Abstract
Until recently, LNG carriers have been equipped with steam propulsion systems. Boil-Off Gas (BOG) is then fired in the steam generating plant by dual fuel burners. When the amount of BOG is greater than required for propulsion, excess steam is dumped into the main condenser of the steam turbine and cooled down. The main condenser is sized accordingly. This dumping facility is not available for LNG carriers with alternative propulsion systems, however. New ship designs thus require a safe and economical BOG treatment when there is no other use for the gas. Venting to the atmosphere is not considered acceptable for environmental and safety reasons.
