JP3774831B2 - Plastic pyrolysis equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal decomposition apparatus for thermally decomposing plastics such as waste plastic and recovering oil components.
[0002]
[Prior art]
Conventionally, various types of pyrolysis apparatuses have been used to thermally decompose plastics and recover oil components. The thermal decomposition apparatus generally used has a thermal decomposition tank whose surroundings are heated directly or indirectly, and the thermal decomposition tank has a plastic input part and a generated oil vapor discharge part at the upper part. The bottom part is provided with a discharge part for discharging the pyrolysis residue.
The plastic in the pyrolysis tank is pyrolyzed by heating to be liquefied and then evaporated to oil vapor. This oil vapor is taken out from the discharge portion, cooled and liquefied by a heat exchanger, and recovered as an oil component. When the thermal decomposition of the plastic is continued, a thermal decomposition residue accumulates at the bottom of the thermal decomposition tank. This thermal decomposition residue is taken out to the outside intermittently or continuously by a discharge means provided at the bottom.
[0003]
[Problems to be solved by the invention]
However, the conventional plastic pyrolysis apparatus has a problem that carbide or the like called coking adheres to the inner surface of the side wall of the pyrolysis tank and gradually accumulates to lower the thermal efficiency.
In addition, the pyrolysis residue that accumulates at the bottom of the pyrolysis tank is discharged by a discharge unit such as a screw conveyor. At that time, the high-viscosity residue adheres to the screw, making it difficult to transport and periodically. It was necessary to stop the operation of the pyrolyzer and clean it.
Further, there is a problem that liquefied plastic is accompanied with the pyrolysis residue discharged, which causes a reduction in the recovery rate of the oil component.
Accordingly, an object of the present invention is to provide a plastic pyrolysis apparatus that solves these problems.
[0004]
[Means for Solving the Problems]
The present invention relates to a thermal decomposition tank 1 having a cylindrical vertical shape in which a plastic is thermally decomposed and vertically disposed downward and projecting downward in a conical shape, and a scraper device that scrapes off deposits adhering to the inner surface of the side wall of the thermal decomposition tank 1. 2, and a residual渣排out portion 11 provided in the bottom portion of the pyrolysis vessel 1, the remaining渣排out portion 11 and the discharge passage 12 extending to the bottom or al outer portion inclined pyrolysis tank 1, the a twin-screw of the screw conveyor means 14 for discharging from the tip portion 13 moves to increase the thermal decomposition residue along the discharge path 12 to the outside, the heating means 15 for heating the exhaust passage 12 is provided, further the plastic pyrolysis device, characterized in that the vapor recovery pipe 21 to the oil vapor evaporated from the thermal decomposition residue back to the top of the pyrolysis chamber 1 is provided at the discharge path 12 to the tip 13 of the discharge passage 12 It is.
[0005]
[Action]
The plastic pyrolysis apparatus of the present invention can scrape off deposits adhering to the inner surface of the side wall of the pyrolysis tank with a scraper device, so there is no problem of a decrease in thermal efficiency due to the deposition. Then, the scraped deposit is discharged from the residue discharge section to the outside as a thermal decomposition residue.
In addition, since the discharge path in the residue discharge section is inclined upward from the bottom of the pyrolysis tank and extended to the outside, even if liquefied plastic is transferred along with the pyrolysis residue to the discharge path, most of the discharge path follows the inclination. It is automatically returned to the bottom of the pyrolysis tank.
Furthermore, since the screw conveyor means in the discharge path is a twin screw type in which a pair of rotating screws approach each other and cooperate to transfer the pyrolysis residue, the high-viscosity pyrolysis residue adhering to the screw is accompanied by rotation. Are scraped together. Therefore, it is not necessary to periodically stop the operation of the thermal decomposition apparatus for cleaning the screw.
[0006]
In addition, a heating means is provided in the discharge path, and a steam recovery pipe for returning the oil vapor evaporated from the thermal decomposition residue in the discharge path to the upper part in the pyrolysis tank is provided at the tip thereof, so that the inclination of the discharge path The liquefied plastic that did not return along the line is heated and evaporated by the heating means, and is recovered to the upper part of the pyrolysis tank by the steam recovery pipe. Therefore, the recovery efficiency of the oil component is increased, and most of the recovered oil vapor can be discharged as it is from the top of the thermal decomposition tank as it is without being liquefied again, so the heat required for heating the discharge path is effective. Used for
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a view schematically showing an example of the plastic pyrolysis apparatus of the present invention, and FIG. In these drawings, the pyrolysis tank 1 is used by inclining a cylindrical horizontal type, and a rotating scraper device 2 is provided inside thereof. The scraper device 2 drives a rotary shaft 3 that is supported so as to pass through the cylindrical axis of the pyrolysis tank 1, a scraper 4 that is fixed at one end along the rotary shaft 3, and the rotary shaft 3. Driving means 5 such as a reduction motor is provided, and the tip of the scraper 4 comes into contact with the inner surface of the side wall of the thermal decomposition tank 1 to scrape off the adhering matter attached thereto.
In addition, above the pyrolysis tank 1, there are provided an inlet 7 for receiving plastic introduced from the charging device 6 into the tank, and an outlet 8 for discharging oil vapor generated by the thermal decomposition to the outside. The oil vapor discharged from the discharge port 8 is introduced into the heat exchanger 10 through the pipe 9, where it is cooled and condensed by the refrigerant, and is liquefied and recovered.
[0008]
A residue discharge unit 11 is provided at the bottom of the pyrolysis tank 1. The residue discharge part 11 moves to the outside along the discharge path 12 extended to the outside along the cylindrical peripheral wall lower side of the pyrolysis tank 1 and moves the pyrolysis residue along the discharge path 12 to discharge it from the tip part 13 to the outside. Screw conveyor means 14 for heating, and heating means 15 for heating the discharge path 12.
The screw conveyor means 14 includes a drive means 16 such as a reduction motor, a pair of shafts 17 that rotate in the opposite direction or the same direction via a gear mechanism (not shown) on the drive shaft, and the respective shafts 17. It is set as the biaxial screw type provided with the spiral blade 18 provided in. The spiral blades 18 of each screw are arranged close to each other and cooperate to carry out the residue existing between the spiral blades 18 in the axial direction.
As shown in FIG. 2, the discharge passage 12 is provided so as to protrude downward from a cylindrical peripheral wall constituting the pyrolysis tank 1 and has a cross-sectional shape that accommodates the spiral blade 18 of the biaxial screw.
[0009]
The heating means 15 is composed of a heating unit A that heats the periphery of the portion of the discharge path 12 at the bottom of the pyrolysis tank 1, and a heating unit B that heats the periphery of the portion of the discharge path 12 that extends to the outside. It is heated directly or indirectly by heating gas or electric heater heating. The temperature of the heating part A is maintained and controlled by a control means (not shown) at a temperature sufficient to heat and actively evaporate the liquefied plastic stored in the discharge passage 12. Since this temperature varies depending on the type of plastic to be charged, it is generally determined experimentally, but is usually about 350 to 450 ° C. The heating unit B is controlled so as to maintain a temperature higher than the heating unit A (for example, a temperature higher by about 50 ° C.) in order to surely evaporate the liquefied plastic accompanying the pyrolysis residue in the portion in a short transfer time. Is done.
[0010]
In addition, as shown in FIG. 1 (and FIG. 2), in this example, in addition to the bottom part of the thermal decomposition tank 1 as a heating part A, the peripheral wall of the liquid level height of a liquefied plastic is heated. However, when this portion is heated by a heating means for pyrolysis (not shown), this is not necessary.
An opening / closing means 20 such as a gate valve is provided at the distal end portion 13 of the discharge passage 12 and used when the pyrolysis residue stored in the storage portion 19 is periodically taken out.
Furthermore, the tip 13 is provided with a steam recovery pipe 21 for returning the oil vapor heated and evaporated by the heating part B to the upper part in the pyrolysis tank. The outer periphery of the steam recovery pipe 21 is covered with a heat insulating material (not shown) so that the oil vapor is not liquefied in the middle.
Further, in this example, the thermal decomposition tank 1 is used by inclining the cylindrical horizontal type as it is, but the upper part thereof can be horizontally deformed in some cases.
[0011]
Next, the operation of the above apparatus will be described.
The plastic introduced from the inlet 7 is thermally decomposed in the thermal decomposition tank 1 and is once liquefied and then evaporated, discharged from the outlet 8 and introduced into the heat exchanger 10 through the pipe 9, where it is condensed and liquefied. And recovered.
Deposits such as carbides adhering to the side wall due to pyrolysis are scraped off and removed to the bottom by rotating the scraper device 2 continuously or intermittently or by repeatedly rotating at a desired angle. On the other hand, the discharge path 12 at the bottom is constantly heated by the heating part A, and solidification of the liquefied plastic in the part is prevented.
[0012]
By continuing the thermal decomposition, pyrolysis residue gradually accumulates in the discharge path 12 at the bottom of the pyrolysis tank 1, but the pyrolysis residue is transported and lifted up through the discharge path 12 inclined by the screw conveyor means 14, It is stored in the storage part 19 from the tip part 13. At that time, a considerable part of the liquefied plastic accompanied with the pyrolysis residue is returned to the bottom along the inclination, and the remaining part is evaporated by heating of the heating part B. This oil vapor rises to the front end portion 13 of the discharge passage 12, and then returns to the upper portion of the pyrolysis tank 1 through the steam recovery pipe 21 and is recovered.
Since the screw conveyor means 14 employs a twin screw type, the high-viscosity pyrolysis residue adhering to or existing between the spiral blades 18 of the screw is the mutual spiral blade 18. It is automatically conveyed by. When the storage unit 19 is filled with the pyrolysis residue, the screw is stopped, the opening / closing means 20 is closed, and the internal pyrolysis residue is taken out. By such an operation, the operation of the present apparatus can be continued while maintaining the seal.
[0013]
FIG. 3 is a view schematically showing another example of the plastic pyrolysis apparatus of the present invention. This example is substantially the same as the one shown in FIG. 1 except that the thermal decomposition tank 1 is arranged upright as a pyrolysis tank 1 and has a bottom that protrudes downward in a conical shape. Parts having the same functions as those in FIG. 1 are denoted by the same reference numerals.
Also in the case of FIG. 3, the discharge path 12 of the residue discharge unit 11 is extended from the inclined bottom part in the pyrolysis tank 1 to the outside, the heating part A is provided at the bottom part, and the heating part B is provided at the extension part. A steam recovery pipe 21 and an opening / closing means 20 are provided at the front end portion 13. Since their operation is the same as that in the case of FIG.
[0014]
【The invention's effect】
The plastic pyrolysis apparatus of the present invention configured as described above has the following effects.
(1) Since deposits adhering to the inner surface of the side wall of the pyrolysis tank can be scraped off by the scraper device, there is no problem that it gradually accumulates and lowers the thermal efficiency. Then, the scraped deposit is discharged from the residue discharge section to the outside as a thermal decomposition residue.
(2) Since the discharge path in the residue discharge section is inclined upward from the bottom of the pyrolysis tank and extended to the outside, even if the liquefied plastic is transferred along with the pyrolysis residue to the discharge path, most of it is inclined And automatically returned to the bottom of the pyrolysis tank.
Furthermore, since the screw conveyor means in the discharge path is a twin screw type in which a pair of rotating screws approach each other and cooperate to transfer the pyrolysis residue, a high viscosity that adheres to the screw or exists between the spiral recesses. These pyrolysis residues are conveyed to each other as they rotate. Therefore, it is not necessary to periodically stop the operation of the thermal decomposition apparatus for cleaning the screw.
(3) A heating means is provided in the discharge path, and further, a steam recovery pipe for returning the oil vapor evaporated from the thermal decomposition residue in the discharge path to the upper part in the pyrolysis tank is provided at the tip thereof. The liquefied plastic that has not completely returned along the inclination is heated and evaporated by the heating means, and is recovered to the upper part in the pyrolysis tank by the steam recovery pipe. Therefore, the recovery efficiency of the oil component is increased, and most of the recovered oil vapor can be discharged from the upper part of the thermal decomposition tank as oil vapor without being liquefied again, so the heat required for heating the discharge path is effective Used for
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an example of a plastic pyrolysis apparatus of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a diagram schematically showing another example of the plastic pyrolysis apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Thermal decomposition tank 2 Scraper apparatus 3 Rotating shaft 4 Scraper 5 Driving means 6 Input apparatus 7 Input port 8 Outlet 9 Pipe 10 Heat exchanger 11 Residue discharge part 12 Discharge path 13 Tip part 14 Screw conveyor means 15 Heating means 16 Drive means 17 Shaft 18 Spiral blade 19 Storage part 20 Opening / closing means 21 Steam recovery piping

Claims (1)

A cylindrical vertical pyrolysis tank 1 which is disposed upright and has a bottom protruding in a conical shape ; and a scraper device 2 for scraping off deposits adhering to the inner surface of the side wall of the pyrolysis tank 1; and a residual渣排out portion 11 provided on the bottom of the thermal decomposition tank 1, and the discharge path 12 to the remainder渣排out portion 11 extending to the bottom or al outer portion inclined pyrolysis tank 1, the exhaust Detchi 12 A screw conveyor means 14 of a twin screw type for moving and raising the pyrolysis residue along the way and discharging it from the tip end portion 13 to the outside, and a heating means 15 for heating the discharge path 12 are further provided. A steam recovery pipe 21 for returning oil vapor evaporated from the thermal decomposition residue in the discharge passage 12 to the upper part in the thermal decomposition tank 1 is provided at the front end portion 13 of the plastic thermal decomposition apparatus.

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