Madhat Abdel Jawad, GexCon: Using dedicated CFD-tool FLACS for floating LNG liquefaction plants

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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/flngforum2013

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Madhat Abdel Jawad, GexCon: Using dedicated CFD-tool FLACS for floating LNG liquefaction plants

  1. 1. Optimal design of FLNG installations: limiting the potential consequences of accidental Dr. Madhat Abdel-jawad explosions MD GexCon Australia Indonesia and the Middle East
  2. 2. GexCon – 2008 GexCon in short GexCon spun off CMR which started Large research programs in the 70s, 80s and 90s within gas explosion and dust explosion safety  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. 2
  3. 3. 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
  4. 4. Acceleration © GexCon AS www.gexcon.com 4
  5. 5. GexCon – 2008 I could have left at 5pm 5
  6. 6. 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 © GexCon AS www.gexcon.com 6
  7. 7. Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012 Experiments – 45 m long array of cross flow obstructions; no confinement © GexCon AS www.gexcon.com 7
  8. 8. Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012 Experiments – obstructed vs. nonobstructed © GexCon AS www.gexcon.com 8
  9. 9. Experiments in congested area – DDT and detonation
  10. 10. Experiments – DDT and detonation
  11. 11. GexCon – 2008 11 P > 4.0 bar P = 0.025 bar Experiments in 3-D corner
  12. 12. 12 12 Gas Explosions Hazards on Offshore Facilities, Kuala Lumpur, 19-20 October 2010 GexCon – 2008 Analysis Process Overview Leak Dispersion Geometry import FLACS Import + Adjustments Structural Response Consequence Modelling 3-Dec-13 12 Vapour Cloud Explosion
  13. 13. 13 FLNG: probabilistic study; step 1 geometry: Anticipated congestion © GexCon AS www.gexcon.com 13
  14. 14. 14 Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012 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 © GexCon AS www.gexcon.com 14
  15. 15. 15 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: 5m/s Wind: 1m/s © GexCon AS www.gexcon.com 15
  16. 16. 16 Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012 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 (nonbuoyant) HC give stronger explosions  Non-buoyant gases stay along the ground and have higher likelihood of being ignited © GexCon AS www.gexcon.com 16
  17. 17. 17 FLNG: probabilistic study © GexCon AS www.gexcon.com 17
  18. 18. 18 Port side vs. Starboard side modules © GexCon AS www.gexcon.com 18
  19. 19. 19 FLNG: choice of dispersion scenarios © GexCon AS www.gexcon.com 19
  20. 20. 20 FLNG: generation of large clouds © GexCon AS www.gexcon.com 20
  21. 21. 21 FLNG: explosion simulations © GexCon AS www.gexcon.com 21
  22. 22. 22 Exceedance curves © GexCon AS www.gexcon.com 22
  23. 23. 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 © GexCon AS www.gexcon.com 23
  24. 24. Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012 24 Safety gaps © GexCon AS www.gexcon.com 24
  25. 25. Safety gaps © GexCon AS www.gexcon.com 25
  26. 26. 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 © GexCon AS www.gexcon.com 26
  27. 27. Seminar on Management of the Gas Value Chain, Jakarta, Indonesia, November 27-28, 2012 27

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