Method of inhibiting scale formation and deposition in desalination systems

Abstract

This invention relates to an improved method of inhibiting corrosion and calcium sulfate and calcium carbonate scaling in thermal and membrane desalination processes. The method includes adding a composition having an acrylic acid 2-acrylamido-2-methylpropyl sulfonic acid copolymer, optionally combined with an oligomeric phosphinosuccinic acid to seawater or recirculation brine in a desalting process to produce water for drinking and industrial applications. The method also includes adding a composition including mono, bis, and oligomeric phosphinosuccinic acid adducts to the desalting process.

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.