JP2001164264A - Apparatus for treating waste plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for treating a waste plastic capable of reducing the corrosion problem in a practical use in a dechlorination treatment using properties of polyvinyl chloride of thermally decomposing at about 300 deg.C and releasing hydrogen chloride. SOLUTION: This apparatus 20 for treating a waste plastic is equipped with a thermal decomposition furnace 3 for thermally decomposing and dechlorinating the waste plastic to be fed and a vacuum exhaust apparatus 6 connected to the thermal decomposition apparatus 3 and sucking and discharging a gas in the thermal decomposition apparatus 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste plastic processing apparatus for removing harmful chlorine in vinyl chloride to convert waste plastic containing vinyl chloride into a solid fuel or oil.

[0002]

2. Description of the Related Art In converting waste plastic containing vinyl chloride into a solid fuel or oil, it is necessary to remove harmful chlorine contained in the vinyl chloride and detoxify the plastic. If such a detoxification process is not performed, not only chlorine gas is generated when the generated solid fuel and oil are burned, but also highly toxic substances such as dioxin may be generated. The detoxification treatment can be performed, for example, by utilizing the property that vinyl chloride is thermally decomposed at about 300 ° C. to release hydrogen chloride.

[0003] Conventional devices for performing such processing include:
An apparatus described in Japanese Patent Application Laid-Open No. 5-245463 is known. This conventional device is a device in which a valve for adjusting the internal pressure is attached to the outlet of a screw extruder used when molding and processing plastic.
Dechlorination is performed by kneading and stirring at a high temperature of about 0 ° C.

[0004]

As described above, in order to remove harmful chlorine contained in vinyl chloride and render it harmless, it is necessary to decompose vinyl chloride at about 300 ° C. to release hydrogen chloride. . For this reason, the inside of the pyrolysis furnace in the conventional apparatus is directly exposed to a high-temperature gas environment containing hydrogen chloride, oxygen, and moisture.

[0005] When chlorine and oxygen are present in the pyrolysis furnace, Fe, which is a chemical component of equipment components, is sublimated to FeCl ₃ with the production of water by reaction with chlorine. This significantly accelerates the corrosion of the equipment. In addition, Cr, which is a chemical component of a component material, is CrCl ₃
And sublime, accelerating corrosion as well.

Further, since a temperature gradient is generated in a portion penetrating into the atmosphere (contact) such as a rotating body bearing portion, acid dew point corrosion of hydrogen chloride is accompanied particularly in a low temperature range, and there is also a problem of corrosion of device materials. Serious.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in practical use in a dechlorination treatment utilizing the property of decomposing vinyl chloride at about 300 ° C. to release hydrogen chloride. It is an object of the present invention to provide a waste plastic processing device capable of reducing a corrosion problem.

[0008]

According to the present invention, there is provided a pyrolysis furnace for decomposing a waste plastic by heating and decomposing waste plastic, and a gas connected to the pyrolysis furnace for sucking gas in the pyrolysis furnace. And a vacuum exhaust device for removing the waste plastic.

According to the present invention, even when corrosive gas such as hydrogen chloride is generated during the thermal decomposition treatment of waste plastic, the pressure inside the pyrolysis furnace is reduced to the atmospheric pressure or lower. , By reducing the amount of oxygen in the pyrolysis furnace,
Environmental conditions in which the corrosion reaction does not easily proceed can be realized. As a result, the pyrolysis furnace and the equipment connected to the pyrolysis furnace do not need to be composed only of materials having good corrosion resistance. It is possible to select the material of each component device with the intention of such functions.

[0010] In order to more effectively eliminate corrosive environmental conditions, the temperature of the contact surface should be 110 ° C or higher in a part where corrosive gas may reach the acid dew point by contacting the low temperature part of the equipment. It is preferable to perform external heating so that

In addition, by installing a test piece simulating a structural weld which is considered to have a particularly rapid corrosion progress rate in the pyrolysis furnace, the corrosion state of the pyrolysis furnace body itself can be directly investigated. In addition, the corrosion state of the equipment can be continuously monitored as a preventive maintenance.

In order to reduce the oxygen concentration in the pyrolysis furnace, it is preferable to install a member for forcibly promoting metal oxidation and consuming oxygen inside the pyrolysis furnace.

In addition, air containing oxygen, which easily promotes a corrosion reaction, is contained in waste plastic in the pyrolysis furnace, and air flows back into the pyrolysis furnace when dechlorinated waste plastic is discharged. As a countermeasure, it is preferable to replace these airs with an inert gas before introducing or discharging the waste plastic.

In addition, an inert gas purging device is installed in the shaft seal portion of the rotating body which is likely to cause air in leak, so that even if the shaft seal portion is damaged, etc.
It is preferable that air is not mixed into the pyrolysis furnace.

The present invention also provides a pyrolysis furnace for decomposing a waste plastic by thermally decomposing a waste plastic to be charged therein, and a vacuum connected to the pyrolysis furnace for sucking and removing gas in the pyrolysis furnace. An exhaust device, and a use method using a waste plastic processing apparatus, comprising: a coating step of performing a processing operation of a coating material that does not generate hydrogen chloride; and a step of starting a waste plastic processing operation. And a method comprising:

According to the present invention, the surface of equipment for treating waste plastic, which is in direct contact with corrosive gas, can be effectively protected by a coating material.

Further, the present invention provides a pyrolysis furnace for decomposing a waste plastic by thermally decomposing a waste plastic to be charged therein, and a vacuum connected to the pyrolysis furnace for sucking and removing gas in the pyrolysis furnace. A method of using a waste plastic processing apparatus, comprising: a step of operating a vacuum exhaust apparatus during a waste plastic processing operation; and a step of operating a vacuum exhaust apparatus during a waste plastic processing operation. And a step of operating.

According to the present invention, it is possible to effectively prevent corrosion of the equipment surface of the waste plastic processing during the suspension of the waste plastic processing operation.

The present invention also provides a pyrolysis furnace for decomposing a waste plastic by thermally decomposing a waste plastic to be charged therein, and a vacuum connected to the pyrolysis furnace for sucking and removing gas in the pyrolysis furnace. An exhaust device, wherein the waste plastic processing apparatus is connected to an inert gas replacement device that forcibly introduces an inert gas into the pyrolysis furnace. A method comprising the steps of: activating an inert gas replacement device during a processing operation; and activating an inert gas replacement device during a waste plastic processing operation stop.

According to the present invention, it is possible to effectively prevent corrosion of the equipment surface of the waste plastic processing during the suspension of the waste plastic processing operation.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a waste plastic processing apparatus according to a first embodiment of the present invention. FIG.
As shown in FIG. 1, a waste plastic processing apparatus 20 according to the first embodiment of the present invention is connected to a pyrolysis furnace 3 for thermally decomposing a waste plastic to be charged and performing a dechlorination treatment, and a pyrolysis furnace 3. A vacuum exhaust device 6 is connected through a pipe 16 and sucks and removes gas in the pyrolysis furnace 3.
The pyrolysis furnace 3 has an inlet 1 for charging waste plastic into the pyrolysis furnace 3, an outlet 4 for discharging pyrolysis-melted waste plastic from the pyrolysis furnace 3, Is provided.

In the present embodiment, the rotating body 2 for stirring the waste plastic to be thermally decomposed is provided in the pyrolysis furnace 3. The rotating body 2 has a screw or a plurality of fins 2a for kneading and stirring. The rotating body 2 is attached to the pyrolysis furnace 3 via a bearing 12, and is rotated by an electric motor 5 provided outside the pyrolysis furnace 3.

Further, the pyrolysis furnace 3 of the present embodiment is heated by a heating means 11 such as a heater arranged adjacent to the pyrolysis furnace 3. More specifically,
The pyrolysis furnace 3 has a heating portion 3a heated by the heating means 11 and a staying portion 3b adjacent to the heating portion for holding the waste plastic to be thermally decomposed. The heating part 3a of the pyrolysis furnace 3 is made of carbon steel having a good heat transfer coefficient, and the stagnant part 3b of the pyrolysis furnace 3 is made of stainless steel having a bad heat transfer coefficient. I have. The inlet 1 is provided in the heating part 3a, and the outlet 4 is provided in the retaining part 3b.

Next, the operation of the present embodiment having the above configuration will be described.

Waste plastic is supplied from a supply device (not shown) to the heating portion 3a of the pyrolysis furnace 3 through the input port 1.

On the other hand, the heating means 11 is activated to operate the pyrolysis furnace 3.
Is heated, and the electric motor 5 is driven to rotate the rotating body 2 inside the pyrolysis furnace 3. As a result, the waste plastic to be charged is heated to about 300 ° C., kneaded and stirred, melted and thermally decomposed.

In the course of the thermal decomposition, chlorine in vinyl chloride contained in the waste plastic is extracted as hydrogen chloride. That is, dechlorination of the waste plastic is performed.

At this time, the waste plastic is melted in the heating portion 3a immediately below the charging port 1 and is stirred by the rotating body 2 while staying in the staying portion 3b. It is effectively prevented that the waste plastic melts and remains inside.

In the present embodiment, carbon steel having a high heat transfer rate is used as the material of the heating portion 3b of the pyrolysis furnace 3, and the material of the stagnation portion 3b of the pyrolysis furnace 3 has a low heat transfer rate, that is, The use of stainless steel with excellent heat retention and low heat dissipation results in high waste plastic heating efficiency.

In the conventional structure, carbon steel having a high heat transfer coefficient may be severely corroded in a use environment of hydrogen chloride gas and may not be able to withstand actual use. Further, in order to manufacture by combining different kinds of materials, structural welding is physically required, and depending on the material of the welding rod in these welding portions, corrosion occurs, and it may not be able to withstand actual use.

However, according to the structure of the present embodiment, the highly corrosive hydrogen chloride gas generated inside the pyrolysis furnace 3 is evacuated from the inside of the pyrolysis furnace 3 to the vacuum exhaust device 6 via the connection pipe 16. It is sucked and evacuated and sent to an exhaust gas treatment device (not shown) for purification treatment. By appropriately adjusting the output of the vacuum exhaust device 6, even if a large amount of hydrogen chloride gas is generated due to the thermal decomposition of vinyl chloride in the pyrolysis furnace 3, at least the pressure inside the pyrolysis furnace 3 is reduced. Since the pressure can be reduced to the atmospheric pressure or less, the amount of oxygen remaining in the pyrolysis furnace 3 can be extremely reduced. This significantly suppresses a metal corrosion reaction in a hydrogen chloride gas atmosphere.

Therefore, as in the present embodiment, the thermal decomposition furnace 3
It is possible to use carbon steel substantially, and the heating efficiency is improved. In addition to the above, the material of the pyrolysis furnace 3 is considered in consideration of measures to reduce wall thickness due to contact abrasion of waste plastic during operation.
It is also possible to use alloy steel or the like having high hardness. In any case, it is possible to select a material for the purpose of the function.

On the other hand, the dechlorinated (detoxified) molten plastic is discharged from a discharge port 4 to a discharge device (not shown), and becomes a raw material for solid fuel and oil.

As described above, according to the present embodiment, the amount of oxygen in the pyrolysis furnace 3 can be reduced by setting the pressure inside the pyrolysis furnace 3 to a reduced pressure state below the atmospheric pressure. Environmental conditions in which the corrosion reaction does not easily proceed can be realized.

As a result, the pyrolysis furnace 3 and each equipment member connected to the pyrolysis furnace 3 do not need to be composed only of a material having good corrosion resistance, and the operating temperature can be maintained without paying special attention to material corrosion. In addition, it is possible to select the material of each component device for the purpose of the function such as the device structure and the strength condition. That is, it becomes possible to use carbon steel for the heating portion 3a of the pyrolysis furnace 3 and to use stainless steel for the staying portion 3b. With such a combination structure, the heating efficiency is significantly improved.

Further, according to the present embodiment, the provision of the rotating body 2 having the screw 2a enables effective stirring of the waste plastic.

It is to be noted that appropriate air is supplied from a supply device or a discharge device (not shown) or an air-penetrating (contacting) portion such as the bearing 12 of the rotating body 2 so that external air does not leak into the pyrolysis furnace 3. It is preferable that a blocking mechanism and a sealing mechanism are provided.

Further, the heating of the pyrolysis furnace 3 by the heating means 11 is performed so that the surface temperature in the pyrolysis dew 3 becomes 110 ° C. or higher in order to prevent the corrosive gas from reaching the acid dew point. Is preferred.

Next, a waste plastic processing apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the waste plastic processing apparatus according to the second embodiment.

As shown in FIG. 2, the waste plastic processing apparatus 20 of the present embodiment is provided with a shaft seal portion heating device 12h for externally heating the seal portion of the bearing 12 of the rotating body 2 except that a shaft seal heating device 12h is further provided. The configuration is substantially the same as that of the waste plastic processing apparatus according to the first embodiment shown in FIG. In the second embodiment, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

In this embodiment, since the shaft of the rotating body 2 has a structure penetrating the pyrolysis furnace 3, a temperature gradient occurs in the axial direction of the bearing 12, and the pyrolysis furnace of the bearing 12 is formed. In some cases, a part of 3 may be lower than the acid dew point of the corrosive gas. At a temperature lower than the acid dew point, a corrosive reaction by a corrosive gas may significantly proceed. The present embodiment is to solve such a problem.

That is, according to the present embodiment, the bearing 1
Since the seal portion 2 is supplementarily heated by the shaft seal portion heating device 12h, it is ensured that all the portions in the pyrolysis furnace 3 where the corrosive gas comes into contact are kept at 110 ° C. or higher. Therefore, the corrosion reaction due to the corrosive gas can be more effectively suppressed.

Next, a waste plastic processing apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic configuration diagram of a waste plastic processing apparatus according to the third embodiment.

As shown in FIG. 3, a waste plastic processing apparatus 20 of the present embodiment includes a test piece 13 having a welded structure made of the same material as the constituent members of the pyrolysis furnace 3 in the pyrolysis furnace 3.
The configuration is substantially the same as that of the waste plastic processing apparatus of the first embodiment shown in FIG. In the third embodiment, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

Waste plastic processing apparatus 2 of the present embodiment
Numeral 0 has a structural weld between, for example, the pyrolysis furnace 3 and each device around it. It is empirically known that the corrosion progress rate of these welded portions is particularly high. Therefore, in the present embodiment, the test piece 13 simulating the structural weld is installed inside the pyrolysis furnace 3 to reduce the thickness of the waste plastic processing apparatus 20 due to corrosion during periodic maintenance and inspection. Material inspection such as quantity measurement, non-destructive test, metal surface inspection, etc. can be performed very easily. That is, the corrosion state of the equipment can be continuously monitored for preventive maintenance without directly investigating the corrosion state of the pyrolysis furnace 3 itself.

Next, a waste plastic processing apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a schematic configuration diagram of the waste plastic processing apparatus according to the fourth embodiment.

As shown in FIG. 4, in the waste plastic processing apparatus 20 of the present embodiment, an oxidizing member 10 for forcibly consuming oxygen is provided in the pyrolysis furnace 3. It has substantially the same configuration as the waste plastic processing apparatus of the first embodiment shown in FIG. 1 except that a connection pipe 10t for supplying a high-temperature gas from the heating device 11 is provided. In the fourth embodiment, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

In the present embodiment, the high-temperature gas from the heating device 11 is supplied to the pyrolysis furnace 3 via the connection pipe 10t.
Is supplied to the oxidizing member 10 installed in the inside. The oxidizing member 10 is heated by the high-temperature gas to have a temperature higher than the internal temperature of the pyrolysis furnace 3, and reacts with oxygen existing inside the pyrolysis furnace 3 and moisture attached to the waste plastic to form a surface. Oxidation is promoted.

According to the present embodiment, by oxidizing the oxidizing member 10 forcibly, the oxygen concentration in the pyrolysis furnace 3 is reduced, and oxidation and corrosion other than the oxidizing member 10 are effectively prevented. can do. The oxidizing member 10 is
It is preferred that it be replaced periodically.

Next, a waste plastic processing apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a schematic configuration diagram of a waste plastic processing apparatus according to a fifth embodiment.

As shown in FIG. 5, the waste plastic processing apparatus 20 of the present embodiment has an inlet 1 and an outlet 4 in which inert gas is forcibly introduced into the pyrolysis furnace 3 by inert gas replacement. The configuration is substantially the same as that of the waste plastic processing apparatus of the first embodiment shown in FIG. 1 except that the apparatus 7 is connected. In the fifth embodiment, the same portions as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

In the present embodiment, by operating the inert gas replacing device 7, the air from the air shut-off mechanism of the supply device (not shown) to the air shut-off mechanism of the discharge device (not shown) via the pyrolysis furnace 3 is removed. Before injecting or discharging waste plastic, it can be replaced with an inert gas such as nitrogen gas.

According to the present embodiment, air containing oxygen, which easily causes a corrosion reaction, enters the pyrolysis furnace 3 in a form contained in the waste plastic, and heat is generated when the dechlorinated waste plastic is discharged. Backflow to the decomposition furnace 3 can be prevented. Therefore, corrosion in the pyrolysis furnace 3 can be effectively suppressed.

The inert gas replacing device 7 may be provided directly in the pyrolysis furnace 3 as shown in FIG.

Next, a waste plastic processing apparatus according to a sixth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a schematic configuration diagram of a waste plastic processing apparatus according to the sixth embodiment.

As shown in FIG. 7, in the waste plastic processing apparatus 20 of the present embodiment, the bearing 12 has an inert gas purge device 8 for preventing the surrounding air from leaking into the pyrolysis furnace 3. Other than being provided, the first
The configuration is substantially the same as that of the waste plastic processing apparatus according to the embodiment. In the sixth embodiment, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

Inert gas purging device 8 of this embodiment
Is designed to purge an inert gas such as a nitrogen gas set at a pressure higher than the atmospheric pressure and higher than the internal pressure of the pyrolysis furnace 3 into the shaft seal portion of the rotating body 2.

According to the present embodiment, during normal operation, the inert gas from the inert gas purging device 8 is constantly blown out to both the atmosphere side and the pyrolysis furnace 3 side. Even if it occurs, the inside of the pyrolysis furnace 3 and the atmosphere side do not directly pass (communicate). Therefore, air is prevented from being mixed into the pyrolysis furnace 3, and
Corrosion in the pyrolysis furnace 3 can be effectively suppressed.

When using the waste plastic processing apparatus 20 of each of the above embodiments, prior to the actual processing of the waste plastic, a coating material that does not generate hydrogen chloride, for example, plastic such as polypropylene, polyethylene, polystyrene, or silicone. It is preferable to thermally decompose mineral oil such as oil and heavy oil. Thereby, the pyrolysis furnace 3
Can be coated with molten plastic or oil, and the corrosion of the inner surface of the pyrolysis furnace 3 can be more effectively prevented.

In each of the above embodiments, it is preferable to operate the evacuation device 6 even during the stoppage of operation in order to prevent the progress of corrosion during the stoppage of operation.

Similarly, it is preferable to operate the inert gas replacing device 7 of the fifth embodiment during the suspension of operation. In this case, the inert gas is continuously injected for a period of time from the operation stop operation until the temperature inside the pyrolysis furnace 3 decreases to room temperature and the completely melted waste plastic is solidified. Is preferably stored in a closed state.

The inert gas injection device 7 is designed to extinguish the fire when, for example, the temperature inside the pyrolysis furnace 3 rises sharply during operation and, in the worst case, ignites. It is also possible to operate urgently.

[0064]

According to the present invention, even when a corrosive gas such as hydrogen chloride is generated during the pyrolysis of waste plastic, the pressure inside the pyrolysis furnace is reduced to a pressure lower than the atmospheric pressure. In addition, it is possible to reduce the amount of oxygen in the pyrolysis furnace and realize an environmental condition in which a corrosion reaction does not easily proceed.

As a result, the pyrolysis furnace and the equipment connected to the pyrolysis furnace do not need to be composed only of a material having good corrosion resistance, and no special attention is paid to material corrosion.
It is possible to select the material of each component device for the purpose of the function such as the operating temperature, the device structure and the strength condition.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a waste plastic processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a waste plastic processing apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a waste plastic processing apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a waste plastic processing apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a waste plastic processing apparatus according to a fifth embodiment of the present invention.

FIG. 6 is a schematic configuration diagram showing a modified example of the waste plastic processing apparatus according to the fifth embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing a waste plastic processing apparatus according to a sixth embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 20 Waste plastic treatment device 1 Input port 2 Rotating body 2a screw 3 Pyrolysis furnace 4 Discharge port 5 Electric motor 6 Vacuum exhaust device 7 Inert gas replacement device 8 Inert gas purge device 10 Oxidizing member 10t Connection piping 11 Heating device 12 Bearing 12h Shaft seal heating device 13 Test piece 16 Connection piping

Claims (13)

[Claims] A pyrolysis furnace for thermally decomposing the waste plastic to perform a dechlorination treatment; a vacuum exhaust device connected to the pyrolysis furnace for sucking and removing gas in the pyrolysis furnace; Waste plastic processing equipment characterized by comprising: 2. The waste plastic processing apparatus according to claim 1, wherein a rotating body for stirring the waste plastic to be thermally decomposed is provided in the pyrolysis furnace. 3. The pyrolysis furnace has a heating portion heated by heating means, and the heating portion of the pyrolysis furnace is made of carbon steel having a good heat transfer coefficient. Or the waste plastic processing apparatus according to 2. 4. The pyrolysis furnace has a retaining portion adjacent to the heating portion and retaining the waste plastic to be thermally decomposed, wherein the retaining portion of the pyrolysis furnace is made of stainless steel having a poor heat transfer coefficient. The waste plastic processing apparatus according to any one of claims 1 to 3, wherein: 5. The waste plastic processing apparatus according to claim 1, wherein the pyrolysis furnace is heated so that an inner surface thereof is 110 ° C. or higher. 6. The waste plastic processing apparatus according to claim 1, wherein the inner surface of the pyrolysis furnace is coated with molten plastic or oil. 7. The pyrolysis furnace according to claim 1, wherein a test piece having a welded structure made of the same material as a constituent member of the pyrolysis furnace is provided. Waste plastic processing equipment. 8. The waste plastic processing apparatus according to claim 1, wherein an oxidizing member for forcibly consuming oxygen is provided in the pyrolysis furnace. 9. The pyrolysis furnace according to claim 1, wherein an inert gas replacement device for forcibly introducing an inert gas into the pyrolysis furnace is connected to the pyrolysis furnace. Waste plastic processing equipment. 10. A rotating body is mounted on a pyrolysis furnace via a bearing, and the bearing is provided with an inert gas purge device for preventing ambient air from leaking into the pyrolysis furnace. The waste plastic processing apparatus according to claim 2, wherein 11. A method of using the waste plastic processing apparatus according to claim 1, wherein the coating step performs a processing operation of a coating material that does not generate hydrogen chloride, a step of starting the waste plastic processing operation, A method comprising: 12. A method of using the waste plastic processing apparatus according to claim 1, wherein the step of operating the vacuum exhaust apparatus during the waste plastic processing operation, and the step of operating the vacuum exhaust apparatus during the waste plastic processing operation is stopped. Actuating the method. 13. A method of using the waste plastics treatment apparatus according to claim 9, wherein the step of activating the inert gas replacement device during the waste plastics treatment operation, and the step of inactive during the waste plastics treatment operation stop. Actuating the gas displacement device.