What are the common problems of plate heat exchangers and how to solve them?

Liquid cross-contamination in plate heat exchanger;

 

Causes of plate heat exchanger cross-linking: improper selection of plate raw materials leads to corrosion, cracks or perforations of the plates, and operating conditions do not meet design requirements; residual stress after cold stamping of the plates and stress corrosion caused by too small clamping size during installation; slight leakage at the plate leakage groove causes the concentration of harmful substances in the medium to corrode the plates, resulting in cross-linking.

 

The solution to cross-liquid is: replace the cracked or perforated plates, and use the light transmission method to find the cracks in the plates on site; adjust the corresponding operating parameters to meet the design conditions; the clamping size of the plate heat exchanger should meet the requirements when repairing and assembling, and the smaller the better.

Plate heat exchanger leakage (seal leakage)

Causes of leakage in HVAC equipment: The clamping size is not in place, the size is uneven or the clamping bolts are loose; some gaskets are out of the sealing groove, there is dirt on the main sealing surface of the gasket, the gasket is damaged or the gasket is aged; the plate is deformed, and the assembly is misaligned, causing the gasket to run; there are cracks in the plate sealing groove or the sealing area.

 

How to deal with leakage of plate heat exchanger：In a pressure-free state, re-clamp the equipment according to the clamping size provided by the manufacturer. The size should be uniform and consistent.The error of the compression scale should not be greater than 0.2*the total number of plates, and the equivalence between the two compression plates should not be greater than 2 mm; you can mark the leaking parts.Then disassemble the heat exchanger and check each one, reinstall or replace the gaskets and plates; repair or replace the deformed parts of the plates.

 

       Causes of leakage in HVAC equipment: The clamping size is not in place, the size is uneven or the clamping bolts are loose; some gaskets are out of the sealing groove, there is dirt on the main sealing surface of the gasket, the gasket is damaged or the gasket is aged; the plate is deformed, and the assembly is misaligned, causing the gasket to run; there are cracks in the plate sealing groove or the sealing area.

      How to deal with leakage of plate heat exchanger：In a pressure-free state, re-clamp the equipment according to the clamping size provided by the manufacturer. The size should be uniform and consistent.The error of the compression scale should not be greater than 0.2*the total number of plates, and the equivalence between the two compression plates should not be greater than 2 mm; you can mark the leaking parts.Then disassemble the heat exchanger and check each one, reinstall or replace the gaskets and plates; repair or replace the deformed parts of the plates.

       Reasons for excessive pressure drop in plate heat exchanger:Flow channel blockage: solid particles and rust products are deposited, reducing the flow cross section; improper selection: the actual flow rate far exceeds the design value, or the plate flow channel width does not match the medium. viscosity;Changes in medium properties: Low temperature causes a sudden increase in medium viscosity, or suspended matter increases flow resistance.

     How to deal with excessive pressure drop:Adjust operating parameters to reduce load shock; clean the inlet filter to eliminate front-end blockage; reverse flush the flow channel to remove minor blockages;Severe blockage of the flow channel: disassembly, cleaning and repair; Improper selection: equipment modification and parameter optimization; Installation and assembly problems: correction and retightening.

       Reasons for heat transfer efficiency attenuation:Medium problems: Water hardness is too high, causing scaling; the medium contains high-viscosity/coking-prone components; improper operation: long-term over-flow operation, excessive turbulence intensity, accelerating impurity deposition; 

       lack of pretreatment: no high-precision filter (precision <100 mesh) installed at the inlet, solid particles blocking the flow channel.

Treatment method: Remove dirt by cleaning to restore its heat transfer capacity and flow area.

         Causes of internal leakage in plate heat exchangers:Plate damage: Corrosion perforation (chloride pitting, intergranular corrosion), overheating cracking, and freeze cracking.Seal failure: Extensive damage or detachment of the seal, leading to cross-flow of the medium. Poor material compatibility: The plate material does not match the medium characteristics (e.g., using 304 stainless steel to handle chloride-containing media).

Treatment methods: Adjust operating parameters to reduce fluid impact; exhaust and remove blockage to eliminate fluid disturbance; temporarily reinforce to reduce vibration transmission;

       Causes of plate corrosion: Medium corrosion: Chloride ions destroy the passivation film (pitting corrosion), strong acid/strong alkali accelerates chemical corrosion; Material problems: The plate material does not match the medium (such as using 304 stainless steel to treat chloride-containing media); Environmental factors: After decommissioning, the humid environment triggers oxidative corrosion, and different materials (carbon steel support + stainless steel plate) form a galvanic cell, leading to electrochemical corrosion; Process defects: Improper heat treatment after plate welding, resulting in reduced corrosion resistance of grain boundaries (intergranular corrosion).

        Anti-corrosion treatment methods: clean the surface for mild corrosion, repair the local area for moderate corrosion, and replace the plate for severe corrosion.