Separation of carbon monoxide from nitrogen-contaminated gaseous mixtures

摘要

Carbon monoxide is separated from a gaseous mixture (Figure 2, 1) containing hydrogen and contaminated with nitrogen by separating (7, 10, 21) hydrogen and carbon monoxide contents to provide a carbon monoxide-enriched nitrogen-containing stream (22) and separating carbon monoxide and nitrogen contents of said stream in a nitrogen-separation column (31) to provide a nitrogen-enriched overheads vapour (32) and a nitrogen-freed bottoms liquid (33). The overheads vapour (32) is washed (47) with liquid nitrogen (48) to remove carbon monoxide therefrom and the resultant carbon monoxide-enriched liquid nitrogen is returned to said column as additional reflux. The liquid nitrogen wash (47) simultaneously reduces the loss of carbon monoxide with the nitrogen-enriched vapour and provides refrigeration to the process. When the gaseous feed is a synthesis gas also containing methane, the methane and carbon monoxide contents can be separated (21) before or after separation (31) of the nitrogen and carbon monoxide contents.