Method and apparatus for producing nitrogen by cryogenic distillation of air

摘要

In a method for producing nitrogen by cryogenic distillation, air containing carbon monoxide is sent to a cryogenic distillation column (5), a flow D of nitrogen is taken from the top of the distillation column, with a CO content less than a fixed value S1, and a flow of nitrogen-rich cryogenic liquid coming from an external source (7) is sent to the top of the column, the flow rate of cryogenic liquid sent to the column being less than a value V if the CO content in the air does not exceed a previously defined threshold (S0), and the flow rate of cryogenic liquid sent to the column being greater than a value V if the carbon monoxide content of the air exceeds this previously defined threshold (S0).

主权项

1. A method for producing nitrogen by cryogenic distillation of air, the method comprising the steps of:
analyzing a carbon monoxide content of an air stream; sending the air stream to a cryogenic distillation column; taking a flow D of nitrogen from the top of the distillation column, the flow D of nitrogen having a CO content less than a fixed value S1; and sending a flow of nitrogen-rich cryogenic liquid coming from an external source to the top of the cryogenic distillation column, the flow rate of the nitrogen-rich cryogenic liquid sent to the cryogenic distillation column being less than a value V if the CO content in the air stream does not exceed a previously defined threshold, wherein the flow rate of the nitrogen-rich cryogenic liquid sent to the cryogenic distillation column is greater than a value V if the carbon monoxide content of the air stream exceeds this previously defined threshold.