JP3927917B2 - Waste treatment system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a waste treatment system.
[0002]
[Prior art]
As an example of a waste treatment system, combustibles in pyrolysis gas and pyrolysis residue generated by pyrolyzing waste, and incombustible particles entrained in the pyrolysis gas by this combustion heat There are some which are effectively used as an aggregate of building materials and paving materials by melting incombustible powders contained in the body and pyrolysis residue into slag.
[0003]
That is, the pyrolysis residue contains combustible materials such as pyrolytic carbon and rubble incombustible materials such as glass, ceramic pieces, and concrete pieces. They are separated and used as fuel in combustion melting. At this time, if the pyrolysis residue is mixed with non-combustible particles produced by pulverization, the non-combustible particles are mixed with combustible particles such as pyrolytic carbon and separated. To make molten slag.
[0004]
As such a thermal decomposition residue separation device, a fluid type separation device has been proposed (see, for example, Patent Document 1). In this apparatus, air is injected into a bed containing cinnabar as a fluid medium to form a fluidized bed, and a pyrolysis residue is supplied to the fluidized bed to form granular carbon and non-combustible materials, relatively large-sized metals, It separates rubble. According to this flow fractionation, the carbon recovery rate is good because the carbon adhering to the metal and rubble can be separated as compared with the case of fractionation with a sieve.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-219417 (page 2-3, FIGS. 1 and 6)
[0006]
[Problems to be solved by the invention]
However, it has been found that when cinnabar sand is used as a fluid medium, incombustible materials may not be sufficiently melted in the combustion melting furnace. If the incombustible material is not sufficiently melted, the viscosity of the slag in the molten state is increased and the shape of the molten slag is deteriorated, so that sufficient strength as an aggregate cannot be obtained.
[0007]
As a result of examining the cause of the poor melting of the incombustible material, the present inventors have found that the cause is that a part of the cinnabar sand for the fluidized medium is supplied to the combustion melting furnace along with pyrolytic carbon. Got. That is, by supplying silica sand containing SiO2 as a main component to the combustion melting furnace, the ratio of SiO2 in the incombustible material in the combustion melting furnace increases, and the ratio of CaO and SiO2 that serves as one standard for melting the incombustible material is Out of the proper range. This ratio of CaO and SiO2 is called basicity, and the melting temperature of the incombustible material increases as the basicity goes out of the proper range, which causes poor melting. For example, when the basicity is in the range of 0.4 to 1.0, the melting temperature of the incombustible material is 1300 ° C. at the maximum, and it can be melted well by setting the combustion temperature of the combustion melting furnace to 1300 ° C. If the degree is out of this range and the melting temperature rises, poor melting occurs.
[0008]
Then, this invention makes it a subject to improve the intensity | strength fall of the molten slag caused by the dredged sand used as a fluid medium, when producing | generating a molten slag by using the granular material classified by the flow separation as a raw material.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is characterized by using molten slag as a fluid medium instead of dredged sand. As a result, even when molten slag is entrained in the granular material during flow separation, the molten slag contains CaO and SiO2 in the same proportion as the incombustible material, so that the basicity of the incombustible material is changed. There is no. Accordingly, since the melting temperature of the incombustible material does not change, poor melting of the incombustible material can be prevented in the combustion melting furnace, so that the decrease in the strength of the molten slag caused by dredged sand can be improved.
[0010]
Specifically, the waste treatment system is configured to pulverize molten slag having a basicity CaO / SiO2 of 0.4 to 1.0 manufactured in a combustion melting furnace and supply the molten slag to a fluid separation tank. Here, the particle size of the molten slag is large enough not to be discharged by the airflow in the flow separation tank, and small enough to flow well in the flow separation tank, and is adjusted to, for example, about 0.5 to 1 mm. It is preferable to do.
[0011]
In this case, solidification, pulverization, and supply of slag are performed using various known devices, for example, slag discharged from a combustion melting furnace is dropped into a water tank filled with water, cooled and solidified, The molten slag in the water tank can be conveyed to the flow separation tank by a conveyor, and the molten slag can be crushed by a biaxial facing roller or the like in the middle. Here, for example, a storage tank such as a hopper in which the molten slag is stored and a supply unit such as a valve and a screw feeder are preferably provided. Thereby, for example, the amount of molten slag supplied into the separation tank can be adjusted. This supply amount is appropriately set so that, for example, a certain amount of molten slag stays in the separation tank, for example, from the degree of wear due to wear of the molten slag in the separation tank. Moreover, the molten slag manufactured with the waste processing system of another system | strain can also be used as a fluid medium.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an overall configuration diagram of an embodiment of a waste treatment system according to the present invention. As shown in the figure, the waste 1 is pulverized to an appropriate size and charged into the pyrolysis reactor 2. The pyrolysis reactor 2 is formed by using, for example, a horizontal rotating drum, and heats the waste material 1 fed from one end to the other end while heating and pyrolyzing it in a low oxygen atmosphere, and heat from the other end. The cracked gas 3 and the pyrolysis residue 4 are discharged. The pyrolysis gas 3 is supplied to the combustion melting furnace 5 and burned. The pyrolysis residue 4 includes combustible materials such as carbon generated by pyrolysis and non-combustible materials such as metal pieces, glass, ceramics, and concrete pieces contained in the waste 1. Among these, pyrolytic carbon can recover heat by being burned. Therefore, it is preferable that the pyrolytic carbon is separated from other pyrolysis residues and burned in the melting combustion furnace 5. Therefore, the pyrolysis residue 4 is guided to a fluid type separation device 6 so as to be separated into pyrolytic carbon and other non-combustible materials.
[0013]
That is, the fluid type separation device 6 includes a separation tank 24 in which the fluid medium 23 stays. A diffuser header pipe 25 is inserted and disposed in the lower part of the separation tank 24, and external air is supplied to the diffuser header pipe 25 by, for example, a forced blower. With this configuration, the fluid medium in the separation tank 24 is fluidized by the air ejected from the diffuser header pipe 25. At this time, the powder 7 in the pyrolysis residue charged into the fluidized bed is blown off into the upper space of the separation tank 25 by the air ejected from the diffuser header pipe 25. In addition, the powder body 7 adhering to relatively coarse-grained metals in the pyrolysis residue is scraped off by the fluid medium 23 and blown off into the upper space of the separation tank 24. In addition to pyrolytic carbon, these granular materials 7 include incombustible granular materials. The granular material 7 containing pyrolytic carbon is supplied to the combustion melting furnace 5 from the upper part of the separation layer 24. It has come to be.
[0014]
On the other hand, a screw feeder 26 is installed at the bottom of the separation tank 24, and the relatively coarse pyrolysis residue that has not been blown away by the air ejected from the diffuser header pipe 25 is below the fluidized bed in the separation tank 24. And is discharged from the separation tank 24 by the screw feeder 26, and non-combustible materials such as metals such as iron and aluminum are further separated and collected as valuable materials.
[0015]
In the combustion melting furnace 5, the pyrolysis gas 3 and the pyrolysis carbon of the granular material 7 are subjected to combustion treatment. With this combustion heat, the incombustible particulates entrained in the pyrolysis gas 3 are melted, fall along the furnace wall from the bottom of the furnace into, for example, a water tank, and are discharged as molten slag 8. The combustion exhaust gas 9 from the combustion melting furnace 5 is guided to the heat recovery device 10 and recovered. The heat recovery device 9 includes, for example, a heat exchanger that heats a gas (for example, air) used as a heat decomposition heat source of the heat decomposition reactor 2, a waste heat boiler that generates steam used for power generation, and the like. can do. The exhaust gas 11 discharged from the heat recovery device 10 is guided to a dust collector 12 including a bag filter and the fly ash contained in the exhaust gas 11 is collected. The exhaust gas 13 discharged from the dust collector 12 is guided to a desalinator 15 to which a desalting agent 14 is added and configured by a bag filter. In the desalting apparatus 15, a layer of the desalting agent 14 is formed on the filter cloth surface of the bag filter, and the chlorine and sulfur components in the exhaust gas 16 passing through the desalting agent layer react with the desalting agent 14. Separated from the exhaust gas 13. The exhaust gas 16 that has passed through the desalinator 15 is discharged into the atmosphere from the chimney 18 via the induction blower 17.
[0016]
Next, the structure which concerns on the characteristic part of this embodiment is demonstrated. In the present embodiment, the molten slag 8 discharged from the combustion melting furnace 5 is crushed and supplied to the fluid separation device 6. That is, a part of the molten slag 8 discharged from the combustion melting furnace 5 is guided to the pulverizer 19. The pulverizer 19 is configured by using a known device for pulverizing solids, for example, a biaxial facing roller, and the molten slag 8 is adjusted to have a particle diameter of, for example, about 0.5 to 1 mm. Yes. The molten slag particles 20 pulverized by the pulverizer 19 are supplied to a storage hopper 21. A discharge port is provided at the bottom of the storage hopper 21, and a screw feeder 22 is attached to the discharge port. The molten slag particles 20 discharged from the screw feeder 22 are supplied into the separation tank 24 of the fluid type separation device 6.
[0017]
By comprising in this way, the molten slag 8 discharged | emitted from the combustion melting furnace 5 is grind | pulverized, becomes the granule 20, and is thrown into the flow separation tank 57. FIG. Accordingly, the molten slag can be used as the fluid medium 23 of the fluid type separation device 6.
[0018]
As described above, according to the present embodiment, since the molten slag particles 20 are used as the fluid medium 23 instead of the cinnabar, a decrease in the strength of the molten slag 8 caused by the cinnabar can be avoided. That is, even if the molten slag particles 20 used as the fluid medium are crushed by the flow and are accompanied by the particles 7, the particles 20 are composed of CaO and SiO2 at the same ratio as the incombustibles in the particles 7. Since it is contained, the basicity of the incombustible material supplied to the combustion melting furnace 5 is not changed. Therefore, it is possible to prevent the melting temperature of the incombustible material from rising and to prevent the incombustible material from being poorly melted in the combustion melting furnace 5. As a result, since the slag melts uniformly as a whole, it is possible to prevent a decrease in strength of the molten slag 8.
[0019]
Moreover, in this embodiment, since the molten slag 8 once melted in the combustion melting furnace 5 is used as the fluid medium, even if these are accompanied by the powder 7 and supplied to the combustion melting furnace 5, they are relatively easily melted. be able to. In addition, heavy metals such as lead are enclosed in the molten slag 8, for example, but according to the present embodiment, these heavy metals can be more stably sealed, and safety is improved. It can be further increased.
[0020]
According to the inventor's knowledge, the sand contains less than 2% CaO and 98% or more of SiO2, and the molten slag 8 varies depending on the type of waste to be treated. CaO is contained in a range of 17 to 27% and SiO2 in a range of 29 to 53%. The composition of the molten slag 8 is, for example, in the range of 0.4 to 1.0 when the basicity is replaced. Actually, even when the waste treatment plant was operated using these molten slag granules 20 as the fluidized medium 23, problems such as undissolved unburned matter in the combustion melting furnace 5 did not occur.
[0021]
Moreover, in this embodiment, although the separation tank 24 was a diffused header pipe type, the same effect can be obtained even if it is a diffused plate type or diffused floor type. In the case of the diffuser plate method, a single diffuser plate may be inclined and attached to the bottom of the separation tank 24, and the pyrolysis residue may be discharged from one side of the bottom of the separation tank 24 with a screw feeder. Alternatively, two diffuser plates may be attached so as to be lowered at the bottom center of the separation tank 24, and the pyrolysis residue may be discharged from the center of the bottom part of the separation tank 24 with a screw feeder.
[0022]
In addition, the particle size of the molten slag g pulverized by the pulverizer 19 is large enough not to be blown by the blown air and small enough to flow well, for example, adjusted to about 0.5 to 1 mm. The adjustment of the particle size can be performed by grinding the molten slag 8.
[0023]
Moreover, the screw feeder 22 of this embodiment can adjust the supply amount of the granular material 20 of the molten slag supplied into the separation tank 24 of the fluid type separation apparatus 6. This supply amount is appropriately set based on, for example, the degree of wear of the molten slag 20 in the separation tank so that a certain amount of the molten slag 20 always stays in the tank.
[0024]
【The invention's effect】
As described above, according to the present invention, in the case where molten slag is generated using the granular material separated by flow separation as a raw material, the strength reduction of molten slag caused by dredged sand used as a fluid medium is improved. Can do.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a detailed diagram for explaining a separation process of an embodiment of a waste treatment plant to which the present invention is applied.
[Explanation of symbols]
2 Pyrolysis reactor 5 Combustion melting furnace 6 Fluid type separation device 19 Pulverizer 21 Storage hopper 22 Screw feeder

Claims (3)

A pyrolysis reactor that heats waste to decompose it into pyrolysis gas and pyrolysis residue, and separates flammable and non-flammable particles in the pyrolysis residue by flowing the fluid medium in the tank with air flow Waste comprising: a fluidized separation tank that burns the pyrolysis gas and the powder discharged from the fluidized separation tank to melt the incombustible powder and slag it In the processing system,
A waste treatment system, wherein the slag having a basicity CaO / SiO2 of 0.4 to 1.0 discharged from the combustion melting furnace is pulverized and used as the fluid medium. A pyrolysis reactor that heats waste to decompose it into pyrolysis gas and pyrolysis residue, and separates flammable and non-flammable particles in the pyrolysis residue by flowing the fluid medium in the tank with air flow Waste comprising: a fluidized separation tank that burns the pyrolysis gas and the powder discharged from the fluidized separation tank to melt the incombustible powder and slag it In the processing system,
A waste treatment system characterized in that slag having a basicity CaO / SiO2 of 0.4 to 1.0 produced by a separate waste treatment system is pulverized and used as the fluid medium. The waste treatment according to claim 1 or 2, further comprising: a storage tank for storing the molten slag; and a supply unit that supplies the molten slag in the storage tank to the flow separation tank. system.

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