JPS6279844A - Gas diffusion plate for fluidized bed synthesizing apparatus - Google Patents

Abstract

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.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an improvement in a gas distribution plate provided in a fluidized bed synthesis apparatus for synthesizing powder.

[L row 19 In synthesis using the fluidized bed method, an important technique is to uniformly synthesize the powder while rapidly circulating the powder using high-temperature blown gas.

A conventional fluidized bed synthesis apparatus has a structure as shown in FIG. That is, a gas dispersion plate 3 having a large number of holes 2 is provided at the lower part of the side wall 1.

, the mouth is v? While trying - brush However, this gas distribution plate 3 is a flat plate.

For example, when a blowing gas such as N2 is blown into the powder in the synthesis chamber 4 in the direction of the arrow through the gas distribution plate 3, an upward backflow occurs in the center of the synthesis chamber 4, and a downward flow near the side wall 1. becomes.

For this reason, the powder tends to accumulate in the lower part of the side wall 1 to form an immovable part 5, and the powder in the synthesis chamber 4 as a whole does not circulate well, resulting in a problem that synthetic powder of uniform quality cannot be produced.

11 Tragedy 1 This invention was made to solve the above-mentioned problems, and provides a gas dispersion plate for a fluidized bed synthesis apparatus that can circulate the entire powder in a synthesis chamber well and obtain a uniform synthetic powder. The purpose is to

SUMMARY OF THE INVENTION To achieve this object, the present invention provides a gas dispersion plate for a fluidized bed synthesis apparatus in which the central part is thick and the peripheral part is thin and mountain-shaped in a fluidized bed production apparatus for producing silicon nitride powder using a silica reduction method. The gist is:

Part 2 of Question 4: The gas distribution plate 7 is thick in the center and has a peak at the center 8, and the peripheral part 10 is thin and has a mountain shape.

f ITI The ejection force of the gas ejected from the gas distribution plate 7 is
This causes a strong circulation of powder in the direction of the arrow in Figure 1. Therefore, the powder 12 at the bottom of the side wall 6 moves easily and does not form an immovable part. Furthermore, since the gas distribution plate 7 has an inclination, the powder 12 in the lower part of the synthesis chamber 13 will flow along the inclination, and since there is a circulation flow B in the opposite direction to the flow, the powder 12 will rise due to the circulation flow. , no immobile part of the powder 12 occurs.

Reference numeral 6 in FIG. 1 is the side wall of the composite layer. A gas distribution plate 7 is attached to the lower part of this side wall 6.

The gas distribution plate 7 has a chevron shape as shown in FIG. However, the central part 8 is thick and has a peak 9, and the peripheral part 10 is thin. The gas distribution plate 7 has a large number of holes 11 formed in the height direction. This gas distribution plate 7
The inclination angle θ is in the range of 10 to 50'.

In use, as a raw material, for example, granulated silica/carbon/silicon nitride powder 12 is placed in a synthesis chamber 13 and heated to, for example, 1400° C. by a heat source (not shown). Then, for example, high-temperature N2 gas may be blown into the synthesis chamber 13 through the hole 11 of the waste dispersion plate 7 as shown by the arrow.

The direction of the circulating flow of the powder 12 at this time is as shown by the arrow in FIG. The ejection force of the gas ejected from the gas distribution plate 7 is stronger in the peripheral portion 10 where the length of the hole 11 is shorter. Therefore, the powder 12 at the bottom of the side wall 6 moves easily. The movement of the powder is a -F backflow in the center 8 of the synthesis chamber 13 and a downward flow near the side wall 6, but the overall movement is rapid because there are no stationary parts.

Furthermore, since the gas distribution plate 7 has an inclination, the powder in the lower part of the synthesis chamber 13 flows along the inclination, and since there is a circulating flow B in the opposite direction to that flow, the circulating flow moves the upper back and the immovable part. Don't let it happen.

By the way, if the inclination angle O of the gas distribution plate 7 is smaller than 10°, no difference in gas ejection force between the central portion 8 and the peripheral portion 10 will appear. In addition, since the powder does not flow along the slope shown in (E) above, there is no effect of eliminating the immobile part.

Moreover, when the inclination angle θ is larger than 50°, the length of the hole 11 becomes long and the gas jetting force of the central portion 8 is lost, making it difficult to generate a circulating flow of the powder 13 as a whole.

Note that this invention is not limited to the above-described embodiments.

As described in detail, according to the present invention, the entire powder is circulated well and a uniform synthetic powder can be obtained.

[Brief explanation of drawings]

Fig. 1 is a front view showing a fluidized bed synthesis apparatus showing an embodiment of the gas dispersion plate of the present invention, Fig. 2 is a perspective view of the gas dispersion plate, and Fig. 3 is a diagram showing a conventional gas dispersion plate. It is a cross-sectional view showing a fluidized bed synthesis apparatus. ,,peripheral part 11,,,,hole 12,,,,powder 13,,,,synthesis chamber Fig. 1 Fig. 2 Fig. 3

Claims (2)

[Claims] (1) A gas dispersion plate for a fluidized bed synthesis device that is thick at the center and thin at the periphery to form a mountain shape in a fluidized bed manufacturing device for silicon nitride powder using the silica reduction method. (2) The gas distribution plate of the fluidized bed synthesis apparatus according to claim 1, wherein the inclination angle is 10 to 50 degrees.