Method and apparatus for reboiling a liquefied gas mixture

Abstract

A liquefied gas mixture comprising at least two components of which one is more volatile than the other or others is boiled in an apparatus including stripping passages for vaporising part of a flow of the mixture. The passages are arranged alternately with condensing passages. The stripping passages each have at least one heat exchange surface which is heated to a temperature which causes the liquid to boil and along which the liquefied gas mixture flows in countercurrent mass exchange relationship with a vapour flow evolved from such liquid. The more volatile component is progressively stripped from the liquefied gas mixture such that the vapour flow is enriched in its direction of flow in the more volatile component and the mixture itself is depleted of the more volatile component in its direction of flow. Accordingly, separation of the mixture takes place in addition to its boiling. The apparatus can be employed as a reflux condenser for an argon distillation column connected to a lower pressure column of a double column air separation unit. Condensation in such apparatus can be effected while separating oxygen-rich liquid produced in a higher pressure column. The products of such separation can then be introduced into the lower pressure column to reduce the separation work that would otherwise have to be performed in the lower pressure column.