METHOD OF INHIBITING SCALE FORMATION AND DEPOSITION IN DESALINATION SYSTEMS

1 . A method of inhibiting formation and deposition of scale in a desalination process, the method comprising adding to a saline aqueous source an effective amount of a scale-inhibiting composition including an acrylic acid 2-acrylamido-2-methylpropyl sulfonic acid copolymer, wherein said copolymer optionally includes a fluorescent moiety.

2 . The method of claim 1 , wherein the scale-inhibiting composition includes a synergistically effective amount of an oligomeric phosphosuccinic acid.

3 . The method of claim 2 , wherein the oligomeric phosphosuccinic acid is a phosphinosuccinic acid oligomer having a formula [R x —(POOM)-R1 Y ], wherein R and R1 independently are H, [CH(COOM)], or [CH(COOM)-CH(COOM)], X and Y are either 0 or a small whole number, the sum of X and Y being greater than 2, and M is chosen independently at each occurrence from the group consisting of: H, Na, K, NH 4 , and combinations thereof.

4 . The method of claim 2 , wherein the oligomeric phosphinosuccinic acid includes less than about 22 mole percent monosodium phosphinicobis-succinic acid; less than about 26 mole percent monosodium phosphinico-succinic acid; less than about 12 mole percent sodium phosphosuccinic acid; less than about 5 mole percent sodium phosphate; less than about 6 mole percent sodium phosphate; less than about 6 mole percent sodium hypophosphite; and greater than about 32 mole percent phosphinosuccinic acid oligomer having a formula [R x —(POOM)-R1 Y ], wherein R and R1 independently are H, [CH(COOM)], or [CH(COOM)-CH(COOM)], X and Y are either 0 or a small whole number, the sum of X and Y being greater than 2, and M is chosen independently at each occurrence from the group consisting of: H, Na, K, NH 4 .

5 . The method of claim 2 , wherein the oligomeric phosphosuccinic acid comprises: (a) phosphinosuccinic acid oligomer having formula [R x —(POOM)-R1 Y ], wherein R and R1 independently are H, [CH(COOM)], or [CH(COOM)—CH(COOM)], X and Y are either 0 or a small whole number, the sum of X and Y being greater than 2, and M is chosen independently at each occurrence from the group consisting of: H, Na, K, NH 4 , or combinations thereof (b) about 36 mole percent to about 49 mole percent bis phosphinosuccinic acid adducts and about 26 mole percent to about 35 mole percent oligomeric phosphinosuccinic acid adducts; and (c) about 22 mole percent monosodium phosphinicobis-succinic acid, less than about 26 mole percent monosodium phosphinico-succinic acid, less than about 12 mole percent sodium phosphosuccinic acid, less than about 5 mole percent sodium phosphate, less than about 6 mole percent sodium phosphate, less than about 6 mole percent sodium hypophosphite, and greater than about 32 mole percent phosphinosuccinic acid oligomer having the formula [R x —(POOM)-R1 y ].

6 . The method of claim 2 , wherein the scale-inhibiting composition includes about 40 weight percent maleic anhydride reaction products.

7 . The method of claim 2 , wherein the scale-inhibiting composition includes mono, bis, and oligomeric phosphinosuccinic acid adducts.

8 . The method of claim 7 , wherein the scale-inhibiting composition includes mono, bis, and oligomeric phosphinosuccinic acid adducts selected from group consisting of: about 20 mole percent to about 85 mole percent bis phosphinosuccinic acid adduct; and about 36 mole percent to about 49 mole percent bis phosphinosuccinic acid adducts and about 26 mole percent to about 35 mole percent oligomeric phosphinosuccinic acid adducts.

9 . The method of claim 2 , wherein the scale-inhibiting composition includes said copolymer and said oligomeric phosphosuccinic acid in a weight-to-weight ratio from about 5:1 to about 1:5.

10 . The method of claim 9 , wherein said ratio is about 1:2.

11 . The method of claim 1 , including adding from about 0.01 ppm to about 10,000 ppm of the scale-inhibiting composition, based on the saline aqueous source.

12 . The method of claim 1 , including adding from about 0.1 ppm to about 10 ppm of the scale-inhibiting composition, based on the saline aqueous source.

13 . The method of claim 1 , wherein the desalination process is selected from the group consisting of: a thermal desalination process and a membrane desalination process.

14 . The method of claim 1 , wherein the scale includes one or more constituents selected from the group consisting of: calcium, phosphate, magnesium, sulfate, bicarbonate, silicate, carbonate, iron, and combinations thereof.

15 . The method of claim 1 , including inhibiting formation and deposition of scale selected from the group consisting of: calcium sulfate, calcium carbonate, magnesium hydroxide, magnesium carbonate, and combinations thereof.

16 . The method of claim 1 , wherein the saline aqueous source includes seawater and including adding the scale-inhibiting composition to a seawater input stream of the desalination process.

17 . The method of claim 1 , including adding the scale-inhibiting composition to a recirculation brine of the desalination process.

18 . The method of claim 1 , wherein the desalination process produces a water temperature from about 80° C. to more than about 160° C. during the process.

19 . The method of claim 1 , wherein the scale-inhibiting composition includes scale inhibitors added as part of said composition, separately, sequentially, or simultaneously and selected from the group consisting of: polyacrylate, polycarboxylate, polymaleic acid, and combinations thereof.

20 . The method of claim 1 , including components selected from the group consisting of: one or more corrosion inhibitors; one or more other scale inhibitors; one or more fluorescent tracers; one or more water treatment polymers; one or more pH-controlling chemicals; and combinations thereof either as part of the scale-inhibiting composition or added separately, sequentially, or simultaneously with the scale-inhibiting composition.