Views:14 Author:Site Editor Publish Time: 2017-04-13 Origin:Site
The meaning of calcium and magnesium scale
In calcium and magnesium scale, the content of calcium, magnesium salt is often large, some about 90%. And these scale can be divided into calcium scale CaCO3, CaS04 · 2H20, CaSiO3 · 5Si02 · H2O and magnesium scale Mg (OH) 2, Mg3 (P04) 2 and so on.
The formation of these scale
The main reason for the formation of calcium and magnesium is that the ion concentration of calcium and magnesium salts in the water exceeds the solubility product, causing these salts to crystallize from the solution and attach to the heating surface to form scale.
The reason for the ion of calcium and magnesium salts in water exceeds the solubility is as followed:
1. With the increase of water temperature, the solubility of some calcium and magnesium salts in water decreased.
2. When the water is continuously heated, the salt is gradually concentrated.
3. In the process of water heating and evaporation, some calcium and magnesium salts in water are "thermally decomposed" and become insoluble in water.
How to prevent it ?
1. Completely remove the hardness of make-up water .
2. Ensure the condenser tightly closed. If the condensers leak, cooling water will get into the condensate, which is an important reason for producing calcium, magnesium scale in the furnace. When the condensate hardness is increased, people should quickly identify the cause and eliminate in time.
3. There is no hardness in the condensate water.
4. Use phosphate salts as treatment for the scale in drum boiler.