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

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