| 摘要 |
<p>Method for producing liq. nitrogen comprises (a) passing a feed of nitrogen and methane into a column and sepg. the feed into a nitrogen-enriched vapour and a methane-enriched liq.; (b) withdrawing the nitrogen-enriched vapour from the column and increasing the pressure of the vapour to produce pressurised nitrogen-enriched vapour; (c) condensing the pressurised nitrogen-enriched vapour by indirect heat exchange with methane-enriched liq. to produce liq. nitrogen; (d) subcooling the liq. nitrogen by indirect heat exchange with cold vapour; and (e) recovering the resulting liq. nitrogen as product. The method also includes (i) providing a stream contg. nitrogen, methane and helium, sepg. this stream into a first fluid enriched in nitrogen and methane and into a second fluid enriched in helium, employing the first fluid as the feed passed into the column, and employing the second fluid as the helium-contg. vapour; and (ii) partially condensing the second fluid, by indirect heat exchange with methane-enriched liq., and employing the resulting vapour as the helium-contg. vapour, and passing the resulting liq. into the column.</p> |
