JPH10130659A - Apparatus for decomposing plastic waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decomposition apparatus by which the decomposition of mixed plastic wastes can be performed in succession to pretreatment such as dehydrochlorination. SOLUTION: This apparatus is provided with a pretreatment section Sb and a decomposition section Sa. Each of these sections is provided with a rotary inner cylinder 2 or 3 having a conveying blade 1 and an outer cylinder 5 which forms reaction chambers 7 and 8 each of which is confined by the cylinder 5 and the periphery of each inner cylinder. In the pretreatment section, the plastic wastes fed to the reaction chamber is conveyed in the direction shown by an arrow X, whereupon the fusible plastic is molten into a liquid by the heat from a heating flue, and the non-fusible plastic undergoes a dehydrochlorination reaction, etc. In the decomposition section, the liquid-phase polymer formed in the pretreatment section is continuously introduced into the reaction chamber where the liquid-phase polymer is conveyed in the direction shown by an arrow Z, whereupon it is decomposed into a fuel oil or a fuel gas by the heat from the heating flue.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for treating waste plastic, and more particularly to a technique for treating a waste plastic mixed with a plastic that releases hydrogen chloride or cyan by heating, such as polyvinyl chloride, ABS resin, or polyacrylonitrile. The present invention relates to a processing technique capable of continuously performing oil conversion and gasification in a preliminary treatment such as dehydrochlorination.

[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, and those that cannot be oiled or gasified, such as polyvinyl chloride and polyethylene terephthalate, that is, dehydrochlorination without heating and liquefaction There are some that occur, but the former account for a much larger proportion. Therefore, waste plastic is converted into oil or gas at a reasonable cost, and collected and recovered as fuel oil or fuel gas.
Recycling is the most desirable method of treating waste plastic.

However, in practice, a technology for recycling waste plastic as fuel oil or fuel gas at a reasonable cost has not yet been put to practical use. There are two main causes. One of them concerns the decomposition itself in oil and gasification. For example, because a large amount of carbon is generated during decomposition, control of decomposition, particularly control of decomposition temperature, cannot be performed effectively, and it is not possible to efficiently generate a recovered material having a desired composition. That is, the decomposition process cannot be performed at a reasonable cost.

[0004] Another problem is a problem in the case of treating a mixed waste plastic mixed with polyvinyl chloride or the like. That is, for example, polyvinyl chloride releases hydrogen chloride upon heating, so if this hydrogen chloride is added to the product generated by dissolution and decomposition of plastic,
There is a problem that the separation is difficult, and the usefulness of the recovered material is greatly reduced when hydrogen chloride is contained in the final recycled recovered product obtained by cooling the product. 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. Therefore, in the case of mixed waste plastics, it is necessary to perform a preliminary treatment such as dehydrochlorination prior to the oiling treatment or gasification treatment.
The efficiency of this pretreatment and the treatment of polyvinyl chloride or the like after dehydrochlorination have a considerable effect on the cost of the entire decomposition treatment.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made so that the mixed waste plastics can be decomposed continuously with a pretreatment such as dehydrochlorination. It is an object of the present invention to provide a decomposer, and more particularly to provide a decomposer capable of efficiently performing a preliminary treatment prior to a decomposition treatment and effectively preventing generation of carbon that adversely affects a decomposition reaction.

[0006]

A disassembly apparatus according to the present invention for achieving the above object includes a pretreatment section and a disassembly section. Each of these two sections includes an inner cylinder having a transport blade provided on the outer periphery and rotatable, and an outer cylinder forming a reaction chamber between the inner cylinder and the outer periphery. In the pretreatment section, the waste plastic supplied to the reaction chamber is supplied from one side to the other side in the reaction chamber by rotation of the inner cylinder, and is supplied to the reaction chamber using the inside of the inner cylinder as a heating path. With the heating energy, the molten plastic melts and liquefies, and the non-meltable plastic undergoes a dehydrochlorination reaction, etc., while the decomposition section continuously converts the liquid-phase polymer produced in the pretreatment section. The liquid phase polymer is received in the reaction chamber, and the liquid polymer is conveyed from one side to the other side in the reaction chamber by rotation of the inner cylinder. And decompose into fuel gas.

One of the features of such a decomposition apparatus according to the present invention is that a decomposition treatment of a mixed waste plastic containing a non-melting plastic such as, for example, polyvinyl chloride or polyacrylonitrile is performed by dehydrochlorination or the like. This means that the pre-processing can be performed continuously, and in particular, it is characterized in that the pre-processing is performed by a screw conveyor structure in which a conveying blade is provided in the inner cylinder. That is, by adopting the screw conveyor structure, the liquid-phase polymerization of the fusible plastic can be promoted while performing the dehydrochlorination reaction or the like on the non-fusible plastic. At the same time, the liquid-phase polymer and the non-melting plastic can be efficiently separated. The liquid-phase polymer is continuously supplied to the decomposition section, while the non-meltable plastic can be recovered from one end of the pretreatment section, for example, as a solid fuel.

Another feature of the processing apparatus according to the present invention is that
The purpose of the present invention is to decompose the liquid phase polymer supplied from the pretreatment section in a decomposition section also having a screw conveyor structure. That is, the liquid-phase polymer supplied to the decomposition section forms a shallow liquid layer at the bottom of the reaction chamber, and is scraped from the liquid layer to the outer peripheral surface of the inner cylinder in accordance with the rotation of the inner cylinder. A thin film is formed, and heating energy is supplied in this thin film state to decompose and vaporize. In other words, the liquid phase polymer that is going to decompose and vaporize is, for example, 0.5 m
The thin film having a thickness of not more than m is in contact with the heating source, so that the whole can always be kept at a uniform temperature. Further, the product generated from the liquid-phase polymer (which becomes a fuel oil or a fuel gas when cooled to about room temperature) is quickly released from the liquid-phase polymer, so that the state in which the product is exposed to excessive heating can be eliminated. That is, excessive heating of the product is the largest cause of carbon generation. By removing this, carbon generation 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, the decomposition reaction of the polymer can be effectively controlled, and high-quality fuel oil or fuel gas having a desired composition can be efficiently recovered. In addition, the burden on maintenance of the apparatus can be greatly reduced, and furthermore, monitoring of the reaction process is substantially unnecessary, and unmanned operation can be performed.

[0009] In the processing apparatus as described above, the pretreatment section and the disassembly section can have a structure in which the respective reaction chambers and the heating path are integrally communicated. It is also possible to adopt a structure in which the section and the reaction chamber communicate with each other via the feeding section.

In the former case, it is preferable that the diameter of the inner cylinder of the disassembly section is larger than the diameter of the inner cylinder of the pretreatment section. The liquid phase polymer generated in the section can be smoothly supplied to the decomposition section.

Further, in the processing apparatus as described above, it is more preferable that a small-diameter portion in which the thickness of each of the inner cylinder and the outer cylinder is relatively small is provided in the preliminary processing section on the front side in the transport direction. By doing so, the efficiency of heating and compression of the non-melting plastic separated from the liquid-phase polymer can be increased, thereby increasing the dehydrochlorination of the non-melting plastic and increasing the solid fuel Can be promoted efficiently. In other words, for non-melting plastics that turn into solid fuels, unlike meltable plastics, there is no need to avoid the generation of carbon, and conversely, promoting carbonization and dehydrochlorination increases the quality of solid fuels, It is desirable to increase the heating temperature and the compression ratio. And such a condition can be realized by the small diameter portion.

Further, with respect to the processing apparatus as described above,
The heating path may be structured, for example, like a rotary kiln, and the heating energy may be obtained by incinerating incineration waste in the heating path. By doing so, complex treatment of waste can be performed.

[0013]

Embodiments of the present invention will be described below. The processing apparatus according to the first embodiment has a structure in which a preliminary processing section and a disassembly section are integrated. Specifically, as shown in FIG. 1, an inner cylinder 2 for a disassembled section Sa having a screw structure having a transport blade 1 on the outer periphery thereof.
And the inner cylinder 3 for the preliminary processing section Sb
To form a single continuous cylinder by joining freely. The two inner cylinders 2 and 3 are commonly covered by an integral outer cylinder 5 to form a reaction chamber 7 for the decomposition section Sa and a reaction chamber 8 for the pretreatment section Sb.

Further, the diameter of the inner cylinder 2 is made larger than the diameter of the inner cylinder 3, and the inner cylinder 3 has a small diameter portion 3 s on the front side in the direction in which the waste plastic is conveyed for pretreatment as described later. The thickness of the outer cylinder 5 is reduced accordingly.

The dehydrochlorination treatment and the decomposition treatment of the waste plastic by such a treatment device are performed as follows. The inner cylinder 2 of the disassembly section Sa is rotated, for example, clockwise by the motor 9 via the gears 10 and 11, while the inner cylinder 3 of the pretreatment section Sb is rotated by the motor 1
2, it is rotated counterclockwise through gears 13 and 14. The waste plastic introduced from the hopper 15 connected to the outer cylinder 5 is conveyed in the direction of the arrow X in the reaction chamber 8 by the inner cylinder 3, during which the heating path communicating from the inner cylinder 2 to the inner cylinder 3. It is heated by heating energy supplied by a burner 17 through 16. By this heating, the fusible plastic contained in the waste plastic is melted and liquefied.

The liquid-phase polymer produced in the pretreatment section Sb in this way separates from the non-melting plastic and flows as indicated by the arrow Y while remaining at the bottom of the reaction chamber 8 to enter the reaction chamber 7 of the decomposition section Sa. It is supplied continuously. In the decomposition section Sa, the liquid-phase polymer is heated while being conveyed in the direction of arrow Z, thereby being decomposed and vaporized.
The liquid phase polymer in the decomposition section Sa is in a state of forming a liquid layer L having a shallow liquid depth at the bottom of the reaction chamber 7 as shown in FIG. In this state, the liquid phase polymer is scraped up by the rotation of the inner cylinder 2. Therefore, the liquid phase polymer forms a thin film F on the outer peripheral surface of the inner cylinder 2. Then, in the state of the thin film F, the thin film F is heated and decomposed and vaporized by the high-temperature hot air in the heating path 16 through the inner cylinder 4. The product generated thereby fills the entire reaction chamber 7 except for the shallow liquid layer L, and is successively guided from the product delivery port 18 to a cooling device (not shown), where it is cooled to produce fuel oil or fuel. Collected as gas. Whether the liquid-phase polymer is to be converted to oil or gas is determined by, for example, the conditions of the decomposition reaction determined by the type and amount of the catalyst.

On the other hand, the non-melting plastic is conveyed inside the reaction chamber 8 to a take-out section 19 connected to the tip of the reaction chamber 8 while causing a dehydrochlorination reaction or the like. During this time, it passes through the small-diameter portion 3s, where it is compressed at a higher density, thereby promoting dehydrochlorination and carbonization and progressing in solidification. It is. Hydrogen chloride gas and the like generated by a dehydrochlorination reaction and the like are sent from a gas discharge 20 to a gas processing device (not shown).

As for such a processing apparatus diagram, a cover cylinder is added around the outer cylinder 5, and this cover cylinder and the outer cylinder 5 are added.
It is more preferable to stabilize the temperatures of the two reaction chambers 7 and 8 by passing high-temperature exhaust gas from a heating path to be described later through a gap between the two reaction chambers. In addition, it is also preferable that the outer cylinder 5 can be rotated, so that residues and the like adhering and accumulating on the inner surface of the outer cylinder 5 can be cleaned by rotating the outer cylinder 5 when necessary. In addition to the processing of waste plastic that can be turned into oil, other waste is incinerated, and a heating path 16 is provided with a screw therein so that heat generated in the incineration can be used as heating energy. By providing a conveyor or the like, a rotary kiln structure can be provided.

The processing apparatus according to the second embodiment of the present invention has a structure in which a preprocessing section and a disassembly section are connected via a feeding section. Specifically, as shown in FIG. 3, the pre-processing section Sb placed vertically and the disassembly section Sa placed horizontally are connected by a feeding section 21.
And the hopper 2 connected to the preliminary processing section Sb.
The liquid-phase polymer generated in the reaction chamber 8 of the pretreatment section Sb from the waste plastic charged from the second section 2 accumulates and stays near the inlet of the small-diameter portion 3s, and this liquid-phase polymer passes through the feed section 21 and is decomposed into the decomposition section Sa. Is supplied to the reaction chamber. In such a structure in which the feeding section 21 is provided, an intermediate processing section is provided in the middle of the feeding section 21, and the intermediate processing section applies a process such as filtration for removing impurities and dehumidification for removing moisture to the liquid phase polymer. Alternatively, a treatment for adding a catalyst used for the decomposition reaction in the decomposition section Sa can be performed. The other structures are basically the same as those in the first embodiment, and thus the same reference numerals are given to the common parts, and the description thereof will be omitted. In FIG. 3, the illustration of the rotation drive system of the inner cylinder is omitted.

In the processing device according to the second embodiment, the direction of the preliminary processing section Sb can be inverted. In this case, the waste plastic put into the pretreatment section Sb is transported from the lower side to the upper side.

[0021]

As described above, according to the present invention, a non-melting plastic can be efficiently subjected to a pretreatment such as a dehydrochlorination treatment, and a carbon can be generated from a melting plastic. It is possible to effectively prevent the decomposition reaction and perform an efficient decomposition reaction, and it is possible to efficiently collect useful recyclable materials from the mixed waste plastic mixed with polyvinyl chloride or the like.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view schematically showing a decomposition apparatus according to a first embodiment.

FIG. 2 is a sectional view taken along the line SA-SA in FIG.

FIG. 3 is a partial cross-sectional side view showing a disassembly apparatus according to a second embodiment in a simplified manner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conveyance blade 2,3 Inner cylinder 3s Small diameter section 5 Outer cylinder 7,8 Reaction chamber 16 Heating path 21 Feeding section Sa Decomposition section Sb Pretreatment section

Claims (6)

[Claims] 1. A decomposing apparatus for decomposing waste plastic to recover it as fuel oil, fuel gas, etc., comprising a pretreatment section and a decomposition section, both of which are conveyed to the outer periphery. An inner cylinder provided with blades and rotatable; and an outer cylinder forming a reaction chamber between the inner cylinder and an outer periphery of the inner cylinder, and in the pretreatment section, waste supplied to the reaction chamber is provided. The plastic is conveyed from one side to the other side in the reaction chamber by the rotation of the inner cylinder, and is heated and supplied to the reaction chamber using the inside of the inner cylinder as a heating path. For non-melting plastics, a dehydrochlorination reaction occurs.
In the decomposition section, the liquid-phase polymer generated in the pretreatment section is continuously received in the reaction chamber, and the liquid-phase polymer is conveyed from one side to the other side in the reaction chamber by rotation of the inner cylinder. A decomposer characterized by being decomposed into fuel oil, fuel gas or the like by heating energy supplied to the reaction chamber using the inside of the as a heating path. 2. The decomposition apparatus according to claim 1, wherein the pretreatment section and the decomposition section integrally connect the respective reaction chambers and the heating path. 3. The disassembly apparatus according to claim 2, wherein the diameter of the inner cylinder of the disassembling section is larger than the diameter of the inner cylinder of the pretreatment section. 4. The decomposition apparatus according to claim 1, wherein the reaction chamber of the pretreatment section and the reaction chamber of the decomposition section communicate with each other via a feed section. 5. The pre-treatment section has a small-diameter portion in which the thickness of each of the inner cylinder and the outer cylinder is relatively reduced on the front side in the transport direction.
The disassembly device according to item. 6. The decomposition apparatus according to claim 1, wherein heating energy is obtained by incinerating incineration waste in a heating path.