| 摘要 |
<p>Cooled and clean air feed is (i) fed into a primary distn. or fractionation column (A) operating at 40-200 psia for sepn. in N2 such vapour and O2 rich liq. (ii) a first portion of the vapour obtd. is recovered as elevated pressure N2 gas and (iii) a reflux liq. provided for column (A); (iv) a first portion of the liq. obtd. in (i) is fed to a secondary column (B) operating at 15-75 psia for sepn. into liq. and vapour fractions. (v) a first portion of the liq. obtd. is withdrawn from (B) and a second portion vapourised to provide reflux vapour for (B). (vi) a vapour stream is withdrawn from (B) at a point above at least one equilibrium stage above the vaporising second liq. portion of (v) and (vii) the stream obtd. is recovered as O2 prod.. - Pref. reflux liq. in (iii) is obtd. by condensing a second portion of N2 rich vapour. Air for (i) is pref. cleaned by passage through a gel trap. Vapour withdrawn in (vi) is pref. further purified prior to recovery e.g. by passage through a catalytic reactor.</p> |
