JPH09302136A - Decomposition treatment of synthetic resin and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the disposal of residue and improve energy efficiency and monomer extraction efficiency by setting the temperature of the upper part of a decomposition furnace to a 1st temperature to proceed the decomposition reaction of a synthetic resin and setting the lower part of the furnace to a 2nd temperature higher than the 1st temperature, thereby efficiently performing the decomposition treatment of the synthetic resin. SOLUTION: Decomposition treatment of a synthetic resin is carried out by setting the temperature of the upper part of a decomposition furnace 10 to a 1st temperature (280-350 deg.C) to proceed the decomposition of a synthetic resin such as styrol resin and setting the temperature of the lower part of the decomposition furnace to a 2nd temperature (380-430 deg.C) higher than the 1st temperature. The decomposition furnace 10 is provided with an upper heating part 12 and a lower heating part 14 having independently controllable heating temperatures and connected with each other. The lower heating part 14 is provided with a closable residue-discharging port 14d.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for decomposing a synthetic resin, and more particularly to a method for treating a synthetic resin in a reusable manner by heating a styrene resin or the like to decompose it into a monomer. Disassembly processing technology.

[0002]

2. Description of the Related Art Conventional methods for treating synthetic resins are generally crushed and landfilled as it is, or incinerated in an incinerator, but these methods have a negative effect on the environment due to landfilling or incineration. And the residue remains semipermanently.

Therefore, in recent years, various synthetic resin treatment methods have been proposed in consideration of recycling of synthetic resins. Some of these treatment methods use modified synthetic resins to use them as other industrial raw materials, but the most direct and essential method is to decompose the synthetic resins into the original monomers so that they can be reused. Is the way to do it.

As a decomposition treatment method for decomposing a synthetic resin into a monomer, for example, after dissolving the synthetic resin in a solvent,
There are a decomposition treatment method using a solvent for distilling the monomer to extract the monomer, and a direct decomposition treatment method for directly introducing the synthetic resin into a decomposition furnace, heating and dissolving it, and extracting the monomer from the evaporated component.

[0005]

Among the above-mentioned conventional decomposition treatment methods, in the treatment method using a solvent, it is necessary to use a large amount of solvent for extracting the monomer, and the resin dissolved in this solvent is distilled. There is a problem that a large amount of energy is required for taking out and energy efficiency is low, and moreover, there is a problem that the installation area increases due to the need for solvent circulation equipment and the like.

On the other hand, in the direct decomposition method, there is a problem in that the extraction efficiency of the monomer is low because a polymerization reaction occurs by heating and many portions cannot be taken out as a monomer.

Further, in any of the above decomposition treatment methods, there is a problem that the extraction efficiency of the monomer is not sufficient, the treatment cost is relatively high, and the price of the regenerated monomer is high. Further, in any of the methods, residues are accumulated in the decomposition furnace, and the residue adheres to the furnace wall, which makes it difficult to clean the decomposition furnace, and as a result, the processing cost is further increased. is there.

Therefore, the present invention solves each of the problems described above, and the problem is to provide a novel decomposition treatment method which can improve energy efficiency, monomer extraction efficiency, and facilitate residue treatment. It is to provide a decomposition processing apparatus.

[0009]

Means for Solving the Problems The means taken by the present invention to solve the above-mentioned problems are as follows: in the method for decomposing a synthetic resin, which comprises treating a synthetic resin by heating and decomposing it in a decomposition furnace, The upper part of the furnace is set to a first temperature at which the decomposition reaction of the synthetic resin proceeds, and the lower part of the decomposition furnace is set to a second temperature higher than the first temperature to perform the decomposition process. It is a thing.

According to this means, the lower part of the cracking furnace is set at a higher temperature than the upper part thereof to suppress the production of high polymer in the upper part of the cracking furnace, and to raise the temperature in the lower part of the cracking furnace and to decompose it by convection. By moving the product to the upper part to lower the ratio of the decomposition product and accelerate the decomposition reaction, it is possible to improve the recovery rate of the decomposition product as compared with the conventional one, and to increase the degree of polymerization Since the residue can be accumulated in the lower part, the residue can be easily removed.

Here, the synthetic resin is a styrene resin, and the first temperature is within a range of about 280 to 350 ° C.
The second temperature is preferably set within the range of about 380 to 430 ° C. By setting this temperature range,
The recovery rate of styrene monomer can be 90 wt% or more.

Next, in a decomposition treatment apparatus for a synthetic resin, which treats a synthetic resin by heating it in a decomposition furnace to decompose it into monomers, the decomposition furnace is constructed so that the heating temperature can be set independently. And an upper heating part and a lower heating part which are in communication with each other.

Here, it is preferable that the lower heating section is provided with an openable residue outlet. According to this means, it is possible to easily remove the residue accumulated in the lower heating section.

In this case, it is preferable that the residue take-out port is formed on the bottom surface of the lower heating unit so as to have an opening cross section that is substantially the same as the horizontal cross section of the lower heating unit. According to this means, it is possible to easily clean the inner wall of the lower heating section from the residue outlet.

Further, it is preferable that the diameter of the lower heating portion is smaller than the diameter of the upper heating portion, and the step between the upper heating portion and the lower heating portion is inclined. According to this means, the removal volume of the residue can be reduced by reducing the diameter of the lower heating portion on which the residue is deposited without reducing the capacity of the decomposition process. Moreover, since the step portion is formed to be inclined, it is possible to smoothly guide the residue generated in the upper heating portion to the lower heating portion.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the method and apparatus for decomposing a synthetic resin according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a schematic configuration of a decomposition processing apparatus according to the present invention. The device of this embodiment is
A decomposition furnace main body 10 including an upper heating part 12 and a lower heating part 14, a resin charging part 20 for charging crushed resin into the decomposition furnace main body 10, and a vaporized component generated from the decomposition furnace main body are cooled and recovered. The resin recovery unit 30 composed of a condenser or the like configured as described above, a stirring mechanism 40 for stirring the molten resin inside the decomposition furnace main body 10, and a residue extraction port (described later) provided at the bottom of the decomposition furnace main body 10 are opened and closed. And a bottom opening / closing mechanism 50 for operating.

The decomposition furnace main body 10 includes a metal frame 11
It is supported by a heat insulating material. Frame 11
Is an upper vertical portion 11a that extends upward around the upper heating portion 12 and a horizontal support portion 11b that is connected to the upper vertical portion 11a and that extends inward and supports a step portion 13 described later via a heat insulating material. And this horizontal support 11
and a lower vertical portion 11c that supports the lower heating portion 14 from the surroundings.

Inside the frame 11, there is a large-diameter furnace wall 12
A furnace body made of stainless steel having an upper heating part 12 provided with a and a lower heating part 14 provided with a small-diameter furnace wall 14a configured to communicate with the lower part of the upper heating part 12 is supported. There is. A heater 12b is attached around the upper heating portion 12, and the outside of the heater 12b is covered with a heat insulating material 12c. Upper heating part 12
Is formed between the lower heating section 14 and the lower heating section 14, and the step section 13 forms the furnace wall 12a of the upper heating section 12 and the furnace wall 14a of the lower heating section 14 in the same surface shape as the inner surface of the cone. It is connected by the inclined surface.

The outside of the step portion 13 is supported by the horizontal support portion 11b of the frame 11 via a heat insulating material. Further, a heater 14b surrounds the lower heating section 14, and its outside is covered with a heat insulating material 14c. A lower side of the lower heating unit 14 is opened to form a residue outlet 14d, and the bottom plate 51 closes the residue outlet 14d during the decomposition process.

Various auxiliary equipments are attached to the decomposition furnace main body 10. A top plate 15 is attached on the upper heating section 12, and the top plate 15 is provided with a plurality of openings. The injection pipe 25 of the resin injection unit 20 described above is attached to one of these openings. Resin injection part 20
Then, as shown in FIG. 5, the crushed resin conveyed from the resin crusher (not shown) by the horizontal conveyor 26 is transferred upward by the vertical lift 27, and is transferred into the receiving pipe 21 installed above the decomposition furnace main body 10. It is supposed to be thrown in. As shown in FIG. 1, the receiving pipe 21 is connected to a feeding pipe 25 via a transfer box 22 extending in the horizontal direction.

Here, the receiving pipe 21 and the feeding pipe 25 are formed such that their axes are horizontally displaced from each other. A transfer piston 23 is accommodated inside the transfer box 22 so as to be movable in the horizontal direction, and a drive cylinder 24 for moving the transfer piston 23 in and out is provided. The drive cylinder 24 causes the transfer piston 23 to project, pushes out the crushed resin that has been charged into the receiving pipe 21 and accumulated inside the transfer box 22, and causes the crushed resin to drop from the upper opening of the charging pipe 25 into the decomposition furnace body 10.

On the other hand, the exhaust pipe 31 of the above-mentioned resin recovery section 30 is connected to another opening formed in the top plate 15. In the resin recovery unit 30, as shown in FIG. 5, an exhaust pipe 31 is connected to a primary cooling tower 32, and this primary cooling tower 32 is further connected to a secondary cooling tower 34 via a connecting pipe 33. There is. Both the primary cooling tower 32 and the secondary cooling tower 34 are known condensers that cool the gas introduced from the exhaust pipe 31 through a cooling pipe arranged in a cooling water tank and liquefy the gas to take it out.

The liquid outlets of the primary cooling tower 32 and the secondary cooling tower 34 are both connected to the drain pipe 35. Drain pipe 35
Is connected to a gas separation pipe 36, and an exhaust filter 37 is connected to the gas separation pipe 36. The drain pipe 35 is separated from the gas separation pipe 36, and is then bent downward in a U-shape to form a U-shaped portion 3.
It opens to the collection tank 39 through 8.

A bearing body 41 is attached to the center of the top plate 15 of the decomposition furnace main body 10, and an agitating shaft 42 is inserted vertically inside the bearing body 41. The stirring shaft 42 is rotatably supported up and down and rotatable about its axis, and a stirring blade 43 is attached to the lower end thereof. The upper end of the stirring shaft 42 is connected to a drive motor 44, and the stirring blade 43 is rotated by the drive motor 44.

The drive motor 44 includes a pair of lift guides 45,
It is provided with a nut (not shown) which is guided vertically along 45 and is screwed into the feed screw 46, and the drive motor 44 is moved up and down by rotating the feed screw 46 or the nut by a drive mechanism (not shown). With this configuration, the stirring blade 43 causes the decomposition furnace main body 1 to
It is configured so that it can be moved up and down inside 0.

In the bottom opening / closing mechanism 50, the bottom plate 51 that closes the residue outlet 14d of the lower heating unit 14 is configured to be slidable in the horizontal direction with respect to the lower heating unit 14.
A drive arm 52 for moving 1 in the horizontal direction and a drive cylinder 53 for moving the drive arm 52 in and out are provided. The drive arm 52 is supported by a guide table installed on the floor.

On the side of the bottom plate 51 opposite to the mounting portion of the drive arm 52, the residue discharge port 14 of the lower heating unit 14 is provided.
Gripping portion 54 for sandwiching the opening edge portion and the edge portion of the bottom plate 51
And a clamp mechanism 55 for opening and closing the grip portion. When the clamp mechanism 55 operates, the grip portion 54 is driven in the closing direction to fix the bottom plate 51 to the opening edge portion of the residue outlet 14.

In this apparatus, as shown in FIG. 1, the crushed resin charged from the receiving pipe 21 is repeatedly extruded by the transfer piston 23 into the charging pipe 25 to deposit the crushed resin in the furnace. The decomposition furnace main body 10 is heated in advance or after the crushed resin is accumulated to some extent in the furnace, then the heaters 12b, 1
The crushed resin is gradually melted by being heated by 4b. While melting the crushed resin, transfer piston 2
A new crushed resin is charged into the furnace by the reciprocating motion of 3, and the liquid level of the molten resin is raised to a relatively upper part of the upper heating part 12 as shown in FIG.

Here, as shown in FIG. 2, the transfer piston 23 closes the charging path of the resin charging section 20 including the receiving tube 21, the transfer box 22 and the charging tube 25 when the crushed resin is pushed out into the charging tube 25. Therefore, new crushed resin can be appropriately charged even during the decomposition process described later, and the reverse flow of steam from the inside of the decomposition furnace main body 10 can be almost prevented.

Next, the operation after charging the crushed resin into the decomposition furnace body 10 and heating it to a molten state will be described.
When the crushed resin is a styrene resin, a part of the crushed resin is decomposed into styrene monomer in the molten state. This styrene monomer is vaporized and guided from the exhaust pipe 31 to the primary cooling tower 32 shown in FIG. 5, where it is cooled, condensed, and liquefied.

The styrene monomer that has not been liquefied in the primary cooling tower 32 is liquefied in the secondary cooling tower 34 and is drained together with the styrene monomer liquefied in the primary cooling tower 32.
It is recovered in the recovery tank 39 via 5. Secondary cooling tower 34
Even in the above, the component that is not liquefied is discharged from the gas separation pipe 36 before the U-shaped portion 38 where liquid (monomer) always exists, and is discharged to the outside through the filter 37. The U-shaped portion 38 is configured so that the unliquefied gas does not reach the recovery tank 39. The styrene monomer thus recovered can be reused as a raw material of expanded polystyrene, styrene resin or the like, or as a liquid fuel.

The styrene resin charged as a crushed resin inside the decomposition furnace main body 10 is melted by being heated in the furnace, and the decomposition reaction shown in the following chemical formula 1 and the polymerization reaction shown in the chemical formula 2 below. Cause

[0033]

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[0034]

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Here, in order to make the reaction rate of the decomposition reaction shown in Chemical formula 1 for decomposing the polymer into monomers higher than the reaction rate of the polymerization reaction shown in Chemical formula 2 to accelerate the production of the monomer, It is necessary to raise the temperature. But,
As the furnace temperature rises, the polymerization reaction shown in Chemical formula 2 also proceeds, and a highly viscous liquid (black liquid) having a high degree of polymerization is produced.
Once this liquid is produced, it becomes difficult to vaporize it and it is impossible to decompose it again into monomers, so it is difficult to increase the yield of styrene monomer above a predetermined ratio, and to some extent. It also takes longer to obtain the yield of.

In the present embodiment, the upper heating section 12 and the lower heating section 14 are configured in two stages so that the temperature can be controlled independently of each other, and the temperature of the lower heating section 14 is controlled to be higher than that of the upper heating section 12. I chose In this case, the upper heating unit 12
In the above, since the decomposition reaction is promoted by the vaporization of the styrene monomer rather than the polymerization reaction, the yield does not decrease even if the temperature is suppressed to some extent, and the generation of the above-mentioned liquid having a high polymerization degree can be suppressed.

On the other hand, in the lower heating section 14, the temperature is raised to increase the reaction rate, and the styrene monomer obtained by the decomposition reaction is preferentially raised by convection due to its low specific gravity, and the upper heating section 12 is heated. Since it moves and vaporizes, the component ratio of the monomer in the lower heating section 14 decreases, and as a result, the decomposition reaction shown in Chemical formula 1 is promoted more than the polymerization reaction shown in Chemical formula 2.

As described above, in the decomposition treatment method of this embodiment, the decomposition reaction is promoted in both the upper part and the lower part of the decomposition furnace more than before, and as a result, the recovery rate of the styrene monomer can be dramatically increased. It became possible. For example, by setting the set temperature of the upper heating unit 12 in the range of 280 to 350 ° C and the set temperature of the lower heating unit 14 in the range of 380 to 430 ° C, the final recovery rate is 96 wt%.
By optimizing the temperature conditions as described above, 9
It could be 8-99.2 wt%. This recovery rate is 10 wt% or more higher than the conventional value.

In the above decomposition step, the lower heating unit 1
By setting the temperature of No. 4 higher than that of the upper heating unit 12, convection that rises from the lower heating unit 14 to the upper heating unit 12 is generated as shown in FIGS. 1 and 2, and vaporization of the monomer is promoted. Although it works as described above, the stirring blade 43 is further rotated to stir the molten resin in the lower heating section 14, thereby promoting the movement of the decomposed monomer to the upper heating section 12. This stirring action also has the effect of preventing the residue from adhering to the furnace wall 14a.

As shown in FIG. 3, the stirring blade 43 retreats upward due to the rise of the drive motor 44 at a predetermined point in time when the disassembling process proceeds, so as not to damage the stirring blade 43 when a large amount of residue adheres. It is configured. Even if there is not much adhesion of the residue, the stirring blades 43 are retracted upward to prevent sticking when the heating of the lower heating unit 14 is stopped.

In the decomposition treatment apparatus of this embodiment, since the set temperature of the upper heating section 12 is relatively low, the polymerization reaction does not easily proceed in the upper heating section 12, and the sedimentation action by gravity is also assisted. As a result, the amount of residue attached is small. Further, even if a residue is generated, the liquid level of the molten resin may decrease as the recovery progresses.
It hardly adheres to 2a, and most of it deposits on the lower heating part 14 through the step part 13. Here, the step portion 13 is formed as an inclined surface so that the residue generated in the upper heating portion 12 can be smoothly guided to the lower step portion 14.

Since the lower heating section 14 has a relatively high set temperature, a certain amount of highly polymerized substances is unavoidable, and residues are accumulated in the crushed resin that has been charged, so that residues are accumulated. Attach to the inner surfaces of the furnace wall 14a and the bottom plate 51. When the recovery step is almost completed, as shown in FIG. 3, most of the residue is concentrated and deposited in the lower heating section 14.

Here, since the upper heating section 12 is formed to have a large diameter and the lower heating section 14 is formed to have a small diameter, the volume of the portion for removing the residue will be described below without reducing the capacity of the decomposition treatment. In addition, since the step portion 13 is formed as an inclined surface as described above, the residue generated in the upper heating portion 12 can be accumulated in the lower heating portion 14.

In order to remove this residue, first, after releasing the grip portion 54 by the clamp mechanism 55, the drive cylinder 53 is operated to move the bottom plate 51 in the horizontal direction. At this time, the residue adhering to the bottom plate 51 was removed by the lower heating unit 1.
It is removed to some extent by the opening edge portion of the residue removal port 14d of No. The bottom plate 51 is moved to the maximum extent to completely open the residue outlet 14d, and then the grinder 56 is inserted into the residue outlet 14d to scrape off the residue. In the present embodiment, the residue outlet 14d is formed in a circular opening shape having substantially the same diameter and shape as the horizontal cross section of the lower heating section 14, so that the residue can be easily removed with a grinder 56 or the like. You can

[0045]

As described above, according to the present invention, by setting the temperature of the lower part of the decomposition furnace to be higher than that of the upper part of the decomposition furnace, it is possible to suppress the formation of high polymer in the upper part of the decomposition furnace and to suppress the formation of high polymer in the lower part of the decomposition furnace. By increasing the temperature and moving the decomposition products to the upper part by convection to lower the ratio of the decomposition products and accelerate the decomposition reaction, the recovery rate of the decomposition products can be improved as compared with the conventional case. At the same time, the highly polymerized product and other residues can be accumulated in the lower portion, so that the residues can be easily removed.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of an apparatus showing an embodiment of a method for disassembling a synthetic resin and a disassembling apparatus according to the present invention.

FIG. 2 is an enlarged vertical cross-sectional view showing a state at the beginning of the decomposition processing step in the same embodiment.

FIG. 3 is an enlarged vertical cross-sectional view showing a state at the end of the decomposition processing step in the same embodiment.

FIG. 4 is a partial vertical cross-sectional view showing a state of residue treatment in the same embodiment.

FIG. 5 is a schematic configuration diagram showing an overall schematic configuration of the same embodiment.

[Explanation of symbols]

 10 Decomposition furnace main body 11 Frame 12 Upper heating part 13 Step part 14 Lower heating part 15 Top plate 20 Resin input part 21 Receiving pipe 22 Transfer box 23 Transfer piston 24 Drive cylinder 25 Input pipe 30 Resin recovery part 31 Exhaust pipe 32 Primary cooling Tower 34 Secondary cooling tower 35 Drainage pipe 36 Gas separation pipe 38 U-shaped section 39 Recovery tank 50 Bottom opening / closing mechanism 51 Bottom plate 52 Drive arm 53 Drive cylinder 54 Grip 55 Clamp mechanism 56 Grinder

Claims (6)

[Claims] 1. In a method for decomposing a synthetic resin, which comprises treating a synthetic resin by heating and decomposing it in a decomposition furnace, the upper part of the decomposition furnace is set to a first temperature at which a decomposition reaction of the synthetic resin proceeds. At the same time, the decomposition treatment method of the synthetic resin is characterized in that the decomposition treatment is performed by setting the lower part of the decomposition furnace to a second temperature higher than the first temperature. 2. The synthetic resin according to claim 1, wherein the synthetic resin is a styrene resin, and the first temperature is about 280 to 350 ° C.
The second treatment temperature is set in the range of about 380 to 430 ° C., and the synthetic resin decomposition treatment method is characterized in that: 3. A decomposition treatment apparatus for a synthetic resin, which treats a synthetic resin by heating and decomposing it in a decomposition furnace, wherein the decomposition furnace is configured so that the heating temperature can be set independently and is in communication with each other. An apparatus for decomposing synthetic resin, comprising an upper heating section and a lower heating section. 4. The apparatus for decomposing synthetic resin according to claim 3, wherein the lower heating unit is provided with a residue outlet that can be opened and closed. 5. The residue removal port according to claim 4,
An apparatus for decomposing synthetic resin, characterized in that the bottom surface of the lower heating unit is formed to have an opening cross section that is substantially the same as the horizontal cross section of the lower heating unit. 6. The structure according to claim 3, wherein the diameter of the lower heating portion is smaller than the diameter of the upper heating portion, and the step between the upper heating portion and the lower heating portion is inclined. An apparatus for disassembling a synthetic resin, characterized by: