The plate heat exchanger will have problems during use and maintenance, especially its seals, to see if it is loose. The small series will introduce the precautions for the maintenance of the plate heat exchanger:
Plate heat exchangers are an important part of heat exchange technology in process industry equipment. Elastomeric seals (see Table 1) that seal between the various plate fins are a consumable part and are also an easily aged part under natural conditions. Its service life has an important influence on the service life of the plate heat exchanger. If these seals heat harden and lose their original elasticity, the heat exchanger will not work properly.
The softening of the elastomeric 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, the sealing performance adjustment of the heat exchanger is allowed, that is, the bolts of the combined plate heat exchanger are tightened again, and the elastic gasket between the heat exchangers is adjusted. The pressing force solves the problem of dripping. On the nameplate of a heat exchanger with this function, the maximum and minimum stresses are generally given. For new heat exchanger sets, the minimum allowable stress should be used for connection fixation. Depending on the number of heat exchanger plates per group, the tightening force of the heat exchanger can be adjusted one or more times. Each time the Screw is tightened, the nut can be screwed in 3mm, and the stress of the adjusting piece is always paid attention to during the tightening process, and Only allow the heat exchanger without working pressure to adjust the tightening force at room temperature to prevent dripping.
For plate heat exchangers that do not have a stress adjustment range on the nameplate, the stress values ​​are generally given in the part drawing. When tightening such plate heat exchangers, the tightening torque should not be lower than the value specified in the drawings. 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 seal can be replaced in a planned manner. For plate heat exchangers used in critical production equipment and corrosive media, a spare seal is recommended. When the warehouse temperature is 18 °C, the seal of the plate heat exchanger can be stored for about 3 years in a transparent plastic package.
Seal fixing
In principle, the fixing of the sealing member is divided into two categories: adhesive fixing and non-bonding fixing. The shape of the gasket should be consistent with the shape of the plate heat exchanger seal. It must be pointed out that the adhesive fixing method does not have any effect on the sealing function.
Non-bonded seal
Alignment: Place the seal in place
Put in: make the sealing ring enter the sealing groove correctly
Compression: In the sealing groove, there is a trough structure with a gradually decreasing cross section to properly position the sealing ring
Adhesive seal
Depending on the purpose of the gasket and the quality of the seal, blending sealants and non-harmonic sealants from different manufacturers can be used. Before bonding, a vapor stream should be used to thoroughly remove the adhesive remaining on the bonding surface and the residual gasket. For blended sealant bonding, the residual adhesive and residual gasket on the bonding surface of the plate heat exchanger must be burned out. When bonding in large quantities, the liquid nitrogen tank of the frozen seal should be prepared, and the heating furnace for drying the plate heat exchanger with gasket should be prepared. The heating temperature should be 160 ° C. If conditions permit, the plate should be prepared. The heat exchanger is chemically cleaned to ensure complete removal of the gasket of the bond remaining in the bonded surface of the plate heat exchanger.
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Label: Repair and maintenance of plate heat exchanger
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