Patent ID: 8057738

Claim:
A method for controlling precipitation of polyvalent metal ion salts that form deposits on heat transfer surfaces in an aqueous water system and concurrently precipitate silica contributed by source water, the method comprising the steps: a) removing polyvalent metal (PVM) ions from said source water; b) controlling the monovalent metal (MVM) ion concentration of the aqueous system water such that said aqueous system water possesses an MVM ion concentration that exceeds the soluble silica concentration; c) elevating and maintaining the pH of said aqueous system water such that said aqueous system water possesses a pH of approximately 7.0 or greater; and d) concentrating said source water and its natural silica content by evaporation of makeup water in an aqueous system where the system water temperature is higher than the makeup water temperature, and said system water is circulated in contact with heat transfer surfaces that elevate such portion of water to even higher temperatures.