Parametric Analysis on Boil-Off Gas Rate inside Liquefied Natural Gas Storage Tank

Abstract

Research into the environmental effect of greenhouse emissions is now intense. One of the sources contributing to the effect is boil-off gas (BOG) flaring into the atmosphere. BOG formation is caused by heat leakage from the liquefied natural gas (LNG) storage tank. Heat leakages are determined by the effectiveness of heat thermal transmittance of the structural tank and ambient condition. The objective of this present study is therefore to determine the relationship between heat thermal transmittance and ambient condition, and the boil-off rate for a specific 40,447m3 LNG tank size corresponding to a 160,000m3 LNG ship size. General estimations of the amounts of BOG generated are useful in determining the amount of BOG that will need to flare in order to control the greenhouse effect and the amount of pollution entering the environment. This study analyzes both the steady and unsteady behavior of heat transfer mechanisms using ANSYS Fluent software. Results show that dynamic transient simulation only takes effect on the first five days of a voyage. There is then a linear relationship between the investigated parameters of the boil-off rate of LNG. These linear relations are of the utmost use for LNG tank manufacturer and researchers requiring a preliminary view in order to determine LNG tank specification. The result obtained is also validated by studies by previous researcher.

Keywords

• liquefied natural gas
• boil-off gas
• heat transfer
• greenhouse emission
• pollution