Annular divided wall column for an air separation unit having a ring shaped support grid

An annular divided wall column, 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 ring-shaped support grid having an outer annular edge member, a plurality of rigid bars radially disposed within the ring-shaped support grid and connecting the outer annular edge member, and a plurality of arcuate support ribs, each arcuate support rib attached to at least one of the rigid bars;
• the ring-shaped support grid disposed in the annulus column region with the outer annular edge member rigidly attached to the first annular column wall and the ring-shaped support grid being unattached to the second 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 ring-shaped support grid and the first annular column wall in the radial and axial directions;
• and
• a plurality of structured packing elements disposed on the ring-shaped support grid within the annulus column region.