JP2804008B2 - Asphalt plant dryer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dryer for drying aggregates provided in a recycling plant or a drum mixing plant for recycling asphalt waste.

[0002]

2. Description of the Related Art In recent years, a so-called recycling plant that recycles asphalt waste generated by replacing existing roads or the like has been put into practical use from the viewpoint of regulation of industrial waste treatment or effective use of resources.

[0003] As a heating and drying apparatus for asphalt waste material in such a recycling plant, a cylindrical drum main body for rotating and falling asphalt waste material, a hot air generator for blowing hot air into the drum main body, and a drum main body and a hot air generator. A dryer having a combustion cylinder provided therebetween is used.

[0004] In the combustion cylinder, the gas supplied from the burner burns at a high temperature, and its internal temperature reaches about 1000 ° C. Conventionally, in order to protect the steel combustion cylinder from such a temperature rise, a refractory material such as castable refractory or ceramic wool is pasted on the inner surface of the combustion cylinder. However, there is a problem that such refractories are expensive and not only increase the cost but also cannot be easily handled because they are industrial wastes. Particularly, in the case of a recycling plant, matters that lead to an increase in cost are extremely serious drawbacks.

Therefore, as a measure for protecting the combustion cylinder, attempts have been made to protect the combustion cylinder from high temperatures by introducing outside air into the combustion cylinder and cooling the inner surface of the combustion cylinder.

On the other hand, when the recycled material is heated by a dryer, the combustion gas is directly applied to the recycled material and heated.
Since the combustion gas temperature reaches about 1000 ° C., it is overheated, and the fine particles of the recycled material cause the generation and deterioration of blue smoke.

In order to prevent this, the exhaust gas from the dryer is generally reused, mixed with the combustion gas, and the temperature of the gas for heating the recycled material is lowered. Since the temperature is 200 ° C., which is low enough to cool the combustion cylinder, a method of introducing this return gas into the combustion cylinder to cool it has also been implemented.

[0008]

However, when external air is introduced into the combustion cylinder to cool the inner surface of the combustion cylinder, only the portion of the combustion gas passing through the combustion cylinder into which the external air has been introduced is cooled. Because the temperature drops significantly, the recycled material in the dryer is locally cooled, causing uneven drying,
Alternatively, a new problem has occurred, such as a decrease in the drying efficiency due to a too low combustion gas temperature.

On the other hand, when the return gas from the dryer is introduced into the combustion cylinder and cooled, the mechanism is such that the return gas is simply introduced into the combustion cylinder as it is, so the combustion gas inside the combustion cylinder is cooled. The combustion cylinder itself is not cooled, and its cooling effect is extremely insufficient. Further, since the combustion cylinder is maintained at a high temperature without being cooled, there is a disadvantage that radiant heat from the combustion cylinder increases and energy is wasted. Furthermore, since the return gas and the combustion gas are difficult to be uniformly mixed in the combustion tube, and the combustion gas and the like are blown into the dryer in a state where the temperature is not uniform, there is also a major problem that drying unevenness occurs in the recycled material.

[0010] Therefore, an object of the present invention is to provide means capable of effectively protecting a combustion cylinder without unnecessarily lowering the temperature inside the combustion cylinder.

[0011]

In order to solve the above problems, the present invention provides a dryer body for drying aggregate, a hot air generator for supplying hot air to the dryer body, the dryer body and the hot air generator. In a dryer of an asphalt plant having a combustion cylinder disposed between the outer cylinder and the inner cylinder, the cooling cylinder supplies a cooling gas between the outer cylinder and the inner cylinder. It is characterized by having a supply system.

As described above, the combustion cylinder has the double structure of the outer cylinder and the inner cylinder, and by supplying the cooling gas between the outer cylinder and the inner cylinder, the excess of hot air passing through the inside of the inner cylinder is obtained. Cooling can be prevented, the cooling effect of the combustion cylinder can be improved, and radiant heat to the outside can be reduced.

[0013] Here, the cooling gas is supplied along a linear direction which forms a torsion position with the center axis of the combustion cylinder. When supplying the cooling gas into the combustion cylinder, by supplying the cooling gas along the straight line, the cooling gas moves while spirally rotating between the outer cylinder and the inner cylinder. The cooling effect of the cylinder is improved.

Further, as a cooling gas supplied to the combustion cylinder,
The exhaust gas generated from the dryer is used. Since the exhaust gas generated from the dryer is at 100 to 200 ° C., by using this as a cooling gas,
The cooling effect of the combustion cylinder is sufficient, and the effective use of heat can be achieved by reducing radiant heat to the outside.

Further, a through hole through which the cooling gas can flow is formed in the inner cylinder. By forming a through hole in the inner cylinder, a part of the cooling gas supplied between the outer cylinder and the inner cylinder passes through the through hole and enters the inner cylinder. Also, a cooling gas layer is formed. For this reason, the temperature difference between the outside and the inside of the inner cylinder wall surface is eliminated, the cooling effect of the inner cylinder itself is improved, and the thermal deterioration of the material forming the inner cylinder can be prevented.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a side view showing an embodiment, FIG. 2 is a partially cutaway perspective view showing an embodiment, FIG. 3 is a partially cutaway side view around a combustion cylinder, and FIG. 4 is a sectional view taken along line AA of FIG. It is.

In FIG. 1, 1 is a dryer of an asphalt plant, 2 is a dryer body for drying aggregate, 3 is a burner for supplying hot air to the dryer body 2, and 4 is disposed between the dryer body 2 and the burner 3. The combustion cylinder 5 is a return fan that blows the gas discharged from the dryer body 2 to the combustion cylinder 4 as return gas RG.

As shown in FIG. 2, in the dryer 1,
The combustion cylinder 4 has a double structure of an outer cylinder 41 and an inner cylinder 42, and the inner cylinder 42 has a small inner cylinder 42a and a large inner cylinder 4 having different diameters.
2b, and a large number of through holes 6 are opened in both the small inner cylinder 42a and the large inner cylinder 42b.

A return gas supply port 7 is provided at a position of the outer cylinder 41 of the combustion cylinder 4 near the burner 3, and the return gas RG blown from the return fan 5 is supplied to the outer cylinder 41 and the inner cylinder 42. Supply between. Although the temperature of the return gas RG is 100 to 200 ° C., the combustion gas HG in the combustion tube 4 may reach 1000 ° C.
The temperature is low enough to be used for cooling. Therefore, by using the return gas RG as a cooling gas, not only an excellent cooling effect can be obtained, but also radiant heat to the outside is extremely reduced, and effective use of heat can be achieved.

Here, in order to supply the return gas RG along a linear direction which is twisted with respect to the center axis of the combustion cylinder 4, a return gas supply port 7 is provided on the outer peripheral portion of the combustion cylinder 4. As a result, the return gas RG introduced from the return gas supply port 7 spirally rotates between the outer cylinder 41 and the inner cylinder 42 in the combustion cylinder 4 as shown in FIG. Move toward. Therefore, not only is the cooling effect of the combustion cylinder 4 high, but also the combustion gas HG passing through the inner cylinder 42 toward the dryer main body 2 is not excessively cooled.

Therefore, the combustion gas HG is sent into the dryer main body 2 in a state where no temperature unevenness occurs and the appropriate temperature is maintained.
There is no drying failure and the drying efficiency is excellent.

Further, the inner cylinder 42 is constituted by two small inner cylinders 42a and large inner cylinders 42b having different diameters, and a large number of through holes 6 are formed in each of them. A part of the return gas RG supplied therebetween passes through the through hole 6 and the gap 9 and enters the inner cylinder 42. Therefore,
Cooling gas layer 8 not only on the outside but also inside the wall surface of inner cylinder 42
Is formed, no temperature difference occurs between the outside and the inside of the wall surface of the inner cylinder 42, the cooling effect of the inner cylinder 42 is improved, and the thermal deterioration of the material forming the inner cylinder 42 can be prevented. .

As described above, since the inner cylinder 42 is composed of two large and small inner cylinders 42a and 42b having different diameters, the gap 9 is formed at the boundary between the small inner cylinder 42a and the large inner cylinder 42b. . Therefore, since a part of the supplied return gas RG flows into the large inner cylinder 42b from the gap 9, a constant flow is generated in the return gas RG. Promotes formation. Therefore, the cooling effect of the large inner cylinder 42b located at a position distant from the return gas supply port 7 can be enhanced.

Incidentally, regarding the inner cylinder provided in the combustion cylinder,
Other forms may be used. For example, one with an inner cylinder,
It is also possible to use one having three or more inner cylinders, one having no through hole, or one having a cone shape with a gradually changing diameter.

As described above, in the dryer 1, since the combustion cylinder 4 is cooled by supplying the return gas RG between the outer cylinder 41 and the inner cylinder 42, the cooling effect is excellent, and the excessive cooling of the combustion gas HG is performed. No emission and very little heat radiation. Therefore, heat can be effectively used, and energy is not wasted. In addition, since the combustion gas HG having no temperature unevenness and having an appropriate temperature is sent to the dryer main body 2, unevenness in drying of the recycled material, poor drying, and the like do not occur.
Excellent drying efficiency.

[0026]

According to the present invention, the following effects can be obtained.

(A) Since the combustion cylinder has a double structure of an outer cylinder and an inner cylinder, and a cooling gas is supplied between the outer cylinder and the inner cylinder, the temperature of the hot air passing through the inner cylinder does not drop too much. In addition, the cooling effect of the combustion cylinder is high, and the radiation heat to the outside is small. For this reason, drying unevenness and poor drying of the recycled material do not occur, and the drying efficiency is high.

(B) By supplying the cooling gas in a direction along a straight line that is twisted with the center axis of the combustion cylinder,
The cooling gas moves while spirally rotating between the outer cylinder and the inner cylinder, so that the cooling effect of the combustion cylinder is improved.

(C) By using the exhaust gas generated from the dryer as the cooling gas, the cooling effect of the combustion cylinder becomes sufficient, the radiant heat to the outside is reduced, and the heat can be effectively used. .

(D) By forming a through hole in the inner cylinder, a part of the supplied cooling gas passes through the through hole and enters the inner cylinder. The cooling gas layer is formed, the temperature difference between the outside and the inside of the inner cylinder wall surface is eliminated, the cooling effect of the inner cylinder itself is improved, and the thermal deterioration of the material forming the inner cylinder can be prevented.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment.

FIG. 2 is a partially cutaway perspective view showing the embodiment.

FIG. 3 is a partially cutaway side view near a combustion cylinder.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dryer 2 Dryer main body 3 Burner 4 Combustion cylinder 41 Outer cylinder 42 Inner cylinder 42a Small inner cylinder 42b Large inner cylinder 5 Return fan 6 Through hole 7 Return gas supply port 8 Cooling gas layer 9 Gap RG Return gas HG Combustion gas

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F26B 3/04 B09B 3/00 C10C 3/12 F26B 21/00 F26B 23/02

Claims (4)

(57) [Claims] 1. A dryer for an asphalt plant having a dryer body for drying aggregate, a hot air generator for supplying hot air to the dryer body, and a combustion tube disposed between the dryer body and the hot air generator. 3. The asphalt plant dryer according to claim 1, wherein the combustion cylinder has a double structure of an outer cylinder and an inner cylinder, and a cooling gas supply system that supplies a cooling gas between the outer cylinder and the inner cylinder. 2. A dryer for an asphalt plant according to claim 1, wherein said cooling gas is supplied along a linear direction which is twisted with a central axis of said combustion cylinder. 3. The dryer for an asphalt plant according to claim 1, wherein the cooling gas is exhaust gas generated from the dryer. 4. A dryer for an asphalt plant according to claim 1, wherein a through hole through which a cooling gas can flow is formed in said inner cylinder.