In a factory, equipment failures are part of everyday operations.
But plate heat exchangers are a little tricky. Unlike motors, they don't smoke or scream when something goes wrong. Instead, they often cause problems quietly, without giving you much warning.
By the time operators notice something is wrong, the temperature may refuse to rise to the required level, the pressure may be alarmingly high, or water may already be leaking all over the floor.
When faced with all these symptoms, how can you quickly identify the source of the problem?
Today, we'll share a few practical troubleshooting techniques to help you identify the likely cause of a fault without disassembling the equipment!
1. Check the Temperature: Determine Whether the Heat Exchanger Is Clogged
This is one of the simplest and most straightforward ways to identify a potential problem.
If the temperature difference between the inlet and outlet of your heat exchanger becomes unusual, something may be wrong.
Symptom 1: The Temperature Difference Increases
For example, the hot water enters at 80°C, but the outlet temperature is only 30°C, whereas it might normally be around 50°C.
This may indicate that the hot water is flowing too slowly through the heat exchanger, causing abnormal heat transfer.
Diagnosis: This usually indicates insufficient flow, most likely due to blockage or an inadequate pump head.
Symptom 2: The Temperature Difference Decreases
The hot water enters at 80°C and leaves at 78°C, showing almost no temperature change.
Meanwhile, the cold water side does not heat up much either.
Diagnosis: This indicates very low heat transfer efficiency. The plate surfaces may be covered with a thick layer of scale, or internal short-circuiting may have occurred. The latter can happen when a damaged gasket allows fluid to bypass the corrugated flow channels and pass directly through an unintended path.
2. Check the Pressure: Determine Whether the Problem Is Blockage or Leakage
The pressure gauge is like a "blood pressure monitor" for a heat exchanger.
Under normal operating conditions, there should be a reasonable pressure difference between the inlet and outlet, such as approximately 0.5 kgf/cm².
Symptom 1: The Pressure Drop Increases Sharply
The inlet pressure is normal or slightly high, but the outlet pressure is unusually low.
This means the fluid is encountering significant resistance inside the heat exchanger, much like traffic congestion on a road.
Diagnosis: Severe blockage is a likely cause. Check immediately for debris obstructing the inlet.
Symptom 2: The Pressure Difference Is Almost Zero
The inlet and outlet pressures are nearly the same.
Diagnosis: This may indicate internal bypassing or a damaged internal partition, allowing the fluid to bypass the intended flow path before completing the normal process.
3. Check the Fluid: Determine Whether Internal Leakage Has Occurred
This is one of the most troublesome faults: cross-contamination between the two fluids.
The two media should remain completely separate, but they have somehow mixed together.
Symptom 1: The Fluid Changes Color
Suppose one side contains clean water while the other contains colored oil or a chemical solution.
If the clean water suddenly becomes cloudy or changes color, something may be wrong.
Diagnosis: The plates may have corroded through or developed cracks. This is a serious problem, and the equipment should be shut down immediately.
Symptom 2: The Pressure Rises Abnormally
For example, the pressure on the low-pressure side rises unexpectedly and approaches the pressure on the high-pressure side.
Diagnosis: This indicates that fluid may be leaking from the high-pressure side into the low-pressure side, providing strong evidence of internal leakage.
4. Inspect the Exterior: Determine Whether External Leakage Has Occurred
External leakage is usually the easiest fault to spot, but different leakage patterns can indicate different problems.
Symptom 1: Leakage When Cold
The equipment starts dripping when it is first started or after it has cooled down following shutdown. However, the leakage stops once the temperature rises.
Diagnosis: This may be caused by aging gaskets or insufficient tightening of the plate pack. At low temperatures, the gaskets may have reduced elastic recovery. As the temperature rises, thermal expansion may improve the seal and stop the leakage.
Symptom 2: Leakage Under Hot Operating Conditions
When the pressure or temperature rises, water begins spraying directly out of the equipment.
Diagnosis: The gasket may have failed completely, the plates may be deformed, or even the tightening bolts may have broken.
In this situation, depressurize and shut down the equipment immediately. This is extremely dangerous!
Final Thoughts
Troubleshooting a plate heat exchanger is essentially a process of logical deduction:
Abnormal temperatures: Check for scale buildup or internal bypassing.
Abnormal pressure: Check for blockage.
Fluid discoloration: Check for internal leakage.
Water on the floor: Check the gaskets and other potential sources of external leakage.
By understanding these warning signs, you can identify potential faults more quickly and take appropriate action before the problem becomes more serious.
