JPH10183138A - Treatment of waste plastic and treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating waste plastics capable of performing a decomposition treatment of the mixed waste plastics following to a preliminary treatment such as dehydrochlorination. SOLUTION: This method for treating waste plastics comprises a step for performing a preliminary treatment by traveling a conveyer belt 10 in a heated atmosphere to heat waste plastics charged on the conveyer belt 10 and to melt and liquefy the meltable plastics, and on the other hand to allow the dehydrochlorination reaction, etc., of an unmelted plastics to be caused and further to separate the liquid polymer formed by melting and liquefying the meltable polymer by a liquid penetrable properties of the conveyer belt 10 from a solid material, and a step for decomposing the liquid polymer obtained by the step for performing a preliminary treatment by charging the liquid polymer to a decomposing section Sa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for treating waste plastics, and particularly to a plastic, such as polyvinyl chloride, PET resin or polyacrylonitrile, which is difficult to decompose and liquefy by heating and releases hydrogen chloride and cyanide. The present invention relates to a processing technology that can continuously convert oil waste and gasification of mixed waste plastics to 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 as well as those that are difficult to oil or gasify, such as polyvinyl chloride and polyethylene terephthalate. 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 developed in view of the above-mentioned circumstances. In particular, it is an object of the present invention to provide a technique capable of efficiently performing a preliminary treatment prior to the decomposition treatment and effectively preventing the generation of carbon that adversely affects the decomposition reaction.

[0006]

SUMMARY OF THE INVENTION A method for treating waste plastic according to the present invention is based on the fact that waste plastic is decomposed and recovered as fuel oil or fuel gas.
For this purpose, a conveyor belt having liquid permeability is run in a heated atmosphere, and waste plastic continuously supplied on the conveyor belt is heated along with the movement of the conveyor belt. While liquefaction, non-melting plastics undergo a dehydrochlorination reaction, etc., and pretreatment to separate the liquid-phase polymer produced by melting and liquefaction of the fusible plastics from solids by the liquid permeability of the conveyor belt. No, and the liquid phase polymer obtained in this pretreatment is supplied to a decomposition section to be decomposed.

Further, the processing apparatus according to the present invention includes an inner cylinder provided with conveying blades on the outer periphery and rotatable, and an outer cylinder forming a reaction chamber between the inner cylinder and the outer periphery of the inner cylinder. A decomposition section configured to supply heating energy to the reaction chamber using the inside of the cylinder as a heating path is provided, and is provided so as to travel inside a shielding cylinder provided in the heating path inside the inner cylinder. A pretreatment section comprising a conveyor belt having liquid permeability is provided, and in the pretreatment section, waste plastic continuously supplied on the conveyor belt is heated as the conveyor belt travels to melt the waste plastic. While fusible plastics are melted and liquefied, non-fusible plastics undergo a dehydrochlorination reaction, etc. - a liquid phase polymer produced by liquefaction was separated from the solids by liquid permeability of the conveyor belt, and has a liquid-phase polymer was separated from the solids to degrade supplied to the reaction chamber.

One of the features of the treatment method and the treatment apparatus according to the present invention is that the decomposition treatment of the mixed waste plastic mixed with a non-melting plastic such as polyvinyl chloride or polyacrylonitrile is performed by dechlorination. This means that the pretreatment can be continuously performed with hydrogen or the like, and is characterized in that the pretreatment is performed using a conveyor belt having liquid permeability. In other words, the use of a conveyor belt system allows the non-melting plastic to undergo a dehydrochlorination reaction while promoting the liquid-phase polymerization of the melting plastic, and at the same time efficiently separates the liquid-phase polymer from solids. Can be done
In addition, by effectively separating the liquid-phase polymer from hydrogen chloride and the like generated by the dehydrochlorination reaction, etc., the product obtained by decomposition of the liquid-phase polymer due to mixing of hydrogen chloride and the like into the liquid-phase polymer is obtained. Deterioration can also be effectively prevented. The liquid-phase polymer is continuously supplied to the decomposition section, while the non-melting plastic can be recovered from one end of the conveyor belt, for example, as a solid fuel. That is, the pretreatment of the mixed waste plastic can be efficiently performed in various senses.

Another feature of the processing apparatus according to the present invention is that
The decomposition section has a screw conveyor structure including an inner cylinder having a conveying blade on the outer periphery and an outer cylinder covering the inner cylinder, and the liquid phase polymer obtained in the pretreatment is decomposed by the decomposition section having the screw conveyor structure. .
That is, the liquid phase polymer supplied to the decomposition section
A liquid layer having a shallow liquid depth is formed at the bottom of the reaction chamber, and a thin film is formed by being scraped up from the liquid layer on the outer peripheral surface of the inner cylinder in accordance with the rotation of the inner cylinder. It is supplied and decomposed and vaporized. That is, the liquid-phase polymer that is to be decomposed and vaporized comes into contact with the heating source as a thin film of, for example, about 0.5 mm, and 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.

Further, the processing apparatus according to the present invention is characterized in that the waste plastic on the conveyor belt is heated using the heating path of the inner cylinder. With such a structure, the heating source can be used for both the pretreatment and the decomposition reaction, and the heating energy can be largely saved.

[0011]

Embodiments of the present invention will be described below. As shown in FIG. 1, a processing apparatus according to an embodiment of the present invention includes a disassembly section Sa and a preliminary processing section Sb.
Is provided. The disassembly section Sa is composed of an inner cylinder 2 having a screw structure having a conveying blade 1 on the outer periphery, and an outer cylinder 4 forming a reaction chamber 3 between the inner cylinder 2 and the inner cylinder 2.
, The axis is shifted downward. By doing so, the upper space of the reaction chamber 3 can be made relatively larger than the lower space, and as will be described later, the liquid phase polymer of the vapor generated by the decomposition reaction of the liquid phase polymer in the reaction chamber 3 Can be promoted. The inner cylinder 2 has a heating path 5 inside.
The heating energy is supplied to the reaction chamber 3 by blowing high-temperature hot air through the heating path 5 with a burner or the like. The inner cylinder 2 has a gear 6 on the outer periphery of each of the left and right ends, and a driving system 7
To rotate. On the other hand, the outer cylinder 4 has a collection port 8 connected to a collection device (not shown).

The pretreatment section Sb runs endlessly in a state in which the shield tube 9 provided inside the heating path 5 of the inner cylinder 2 and the shield tube 9 separates the heated wind from the burner and the like in the heating path 5. And a conveyor belt 10. The conveyor belt 10 is formed in a structure having liquid permeability using, for example, a ceramic material or the like. The shielding cylinder 9 is formed to have an inverted triangular cross-sectional shape, the lower part of which is a liquid collecting gutter part 11, and a conveyor screw 11 s is arranged in the liquid collecting gutter part 11. The shielding cylinder 9 is
The heat conductivity of the lower part is formed so as to be smaller than the heat conductivity of the upper part. Further, an exhaust pipe 12 for forcibly exhausting a hydrogen chloride gas or the like which causes a dehydrochlorination reaction described later is connected to the shielding cylinder 9. The collecting trough 11 in the shielding tube 9 functions to collect the liquid-phase polymer generated on the conveyor belt 10 and flowing down by the liquid-permeability of the conveyor belt 10 and supply it to the reaction chamber 3 as described later. I do. The supply of the liquid-phase polymer collected in the collecting trough 11 to the reaction chamber 3 is performed by providing an appropriate communication port in the shielding cylinder 9 outside the heating path 5.
It is performed through this communication port.

The dehydrochlorination treatment and the decomposition treatment of waste plastic by such a treatment apparatus are performed as follows. Waste plastic is continuously supplied from the supply hopper H onto the conveyor belt 10. Conveyor belt 10
Is transported inside the shielding tube 9 as the conveyor belt 10 travels as indicated by the arrow X, and during this time, heat energy is supplied from the hot air in the heating path 5 through the shielding tube 9. Heated. Then, the meltable plastic in the waste plastic is melted and liquefied to generate a liquid phase polymer. The produced liquid-phase polymer is separated from the solid matter because the conveyor belt 10 has liquid permeability, and flows down to the lower liquid collecting trough 11. On the other hand, the non-meltable plastic is transported to the tip of the conveyor belt 10 while causing a dehydrochlorination reaction or the like, where it is collected as a solid fuel or the like. Hydrogen chloride gas generated by the dehydrochlorination reaction or the like is recovered by a recovery device (not shown) through a recovery port 14 provided at the end of the inner cylinder 2.

Here, since the shielding cylinder 9 is formed so that the thermal conductivity of the lower part thereof is smaller than the thermal conductivity of the upper part, the dehydrochlorination reaction and the decomposition reaction of the liquid phase polymer are performed as described above. It is possible to carry out efficiently under the same temperature level, that is, high temperature condition. In other words, by setting the upper part to a high thermal conductivity state, the thermal energy for the dehydrochlorination reaction is efficiently supplied to the waste plastic on the conveyor belt 10, while the lower part is set to a low thermal conductivity state, The liquid-phase polymer flowing down from the conveyor belt 10 and collecting in the liquid collecting trough 11 is disassembled into sections S as described later.
Decomposition before undergoing decomposition in a can be prevented.

The liquid phase polymer produced in the pretreatment section Sb in this way is continuously decomposed in the decomposition section Sa.
Is supplied to the reaction chamber 3. In the reaction chamber 3, the liquid-phase polymer is heated while being transported in the direction of arrow Y by the screw structure of the inner cylinder 2, whereby it is decomposed and vaporized. The liquid phase polymer in the degradation section Sa, as seen in FIG.
At the bottom of the reaction chamber 3, a liquid layer L having a shallow liquid depth is formed. In this state, the liquid phase polymer is scraped up by the rotation of the inner cylinder 2. Therefore, the liquid phase polymer is
A thin film F is formed on the outer peripheral surface of the substrate. Then, in the state of the thin film F, the thin film F is heated by the high-temperature hot air of the heating path 5 through the inner cylinder 2 and is decomposed and vaporized. The product generated by this, except for the shallow liquid layer L, fills the entire reaction chamber 3 and is successively guided from the recovery port 8 to a cooling device (not shown), where it is cooled to form fuel oil or fuel gas. Will be collected as On the other hand, the residue that has not been completely decomposed is collected from a discharge port 15 provided in the outer cylinder 4. Whether the liquid-phase polymer is 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.

In the processing apparatus as described above, the outer cylinder 4
It is more preferable that the periphery of the conveyor belt 10 be airtightly covered with a cover housing, and that the high temperature exhaust air from the heating path 5 be passed through the space covered by the cover housing to stabilize the temperature of the reaction chamber 3. . It is also preferable that the outer cylinder 4 can be rotated, so that residues and the like adhering and accumulating on the inner surface of the outer cylinder 4 can be cleaned by rotating the outer cylinder 4 when necessary.

In the above embodiment, the return portion of the conveyor belt 10 passes through the outside of the heating path 5 in the inner cylinder 2. However, the return section instead of this also passes through the inside of the heating path 5. Can also. By doing this,
Residues and the like attached to the return portion can be burned off inside the heating path 5.

[0018]

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 partially cutaway side view schematically showing a main part of a processing apparatus according to an embodiment.

FIG. 2 is an essential part cross-sectional view along the line SA-SA in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conveying blade 2 Inner cylinder 3 Reaction chamber 4 Outer cylinder 5 Heating path 9 Shielding cylinder 10 Conveyor belt Sa Disassembly section Sb Pretreatment section

Claims (2)

[Claims] In a processing method for decomposing waste plastics and recovering them as fuel oil or fuel gas, a conveyor belt having liquid permeability is run in a heated atmosphere, and is continuously placed on the conveyor belt. By heating the waste plastic to be supplied along with the traveling of the conveyor belt, the fusible plastic is melted and liquefied, while the non-fusible plastic is dehydrochlorinated, etc. The liquid polymer produced by the melting and liquefaction was preliminarily treated to be separated from the solid by the liquid permeability of the conveyor belt, and the liquid polymer obtained by the pretreatment was supplied to the decomposition section to be decomposed. A method for treating waste plastic, comprising: 2. A processing apparatus for decomposing waste plastic to recover it as fuel oil, fuel gas, or the like, comprising: an inner cylinder provided with conveying blades on its outer periphery and rotatable; And an outer cylinder forming a reaction chamber between the inner cylinder and a decomposition section configured to supply heating energy to the reaction chamber using the inside of the inner cylinder as a heating path, and a heating section inside the inner cylinder. A pretreatment section comprising a liquid-permeable conveyor belt provided so as to run inside the provided shielding cylinder, and in the pretreatment section, waste disposed continuously on the conveyor belt; By heating the plastic as the conveyor belt travels, the fusible plastic is melted and liquefied, while the non-fusible plastic is removed. In addition to causing a hydrogen chloride reaction and the like, the liquid-phase polymer produced by melting and liquefaction of the fusible plastic is separated from the solid by the liquid permeability of the conveyor belt, and the liquid-phase polymer separated from the solid is separated into the reaction chamber. A waste plastic processing apparatus characterized in that the waste plastic is supplied and decomposed.