Air disperser for a spray dryer and a method for designing an air disperser

aleThe air disperser includes an air inlet, a pipe defining an air outlet area equipped with one or more atomizers, an outer wall and a space defined by the pipe wall and the outer wall of the air disperser. The space has a plurality of guide vanes (-) positioned substantially vertically in the axial direction and substantially on the radii between the pipe wall and the outer wall of the air disperser. At least one of the guide vanes is covering at least 90% of the full radius from the pipe wall in the direction towards the outer wall of the air disperser, and the rest of said guide vanes being distributed on radii along the circumference of the pipe.