Boil-Off-Gas (BOG) Management

Liquefied Natural Gas (LNG) is stored and transported in tanks as a cryogenic liquid. Due to a variety of processes at the terminal, LNG continuously evaporates at temperatures above its boiling point generating Boil-Off-Gas (BOG).

BOG must be either removed from the process or recovered back into the system to prevent the over pressurisation of plant equipment and ship storage. The quantity of BOG depends on the design and operating conditions of storage tanks and ship’s cargo tanks.

BOG is generated at the terminal through:

  • Heat leak into Bulk Storage Tanks
  • Mechanical heat input from pumps
  • Displaced vapours during ship offloading
  • Tank equilibrium changes
  • Atmospheric pressure changes
  • Elevation difference between the ship and the bulk tank

OSL has experience in design and engineering of the different options to handle BOG. These include:

  • Routing the BOG to the Non Visible System
  • Compressing the BOG to Export Gas pressure
  • Re-liquefying the BOG through refrigeration and return it to the bulk or ship storage

We also have experience in the design of BOG system equipment including BOG Compressors, BOG Recondenser Columns, send-out Pumps and flare systems.

At OSL we will apply our Clever Thinking® culture to understand and deliver cost effective solutions to challenges associated with the generation of BOG in LNG transportation and storage, and to optimise the management of BOG produced across the different units throughout the system.

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