JP2001158629A - Method and device for heating fine powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for heating fine powder, especially the fine powder having a particle diameter of <=75 μm, by which the fine powder can be treated in a large amount and by which the temperature histories of the particles are uniformed, respectively, and to provide a device therefor. SOLUTION: This method for thermally treating the fine powder, comprising feeding the fine powder D into a particulate dispersion medium-charging zone C, carrying the fine powder with pulsed air flow charged from the lower portion of the charging zone C to lift the fine powder at a speed of 10 to 100 cm/sec, and simultaneously thermally treating the fine powder, characterized by lifting the fine powder through divided routes, bundling the divided routes to form at least three units, and uniformly heating the units with heated gas flows jetted from the sides.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for heat-treating a fine powder, particularly a fine powder having a particle size of 75 .mu.m or less, in a large amount and uniformly.

[0002]

2. Description of the Related Art For heating relatively large size powder,
A rotary kiln is generally used because a large amount and continuous processing can be performed. However, a particle size of 75
When this is used for fine powders such as μm or less, particles are not smoothly moved, so that it is not possible to heat evenly, dust is generated, and it is difficult to handle industrially, There are many issues to solve.

Therefore, a fluidized-bed furnace using sand as a dispersion medium is mainly used for heating such fine powder.
For example, as a method of producing a fine hollow glass sphere by heating a fine powder of volcanic vitreous sediment, a pulsating air flow is introduced from below a dispersion portion filled with solid glass spheres and silica sand, and dispersed. The fine powder supplied above the part is 10-100c
A method is known in which the sheet is conveyed at a speed of m / sec and foamed in a foaming section heated to 900 to 1100 ° C (Japanese Patent Application Laid-Open No. 8-73232).

FIG. 4 is a cross-sectional view for explaining an apparatus used in the conventional method, and FIG. 5 is a cross-sectional view showing the structure of the dispersion layer. This apparatus has a built-in dispersion layer C filled with a glass solid sphere 9 and silica sand 8 on a perforated plate 7, and a dispersion chamber A having a raw material supply port 2 opened above the dispersion layer C. And an upright cylindrical heating furnace B connected to the upper part thereof, and the heating furnace B has a focusing tube structure 3 in which 3 to 20 thin tubes are focused.

According to the conventional method, fine powder D is conveyed from a hopper 1 by a screw feeder, supplied from a raw material supply port 2 to a dispersion chamber A, and pulsated from a pulsating air flow inlet 5 below the dispersion layer C. The powder is dispersed in the dispersion layer C by an air flow, is heated from the surroundings by a focusing tube 3 disposed in a heating furnace B above the dispersion layer C, foams, and then a powder outlet 4 is formed.
Taken out of At this time, if necessary, air is introduced from the air inlet 6 provided on the side wall or upper part of the heating furnace B,
Recovery can be facilitated. However, the method using such an apparatus has a limited amount of processing and cannot be scaled up, and is therefore unsuitable as an industrial method requiring a large amount of processing.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to heat a fine powder, particularly a fine powder having a particle diameter of 75 μm or less, in a large amount and to make the temperature history of each particle uniform. The present invention has been made to provide a method and an apparatus capable of producing a product of equal quality.

[0007]

The present inventors have conducted various studies on a method and an apparatus for heat-treating a fine powder uniformly and in large quantities. As a result, the inventors have found that the method using the apparatus shown in FIGS. By arranging at least three focusing tubes in a heating furnace and arranging a combustion burner so that the individual fine powder rising in these focusing tubes is uniformly heated, uniform heating is performed. The present inventors have found that large-scale processing can be performed, and have accomplished the present invention based on this finding.

That is, according to the present invention, a fine powder to be treated is supplied onto a granular dispersion medium filling zone, and the fine powder is carried by a pulsating air flow fed from below the filling zone to form a 10 to 100 cm.
In a method of performing heat treatment while increasing the speed at a rate of 1 / sec, the fine powder is raised along divided paths, and these divided paths are converged to at least 3
A fine powder heating method, wherein each unit is uniformly heated by a heating gas flow injected from the side, and a built-in granular dispersion medium packed layer, and above the packed layer In a fine powder heating apparatus comprising: a dispersion chamber A having an open fine powder supply port 2; an upright cylindrical heating furnace B airtightly connected to the upper part of the dispersion chamber A; and heating means for the heating furnace B, At least three upright focusing tubes 3 each having a plurality of narrow tubes bundled in the upright cylindrical heating furnace B are arranged in parallel, and a plurality of injection-type combustion burners 11 are eccentrically arranged at appropriate positions on the wall surface of the heating furnace. In addition, the present invention provides a fine powder heating apparatus characterized in that the heating means is attached at substantially equal intervals.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the structure of a method according to the present invention. FIG. 1 is a schematic longitudinal sectional view showing one example of the apparatus of the present invention, and FIG. 2 is a transverse sectional view taken along the line XX. The raw material fine powder D is supplied from a hopper 1 to an upper part of a dispersion chamber A by a screw feeder. Are supplied to the dispersion chamber A through the supply port 2 provided in the heating chamber B, and rise from the dispersion chamber A through the plurality of upright focusing tubes 3,. Taken out of

The dispersion chamber A has the same structure as that of the conventional apparatus. A dispersion layer C is formed by filling granular dispersion media 8, 9 such as silica sand or glass solid spheres on the upper part of a perforated plate 7. A pulsating air flow inlet 5 is provided below the dispersion layer C.

The heating furnace B comprises an upright cylindrical main body B 'and a conical top B ". The top of the conical top B" is open and an exhaust port 10 is provided. A plurality of injection-type combustion burners 11,... Are mounted eccentrically at substantially equal intervals on the middle wall surface of the upright cylindrical body B 'of the heating furnace. Here, the eccentric radial means that the injection direction of each of the combustion burners 11,... Is a concentric circle a having a diameter smaller than the diameter of the circle of the cross section of the heating furnace main body, as shown by the dashed line in FIG.
Refers to the state of being attached so as to match the tangent line of.

By arranging the combustion burners 11, the fine powder D rising in each of the upright focusing tubes 3,... Arranged in parallel in the heating furnace B is uniformly heated. Is done. The rising speed of the fine powder D in each of the upright focusing tubes 3 is selected within a range of 10 to 100 cm / sec. The heating temperature of the fine powder D depends on the purpose of the treatment, but is usually in the range of 500 to 1300C, preferably 900 to 1100C.

Each of the upright focusing tubes 3,... Comprises a plurality of focusing tubes 12, as shown in FIG. 3, and at least three, preferably 10 to 10 focusing tubes are provided in the heating furnace.
Twenty of them are erected and installed in parallel. The above-mentioned pipes 12 are each formed of an elongated pipe having an inner diameter of 10 to 20 mm, and 10 to 30 pieces are bundled.
Fine powder D heat-treated in heating furnace B having such a structure
Are collected from the upper outlets of the respective bundles through the discharge pipes 13,..., Taken out from the discharge ports 4, and collected.

[0014]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 In this example, volcanic glassy sediment (produced in Iizaka-machi, Fukushima City, commonly known as Fukushima Shirato) was crushed as a raw material powder, and 10 μm was obtained.
Powders of 10-30 μm classified by m and 30 μm were used. The ratio of particles exceeding 30 μm contained in the raw material powder is 15% by weight or less, and the particle diameter is 10 μm.
The proportion of particles less than 15% by weight.

The raw material powder was supplied to the heating device shown in FIG. This heating device has an exhaust port 10 at the center upper part of the heating furnace, and 18 focusing tubes 3,... In a cylindrical vertical furnace installed so that the flow of hot air is rotated by gas burners 11,. Are installed separately.

First, the raw material powder is put into a hopper 1 and silica sand 4 sized to a particle size of about 200 μm is placed on a perforated plate 7.
A dispersion layer C having a cross-sectional area of 475 cm ² filled with 75 g is supplied by a screw feeder at a rate of 10 kg per hour, and pulsating air having a pulsation rate of 30 times / second is supplied from the lower part of the dispersion layer at a rate of 0.855 m ³ per minute. Sent at a rate. The particles thus dispersed were lifted through 18 vertically installed focusing tubes. Each focusing tube was configured by bundling 19 elongated tubes each having an inner diameter of 13.3 mm. The maximum temperature inside this focusing tube is gas burner 11,
... was adjusted and kept at 1000 ° C.

In order to cool the heated air and the foam, and to suppress the condensation of water in the foam recovery section, air was introduced from the air inlet 6 at the upper part of the heating furnace. The introduction amount was adjusted by adjusting the flow rate of a suction blower directly connected to the foam recovery section. The formed foam was recovered, and its density and strength were measured. As a result, a volcanic glassy foam having a bulk density of 0.50 g / cm ³ , a particle density of 0.85 g / cm ³ , a coarse particle content of 1.5% by weight, and a strength of 90.6% by weight was obtained. In addition, this strength represents the content ratio of the non-destructive particles after holding for 1 minute under the hydrostatic pressure of 8 MPa.

[0019]

According to the present invention, a large amount of fine powder having a particle size of 75 μm or less can be heat-treated uniformly.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of an example of the device of the present invention.

FIG. 2 is a transverse sectional view taken along line XX of FIG. 1;

FIG. 3 is a cross-sectional view of the focusing tube of the present invention.

FIG. 4 is a schematic vertical sectional view of a conventional example.

FIG. 5 is a cross-sectional view of a dispersion layer in a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Hopper 2 Raw material supply port 3 Upright focusing tube 4 Powder discharge port 5 Pulsating air flow inlet 6 Air intake 7 Perforated plate 8, 9 Granular dispersion medium 10 Exhaust port 11 Combustion burner 12 Pipe 13 Discharge pipe A Dispersion chamber B Upright cylindrical heating furnace C Dispersion layer D Fine powder

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kunio Kimura 218-34, Kayakata-cho, Tosu-shi, Saga Prefecture (72) Inventor Yoshitada Nemoto 2-24-47, Wild-nest, Higashi-ku, Fukuoka City, Fukuoka Prefecture (72) Inventor Shigeru Kanamaru 589, Kamo, Inazuki-cho, Kaho-gun, Fukuoka

Claims (2)

[Claims] 1. A fine powder to be treated is supplied onto a granular dispersion medium filling zone, and is carried by a pulsating air flow fed from below the filling zone, and is raised at a speed of 10 to 100 cm / sec. Meanwhile, in the heat treatment method, the fine powder is raised by the divided paths, and the divided paths are converged to form at least three units, and each unit is heated by a side jet. A fine powder heating method characterized by heating uniformly by a gas flow. 2. A dispersion chamber which contains a granular dispersion medium packed layer and has a fine powder supply port opened above the packed bed, an upright cylindrical heating furnace airtightly connected to the upper part of the dispersion chamber, and And a heating means for the furnace, wherein at least three upright converging tubes each comprising a plurality of thin tubes converged in the upright cylindrical heating furnace are arranged in parallel, and A fine powder heating apparatus characterized in that a plurality of injection-type combustion burners are eccentrically mounted at appropriate positions at substantially equal intervals as heating means.