Annular divided wall column for an air separation unit

An annular divided wall column for cryogenic rectification of air or constituents of air, said column comprising:

• a first annular column wall;
• a second annular column wall radially spaced from the first annular column wall and disposed within a first interior space of the first annular column wall to define an annulus column region between the first annular column wall and the second annular column wall and to define an interior core column region as part or all of a second interior space of the second annular column wall;
• a conical shaped transition wall connected to the second annular column wall proximate a top end of the second annular column wall and further connected to the first annular column wall and configured to isolate the annulus column region from the interior core column region proximate the top end of the second annular column wall;
• a plurality of structured packing elements of a first type or trays disposed within the interior core column region;
• and
• a plurality of structured packing elements of a second type disposed within the annulus column region;
• wherein the conical shaped transition wall is either:
• (i) fixedly attached to the second annular column wall proximate the top end of the second annular column wall and moveably hung on the first annular column wall;
• or (ii) moveably connected to the second annular column wall proximate the top end of the second annular column wall and fixedly connected to the first annular column wall;
• and
• wherein thermal expansion and contraction of the second annular column wall in a radial direction and in an axial direction is independent of the thermal expansion and contraction of the first annular column wall in the radial direction and in the axial direction.