an inflow stub for delivering a flow of fluid into the interior of a column; and

a deflection unit adjoining a downstream side of said stub to receive and disperse the flow of fluid into the column, said deflection unit including an input zone having at least two stories of inlet passages of constant cross-section extending at least partly into said inflow stub to convey the fluid therethrough, each said story including a central passage and a pair of lateral passages, and a plurality of curved guide lamellae extending from said input zone into the column to form diffuser-like passages for diffusing the flow of fluid from said lateral passages laterally and circumferentially of the column and the flow of fluid from said central passages downwardly of the column.