Mixing device

Abstract

To provide a mixing device capable of reusing more working fluid.SOLUTION: A mixing device comprises a manufacturing unit 2 which manufactures supercritical CO2, a mixing unit 3 which mixes materials under supercritical CO2, a return flow path 4 which circulates CO2 gas separated from the materials after mixing in the mixing unit 3, and a storage tank 5 which is provided in the return flow path 4, and stores CO2 gas separated from the materials. The upstream end of the return flow path 4 is connected to the mixing unit 3, and the downstream end of the return flow path 4 is connected to the manufacturing unit 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a kneading device that kneads materials in the presence of a working fluid in a supercritical or subcritical state. [Background technology]

[0002] Patent Document 1 discloses a mixer that mixes (kneads) materials in the presence of a working fluid in a supercritical or subcritical state. In this mixer, the working fluid separated from the materials after kneading in the mixing section is decompressed and returned to a production section that produces a working fluid in a supercritical or subcritical state, thereby reusing the working fluid used during kneading. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-84752 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, only the amount of working fluid that can be reused until the pressure in the system reaches equilibrium can be reused, and the excess working fluid is released into the atmosphere. Thus, there is a limit to the amount of working fluid that can be reused.

[0005] An object of the present invention is to provide a kneading device that is capable of reusing a larger amount of working fluid. [Means for solving the problem]

[0006] The present invention is characterized in that it comprises a production unit that produces a working fluid in a supercritical or subcritical state, a kneading unit that kneads materials in the presence of the working fluid in a supercritical or subcritical state, a return flow path through which the working fluid separated from the materials after kneading in the kneading unit flows, and a storage tank that is provided in the return flow path and stores the working fluid separated from the materials, and the upstream end of the return flow path is connected to the kneading unit and the downstream end of the return flow path is connected to the production unit. [Effects of the Invention]

[0007] According to the present invention, the working fluid separated from the material is stored in a storage tank provided in the return flow path. In a configuration in which a storage tank is not provided in the return flow path, only the amount of working fluid until the pressure in the system is equilibrated can be reused, and the excess working fluid is released into the atmosphere. In contrast, in a configuration in which a storage tank is provided in the return flow path, the working fluid separated from the material can be temporarily stored in the storage tank and returned to the manufacturing department as appropriate. This reduces the amount of working fluid released into the atmosphere. Therefore, more working fluid can be reused. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a kneading device of a first embodiment. [Figure 2] FIG. 4 is a block diagram showing a kneading device according to a second embodiment. [Figure 3A] FIG. 1 is a diagram showing a conventional process for decompressing supercritical CO2 discharged from a kneader. [Figure 3B] FIG. 10 is a process diagram of a second embodiment in which the supercritical CO2 discharged from the inside of the kneader is not decompressed. [Figure 4] 10 is a flowchart of kneading control in the second embodiment. [Figure 5] FIG. 10 is a block diagram showing a kneading device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0010] [First embodiment] (Configuration of the kneading device) The kneading device according to the first embodiment of the present invention kneads materials in the presence of a working fluid in a supercritical or subcritical state. In this embodiment, the material is rubber, but it may also be resin, food, or the like. The kneading device of this embodiment kneads in a batch manner.

[0011] Here, the supercritical state refers to a state in which the temperature is equal to or higher than the critical temperature of the working fluid and the pressure is equal to or higher than the critical pressure of the working fluid, whereas the subcritical state refers to a state in which only one of the temperature and pressure has reached the critical state and the other has not reached the critical state, or a state in which neither the temperature nor the pressure has reached the critical state but at least one of the temperature and pressure is sufficiently higher than normal temperature and normal pressure and is close to the critical state.

[0012] Examples of substances that constitute the working fluid include carbon dioxide, nitrogen, hydrogen, xenon, ethane, ammonia, methanol, water, etc. Of these, carbon dioxide and nitrogen are suitable for kneading rubber.

[0013] In this embodiment, carbon dioxide (CO2) is used as the working fluid, and kneading is performed in the presence of carbon dioxide in a supercritical state (supercritical CO2). Note that kneading may also be performed in the presence of another working fluid in a supercritical state or in the presence of a working fluid in a subcritical state.

[0014] As shown in FIG. 1, which is a block diagram showing a kneading device 1, the kneading device 1 has a production section 2 and a kneading section 3.

[0015] The production unit 2 produces supercritical CO2. The production unit 2 has a tank 11, a first heat exchanger 12, a pump 13, and a second heat exchanger .

[0016] The tank 11 stores CO2 gas. The first heat exchanger 12 cools the CO2 gas supplied from the tank 11 to turn it into liquid CO2 (liquid CO2).

[0017] The pump 13 pressurizes the liquid CO2. The pump 13 can be made smaller when pressurizing the liquid CO2 than when pressurizing the CO2 gas. The pump 13 pumps the pressurized liquid CO2 downstream.

[0018] The second heat exchanger 14 heats the pressurized liquid CO2 to vaporize it. The second heat exchanger 14 pressurizes the CO2 by vaporizing the liquid CO2 within the container. This converts the CO2 into supercritical CO2. A check valve 16 is provided in the liquid flow path 15 connecting the pump 13 and the second heat exchanger 14 to prevent backflow of the liquid CO2.

[0019] The kneading section 3 kneads the materials in the presence of supercritical CO 2. The kneading section 3 has a kneader 21, a first adjusting valve 22, and a separation filter 23.

[0020] Materials and additives are supplied to a supply flow path 17 that connects the production unit 2 and the kneading unit 3. The materials and additives supplied to the supply flow path 17 are transferred into a kneader 21 together with supercritical CO2. A check valve 18 that prevents backflow of the supercritical CO2, materials, and additives is provided in the supply flow path 17. A second adjustment valve 24 that adjusts the amounts of supercritical CO2, materials, and additives supplied to the kneader 21 is provided between the kneader 21 and the check valve 18.

[0021] The kneader 21 kneads the materials and additives in the presence of supercritical CO2 inside. The materials and additives are dissolved in supercritical CO2, so they are kneaded quickly.

[0022] When the material is a polymer material such as rubber or resin, the additives are additives, kneaded rubber, plant-derived materials including cellulose nanofiber, etc. When the material is food, the additives are food additives, etc. Note that additives do not necessarily have to be used.

[0023] When mixing in the mixer 21 is completed, the mixture of the materials and additives is separated from the supercritical CO2 within the mixer 21. The mixture is discharged from the mixer 21. The first adjustment valve 22 adjusts the flow rate of the supercritical CO2 discharged from the mixer 21. In this embodiment, the first adjustment valve 22 reduces the pressure of the supercritical CO2 discharged from the mixer 21 to form CO2 gas. The separation filter 23 separates the additives remaining in the CO2 gas.

[0024] The kneading device 1 also has a return flow path 4 and a storage tank 5. CO2 gas separated from the kneaded product after the materials are kneaded flows through the return flow path 4. The upstream end of the return flow path 4 is connected to the kneading section 3. Specifically, the upstream end of the return flow path 4 is connected to the separation filter 23 of the kneading section 3. The downstream end of the return flow path 4 is connected to the production section 2. In this embodiment, the downstream end of the return flow path 4 is connected to a gas flow path 19 that connects the tank 11 and the first heat exchanger 12.

[0025] The storage tank 5 is provided in the return flow path 4. The storage tank 5 stores the CO2 gas separated from the kneaded material. A check valve 25 that prevents backflow of CO2 gas is provided in the return flow path 4 upstream of the storage tank 5. A third adjustment valve 26 that adjusts the flow rate of CO2 gas flowing through the return flow path 4 is provided in the return flow path 4 between the storage tank 5 and the production unit 2.

[0026] The CO2 gas separated from the kneaded material in the kneading section 3 is returned to the production section 2 through the return flow path 4. This allows the CO2 gas separated from the kneaded material to be reused.

[0027] In addition, the CO2 gas separated from the kneaded material is stored in a storage tank 5 provided in the return flow path 4. In a configuration in which the storage tank 5 is not provided in the return flow path 4, only the amount of CO2 gas until the pressure in the system is equilibrated can be reused, and the excess CO2 gas is released into the atmosphere. In contrast, in a configuration in which the storage tank 5 is provided in the return flow path 4, the CO2 gas separated from the kneaded material can be temporarily stored in the storage tank 5 and returned to the production section 2 as appropriate. This makes it possible to reduce the amount of CO2 gas released into the atmosphere. Therefore, more CO2 gas can be reused.

[0028] (effect) As described above, in the kneading device 1 according to this embodiment, the CO2 gas separated from the kneaded material is stored in the storage tank 5 provided in the return flow path 4. In a configuration in which the storage tank 5 is not provided in the return flow path 4, only the amount of CO2 gas until the pressure in the system is equilibrated can be reused, and the excess CO2 gas is released to the atmosphere. In contrast, in a configuration in which the storage tank 5 is provided in the return flow path 4, the CO2 gas separated from the kneaded material can be temporarily stored in the storage tank 5 and returned to the production section 2 as appropriate. This makes it possible to reduce the amount of CO2 gas released to the atmosphere. Therefore, more CO2 gas can be reused.

[0029] [Second embodiment] Next, a kneading device of a second embodiment will be described with reference to the drawings. Note that a description of the configuration common to the first embodiment and the effects achieved thereby will be omitted, and the following mainly describes the differences from the first embodiment. Note that the same members as in the first embodiment are assigned the same reference numerals as in the first embodiment.

[0030] (Configuration of the kneading device) FIG. 2 shows a block diagram of a kneading device 101 of this embodiment. In the first embodiment, the first regulating valve 22 reduced the pressure of supercritical CO2 discharged from the kneader 21 to form CO2 gas. This resulted in energy loss due to the pressure drop. The first regulating valve 22 of this embodiment allows supercritical CO2 to circulate as is without reducing the pressure. Therefore, supercritical CO2 separated from the kneaded material flows into the storage tank 5. The CO2 stored in the storage tank 5 is CO2 gas whose temperature and pressure are lower than those of supercritical CO2, or supercritical CO2.

[0031] In this embodiment, the downstream end of the return flow path 4 is connected to a liquid flow path 15 that connects the pump 13 and the second heat exchanger 14. Specifically, the downstream end of the return flow path 4 is connected to a portion of the liquid flow path 15 that is downstream of the check valve 16.

[0032] In this way, the supercritical CO2 separated from the kneaded material flows into the storage tank 5. As a result, the pressure of the CO2 gas or supercritical CO2 stored in the storage tank 5 becomes higher than atmospheric pressure. The CO2 gas or supercritical CO2 stored in the storage tank 5 is returned downstream of the pump 13 and upstream of the second heat exchanger 14. When CO2 gas is stored in the storage tank 5, the CO2 gas, which has a pressure higher than atmospheric pressure, can be easily converted into supercritical CO2 by heating and pressurizing it in the second heat exchanger 14. This reduces the power of the pump 13 and shortens the time required for pressure increase. On the other hand, when supercritical CO2 is stored in the storage tank 5, the supercritical CO2 can be supplied directly to the kneading section 3, thereby almost eliminating the power of the pump 13 and the time required for pressure increase.

[0033] The kneading device 101 of this embodiment also has a recovery pump 6. The recovery pump 6 is provided in the return flow path 4, upstream of the storage tank 5. The recovery pump 6 sucks the supercritical CO2 in the kneading section 3. The recovery pump 6 also pressurizes the supercritical CO2 circulating through the return flow path 4. The power required for the recovery pump 6 to suck supercritical CO2 can be reduced compared to sucking CO2 gas.

[0034] A fourth adjustment valve 31 is provided in the return flow path 4 upstream of the recovery pump 6 to adjust the flow rate of supercritical CO2 flowing into the recovery pump 6. In addition, a check valve 32 is provided in the return flow path 4 downstream of the recovery pump 6 to prevent backflow of supercritical CO2 flowing through the return flow path 4. A branch flow path 33 branches off from the return flow path 4 upstream of the check valve 32, and a fifth adjustment valve 34 is provided in this branch flow path 33 to adjust the flow rate of supercritical CO2 flowing through the branch flow path 33.

[0035] Furthermore, a bypass flow path 35 branches off from the return flow path 4 upstream of the fourth adjustment valve 31, and the downstream end of this bypass flow path 35 is connected to a portion of the return flow path 4 downstream of the check valve 32 and upstream of the check valve 25. The bypass flow path 35 is provided with a sixth adjustment valve 36 that adjusts the flow rate of supercritical CO2 flowing through the bypass flow path 35.

[0036] Therefore, when the sixth adjustment valve 36 is opened and the fourth adjustment valve 31 is closed, the supercritical CO2 separated from the kneaded material passes through the bypass flow path 35 and flows into the storage tank 5. On the other hand, when the sixth adjustment valve 36 is closed and the fourth adjustment valve 31 is opened, the supercritical CO2 separated from the kneaded material is sucked by the recovery pump 6 and passes through the return flow path 4. In this case, when the fifth adjustment valve 34 is closed, the supercritical CO2 sucked by the recovery pump 6 flows into the storage tank 5. On the other hand, when the fifth adjustment valve 34 is open, the supercritical CO2 sucked by the recovery pump 6 is released into the atmosphere through the branch flow path 33.

[0037] In this way, when the sixth adjustment valve 36 is closed and the fourth adjustment valve 31 is opened, the supercritical CO2 in the kneading section 3 is sucked by the recovery pump 6. This makes it possible to recover the supercritical CO2 remaining in the kneading section 3.

[0038] The kneading device 101 also has a heater 7. The heater 7 is provided in the storage tank 5 and heats the inside of the storage tank 5.

[0039] The CO2 gas or supercritical CO2 stored in the storage tank 5 is heated by the heater 7. The CO2 gas or supercritical CO2 stored in the storage tank 5 is returned downstream of the pump 13 and upstream of the second heat exchanger 14. When CO2 gas is stored in the storage tank 5, the CO2 gas, which has a pressure higher than atmospheric pressure and a temperature higher than atmospheric temperature, can be easily converted into supercritical CO2 by heating and pressurizing it in the second heat exchanger 14. This reduces the time required for heating. On the other hand, when supercritical CO2 is stored in the storage tank 5, it can be supplied directly to the kneading section 3, thereby almost eliminating the time required for heating.

[0040] (Manufacturing department operating rate) Next, the operating rate of the production section 2 will be described. FIG. 3A shows a conventional process diagram in which the supercritical CO2 discharged from the kneader 21 is depressurized. FIG. 3B shows a process diagram of this embodiment in which the supercritical CO2 discharged from the kneader 21 is not depressurized. One batch consists of material charging, pressurization, kneading, and devolatilization. Devolatilization refers to the removal of volatile components. Batches are repeatedly performed in the kneading section 3.

[0041] In this embodiment, by flowing supercritical CO into the storage tank 5, the pressure of the CO gas or supercritical CO stored in the storage tank 5 becomes higher than atmospheric pressure. When CO gas is stored in the storage tank 5, the CO gas stored in the storage tank 5 is heated and pressurized in the second heat exchanger 14, so that the CO gas easily becomes supercritical CO. As a result, in the process of this embodiment, the time required for pressure increase is shorter than in conventional processes. On the other hand, when supercritical CO is stored in the storage tank 5, the time required for pressure increase can be almost eliminated by supplying the supercritical CO directly to the kneading section 3. As a result, the number of batches per unit time can be increased.

[0042] (Operation of the kneading device) Next, the operation of the kneading device 101 will be described with reference to FIG. 4, which is a flowchart of kneading control.

[0043] First, the third regulating valve 26 is opened (step S1). At this time, the first regulating valve 22 is closed and the second regulating valve 24 is open. Then, it is determined whether the pressures in the kneader 21 and the storage tank 5 have become equal (step S2). If it is determined in step S2 that the pressures in the kneader 21 and the storage tank 5 have not become equal (S2: NO), step S2 is repeated. On the other hand, if it is determined in step S2 that the pressures in the kneader 21 and the storage tank 5 have become equal (S2: YES), the third regulating valve 26 is closed (step S3).

[0044] Next, the pump 13 is operated (Step S4). Then, it is determined whether the pressure inside the kneader 21 has reached the desired pressure (Step S5). If it is determined in Step S5 that the pressure inside the kneader 21 has not reached the desired pressure (S5: NO), Step S5 is repeated. On the other hand, if it is determined in Step S5 that the pressure inside the kneader 21 has reached the desired pressure (S5: YES), the second adjusting valve 24 is closed (Step S6) and the pump 13 is stopped (Step S7). Then, kneading is performed in the kneader 21 (Step S8).

[0045] Next, the sixth adjustment valve 36 is opened, and the fourth adjustment valve 31 is closed (step S9). Then, the first adjustment valve 22 is opened (step S10). As a result, the supercritical CO2 separated from the kneaded material passes through the bypass flow path 35 and flows into the storage tank 5.

[0046] Next, it is determined whether the pressures in the kneader 21 and the storage tank 5 have become equal (Step S11). If it is determined in Step S11 that the pressures in the kneader 21 and the storage tank 5 have not become equal (S11: NO), Step S11 is repeated. On the other hand, if it is determined in Step S11 that the pressures in the kneader 21 and the storage tank 5 have become equal (S11: YES), the sixth adjustment valve 36 is closed and the fourth adjustment valve 31 is opened (Step S12). Then, the recovery pump 6 is operated (Step S13). At this time, the fifth adjustment valve 34 is closed. As a result, the supercritical CO2 separated from the kneaded material is sucked by the recovery pump 6, passes through the return flow path 4, and flows into the storage tank 5.

[0047] Next, it is determined whether or not a vacuum exists inside the kneader 21 (Step S14). If it is determined in Step S14 that a vacuum does not exist inside the kneader 21 (S14: NO), Step S14 is repeated. On the other hand, if it is determined in Step S14 that a vacuum exists inside the kneader 21 (S14: YES), the kneaded material is discharged from the kneader 21 (Step S15).

[0048] Next, the fifth adjustment valve 34 is opened (step S16). As a result, the inside of the kneader 21 is evacuated by the recovery pump 6. Then, it is determined whether or not a vacuum is created inside the kneader 21 (step S17). If it is determined in step S17 that a vacuum is not created inside the kneader 21 (S17: NO), step S17 is repeated. On the other hand, if it is determined in step S17 that a vacuum is created inside the kneader 21 (S17: YES), the first adjustment valve 22 is closed (step S18), the recovery pump 6 is stopped (step S19), and the fifth adjustment valve 34 is closed (step S20). Then, the second adjustment valve 24 is opened (step S21), and the material and additives are introduced into the supply passage 17 (step S22). Then, the process returns to step S1.

[0049] (effect) As described above, in the kneading device 101 according to this embodiment, supercritical CO2 separated from the kneaded material flows into the storage tank 5. As a result, the pressure of the CO2 gas or supercritical CO2 stored in the storage tank 5 becomes higher than atmospheric pressure. The CO2 gas or supercritical CO2 stored in the storage tank 5 is returned downstream of the pump 13 and upstream of the second heat exchanger 14. When CO2 gas is stored in the storage tank 5, the CO2 gas, which has a pressure higher than atmospheric pressure, can be easily converted into supercritical CO2 by heating and pressurizing it in the second heat exchanger 14. This reduces the power required for the pump 13 and shortens the time required for pressure increase. On the other hand, when supercritical CO2 is stored in the storage tank 5, the supercritical CO2 can be supplied directly to the kneading section 3, thereby substantially eliminating the power required for the pump 13 and the time required for pressure increase.

[0050] Furthermore, the CO2 gas or supercritical CO2 stored in the storage tank 5 is heated by the heater 7. The CO2 gas or supercritical CO2 stored in the storage tank 5 is returned downstream of the pump 13 and upstream of the second heat exchanger 14. When CO2 gas is stored in the storage tank 5, the CO2 gas, which has a pressure higher than atmospheric pressure and a temperature higher than atmospheric temperature, can be easily converted into supercritical CO2 by heating and pressurizing it in the second heat exchanger 14. This reduces the time required for temperature increase. On the other hand, when supercritical CO2 is stored in the storage tank 5, the supercritical CO2 can be supplied directly to the kneading section 3, thereby almost eliminating the time required for temperature increase.

[0051] Furthermore, the supercritical CO2 in the kneading section 3 is sucked by the recovery pump 6. This allows the supercritical CO2 remaining in the kneading section 3 to be recovered.

[0052] [Third embodiment] Next, a kneading device of a third embodiment will be described with reference to the drawings. Note that a description of the configuration common to the second embodiment and the effects achieved thereby will be omitted, and the following mainly describes the differences from the second embodiment. Note that the same members as those in the second embodiment are assigned the same reference numerals as those in the second embodiment.

[0053] (Configuration of the kneading device) As shown in Fig. 5, which is a block diagram illustrating a kneading device 201 of this embodiment, the kneading device 201 of this embodiment has a bypass flow path 8. The bypass flow path 8 connects a portion of the supply flow path 17 upstream of the check valve 18 to a portion of the return flow path 4 upstream of the storage tank 5 and downstream of the recovery pump 6. Note that the branch flow path 33 and the detour flow path 35 are not shown in Fig. 5.

[0054] The supercritical CO2 produced in the production unit 2 flows through the bypass flow path 8. A check valve 27 that prevents the supercritical CO2 from flowing backward is provided upstream of the bypass flow path 8. Furthermore, a seventh adjustment valve 28 that adjusts the flow rate of the supercritical CO2 flowing through the bypass flow path 8 is provided downstream of the bypass flow path 8. The CO2 stored in the storage tank 5 is CO2 gas that has a lower temperature and pressure than supercritical CO2, or supercritical CO2. In this embodiment, the pressure of the CO2 gas or supercritical CO2 stored in the storage tank 5 is equal to or higher than the normal pressure of the kneader 21.

[0055] Supercritical CO2 produced in the production unit 2 flows into the storage tank 5 through the bypass flow path 8. In a conventional configuration without the bypass flow path 8, even if supercritical CO2 is produced while the kneading unit 3 is operating, it cannot be supplied to the kneading unit 3 and is wasted. Therefore, the operation of the production unit 2 is stopped when the kneading unit 3 is operating. In contrast, in a configuration with the bypass flow path 8, the production unit 2 can be operated even while the kneading unit 3 is operating, and the produced supercritical CO2 can flow into the storage tank 5. This allows the operating rate of the production unit 2 to be increased.

[0056] (effect) As described above, in the kneading apparatus 201 according to this embodiment, supercritical CO2 produced in the production unit 2 flows into the storage tank 5 through the bypass flow path 8. In a conventional configuration without the bypass flow path 8, even if supercritical CO2 is produced while the kneading unit 3 is operating, it cannot be supplied to the kneading unit 3, and is wasted. Therefore, the operation of the production unit 2 is stopped while the kneading unit 3 is operating. In contrast, in a configuration with the bypass flow path 8, the production unit 2 can be operated even while the kneading unit 3 is operating, and the produced supercritical CO2 can flow into the storage tank 5. This increases the operating rate of the production unit 2.

[0057] Although the embodiments of the present invention have been described above, they are merely illustrative examples and do not limit the present invention, and the specific configurations and other aspects can be appropriately modified in design. Furthermore, the actions and effects described in the embodiments of the invention are merely a list of the most preferred actions and effects resulting from the present invention, and the actions and effects of the present invention are not limited to those described in the embodiments of the present invention.

[0058] For example, in the first embodiment, the recovery pump 6 may be provided in the return flow path 4. Even with this configuration, the supercritical CO2 remaining in the kneading section 3 can be recovered as CO2 gas. [Explanation of symbols]

[0059] 1,101,201 Mixing equipment 2 Manufacturing Department 3. Mixing section 4 Return flow path 5. Storage Tank 6 Recovery pump 7 Heater 8 Bypass flow path 11. Tank 12 1st heat exchanger 13 Pump 14 Second heat exchanger 15 Liquid flow path 16 Check valve 17 Supply channel 18 Check valve 19 Gas flow path 21 Kneader 22 First adjusting valve 23 Separation Filter 24 Second adjusting valve 25 Check valve 26 Third adjusting valve 27 Check valve 28 7th adjusting valve 31 Fourth adjusting valve 32 Check valve 33 Branch channel 34 5th adjusting valve 35 Detour flow path 36 6th adjusting valve

Claims

1. a production department that produces a working fluid in a supercritical state or a subcritical state; a kneading section that kneads materials in the presence of the working fluid in a supercritical state or a subcritical state; a return flow path through which the working fluid separated from the material after kneading in the kneading section flows; a storage tank provided in the return flow path for storing the working fluid separated from the material; and an upstream end of the return flow path is connected to the kneading section, A kneading device characterized in that the downstream end of the return flow path is connected to the production section.

2. The manufacturing department a first heat exchanger for cooling the gaseous working fluid to form the liquid working fluid; a pump for pressurizing the liquid working fluid; a second heat exchanger for heating the pressurized liquid working fluid to vaporize the working fluid and thereby bring the working fluid to a supercritical or subcritical state; and The working fluid in a supercritical state or a subcritical state separated from the material flows into the storage tank; 2. The kneading device according to claim 1, wherein the downstream end of the return flow path is connected to a liquid flow path connecting the pump and the second heat exchanger.

3. 3. The kneading device according to claim 2, further comprising a heater provided in the storage tank for heating the inside of the storage tank.

4. 4. The kneading device according to claim 2, further comprising a supply flow path connecting the production section and the kneading section, and a bypass flow path connecting a portion of the return flow path upstream of the storage tank.

5. 5. The kneading device according to claim 1, further comprising a recovery pump provided in the return flow path for sucking the working fluid from within the kneading section.

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