| 摘要 |
This invention concerns a method for recovering carbon monoxide and carbon dioxide from Fischer-Tropsch off-gas by feeding Fischer-Tropsch off-gas through a column comprising an adsorbent bed, and discharging effluent, optionally rinsing the column and the adsorbent bed by feeding NG and discharging effluent until at least 60% of the carbon monoxide that was present in the bed is discharged, pressurizing the column and adsorbent bed with NG, rinsing the column and the adsorbent bed by feeding NG until at least 50% of the carbon dioxide present at the commencement of this rinsing step is discharged, rinsing the column and adsorbent bed by feeding a mixture of hydrogen and nitrogen, pressurizing the column and adsorbent bed by feeding a mixture of hydrogen and nitrogen. With this method a feed comprising at least 50 vol % carbon monoxide can be produced. Furthermore, methane and carbon dioxide at a high pressure can be recovered from the Fischer-Tropsch gas. This can be fed to a gasifier or a reformer. In a preferred embodiment a gas comprising at least 80 vol % hydrogen is produced as well. |
| 主权项 |
1. A method for recovering carbon monoxide and carbon dioxide from a gas mixture comprising 5-50 vol % methane, 10-50 vol % carbon dioxide, 20-65 vol % carbon monoxide, 10-40 vol % hydrogen and 10-55 vol % nitrogen, calculated on the total volume of the gas mixture, said method comprising, in sequence, the following steps:
(1) feeding a gas mixture through a column comprising an adsorbent bed,
said gas mixture comprising 5-50 vol % methane, 10-50 vol % carbon dioxide, 20-65 vol % carbon monoxide, 10-40 vol % hydrogen and 10-55 vol % nitrogen, calculated on the total volume of the gas mixture, the adsorbent bed comprising alumina, a carbon molecular sieve, silicalite, activated carbon, a zeolite, or mixtures thereof,
with upon commencement of said feeding, the bed and column being pre-saturated and pre-pressurized to a pressure in the range of 10 to 80 bar absolute (bar a) with pure hydrogen, or with a mixture of hydrogen and nitrogen, anddischarging effluent from the other end of said bed, andcontinuing said feeding and said discharging until a carbon monoxide comprising gas has reached at least 45% of the length of the bed and has reached at most 80% of the length of the bed, calculated from the end of the bed at which the gas mixture is being fed; and (2) ceasing the feeding of the gas mixture comprising 5-50 vol % methane, 10-50 vol % carbon dioxide, 20-65 vol % carbon monoxide, 10-40 vol % hydrogen and 10-55 vol % nitrogen, and reducing the pressure in the column and the bed by about 5 to 25 bar a; and (3) rinsing the column and the adsorbent bed by feeding a gas comprising at least 70 vol % methane through the column and adsorbent bed,
the column and bed being at a pressure in the range of 5 to 75 bar a, anddischarging effluent from the other end of said bed, andcontinuing said feeding and said discharging until at least 60% of the carbon monoxide that was present in the bed at the commencement of this rinsing step is discharged from the other end of said bed; (4) pressurizing the column and adsorbent bed by about 5 to 25 bar a by feeding a gas comprising at least 70 vol % methane, (5) rinsing the column and the adsorbent bed by feeding a gas comprising at least 70 vol % methane through the column and adsorbent bed,
the column and bed being at a pressure in the range of 30 to 80 bar a, anddischarging effluent from the other end of said bed, andcontinuing said feeding and said discharging until an amount equal to at least 50% of the carbon dioxide that was present at the commencement of this rinsing step is discharged from the other end of said bed; and (6) ceasing the feeding of a gas comprising at least 70 vol % methane and reducing the pressure of the column and adsorbent bed to a pressure in the range of 15 to 25 bar a; and (7) further reducing the pressure of the column and adsorbent bed to a pressure in the range of 1 to 5 bar a; and (8) rinsing the column and adsorbent bed by feeding a mixture of hydrogen and nitrogen through the column and adsorbent bed
the column and bed being at a pressure in the range of 1 to 5 bar a, and (9) pressurizing the column and adsorbent bed to a pressure in the range of 15 to 75 bar a by feeding a mixture of hydrogen and nitrogen. |
