A spray drying apparatus comprising a drying chamber and atomizing means, comprising at least one gas disperser for guiding gas into the drying chamber, said gas disperser comprising an inlet duct section with an upstream end and a downstream end, and with an internal diameter defining a cross-sectional area, the inlet section defining an axial direction (axd), a radial direction (rdd) and a tangential direction (tgd), and a flow conditioning device (5, 6) located in the inlet duct section, characterized in that said flow conditioning device comprises at least one hole plate having a diameter substantially corresponding to the internal diameter of the inlet duct section and defining a cross-sectional area substantially corresponding to the cross-sectional area of the inlet duct section, and at least one flow straightener having a diameter substantially corresponding to the internal diameter of the inlet duct section and defining a cross-sectional area substantially corresponding to the cross-sectional area of the inlet duct section, that the at least one flow straightener is positioned substantially in parallel with and at a distance (h) in the axial direction (axd) from the downstream side of the at least one hole plate, that said at least one hole plate is provided a plurality of holes distributed over substantially the entire cross-sectional area of the hole plate, each hole preferably having a cross-sectional dimension in the same order of magnitude as the hole plate thickness (tp), that the ratio between the total area of the holes and the area of the hole plate lies in the range 0.2 to 0.8, preferably about 0.5, that the flow straightener is provided with a plurality of flow channels, each having a longitudinal extension in parallel with the axial direction (axd), that each hole plate has a predefined hole plate thickness (tp) in the axial direction (axd) and each flow straightener has a predefined flow straightener length (Is) in the axial direction (axd), the flow straightener length (ls) being substantially larger than the hole plate thickness (tp), and that the flow straightener length (Is) is larger than the hole plate thickness (tp) by a factor in the range 5 to 200, preferably 10 to 150. an inlet duct section with an upstream end and a downstream end, and with an internal diameter defining a cross-sectional area, the inlet section defining an axial direction (axd), a radial direction (rdd) and a tangential direction (tgd), and a flow conditioning device (5, 6) located in the inlet duct section, characterized in that said flow conditioning device comprises at least one hole plate having a diameter substantially corresponding to the internal diameter of the inlet duct section and defining a cross-sectional area substantially corresponding to the cross-sectional area of the inlet duct section, and at least one flow straightener having a diameter substantially corresponding to the internal diameter of the inlet duct section and defining a cross-sectional area substantially corresponding to the cross-sectional area of the inlet duct section, that the at least one flow straightener is positioned substantially in parallel with and at a distance (h) in the axial direction (axd) from the downstream side of the at least one hole plate, that said at least one hole plate is provided a plurality of holes distributed over substantially the entire cross-sectional area of the hole plate, each hole preferably having a cross-sectional dimension in the same order of magnitude as the hole plate thickness (tp), that the ratio between the total area of the holes and the area of the hole plate lies in the range 0.2 to 0.8, preferably about 0.5, that the flow straightener is provided with a plurality of flow channels, each having a longitudinal extension in parallel with the axial direction (axd), that each hole plate has a predefined hole plate thickness (tp) in the axial direction (axd) and each flow straightener has a predefined flow straightener length (Is) in the axial direction (axd), the flow straightener length (ls) being substantially larger than the hole plate thickness (tp), and that the flow straightener length (Is) is larger than the hole plate thickness (tp) by a factor in the range 5 to 200, preferably 10 to 150.