| abstract |
1. A cryogenic distillation process for the production of oxygen and nitrogen, which comprises:n a) cooling at least a fraction of a cleaned and dried feed stream (10) containing at least oxygen and nitrogen and introducing the same into a high pressure column (13), and separating the same into nitrogen-rich stream at the top of the column and an oxygen-rich stream at the bottom of the column, wherein the overhead of the high pressure column exchanges heat with both the bottom of the low pressure column (19) and the bottom of an intermediate column (28), b) introducing at least a fraction of the oxygen-rich stream (2) into said intermediate column to afford a top liquid fraction A (32) and a bottom liquid fraction B (21), the overhead of the intermediate column exchanging heat (29) with the low pressure column at a location above the bottom reboiler (30) of the low pressure column, wherein the pressure of the intermediate column is lower than the high pressure column but higher than the low pressure column, c) introducing at least a fraction of the liquid fractions A and B into the low pressure column as feed, d) feeding at least a fraction of the nitrogen-rich stream (22) of step b) to the low pressure column as reflux, and e) recovering an oxygen-rich stream (25) product at the bottom of the low pressure column and a nitrogen-rich stream (24) at the top of the low pressure column. |