Why is boiler feedwater chemically treated?

Boiler feedwater is chemically treated primarily to prevent the formation of scale. Scale is the accumulation of mineral deposits that can build up on the heat transfer surfaces within a boiler. If not managed, this scale can drastically reduce the efficiency of heat transfer, leading to overheating of the boiler metals and ultimately causing damage to the system.

In order to effectively manage this risk, various chemicals are added to the feedwater to sequester minerals that could precipitate and form scale, particularly calcium and magnesium. Furthermore, when scale forms, it acts like an insulating layer on the boiler tubes, which can require more energy to produce the same amount of steam, thereby decreasing overall thermal efficiency. By preventing scale formation, the boiler operates more efficiently, utilizes energy more effectively, and has a longer lifespan due to reduced stress and damage to boiler components.

While enhancing thermal efficiency, preventing corrosion, and maintaining proper pH levels are important aspects of boiler operation and water treatment, the direct prevention of scale formation is critical for the immediate operational integrity and efficiency of the boiler.