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Maintenance precautions for plate heat exchangers
Release time:
2022-01-10
Precautions for maintenance of plate heat exchanger?
Plate heat exchangers are an important part of heat exchange technology in process industry equipment. The elastic gasket that seals between each plate heat sink is a vulnerable part, and it is also a part that is easy to age under natural conditions. Its service life has an important impact on the service life of the plate heat exchanger. If these seals heat harden and lose their original elasticity, this can cause the heat exchanger to fail to function properly. The following factors have a significant impact on the service life of elastomeric gaskets:
1. The working mode of the heat exchanger (continuous or discontinuous);
2. The corrosiveness of the heat dissipation medium and the cleaning agent used;
3. Working temperature;
4. Working pressure;
5. Due to excessive pressure and unbalanced pressure, the stress of the elastic gasket is large;
6. Natural aging. The softening of the elastic gasket is related to pressure and temperature. When the gasket loses its elasticity, the heat exchanger will leak.
In some products, in order to solve the dripping phenomenon caused by the aging of the gasket, it is allowed to adjust the sealing performance of the heat exchanger, that is, tighten the bolts of the combined plate heat exchanger again, and adjust the elastic gasket between each heat exchanger The compression force solves the problem of dripping. On the nameplate of the heat exchanger with this function, the allowable maximum and minimum stresses are generally given. For a new heat exchanger plate set, a small allowable stress should be used for connection and fixation. Depending on the number of heat exchanger fins in each group, the tightening force of the heat exchanger can be adjusted once or several times. When tightening each time, the nut can be screwed in 3mm, and the stress of the adjusting fins should always be paid attention to during the tightening process, and , it is only allowed to adjust the tightening force at room temperature for heat exchangers without working pressure to prevent dripping.
For plate heat exchangers that do not specify the stress adjustment range on the nameplate, the stress value is generally given in the part drawing. When tightening this type of plate heat exchanger, the tightening torque should not be lower than the value specified in the drawing in any case. Because it is related to the assembly quality and assembly deformation of the plate heat exchanger. When the tightening torque reaches the specified value, the elastic gasket can be replaced in a planned way. For plate heat exchangers used in important production equipment and corrosive media, it is recommended to have a spare set of seals. When the warehouse temperature is 18°C, the seals of the plate heat exchanger can be stored for about 3 years in transparent plastic packaging.
In principle, the fixation of seals is divided into two categories: adhesive fixation and non-adhesive fixation. The shape of the gasket should be consistent with the shape of the seal of the plate heat exchanger. It must be pointed out that the adhesive fixing method does not have any effect on the sealing function.
1. Non-adhesive seal
(1) Alignment: Put the sealing ring in place
(2) Putting in: Make the sealing ring enter the sealing groove correctly
(3) Compression: In the sealing groove, there is a groove-shaped structure with a gradually decreasing cross-section, so that the sealing ring can be positioned correctly
2. Adhesive seal According to the purpose of use of the gasket and the quality requirements of the seal, blended sealants and non-blended sealants from different manufacturers can be used. Before bonding, the residual adhesive and residual gasket on the bonding surface should be thoroughly removed by steam flow. For the bonding of the blended sealant, the residual adhesive and residual gasket on the joint surface of the plate heat exchanger must be burned out with fire. When bonding in large quantities, a liquid nitrogen pool for freezing seals should be prepared, and a heating furnace for drying treatment of plate heat exchangers with gaskets should be prepared. The heating temperature should reach 160 ° C. If possible, plate heat exchangers should be used. The heat exchanger is chemically cleaned to ensure that the gaskets of the adhesive parts remaining in the joint surface of the plate heat exchanger are completely removed.
You can know whether the gasket is installed correctly according to the observation hole of the honeycomb of the plate heat exchanger.
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