Common Troubleshooting Methods for Plate Heat Exchangers

Plate heat exchangers have been widely used in many fields such as heating. Plate heat exchangers have the characteristics of high heat transfer coefficient, small pressure drop, compact structure, light weight, small occupied space, convenient area and process combination, strong parts versatility, and It has the characteristics of wide selection of materials and easy realization of large-scale production. And become the leading heat exchange equipment in central heating projects. In order to ensure the normal operation of the plate heat exchanger and extend the service life of key components such as plates and rubber pads, it is particularly important to understand the failures of the plate heat exchanger, their causes and treatment methods.

Common troubleshooting methods for plate heat exchangers

1. Common Faults of Plate Heat Exchangers

1) External Leakage

The main manifestations are small leakage, discontinuous water droplets, large leakage, and continuous water droplets leaking out. The main parts that appear are the seals between plates, the secondary sealing leakage grooves of the plates, and the ends. The inside of the plate and compression plate.

2) The Liquid Leakage

The main feature is that the medium on the higher pressure side flows into the medium on the lower pressure side, and pressure and temperature abnormalities will occur in the system. If the medium is corrosive, it may also cause corrosion of other equipment in the pipeline. Liquid leakage usually occurs in the diversion area or the secondary sealing area.

3) Large Pressure Drop

The pressure drop at the inlet and outlet of the medium exceeds the design requirements, and is even many times higher than the design value, seriously affecting the system's flow and temperature requirements. 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 not meeting the requirements.

4) The Heating Temperature Cannot Meet the Requirements

The main feature is that the inlet temperature is low and cannot meet the design requirements.

2. Cause Analysis and Treatment Methods

1. External Leakage

(1) Cause of Occurrence

① The clamping size is not in place, the size is uneven everywhere (the size deviation everywhere should not be greater than 3mm) or the clamping bolt is loose.

② Part of the sealing gasket is separated from the sealing groove, there is dirt on the main sealing surface of the gasket, the gasket is damaged or the gasket is aged.

③ The plate is deformed and the assembly is misaligned, causing the pad to run.

④ There are cracks in the plate sealing groove or the secondary sealing area. Example: Many thermal stations in Beijing, Qinghai, Xinjiang and other places use saturated steam as the primary heat source for heating. Due to the high steam temperature, when the system is unstable in the early stages of equipment operation, the rubber sealing gasket fails at high temperatures, causing steam leakage.

(2) Disposal Method

① In the no-pressure state, re-clamp the equipment according to the clamping dimensions provided by the manufacturer. The dimensions should be uniform and the parallelism between the two compression plates should be maintained within 2mm.

② Mark the leakage area, then disassemble the heat exchanger, check and solve the problem one by one, and reassemble or replace the gaskets and plates.

③ Disassemble the heat exchanger and repair the deformed parts of the plates or replace the plates. If there are no spare parts for the plates, the plates at the deformed parts can be temporarily removed and then reassembled for use.

④ When reassembling the disassembled plates, the plate surface should be cleaned to prevent dirt from adhering to the gasket sealing surface.

2. The Liquid Leakage

(1) Cause of Occurrence

① Due to improper selection of plate materials, corrosion may cause cracks or holes in the plate.

② The operating conditions do not meet the design requirements.

③ Residual stress after cold stamping of the plate and too small clamping size during assembly cause stress corrosion.

④ There is slight leakage at the leakage groove of the plate, causing harmful substances in the medium such as C1 to concentrate and corrode the plate, forming liquid flow.

(2) Disposal Method

① Replace the cracked or perforated plate, and use the light transmission method to search for cracks in the plate on site.

② Adjust the operating parameters to meet the design conditions.

③ When repairing and assembling the heat exchanger, the clamping size should meet the requirements. Smaller is not always better.

④ The pattern information matches reasonably.