Gas distribution device for the supply of a processing gas with adjustable flow direction to an atomizing chamber

A gas distribution device for supplying a processing gas to an atomizing zone around an atomizing device arranged centrally in an atomizing chamber, comprising a horizontal spiral supply duct for said processing gas, said duct having an annular mouth extending in rotational symmetry around the axis of the chamber, and two conical guide walls extending around and above the atomizing device, said guide walls limiting a space communicating with said mouth, guide vanes being provided in said mouth for imparting a change of direction to the gas stream from a mainly purely tangential flow in the spiral duct into a rotating flow with a smaller tangential velocity component in the space between the conical guide walls, wherein the improvement comprises two separate sets of stationary vanes positioned relatively close to and overlying each other in the mouth, one of said sets being shaped to deflect the gas stream stronger to a direction with a considerably lower tangential velocity component than the other set and a damper being arranged along the mouth to be adjustable in the height direction for controlling the ratio of the portions of the gas stream in the spiral duct conducted into each of the two vane sets.