Patent ID: 8535638

Claim:
A process for recovering hydrogen and carbon dioxide from a process stream ( 1 ) of a process unit ( 0 ), the process stream ( 1 ) containing at least carbon dioxide, hydrogen and methane, and the process comprising the steps of: a) optionally compressing the process stream ( 1 ) in a first compressor ( 2 ); b) cooling the process stream ( 1 ) in a heat exchanger ( 3 ) to a temperature equal to or less than −10° C.; c) separating and purifying the cooled process stream ( 1 ) in a carbon dioxide separation unit ( 4 ) to produce a carbon dioxide rich liquid stream ( 6 ) and a carbon dioxide lean non-condensable stream ( 5 ); d) withdrawing the carbon dioxide rich liquid stream ( 6 ) as carbon dioxide product for further use; e) withdrawing the carbon dioxide lean non-condensable stream ( 5 ) from the carbon dioxide separation unit ( 4 ) and passing the carbon dioxide lean non-condensable stream ( 5 ) through a hydrogen selective membrane separation unit ( 7 ) to form a hydrogen rich permeate stream ( 8 ) with the remaining components in the carbon dioxide lean non-condensable stream ( 5 ) forming a hydrogen lean residue stream ( 9 ); f) passing the hydrogen lean residue stream ( 9 ) through a carbon dioxide selective membrane separation unit ( 10 ) to form a carbon dioxide enriched permeate stream ( 11 ) with the remaining components in the hydrogen lean residue stream ( 9 ) forming a carbon dioxide depleted residue stream ( 12 ); and g) optionally compressing the hydrogen rich permeate stream ( 8 ) in a second compressor ( 13 ) and recycling the hydrogen rich permeate stream ( 8 ) for use as a supplemental feed stream in the process unit ( 0 ) or in other processes, recycling the carbon dioxide enriched permeate stream ( 11 ) to the process stream ( 1 ) prior to the compressor ( 2 ) or within the compressor ( 2 ) between stages of compression, or to the carbon dioxide separation unit ( 4 ) and withdrawing the carbon dioxide depleted residue stream ( 12 ) for further use.