CA2029073C - Scale control in aqueous systems - Google Patents
Scale control in aqueous systems Download PDFInfo
- Publication number
- CA2029073C CA2029073C CA 2029073 CA2029073A CA2029073C CA 2029073 C CA2029073 C CA 2029073C CA 2029073 CA2029073 CA 2029073 CA 2029073 A CA2029073 A CA 2029073A CA 2029073 C CA2029073 C CA 2029073C
- Authority
- CA
- Canada
- Prior art keywords
- acid
- copolymer
- acrylic acid
- composition
- amino
- 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
- 239000000203 mixture Substances 0.000 claims abstract description 82
- 239000000654 additive Substances 0.000 claims abstract description 44
- 229920001577 copolymer Polymers 0.000 claims abstract description 35
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229920002125 Sokalan® Polymers 0.000 claims abstract description 25
- 239000004584 polyacrylic acid Substances 0.000 claims abstract description 21
- BAERPNBPLZWCES-UHFFFAOYSA-N (2-hydroxy-1-phosphonoethyl)phosphonic acid Chemical compound OCC(P(O)(O)=O)P(O)(O)=O BAERPNBPLZWCES-UHFFFAOYSA-N 0.000 claims abstract description 20
- 230000000996 additive effect Effects 0.000 claims abstract description 20
- QPCDCPDFJACHGM-UHFFFAOYSA-N N,N-bis{2-[bis(carboxymethyl)amino]ethyl}glycine Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(=O)O)CCN(CC(O)=O)CC(O)=O QPCDCPDFJACHGM-UHFFFAOYSA-N 0.000 claims abstract description 16
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims abstract description 15
- 229960003330 pentetic acid Drugs 0.000 claims abstract description 15
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000010802 sludge Substances 0.000 claims abstract description 11
- 230000008021 deposition Effects 0.000 claims abstract description 7
- -1 allyl sulfonate Chemical compound 0.000 claims description 26
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 21
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 claims description 14
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 10
- NBIIXXVUZAFLBC-UHFFFAOYSA-N phosphoric acid Substances OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 10
- 229910052742 iron Inorganic materials 0.000 claims description 9
- 230000002401 inhibitory effect Effects 0.000 claims description 6
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 claims 8
- VKTHZHSHTVVWPN-UHFFFAOYSA-N [Na].[Na].[Na].[Na].[Na].CC(O)=O.CC(O)=O.CC(O)=O.CC(O)=O.CC(O)=O.NCCNCCN Chemical compound [Na].[Na].[Na].[Na].[Na].CC(O)=O.CC(O)=O.CC(O)=O.CC(O)=O.CC(O)=O.NCCNCCN VKTHZHSHTVVWPN-UHFFFAOYSA-N 0.000 claims 1
- 150000008064 anhydrides Chemical class 0.000 abstract description 11
- AGBXYHCHUYARJY-UHFFFAOYSA-N 2-phenylethenesulfonic acid Chemical compound OS(=O)(=O)C=CC1=CC=CC=C1 AGBXYHCHUYARJY-UHFFFAOYSA-N 0.000 abstract description 5
- 230000003405 preventing effect Effects 0.000 abstract description 5
- 150000008052 alkyl sulfonates Chemical class 0.000 abstract description 2
- BXLLINKJZLDGOX-UHFFFAOYSA-N dimethoxyphosphorylmethanamine Chemical compound COP(=O)(CN)OC BXLLINKJZLDGOX-UHFFFAOYSA-N 0.000 abstract 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- 238000001556 precipitation Methods 0.000 description 11
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- 230000032258 transport Effects 0.000 description 8
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 6
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- 239000011777 magnesium Substances 0.000 description 6
- 229910052749 magnesium Inorganic materials 0.000 description 6
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 6
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 5
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 5
- 239000011575 calcium Substances 0.000 description 5
- 229910052791 calcium Inorganic materials 0.000 description 5
- 229910000019 calcium carbonate Inorganic materials 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- 229910052708 sodium Inorganic materials 0.000 description 5
- 235000002639 sodium chloride Nutrition 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 239000001488 sodium phosphate Substances 0.000 description 4
- 239000002270 dispersing agent Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 235000011121 sodium hydroxide Nutrition 0.000 description 3
- 235000010265 sodium sulphite Nutrition 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 description 2
- 235000019800 disodium phosphate Nutrition 0.000 description 2
- 229910000397 disodium phosphate Inorganic materials 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 235000011152 sodium sulphate Nutrition 0.000 description 2
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical class [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 2
- MOMKYJPSVWEWPM-UHFFFAOYSA-N 4-(chloromethyl)-2-(4-methylphenyl)-1,3-thiazole Chemical compound C1=CC(C)=CC=C1C1=NC(CCl)=CS1 MOMKYJPSVWEWPM-UHFFFAOYSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 101150033824 PAA1 gene Proteins 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- ABLZXFCXXLZCGV-UHFFFAOYSA-N Phosphorous acid Chemical class OP(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 235000010216 calcium carbonate Nutrition 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000008240 homogeneous mixture Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000347 magnesium hydroxide Substances 0.000 description 1
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 1
- 159000000003 magnesium salts Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- MGFYIUFZLHCRTH-UHFFFAOYSA-N nitrilotriacetic acid Chemical compound OC(=O)CN(CC(O)=O)CC(O)=O MGFYIUFZLHCRTH-UHFFFAOYSA-N 0.000 description 1
- LQPLDXQVILYOOL-UHFFFAOYSA-I pentasodium;2-[bis[2-[bis(carboxylatomethyl)amino]ethyl]amino]acetate Chemical compound [Na+].[Na+].[Na+].[Na+].[Na+].[O-]C(=O)CN(CC([O-])=O)CCN(CC(=O)[O-])CCN(CC([O-])=O)CC([O-])=O LQPLDXQVILYOOL-UHFFFAOYSA-I 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 1
- 229920000193 polymethacrylate Polymers 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 235000017550 sodium carbonate Nutrition 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 235000019983 sodium metaphosphate Nutrition 0.000 description 1
- 235000011008 sodium phosphates Nutrition 0.000 description 1
- 230000003381 solubilizing effect Effects 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 235000019801 trisodium phosphate Nutrition 0.000 description 1
- 229910000406 trisodium phosphate Inorganic materials 0.000 description 1
Landscapes
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
A composition and process for preventing the deposition of scale and sludge in aqueous systems comprising adding to the system the combination of three or more additives selected from the group consisting of a) polyacrylic acid, copolymer of alkylsulfonate and malefic anhydride and mixtures thereof, b) hydroxy ethylidene diphosphonic acid, amino (trimethyl phosphonic acid), diethylenetriamine pentaacetic acid, and mixtures thereof, and c) copolymer of styrene sulfonate and malefic anhydride, copolymer of acrylic acid and acrylamide, poly(acrylic acid-co-hypophosphite) and mixtures thereof, and wherein the combination contains at least one additive selected from each of a), b) and c).
Description
(T h ('n !) ~1 "t <~
..A
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to compositions useful for inhibiting the deposition of scale and sludge deposits in aqueous systems particularly in steam generating boilers, and more specifically this invention relates to improved compositions comprising three or more additives selected from the group consisting of a) polyacrylic acid, copolymer of alkyl sulfonate and malefic anhydride, and mixtures thereof, b) amino (trimethylene phosphoric acid), hydroxyethylidene diphosphonic acid, diethylenetriamine pentaacetic acid, and mixtures thereof, and c) copolymer of styrene sulfonate and malefic anhydride, copolymer of acrylic acid and acrylamide, poly(acrylic acid- co-hypophosphite) and mixtures thereof, wherein at least one additive is selected from each of a), b) and c) supra.
Description of Prior Art The formation of scale and sludge deposits on heating surfaces is the most serious problem encountered in boiler operations. External water softening only partially removes from the boiler feedwater those scale-forming substances. In most industrial boilers, internal chemical treatment is applied to the boiler water to combat the scale-forming tendency of entrained impurities, such as calcium, magnesium salts, iron and silica. The internal chemical treatment of boiler water can be accomplished by either non-precipitation or precipitation treatment programs. Under the non-precipitation treatment program, chelants such as NTA (nitrilotriacetic acid) ct cy ,,. .,,, '~J <_r !-..~ O.. ii ~ ~' r and EDTA (ethylenediamine tetraacetic acid) are used.
EDTA is capable of preventing calcium and magnesium deposits by solubilizing and moving these scale-forming substances through the boiler system until they are removed by blowdown. However, EDTA is known to be corrosive under certain conditions for example when there is excessive residual in the boiler.
Under the precipitation treatment program, commonly used precipitating chemicals include soda ash and sodium phosphates, e.g. disodium phosphate, trisodium phosphate and sodium metaphosphate. Thus, magnesium is precipitated as magnesium hydroxide by increasing the alkalinity of the boiler water. The precipitate or sludge, which can be made non-sticky and easily manageable by the addition of a dispersant or sometimes called sludge conditioner, is periodically or continuously removed from the boiler through blowdown.
A wide variety of materials have been used as boiler dispersants such as sodium polyacrylates, sodium 2o polymethacrylates, sodium carboxymethylcellulose, styrene-malefic anhydride copolymers, etc. However, the results of their dispersants have not been completely satisfactory.
Summary of the Invention It is an object of this invention to provide improved compositions for inhibiting the deposition of scale and sludge in aqueous systems.
In accordance with this invention, there have been provided certain navel compositions which are comprised of a mixture of at least three additives selected from the group consisting of;
~~~;;ia~it~.::~;D
a) polyacrylic acid (PAA), copolymer of allyl sulfonate and malefic anhydride (ASMA) and mixtures thereof, b) amino(trimethylene phosphonic acid) (AMP), hydroxyethylidene diphosphonic acid (HEDPA), diethylenetriamine pentaacetic acid (DTPA) and mixtures thereof, and c) copolymer of styrene sulfonate and malefic anhydride (SMA), copolymer of acrylic acid and acrylamide (AAA), poly(acrylic acid-co-hypophosphite) (PAAHP) and mixtures thereof, wherein at least one additive is selected from each of a), b) and c) supra.
The novel compositions of this invention exhibit surprising and unexpected activity in preventing and controlling scale and sludge deposits in aqueous systems under both precipitation and non-precipitation treatment programs.
Detailed Description The present invention is directed to compositions with improved effectiveness for inhibiting the deposition of scale and sludge in aqueous systems. The compositions of this invention comprise a combination ' of three or more additives selected from the group consisting of;
a) polyacrylic acid (PAA), copolymer of allyl sulfonate and malefic anhydride (ASMA) and mixtures thereof, b) hydroxyethylidene diphosphonic acid (HEDPA), amino(trimethylene phosphonic acid) (AMP) and diethylenetriamine pentaacetic acid (DTPA) and mixtures thereof, and c) copolymer of styrene sulfonate and malefic anhydride (SMA), copolymer of acrylic acid and C4 w cY r~, ~! 'iu t:,d ;_,i ;,~~ ', acrylamide (AAA), poly(acrylic acid-co-hyphophosphite) (PAAHP) and mixtures thereof, wherein at least one additive is selected from each of a), b) and c) supra.
The ratio of additives a:b:c is typically in the range (9-1):(9-1):5-0.5, preferably (6-2):(6-2):(3:1) respectively on an active basis. Mixtures within a group, for example in group a) polyacrylic acid together with copolymer of allyl sulfonate and malefic anhydride, are typically in the range (10-1):(1-10) and are preferably I:1 on an active basis.
The polyacrylic acid preferably has a low molecular weight in the range of 800 to 90,000, most preferably 1000 to 5000 on a weight average basis. The copolymer of allyl sulfonate and malefic anhydride typically has a weight ratio of 10:1 to 1:10 respectively, preferably l:l and has a molecular weight in the 800 to 90,000 preferably 1000 to 10,000 on a weight average basis. The hydroxyethylidene diphosphonic acid and the amino(trimethylene phosphonic acid) are commercially available and conventional procedures for preparation of these are described, for example, in U.S. Patent 3,214,454 and U.S. Patent 3,234,124 respectively. These phosphonates can be in potassium, sodium or ammonium salts. The diethylenetriamine pentaacetic acid can be "as is" in acid form or in water soluble salts such as sodium, potassium and ammonium, most preferably the sodium salts. The DTPA is commercially available under the trademark of Hamp-EX Acid or Hamp-Ex 80 in sodium salts, of W. R. Grace & Co.-Conn. The poly(acrylic acid-co-hypophosphite) can be in a weight ratio of 20:1 to 1:20 respectively, preferably 4:1 to 16:1 having a molecular weight in the range of 1000 to 20,000, preferably 1,000 to 5,000 on a weight average basis.
Fa n as f~ .-. , .:
r~> ~f ~ ~:'~ ~~,;:
The copolymer of styrene sulfonate and malefic anhydride can be in a weight ratio of 10:1 to 1:10 respectively, preferably 1:1 having a molecular weight in the range 800 to 20,000, preferably 1000 to 5000 on a weight average basis. The copolymer of acrylic acid and acrylamide typically has a weight ratio of 1:10 to 10:1 and a molecular weight in the range 800 to 90,000 preferably 1000 to 10,000 on a weight average basis.
The combination of additives in accordance with this invention are capable of preventing and controlling scale in aqueous systems, such as steam generating boilers, under both the precipitation and non-precipitation treatment programs.
The total amounts of each additive can vary widely, provided it is in an amount effective to control the deposition of scale and sludge and in general, each additive is present in the range 0.1 ppm to 500 ppm, preferably 0.5 to 10 ppm and most preferably between 1 to 5 ppm.
The additives may be added to the aqueous system individually or they may be blended into uniform, homogeneous mixture, and optionally diluted with a suitable water-miscible diluents. In such mixtures, additives, (a) will normally be present in an amount from 15 to 90%, preferably 40 to 70%, and most preferably 45 to 55% by weight. The amount of the second additive, (b), will generally be in the range 5 to 45%, preferably 10 to 35 and most preferably 20 to 30% by weight. Thus, the amount of the third component is generally between 5 to 40%, preferably 10 to 25 and most preferably 15 to 20% by weight.
In addition to the instant composition, it is possible to incorporate into the composition or add to the aqueous system other materials used in the C3 'u C? !1, ~ ' 7 ;.~1,~::;~'_T';~c>
treatment of aqueous systems. Such materials include, but are not limited to corrosion inhibitors.
The following examples are provided to illustrate the invention, but axe not to be construed as limiting the invention in any way except as indicated on the appended claims. The examples provided herein include various embodiments of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is understood that modifications and variations may be practiced without departing from the spirit and scope of the novel concepts of this invention.
The evaluation of the effectiveness of the additives under the non-precipitation and precipitation treatment programs was carried out in a small laboratory boiler. This boiler has been described previously in the proceedings of the Fifteenth Annual Water Conference, Engineers Society of Western Pennsylvania, pages 87-102.
Using the laboratory boiler, the efficiency of the blended additives to transport calcium, magnesium and iron through the boiler system was tested at 200 psig for four days. The feedwater contained about 2 ppm as CaC03 of total hardness having a 2:1 (as CaC03) of calcium to magnesium ratio, 0.5 ppm as Fe of iron, 20 ppm as C1 of chloride, 35 ppm as SOu of sulfate and less than 1 ppm as Si02 of silica. The boiler water concentration was about ten times. Sodium hydroxide and sodium sulfite were used to maintain a hydroxide alkalinity of 300-350 ppm as CaC03 and a residual sulfite of at least 20 ppm as 503. The feedwater and c, ~L <~.. ~y .;w '->
:~ ; , ~ . . ~ Vii. f ~ 2 -boiler water samples were analyzed far calcium, magnesium and iron by atomic absorption.
Various blended additives were tested using a dosag e of 5:1 active additive per total hardness plus iron. The compositionstested have shown excellent total hardness recoveryin the boiler.
1. Composition I - PAA + AMP + SMA
(6:3:2 active) 2. Composition TI - PAA + DTPA + AAA
(6:3:2 active) 3. Composition III - AAA + AMP + ASMA
(6:6:2 active) 4. Composition IV - ASMA + AMP + AAA
(6:3:2 active) 5. Composition V - ASMA + HEDPA + SMA
(6;3:2 active) 6. Composition VI - PAA + AMP + SMA
(6:6:2 active) 7. Composition VII - ASMA + HEDPA + SMA
(6:3:4 active) 8. Composition VIII- PAA + AMP + AAA + PAAHP
(6:3:2:2 active) 9. Composition IX - PAA + AMP + SMA + ASMA
(6:3:2:2 active) 10. Composition X - PAA + HEDPA + AAA + PAAHP
(6:3:2:2 active) The excellent total hardness transport performance of the 10 products is illustrated in the following table.
c°m~ n n ~ ~ ~ ~ =. ~
,, 'y ~;'. ,: " ,. ~:.?
-Table 1 Performance in ~ Transport Total Run No. Additive Hardness Iron R-20 None (Blank) 15.3 0.8 C-1429 Composition I 161.7 41.6 C-1430 Composition II 127.4 66.2 R-43 Composition III 111.0 81.5 C-1435 Composition IV 115.0 11.5 R-23 Composition V 110.0 82.1 R-42 Composition VI 89.0 86.4 R-30 Composition VII 87.5 91.2 R-32 Composition VIII 90.4 68.8 R-33 Composition IX 84.2 72.5 R-38 Composition X 94.8 90.4 When the individual for additives were evaluated material transports 200 psig,the following at data were obta ined.
._ , , :~,~ c~~'t,~ ~:~ F.~
- to -Table 2 Total Hardness ~ Iron Run Nos. Additive Transport Transport M-1911/R-11 None (Blank)17.0 0.7 C-1416/R-12 PAA '179 3.4 C-1417/C-1422 SMA 35.9 30.4 M-1906/M-1913 AAA 71.8 23.5 C-1415/R-12 ASMA 56.0 22.4 R-48/R-49 PAAHP 74.4 14.9 M-1909/M-1914 HEDPA 24.7 22.0 R-8/M-1916 AMP 39.2 17.5 C-1418/R-21 DTPA 51.8 32.2 R-7/R-10 EDTA 68.8 12.1 Using the same procedure as in Example 1, except the boiler pressure was 600 psig, the excellent total hardness transport performance of three products tested is shown as follows:
Table 3 Run No. Additive ~ Total Hardness Transport R-50 None (Blank) 20.2 R-52 Composition VII 115.9 R-51 Composition X 98~1 R-81 Composition VIII 95.9 The scale preventing property of the blended additives on a precipitation boiler water treatment program was determined using the same small laboratory boiler. The boiler has three removable tubes. After the completion of a test, the boiler tubes were removed . ,j ~J ~ l~J ~:-J ~~ i~/ ~.J
..A
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to compositions useful for inhibiting the deposition of scale and sludge deposits in aqueous systems particularly in steam generating boilers, and more specifically this invention relates to improved compositions comprising three or more additives selected from the group consisting of a) polyacrylic acid, copolymer of alkyl sulfonate and malefic anhydride, and mixtures thereof, b) amino (trimethylene phosphoric acid), hydroxyethylidene diphosphonic acid, diethylenetriamine pentaacetic acid, and mixtures thereof, and c) copolymer of styrene sulfonate and malefic anhydride, copolymer of acrylic acid and acrylamide, poly(acrylic acid- co-hypophosphite) and mixtures thereof, wherein at least one additive is selected from each of a), b) and c) supra.
Description of Prior Art The formation of scale and sludge deposits on heating surfaces is the most serious problem encountered in boiler operations. External water softening only partially removes from the boiler feedwater those scale-forming substances. In most industrial boilers, internal chemical treatment is applied to the boiler water to combat the scale-forming tendency of entrained impurities, such as calcium, magnesium salts, iron and silica. The internal chemical treatment of boiler water can be accomplished by either non-precipitation or precipitation treatment programs. Under the non-precipitation treatment program, chelants such as NTA (nitrilotriacetic acid) ct cy ,,. .,,, '~J <_r !-..~ O.. ii ~ ~' r and EDTA (ethylenediamine tetraacetic acid) are used.
EDTA is capable of preventing calcium and magnesium deposits by solubilizing and moving these scale-forming substances through the boiler system until they are removed by blowdown. However, EDTA is known to be corrosive under certain conditions for example when there is excessive residual in the boiler.
Under the precipitation treatment program, commonly used precipitating chemicals include soda ash and sodium phosphates, e.g. disodium phosphate, trisodium phosphate and sodium metaphosphate. Thus, magnesium is precipitated as magnesium hydroxide by increasing the alkalinity of the boiler water. The precipitate or sludge, which can be made non-sticky and easily manageable by the addition of a dispersant or sometimes called sludge conditioner, is periodically or continuously removed from the boiler through blowdown.
A wide variety of materials have been used as boiler dispersants such as sodium polyacrylates, sodium 2o polymethacrylates, sodium carboxymethylcellulose, styrene-malefic anhydride copolymers, etc. However, the results of their dispersants have not been completely satisfactory.
Summary of the Invention It is an object of this invention to provide improved compositions for inhibiting the deposition of scale and sludge in aqueous systems.
In accordance with this invention, there have been provided certain navel compositions which are comprised of a mixture of at least three additives selected from the group consisting of;
~~~;;ia~it~.::~;D
a) polyacrylic acid (PAA), copolymer of allyl sulfonate and malefic anhydride (ASMA) and mixtures thereof, b) amino(trimethylene phosphonic acid) (AMP), hydroxyethylidene diphosphonic acid (HEDPA), diethylenetriamine pentaacetic acid (DTPA) and mixtures thereof, and c) copolymer of styrene sulfonate and malefic anhydride (SMA), copolymer of acrylic acid and acrylamide (AAA), poly(acrylic acid-co-hypophosphite) (PAAHP) and mixtures thereof, wherein at least one additive is selected from each of a), b) and c) supra.
The novel compositions of this invention exhibit surprising and unexpected activity in preventing and controlling scale and sludge deposits in aqueous systems under both precipitation and non-precipitation treatment programs.
Detailed Description The present invention is directed to compositions with improved effectiveness for inhibiting the deposition of scale and sludge in aqueous systems. The compositions of this invention comprise a combination ' of three or more additives selected from the group consisting of;
a) polyacrylic acid (PAA), copolymer of allyl sulfonate and malefic anhydride (ASMA) and mixtures thereof, b) hydroxyethylidene diphosphonic acid (HEDPA), amino(trimethylene phosphonic acid) (AMP) and diethylenetriamine pentaacetic acid (DTPA) and mixtures thereof, and c) copolymer of styrene sulfonate and malefic anhydride (SMA), copolymer of acrylic acid and C4 w cY r~, ~! 'iu t:,d ;_,i ;,~~ ', acrylamide (AAA), poly(acrylic acid-co-hyphophosphite) (PAAHP) and mixtures thereof, wherein at least one additive is selected from each of a), b) and c) supra.
The ratio of additives a:b:c is typically in the range (9-1):(9-1):5-0.5, preferably (6-2):(6-2):(3:1) respectively on an active basis. Mixtures within a group, for example in group a) polyacrylic acid together with copolymer of allyl sulfonate and malefic anhydride, are typically in the range (10-1):(1-10) and are preferably I:1 on an active basis.
The polyacrylic acid preferably has a low molecular weight in the range of 800 to 90,000, most preferably 1000 to 5000 on a weight average basis. The copolymer of allyl sulfonate and malefic anhydride typically has a weight ratio of 10:1 to 1:10 respectively, preferably l:l and has a molecular weight in the 800 to 90,000 preferably 1000 to 10,000 on a weight average basis. The hydroxyethylidene diphosphonic acid and the amino(trimethylene phosphonic acid) are commercially available and conventional procedures for preparation of these are described, for example, in U.S. Patent 3,214,454 and U.S. Patent 3,234,124 respectively. These phosphonates can be in potassium, sodium or ammonium salts. The diethylenetriamine pentaacetic acid can be "as is" in acid form or in water soluble salts such as sodium, potassium and ammonium, most preferably the sodium salts. The DTPA is commercially available under the trademark of Hamp-EX Acid or Hamp-Ex 80 in sodium salts, of W. R. Grace & Co.-Conn. The poly(acrylic acid-co-hypophosphite) can be in a weight ratio of 20:1 to 1:20 respectively, preferably 4:1 to 16:1 having a molecular weight in the range of 1000 to 20,000, preferably 1,000 to 5,000 on a weight average basis.
Fa n as f~ .-. , .:
r~> ~f ~ ~:'~ ~~,;:
The copolymer of styrene sulfonate and malefic anhydride can be in a weight ratio of 10:1 to 1:10 respectively, preferably 1:1 having a molecular weight in the range 800 to 20,000, preferably 1000 to 5000 on a weight average basis. The copolymer of acrylic acid and acrylamide typically has a weight ratio of 1:10 to 10:1 and a molecular weight in the range 800 to 90,000 preferably 1000 to 10,000 on a weight average basis.
The combination of additives in accordance with this invention are capable of preventing and controlling scale in aqueous systems, such as steam generating boilers, under both the precipitation and non-precipitation treatment programs.
The total amounts of each additive can vary widely, provided it is in an amount effective to control the deposition of scale and sludge and in general, each additive is present in the range 0.1 ppm to 500 ppm, preferably 0.5 to 10 ppm and most preferably between 1 to 5 ppm.
The additives may be added to the aqueous system individually or they may be blended into uniform, homogeneous mixture, and optionally diluted with a suitable water-miscible diluents. In such mixtures, additives, (a) will normally be present in an amount from 15 to 90%, preferably 40 to 70%, and most preferably 45 to 55% by weight. The amount of the second additive, (b), will generally be in the range 5 to 45%, preferably 10 to 35 and most preferably 20 to 30% by weight. Thus, the amount of the third component is generally between 5 to 40%, preferably 10 to 25 and most preferably 15 to 20% by weight.
In addition to the instant composition, it is possible to incorporate into the composition or add to the aqueous system other materials used in the C3 'u C? !1, ~ ' 7 ;.~1,~::;~'_T';~c>
treatment of aqueous systems. Such materials include, but are not limited to corrosion inhibitors.
The following examples are provided to illustrate the invention, but axe not to be construed as limiting the invention in any way except as indicated on the appended claims. The examples provided herein include various embodiments of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is understood that modifications and variations may be practiced without departing from the spirit and scope of the novel concepts of this invention.
The evaluation of the effectiveness of the additives under the non-precipitation and precipitation treatment programs was carried out in a small laboratory boiler. This boiler has been described previously in the proceedings of the Fifteenth Annual Water Conference, Engineers Society of Western Pennsylvania, pages 87-102.
Using the laboratory boiler, the efficiency of the blended additives to transport calcium, magnesium and iron through the boiler system was tested at 200 psig for four days. The feedwater contained about 2 ppm as CaC03 of total hardness having a 2:1 (as CaC03) of calcium to magnesium ratio, 0.5 ppm as Fe of iron, 20 ppm as C1 of chloride, 35 ppm as SOu of sulfate and less than 1 ppm as Si02 of silica. The boiler water concentration was about ten times. Sodium hydroxide and sodium sulfite were used to maintain a hydroxide alkalinity of 300-350 ppm as CaC03 and a residual sulfite of at least 20 ppm as 503. The feedwater and c, ~L <~.. ~y .;w '->
:~ ; , ~ . . ~ Vii. f ~ 2 -boiler water samples were analyzed far calcium, magnesium and iron by atomic absorption.
Various blended additives were tested using a dosag e of 5:1 active additive per total hardness plus iron. The compositionstested have shown excellent total hardness recoveryin the boiler.
1. Composition I - PAA + AMP + SMA
(6:3:2 active) 2. Composition TI - PAA + DTPA + AAA
(6:3:2 active) 3. Composition III - AAA + AMP + ASMA
(6:6:2 active) 4. Composition IV - ASMA + AMP + AAA
(6:3:2 active) 5. Composition V - ASMA + HEDPA + SMA
(6;3:2 active) 6. Composition VI - PAA + AMP + SMA
(6:6:2 active) 7. Composition VII - ASMA + HEDPA + SMA
(6:3:4 active) 8. Composition VIII- PAA + AMP + AAA + PAAHP
(6:3:2:2 active) 9. Composition IX - PAA + AMP + SMA + ASMA
(6:3:2:2 active) 10. Composition X - PAA + HEDPA + AAA + PAAHP
(6:3:2:2 active) The excellent total hardness transport performance of the 10 products is illustrated in the following table.
c°m~ n n ~ ~ ~ ~ =. ~
,, 'y ~;'. ,: " ,. ~:.?
-Table 1 Performance in ~ Transport Total Run No. Additive Hardness Iron R-20 None (Blank) 15.3 0.8 C-1429 Composition I 161.7 41.6 C-1430 Composition II 127.4 66.2 R-43 Composition III 111.0 81.5 C-1435 Composition IV 115.0 11.5 R-23 Composition V 110.0 82.1 R-42 Composition VI 89.0 86.4 R-30 Composition VII 87.5 91.2 R-32 Composition VIII 90.4 68.8 R-33 Composition IX 84.2 72.5 R-38 Composition X 94.8 90.4 When the individual for additives were evaluated material transports 200 psig,the following at data were obta ined.
._ , , :~,~ c~~'t,~ ~:~ F.~
- to -Table 2 Total Hardness ~ Iron Run Nos. Additive Transport Transport M-1911/R-11 None (Blank)17.0 0.7 C-1416/R-12 PAA '179 3.4 C-1417/C-1422 SMA 35.9 30.4 M-1906/M-1913 AAA 71.8 23.5 C-1415/R-12 ASMA 56.0 22.4 R-48/R-49 PAAHP 74.4 14.9 M-1909/M-1914 HEDPA 24.7 22.0 R-8/M-1916 AMP 39.2 17.5 C-1418/R-21 DTPA 51.8 32.2 R-7/R-10 EDTA 68.8 12.1 Using the same procedure as in Example 1, except the boiler pressure was 600 psig, the excellent total hardness transport performance of three products tested is shown as follows:
Table 3 Run No. Additive ~ Total Hardness Transport R-50 None (Blank) 20.2 R-52 Composition VII 115.9 R-51 Composition X 98~1 R-81 Composition VIII 95.9 The scale preventing property of the blended additives on a precipitation boiler water treatment program was determined using the same small laboratory boiler. The boiler has three removable tubes. After the completion of a test, the boiler tubes were removed . ,j ~J ~ l~J ~:-J ~~ i~/ ~.J
from the boiler. The scale or deposit farmed on the six inches of the central length of each tube was removed by scraping, collected in a tared vial and weighed. The scale scraped on the tubes on a blank test (no additive) and on a test with the additive being tested is compared.
The feedwater for the evaluation of additives was prepared by diluting Lake Zurich, Illinois tap water with distilled water to 40 ppm total hardness as CaCO3, followed by adjustment to a 6 to 1 elemental calcium to magnesium ratio using calcium chloride and/or magnesium chloride. The feedwater was fed to the boiler together with chemical treatment solutions (containing sodium sulfate, sodium sulfite, sodium hydroxide, sodium chloride, disodium phosphate and the additives for scale prevention) in a ratio of three volumes of feedwater to one volume of chemical treatment solution, giving a feedwater total hardness of 30 ppm as CaC03.
In the case of a blank test, no additive was added.
All scaling tests, whether boiler water additive was present or absent (blank), were carried out in fixed manner as described as follows: Boiler blowdown was adjusted to 10~ of the boiler feedwater, giving approximately 10 concentrations of the boiler water salines. Using the feedwater described previously in this paragraph, the composition of the chemical treatment solution was adjusted to give a boiler (after the 10 concentrations) of the following composition.
f~ ~~ a. i air i1 F~ ~.~ r ,. c Table 4 Sodium hydroxideas NaOH 258 ppm Sodium carbonateas Na2C03 120 ppm Sodium chloride s NaCl 681 ppm a Sodium sulfite NaZS03 30-50 ppm as Sodium sulfate Na2S04 819 ppm as Silica as Si02 less than 1 ppm Iron as Fe less than 1 ppm Phosphate as P04 20-40 ppm All scaling tests were run for 47 hours each at a boiler pressure of 400 psig.
The effective scale inhibiting properties of the blended additive products are illustrated in the following table.
C, sip w, ,,., , ,- D
i~ ~:~ r.:~ il r, c:,'!
The feedwater for the evaluation of additives was prepared by diluting Lake Zurich, Illinois tap water with distilled water to 40 ppm total hardness as CaCO3, followed by adjustment to a 6 to 1 elemental calcium to magnesium ratio using calcium chloride and/or magnesium chloride. The feedwater was fed to the boiler together with chemical treatment solutions (containing sodium sulfate, sodium sulfite, sodium hydroxide, sodium chloride, disodium phosphate and the additives for scale prevention) in a ratio of three volumes of feedwater to one volume of chemical treatment solution, giving a feedwater total hardness of 30 ppm as CaC03.
In the case of a blank test, no additive was added.
All scaling tests, whether boiler water additive was present or absent (blank), were carried out in fixed manner as described as follows: Boiler blowdown was adjusted to 10~ of the boiler feedwater, giving approximately 10 concentrations of the boiler water salines. Using the feedwater described previously in this paragraph, the composition of the chemical treatment solution was adjusted to give a boiler (after the 10 concentrations) of the following composition.
f~ ~~ a. i air i1 F~ ~.~ r ,. c Table 4 Sodium hydroxideas NaOH 258 ppm Sodium carbonateas Na2C03 120 ppm Sodium chloride s NaCl 681 ppm a Sodium sulfite NaZS03 30-50 ppm as Sodium sulfate Na2S04 819 ppm as Silica as Si02 less than 1 ppm Iron as Fe less than 1 ppm Phosphate as P04 20-40 ppm All scaling tests were run for 47 hours each at a boiler pressure of 400 psig.
The effective scale inhibiting properties of the blended additive products are illustrated in the following table.
C, sip w, ,,., , ,- D
i~ ~:~ r.:~ il r, c:,'!
Table 5 Active Dosage in the Scaling Scale Feed, Rate, Reduc-Run No. Additives ppm g,/ftz tion. %
/hr M-1947 None (Blank) - 0.220 -M-1443 PAA 1 0.046 79.1 M-1703 SMA 1 0.010 95.4 M-1716 AAA 1 0.061 72.3 C-1138 ASMA 1 0.006 97.3 C-1506 PAAHP 1 0.099 58.2 M-398 HEDPA 1 0.145 34.1 M-372 AMP 1 0.074 66.4 C-1439 Composition I 1 0.000 100.0 M-1934 Composition V 1 0.002 99.1 M-1936 Composition VII 1 0.004 98.2 M-1939 Composition X 1 0.009 95.9 C-1441 Composition I 0.5 0.015 93.8 M-1935 Composition V 0.5 0.128 39.4 M-1938 Composition VII 0.5 0.042 80.1 M-1940 Composition X 0.5 0.069 68.6 M-1950 Composition VI 0.5 0.019 90.9 M-1946 Composition III 0.5 0.065 70.4
/hr M-1947 None (Blank) - 0.220 -M-1443 PAA 1 0.046 79.1 M-1703 SMA 1 0.010 95.4 M-1716 AAA 1 0.061 72.3 C-1138 ASMA 1 0.006 97.3 C-1506 PAAHP 1 0.099 58.2 M-398 HEDPA 1 0.145 34.1 M-372 AMP 1 0.074 66.4 C-1439 Composition I 1 0.000 100.0 M-1934 Composition V 1 0.002 99.1 M-1936 Composition VII 1 0.004 98.2 M-1939 Composition X 1 0.009 95.9 C-1441 Composition I 0.5 0.015 93.8 M-1935 Composition V 0.5 0.128 39.4 M-1938 Composition VII 0.5 0.042 80.1 M-1940 Composition X 0.5 0.069 68.6 M-1950 Composition VI 0.5 0.019 90.9 M-1946 Composition III 0.5 0.065 70.4
Claims (22)
1. A composition For inhibiting the deposition of scale and sludge in aqueous systems comprising the combination of three or more additives selected from the group consisting of:
a) polyacrylic acid (PAA), copolymer of allyl sulfonate and maleic anhydride (ASMA) and mixtures thereof, b) hydroxyethylidene diphosphonic acid (HEDPA), amino(trimethylene phosphoric acid) (AMP), diethylenetriamine pentaacetic acid (DTPA), and mixtures thereof, and c) copolymer of acrylic acid and acrylalmide (AAA), and poly(acrylic acid-co-hyphophosphite) (PAAHP) and mixtures thereof, and wherein the composition contains at least one additive selected from each of a), b) and c) supra, wherein the ratio additives a:b:c is from about 9-1:9-1:5-0.5, respectively on an active basis.
a) polyacrylic acid (PAA), copolymer of allyl sulfonate and maleic anhydride (ASMA) and mixtures thereof, b) hydroxyethylidene diphosphonic acid (HEDPA), amino(trimethylene phosphoric acid) (AMP), diethylenetriamine pentaacetic acid (DTPA), and mixtures thereof, and c) copolymer of acrylic acid and acrylalmide (AAA), and poly(acrylic acid-co-hyphophosphite) (PAAHP) and mixtures thereof, and wherein the composition contains at least one additive selected from each of a), b) and c) supra, wherein the ratio additives a:b:c is from about 9-1:9-1:5-0.5, respectively on an active basis.
2. A composition according to claim 1 wherein the ratio of additives a:b:c is from about 6:3:2 respectively.
3. A composition according to claim 1 wherein (a) is polyacrylic acid and (b) is amino(trimethylene phosphoric acid).
4. A composition according to claim 1 wherein (a) is polyacrylic acid, (b) is diethylenetriamine pentaacetic acid and (c) is copolymer of acrylic acid and acrylamide.
5. A composition according to claim 1 wherein (a) is copolymer of allyl sulfonate and maleic anhydride, (b) is amino(trimethylene phosphoric acid) and (c) is copolymer of acrylic acid and acrylamide.
6. A composition according to claim 1 wherein (a) is copolymer of allyl sulfonate and maleic anhydride and (b) is hydroxyethylidene diphosphonic acid.
7. A composition according to claim 1 wherein (a) is polyacrylic acid, (b) is amino(trimethylene phosphoric acid), and (c) is a mixture of copolymer of acrylic acid and acrylamide, and poly(acrylic acid-co-hypophosphite).
8. A composition according to claim 1 wherein (a) is a mixture of polyacrylic acid and copolymer of allyl sulfonate and maleic anhydride and (b) is amino(trimethylene phosphoric acid).
9. A composition according to claim 1 wherein (a) is polyacrylic acid, (b) is hydroxyethylidene diphosphonic acid, and (c) is a mixture of copolymer of acrylic acid and acrylamide and poly(acrylic acid-co-hypophosphite).
10. A method for inhibiting the deposition of scale and sludge in aqueous systems comprising adding to the aqueous system the composition which further comprises the combination of three or more additives selected from the group consisting of:
a) polyacrylic acid (PAA), copolymer of allyl sulfonate and maleic anhydride (ASMA), b) hydroxyethylidene diphosphonic acid (HEDPA), amino(trimethylene phosphoric acid) (AMP), and pentasodium diethylenetriamine pentaacetic acid (DTPA), and c) copolymer of acrylic acid and acrylalmide (AAA), and poly(acrylic acid-co-hyphophosphite) (PAAHP), and wherein the composition contains at least one additive selected from each of a), b) and c) supra wherein the ratio of additives a:b:c is from about 9-1:9-1:5-0.5 respectively on an active basis.
a) polyacrylic acid (PAA), copolymer of allyl sulfonate and maleic anhydride (ASMA), b) hydroxyethylidene diphosphonic acid (HEDPA), amino(trimethylene phosphoric acid) (AMP), and pentasodium diethylenetriamine pentaacetic acid (DTPA), and c) copolymer of acrylic acid and acrylalmide (AAA), and poly(acrylic acid-co-hyphophosphite) (PAAHP), and wherein the composition contains at least one additive selected from each of a), b) and c) supra wherein the ratio of additives a:b:c is from about 9-1:9-1:5-0.5 respectively on an active basis.
11. A method according to claim 10 wherein the amount of additive is in the range 1 ppm to 500 ppm.
12. A method according to claim 10 wherein the amount of additive is equal to the total hardness plus iron of the aqueous system.
13. A method according to claim 10 wherein the ratio of additives a:b:c is from about 6:3:2 respectively.
14. A method according to claim 10 wherein (a) is polyacrylic acid and (b) is amino(trimethylene phosphoric acid).
15. A method according to claim 10 wherein (a) is polyacrylic acid, (b) is diethylenetriamine pentaacetic acid and (c) is copolymer of acrylic acid and acrylamide.
16. A method according to claim 10 wherein (a) is copolymer of allyl sulfonate and maleic anhydride, (b) is amino(trimethylene phosphoric acid) and (c) is copolymer of acrylic acid and acrylamide.
17. A method according to claim 10 wherein (a) is copolymer of allyl sulfonate and maleic anhydride and (b) is hydroxyethylidene diphosphonic acid.
18. A method according to claim 10 wherein (a) is polyacrylic acid, (b) is amino(trimethylene phosphoric acid), and (c) is a mixture of copolymer of acrylic acid and acrylamide, and poly(acrylic acid-co-hypophosphite).
19. A method according to claim 10 wherein (a) is a mixture of polyacrylic acid and copolymer of allyl sulfonate and maleic anhydride and (b) is amino(trimethylene phosphonic acid).
20, A method according to claim 10 wherein (a) is polyacrylic acid, (b) is hydroxyethylidene diphosphonic acid, and (c) is a mixture of copolymer of acrylic acid and acrylamide, and poly(acrylic acid-co-hypophosphite).
21. A composition according to claim 1 wherein the ratio of additives a:b:c is from (6-2):(6-2):(3-1).
22. A method according to claim 10 wherein the ratio of additives a:b:c is from (6-2):(6-2):(3-1).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US51228290A | 1990-04-20 | 1990-04-20 | |
| US512,282 | 1990-04-20 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2029073A1 CA2029073A1 (en) | 1991-10-21 |
| CA2029073C true CA2029073C (en) | 2000-12-12 |
Family
ID=24038452
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2029073 Expired - Fee Related CA2029073C (en) | 1990-04-20 | 1990-10-31 | Scale control in aqueous systems |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AU633717B2 (en) |
| CA (1) | CA2029073C (en) |
| NZ (1) | NZ235904A (en) |
| ZA (1) | ZA908729B (en) |
-
1990
- 1990-10-31 ZA ZA908729A patent/ZA908729B/en unknown
- 1990-10-31 CA CA 2029073 patent/CA2029073C/en not_active Expired - Fee Related
- 1990-10-31 NZ NZ23590490A patent/NZ235904A/en unknown
-
1991
- 1991-04-09 AU AU74222/91A patent/AU633717B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| CA2029073A1 (en) | 1991-10-21 |
| ZA908729B (en) | 1991-12-24 |
| AU633717B2 (en) | 1993-02-04 |
| AU7422291A (en) | 1991-10-24 |
| NZ235904A (en) | 1992-04-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4255259A (en) | Scale inhibition | |
| US4048066A (en) | Method of inhibiting scale | |
| US3959167A (en) | Method and composition of inhibiting scale | |
| US4306991A (en) | Scale inhibition | |
| US4029577A (en) | Polymers for use in water treatment | |
| US4536292A (en) | Carboxylic/sulfonic/quaternary ammonium polymers for use as scale and corrosion inhibitors | |
| US3890228A (en) | Polyacrylate-polyphosphonic acid treatment in aqueous systems | |
| US5288410A (en) | Scale control in aqueous systems | |
| US4374733A (en) | Method for treating aqueous mediums | |
| EP0071323B1 (en) | Method and composition for treating aqueous mediums | |
| US4175100A (en) | Preparation of anionic polymers for use as scale inhibitors and anti-precipitants | |
| BR0208127B1 (en) | method for controlling fouling and deposition formation in aqueous systems. | |
| US5200105A (en) | Scale control in aqueous systems | |
| NZ207345A (en) | Scale and corrosion inhibiting mixtures | |
| JPS60143899A (en) | Scale inhibiting composition and method | |
| JPS6152760B2 (en) | ||
| US3666664A (en) | Compositions and methods for controlling scale | |
| US4556493A (en) | Composition and method for inhibiting scale | |
| US4446045A (en) | Composition for treating aqueous mediums | |
| US4324664A (en) | Method and composition for treating aqueous mediums | |
| GB2087862A (en) | Process for dispersing particulate material in aqueous systems | |
| CA2029073C (en) | Scale control in aqueous systems | |
| CA1224999A (en) | Composition and method for inhibiting scale | |
| US4604212A (en) | Use of copolymers of carboxylic monomer and betaine-containing monomer as corrosion and scale inhibitors | |
| AU603369B2 (en) | Polyacrylate blends as boiler scale inhibitors |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |