Diagnosis and Treatment of Common Running Faults of the Plate Heat Exchanger

Diagnosis and Treatment of Common Running Faults of the Plate Heat Exchanger

17 Jan 2020

1 If the new plate heat exchanger fails to meet the process requirements, it shall carefully check whether the original design parameters, design calculation, assembly, etc. are correct, and then decide whether to increase or reduce the heat exchange area and change the process combination. If the plate heat exchanger starts to operate normally, it will deviate from the process requirements after a period of operation, such as increase or decrease of pressure drop; increase or decrease of medium outlet temperature.

The way to deal with this kind of fault is:
A. Check whether the inlet parameters of hot and cold media are consistent with the original design values. If not, try to adjust to the original value. If the inlet parameters have been changed and cannot be adjusted to the original design value, the design calculation shall be carried out again to decide whether to increase or decrease the heat exchange area or change the process combination.

B. If the inlet parameters of cold and hot media are consistent with the original design values, and the outlet parameters are not up to the design values, the machine shall be shut down, and the boards shall be disassembled to check whether there is blockage or scaling between the boards, and the problem shall be solved in time.

2. Leakage of the heat exchanger
Due to the long sealing perimeter and thin plate of the plate heat exchanger, leakage may occur during use. Leakage can be divided into internal leakage and external leakage.

A. The leakage of plate heat exchanger refers to the leakage of the medium in the heat exchange equipment to the external space. This kind of leakage is easy to be found. The main cause of the leakage is the gasket ageing, corrosion or plate deformation. In case of such leakage, mark the leakage part in time, and open the equipment to replace the gasket or plate.

B. The internal leakage of plate heat exchanger refers to the leakage of two kinds of media in the heat exchange equipment from the high side to the low side due to some reason. This kind of leakage is not easy to find in time. The main causes of the leakage are perforation, crack and corrosion.

The way to find this kind of leakage is to often test the medium at the low-pressure side and judge from the change of its components. The shutdown inspection method for this leakage is:

a. Disassemble the plate heat exchanger, remove the dirt on the plate surface, dry and reassemble the heat exchanger. The water pressure test of 0.2-0.3mpa was carried out on one side. After the other side flows out water, stop the test, open the heat exchanger, and carefully observe the untested side of the plate. The wet plate is the plate with holes or cracks.

b. In the field, it can also be used to check the light transmission and colouring to find out the waste plates. All the inspected waste plates and gaskets shall be replaced and used after reassembly.

3. Plate dislocation of a plate heat exchanger is easy to occur for a plate heat exchanger which has a large change in medium flow and pressure and is a multi-path combination and long-term use. When the plates are misplaced, sometimes they will leak out quickly; although some of them do not leak out immediately, they are a hidden danger of leakage, so they must be dealt with in time. The main causes of the displacement are the plate deformation of the heat exchanger; the sealing gasket of the plate heat exchanger slips away from the gasket groove. In order to deal with this kind of displacement, the deformed plate and the gasket sliding away from the gasket groove should be replaced in time.

4. In the absence of maintenance equipment on site, the simple treatment method of plate heat exchanger in the use process, whether the plate deformation, cracks, perforation, or gasket ageing, fracture, all need 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, the simple treatment on the site shall be carried out. The simple method of field treatment is to extract the damaged plates and the leaking plates in pairs (a plate + B plate). If the number is not too much, the number of reduced flow channels is not too much. After assembly, it will continue to be used, which has little impact on production.