Process on or with liquid

A method of carrying out a process on or with a liquid comprising the steps of (1) introducing the liquid into a chamber bounded by a vertically disposed tubular wall above a horizontal annular fluid inlet to the chamber, and the (2) passing fluid upwardly through an annular array of inclined vanes spanning said annular fluid inlet such that the fluid supports a bed of the liquid above the vanes and moves the bed in a compact band continuously circulating along an annular path above the vanes as the fluid passes through the bed with circumferential and vertical flow components.