At what residual level of sodium sulphite is sufficient to control oxygen variations in the boiler?

The optimal residual level of sodium sulphite for controlling oxygen variations in a boiler is critical as it plays a significant role in preventing oxygen corrosion, which can lead to severe damage over time. Sodium sulphite acts as an oxygen scavenger; it reacts with dissolved oxygen in water to form sodium sulfate, thereby lowering the oxygen concentration within the boiler water.

Maintaining a sodium sulphite concentration in the range of 10-15 mg/L is generally considered sufficient for effectively managing the levels of dissolved oxygen in the boiler. This concentration strikes a balance between providing enough scavenging capability while avoiding excessive chemical usage, which could lead to other issues, such as increased solids concentration in the boiler water.

The need for precise control is essential because too low a level may not adequately protect against corrosion, while too high a level could create undesirable operational repercussions in the system. Hence, the 10-15 mg/L range is widely accepted as the optimal choice for maintaining boiler integrity and ensuring longevity in equipment performance.