Atomizing nozzles
• Function is to control the flow and the pattern of atomizing medium to provide for efficient disintegration of powders
• For a given nozzle design, the average particle size is controlled by the pressure of the atomizing medium and also by the apex angle between the axes of the gas jets
• Higher apex angle lead to smaller particle size
• Apex angle for water atomization is smaller than for gas atomization
• Nozzle design: i) annular type, ii) discrete jet type;
i) free falling, ii) confined design
• In free falling, molten metal comes in contact with atomizing medium after some distance. Here free falling of metal is seen. This is mainly used in water atomization.
• In confined design used with annular nozzle, atomization occurs at the exit of the nozzle. Gas atomization is used generally for this. This has higher efficiency than free falling type. One has to be cautious that “freeze up” of metal in the nozzle has to be avoided.
