JPH08278015A - Treating method of waste - Google Patents

Abstract

PURPOSE: To provide waste treating method, restraining the generation of poisonous substances such as dioxin and the like and reducing the adhesion of resins, contained in waste, to the inner wall of an incinerating furnace by fusion. CONSTITUTION: Wastes 21 receive dechlorinating reaction in a dechlorinating decomposition furnace 1 and the constituent of chlorine is removed. The dechlorinated wastes 28 are guided into a main combustion and melting furnace 3 and are burnt completely by oxygen enriched air 7 from an oxygen supplying facility 26 while incombustibles are molten and are discharged into a molten slag recovery device 8 as molten slag 29. On the other hand, exhaust gas of combustion is burnt completely in a recombustion chamber 4. Exhaust gas, discharged out of the dechlorinating decomposition furnace 1, is sent into a thermal decomposition exhaust gas washing device 2. Further, the molten slag 29 is changed into sand type slag having a given grain size by a molten slag classifying device 12 and is added to the wastes, supplied into the dechlorinating decomposition furnace 1, to prevent the welding to the inner wall of the decomposition furnace or between resins mutually.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incineration / melting treatment method applied to the treatment of waste such as municipal solid waste and industrial waste.

[0002]

2. Description of the Related Art Conventionally, when waste containing a large amount of chlorine compounds such as vinyl chloride is incinerated, a large amount of HCl gas, FeCl ₃ fumes, etc. are volatilized in the combustion exhaust gas, and the tube of the subsequent heat exchanger is evaporated. Since it causes high temperature corrosion of various equipment materials, it has been disposed of as waste not suitable for combustion. In addition, in recent years, when incineration of this chlorine compound-containing waste, harmful dioxin other than the above is generated, which has attracted attention, further obstructing incineration, and development of an appropriate treatment method is awaited. .

An example of a conventional incineration plant is shown in FIG. In the incineration plant shown in FIG. 3, the waste stored in the waste pit 101 is put into the incinerator 103 by the crane 102 and burned. Combustion ash is ash pit 104
Temporarily store it in the land and dispose of it in landfills.

The heat generated by the combustion is recovered by the boiler 105. The combustion flue gas is removed by a dust collector 106 after removing fly ash, oxides, etc., and dioxins generated by burning waste containing chlorine compounds such as vinyl chloride are collected by the dust collector 1.
It cannot be completely removed with 06.

[0005]

On combustion of the chlorine compounds containing waste in a conventional incineration plant [0005] By chlorine burns HCl, FeCl ₃ or the like occurs, such as a boiler is the gas caused It was causing high temperature corrosion. Therefore, the temperature inside the furnace cannot be raised above a certain temperature,
The high temperature did not completely burn the waste. Therefore,
There was a problem that harmful substances such as dioxins were generated because they could not be completely burned. In addition, the resin contained in the waste is fused to the inner wall of the pyrolysis furnace, and the resins are fused to each other, so that stable pyrolysis treatment cannot be performed.

In order to solve the above problems, the present invention is designed to suppress the generation of HCl, FeCl _3, etc., which causes high temperature corrosion, when chlorine-containing waste is burned, so that chlorine contained in the waste can be suppressed. Not only efficiently removes the chlorine, but also efficiently burns the combustibles after chlorine removal to suppress the generation of harmful substances such as dioxins, and the resin contained in the waste is fused to the inner wall of the pyrolysis furnace. It is an object to provide a waste treatment method that reduces waste.

[0007]

In order to solve the above-mentioned problems in the method of burning waste containing chlorine compounds, the present invention is directed to a dechlorination decomposition step for removing chlorine from waste, and a dechlorination step thereof. A waste treatment method consisting of a combustible component combustion process in which the waste after dechlorination is completely combusted in the chlorine decomposition process is adopted.

[0008] According to this treatment method, for wastes containing chlorine compounds such as vinyl chloride, such as municipal waste and industrial wastes, first, the chlorine compound-containing wastes are thermally decomposed into vinyl chloride. As a pretreatment that takes advantage of the characteristics that occur at each stage, by adjusting the thermal decomposition temperature, gasification of combustibles in vinyl chloride is suppressed and only chlorine is decomposed and removed.

Chlorine is a major cause of high temperature corrosion, HCl.
Etc., and by removing chlorine in advance, it is possible to suppress the generation of HCl, FeCl _3, etc. during combustion. Further, by removing chlorine, the cause of high temperature corrosion is eliminated and the next high temperature treatment becomes possible.

Next, the residue produced by this dechlorination treatment is preferably treated in a high temperature combustion field using oxygen-enriched air to combust combustible substances completely, and dioxins generated due to chlorine content are generated. Suppress. Since the HCl concentration is suppressed by this treatment method, the high temperature and high pressure steam can be recovered by the heat recovery boiler. When burning the waste after the dechlorination treatment, it may be burnt together with other waste containing no chlorine.

In the waste treatment method according to the present invention, the combustible component burning step of burning the waste after dechlorination is performed in a state where the oxygen concentration is increased by using, for example, oxygen-enriched air, whereby the combustion is performed at a high temperature. The combustion / melting process can be performed to obtain incombustibles (ash, etc.) as molten slag. By this step, the incombustible content can be recovered as molten slag, and the volume can be reduced and the slag can be treated in a stable state in which heavy metals are not eluted.

Further, it is possible to add a step of coarsely crushing the molten slag generated by the above-mentioned combustion / melting step, classifying slag having a constant particle size, and returning the classified slag to the dechlorination decomposition step. . By adding the slag having the adjusted particle size to the waste in the dechlorination decomposition step, it is possible to prevent the fusion of the resin to the inner wall of the pyrolysis furnace and the fusion of the resins.

Furthermore, in the waste treatment method according to the present invention, a re-combustion step for introducing the exhaust gas of the above-mentioned combustion / melting step and an exhaust gas cleaning step for introducing the exhaust gas of the dechlorination decomposition step are added. The exhaust gas discharged from the cleaning step may be burnt in the reburning step together with the exhaust gas of the burning / melting step.

According to this, unburned gas components (CO, HC, etc.) which may be slightly contained in the exhaust gas after cleaning the exhaust gas in the dechlorination decomposition process and the exhaust gas discharged from the combustion / melting process. Can be completely burned in the reburning step.

In the waste treatment method according to the present invention described above, the furnace temperature in the dechlorination decomposition step is 250 to 50.
0 ° C., and the air ratio in the combustion / melting process is 0.8 to
Oxygen was supplied so as to be 0.95, and the temperature inside the furnace was set to 1
It is preferable to burn at 350 to 1700 ° C.

The thermal decomposition characteristics of various plastics are shown in FIG. FIG. 2 shows the relationship between the temperature and the weight reduction of the processed product while increasing the temperature at 300 ° C./h. From this figure, the general decomposition temperature of plastic is 350 to 500 ° C., but vinyl chloride decomposes in two stages, and the dechlorination decomposition in the first step in the treatment method of the present invention is 250 to 35 ° C.
It can be seen that at 0 ° C, it occurs prior to the decomposition of other resins.
In the treatment method of the present invention, the property of pyrolysis of vinyl chloride is applied to achieve pollution-free combustion.

As described above, FIG. 2 shows "30 per hour.
The results of the "experiment conducted while raising the temperature at 0 ° C" are shown, and show the weight change of vinyl chloride when the temperature is increased with time. However, in actual decomposition, the decomposition is not performed while raising the temperature, and it is usual to carry out the processing while maintaining the "ambient temperature in the furnace" at a constant temperature.

Even in the dechlorination decomposition step at this time, although vinyl chloride decomposes in two steps, it is not carried out as in the experiment shown in FIG. 2 due to different temperature conditions, and as described above, it is 250 to 500 ° C. It is necessary to disassemble while adjusting the time within the range. When the temperature is as low as 250 ° C., it is necessary to extend the time, and when the temperature is as high as 500 ° C., it is necessary to shorten the time to decompose vinyl chloride.

Further, the combustion used in the treatment method of the present invention
If the oxygen concentration is excessive during the melting process, the temperature will increase to 13
Due to the high temperature of 50 to 1700 ° C., the generation of thermal NO _x may become significant, so it is necessary to adjust the oxygen concentration as well. Therefore, as described above, the air ratio in the combustion / melting process is set to 0.8 to 0.95 to prevent excess oxygen and suppress generation of thermal NO _x .

[0020]

EXAMPLE An embodiment of the method for treating waste according to the present invention will be specifically described below with reference to FIG. FIG. 1 shows an example of equipment for carrying out the treatment method according to the present invention. In the figure, 1 is a rotary kiln type dechlorination furnace for vinyl chloride-containing waste, and 2 is a pyrolysis exhaust gas cleaning apparatus (HCl recovery apparatus). ) 3 is a rotary kiln type main combustion / melting furnace, 4 is a re-combustion chamber, and 5 is a heat recovery boiler.

Reference numeral 6 is a pyrolysis cleaning exhaust gas, and 7 is an oxygen-enriched air for combustion of the decomposition gas and waste oil. Reference numeral 8 is a molten slag recovery device, and 9 is a heat source recovery heat exchanger for thermal decomposition. 10
Is a heating air for thermal decomposition, and 11 is a heating source when the heating air for thermal decomposition 10 is not applied, and is circulating exhaust gas. Reference numeral 12 represents a molten slag classifying device.

Numerals 21 to 25 are objects to be treated, 21 is municipal solid waste or industrial waste, 22 is a flow when there is no separate collection process, and 23 and 24 are cases where separate collection is provided, respectively. A vinyl chloride-containing combustible substance and other combustible substances are shown, and 25 is waste oil. Further, 26 is an oxygen supply facility, and 27 is a molten slag sand 23 for preventing fusion during the thermal decomposition of a vinyl chloride-containing combustible material (so-called "plalich trash").

Next, an embodiment of the processing method according to the present invention using the above equipment will be described according to the flow. 21 such as municipal waste and industrial waste, which are the objects to be treated, may or may not go through the separate collection or separation process,
If there is a separation step, it is vinyl chloride-containing waste,
Generally, the so-called plastic rich waste 23, other combustible materials 24, large incombustible materials 31, etc. are classified.

Therefore, this vinyl chloride-containing waste 23
In a rotary kiln type dechlorination cracking furnace 1, a dechlorination reaction, which is a first-stage thermal decomposition of vinyl chloride, is performed. As the reaction conditions, the thermal decomposition temperature, the reaction time, and the mixed state in the rotary kiln are involved. However, when the present invention is carried out at the thermal decomposition temperature: 250 to 500 ° C., the chlorine content is substantially contained in the thermal decomposition residue 28. However, it has been found that there is almost no such problem and that the decomposition loss of combustible components is minimized.

Further, at this time, in order to prevent fusion between the inner wall of the kiln and the resin, the waste slag 2 produced by burning the wastes 24 and 28 in the main combustion / melting furnace 3 in the subsequent stage 2
It was also found that it is effective to crush No. 9 and add sandy slag whose particle size is adjusted by the slag classifier 12.

In this equipment, in order to obtain the sandy slag to be supplied to the dechlorination cracking furnace 1, as an example, by supplying cooling water to the outlet portion of the rotary kiln type main combustion / melting furnace 3, the high temperature molten slag is generated. It employs a means of rapid cooling and crushing into particles. Instead of this quenching means, after gradually cooling to a lump,
This may be crushed and only a predetermined amount of sandy slag may be taken out from this.

On the other hand, with respect to the waste 22 that does not pass through the separation step, the waste is also dried in this thermal decomposition (dechlorination) step, and the heat amount required here increases, but the water content in the waste heats up. It has been found that the properties of the waste (particularly the calorific value) of the waste introduced into the main combustion / melting furnace 3 are improved and the thermal efficiency is improved because it is removed (dehumidified) by the decomposed exhaust gas cleaning device 2. In addition, since the pyrolysis cleaning exhaust gas 6 may contain a small amount of unburned gas components (CO, HC, etc.), it is supplied to the re-combustion chamber 4 to achieve complete combustion.

Next, the main combustion / melting furnace 3 adopts the rotary kiln system which has less restriction on the shape and size of the inlet of the object to be treated as compared with other furnace types, and the pyrolysis (dechlorination) residue 2
8 is incinerated together with other combustibles 24 to reduce the volume.
In the rotary kiln type main combustion / melting furnace 3 for main combustion, depending on the properties of the incineration material to be supplied, active combustion or suppression combustion (gasification combustion) method is adopted, and finally, main combustion High-temperature combustion is performed with the oxygen-enriched air 7 blown into the inlet portion, the intermediate portion, or the outlet portion of the melting furnace 3.

In the main combustion / melting furnace 3, ash, which is an incombustible material, is melted by radiant heat due to high temperature combustion, and is discharged to the molten slag recovery device 8 as a molten slag 29. In addition,
At this time, the present inventors conducted various experiments to set the air ratio (excess air ratio) of the combustion field to 0.8 to 0.95 (reducing atmosphere),
It was confirmed that NO _x reduction and stable melting can be achieved by controlling the combustion temperature to 1350 to 1700 ° C. (the optimum condition varies depending on the ash component).

On the other hand, the combustion exhaust gas from the main combustion / melting furnace 3 is
Since it is completely combusted with the combustion air 30 in the re-combustion chamber 4 and the exhaust gas does not contain Cl content, high temperature corrosion of the tube of the heat recovery boiler 5 can be prevented, and high temperature / high pressure steam (for example, about 500). It was also found that it is possible to obtain superheated steam (° C x 100ata). Further, it was also found that the dechlorination pretreatment of the waste and the high temperature combustion hardly generate dioxins, which is a problem when incinerating the chlorine-containing waste such as vinyl chloride.

The embodiments of the present invention have been specifically described above with reference to the drawings. However, the present invention is not limited to these examples, and a specific method thereof within the scope of the present invention shown in the claims. It goes without saying that various changes may be added to the.

For example, in the above example, a rotary kiln type is adopted as the dechlorination decomposition furnace 1 and the main combustion / melting furnace 3, but the dechlorination decomposition step and the combustion / melting step in the present invention are of this type. The present invention is not limited to the furnace, and may be performed by various other types of furnaces.

[0033]

As described above, in the waste treatment method according to the present invention, the dechlorination decomposition step for removing chlorine from the waste, and the combustible content combustion step for completely burning the waste after dechlorination, Alternatively, by providing a waste treatment method comprising a combustion / melting step of burning the dechlorinated waste at a high temperature and melting the incombustible generated by the combustion,
Pollution-free and stabilizing treatment of chlorine-containing waste such as vinyl chloride can be performed.

Therefore, according to the treatment method of the present invention, the chlorine content which is a high temperature corrosion source of the boiler tube and the like can be removed, high temperature and high pressure steam can be recovered, and harmful substances such as dioxins are not generated. Further, the ash content is made stable and harmless by the slag formation, and the pollution-free and stabilization treatment that enables highly efficient heat recovery becomes possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a waste treatment facility for carrying out a treatment method according to the present invention.

FIG. 2 is a diagram showing the thermal decomposition characteristics of various types of reference plastics.

FIG. 3 is a configuration diagram showing a conventional waste incinerator.

[Explanation of symbols]

 1 Dechlorination decomposition furnace 2 Thermal decomposition exhaust gas cleaning device 3 Main combustion / melting furnace 4 Recombustion chamber 5 Heat recovery boiler 6 Thermal decomposition cleaning exhaust gas 7 Oxygen-enriched air 8 Molten slag recovery device 9 Heat exchanger for recovering heat source for thermal decomposition 12 Molten slag classifier 21 Municipal waste or industrial waste 23 Vinyl chloride-containing combustibles 24 Other combustibles 25 Waste oil 26 Oxygen supply equipment 27 Molten slag sand 28 Thermal decomposition residue 29 Molten slag 30 Combustion air

Claims (5)

[Claims] 1. A method of burning waste containing a chlorine compound, comprising a dechlorination decomposition step of removing chlorine from waste, and a combustible content combustion of completely burning the waste after dechlorination in the dechlorination decomposition step. A waste treatment method comprising the steps of: 2. A method for burning a waste containing a chlorine compound, comprising: a dechlorination decomposition step of removing chlorine from the waste; and burning and burning the waste after dechlorination in the dechlorination decomposition step. And a combustion / melting step for melting the incombustibles generated by 3. A method of burning a waste containing a chlorine compound, wherein the chlorine content is removed from the waste by a dechlorination decomposition step, and the waste after dechlorination in the dechlorination decomposition step is burned and generated by combustion. Combustion / melting step of melting the incombustible material, and a classification step of roughly crushing the molten slag generated in the combustion / melting step to classify slag having a constant particle size, and the slag after classification in the classification step is A waste treatment method characterized by returning to a dechlorination decomposition step. 4. A reburning step for guiding the exhaust gas of the combustion / melting step and an exhaust gas cleaning step for guiding the exhaust gas of the dechlorination decomposition step are provided, and the exhaust gas treated in the exhaust gas cleaning step is reburned. The method for treating waste according to claim 2 or 3, characterized in that it is combusted with. 5. The furnace temperature in the dechlorination decomposition step is 250.
To 500 ° C., and oxygen is supplied to the combustion / melting step so that the air ratio becomes 0.8 to 0.95, and the temperature in the furnace is burned at 1350 to 1700 ° C. The method for treating waste according to any one of 2 to 4.