How to Troubleshoot a Plate Heat Exchanger

You don't need to be an expert technician to troubleshoot a plate heat exchanger (PHE). PHEs are persistent, however, they occasionally experience performance issues. Leakage outside the cell, leakage within the cell, and pressure drop are the three most common problems with PHE. Most of these problems are easy to identify and fix.

This article will help you find out what's wrong with your plate heat exchanger and how to fix it. Almost all problems are caused by plate fouling or gasket failure, but it's important to figure out if this is a one-time problem or a system defect. The first step is to determine what is causing your heat exchanger to fail.

Identify symptoms

Here are some of the most common symptoms:

• The pressure drop from inlet to outlet increases.

• Heat transfer efficiency is deteriorating.

• Both traffic and performance are affected.

• Leakage during process

The first three symptoms are usually caused by plate fouling, while the last is caused by gasket failure. However, any of these four can be caused by a gasket failure or a rare plate crack, so it's critical to take some basic procedures to find out what's wrong.

Differential Leaks and Gasket Failure

When troubleshooting, it’s usually preferable to start with the most likely problem, as it has the simplest and cheapest solution. Gasket failure is the easiest thing to spot: if a gasket fails, the pressure will drive fluid through the leak, and you’ll see fluid dripping from the PHE. You’ll be able to easily detect the failure since the fluid will seep from the faulty gasket. Disassemble your PHE and remove the plate with the failing gasket as well as a plate adjacent to it. Then, if you have new parts on hand, just replace them, reassemble, and tighten your PHE to specifications before returning it to service. If you don’t have the replacement components on hand and can’t wait for them to arrive, you may simply close your plate heat exchanger and put it back into service while you wait – the loss of two plates will have a little influence on performance. However, with two fewer plates, be sure you know how much to tighten the PHE. This information should be in your manual or available from the manufacturer.

A differential leak occurs when two fluids are in a PHE mix owing to device failure. Incompatible fluids and/or high pressure are the two most typical causes of a failed gasket. Ensure that your pressures are within specifications (and that your system is devoid of potential water hammers) and that your gaskets are rated for the materials you’re using. If your gaskets are forming holes, your fluid is likely too hot or corrosive, and you’ll need to replace them with new ones that are better suited to your operation.

External leakage

Damaged gaskets or unit assembly errors are the most common causes of fluid leakage. First measure the distance between the front plate and the pressure plate. The device's instructions should have given you this measurement. If this measurement is larger than usual, the unit should be tightened; make sure all bolts are tightened evenly. If the unit continues to leak after tightening, if this measurement is accurate, mark which plates are leaking. Check the plate after removing the heat exchanger. On the designated plate, replace the gasket. Our heat exchanger brochure contains instructions on how to replace the gasket.

Leakage inside the unit (liquid mixing)

If the liquids inside the device start to mix, it's because the plates inside the device are leaking. Perfboard is most likely to be blamed. This can be verified using a stress test. Fill the unit halfway with water and pressurize only one side. If there is an unpressurized side of the perforated plate, it will overflow. Apply consistent water pressure on one side of the unit to get started (never use compressed air in a PHE). Fill the other side of the device with water, but do not apply pressure on the other side. If the plate is perforated, the compressed side will seep into the uncompressed side, causing overflow. If the heat exchanger has two sections, each section must be tested independently. If the plate is perforated, disassemble the machine and inspect the plate with gap detection fluid.

DEGONG brewery with plate heat exchanger

Corrosion and Plate Fouling

Plate fouling is the most prevalent problem with PHEs, but it’s difficult to fix because it’s not usually covered by a warranty. If your PHE becomes fouled frequently due to the qualities of your process fluid, there isn’t much you can do except clean it regularly. You can talk to your manufacturer about adding plates with wider spacing, but that solution has performance and cost limitations, and it isn’t appropriate in all circumstances. In general, the best approach is to keep a regular cleaning plan. The most convenient method is to clean in place (CIP), however, disassembly and cleaning by hand is also an option.

Corrosion of the plates is a far more serious problem than simple fouling. A differential leak is also present in this case. You can re-use your plate heat exchanger in the same way, but a cracked or corroded plate indicates that one of your fluids is excessively corrosive, and you may encounter the same issue again. Make that your PHE is correctly specified for your application by checking with your manufacturer. If everything appears to be in order, the crack or rust is almost certainly a manufactured defect that will be covered by warranty.

Heat Transfer and/or Pressure Drop Performance of the PHE is Abnormal

There are a few tests you may run to figure out why your heat exchanger isn’t performing as well, as it should. The most prevalent problem with heat exchangers is poor performance, which can be caused by a number of factors including platage errors, insufficient water flow, debris buildup inside the device, or a bad hookup.

Platage error: If the plates are joined incorrectly, a dead zone can form, leading the unit to bypass a portion of the plates. Examine the plates to make sure they’re in a honeycomb design. It can be difficult to spot the pattern change straight away, so keep an eye out for any backward plates. If a plate is out of place, you must open the heat exchangerand turn the reverse plate. Close the device and test the pressure once more when all of the plates have been adjusted.

Insufficient water flows: The heat exchanger will lose productivity if the water flowing to the unit is insufficient. Check the water’s pressure and flow rate to make sure they’re within the set limits.

Debris in the unit: Debris in the unit will reduce performance. To clear out any extra debris, run a regular CIP cycle; if the debris does not go, manual cleaning may be required. Cleaning a heat exchanger by hand is pretty simple, and the Heat Exchanger Manual contains full instructions.

Faulty Connection: If the connection is incorrect, the unit will run at very low efficiency. Check the operating and setup instructions to make sure it’s working appropriately. Keep in mind that countercurrent flow is essential.

Thing to Remember

Plate heat exchangers are notoriously difficult to assemble if you don’t know the plate configuration. Please do not remove your dishes from the table without first numbering them.