JPH09236244A - Slag discharge device of melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover high-strength slag at low temperatures of about 100 deg.C or lower while a risk of elution of heavy metals is prevented. SOLUTION: A melting furnace to melt an object has a slag outlet 5 at the lower part. Slag flowing out through the slag outlet 5 is discharged after it passes through a shoot 6 and is cooled down at a cooling unit. The cooling unit includes an air-cooled cooler 8 arranged under the shoot 6 and a water- cooled cooler 9 continuously arranged at the front end in the slag traveling direction of the air-cooled cooler 8, so that the slag is discharged after it passes through the shoot 6 and cooled down by the air-cooled and water-cooled coolers 8 and 9 in turn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slag discharge device for a melting furnace, and more particularly to a slag discharge device for a melting furnace suitable for equipment for melting and solidifying various wastes such as municipal waste incineration ash at high temperature. .

[0002]

2. Description of the Related Art Most of incineration ash generated by incinerating municipal waste, sewage sludge, and other wastes is landfilled. However, since it is becoming more difficult to secure landfill sites year after year, there is a demand for minimizing the volume of incinerated ash to be landfilled, that is, volume reduction treatment.
Further, when the incinerated ash is landfilled as it is, harmful substances such as various heavy metals contained in the incinerated ash itself may dissolve into rainwater, groundwater and the like, causing so-called secondary pollution. For this reason, it is also strongly desired that the incineration ash be treated to be pollution-free before the landfill. Under such circumstances, a method of melting and solidifying at high temperature is being adopted in order to realize volume reduction and detoxification treatment of incinerated ash, and a melting furnace is generally used for carrying out the method.

By the way, there are roughly two ways of constructing the apparatus for discharging the high temperature molten slag generated in the melting furnace and solidifying it to the slag storage tank. One is to attach a downward chute to the outlet of the slag, and to provide a water-cooling type cooling device under the chute as shown in Japanese Patent Publication No. 7-39857, and to convey slag into the cooling device. This is a method of incorporating a device. In such a water cooling system, the high-temperature slag discharged from the melting furnace is rapidly cooled as soon as it is continuously put into water, cooled to about 100 ° C. or lower, and then continuously taken out. Therefore, it is easy to handle the so-called slag because it is easy to simplify, and because the solidified slag becomes fine particles, it has the advantage that it is easy to separate and recover metal components such as iron in the slag. There is.

The other is that a fixed or movable slag receiving container is arranged below the outlet as disclosed in JP-B-7-30893 and JP-A-5-312311. When a predetermined amount of slag is accumulated in the container, the next empty container is set, and the container in which the slag is accumulated is conveyed to the slag storage tank. In this method, the high-temperature slag discharged from the melting furnace is air-cooled or de-cooled, so that the solidified slag becomes a stone block and has an advantage that high strength is obtained.

[0005]

However, in the case of the above water cooling system, the strength of the recovered slag is low, so that its application is extremely limited even if it is intended to be effectively used. For example, the lower layer subbase material for asphalt pavement is used. There is a problem that it is limited to such uses. On the other hand, in the case of the above air cooling system,
The temperature of the slag discharged to the slag storage tank is 200 ° C. or higher, and sometimes it is discharged at a high temperature of about 500 ° C. For this reason, when the discharged slag is moved to the slag storage tank itself or to a slag storage tank located at a remote place, the moving device must also have a heat resistant structure. Further, not only the entire outer surface of the slag storage tank or the slag moving device, but also the work space around the slag storage tank becomes high in temperature, and if heat countermeasures are insufficient, the work environment is deteriorated.

In the exhaust gas near the outlet of the melting furnace,
Fly ash and low-boiling-point gaseous substances (collectively referred to as “melt fly ash” below) are included, and it is inevitable that the melt fly ash will adhere to the inner wall of the chute to some extent, and this melt It is unavoidable that small particles of fly ash deposits adhere to the slag falling along the inner wall of the chute to some extent. In this case, in the water cooling method, most of the molten fly ash attached to the surface of the slag is washed and removed in water, but in the air cooling method, the molten fly ash is solidified with the molten fly ash attached to the surface of the slag. However, since the molten fly ash contains heavy metals, when such solidified slag with molten fly ash attached is used as road aggregate, etc., heavy metals are eluted by rainwater, groundwater, etc. However, there is a problem that it may pollute the soil and cause new pollution.

The present invention has been made in view of the above problems of the prior art. The invention according to claim 1 of the present invention prevents the possibility of heavy metal elution. It is an object of the present invention to provide a slag discharge device for a melting furnace that can recover high-strength slag at a low temperature of about 100 ° C or lower. In addition to the object of the invention described in claim 1, the invention described in claim 2 aims to provide a slag discharge device for a melting furnace which is particularly excellent in the effect of preventing the elution of heavy metals. Is.

[0008]

The invention according to claim 1 of the present invention, which has achieved the above object, discharges from an outlet provided at the bottom of a melting furnace for melting a material to be melted, In a slag discharging device of a melting furnace that is discharged after being cooled in a cooling part through a chute, a cooling part is provided, and an air-cooling type cooling device (hereinafter simply referred to as “air cooling device”) is arranged below the chute. A water cooling type cooling device (hereinafter simply referred to as "water cooling device") is connected to the tip of the air cooling device on the slag advancing direction side, and the slag that has passed through the chute is cooled in the order of air cooling and water cooling and then discharged. It is characterized by being done.

According to such a slag discharge device, the high temperature slag that has dropped from the chute is gradually cooled by the air cooling device, so that the strength of the slag is increased, and then the slag is further cooled by the water cooling device. At the same time, most of the molten fly ash adhering to the slag surface is removed by washing. Therefore, most of the molten fly ash that is the source of elution of heavy metals is removed, so that high-strength slag with little risk of elution of heavy metals can be recovered at low temperatures. Since the slag recovered in this way has much higher strength than simple granulated slag, it is used for crushed stone for roads, asphalt pavement (lower layer, upper layer, surface layer, base layer, etc.), as well as crushed stone for concrete. Since it can also be used as an aggregate for concrete, the slag has a high utility value. In addition, since the slag after water cooling is cooled to about 100 ° C. or less, the heat required for the conventional air-cooled single system for the slag discharge device after the water cooling device (including the slag storage tank) is required. Not only the cost for countermeasures can be reduced, but also the recovery work is facilitated, which can contribute to the reduction of the total cost required for the operation of the melting furnace.

The invention according to claim 2 is characterized in that, in the constitution of the invention according to claim 1, a water injection nozzle is provided in an intermediate duct connecting the air cooling device and the water cooling device in series. is there. In this way, between the air cooling device and the water cooling device,
Although the physical strength is increased, by spraying water from the water spray nozzle to the slag with molten fly ash attached, the cleaning and removing effect of the molten fly ash attached to the slag surface can be achieved. Can be increased. Therefore, in addition to the effect of the invention as set forth in claim 1, it has been made particularly excellent in the effect of preventing the elution of heavy metals in advance, and the slag that is more stable in terms of chemical structure as a coarsely crushed raw material such as a construction base material is obtained. Recovery may be possible.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are schematic explanatory views showing a slag discharge device of a melting furnace according to the present invention. In FIG. 1, the slag discharge device is provided with a slag air cooling device 8 below a chute 6 extending downward from a slag outlet 5 of a melting furnace 1 through a connection duct 12 having an exhaust gas duct 10, and further, this slag air cooling device. A slag water cooling device 9 is connected to the tip of the device 8 on the slag advancing direction side. The slag air cooling device 8 is configured by incorporating a bucket conveyor 18 inside a heat shield hood 17. 18a, 18b, ...
Is each bucket. The slag water cooling device 9 has a screw 21 inside a long cylinder 20 that extends obliquely upward from the bottom of the water-sealed container 19. Since the water-sealed container 19 always holds water to a certain level, the lower part of the screw 21 is always located in the water-sealed container 19. That is, when the screw 21 is rotated, an object in the water of the water-sealed container 19 is carried upward by the screw 21 and dropped from the rear duct 22 downward. Further, the air cooling device 8 and the water cooling device 9 are connected by extending the lower end portion of the intermediate duct 16 into the water of the water sealing container 19, and the air cooling device 8 is kept in the sealing property.

The waste and waste incineration ash continuously supplied from the supply device 3 into the melting furnace 1 are heated by the plasma torch 2 in the melting furnace 1 and melted, and finally liquid slag is obtained. Becomes Then, with the lapse of time, the metal component having a large specific gravity in the incineration ash gradually settles, and the slag bath is separated into the upper slag layer 4a and the lower metal layer 4b. Molten slag 2 forming slag layer 4a
3 overflows from the outlet port 5 and falls in the chute 6, and the bucket 18 of the bucket conveyor 18 installed below.
a, 18b, ... Enter inside. This bucket advances in the direction of the arrow and passes through the intermediate duct 16 to the water-sealed container 1 of the water cooling device 9.
It is carried to the inside of 9. During this time, the molten slag 23 is gradually cooled and solidified, so that the strength of the slag is increased. The air cooling rate of the slag is preferably 50 ° C./min or less. This is because when the molten slag is rapidly cooled, countless fine cracks are generated in the solidified slag, and the strength of the solidified slag is significantly weakened.

Exhaust gas 14 generated in the melting furnace 1
Is guided from the outlet 5 to the exhaust gas treatment device (not shown) through the chute 6 and the exhaust gas duct 10 as shown by the arrow. The exhaust gas contains molten fly ash containing heavy metals such as lead. However, it is unavoidable that the molten fly ash adheres to and accumulates on the inner wall of the connection duct 12 to some extent. The shaded portion in the figure shows the molten fly ash 11 that has adhered and accumulated.
Therefore, it is unavoidable that the molten slag 23, which falls along the inner wall of the chute 6, adheres to some extent. Also,
Some of the accumulated molten fly ash falls and falls into the buckets 18a, 18
When mixed in b, ..., the proportion of the molten slag with the molten fly ash attached increases. In this way, the solidified slag 13 to which the molten fly ash adheres is cooled and washed in the water in the water-sealed container 19. As a result, the solidified slag 13 is cooled to about 100 ° C. or lower, and
Most of the molten fly ash attached to the surface of the solidified slag 13 is removed by washing. The solidified slag from which the molten fly ash has been removed in this way passes through the rear duct 22 and is located in the lower slag pit 1.
5 is stored.

As described above, the solidified slag of high strength, from which most of the molten fly ash, which is the elution source of heavy metals, has been removed, can be recovered at a low temperature. The recovered slag has much higher strength than mere water granulated slag, so concrete such as crushed stone for road, aggregate for road such as asphalt pavement (lower layer, upper layer, surface layer, base layer, etc.) and crushed stone for concrete It can also be used as an aggregate for use, making it a highly usable slag. Further, since it can be recovered at a low temperature of about 100 ° C. or less, it is not necessary to take special heat measures for the long cylinder 20, the screw 21, the rear duct 22, and the slag pit 15. As a result, not only the cost for heat countermeasures required for handling and the like in the conventional slag discharge device can be reduced, but also the recovery work is facilitated, which can contribute to the reduction of the total cost required for the operation of the melting furnace. .

FIG. 2 is a schematic explanatory view showing a slag discharge device according to one embodiment of the present invention (the invention according to claim 2). A structural difference from the slag discharge device shown in FIG. 1 is that a water injection nozzle 25 is provided in the intermediate duct 16. If water is jetted by such a water jet nozzle 25, solidified slag dropped from the tip of the bucket conveyor 18 in the intermediate duct 16 before the water sealing device 19, that is, the strength is increased. A considerable portion of the molten fly ash adhering to the surface of the solidified slag in the state of the molten fly ash adhering thereto is washed or softened. Subsequently, since the cleaning treatment is performed in the water cooling device 9, the effect of cleaning and removing the molten fly ash adhering to the surface of the solidified slag 16 can be further enhanced. Therefore, the solidified slag finally collected is superior to the solidified slag obtained by the slag discharge device shown in FIG. A slag that is more stable in terms of chemical structure as a crushing raw material can be obtained.

[0016]

As described above, according to the invention of claim 1 of the present invention, the slag is discharged from the slag opening provided in the lower portion of the melting furnace for melting the material to be melted, and is cooled through the chute. In a slag discharge device of a melting furnace that is cooled after being discharged by a cooling unit, a cooling unit is provided, an air cooling device is arranged at a lower part of a chute, and a water cooling device is further connected to a tip end of the air cooling device on the slag advancing direction side. The slag that has passed through the chute is cooled in the order of air cooling and water cooling and then discharged. Therefore, according to such a slag discharge device, since the high temperature slag that has dropped from the chute is first gradually cooled by the air cooling device, the strength of the slag is increased, and then the slag is further cooled by the water cooling device. , Most of the molten fly ash adhering to the slag surface is removed by washing. As a result, most of the molten fly ash that is an elution source of heavy metals is removed, so that high-strength slag with little risk of elution of heavy metals can be recovered at a low temperature. If it is the slag collected in this way, the strength is much higher than just granulated slag,
It can be used as road aggregate such as road crushed stone and asphalt pavement (lower layer, upper layer, surface layer / base layer, etc.) and concrete aggregate as crushed stone for concrete. In addition, since the slag after water cooling is cooled to about 100 ° C. or less, the heat required for the conventional air-cooled single system for the slag discharge device after the water cooling device (including the slag storage tank) is required. Not only the cost for countermeasures can be reduced, but also the recovery work is facilitated, which can contribute to the reduction of the total cost required for the operation of the melting furnace.

The invention according to claim 2 is, in the structure of the invention according to claim 1, provided with a water injection nozzle in an intermediate duct connecting the air cooling device and the water cooling device in series. As a result, between the air-cooling device and the water-cooling device, the physical strength is increased, but for the slag in the state where the molten fly ash is adhered, by injecting water from the water injection nozzle,
The cleaning and removing effect of the molten fly ash adhering to the slag surface can be enhanced. Therefore, in addition to the effect of the invention as set forth in claim 1, it has been made particularly excellent in the effect of preventing the elution of heavy metals in advance, and the slag that is more stable in terms of chemical structure as a coarsely crushed raw material such as a construction base material is obtained. Recovery may be possible.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a slag discharge device of a melting furnace according to the present invention (the invention according to claim 1).

FIG. 2 is a schematic explanatory view showing a melting furnace slag discharge device according to the present invention (the invention according to claim 2).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Plasma torch 3 Supply device 5 Slag mouth 6 Chute 8 Slag air cooling device 9 Slag water cooling device 10 Exhaust gas duct 11 Adhesion molten fly ash 12 Connection duct 13 Solidified slag 14 Exhaust gas 15 Slag pit 16 Intermediate duct 17 Thermal insulation hood 18 Bucket conveyor 19 Water-sealed container 20 Long tube 21 Screw 22 Rear duct 23 Molten slag 25 Water injection nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Higashi 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Kobe Steel Co., Ltd. Kobe Research Institute (72) Inventor Tomio Suzuki Takatsuka, Nishi-ku, Kobe-shi, Hyogo Prefecture 1-5-5 stand, Kobe Steel, Ltd. Kobe Research Institute

Claims (2)

[Claims] 1. A slag discharge device for a melting furnace, wherein the slag discharge device of a melting furnace discharges a substance to be melted from a slag outlet provided at a lower portion of the melting furnace, passes through a chute, is cooled in a cooling section, and is then discharged. The cooling unit is configured by arranging an air-cooling type cooling device in the lower part of the chute and further connecting a water-cooling type cooling device to the tip of the air-cooling type cooling device on the slag advancing direction side and passing through the chute. A slag discharging device for a melting furnace, wherein the slag is discharged after being cooled in the order of air cooling and water cooling. 2. The slag discharge device of the melting furnace according to claim 1, wherein a water injection nozzle is provided in an intermediate duct connecting the air cooling type cooling device and the water cooling type cooling device in series.