Dynamic simulation of LNG loading, BOG generation, and BOG recovery at LNG exporting terminals

Liquefied natural gas (LNG) is a prominent clean energy source available in abundance. LNG has high calorific value, while lower price and emissions. Vapors generated from LNG due to heat leak and operating-condition-changes are called boil-off gas (BOG). Because of the very dynamic in nature, the rate of BOG generation during LNG loading (jetty BOG, or JBOG) changes significantly with the loading time, which has not been well studied yet. In this work, the LNG vessel loading process is dynamically simulated to obtain JBOG generation profiles. The effect of various parameters including holding-mode heat leak, initial-temperature of LNG ship-tank, JBOG compressor capacity, and maximum cooling-rate for ship-tank, on JBOG profile is studied. Understanding JBOG generation would help in designing and retrofitting BOG recovery facilities in an efficient way. Also, several JBOG utilization strategies are discussed in this work. The study would help proper handling of BOG problems in terms of minimizing flaring at LNG exporting terminals, and thus reducing waste, saving energy, and protecting surrounding environments.