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Maintenance Practices for Air-Cooled Heat Exchangers (ACHEs)

Proper maintenance is critical for ensuring optimal performance, energy efficiency, and longevity of air-cooled heat exchangers. Here are comprehensive maintenance practices:

1. Routine Inspection Practices

A. Visual Inspections (Monthly/Quarterly)

• Check for fin damage (bent, corroded, or missing fins)
• Inspect fan blades for cracks, imbalance, or erosion
• Examine tube bundles for leaks or corrosion
• Verify structural integrity (supports, vibration dampeners)
• Check louver operation (if equipped)

B. Thermal Imaging (Annual)

• Identify hot spots indicating fouling or flow restrictions
• Detect tube blockages or maldistribution

2. Cleaning Procedures

A. Dry Cleaning Methods

1. Compressed Air (100-150 psi)
   1. Effective for loose debris

• Use nozzle at 45° angle to avoid fin damage
• Vacuum Cleaning
  • For light dust accumulation
  • Special fin vacuum attachments available

B. Wet Cleaning Methods

1. Low-Pressure Water (<600 psi)
   1. Effective for moderate fouling
   1. Always spray parallel to fins (never perpendicular)
2. Foam Cleaning
   1. For oily/sticky deposits
   1. Biodegradable foaming agents recommended

C. Chemical Cleaning

• For severe scaling or corrosion products
• Acid cleaning (10% phosphoric acid solution)
• Always perform post-cleaning neutralization

3. Mechanical Component Maintenance

A. Fan Maintenance

Component	Maintenance Action	Frequency
Blades	Balance check	Annual
Bearings	Lubrication	Quarterly
Belts	Tension adjustment	Monthly
Motors	Insulation resistance test	Annual

B. Drive Systems

• VFDs: Check heat sinks and capacitors
• Gearboxes: Oil analysis and level checks

4. Winterization (Cold Climate Specials)

A. Freeze Protection

• Maintain minimum airflow (1.5 m/s) during operation

• Install tracer heating on critical pipes
• Use glycol solutions when applicable

B. Snow/Ice Management

• Install anti-icing controls
• Manual snow removal from fan inlets
• Consider heated louvers

5. Performance Monitoring

A. Key Performance Indicators

1. Air ΔT (Should match design values)
2. Approach temperature (T_out,air – T_ambient)
3. Fan power consumption
4. Pressure drop (airside and process side)

B. Benchmarking

• Compare current performance vs as-new condition
• Track fouling factor over time

6. Common Problems & Solutions

Problem	Root Cause	Solution
High approach temp	Fouled fins	Clean bundles
Vibration	Unbalanced fan	Dynamic balancing
Oil leaks	Gasket failure	Replace seals
Corrosion	Moisture ingress	Apply coatings

7. Maintenance Scheduling

Activity	Frequency	Tools Required
Visual inspection	Monthly	Flashlight, camera
Fin cleaning	6-12 months	Air/water spray

Bearing lubrication	Quarterly	Grease gun
Comprehensive check	Annual	Thermal camera, vibrometer

8. Safety Considerations

A. Lockout/Tagout

• Always isolate electrical power before servicing
• Secure fan rotation during maintenance

B. PPE Requirements

• Face shield during high-pressure cleaning
• Hearing protection near operating fans
• Fall arrest systems for elevated units

Conclusion

Effective ACHE maintenance requires:

1. Regular inspections to catch issues early
2. Proper cleaning techniques matched to fouling type
3. Proactive component care (especially fans)
4. Performance tracking to identify degradation