LNG FSU for LNG import to Malta

LNG Floating Storage Unit (FSU) for LNG import to Malta

Thormod Andersen

Department Manager, LNG & Process TechnologyMoss Maritime AS

NORWEP seminar - 22 November 2018

LNG FSU for LNG import to Malta

• Project: LNG FSU for Malta LNG import (ElectroGas Malta)

– The project is part of Malta’s strategy to switch from Heavy Fuel Oil (HFO) & diesel power generation to gas-fired power generation (better wrt local pollution and also CO2 footprint).

– The FSU was built under a $300 million contract Bumi Armada won from ElectroGasMalta in 2015.

– Malta received its first-ever LNG cargo in 2017 via the Floating Storage Unit (FSU) Armada Mediterrana.

– The FSU delivers LNG to the onshore regasification plant feeding natural gas to the CCGT Delimara 4 power plant.

LNG FSU for LNG import to Malta

LNG FSU for LNG import to Malta

• Project: LNG FSU for Malta LNG import (ElectroGas Malta)

• Moss scope: Pre-FEED, basic & detail engineering of LNGC ⇾ FSU conversion

• FSU: Conversion of MOL’s 125,000 m3 MOSS LNG carrier Wakabu Maru, by Mitsui (MES) in Japan, 1985. Storage tanks in very good condition.

• Project highlights:

- 18 years contract, start-up 2017

- Small & continuous LNG flow from

FSU to shore regas plant feeding

GTCC gas fired power plant

- All BOG from FSU transfer

continuously to shore handling

- Focus on BOG preservation

& minimize power consumption

- FSU el power from shore system

LNG FSU for LNG import to Malta

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2 off Aux steam boilers

(existing boilers decommissioned)

5 off LNG feed pumps

LNG feed header & cargo piping conversion

LNG (MLA) and BOG (hoses) manifold to shore

LNG and BOG manifold

to LNGC via hoses (LNG loading)

SSL system

Quick release hooks towards

offloading LNGCHose/man-riding crane

FSU vs LNGC

IAS upgrade

LNG FSU for LNG import to Malta

• Continuous LNG flow to shore: 10 to 150 m3/h

• LNG pressure to shore: 5 to 9 barg

• New LNG feed pumps @ 55 m3/h in each of 5 tanks

• New dedicated LNG feed header to port side manifold

• LNG loading from LNGCs moored in SBS configuration stbd side

• LNG loading not interrupting LNG nor BOG feeding to shore

• Max LNG transfer rate about 4,500 m3/h

• LNG loading to FSU typically each 1->2 months

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LNG systems: LNG transfer to shore and LNG loading to FSU

LNG FSU for LNG import to Malta

• LNG transfer to shore by DN150 loading arm installed on jetty. Back-up LNG transfer by DN250 hose.

• BOG transfer to shore by DN250 hoses x 2

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LNG & BOG transfer to shore

LNG FSU for LNG import to Malta

• LNG transfer from LNGC by DN250 flexible hoses, 3 off liquid and 1 off vapor.

• All hose equipment handled by FSU.

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LNG loading to FSU

LNG FSU for LNG import to Malta

• Tank safety relief valves setting increased to 0.70 kg/cm2g to minimise BOG generation during loading. Increased pressure demonstrated feasible by tank strength calculations.

• LNG vessel max BOG rate 0.20%/day, equal to abt 4.5 tonnes/h of BOG.

• All BOG normally handled by onshore systems; is transferred by freeflow or compressor from FSU. BOG is further compressed up to pipeline pressure by 3 off reciprocating compressors located on shore.

• FSU back-up BOG handling by new aux steam boilers dumping

• FSU is normally receiving electrical power from shore

• FSU back-up power generation by diesel generators

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FSU Boil-Off Gas (BOG) handling & FSU powergen

LNG FSU for LNG import to Malta

During normal operation, the BOG can be transferred to shore by free flow. In case of higher BOG flows, during LNG loading, it may be required to start one FSU cargo compressor to transfer the BOG at required rate and delivery pressure.

Two BOG compressor systems operating in series – centrifugal + recip

- The impact on operational stability / control of the two compressor systems was evaluated.

- The onshore reciprocating type compressors create pressure pulsations in the piping back to the FSU -> it was required to evaluate that the estimated pulsations are within acceptable limits.

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BOG handling

LNG FSU for LNG import to Malta

• FSU storm mooring system:

The FSU will be shifted abt 60-70 meters away from the jetty in case of inclementweather, and will be staying at a «storm mooring system».

All LNG/BOG transfer to shore and shore power is disconnected!

Wrt BOG handling this means that primary BOG handling equipment are the new aux steam boilers only (which have limited burning/dumping capacity).

Following this, a study of the estimated pressure increase in cargo tanks during this condition was carried out as input to the class and flag state evaluations and acceptance.

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A special challenge in BOG handling for this FSU....

LNG FSU for LNG import to Malta

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Questions?

Thank you for your time!