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US 4,913,822 AGranted
Method for control of scale and inhibition of corrosion in cooling water systems
AssigneeBetz Laboratories, Inc.
InventorsFu Chen, J. Michael Brown
Life of this patent
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Abstract
A method for inhibiting scale deposition and the corrosion of metal surfaces in a cooling water system. It comprises a water soluble copolymer consisting of moities of acrylic acid and monohydroxylated alkyl allyl ether, a phosphonate compound, a water soluble zinc salt and, optionally, an azole compound, and/or a water soluble molybdate salt.
Claims7
A method for inhibiting corrosion and mineral deposition including calcium carbonate in a cooling water system comprising
- (a) maintaining the pH of said cooling water system at a minimum of 8;
- (b) maintaining said cooling water system in a state of super saturation with respect to calcium carbonate and operating said cooling water system at a Langelier Saturation Index maintained at a minimum level of 0.8;
- (c) adding to said cooling water system, about 0.1-500 ppm of a water soluble polymeric corrosion inhibitor and deposition control agent, having repeat units x and y comprising the structure:
- ##STR4## wherein R1 and R3 are independently hydrogen or lower alkyl group (C1-C3);
- R2 is OH or OM;
- M is a water soluble cation;
- R4 is 2 hydroxypropyl the molar ratio of said repeat units x:y is from about 8:1 to about 1:5;
- (d) adding to said cooling water system a water soluble zinc salt at a concentration of from about 0.1-15 ppm;
- (e) adding to said cooling water system a water soluble phosphonate compound at a concentration of about 6 ppm.
6 more elements
Dependencies are inferred from the claim text.