Importance

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Abstract

A process for the separation of air to obtain oxygen, nitrogen and argon is disclosed which comprises: subjecting air from which carbon dioxide and water have been removed to fractional distillation in a first column to form oxygen-nitrogen vapor and argon-enriched oxygen; separating argon from the latter in a second column operating at substantially lower pressure than the first; liquefying a portion of the nitrogen vapor in a cycle including heat exchange with incoming air and compression to a pressure above that of the first column, a portion of the liquid nitrogen being taken as product and a second portion being returned to the first column as reflux. Liquid-oxygen and nitrogen vapor from the first column are mixed in a liquid-vapor contact column, impure liquid nitrogen is withdrawn therefrom and used as reflux in the first column. A remixed oxygen-nitrogen stream is withdrawn from the contact column and expanded to create refrigeration for the system. Also, disclosed is apparatus for carrying out the subject process.

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First Claim