What is one disadvantage of using sodium sulphite in high pressure boilers?

Using sodium sulphite in high-pressure boilers can indeed lead to an increase in Total Dissolved Solids (TDS), which would necessitate blowdown. This is a key disadvantage because high TDS levels can affect the boiler's efficiency and performance.

Sodium sulphite is commonly used as an oxygen scavenger to prevent corrosion, particularly in feedwater. While it effectively reduces oxygen levels to minimize corrosion risks, it also adds to the overall dissolved solids in the water. Over time, these dissolved solids can accumulate, leading to scaling and the potential need for regular blowdown to maintain water quality. The blowdown process removes a portion of water to lower TDS levels, which, while necessary, can lead to energy loss and water waste.

Understanding this dynamic is crucial for managing boiler operation effectively, as it highlights the balance needed between using chemicals for water treatment and maintaining operational efficiency through proper control of TDS levels.