Energy-Efficient Helium Extraction and Boil-off Gas Recovery from Liquefied Natural Gas Based on Low-Temperature Pressure Swing Adsorption

Helium is widely used in industry, but extraction of it from natural gas remains complex and energy-intensive. This work proposes an energy-saving helium extraction and boil-off gas (BOG) recovery process based on low-temperature pressure swing adsorption (PSA). The integrated scheme combines BOG recovery and compression, crude helium separation, catalytic dehydrogenation and drying, and low-temperature PSA purification using LNG cold energy. BOG is primarily adsorbed and recovered in the first-stage PSA, while helium is enriched and purified through a two-stage low-temperature PSA system, achieving crude helium separation with a helium content above 2.71% and final helium purity up to 99.99%. Numerical energy and exergy analyses show a unit energy consumption of 6.54 kWh/m 3, 21.7% lower than a conventional liquefaction-based process, with cold energy utilization efficiency improved by 21.6%.