Estimating Boil-Off Gas Generation in Industrial Cryogenic Storage Tank during Unloading Operations Using CFD Models

Using this model, we compare the BOG generation during unloading against a baseline holding-mode operation. Our results demonstrate that top-unloading leads to a significant (up to 18×) increase in BOG generation due to flashing of the incoming LNG. Further, initial tank pressure is identified as the dominant controlling parameter; in contrast, the initial LNG level and density exhibit only a weak influence on the boil-off rate (BOR).

A correlation has been established between tank pressure and BOR, with an 8.3% decrease in BOR for every 10 kPa increase in tank pressure. This correlation can serve as a practical tool for estimating BOR under various unloading conditions and provides recommendations to operators for managing BOG effectively, thereby minimizing flaring and energy consumption.