1. Scale buildup inside the heat exchanger leads to a decrease in heat transfer efficiency.
Fouling Increases Thermal Resistance and Reduces Heat Transfer Capacity
During long-term operation, impurities, minerals, oil, or corrosion products in the fluid gradually deposit on the heat exchange surface, forming a fouling layer.
Fouling increases heat transfer resistance, reducing the efficiency of heat exchange between hot and cold fluids, resulting in the outlet temperature failing to meet design requirements.
② Fouling Affects Fluid Flow Conditions
A thicker fouling layer reduces the flow channel area, decreasing fluid velocity and reducing turbulence, further weakening the heat exchange effect.
In severe cases, fouling may cause flow channel blockage, leading to increased pressure drop and abnormal equipment operation.
③ Solutions
Develop a regular cleaning plan based on the medium characteristics, such as using chemical cleaning, mechanical cleaning, or online CIP cleaning.
For operating conditions prone to fouling, optimize the fluid flow rate to avoid low-velocity operation that leads to deposition.
2. Insufficient Fluid Flow Rate Leads to Reduced Heat Exchange Efficiency
① Low Flow Rate Affects Heat Transfer
Heat exchangers require a certain flow rate to achieve effective heat exchange. When the flow rate on the hot and cold sides is lower than the design value, the amount of fluid participating in heat exchange per unit time decreases.
Insufficient flow rate will cause the outlet temperature to deviate from the design parameters, reducing overall heat exchange efficiency.
② Common Causes of Abnormal Flow Rate
This may be due to decreased pump operating capacity, filter blockage, insufficient valve opening, or increased pipeline resistance.
For plate heat exchangers, uneven flow distribution may also be caused by plate blockage.
③ Solutions
Check pump operating status, valve opening, and pipeline pressure changes.
Clean the filter and heat exchanger flow channels to ensure the fluid operates at the design flow rate.
3. Insufficient Temperature Difference Leads to Reduced Efficiency
① Temperature Difference is the Core Driving Force of Heat Exchange
Heat exchangers rely on the temperature difference between hot and cold fluids for heat transfer. If the temperature difference between the hot and cold inlet sides is too small, the heat transfer force is insufficient.
Even if the equipment operates normally, the designed heat exchange capacity cannot be achieved.
② Causes of Insufficient Temperature Difference
Heat source temperature decreases, for example, insufficient steam pressure or a drop in hot water temperature.
Cooling medium temperature increases, for example, insufficient cooling water circulation capacity.
③ Solutions
Check the supply of heat and cold sources to confirm whether the inlet temperature meets the design conditions.
Optimize the ratio of hot and cold fluid flow rates to increase the average temperature difference.
4. Heat Exchanger Flow Channel Blockage or Abnormal Pressure Drop
① Blockage Affects Normal Fluid Flow
If the internal channels of the heat exchanger are blocked by impurities, the fluid cannot flow evenly through the heat exchange area.
Uneven fluid distribution reduces the effective heat exchange area, preventing some areas from fully participating in heat transfer.
② Abnormal Pressure Drop is an Important Indicator of Blockage
When the actual operating pressure drop is significantly higher than the design value, it usually indicates internal fouling, scaling, or flow channel blockage.
Long-term operation with high pressure drop may also increase pump energy consumption.
③ Solutions
Regularly check the inlet and outlet pressure difference and compare it with the design parameters.
Disassemble and clean or backflush severely blocked equipment.
5. Inadequate Performance Due to Inappropriate Heat Exchanger Design and Selection
① Insufficient Heat Exchange Area
If the heat exchanger's initial design area is insufficient, it may fail to meet production demands after changes in actual operating conditions.
Common situations include increased production capacity, higher flow rates, or changes in process temperature requirements.
② Unsuitable Heat Exchanger Type
Different types of heat exchangers are suitable for different application environments. For example, plate heat exchangers are suitable for high-efficiency, compact applications; shell-and-tube heat exchangers are suitable for high-temperature, high-pressure conditions.
If the equipment type is mismatched, it may lead to low heat exchange efficiency or maintenance difficulties.
③ Solutions
Recheck the actual operating parameters, including flow rate, temperature, pressure, and medium properties.
If necessary, increase the heat exchange area or replace with a more suitable heat exchanger type.
6. Heat Exchanger Sealing Issues Leading to Performance Degradation
① Sealing Failure Affects the Heat Exchange Process
For plate heat exchangers, aging, damaged, or improperly installed gaskets can cause internal leaks.
Mixing of two fluids reduces heat exchange efficiency and may affect product quality and system safety.
② Manifestations of Sealing Problems
External leakage occurs.
Abnormal inlet and outlet temperatures and unstable pressure changes.
③ Solutions
Regularly check the condition of the gaskets and replace aged or deformed seals.
Install the plates to the specified torque, avoiding insufficient or excessive tightening.
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