Introduction
Flare systems are critical safety features in hydrocarbon processing facilities, designed to safely dispose of excess gases during both normal operations and emergency conditions. However, abnormal events such as flare flame-out can result in the release of unignited flammable or toxic gases. A Flare Radiation and Dispersion Study is therefore essential to evaluate how such releases behave under realistic and worst case atmospheric conditions and to verify that personnel, equipment, and surrounding areas remain adequately protected.
Methodology – Key Highlights
- Study Scoping
- Data Collection & Source Term Definition
- Scenario Identification
- Meteorological Modelling Setup
- Consequence Modelling (Flammable & Toxic Dispersion)
- Results Interpretation & Criteria Comparison
- Mitigation & Recommendations
- Reporting & Documentation
Outcomes
The Flare Radiation and Dispersion Study provides a clear technical validation of flare system performance by quantifying flammable and toxic dispersion extents under realistic and worst-case conditions. It confirms safe separation distances for personnel and equipment, identifies critical meteorological drivers influencing dispersion behaviour, and strengthens the technical basis for emergency planning and regulatory compliance.
1. Case Study: Flare Flame-Out Dispersion Analysis Study
Facility – Flare System
Client: ORYX GTL Limited
Introduction
ORYX GTL Limited operates a large-scale GTL facility at Ras Laffan Industrial City, Qatar, with elevated flare systems for safe disposal of relief and vent gases. A HAZID study identified flare flame-out as a credible abnormal scenario that could result in the release of unignited flammable and toxic gases. To address potential risks to personnel under adverse meteorological conditions, a Flare Flame-Out Dispersion Analysis Study was commissioned to evaluate gas dispersion behaviour and confirm whether hazardous concentrations could reach occupied areas.
Project Insights
- Dispersion modelling demonstrated that flammable gas clouds remained at elevated heights and did not enter the personnel breathing zone.
- Worst-case dispersion extents occurred under low wind speed and stable atmospheric conditions, which governed the assessment.
- Toxic gas dispersion analysis showed that carbon dioxide (CO₂) at IDLH concentrations remained confined close to the flare elevation.
- Carbon monoxide (CO) dispersion resulted in extended downwind plumes only under highly conservative modelling assumptions.
- No credible ground-level exposure to hazardous concentrations was identified for the assessed scenarios.
- The results supported validation of flare stack elevation and provided key inputs for emergency response planning.
Conclusion
The flare flame-out dispersion assessment confirmed that, even under conservative worst-case conditions, the elevated flare systems at ORYX GTL Limited do not pose a credible flammable or toxic exposure risk to ground level personnel.
The study strengthened the facility’s safety justification by validating flare system performance, supporting emergency preparedness, and demonstrating alignment with recognised consequence modelling practices. Such dispersion assessments form a critical part of maintaining robust process safety and regulatory confidence in complex hydrocarbon processing environments.
