The present invention relates to a column (1) for thermal treatment of fluid mixtures, having a cylindrical, vertical column body (2) which forms a column cavity (3), a plurality of trays (8) mounted with vertical spacing in the column cavity (3), and a support construction (9) which supports at least one of the trays (8) in vertical direction. It is a characteristic feature of the inventive column (1) that the support construction (9) has a plurality of orifices (12) which allow horizontal mass transfer through the support construction (9). The invention further relates to a tray device for such a column and to a thermal separation process between at least one gas ascending within such a column (1) and at least one liquid descending within the column (1).