Onboard Reliquifaction for LNG Ships (eBook)

Published Date

January 2005

Onboard Reliquifaction for LNG Ships (eBook)

(Excludes any applicable taxes)

This paper describes a BOG re-liquefaction system developed by Tractebel Gas Engineering (TGE) and the operations and economics of implementing the scheme onboard a 200,000 m³ ship(10pp)

Be the first to review this product

LNG is transported at near atmospheric pressure and low temperatures (approx. –160 °C) over long distances. During the voyage a proportion of the LNG is vaporized by heat ingress in the cargo containment system. The cargo tanks are well insulated with, typically, 270mm cryogenic insulation but some heat inleak producing boil-off gas (BOG) is inevitable. Typical values are about 0.1 to 0.15% of the full contents per day, which over a 21 day voyage, becomes a significant amount.

Ships have employed gas compression and use of the boil-off gas as fuel for the propulsion systems. Until now LNG carriers have been equipped with steam turbines powered by heavy fuel oil (HFO) and/or LNG BOG. However, designers of new larger ships are seeking more economic propulsion solutions.

This paper describes the process concept for a BOG re-liquefaction system developed by Tractebel Gas Engineering (TGE), the operating experience of such a process and preliminary economics of implementing the scheme on board a ship having a capacity greater than 200,000 m³ LNG.

The process described in this paper considers BOG re-liquefaction with a capacity of approximately 6,500 kg/h of BOG, which is sufficient to maintain tank pressure for a carrier of 228,000 m³ capacity. In reality, the boil-off gas rates are somewhat smaller, but the unit must be able to deal with peak rates to bring the tank pressure down and also be able to deal with LNG cargoes having relatively high nitrogen concentrations.

Paper Delivered by:
Dr. K-D.Gerdsmeyer (Tractebel Gas Engineering)
W.H.Isalski (Tractebel Gas Engineering)

Prepared for:
Gastech Bilbao 2005

For over 45 years, the Gastech Exhibition & Conference has been at the forefront of the international gas and LNG market. This world-renowned event is regarded as the most significant meeting place for gas and LNG professionals, where the global industry gathers to do business.

Gastech hosts major IOCs, NOC’s, global utility companies, EPC contractors, shipbuilders, pipeline companies, manufacturers, distributors, technology and service providers, all who play an active role in the global energy value chain.

Title: Onboard Reliquifaction for LNG Ships (eBook)
Product Code: 4433g086
Published Date: January 2005

Bought this product? Why not review it?

If you have a question about this product, please contact us directly.

Windows eBooks:


To access the eBook, you need to install our free Windows eBook Reader.

The application can be downloaded from:



Standalone eBooks are supplied with 1 licence + 1 backup and are not transferable between platforms.


Remote Desktop Services (Terminal Services) and virtual environments are not supported.


The Windows eBook Reader works with Windows XP or later OS (but not Windows RT).

See more details.


Cloud (online) eBooks:


The Cloud (online) eBooks use Microsoft Silverlight browser plugin to deliver the best possible reading experience with the ability to work in offline mode.


It is an annual subscription service (i.e. each eBook is purchased for 1 year of use).

Online licences are not transferrable to Windows or iPad (or vice-versa).


Silverlight is compatible with the major web browsers used on Windows and Mac OS X operating systems.

However it is not supported on Linux, Android, Windows RT and iPad devices and therefore the Cloud eBooks use an HTML site in these instances.

The HTML site is more restricted than the Silverlight version.


See https://www.microsoft.com/silverlight/what-is-silverlight and more details.


Note for Mac Users:


Mac users can read Windows eBooks with Boot Camp or using virtual machines such as Parallels Desktop, Virtual Box, ...

Alternatively, Cloud (online) eBooks are accessible on Mac, including the Silverlight plugin with offline mode.


Note for Linux Users:


Linux users can read Windows eBooks using a virtual PC.

Alternatively, the HTML version of the Cloud (online) eBooks is accessible.


Note for Tablet Users:


Tablets owners can use the HTML version of the Cloud (online) eBooks.