1. Impurities dissolved in water in an ionic or molecular state
Calcium salts: The main constituents in water are Ca(HCO3)2, CaCl2, CaSO4, CaSiO3 and the like. Calcium salts are the main component of the Heat Exchanger fouling.
Magnesium salt: The main constituents in water are Mg(HCO3)2, MgCl2, MgSO4 and the like. After the magnesium is dissolved in water, it is precipitated by heat to form a precipitate of Mg(OH)2, which constitutes sludge or scale.
Sodium salt: mainly composed of NaCl, Na2SO4, NaHCO3, and the like.
NaCl does not generate scale, but free oxygen in the water will accelerate the corrosion of the metal wall; if the content of Na2SO4 is too high, salt will be formed, which will affect the safe operation; NaHCO3 in water will decompose NaCO3, NaOH and CO3 under the action of temperature and pressure. , damage to the metal grains.
2. Impurities present in colloidal state
Iron compound: The main component is Fe2O3, which produces iron scale.
Microorganisms: Microorganisms will multiply in large quantities because the water temperature, dissolved oxygen, etc. of the circulating water provide conditions for the microorganisms to be propagated. When the temperature of the circulating water is high, the addition of a phosphate or the like to the water is just a nutrient for the microorganisms. The propagation of the microorganisms not only blocks the passage of the sheets, but also blocks the tubes and corrodes the metal.
Sludge: The sludge in the circulating water is cooled from the dust in the air and the suspended matter in the replenishing water, and is gradually deposited in the heat exchanger with a lower flow rate.
Viscosity: It is mainly caused by the secretion of microorganisms and the sediment, corrosion products and algae residues in the water, often attached to the wall of the heat exchanger.
