JPH07216363A - System for liquefying waste plastic - Google Patents

Abstract

PURPOSE:To prevent a back flow and, consequently, to enable an apparatus to be operated safely and reliably by disposing a gas suction ejector and a water seal downstream of an apparatus for recovering a thermal decomposition oil from a thermal decomposition gas generated by thermal decomposition of a waste plastic. CONSTITUTION:Thus system comprises a reactor 1 for melting and thermally decomposing a waste plastic; condensers 2, 3 for cooling and condensing the resultant thermal decomposition gas to recover a thermal decomposition oil ; and a recovery or combustion device 4 for a remaining uncondensed and combustible gas, and an ejector 17 for ejecting a driving liquid to suck a combustible gas, and a water seal 24 are disposed between the condenser and the recovery or combustion device. An air suction pipe 21 is provided near a nozzle of the ejector. It is interlocked with a high-pressure pump 19 for feeding a driving liquid to the ejector to close or open a solenoid valve 22. The system can prevent a back flow of a gas or water and a backfire even though a negative pressure is created by removal of foreign materials from the thermal decomposition reactor or shut-down of the system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste plastic oil conversion system.

[0002]

2. Description of the Related Art Waste plastics include general wastes discharged as separated garbage and industrial wastes discharged from plastic producers. Conventionally, most wastes are incinerated and landfilled, and some industrial wastes have been reused by pyrolyzing them into fuel. However,
In recent years, all waste plastics have been reused as fuel. The conversion of waste plastics into fuel is performed by a method of melting and thermally decomposing the waste plastics as a raw material, cooling and condensing the generated pyrolysis gas, and collecting it as pyrolysis oil.

Conventionally, as an oiling system for converting such waste plastics into fuel, a thermal decomposition reactor for internally melting and thermally decomposing the waste plastics,
A condenser which is arranged on the downstream side of the thermal decomposition reactor and cools and condenses the thermal decomposition gas generated in the thermal decomposition reactor to obtain thermal decomposition oil, and a condenser which is arranged on the downstream side of the condenser and does not condense in the condenser. It is known to include a pyrolysis gas recovery device for recovering flammable pyrolysis gas or a pyrolysis gas combustion device for burning.

By the way, foreign materials such as metal, glass and earth and sand are mixed in the waste plastic as a raw material, and such foreign materials are released into the molten liquid at the time of melting and accumulated in the thermal decomposition reactor. The problem arises. Therefore, in the above-mentioned oilification system, these foreign substances are removed from the inside of the thermal decomposition reactor by the vacuum method. Therefore, when the pyrolysis gas flows backward due to negative pressure in the system and the pyrolysis gas recovery device is arranged on the downstream side of the condenser, the pyrolysis gas cannot be recovered by this device. There is. Further, when the pyrolysis gas combustion device is arranged on the downstream side of the condenser, there is a problem that backfire occurs in the system. Further, even when the operation of the thermal decomposition reactor is stopped and the temperature inside the system is lowered, the inside of the system becomes a negative pressure and the thermal decomposition gas flows backward, causing the same problem as described above.

Therefore, in order to solve such a problem, the following three oiling systems have been considered.

The first oilification system is a system in which a water seal is provided between the condenser and the pyrolysis gas recovery device or the pyrolysis gas combustion device in the above-mentioned conventional oilification system. The oilification system is a system in which compressed air injecting means for injecting compressed air to the downstream side is provided between the condenser and the pyrolysis gas recovery device or the pyrolysis gas combustion device in the above conventional oilification system. The third oilification system is provided with a blower that forcibly sucks the pyrolysis gas to the downstream side.

However, even in the above-mentioned first and second oiling systems, it is not possible to completely prevent the occurrence of backfire due to the reverse flow of the pyrolysis gas when the pressure in the system becomes negative. There was found. It has also been found that, particularly in the second oiling system, the water in the water seal flows backward and mixes with the pyrolysis oil obtained in the condenser. Further, it has been found that the third oilification system has a problem in the explosion-proof property in the blower part.

An object of the present invention is to provide a waste plastic oiling system that solves the above problems.

[0009]

SUMMARY OF THE INVENTION A waste plastic oiling system according to the present invention comprises a thermal decomposition reactor for internally melting and thermally decomposing the waste plastic, and a thermal decomposition reactor disposed downstream of the thermal decomposition reactor. A condenser that cools and condenses the pyrolysis gas generated in the cracking reactor to obtain pyrolysis oil, and a pyrolysis gas that is placed downstream of the condenser and that collects the flammable pyrolysis gas that has not condensed in the condenser. A waste plastic oiling system comprising a recovery device or a pyrolysis gas combustion device for combustion, wherein a driving liquid is ejected from a nozzle at high speed between a condenser and the pyrolysis gas recovery device or the pyrolysis gas combustion device. An ejector for injecting and sucking the pyrolysis gas to send the pyrolysis gas to the downstream side, and a water seal for preventing backflow of the pyrolysis gas are arranged.

In the above, it is preferable to use water as the driving liquid for the ejector. In this case, the cost is low and the handling is easy.

The above waste plastic oiling system is provided with a tank in which the driving liquid for the ejector is placed, and the tank is fed into the tank on the inlet side for feeding the pyrolysis gas that has not condensed in the condenser. An outlet side conduit for sending the pyrolysis gas to the pyrolysis gas recovery device or the pyrolysis gas combustion device is connected, an ejector is provided so as to face the inside of the entrance side pipe, and a driving liquid supply pipe is provided between the ejector and the tank. In some cases, the driving liquid supply pipe is provided with a high-pressure liquid pump that sends the driving liquid in the tank to the ejector.

In the waste plastic oil conversion system, an air suction pipe having a tip open to the atmosphere may be connected near the nozzle of the ejector.

Further, the waste plastic oiling system is provided with a tank in which the driving liquid for the ejector is placed, and an inlet side conduit for feeding the pyrolysis gas that has not condensed in the condenser to this tank, and a tank for feeding the pyrolysis gas. The outlet side conduit for sending out the pyrolyzed gas that has been generated to the pyrolyzed gas recovery device or the pyrolyzed gas combustion device is connected,
An ejector is provided so as to face the inlet side conduit, a drive liquid supply pipe is provided between the ejector and the tank, and a high pressure liquid pump for supplying the drive liquid in the tank to the ejector is provided in the drive liquid supply pipe. An air suction pipe with a tip open to the atmosphere is connected to the downstream side of the nozzle of, and the air suction pipe is interlocked with the high-pressure liquid pump and opens when the high-pressure liquid pump operates, and also closes when stopped. A valve may be provided.

[0014]

The ejector for injecting the driving liquid at a high speed from the nozzle and sucking the pyrolysis gas to send the pyrolysis gas to the downstream side between the condenser and the pyrolysis gas recovery device or pyrolysis gas combustion device, and the pyrolysis gas If a water seal is installed to prevent backflow, the pyrolysis gas is forced to be sent to the wake side by the ejector, so even if the system becomes a negative pressure, it will function as a water seal. In addition, the reverse flow of pyrolysis gas is completely prevented. Moreover, since the pyrolyzed gas is forcibly sent to the downstream side by the ejector, the reverse flow of water in the water seal is prevented.

A tank containing the driving liquid for the ejector is provided, and an inlet-side conduit for feeding pyrolysis gas that has not condensed in the condenser to this tank, and a pyrolysis gas for recovering the pyrolysis gas fed into the tank An outlet side conduit for sending to the device or the pyrolysis gas combustion device is connected, an ejector is provided so as to face the inside of the inlet side conduit, a driving liquid supply pipe is provided between the ejector and the tank, and the driving liquid supply pipe is connected to the tank. If the high-pressure liquid pump for supplying the driving liquid therein to the ejector is provided, the driving liquid can be circulated and used.

If an air suction pipe whose tip is open to the atmosphere is connected near the nozzle of the ejector, when the driving liquid is jetted at high speed from the nozzle of the ejector, air is sucked from the air suction pipe and the driving liquid is discharged. And the gas-liquid mixed phase fluid is injected. Therefore, the ability of sucking the pyrolysis gas is improved as compared with the case where the driving liquid is jetted alone.

A tank containing the driving liquid for the ejector is provided, and an inlet side conduit for feeding the pyrolysis gas that has not condensed in the condenser to this tank, and a pyrolysis gas for recovering the pyrolysis gas fed into the tank An outlet side conduit for sending to the device or the pyrolysis gas combustion device is connected, an ejector is provided so as to face the inside of the inlet side conduit, a driving liquid supply pipe is provided between the ejector and the tank, and the driving liquid supply pipe is connected to the tank. A high-pressure liquid pump that sends the driving liquid inside the ejector to the ejector is provided, and an air suction pipe whose tip opens into the atmosphere is connected to the downstream side of the ejector nozzle, and the air suction pipe is linked to the high-pressure liquid pump and If a solenoid valve is provided which is opened when the pump is operated and is closed when the pump is stopped, the driving liquid can be circulated and used. Further, since the solenoid valve is opened only when the high-pressure liquid pump is operating and is closed when the high-pressure liquid pump is stopped, it is possible to prevent air from entering the system when the high-pressure liquid pump is stopped.

[0018]

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

FIG. 1 shows the entire construction of an oil plasticization system for waste plastics according to the present invention, and FIG. 2 shows the construction of the essential parts thereof.

In FIG. 1, the waste plastic oiling system is arranged on the downstream side of the thermal decomposition reactor (1) for melting and thermally decomposing the waste plastic inside, and on the downstream side of the thermal decomposition reactor (1). A first condenser (2) for cooling and condensing the pyrolysis gas generated in the pyrolysis reactor (1) to obtain kerosene (pyrolysis oil); The second condenser (3), which obtains gasoline (pyrolysis oil) by cooling and condensing the pyrolysis gas that did not condense in the first condenser (2), and is arranged downstream of the second condenser (3). In addition, a burner (4) (pyrolysis gas combustion device) that burns combustible pyrolysis gas that has not condensed in both condensers (2) and (3) is provided. First capacitor
The kerosene collected in (2) is stored in the kerosene tank (5).
The gasoline collected by the second condenser (3) is stored in the gasoline tank (6).

The pyrolysis reactor (1) is arranged in a furnace (8) having a heating burner (7) which uses the recovered pyrolysis oil as a fuel. The bottom surface of the pyrolysis reactor (1) has a concave spherical shape that is recessed downward. Top wall (1a) of pyrolysis reactor (1)
A waste plastic supply port (9) that can be opened and closed is provided in the waste plastic, and the waste plastic conveyed from the waste plastic receiving tank (10) by the conveyor (11) is pyrolyzed through this supply port (9). It is designed to be fed into the container (1). Further, a pyrolysis gas discharge pipe (12) is provided on the top wall (1a) of the pyrolysis reactor (1), and the tip of this discharge pipe (12) is connected to the first condenser (2). There is.

A reformer (13) for reforming the pyrolysis gas generated in the pyrolysis reactor (1) into a low boiling point component is provided in the middle of the discharge pipe (12). The reformer (13) is adapted to be heated by the combustion exhaust gas of the heating burner (7) which has heated the thermal decomposition reactor (1). The combustion exhaust gas of the heating burner (7) that has heated the reforming device (13) is discharged to the atmosphere.

A heavy oil that collects high-boiling components that have not been sufficiently reformed in the reformer (13) in the middle of the discharge pipe (12) and on the downstream side of the reformer (13). A collection device (14) is provided. The heavy oil collected by the heavy oil collecting device (14) is returned to the pyrolysis reactor (1).

On the downstream side of the second condenser (3) and on the burner
A drive water tank for ejector (15) (driving liquid tank) is arranged in the portion on the upstream side of (4), and the driving water for ejector (driving liquid) is put in the lower part of this tank (15). There is. Also, on the top wall of the tank (15), one end is the second condenser.
The other end of the inlet-side conduit (16) that is connected to (3) and that sends the pyrolysis gas that has not condensed in the second condenser (3) into the upper space of the tank (15) is connected. As shown in Fig. 2, at the end of the inlet side conduit (16) on the tank (15) side, drive water is rapidly fed from the nozzle (17a) into the inlet side conduit (16) toward the tank (15) side. Jetting, and thus the second
An ejector (17) that sucks the combustible pyrolysis gas that has not condensed in the condenser (3) and sends it into the tank (15) is provided so as to face the inside of the inlet side conduit (16). Ejector (1
Drive water supply pipe (18) extending from the lower end of the tank (15) to 7)
(Drive liquid supply pipe) is connected. Drive water supply pipe (1
In the middle of step 8), the high-pressure water pump (19) (high-pressure liquid pump), and the solenoid valve (20) that is interlocked with the high-pressure water pump (19) and opens when the pump (19) operates and also closes when it stops. )
Is provided. Also, the nozzle in the ejector (17)
An air suction pipe (21) having a tip open to the atmosphere is connected to a portion closer to the tank (15) than the (17a), and the air suction pipe (21) is linked to the high-pressure water pump (19) and pumps ( A solenoid valve (22) is provided which is opened when the operation (19) is performed and is closed when the operation is stopped.

At the portion on the downstream side of the drive water tank for ejector (15) and on the upstream side of the burner (4), the pyrolysis gas sent into the upper space in the tank (15) is burned by the burner (4). A water seal (24) is provided in the middle of the outlet side conduit (23) for sending out to the above, to prevent backflow of the pyrolysis gas and prevent backfire.

Through the top wall (1a) of the thermal decomposition reactor (1),
A hollow vertical rotation shaft (25) is arranged. Vertical rotation axis
The lower end of (25) is located near the bottom of the pyrolysis reactor (1). The upper end of the vertical rotation shaft (25) is located above the top wall (1a) and is connected to the drive motor via a reduction gear (not shown). A plurality of stirring blades (26) are fixedly provided at the lower end of the vertical rotation shaft (25). Each stirring blade
The lower edge of the (26) is formed in a substantially arc shape according to the shape of the bottom surface of the thermal decomposition reactor (1).

A vertical foreign matter suction tube (2
7) is located. The upper end of the foreign matter suction pipe (27) extends above the upper end of the vertical rotation shaft (25) and is connected to the foreign matter collection container (29) by a conduit (28). Foreign Material Collection Container (29)
On the top wall (29a) of the tank, one end has the second condenser (3) and the tank (1
The other end of the conduit (30) connected to the inlet side conduit (16) that connects with (5) is connected. In the middle of the conduit (30), a vacuum pump (31) for sucking the molten liquid containing foreign matter from the pyrolysis reactor (1) into the foreign matter collection container (29) is provided. In the part of the conduit (30) between the foreign material collection container (29) and the vacuum pump (31), the foreign material mixed melt liquid sucked from the thermal decomposition reactor (1) by the vacuum pump (31) is mixed. A condenser (32) for cooling and condensing the previously decomposed pyrolysis gas is provided. The pyrolysis oil collected by the condenser (32) is stored in the tank (33).

In such a construction, the waste plastic contained in the waste plastic receiving tank (10) mixed with the foreign matter is conveyed by the conveyor (11) and supplied from the supply port (9) to the thermal decomposition reactor (1). Supplied within. When a predetermined amount of waste plastic is supplied into the pyrolysis reactor (1), the supply port (9) is closed. This waste plastic is heated and melted by the combustion exhaust gas from the heating burner (7) to form a molten liquid. When the melt is maintained at a predetermined temperature or higher, it undergoes a thermal decomposition reaction to generate a thermal decomposition gas. Here, in order to accelerate the reaction, a vertical rotation shaft (2
5) Rotate and stir the melt in the thermal decomposition reactor (1) with a stirring blade.
Stir according to (26). The generated pyrolysis gas is exhaust pipe (12)
It is sent to the reforming device (13) through the gas and is heated by the combustion exhaust gas of the heating burner (7) that has heated the thermal decomposition reactor (1) to be reformed into a low boiling point component. The pyrolysis gas reformed to a low boiling point component is sent to the first condenser (2) through the discharge pipe (12). The high boiling point components of the pyrolysis gas that have not been sufficiently reformed in the reformer (13) are collected as heavy oil in the heavy oil collector (14). The heavy oil collected by the heavy oil collecting device (14) is returned to the pyrolysis reactor (1).

The low boiling point component of the pyrolysis gas sent to the first condenser (2) is cooled here and condensed, whereby kerosene is recovered. The recovered kerosene is a kerosene tank
It is stored in (5). The low boiling point components of the pyrolysis gas that have passed through the first condenser (2) without being condensed are sent to the second condenser (3) where they are cooled and condensed,
This collects gasoline. The recovered gasoline is stored in the gasoline tank (6).

The pyrolysis gas that has not condensed in the second condenser (3) is sent to the upper space of the ejector drive water tank (15) through the inlet side conduit (16). At this time, when the high-pressure water pump (19) is operated, the two solenoid valves (20) and (22) are respectively opened in association with this, and the driving water in the tank (15) is moved to the nozzle of the ejector (17). From (17a) to inlet side conduit
It is injected into the tank (15) at a high speed toward the tank (15), air is first sucked from the air suction pipe (21) and mixed with water, and this gas-liquid mixed phase fluid becomes a driving high-speed fluid and becomes a conduit ( The pyrolysis gas that has been injected into the 16) and not condensed in the second condenser (3) is sucked and forcedly sent into the upper space of the tank (15). Then, it is sent to the burner (4) through the water seal (24) and burned there. The driving water in the tank (15) is circulated and used.

When such an operation is continued, the foreign substances mixed in the waste plastic accumulate in the thermal decomposition reactor (1) as the waste plastic melts. Then, foreign matter with a large specific gravity such as metal or glass will be stirred by the stirring blade (2
Due to the agglomeration effect due to the shape of 6) and the shape of the bottom surface of the pyrolysis reactor (1), they accumulate at the center of the bottom surface of the pyrolysis reactor (1). If the amount of accumulated foreign matter increases, problems such as damage to the stirring blade (26) and burning of the melt at the bottom of the thermal decomposition reactor (1) occur. To prevent this, a vacuum pump
Activate (31). Then, the inside of the foreign matter collection container (29) becomes a vacuum state, and the molten liquid in the thermal decomposition reactor (1) passes through the foreign matter suction pipe (27) and the conduit (28) together with the foreign matter collection container (2).
9) It is sucked in. Thus, the foreign matter is removed without stopping the operation of the oilification system.

When the melted liquid is sucked into the foreign matter collection container (29), the inside of the thermal decomposition reactor (1) becomes negative pressure. Pyrolysis reactor
When the inside of (1) becomes negative pressure, the inert gas is sent into the thermal decomposition reactor (1) to adjust the pressure, but the inside of the system becomes negative pressure. This is unavoidable, and the pyrolysis gas discharged from the pyrolysis reactor (1) may flow backward. However, the ejector (1
Since the pyrolysis gas is forcedly sent to the wake side by 7), the backflow of the pyrolysis gas is completely prevented in combination with the function of the water seal (24), and the burner (4) is reliably It is sent and burned here. Therefore, the occurrence of backfire is completely prevented. Moreover, the water seal (2
4) Backflow of water in the inside is also prevented, which allows the gas tank
Water is prevented from mixing with gasoline in the (6) or kerosene in the kerosene tank (5).

In the above embodiment, the ejector (17)
It is also possible to maintain the system internal pressure at a desired pressure by making the capacity of the high-pressure water pump (19), which is the drive source, of the system variable in association with the system internal pressure. When the amount of pyrolysis gas generated in the pyrolysis reactor (1) is small and the ejector (17) is actuated to generate a negative pressure on the upstream side, the ejector (17) injects the gas. A part of the air in the gas-liquid mixed phase fluid may be supplied to the upstream side.

In the above embodiment, two condensers for cooling and condensing the pyrolysis gas are provided, but the number of such condensers is not limited to this.
Further, in the above embodiment, the pyrolysis gas that was not condensed in the condenser is burned by the burner (4), but instead of this, the pyrolysis gas may be recovered by a recovery device. Good. Further, although water is used as the driving liquid for the ejector in the above-mentioned embodiment, the present invention is not limited to this.

[0035]

As described above, according to the waste plastic oiling system of the present invention, the reverse flow of the pyrolysis gas is completed even when the pressure in the system becomes negative, in combination with the function of the water seal. To be prevented. Therefore, when the flammable pyrolysis gas recovery device that has not condensed in the condenser is arranged on the downstream side of the condenser, the pyrolysis gas is reliably recovered. If a combustor for combustible pyrolysis gas that did not condense in the condenser is provided on the downstream side of the condenser, the combustion of the pyrolysis gas is performed reliably and backfire is prevented from occurring. It Furthermore, since the backflow of water in the water seal is prevented by the action of the ejector, it is possible to prevent water from being mixed into the pyrolysis oil collected by the condenser.

Further, the tank is provided with a driving liquid for the ejector, and an inlet side conduit for feeding the pyrolysis gas which is not condensed in the condenser to the tank, and the pyrolysis gas for the pyrolysis gas fed into the tank. An outlet side conduit for sending to a gas recovery device or a pyrolysis gas combustion device is connected, an ejector is provided so as to face the inside of the inlet side conduit, a drive liquid supply pipe is provided between the ejector and the tank, and a drive liquid supply pipe If a high-pressure liquid pump that sends the driving liquid in the tank to the ejector is provided in the device, the driving liquid can be circulated and used, so that it is not necessary to use a large amount of the driving liquid and the cost is reduced.

Further, if an air suction pipe having a tip open to the atmosphere is connected near the nozzle of the ejector, when the driving liquid is jetted at high speed from the nozzle of the ejector, air is sucked from the air suction pipe. It mixes with the driving liquid, and this gas-liquid mixed phase fluid is ejected. Therefore, as compared with the case where the driving liquid is sprayed alone, the suction capacity of the pyrolysis gas is improved, and the backflow of the pyrolysis gas and the backflow of water in the water seal can be prevented more completely.

Further, the tank is provided with a drive liquid for the ejector, and an inlet-side conduit for feeding the pyrolysis gas that has not condensed in the condenser to the tank and the pyrolysis gas fed into the tank are pyrolyzed. An outlet side conduit for sending to a gas recovery device or a pyrolysis gas combustion device is connected, an ejector is provided so as to face the inside of the inlet side conduit, a drive liquid supply pipe is provided between the ejector and the tank, and a drive liquid supply pipe Is provided with a high-pressure liquid pump for sending the driving liquid in the tank to the ejector, an air suction pipe having a tip opening into the atmosphere is connected to the downstream side of the ejector nozzle, and the air suction pipe is interlocked with the high-pressure liquid pump and If a solenoid valve is provided that opens when the high-pressure liquid pump operates and closes when it stops, the drive liquid can be circulated and used. , Cost is cheap and there is no need use a large amount of the driving liquid. Further, it is possible to prevent air from entering the system when the high-pressure liquid pump is stopped.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the overall configuration of a waste plastic oil conversion system according to the present invention.

FIG. 2 is a sectional view showing a structure of a main part of the same.

[Explanation of symbols]

 (1) Pyrolysis reactor (2) First condenser (3) Second condenser (4) Burner (pyrolysis gas combustion device) (17) Ejector (24) Water seal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C08J 11/12 7310-4F

Claims (4)

[Claims] 1. A pyrolysis reactor that melts and thermally decomposes waste plastic inside, and a pyrolysis gas that is disposed downstream of the pyrolysis reactor and that is generated by the pyrolysis reactor is cooled and condensed. It is equipped with a condenser for obtaining pyrolysis oil and a pyrolysis gas recovery device for recovering combustible pyrolysis gas which is arranged on the downstream side of the condenser and has not condensed in the condenser, or a pyrolysis gas combustion device for combustion. A waste plastic oiling system, in which a driving liquid is injected at high speed from a nozzle between a condenser and a pyrolysis gas recovery device or a pyrolysis gas combustion device, and the pyrolysis gas is sucked and sent to the downstream side. A waste plastic oil conversion system that has an ejector and a water seal that prevents backflow of pyrolysis gas. 2. A tank in which a driving liquid for an ejector is placed, an inlet-side conduit for feeding pyrolysis gas that has not condensed in a condenser to the tank, and a pyrolysis gas for the pyrolysis gas fed into the tank. An outlet side conduit for sending to a gas recovery device or a pyrolysis gas combustion device is connected, an ejector is provided so as to face the inside of the inlet side conduit, a drive liquid supply pipe is provided between the ejector and the tank, and a drive liquid supply pipe The waste plastic oiling system according to claim 1, further comprising a high-pressure liquid pump for feeding the driving liquid in the tank to the ejector. 3. The waste plastic oiling system according to claim 1, wherein an air suction pipe having a tip opening into the atmosphere is connected near the nozzle of the ejector. 4. A tank containing a driving liquid for an ejector is provided, and an inlet side conduit for feeding pyrolysis gas that has not condensed in a condenser to this tank, and pyrolysis gas for pyrolysis gas fed into the tank. An outlet side conduit for sending to a gas recovery device or a pyrolysis gas combustion device is connected, an ejector is provided so as to face the inside of the inlet side conduit, a drive liquid supply pipe is provided between the ejector and the tank, and a drive liquid supply pipe Is provided with a high-pressure liquid pump for sending the driving liquid in the tank to the ejector, an air suction pipe having a tip opening into the atmosphere is connected to the downstream side of the ejector nozzle, and the air suction pipe is interlocked with the high-pressure liquid pump and The waste plastic oiling system according to claim 1, further comprising an electromagnetic valve that is opened when the high-pressure liquid pump is operated and is closed when the high-pressure liquid pump is stopped.