Prepared Discussion of: Solubility and Thermodynamics of Sodium Phosphate Reaction Products Under Hideout Conditions in High-Pressure Boilers

摘要

Boiler water chemical control has two goals: to ensure the highest purity steam possible and to minimize waterside corrosion in the boiler. Control of waterside corrosion requires keeping the boiler water alkaline. A slightly elevated pH preserves the magnetite film that protects the boiler tubes from additional corrosion, and the alkalinity buffers the boiler water against pH depressions caused by acid forming contaminants. In the past, there were two phosphate treatment programs that were available for boilers operating above 1800 psig, congruent and coordinated phosphate treatment. Becaused of the work done by researchers like the authors to increase the understanding of phosphate hideout, Equilibrium Phosphate Treatment was developed and added to our boiler water treatment options. Equilibrium Phosphate Treatment recognizes that chemical reactions occurring in the boiler make the relatively high phosphate limits associated with coordinated and congruent phosphate control impractical, if not impossible, to maintain.