JP2895754B2 - Waste plastic processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for thermally decomposing waste plastics, and more particularly to a technology for efficiently recovering a reusable oil component such as fuel oil.

[0002]

2. Description of the Related Art Most of waste plastics are still treated by landfill or incineration. However, while it is becoming increasingly difficult to secure landfill sites and the pollution problems associated with incineration are increasing, the amount of waste plastic is increasing. In such a situation, it has become increasingly important to be able to treat waste plastic by a method that can be reused as a useful resource without reclamation or incineration.

[0003] There have already been many proposals for processing techniques intended for the effective reuse of waste plastics, all of which are designed to thermally decompose waste plastics to recover fuel oil and fuel gas ( For example, JP-A-5-263079, JP-A-5-237467, JP-A-4-180878, JP-A-49-115157, and the like. However, there are some problems with the conventional technology,
The reality is that it has not yet been able to operate at a practical level.

One of the major factors is heating for thermal decomposition. In other words, the properties of oil that can be recovered by thermal decomposition of waste plastics vary greatly depending on the heating temperature. However, uniform heating is difficult due to the problem of thermal conductivity, and uniform heating is difficult. Therefore, the target oil cannot be efficiently recovered.

[0005] Another problem is the problem of carbides generated during heating. That is, the generated carbide serves as a heat insulating material to cause a decrease in heating efficiency, and the excessive mixing of the carbide lowers the quality of the recovered oil, resulting in a combustion problem when this is used as fuel oil.

Another additional factor is that the treatment must be carried out in a state where oily or non-oilable plastics having different decomposition characteristics are mixed. In other words, plastics that are widely used are mainly olefin-based, styrene-based, and vinyl chloride-based plastics, but many of them have different types of plastics with different properties, and they have different oiling conditions. Even if complete oiling is possible by high-temperature cracking, a large amount of carbides are generated, and on the other hand, if the formation of carbides is suppressed, it is unavoidable that unoiled materials and the like remain, but such carbides and unoiled materials It is difficult to control the reaction, and it is difficult to separate and recover non-oilable plastics and carbides, especially when non-oilable plastics are mixed, which is one of the factors that hinders the realization of practical treatment. .

Based on such knowledge, the applicant of the present invention has previously disclosed in Japanese Patent Application No. 5-37403 a granular material having appropriate heat resistance, thermal conductivity and hardness, such as silica sand, as a heating medium. We proposed a technology to thermally decompose waste plastic by using it as a heat storage medium. According to the technology using this granular heating medium, the uniformity of heating is remarkably improved, and the granular heating medium also functions to remove carbide, thereby effectively preventing heat transfer inhibition by the carbide and lowering the quality of the recovered oil. The decomposition efficiency can be increased by using a granular heating medium having a catalytic ability for thermal decomposition, such as silica alumina, for example, so that a highly efficient thermal decomposition treatment can be performed. Further, in this technique, it is relatively easy to treat non-oilable plastics and unoiled substances by using a mixed state with a granular heating medium. As a result, the technology of using the granular heating medium substantially enables the practical use of the effective recycling of waste plastic.

However, there is still room for further improvement in this technology. One of them is the problem of mixed contact between the granular heating medium and the waste plastic, that is, the object to be treated. That is, if the granular heating medium and the object to be treated are mixed and contacted as uniformly as possible and over a large area, the uniformity of heating is increased accordingly, and the heating temperature can be easily controlled, so that a more advanced treatment can be expected. In this regard, the level of the previously proposed technology was still insufficient.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a processing technique for promoting thermal decomposition by performing heating by mixing and heating an object to be processed with a granular heating medium. It is an object of the present invention to provide an improvement in which the contact between the object to be treated and the granular heating medium is made more uniform and in a wider area.

[0010]

For this purpose, the present invention relates to a waste plastic processing apparatus for recovering useful components by thermally decomposing waste plastic while mixing and contacting it with a granular heating medium. Incorporates a pre-processor with built-in transport means capable of agitating and transporting the target object, and a built-in medium holding plate with a processing surface having an appropriate planar spread, and heats the processing surface of the medium holding plate from below. And a main processing unit with a built-in heating chamber for heating the waste plastic. The pre-processed material is supplied to the main processor, and the pre-processed material supplied from the pre-processor is processed on the processing surface of the medium holding plate. It is pyrolyzed by contacting it in a mixed state while scatteredly supplying it to the heating granular heating medium, and the vaporized components generated by this pyrolysis are collected as fuel gas and light oil, etc. Is to be processed with a granular heating medium,
It is based on a waste plastic processing apparatus which recovers useful components by thermally decomposing waste plastic while contacting it with a granular heating medium.

In the main processing unit of the waste plastic processing apparatus according to the present invention, the pretreated material which has been given an appropriate fluidity by the heat treatment by the pretreatment device is mixedly brought into contact with the granular heating medium. Since it is scatteredly supplied to the granular heating medium that is being heated in a state of being spread in a layer with an appropriate thickness on a processing surface having an appropriate planar spread, it will be mixedly contacted, Mixing contact can be made more uniform and over a large area, so that heating can be performed with very high uniformity, that is, with a small temperature gradient, and the heating temperature can be easily controlled.
As a result, it is possible to recover the target oily oil with high efficiency.

[0012] In such a waste plastic processing apparatus, the medium holding plate is formed in a conical shape in which a plurality of holding plates are protruded stepwise at predetermined intervals in a flange shape on the peripheral surface or in a spiral shape on the peripheral surface. It is preferably formed in a protruding conical shape. In this way, it is possible to obtain a processing surface having a large area without significantly increasing the size in the width direction,
Therefore, processing efficiency can be improved. In particular, in a structure in which the holding plate is projected in a spiral shape, the pretreatment material flows down along the spiral holding plate, so that the pretreatment material can be brought into contact with the granular heating medium for a longer time, and thus the heat Decomposition can be performed more efficiently.

In the waste plastic processing apparatus according to the present invention, a spraying means is provided above the medium holding plate.
It is more preferable to supply the pre-processed material to the granular heating medium on the processing surface via the spraying means, since the uniformity of the scattered supply can be improved and the processing efficiency can be improved.

On the other hand, in the waste plastic processing apparatus according to the present invention, the waste plastic is first heated in a mixed state with the granular heating medium in the pretreatment device to be a preprocessed product having an appropriate fluidity. In this case, “appropriate fluidity” generally refers to fluidity that facilitates scattered supply to the granular heating medium in the main processing unit, and has a molecular weight distribution such that the molecular weight distribution includes thousands to hundreds. A state in which a reaction is caused to cause liquefaction is preferable, and thus heating conditions are set.

For the mixing of the granular heating medium and the waste plastic in the pretreatment device, a conveying means capable of agitatingly conveying the object, for example, a screw conveyor or the like is most suitable as such a conveying means. Sufficiently, the heating is performed while applying the conveying force and the stirring force by the conveying means. As a result, the mixed contact between the granular heating medium and the waste plastic can be performed uniformly and over a large area, and the heating can be performed with high efficiency. . Also, heating in the pre-treatment unit may generate a considerable amount of carbide depending on the heating temperature, but this carbide can be dispersed and removed by the individual particles of the granular heating medium, and therefore, the heat transfer inhibition due to the generated carbide is suppressed. This can be effectively prevented, and high heating efficiency can be maintained.

[0016]

An embodiment of the present invention will be described below.
As shown in FIG. 3, the waste plastic processing apparatus according to the present embodiment includes a pre-processing device 1 and a main processing device 2, and a waste plastic to be processed is preliminarily processed in the pre-processing device 1. The raw material is supplied to the main processing unit 2 while being made into a pre-processed product having an appropriate fluidity by appropriate heating, where thermal decomposition for recovering useful oil and the like is performed.

The pre-processor 1 is, as seen in FIG.
It has a pipe structure in which the screw conveyor 3 is built in, and an external heating method in which heating is performed from the outside by an electric heater or the like (not shown) is used for preliminary heating there.

The pretreatment device 1 has an air shutoff hopper 4
A transport duct 6 is connected with a drying hopper 5 interposed therebetween. The waste plastic supplied from the storage facility (not shown) via the transport duct 6 is dried by the drying hopper 5 and is separated from the outside air by the air blocking hopper 4. The cut-off state is sent to the pre-processor 1.

A medium supply mechanism 7 is connected to the drying hopper 5. The medium supply mechanism 7 is for supplying a granular heating medium. The medium heating mechanism regenerated and stored in the medium regeneration processing tank 8 is taken out by the conveyor 9 and supplied from the feeder 10 to the drying hopper 5, where the waste plastic is discharged. To be mixed.

As the granular heating medium, various materials are used according to the kind of waste plastic and the oil quality of the recovered oil, and the particle size is also selected. In particular, when a granular heating medium having a catalytic ability for thermal decomposition, such as a silica-alumina-based one, is used, the granular heating medium can be directly supplied to the main processing unit 2 in order to effectively exert the catalytic ability in the main processing unit 2. The auxiliary feeder 10p is provided on the conveyor 9 as described above. This will be described more specifically below. If the waste plastic contains chlorine-containing plastics, the chlorine gas generated from the waste plastics can easily deactivate the catalytic activity of the silica-alumina system. Almost no chlorine gas is generated from the pre-processed material supplied from 1 to the main processor 2. In other words, in the treatment in the pretreatment device 1, the catalytic activity of the granular heating medium is deactivated, but the main treatment device 2
Does not substantially deactivate the catalytic ability of the granular heating medium due to chlorine gas. Therefore, a fresh granular heating medium is directly supplied from the auxiliary feeder 10p to the main processing unit 2 so that the catalytic activity is effectively exerted in the main processing unit 2.

As shown in FIG. 1, the main processing unit 2 includes a medium holding plate 1 inside a reaction tank 11 formed in a sealed state.
2. A scraping means 13, a heating chamber 14, and a spraying means 15 are provided, and a collection duct 16 for collecting vaporized components is connected to the top end of the reaction tank 11, as shown in FIG. A medium recovery mechanism 17 for recovering the granular heating medium together with the non-vaporized components is connected to the lower end of the medium.

The medium holding plate 12 has a conical shape as a whole, and a holding plate 18 is provided on a peripheral surface 12f thereof at regular intervals.
Are formed in a flange-like manner and are protruded step by step at predetermined intervals. Each holding plate 18 holds a granular heating medium P using silica-alumina-based particles in a layer having a thickness of about several centimeters. (FIG. 2). In other words, in the medium holding plate 12, the peripheral surface 12f of the conical body with which the layer of the granular heating medium P contacts within the range of the angle of repose and the upper surface of each holding plate 18 become the "processing surface", and have a relatively large area. A "processing surface" can be obtained. The holding plate 18 may be provided with a "sand stopper" having a height of, for example, about 0.3 to 3 cm on the outer peripheral edge thereof, if necessary, in consideration of conditions such as the fluidity of the pretreatment material. .

The scraping means 13 cross-links the granular heating medium P held by the medium holding plate 12 due to the adhesion of carbides or unoiled components, and scrapes the cross-linked granular heating medium P at an appropriate time. It is for dropping. Specifically, a plurality of scraping blades 13 are
The scraping arm 13a provided with w is driven by driving means 23 (FIG. 3).
And is attached to the tip of a rotating shaft 13s that is driven to rotate by the rotation of the rotating shaft 13s.
a moves around the medium holding plate 12 and
At 3w, the granular heating medium P in each holding plate 18 is scraped off.

The heating chamber 14 is formed in a closed structure with the medium holding plate 12 as its upper lid, and the medium holding plate 12 can be heated from below by a burner 19 provided therein. The combustion exhaust of the exhaust stack 20
Through the reaction tank 11. However, the burner 19 is provided outside if necessary,
Even if the hot air obtained thereby is supplied to the heating chamber 14, there is no substantial difference from the present structure. The connection between the heating chamber 14 and the medium holding plate 12 is made by fitting the skirt portion 22 of the medium holding plate 12 into the receiving groove 21 provided at the top end of the heating chamber 14. The gap is filled with sand for sealing.

The spraying means 15 has a structure in which a spraying disk 25 is attached to the tip of a rotating shaft 15s which forms a double axis with the rotating shaft 13s of the scraping means 13 and is driven to rotate by a common driving means 23. . The spraying plate 25 is formed in a dish shape having a moderate internal inclination, and is provided with a large number of small through holes (not shown) on the entire surface thereof. While spreading with rotation,
The granular heating medium P in the medium holding plate 12 is supplied from the many through-holes in a uniform scattered state. At this time, most of the low-viscosity and high-fluidity components in the pre-processed material are supplied to the medium holding plate 12 through the through holes at the positions where they fall from the pre-processing device 1 to the spraying plate 25. The high-viscosity, low-fluidity component is spread over the through hole at the drop position because of the low fluidity.
Easily gather at the center along the internal inclination of the medium holding plate 12 and flow down to the top end of the medium holding plate 12 therefrom. Therefore, the higher the viscosity component, the longer the residence time in the medium holding plate 12 on average. That is, the spraying plate 25 functions so as to screen the low-viscosity component and the high-viscosity component by its internal inclined structure, so that the higher the viscosity component, the longer the average residence time in the medium holding plate 12 is given. . As a result,
High viscosity components can be sufficiently decomposed, and high decomposition efficiency can be obtained as a whole.

The treatment of waste plastic by the waste plastic treatment apparatus as described above is performed as follows. As described above, the waste plastic supplied from the storage facility (not shown) via the transport duct 6 is first treated with the pretreatment device 1.
A pre-processed product is obtained by the process in. The treatment in the pre-treatment device 1 is performed by heating the waste plastic in the mixed state with the granular heating medium mixed in the drying hopper 5 as described above while giving the conveying force and the stirring force by the screw conveyor 3. Heating temperature is 350-5
00 ° C. The waste plastic that has been treated by the pretreatment device 1 becomes a liquefied pretreatment product having a molecular weight distribution of about several thousands to several hundreds.

In the main processor 2, the pre-processed material from the pre-processor 1 is sprayed in a mixed state with the granular heating medium.
5, the granular heating medium P in the medium holding plate 12 is scatteredly supplied from above. The pre-processed material supplied in this manner is heated while being brought into contact with the granular heating medium P being heated by the medium holding plate 12 in a mixed state, thereby causing thermal decomposition. In this case, the mixed contact between the pre-processed material and the granular heating medium P is in a state where the pre-processed material having liquefaction and appropriate fluidity enters the gaps between the granular heating media, that is, the pre-processed material is thinned. Made in state. Therefore, heating with a high heating efficiency and a small temperature gradient can be performed, and the pyrolysis temperature can be freely controlled, and highly efficient pyrolysis can be performed.

The vaporized components generated by the thermal decomposition are collected in the recovery duct 16.
And then cooled and recovered as light oil. On the other hand, the non-vaporized component flows down to the lower part of the reaction tank 11 through the flow-down passage provided around the heating chamber 14 together with the granular heating medium P, and the oil-forming component contained therein flows into the medium recovery mechanism 17 in the heavy oil component. And the unoiled component contained therein is subjected to a treatment accompanying the regeneration treatment of the granular heating medium P.

Along with this recovery, most of the vaporized components are collected in the recovery duct 16 while being in contact with the inner peripheral surface of the reaction tank 11. As a result, components having a certain molecular weight or more are condensed and adhere to the inner peripheral surface of the reaction tank 11. Then, the liquefied component flows down along the inner peripheral surface of the reaction tank 11 and merges with the non-vaporized component to be recovered as heavy oil. That is, by controlling the temperature of the inner peripheral surface of the reaction tank 11, control of the composition of the light oil and control of the ratio of light to heavy in the recovered oil can be additionally performed. For the temperature control for this purpose, for example, the peripheral wall of the reaction tank 11 has a double structure with a gap,
This can be performed by passing the exhaust gas from the heating chamber 14 through the gap between the peripheral walls of the double structure while controlling it with a damper or the like.

FIG. 4 shows a medium holding plate 3 according to another example.
0, which is basically the same as the medium holding plate 12 described above, except that a spiral holding plate 31 is provided on the peripheral surface 30f. In the case of this helical holding plate 31, the pre-processed material supplied from the pre-processing device 1 flows down along the holding plate 31, so that it comes into contact with the granular heating medium for a longer time, Generates thermal decomposition efficiently.

[0031]

As described above, according to the present invention, the waste plastic is thermally decomposed while being mixedly contacted with the granular heating medium so that a uniform contact with the granular heating medium over a wide area can be obtained. Therefore, heating with high efficiency and a small temperature gradient can be performed, and free control of the thermal decomposition temperature becomes possible. As a result, according to the present invention, high value-added oil components can be recovered with high efficiency while controlling the oil quality of the recovered oil, and the practical reuse of waste plastic can be realized.

[Brief description of the drawings]

FIG. 1 is a side view including a partial cross section schematically showing a main part of a waste plastic processing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a holding state of a granular heating medium in a medium holding board.

FIG. 3 is an overall configuration diagram of a waste plastic processing apparatus according to an embodiment of the present invention.

FIG. 4 is a side view of a medium holding plate according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pre-processing unit 2 Main processing unit 3 Screw conveyor (conveying means) 12, 30 Medium holding plate 14 Heating chamber 15 Spraying means 18, 31 Holding plate P Granular heating medium

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C10G 1/10 B09B 3/00 B29B 17/00 C08J 11/12 C10J 3/00

Claims (3)

(57) [Claims] 1. A built-in pre-processing device having a transport means capable of agitatingly transporting an object, and a media holding plate having a processing surface having an appropriate planar spread, and the medium holding plate is mounted from below. A main processing unit having a built-in heating chamber for heating, wherein the waste plastic is mixed with the granular heating medium and heated by applying a conveying force and a stirring force by a conveying means in a pre-processing device. A pre-processed material having fluidity, and the pre-processed product is supplied to the main processor,
In the main processor, pyrolysis is performed by contacting the pre-processed material supplied from the pre-processor in a mixed state while scatteredly supplying it to the granular heating medium being heated on the processing surface of the medium holding plate The vaporized components generated by this thermal decomposition are collected as fuel gas or light oil, and the non-vaporized components are processed together with the granular heating medium.
This is a waste plastic treatment device that collects useful components by thermally decomposing waste plastic while contacting it with a granular heating medium.A plurality of holding plates are protruded stepwise at predetermined intervals in a flange shape on the peripheral surface. A waste plastic processing apparatus in which a medium holding plate is formed in a conical shape or a conical shape in which a holding plate is helically protruded on a peripheral surface. 2. The waste plastic processing apparatus according to claim 1, wherein the conveying means of the pretreatment device is formed by a screw conveyor. 3. The method according to claim 1, wherein a spraying means is provided above the medium holding plate, and the pretreated material is supplied to the granular heating medium on the processing surface via the spraying means. 2. The waste plastic processing apparatus according to claim 1.