madhat abdel jawad, gexcon: using dedicated cfd-tool flacs for floating lng liquefaction plants
DESCRIPTION
Madhat Abdel-jawad, Managing Director, GexCon Australia,Indonesia and the Middle East delivered this presentation at the 2013 FLNG Forum in Perth. The two day conference brings attendees key insights into the technology and concepts that will unlock Australia’s stranded gas reserves. This event brings together case studies, keynote and technical presentations from the experts at the forefront of the Floating LNG projects. For more information about the forum, please visit the event website: http://www.informa.com.au/flngforum2013TRANSCRIPT
Optimal design of
FLNG installations:
limiting the potential
consequences of
accidental
explosions Dr. Madhat Abdel-jawad MD GexCon Australia Indonesia and the Middle East
GexCon – 2008 2
GexCon in short
More than 800 man years of
explosion experience
~ 400 fire and explosion
projects per year
Main office in Bergen, Norway
Other offices in Perth(AUS),
Jakarta (Indonesia), others.
Agents in Qatar, UAE,
Malaysia and elsewwhere.
GexCon spun off CMR which started Large
research programs in the 70s, 80s and 90s
within gas explosion and dust explosion safety
GexCon – 2008 3
GexCon’s Core Business
Consequence Explosion Analysis Worst case Analysis
Targeted Analysis
Probabilistic Analysis
Fire and Smoke Analysis FEA and CFD
Toxic Dispersion Analysis
Causes
Examples of Past accident investigations include:
TWA 800 (NTSB)
P36 (Petrobras)
Piper Alpha (Investigation led by Lord Cullen)
Buncefield (Total)
Prevention
Protection
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Acceleration
GexCon – 2008 5
I could have left at 5pm
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Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012 6
Explosion generated turbulence
• Positive feedback
mechanism of explosion
generated flow and
combustion
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Experiments – 45 m long array of cross
flow obstructions; no confinement
Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012
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Experiments – obstructed vs. non-
obstructed
Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012
Experiments in congested area – DDT and
detonation
Experiments – DDT and detonation
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Experiments in 3-D corner
P = 0.025 bar
P > 4.0 bar
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Analysis Process Overview
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Geometry import
FLACS Import + Adjustments
Vapour Cloud Explosion Consequence Modelling
Structural Response
Leak Dispersion
Gas Explosions Hazards on Offshore Facilities, Kuala Lumpur, 19-20 October 2010 12
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FLNG: probabilistic study; step 1
geometry: Anticipated congestion
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FLNG: Heavy gas, spill & aerosols Heavy or non-buoyant gas:
Refrigerant medium
NGL extracted offshore
Flashing releases may generate large
dense clouds
Non-buoyant clouds
Greater probability of drifting into
adjacent modules
Larger cloud sizes and higher ignition
probability
Stronger explosions
Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012
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FLNG: LNG spills Implications for explosion analysis:
FLACS geometry – bunds
Bunding: significant impact on pool/cloud size
Leak locations: relative to edge of vessel, drainage points, drip
trays, leaks relative to larger objects
Wind speed will be important for mixing
Wind: 1m/s
Wind: 5m/s
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FLNG example: summarized
In spite of lower leak frequency, release of
non-buoyant gas is the major contributor to
explosion risk:
For the same release rate, clouds becomes
bigger (stay on the ground and don’t
disappear upward)
For the same cloud size, heavier (non-
buoyant) HC give stronger explosions
Non-buoyant gases stay along the ground
and have higher likelihood of being ignited
Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012
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FLNG: probabilistic study
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Port side vs. Starboard side modules
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FLNG: choice of dispersion
scenarios
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FLNG: generation of large clouds
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FLNG: explosion simulations
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Exceedance curves
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Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012 23
Safety gaps • FLNG layout: module based with safety gaps:
1. Reduce likelihood of clouds spanning several modules
2. Reduce pressure if clouds span several modules
3. Reduce pressure load from one module to the other
Implications for Design Accidental Loads (DAL)
• Explosion where clouds span a gap:
Flame propagation in:
1. Congested areas -> flame acceleration & pressure
2. Open gap -> flame deceleration & reduced pressure
3. Flame re-enters congested area -> flame acceleration & pressure
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Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012 24
Safety gaps
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Safety gaps
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Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012 26
Safety gaps
• Dimensioning gas cloud & implication for gap
distance
• Large cloud -> gap -> large impact on DAL
• Small cloud -> gap -> marginal impact on DAL
• Safety gaps can have large cost implications
• Alternative solutions:
• Blast walls, gas migration barriers or water curtains
Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012
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