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Simultaneous Production of LNG and NGL. Why NGL with LNG is of increasing interest NGL recovery processes Case study Cryomax process 0% - 65% ethane recovery Three configurations in LNG train Operability and reliability considerations. NGL recovery in LNG plants. Existing LNG plants.
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Why NGL with LNG is of increasing interest NGL recovery processes Case study Cryomax process 0% - 65% ethane recovery Three configurations in LNG train Operability and reliability considerations
NGL recovery in LNG plants Existing LNG plants Next step C4 Sometimes 100% C3 Sometimes 90 - 95% C2 Once 30 - 50% Scheme Scrub column Turbo-Expander
Ethane • New markets require lean revaporised NG • UK Wobbe Index 51.4 MJ/Sm3 (max) • ~ 50.8 MJ/Sm3 in Qatar • Met with 36% ethane extraction • Ethylene from ethane in Qatar • Qatar 2.5 Mtpa in 2008 • UK 2.8 Mtpa (all feed stocks) • France 3.4 Mtpa (all feed stocks)
Why NGL with LNG is of increasing interest NGL recovery processes Case study Cryomax process 0% - 65% ethane recovery Three configurations in LNG train Operability and reliability considerations
NGL recovery processes • Efficient ethane and propane plus extraction • Flexibility in ethane recovery • Good selectivity - minimal methane in NGL • Entrainment tolerant – no heavy ends, ever • Resistance to equipment failure • Lean gas at high pressure to favour liquefaction
Conventional scrub column C3R NG 54 bar -35°C NG 55 bar -16°C NGL LNG C3R SCRUB COLUMN REFLUX LIQUEFACTION MCHE PRECOOLING LEAN GAS C3R MR NGL DRY NG
Scrub column (high recovery) MCHE NG 52 bar -65°C NG 55 bar -35°C LNG NGL REFLUX LIQUEFACTION MCHE PRECOOLING SCRUB COLUMN OVERHEAD LEAN GAS C3R MR NGL DRY NG
Cryomax LNG LIQUEFACTION MCHE PRECOOLING CRYOMAX DUAL COLUMN NGL RECOVERY LEAN GAS C3R MR NGL DRY NG
Cryomax - LNG LEAN GAS TO MCHE PRECOOLED GAS 36 bar -80°C 29 bar DC1 RT Recovery Tower Reflux NGL Demethaniser Reflux US Patent 5,291,736
Why NGL with LNG is of increasing interest NGL recovery processes Case study Cryomax process 0% - 65% ethane recovery Three configurations in LNG train Operability and reliability considerations
Cryomax Case Study • Qatar: North Field gas; climate • APCI C3/MCR process • High LNG capacity (approximately 5 Mtpa) • High natural gas pressures • Two GE Frame 7 gas turbines • MCHE outlet temperature –148°C • Hydraulic turbines for MCR and LNG • Four ethane extraction rates (0-65%) in three configurations
Cryomax Unit Location • “Front End” • Warm natural gas feed • No propane refrigeration • Driven by lean gas compression • Inlet = Outlet (P; T) NGL NG NRU OFF GAS “FRONT END” NGL RECOVERY LEAN GAS COMPRESSION C3 PRECOOLING NG LIQUEFACTION NITROGEN REMOVAL LNG • “Straddle” • Pre-cooled feed • Inlet = Outlet (P; T) NGL NG NRU OFF GAS “STRADDLE” C3 PRECOOLING NGL RECOVERY LEAN GAS COMPRESSION NG LIQUEFACTION NITROGEN REMOVAL • “Mid train” • Pre-cooled feed • P2 < P1 • Simpler • Less power • Less capacity LNG NG NGL NRU OFF GAS “MID TRAIN” C3 PRECOOLING NGL RECOVERY NG LIQUEFACTION NITROGEN REMOVAL LNG
Why NGL with LNG is of increasing interest NGL recovery processes Case study Cryomax process 0% - 65% ethane recovery Three configurations in LNG train Operability and reliability considerations
NGL recovery rates Ethane 1% 16% 36% 65% Propane 99.0% 95.8% 94.5% 97.7% Butane + 100% 100% 100% 100% HHV * Btu/scf 1046.6 1042.0 1033.8 1019.0 Wobbe * MJ/Sm3 51.1 51.0 50.8 50.5 * In LNG tanks in Qatar
Specific power Target C2 Recovery Front end Straddle Mid-train
Why NGL with LNG is of increasing interest NGL recovery processes Case study Cryomax process 0% - 65% ethane recovery Three configurations in LNG train Operability and reliability considerations
“Straddle” - Lean gas compressor failure • Same as “mid-train” scheme • LNG quality unchanged • 10% to 15% reductionin throughput
“Straddle” - Joule-Thomson Mode • C3 precooling & lean gas compressor OK • Specifications OK except Wobbe • 5%-10% reductionin throughput
“Straddle” - Joule-Thomson Mode • C3 precooling & lean gas compressor OK • Specifications OK except Wobbe • 5%-10% reductionin throughput Expander JT mode Expander power MW 5.4 - Ethane recovery % 36 1 Propane recovery % 93 76 Wobbe Index MJ/Sm3 50.8 51.2 Sp consumption MW.h/t 0.267 0.287
Conclusions • Ethane and C3/C4 LPG extraction in Qatar meets lean gas specifications directly • The Cryomax process can be adapted to a wide range of ethane recovery requirements • Process efficiency insensitive to extraction rate or location • Cryomax “Straddle” – Efficient and reliable • New or existing trains