Anti-scaling treatment of heat exchangers

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Overview: After the heat exchanger has been running for a certain period of time, a layer of white scale will adhere to the inner and outer walls of the heat exchanger. The main reason for the formation of scale is that the water contains calcium and magnesium salts with low solubility. These salts have common characteristics. Their solubility decreases as the water temperature increases, and they become intolerable salts. The existence of this salt will have the following consequences for the heat exchanger.: 1. The thermal conductivity of scale is very poor. It is 30 to 50 times smaller than the thermal conductivity of steel. The presence of scale will deteriorate the heat transfer of the heating surface, thus preventing the heat transfer surface from reaching the ideal temperature drop. According to relevant information, experiments show that if scale is 1mm thick, the efficiency of the heat exchanger will be reduced by about 10%. 2. Scale adheres to the heat transfer surface and is difficult to remove, which increases maintenance costs. It not only consumes manpower and material resources, but also damages the heating surface and reduces the life of the heat exchanger. 3. After scale is generated, it will reduce the flow cross-section inside and outside the heat transfer surface, and increase the flow resistance of the circulating water inside and outside the heat transfer surface. In severe cases, the flow cross-section will be very small or even completely blocked, which will prevent the heat exchanger from operating normally. In order to prevent the above consequences, current design units or operating units often use methods such as dosing and softening treatment, magnetization and ion rod anti-scaling treatment, and sodium ion exchange treatment. In order to facilitate everyone's further understanding of these softening treatment methods, the principles, formulas and operation methods of these treatment methods will be introduced below. one. Medicinal softening treatment Medicinal softening treatment has the characteristics of simple method, high efficiency, good economy and does not require special water production equipment. It is a highly practical anti-scale water treatment method. According to the different methods of dosing, there are two types: corrective agent treatment and anti-scaling treatment. 2. .Magnetized anti-scaling treatment The principle of magnetized anti-scaling treatment is to utilize the polarity of water molecules, that is, water molecules are covalently combined. Single molecules of water polymerize into bimolecular associations (H2O)2 or multi-molecular associations (H2O)n due to the effects of polarity and hydrogen bonding. .When the water flow passes through a high-intensity magnetic field, under the action of the multi-molecule associations in the water and the ion magnetic field, the originally scattered multi-ion associations are disassembled into single or short-bond associations. They vertically cut the magnetic field lines of the external magnetic field at a certain speed to generate an induced current. Therefore, each ion establishes a new magnetic field in the same direction as the external magnetic field, and adjacent polar ion molecules compress and attract each other in an orderly manner, which leads to changes in crystallization conditions. The formed crystals are very loose, have poor compression and tensile resistance, and are very brittle. Their cohesion and adhesion are also very weak, and they are not easy to adhere to the heated surface to form scale. 3. Ion rod anti-scale water treatment Ion rod anti-scale water treatment is a new and advanced water treatment equipment. It is a patented product in the United States in 1987 and was introduced by Changsha York Water Treatment Company. It is used in hot water circulation systems, central air conditioning systems, and circulating cooling water systems, and has achieved satisfactory anti-scaling effects. It is a promising new water treatment equipment, especially when applied to heat exchangers, the effect will be more significant. Four. Sodium ion exchange softening treatment.