Mass transfer assembly and column with dividing wall and methods involving same

A mass transfer assembly for use in an open internal region within a mass transfer column, the mass transfer assembly comprising:

• a dividing wall forming first and second sub-regions on opposite sides of the dividing wall;
• one or more zones of mass transfer structures positioned in the sub-regions on the opposite sides of the dividing wall;
• and
• a vapor flow restrictor positioned in the first sub-region and moveable between a first orientation that causes a first vapor flow resistance through the first sub-region and a second orientation that causes a second vapor flow resistance through the first sub-region that is greater than the first vapor flow resistance to allow an adjustment of a volumetric split of vapor when ascending through the first and second sub-regions on the opposite sides of the dividing wall,
• wherein the vapor flow restrictor comprises a tray having a tray deck and vapor flow apertures in the tray deck, and wherein when the vapor flow restrictor is in the first orientation a total open area of the vapor flow apertures is less than the total open area of the vapor flow apertures when the vapor flow restrictor is in the second orientation.