JPH10325532A - Method and apparatus for melting powder - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To efficiently melt and process powders
Provided is a method and an apparatus for melting a granular material capable of controlling the particle size of the molten particles. SOLUTION: Flame flows from a plurality of burners 2 and 3 are made to collide with each other, and a raw material powder is charged into a combustion flame of at least one of the plurality of burners to perform a melting process.

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 melting a granular material, and more particularly, to a method and an apparatus for melting a granular material suitable for producing inorganic spheroidized particles and melting treatment of incinerated ash. About.

[0002]

2. Description of the Related Art Conventionally, inorganic spheroidized particles have been produced by melting and passing an inorganic powdery raw material into a combustion flame of a burner,
Incineration ash generated by incineration of municipal solid waste, sewage sludge, and other waste is melted (Japanese Patent Application Laid-Open Nos. 58-14563 and 7-1903).
No. 28, etc.).

[0003] In the melting treatment of the above-mentioned powdery and granular materials, the powdery and granular materials are usually conveyed to a burner by a carrier gas, ejected from the tip of the burner together with fuel or a supporting gas, and proceed in the same direction as the combustion flame. Then, after the surface temperature rises due to radiant heat transfer from the combustion flame and convective heat transfer, the temperature inside the particles rises due to heat conduction, and the particles are melted. Therefore, in order to completely melt the granular material, it is necessary to appropriately set the velocity distribution and temperature distribution of the combustion flame depending on the structure of the burner in accordance with the melting temperature and the particle size of the granular material. is there.

On the other hand, in such a melting method, when the supply amount of the granular material per unit time is increased, the sensible heat and the latent heat for heating the granular material are removed from the combustion flame. The temperature of the flame decreases, making it difficult to melt the powder. For this reason, the conventional one has a limit in the processing amount of the granular material per unit time.

Further, when the particles collide with each other due to a speed difference caused by a particle size difference between the powders, the particles are fused and coalesced with each other to generate a molten particle having a large particle size. However, it was not intended to actively obtain large-diameter particles.

Accordingly, an object of the present invention is to provide a method and an apparatus for melting a granular material, which can efficiently melt the granular material and control the particle diameter of the molten particles.

[0007]

In order to achieve the above object, the present invention provides a method for melting granules, the method comprising: charging raw granules into a combustion flame of a burner; In the method of melting the powders and granules to be performed, the flame streams from the plurality of burners are collided with each other, and the raw powders and granules are charged into the combustion flame of at least one of the plurality of burners. In particular, it is characterized in that the flame flows of the plurality of burners collide with each other at a portion where the flame temperature is equal to or higher than the melting temperature of the raw material particles.

[0008] Further, in the method for melting a granular material according to the present invention, the burner is a so-called oxygen burner using pure oxygen or oxygen-enriched air as a combustion supporting gas. It is characterized in that the body is an inorganic powder for producing inorganic spheroidized particles, or the raw material powder is incinerated ash.

Further, the present invention provides a powder / melting apparatus for melting a raw material in which a raw material is charged into a combustion flame of a burner to melt the raw material. Are arranged such that the flame flows from the respective burners collide with each other, and the raw material powder is supplied to at least one of the plurality of burners in the flame. In particular, two burners are arranged to face each other, and at least one of the burners is provided with a powder material supply path for introducing the raw material particles into a flame. .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a system diagram showing an embodiment of the present invention, and is a heating and melting processing chamber (hereinafter referred to as a melting furnace).
1, two burners 2 and 3 are arranged opposite to each other, and one of the burners 2 is provided with a powder / particle supply path 4 through which a powder to be melted (raw powder) is introduced into a combustion flame. Things.

The burners 2 and 3 are arranged so that the burner central axes are located on the same straight line. The distance between the burners 2 and 3 is determined by the flame temperature of the two burners 2 and 3 It is set so that a frontal collision occurs at a temperature higher than the temperature.

Each of the burners 2 and 3 is provided with a fuel supply path 5 and a supporting gas supply path 6, respectively. A carrier gas introduction path 8 for transporting the raw material particles is provided. Further, on the downstream side of the melting furnace 1, a collecting device 9 for collecting the generated molten powder and a blower 10 for sucking and exhausting the combustion gas are provided.

Therefore, the raw material powder is supplied to the center of the burner 2 from the powder supply device 7 through the powder supply path 4 by the carrier gas introduced from the carrier gas introduction path 8, and the fuel supply path is provided. The fuel is supplied into the combustion flame generated by the fuel and the supporting gas supplied from the fuel supply line 5 and the supporting gas supply path 6, respectively.

The raw material powder charged into the combustion flame of the burner 2 is heated while traveling in the same direction as the combustion flame of the burner 2, and is heated at the center of the melting furnace 1 by the combustion flame of the burner 2 and the other burner 3. When the combustion flame collides with the combustion flame, the progress of the granular material is braked on the collision surface, and the particle stagnates in the ignited combustion flame. It will be heated.

As a result, the residence time of the raw material particles in the high-temperature combustion flame becomes longer than before, and the raw material particles can be effectively heated and melted. The throughput of the granules can be increased.

Further, by forming the distance between the two burners 2 and 3 so as to be adjustable, the fuel and the supporting gas to each of the burners 2 and 3 can be adjusted according to the properties and the supply amount of the raw material particles. Even if the supply amount is adjusted, the combustion flame can be made to collide at an optimal position, so that the melting treatment of various powders can be performed efficiently.

FIG. 2 is a system diagram showing another embodiment of the present invention. The same burner supply path 4 as described above is provided in the other burner 3 as well. In this way, when the raw material powder is charged into the two burners 2 and 3 installed in a positional relationship in which the combustion flames collide with each other, the combustion flames collide with each other and simultaneously the molten state or the semi-molten state. The raw material powder particles also collide with each other and fuse with each other to generate molten particles having a large particle diameter.

By appropriately setting the temperature and speed of the combustion flame at the position where the raw material powders collide with each other and the collision angle of the combustion flames, the degree of fusion of the raw material particles, that is, The size of the particles can be controlled.

For example, as shown in FIG. 3 and FIG. 4, by changing the positions of the burners 2 and 3 to change the collision angle of the combustion flame, the effect of increasing the throughput of the raw material particles and the melting The coalescence effect can be adjusted. That is,
When the position of one burner 2 is set to a position 2a where the axes of the two burners are oriented at 180 degrees on the same plane with respect to the other burner 3, the collision force becomes maximum and the position of the burner 2 becomes 90 degrees from the position 2b at 135 degrees. The impact force becomes smaller as the position 2c is reached. Furthermore, the arrangement angle of both burners is 90
When the angle is increased from the degree to the acute angle, the collision force becomes smaller and the collision effect becomes weaker.

The above two burners 2 and 3 may be of appropriate structures, for example, the two burners 2 and 3 may have the same function of feeding raw material and granules. If a burner having a structure is used and the raw material powder is not supplied to one of the burners, the state becomes the same as that of the apparatus shown in FIG. 1. By supplying the raw materials to both burners, the apparatus shown in FIG. It will be in the same state.

Further, it is preferable to use two burners which can obtain substantially the same combustion flame and collide at a point where the combustion state is the same, but it is also possible to collide at a point where the temperature and speed of the combustion flame are different. Further, even if the burners have the same structure, the fuel supply amount or the supporting gas supply amount of each burner may be changed, or burners having different structures may be used. Further, the combustion flames of three or more burners may collide at one point, and the flames from the third burner collide in the traveling direction of the flame after the flames from the two burners collide. You can also. In any case, the optimum conditions may be set according to the properties of the raw material powder to be melt-processed and the properties of the processed molten powder.

As the fuel supplied to the burner, any of a solid fuel such as pulverized coal, a liquid fuel such as heavy oil, and a gas fuel such as natural gas and LPG can be used. Any oxygen-containing gas such as oxygen, low-pure oxygen), oxygen-enriched air, and air can be used. However, by using pure oxygen or oxygen-enriched air containing oxygen at a high concentration, high temperatures can be obtained. Therefore, the melting process of the raw material particles having a high melting temperature can be easily performed.

The raw material particles to be melt-processed include:
Not limited to the above-mentioned inorganic powders, for example, natural quartz crushed powder and incinerated ash, but also powders and granules of various materials such as glass, cement, plastic, iron, various alloys, steel slag, steel dust, etc. Can be.

[0024]

EXAMPLE 1 As shown in FIG. 1, an apparatus in which two burners 2 and 3 were installed in a straight line facing each other was used, and a natural quartz pulverized powder having a median diameter of 35 μm was used as a raw material to be melt-processed. . On one of the burner 2, 5 Nm ³ / h of LPG as fuel, pure oxygen as the combustion assisting gas to form a 17.5 nm ³ / h respectively supplied to the flame, pure oxygen 7.5 nm ³ / h of carrier Burner 2 with raw material powder as gas at a predetermined supply rate
It was thrown into the flame. The other burner 3 contains 5 Nm ³ / h of LPG as a fuel and 2 N 2 of pure oxygen as a supporting gas.
A flame was formed by supplying 5 Nm ³ / h, respectively. In addition,
The same structure is used for both burners, except that the other burner 3 does not convey the raw material.
Of the 25 Nm ³ / h pure oxygen, 7.5 Nm ³ / h was supplied to the burner 3 via a powder supply path.

For comparison, similarly to the conventional method, one burner (the structure is the same as the above-mentioned burner) is installed vertically downward on the top of the melting furnace (position 2c in FIG. 3), and the same Melting was performed by burning under the conditions (fuel: LPG ⁵ Nm ³ / h, supporting gas: pure oxygen 17.5 Nm ³ / h, carrier gas: pure oxygen 7.5 Nm ³ / h). As a result, the raw material supply amount per unit calorific value is 0.18 kg.
At the time of / Mcal, it was confirmed that the vitrification ratio became approximately 100% at a position about 400 mm from the tip of the burner.

Therefore, the interval between the two burners 2 and 3 is set to 800 mm so that the combustion flames of the two burners 2 and 3 collide with each other at a position 400 mm from the tip of the burner. Was measured.
The result is shown in FIG. The vitrification ratio is an index indicating the degree of melting of the raw material crushed natural quartz powder. If all of the raw material is melted to the center, the vitrification ratio becomes 100%.

In FIG. 5, the circles connected by solid lines show the results obtained by the conventional method, and the triangles connected by dashed-dotted lines show the results of the embodiment. From this result, it is possible to greatly increase the amount of raw material supplied per unit calorific value at the same vitrification rate by causing the combustion flame to collide, and the raw material per unit calorific value at which the vitrification rate becomes 100%. The supply amount is 0.18 kg / Mc
From al, it turned out to be 0.28 kg / Mcal, indicating that the processing capacity was improved about 1.6 times.

Example 2 The same operation was performed except that the same apparatus and the same raw material as in Example 1 were used, and that the other side of the burner 3 was also supplied with the raw natural quartz powder. That is, the burners 2 and 3 opposed to each other at an interval of 800 mm are supplied with 5N of LPG as fuel.
m ³ / h, pure oxygen 17.5 Nm ³ /
h, pure oxygen was supplied at 7.5 Nm ³ / h as a carrier gas, and pulverized natural quartz powder having a median diameter of 35 μm was supplied at a predetermined supply rate by the carrier gas. FIG. 6 shows the particle size distribution of the obtained molten powder.

In FIG. 6, the horizontal axis is the particle size [μm], the vertical axis is the cumulative frequency of the particle size [%], the solid line is the particle size distribution of the raw material, and the one-dot chain line is the conventional melting treatment (compared in Example 1). Particle size distribution of the molten powder obtained by
The broken lines represent the particle size distribution of the molten powder in this example. From this result, it can be seen that the median diameter of the molten powder is 37 μm in the prior art, whereas the median diameter is increased to 45 μm in the present embodiment.

Example 3 Incinerated ash collected by an electric dust collector after incineration of municipal waste was used as a raw material powder. As shown in FIG. 1, an apparatus in which two burners 2 and 3 are arranged to face each other is used, and one burner 2 has LPG ⁵ Nm ³ / h and pure oxygen 17.5 N.
m ³ / h to form a flame and air 3
Using 5.7 Nm ³ / h as a carrier gas, the incinerated ash of the raw material was charged into the flame of the burner 2 at a predetermined supply rate. The other burner 3 was supplied with 5 Nm ³ / h of LPG and 25 Nm ³ / h of pure oxygen to form a flame. Also,
The molten powder in the combustion gas derived from the melting furnace 1 contains 10
It was collected by the collecting device 9 kept at 0 ° C. or higher.

The recovered molten powder was a spherical melt-solidified material. EPMA for comparison with conventional treatment
The residual chlorine concentration in the molten granules was measured by elemental analysis by the method. FIG. 7 shows the result. In FIG. 7, the solid line represents the residual chlorine concentration in the molten powder obtained by the conventional melting treatment (used as a comparison in Example 1), and the dashed line represents the residual chlorine concentration in this example. From this result, the chlorine concentration in the incinerated ash of the raw material is 20% by weight (dry state), and the chlorine concentration in the incinerated ash becomes 0% (undetectable state).
/ Mcal, but 0.34 k in this embodiment.
g / Mcal, indicating that the processing capacity was improved about 1.7 times. As a result of microscopic observation, the particle diameter of the molten powder obtained in this example was larger than that obtained by the conventional method.

[0032]

As described above, according to the method and the apparatus for melting a granular material of the present invention, it is possible to greatly increase the amount of the raw material to be melted and to reduce the processing cost. Can be. Further, it is possible to effectively increase the particle size of the powder, and to obtain a heated melt having a large particle diameter from a fine raw material.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of the present invention.

FIG. 2 is a system diagram showing another embodiment of the present invention.

FIG. 3 is a schematic front view for explaining an installation position of a burner.

FIG. 4 is a schematic side view of the same.

FIG. 5 is a diagram showing a relationship between a raw material supply amount per unit calorific value and a vitrification rate in Example 1.

FIG. 6 is a diagram showing a particle size and an integration frequency in Example 2.

FIG. 7 is a diagram showing a relationship between a raw material supply amount per unit calorific value and a residual chlorine concentration in Example 3.

[Explanation of symbols]

1 ... melting furnace, 2,3 ... burner, 4 ... powder supply path,
5: fuel supply path, 6: combustible gas supply path, 7: powder and granular material supply apparatus, 8: carrier gas introduction path, 9: trapping apparatus, 10: blower

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23L 7/00 B09B 3/00 303L

Claims (7)

[Claims] 1. A method for melting a raw material particle in which a raw material particle is charged into a combustion flame of a burner to perform a melting treatment of the raw material particle, wherein flames from a plurality of burners are collided with each other, A method for fusing powder or granules, comprising charging the raw material or granules into a combustion flame of at least one of the plurality of burners. 2. The method according to claim 1, wherein the flame flows of the plurality of burners collide at a portion where the flame temperature is higher than the melting temperature of the raw material particles. 3. The method according to claim 1, wherein the burner uses pure oxygen or oxygen-enriched air as a combustion supporting gas. 4. The method according to claim 1, wherein the raw material particles are inorganic powders for producing inorganic spheroidized particles. 5. The method according to claim 1, wherein the raw material particles are incinerated ash. 6. In a powder and particle melting apparatus for performing a melting treatment of the raw material particles by charging the raw material particles into a combustion flame of the burner, a plurality of burners are used, and a flame flow from each burner is used. Powdery and granular material, wherein the powdery and granular material is arranged so as to collide with each other, and at least one of the plurality of burners is provided with a powdery or granular material supply path for introducing the raw material or granular material into a flame. Melting equipment. 7. A powder and particle melting apparatus for charging raw material and particles into a combustion flame of a burner and melting the raw material and particles, wherein two burners are arranged to face each other,
A powder / particle melting apparatus, wherein at least one of the burners is provided with a powder / particle supply path for feeding the raw material / particle into a flame.