HEDP was completely eli~inated.
A second series of bottle tests illustrates the effect of two stabilizers, sulfamic acid (SAA) and cyanuric acid (CYA), on the decomposition of two phosphonates (1-hydroxyethylid~ e l,l-diphosphonic acid and phosphono glycolic acid). As can be seen from Fiy. 2, both of these stabilizers gave inhibition of decomposition of both phosphonates. However, sulfamic acid was substantially superior to cyanuric acid.
1 1;~69~29 Pilot Coolinq Tower Results l Some relevant data from the pilot cooling tower test is ¦shown in Fig. 3. The first lû days of the test were used to establish a baseline condition for decomposition in this experiment. After an initial buildup period, substantial levels of orthophosphate were generated, indicating that the HEDP
component of the treatment formulation was being decomposed. On the tenth day of the test, addition of 20 ppm of sulfamic acid (SAA) was begun. The orthophosphate level immediately fell to and was maintained at a much lower level than had been observed in the baseline period.
Field Evaluation Results The results of the field evaluation are summarized in Figs. 4 and 5. Fig. 4 shows the effect of 20 ppm of sulfamic acid on chlorine consumption. Throughout the evaluation, chlorine addition rates were such that a free residual of .2 to .4 was maintained. The addition of sulfamic acid significantly reduced the amount of chlorine required to give this residual of free chlorine. Sulfamic acid feed was commenced on the eighth day of the trial. After sufficient time had elapsed for the tower to turn over the water content, the orthophosphate content of the tower water decreased from the range of 2.5 to 3.û ppm to an average level of 1.2 to 1.8 ppm. This field evaluation clearly shows the efficacy of sulfamic acid in reducing phosphonate degradation under field conditions.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of preventing the decomposition of phosphonates from the group consisting of:
1,1-hydroxyethylidene diphosphonic acid; tris amino-methane phosphonic acid; 1-phosphono glycolic acid; ethylene diamine tetra(methylenephosphonic acid):
hexamethylene diamine tetra(methylenephosphonic acid); and, diethylene triamine penta(methylenephosphonic acid); which are present in an effective amount to prevent scale in industrial cooling waters which contain an effective amount of chlorine for microbiological control which comprises treating said waters with at least 1/4 ppm of sulfamic acid for each ppm of C12 present in these waters.
1,1-hydroxyethylidene diphosphonic acid; tris amino-methane phosphonic acid; 1-phosphono glycolic acid; ethylene diamine tetra(methylenephosphonic acid):
hexamethylene diamine tetra(methylenephosphonic acid); and, diethylene triamine penta(methylenephosphonic acid); which are present in an effective amount to prevent scale in industrial cooling waters which contain an effective amount of chlorine for microbiological control which comprises treating said waters with at least 1/4 ppm of sulfamic acid for each ppm of C12 present in these waters.
2. The method of claim 1 where the dosage of the sulfamic acid is at least 1/2 ppm for each ppm of C12.
3. A method of preventing the decomposition of phosphonates from the group consisting of:
1,1-hydroxyethylidene diphosphonic acid; and, 1-phosphono glycolic acid; which are present in an effective amount to prevent scale in industrial cooling waters which contain an effective amount of chlorine for microbiological control which comprises treating said waters with at least 1/4 ppm of sulfamic acid for each ppm of C12 present in these waters.
1,1-hydroxyethylidene diphosphonic acid; and, 1-phosphono glycolic acid; which are present in an effective amount to prevent scale in industrial cooling waters which contain an effective amount of chlorine for microbiological control which comprises treating said waters with at least 1/4 ppm of sulfamic acid for each ppm of C12 present in these waters.
4. A method of preventing the decomposition of 1,1-hydroxyethylidene diphosphonic acid which is present in an effective amount to prevent scale in industrial cooling waters which contain an effective amount of chlorine for micro-biological control which comprises treating said waters with at least 1/4 ppm of sulfamic acid for each ppm of C12 present in these waters.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/776,551 US4642194A (en) | 1985-09-16 | 1985-09-16 | Method for prevention of phosphonate decomposition by chlorine |
| US776,551 | 1985-09-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1269229A true CA1269229A (en) | 1990-05-22 |
Family
ID=25107710
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000517001A Expired - Fee Related CA1269229A (en) | 1985-09-16 | 1986-08-28 | Method for prevention of phosphonate decomposition by chlorine |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US4642194A (en) |
| JP (1) | JPS6268598A (en) |
| CA (1) | CA1269229A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111573900A (en) * | 2020-05-29 | 2020-08-25 | 中国水利水电科学研究院 | Dynamic regulation and control system and method for concentration multiple of circulating cooling water tower |
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|---|---|---|---|---|
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| EP1278811B1 (en) * | 2000-04-17 | 2005-08-10 | The Lubrizol Corporation | Heat transfer fluid for secondary refrigeration systems comprising a formate salt |
| US6375991B1 (en) | 2000-09-08 | 2002-04-23 | Albemarle Corporation | Production of concentrated biocidal solutions |
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| US6908636B2 (en) * | 2001-06-28 | 2005-06-21 | Albermarle Corporation | Microbiological control in poultry processing |
| US6986910B2 (en) * | 2001-06-28 | 2006-01-17 | Albemarle Corporation | Microbiological control in poultry processing |
| CA2462898C (en) * | 2001-10-09 | 2012-03-27 | Albemarle Corporation | Control of biofilms in industrial water systems |
| BR0304877B1 (en) * | 2002-05-22 | 2013-12-03 | COMPOSITION TO PREVENT SLUDGE FORMATION AND PROCESS TO PREVENT SLUDGE FORMATION | |
| US20040265445A1 (en) * | 2003-06-24 | 2004-12-30 | Liimatta Eric W. | Microbiocidal control in the processing of poultry |
| US20040265446A1 (en) * | 2003-06-24 | 2004-12-30 | Mcnaughton James L. | Microbiocidal control in the processing of poultry |
| US7901276B2 (en) * | 2003-06-24 | 2011-03-08 | Albemarle Corporation | Microbiocidal control in the processing of meat-producing four-legged animals |
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| EP1827107B1 (en) * | 2004-12-23 | 2014-02-12 | Albemarle Corporation | Microbiocidal control in the processing of meat-producing four-legged animals |
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| JP5824841B2 (en) * | 2011-03-30 | 2015-12-02 | 栗田工業株式会社 | Method for inhibiting corrosion of copper-based parts |
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|---|---|---|---|---|
| US2106513A (en) * | 1934-05-10 | 1938-01-25 | William M Allison | Process for effecting bactericidal action by the aid of chlorine |
| NL55478C (en) * | 1939-02-21 | |||
| NL242785A (en) * | 1958-09-06 | 1900-01-01 | ||
| US3170883A (en) * | 1962-04-02 | 1965-02-23 | Cortez Chemicals Company | Stabilization of chlorine in aqueous solutions |
| US3278446A (en) * | 1962-10-09 | 1966-10-11 | Monsanto Co | Washing compositions |
| US3336221A (en) * | 1964-11-05 | 1967-08-15 | Calgon Corp | Method of inhibiting precipitation and scale formation |
| US3751372A (en) * | 1971-06-18 | 1973-08-07 | Hercules Inc | Scale and corrosion control in circulating water using polyphosphates and organophonic acids |
| US4108790A (en) * | 1971-11-02 | 1978-08-22 | Exxon Research & Engineering Co. | Corrosion inhibitor |
| DE2333353C2 (en) * | 1973-06-30 | 1983-05-19 | Bayer Ag, 5090 Leverkusen | Process for preventing corrosion in water-bearing systems and anti-corrosion agents for carrying out the process |
| US4011171A (en) * | 1976-01-29 | 1977-03-08 | Nalco Chemical Company | Boiler treatment using amines and organophosphonate materials |
| US4163733A (en) * | 1977-10-25 | 1979-08-07 | Buckman Laboratories, Inc. | Synergistic compositions for corrosion and scale control |
-
1985
- 1985-09-16 US US06/776,551 patent/US4642194A/en not_active Expired - Lifetime
-
1986
- 1986-06-27 JP JP61149873A patent/JPS6268598A/en active Granted
- 1986-08-28 CA CA000517001A patent/CA1269229A/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111573900A (en) * | 2020-05-29 | 2020-08-25 | 中国水利水电科学研究院 | Dynamic regulation and control system and method for concentration multiple of circulating cooling water tower |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6268598A (en) | 1987-03-28 |
| US4642194A (en) | 1987-02-10 |
| JPS6365400B2 (en) | 1988-12-15 |
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