JP2016060800A - Waste plastic liquefaction processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste plastic liquefaction processing apparatus in which the amount of molten waste plastic in the thermal decomposition kettle is maintained within a predetermined range, and the thermal decomposition of the molten waste plastic is carried out efficiently.SOLUTION: Provided is a waste plastic liquefaction processing apparatus including a thermal decomposition kettle for thermally decomposing a waste plastic and producing a decomposition gas, and a condenser for cooling and liquefying the decomposition gas obtained by the thermal decomposition kettle to produce a regeneration oil. To the thermal decomposition kettle, a molten waste plastic is fed and there is provided therein a liquid level measurement unit for controlling the liquid level of the molten waste plastic in the thermal decomposition kettle, and the liquid level measurement unit has a plurality of thermometers as well as having the positions of the temperature measurement part of said thermometers each placed in a different position in respect of the height direction. The liquid level position of the molten waste plastic in the thermal decomposition kettle is maintained within a predetermined range by grasping the position of the liquid level by the change in the temperature of the respective thermometers and controlling the feed of the molten waste plastic.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus for producing recycled oil by decomposing waste plastic, and more specifically, an apparatus for continuously supplying waste plastic, characterized by controlling the liquid level in the pyrolysis kettle It is the invention which concerns on the apparatus for manufacturing regenerated oil using.

  Conventionally, as a plastic recycling method, various methods for decomposing waste plastic to obtain recycled oil and the like have been studied. As an example of this method, a method is known in which waste plastic is melted and sent to a pyrolysis kettle, and then pyrolyzed in the pyrolysis kettle to generate cracked gas, which is liquefied to obtain recycled oil ( Patent Document 1).

  By the way, if the amount of molten waste plastic in the pyrolysis kettle fluctuates, the amount of heat applied to the molten waste plastic fluctuates and at the same time the residence time in the kettle fluctuates, so that thermal decomposition becomes insufficient or conversely heat is applied. Too much carbonization increases. For this reason, it is preferable to keep the amount of the molten waste plastic in the pyrolysis kettle within a certain range.

JP 2005-170986 A

However, since it is necessary to keep the pyrolysis pot at a high temperature, there is currently no instrument that can be used as an industrial measuring instrument based on the operating temperature and contents, and the amount inside is confirmed directly or indirectly. Difficult to do. In addition, since some components discharged from the pyrolysis kettle are not captured, it is difficult to accurately grasp the amount of the pyrolysis kettle coming in and out, and the amount of molten waste plastic present in the pyrolysis kettle is It is difficult to grasp.
Accordingly, an object of the present invention is to measure the liquid level of the molten waste plastic in the pyrolysis kettle using a thermometer, hold it within a predetermined range, and efficiently perform the thermal decomposition of the molten waste plastic.

  The present invention relates to a pyrolysis kettle that pyrolyzes waste plastic to generate cracked gas, and a waste plastic oil conversion process having a condenser that cools and liquefies the cracked gas obtained in the pyrolysis kettle to obtain recycled oil The pyrolysis kettle is supplied with molten waste plastic, and is provided with a liquid level measuring unit for controlling the liquid level of the molten waste plastic in the pyrolysis kettle. In addition, the temperature measuring units of these thermometers are arranged at different positions in the height direction, and the position of the liquid level is grasped by the temperature change of each thermometer, It is a control unit that controls the supply of molten waste plastic so that the position of the liquid level of the molten waste plastic in the pyrolysis kettle is within a predetermined range. To use the equipment Ri, it was to solve the above-mentioned problems.

  The present invention has a liquid level measuring unit, that is, a plurality of thermometers in the pyrolysis kettle, and the temperature measuring units of these thermometers are arranged at different positions in the height direction, In the change, the position of the liquid level of the molten waste plastic in the thermal decomposition pot is controlled within a predetermined range by grasping the position of the liquid level and controlling the supply of the molten waste plastic to the thermal decomposition pot. Since the control unit is provided so that the position of the liquid level can be within a predetermined range, the thermal decomposition of the molten waste plastic can be stabilized, the thermal decomposition becomes insufficient, the carbonization amount Can be prevented from increasing. For this reason, thermal decomposition of molten waste plastic can be performed efficiently.

The flowchart which shows the process of the waste plastic oil conversion processing apparatus which concerns on this invention Schematic diagram showing an example of the liquid level measuring part of the pyrolysis kettle of FIG. In FIG. 1, a flow diagram showing a case where a reflux tower is used and a case where part of the product is returned to the reflux tower or the like. In FIG. 1, a flowchart showing a process of cooling the pyrolysis kettle

  As shown in FIG. 1, the waste plastic oil converting apparatus according to the present invention cools the cracked gas obtained in the pyrolysis kettle 11a and the pyrolysis kettle 11a which pyrolyzes the waste plastic M to produce cracked gas. It is an apparatus having a condenser 12 that is liquefied to obtain regenerated oil.

  Examples of the waste plastic to be treated in the present invention include polyolefins such as polyethylene and polypropylene, polystyrene, polyamide and the like.

  As a specific process, the process shown in FIG. 1 can be mentioned. First, the waste plastic M to be treated is washed and dried in the washing and drying step 13. Thereby, the dust adhering to the waste plastic M can be removed, and liquefaction in the next step can be more easily performed. As this washing machine, (manufactured by Kanemiya Co., Ltd .: Bun-Sen) can be raised. Moreover, the said drying process can dry using the waste heat of the thermal decomposition pot 11a.

  The washed and dried waste plastic M is liquefied in the liquefaction step 14 to obtain molten waste plastic. The temperature at this time should just be the temperature which can liquefy object waste plastic, and if it is about 230 to 260 degreeC, it is enough. As an apparatus used for this liquefaction process, extruders, such as a single screw extruder and a twin screw extruder, etc. can be mention | raise | lifted.

  Next, the molten waste plastic is supplied to the thermal decomposition pot 11a and thermally decomposed into a decomposition gas. This pyrolysis pot 11a constitutes a pyrolysis furnace 11 together with a combustion furnace 11b that heats it, and the temperature of the pyrolysis pot 11a is adjusted by the combustion furnace 11b. An agitator (not shown) for agitating the molten waste plastic is provided inside the pyrolysis kettle 11a, so that the temperature inside the pyrolysis kettle 11a is made substantially uniform.

  The thermal decomposition temperature under almost atmospheric pressure is preferably 370 ° C. or higher, and preferably 380 ° C. or higher. When it is lower than 370 ° C., it may be difficult to sufficiently thermally decompose the molten waste plastic. On the other hand, the upper limit of the thermal decomposition temperature is preferably 400 ° C, and preferably 390 ° C. When the temperature is higher than 400 ° C., carbonization occurs and the yield of the regenerated oil may be deteriorated, and carbides are accumulated in the pyrolysis vessel 11a.

  A liquid level measuring unit is provided for controlling the liquid level of the molten waste plastic in the pyrolysis vessel 11a (hereinafter sometimes simply referred to as “liquid level”). This liquid level measurement unit can control the position of the liquid level to be within a predetermined range. For this reason, the amount of heat applied to the molten waste plastic in the pyrolysis kettle 11a becomes substantially constant, and the pyrolysis reaction can be performed stably.

  As shown in FIG. 2, the liquid level measuring unit has a plurality of thermometers 31 and the temperature measuring units of these thermometers 31 are arranged at different positions in the height direction. It is. In the pyrolysis vessel 11a, there is a difference in temperature between the liquid phase portion made of liquid molten waste plastic and the gas phase portion above the liquid phase portion. For this reason, the temperature of each thermometer 31 can be monitored, and the position of the liquid level can be grasped by the change in temperature. Then, the supply of the molten waste plastic is controlled by the position of the liquid level, that is, when the liquid level falls below a predetermined range, the supply of the molten waste plastic is increased, and conversely, the liquid level is within a predetermined range. If it rises further, the position of the said liquid level can be hold | maintained in the predetermined range by reducing the supply of the said thermal decomposition of the said molten waste plastic.

The thermometer 31 may be any thermometer that can measure temperature, such as a thermocouple.
The number of the thermometers installed may be plural, that is, two or more, and three or more are preferable in terms of confirmation of temperature change. Moreover, the upper limit of the number of thermometers installed is sufficient if it is five.

  Below, the specific example of a liquid level measurement part is demonstrated using FIG. In FIG. 2, three thermometers (31a, 31b, 31c) are used. A temperature measuring unit of a thermometer 31b is disposed at a target liquid level position (hereinafter referred to as “reference plane”) 32 of the molten waste plastic, and a distance a above the reference plane 32. A temperature measurement unit of the thermometer 31a is arranged at a position separated by a distance c, and a temperature measurement unit of the thermometer 31c is arranged at a position separated by a distance c below the reference plane 32.

  The inside of the pyrolysis pot 11a is in a high temperature state. The temperature of the liquid phase part is higher than that of the upper gas phase part. For this reason, when the liquid level is above the temperature measurement part of the thermometer 31a, that is, when the temperature measurement part of the total thermometer 31 is immersed in the liquid phase part, the temperature indicated in each thermometer is: It becomes the temperature of the molten waste plastic.

  In this state, when the supply of the molten waste plastic is decreased, the molten waste plastic is thermally decomposed and gasified, so that the liquid level is lowered. And the temperature measurement part of the thermometer 31a comes out above the said liquid level, and moves to a gaseous-phase part. At this time, the temperature indicated by the thermometer 31a temporarily decreases. Thereby, it can be grasped that the position of the liquid surface is at a position below the temperature measuring part of the thermometer 31a.

  Subsequently, when the supply of the molten waste plastic is continuously reduced, the liquid level gradually decreases, and the temperature measuring part of the thermometer 31b comes out above the liquid level and moves to the gas phase part. At this time, the temperature indicated by the thermometer 31b temporarily decreases. Thereby, it can be grasped that the position of the liquid surface is at a temperature measurement part of the thermometer 31b, that is, a position below the reference surface.

  Subsequently, when the supply of the molten waste plastic is continuously reduced, the liquid level further decreases, and the temperature measuring part of the thermometer 31c comes out above the liquid level and moves to the gas phase part. At this time, the temperature indicated by the thermometer 31c temporarily decreases. Thereby, it can be grasped that the position of the liquid surface is at a position below the temperature measuring part of the thermometer 31c.

  When the amount of the molten waste plastic is increased in this state, the temperature measuring part of the thermometer 31c is located below the liquid surface and moves to the liquid phase part. At this time, the temperature indicated by the thermometer 31c temporarily rises. Thereby, it can be grasped that the position of the liquid level is located above the temperature measuring part of the thermometer 31c.

  Subsequently, when the amount of the molten waste plastic is continuously increased, the temperature measuring part of the thermometer 31b is positioned below the liquid surface and moves to the liquid phase part. At this time, the temperature indicated by the thermometer 31b temporarily rises. Thereby, it can be grasped that the position of the liquid surface is at a temperature measurement part of the thermometer 31b, that is, a position above the reference surface.

  Further, when the amount of the molten waste plastic is continuously increased, the temperature measuring part of the thermometer 31a is located below the liquid level and moves to the liquid phase part. At this time, the temperature indicated by the thermometer 31a temporarily rises. Thereby, it can be grasped that the position of the liquid level is located above the temperature measuring part of the thermometer 31a.

  When this state is reached, the supply of the molten waste plastic is stopped. By repeating these steps, the liquid level goes back and forth between the vicinity of the temperature measurement unit of the thermometer 31a and the vicinity of the temperature measurement unit of the thermometer 31c, and the liquid level is maintained within this range. Is possible.

  The distance between the temperature measurement part of the thermometer 31a and the temperature measurement part of the thermometer 31c, that is, a + c, generally speaking, the temperature measurement part of the thermometer to be measured that is the uppermost from the reference plane; The measurement target range distance, which is the distance to the temperature measurement part of the thermometer that is the lowest part from the reference plane, is the range that does not affect the efficiency of the thermal decomposition reaction as the width of the blurring of the interface, Can be set.

  Specifically, the measurement target range distance is preferably 600 mm or less, and preferably 550 mm or less. If it is larger than 600 mm, the upper vapor phase temperature in the pyrolysis kettle is measured, which may cause a problem that the temperature change cannot be confirmed. On the other hand, the lower limit of the measurement target range distance is specifically 300 mm or more, and preferably 200 mm. If it is smaller than 200 mm, a stirrer is used, so measurement is impossible if the distance is too short. In addition, there may be a problem that the temperature difference is not clear unless there is a certain distance.

In FIG. 2, an odd number of thermometers are used, but an even number of thermometers may be used. In the case of using an even number of thermometers, if the reference plane is arranged between the temperature measuring parts of two thermometers with the temperature measuring part at the center, two gas phase thermometers are provided. Shows substantially the same value, and the same thing occurs in two thermometers in the liquid phase portion, so that it is clearer where the reference plane is located.
In FIG. 2, three thermometers are used. However, in consideration of the fine control of the liquid level fluctuation, it is preferable to use five or less thermometers, and four or less thermometers are used. Is preferred. On the other hand, the lower limit of the thermometer to be used is two.

The cracked gas obtained in the pyrolysis kettle 11a is sent to the condenser 12. And the decomposition gas which can be liquefied here is liquefied. Next, the gas-liquid separator 16 separates the gas and liquid, and the gas component is purified by the purifier 17 and released as exhaust.
On the other hand, the regenerated oil P which is a liquid component is stored in the liquid storage tank 18 and used as a product.

  By the way, the cracked gas obtained in the pyrolysis vessel 11a may be sent to the reflux tower 15 as shown in FIG. 3 before being sent to the condenser 12. By sending the cracked gas 11 to the reflux tower 15, the cracked gas 11 is refluxed. As a result, high boiling components such as a wax component that comes with the cracked gas are returned to the lower pyrolysis pot 11a. The reflux tower 15 may have a state in which reflux occurs, that is, a state in which the cracked gas and the liquefied gas of the cracked gas counter-flow. Examples thereof include a method of setting the height to such a level that the above-described object can be achieved, a method of cooling the reflux tower 15 to such an extent that the temperature inside the reflux tower 15 can enable liquefaction of the cracked gas, and the like. Moreover, you may fill the inside of the reflux tower 15 with a filler as needed. By using the packing material, the height of the reflux tower can be set low and the degree of cooling can be lowered.

  Furthermore, as shown in FIG. 3, a part of the regenerated oil P that is a product stored in a liquid storage tank 18 to be described later may be extracted and cooled by the condenser 21, and then returned to the upper part of the reflux tower 15. . By doing in this way, it becomes possible to cool the cracked gas which went up to the reflux tower 15 by making direct contact with the regenerated oil P which is a product. The amount and temperature of the reclaimed oil P to be returned are appropriately selected according to the recovered amount of reclaimed oil, the amount of high boiling components contained in the reclaimed oil, the target degree of cooling, and the like. And by doing in this way, the effect of the cooling in the reflux tower 15 can be improved more, and the separation from the decomposition gas of a high boiling component can be made easier.

  The filler may be regular packing or irregular packing. The regular packing is preferable because it can keep the reflux state constant and can further reduce the pressure loss. This ordered packing has a large number of holes, and a flat plate or a net-like body having a large number of holes is processed into a cylindrical shape or a tower shape. And this regular packing is used in accordance with the diameter and height of the reflux tower 15. Examples of such regular packing include MC pack (manufactured by Matsui Machine Co., Ltd.) and the like.

  In the reflux tower 15, the liquid high-boiling component and the liquefied cracked gas are returned to the lower pyrolysis tank 11 a, while the remaining cracked gas is sent to the condenser 12.

  When the cooling effect in the condenser 12 is insufficient, there is a possibility that the decomposition gas in the gas state goes to the purification device 17. When this state may occur, as shown in FIG. 3, a part of the regenerated oil P, which is a product stored in the liquid storage tank 18, is extracted and cooled by the condenser 21. To the pipe to the condenser 12. By doing in this way, the cracked gas sent to the condenser 12 is cooled by the direct contact with the regenerated oil P, and cooling in the condenser 12 can be assisted. The amount and temperature of the reclaimed oil P to be returned are appropriately selected according to the recovered amount of reclaimed oil, the amount of high boiling components contained in the reclaimed oil, the target degree of cooling, and the like.

  By the way, when the high-temperature decomposition gas enters the condenser 12 as it is, there is a possibility that adhesion occurs on the inner surface of the heat exchange tube of the condenser 12 at the same time as liquefaction. Furthermore, in some cases, carbonization may occur if a high temperature state is maintained. In such a case, the inside of the condenser 12 needs to be cleaned, but it may not be removed by simple cleaning, and may need to be scraped off. On the other hand, a part of the cooled regenerated oil P is branched and allowed to flow in the form of a spray to the condenser 12 so that the high temperature gas and the cooled regenerated oil are brought into direct contact with each other, thereby reducing the temperature of the cracked gas. It is possible to prevent adhesion and carbonization to the inner surface of the heat exchange tube of the condenser 12.

  Further, when the cooling effect in the condenser 12 is insufficient, or when it is desired to adjust the components of the reclaimed oil P to be recovered, the second condenser and the second condenser are connected from the gas-liquid separation device 16 to the piping of the purification device 17. Two gas-liquid separators may be provided. If it does in this way, when the cooling effect in the said condenser 12 is inadequate, it will be possible to cool again and the reproduction | regeneration oil P will be more reliably recoverable.

  Further, in this case, when the component of the regenerated oil P to be recovered is to be adjusted, the cooling temperature of the condenser 12 and the second condenser is set to different temperatures, and the cooling temperature of the condenser 12 is further increased, The recycled oil liquefied by the condenser 12 and collected in the liquid storage tank 18 is liquefied by the second condenser, and the component having a higher boiling point than the recycled oil collected in the second liquid storage tank is collected. This makes it possible to produce reclaimed oil according to the purpose of use.

By the way, air or the like is used as the refrigerant of the condenser 12. If a part of the air or the like heated by the condenser 12 is used as hot air for drying in the cleaning / drying step 13, It is preferable from the viewpoint.
In addition, when a part of the regenerated oil P that is a product is used as a part of the combustion raw material of the combustion furnace 11b, consumption of external energy can be saved, and energy saving can be achieved in the whole apparatus.

When the regenerated oil P is produced by the above-described method, a residue is accumulated in the pyrolysis vessel 11a. For this reason, it is necessary to cool the pyrolysis kettle 11a at a timing at which the thermal decomposition efficiency of the waste plastic M in the pyrolysis kettle 11a is not lowered so much that the internal residue is taken out together with the molten waste plastic M. In this case, natural cooling may be performed. However, when the pyrolysis pot 11a is large, cooling takes time, which is not efficient. In such a case, as shown in FIG. 4, it is preferable to connect a cooling unit for cooling the internal gas of the pyrolysis vessel 11a to the pyrolysis vessel 11a.
The cooling unit includes a condenser 22 for cooling the internal gas of the pyrolysis kettle 11a, a lead-out line for sending the internal gas of the pyrolysis kettle 11a to the condenser 22, and the internal gas cooled by the condenser 22 It has an introduction line that returns to the pyrolysis kettle 11a.
When operating this cooling unit, first, the combustion furnace 11b is temporarily stopped, and the heating of the pyrolysis pot 11a is temporarily stopped. Next, the internal gas of the pyrolysis vessel 11a is sent to the condenser 22 via the lead-out line. And after cooling internal gas with the condenser 22, this cooled internal gas is returned to the thermal decomposition pot 11a via the said introduction line.
This operation is preferable because the inside of the pyrolysis pot 11a can be forcibly cooled and the cooling time can be shortened. At this time, it is preferable to add a small amount of nitrogen gas (N ₂ ) to the positive pressure through a pipe from the pyrolysis kettle 11 a to the condenser 22. If it does in that way, the subsequent piping will become a negative pressure by cooling with the condenser 22, and it can prevent that air, especially oxygen enter. This is because when oxygen intrudes, the temperature is high and oxidation may occur.
In addition, since the residue in the pyrolysis pot 11a is a carbide | carbonized_material, it is better to cool as much as possible.

  When the waste plastic oil treatment apparatus according to the present invention is used, recycled oil can be obtained from waste plastic that has been conventionally discarded and burned, and a new energy source can be obtained.

Hereinafter, the present invention will be described more specifically with reference to examples.
[Example 1]
In the flowchart shown in FIG. 1, the flow after the pyrolysis pot 11a was used. The pyrolysis furnace 11 used a reaction kettle with an internal volume of 1 liter as the pyrolysis kettle 11a shown in FIG. 2, and a mantle heater as the combustion furnace 11b. And the part of the reaction kettle not covered with the mantle heater including the upper part of the reaction kettle was covered with a heat insulating material.
In addition, three thermometers are used, and a temperature measuring unit of one thermometer (hereinafter referred to as “central thermometer”) is arranged on the reference surface, and another thermometer (hereinafter referred to as “15 mm” above the reference surface). And a temperature measuring unit of the remaining thermometer (hereinafter referred to as “lower thermometer”) 15 mm below the reference plane.

First, 750 g of polypropylene chips were charged as waste plastic in the reaction kettle.
Next, the mantle heater was set to 470 ° C., and the waste plastic was melted while heating. At this time, 0.2 L / min of nitrogen gas was flowed into the pyrolysis vessel 11a as a carrier gas. The stirrer was not rotated.

The heater temperature and the temperature of each thermometer varied as shown in Table 1. The waste plastic started to melt around 60 minutes, and the waste plastic almost melted around 90 minutes. At about 210 minutes, all the thermometers became around 350 ° C. or higher, so it was considered that the waste plastic was completely dissolved, and the mantle heater was once cut off.
After 240 minutes, the temperature of all thermometers was close to normal temperature, so the mantle heater was set to 470 ° C. and heating was started again.

After 360 minutes, the temperature of the lower thermometer exceeded 300 ° C, the temperature of the middle thermometer became 300 ° C, and after 420 minutes, the temperature of the upper thermometer exceeded 300 ° C.
And after 480 minutes passed, after the temperature of the upper thermometer showed 344 degreeC, after 510 minutes passed, it showed 330 degreeC and the fall of 14 degreeC was seen. At this stage, the upper thermometer is considered to be separated from the liquid phase part.

Next, after 510 minutes, the temperature of the central thermometer showed 368 ° C., after 540 minutes, it showed 357 ° C., and a decrease of 11 ° C. was observed. At this stage, the middle thermometer is considered to be separated from the liquid phase part.
And after 540 minutes passed, after the temperature of the lower thermometer showed 379 degreeC, after 570 minutes passed, it showed 367 degreeC and the fall of 12 degreeC was seen. At this stage, the lower thermometer is considered to be separated from the liquid phase part.

Thereafter, the temperature indicated by each thermometer started to rise.
Therefore, it was confirmed that when the temperature measurement part of each thermometer shifts from the liquid phase part to the gas phase part, the temperature decreases by 10 ° C. or more.
The reclaimed oil obtained in this experiment has a low content of high boiling components such as wax, and it is assumed that the molten waste plastic was thermally decomposed stably.
In addition, the regenerated oil obtained by this operation is not different from the conventional one, and the residue of the pyrolysis vessel 11a is 2 to 3% of the raw material weight, which is not different from the conventional one.
The changes in time and temperature are summarized in Table 1 below.

DESCRIPTION OF SYMBOLS 11 Pyrolysis furnace 11a Pyrolysis pot 11b Combustion furnace 12 Condenser 13 Washing and drying process 14 Liquefaction process 15 Reflux tower 16 Gas-liquid separation apparatus 17 Purification apparatus 18 Liquid storage tank 21 Condenser 22 Condenser M Waste plastic P Recycled oil

Claims (8)

It is a waste plastic oil processing apparatus having a condenser that thermally decomposes waste plastic to generate cracked gas, and a condenser that cools and liquefies the cracked gas obtained in the thermal cracking pot to obtain recycled oil,
The pyrolysis kettle is supplied with molten waste plastic,
A liquid level measuring unit for controlling the liquid level of the molten waste plastic in the pyrolysis kettle,
The liquid level measuring unit has a plurality of thermometers, and the temperature measuring units of these thermometers are arranged at different positions in the height direction, and the liquid level is measured by changing the temperature of each thermometer. Is a control unit that keeps the position of the liquid level of the molten waste plastic in the pyrolysis kettle within a predetermined range by controlling the supply of the molten waste plastic.
Waste plastic oil processing equipment characterized by the above.   A reflux tower for refluxing the cracked gas obtained in the pyrolysis kettle is provided above the pyrolysis kettle, and the high boiling component in the cracked gas is returned to the pyrolysis kettle. The waste plastic oil processing apparatus as described.   The waste plastic oil processing apparatus according to claim 2, wherein a part of the regenerated oil obtained in the condenser is cooled and returned to at least one of the reflux tower and a pipe between the reflux tower and the condenser. The pyrolysis kettle is connected to a cooling unit for cooling the internal gas of the pyrolysis kettle,
The cooling unit includes a condenser for cooling the internal gas of the pyrolysis kettle, a lead-out line for sending the internal gas of the pyrolysis kettle to the condenser, and the internal gas cooled by the condenser. The waste plastic oil converting apparatus according to any one of claims 1 to 3, further comprising an introduction line for returning to the pyrolysis kettle. Supply molten plastic to the pyrolysis kettle,
The liquid level of the molten waste plastic in the pyrolysis kettle is controlled by a liquid level measuring unit,
The liquid level measuring unit has a plurality of thermometers, and the temperature measuring units of these thermometers are arranged at different positions in the height direction, and the liquid level is measured by changing the temperature of each thermometer. And controlling the supply of the molten waste plastic to control the position of the liquid level of the molten waste plastic in the pyrolysis kettle within a predetermined range,
The molten waste plastic is pyrolyzed with the pyrolysis kettle,
A method for producing recycled oil from waste plastic, wherein the cracked gas obtained by the thermal decomposition is cooled by the condenser to obtain recycled oil.   The waste gas according to claim 5, wherein the cracked gas obtained by the pyrolysis is refluxed in a reflux tower provided above the pyrolysis kettle, and the cracked gas discharged from the reflux tower is sent to the condenser. A method for producing reclaimed oil.   A part of the regenerated oil obtained in the condenser is cooled and returned to at least one of the reflux tower and the pipe between the reflux tower and the condenser, and the cracked gas in the reflux tower, or in the pipe A method for producing reclaimed oil from waste plastics according to claim 6, which is brought into direct contact with the cracked gas. When removing the reclaimed oil, in order to remove the residue accumulated in the pyrolysis kettle,
Temporarily stops heating the pyrolysis kettle,
Send the internal gas of the pyrolysis kettle to the condenser via the outlet line,
Cooling the internal gas with the condenser;
The recycled oil is produced from the waste plastic according to any one of claims 5 to 7, wherein the inside of the pyrolysis kettle is cooled by returning the cooled internal gas to the pyrolysis kettle via an introduction line. Method.

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