FERA for Fire Protection of Refrigeration System (Propane Loop) – Oryx GTL

FERA For Fire Protection of the Refrigeration System

A Fire and Explosion Risk Analysis (FERA) study was conducted for the fire protection of the Refrigeration System (Propane Loop) in Unit-35 at Ras Laffan Industrial City (RLIC) for Oryx GTL. The objective of this study was to systematically assess fire and explosion hazards associated with the facility’s operations and provide risk mitigation recommendations.

Overview of Ras Laffan Industrial City (RLIC)

RLIC, located 80 km northeast of Doha, Qatar, serves as the hub for onshore operations supporting the development of Qatar’s North Field gas assets. Established in 1996, it has evolved into a world-class industrial city, offering infrastructure and port facilities for natural gas-based industries.

Scope of the FERA Study

The study focused on the Refrigeration System for Heavy Ends Recovery. Key observations include:

  • The propane loop relies on Pressure Safety Valves (PSVs) for fire protection and only has manual depressurization to the flare.
  • Propane storage lacks external fire protection and a deluge system.
  • Fire detection in Unit-35 is inadequate.
  • In the event of a pool fire, the system could be subjected to BLEVE (Boiling Liquid Expanding Vapor Explosion), leading to vapor cloud explosion and potential damage to adjacent units.

FERA Methodology

Flowchart depicting the fire and explosion risk assessment process, including hazard identification, physical effects modeling, frequency analysis, consequence assessment, and risk reduction strategies.
Fire & Explosion Risk Assessment: Identifying & Mitigating Risks

The study followed a structured approach:

  1. Hazard Identification – Identifying potential fire and explosion hazards.
  2. Frequency Estimation – Assessing event probability using failure frequency data.
  3. Consequence Modeling – Using PHAST 8.4 for impact assessment.
  4. Risk Evaluation & Recommendations – Recording findings and proposing mitigation measures.

The study was conducted using DNV PHAST & SAFETI software (version 8.4) to analyze various failure scenarios, including:

  • Jet Fire
  • Flash Fire
  • Pool Fire
  • Explosion

Key Findings & Risk Assessment

  • Jet Fire Scenarios: A 25mm leak scenario (8 kW/m² radiation) could impact adjacent equipment in Heavy Ends Recovery. A higher intensity scenario (32 kW/m² radiation) could further escalate risks. The jet fire risk is credible, with exceedance levels of 1×10⁻⁴ per year (8 kW/m²) and 1×10⁻⁵ per year (32 kW/m²).
  • Pool Fire Scenarios: A pool fire involving propane refrigeration loop equipment (e.g., Propane Suction Separator, Propane Oil Separator) could impact nearby units. However, risk contour analysis indicates limited spread within Unit-35.
  • Active Fire Protection: The study determined that automatic fire protection, including deluge and fixed water spray systems, is essential for mitigating potential fire risks.

FERA Recommendations

To minimize fire and explosion risks, the following measures are recommended:

  1. Fireproofing Protection: Provide fireproofing for critical supports, load-bearing structures, and essential valve cables (SDV & BDV) in accordance with API 2218 to prevent escalation during a 15-minute jet fire.
  2. Active Fire Protection Systems:
    • Install a fixed water spray system with a minimum duration of 1 hour for propane refrigerant handling equipment.
    • Ensure fire-fighting water mains, hydrants, and fixed monitors for additional cooling.
  3. Fire & Gas Detection: Conduct a Fire and Gas Mapping Study and install fire and gas detectors at strategic locations to enable early detection and isolation.
  4. Emergency Depressurization: Implement a SIL-rated BDV to achieve depressurization within 15 minutes to mitigate BLEVE or explosion risks.

By implementing these recommendations, Oryx GTL can enhance the safety and reliability of its Refrigeration System in Heavy Ends Recovery, ensuring compliance with best practices in fire protection and risk management.