How to Select an Enclosed Ground Flare System for LNG and Petrochemical Projects

Created on 07.08
Enclosed ground flare systems are increasingly used in LNG terminals, petrochemical plants, chemical facilities, and other industrial projects where radiation, visibility, noise, and site limitations are important design considerations.
However, selecting an enclosed ground flare is not simply a matter of replacing an elevated flare.
The correct selection depends on process conditions, relief scenarios, environmental requirements, and project philosophy.

1. What Is an Enclosed Ground Flare System?

An enclosed ground flare is a combustion system where flare burners are installed inside a refractory-lined enclosure.
Compared with elevated flare systems, the flame is contained within the combustion chamber, which helps control:
  • Radiation
  • Flame visibility
  • Noise
  • Thermal impact
Typical applications include:
  • LNG terminals
  • Petrochemical plants
  • Chemical industries
  • Pharmaceutical facilities
  • Waste gas treatment systems

2. When Should an Enclosed Ground Flare Be Considered?

① Limited Radiation Requirements

Radiation is one of the primary reasons for selecting enclosed ground flares.
They are often considered when projects have:
  • Limited plot space
  • Nearby operating units
  • Environmental restrictions
  • Public area proximity

② Strict Visual Impact Requirements

Some projects require minimal visible flame.
Examples:
  • LNG receiving terminals
  • Coastal energy facilities
  • Industrial parks
An enclosed flare can significantly reduce visible flame exposure.

③ Noise and Environmental Considerations

High-pressure flare combustion can generate significant noise.
Enclosed systems can help reduce:
  • Flame noise
  • Visual impact
  • Community disturbance

3. Key Engineering Parameters for Selection

Gas Composition

Important parameters include:
  • Hydrocarbon components
  • Methane content
  • Hydrogen content
  • Acid gas content
  • Inert gas concentration
Different gases require different combustion designs.

Heat Release Capacity

The system must be evaluated based on:
  • Maximum emergency relief load
  • Normal operating load
  • Burner quantity
  • Combustion chamber size

Turn-down Ratio

Industrial flare systems often experience large flow variations.
The design must ensure:
  • Stable combustion at low flow
  • Reliable ignition
  • Complete combustion at high flow

Operating Temperature

Material selection is critical because enclosed ground flares operate under high-temperature conditions.
Important considerations:
  • Refractory design
  • Burner material
  • Thermal expansion
  • Maintenance requirements

4. Enclosed Ground Flare vs Elevated Flare

Factor
Elevated Flare
Enclosed Ground Flare
Flame visibility
Visible
Limited
Radiation
Higher
Lower
Height requirement
Requires stack structure
Ground installation
Plot requirement
Vertical space
Ground area
Maintenance
Structural access
Easier access
Typical use
Large emergency loads
Sensitive locations

5. LNG Project Considerations

For LNG facilities, flare selection must consider:
  • BOG management philosophy
  • Emergency depressurization scenarios
  • Cryogenic gas characteristics
  • Terminal location
  • Environmental requirements
A flare system in an LNG terminal is normally not a normal operation device.
It is a critical safety protection system.

6. Engineering Principle

The question should not be:
"Which flare type is more advanced?"
The better question is:
"Which flare configuration provides the safest and most reliable solution for this project?"

Conclusion

Selecting an enclosed ground flare requires a balance between:
  • Safety
  • Environmental performance
  • Site limitations
  • Operating requirements
  • Lifecycle considerations
The best flare system is not determined by appearance.
It is determined by engineering requirements.
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