A qualified boiler water treatment agent must effectively play the role of scale and corrosion inhibition. Scale inhibition mainly refers to the scale inhibition of the boiler body, and the objects of corrosion inhibition include the boiler body and the pipes through which the steam passes, heat exchangers and condensate pipes.
Ca2+ and Mg2+ are the main fouling ions, and most of the boilers currently used in the market are equipped with ion exchangers to remove them. However, the concentration of other soluble salts in the water increases due to the concentration and evaporation of the pot water, and there is still the possibility of scaling beyond its solubility. Especially in high-temperature parts such as smoke pipes, due to the rapid vaporization of water, it is likely that certain salts will crystallize due to excessive local concentration. This is why many boilers that use softened water still foul. Although this phenomenon can be alleviated by increasing the amount of pollutant discharge, on the one hand, it wastes a lot of energy. On the other hand, due to the increase in the amount of pollutant discharge, the alkalinity of the boiler water is often lower than the lower limit of the national standard, which accelerates the rate of corrosion. . Therefore, it is very necessary to take appropriate anti-scale measures for the pot water.
Dissolved oxygen in water is the main factor causing boiler corrosion. Due to the high temperature in the pot, dissolved oxygen reacts quickly with iron. For boilers without deaerators, the use of chemical deaeration measures is indispensable. For boilers with deaerators, the current deaerators cannot completely remove oxygen, especially for some non-continuously operating boilers. When the furnace is just opened, the thermal deaerator is almost ineffective, so it is necessary to take chemical deaeration as a remedy.
Another major factor causing boiler corrosion is Fe3+. Most office buildings, hotels, etc. now use closed heating systems, and the condensate reuse can account for about 80% of the boiler’s make-up water. If the steam pipes, condensate pipes, heat exchangers and other parts do not have necessary corrosion inhibition measures, the pipe surface The iron dissolved in it will enter the condensate. Because Fe3+ has strong oxidizing properties, it can greatly accelerate the corrosion rate of the boiler.
After entering the boiler, the CO2 gas in the boiler feed water escapes from the water due to heat, enters the heat exchanger along with the steam, and re-dissolves in the condensate water, making the water acidic. Under acidic conditions, the corrosion of iron is greatly accelerated, and a large amount of iron is dissolved in the condensate, and sometimes the condensate has to be drained. Due to the high temperature of the condensate, this will inevitably cause a lot of waste of energy.