Why do high pressure boilers need to use ultrapure water?

Due to the different working pressure of the boiler, the water quality requirements and control methods are different. The higher the working pressure of the boiler, the higher the requirements for water quality and the stricter the control. The purpose of water quality control is to prevent scaling and corrosion in the boiler and its auxiliary water and steam systems, ensure the steam quality and the safe operation of the steam turbine, and reduce the pollution loss of the boiler and improve the economic benefits under the above conditions.

Low-pressure boiler is generally used soft water as make-up water; Medium-pressure boiler and some high-pressure boilers, demineralized water after dealkalization, desilication, desalting and sodium ion exchange (medium-pressure boiler) is usually used as make-up water, while phosphate treatment is mainly used in the boiler. For high pressure and subcritical boilers, chemical demineralized water is generally used for make-up, while phosphate treatment or volatile treatment is used in the boiler. Volatility treatment must be adopted for once-through boiler. In addition, the regulation of dissolved oxygen, salt content of boiler water, SiO2 and pH value in feedwater treatment is also more stringent due to the increase of boiler pressure.