JPH1161151A - Device for decomposing waste plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decomposition device enabling to effectively eliminate various factors inhibiting the full scale implementation of technology for the decomposition treatments of waste plastics. SOLUTION: This device for decomposing waste plastics is provided with plural reaction chambers 1, 2, 3, 4 vertically disposed in many stages. The reaction chambers have communication portions 1h, 2h, 3h, 4h in the central portions, respectively, and further have mortar-like heating surfaces downward inclined toward the communication portions, respectively. In the reaction chamber at the uppermost stage, waste plastics fed from outside are heated with the heating surface of the reaction chamber and simultaneously flowed down toward the communication portion. In the reaction chamber in the second stage, the waste plastics or their melted products fed from the reaction chamber in the uppermost state through the communication portion are heated with the heating surface of the second reaction chamber and simultaneously flowed down toward the communication portion. Hereafter, the same treatments are repeated to the reaction chamber in the lowermost stage. During the treatments, reactions such as a hydrogen chloride-removing reaction and decomposition reactions are generated on the waste plastics and their melted products.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing technique for decomposing waste plastic and recovering it as fuel oil or fuel gas.

[0002]

2. Description of the Related Art Waste plastics, such as polyethylene and polystyrene, which can be oiled or gasified, are melted by heating to form a liquid-phase polymer, which is decomposed in this liquid-phase polymer to form a fuel. Oil and fuel gas can be used as well as those that are difficult to oil or gasify, such as polyvinyl chloride and polyethylene terephthalate. There are things that occur. In general, the former accounts for a much larger proportion. Therefore, it can be said that it is the most desirable method for treating waste plastic to convert waste plastic into oil or gas at a reasonable cost and to collect and recycle it in the form of fuel oil or fuel gas.

In view of the above, regarding the decomposition treatment of waste plastic, for example, JP-A-49-115157, JP-A-59-111815, and JP-A-4-18.
Various techniques have been proposed, for example, in JP-A-0878, JP-A-5-237467 and JP-A-5-263079. However, these technologies have not yet reached the stage of full-scale practical application. There are various reasons. For example, a large amount of carbon is generated during the decomposition, so that the control of the decomposition, particularly the control of the decomposition temperature, cannot be performed effectively, and the recovered material having a desired composition cannot be efficiently generated. One of them. In addition, one of the reasons is that the processing efficiency and the heating efficiency are insufficient, so that the apparatus is increased in size, and the cost of the apparatus becomes excessively large.

[0004] Further, there is another problem in the case of treating a mixed waste plastic mixed with polyvinyl chloride or the like. For example, polyvinyl chloride releases hydrogen chloride when heated, so if this hydrogen chloride is added to the product obtained by dissolving and decomposing plastics, it is difficult to separate it, and as a result, the product is cooled and cooled. If hydrogen chloride is contained in the final recycled product obtained by the above method, there is a problem that the usefulness of the recovered material is greatly reduced. In addition, hydrogen chloride shortens the life of the oiling unit, especially the main factor, and the reactor, which accounts for a large proportion of the total unit cost, becomes extremely short, which significantly increases the cost of cracking treatment. There is also.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and effectively eliminates various factors that hinder the full-scale practical use of waste plastic decomposition processing technology. The purpose of the present invention is to provide a disassembly device capable of causing the disassembly.

[0006]

[Means for Solving the Problems]

[0007] The waste plastic decomposition apparatus according to the present invention includes a plurality of reaction chambers arranged in multiple stages in the vertical direction.
Each reaction chamber has a communicating part in the center and a mortar-shaped heating surface that is inclined downward toward the communicating part. In the uppermost reaction chamber, the waste plastic supplied from the outside flows down toward the communication section while being heated on the heating surface of the reaction chamber, and in the second reaction chamber, the waste plastic flows from the uppermost reaction chamber to the communication section. The waste plastic or the melt thereof supplied through the above is caused to flow down to the communicating portion while being heated on the heating surface of the reaction chamber, and thereafter the same processing is repeated up to the lowermost reaction chamber. In the meantime, a reaction such as dehydrochlorination and a decomposition reaction are caused in the waste plastic or its melt.

More specifically, a reaction such as dehydrochlorination is caused on polyvinyl chloride or the like in the upper reaction chamber, for example, the uppermost reaction chamber or the uppermost reaction chamber and the second reaction chamber. At the same time, the solid waste plastic is melted to form a melt, that is, a liquid polymer. On the other hand, in the lower reaction chamber, for example, in the second to third and subsequent reaction chambers, the liquid polymer is decomposed. The hydrogen chloride gas and the decomposed and vaporized polymer generated in these reaction processes are collected from the respective reaction chambers by different routes.

Such a decomposition apparatus according to the present invention can efficiently perform heating for dehydrochlorination and the like and heating for decomposition of a liquid phase polymer, and can effectively perform a decomposition reaction of a liquid phase polymer. Can be controlled. The mortar-shaped heating surface of each reaction chamber contributes to this. That is, the mortar-shaped heating surface can be heated in a state in which the waste plastic is made in a thin layer and is directly adhered to the heating surface. Therefore, the heating efficiency is high, and the gas generated by dehydrochlorination or the like is excellent in desorbability. In addition, the mortar-shaped heating surface forms a thin film on the liquid-phase polymer flowing down thereon, and heats the liquid-phase polymer in this thin-film state. That is, the liquid-phase polymer that is to be decomposed and vaporized comes into close contact with the heating surface in a thin film. Therefore, the whole can always be kept at a uniform temperature. Thus, the temperature gradient in the liquid phase polymer can be made very small to the extent that it is substantially absent. In addition, it is possible to quickly remove the vaporized substance generated from the liquid-phase polymer (which becomes a fuel oil or a fuel gas by cooling to about room temperature) from the liquid-phase polymer, thereby eliminating a state in which the vaporized substance is exposed to excessive heating, The generation of carbon can be effectively prevented. Furthermore, the heating efficiency for the liquid phase polymer for decomposition and vaporization is significantly increased, and the decomposition efficiency can be greatly improved. As a result, it becomes possible to effectively control the decomposition reaction of the polymer, and it is possible to efficiently recover oily substances, fuel gas, and the like having desired quality.

The decomposition apparatus according to the present invention has the following features because a plurality of reaction chambers are provided in multiple stages in the vertical direction. First, as described above, a dehydrochlorination reaction or the like and a polymer decomposition reaction can be continuously generated, and hydrogen chloride gas or the like generated by dehydrochlorination or the like is vaporized by the polymer decomposition reaction. Can be effectively avoided. Therefore, it is possible to efficiently treat plastic waste mixed with a non-melting plastic such as polyvinyl chloride, for example, plastic waste that is generally separated in small and medium-sized cities. The device structure can be made relatively compact. Second, the ratio of the heating area to the installation area of the device can be increased. That is, the processing efficiency per installation area of the apparatus can be increased. Third, increasing the number of reaction chamber stages as necessary;
That is, it is easy to increase the scale of the apparatus according to the required processing amount. Fourth, the structure that allows each reaction chamber to be separated is easy, and the life of the entire apparatus can be extended by replacing only the reaction chamber whose life is shortened in order to work on dehydrochlorination or the like. .

In the above-described decomposition apparatus, it is preferable to provide a heating chamber between the reaction chambers and supply heat energy from the heating chamber to the heating surface of each reaction chamber.
By doing so, the heating temperature on the heating surface of each reaction chamber can be individually controlled, and the control of the continuously generated dehydrochlorination reaction and polymer decomposition reaction can be easily performed.

In the above-mentioned decomposition apparatus, a rotary shaft is provided so as to penetrate a communication portion of each reaction chamber, and a conveyor blade is provided on the rotary shaft at a position corresponding to the communication portion of each reaction chamber. Is preferred. The conveyor blade provided in this manner functions to assist the movement of the solid polymer or liquid phase polymer moving to the adjacent reaction chamber through the communication part, and also functions as a seal for the communication part. As a result,
It is possible to effectively prevent hydrogen chloride gas or polymer decomposition and vapor generated in each reaction chamber from entering another reaction chamber.

[0013] Further, with respect to the above-mentioned disassembling apparatus,
A diffuser having a cone-shaped portion is provided in the second and subsequent reaction chambers,
It is preferable that the waste plastic or the melt thereof supplied through the communication portion is diffused and guided to the outer peripheral portion of the heating surface by the diffuser. In this way, the entire mortar-shaped heating surface can be used more effectively.

[0014] It is further preferred that the diffuser as described above is made rotatable. To this end, it is reasonable to connect and provide a diffuser to the rotating shaft.

[0015]

Embodiments of the present invention will be described below. As shown in FIG. 1, a decomposition apparatus according to an embodiment of the present invention includes a first-stage reaction chamber 1, a second-stage reaction chamber 2, a third-stage reaction chamber 3, and a fourth-stage reaction chamber 4. It has a four-stage structure in which the heating chambers 5, 6, 7, and 8 are sandwiched between these reaction chambers. The sandwich structure of the reaction chamber and the heating chamber is unitized, for example, with the reaction chamber and the heating chamber as a unit, and can be assembled and disassembled for each unit. For this purpose, the units are stacked in a stacked structure as shown in an enlarged manner in FIG. This overlapping structure is a structure in which a lower end T of an upper unit is fitted to a gutter-like support portion S provided in a lower unit. The supporting portion S is formed sufficiently wider than the lower end T, and a gap between the supporting portion S and the lower end T is filled with sand P or the like as a sealing material. This makes it possible to absorb differences in thermal deformation between the units.

Each reaction chamber has a heating surface 1f, 2f, 3f, 4
f. Each of the heating surfaces has a mortar-like shape that is inclined downward toward the communicating portions 1h, 2h, 3h, and 4h provided at the center of each reaction chamber. The rotating shaft 10 is made to penetrate each reaction chamber through each communicating part. A conveyer blade 11 having a screw structure is provided on the rotating shaft 10 at a position corresponding to a communicating portion of each reaction chamber. The outer diameter of the conveyor blade 11 is approximately equal to the inner diameter of the communicating portion.

The first-stage reaction chamber 1 functions to receive waste plastic supplied from the outside, and is heated so that the waste plastic is spread on the heating surface 1f, so that, for example, the waste plastic contained in the waste plastic is contained. It functions to cause a dehydrochlorination reaction on vinyl chloride. Therefore, the reaction chamber 1 is provided with a supply section 12 for waste plastic, a recovery section 13 for recovering hydrogen chloride gas generated by the dehydrochlorination reaction, and a stirrer 14. Stirrer 14
Has a structure in which a stirring tooth 14t is attached to an arm 14a connected to the rotating shaft 10 in a comb-like shape so as to have a length approximately equal to the radius of the heating surface 1f.

Each of the reaction chambers in the second and subsequent stages in this example functions for the decomposition reaction of the liquid phase polymer, and has basically a common structure. That is, in each of the second and subsequent reaction chambers,
A diffuser 15 connected to the rotating shaft 10 is provided. Diffuser 1
5 is formed in a substantially conical shape, and a stirring tooth 15t for stirring the solid plastic or liquid-phase polymer on the heating surface is attached to the lower surface thereof in a comb-like shape. Each of the second and subsequent reaction chambers is provided with a collecting section 16 for collecting vaporized materials.
These collecting sections 16 are connected to a common pipe (not shown) and connected to a collecting device (not shown). Further, in each of the second and subsequent reaction chambers, the ceiling is made parallel to the inclined surface 15f of the diffuser 15, and the brush 17 is provided there. This brush 17 is used for scraping off the deposits on the inclined surface 15f. When the brush 17 is operated, the inclined surface 15 f is pressed against the brush 17 by slightly lifting the rotating shaft 10.

The heating chambers 6, 7, 8 have a structure in which the heating surfaces 2f, 3f, 4f of each reaction chamber can be directly heated by hot air supplied from a burner 19 attached thereto. On the other hand, the heating chamber 5 has a structure in which the heating surface 1f is heated using exhaust air from the heating chambers 6, 7, and 8.
For that purpose, the hot air collected in the exhaust unit 20 of the heating chambers 6, 7, 8 is supplied to the heating chamber 5 by the air guide tube 21.

The treatment of waste plastic using such an apparatus is performed as follows. Waste plastic as municipal waste is continuously supplied to the first-stage reaction chamber 1 through a supply unit 12 from a hopper (not shown) or the like.
In the reaction chamber 1, the stirrer 14 rotates along with the rotation of the rotating shaft 10 to spread the waste plastic in a thin layer on the heating surface 1f while stirring. The waste plastic spread on the heating surface 1f flows down the heating surface 1f toward the communicating portion 1h while being heated by receiving the heating energy supplied from the heating chamber 13 to the heating surface 1f. During this time, the waste plastic is heated to, for example, about 200 to 300 ° C., and the fusible plastic becomes a liquid polymer, while the infusible plastic, for example, polyvinyl chloride, undergoes a dehydrochlorination reaction. The hydrogen chloride gas generated by this is sent out to a recovery device (not shown) via the recovery unit 13. In the recovery device, the hydrogen chloride gas is reacted with, for example, aluminum scrap to recover in the form of aluminum chloride. This aluminum chloride can be used as a high-performance catalyst in a decomposition reaction described below.

The liquid polymer produced by the treatment in the first-stage reaction chamber 1 is forcibly fed by the conveyor blades 11 and solids such as infusible plastic and the like through the communicating portion 1h. Supplied to The liquid polymer supplied to the second-stage reaction chamber 2 is heated by the heating surface 2 while being spread by the inclined surface 15 f of the diffuser 15 rotating together with the rotating shaft 10.
It flows down to the outer periphery of f. The liquid polymer that has flowed down to the outer peripheral portion of the heating surface 2f forms a thin film of, for example, 1 mm or less on the heating surface while being stirred by the stirring teeth 15t, and is heated toward the communication portion 2h by the heating surface 2f. Flow down. The heating temperature for the decomposition of the liquid polymer is about 400 to 500 ° C. if no catalyst is used,
In the case where aluminum chloride or the like is used as the catalyst, the temperature is set to about 350 ° C. During this time, the liquid polymer gradually decomposes to form a vapor. The generated vapor is sent out to a collecting device (not shown) via the collecting unit 16.

The liquid polymer supplied to the third reaction chamber 3 without being completely decomposed in the second reaction chamber 2 is spread by the diffuser 15 in the same manner as in the second reaction chamber 2. While flowing down to the outer peripheral portion of the heating surface 3f, it flows down to the communicating portion 3h while being heated as a thin film on the heating surface, and a decomposition reaction occurs during this time. The same is performed in the fourth-stage reaction chamber 4, and by the time the treatment in the fourth-stage reaction chamber 4 is completed, substantially all of the liquid polymer is decomposed and becomes a vapor. On the other hand, solids, residues, and the like that have flowed down together with the liquid polymer are discharged from the discharge unit 22 to the outside.

[0023]

As described above, according to the present invention, the problem of the processing capacity associated with the decomposition treatment of waste plastic, the problem of generating a large amount of carbon, and the problem of hydrogen chloride when polyvinyl chloride is mixed are effective. This can greatly advance the full-scale practical use of waste plastic recycling processing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a disassembly apparatus according to an embodiment.

FIG. 2 is an explanatory diagram of a stacked structure of units.

[Explanation of symbols]

 1,2,3,4 Reaction chamber 1f, 2f, 3f, 4f Heating surface 1h, 2h, 3h, 4h Communication part 5,6,7,8 Heating chamber 10 Rotation axis 11 Conveyor blade 15 Diffuser

Claims (5)

[Claims] 1. A decomposing apparatus for decomposing waste plastic and recovering it as fuel oil, fuel gas, or the like, has a communicating portion at a central portion, and has a mortar-shaped heating sloping downward toward the communicating portion. A reaction chamber having a surface is provided in multiple stages so as to sequentially communicate with each other through respective communication sections, and in the uppermost reaction chamber, waste plastic supplied from the outside is heated while being heated on the heating surface of the reaction chamber. In the second-stage reaction chamber, waste plastic or its melt supplied from the uppermost reaction chamber through the communication section is heated and heated by the heating surface of the reaction chamber to the communication section. Thereafter, the same treatment is repeated up to the lowermost reaction chamber, during which a reaction such as dehydrochlorination and a decomposition reaction occur in the waste plastic or its melt. A disassembly device characterized by the fact that: 2. The decomposition apparatus according to claim 1, wherein a heating chamber is provided between each reaction chamber, and heat energy is supplied from the heating chamber to a heating surface. 3. The method according to claim 1, wherein a rotating shaft is provided so as to penetrate a communicating portion of each reaction chamber, and a conveyor blade is provided on the rotating shaft at a position corresponding to the communicating portion of each reaction chamber. The disassembly apparatus according to any one of the preceding claims. 4. A diffuser having a cone-shaped portion is provided in the second and subsequent reaction chambers, and waste plastic or a melt thereof supplied through the communicating portion is diffused to the outer peripheral portion of the heating surface by the diffuser. The disassembly device according to any one of claims 1 to 3, wherein the disassembly device is configured to guide the disassembly. 5. The disassembly device according to claim 4, wherein the diffuser is connected to the rotation shaft.