JPH0642876A - Indirect heating type rotary heating furnace - Google Patents

Abstract

(57) [Summary] [Purpose] The residence time of the material in the rotary furnace is set arbitrarily,
To improve production capacity and obtain high quality products. [Structure] Rotating furnace 1 that receives power from a drive mechanism to rotate
An outlet lid 11 having an opening 12 is provided in the vicinity of the 0 outlet. The material to be heat-treated 34 is fed into the rotary furnace 10 from the charging hopper 30 and is delivered as a product from the opening 12 of the outlet lid 11. Rotating furnace 10 instead of outlet lid 11
A weir may be provided along the inner peripheral surface of the. [Effect] By providing a discharge amount adjusting means such as a lid at the outlet of the rotary furnace 10, the material filling rate in the rotary furnace 10 is increased, and the residence time is arbitrarily adjusted, while sufficient heat treatment is performed in the rotary furnace 10. It can be applied and the production amount can be greatly improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to various materials which have a high filling rate of the material to be treated and a greatly increased production capacity, and are used for firing, roasting,
The present invention relates to an indirect heating type rotary heating furnace that performs heat treatment such as drying.

[0002]

2. Description of the Related Art A rotary heating furnace such as a rotary kiln is used for subjecting various materials to heat treatment such as roasting, sintering and drying, as represented by a firing kiln in the cement industry. This rotary heating furnace is classified into a direct heating type and an indirect heating type.

In a direct heating type rotary heating furnace, the fuel gas fed into the furnace is combusted and the charging heat is used to heat the charging raw material. Alternatively, the charging raw material may be heated by the hot gas blown into the furnace. However, since the charging raw material comes into direct contact with combustion gas, hot gas, etc., the type of charging raw material that can be applied is restricted. Further, the dust contained in the gas may be mixed into the charging raw material to deteriorate the quality of the product.

On the other hand, in the indirect heating type rotary heating furnace, the charged raw material is heated by heat transfer through the furnace wall. Therefore, although the thermal efficiency is low, the charging raw material is not contaminated or deteriorated by the combustion gas, the hot gas or the like. Taking advantage of this advantage, an indirect heating type rotary heating furnace fires a substance that does not like foreign matter from combustion gas, etc., and deterioration caused by contact with combustion gas, and a small amount of raw material that does not cause a big problem in thermal efficiency. Is used for that.

In the case of firing an inorganic material used as an electronic material or the like, even if a very small amount of foreign matter is mixed in, the quality characteristics of the product are greatly deteriorated. Therefore, it has been very rare so far to use a direct heating rotary heating furnace to sinter inorganic materials used as electronic materials and the like.

The reason why the direct heating type rotary heating furnace is not used is not only the problem of foreign matter mixing but also the baking time, the baking temperature and the like. That is, the passing time of the charging raw material in the rotary heating furnace is generally short, and a sufficient residence time cannot be secured. Therefore, it is not suitable for materials such as silica and alumina that require long-term firing. Further, in the indirect heating type rotary heating furnace, although there is no problem of foreign matter mixing, the diameter and length of the rotary furnace are limited to some extent due to the configuration of the apparatus. That is, since the indirect heating type rotary heating furnace has to support the rotary furnace main body outside the heating part, there is a problem in strength in a long rotary furnace or a large diameter rotary furnace.
Mass production is impossible due to the large size.

For this reason, when firing an inorganic material used as an electronic material or the like, firing using a batch furnace, a tunnel furnace or the like is the mainstream. However, even in batch furnaces, tunnel furnaces, etc., it is inevitable that impurities will be mixed in the product due to evaporation of trace components contained in pots, furnace materials, etc., and evaporation of trace components from heating elements. , Unable to produce high quality products.

[0008]

When heating is performed using a rotary furnace, the filling rate in the rotary furnace is generally 15 to 18%. The reason for this is that the speed of the material passing through the rotary furnace is
This is because it is determined by the tilt angle of the rotary furnace, the charging speed, the number of rotations, etc., and therefore does not fall below a certain speed.

The time for the charging material to pass through the rotary furnace, that is, the residence time of the fired product, is determined by the same factors as described above. The material retention time when the retort inclination angle is 0 ° is calculated by the following formula. τ = 0.91 (L / D) ² × (D / hf) ^0.57 × (tan β / N) hf = (FL / 0.74 × D ⁴ × N × cot β × ρ _S ) ^-0.25 × D τ = Residence time (min) N = Rotational speed (rpm) β = Material repose angle (°) F = Material supply speed (kg / m)
in) L = length (m) ρ _S = material bulk density (kg /
m ³ ) D = inner diameter (m)

Therefore, in the case of a material that requires a long firing time, even if the inclination angle of the rotary furnace is 0 °, there is no choice but to reduce the material supply rate at a predetermined rotation speed.

However, even in this case, there was a problem that the residence time could be extended only slightly and that the production capacity was lowered if the feed rate was lowered.

The present invention has been devised to solve such a problem. By increasing the filling rate by providing means for adjusting the discharge amount of the burned material near the outlet of the rotary furnace. The purpose is to control the moving speed, set the residence time of the material in the rotary furnace arbitrarily, improve the production capacity, and obtain a high quality product.

[0013]

In order to achieve the object, the indirect heating type rotary heating furnace of the present invention is characterized in that a means for adjusting the discharge amount of the burned material is provided near the outlet of the rotary heating furnace. .

As means for adjusting the discharge amount of the burned material,
There are a method in which the outlet is covered and an opening is provided in the outer lid, and a method in which a weir is provided along the inner peripheral surface near the outlet of the rotary furnace. Further, the opening area provided in the lid or the like is determined according to the production amount, but it is preferable to have a structure in which the opening area can be changed in order to match with the charging amount.

[Action]

By providing a lid having an opening at the outlet of the rotary furnace, it is intended to prevent the natural flow of the material, limit the discharge speed of the burned material, and arbitrarily set the material moving speed inside the rotary furnace. .

The material charged into the rotary furnace from the charging port is
As the rotary furnace rotates, it moves toward the outlet due to the inclination of the rotary furnace and the difference in material level. However, because the amount of emissions is limited, the material filling rate in the rotary furnace becomes high,
The movement will stop when the material level at the inlet is reached.
If the material at the discharge port is discharged there, the material is moved by the volume.

[0017]

EXAMPLE As shown in FIG. 1, the rotary heating furnace of this example is equipped with a rotary furnace 10 having an opening at its outlet. The rotary furnace 10 includes receiving rollers 1 installed on both sides of the electric furnace 13.
Both ends are supported by 4a and 14b, and the electric furnace 13 is penetrated and arranged.

The rotary furnace 10 is rotated by a drive gear 21 connected to a drive mechanism (not shown). At this time, it is preferable that the rotary furnace 10 is made of a material having a small amount of evaporated impurities. For example, when firing silica, a quartz tube having the same components as silica is used.

On the inlet side of the rotary furnace 10, the charging hopper 3
0 is placed. At the bottom of the charging hopper 30,
A charging pipe 32 having a screw feeder 31 is connected. The tip of the charging pipe 32 faces the inside of the rotary furnace 10, and a level gauge 33 is incorporated near the tip.

The level gauge 33 is a charging hopper 30.
The charging raw material 34 cut out from the screw feeder 3
When it is sent to the rotary furnace 10 by the charging furnace 1, the charging pipe 32
Detect the level of feedstock inside. The detection result is output to an appropriate control circuit (not shown) to control the drive mechanism (not shown) of the screw feeder 31. As a result, an appropriate amount of charging raw material is charged into the rotary furnace 10. In addition,
The mechanism for feeding the charging raw material from the charging hopper 30 to the rotary furnace 10 is not limited to this, and it is needless to say that another cutting mechanism such as a roll feeder can be adopted.

The charging raw material fed into the rotary furnace 10 flows in the direction shown by the arrow in FIG. 1 as the rotary furnace 10 rotates. During this flow process, the heat transferred from the electric furnace 13 through the rotary furnace 10 is used to bake, roast, and charge the charging raw material.
Heat treatment such as drying is performed. The heat-treated charging raw material is
The product is delivered from the outlet on the opposite side of the rotary furnace 10.

An outlet lid 11 is fitted to the outlet,
The outlet lid 11 is provided with an opening 12. Opening 12
The position of may be at the center of the outlet lid 11, but since the material near the inner peripheral surface of the rotary furnace 10 is not discharged, the material near the center tends to be discharged intensively, so in this embodiment, By providing the position of the opening 12 eccentrically from the outer periphery,
The material in the rotary furnace 10 is discharged on average. Further, a plurality of openings may be provided if necessary.

Silica was fired using this rotary heating furnace. Silica with an average particle size of 1.50 μm was used as a charging raw material, and a quartz tube made of the same material as this silica and having an inner diameter of 350 mm was used as a rotary furnace. The quartz tube has an inner diameter of 380 m to prevent the rotary furnace from being deformed by heating.
m alumina tube was used. The internal temperature of the rotary furnace was set to 1200 to 1230 ° C., and the rotary furnace was rotated at a speed of 0.5 rpm while supplying silica at a supply rate of 30 kg / hour. The amount discharged from the outlet was 30 kg / hour. Observation of the calcined silica discharged from the rotary furnace revealed that there was neither uneven burning nor insufficient burning, and an extremely high quality product was obtained.

[0024]

As described above, in the indirect heating type rotary heating furnace of the present invention, the discharge amount adjusting means such as a lid is provided at the outlet of the rotary furnace to increase the material filling rate in the rotary furnace. By adjusting the residence time arbitrarily and subjecting the charging raw material to heat treatment such as firing, roasting, and drying in the rotary furnace, sufficient heat treatment can be performed in the rotary furnace.
The production amount can be greatly improved.

[Brief description of drawings]

FIG. 1 is an indirect heating type rotary heating furnace used in an embodiment of the present invention.

[Explanation of symbols]

 10 rotary furnace 11 outlet lid 12 opening

Claims (3)

[Claims] 1. An indirect heating type rotary heating furnace, wherein a means for adjusting the discharge amount of the burned material is provided near the outlet of the rotary heating furnace. 2. The indirect heating type rotary heating furnace according to claim 1, wherein a lid having an opening is provided at an outlet of the rotary heating furnace. 3. The indirect heating type rotary heating furnace according to claim 2, wherein the position of the opening is eccentric to the outer periphery.