CROSS-REFERENCE TO RELATED APPLICATIONSNot applicable.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot applicable.BACKGROUND OF THE INVENTIONIn a process to effect the cryogenic separation of air into at least a nitrogen-enriched product and an oxygen-rich product, it is necessary to essentially remove the carbon dioxide and other impurities (e.g., water and hydrocarbons) present