JP3894724B2 - Decomposition method of rubber and plastic waste - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for decomposing rubber / plastic waste, and more particularly, to a method for thermally decomposing rubber / plastic waste to produce and recover a wax-like substance.
[0002]
[Prior art]
Various types of rubber and plastic materials, especially polyolefins such as cross-linked polyethylene, are widely used as coating materials for electric wires and cables, and these rubber and plastic materials are used at the time of manufacture and after use. Generated in large quantities as waste.
[0003]
Conventionally, this type of waste treatment has been mainly landfill, but in recent years, methods have been developed to produce wax-like substances and hydrocarbon oils by thermally decomposing rubber and plastic wastes, thereby reusing resources. In addition, it attracts attention because it is less likely to cause environmental pollution. In particular, the method of self-combusting rubber and plastic waste, decomposing rubber and plastic with the heat of combustion to lower the molecular weight, and producing waxy substances useful for fuel, pigments, casting, etc. is discarded. Since heat energy obtained by burning an object itself is used, the processing cost can be reduced, and it is expected as a processing technique for a large amount of electric wire / cable coating material.
[0004]
FIG. 2 shows an example of an apparatus used in such a processing technique. A combustion chamber 2 for burning rubber / plastic waste 1 and a wax-like structure integrally provided at the bottom opening thereof are shown. And a reservoir tank 4 for receiving the melt 3 of the substance. Inside the combustion chamber 2, a net-like raw material receiver 5 for receiving the raw rubber / plastic waste 1 is provided so as to close the bottom opening of the combustion chamber 2. Is provided with a discharge port 4a for discharging the wax-like substance melt 3.
[0005]
In such an apparatus, when a rubber / plastic waste 4 such as polyolefin is put into the combustion chamber 2 and ignited and self-combusted, the rubber / plastic waste 1 is eventually thermally decomposed by the heat of combustion and becomes waxy. A substance melt 3 falls from the mesh of the raw material receptacle 5 and accumulates in the reservoir tank 4.
[0006]
However, in such a conventional method, since the melt 3 of the wax-like substance that has fallen into the receiving tank 4 is in a high temperature state, a part thereof is vaporized, and this reacts with oxygen in the receiving tank 4 and burns. As a result, there is a problem that the yield of the wax-like substance is lowered.
[0007]
[Problems to be solved by the invention]
As described above, there is a problem that the yield of the wax-like substance is lowered because part of the melt of the wax-like substance that has fallen into the receiving tank is vaporized and burned.
[0008]
The present invention has been made to solve such a problem, and in a method for producing a wax-like substance by self-combustion of rubber / plastic waste, combustion of a melt of the wax-like substance dropped in a receiving tank. It is an object of the present invention to provide a method for decomposing a rubber / plastic waste that can prevent the above-described problem and improve the yield.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the method for decomposing rubber / plastic waste according to claim 1 of the present application is to heat the remainder by putting rubber / plastic waste into a combustion chamber and burning a part thereof. In the method for decomposing rubber and plastic waste, the wax-like material melt is decomposed to produce a wax-like material melt, and the wax-like material melt is dropped and collected in a reservoir tank attached to the bottom of the combustion chamber. By introducing an inert gas into the reservoir tank, the treatment is performed while blocking oxygen from entering the reservoir tank from the combustion chamber.
[0010]
In the method of the above configuration, by introducing an inert gas into the receiving tank, contact between the wax-like substance melt and oxygen in the receiving tank is cut off, so that the combustion of the wax-like substance melt is suppressed. And a decrease in yield due to combustion can be suppressed.
[0011]
According to a second aspect of the present invention, there is provided a method for decomposing a rubber / plastic waste, wherein an air inlet is provided in a lower side wall of the combustion chamber and the air is introduced from the air inlet.
[0012]
With this configuration, oxygen can be supplied to the lower portion of the combustion chamber, where the amount of oxygen tends to be insufficient, and combustion failure due to lack of oxygen can be prevented. As a result, generation of combustion residues and non-uniform heating are suppressed, and it is possible to reduce the yield reduction caused by them.
[0013]
According to a third aspect of the present invention, there is provided a method for decomposing a rubber / plastic waste, wherein the internal temperature of the combustion chamber is controlled to a predetermined temperature by adjusting an amount of oxygen introduced into the combustion chamber. It is characterized by.
[0014]
With this configuration, it becomes possible to thermally decompose the rubber / plastic waste uniformly, and it is possible to improve the yield of the wax-like substance and stabilize the quality.
[0015]
In the method for decomposing a rubber / plastic waste according to the present invention, examples of the rubber / plastic waste include those mainly containing a crosslinked polyolefin as described in claim 4.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
That is, FIG. 1 is a sectional view schematically showing an example of a rubber / plastic waste treatment apparatus used in the present invention.
[0018]
In FIG. 1, reference numeral 10 denotes a combustion chamber for self-combusting the rubber / plastic waste 20, and this combustion chamber 10 is supported and fixed by four support legs 11. The bottom of the combustion chamber 10 is open, and a receiving tank 12 for receiving a wax-like melt 30 is integrally provided in the bottom opening 10a. At the bottom of the reservoir tank 12, there is provided a discharge port 12 a having an open / close valve 13 for discharging the melted wax-like substance 30.
[0019]
Although not shown in the figure, an openable and closable raw material input port for supplying raw material rubber / plastic waste 20 is provided in the upper part of the combustion chamber 10, while the raw material input port is provided inside. A net-like raw material receiver 14 for receiving the raw material supplied is provided so as to close the bottom opening 10a.
[0020]
Further, a temperature sensor 15 such as a thermocouple for detecting the combustion temperature of the rubber / plastic waste 20 is installed in the combustion chamber 10, and air is introduced into the combustion chamber 10 on the lower side wall of the combustion chamber 10. For this purpose, an air inlet 10b is provided. An air introduction amount control means for adjusting the introduction amount of air so that the combustion temperature of the rubber / plastic waste 20 is maintained at a predetermined temperature based on a signal from the temperature sensor 15. 40 is connected.
[0021]
On the other hand, an inert gas introduction port 12b for introducing an inert gas is opened on the side wall of the reservoir tank 12, and an inert gas supply device 50 is connected to the inert gas introduction port 12b. ing.
[0022]
The air introduction port 10b prevents the occurrence of defective combustion of rubber / plastic waste due to insufficient oxygen in the lower portion of the combustion chamber 10 by introducing the inert gas into the receiving tank 12, and It is provided for adjusting the oxygen concentration in the combustion chamber 10 so that the combustion temperature of the rubber / plastic waste 20 is maintained at a predetermined temperature. Therefore, if the combustion temperature can be maintained at the predetermined temperature. In addition, an opening for introducing air into the combustion chamber 10 may be provided in addition, and an air introduction amount control means 40 connected to the temperature sensor 15 is provided in such other opening. Further, a function of maintaining the combustion temperature of the rubber / plastic waste 20 at a predetermined temperature may be provided.
[0023]
Next, a method for producing a wax-like substance from rubber / plastic waste using the above apparatus will be described.
[0024]
First, rubber / plastic waste 20 collected from electric wire / cable waste or the like is put into the combustion chamber 10 from the raw material inlet. Next, the rubber / plastic waste 20 is ignited and an inert gas is introduced into the reservoir tank 12 from the inert gas inlet 12 b by the inert gas supply device 50. After the ignition, the combustion progresses with time, and the heat of combustion causes the rubber / plastic waste 20 that has not yet been combusted to be thermally decomposed and reduced in molecular weight. Air is introduced from the air inlet 10b so as to be maintained at a predetermined temperature. The combustion temperature of the retained rubber / plastic waste 20 is preferably about 350 to 450 ° C., for example, when the rubber / plastic waste 20 mainly contains a crosslinked polyolefin. By maintaining in such a temperature range, the rubber / plastic waste 20 is efficiently thermally decomposed into a wax-like substance, and the wax-like substance in a molten state due to the high temperature falls from the mesh of the raw material receiver 14 and becomes unreacted. It collects in the receiving tank 12 into which the active gas is introduced.
[0025]
An inert gas is introduced into the reservoir tank 12, and the retained wax-like substance 30 is in a molten state at a high temperature, but burns because contact with oxygen is cut off by the inert gas. There is nothing.
[0026]
In such a method, since the burning of the wax-like substance in the receiving tank 12 is prevented, the yield is improved.
[0027]
Further, since air is introduced from the air inlet 10b provided in the lower side wall of the combustion chamber 10, oxygen can be supplied to the lower portion of the combustion chamber 10 where the amount of oxygen tends to be insufficient due to diffusion of the inert gas. In addition, poor combustion of the rubber / plastic waste 20 can be prevented. Such poor combustion also causes a decrease in the yield of the wax-like substance.
[0028]
The inert gas introduced into the reservoir tank 12 includes nitrogen gas, argon gas, helium gas, and the like. Among them, the argon gas is heavier than air and is easily retained in the reservoir tank 12. .
[0029]
【Example】
Next, although the Example of this invention is described, this invention is not limited to this Example.
[0030]
Example 1
Using the processing apparatus shown in FIG. 1, 5 kg of a crosslinked polyethylene (gel fraction 80%) insulation coating peeled off from a 6 kV crosslinked polyethylene insulated cable was cut into an appropriate length and put into the combustion chamber 10. Next, this was ignited and argon gas was introduced into the receiving tank 12. And it was made to burn, adjusting the air introduction amount from the air inlet 10b so that combustion temperature may hold about 400 degreeC. As a result, it was possible to recover the waxy substance with a yield of about 80%.
[0031]
Example 2
Cross-linked polyethylene (gel fraction 80%) insulation coating stripped from 6kV cross-linked polyethylene insulated cable in the same manner as in Example 1 except that the amount of air introduced was adjusted and the combustion temperature was kept at about 200 ° C. Was decomposed. As a result, the wax-like substance could be recovered with a yield of about 60%.
[0032]
Comparative Example 1
In the same manner as in Example 1 except that argon gas was not introduced, the decomposition treatment of the crosslinked polyethylene (gel fraction 80%) insulation coating peeled off from the 6 kV crosslinked polyethylene insulated cable was performed. The recovery rate of the wax-like substance by this treatment was 30%, and a considerable amount of carbon particles was found in the recovered wax-like substance.
[0033]
Comparative Example 2
Except for not introducing argon gas, in the same manner as in Example 2, decomposition treatment of the insulation coating of the crosslinked polyethylene (gel fraction 80%) peeled off from the 6 kV crosslinked polyethylene insulated cable was performed. The recovery rate of the wax-like substance by this treatment was 10%, and a considerable amount of carbon particles was mixed in the recovered wax-like substance.
[0034]
【The invention's effect】
As described above, according to the present invention, since the inert gas is introduced into the receiving tank for receiving the melt of the wax-like substance, the wax-like substance melt in the receiving tank is used. Combustion can be suppressed, and a decrease in yield due to combustion can be suppressed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing an example of a rubber / plastic waste treatment apparatus used in the present invention.
FIG. 2 is a cross-sectional view schematically showing an example of a conventional rubber / plastic waste processing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Combustion chamber 10a ... Bottom opening 10b ... Air inlet 12 ... Reservoir tank 12b ... Inert gas inlet 14 ... Raw material receiver 15 ... Temperature sensor 20 ... Rubber and plastic waste 30 ... ... Wax-like substance melt 40 ... Air introduction amount control means 50 ... Inert gas supply device

Claims (4)

By putting rubber / plastic waste into the combustion chamber and burning a part of it, the remainder is pyrolyzed to produce a waxy substance melt, and this waxy substance melt is attached to the bottom of the combustion chamber. In the method of disassembling rubber and plastic waste that is dropped and collected in a receiving tank,
A method for decomposing rubber / plastic waste, wherein an inert gas is introduced into the reservoir tank to prevent oxygen from entering the reservoir tank from the combustion chamber. 2. The rubber / plastic waste decomposition method according to claim 1, wherein an air inlet is provided in a lower side wall of the combustion chamber, and the treatment is performed while introducing air from the air inlet. 3. The rubber / plastic waste decomposition method according to claim 1, wherein the internal temperature of the combustion chamber is controlled to a predetermined temperature by adjusting an amount of oxygen introduced into the combustion chamber. The method for decomposing a rubber / plastic waste according to any one of claims 1 to 3, wherein the rubber / plastic waste mainly contains a crosslinked polyolefin.

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