Patent ID: 6929749

Claim:
A method for controlling silica or silicate scale formation in an aqueous cooling water system with silica contributed by source water, comprising the steps: a) removing hardness ions from said source water fed to said system; b) controlling the conductivity of the aqueous system water such that said aqueous system water possesses a conductivity from approximately 10,000 to 150,000 μmhos, wherein said aqueous system water contains soluble SiO 2 in excess of 200 mg/L; c) elevating and maintaining the pH of said aqueous system water such that said aqueous system water possesses a pH of approximately 9.0 or greater; and d) providing a metallic heat transfer surface in said system and cyclically contacting said aqueous system water thereabout, wherein said pH increases the solubility of said silica and controls silica or silicate scale formation on said metallic heat transfer surface.