1, to the state of ions or molecules dissolved in water of harmful impurities

A and calcium salts in the water main components have the Ca (HCO3) 2, CaCl2 and CaSO4, CaSiO3, etc. Calcium salt is the main component of fouling in heat exchanger. CaSO4 is a germplasm hard, crystallization fine scale, loose structure, adhesion, is a relatively loose sludge, separated from water by liquid, even attached on the heating surface is easy to clean.

B, magnesium salt in the water of the main components such as Mg (HCO3), MgCl2 and MgSO4. Magnesium dissolved in the water, after generation after thermal decomposition of Mg (OH) 2 precipitate, Mg (OH) 2 is also a sludge type scale. MgCl2, MgSO4 dissolved in the water, the water pH < 7, due to the corrosion of acidic hydrolysis can cause metal wall.

C, sodium main components such as NaCl and Na2SO4, NaHCO3. NaCl don't generate the scale, but there is a free oxygen in the water, will accelerate the corrosion of the metal wall; Na2SO4 content is too high, will be after the evaporator on the attachment of salt, influence the safe operation; The NaHCO3 in the water under the action of temperature and pressure, decompose the NaCO3, NaOH, CO2, can make the metal grain damage.

2, the dangers of dissolved oxygen gas

Some of the reasons for corrosion to occur in the heat exchanger, but corrosion is most serious, the fastest, or oxygen. In atomic order sheet, the potential of iron on hydrogen in neutral water contains no oxygen, system lose electrons into bivalent iron atoms on the surface of the metal ions (Fe - 2 e - Fe2 +), Fe2 + ion and OH - ions in the water under the action of electrostatic attraction combining [Fe2 + + 2 OH - - Fe (OH) 2], and set up in the water balance of the following:

Fe2 + + 2 OH - = Fe (OH) 2

When the water, in the presence of Fe (OH) 2 be further oxidized to insoluble ferric hydroxide precipitation:

4 fe (OH) 2 + O2 + 2 h2o - 4 fe (OH) 3 left

Deposited by Fe (OH) 3, around the anode iron ions into aqueous solution, the accelerated corrosion.

Can be seen from the above reaction, water and oxygen are the necessary conditions of corrosion, anode area is subject to corrosion, cathode area is the part of the corrosion products gathering. When corrosion in the metal surface basic evenly, the corrosion speed is not soon, so harmless, this kind of corrosion is called the general corrosion. When corrosion to focus on certain parts of the metal surface, it is called a local corrosion. Local corrosion speed fast, easy to wear, rust corrosion pit in the heat exchanger is a common local corrosion, so very dangerous.

3, exist in the colloidal state in the impurities to the harm of heat exchanger

Is a main composition, iron compounds Fe2O3, it will generate iron scale. When the water is large, contain iron compounds often yellow.

B, microorganism due to air conditioning cooling circulating water temperature, dissolved oxygen and nutrients to microbial provides for breeding conditions, microbes will propagate infested. Microbes from soil and air, cooling water temperature is high, through the cooling tower aeration, oxygen content increases, often adding phosphate in water such as potions, microbial fertilizer, cooling tower and mostly in open air, sunlight for algae growth, microbial breeding not only blocking plate channels, sometimes blocking line, still can make the metal corrosion.

C, cooling circulating water in the sludge, the sludge from the dust in the air, and complement the suspended solids in the water. Air and water in the process of convection exchange, a large number of air circulating water spray in the tower, the dust in the water, gradually deposit in heat exchanger at low velocity of flow.

D, sticky dirty mainly is secretion of the microbial debris and bacterium and algae in the water and sediment, corrosion products, bonding, and they are attached to the heat exchanger wall often, produce all kinds of organic acid, the acid can also cause corrosion.

Heat exchanger fluid water quality requirement is very important, therefore, in the operation and management, should strengthen the attention, equipped with the necessary antiscale, anticorrosive equipment, prolong the service life of equipment.