What chemical is commonly added to feedwater to remove oxygen?

Sodium sulfite is commonly added to feedwater in boiler systems to remove oxygen, a process known as oxygen scavenging. Oxygen can cause severe corrosion within boiler systems, leading to damage and reduced efficiency. When sodium sulfite is introduced into the feedwater, it reacts with dissolved oxygen, effectively neutralizing it and forming sodium sulfate, which is generally non-harmful to boiler operation.

This treatment is essential because it helps maintain the integrity of the boiler by preventing rust and other forms of corrosion that can occur when oxygen is present, thereby enhancing the longevity and safety of the boiler. The choice of sodium sulfite is particularly suitable due to its effectiveness and relative cost-effectiveness compared to other chemicals.

In contrast, sodium chloride (table salt) does not serve this purpose and can actually increase the risk of scale and corrosion when introduced into the boiler environment. Sodium carbonate is primarily used to manage pH levels in water, and calcium sulfate is more commonly associated with water hardness issues rather than oxygen removal. Hence, sodium sulfite is the go-to chemical for this specific function in feedwater treatment.