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Floating LNG
Plant Technology

Jangkrik Gas FPU
Source : http://skkmigas.go.id/

A floating LNG production plant shall play an important role in energy production.

A floating LNG (FLNG) or a floating production, storage and offloading unit (LNG-FPSO), is an LNG plant constructed on a ship or a barge which has LNG storage and shipment (offloading) facilities. The FLNG/LNG-FPSO accomplishes the gas treatment and liquefaction (production of LNG) from the natural gases produced in offshore gas fields, and the storage/offloading of product LNG to LNG carriers for ocean transportation.

The advantages of FLNG / LNG-FPSO compared with onshore LNG plant are (a) to reduce the length of subsea pipelines that need to be built from the offshore gas fields, (b) to reduce the environmental impact since FLNG/LNG-FPSO does not require the coastal development, and (c) to be built in fabrication yards where facilities and practices are well-established for construction without constraints of the countries or regions of the gas field or onshore LNG plant, which secures the efficiency and the safety of construction.

As the market seeks lower-priced LNG plants with shorter delivery in response to weak LNG prices associated with the recent fall in oil prices, Chiyoda is focusing on new approaches and innovative ideas for FLNG / LNG-FPSO. For example, Chiyoda provides low-priced, mid-scale FLNG with shorter delivery, by converting used LNG carriers into FLNG. Chiyoda also provides new LNG liquefaction processes which enable safe and stable operation with a lower capital cost, and proposes an appropriate process selection in compliance with various customer requirements.

In addition, to ensure the safety of operators in the limited space on a ship, Chiyoda applies FLNG safety design and analysis methods for accidents inside a plant, such as explosions, fires or leakages.
Chiyoda has experiences not only in engineering and constructing a number of onshore LNG plants, but also in engineering FLNGs and in constructing offshore plants. Chiyoda quickly responds to changing demands by taking advantage of these expertise and continuing to develop and introduce new technologies.

Key business and technology

Chiyoda is proposing the realization of safer FLNG or LNG-FPSO with lower cost and shorter delivery by combining the following technologies.

1. Selection of a liquefaction process appropriate for the scale of FLNG

e.g.) Chiyoda can adopt a liquefaction process that does not use liquid refrigerants for a 0.5 - 2 million ton-class FLNG in annual production.

Benefits

  • A storage system of liquid refrigerants is unnecessary.
  • A production facility or an import facility for liquid refrigerants in a floating plant is unnecessary.
  • The total volume of flammable substances can be significantly reduced since the quantity of liquid refrigerants possessed in a floating plant is limited.
  • The risk of cryogenic refrigerants leakage is limited.
  • The size is more compact and the weight is lighter than FLNG that uses liquid refrigerants.

2. Selection of appropriate construction method for FLNG

Generally speaking, it takes time to construct the hull and LNG storage systems for FLNG newly built. Therefore the topsides plant is divided into several blocks (modules) and fabricated in land in parallel with the hull fabrication and integrated on the hull deck.
The method can minimize the works at the integration, achieve the low cost and shorten duration of the construction by such Modular Method.

In case of the conversion of used ship, it takes shorter duration to construct the hull and LNG storage systems, the smaller modules and or pieces of equipment may be installed directly on the deck. The duration of the construction can be squeezed efficiently by such Hybrid Method.

The other method experienced in the construction of a floating gas processing plant is Skidding Method, which may be applied when huge construction space is available. The plant is constructed on the large skid and shifted to the hull coming alongside the quay.
The optimum method aforementioned for FLNG construction can be recommended to select as per the circumstance of the project.

3. Safety design and analysis

An accident that would likely cause major damage to FLNG is a leakage of LNG and liquid refrigerants. If structures and hull of FLNG, which are mainly made of carbon steel, are accidentally exposed to released LNG and liquid refrigerants, a low temperature embrittlement of those materials could occur. In addition, if released LNG and/or liquid refrigerants are vaporized and ignited, an explosion could occur. Explosions in FLNG could generate high overpressures and cause serious damage to facilities as space on FLNG is limited and facilities are congested. Furthermore, if an accident occurs, personnel on FLNG facility need to evacuate in a worst-case scenario.
In addition to taking measures to minimize a leakage of LNG and liquid refrigerants, Chiyoda performs the following analysis and design taking into consideration the case that a leakage of LNG and liquid refrigerants occurs.

Cryogenic spill protection

Spill of LNG and liquid refrigerants is modelled by Computational Fluid Dynamics (CFD). Based on the results from CFD modelling, thermal insulations, water curtains and other measures are taken where necessary.

Explosion hazard mitigation

Dispersion and explosion of vaporized LNG and liquid refrigerants after the leakage are modelled by Computational Fluid Dynamics (CFD). Safety gaps are allocated between facilities to reduce the explosion overpressure, and structures on FLNG are designed to be blast-resistant.

Escape route arrangement

Escape routes are arranged so that personnel on FLNG facility can access at least two escape routes from anywhere on FLNG facility, and can move to a point of embarkation such as helideck or lifeboat boarding area.

4.Application of LNG Carrier Conversion FLNG concept

This concept does not require a new construction of hull and LNG storage systems by converting a used LNG carrier as well as adding an LNG plant on this converted LNG carrier, which enables to minimize the construction of hull and LNG storage systems and realize shorter delivery and lower cost than a new FLNG construction.

Key projects

1. Chiyoda’s recent experiences of FLNG / Floating Units

You can scroll horizontally to see it.

PROJECTCLIENTLOCATIONSCOPEAWARD
(Confidential) (Confidential) (Confidential) Concept 2017
(Confidential) (Confidential) (Confidential) Concept 2016
(Confidential) (Confidential) (Confidential) Pre-FEED 2016,17
(Confidential) (Confidential) Australia Pre-FEED 2015,16
Coral FLNG Eni East Africa S.p.A Mozambique FEED 2014
Jangkrik FPC Eni Muara Bakau B.V. Indonesia FEED
EPCI
2012
2014
Scarborough FLNG Esso Australia Resources Pty.Ltd. Australia Pre-FEED
Optimization Study
2012
2013
Abadi FLNG INPEX MAsela,Ltd. Indonesia FEED 2013
Petrobras FLNG Petrobras Netherlands B.V. Brazil FEED
Pre-EPC
2009
2011

2. Jangkrik Floating Production Unit Project for Eni Muara Bkau B.V.

The following photo is not an FLNG, but shows a floating gas processing plant at the time of sail away. The plant was completed in 2017 by a joint venture company which Chiyoda set up with a partner. Chiyoda is also promoting the engineering and construction of floating gas processing plants in addition to FLNG.

Outline :

Floating gas processing plant (separation and production of gases and condensate)

Location :

angkrik and Jangkrik North (70km offshore East Kalimantan, Water Depth 450m), Indonesia

Source: http://skkmigas.go.id/