Sulfite Oxygen Scavenging

Definition

The deaeration reaction in which sulfite consumes dissolved oxygen to protect feedwater and boiler metal from corrosion.

Sulfite fed to the feedwater tank reacts with dissolved oxygen by SO3^2- + 1/2 O2 to SO4^2-, consuming residual sulfite to produce sulfate. The stoichiometric demand is roughly 7.9 mg of sulfite per 1 mg of dissolved oxygen, so when oxygen load triples the sulfite demand triples and any residual disappears if feed is unchanged. A lost sulfite residual is therefore often an oxygen-load problem, not a chemical-feed problem.

Related concepts

Chemical Demand · Dissolved Oxygen · Boiler Feedwater

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Part of The Blueprint of Water · 🧪 chemistry