Abstract:

Taking methane-hydrogen off-gas by-produced from C₂ recovery unit using shallow-cool oil-absorption technology of two domestic refineries as research objects, two schemes for the recovery and utilization of methane-hydrogen off-gas were designed, and the hydrogen yield, consumption, energy consumption, investment of the two schemes are compared. Scheme 1 is Membrane Separation + VPSA process, and scheme 2 is VPSA process. The results show that the energy consumption and investment of scheme 1 is lower for methane-hydrogen off-gas with low hydrogen and high nitrogen produced from C₂ recovery unit, which uses catalytic dry gas as feedstock. The energy consumption of scheme 1 could be further reduced by considering that the exhaust gas of membrane separation can be generated by expander to recover energy. For the methane-hydrogen off-gas with high hydrogen and low nitrogen produced from C₂ recovery unit using hydrogenation dry gas as feedstock, the energy consumption and investment of scheme 2 are lower. However, if the tail gas after H₂ recovery is considered as feedstock of hydrogen production unit, scheme 1 is more advantageous.

Key words: C₂ recovery unit, methane-hydrogen off-gas, membrane separation, VPSA, low hydrogen and high nitrogen, high hydrogen and low nitrogen

摘要：

以国内某两个炼油厂碳二回收装置副产的甲烷氢尾气为研究对象，对甲烷氢尾气的回收利用设计了两种方案，并重点在氢气收率、消耗、能耗、投资等方面进行了比较。方案一为膜分离+真空变压吸附(VPSA)工艺，方案二为VPSA工艺。结果表明：对以催化干气为原料的碳二回收装置副产的低氢高氮甲烷氢尾气，采用方案一时能耗和投资更低，且若通过膨胀机发电回收膜分离尾气能量还可以进一步降低方案一的能耗；对以加氢干气为原料的碳二回收装置副产的高氢低氮甲烷氢尾气，采用方案二时能耗和投资更低，但若考虑提氢尾气全部升压作制氢装置原料，则方案一更有优势。

关键词: 碳二回收装置, 甲烷氢尾气, 膜分离, VPSA, 低氢高氮, 高氢低氮