JP3288164B2 - Waste plastic pyrolysis 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 pyrolysis apparatus for waste plastics, and more particularly to a pyrolysis apparatus for pyrolyzing waste plastics to recover fuel oil.

[0002]

2. Description of the Related Art As a method of treating waste plastic,
For a long time, a technology for reducing the volume by heat treatment and a technology for incineration have been known. When waste plastics, especially vinyl chloride resin, are thermally decomposed, residues are generated in the apparatus.
In addition, from the viewpoint of effective use of resources, recently, not only reducing the volume of plastic itself discarded as garbage, but also recycling it as fuel oil has been attracting attention. Sticky or particulate residue is formed in the tank. Therefore, it is necessary to scrape out the residue after the heat treatment. In particular, in the case of batch processing, the operation of the equipment must be stopped during the work of writing out the residue. Is severely restricted.

[0003]

However, in recent years, it has become difficult to secure treatment facilities such as a final disposal site, and waste disposal has become a major social problem. In such a situation, there is an urgent need to increase the processing capacity of the decomposer so that waste plastic can be efficiently recycled. In addition, the scraping operation in the disassembling tank is not easy, and there is a great possibility that the worker's health is impaired by dust or the like.

[0004] The present invention has been made in view of such conventional problems, and can efficiently decompose and recycle waste plastic and treat the residue, and can easily treat the residue. It is an object of the present invention to provide a pyrolysis apparatus.

[0005]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies. As a result, the use of a double-tank type pyrolysis apparatus enables efficient and easy treatment of residues. It has been found that the efficiency of thermal decomposition is improved by providing the corresponding heat transfer sections in two tanks, and the inventors have invented the thermal decomposition apparatus of the present invention.

The pyrolysis apparatus of the present invention is a pyrolysis apparatus for recovering fuel oil by pyrolyzing waste plastic, and comprises an outer tank heated by a heating means, and a waste plastic that can be taken in and out of the outer tank. An inner tank for housing the outer tank, wherein the outer tank has a heat conducting part for increasing heat conductivity from the outer tank to the inner tank in close contact with the inner tank surface during heating.

Further, when the heat conducting portion is formed by a cylindrical partition plate having an inner diameter D, and the inner tank is formed by a cylindrical container having a diameter d, d / D is 0.7 <d / D ≦ Set to 0.98.

[0008]

The inner tank containing the waste plastic is placed in the outer tank, and the surface of the inner tank is in close contact with the heat conducting portion of the outer tank. The outer tank is heated by the heating means, heat is transferred with high thermal conductivity from the outer tank to the inner tank through the heat conducting portion, and the inner tank is heated to thermally decompose waste plastic. After the decomposition, the inner tank is taken out of the outer tank, and the residue is removed from the inner tank.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The thermal decomposition apparatus is of a batch processing type and includes a decomposition tank for storing waste plastic, and a heating means for heating the decomposition tank for thermally decomposing the waste plastic in the decomposition tank. A recovery unit is provided for recovering the fuel oil gas generated by the decomposition as liquid fuel oil by a process such as cooling.

The decomposition apparatus according to the present invention is characterized in that the decomposition tank has a double structure. That is, the decomposition tank is composed of an outer tank and an inner tank that can be separated from each other, the outer tank is directly heated by the heating means, and the inner tank stores waste plastic and is set in the outer tank. After the thermal decomposition of the waste plastic, the inner tank is drawn out of the outer tank together with the decomposed plastic residue, and the residue is scraped out. During that time, new waste plastic stored in another inner tank is introduced into the outer tank and decomposed by heating. Furthermore, in the present invention, in order to improve the efficiency of heat conduction from the outer tank to the inner tank, the outer tank is provided with a heat conducting portion that is in close contact with the surface of the inner tank when heated, and the surfaces of the outer tank are provided with each other. The heat is directly transmitted by the contact of the metal, and heat conduction is facilitated. The heat conducting part is devised so that the inner tank is heated from below to perform the thermal decomposition appropriately.

Hereinafter, the present invention will be described in more detail using embodiments with reference to the drawings. As shown in FIGS. 1 and 2, the thermal decomposition apparatus includes an inner tank 1 and an outer tank 3. The inner tank 1 in this embodiment has a cylindrical side wall 1a and a circular bottom 1b. The inner tank 1 is provided with a transport hook or handle (not shown). The inner tank 1 is transported using a jib crane 5, and the outer tank 3 has a hatch 7 at the top which is opened and closed to introduce the inner tank 1 into the outer tank 3. As shown in FIG. 2, a cylindrical concave portion 3b is formed at the center of the partition plate 3a of the outer tank 3, and the inner tank 1 is fitted therein. A combustion chamber 9 is formed integrally with a partition plate 3a at a lower portion of the outer tub 3 and the outer tub 3 including the partition plate 3a is heated by combustion by a burner 11 installed in the combustion chamber 9. At the time of heating, the heat of the partition plate 3a is transmitted to the inner tank 1 through a portion of the inner tank 1 that contacts the recess 3b.

Further, temperature detectors 13a and 13b for detecting the temperatures inside the inner tank 1 and the outer tank 3 are introduced into the outer tank 3 through the hatch 7 and the outer tank wall. A temperature control calculator 15 for controlling the heating amount of the burner 11 using the temperature detected by the temperature detector 13 as a control variable is connected to the temperature detector 13 and the burner 11.

A pipe 15 for delivering gaseous fuel oil generated by decomposition of waste plastic to the outside of the outer tank 3.
Is connected to the outer tank 3, and a flow rate detector 17 for detecting the fluid flow rate of the pipe 15 is attached as shown in FIG. Further, a control valve 19 for adjusting the flow rate is provided in the pipe 15.
Is provided, and is configured to be controlled by the flow rate control calculator 21 using the flow rate detected by the flow rate detector 17 as a control variable. Further, a pressure detector 23 for detecting a gas pressure in the outer tank 3 is attached.

Further, the pipe 15 is connected to an exhaust gas treatment device 29 through a primary condenser 25 and a secondary condenser 27.
The primary condenser 25 and the secondary condenser 27 are connected to a heavy component storage tank 31 and a light component storage tank 33, respectively. On the other hand, the combustion chamber 9 is connected to an exhaust gas treatment device 35 for treating combustion exhaust gas.

In the above configuration, the treatment of the waste plastic is performed as follows.

First, in order to deal with a plastic containing halogen, a granular material or a crushed flow of waste plastic P to which an alkali such as sodium hydroxide is added as an agent for promoting dehalogenation is accommodated in the inner tank 1. Then, the inner tank 1 is lifted above the outer tank 3 by the jib crane 5, the hatch 7 is opened, and the inner tank 1 is set in the concave portion 3 b of the outer tank 3. Next, burner 1
When the partition plate 3a is heated by igniting 1, the heat is transferred through the portion of the inner tank 1 that is in contact with the partition plate 3a, and the waste plastic P is heated. When the heating is continued, a gas containing a fuel oil component is generated by thermal decomposition of the waste plastic, and the inside of the outer tank 3 is filled and dry-distilled to promote the reforming into oil. The temperature of the waste plastic is detected by the detector 13, the combustion of the burner 11 is controlled accordingly, and the temperature inside the inner tank 1 is preferably adjusted to 400 to 500 ° C. The product gas containing the gaseous fuel oil flows through the pipe 15, during which the flow rate is appropriately adjusted by the control valve 19. When the pressure in the outer tub 3 fluctuates rapidly, the control valve 19 is opened and closed. The produced gas reaches the primary condenser 25 where it is cooled, and the liquefied component 101 containing a large amount of heavy matter is condensed and separated and stored in the heavy matter storage tank 31. The gas is further cooled in the secondary condenser 27, and the liquefied component 103, such as kerosene, which contains many light components is condensed and separated and stored in the light component storage tank 33. The gas components that are not condensed are sent to an exhaust gas treatment device 35, where they are treated so that they can be released into the atmosphere.

After the thermal decomposition of the waste plastic is completed, the burner 11 is extinguished, the heating is stopped, and the outer tub 3 is cooled to about room temperature. Completion of the thermal decomposition can be detected by, for example, an increase in the temperature in the inner tank 1. Alternatively, the completion of the cracking reaction may be considered when a calculated amount of fuel oil is obtained according to the amount of the raw material waste plastic. After the outer tub 3 is cooled, the hatch 7 is opened and the inner tub 1 is taken out by the jib crane 5. The taken-out residue 105 of the inner tank 1 is scraped out and washed using a scraping machine 39 having a rotary drive shaft 37. During scraping and cleaning of the residue, the waste plastic is thermally decomposed using a separate inner tank. Since the place and environment in which the scraping cleaning work is performed can be appropriately selected, it is easy to take care not to impair the health of the worker. When a fuel component remains in the scraped residue, the residue can be used as a solid fuel.

In the above-mentioned thermal decomposition apparatus, the diameter d of the inner tank 1 and the inner diameter D of the recess 3b of the partition plate 3a are, as shown in FIG. It is set so that a slight gap is formed between the surface of the concave portion 3b and the coefficient of thermal expansion of the material of the inner tank 1 is determined by the partition plate 3
The combination of materials is selected so as to be slightly larger than the coefficient of thermal expansion a. With this configuration, at normal temperature, the inner tank 1 is smoothly inserted into the recess 3b, and the material of the inner tank 1 and the partition plate 3a expands at the time of heating, so that the recess 3b and the outer surface of the inner tank 1 And the thermal conductivity to the inner tank 1 is improved. For example, when the inner tank 1 is formed of austenitic stainless steel and the partition plate 3b is formed of carbon steel,
The expansion rate of the inner tank is large, and the inner tank can be brought into close contact.
The diameter ratio d / D (when d or D is not constant, each average value in a region where both contact) is 0.7 <d / D ≦
It is set appropriately within the range of 0.98. When the diameter ratio is 0.98 or less, the operation of fitting the inner tank 1 into the concave portion 3b at normal temperature is easy, but when it is 0.7 or less, it becomes difficult to obtain a suitable thermal conductivity during heating.

By heating, the injected plastic is
Taking into account the rise in the liquid level of the fluid due to the bubbles at the time of decomposition, the fluid generally expands 1.2 to 1.5 times, and sometimes 2 times or more.
Therefore, when the waste plastic is accommodated in one inner tank, the waste plastic overflows from the inner tank 1 during thermal decomposition. Therefore,
It is preferable that the amount of the waste plastic stored in the inner tank 1 is 50 to 70% of the height of the inner tank 1. Further, heating the upper portion of the waste plastic promotes further expansion upward, so that the heat conducting portion is preferably located at the lower portion of the inner tank 1. From this point, it is preferable to set the axial height of the inner tank 1 to about 1.2 to 2 times the depth of the recess 3b.

By providing the heat conducting section as described above, heat can be directly transmitted from the outer tank to the inner tank without relying on air conduction having low thermal conductivity, and thus the waste plastic can be heated quickly. And operability is improved. or,
In such a thermal decomposition operation of waste plastics for recovering fuel oil, thermal conductivity is important for improving oil quality and reducing dispersion, and the ratio of the area of the heat conductive portion to the volume occupied by the heated waste plastics. Is 0.08 cm ² /
cm ³ or more certain of is effective.

Therefore, by adopting the double tank type structure and providing the heat conducting portion, it is possible to reduce the time loss due to the scraping of the residue and to efficiently supply the heat. The work time required for the process can be reduced, and the processing capacity per unit time can be increased.

In the above-mentioned apparatus, as shown in FIG. 1, the fuel obtained by the pyrolysis can be sent to the burner 11 through a pipe 41 and used for combustion. The operation of putting the waste plastic into the inner tank 1 and the operation of scraping out the residue may be performed in a place remote from the outer tank, and a transport means such as a truck is used as appropriate.

FIG. 4 shows a second embodiment of the thermal decomposition apparatus according to the present invention. In this example, a general-purpose drum 43 is used as the inner tank. In this case, there is a space between the inner diameter of the recess 3 b and the side of the drum 43, and this space reduces the thermal conductivity from the recess 3 b to the drum 43. In order to improve this, a space is filled with a metal medium such as steel wool or a liquid medium such as heavy oil to form a heat conducting portion. That is, by interposing such a filler having a small specific heat, a heat conductive portion closely contacting the inner tank can be formed. According to this, it can be understood that even when the d / D ratio in the first embodiment is small and the closeness at the time of heating is low, it is possible to compensate using the filler.

FIG. 5 shows a third embodiment of the decomposition apparatus according to the present invention. In this example, a frustoconical inner tank 47 is used as the inner tank. Therefore, a truncated cone-shaped recess 3b 'is used for the recess of the partition plate 3a. By thus forming the inner tank and the concave portion in a tapered shape, the operation of transferring the inner tank to the concave portion and positioning the same is not so strictly required, and the work of fitting into the concave portion becomes easy. Even if there is some error in the size design of the inner tank and the concave portion, it is possible to avoid poor heat conduction in the heated state and damage due to expansion of the device. In addition, the stability of the inner tank installed in the recess is easily obtained. Further, since the opening of the inner tank is wide, it is easy to take out the residue. Also, as shown in FIG. 6, a plurality of inner tanks can be stored and transported in an overlapping manner, so that the inner tanks can be stored and transported.
The space required for transportation can be reduced.

[0026]

As described above, the waste plastic pyrolysis apparatus of the present invention can easily treat the pyrolysis residue and has a high efficiency of the decomposition work, and its industrial value is extremely large. Further, disposal of the residue by the decomposition according to the present invention is also easy.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a configuration of a first embodiment of a decomposition apparatus according to the present invention.

FIG. 2 is a vertical sectional view showing an internal configuration of an outer tank in FIG.

FIG. 3 is a horizontal sectional view showing the internal configuration of the outer tank in FIG.

FIG. 4 is a vertical sectional view showing an outer tank in a second embodiment of the decomposition apparatus according to the present invention.

FIG. 5 is a vertical sectional view showing an outer tank in a third embodiment of the decomposition apparatus according to the present invention.

6 is a vertical sectional view showing a state in which a plurality of inner tanks in FIG. 5 are stacked.

[Explanation of symbols]

 Reference Signs List 1 inner tank 3 outer tank 9 combustion chamber 11 burner

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-200257 (JP, A) JP-A-57-38883 (JP, A) JP-A-61-155347 (JP, U) JP-A-60-155347 9954 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) C10G 1/10 ZAB B29B 17/00 C08J 11/12

Claims (1)

(57) [Claims] 1. A pyrolysis apparatus for recovering fuel oil by pyrolyzing waste plastics, comprising: an outer tank heated by a heating means; and an inner tank for storing waste plastic that can be taken in and out of the outer tank. with the door, outer tank, close contact with the inner tank surface during heating to have the heat-conducting portion for increasing the thermal conductivity of the inner tank from the outer tank, the heat conduction part of the cylindrical inner diameter D Partition
The inner layer is formed of a cylindrical container having a diameter d.
D / D is set so that 0.7 <d / D ≦ 0.98.
A pyrolysis device for waste plastics, characterized in that: