The fouling of the cooling water system mainly comes from the following three aspects:
- Biological slime: also known as sludge or fouling, it is caused by the proliferation of microorganisms in the cooling water.
Bacteria usually live as single-cell or multi-cell colonies, and if conditions are suitable, 1.2 billion can be multiplied in one hour. Circulating cooling water is a special ecological environment. The water temperature is 25-40℃ and the conditions are just suitable for the growth of a variety of microorganisms. In addition, the concentration of circulating water increases the nutrient source and oxygen, which is conducive to the reproduction of microorganisms and results in biological sludge.
- Medium deposition: With the continuous evaporation of cooling water, the salt concentration in the water gradually increases. When the concentration is greater than the solubility, it will be deposited on the heat exchange surface. This type of scale is mainly CaCO3, CaSO4, CaSiO3, SiO2, etc.
3. Corrosion products: Air invades and corrodes metals during evaporative condenser shutdown. The corrosion products formed are FeO, Fe2O3, Fe3O4. During operation, the oxidants such as elemental oxygen, carbon dioxide, and high-value metal ions dissolved in the water corrode metals. The corrosion process is very complicated and the corrosion forms are various, but the final result is metal oxides or metal salts.
