| 摘要 |
PURPOSE:To satisfactorily circulate powder and to obtain uniformly synthesized powder with a fluidized bed type apparatus for producing silica reduction method silicon nitride powder by forming a gas diffusion plate to a peak shape which is thick in the central part and thin in the peripheral part. CONSTITUTION:The gas diffusion plate 7 is constituted to the peak shape which is thin in the central part 8, has a peak 8 and is thin in the peripheral part 10. Many holes 11 are provided in the height direction thereof. The angle theta of inclination thereof is preferably in a 10-50 deg. range. The powder 12 (e.g.: granular silica particles, etc.) is charged into a synthesizing chamber 13, then gas (e.g.: gaseous N2, etc.) is blown through the holes 11 of the plate 7, by which the circulation flow of the powder 12 like arrows is made. The ejection force of the gas from the plate 7 is stronger nearer the peripheral part 10 where the length of the holes 11 is shorter; therefore, the powder 12 in the lower part of a side wall 6 moves easily. Since the plate 7 has the inclination, the flow along the inclination arises in the powder in the lower part of the chamber 13 and since there is the circulating flow B in the direction opposite from said flow, the flow is raised by the circulating flow and the generation of immobile parts is obviated. |
