| 摘要 |
Air is separated in a main rectification column comprising a higher pressure column, a lower pressure column and a condenser-reboiler replacing the higher pressure column in heat exchange relationship with the lower pressure column. A first liquid oxygen fraction concentrated in krypton and xenon is formed at the bottom of the lower pressure column and is withdrawn through outlet. Argon-oxygen separation takes place in the column and a vaporous argon-oxygen stream depleted of krypton and xenon is taken from the outlet as it is subjected to further rectification in a column, a second liquid oxygen fraction containing argon impurity being obtained. A stream of the second liquid oxygen fraction is withdrawn from the column through the outlet and is purified in the column so as to obtain a purified oxygen product.
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