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Abstract
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A cryogenic-based module is developed for the separation of the hydrogen from a feed gas mixture
including nitrogen and linear branched or cyclic C1 C6 hydrocarbons. The feed gas mixture is initially
separated in a network of heat exchangers and phase separators to produce hydrogen-rich and
hydrogen-lean streams. The hydrogen-enrich stream is extracted from the cryogenic separation heat
exchangers and the hydrogen-lean stream is processed through the cryogenic sections to remove non-
hydrogen components and produce aromatic, low pressure, and high-pressure fuel streams. A Joule-
Bryton propane refrigeration cycle and an auxiliary nitrogen refrigeration stream supply the required
cryogenic streams. The process is energy and exergy analyzed and results show that the more than 88.4%
of exergy destruction occurred in heat exchangers and the valves have the least role in exergy
destruction. Moreover, sensitivity analysis shows that when the mole fraction of hydrogen in feed gas
increases by 60.0%, the specific energy decreases by 38.0%, the required power increases by 68.6%, the
exergy efficiency reduces by 58.3%, and the required heat increases by 60.0%. As well as, when the
pressure of stream 23 increases by 10%, the reduction of exergy efficiency is 9.2%, the promotion of
specific energy is 3.0%, the reduction of hydrogen recovery rate is 0.08%, and the increase of nitrogen
refrigeration capacity is 10.60%. Therefore, a comprehensive view is needed to change the operational
parameters to achieve the desired results. The proposed module may be combined with many other gas
upgrading systems.
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