Analysis of discharging characteristics of the storage system by adsorption for boil off gas (BOG) from onboard LNG

Abstract

In observation of efficiently utilizing the boil off gas (BOG) from onboard liquefied natural gas (LNG), storage by adsorption is employed to construct an auxiliary system for fuel storage. A typical LNG powered ship was selected, and the storage by adsorption system was designed as per the amount of BOG released during the process of charging and that from daily evaporation on the LNG storage tank. Researches were conducted experimentally and numerically on a 1 L conformable vessel typically designed for adsorbing BOG. Verification of the accuracy of the results from simulations was performed by comparing the data recorded during the charging and discharging process of methane on the vessel packed with one kind of commercially available activated carbon SAC-01 (S_BET = 1507 m²·g⁻¹). Simulations were conducted further to evaluate the performance of the vessel respectively filled with activated carbon AX-21, HKUST-1, MIL-101(Cr), MOF-5. It shows that the mean relative error between the data from simulations and the experimental data is less than 5%. Results also reveal that, within the flow rates range in correspondence with the fuel consumed by the model ship's power unit under its typical working conditions, the mean temperature fluctuation within the vessel is the weakest while packing HKUST-1, which results in the largest accumulated amount of discharge. It suggests that HKUST-1 is a suitable adsorbent for storage by adsorption of BOG from on board LNG.