Common faults of plate heat exchanger, their causes and treatment methods

With the development and reform of industry, the position of plate heat exchanger in industry is getting heavier and heavier, and there are plate heat exchangers in more and more industries. In order to ensure the normal operation of plate heat exchanger and prolong its service life, it is particularly important to know the common faults of plate heat exchanger, their causes and treatment methods. Let's introduce the diagnosis and treatment of common faults of plate heat exchangers.

(a) the operation status deviates from the process requirements

If the new plate heat exchanger put into production can't meet the process requirements, the original design parameters, design calculation, assembly, etc. should be carefully checked, and then the heat exchange area should be increased or decreased, and the process combination should be changed. If the plate heat exchanger starts to operate normally, it will deviate from the process requirements after a period of operation, such as: pressure drop increases or decreases; The outlet temperature of the medium rises or falls. The methods to deal with this failure are as follows: 1. Check whether the inlet parameters of cold and hot media are consistent with the original design values. If not, try to adjust it to the original design value. If the inlet parameters have been changed and cannot be adjusted to the original design value, the design calculation should be carried out again, and it is decided to increase or decrease the heat exchange area or change the process combination. 2. If the inlet parameters of the cold and hot media are consistent with the original design values, but the outlet parameters can't meet the design values, you should stop the machine, disassemble it to check whether there is any blockage or scaling between the plates, and handle it in time.

(II) Leakage of plate heat exchanger Because of the long sealing perimeter and thin plate of plate heat exchanger, leakage may occur during use. Leakage can be divided into internal leakage and external leakage. 1. External leakage of plate heat exchanger here refers to the leakage of medium in plate heat exchanger to external space. This kind of leakage phenomenon is generally easy to find. The main reason for this leakage is the aging of gasket, corrosion or deformation of plate. When this kind of leakage occurs, mark the leaking plate, and then disassemble the equipment to take out the damaged plate and replace it with a new one. 2. Internal leakage of the plate heat exchanger. This refers to the leakage of two media in the heat exchanger from the high-pressure side to the low-pressure side for some reason. This leakage phenomenon is generally not easy to find in time. The main causes of this leakage are perforation, crack and corrosion of the plate. The method to find this kind of leakage is to often test the medium on the low-pressure side and judge it from the change of its components. This leakage shutdown inspection method is: (1) Disassemble the plate heat exchanger, clean and dry the dirt on the plate, and then reassemble the heat exchanger. Carry out 0.2~0.3Mpa water pressure test on one side of the heat exchanger. Stop the test immediately after the water flows out from the other side, disassemble the heat exchanger, and carefully observe the side of the plate that did not participate in the pressure test. The wet plate is the plate with holes or cracks. (2) At the scene, the inspection methods of light transmission and coloring can also be used to find out the waste plates. All the waste plates and gaskets checked out should be replaced and reassembled for use.

(3) Plate dislocation of plate heat exchanger. Plate dislocation is easy to occur for plate heat exchangers with large changes in medium flow and pressure, multi-pass combination and long-term use. After the plate is dislocated, sometimes it will leak out soon; Although some of them do not leak immediately, they are a hidden danger of leakage, so they must be dealt with in time. The main causes of dislocation are: deformation of heat exchanger plate; The sealing gasket of the plate heat exchanger slipped out of the gasket groove. To deal with this dislocation, the deformed plate and the gasket sliding out of the gasket groove should be replaced in time.

(IV) When there is a lack of maintenance equipment on site, simple treatment method of plate heat exchanger. During the use of plate heat exchanger, whether the plate is deformed, cracked or perforated, or the gasket is aged or broken, it needs to be replaced in time. In case there are not enough spare parts on the site, and the heat exchange equipment has neither spare parts nor shutdown, it should be handled simply on the site. On-site simple treatment method is to pair the damaged plate with the leaking plate (plate A+plate B). If the number is not too large, the number of flow passages will not be reduced, and it can be used continuously after assembly, which will not have a great impact on production. As the application field of plate heat exchanger is expanding, different media and processes have different requirements for temperature resistance, pressure resistance and corrosion resistance. It is obviously impossible to think of a "universal" gasket to adapt to all situations. Instead, gaskets made of different materials should be used for different situations. Commonly used gaskets are hexagonal in cross section. Commonly used gaskets are natural rubber, neoprene, Ding Qing rubber, EPDM, silicone rubber, fluororubber, asbestos fiberboard, etc. In case of leakage, fracture, aging and other phenomena, the gasket of plate heat exchanger should be replaced in time. Replacement should be carried out in the following order. 1. Remove the waste gasket. Be careful not to scratch the gasket groove during disassembly. 2. Use acetone, butanone or other ketone solvents to remove the residual glue in the gasket groove. 3. Wipe the gasket groove and gasket with clean cloth or cotton yarn. 4. Apply the adhesive evenly in the gasket groove. 5. Stick a clean new gasket on the board. 6. The plate with the gasket attached should be placed in a flat, cool and ventilated place, and can be installed and used only after it has dried for 4h.

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