Corrosion inhibitors for cooling water applications

Abstract

A new corrosion inhibitor composition containing a carboxylic acid and its water soluble salts with zinc can be used for corrosion inhibition on the carbon steel pipe and heat exchangers in industrial cooling water. This new composition of matter contains less carboxylic acid and Zn 2+ than previous formulations and still have >90% corrosion inhibition. It is disclosed that the synergistic effect of combining the carboxylic acid with very small amounts of Zn results in a product with good corrosion inhibition properties that is more environmentally friendly than the current common phosphonate corrosion inhibitors; particularly for use in cooling water applications.

1 . A method for preventing or mitigating corrosion in cooling water systems comprising treating the cooling water with an additive comprising a soluble zinc salt and a soluble carboxylic acid salt. 
     
     
         2 . The method of  claim 1  wherein the soluble zinc salt is selected from the group consisting of: zinc chloride, zinc bromide, zinc hydroxide, zinc carbonate, zinc borate, zinc nitrate, and combinations thereof. 
     
     
         3 . The method of  claim 2  wherein the soluble zinc salt is selected from the group consisting of: zinc chloride, zinc bromide, zinc hydroxide and combinations thereof. 
     
     
         4 . The method of  claim 1  wherein the soluble carboxylic acid salt is selected from the group consisting of a soluble gluconic acid salt, a soluble saccharic acid salt, and combinations thereof. 
     
     
         5 . The method of  claim 1  wherein the additive, when added to cooling water is present at a concentrations sufficient to provide from about 30 to about 300 ppm by weight carboxylic acid or its soluble salts. 
     
     
         6 . The method of  claim 5  wherein the additive, when added to cooling water is present at a concentrations sufficient to provide from about 30 to about 180 ppm by weight carboxylic acid or its soluble salts. 
     
     
         7 . The method of  claim 1  wherein the additive, when added to cooling water is present at a concentration sufficient to provide up to 10 ppm by weight of soluble zinc salts. 
     
     
         8 . The method of  claim 1  wherein the additive, when added to cooling water is present at a concentration sufficient to provide up to 4 ppm by weight of soluble zinc salts. 
     
     
         9 . The method of  claim 1  wherein the additive additionally comprises a composition selected from the group comprising: scale inhibitors, yellow metal corrosion inhibitors, dispersants, deodorants, biocides, dyes, and combinations thereof. 
     
     
         10 . A method for preventing or mitigating corrosion in cooling water comprising treating the cooling water with an additive comprising a soluble zinc salt and a compound selected from the group consisting of gluconic acid, saccharic acid, a water soluble gluconate salt, a water soluble saccharic acid salt, and combinations thereof. 
     
     
         11 . The method of  claim 9  wherein the water soluble saccharic acid salt is selected from the group consisting of its potassium salts, its calcium salts, and combinations thereof. 
     
     
         12 . The method of  claim 9  wherein the water soluble gluconate salt is its sodium salt. 
     
     
         13 . The method of  claim 9  wherein the additive, when added to cooling water is present at a concentrations sufficient to provide from about 30 to about 300 ppm by weight of gluconic acid, saccharic acid, a water soluble gluconate salt, a water soluble saccharic acid salt, and combinations thereof. 
     
     
         14 . The method of  claim 12  wherein the additive, when added to cooling water is present at a concentrations sufficient to provide from about 30 to about 180 ppm by weight of gluconic acid, saccharic acid, a water soluble gluconate salt, a water soluble saccharic acid salt, and combinations thereof. 
     
     
         15 . The method of  claim 9  wherein the additive additionally comprises a composition selected from the group comprising: scale inhibitors, yellow metal corrosion inhibitors, dispersants, deodorants, biocides, dyes, and combinations thereof. 
     
     
         16 . A method for preventing or mitigating corrosion in a cooling water system comprising treating the cooling water with an additive comprising a soluble zinc carboxylate. 
     
     
         17 . The method of  claim 14  wherein the soluble zinc carboxylate is present at a concentration of from 30 to about 300 ppm by weight. 
     
     
         18 . The method of  claim 14  wherein the additive additionally comprises a composition selected from the group comprising: scale inhibitors, yellow metal corrosion inhibitors, dispersants, deodorants, biocides, dyes, and combinations thereof. 
     
     
         19 . A method for preventing or mitigating corrosion in cooling water comprising treating the cooling water with an additive comprising a compound selected from the group consisting of zinc gluconate, the zinc salt of saccharic acid, and combinations thereof. 
     
     
         20 . The method of  claim 16  wherein the additive additionally comprises a composition selected from the group comprising: scale inhibitors, yellow metal corrosion inhibitors, dispersants, deodorants, biocides, dyes, and combinations thereof.