Common failures encountered in the use of plate heat exchangers

Common failures encountered in the use of plate heat exchangers

1. External leakage, mainly manifested as leakage (small volume, discontinuous water droplets) and leakage (large volume, continuous water droplets). The main places where leakage occurs are the seal between the plate and the plate, the two sealing leak grooves of the plate, and the inner side of the end plate and the compression plate.

　　2. The heating temperature cannot meet the requirements. The main feature is that the outlet temperature is low, which fails to meet the design requirements.

　　3. The pressure drop is large, and the medium inlet and outlet pressure drop exceeds the design requirements, or even many times higher than the design value, which seriously affects the system's requirements for flow and temperature. In the heating system, if the pressure drop on the hot side is too large, the primary side flow will be seriously insufficient, that is, the heat source is not enough, resulting in the secondary side outlet temperature that cannot meet the requirements.

　　 The cause of the failure and its treatment

1. In the case of leakage, re-clamp the equipment according to the clamping size provided by the manufacturer. The size should be uniform, and the deviation of the compressed size should not exceed ±0.2N (mm) (N. The total number of plates) ), the parallelism between the two compression plates should be kept within 2 mm. Mark the leaking parts, then disassemble the heat exchanger and investigate and solve them one by one, and then reassemble or replace the gaskets and plates. Disassemble the heat exchanger, repair the deformed parts of the plate or replace the plate. When there is no plate spare part, the plate at the deformed part can be temporarily removed and then reassembled for use. When reassembling the disassembled plates, clean the plate surface to prevent dirt from adhering to the gasket sealing surface.

　　2. The pressure drop is too large to remove the dirt or plate fouling in the heat exchanger flow channel. For the newly operating system, clean it once a week according to the actual situation. Avoid damaging the plates and rubber pads during the cleaning process. If the mechanical backwashing method without disassembly is used, a nozzle should be connected to the medium inlet and outlet pipes in advance, the equipment should be connected to the mechanical cleaning vehicle, and the cleaning fluid should be injected into the equipment in the opposite direction of the medium flow. The cycle cleaning time is 10-15min. The flow rate of the medium is controlled at 0.05～0.15 m/s.

　　3. The heating temperature cannot meet the requirements. Increase the flow rate of the heat source or increase the diameter of the heat source medium pipeline. Balance the flow of multiple plate heat exchangers operating in parallel. Disassemble the plate heat exchanger to clean the surface of the plates.