(1) Scale: As the circulating water continuously evaporates during the cooling process, the salt concentration in the water is continuously increased, and it exceeds the solubility of some salts to precipitate. Common scales include calcium carbonate, calcium phosphate, and magnesium silicate. The texture of scale is relatively dense, which greatly reduces the heat transfer efficiency. The thickness of 0.6 mm scale reduces the heat transfer coefficient by 20%.
(2) Dirt: Dirt is mainly composed of organic matter, microbial colonies and secretions, sediment, dust, etc. in water. The texture of the fouling is not only reducing the heat transfer efficiency but also causing corrosion under the fouling and shortening the service life of the equipment.
(3) Corrosion: Corrosion of circulating water to heat exchange equipment is mainly galvanic corrosion, which is caused by equipment manufacturing defects, sufficient oxygen in water, corrosive ions (Cl-, Fe2 +, Cu2 +) in water and mucus secreted by microorganisms. The consequences of corrosion, such as the generated dirt, are very serious. Even if the heat exchanger and water pipeline equipment are scrapped, they will not be controlled for a very short time.
(4) Microbial slime: Because the circulating water has sufficient oxygen, suitable temperature and rich conditions, it is very suitable for the growth and reproduction of microorganisms. If it is not controlled in time, it will cause rapid deterioration of water quality, odor, blackening, and a large number of cooling towers. Sludge deposits and even blockages, cooling effect is greatly reduced, and equipment corrosion is intensified. Therefore, circulating water treatment must control the reproduction of microorganisms.