CA2215395A1 - Scale control in aqueous industrial systems - Google Patents
Scale control in aqueous industrial systems Download PDFInfo
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- CA2215395A1 CA2215395A1 CA002215395A CA2215395A CA2215395A1 CA 2215395 A1 CA2215395 A1 CA 2215395A1 CA 002215395 A CA002215395 A CA 002215395A CA 2215395 A CA2215395 A CA 2215395A CA 2215395 A1 CA2215395 A1 CA 2215395A1
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- 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
- C02F5/086—Condensed phosphates
-
- 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
-
- 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
- C02F5/145—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 combined with inorganic substances
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- Chemical & Material Sciences (AREA)
- Water Supply & Treatment (AREA)
- Environmental & Geological Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Hydrology & Water Resources (AREA)
- Inorganic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Paper (AREA)
- Paints Or Removers (AREA)
- Control Of Non-Electrical Variables (AREA)
- Steroid Compounds (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
A composition containing an anionic organic polymer, a polyphosphate, and an organophosphonic acid, where these three components of the composition are present in a combined amount synergistically effective for controlling the formation of inorganic scales in an aqueous system. Also provided is a method for controlling the formation of inorganic scales on surfaces in an aqueous system. The aqueous system is contacted with a composition comprising an anionic organic polymer, a polyphosphate, and an organophosphonic acid. These three components are present in a combined amount synergistically effective for controlling the formation of inorganic scales in the aqueous system.
Description
-CA 0221~39~ 1997-09-1~
WO96129291 PCT~S96/02698 Description SCALE CONTROL IN AQUEOUS INDUSTRIAL SYSTEMS
Technical Field The present invention relates to a composition and method for the chemical treatment of aqueous industrial systems to prevent or reduce the formation of inorganic scales on surfaces within such systems.
Bach~ ~,d Art Contamination of surfaces can be a serious economic problem in many commercial and industrial aqueous processes. This contamination is generally caused by the buildup of organic or inorganic materials on a surface in an aqueous system.
Inorganic cont~m;n~nts in the form of scales are particularly troublesome. Scale formation results from the deposition of mineral compounds present in the water used in an aqueous system. Because they form a hard, rock-like deposit on surfaces in contact with the water, such as the walls of pipes, reservoirs, tanks, and other containment elements in aqueous industrial systems, the formation of scales may cause serious process problems in an aqueous industrial system. Scale formation is especially problematic in geographical areas which have hard water.
Examples of inorganic cont~min~nts which may appear as scales in an aqueous system include barium sulfate, calcium carbonate, calcium sulfate, calcium phosphate, calcium oxalate and other inorganic metal ~ salts which are well known in the art. Often the scale that appears is a mixture of several contaminating materials.
If the formation of scales is not controlled, the buildup of material can interfere with process operations, lower the efficiency of processes, waste CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96/02698 energy, reduce product quality and result in serious economic disadvantages. For example, aqueous industrial systems such as pulp mills, paper-making machines, oil wells, and the like may encounter problems ~rom inorganic scale buildup. The scale deposits may clog or plug or otherwise reduce the ~low o~ aqueous solutions and/or suspensions in water supply lines, condenser tubes, irrigation lines, and other surfaces associated with aqueous systems.
It is well-known that treating an aqueous system with certain chemical additives can reduce or prevent the ~ormation o~ inorganic scales on sur~aces in an aqueous industrial system. Numerous additives can be used in various situations, depending on the type o~
scale causing the problem, and also depending on conditions in the industrial system where scale ~ormation occurs. For example, certain organic polymers and copolymers can be added to an aqueous system ~or this purpose, including polymers and copolymers made ~rom such monomers as acrylic acid, acrylamide, vinyl sul~onic acid, maleic acid, or maleic anhydride; polymers and copolymers made ~rom maleic acid; and terpolymers and copolymers using these and other similar components.
Another group o~ additives which has been used to reduce or prevent the ~ormation o~ inorganic scales on sur~aces in aqueous systems is polyphosphates. This group may include, but is not limited to, tetrapotassium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, and the like.
Finally, organic compounds that include phosphorus-containing moieties have been used in the battle against inorganic scale buildup. These phosphorous-containing compounds include, but are not limited to, products commonly re~erred to as CA 0221~39~ 1997-os-1~
wog6/292s1 PCT~S96/02698 phosphonic acids, phosphonocarboxylic acids, organic phosphate esters, and the like.
The u~e of any of the above conventional compounds or additives is well-known to those skilled in the art of scale control in industrial systems.
In many cases, it is possible to achieve enhanced activity against the scaling problem by using various combinations of the compounds and additives listed above, or by using similar compounds and additives and combinations thereof.
For example, it is known that mixtures of polyphosphates with organic polymers similar to and including poly(acrylic acids) are effective in reducing formation of barium sulfate scales. Products containing this combination have been used commercially for many years, and have provided a major benefit by reducing downtime in industrial processes, and improving quality of the product made in these systems.
Although the above additives and combinations have provided various advantages and benefits, it is always advantageous and bene~icial to increase the efficacy in reducing or preventing the buildup of scales on surfaces in aqueous systems.
Disclosure of the Invention Accordingly, the present invention is directed to a composition and method for improving the prevention, reduction, or inhibition of scale buildup on surfaces contacted by an aqueous medium in industrial systems.
A principal advantage of the present invention is the provision of a composition and method for the prevention, reduction, and/or inhibition of barium sulfate scale and/or other types of scale on the surfaces contacted by an aqueous medium in industrial systems where large amounts of water are used.
-CA 022l~39~ l997-09-l~
WO96/29291 PCT~S96/02698 Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the composition and method particularly pointed out in the written description and claims herein as well as in the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, the present invention is directed to a composition for the prevention, reduction, and/or inhibition of scale buildup in systems utilizing an aqueous medium.
Accordingly, in one aspect of the invention, there is provided a composition having an anionic organic polymer, a polyphosphate compound, and an organophosphonic acid compound, in which the three components are present in an amount effective for controlling the formation of inorganic scales in an aqueous system. Such scales include scales containing barium sulfate, calcium sulfate, calcium carbonate, calcium phosphate, and calcium oxalate.
In another aspect of the invention, there is provided a composition for controlling the formation of scales containing barium sulfate on the surfaces o~
industrial systems which contact an aqueous medium containing barium sulfate wherein the composition is a mixture having an anionic organic polymer, a polyphosphate compound, and an organophosphonic acid compound. Mixtures having these three components have been found to be very effective in controlling the precipitation or formation of barium sulfate scales.
In a further aspect of the present invention, there is provided a method for controlling the CA 022l~39~ l997-09-l~
WO96/29291 PCT~S96/02698 ~ormation of inorganic scales on sur~aces in contact with an aqueous medium in an aqueous system.
"Contact" as used herein includes periodic or occasional contact as well as continual contact with aqueous systems. The aqueous system is contacted with a composition having an anionic organic polymer, a polyphosphate compound, and an organophosphonic acid compound. These three components are present in a combined amount synergistically e~fective ~or controlling the ~ormation o~ inorganic scales in the aqueous system.
The inventors have found that the addition o~ an organophosphonic acid to the polyphosphate/organic polymer combinations described above a~fords a major benefit to increased e~ficacy in reducing or preventing the buildup o~ scales on sur~aces in aqueous systems.
When the organophosphonic acid compound is used in combination with the polyphosphate compound and the anionic organic polymers in accordance with the present invention, there is a synergistic e~fect in the prevention, elimination, reduction, and/or inhibition o~ inorganic scale buildup on the sur~aces in contact with aqueous media (including water) which have inorganic scale-building salts therein, in systems and processes which utilize such aqueous media and which are de~ined herein as aqueous systems or aqueous industrial systems. As shown in the ~ollowing description and examples, the synergistic e~ect of the combination o~ at least one organophosphonic acid compound with at least one anionic organic polymer and at least one polyphosphate compound resulted in a substantial reduction in barium sul~ate precipitation from an aqueous medium containing barium sul~ate.
Accordingly, the composition o~ the present invention is substantially more e~ective that the mixtures and CA 0221~39~ 1997-os-1~
PCT~S96/02698 materials currently known or available for controlling scale buildup. As used herein, controlling the formation of scales, such as barium sulfate scales, is defined as eliminating, preventing, reducing and/or inhibiting the formation of such scales.
The above and other advantages and features of this invention will become apparent upon review of the following detailed description. The accompanying graph is included to provide a further understanding of the invention and is incorporated in and constitutes part of this specification, illustrates several embodiments of the invention and, together with the description, serves to explain the principles of the invention.
Brief DescriPtion o~ the Drawinqs Figure l is a graphical representation of a cost comparison of barium sulfate scale inhibitors. The cost factor versus percent scale inhibition in aqueous medium having a pH of 5 is shown to illustrate the advantages o~ the present invention. Over a large range o~ treatment rates, a combination o~ polyacrylic acid and polyphosphate gives the result designated by AP. Addition of organic phosphonic acids to this mixture gives the noticeably improved results shown as lines A (for Formula A) and B (for Formula B).
Best Mode ~or Carryin~ Out the Invention In accordance with the present invention, the composition must have at least one of each o~ an anionic organic polymer, a polyphosphate compound, and an organophosphonic acid compound. These three components of the composition are present in a combined amount ef~ective ~or controlling the formation of inorganic scales in an aqueous system.
According to the invention, the combined amount of an CA 0221~39~ 1997-og-l~
WO96/29291 PCT~S96/02698 anionic organic polymer, a polyphosphate compound, and an organophosphonic acid compound achieves superior control of the ~ormation of inorganic scales over the same amount of any of the three components alone or over the same amount of any two o~ the components combined. Preferably, the compositions of the present invention provide synergistic results in controlling the formation of scales.
The anionic organic polymers (which includes oligomers, homopolymers, copolymers, terpolymers, etc.) used in the composition and method of the present invention include any of the conventional anionic organic polymers used in scale reduction applications. As used herein, anionic organic polymers include, but are not limited to, polymers resulting from the polymerization of one or more of the following monomers: acrylic acid, acrylamide, vinyl sulfonic acid, maleic acid, maleic anhydride, and the like. Examples of such anionic organic polymers include, but are not limited to, polyacrylates, polymaleic acid, polymaleic anhydrides, hydrolyzed polyacrylonitrile, polymethacrylic acid, sulfonated AMPS, vinyl sulfonic acid, and the salts thereof. Other anionic organic polymers that can be used are polymers (preferably copolymers) resulting ~rom the polymerization o~ one or more o~ the above-listed monomers with one or more nonionic monomers such as acrylamide, styrene, and the like. The molecular weight of the anionic organic polymers (including copolymers) is not critical and anionic organic polymers used in the present invention may have any molecular weight as well known in the art.
Part of the mechanism of preventing scales from forming is the "dispersing~ of the precipitating materials. An anionic polymer will attach to the initial crystal of precipitated material and coat it CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96/02698 with an anionic charge, thus reducing the likelihood that these crystals will agglomerate and build up on surfaces in contact with aqueous solutions used in aqueous systems, e . g., walls of pipes, reservoirs, and the like. In addition, surfaces generally tend to be anionic so repulsion occurs there as well.
The anionic polymers used in the present invention are generally water-soluble or water-dispersible. Preferably, they are water-soluble.
Preferably, the anionic organic polymer in the composition of the present invention is a polyacrylate compound or salts thereof. More preferably, the anionic organic polymer is a polymer of acrylic acid ( e . g., a homopolymer of acrylic acid). Most preferably, the anionic organic polymer is a copolymer of acrylic acid and acrylamide having a molecular weight of about 3000 to about 5000. For example, BSI
9l, a polyacrylic acid, and BSI 75, a polyacrylic acid copolymer, can be used in the present invention. Both are available from Buckman Laboratories International, Inc. in Memphis, Tennessee.
The polyphosphate compounds used in the composition and method of the present invention include any of the conventional polyphosphate compounds, preferably those used in scale reduction applications. Examples of polyphosphate compounds which may be used in the present invention include, but are not limited to, pyrophosphates and polyphosphates coordinated with sodium or potassium, such as sodium tripolyphosphate, potassium pyrophosphate, and sodium hexametaphosphate. Sodium hexametaphosphate is preferably used at a pH of about 5-6. The preferred polyphosphate compound used in the composition and method of the present invention is a tripolyphosphate. Tripolysphosphates are preferably used at a pH of about lO-ll. More preferably, the CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96102698 polyphosphate compound used in the present invention is sodium tripolyphosphate.
The organophosphonic acid compounds used in the composition and method of the present invention include any of the conventional phosphorus-containing organic compounds used in water treatment. Any organophosphonic acid compound may be used in accordance with the present invention as long as it produces a synergistic effect in the prevention, elimination, reduction, and/or inhibition of inorganic scale buildup, including barium sulfate scale buildup, on surfaces in contact with aqueous media, when it is combined with an anionic organic polymer and a polyphosphate compound. Pre~erably, these organic phosphonic acids have the general structure:
o ~ Il R - P~
~ OH
OH
Typically, the molecule contains at least several phosphonic acid groups. It may be water-soluble, depending on the characteristics of the R substituent~.
For example, the R substituent may be an organic amine. Such organophosphonic acids are described in a paper given April 5, l99l at the Association of Water Technologies in San Antonio, TX by Robert Cavano entitled "Phosphonates: Lore and Legend", the disclosure of which is hereby incorporated by reference.
Examples of organophosphonic acids which may be used in the present invention include, but are not limited to, aminotris (methylenephosphonic acid), diethylenetriaminepenta (methylene phosphonic acid), CA 022l~39~ l997-09-l~
WO96/29291 PCT~S96/02698 hydroxyethylidenebis (phosphonic acid), tetrakis-methylene phosphonic acid o~ diaminocyclohexane, tetrakis-methylene phosphonic acid o~ diamino methyl pentane, the salts o~ such acids, and the like.
Pre~erably, the organophosphonic acid is selected ~rom aminotris(methylene phosphonic acid), hydroxyethylidenebis (phosphonic acid), tetrakis-methylene phosphonic acid o~ diaminocyclohexane, and tetrakis-methylene phosphonic acid o~ diamino methyl pentane.
The amount o~ organophosphonic acid compound, polyphosphate compound and anionic organic polymer in the composition and method o~ the present invention is an amount e~ective to control the ~ormation o~
inorganic scale buildup on sur~aces in contact with aqueous media in systems which utilize aqueous media, i.e., in aqueous systems or aqueous industrial systems, and to provide the synergistic e~ect discussed herein. Although there is no intention to be limited to speci~ic amounts, in certain aspects of the present invention, the composition has about 0.1%
to about 60.0~ organophosphonic acid compoundi about 1.0~ to about 50.0~ polyphosphate compound and about 1.0~ to about 60.0~ anionic organic polymer. In certain pre~erred embodiments, the composition has about 0.1~ to about 10.0~ organophosphonic acid compound; about 1.0% to about 20.0~ polyphosphate compound and about 1.0~ to about 30.0~ anionic organic polymer. In the most pre~erred embodiments, the composition has about 0.1~ to about 4.0~
organophosphonic acid compound; about 1.0~ to about 10.0~ polyphosphate compound and about 1.0~ to about 20.0~ anionic organic polymer. All amounts are given as weight percent based on the total weight o~ the composition.
CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96/02698 The compositions of the present invention are generally water soluble or water-dispersible and may be added directly to aqueous process streams and/or reservoir and the like as solids, e.g., as free-flowing powders, or they may be dissolved in water at any desired concentrations, e.g., about 25~ to about 75~ by weight, and added to aqueous process streams, reservoir, and the like in solutions. When the compositions of the present invention are added to an aqueous process stream or a reservoir containing an aqueous medium or to any other aqueous medium in an aqueous system, the composition is in contact with surfaces ( e . g., walls of pipes, reservoirs, and the like) in the aqueous system and controls inorganic scale buildup on the surface, i . e ., it eliminates, prevents, reduces and/or inhibits the formation of such scales on the surface. The present invention operates both by the presence of the compositions of the invention in aqueous mediums and by the contact of the compositions with surfaces in those mediums as described above.
Other additives may be used in the compositions and method of the present invention as long as they do not have an adverse effect on the control of the formation of scales. For example, conventional water treatment compounds may be used in the composition and method of the present invention. The composition of the present invention may be used at any pH normally encountered in aqueous systems, for example, in oil wells, pulp mills, paper-making processes and the like.
The present invention further relates to a method for controlling the formation of inorganic scales on surfaces in an aqueous system. The aqueous system is contacted with a composition comprising an anionic organic polymer, a polyphosphate, and an CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96/02698 organophosphonic acid. These three components are present in a combined amount synergistically e~ective ~or controlling the ~ormation o~ inorganic scales in the aqueous system.
The present invention is particularly useful in the reduction or prevention o~ scales containing barium sul~ate. Barium sul~ate scales, as well as scales containing other inorganic compounds, may be ~ound in aqueous industrial systems such as paper-making plants, pulp mills, and oil wells.
The composition and method o~ the present invention is illustrated by way o~ the ~ollowing examples. It is to be understood that the invention is not to be limited to the speci~ic conditions or details set ~orth in these examples except inso~ar as such limitations are speci~ied in the appended claims.
EXAMPLES
Example 1 The data given below in Table l and Table 2 illustrate the synergism provided by the composition of the present invention. At both pH levels 5 and 7, the additive e~ect ~rom the separate components was much less than the observed result o~ the combined materials.
First, the ~ollowing solutions were prepared:
-- a 300 ppm solution o~ barium chloride, prepared by dissolving 0.5336 g of BaCl2*2H2O per liter of deionized water;
-- a 200 ppm sodium sul~ate solution, prepared by dissolving 0.2957 g o~ Na2SO4 per liter o~ deionized r water; and -- a lll.ll ppm potassium chloride solution, prepared by dissolving O.llll g o~ KCl per liter o~
deionized water.
CA 022l~39~ l997-09-l~
WO96/29291 PCT~$96/02698 0.05~ active ~olutions of the composition of the present invention were prepared by making a 0.5 active solution and diluting by a ~actor of 10.
Formula A contained the ppm dosage of each component below as shown in Table 1. Test results using Formula A are also shown in Table 1.
Formula A: 4.05 parts sodium tripolyphosphate 4.57 parts polyacrylic acid (X) 1.38 parts aminotris(methylene phosphonic acid) (A) Polyacrylic acid X was a copolymer of acrylic acid and acrylamide.
25 ml of the barium chloride solution was mixed with the combination of Formula A in a 2-oz. bo~tle.
The pH of Formula A had been adjusted to be about 10-11 by addition of sodium hydroxide. This is the preferred pH when working with sodium tripolyphosphate. Next, 25 ml of the sodium sulfate solution, its pH adjusted with sodium hydroxide, was introduced. The bottle was capped and allowed to sit overnight at 25~C. Controls were made which contained only 25 ml of the barium solution and 25 ml of the sulfate solution. Blanks were made which contained only 25 ml of the barium solution and 25 ml deionized water.
A 2 ml sample was removed from the bottle and placed with 18 ml of the potassium chloride solution in a centrifuge tube and shaken. The sample was analyzed ~or barium using an atomic absorption spectrophotometer. Percent inhibition was calculated, based on the ppm of barium in the control subtracted from the ppm of barium in the test sample, divided by the ppm of barium in the control subtracted from the ppm of barium in the blank. This is shown in Tables 1 CA 022l~39~ l997-09-l~
WO96/29291 PCT~S96/02698 and 2 as percent reduction in precipitate.
TAsLE 1 ~ Reduction % Reduction Additive Used Dosage in Precipitate in Precipitate ppm pH 5 pH 7 polyphosphate 2.35 11.4 14.7 polyacrylate X 2.65 0.6 o phosphonic acid A 0.8 0 0 expected result all above 12.0 14.7 observed result all above 25.8 21.1 The data in Table 2 are from a variation (Formula B), in which a different commercially available polyacrylate (a homopolymer of acrylic acid) and a different commercially available phosphonic acid were used to prepare the composition of the invention.
Formula B, its components listed below, contained the ppm dosage of each component below as shown in Table 2. Test results using Formula B are also shown in Table 2. Again, the combination produced results much better than expected.
Formula B: 4.05 parts sodium tripolyphosphate 4.57 parts polyacrylic acid (Y) 1.38 parts hydroxyethylidenebis(phosphonic acid)(B) CA 022l~39~ l997-09-l~
W O96/29291 PCTrUS96/02698 ~ Reduction ~ Reduction Additive Used Dosage in Precipitate in Precipitate ppm pH 5 pH 7 polyphosphate 2.35 11.~ 14.7 polyacrylate Y 2.65 0.2 0 phosphonic 0.8 3.9 0 acid B
expectedall above15.5 14.7 result observedall above25.8 23.7 result Figure 1 illustrates in another way the advantage of the present invention. Over a large range of treatment rates, the combination of polyacrylic acid and polyphosphate, an effective commercially available product, gave the result designated by AP. Addition of the organic phosphonic acids to this mixture gave the noticeably improved results shown as lines A (for Formula A) and B (for Formula B). Graph 1 shows the results at pH 5.
Example 2 The present invention was also tested on site in a paper mill. This mill produces in excess of 700 tons per day of linerboard. A recurring problem over CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96102698 the years has been buildup of barium sulfate scale in production equipment, including headboxes, and cleaners. This scale can plug holes in the headbox, reducing the quality of the paper produced.
A combination of polyphosphate and polyacrylic acid had been used to reduce problems and increase time between machine shutdowns for required cleanings.
At a certain level of treatment, this combination may work very well. Typical treatment in this case is about 0.25 parts per million (ppm) of polyphosphate in the total water flow, and O.lO ppm polyacrylic acid.
In an attempt to improve performance, a composition according to the present invention, i.e., phosphonic acid, polyphosphate, and polyacrylic acid, was used in the ongoing treatment, replacing the polyphosphate/polyacrylic acid combination. The - revised treatment was at a cost equal to that of the original treatment. 25~ of the original treatment was replaced by a phosphonic acid. Addition rates were approximately O.l9 ppm polyphosphate, 0.075 ppm polyacrylic acid, and 0.09 ppm phosphonic acid.
As a result of this program, there was a significant reduction in the buildup of barium sulfate scale in this paper machine. After running this program for 6 weeks, all holes in the headbox were clear and unplugged. A small amount of scale that was sighted was extremely light and not problematic. This mill now uses the combination of this invention to control barium sulfate scale.
WO96129291 PCT~S96/02698 Description SCALE CONTROL IN AQUEOUS INDUSTRIAL SYSTEMS
Technical Field The present invention relates to a composition and method for the chemical treatment of aqueous industrial systems to prevent or reduce the formation of inorganic scales on surfaces within such systems.
Bach~ ~,d Art Contamination of surfaces can be a serious economic problem in many commercial and industrial aqueous processes. This contamination is generally caused by the buildup of organic or inorganic materials on a surface in an aqueous system.
Inorganic cont~m;n~nts in the form of scales are particularly troublesome. Scale formation results from the deposition of mineral compounds present in the water used in an aqueous system. Because they form a hard, rock-like deposit on surfaces in contact with the water, such as the walls of pipes, reservoirs, tanks, and other containment elements in aqueous industrial systems, the formation of scales may cause serious process problems in an aqueous industrial system. Scale formation is especially problematic in geographical areas which have hard water.
Examples of inorganic cont~min~nts which may appear as scales in an aqueous system include barium sulfate, calcium carbonate, calcium sulfate, calcium phosphate, calcium oxalate and other inorganic metal ~ salts which are well known in the art. Often the scale that appears is a mixture of several contaminating materials.
If the formation of scales is not controlled, the buildup of material can interfere with process operations, lower the efficiency of processes, waste CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96/02698 energy, reduce product quality and result in serious economic disadvantages. For example, aqueous industrial systems such as pulp mills, paper-making machines, oil wells, and the like may encounter problems ~rom inorganic scale buildup. The scale deposits may clog or plug or otherwise reduce the ~low o~ aqueous solutions and/or suspensions in water supply lines, condenser tubes, irrigation lines, and other surfaces associated with aqueous systems.
It is well-known that treating an aqueous system with certain chemical additives can reduce or prevent the ~ormation o~ inorganic scales on sur~aces in an aqueous industrial system. Numerous additives can be used in various situations, depending on the type o~
scale causing the problem, and also depending on conditions in the industrial system where scale ~ormation occurs. For example, certain organic polymers and copolymers can be added to an aqueous system ~or this purpose, including polymers and copolymers made ~rom such monomers as acrylic acid, acrylamide, vinyl sul~onic acid, maleic acid, or maleic anhydride; polymers and copolymers made ~rom maleic acid; and terpolymers and copolymers using these and other similar components.
Another group o~ additives which has been used to reduce or prevent the ~ormation o~ inorganic scales on sur~aces in aqueous systems is polyphosphates. This group may include, but is not limited to, tetrapotassium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, and the like.
Finally, organic compounds that include phosphorus-containing moieties have been used in the battle against inorganic scale buildup. These phosphorous-containing compounds include, but are not limited to, products commonly re~erred to as CA 0221~39~ 1997-os-1~
wog6/292s1 PCT~S96/02698 phosphonic acids, phosphonocarboxylic acids, organic phosphate esters, and the like.
The u~e of any of the above conventional compounds or additives is well-known to those skilled in the art of scale control in industrial systems.
In many cases, it is possible to achieve enhanced activity against the scaling problem by using various combinations of the compounds and additives listed above, or by using similar compounds and additives and combinations thereof.
For example, it is known that mixtures of polyphosphates with organic polymers similar to and including poly(acrylic acids) are effective in reducing formation of barium sulfate scales. Products containing this combination have been used commercially for many years, and have provided a major benefit by reducing downtime in industrial processes, and improving quality of the product made in these systems.
Although the above additives and combinations have provided various advantages and benefits, it is always advantageous and bene~icial to increase the efficacy in reducing or preventing the buildup of scales on surfaces in aqueous systems.
Disclosure of the Invention Accordingly, the present invention is directed to a composition and method for improving the prevention, reduction, or inhibition of scale buildup on surfaces contacted by an aqueous medium in industrial systems.
A principal advantage of the present invention is the provision of a composition and method for the prevention, reduction, and/or inhibition of barium sulfate scale and/or other types of scale on the surfaces contacted by an aqueous medium in industrial systems where large amounts of water are used.
-CA 022l~39~ l997-09-l~
WO96/29291 PCT~S96/02698 Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the composition and method particularly pointed out in the written description and claims herein as well as in the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, the present invention is directed to a composition for the prevention, reduction, and/or inhibition of scale buildup in systems utilizing an aqueous medium.
Accordingly, in one aspect of the invention, there is provided a composition having an anionic organic polymer, a polyphosphate compound, and an organophosphonic acid compound, in which the three components are present in an amount effective for controlling the formation of inorganic scales in an aqueous system. Such scales include scales containing barium sulfate, calcium sulfate, calcium carbonate, calcium phosphate, and calcium oxalate.
In another aspect of the invention, there is provided a composition for controlling the formation of scales containing barium sulfate on the surfaces o~
industrial systems which contact an aqueous medium containing barium sulfate wherein the composition is a mixture having an anionic organic polymer, a polyphosphate compound, and an organophosphonic acid compound. Mixtures having these three components have been found to be very effective in controlling the precipitation or formation of barium sulfate scales.
In a further aspect of the present invention, there is provided a method for controlling the CA 022l~39~ l997-09-l~
WO96/29291 PCT~S96/02698 ~ormation of inorganic scales on sur~aces in contact with an aqueous medium in an aqueous system.
"Contact" as used herein includes periodic or occasional contact as well as continual contact with aqueous systems. The aqueous system is contacted with a composition having an anionic organic polymer, a polyphosphate compound, and an organophosphonic acid compound. These three components are present in a combined amount synergistically e~fective ~or controlling the ~ormation o~ inorganic scales in the aqueous system.
The inventors have found that the addition o~ an organophosphonic acid to the polyphosphate/organic polymer combinations described above a~fords a major benefit to increased e~ficacy in reducing or preventing the buildup o~ scales on sur~aces in aqueous systems.
When the organophosphonic acid compound is used in combination with the polyphosphate compound and the anionic organic polymers in accordance with the present invention, there is a synergistic e~fect in the prevention, elimination, reduction, and/or inhibition o~ inorganic scale buildup on the sur~aces in contact with aqueous media (including water) which have inorganic scale-building salts therein, in systems and processes which utilize such aqueous media and which are de~ined herein as aqueous systems or aqueous industrial systems. As shown in the ~ollowing description and examples, the synergistic e~ect of the combination o~ at least one organophosphonic acid compound with at least one anionic organic polymer and at least one polyphosphate compound resulted in a substantial reduction in barium sul~ate precipitation from an aqueous medium containing barium sul~ate.
Accordingly, the composition o~ the present invention is substantially more e~ective that the mixtures and CA 0221~39~ 1997-os-1~
PCT~S96/02698 materials currently known or available for controlling scale buildup. As used herein, controlling the formation of scales, such as barium sulfate scales, is defined as eliminating, preventing, reducing and/or inhibiting the formation of such scales.
The above and other advantages and features of this invention will become apparent upon review of the following detailed description. The accompanying graph is included to provide a further understanding of the invention and is incorporated in and constitutes part of this specification, illustrates several embodiments of the invention and, together with the description, serves to explain the principles of the invention.
Brief DescriPtion o~ the Drawinqs Figure l is a graphical representation of a cost comparison of barium sulfate scale inhibitors. The cost factor versus percent scale inhibition in aqueous medium having a pH of 5 is shown to illustrate the advantages o~ the present invention. Over a large range o~ treatment rates, a combination o~ polyacrylic acid and polyphosphate gives the result designated by AP. Addition of organic phosphonic acids to this mixture gives the noticeably improved results shown as lines A (for Formula A) and B (for Formula B).
Best Mode ~or Carryin~ Out the Invention In accordance with the present invention, the composition must have at least one of each o~ an anionic organic polymer, a polyphosphate compound, and an organophosphonic acid compound. These three components of the composition are present in a combined amount ef~ective ~or controlling the formation of inorganic scales in an aqueous system.
According to the invention, the combined amount of an CA 0221~39~ 1997-og-l~
WO96/29291 PCT~S96/02698 anionic organic polymer, a polyphosphate compound, and an organophosphonic acid compound achieves superior control of the ~ormation of inorganic scales over the same amount of any of the three components alone or over the same amount of any two o~ the components combined. Preferably, the compositions of the present invention provide synergistic results in controlling the formation of scales.
The anionic organic polymers (which includes oligomers, homopolymers, copolymers, terpolymers, etc.) used in the composition and method of the present invention include any of the conventional anionic organic polymers used in scale reduction applications. As used herein, anionic organic polymers include, but are not limited to, polymers resulting from the polymerization of one or more of the following monomers: acrylic acid, acrylamide, vinyl sulfonic acid, maleic acid, maleic anhydride, and the like. Examples of such anionic organic polymers include, but are not limited to, polyacrylates, polymaleic acid, polymaleic anhydrides, hydrolyzed polyacrylonitrile, polymethacrylic acid, sulfonated AMPS, vinyl sulfonic acid, and the salts thereof. Other anionic organic polymers that can be used are polymers (preferably copolymers) resulting ~rom the polymerization o~ one or more o~ the above-listed monomers with one or more nonionic monomers such as acrylamide, styrene, and the like. The molecular weight of the anionic organic polymers (including copolymers) is not critical and anionic organic polymers used in the present invention may have any molecular weight as well known in the art.
Part of the mechanism of preventing scales from forming is the "dispersing~ of the precipitating materials. An anionic polymer will attach to the initial crystal of precipitated material and coat it CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96/02698 with an anionic charge, thus reducing the likelihood that these crystals will agglomerate and build up on surfaces in contact with aqueous solutions used in aqueous systems, e . g., walls of pipes, reservoirs, and the like. In addition, surfaces generally tend to be anionic so repulsion occurs there as well.
The anionic polymers used in the present invention are generally water-soluble or water-dispersible. Preferably, they are water-soluble.
Preferably, the anionic organic polymer in the composition of the present invention is a polyacrylate compound or salts thereof. More preferably, the anionic organic polymer is a polymer of acrylic acid ( e . g., a homopolymer of acrylic acid). Most preferably, the anionic organic polymer is a copolymer of acrylic acid and acrylamide having a molecular weight of about 3000 to about 5000. For example, BSI
9l, a polyacrylic acid, and BSI 75, a polyacrylic acid copolymer, can be used in the present invention. Both are available from Buckman Laboratories International, Inc. in Memphis, Tennessee.
The polyphosphate compounds used in the composition and method of the present invention include any of the conventional polyphosphate compounds, preferably those used in scale reduction applications. Examples of polyphosphate compounds which may be used in the present invention include, but are not limited to, pyrophosphates and polyphosphates coordinated with sodium or potassium, such as sodium tripolyphosphate, potassium pyrophosphate, and sodium hexametaphosphate. Sodium hexametaphosphate is preferably used at a pH of about 5-6. The preferred polyphosphate compound used in the composition and method of the present invention is a tripolyphosphate. Tripolysphosphates are preferably used at a pH of about lO-ll. More preferably, the CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96102698 polyphosphate compound used in the present invention is sodium tripolyphosphate.
The organophosphonic acid compounds used in the composition and method of the present invention include any of the conventional phosphorus-containing organic compounds used in water treatment. Any organophosphonic acid compound may be used in accordance with the present invention as long as it produces a synergistic effect in the prevention, elimination, reduction, and/or inhibition of inorganic scale buildup, including barium sulfate scale buildup, on surfaces in contact with aqueous media, when it is combined with an anionic organic polymer and a polyphosphate compound. Pre~erably, these organic phosphonic acids have the general structure:
o ~ Il R - P~
~ OH
OH
Typically, the molecule contains at least several phosphonic acid groups. It may be water-soluble, depending on the characteristics of the R substituent~.
For example, the R substituent may be an organic amine. Such organophosphonic acids are described in a paper given April 5, l99l at the Association of Water Technologies in San Antonio, TX by Robert Cavano entitled "Phosphonates: Lore and Legend", the disclosure of which is hereby incorporated by reference.
Examples of organophosphonic acids which may be used in the present invention include, but are not limited to, aminotris (methylenephosphonic acid), diethylenetriaminepenta (methylene phosphonic acid), CA 022l~39~ l997-09-l~
WO96/29291 PCT~S96/02698 hydroxyethylidenebis (phosphonic acid), tetrakis-methylene phosphonic acid o~ diaminocyclohexane, tetrakis-methylene phosphonic acid o~ diamino methyl pentane, the salts o~ such acids, and the like.
Pre~erably, the organophosphonic acid is selected ~rom aminotris(methylene phosphonic acid), hydroxyethylidenebis (phosphonic acid), tetrakis-methylene phosphonic acid o~ diaminocyclohexane, and tetrakis-methylene phosphonic acid o~ diamino methyl pentane.
The amount o~ organophosphonic acid compound, polyphosphate compound and anionic organic polymer in the composition and method o~ the present invention is an amount e~ective to control the ~ormation o~
inorganic scale buildup on sur~aces in contact with aqueous media in systems which utilize aqueous media, i.e., in aqueous systems or aqueous industrial systems, and to provide the synergistic e~ect discussed herein. Although there is no intention to be limited to speci~ic amounts, in certain aspects of the present invention, the composition has about 0.1%
to about 60.0~ organophosphonic acid compoundi about 1.0~ to about 50.0~ polyphosphate compound and about 1.0~ to about 60.0~ anionic organic polymer. In certain pre~erred embodiments, the composition has about 0.1~ to about 10.0~ organophosphonic acid compound; about 1.0% to about 20.0~ polyphosphate compound and about 1.0~ to about 30.0~ anionic organic polymer. In the most pre~erred embodiments, the composition has about 0.1~ to about 4.0~
organophosphonic acid compound; about 1.0~ to about 10.0~ polyphosphate compound and about 1.0~ to about 20.0~ anionic organic polymer. All amounts are given as weight percent based on the total weight o~ the composition.
CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96/02698 The compositions of the present invention are generally water soluble or water-dispersible and may be added directly to aqueous process streams and/or reservoir and the like as solids, e.g., as free-flowing powders, or they may be dissolved in water at any desired concentrations, e.g., about 25~ to about 75~ by weight, and added to aqueous process streams, reservoir, and the like in solutions. When the compositions of the present invention are added to an aqueous process stream or a reservoir containing an aqueous medium or to any other aqueous medium in an aqueous system, the composition is in contact with surfaces ( e . g., walls of pipes, reservoirs, and the like) in the aqueous system and controls inorganic scale buildup on the surface, i . e ., it eliminates, prevents, reduces and/or inhibits the formation of such scales on the surface. The present invention operates both by the presence of the compositions of the invention in aqueous mediums and by the contact of the compositions with surfaces in those mediums as described above.
Other additives may be used in the compositions and method of the present invention as long as they do not have an adverse effect on the control of the formation of scales. For example, conventional water treatment compounds may be used in the composition and method of the present invention. The composition of the present invention may be used at any pH normally encountered in aqueous systems, for example, in oil wells, pulp mills, paper-making processes and the like.
The present invention further relates to a method for controlling the formation of inorganic scales on surfaces in an aqueous system. The aqueous system is contacted with a composition comprising an anionic organic polymer, a polyphosphate, and an CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96/02698 organophosphonic acid. These three components are present in a combined amount synergistically e~ective ~or controlling the ~ormation o~ inorganic scales in the aqueous system.
The present invention is particularly useful in the reduction or prevention o~ scales containing barium sul~ate. Barium sul~ate scales, as well as scales containing other inorganic compounds, may be ~ound in aqueous industrial systems such as paper-making plants, pulp mills, and oil wells.
The composition and method o~ the present invention is illustrated by way o~ the ~ollowing examples. It is to be understood that the invention is not to be limited to the speci~ic conditions or details set ~orth in these examples except inso~ar as such limitations are speci~ied in the appended claims.
EXAMPLES
Example 1 The data given below in Table l and Table 2 illustrate the synergism provided by the composition of the present invention. At both pH levels 5 and 7, the additive e~ect ~rom the separate components was much less than the observed result o~ the combined materials.
First, the ~ollowing solutions were prepared:
-- a 300 ppm solution o~ barium chloride, prepared by dissolving 0.5336 g of BaCl2*2H2O per liter of deionized water;
-- a 200 ppm sodium sul~ate solution, prepared by dissolving 0.2957 g o~ Na2SO4 per liter o~ deionized r water; and -- a lll.ll ppm potassium chloride solution, prepared by dissolving O.llll g o~ KCl per liter o~
deionized water.
CA 022l~39~ l997-09-l~
WO96/29291 PCT~$96/02698 0.05~ active ~olutions of the composition of the present invention were prepared by making a 0.5 active solution and diluting by a ~actor of 10.
Formula A contained the ppm dosage of each component below as shown in Table 1. Test results using Formula A are also shown in Table 1.
Formula A: 4.05 parts sodium tripolyphosphate 4.57 parts polyacrylic acid (X) 1.38 parts aminotris(methylene phosphonic acid) (A) Polyacrylic acid X was a copolymer of acrylic acid and acrylamide.
25 ml of the barium chloride solution was mixed with the combination of Formula A in a 2-oz. bo~tle.
The pH of Formula A had been adjusted to be about 10-11 by addition of sodium hydroxide. This is the preferred pH when working with sodium tripolyphosphate. Next, 25 ml of the sodium sulfate solution, its pH adjusted with sodium hydroxide, was introduced. The bottle was capped and allowed to sit overnight at 25~C. Controls were made which contained only 25 ml of the barium solution and 25 ml of the sulfate solution. Blanks were made which contained only 25 ml of the barium solution and 25 ml deionized water.
A 2 ml sample was removed from the bottle and placed with 18 ml of the potassium chloride solution in a centrifuge tube and shaken. The sample was analyzed ~or barium using an atomic absorption spectrophotometer. Percent inhibition was calculated, based on the ppm of barium in the control subtracted from the ppm of barium in the test sample, divided by the ppm of barium in the control subtracted from the ppm of barium in the blank. This is shown in Tables 1 CA 022l~39~ l997-09-l~
WO96/29291 PCT~S96/02698 and 2 as percent reduction in precipitate.
TAsLE 1 ~ Reduction % Reduction Additive Used Dosage in Precipitate in Precipitate ppm pH 5 pH 7 polyphosphate 2.35 11.4 14.7 polyacrylate X 2.65 0.6 o phosphonic acid A 0.8 0 0 expected result all above 12.0 14.7 observed result all above 25.8 21.1 The data in Table 2 are from a variation (Formula B), in which a different commercially available polyacrylate (a homopolymer of acrylic acid) and a different commercially available phosphonic acid were used to prepare the composition of the invention.
Formula B, its components listed below, contained the ppm dosage of each component below as shown in Table 2. Test results using Formula B are also shown in Table 2. Again, the combination produced results much better than expected.
Formula B: 4.05 parts sodium tripolyphosphate 4.57 parts polyacrylic acid (Y) 1.38 parts hydroxyethylidenebis(phosphonic acid)(B) CA 022l~39~ l997-09-l~
W O96/29291 PCTrUS96/02698 ~ Reduction ~ Reduction Additive Used Dosage in Precipitate in Precipitate ppm pH 5 pH 7 polyphosphate 2.35 11.~ 14.7 polyacrylate Y 2.65 0.2 0 phosphonic 0.8 3.9 0 acid B
expectedall above15.5 14.7 result observedall above25.8 23.7 result Figure 1 illustrates in another way the advantage of the present invention. Over a large range of treatment rates, the combination of polyacrylic acid and polyphosphate, an effective commercially available product, gave the result designated by AP. Addition of the organic phosphonic acids to this mixture gave the noticeably improved results shown as lines A (for Formula A) and B (for Formula B). Graph 1 shows the results at pH 5.
Example 2 The present invention was also tested on site in a paper mill. This mill produces in excess of 700 tons per day of linerboard. A recurring problem over CA 0221~39~ 1997-09-1~
WO96/29291 PCT~S96102698 the years has been buildup of barium sulfate scale in production equipment, including headboxes, and cleaners. This scale can plug holes in the headbox, reducing the quality of the paper produced.
A combination of polyphosphate and polyacrylic acid had been used to reduce problems and increase time between machine shutdowns for required cleanings.
At a certain level of treatment, this combination may work very well. Typical treatment in this case is about 0.25 parts per million (ppm) of polyphosphate in the total water flow, and O.lO ppm polyacrylic acid.
In an attempt to improve performance, a composition according to the present invention, i.e., phosphonic acid, polyphosphate, and polyacrylic acid, was used in the ongoing treatment, replacing the polyphosphate/polyacrylic acid combination. The - revised treatment was at a cost equal to that of the original treatment. 25~ of the original treatment was replaced by a phosphonic acid. Addition rates were approximately O.l9 ppm polyphosphate, 0.075 ppm polyacrylic acid, and 0.09 ppm phosphonic acid.
As a result of this program, there was a significant reduction in the buildup of barium sulfate scale in this paper machine. After running this program for 6 weeks, all holes in the headbox were clear and unplugged. A small amount of scale that was sighted was extremely light and not problematic. This mill now uses the combination of this invention to control barium sulfate scale.
Claims (12)
1. A composition comprising:
(a) an anionic organic polymer, (b) a polyphosphate, and (c) an organophosphonic acid wherein (a), (b), and (c) are present in a combined amount effective for controlling the formation of inorganic scales in an aqueous system.
(a) an anionic organic polymer, (b) a polyphosphate, and (c) an organophosphonic acid wherein (a), (b), and (c) are present in a combined amount effective for controlling the formation of inorganic scales in an aqueous system.
2. The composition of claim 1, wherein the anionic organic polymer is a polyacrylate.
3. The composition of claim 2, wherein the polyacrylate is an acrylic acid/acrylamide copolymer.
4. The composition of claim 1, wherein the polyphosphate is sodium tripolyphosphate.
5. The composition of claim 1, wherein the inorganic scales are scales containing inorganic metal salts selected from barium sulfate, calcium carbonate, calcium sulfate, calcium phosphate and calcium oxalate.
6. The composition of claim 5, wherein the inorganic scales are scales containing barium sulfate.
7. The composition of claim 1, wherein the amount of the anionic organic polymer ranges from about 1.0% to about 60.0% by weight; the amount of the polyphosphate ranges from about 1.0% to about 50.0% by weight and the amount of the organophosphonic acid ranges from about 0.1% to about 60.0% by weight.
8. The composition of claim 7, wherein the amount of the anionic organic polymer ranges from about 1.0% to about 30.0% by weight; the amount of the polyphosphate ranges from about 1.0% to about 20.0% by weight and the amount of the organophosphonic acid ranges from about 0.1% to about 10.0% by weight.
9. The composition of claim 8, wherein the amount of the anionic organic polymer ranges from about 1.0% to about 20.0% by weight; the amount of the polyphosphate ranges from about 1.0% to about 10.0% by weight and the amount of the organophosphonic acid ranges from about 0.1% to about 4.0% by weight.
10. A method for controlling the formation of inorganic scales on surfaces in an aqueous system, comprising contacting an aqueous system with a composition comprising:
(a) an anionic organic polymer, (b) a polyphosphate, and (c) an organophosphonic acid wherein (a), (b), and (c) are present in a combined amount synergistically effective for controlling the formation of inorganic scales in the aqueous system.
(a) an anionic organic polymer, (b) a polyphosphate, and (c) an organophosphonic acid wherein (a), (b), and (c) are present in a combined amount synergistically effective for controlling the formation of inorganic scales in the aqueous system.
11. The method of claim 10, wherein the inorganic scales are scales containing barium sulfate.
12. The method of claim 10, wherein the aqueous system is a paper making machine, a pulp mill, or an oil well.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US40596295A | 1995-03-17 | 1995-03-17 | |
| US08/405,962 | 1995-03-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2215395A1 true CA2215395A1 (en) | 1996-09-26 |
Family
ID=23605950
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002215395A Abandoned CA2215395A1 (en) | 1995-03-17 | 1996-03-15 | Scale control in aqueous industrial systems |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0815060A1 (en) |
| JP (1) | JPH11502763A (en) |
| AU (1) | AU5176096A (en) |
| BR (1) | BR9609078A (en) |
| CA (1) | CA2215395A1 (en) |
| CZ (1) | CZ290697A3 (en) |
| NO (1) | NO974279D0 (en) |
| SK (1) | SK125397A3 (en) |
| WO (1) | WO1996029291A1 (en) |
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|---|---|---|---|---|
| BR0209062A (en) | 2001-04-16 | 2004-10-26 | Buckman Labor Inc | Process and system for removing scale buildup |
| JP2004293028A (en) * | 2003-03-13 | 2004-10-21 | Hakuto Co Ltd | Scale inhibitor and scale inhibitory method for barium sulfate in water system |
| US20100028202A1 (en) * | 2008-07-30 | 2010-02-04 | Zhaoyang Wan | Proactive control system for an industrial water system |
| JP5615049B2 (en) * | 2010-06-07 | 2014-10-29 | 伯東株式会社 | Barium sulfate scale prevention method |
| JP5435080B2 (en) * | 2012-05-24 | 2014-03-05 | 栗田工業株式会社 | How to prevent scale |
| JP6115730B2 (en) * | 2014-01-10 | 2017-04-19 | 住友金属鉱山株式会社 | Liquid analysis method, metal recovery method, and scale regeneration suppression method |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53146279A (en) * | 1977-05-26 | 1978-12-20 | Kurita Water Ind Ltd | Corrosion, scale, and stain inhibitor in aqueous system |
| EP0122013B1 (en) * | 1983-03-07 | 1988-12-21 | Calgon Corporation | Polymeric additives for water |
| US4600524A (en) * | 1983-12-08 | 1986-07-15 | W. R. Grace & Co. | Composition and method for inhibiting scale |
| AU612603B2 (en) * | 1986-11-13 | 1991-07-18 | B.F. Goodrich Company, The | Calcium phosphonate scale inhibition |
| EP0311072A3 (en) * | 1987-10-08 | 1989-06-07 | The B.F. Goodrich Company | Stabilization of metal ions and dispersion of particulates in aqueous systems |
| US4834955A (en) * | 1988-04-26 | 1989-05-30 | Nalco Chemical Company | Chemical formulation and combined process for inhibiting deposition and corrosion in cooling water and gypsum scaling in flue gas desulfurization scrubber systems |
| ATE109434T1 (en) * | 1990-04-13 | 1994-08-15 | Denac Nv | METHOD OF PREVENTING DEPOSITION AND CORROSION IN WATER TREATMENT SYSTEMS. |
| AU5968394A (en) * | 1993-02-17 | 1994-09-14 | Deutsche Nalco-Chemie Gmbh | Process for preventing deposits in a structure's drainage system |
-
1996
- 1996-03-15 CA CA002215395A patent/CA2215395A1/en not_active Abandoned
- 1996-03-15 CZ CZ972906A patent/CZ290697A3/en unknown
- 1996-03-15 EP EP96908554A patent/EP0815060A1/en not_active Withdrawn
- 1996-03-15 SK SK1253-97A patent/SK125397A3/en unknown
- 1996-03-15 JP JP8528431A patent/JPH11502763A/en not_active Ceased
- 1996-03-15 WO PCT/US1996/002698 patent/WO1996029291A1/en not_active Application Discontinuation
- 1996-03-15 AU AU51760/96A patent/AU5176096A/en not_active Abandoned
- 1996-03-15 BR BR9609078A patent/BR9609078A/en not_active IP Right Cessation
-
1997
- 1997-09-16 NO NO974279A patent/NO974279D0/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11502763A (en) | 1999-03-09 |
| NO974279L (en) | 1997-09-16 |
| EP0815060A1 (en) | 1998-01-07 |
| MX9707029A (en) | 1997-11-29 |
| SK125397A3 (en) | 1998-02-04 |
| AU5176096A (en) | 1996-10-08 |
| NO974279D0 (en) | 1997-09-16 |
| WO1996029291A1 (en) | 1996-09-26 |
| CZ290697A3 (en) | 1998-03-18 |
| BR9609078A (en) | 1999-02-02 |
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