JP2002212569A - Pyrolisis furnace for waste plastics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pyrolisis furnace for waste plastics used in pyrolysis oil producing system for the waste plastics or the like to efficiently use the waste plastics as a fuel oil or the like by pyrolyzing them. SOLUTION: This pyrolisis furnace for the waste plastics installs an opening/ shutting system 21 to open and shut an input port H on a kiln like furnace body 20, the opening/shutting system 21 at least has a plate shutter 24 larger than the opening space of the input port H and a fixing means 25 fixing the shutter 24 by pressing the shutter to a sealing face S of a periphery of the input port H. The reduction of a pressure in the furnace and leak of a gas are inhibited beforehand caused to closing the inside of the furnace by adhering the shutter 24 to the sealing face S.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste plastic pyrolysis furnace used in a waste plastic oil conversion system for thermally decomposing waste plastic and effectively utilizing it as fuel oil or the like.

[0002]

2. Description of the Related Art In recent years, one of the most important issues among the garbage disposal measures that have been increasing is plastic parts used in most industrial products such as electric products, household goods, automobiles, PET bottles and the like. And disposal of plastic containers.

That is, such waste plastics are:
Since it is difficult for biodegradation by microorganisms such as garbage and wood garbage to occur, most of them are currently incinerated, but as is well known, plastics emit large amounts of soot and harmful gases when incinerated. In addition to the generation, there is a problem in that the high combustion temperature adversely affects the incinerator.

Therefore, in recent years, attempts have been made to collect this waste plastic and reuse it as one of valuable recycled resources.
For example, since complicated work such as collection and separation for each component, color, and the like is required, there is a problem that a great deal of cost and labor are required, and economically unfit.

Accordingly, the present applicant has developed a new waste plastic oiling system capable of effectively disposing of such waste plastics which have been difficult to dispose or recycle and effectively utilizing the waste plastics as recycled oil. A patent application has been filed (Japanese Patent Application No. 2000-63335).

This waste plastic oiling system is shown in FIG.
As shown in FIG. 2, a waste plastic pyrolysis furnace 1 that heats and melts and gasifies waste plastic by the heat of a gas burner 4 and the like, and a pyrolysis gas obtained in the waste plastic pyrolysis furnace 1 is cooled and condensed. The waste plastic pyrolysis furnace 1 mainly comprises a waste plastic pyrolysis furnace 1 which is mainly composed of an oily part 2 which is turned into oil, and is thermally decomposed into a styrene monomer or low molecular weight polyethylene. Then, the thermally decomposed gas is brought into gas-liquid contact with cooling water in the oiling section 2 to be cooled and condensed to be re-liquefied. It is designed to be used effectively as a raw material for products.

That is, as shown in the figure, first, waste plastic is introduced into the waste plastic pyrolysis furnace 1 from its upper input port together with a small amount of water, and the upper input port is closed by a shutter 3 which can be opened and closed and sealed. Thereafter, the gas burner 4 at the bottom is burned to heat the inside of the furnace. Then, the water input by this heating evaporates first,
This becomes steam and flows out to the gas line G from the gas outlet 5 extending from the inside of the furnace, and then flows through the oiling section 2 to the waste oil line L1. Accordingly, the gas line G, the oiling section 2, and the oil drain line L1 as well as the inside of the pyrolysis furnace 1 are filled with the steam, and almost all of the air accumulated therein is discharged outside the system.

[0008] Next, when all of the initially charged water evaporates and the temperature in the pyrolysis furnace 1 further rises, the waste plastics that have been charged begin to melt and liquefy and become a molten liquid. The gas is sequentially pyrolyzed and gasified, flows out from the gas outlet 5 to the gas line G, and reaches the oiling section 2. Since the oiling section 2 is provided with a jet scrubber 7 serving as a cooler and a neutralization tower 8 integrated in a water tank 6 for storing liquid, the pyrolysis gas that has reached the oiling section 2 In this jet scrubber 7, the cooling water circulation line L2
After being rapidly cooled and condensed and liquefied by being brought into gas-liquid contact with the cooling water blown out from the cooling water, it is temporarily stored in the water tank 6 together with the cooling water as a decomposed liquid.

[0009] After the mixed solution of the decomposed liquid and the cooling water obtained as described above is separated into a decomposed liquid and water up and down by specific gravity after a predetermined period of time, the decomposed liquid collected on the liquid surface side is separated into a water tank. After overflowing the overflow weir 9 provided at the end of the tank, it flows to the oil drain line L1 side, and is filtered by the filter 10 to separate solids.
The cooling water collected at the bottom is drawn out of the water tank 6 by the pump 11, sent again to the jet scrubber 7 through the cooling water circulation line L2, and sequentially cooled as high-temperature pyrolysis gas cooling water. Reused.

On the other hand, the pyrolysis gas which cannot be liquefied by the jet scrubber 7 and the harmful components such as chlorine and bromine which are not liquefied by cooling reach the neutralization tower 5 in a gaseous state, where the cooling water line After being cooled and condensed again with the cooling water newly supplied from L4, it is rendered harmless by being neutralized with the neutralizing solution supplied into the cooling water from the neutralizing agent tank 12 and then released into the atmosphere. Alternatively, the gas is returned to the pyrolysis furnace 1 via the gas recovery line G2, and is effectively used as fuel gas of the gas burner 4. The flue gas generated by the gas burner 4 flows into the flue gas line G1 and is filtered and purified by the filter 13 before being released into the atmosphere. In addition, excess cooling accumulated in the water tank 6 of the oiling section 2 is performed. Water will be sequentially discharged from the drain line L3.

Therefore, according to such a waste plastic oiling system, it is possible not only to effectively treat waste plastic which has been conventionally difficult to treat, but also to effectively use it as a flammable regenerated oil. Therefore, the waste plastic can be recycled economically and efficiently. Also,
In this treatment, no harmful gas leaks out to the outside in principle, so that it is possible to exhibit excellent effects such as no risk of polluting the local environment. In the figure, reference numeral 15 denotes a hopper for facilitating introduction of waste plastic, and reference numeral 16 denotes a jacket for guiding the combustion exhaust gas to the periphery of the furnace and heating it from the periphery.

[0012]

However, the waste plastic pyrolysis furnace 1 which is a main part of such a waste plastic oiling system has several disadvantages due to its structure as described below. There is a risk.

That is, first, in the waste plastic pyrolysis furnace 1, after the waste plastic is charged into the furnace, the inlet is closed with a plate-shaped shutter 3 to seal the inside of the furnace. The shutter 3 is shown in FIG.
As shown in (B), rails 1 formed on both sides thereof
The rack and pinion engage with the rails 17 and 17 and are opened and closed in the horizontal direction along the rails 17 and 17 by a rack and pinion system driven by a motor 18. for that reason,
When the shutter 3 closes the input port, the load is simply placed on the sealing surface S of the input port by its own weight, so that the furnace internal pressure increases and a part of the pyrolysis gas leaks from the gap, There is a possibility that the surrounding environment may be polluted, or the internal pressure may be reduced to reduce the supply amount of the decomposed gas to the oiling section.

In addition, when the waste plastic is charged,
If waste plastic or dust adheres to the sealing surface S of the charging port, the shutter 3 may not be completely closed, and a gap may be generated between the shutters, causing the same inconvenience.

On the other hand, the furnace body in which the molten liquid is directly stored is made of a metal having excellent thermal conductivity in order to transmit heat from the gas burner 9 well. Therefore, there is a disadvantage that the contact area with the high-temperature combustion gas is small and the heating efficiency is low.

In addition, depending on the waste plastic to be treated, insolubles such as earth and sand and metal adhere to the furnace, and these insolubles accumulate or adhere to the furnace bottom as residue, thereby gradually reducing the furnace volume. In addition, it is conceivable that the insoluble matter itself acts as a heat insulating material at the bottom of the furnace and significantly deteriorates the thermal conductivity.

Therefore, it is necessary to periodically remove the residue from the bottom of the furnace. The work is performed by temporarily stopping the entire system, leaving the system to cool down for a while, and then allowing the worker to remove the inlet from the furnace. Since removal is performed using a tool such as a scraper or a suction device, there is a disadvantage that the operation efficiency is greatly reduced and the operation is troublesome.

Therefore, the present invention has been devised in order to effectively solve such a problem, and its main object is to completely prevent gas leakage from an inlet and to improve heat efficiency and operation efficiency. The present invention provides a novel waste plastic pyrolysis furnace excellent in heat resistance.

[0019]

In order to solve the above-mentioned problems, the present invention is directed to a kiln-shaped furnace body provided with a waste plastic inlet at an upper portion thereof. A waste plastic pyrolysis furnace provided with a heating means for heating / melting and thermally decomposing the waste plastic and having an opening / closing mechanism for opening / closing the waste port, wherein the opening / closing mechanism has at least an opening area of the input port. And a fixing means for pressing and fixing the shutter against the sealing surface of the peripheral portion of the charging port, for example, a hydraulic pressure for pressing and fixing the shutter against the sealing surface from above, as shown in claim 4. And a cylinder. By this, when the plate-shaped shutter is closed, it is strongly pressed and closely adhered to the sealing surface of the charging port peripheral portion so that a gap does not occur, so that even if the internal pressure of the furnace body increases, the shutter and the sealing surface can be in contact with each other. Inconveniences such as gas leaking out of the furnace during the period can be completely prevented.

Further, as described in claim 2, a slide means for sliding the shutter horizontally in the horizontal direction to open and close the inlet, for example, one end is connected to the shutter side as in claim 3. If a hydraulic cylinder whose other end is swingably connected to the furnace body side is used, it can be automatically and quickly opened and closed.

Further, if a purge gas header for blowing a purge gas to the sealing surface is provided at the peripheral portion of the charging port, a part of the waste plastic or dust may temporarily adhere to the sealing surface. However, because it can be removed with a purge gas before closing the shutter,
A gap can be prevented from occurring between the shutter and the sealing surface.

Further, by forming the bottom of the furnace body in a concavo-convex shape in which a plurality of gutter-like members are arranged in parallel, the surface area of the furnace bottom is increased and the thermal efficiency is increased. Furthermore, as shown in claim 7, by having a gutter-shaped discharge path at the end of each gutter-shaped member and merging with them, by providing a screw conveyor in each of the gutter-shaped member and the discharge path, By rotating the respective screw conveyors, residues such as insoluble matter accumulated in the furnace bottom can be removed from each gutter-like member via a discharge path and easily discharged to the outside.

The heating means comprises a gas burner, and a jacket is provided around the furnace body for flowing the combustion exhaust gas from the gas burner. In addition, the flue gas can be heated from the surroundings, and the flue gas can be spirally flowed around the furnace body by providing a spiral partition plate on the jacket, so that the contact time between the flue gas and the furnace body can be improved. , And efficient furnace body heating can be achieved.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of a waste plastic pyrolysis furnace according to the present invention, and FIG.
It is a line sectional view.

As shown in the figure, this waste plastic pyrolysis furnace has a kiln-shaped furnace body 20 provided with a waste plastic inlet H, an opening / closing mechanism 21 for opening and closing the inlet H, and heating this from outside. And a heating means 22 which is integrally provided, and these are covered with a heat insulating casing 23.

The furnace body 20 is entirely made of a metal having excellent heat resistance, corrosion resistance and thermal conductivity, for example, Hastelloy, stainless steel, or superalloy. The plastic is heated and melted by the heating means 22 to be thermally decomposed, and the pyrolysis gas is sequentially supplied from the gas outlet 20a to the above-described oiling section.

The opening / closing mechanism 21 has a plate-like shutter 24 for opening and closing the waste plastic inlet H, and a fixing means 25 for pressing and fixing the shutter 24 against a sealing surface S formed on the periphery of the inlet H. It consists of

As shown in FIGS. 3 and 4, the shutter 24 has a heat-resistant rectangular shape similar to the rectangular opening H, and at least sufficiently larger than the opening area of the opening H. Wheels 26, 26, 26, 26, which are made of a flat plate and provided on each side in pairs
(It may be one or two), but it moves horizontally with respect to the insertion port H by traveling along a pair of rails 27, 27 extending horizontally from both sides of the insertion port H. On both sides of the end of the shutter 24, brackets 28, 28 extending in a direction perpendicular to the moving direction are integrally provided, and the shutter 24 is moved in a horizontal direction by a sliding means including a pair of hydraulic cylinders 29, 29. And the opening H is opened and closed. That is, one end of each of the hydraulic cylinders 29, 29 is connected to the bracket 28, 28 side of the shutter 24, and the other end is fixed to the bracket 30, 30 on the side of the inlet casing 23a. As shown in FIG. 4, the hydraulic cylinders 29, 29 are simultaneously expanded and contracted with the shutter 24 as a starting point.
Is freely opened and closed.

As shown in FIGS. 1 and 2, the fixing means 25 includes a pair of front and rear hydraulic cylinders 31 and 3 vertically supported on the upper side of the charging casing 23a.
1, 31, and 31, and U-shaped pressing claws 32, 32, 32, 32 provided at respective corners of the shutter 24. When the shutter 24 is closed, the pressing claws 32, 32, 32, 32 and each hydraulic cylinder 3
1,31,31,31 cylinder rods 33,33,3
3 and 33 respectively engage with the pressing claws 32, 32,
32, 32 is pressed against the sealing surface of the input port H by the piston rods 33, 33, 33, 33, so that the shutter 24 is pressed.
Is fixed to seal the inlet H.

That is, as shown in FIGS. 5 to 8, each of the cylinder rods 33, 33, 33 is provided with a disc-shaped flange 34, and the holding claw 32 is fitted into the piston rod 33. After that, the cylinder rod 33 is extended, and the flange portion 34 forcibly pushes down the holding claw 32 so that the shutter 24 is strongly adhered to the sealing surface S of the inlet H at each of the four corners. In addition, after the insertion port H is sealed by the shutter 24, when the insertion port H is slid, it can be easily released simply by pulling the cylinder rod 33 upward.

When the shutter 24 is forcibly pushed down to the inlet H side, the shutter 2
When the rails 27 that support the wheel 4 are fixed, the vertical movement of the shutter 24 causes the wheels 26, 26, 26,
It will be regulated through 26. Therefore, according to the present invention, as shown in FIGS.
7 is divided into two in the longitudinal direction, and the split rails 27a, 27a on the input port H side are vertically movably supported by a coil spring 35 as shown in FIG.
As shown in FIG. 6, the split rails 27a, 27a side
The shutter 24 moves up and down together with the shutter 24.
The structure does not restrict the vertical movement of the camera.
As shown in FIG. 5, the ends of the split rails 27a, 27a are connected by an H-shaped connection beam 36, and another flange 37 is provided on the cylinder rod 33. 36, the vertical rail 27a, 2
7a may be moved up and down simultaneously.
As shown, a cylindrical guide 49 may be provided at the lower end of the cylinder rod 33 to guide the cylinder vertically.

Further, as shown in FIG.
A purge gas header 38 is provided along the entire periphery of the inlet H of the inlet, and a purge gas supplied from a purge tank or the like (not shown) is supplied through a slit 39 opened at an upper portion thereof. By spraying H on the sealing surface, even if a part or waste of the waste plastic adheres or accumulates on the sealing surface H, it can be forcibly removed by the pressure of the purge gas. The slit 39 is provided with a guide piece 40 through which the purge gas flows in the direction of the seal surface H.
Is a flexible leaf spring, which easily deforms when the shutter 24 is opened and closed.
4 does not interfere.

On the other hand, as shown in FIGS. 1, 2 and 10, the bottom of the furnace body 20 is provided with a plurality of gutter members 20b, 2b.
0b... Are arranged in parallel with each other in a concave and convex (corrugated) shape, and each of the gutter-like members 20b has a gutter-like discharge passage 20c at the end of the gutter-like members 20b. The area of the furnace bottom is larger than that of the flat plate, that is, about ππ times larger than that of the flat plate.

Further, each of the gutter members 20b, 20b
, And in the discharge path 20c, screw conveyors 41, 41,... Extending in the longitudinal direction thereof are provided rotatably coaxially, and insoluble matter accumulated in the furnace bottom, for example,
Solid material such as earth and sand, metal, glass, or sludge is forcibly scraped off from the furnace bottom wall, and this is removed from each of the gutter-like members 20b,
20b are discharged to the outside from a discharge hole 42 formed in the casing 23 through a discharge path 20c. The exhaust hole 42 is provided with an open / close valve (not shown), which is closed during normal operation so that the melt or pyrolysis gas in the furnace body 20 does not leak out from the exhaust hole 42 to the outside. Of course.

Each of the screw conveyors 41, 41 provided on each of the gutter members 20b, 20b,... Has an end of the rotating shaft extending through the casing 23 to the outside, and has a pulley 43, Are provided, and a belt 4 is provided between each of the pulleys 43, 43 and a scraping motor 44 fixed outside the casing.
5 are connected to each other so that the screw conveyors 41 are simultaneously driven to rotate in the same direction.

Also, the screw conveyor 41 provided on the discharge path 20c side has a rotating shaft end portion which extends to the outside through the casing 23, and also has a pulley 46 provided at the end portion thereof. The screw conveyor 41 is rotationally driven by connecting and fixing the fixed unloading motors 47 by means of a belt 48.

Further, as shown in FIG. 11, between the gutter-like members 20b, strip-like reinforcing plates 49, 49 extending in the longitudinal direction thereof are provided, respectively. A metal thermometer 50 is embedded in the plate 49, and the reinforcing body 49, 49.
The strength of the bottom is ensured, and the temperature of the furnace bottom can be detected at any time by the metal thermometer 50.
Note that the measurement information of the metal thermometer 50 is input to a control unit that controls the output of the gas burner described later as needed.

On the other hand, heating means 2 for heating the furnace body 20
2, a combustion chamber 51 located at a lower portion of the furnace body 20, a gas burner 52 provided in the combustion chamber 51, and a periphery of the furnace body 20 with a certain gap as shown in FIGS. The furnace body 20 is heated from the bottom by the combustion gas generated in the combustion chamber 51 by the gas burner 52, and the combustion exhaust gas is supplied to the jacket 53 side communicating with the combustion chamber 51. The furnace body 20 is also heated from the periphery of the side surface by guiding the gas and flowing the gas through the exhaust gas outlet 54 at the top of the jacket 53.

Further, in the present invention, a partition plate 55 for spirally partitioning the inside of the jacket 53 is provided in the jacket 53, and the high-temperature combustion exhaust gas flowing into the jacket 53 side is directly sent to the exhaust gas outlet 54. Instead of flowing, the flue gas is spirally flown around the furnace body 20 by the partition plate 55, so that the high-temperature flue gas and the furnace body 20 come into contact with each other for as long as possible. ing. 1 and 2, reference numerals 56 and 57 denote manholes for opening and closing the combustion chamber and their opening and closing lids, 58 and 58 denote supporting legs for supporting the present cracking furnace, and 59 denotes waste plastic in the furnace body 20. Hopper, 60
Is a viewing window for checking the inside of the combustion chamber 51.

Then, in the waste plastic pyrolysis furnace of the present invention having such a structure, first, the shutter 24 for closing the inlet H of the furnace body 20 is operated by the hydraulic cylinder 31 and the pressing claw 32 or the like. Is tightly pressed against the seal surface S of the furnace 20 and is closed in such a state that the shutter 24 closely contacts the seal surface S. Therefore, even if the internal pressure in the furnace body 20 increases during operation, a gap is formed between the shutter 24 and the seal surface S. Become
Normally, it is possible to reliably prevent the inconvenience of harmful pyrolysis gas leaking out and deteriorating the surrounding environment.

In addition, a purge gas header 38 is provided on the periphery of the charging port H, and a high-pressure purge gas is blown from the purge gas header 38 to the sealing surface S when the shutter 24 is closed, so that when the waste plastic is charged, the sealing surface is closed. Even if a part of the waste plastic or dust adheres to S, it is surely removed, so that the generation of a gap in the seal surface S due to the adhesion of dust or the like can be reliably avoided.

Further, the furnace bottom of the furnace body 20 is
By increasing the surface area by arranging a plurality of b in a concavo-convex (corrugated) shape and increasing the contact area between the high-temperature combustion gas immediately after generation and the furnace bottom, the heating rate of the furnace body 20 is improved, Efficient melting and thermal decomposition can be achieved.
Further, the screw conveyor 4 is attached to the gutter-shaped member 20b or the like.
By providing 1, the solid matter or sludge deposited and adhered to the furnace bottom can be forcibly scraped off from the furnace bottom wall and easily removed, so that the cumbersome manual removal work as in the prior art is required. Becomes unnecessary, and at the same time, the furnace body 2
Since 0 can be removed in a high temperature state, the furnace downtime can be shortened, and high operating efficiency can be maintained.

Further, by providing a metal thermometer 50 for measuring the temperature of the furnace bottom at the furnace bottom, the temperature of the entire furnace body 20 can be accurately measured together with the in-furnace thermometer provided conventionally. . For example, if the difference between the temperature of the furnace bottom measured by the metal thermometer 50 and the temperature inside the furnace 20 due to the furnace thermometer furnace is small, the operation is continued as it is during gasification, and the temperature difference is determined. Exceeds a certain value, it can be determined that gasification has been completed.

Incidentally, in the initial operation method of the waste plastic cracking furnace of the present invention, water is added at the same time as or before and after the waste plastic is charged, as in the above-described conventional one. Due to the unevenness (waveform), the contact area between the waste plastic and the furnace bottom (furnace wall) is reduced, and heat transfer (melting) may not be performed well in the initial stage. Therefore, for example, if a small amount of high-boiling oil obtained from regenerated oil or the like is further injected together with this water, evaporation of the high-boiling oil occurs following evaporation of water, so that waste plastic and heat transfer surface (furnace wall) Even if the contact area is small, good heat transfer is performed, and efficient heating and melting can be achieved.

[0046]

In summary, according to the present invention, since the inlet for waste plastic can be securely sealed, it is possible to prevent a decrease in furnace pressure and a deterioration in the surrounding environment due to gas leakage in the furnace. it can. In addition, since the surface area of the furnace bottom is increased and insoluble matters and the like accumulated in the furnace bottom can be easily removed and discharged, excellent effects such as excellent thermal decomposition efficiency and operation efficiency can be exhibited. This can greatly contribute to improving the safety and reliability of the waste plastic cracking furnace, and furthermore, the entire waste plastic recycling system.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a waste plastic pyrolysis furnace according to the present invention.

FIG. 2 is a vertical sectional view taken along line XX in FIG.

FIG. 3 is a plan view taken along line YY in FIG. 1;

FIG. 4 is a plan view showing a state where a shutter is opened from the state shown in FIG. 3;

FIG. 5 is a partially enlarged view showing a portion A in FIG. 1;

6 is a longitudinal sectional view showing a state where the hydraulic cylinder is operated from the state shown in FIG.

FIG. 7 is a partially enlarged view showing a portion A in FIG. 3;

FIG. 8 is a partially enlarged view showing a portion B in FIG. 3;

FIG. 9 is a partially enlarged sectional view showing a portion A in FIG. 2;

FIG. 10 is a plan view taken along line ZZ in FIG. 1;

FIG. 11 is a partially enlarged view showing a portion B in FIG. 2;

FIG. 12 is a configuration diagram showing a conventional waste plastic oiling system.

FIG. 13 is an explanatory diagram showing a configuration near an inlet of a pyrolysis furnace used in a conventional waste plastic oiling system.

[Explanation of symbols]

 20 Furnace body 20b Gutter-like member 20c Discharge path 21 Opening / closing mechanism 22 Heating means 23 Casing 24 Shutter 25 Fixing means 31 Hydraulic cylinder 38 Purge gas header 41 Screw conveyor 53 Jacket 55 Partition plate H Inlet S Seal surface

Claims (8)

[Claims] At the bottom of a kiln-shaped furnace body provided with a waste plastic inlet at the top, heating means for heating and melting the waste plastic in the furnace to thermally decompose the waste plastic is provided. In a waste plastic pyrolysis furnace provided with an opening / closing mechanism for opening and closing, the opening / closing mechanism has a plate-shaped shutter that is at least larger than the opening area of the input port, and presses and fixes the shutter against a sealing surface of the input port peripheral portion. A waste plastic pyrolysis furnace, comprising: 2. The waste plastic pyrolysis furnace according to claim 1, wherein the shutter is provided with a slide means for sliding the shutter horizontally to open and close the charging port. 3. The waste plastic according to claim 2, wherein the slide means is a hydraulic cylinder having one end connected to the shutter side and the other end swingably connected to the furnace body side. Pyrolysis furnace. 4. The waste plastic pyrolysis furnace according to claim 1, wherein said fixing means is a hydraulic cylinder that presses and fixes the shutter against the seal surface from above. 5. The waste plastic pyrolysis furnace according to claim 1, wherein a purge gas header for blowing a purge gas to a sealing surface is provided at a peripheral portion of the charging port. 6. The waste plastic pyrolysis furnace according to claim 1, wherein the bottom of the furnace body is formed in an uneven shape in which a plurality of gutter members are arranged in parallel. . 7. An end of each of said gutter-shaped members has a gutter-shaped discharge passage merging therewith, and a screw conveyor is provided in each of said gutter-shaped member and discharge passage. A waste plastic pyrolysis furnace according to any one of claims 1 to 6. 8. The heating means comprises a gas burner, a jacket surrounding the furnace body for flowing combustion exhaust gas from the gas burner, and a spiral partition plate provided on the jacket. The waste plastic pyrolysis furnace according to any one of claims 1 to 7.