Method and apparatus for cryogenic separation of a mixture containing at least carbon monoxide, hydrogen and nitrogen

A method for the cryogenic separation of a mixture containing at least carbon monoxide, hydrogen and nitrogen, the method comprising the steps of:

• introducing the mixture, in liquid form, to the top of a stripping column under conditions effective for separation therein to form a hydrogen-lean liquid and a hydrogen-enriched gas;
• introducing the hydrogen-lean liquid or a fluid derived from the hydrogen-lean liquid to a nitrogen-removal column under conditions effective for separation therein to form a carbon monoxide-enriched liquid and a nitrogen-enriched gas containing the majority of the nitrogen present in the mixture;
• and
• determining if the nitrogen content of an identified stream(s) selected from the group consisting of the mixture, the nitrogen-enriched gas, and combinations thereof is/are below a respective threshold(s),
• selectively introducing at least part of the hydrogen-enriched gas coming from the stripping column to an intermediate point of the nitrogen-removal column based on the nitrogen content of the identified stream.

A method for the cryogenic separation of a mixture comprising carbon monoxide, hydrogen and nitrogen, the method comprising the steps of:

• introducing the mixture, in liquid form, to the top of a stripping column under conditions effective for separation therein to form a hydrogen-lean liquid and a hydrogen-enriched gas;
• and
• introducing the hydrogen-lean liquid or a fluid derived from the hydrogen-lean liquid to a nitrogen-removal column under conditions effective for separation therein to form a carbon monoxide-enriched liquid and a nitrogen;
• selectively increasing a flow rate of incondensables introduced to the nitrogen-removal column based on the nitrogen content within the nitrogen removal column, wherein the incondensables comprise hydrogen from the hydrogen-enriched gas.