1、 Deviation of operating conditions from process requirements
(1) If the newly put into production plate heat exchanger fails to meet the process requirements, carefully check whether the original design parameters, design calculation and assembly are correct, and then decide whether to increase or reduce the heat exchange area and change the process combination.
(2) If the operation of the plate heat exchanger is normal, it deviates from the process requirements after a period of operation, such as: the pressure drop increases or decreases; Medium outlet temperature rises or falls.
The way to deal with this failure is:
(1) Check whether the inlet parameters of cold and hot medium are consistent with the original design value. 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 shall be carried out again to decide whether to increase or decrease the heat exchange area or change the process combination.
(2) If the inlet parameters of cold and hot media are consistent with the original design value, but the outlet parameters cannot reach the design value, stop the machine, disassemble and check whether there is blockage or scaling between plates, and deal with it in time.
2、 Leakage of plate heat exchanger
As the sealing periphery of the plate heat exchanger is long and the plate is thin, leakage may occur in the process of use. Leakage can be divided into internal leakage and external leakage:
(1) External leakage of plate heat exchanger
This refers to the leakage of the medium in the plate heat exchange equipment to the external space. This leakage phenomenon is generally easy to find. The main causes of this leakage are gasket aging, 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.
(2) Internal leakage of plate heat exchanger
This refers to the leakage of two media in the heat exchange equipment from the high-pressure side to the low-pressure side due to some reason. This leakage phenomenon is generally not easy to find in time. The main causes of this leakage are plate perforation, crack and corrosion. The way to find this leakage is to often test the medium on the low-pressure side and judge it from the transformation of its components.
The shutdown inspection method for this leakage is:
(1) Disassemble the plate heat exchanger, remove the dirt on the plate surface, wipe it dry and reassemble the heat exchanger. Hydrostatic test with pressure of 0.2 ~ 0.3MPa shall be conducted on one side. Stop the test after the water flows out from the other side, open the heat exchanger and carefully observe the non pressure test side of the plate. The wet plate is the plate with holes or cracks.
(2) light transmission and coloring inspection methods can also be used on site to find out waste plates. All waste plates and gaskets inspected shall be replaced and used after reassembly.
3、 The plates of the plate heat exchanger are misaligned
(1) For plate heat exchangers with large changes in medium flow and pressure, multi pass combination and long-term use, plate dislocation is easy to occur. Sometimes, leakage occurs quickly after the plate is misplaced; Although some leakage does not occur immediately, it is a hidden danger of leakage, so they must be handled in time.
(2) The main causes of dislocation are: deformation of heat exchanger plate; The sealing gasket of the plate heat exchanger slipped away from the gasket groove. To deal with this dislocation, the deformed plate and the gasket sliding away from the gasket groove should be replaced in time.
4、 Simple treatment method of plate heat exchanger when there is a lack of maintenance equipment on site
(1) During the use of plate heat exchanger, whether the plate is deformed, cracked, perforated, or the gasket is aged and broken, it needs to be replaced in time. In case there are not enough spare parts on the use site, and the heat exchange equipment has neither spare parts nor shutdown, simple treatment on the site shall be carried out.
(2) The simple method for on-site treatment is to pair the damaged plate with the leaking plate (a plate + B plate). If the number is not too large, the number of reduced flow channels is not too large, and it can be used again after assembly, which will not have a great impact on production.