Cooling water scale and corrosion inhibition

Abstract A methods for inhibiting silica scale formation and corrosion in aqueous systems where soluble silica (SiO2) can be maintained at residuals below 200 mg/L, but more preferably maintained at greater than 200 mg/L as SiO2, without silica scale and with control of deposition of source water silica accumulations as high as 4000 mg/L (cycled accumulation) from evaporation and concentration of source water. The methods of the present invention also provide highly effective inhibition of corrosion for carbon steel, copper, copper alloy, and stainless steel alloys. The methods of the present invention comprise pretreatment removal of hardness ions from the makeup source water, maintenance of electrical conductivity, and elevating the pH level of the aqueous environment. Thereafter, specified water chemistry residual ranges are maintained in the aqueous system to achieve inhibition of scale and corrosion. Other References   The NALCO Water Handbook; 1979; Chapter 3, p. 14 and 16. Drew; Principles of Industrial Water Treatment; Sixth Edition; 1983; Chapter 3, pp. 43 and 64. Boffardi, Bennett P., PhD; Calgon Internal Publication; 1988; Chapter 4; pp. 30-31. Strumm, et al.; “Formation of Polysilicates as Determined by Coagulation Effects”; Environmental Science and Technology; 1967; Vo. 1, 221-227. Rozenfeld, I.L.; “Corrosion Inhibitors”; 1981; McGraw Hill; 171-174. Drew; Principles of Industrial Water Treatment; Sixth Edition; 1983; Chapter3, pp. 43 and 64.

Field of Search

159/47.1 , PROCESSES 159/47.3 , Involving waste liquid 203/10 , WATER PURIFICATION ONLY 210/652 , Hyperfiltration (e.g., reverse osmosis, etc.) 210/687 , Calcium or magnesium (e.g., hardness, water softening, etc.) 210/696 , Preventing, decreasing, or delaying precipitation, coagulation or flocculation 210/697 , Utilizing inorganic phosphorus agent 210/698 , Utilizing organic agent 210/699 , Phosphorus containing 210/700 , Nitrogen containing 210/701 , Acrylic polymer 210/702 , Making an insoluable substance or accreting suspended constituents 210/743 , pH Sensing 210/746 , Electrical property sensing 210/748 , Utilizing electrical or wave energy (directly applied to liquid or material being treated) 210/96.1 , CONSTITUENT MIXTURE VARIATION RESPONSIVE 422/13 Aqueous alkali environment (i.e., pH £ 4.1)

US Patent References

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