Common failure analysis and maintenance of plate heat exchanger
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 disposal methods. Let us analyze the causes and maintenance methods for different faults.
1. The external leakage indicates that the leakage is not large, the water droplets are discontinuous and the leakage is large. The main parts of the continuous leakage of water droplets are the seal between the plate and the plate, the two seal leakage grooves of the plate, and The end plate and the inner side of the pressing plate.
Reasons for external leakage ① The clamping dimensions are not in place, the dimensions are not uniform everywhere, and the dimensional deviation should not be greater than 3mm or the clamping bolts are loose.
② Part of the gasket is detached from the sealing groove, the main sealing surface of the gasket is dirty, the gasket is damaged or the gasket is aging.
③ The plate is deformed, and the running pad is caused by assembly misalignment.
④ There are cracks in the plate sealing groove or in the second sealing area.
Maintenance method ① In a non-pressed state, re-clamp the equipment according to the clamping dimensions provided by the manufacturer. The dimensions should be uniform and the deviation of the pressing dimensions should not be greater than ± 0.2NmmN. The total parallelism between the two pressing plates should be maintained. Within 2mm.
② Make a mark on the external leak, then disassemble the heat exchanger one by one to check and solve, reassemble or replace the gaskets and plates.
③ Disassemble the open heat exchanger and repair or replace the deformed part of the plate. When no spare parts are available, the deformed parts can be temporarily removed and reassembled.
④ When reassembling the disassembled plate, clean the surface to prevent dirt from adhering to the gasket sealing surface.
2. The characteristic of string fluid is that the medium on the higher pressure side is strung into the medium on the lower pressure side, and the system will show abnormal pressure and temperature. If the medium is corrosive, it may also cause corrosion of other equipment in the pipeline. Streaking usually occurs in the diversion area or in the second sealed area.
Reasons for the occurrence of liquid leakage ① Due to improper selection of the plate, cracks or perforations occur in the plate corrosion.
② The operating conditions do not meet the design requirements.
③ Residual stress after cold stamping of the plate and too small clamping dimensions during assembly cause stress corrosion.
④ There is a slight leakage at the plate leakage groove, which causes harmful substances (such as C1) in the medium to condense and corrode the plate, forming a string of liquid.
Maintenance method ① Replace the cracked or punctured L plate, and use the light transmission method to find the plate crack on site. ② Adjust the operating parameters to meet the design conditions.
③ The size of the clamp during maintenance and assembly of the heat exchanger should meet the requirements, not as small as possible. ④ The plate materials are reasonably matched.
3. Large pressure drop The inlet and outlet pressure drop of the medium exceeds the design requirements, even many times higher than the design value, which seriously affects the system's requirements for flow and temperature. In a heating system, if the hot-side pressure drop is too large, the primary-side flow rate will be seriously insufficient, that is, the heat source is insufficient, resulting in the secondary-side outlet temperature not meeting the requirements.
4. The heating temperature can't meet the requirements. The main characteristic is that the inlet temperature is too low to meet the design requirements.
Causes ① Insufficient medium flow on the primary side causes a large temperature difference on the hot side and a small pressure drop.
② The cold side temperature is low, and the cold and hot end temperatures are low.
③ The flow distribution of multiple plate heat exchangers operating in parallel is uneven.
④ Scaling inside the heat exchanger is serious.
The above is the failures often encountered in the use of plate heat exchangers. As a professional plate heat exchanger manufacturer, we also analyze the causes and solutions of the failures for free, helping us to operate the equipment correctly during use.