JPS621483B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for incinerating and melting waste,
In detail, it relates to a method for increasing combustion efficiency and melting efficiency by separating low-calorie combustibles, high-calorie combustibles, and non-combustibles contained in waste such as municipal waste in advance and then appropriately dividing the flow. It is something.

Municipal waste includes low-calorie combustibles such as paper and wood; high-calorie combustibles such as rubber and plastic;
Since it contains combustible materials such as ash, rubble, and glass along with kitchen waste, its combustibility is not always good, and various measures are required for incineration. In particular, waste containing a large amount of combustible materials (particularly ash) has a low calorific value and is difficult to incinerate in a mixed state, so it is necessary to separate it from the combustible materials before feeding it into an incinerator.

In other words, the non-combustibles themselves do not have heat generating power and do not contribute to combustion, and the ash in particular has strong water absorption and is put into the incinerator in the form of lumps, so at that time, water is brought into the furnace and produces low-level heat generation. In addition to causing a decrease in the amount of dust, when it dries due to the heat of combustion in the furnace, it returns to fine powder and fills the gaps between dust, or it progresses further and becomes a fused substance that obstructs air permeability. Prevents the combustion of garbage.

On the other hand, the oil situation has continued to deteriorate, and coal has come to be used industrially as boiler fuel, and in some regions, charcoal briquettes and charcoal have come to be widely used for home heating. As a result, the composition of municipal waste has changed and the ash content has tended to increase, and the above-mentioned damage caused by ash being brought into the incinerator has become impossible to ignore in some regions.

There are methods for separating combustibles and non-combustibles, such as by making use of differences in shape, bulk specific gravity, particle size, etc., but whichever method is used, it is important to completely separate the two. It is virtually impossible to do so, and a considerable amount of combustible materials will be mixed into the separated non-combustible materials. Therefore, if this is dumped as is in a landfill or the like, odors and sewage will be generated due to the decomposition of the combustible matter (organic matter) mixed in, which will pose a problem in terms of environmental conservation.

On the other hand, the separated combustibles are reduced in volume through incineration, but the incineration residue (ash, dust, sludge, etc.)
contains a large amount of toxic heavy metals, so if they are disposed of as is, they will cause environmental damage due to the elution of heavy metals. Therefore, in incineration equipment, after solidifying the incineration ash and residue containing heavy metals by adding an appropriate solidifying agent (cement, asphalt, etc.),
Landfill or ocean dumping. However, the solidification treatment method requires a large amount of cost, and there is no guarantee that environmental pollution can be completely eliminated.

The present invention has been made in view of these circumstances, and its purpose is to provide a waste treatment method that can make separated incombustibles, combustion residues, etc. discharged from incineration facilities harmless from an environmental perspective. This is what we are trying to provide.

Therefore, the waste incineration/melting treatment method of the present invention involves separating waste into low-calorie combustibles, high-calorie combustibles, and non-combustibles, and injecting the low-calorie combustibles into an incinerator for combustion and ashing. After recovering the iron content from the ash and residue discharged from the incinerator, they are put into a melting furnace together with the above-mentioned non-combustible materials and high-calorie combustible materials, where they are melted and turned into slag by an auxiliary combustion burner, while the exhaust gas from the incinerator and melting furnace is collected. The gist is that the dust collected by being guided to the dust device is also led to the melting furnace to be melted and turned into slag, and the molten slag is cooled and solidified.

The above-mentioned non-combustible materials, especially those whose main component is combustion ash, contain not only a considerable amount of harmful heavy metals, but also a considerable amount of organic matter mixed in during the separation process from combustible materials. Melting treatment is considered to be the most effective method for rendering these materials harmless. The reason for this is that when the melting process is performed, the mixed organic matter is burned away and no longer causes problems such as spoilage, and the harmful heavy metals are turned into slag along with other incombustible materials, and their elution is also prevented. However, since non-combustible materials have no heat generation source, a large amount of heat must be applied to melt them, which increases fuel costs. Therefore, in order to put such technology into practical use, it is necessary to establish a technology that can perform melting processing with low fuel costs. Therefore, the inventor of the present invention thought that the above purpose could be achieved by using the combustible components in the waste as a heat source for melting processing, and after further investigation, the inventor found that the high calorie components in the combustible material could be used as a heat source for melting. This is the result of the idea of the method of the present invention, which is used as a. It has also been pointed out that high calorie combustible materials excessively raise the temperature inside the furnace when burned, shortening the life of the combustion furnace.However, in the present invention, this is separated from low calorie combustible materials. Since only the materials are incinerated, the lifespan of the incinerator can be extended. Moreover, since there is a method of using a high-calorie combustible material as a heat source for melting processing that requires high-temperature heating, the thermal balance of the processing equipment as a whole is also significantly improved.

The configuration and effects of the present invention will be explained below with reference to the drawings, but the examples are not intended to limit the present invention, and design changes may be made as appropriate in keeping with the spirit of the above and below. All are included within the technical scope of the present invention.

FIG. 1 is a flow diagram illustrating a waste treatment system to which the method of the present invention is applied. The collected waste G is first put into a storage pit.
The waste that has become agglomerated in the storage pit due to the accumulation pressure, etc. is then crushed into small particles by a crushing device, and then supplied to a separator to produce low-calorie combustibles A,
Separated into high calorie combustibles B and non-combustibles. Although there are no particular restrictions on the configuration of the crushing device and separation device, the former includes a crushing device that applies mechanical vibration or shock to release the bonds of nodules, especially ash, etc., into small particles or powder. can be mentioned. For the latter, for example, waste is first separated into combustibles and non-combustibles (mainly ash) using particle size differences, and then combustibles are separated into low-calorie combustibles A (low specific gravity) using differences in specific gravity. ) and high-calorie combustibles B (high specific gravity). Although it is desirable that these separations be as complete as possible, in reality, a considerable amount of contamination cannot be avoided, and some contamination is permitted in the present invention. The separated low-calorie incombustible materials A are introduced into an incinerator (for example, a stoker-type incinerator) and are incinerated. Then, the incineration residue _G1 discharged from the incinerator is supplied to an iron recovery device (for example, a magnetic separator) to recover Fe, and the recovered residue _G2 , which mainly consists of ash, is supplied to the melting furnace, as shown below. Melt it together with non-combustible materials.

On the other hand, high-calorie combustible material B and non-combustible material are put into a melting furnace and heated by an auxiliary combustion burner such as heavy oil firing, but this auxiliary heating causes combustible material B to ignite.
The temperature inside the furnace is 1250~ due to the heat of combustion.
Even though the temperature is raised to about 1500°C, the incombustible materials and incineration residue can be easily brought into a molten state. If the ratio of non-combustibles fed into the melting furnace becomes too large, the amount of heat generated by combustibles B will become insufficient and the amount of combustion aid will have to be increased, while the amount of combustibles B will be relatively large. If it becomes too much, the amount of heat generated will become excessive, so it is better to adjust the ratio of both inputs in consideration of the optimum amount of heat required for melting. Furthermore, at this time,
The combustibles or unburnt materials contained in the uncombustible materials or recovered residue _G2 are burned, and the generated ash is melted together with the noncombustible materials.

On the other hand, exhaust gas generated from incinerators or melting furnaces is sent to exhaust gas treatment equipment for treatment, and the dust G ₄ collected by the dust collector, which is part of the treatment equipment, is also melted and treated together with incombustible materials. It doesn't matter. The molten slag _G3 is then led from the melting furnace to a slag cooling device where it is cooled and solidified, but the harmful heavy metals are sealed inside together with the solidified slag, so there is no risk of them leaching out even if the slag is dumped as is. Since the obtained solidified slag is a hard material made of stable metal oxide, it can be effectively used as an aggregate or the like. In this case, the rapidly cooled slag has a small bulk specific gravity, so it is useful as a ballast for roadbeds, a lightweight aggregate for concrete, etc., and the slowly cooled slag has a high hardness, so it is useful as a reinforcing aggregate, etc.

The basic configuration of the present invention is as described above, but the waste brought into the treatment facility includes combustible and non-combustible materials collected separately, and in this case, instead of the line from the storage pit, The combustible waste _S1 , which has been collected separately, is input into the crushing device and processed in the same way as described above, and the separately collected non-combustible waste _S2 is introduced into the non-combustible line and processed in the melting furnace in the same manner as above. Alternatively, a method of incineration or melting may be adopted. Furthermore, it is also possible to appropriately combine the separated collection materials and the bulk collection materials for incineration and melting treatment.

The present invention is roughly configured as described above, and by using high-calorie components in waste as a heat source for melting noncombustibles, it is possible to significantly reduce the amount of supplementary fuel required for melting, and also to prevent overheating of the incinerator. It has become possible to suppress thermal deterioration and extend its life.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram of a waste melting treatment system according to the present invention. G...Waste, _G1 ...Incineration residue, _G2 ...Recovered residue, _G3 ...Melted slag, _G4 ...Dust, _S1 ...
...separately collected combustible waste, S ₂ ...separately collected non-combustible waste.

Claims (1)

[Claims] 1. A method of incinerating and melting municipal waste, etc., in which waste is separated into low-calorie combustibles, high-calorie combustibles, and non-combustibles, and the low-calorie combustibles are put into an incinerator and burned. After collecting the iron content from the ash and residue discharged from the incinerator, they are put into a melting furnace together with the above-mentioned non-combustible materials and high-calorie combustible materials, where they are melted and turned into slag by an auxiliary combustion burner, and then removed from the incinerator and melting furnace. The exhaust gas is led to the dust collector and the dust collected is also led to the melting furnace and melted.
A method for incinerating and melting waste, characterized by converting it into slag, and cooling and solidifying the molten slag.