JPH0814528A - Incinerated ash melting apparatus - Google Patents

Abstract

PURPOSE:To continuously melt incinerated ash for a long time by alleviating the damage of the refractory material of a wall in a furnace. CONSTITUTION:An induction heating water-cooled copper coil 6 is embedded fixedly in the outside of a ceramic heat insulator 5, an incinerated ash supply port 2 is provided at its upper part and an exhaust port 4 for externally exhausting the melted incinerated ash (melted slag) is provided at the lower part. Refractory material walls 9, 10, 11 are sequentially laminated at the inside of the insulator 5, and graphite or coke lump for performing the operation as a heat generator is installed therein. The graphite or the lump 8 generates heat upon energizing of the coil 6 to heat the walls 9, 10, 11. The walls 9, 10, 11 are refractory materials for preheating the ash, and formed of a refractory material which is less reacted with the melted slag and less invaded with the melted slag.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention treats general municipal waste, sewage sludge and other general wastes to reduce the environmental load, and incinerates the wastes to reduce the final waste amount. The present invention relates to an incinerator ash melting treatment apparatus capable of reducing the volume of waste and making it harmless by melting the incinerated ash continuously or intermittently and vitrifying it.

[0002]

2. Description of the Related Art Conventionally, municipal wastes and other general wastes have been disposed of by landfill, but due to the increased difficulty of securing landfills, they are often incinerated and then disposed of. However, the incineration ash produces about 10% of the volume of the municipal waste before incineration, and even the site for landfill disposal of the incineration ash is becoming a tight situation. In addition, in the landfill disposal of incinerated ash, environmental influences such as ash scattering and leaching of undecomposed heavy metals and bad odor due to unburned substances have become important concerns.

Therefore, recently, in order to achieve environmental protection, the waste incineration ash is melted and the volume is reduced at the time of landfilling, and molten heavy metals are prevented from leaching from the incinerated ash and odors are prevented from unburned materials. The method of doing is beginning to be adopted. For example, as a method for melting dust incinerated ash, a plasma heating method (JP-A-1-273908), an arc discharge heating method (JP-A-2-99184), an electromagnetic induction heating method (JP-A-3-267186), JP-A-3-267187), burner combustion heating (surface melting) method (JP-A-3-263513), and the like are known.

[0004]

In the conventionally known method and apparatus for melting incinerated ash as described above, the refractory material forming the inner wall of the furnace is easily damaged by the reaction with the molten incinerated ash. Was the main cause of limiting the life of the incinerator ash melting device. The reason is that the type and content of the constituents of the incineration ash are unstable and the melting temperature fluctuates, and the melt at the melting temperature may not have a sufficient viscosity depending on the composition of the incineration ash. This is because it is not immediately discharged outside the furnace. Therefore, in the incineration ash melting treatment apparatus of this type which is actually operating at present, the temperature near the ash melting portion reaches 1400 to 1600 ° C, which causes the required viscosity of the melt (40 poise or less). There are many things).

The inner wall of the furnace of the incineration ash melting treatment apparatus is lined with a refractory material such as alumina, but the reaction proceeds at 1400 ° C to 1600 ° C during ash melting, resulting in damage to the refractory material near the ash melting part. Remarkably, it becomes necessary to frequently replace deteriorated refractories and repair the furnace body, etc., and it is difficult to obtain a smooth incineration ash melting process.

In systems other than the electromagnetic induction heating system, a pool of molten iron is required as a heat source for melting the incineration ash, and the melting device is structurally complicated. On the other hand, in the electromagnetic induction heating method, the molten iron pool is not always necessary, but in that case, the graphite lump or coke lump is charged in the magnetic field generating coil, and this is used as a heat source to bring the ash into contact with the incinerated ash. Use a melting method. That is, there is a drawback that the incinerated ash melt is likely to come into direct contact with and react with the refractory material on the inner wall of the furnace, and the wear of the refractory material is particularly remarkable.

An object of the present invention is to provide an incinerator ash melting treatment apparatus which can be used continuously for a long time by reducing damage to the refractory material on the inner wall of the furnace.

[0008]

To achieve the above object, the present invention provides a furnace body having an upper supply port and a lower discharge port, and a refractory material wall provided on an inner surface of a side wall of the furnace body.
A heating means for heating the inside of the furnace body,
In an incineration ash melting treatment device for melting incineration ash supplied from the upper supply port of the furnace body and discharging it as molten slag to the outside from the lower discharge port, in the refractory material wall, the upper refractory material wall is the heating The incinerator ash is preheated by utilizing the heat from the means, and the lower refractory material wall is made of a material that has less reaction with the molten slag and less intrusion of the molten slag.

According to the present invention, in the incineration ash melting apparatus having the above-mentioned structure, the refractory material wall is made of the same material as described above, and the lower discharge port is connected to the discharge part made of the refractory material, The discharge part heating means for heating is provided.

The upper refractory wall is made of at least one of alumina-carbonaceous material, alumina-graphite material and magnesia-coke material, preferably alumina-carbonaceous material or alumina-graphite material, more preferably alumina-carbonaceous material. It is preferably composed of graphite.

Further, the lower refractory wall is made of magnesia.
Chromium, chromium-magnesia, magnesia, alumina, silicon carbide-silicon nitride, alumina-silicon carbide-carbon, alumina-silicon carbide-graphite, preferably magnesia-chromium Alternatively, it is preferably composed of chromium-magnesia, more preferably magnesia-chromium.

The heating means may be composed of a graphite lump or coke lump provided in the furnace body, and an electromagnetic induction heating coil for heating the graphite lump or coke lump by induction heating. An electric resistance heating element that directly heats the inside of the furnace body may be used as the heating means. When a graphite lump or a coke lump is provided in the furnace body, an introduction means for introducing an inert gas into the furnace body may be provided to prevent oxidation of the graphite lump or the coke lump.

[0013]

The present inventors have conducted many experiments and theoretical studies on the melting of incinerated ash such as municipal waste. In the process, it has been recognized that there is a large difference in the degree of melting loss of the refractory material of the melt processing apparatus. Basically, in an incinerator ash melting treatment device that continuously melts incinerated ash, discharges it, and then vitrifies it, with regard to the refractory material wall provided on the inner surface of the side wall of the furnace body, the constituent components differ depending on the height direction of the furnace body By using the refractory material wall of No. 1, the degree of melting loss of the refractory material wall is reduced, and a long life is realized.

More specifically, it is optimal to have a refractory structure in which three types of refractory walls of magnesia-chromium, magnesia-carbon, and alumina-graphite are laminated on the furnace body from the bottom. I knew that. Since the magnesia-chromium refractory material is a refractory that is extremely stable even when it comes into contact with the molten incineration ash, it is suitable for the lower part of the furnace where the molten incineration ash in the highest temperature region (about 1500 ° C. or higher) is always present. Magnesia
Carbonaceous refractory materials have the same level of reactivity as alumina-based refractory materials, but the wettability of molten incineration ash is lower than that of alumina-graphite refractory materials, and molten incineration ash drip to the bottom of the furnace body. It's easy to do. Therefore, it is desirable to use the magnesia-carbon refractory material in the middle temperature range (about 1000 ° C to about 1500 ° C) between the magnesia-chromium refractory material and the alumina-graphite refractory material. The alumina-graphite refractory material is used in the low temperature range (about 1000 ° C. or less).

Magnesia-chromium instead of chrome-
It is also possible to use magnesia, magnesia, alumina, silicon carbide-silicon nitride, alumina-silicon carbide-carbon, alumina-silicon carbide-graphite. Alumina-carbon material may be used instead of magnesia-carbon material, or alumina-carbon material or magnesia-coke material may be used instead of alumina-graphite material.

Further, graphite lumps or coke lumps are stacked and filled inside the furnace body, and the discharge part connected to the lower discharge port is constantly heated by the discharge part heating means. In this way, the incineration ash melted in the furnace by electromagnetic induction heating can be smoothly and continuously discharged to the outside.

The graphite ingot can be heated up to 2000 ° C. The incineration ash is supplied to the inside of the furnace body after being preliminarily adjusted so that its components and composition are in an optimum molten state, heated and melted while dripping inside the furnace body, and dropped in a molten state. When the graphite lump is heated, it causes the following reaction and is consumed.

C + O ₂ = CO ₂ C + (1/2) O ₂ = CO If the amount of consumption is large, continuous incineration ash melting operation cannot be performed for a long time. It is important to reduce Therefore, it is desirable that the furnace body has a structure in which the furnace body is shielded from the outside air. However, even if the atmosphere inside the furnace body is replaced with an inert gas (N ₂ gas or Ar gas) as in the present invention, the consumption of graphite is also reduced. It is possible to prevent.

Table 1 shows the incineration ash at 1500 ± 30 ° C.
After melting for 50 hours at 50 ° C., the depth of the reaction layer formed inside the refractory material wall at the bottom of the furnace body was measured.

[0020]

[Table 1]

According to the results shown in Table 1, the results of the magnesia-chromic refractory material are the best.
The nitrogen carbides and the alumina-silicon carbide-carbonaceous materials should not be so different and should be regarded as having almost the same characteristics.

Further, the correlation between the change in the porosity of the magnesia-chromium refractory material of the refractory material and the amount of wear and the infiltration depth was investigated. According to the results of the survey, it was found that the amount of wear did not significantly differ from the porosity. That is,
The factor that largely controls the amount of wear should be considered not as the porosity but as the composition of the refractory material itself. The higher the porosity, the greater the infiltration depth. The high porosity means that the number of open pores on the surface of the refractory material is large, and therefore the infiltration of molten incineration ash is
It is thought to be easier.

Similar investigations were also conducted on the characteristic values of various refractory materials in the middle temperature range and the low temperature range, the wear amount at the time of specification, and the infiltration depth. The results are shown in Table 2.

[0024]

[Table 2]

According to the results shown in Table 2, although the magnesia-carbon material has a better wear amount and the alumina refractory material has a better infiltration depth, the characteristics are almost the same. Can be determined.

As described above, the components and composition ratio of the incineration ash obtained by incinerating the waste are not constant and naturally vary depending on the type of waste. In this case, the incinerator ash is melted by using the refractory wall as described above by dividing it into parts with different heat load states of the furnace body and installing graphite lumps or coke lumps in the furnace body as heat sources. Can be melted to a temperature of 100 to 150 ° C. or higher,
In addition, since the viscosity of the molten slag can be usually set to 40 poise or less, the molten slag can be quickly discharged to the outside of the furnace body. This can prevent the refractory material wall from being greatly worn.

[0027]

Embodiments of the present invention will now be described in detail with reference to the drawings. (First Embodiment) FIG. 1 shows a cross section of an incinerator ash melting apparatus of the present invention. The furnace body 1 is composed of a semi-enclosed container as a whole, and a supply port 2 for the incineration ash to be treated is provided above the container body 1.
A gas discharge hole 3 for sending out exhaust gas generated when the incineration ash is melted is provided, and a molten incineration ash discharge port 4 is provided in the lower portion. The outer wall of the furnace body 1 is composed of a ceramic heat insulating material 5 obtained by kneading alumina cement, for example, with water glass or the like. Ceramic insulation 5
An induction heating water-cooled copper coil 6 having an internal hollow portion is embedded and fixed on the outer side of, and cooling is performed by flowing water 7 into the internal hollow portion.

A lid 13 having an incineration ash supply port 2, a gas discharge hole 3 and a gas introduction pipe 12 is put on the upper part of the furnace body 1. A vertically movable bell jar 26 is provided side by side with the incineration ash supply port 2, and the incinerator ash supply port 2 is closed by the bell jar 26 when the incineration ash is not charged. Further, a copper pipe 14 is provided on the outer surface of the lid 13, and the lid 13 can be cooled by circulating water therein.

Refractory walls 9, 10 and 11 are sequentially laminated inside the ceramic heat insulating material 5, and graphite or coke lumps 8 serving as a heating element are installed inside the walls. The graphite or coke lump 8 generates heat by energizing the water-cooled copper coil 6 for induction heating, and heats the refractory material walls 9, 10, 11. The gas introduction pipe 12 is for introducing an inert gas at any time in order to reduce the combustion and consumption of the graphite or coke lump 8.

The molten incineration ash discharge port 4 in the lower part of the furnace body 1 is formed of a cylindrical graphite or alumina-carbonaceous refractory material, and an electromagnetic induction for smoothly discharging the molten incineration ash is provided on the outer peripheral portion thereof. A water-cooled copper coil 15 for heating is installed.

FIG. 2 shows an embodiment of an incineration ash melting treatment system using the furnace body 1 described above. In the figure,
Reference numeral 17 is an incineration ash storage hopper, in which incineration ash 18 of waste that has been incinerated in an incinerator (not shown) is stored and while mixing the adjustment components from the adjustment component supply hopper 19,
It is supplied to the furnace body 1 via the incineration ash supply port 2. The molten incineration ash 20 heated and melted inside the furnace body 1 is introduced into the cooling pit 25 via the molten incineration ash discharge port 4, and is rapidly cooled by the water 23 in the cooling pit 25. Cooling pit 25
A belt conveyor 22 is installed therein, and the cooled and solidified slag 21 is automatically taken out by the belt conveyor 22 and transported by a transport vehicle 24. In FIG. 2, 27 is a mixer, and 28 is an incineration ash adjusting component conveying path.

Table 3 shows the operation results of the incineration ash melting treatment system. Further, when the incineration ash melting treatment system was used to continuously perform the ash melting treatment, the data shown in Table 4 were obtained.

[0033]

[Table 3]

[0034]

[Table 4]

Table 4 shows that the incineration ash (1) and the incineration ash (2) have different compositions depending on the time when they are charged into the furnace body. And solidified slag (1)
And (2) show that the molten incineration ash can be continuously discharged from the melt processing apparatus with the components shown in Table 4. Table 5 shows other operating data in the incineration ash melting process.

[0036]

[Table 5]

(Second Embodiment) Next, a second embodiment of the present invention will be described. In this example, the incineration ash is melted smoothly,
Measures were taken to prevent the consumption of graphite lumps, which are heating elements, in order to discharge the molten lumps outside the melt processing equipment without delay. According to this, it was found that the consumption of graphite can be prevented by introducing the high-temperature heated nitrogen gas into the furnace through the gas introduction pipe 12 shown in FIG. Introduction amount of high temperature heating nitrogen gas is about 50 Nm
³ / min.

The consumption of graphite was compared between the case where gas was introduced and the case where gas was not introduced. Table 6 shows the results.
In each case, the refractory material in the high temperature part was magnesia-chrome, and the refractory material used in the middle and low temperature parts was alumina.

As shown in Table 6, if nitrogen gas is not introduced into the incinerator ash melting furnace, the heating element consumption rate (= heating element consumption amount × 100 / ash input amount) is significantly different, and it is clear that nitrogen gas is introduced. The effect of is recognized. It was revealed that when nitrogen gas was not introduced, not only was the wear rate of the heating element high, but the viscosity of the molten slag was also high, and discharge from the furnace body was extremely difficult. The reason for this is that the heating element oxidizes and is consumed, so that what was in the bulk state in the initial stage of heating becomes powdery or granular, and the powdered or granular carbon is contained in the molten slag. This is because the viscosity of the molten slag increases. The effect of introducing nitrogen gas becomes more remarkable particularly when high-temperature heating gas is introduced.

(Third Embodiment) Next, a third embodiment of the present invention will be described. In this embodiment, the molten incineration ash discharge unit (see FIG.
The characteristic is that an electric resistance heating element is used in place of the electromagnetic induction heating water-cooled copper coil for the heating element of reference numeral 15).

In the case of a water-cooled copper coil for electromagnetic induction heating, a separate heating element is always required. In this case, the heating element itself often coincides with the molten incineration ash discharge section. Therefore, in this case, the material of the discharge part is required to have a durability against the magnetic field generated by the electromagnetic induction and the reaction of the molten incineration ash discharged from the furnace body. On the other hand, when the electric resistance heating element is used for local heating,
Since it is not necessary to generate magnetism, any material may be used as long as it considers only reactivity with molten incineration ash.

Table 7 shows the results of experiments comparing the electromagnetic induction heating method and the electric resistance heating method as the melting incineration ash heating method at the time of discharge.

[0043]

[Table 6]

The results shown in Table 7 show that the main components of incinerated ash completely melted at the bottom of the furnace body are CaO = 31% and SiO ₂ =
43%, Al ₂ O ₃ = 20%, MgO = 3.5%, Na ₂ O
= 1.5%, Fe ₂ O ₃ = 1.0%, the melting point of incineration ash is about 1380 ° C, and the data when the temperature of molten incineration ash just before discharge from the furnace body is 1500 ± 15 ° C is there. That is, the viscosity of the molten incineration ash under the above conditions was about 20 poise. A difference in the viscosity of the molten incineration ash at the discharge part is recognized depending on the difference in the local heating method.When the local heating method of the molten incineration ash discharge part is the electric resistance heating method, the difference in the discharge part is higher than that of the electromagnetic induction heating method. This shows that the temperature of the molten incinerator ash does not decrease so much that the molten incinerator ash easily flows.

[0045]

[Table 7]

Finally, Table 8 shows a comparison between the conventional example and the present invention as seen from the operation results.

[0047]

[Table 8]

[0048]

As described above, according to the present invention,
Since the refractory material wall having high reaction resistance to the molten slag is installed on the inner surface of the side wall of the furnace body, the temperature of the molten slag in the furnace body can be maintained at a high temperature. As a result, it is possible to prevent the refractory material wall on the inner surface of the side wall of the furnace body from being damaged, and to perform the work of melting and reducing the volume of incinerated ash continuously for a long time.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an incineration ash melting processing apparatus of the present invention.

FIG. 2 is an overall configuration diagram of an incineration ash melting treatment system in which the incineration ash melting treatment device of FIG. 1 is installed.

[Explanation of symbols]

 1 furnace main body 2 incineration ash supply port 3 gas discharge hole 4 molten incineration ash discharge port 5 ceramic heat insulating material 6 water-cooled copper coil for induction heating 7 water 8 graphite or coke lump 9-11 refractory wall 12 gas inlet pipe 13 lid 14 Copper pipe 15 Water-cooled copper coil for electromagnetic induction heating 17 Incinerator ash storage hopper 18 Incinerator ash 19 Adjusting component supply hopper 20 Molten incinerated ash (molten slag) 21 Solidification slag 22 Belt conveyor 23 Water 24 Transport vehicle 25 Cooling pit 26 Vertically movable Type bell jar 27 Mixer 28 Incineration ash adjustment component transport path

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoyuki Nishikawa 800 Tomita, Ohira-cho, Shimotsuga-gun, Tochigi Prefecture Living Equipment Division, Hitachi, Ltd.

Claims (9)

[Claims] 1. A furnace body having an upper supply port and a lower discharge port, and a refractory material wall provided on an inner surface of a side wall of the furnace body.
A heating means for heating the inside of the furnace body,
In an incineration ash melting treatment apparatus for melting incineration ash supplied from the upper supply port of the furnace body and discharging it as molten slag to the outside from the lower discharge port, in the refractory material wall, the upper refractory material wall is the heating Composed of a material that preheats the incineration ash using heat from the means,
An incinerator ash melting treatment apparatus characterized in that the lower refractory material wall is made of a material that is less likely to react with the molten slag and is less likely to penetrate the molten slag. 2. A furnace main body having an upper supply port and a lower discharge port, and a refractory material wall provided on an inner surface of a side wall of the furnace main body.
A heating means for heating the inside of the furnace body,
In an incineration ash melting treatment apparatus for melting incineration ash supplied from the upper supply port of the furnace body and discharging it as molten slag to the outside from the lower discharge port, in the refractory material wall, the upper refractory material wall is the heating Composed of a material that preheats the incineration ash using heat from the means,
The lower refractory material wall is made of a material that has less reaction with the molten slag and less invasion of the molten slag, and a discharge portion made of a refractory material is connected to the lower discharge port, and the discharge portion is heated to be discharged. An incinerator ash melting treatment apparatus, characterized in that a section heating means is provided. 3. The incinerator ash melting treatment apparatus according to claim 2, wherein the discharge part is formed of at least one of magnesia-chromium, silicon carbide-silicon nitride, and alumina-silicon carbide-carbon. An incineration ash melting treatment device characterized by being used. 4. A furnace body having an upper supply port and a lower discharge port, a graphite lump or a coke lump provided inside the furnace body, a refractory wall provided on an inner surface of a side wall of the furnace body, and Provided on the outer surface of the side wall of the furnace body, and comprising an electromagnetic induction heating coil for heating the graphite lump or coke lump by electromagnetic induction heating, the incineration ash supplied from the upper supply port of the furnace body is melted as molten slag, In the incineration ash melting treatment apparatus for discharging to the outside from the lower discharge port, of the refractory material walls, the upper refractory material wall is composed of a material that preheats the incineration ash by utilizing heat from the graphite lump or coke lump. The incineration ash melting treatment apparatus is characterized in that the lower refractory material wall is made of a material that has less reaction with the molten slag and less intrusion of the molten slag. 5. A furnace body having an upper supply port and a lower discharge port, a graphite lump or a coke lump provided inside the furnace body, a refractory wall provided on an inner surface of a side wall of the furnace body, Provided on the outer surface of the side wall of the furnace body, and comprising an electromagnetic induction heating coil for heating the graphite lump or coke lump by electromagnetic induction heating, the incineration ash supplied from the upper supply port of the furnace body is melted as molten slag, In the incineration ash melting treatment apparatus for discharging to the outside from the lower discharge port, of the refractory material walls, the upper refractory material wall is composed of a material that preheats the incineration ash by utilizing heat from the graphite lump or coke lump. However, the lower refractory wall is made of a material that has less reaction with the molten slag and less invasion of the molten slag, and in order to prevent oxidation of the graphite lump or coke lump, Ash melting treatment apparatus characterized in that a means for introducing an inert gas to. 6. The incinerator ash melting treatment apparatus according to claim 5, wherein the graphite lump or the coke lump is stacked or hung inside the furnace body. 7. A furnace body having an upper supply port and a lower discharge port, and a refractory material wall provided on an inner surface of a side wall of the furnace body.
An electric resistance heating element provided in the furnace body for heating the inside of the furnace body; and incineration for melting the incineration ash supplied from the upper supply port of the furnace body and discharging it as molten slag to the outside from the lower discharge port. In the ash melting treatment apparatus, among the refractory material walls, the upper refractory material wall is made of a material that preheats the incineration ash by using heat from the electric resistance heating element, and the lower refractory material wall is the melting material. An incinerator ash melting treatment apparatus, which is made of a material that has a small reaction with slag and a small amount of molten slag infiltration. 8. The incinerator ash melting treatment apparatus according to claim 1, wherein the upper refractory material wall is made of alumina-carbonaceous, alumina-
At least one of graphite and magnesia-coke
An incinerator ash melting treatment device characterized in that it is formed of various types. 9. The incinerator ash melting treatment apparatus according to claim 1, wherein the lower refractory material wall is magnesia-chromium, chromium-magnesia, magnesia, An incineration ash melting treatment apparatus formed of at least one of alumina, silicon carbide-silicon nitride, alumina-silicon carbide-carbon, and alumina-silicon carbide-graphite.