Method for generating carbon monoxide from synthesis gas
Carbon monoxide is generated carbon monoxide, in a conversion stage (DR), from a hydrocarbon-containing feed ( 1, 2 ), and also steam and/or carbon dioxide (CO 2 ), resulting in the formation of a carbon monoxide (CO)—, hydrogen (H 2 )— and methane (CH 4 )-containing synthesis gas ( 3 ). The synthesis gas is subsequently fed to a fractionation device (Z) for separating off at least one hydrogen-rich fraction ( 7, 9 ) and one methane-rich fraction ( 10 ) and also a carbon monoxide product ( 6 ). The methane-rich fraction ( 10 ) separated off in the fractionation device (Z) is recirculated as feed (M feed) upstream of the conversion stage (DR).
1 . A method for generating carbon monoxide, in a conversion stage, said method comprising:
introducing a hydrocarbon-containing feed, and steam, carbon dioxide (CO 2 ), or a combination of steam and carbon dioxide to said conversion stage;
generating in said conversion stage a carbon monoxide (CO)—, hydrogen (H 2 )— and methane (CH 4 )-containing synthesis gas, and feeding said synthesis gas to a fractionation device;
removing from said fraction a device at least one hydrogen-rich fraction ( 7 ), at least one methane-rich fraction ( 10 ), and a carbon monoxide product; and
recycling at least a portion of said methane-rich fraction ( 10 ) separated off in the fractionation device (Z) as feed (M feed) to said conversion stage (DR).
2 . A method according to claim 1 , wherein CO 2 ( 4 ) is removed from said synthesis gas ( 3 ) and recirculated by means of a CO 2 recycle compressor (V 1 ) to a point upstream of said conversion stage (DR).
3 . A method according to claim 1 , wherein monoxide product ( 6 ) is separated from said synthesis gas ( 5 ) in a methane scrubber.
4 . A method according to claim 1 , wherein recirculation of methane fraction ( 10 ) to a point upstream of the conversion stage (DR) is carried out by means of a methane recycle compressor (V 2 ).
5 . A method according to claim 2 , wherein said at least a portion of said methane fraction ( 10 ) to a point upstream of the conversion stage (DR) is carried out by means of said CO 2 recycle compressor (V 1 ).
6 . A method according to claim 3 , at least a portion of excess liquid methane is vaporized within said methane scrubber by supply of heat and under pressure and is recirculated as M feed ( 10 ) upstream of the conversion stage (DR), the pressure increase being of a size such that solely on account of the pressure drop building up the M feed ( 10 ) flows back to the inlet side of the conversion stage (DR).
7 . A method according to claim 1 , said conversion stage is an externally-fired conversion stage (DR).
8 . A method according to claim 1 , wherein at least a part ( 8 ) of the hydrogen-rich fraction ( 7 ) is recirculated to the conversion stage (DR) from the fractionation device (Z).