Integrated hydrogen liquefaction processes with LNG production by two-stage helium reverse Brayton cycles taking industrial by-products as feedstock gas

Hydrogen-rich industrial by-products, such as coke oven gas (COG) and synthetic ammonia exhaust tail gas, are often simply utilized as fuel gas, or even not utilized at all in many cases. An innovative and efficient utilization method is proposed and investigated in this paper. Aiming to coproduce liquid hydrogen and liquefied natural gas (LNG), three helium reverse Brayton cycles are constructed, opti-mized, analyzed and compared. The LN-He-1 process is constructed with reference to conventional in-dustrial hydrogen liquefaction processes, but with different feedstock gas. The LN-He-2 and N-He processes, which are an improvement on the basis of LN-He-1. A combination of distillation and flash is utilized to reduce the separation load. Analysis of load variation, power consumption, exergy, heat transfer and turbomachinery efficiencies are carried out. For different feedstock gas compositions, the specific power consumptions of LN-He-1, LN-He-2 and N-He processes are within 26.45-54.78 kWh/ kmol (feedstock gas), 26.32-53.78 kWh/kmol (feedstock gas) and 21.94-50.42 kWh/kmol (feedstock gas), respectively. The exergy efficiencies are between 13.0% and 66.5%. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This paper proposes an innovative and efficient method utilizing hydrogen-rich industrial by-products to coproduce liquid hydrogen and liquefied natural gas. Three helium reverse Brayton cycles are constructed and optimized, with specific power consumptions ranging from 21.94-54.78 kWh/kmol and exergy efficiencies between 13.0% and 66.5%.