JP2011137079A - Thermal decomposition apparatus for polymer-based waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal decomposition apparatus for polymer-based waste, which promotes thermal decomposition reaction of polymer-based waste, suppresses graphitization of carbonized material left thereafter and inhibits oxidation of the carbonized material. <P>SOLUTION: The thermal decomposition apparatus of polymer-based waste includes a heat exchanger 1 for heating an oxygen-free gas, a thermal decomposition treatment apparatus 4 having a thermal decomposition furnace 3 that has an outlet for discharging a pyrolysis gas and an inlet for introducing an oxygen-free gas and stores the polymer-based waste 2 inside, an oil recovery apparatus 5 that cools the pyrolysis gas generated in the thermal decomposition treatment apparatus 4 and recovers a condensed oil, a circulation path 6 that supplies a residual gas as an anoxic gas after recovery of the oil by the oil recovery apparatus 5 to the heat exchanger 1. The inlet for introducing the oxygen-free gas has an oxygen-free gas introduction pipe 7 that is projected from the inner wall of the thermal decomposition furnace to a space in the furnace. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thermal decomposition apparatus for polymer waste, and in particular, polymer waste capable of suppressing graphitization of carbide remaining after thermal decomposition of polymer waste and suppressing oxidation of the carbide. The present invention relates to a thermal decomposition apparatus.

  Conventionally, various polymer materials such as rubber materials and resin materials have been industrialized for the purpose of developing functional materials. On the other hand, the development of the polymer industry has led to mass production of general-purpose materials, mass production of general-purpose materials. Consuming and the disposal of polymer waste has become an important issue to be solved immediately. In order to solve this problem, technological progress such as reuse and recycling of polymer materials is essential. For example, tires made of rubber materials have been mass-produced and consumed in large quantities as automobile essential parts along with the development of motorization, and the number of used tires has become enormous. In particular, the recovery of useful materials has become a major issue.

  In Japanese Patent Application Laid-Open No. 2004-277687 (Patent Document 1), a carbide obtained by subjecting a waste tire to carbonization is finely pulverized, and this is heated to 500 ° C. or higher in a sealed container to be crystallized. It is reported that it can be recycled as an additive. However, it is well known that carbide is graphitized by high-temperature treatment, and the electron microscopic image described in Patent Document 1 can be judged to be a graphitized fine powder instead of carbon black. The surface of such graphitized carbide has been modified by oxidation by heat treatment, and when this is used as a rubber reinforcing agent, the reinforcing effect on the rubber component is greatly reduced compared to carbon black. This is well known to those skilled in the art.

  Japanese Patent Application Laid-Open No. 2006-349224 (Patent Document 2) reports that a waste tire is preheated by microwave irradiation, is thermally decomposed in a kiln-type heating furnace, and the resulting carbide can be used as activated carbon. ing. However, there is no description that the carbide can be used as a compounding agent for rubber. Further, from the structure of the heating furnace described in Patent Document 2, air flows relatively easily into the heating furnace, and the degree of oxidation of the resulting carbide. It is thought that this carbide can be used as a raw material for activated carbon because it becomes large and has a porous structure, but it is considered that there is almost no reinforcement to the rubber component.

  Japanese Patent Application Laid-Open No. 2007-70167 (Patent Document 3) reports that glassy carbon can be obtained by heating a waste tire at 500 to 560 ° C. for 2 to 3 hours in a rotary dry distillation furnace. However, the glassy carbon is not suitable as a compound for reinforcing rubber.

  In WO 2007/121166 (patent document 4), the tire is pyrolyzed at 350 ° F. (177 ° C.) to 850 ° F. (566 ° C.) for the purpose of recycling carbon black from the used tire, and then obtained. And a device for removing volatiles by heating at 900 ° F. (482 ° C.) to 1200 ° F. (648 ° C.) when the generated carbide is raised through a pipe into which air is introduced by a screw. Is disclosed. However, since air is introduced into the tube and the heating temperature is high, carbon black may be recovered as oxidized carbide on the surface, and this carbide is also considered unsuitable as a rubber reinforcing compounding agent. .

  As described above, the surface-oxidized carbide or graphitized carbide that has undergone excessive heat treatment, and carbon black produced by pyrolysis or incomplete combustion reaction of heavy oil in a reactor at high temperature However, there is a significant difference in the interaction with the rubber composition when the above carbide is compounded in the rubber composition, only that the main components are composed of carbon. It is widely known that the carbide is not suitable as a rubber compounding agent because the tensile stress and mechanical strength are remarkably reduced, and this is a major factor that hinders the use of carbide as a filler in rubber. It has become.

  Also, when carbon black, which can improve the performance of the rubber composition at the time of rubber compounding, is subjected to a long and long thermal history, graphitization proceeds and at the same time the generation of oxygen-containing groups on the carbon black surface Therefore, it is widely known to those skilled in the art that when carbon black subjected to such a treatment is blended with a rubber composition, the tensile stress and mechanical strength are significantly reduced as well.

  On the other hand, in US Pat. No. 5,037,628 (Patent Document 5), a method in which carbide obtained by pyrolyzing scrap rubber is pulverized under mild pulverization conditions, and agglomerated particles containing carbon black are separated using an air classifier. Has been reported. Here, the compatibility of the separated carbide as a reinforcing filler to the rubber material is greatly influenced by the thermal decomposition conditions. However, Patent Document 5 describes the decomposition conditions at the time of thermal decomposition. There is absolutely no judgment as to whether or not it is suitable as a rubber-reinforcing compounding agent.

  Recently, as an oiling facility for recovering components that can be used as useful substances from polymer waste, a heat exchanger for heating oxygen-free gas, a pyrolysis furnace containing polymer waste inside, A pyrolysis apparatus having an external heating means for heating the pyrolysis furnace from the outside, an oil content recovery apparatus for recovering condensed oil by cooling the pyrolysis gas generated in the pyrolysis apparatus, and the oil recovery There has been reported a circulation type oil making facility provided with a circulation path for circulating the residual gas after the oil is recovered by an apparatus as an oxygen-free gas to the heat exchanger (Japanese Patent Laid-Open No. 2008-285523). (See Patent Document 6). However, from the viewpoint of recovering the carbide after pyrolysis as a suitable compounding agent for rubber, the pyrolysis conditions, for example, conditions for shortening the pyrolysis reaction time, shortening the contact time with the hot gas or the reaction gas, etc. No attempt has been made to optimize.

Moreover, in JP-A-7-233374 (Patent Document 7), the waste plastic melt in the thermal decomposition tank protrudes into the melt in the thermal decomposition tank for direct contact with the heated inert gas. A desalination apparatus comprising a blowing tube is disclosed.
The invention described in Patent Document 7 relates to collective processing of plastic waste containing chlorine-containing polymers such as polyvinyl chloride, and more particularly to a dehydrochlorination apparatus for waste plastic melt, specifically, A pyrolysis device that melts and decomposes waste plastic by blowing heat medium gas, and a heated inert gas as a heat medium gas is blown into the waste plastic melt, and hydrogen chloride gas generated by the thermal decomposition of waste plastic is extracted from the melt. Inert gas blowing device to be released, cooling device for cooling inert gas containing hydrogen chloride, absorption device for desalinating the cooled hydrogen chloride-containing inert gas with an absorbent, and desalted inert material A waste plus characterized by comprising a heating device for heating the gas and a circulation device for sending the heated inert gas to the inert gas blowing device Tsu desalination apparatus is disclosed in click melt.
That is, in the technique described in Patent Document 7, the heat medium gas introduced into the pyrolysis reactor is injected into plastic waste containing a chlorine-containing polymer such as polyvinyl chloride melted in a liquid state, The target is completely different from polymer waste such as solid waste tires. Moreover, in the said patent document 7, there is no description regarding the carbide | carbonized_material which will remain | survive in an apparatus at the time of completion | finish of thermal decomposition, Furthermore, the suggestion of utilizing this carbide | carbonized_material as a useful collection | recovery is not described at all.

JP 2004-277687 A JP 2006-349224 A JP 2007-70167 A International Publication No. 2007/121166 US Pat. No. 5,037,628 JP 2008-285523 A JP-A-7-233374

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, suppress the graphitization of the carbide remaining after the thermal decomposition of the polymer waste, and suppress the oxidation of the carbide. It is in providing a thermal decomposition apparatus. By using the polymer waste thermal decomposition apparatus of the present invention, the quality of the carbide is not deteriorated because it is not subjected to graphitization or oxidation treatment at the time of thermal decomposition. Thus, it is possible to obtain a carbide capable of exhibiting sufficient interaction with the carbon black and exhibiting sufficient performance as a substitute for carbon black for reinforcing rubber.

  “Carbide” in the present application refers to a solid that is produced and left after a substance containing an organic substance is used as a raw material, and the raw material is released from a gas body and a liquid component by a thermal decomposition reaction by heating. It may contain an inorganic substance.

  As a result of intensive studies to achieve the above object, the present inventors have inserted an introduction pipe for introducing oxygen-free gas into a pyrolysis furnace space in which polymer waste is heated and thermally decomposed. , By projecting the introduction pipe into the pyrolysis furnace, the contact efficiency between the polymer waste and the oxygen-free gas can be significantly increased, thereby increasing the decomposition rate of the polymer waste. In order to suppress graphitization due to excessive thermal history and further reduce the chance of contact with oxygen during the thermal decomposition reaction, the present inventors have found that the properties of the generated carbide can be greatly improved, and the present invention It came to complete.

That is, the thermal decomposition apparatus for polymer waste of the present invention is
A heat exchanger for heating anoxic gas;
It has a discharge port for discharging the pyrolysis gas and an introduction port for introducing oxygen-free gas, and has a pyrolysis furnace for containing the polymer waste inside, and the polymer waste in the heat exchanger A thermal decomposition treatment device for generating thermal decomposition gas by thermal decomposition by contacting with heated oxygen-free gas;
An oil content recovery device for recovering condensed oil by cooling the pyrolysis gas generated in the thermal decomposition processing device;
In the thermal decomposition apparatus for polymer waste, comprising a circulation path for supplying the residual gas after the oil is recovered by the oil recovery apparatus to the heat exchanger as an oxygen-free gas,
The introduction port for introducing the oxygen-free gas has an oxygen-free gas introduction pipe protruding from the inner wall of the pyrolysis furnace to the furnace space.

  In the polymer-based waste pyrolysis apparatus of the present invention, it is preferable that the opening surface of the oxygen-free gas introduction pipe is installed so as to face the inner wall surface of the pyrolysis furnace. More preferably, it is installed so as to face the bottom wall surface.

In the polymer waste pyrolysis apparatus of the present invention, the ratio (d ₂ / d ₁ ) between the inner diameter (d ₁ ) of the pyrolysis furnace and the inner diameter (d ₂ ) of the oxygen-free gas introduction pipe is 0.1 to It is preferably 0.25.

Further, the polymer waste pyrolysis apparatus of the present invention is a ratio between the inner diameter (d ₁ ) of the pyrolysis furnace and the distance (D) from the tip of the oxygen-free gas introduction pipe to the inner wall of the pyrolysis furnace. (D / d ₁₎ is preferably a 0.2 to 0.4.

  In a preferred example of the polymer waste pyrolysis apparatus of the present invention, the opening of the oxygen-free gas introduction pipe is formed in a shape that expands toward the downstream side in the oxygen-free gas flow direction.

  In another preferred embodiment of the thermal decomposition apparatus for polymer waste according to the present invention, one or a plurality of holes are formed in the side surface of the portion where the oxygen-free gas introduction pipe is inserted.

  According to the present invention, in a pyrolysis furnace for heating and pyrolyzing polymer waste, an introduction pipe for introducing oxygen-free gas is inserted into the pyrolysis furnace space, and the introduction pipe is connected to the pyrolysis furnace. By projecting inward, the contact efficiency between the polymer waste and the oxygen-free gas can be significantly increased, which makes it possible to greatly increase the decomposition rate of the polymer waste, In order to suppress graphitization due to thermal history and further reduce the chance of contact with oxygen during the thermal decomposition reaction, the properties of the produced carbide can be greatly improved. In addition, since the carbide obtained by the thermal decomposition apparatus does not exhibit a large performance deterioration when blended with rubber as compared with conventional carbon black, it is replaced with carbon black or a part thereof for filling with rubber reinforcement. It has a great advantage that it can be used as an agent.

It is the schematic of an example of the thermal decomposition apparatus of the polymeric waste of this invention. 1 is an enlarged partial cross-sectional view of a polymer-based waste thermal decomposition apparatus used in Example 1. FIG. It is an expanded partial sectional view of the other example of the thermal decomposition apparatus of the polymeric waste of this invention. It is an expanded partial sectional view of the thermal decomposition processing apparatus used in Comparative Example 1.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view of an example of a thermal decomposition apparatus for polymer waste according to the present invention. The pyrolysis apparatus shown in FIG. 1 has a heat exchanger 1 for heating oxygen-free gas, a discharge port for discharging pyrolysis gas, and an introduction port for introducing oxygen-free gas, and polymer waste inside Heat for generating pyrolysis gas by pyrolyzing by bringing the polymer waste 2 into contact with the oxygen-free gas heated by the heat exchanger 1. A decomposition treatment device 4, an oil recovery device 5 for cooling the pyrolysis gas generated in the thermal decomposition treatment device 4 to recover the condensed oil component, and a residual after the oil component is recovered by the oil recovery device 5 A pyrolysis apparatus for polymer waste comprising a circulation path 6 for supplying gas to the heat exchanger 1 as an oxygen-free gas, wherein an inlet for introducing the oxygen-free gas is a pyrolysis furnace Having an oxygen-free gas introduction pipe 7 projecting from the inner wall of the furnace into the furnace space And butterflies.

  In the thermal decomposition apparatus of the present invention, first, the oxygen-free gas is heated in the heat exchanger 1. By supplying the oxygen-free gas heated by the heat exchanger 1 to the pyrolysis furnace 3, the polymer waste 2 in the pyrolysis furnace 3 is pyrolyzed. Here, the oxygen-free gas is a gas body other than oxygen and oxide, and examples thereof include an inert gas such as nitrogen and argon, and a hydrocarbon gas such as methane and ethane. By using the oxygen-free gas, it is possible to prevent oxidation of the carbide remaining in the pyrolysis furnace 3 after pyrolysis of the polymer waste 2. In the thermal decomposition apparatus of the present invention, the configuration of the heat exchanger 1 is not particularly limited. For example, an oxygen-free gas introduced into a silicon carbide heating element or other heating element, or a polymer The oxygen-free gas is heated by heat exchange with the combustion heat of hydrocarbon fuel generated from the thermal decomposition of the system waste 2 or hydrocarbon fuel from another supply source. Further, in order to supply the oxygen-free gas to the heat exchanger 1, in addition to being sent from the non-circulating oxygen-free gas supply source 8, the residual gas after being recovered by the oil content recovery device 5 via the circulation path 6 to be described later (For example, hydrocarbon gas) may be circulated through the heat exchanger 1 as an oxygen-free gas.

In the thermal decomposition apparatus of the present invention, the thermal decomposition processing apparatus 4 has a discharge port for discharging the pyrolysis gas and an introduction port for introducing oxygen-free gas, and contains a polymer waste 2 inside. 3, an oxygen-free gas heated by a heat exchanger 1 is introduced into a pyrolysis furnace 3 containing the polymer waste 2, and the polymer waste 2 is brought into contact with the oxygen-free gas And generate pyrolysis gas. By contacting the polymer waste 2 with an oxygen-free gas, thermal decomposition in an oxygen-free state is possible. Here, since the thermal decomposition apparatus of the present invention includes the oxygen-free gas introduction pipe 7 inserted into the inlet of the thermal decomposition furnace 3 and the tip of the thermal decomposition apparatus protrudes from the inner wall of the thermal decomposition furnace into the furnace, the heat exchanger 1 The oxygen-free gas heated at is introduced into the pyrolysis furnace 3 through the oxygen-free gas introduction pipe 7. By providing the oxygen-free gas introduction pipe 7 so as to protrude into the pyrolysis furnace 3, the oxygen-free gas is introduced from the direction of the oxygen-free gas introduction pipe 7 (downward in FIG. 1), and the pyrolysis furnace 3 facing the oxygen gas introduction pipe 7. This changes the direction of flow by colliding with the inner wall of the bottom surface (changes sideways and upward in FIG. 1). A flow is generated, and the contact efficiency between the polymer waste 2 and the oxygen-free gas can be significantly increased. Thus, the generation of turbulent flow by the collision of the high temperature hot gas (heated oxygen-free gas) with the wall surface in the pyrolysis furnace 3 greatly promotes the pyrolysis reaction of the polymer waste 2. Contribute. From this viewpoint, in order to improve the contact efficiency between the polymer waste 2 and the oxygen-free gas and promote the thermal decomposition reaction of the polymer waste 2, the opening surface of the oxygen-free gas introduction pipe 7 is It is preferably installed so as to face the inner wall surface of the pyrolysis furnace, and more preferably installed so as to face the bottom wall surface of the pyrolysis furnace.
From the same point of view, the oxygen-free gas introduction pipe 7 is installed so that the oxygen-free gas can be introduced in a direction opposite or intersecting with the flow direction of the pyrolysis gas discharged from the discharge port of the pyrolysis furnace. It is also preferable to install an oxygen-free gas introduction pipe 7 (downward in FIG. 1) so that the oxygen-free gas can be introduced in a direction opposite to the flow direction of the pyrolysis gas (that is, the opposite direction). Is particularly preferred.

Further, the shape of the opening of the oxygen-free gas introduction pipe 7 is usually formed in a tubular shape, for example, a cylindrical shape, but is formed in a shape that widens toward the downstream side in the oxygen-free gas flow direction. You can also.
Further, the outer wall side surface of the oxygen-free gas introduction pipe 7 does not have to be subjected to any processing, but the polymer waste 2 that undergoes the pyrolysis reaction at the beginning of the pyrolysis reaction and the high-temperature hot gas (heated) In order to improve the contact efficiency with the oxygen-free gas), it is preferable to form one or a plurality of holes in the side surface of the portion of the oxygen-free gas introduction pipe 7 inserted into the pyrolysis furnace.

Furthermore, in the pyrolysis apparatus of the present invention, the ratio (d ₂ / d ₁ ) between the inner diameter (d ₁ ) of the pyrolysis furnace 3 and the inner diameter (d ₂ ) of the oxygen-free gas introduction pipe 7 is 0.1 to 0.25. It is preferable. The inner diameter (d ₂ ) refers to the inner diameter of the tip of the oxygen-free gas introduction pipe 7. When d ₂ / d ₁ is less than 0.1, since the inner diameter of the oxygen-free gas introduction pipe 7 is small, the flow rate of the heated oxygen-free gas in the pyrolysis furnace 3 becomes too large, and the apparatus together with the heated oxygen-free gas This is not preferable because there is a possibility of generating solid dust (fine suspended matter derived from polymer waste) circulating inside. On the other hand, if d ₂ / d ₁ exceeds 0.25, the oxygen-free gas introduction pipe 7 has an inner diameter that is too large relative to the inner diameter (d ₁ ) in the pyrolysis furnace 3. This is not preferable because the flow rate of the liquid is reduced, the contact efficiency between the polymer waste 2 and the oxygen-free gas is lowered, and the thermal decomposition rate may be lowered.
FIG. 3 shows an enlarged partial cross-sectional view of another example of the thermal decomposition apparatus for polymer waste according to the present invention. The opening of the oxygen-free gas introduction pipe 7 in FIG. A shape that widens toward the downstream side in the flow direction is formed, and a plurality of holes are formed in the side surface of the oxygen-free gas introduction pipe 7 inserted into the pyrolysis furnace. As described above, the aspect of the oxygen-free gas introduction pipe 7 is not limited to this.

Furthermore, in the pyrolysis apparatus of the present invention, the ratio (D / d) between the inner diameter (d ₁ ) of the pyrolysis furnace 3 and the distance (D) from the tip of the oxygen-free gas introduction pipe 7 to the inner wall of the pyrolysis furnace. ₁ ) is preferably 0.2 to 0.4. If D / d ₁ is less than 0.2, the distance between the tip of the oxygen-free gas introduction pipe 7 and the inner wall is too close, and turbulence may occur violently, and fine solid dust from the generated carbides may circulate in the pyrolysis unit. Is unfavorable because of the high. On the other hand, if D / d ₁ exceeds 0.4, the distance between the tip of the oxygen-free gas introduction pipe 7 and the inner wall is too far away, so that it only collides with the inner wall of the reactor and generates a turbulent flow effective for thermal decomposition. This is not preferable because the speed cannot be secured and the thermal decomposition rate is lowered. Here, the distance D indicates the shortest distance from the tip of the oxygen-free gas introduction pipe 7 to the inner wall of the pyrolysis furnace 3.

  The polymer waste 2 mainly refers to organic waste, specifically, rubber material waste such as tire waste (for example, spew, buff powder, 4-32 divided tires), Polymer materials obtained by (co) polymerization reaction of hydrocarbon monomers, such as polyethylene, polypropylene, styrene-butadiene copolymers, etc. Copolymers of hydrocarbon monomers with other monomers, such as ethylene-vinyl acetate (Co) polymers, (co) polymers of halogen derivatives of hydrocarbon monomers, for example, resin material waste such as polyvinyl chloride.

  Further, it is preferable that the pyrolysis apparatus 4 includes an external heating means 9 for heating the pyrolysis furnace 3 from the outside, in addition to the pyrolysis furnace 3 that accommodates the polymer waste 2 therein. Since the pyrolysis apparatus 4 includes the external heating means 9, the polymer waste 2 in the pyrolysis furnace 3 can be indirectly heated from the outside of the pyrolysis furnace 3. It is possible to reduce the flow rate, thereby further increasing the rate of thermal decomposition of the polymer waste 2 in the thermal decomposition furnace 3. As described above, the gas flow rate of the high-temperature oxygen-free gas introduced into the pyrolysis furnace 3 can be reduced, and the temperature of the gas body can also be reduced. Mixing and suppressing the generation of solid dust (fine suspended matter derived from polymer waste) that circulates in the device together with the gas (pyrolysis gas, oxygen-free gas, etc.), and also suppresses the generation of nitrogen oxides, etc. be able to. The external heating means 9 is not particularly limited. For example, a silicon carbide heating element disposed around the pyrolysis furnace 3 or another heating element may be used as the external heating means 9. Alternatively, a space S may be formed between the pyrolysis furnace 3 and an external wall disposed around the pyrolysis furnace 3, and a heat medium may be introduced into the space S. The heat medium that can be introduced into the space S is not limited to oxygen-free gas because the polymer waste 2 is indirectly heated from the outside of the pyrolysis furnace 3, and various media can be used. Can do. The introduction / exhaust port of the heat medium into the space S is not shown.

  In the pyrolysis apparatus of the present invention, in order to control the gas flow rate of the oxygen-free gas introduced into the pyrolysis furnace 3, the flow rate 10 for measuring the gas flow rate, and the gas flow rate is adjusted by the opening degree. The damper 11 for this, the air blower 12 etc. for keeping a gas flow rate constant can be installed. For example, as shown in FIG. 1, in order to supply oxygen-free gas from the oxygen-free gas supply source 8, a flow meter 10, a damper 11 and a pipe 11 connecting the oxygen-free gas supply source 8 and the heat exchanger 1 are connected. A blower 12 may be provided, and a flow meter 10, a damper 11, and a blower 12 are provided in a circulation path 6 for circulating the residual gas after being collected by the oil collecting device 5 as an oxygen-free gas to the heat exchanger 1. It may be provided.

  In the thermal decomposition apparatus of the present invention, the oil content recovery unit 5 uses one or more dry distillation towers 13 to cool the pyrolysis gas generated in the thermal decomposition processing unit 4 and recover the condensed oil content. Is preferred. As shown in FIG. 1, if a plurality of dry distillation towers 13 are used, the recovered oil can be separated from the pyrolysis gas generated in the pyrolysis processor 4 according to the boiling point. Specifically, the first dry distillation column 13a on the upstream side of the gas flow path has a pyrolysis gas supply port from the pyrolysis furnace 3 at a position in the middle of the height direction, and pyrolysis gas at the upper end. A cooler for cooling and condensing into oil (heavy oil) and a discharge port for sending pyrolysis gas to the dry distillation column 13b on the downstream side are provided. The second dry distillation tower 13b on the downstream side of the gas flow path has the same configuration as the first dry distillation tower 13a, but has a lower boiling point in the region than the boiling point of the oil component targeted by the first dry distillation tower 13a. The oil content (light oil) is collected. Thus, by installing the plurality of dry distillation towers 13, it is possible to recover an oil component having a constant composition and stable quality with a high recovery rate. In addition, each of the carbonization towers 13 is connected to the recovery tank 14 through a pipe, for example, at the lower part thereof, and can store the recovered oil. Furthermore, a condensing device or the like can be provided on the downstream side of the carbonization tower, and the oil component condensed in the condensing device can be recovered.

  In the thermal decomposition apparatus of the present invention, the circulation path 6 supplies the residual gas after the oil content is recovered by the oil content recovery device 5 to the heat exchanger 1 as an oxygen-free gas. Connected to the vessel 1 by piping. By providing the circulation path 6, it is possible to recover an oil component having a constant composition and stable quality at a higher recovery rate. The residual gas supplied to the heat exchanger 1 through the circulation path 6 can be directly supplied to the heat exchanger 1, but can also be supplied to the heat exchanger 1 after being heated in a hot stove (not shown). Good. In FIG. 1, the circulation path 6 is connected only to the second dry distillation column 13b. However, the present invention is not limited to this, and the circulation path 6 may be connected to the first dry distillation column 13a. Alternatively, when a condenser is installed, the circulation path 6 may be connected to the condenser. In the thermal decomposition apparatus of the present invention, surplus gas can be released into the atmosphere after being treated by the exhaust gas treatment device 16 via the exhaust fan 15. In FIG. 1, only the pipe connecting the oil content recovery device 5 and the heat exchanger 1 is shown as a circulation path 6. However, since the thermal decomposition apparatus of the present invention is a circulation type, Piping such as piping connecting the processing device 4 and piping connecting the thermal decomposition processing device 4 and the oil content recovery device 5 can also be included as part of the circulation path.

  When performing thermal decomposition of polymer waste using the thermal decomposition apparatus of the present invention, pyrolysis gas is generated from the polymer waste and oxygen-free gas. It is preferable to control the temperature at 300 to 600 ° C. If the temperature at the time of thermal decomposition is within the above specified range, the polymer waste can be stably and continuously decomposed without going through the melting step. If the polymer waste is melted, the contact with the oxygen-free gas is limited to the melt surface, so the thermal decomposition rate is lowered. If the temperature during the pyrolysis is less than 300 ° C., the pyrolysis reaction does not proceed sufficiently, and this is not preferable because there is a possibility of generating a carbide in which the components to be decomposed are not completely removed. Exceeding the above, there is a possibility of occurrence of the above-described melting phenomenon, and an undesirable reforming reaction or activation reaction occurs between the generated carbide and a component (for example, oxide) that can be contained in the gas, There is a possibility that the total acidity in the carbide is increased, or a carbide which is porous and may adversely affect the reinforcing effect on the rubber may be generated. Here, in order to control the temperature at the time of thermal decomposition, the oxygen-free gas heated in the heat exchanger 1, the external heating means 9 for heating the thermal decomposition furnace 3 from the outside, or the like may be used. .

  Next, when the thermal decomposition apparatus of the present invention is used, the carbide remaining in the thermal decomposition furnace after the thermal decomposition of the polymer waste is recovered. For example, when pyrolyzed gas is generated and an oil component obtained by condensing the pyrolyzed gas is recovered, the pyrolyzed carbide remains in the pyrolysis furnace 3, so that the carbide can be recovered. Although the carbide is obtained by the above-described recovery method, generally, it is recovered as a lump, so for example, the carbide recovered by a pulverization process using a pulverizer or the like is finely crushed and further classified. It can be recovered and extracted as a carbide having a specific particle size by a classification process using, for example. The carbide thus obtained can be used as a rubber reinforcing filler in place of carbon black or a part thereof.

  In the thermal decomposition apparatus of the present invention, the oxygen concentration in the apparatus is preferably controlled to 1% by volume or less. If the oxygen concentration in the pyrolysis apparatus is 1% by volume or less, oxidation of carbides remaining in the pyrolysis furnace after pyrolysis can be more reliably suppressed, quality does not deteriorate, and even if blended with a rubber component Carbide that can sufficiently maintain rubber properties can be obtained more reliably. The oxygen concentration in the thermal decomposition apparatus can be measured by, for example, a zirconia oxygen sensor using a solid electrolyte zirconia-based oxygen concentration cell.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Example 1)
By using the pyrolysis apparatus shown in FIG. 1, the waste truck tire was pyrolyzed to recover the carbides. In addition, the thermal decomposition processing apparatus 4 used for the thermal decomposition apparatus of Example 1 is comprised in detail by the structure shown in FIG. Further, as shown in FIG. 2, the oxygen-free gas introduction pipe 7 is installed on the central axis of the pyrolysis furnace 3, and the distance (D) from the tip of the oxygen-free gas introduction pipe 7 to the inner wall of the pyrolysis furnace 3 is 20cm.
Specifically, about 100 kg of waste truck tire cut products (polymer waste 2) are put into the pyrolysis furnace 3 (capacity 0.5 m ³ , inner diameter (d ₁ ) 0.8 m, height 1 m), After replacing the inside of the pyrolysis furnace 3 with nitrogen gas generated by the nitrogen gas supply source 8, the gas temperature was raised to about 500 ° C. by the heat exchanger 1 while circulating the nitrogen gas, and this temperature was maintained. . The oxygen concentration in the thermal decomposition apparatus was controlled to 1% by volume or less. Next, the oxygen-free gas heated in the heat exchanger 1 was introduced into the pyrolysis furnace 3 through the oxygen-free gas introduction pipe 7 (inner diameter (d ₂ ) 15 cm) through the inlet. At this time, the flow rate of the oxygen-free gas introduced into the pyrolysis furnace 3 was controlled to be 0.004 m ³ (STP) / second. About 45 hours after the start of introduction of oxygen-free gas into the pyrolysis furnace 3, oil begins to accumulate in the dry distillation column 13 a and about 3 hours after the introduction of oxygen-free gas into the pyrolysis furnace 3 is started. Distillation stopped later. Stopping the distillation showed that the thermal decomposition reaction was completed, and the heat exchanger 1 was stopped and the system was left to cool for about 12 hours. Thereafter, the carbide was taken out from the pyrolysis furnace 3. Since the carbide includes a steel cord as a tire material, excess tire constituent materials other than the carbide were removed with a magnetic separator. Carbide from which excess tire components have been removed is crushed into fine powder with a particle size of 1 mm or less with a hammer-type pulverizer, and the fine powder is classified with an air classifier having rotating blades. The coarse powder was removed and the carbide was recovered.

(Comparative Example 1)
Instead of the thermal decomposition treatment apparatus 4 shown in FIG. 2, the thermal decomposition treatment apparatus shown in FIG. 4 from which the oxygen-free gas introduction pipe protruding in the thermal decomposition apparatus space is removed is installed. The polymer waste was pyrolyzed using a pyrolysis apparatus.
Specifically, about 100 kg of the same polymer waste 2 as that used in Example 1 is put into the pyrolysis furnace 3, and the inside of the pyrolysis furnace 3 is nitrogen gas generated by the nitrogen gas supply source 8. After the replacement, the gas temperature was raised to about 500 ° C. by the heat exchanger 1 while circulating the nitrogen gas, and this temperature was maintained. The oxygen concentration in the thermal decomposition apparatus was controlled to 1% by volume or less. Next, the oxygen-free gas heated by the heat exchanger 1 was introduced into the pyrolysis furnace 3 from the inlet. At this time, the flow rate of the oxygen-free gas introduced into the pyrolysis furnace 3 was controlled to be 0.004 Nm ³ (STP) / second. About 60 hours after the start of introduction of oxygen-free gas into the pyrolysis furnace 3, oil begins to be accumulated in the dry distillation column 13 a and about 5 hours after the introduction of oxygen-free gas into the pyrolysis furnace 3 is started. Distillation stopped later.

  From the results of Example 1 and Comparative Example 1, the pyrolysis apparatus of Example 1 was compared with Comparative Example 1 in spite of introducing a gas body having the same gas temperature and gas flow rate into the pyrolysis furnace. It can be seen that the time to start the reaction is reduced by 25% and the time to complete the pyrolysis reaction is reduced by 40%. In addition, the acidity evaluated by neutralization reaction with sodium hydroxide as a property of the generated carbide (sample after fine pulverization and classification) is 0.083 milliequivalent per gram for the carbide of Example 1. While it was low, the carbide of Comparative Example 1 was 0.124 milliequivalent per gram. This difference is considered to be because the occurrence of the oxidation reaction has increased due to the prolonged thermal decomposition reaction in Comparative Example 1. Therefore, the present invention is an effective means for improving the performance as a filler when the recovered carbide is used as a filler for a rubber composition.

DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Polymer waste 3 Pyrolysis furnace 4 Pyrolysis processing apparatus 5 Oil content collection apparatus 6 Circulation path 7 Anoxic gas introduction pipe 8 Anoxic gas supply source 9 External heating means 10 Flow meter 11 Damper 12 Blower 13 Carbonization tower 14 Recovery tank 15 Ventilator 16 Exhaust gas treatment device S Space

Claims (7)

A heat exchanger for heating anoxic gas;
It has a discharge port for discharging the pyrolysis gas and an introduction port for introducing oxygen-free gas, and has a pyrolysis furnace for containing the polymer waste inside, and the polymer waste in the heat exchanger A thermal decomposition treatment device for generating thermal decomposition gas by thermal decomposition by contacting with heated oxygen-free gas;
An oil content recovery device for recovering condensed oil by cooling the pyrolysis gas generated in the thermal decomposition processing device;
In the thermal decomposition apparatus for polymer waste, comprising a circulation path for supplying the residual gas after the oil is recovered by the oil recovery apparatus to the heat exchanger as an oxygen-free gas,
A pyrolysis apparatus for polymer waste, wherein the introduction port for introducing the oxygen-free gas has an oxygen-free gas introduction pipe protruding from the inner wall of the pyrolysis furnace to the space in the furnace.   2. The polymer waste pyrolysis apparatus according to claim 1, wherein an opening surface of the oxygen-free gas introduction pipe is disposed so as to face an inner wall surface of the pyrolysis furnace. 3.   The thermal decomposition apparatus for polymer waste according to claim 2, wherein an opening surface of the oxygen-free gas introduction pipe is installed so as to face a bottom wall surface of the pyrolysis furnace. Of claim 1 the ratio of the inner diameter of the pyrolysis furnace (d ₁₎ and the inner diameter of the oxygen-free gas introduction pipe _{(d 2) (d 2 /} d 1) is characterized in that 0.1 to 0.25 Polymeric waste pyrolysis equipment. The ratio (D / d ₁ ) between the inner diameter (d ₁ ) of the pyrolysis furnace and the distance (D) from the tip of the oxygen-free gas introduction pipe to the inner wall of the pyrolysis furnace is 0.2 to 0.4, The thermal decomposition apparatus for polymer waste according to claim 1.   2. The polymer waste pyrolysis apparatus according to claim 1, wherein the opening portion of the oxygen-free gas introduction pipe is formed in a shape that expands toward the downstream side in the oxygen-free gas flow direction.   2. The polymer waste pyrolysis apparatus according to claim 1, wherein one or a plurality of holes are formed in a side surface of a portion where the oxygen-free gas introduction pipe is inserted.

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