Air Blast Type Horizontal Air Cooled Heat Exchanger, Embedded G Fin Tube, API 661, ASME VIII Div.1 , ISO 13706

Horizontal air-cooled heat exchanger (ACHE) is a type of heat exchanger where hot process fluid flows through horizontal tubes while ambient air is forced or induced across them for cooling. These are widely used in refineries, petrochemical plants, power plants, and gas processing facilities due to their efficiency and space-saving design.

1. Key Features of Horizontal ACHEs

A. Design & Components

1. Tube Bundle

   • Horizontal tubes (typically finned for better heat transfer).

   • Materials: Carbon steel, stainless steel, copper-nickel, titanium.

   • Fins: Aluminum (most common), stainless steel, or galvanized steel.

2. Fans & Drivers

   • Forced draft (fans below bundle) or Induced draft (fans above bundle).

   • Fan types: Axial or centrifugal.

   • Drivers: Electric motors, steam turbines, or hydraulic systems.

3. Headers & Nozzles

   • Plug-type, cover plate, or manifold headers.

   • Nozzles designed for thermal expansion.

4. Support Structure

   • Carbon steel frame with corrosion-resistant coating.

   • Designed for wind & seismic loads (per API 661).

B. Flow Configuration

• Process fluid flow: Inside tubes (single-pass or multi-pass).

• Airflow: Crossflow over finned tubes.

2. Advantages of Horizontal ACHEs

✔ Space Efficiency – Compact footprint compared to vertical designs.
✔ Better Air Distribution – Uniform cooling due to horizontal airflow.
✔ Ease of Maintenance – Tube bundles can be easily removed for cleaning.
✔ Flexible Layout – Can be installed on pipe racks or ground level.
✔ Energy Efficient – Variable-speed fans optimize power consumption.

3. Common Applications

• Refineries: Cooling hydrocarbon streams (e.g., overhead condensers).

• Power Plants: Auxiliary cooling for lube oil, transformer oil.

• Gas Processing: Condensers for natural gas liquids (NGLs).

• Chemical Plants: Cooling reactors, distillation columns.

4. Design Considerations (API 661 Compliance)

A. Thermal Performance

• Design ambient temperature: Typically 38°C (100°F).

• Approach temperature: Difference between outlet process temp and ambient air (usually 10–20°C).

B. Mechanical Design

• Wind load: Must withstand 160 km/h (100 mph) gusts.

• Seismic design: Per local codes (e.g., ASCE 7).

• Corrosion allowance: Minimum 1.5 mm (1/16 in).

C. Vibration & Noise Control

• Natural frequency analysis to avoid resonance.

• Acoustic enclosures if noise exceeds 85 dB(A).

5. Maintenance & Troubleshooting

6. Comparison: Horizontal vs. Vertical ACHE

Conclusion

Horizontal air-cooled heat exchangers are versatile, efficient, and easy to maintain, making them ideal for refineries, power plants, and gas processing. Key compliance standards include API 661, ISO 13706, and ASME BPVC.