Abstract: A processing gas is supplied to the atomizing zone around an atomizing device arranged centrally in an atomizing chamber through a conical guide duct communicating with a horizontal spiral supply duct through an annular mouth. A uniform gas distribution with respect to flow direction and velocity is obtained by means of guide vanes arranged with a small angular spacing in the mouth and comprising two succeeding vane sets, in which the vanes of one set are shaped to deflect the tangential gas stream in the spiral duct to a flow direction, for which the radial velocity component considerably exceeds the tangential component, whereas each vane of the other set positioned at the opening of the mouth towards the conical guide duct projects into the space between neighboring vanes of the first set and extends substantially parallel to tangential planes to said vanes at their internal edges.

Abstract: A processing gas is supplied to the atomizing zone around an atomizing device arranged centrally in an atomizing chamber through a conical guide duct communicating with a horizontal spiral duct through an annular mouth. A gas distribution incorporating a simple and accurate adjustment of the deflection of the gas stream from the spiral duct into the conical guide duct is obtained by means of two separate sets of stationary guide vanes arranged relatively close to and overlying each other in the mouth, one of said sets being constructed to deflect the gas stream stronger than the other set to a direction with a considerably smaller tangential velocity component, 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.