FERA (Fire and Explosion Risk Analysis) study was conducted for the Fire Protection of the Refrigeration System (Propane Loop) in the Unit-35 of Ras Laffan Industrial City (RLIC) in Oryx GTL. The aim of the FERA study is to systematically assess the fire and explosion hazards of all potential process risk for the entire scope of the project facilities. Click here to read more on What is FERA study?
Ras Laffan Industrial City (RLIC) is located 80 kilometers northeast of Doha, Qatar and is the base of all the onshore operations that support the development and utilization of Qatar’s North Field gas assets. The organization’s operations were initiated in 1996, primarily focused on offering land, infrastructure, and port facilities to Qatar Gas. Since then, RLIC has evolved into a world-class industrial city, facilitating the needs of the most technologically sophisticated natural gas based industries.
The facility of Refrigeration system for the Heavy Ends Recovery is considered for the FERA study. In Heavy Ends Recovery, propane loop only has PSV’s for fire protection, and only manual depressurization facility to the flare. Propane storage has neither external fire protection nor deluge system provided. Fire detection system is inadequate in U35. In case of a pool fire, the system may potentially be subjected to BLEVE / rupture which might lead to vapor dispersion / vapor cloud explosion and cause further damage to adjacent units
The evaluation will be predicated upon the potential risks that may arise during the course of the project’s operations, as per the available information. The scope of work is limited to the different components associated with the proposed facility only. Any other facilities that are not part of the proposed Complex operations are not included as part of this study. The following facility is considered for the FERA study.
The FERA methodology
- Identify potential flammable / fire hazards and threats in the facility.
- Estimate the frequencies of these events based on failure frequency data.
- Physical effect modelling to understand consequence impact of these scenarios (using PHAST 8.4)
- Record the findings and if required provide recommendations
The report presents the findings of a Fire and Explosion Risk Assessment conducted using DNV PHAST & SAFETI software version 8.4. The assessment evaluates various failure cases to provide an overview of the potential impact of major accident scenarios.
The types of events presented are:
- Jet fire
- Flash fire
- Pool fire
- Explosion
Oryx GTL may consider implementation of the recommendations made in the report as per their individual merit.
Key conclusions and recommendations drawn from this study is presented below: This Fire and Explosion Risk Analysis study for this Refrigeration system for the Heavy Ends Recovery facility assessed the potential for major fires or explosions at the facility and performed physical effects modelling for all fire, explosion, and flammable gas and overpressure hazards to agreed hazard end points. The frequency of fires, explosions have been calculated and risk contours were produced to show the frequency at which fires, explosions and toxic gas could affect the facility
Jet fire scenario (25mm Leak scenario-8 kw/m2) for all the Isolatable sections, is found to affect the all-corresponding adjacent equipment’s in Heavy Ends Recovery. Jet fire scenario (25mm Leak scenario-32 kw/m2) for all the Isolatable sections, is found to affect the all the corresponding adjacent equipment’s or facility of Heavy Ends Recovery.
Jet fire risk is credible (since exceedance level of 1×10-4 per year is developed for 8 kW/m2 thermal radiation and 1×10-5 per year is developed for 32 kW/m2 thermal radiation). Pool fire scenario for the Isolatable sections 135- IS-11 – Propane refrigeration loop equipment’s (i.e Vessel on fire case of Propane Suction Separator and Propane Oil Separator) is found to affect the adjacent equipment’s. The pool fire effect level contour is not envisaged for this unit 35 facility.
Automatic Active fire protection requirement such as deluge water and fixed water spray system is assessed and it is found to be required for the unit 35 refrigeration system facility.
The FERA recommendations are as follows
- Based on the fire and explosion risk assessment results, it is recommended to ensure that suitable fire proofing protection measures against 15 min jet fire should be provided for critical supports/load bearing structures, Critical Valve (SDV & BDV) cables of Refrigeration system for the Heavy Ends Recovery facility, in order to prevent potential escalation. The requirements of API 2218 shall also be taken into account in finalization of fire proofing zone.
- Based on the fire and Explosion risk assessment results, it is recommended to ensure that the following active fire system should be provided in the Refrigeration system for the Heavy Ends Recovery facility, in order to avoid BLEVE or Explosion scenario due to impact from the adjacent unit equipment scenarios.
- Fixed water spray system for a minimum duration of 1 hrs has to be provided for the propane refrigerant handling equipment.
- Fire-fighting water mains and fire hydrants.
- Fixed monitors for additional cooling to support the water spray system.
- Ensure fire and gas mapping study is conducted and Fire and Gas Detectors are provided at the appropriate places, in order to ensure immediate detection and isolation.
- Ensure SIL rated BDV is provided for the Propane refrigeration loop, in order to achieve depressurization in 15 min.
