LNG is a cryogenic fluid contained in tanks, which can be of a different type either pressurized or atmospheric. The conservation of the energy contained in the LNG, depends upon the type of tank and its insulation, but, in any case, the LNG will start boiling as soon as its temperature will start increasing, originating the BOG (Boiling Off Gas).
In the LNG trade, BOG has a significant impact as LNG is sold at the receiving terminal depending on its energy content. Since the BOG reduces the quantity of cargo delivered and increases the heat value of the LNG in the ship tank, the quantity of BOG is of economic evaluation, especially for Oil & Gas companies. Furthermore, given that BOG typically constitutes one-third of the shipping costs, the ability to monitor and manage BOG on LNG carriers strongly points to potential savings.
LNG is composed of several components of varying volatility, each having its own pure component boiling point at any given pressure. The presence of other volatile components in a mixture affects the boiling temperature of all the components in the mixtures.
The reduction and handling of the BOG are a key issue in the LNG shipping industry.