| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 236419 | Powder Technology | 2013 | 8 Pages |
•Nozzle inclination greatly affects jet attrition in fluidized beds.•The optimum inclination is a 60° downward angle.•The 60° angle does not generate more unwanted fines.•A baffle below the attrition jet tip enhances attrition.
The effect of nozzle inclination for a supersonic nozzle in the attrition process is investigated in this study. The aim is to determine the optimal nozzle inclination angle to give the highest grinding efficiency. A high velocity Laval-type nozzle was used and the nozzle was adjusted from 0° to 90°. Particle size analysis was also conducted to monitor the generation of fine particles, and the grinding of coarse particles.It is found that more new particle surface was generated at nozzle inclinations over 45°. The optimal nozzle inclination is determined to be 60°, as it not only created the most new particle surface, but also ground more coarse particles without generating more unwanted fines. A baffle was inserted downstream of the jet tip for the nozzle inclination of 60° to test its effect. The experimental result has shown that more new particle surface area was obtained with the baffle, as the baffle was able to densify the local bed region near the jet tip and enhance particle attrition.
Graphical abstractNew particle surface created vs. attrition nozzle inclination angle (with baffle inserted for the 60° case). The most efficient attrition in a fluidized bed can be achieved with a downward supersonic attrition nozzle with a 60 degree angle with the horizontal plane. Inserting a baffle further improves the performance.Figure optionsDownload full-size imageDownload as PowerPoint slide
