| 摘要 |
<p>A method of nitrogen isotope concentration which includes a step in which raw-material nitrogen containing oxygen and argon in slight amounts is distilled at a low temperature with packed columns constituted in a cascade arrangement to thereby obtain product nitrogen in which stable nitrogen isotope 15N has been concentrated. An argon/oxygen mixture is discharged from the bottom of the final column and an 15N-concentrated nitrogen fluid is taken out of the final column through a lower middle part thereof. Simultaneously therewith, the flow rate of the argon/oxygen mixture to be discharged from the bottom of the final column is controlled based on the reading of a thermometer disposed below the position where the product 15N-concentrated nitrogen is taken out. The method of nitrogen isotope concentration thus enables the product nitrogen to be stably obtained.</p> |
