High-efficient boil-off gas storage using low-temperature activated carbon adsorption

Abstract

Boil-off gas (BOG) leakage poses significant challenges during LNG storage and transportation, since it leads to resource waste, environmental damage, and safety risks. Compared with widely used cryogenic re-liquefaction in BOG recovery, low-temperature adsorption has attracted increasing attention due to relatively low equipment investment and energy consumption. This work aims to investigate the feasibility of cryogenic adsorption for BOG recovery. Biomass-derived coconut shell activated carbon materials for low-temperature methane adsorption are prepared, and their BOG recovery performance are systematically investigated. Results indicate that KOH activated coconut shell activated carbon (CHCS-KOH) has higher specific surface area (1710.28 m²/g) and optimal microporous structure for methane adsorption, achieving a remarkable methane adsorption capacity of14.37 mmol/g at the cryogenic temperature of 133 K, which is rarely reached in previous test. A modified D-A model is successfully fitted for the first time to describe methane adsorption across a wide temperature range from 133 K to 293 K. Based on CHCS-KOH, a BOG adsorption recovery system is established and its performance is analyzed. The optimal storage temperature is determined to be 160 K and minimum recovery energy consumption is 0.5645 kW h/kg with a recovery rate of 89.47 %. These findings may provide new methods for the research on low temperature methane adsorption and BOG recovery.