What is 'scale formation' and what is its effect on boiler operation?

Scale formation refers to the accumulation of mineral deposits, primarily calcium and magnesium salts, that dissolve in water and precipitate on the heat exchange surfaces inside a boiler. This accumulation can significantly hinder heat transfer by acting as an insulating layer on metal surfaces. When scale forms, it disrupts the efficient flow of heat from the combustion gases to the water, leading to decreased boiler efficiency.

As scale builds up, it can also lead to overheating of the boiler tubes, which can cause damage and lead to costly repairs or reduced operational lifespan. The creation of hot spots and uneven heating can also result in increased fuel consumption as the system works harder to produce the desired steam output or water temperature. Thus, managing scale formation is critical for maintaining the efficiency and safety of boiler operations.

The other answers touch on different phenomena related to boiler operation but do not accurately describe the nature or consequences of scale formation.