Feasibility Analysis of Typical Cryogenic Processes for Hydrogen-Mixed Natural Gas Separation

Hydrogen energy is a crucial carrier for the growth of the energy system and its low-carbon transformation. Using natural gas as a carrier of hydrogen transport and the natural gas pipeline network for transportation is a significant step toward realizing large-scale and long-distance hydrogen transport. Hydrogen-mixed natural gas is mainly separated into hydrogen and natural gas by physical methods at present. High purity of hydrogen recovery, but the recovery rate is low. At the same time, compared with natural gas, liquefied natural gas is more economical and flexible. This study analyzes three typical cryogenic separation processes. The results show that the hydrogen separation efficiency and specific energy consumption increase and the liquefaction rate and energy consumption decrease as the hydrogen ratio increases. The energy consumption and specific energy consumption of C3-MRC are lower than the MRC and the cascade liquefaction processes. Besides, as the pressure increases in the C3-MRC liquefaction process, the liquefaction and hydrogen separation efficiency increase and subsequently drop. Different hydrogen content has the highest hydrogen separation efficiency and liquefaction efficiency under different feed gas pressure conditions. The total exergy losses of the C3-MRC are the least in different hydrogen fractions, which are 37.59% and 21.77% less in the 25% hydrogen fraction, and 37.89% and 21.37% less in the 30% hydrogen fraction. Moreover, the exergy efficiency of C3-MRC are 87.68% and 88.06% when the hydrogen fraction are 25% and 30%, higher than the other two processes, which implies that in 25% and 30% fractions, making it more suitable for separate the hydrogen by the cryogenic separation. © 2023, Tech Science Press. All rights reserved.