World Scale Boil-off Gas Reliquefaction

Fuels and Petrochemicals Division
AIChE Spring Meeting and Global Congress on Process Safety
April 30, 2013 - 2:00pm-2:30pm
Boil-off gas reliquefaction has become an industry standard for many LNG carriers, which no longer use gas as fuel for steam boilers, but tap others energy sources to generate power for propulsion. Well known examples are the ships of the Q-Flex and Q-Max class. Most of these vessels use simple nitrogen expander cycles with relatively high energy consumption (typically 800 kWh/t) and a moderate capacity of about 200 t/d LNG liquefaction.

Increasing LNG demand in Asia, especially in Japan after the nuclear catastrophe triggered innovative ideas to increase the LNG output of existing liquefaction plants. Boil-off gases and ship return gases from LNG tank farms have been identified quickly as promising source for additional LNG, as these gases are perfectly suitable for cryogenic processing. Obviously, dehydration and sweetening is not required. However, low pressure, low temperature and elevated nitrogen content pose challenges to an efficient design.

Linde Engineering has developed an innovative concept for a world scale boil-off gas reliquefaction unit with 0.5 to 1.0 mtpa capacity, which includes the following features:

  • Boil-off gas compression starting from cryogenic conditions up to a transcritical pressure level
  • Mixed refrigerant cycle with two heat exchanger bundles
  • Load balancing between feed gas and refrigerant cycle compressors
  • Nitrogen rejection into the gas turbine fuel gas with a double flash process
  • Use of identical gas turbines as mechanical drive

Details of this concept and rejected alternatives will be discussed in depth in the full paper.

Professional Development Hours
0.5 PDHs
You will be able to download and print a certificate for these PDH credits once the content has been viewed. If you have already viewed this content, please click here to login.

Would you like to access this content?

No problem. You just have to complete the following steps.

You have completed 0 of 2 steps.

  1. Log in

    You must be logged in to view this content. Log in now.

  2. Purchase Technical Presentation

    You must purchase this technical presentation using one of the options below.
    If you already purchased this content recently, please click here to refresh the system's record of ownerships.


Credits 0.5 Use credits
List Price $25.00 Buy now
AIChE Members $15.00 Buy now
AIChE Fuels and Petrochemicals Division Members Free Free access
AIChE Undergraduate Student Members Free Free access
AIChE Graduate Student Members Free Free access
Related Topics: