JP2001241861A - Method of manufacturing slowly cooled slag and rotary kiln system therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing slowly cooled slag by which the strength of manufactured slag can be increased. SOLUTION: An outlet chamber 12 which specifies a space larger than the discharge port 11 of a rotary kiln 10 is formed around the port 11. The chamber 12 has an opening on its bottom side and molten slag is discharged into a slag ladle 30 positioned immediately below the opening. By adjusting the keeping time of the ladle 30 at the position immediately below the opening, the cooling rate of the molten slag is maintained within the range of rate of crystallization of the slag by the radiation from the internal wall surface of the outlet chamber 12 and an exhaust gas discharged from the discharge port 11 and the quantity of heat of the discharged molten slag.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary kiln system and, more particularly, to a method for producing a gradually cooled slag for gradually cooling a molten slag discharged from a slag discharge port to obtain a gradually cooled slag, and a rotary kiln system therefor.

[0002]

2. Description of the Related Art A rotary kiln system will be described with reference to FIG. The rotary kiln system
It has a slag discharge type rotary kiln melting furnace (hereinafter, referred to as a rotary kiln) 100 and a secondary combustion tower 200. This type of rotary kiln system is applied to, for example, a system that burns a treated material by self-heat and fuel, and collects incineration residues as molten slag.

[0003] The rotary kiln 100 burns and melts waste introduced from a front end port (not shown) while moving it backward, and forms a slag discharge duct 205 formed below the slag discharge port 101 at the rear end. The molten slag is discharged from below. On the other hand, the exhaust gas is discharged from the gas duct 210 configured to be above the slag discharge port 101.
The waste is general waste such as municipal solid waste and sewage sludge and the residue of industrial waste. Above the gas duct 210, a secondary combustion chamber 220 for collecting and burning exhaust gas rising from the gas duct 210 is formed.

[0004] Although not clear in FIG.
Reference numeral 00 is directly connected to the slag discharge port 101 so that the exhaust gas discharged from the slag discharge port 101 of the rotary kiln 100 can be directly received.

[0005] The lower end of the slag discharge duct 205 is immersed in a water tank 230 for receiving and cooling (rapidly cooling) the molten slag discharged therefrom and descending. this is,
The inside of the secondary combustion tower 200 and thus the rotary kiln 100
This is to prevent the air from entering the inside. In addition,
In the water tank 230, the rapidly cooled and solidified slag is placed in the water tank 230.
A slag conveyor for discharging to the outside is installed.

[0006]

By the way, as a method of solidifying slag melted by a rotary kiln, in addition to the granulated slag method in which the molten slag is directly poured into water as described above, the molten slag is melted in the air. There are known an air-cooled slag method for cooling and a slow cooling slag method for adjusting a cooling rate of a molten slag.

In the granulated slag method, the granulated slag produced is vitreous and has a residual stress inside due to rapid cooling, resulting in low strength. For this reason, granulated slag has a limited field of use as compared with air-cooled and slow-cooled slag, and is mainly used as a substitute for fine aggregate and asphalt sand.

The air-cooled slag method has a much higher strength than the granulated slag shown in Table 1 (b), and the field of use is expanded to the use of roadbed materials in addition to the above-mentioned fields of use of the granulated slag. I do. On the other hand, in some cases, it is difficult to adjust the cooling rate between the surface and the inside in the manufacturing aspect, and the quality is not uniform.

[0009]

[Table 1]

[0010] The slow cooling slag forming method has a higher strength than the former two, and the range of application is remarkably expanded to the range of the upper roadbed material and the crushed stone in addition to the above fields. However, means for adjusting the cooling rate, for example, a holding furnace for adjusting the cooling rate after the melting furnace is required, and the equipment is excessively large.

Accordingly, an object of the present invention is to provide a method of producing a slow-cooled slag by applying a slow-cooling slag-forming method, in which the produced slag has a higher strength. It is in.

Another object of the present invention is to provide a method of producing a slowly cooled slag which can adjust a cooling rate for enhancing slag strength and promote crystallization without using an external heating device. .

Still another object of the present invention is to provide a rotary kiln system suitable for the above-mentioned manufacturing method.

[0014]

According to the method of the present invention, a molten slag produced by melting waste in a rotary kiln is discharged from an outlet of the rotary kiln, and the discharged molten slag is gradually cooled. A method for producing a gradually cooled slag by obtaining a gradually cooled slag, wherein an outlet chamber defining a space larger than the outlet is formed around the outlet of the rotary kiln, and the outlet chamber has an opening at a lower portion thereof. The molten slag is discharged to a movable slag storage container placed directly below the opening, and the time for placing the slag storage container directly below the opening is adjusted, and the molten slag discharged to the slag storage container is externally discharged. Irrespective of the amount of heat from the slag, the cooling rate of the molten slag is determined by the radiation from the inner wall surface of the outlet chamber, the radiation of the exhaust gas discharged from the discharge port and the amount of heat of the molten slag discharged. Characterized in that to produce a slowly cooled slag of high strength by maintaining the range of.

According to the present invention, the molten slag generated by melting the waste in the rotary kiln is discharged downward from the discharge port of the rotary kiln, and the exhaust gas discharged from the discharge port is discharged to the secondary combustion chamber. In a rotary kiln system configured to be introduced, an outlet chamber defining a space larger than the outlet is formed around the outlet of the rotary kiln, and the outlet chamber has an opening at a lower portion thereof, and has an opening directly below the opening. The molten slag is configured to be discharged to a movable slag storage container placed in the heat retaining zone, and the time for placing the slag storage container immediately below the opening is adjusted, and the molten slag is discharged to the slag storage container. Irradiates the molten slag with the radiation from the inner wall surface of the outlet chamber, the radiation of the exhaust gas discharged from the discharge port and the discharged molten Rotary kiln system, characterized in that to be able to produce a slowly cooled slag of high strength by maintaining the cooling rate of the molten slag in the range of the crystallization rate is provided in heat lugs.

It is desirable that the slag reservoir has a capacity of at least two hours for the molten slag discharged from the discharge port in view of the heat retention and the slow cooling effect by the self-heating of the molten slag.

Further, the slag storage container in the heat retaining zone is configured to be sealed from the atmosphere by a sealing mechanism.

Further, the secondary combustion chamber is connected so as to be able to receive the exhaust gas at a position off the extension of the discharge port of the rotary kiln and at a side position of the outlet chamber.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotary kiln system according to an embodiment of the present invention will be described with reference to FIGS. In FIG. 1, waste introduced from a front end port (not shown) of the rotary kiln 10 is melted in the rotary kiln 10, and is charged as molten slag 20 from a discharge port 11 into a slag reservoir 30. On the other hand, as shown in FIG. 2, the exhaust gas from the discharge port 11 is introduced into the secondary combustion chamber 40 via the outlet chamber 12, and the heat is recovered by the heat exchanger 41 of the boiler. It is led to the processing system. The rotary kiln system according to this embodiment is
Unlike the rotary kiln system described in FIG.
An outlet chamber 12 is provided around the outlet 11 of the rotary kiln 10.
Is formed, and a secondary combustion chamber 40 is connected to the side of the outlet chamber 12. The exit chamber 12 is located on the upper inner wall 12.
a, a side inner wall 12b, and a rear inner wall 12c, and the secondary combustion chamber 4 is connected to a connection port 12d opposite to the side inner wall 12b.
0 is linked. This means that the secondary combustion chamber 40 is at a position off the extension of the outlet 11.
The lower part of the outlet chamber 12 is formed so that the width in the lateral direction is increased. This width corresponds to the slag reservoir 3
It is about the size of two cars of 0.

In this way, a space for retaining the exhaust gas is provided between the rotary kiln 10 and the secondary combustion chamber 40, that is, in the outlet chamber 12. The reason for providing the outlet chamber 12 is as follows. The first reason is to prevent dust adhering to the wall surface of the secondary combustion chamber 40 from falling and entering the slag reservoir 30. The second reason is that the outlet chamber 12 is kept at a high temperature by making the space smaller than the space of the secondary combustion chamber 40 so that the temperature of the slag storage container 3 immediately below is maintained.
This is for improving the heat radiation efficiency to zero. In the present embodiment, when dust adhering to the wall surface of the secondary combustion chamber 40 falls, the dust is received by the dust reservoir 42 arranged at the bottom of the secondary combustion chamber 40.

The slag reservoir 30 is movable directly below the lower opening of the outlet chamber 12 while being connected at regular intervals by an endless chain mechanism or the like. Immediately below the lower opening of the outlet chamber 12, seal mechanisms 13 are installed on the entrance side and the exit side of the slag reservoir 30, respectively. The seal mechanism 13 is for sealing the inside of the rotary kiln 10 and the outlet chamber 12 with the atmosphere. For this reason, immediately below the lower opening of the outlet chamber 12 may be referred to as a slag heat retaining zone.

The slag reservoir 30 is configured such that a slag receiver called a mold can roll with respect to the main body. The content of the mold is 10
2 to 6 hours of slag discharged from the furnace. this is,
This is for keeping the slag reservoir 30 in the heat insulation zone immediately below the lower opening of the outlet chamber 12 for 4 hours or more.

In FIG. 2, the slag storage container 30 at the position P1 receives the molten slag flowing down to the position P2. The slag storage container 30 moves to the position P3 after a certain time when the molten slag is almost filled. P
At positions 2 and P3, the temperature is maintained by the sensible heat of the molten slag and the heat transfer by the exhaust gas, and the radiant heat from the upper inner wall 12a, the side inner wall 12b, and the rear inner wall 12c, and the molten slag is gradually cooled. Further, just in case, the slag reservoir 30 moved to the position P4 is cooled while being sealed from the atmosphere by the seal mechanism 13.

According to the above method, the molten slag discharged from the discharge port 11 has a crystal growth of 850 to 1050.
The region of ° C. is gradually cooled at a cooling rate of 0.3 to 2 ° C./min to form a crystallized slowly cooled slag.

The slag reservoir 30 which has come out of the heat insulation zone from the position P4 discharges the gradually cooled slag by rolling the mold or the like. The discharged slowly cooled slag is cracked to the required particle size for the application. After discharging the slowly cooled slag, the slag reservoir 30 is prepared again before the position of P1.

[0026]

EXAMPLES Specific examples will be described below.

(1) Processed material: municipal waste incineration ash (2) Melting furnace: slag discharge type rotary kiln (Φ1.2
m (inner diameter) x 7 m (length)) (3) Slag discharge amount: about 400 kg / h (4) Cooling rate: Cool at 0.5 ° C per minute between 1200 ° C and 700 ° C (5) Result Is as shown in Table 1 (a) above.

According to Table 1 (a), the slowly cooled slag obtained by the present invention is obtained by using a surface material of asphalt pavement, an upper roadbed material,
It satisfies all standards for lower subgrade materials, road crushed stone, concrete crushed stone, and fine sand.

As described above, in the present invention, the cooling rate of the molten slag is maintained within a predetermined range by utilizing the so-called waste heat when melting waste in a rotary kiln without separately providing a heating source. By doing so, it is possible to promote the crystal growth in the slag and produce a slow cooling slag having a natural stone-like appearance and a high strength.

Of course, the present invention is applicable to all fields of industrial waste and general waste.

[0031]

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

(1) Slow-cooled slag having high strength and large particle size can be obtained with respect to granulated slag whose application is limited due to low strength and small particle size.

(2) There is no need to separately install a heating device, and both equipment costs and operation costs can be reduced.

(3) The (1) and (2) make it possible to produce slow-cooled slag easily and inexpensively, thereby expanding the use of the slag and increasing the added value of the slag discharge type rotary kiln.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a part of a rotary kiln and a structure of a secondary combustion chamber in a rotary kiln system according to the present invention.

FIG. 2 is a sectional view of the structure shown in FIG. 1 as viewed from a discharge port side of the rotary kiln.

FIG. 3 is a sectional view showing a part of a rotary kiln and a structure of a secondary combustion chamber in a conventional rotary kiln system.

[Explanation of symbols]

 10, 100 Rotary kiln 11, 101 Outlet 12 Outlet chamber 13 Sealing mechanism 20 Melt slag 30 Slag reservoir 40 Secondary combustion chamber 41 Heat exchanger 42 Dust reservoir 200 Secondary combustion tower 205 Slag discharge duct 210 Gas duct 220 Secondary combustion Room

Claims (6)

[Claims] 1. A method for producing a slowly cooled slag in which a molten slag generated by melting waste in a rotary kiln is discharged from an outlet of the rotary kiln, and the discharged molten slag is gradually cooled to obtain a gradually cooled slag. , An outlet chamber defining a space larger than the outlet port around the outlet port of the rotary kiln, wherein the outlet chamber has an opening at a lower portion thereof, and a movable slag storage container placed immediately below the opening. The molten slag is discharged into the slag reservoir, and the time for placing the slag reservoir directly below the opening is adjusted, and the molten slag discharged into the slag reservoir is discharged from the inner wall surface of the outlet chamber regardless of the amount of heat from outside. , The cooling rate of the molten slag is kept within the range of the crystallization rate by the radiation of the exhaust gas discharged from the discharge port and the calorific value of the discharged molten slag, whereby the high-strength slow cooling slag is maintained. A method for producing slowly cooled slag, which comprises producing a rug. 2. The method for producing slowly cooled slag according to claim 1, wherein the capacity of the slag reservoir is at least 2 hours of the molten slag discharged from the discharge port. Manufacturing method. 3. The method for producing a slowly cooled slag according to claim 1, wherein the rotary kiln constitutes a rotary kiln system together with a secondary combustion chamber for treating exhaust gas from the discharge port. The combustion chamber
A method for producing a slow cooling slag, wherein the exhaust gas is received at a position off the extension of the discharge port of the rotary kiln and at a side position of the outlet chamber. 4. A configuration in which molten slag generated by melting waste in a rotary kiln is discharged downward from a discharge port of the rotary kiln, and exhaust gas discharged from the discharge port is introduced into a secondary combustion chamber. In the rotary kiln system, an outlet chamber defining a space larger than the outlet is formed around the outlet of the rotary kiln, and the outlet chamber has an opening at a lower portion thereof, and is placed in a heat retaining zone immediately below the opening. The molten slag is configured to be discharged to a movable slag storage container placed therein, and by adjusting a time for placing the slag storage container directly below the opening, the molten slag discharged to the slag storage container is externally discharged. Irrespective of the amount of heat from the outlet, the radiation from the inner wall surface of the outlet chamber, the radiation of the exhaust gas discharged from the discharge port, and the heat of the molten slag discharged A rotary kiln system characterized in that a high-strength slowly cooled slag can be produced by maintaining the cooling rate of the molten slag within the range of the crystallization rate. 5. The rotary kiln system according to claim 4, wherein the slag reservoir in the heat insulation zone is sealed from the atmosphere by a sealing mechanism. 6. The rotary kiln system according to claim 4, wherein the secondary combustion chamber is capable of receiving the exhaust gas at a position off the extension of the outlet of the rotary kiln and at a side position of the outlet chamber. A rotary kiln system connected to the rotary kiln.