Maintenance of plate heat exchanger

Release time:2017-05-22 views:933

    Even the plate heat exchanger will have problems in the course of one year, requiring repairs, especially its seals, to see if it has loosened. This paper introduces the points for attention in the maintenance of plate heat exchangers.

    Plate heat exchanger is an important component of heat exchange technology in equipment of process industry. An elastomeric gasket (see Table 1) sealed between each plate is a vulnerable part and is also an easy ageing part under natural conditions. Its service life has an important influence on the service life of plate heat exchangers. If the seals are hardened and the original elasticity is lost, the heat exchanger will not work properly.

     The following factors have an important bearing on the service life of an elastic gasket:

        How does the heat exchanger work (continuous or discontinuous)

        The heat dissipation of the medium and the use of detergents are corrosive

        Maximum operating temperature

       Maximum work pressure

       The stress of the elastomeric gasket is greater due to excessive pressure and uneven pressure

       Natural aging

    The softening of an elastic gasket is related to pressure and temperature. When the gasket loses its elasticity, the heat exchanger will drip. In some of the products, in order to solve the leakage phenomenon caused by the aging of the gasket, allowing the heat exchanger sealing performance adjustment, namely again combined heat exchanger tightening bolt, pressing force adjusting each heat exchanger between the elastic sealing pad, solve the leakage problem. The maximum and minimum stresses are allowed on the plates of heat exchangers with this function. For the new heat exchanger sheet group, the minimum allowable stress shall be used to secure the connection. As each film heat exchanger number can be one or more times to adjust the heat exchanger tightening force, every time when tightening the nut can be screwed in the 3mm, and in the process of tightening the adjustment sheet always pay attention to the stress, and is only allowed to heat exchanger without working pressure, tightening force under the condition of room temperature adjustment, prevent leakage.

    There is no heat exchanger produced the stress range of adjustment in the nameplate, general stress values are given in the drawing, in this kind of screw plate heat exchanger, tightening torque in any case should not be less than the numerical drawing, because the assembly quality, assembly and deformation of plate heat exchanger. When the tightening torque reaches the required numerical value, the elastomeric gasket can be replaced by a planned method. There is a spare set of seals for plate heat exchangers used in important production equipment and corrosive medium. When the warehouse temperature is 18 degrees centigrade, the seal of the plate heat exchanger can be stored for about 3 years in the transparent plastic package.

     Fixed seal

    In principle, the seals are divided into two categories: bonding, fixing and non bonding. The shape of the gasket shall be consistent with the shape of the plate seal. It must be pointed out that the bonding method does not have any effect on the sealing function.

    Non-adhesive sealing
        ■ Alignment: place the sealing ring in place
        ■ Put in: make the sealing ring enter the sealing groove properly
 Compression: in the sealing groove, there is a groove structure with a decreasing cross section so that the sealing ring can be correctly positioned

     Adhesive seal
    According to the use purpose and seal quality of the seal pad, the mixed sealant and non-harmonizing sealant can be used for different manufacturers. Prior to adhesion, steam airflow should be used to thoroughly remove residual adhesives and residual gaskets. The residual adhesive and residual seal on the surface of the plate heat exchanger must be used with fire. Adhesive in large quantities, should be ready to seal the liquid nitrogen pools, frozen ready for plate heat exchanger with gasket is dry processing furnace, heating temperature should be up to 160 ℃, if there are conditions, dealing with the plate heat exchanger for chemical cleaning, to ensure that thoroughly remove residues in the plate heat exchanger in combination with surface adhesion of the gasket.


    It is possible to know whether the sealing pad is installed correctly according to the observation hole of the bee room of the plate heat exchanger.

A chemical cleanser should be used for the combination of plate heat exchanger (e.g., acetone). Also, chemical cleaners must be used to remove the softeners and adhesion coatings that are adhered to the sealing gaskets. Apply the adhesive to the middle of each bonding surface. Depending on the width of the seal pad, the width of the binder is about the width of a match, and then apply the adhesive to the whole surface of the adhesive to make full use of the whole bonding surface. Depending on the type of binder for certain ventilation drying time, and then into the seal, will each plate heat exchanger stacked together, tighten the screw tighten, or stacked with heavy pressure on the heat exchanger group. Depending on the type of adhesive, the hardening time is approximately 8 ~ 20 hours. For harmonic adhesives, screw tightening and heating hardening are necessary.

    Please see table 2 for the advantages and disadvantages of adhesion and non-adhesive sealing.

    Clean and clean
Usually, people is through the process equipment of cold sports drip drip to discover in the process of cooling or parking heat exchanger seal failure, some of the plate heat exchanger has the function of secondary regulation allowed in case of a small drips to tighten heat exchanger tablet group. In order to increase the stress of each sealing pad, the leakage can be solved within a short time. In the newly assembled heat exchanger, the larger combination length can be used, then the plate heat exchanger should be tightened and the length of the combined length will be used. The maximum combined length and minimum combinations are generally available in the heat exchanger's nameplate. It should be noted that no less than the minimum combination length. When the combined heat exchanger reaches the minimum size of the minimum combined length, the seal must be changed.
    AKK industrial service co., LTD. Is a professional enterprise for the debugging of plate heat exchangers. It provides maintenance services for the plate heat exchangers of various process enterprises. In cooperation with different process industry users, AKK company developed its own unique, effective and low cost of heat exchanger, heat exchanger, cleaning, testing and the replacement of the rubber seal technology.

The main steps of the replacement of rubber parts are:

    1. Test and test of return performance. Check the wall thickness of heat exchanger and pipe in case of corrosion.
    2, remove aging seals, according to the different dirt, with Haug chemical co., LTD. Jointly developed for chemical cleaning, acid - alkali cleaning pool was cleaning the surface of the parts are not subject to the corrosion of chemical medium (such as gasoline).
    3. After chemical cleaning, the chemical media of the surface of the plate heat exchanger should be completely removed with high pressure blowing device.
    4. The heat exchanger plate is coated with fluorescence tester, and the small cracks and corrosion holes are examined under the irradiation of ultraviolet light, and the cleaning is cleaned again. In addition, the condition of the seal groove should be examined, and the dressing should be done when necessary.
    5, For bonding type gasket, will completely remove residual material, using mixed type adhesive glue to bonding and recombination of the heat exchanger group in special fixture clamping, adhesive curing; Heat preservation in an insulated furnace to achieve the best bonding effect. For non-bonded gaskets, different devices are used to fix the gasket in the radiator.
   6. Check the bonding position and quality of each plate type heat sink, classify according to the installation sequence, and then carefully assemble the panel.
    According to the above method, the performance of plate heat exchanger will be as new as new.
In process industrial equipment, plate heat exchanger is a device with high safety requirement. When the seal pad is damaged, the leakage is visible. The heat exchanger and heat exchanger can have a slight leakage at the beginning. In the process equipment with large pressure impact, the leakage can be caused by the damage of the sealing pad. Under strong pressure, it can sometimes remove the seal pad from the plate heat exchanger properly and even out of the heat exchanger. In this case, the equipment must be stopped immediately to cool the heat exchanger to room temperature without pressure. If the sealing pad has been deformed under the action of the pressure impact, it can no longer restore the original shape and position and must replace the new sealing pad. If there is no spare gasket, it must be taken from the entire plate heat exchanger group to the heat sink on both sides of the damaged sealing pad, and then check the sealing pad of the remaining radiator. Under the condition of considering the stress and size of the recombinative heat exchanger group, the pressure is repressed. Must be installed in strict accordance with the requirements of the specification of the rest of the heat exchanger, in order to ensure that the rest of the heat exchanger have enough stress to resist load, stress multiplied by the original each piece must be allowed to take the original heat exchanger piece number, the product divided by the current surplus heat exchanger on the number of slices, now in each heat exchanger must withstand the assembly stress value.

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