Dissolving device and foreign matter separation system

Abstract

A dissolving device (10) is provided with: a supply unit (11) for supplying a waste resin and a solvent into a dissolving tank (101); a heating unit (12) for heating the waste resin and the solvent supplied to the dissolving tank (101); a stirrer (13) that stirs the waste resin heated by the heating unit (12) and the solvent; a load detection unit (14) that detects a load torque acting on the stirrer (13); a viscosity calculation unit (111) that calculates the viscosity of a solution comprising the waste resin and the solvent on the basis of the load torque detected by the load detection unit (14); and a dissolution control unit (112) that controls at least one of the supply unit (11) and the heating unit (12) such that the viscosity calculated by the viscosity calculation unit (111) is lower than a predetermined value.

Description

Technical Field

[0001] The invention relates to a dissolving device for separating foreign matter contained in waste plastics and a foreign matter separation system. Background Art

[0002] In recent years, initiatives to significantly reduce waste generation have been actively carried out by preventing and reducing waste generation, recycling and reusing waste. It is known that there is a technology for chemically recycling waste plastics into raw materials in order to achieve this goal. As such a technology, there is a known device for melting waste plastics in a pyrolysis tank while stirring them with a stirrer in a pyrolysis process for oiling waste plastics (see, for example, Patent Document 1). In the device described in Patent Document 1, the timing of starting and stopping the rotation of the stirrer is controlled according to the load torque of the stirrer to prevent damage and failure of the stirrer.

[0003] However, when separating foreign matter from waste plastics, the waste plastics generally need to be stirred and dissolved as a preliminary step. In such a step, the start and stop of the agitator are repeated as in the device described in Patent Document 1, making it difficult to operate efficiently.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 5132093 (JP2008-13595A). Summary of the invention

[0007] A dissolving device according to one embodiment of the present invention dissolves waste resin in a dissolving tank with a solvent. The dissolving device comprises: a supply unit that supplies waste resin and solvent into the dissolving tank; a heating unit that heats the waste resin and solvent supplied to the dissolving tank; a stirrer that stirs the waste resin and solvent heated by the heating unit; a load detection unit that detects a load torque acting on the stirrer; a viscosity calculation unit that calculates the viscosity of a solution formed by the waste resin and the solvent based on the load torque detected by the load detection unit; and a dissolving control unit that controls at least one of the supply unit and the heating unit so that the viscosity calculated by the viscosity calculation unit is lower than a specified value. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The objects, features and advantages of the present invention will be further clarified through the following description of the embodiments in conjunction with the accompanying drawings.

[0009] Figure 1 It is a diagram showing an example of the configuration of a foreign matter separation system according to an embodiment of the present invention.

[0010] Figure 2It is a diagram showing the main part structure of the dissolving device according to the embodiment of the present invention.

[0011] Figure 3 It is a diagram showing the main part structure of the degassing device according to the embodiment of the present invention.

[0012] Figure 4 It is shown by Figure 2 A flowchart of an example of a process performed by a controller.

[0013] Figure 5 It is shown by Figure 3 A flowchart of an example of a process performed by a controller. DETAILED DESCRIPTION

[0014] Below, refer to Figure 1 to Figure 5 An embodiment of the present invention will be described. The foreign matter separation system according to the embodiment of the present invention separates waste plastics used in vehicle structural parts (interior trim, bumper, etc.), and more specifically, separates foreign matter mixed in synthetic resin mixed with glass fiber.

[0015] However, assuming that various pollutants (metals, rubber, other resins, etc.) are mixed in the waste plastics recovered from the market, it is necessary to separate these foreign matters before chemical recovery by depolymerization methods, etc. In such foreign matter separation, first, as a preliminary process, a so-called dissolution treatment is performed to dissolve the waste plastics in a solvent to reduce its viscosity. However, it is difficult to predict the characteristics (type, quantity) of foreign matters mixed in recycled materials such as waste plastics. When the operating conditions (solvent input amount, heating temperature) are set to a certain level for dissolution treatment, it may affect the separation quality in the subsequent foreign matter separation. Although a method of dissolving treatment by batch setting operating conditions that match the recycled materials can also be considered, in this case, it will not be able to cope with continuous processing. Therefore, in order to cope with such a problem, the foreign matter separation system is constructed as follows in this embodiment.

[0016] Figure 1 1 is a block diagram showing an example of the overall structure of the foreign matter separation system according to an embodiment of the present invention. Figure 1 As shown, the foreign matter separation system 1 includes a dissolving device 10 , a separating device 20 , a foreign matter separation filter 30 , a buffer device 40 , a batch degassing device 50 , and an extruder (hereinafter referred to as a continuous kneading machine) 60 .

[0017] The dissolving device 10 dissolves the waste plastic (hereinafter referred to as waste resin) as a recycling material with a solvent. The waste resin is polyamide 6 (hereinafter referred to as PA6GF) mixed with glass fiber (hereinafter referred to as GF). The solvent is ethylene glycol (hereinafter referred to as EG). It should be noted that the waste resin can also be a substance other than PA6GF. In addition, the solvent can also be a substance other than EG.

[0018] The dissolving device 10 is connected to the separation device 20 via the connection part LN1, and the solution of the waste resin and the solvent is supplied to the separation tank (not shown) of the separation device 20 via the connection part LN1. The connection part LN1 includes a conveying line connecting the dissolving tank 101 of the dissolving device 10 and the separation tank of the separation device 20, and an opening and closing device (opening and closing valve) not shown provided on the conveying line. Figure 2 The dissolving device 10 will be described in detail.

[0019] The separation device 20 is a centrifugal separator. The separation device 20 has a separation tank (not shown) into which the solution supplied from the dissolving device 10 is placed, and removes foreign matter (garbage, metal, etc.) from the solution in the separation tank by centrifugal separation. The separation device 20 heats the solution in the separation tank to a temperature that meets the heating temperature command value described later, and centrifuges the solution at a rotation speed that meets the rotation speed command value described later.

[0020] The foreign matter separation filter 30 separates larger foreign matter (hereinafter referred to as large-scale contamination) that is not removed by centrifugal separation from the solution (hereinafter referred to as filtrate) after the foreign matter is separated by the separation device 20. As an example, the filter size of the foreign matter separation filter 30 is 2 to 5 mm. The buffer device 40 has a heating device and a stirrer (not shown) to temporarily concentrate the filtrate from which large-scale contamination has been removed by the foreign matter separation filter 30. The buffer device 40 concentrates the filtrate while keeping it warm and stirring it so that the viscosity of the filtrate is maintained below a certain viscosity (for example, 1 Pa·s). The filtrate concentrated in the buffer device 40 is supplied to the degassing device 50.

[0021] The degassing device 50 is a batch evaporator. The degassing device 50 is connected to the buffer device 40 via the connection part LN2. The degassing device 50 has a degassing tank 501 into which the filtrate supplied from the buffer device 40 via the connection part LN2 is put. The degassing device 50 evaporates the solvent contained in the filtrate in the degassing tank 501. The connection part LN2 includes a conveying line connecting the buffer device 40 and the degassing tank 501 of the degassing device 50, and an opening and closing device (opening and closing valve) not shown in the figure provided on the conveying line.

[0022] In addition, the degassing device 50 is connected to the extruder 60 via the connection part LN3, and the filtrate in the degassing tank 501 is supplied to the extruder 60 via the connection part LN3. The connection part LN3 includes a conveying line connecting the degassing tank 501 of the degassing device 50 and the extruder 60, and an opening and closing device (opening and closing valve) not shown in the figure provided on the conveying line. The extruder 60 heats and kneads the filtrate supplied from the degassing device 50, and degases the solvent remaining in the degassing device 50 without being degassed from the filtrate. The filtrate degassed by the extruder 60 is discharged from the extruder 60 and supplied to the depolymerization device 70 of the subsequent process. Figure 3 The degassing device 50 will be described in detail.

[0023] Figure 2 1 is a diagram showing the main structure of the dissolving device 10. Figure 2 As shown, the dissolving device 10 includes a controller 100, a supply unit 11, a heating unit 12, a stirrer 13, and a load detection unit 14. The controller 100 includes a computer having a computing unit 110 such as a CPU, a storage unit 120 such as a ROM (read only memory) and a RAM (random access memory), and other peripheral circuits. The supply unit 11, the heating unit 12, the stirrer 13, and the load detection unit 14 are connected to the controller 100, respectively.

[0024] The supply unit 11 supplies waste resin and solvent into the dissolution tank 101. The supply unit 11 includes a solvent injector (not shown) for injecting the solvent into the dissolution tank 101 and a recycle material injector (not shown) for injecting the waste resin into the dissolution tank 101 by a screw conveying method using a screw conveyor or the like. When the supply unit 11 receives a solvent supply instruction that specifies the supply amount of the solvent, the supply unit 11 supplies the solvent to the dissolution tank 101 via the solvent injector in accordance with the solvent supply instruction. In addition, when the supply unit 11 receives a recycle material supply instruction that specifies the supply amount of the waste resin, the supply unit 11 supplies the waste resin to the dissolution tank 101 via the recycle material injector in accordance with the recycle material supply instruction. The solvent supply instruction and the recycle material supply instruction will be described later.

[0025] When receiving the heating temperature command, the heating unit 12 heats the waste resin and solvent put into the dissolution tank 101. The heating temperature command will be described later. The stirrer 13 stirs the waste resin and solvent heated by the heating unit 12. The load detection unit 14 is a torque sensor, and detects the load torque acting on the stirrer 13.

[0026] Figure 2 The controller 100 includes a viscosity calculation unit 111 , a dissolution control unit 112 , and a flow control unit 113 as functional structures undertaken by the calculation unit 110 .

[0027] The viscosity calculation unit 111 calculates the viscosity of the solution in the dissolution tank 101 , ie, the solution composed of the waste resin and the solvent, based on the load torque of the stirrer 13 detected by the load detection unit 14 .

[0028] The dissolution control unit 112 controls at least one of the supply unit 11 and the heating unit 12 so that the viscosity calculated by the viscosity calculation unit 111 is lower than a specified value. Specifically, when the viscosity calculated by the viscosity calculation unit 111 is above a specified value, the dissolution control unit 112 sends a heating temperature instruction to the heating unit 12 to increase the temperature of the solution in the dissolution tank 101. When the heating unit 12 receives the heating temperature instruction, it starts heating so that the temperature of the solution in the dissolution tank 101 becomes the temperature specified by the heating temperature instruction. In addition, when the viscosity calculated by the viscosity calculation unit 111 is above a specified value, the dissolution control unit 112 controls the supply unit 11 so that the supply ratio of the solvent increases more than the specified ratio. In more detail, the dissolution control unit 112 determines the additional supply amount of the solvent in such a way that the viscosity of the solution in the dissolution tank 101 becomes lower than a specified value. Then, the solvent supply instruction specifying the determined additional supply amount is output to the supply unit 11. As a result, the supply unit 11 adds an amount of solvent corresponding to the additional supply amount to the dissolution tank 101. The additional supply amount may be a fixed amount, or may be determined so as to increase as the viscosity of the solution increases.

[0029] The flow control unit 113 controls the flow of the solution after stirring in the dissolution tank 101 via the connection unit LN1. In detail, when the viscosity calculated by the viscosity calculation unit 111 is lower than a specified value, the flow control unit 113 controls the flow of the solution so that the solution in the dissolution tank 101 is supplied to the separation tank of the separation device 20. In more detail, the flow control unit 113 outputs an opening command to the on-off valve of the connection unit LN1 to switch the on-off valve from a closed state to an open state. It should be noted that the initial state of the on-off valve is a closed state. In addition, when the supply of the solution to the separation tank of the separation device 20 is completed, the flow control unit 113 returns the on-off valve to a closed state.

[0030] In addition, even if the viscosity calculated by the viscosity calculation unit 111 is greater than the specified value, when a specified time has passed since the stirrer 13 started stirring, the flow control unit 113 outputs an opening command to the on-off valve, switching the on-off valve from a closed state to an open state, so that the solution in the dissolution tank 101 is supplied to the separation tank of the separation device 20. At this time, the flow control unit 113 determines the rotation speed command value and the heating temperature command value based on the viscosity calculated by the viscosity calculation unit 111, and sends the rotation speed command value and the heating temperature command value to the separation device 20.

[0031] The separation device 20 is a centrifugal separator. The separation device 20 heats the solution supplied from the dissolution tank 101 of the dissolution device 10 to a temperature that meets the heating temperature command value, and centrifuges the solution at a speed that meets the speed command value. It should be noted that the separation device 20 performs heating and centrifugation according to the speed and heating temperature that are pre-indicated, and when the speed command value and the heating temperature command value are received from the flow control unit 113, the separation device 20 performs heating and centrifugation according to the received command values.

[0032] Figure 3 : is a diagram showing the main structure of the degassing device 50. The degassing device 50 includes a controller 500, a heating unit 51, a stirrer 52, and a load detection unit 53. The controller 500 includes a computer having a computing unit 510 such as a CPU, a storage unit 520 such as a ROM and a RAM, and other peripheral circuits. The heating unit 51, the stirrer 52, and the load detection unit 53 are connected to the controller 500, respectively.

[0033] The heating unit 51 heats the filtrate in the degassing tank 501. The stirrer 52 stirs the filtrate in the degassing tank 501 heated by the heating unit 51. The load detection unit 53 is a torque sensor, and detects the load torque acting on the stirrer 52.

[0034] Figure 3 The controller 500 has a functional structure as a computing unit 510 , and the computing unit 510 includes a viscosity calculating unit 511 , a degassing control unit 512 , and a flow control unit 513 .

[0035] The viscosity calculation unit 511 calculates the viscosity of the filtrate in the degassing tank 501 based on the load torque of the stirrer 52 detected by the load detection unit 53. The degassing control unit 512 determines the heating temperature of the filtrate in the degassing tank 501 of the degassing device 50 based on the viscosity in the degassing tank 501 calculated by the viscosity calculation unit 511. Specifically, when the viscosity in the degassing tank 501 is lower than a predetermined viscosity, the degassing control unit 512 outputs a heating instruction that specifies a higher heating temperature than the current one to the heating unit 51.

[0036] The flow control unit 513 controls the flow of the filtrate concentrated in the buffer device 40 from the buffer device 40 to the degassing device 50 via the connection unit LN2. The connection unit LN2 includes a conveying line connecting the buffer device 40 and the degassing tank 501 of the degassing device 50, and an opening and closing device (opening and closing valve) not shown in the figure arranged on the conveying line. When the amount of the filtrate concentrated in the buffer device 40 reaches a certain level or more, the flow control unit 513 controls the flow of the filtrate so that the filtrate concentrated in the buffer device 40 is supplied to the degassing device 50. In more detail, the flow control unit 513 outputs an opening instruction to the opening and closing valve of the connection unit LN2, switching the opening and closing valve from a closed state to an open state. It should be noted that the initial state of the opening and closing valve is a closed state. In addition, when the supply of the filtrate to the degassing tank 501 of the degassing device 50 is completed, the flow control unit 513 returns the opening and closing valve to a closed state.

[0037] In addition, the flow control unit 513 controls the flow of the filtrate after stirring in the degassing tank 501 from the degassing device 50 to the extruder 60 via the connection part LN3. In detail, when the viscosity calculated by the viscosity calculation unit 511 reaches the specified viscosity, the flow control unit 513 controls the flow of the filtrate so that the filtrate in the degassing tank 501 is supplied to the extruder 60. In more detail, the flow control unit 513 outputs an opening instruction to the on-off valve of the connection part LN3 to switch the on-off valve from a closed state to an open state. It should be noted that the flow control unit 513 can also control the flow of the filtrate so that the filtrate in the degassing tank 501 is supplied to the extruder 60 even if the viscosity calculated by the viscosity calculation unit 511 is lower than the specified viscosity and a specified time has passed since the stirrer 52 started stirring. It should be noted that the initial state of the on-off valve of the connection part LN3 is a closed state. In addition, when the supply of the filtrate to the extruder 60 ends, the flow control unit 513 returns the above-mentioned on-off valve to a closed state.

[0038] When the filtrate in the degassing tank 501 is supplied to the extruder 60, the flow control unit 513 sends a rotation speed command value and a heating temperature command value to the extruder 60 according to the viscosity calculated by the viscosity calculation unit 511. The extruder 60 heats the filtrate supplied from the degassing tank 501 of the degassing device 50 to a temperature that meets the heating temperature command value. In addition, the extruder 60 rotates a built-in screw (not shown) at a rotation speed that meets the rotation speed command value, thereby kneading the filtrate supplied from the degassing tank 501 of the degassing device 50.

[0039] Figure 4 This is a flowchart showing an example of processing executed by the controller 100 of the dissolving device 10. The processing shown in this flowchart starts when the dissolving device 10 is powered on, for example, and is repeatedly performed in a predetermined cycle until step S19 is executed.

[0040] First, in step S11, waste resin (powder) is added. More specifically, the controller 100 outputs a solvent supply instruction specifying the supply amount of the solvent to the supply unit 11. In addition, the controller 100 outputs a recycled material supply instruction specifying the supply amount of the waste resin to the supply unit 11. At this time, the controller 100 outputs a solvent supply instruction and a recycled material supply instruction so that the supply ratio of the solvent to the waste resin reaches a specified ratio. The supply unit 11 supplies the amount of solvent specified by the solvent supply instruction to the dissolution tank 101, and supplies the amount of waste resin specified by the recycled material supply instruction to the dissolution tank 101.

[0041] In step S12, the waste resin and the solvent in the dissolution tank 101 are heated while being stirred. In step S13, the load torque acting on the stirrer 13 is detected by the load detection unit 14. In step S14, the load torque detected in step S13 is converted into the viscosity of the solution in the dissolution tank 101. It should be noted that the conversion can be performed based on a table or formula showing the correlation between the load torque and the viscosity of the solution pre-stored in the storage unit 120, etc., or can be performed by other methods.

[0042] In step S15, it is determined whether the viscosity calculated in step S14 is lower than a specified value. When step S15 is affirmative (S15: Yes), step S19 is entered. When step S15 is negative (S15: No), in step S16, it is determined whether a specified time has passed since the stirrer 13 started stirring. When step S16 is negative (S16: No), the dissolution condition is updated in step S17. Specifically, the additional supply amount of the solvent is determined in such a way that the viscosity in the dissolution tank 101 is lower than a specified value. Then, a solvent supply instruction specifying the determined additional supply amount is output to the supply unit 11. Thus, in step S11 of the next cycle, an amount of solvent corresponding to the additional supply amount is added to the dissolution tank 101. It should be noted that a heating instruction can also be output to the heating unit 12 together with or instead of the solvent supply instruction specifying the additional supply amount to increase the temperature of the solution in the dissolution tank 101.

[0043] When step S16 is positive (S16: Yes), in step S18, the operating conditions of the next process (foreign matter separation process) determined by the viscosity calculated in step S14 are determined and sent to the separation device 20. The operating conditions include a rotation speed command value and a heating temperature command value. In step S19, the flow of the solution is controlled so that the solution in the dissolution tank 101 is supplied to the separation tank of the separation device 20.

[0044] Figure 54 is a flowchart showing an example of processing executed by the controller 500 of the degassing device 50. The processing shown in the flowchart is started when the amount of filtrate collected in the buffer device 40 reaches a certain level, and is repeated at a predetermined cycle until steps S27 and S28 are executed.

[0045] First, in step S21, the filtrate collected in the buffer device 40 is supplied to the degassing tank 501. In step S22, the filtrate in the degassing tank 501 is heated while being stirred. In step S23, the load torque acting on the agitator 52 is detected by the load detection unit 53. In step S24, the load torque detected in step S23 is converted into the viscosity of the filtrate in the degassing tank 501. It should be noted that the conversion can be performed based on a table or formula showing the correlation between the load torque and the viscosity of the filtrate pre-stored in the storage unit 120, etc., or can be performed by other methods.

[0046] In step S25, it is determined whether the viscosity calculated in step S24 is a specified viscosity (e.g., 10 to 100 Pa·s). When step S25 is negative (S25: No), in step S26, the heating conditions of the filtrate (hereinafter referred to as the pool heating conditions) are changed so that the filtrate in the degassing pool 501 reaches a specified viscosity. Specifically, when the filtrate in the degassing pool 501 is lower than the specified viscosity, a heating instruction specifying a heating temperature higher than the current temperature is output to the heating unit 51. When the pool heating conditions are updated, the process is terminated. Thus, the degassing process of the degassing device 50 is continued according to the updated pool heating conditions.

[0047] On the other hand, when step S25 is affirmative (S25: Yes), in step S27, the operating conditions (rotation speed and heating temperature) of the extruder 60 are determined based on the viscosity calculated in step S24, and the rotation speed command value and the heating temperature command value are sent to the extruder 60 according to the determined operating conditions. In step S28, the flow of the filtrate is controlled so that the filtrate in the degassing tank 501 is supplied to the extruder 60. Thus, the extruder 60 starts the degassing process according to the above-mentioned operating conditions.

[0048] According to this embodiment, the following effects can be achieved.

[0049] (1) The dissolving device 10 dissolves the waste resin in the dissolving tank 101 with a solvent. The dissolving device 10 includes: a supply unit 11 that supplies the waste resin and the solvent into the dissolving tank 101; a heating unit 12 that serves as a first heating unit and heats the waste resin and the solvent supplied to the dissolving tank 101; a stirrer 13 that serves as a first stirrer and stirs the waste resin and the solvent heated by the heating unit 12; a load detection unit 14 that serves as a first load detection unit and detects a load torque acting on the stirrer 13; a viscosity calculation unit 111 that serves as a first viscosity calculation unit and calculates the viscosity of a solution formed by the waste resin and the solvent based on the load torque detected by the load detection unit 14; and a dissolving control unit 112 that controls at least one of the supply unit 11 and the heating unit 12 so that the viscosity calculated by the viscosity calculation unit 111 is lower than a predetermined value. When the viscosity calculated by the viscosity calculation unit 111 is equal to or higher than the predetermined value, the dissolving control unit 112 controls the heating unit 12 to increase the temperature of the solution. In addition, when the viscosity calculated by the viscosity calculation unit 111 is greater than a predetermined value, the dissolution control unit 112 controls the supply unit 11 so that the supply ratio of the solvent increases more than the predetermined ratio. In this way, in the dissolution process, by performing feedback control based on the viscosity of the solution while performing continuous operation, the amount of solvent added and the heating energy can be optimized without the need for a high-precision device. In addition, the uniformity of the solution supplied in the foreign matter separation process can be ensured, and efficient operation can be achieved in subsequent processes including the foreign matter separation process.

[0050] (2) The foreign matter separation system 1 includes a dissolving device 10 and a separating device 20, which is connected to the dissolving device 10 via a connection portion LN1 as a first connection portion, and separates foreign matter contained in the waste resin from the solution. The dissolving device 10 in the foreign matter separation system 1 further includes a flow control unit 113, which is a first flow control unit, and controls the flow of the solution stirred in the dissolving tank 101 from the dissolving device 10 to the separating device 20 via the connection portion LN1. When the viscosity calculated by the viscosity calculation unit 111 is lower than a predetermined value, the flow control unit 113 controls the flow of the solution so that the solution in the dissolving tank 101 is supplied to the separating device 20. More specifically, even if the viscosity calculated by the viscosity calculation unit 111 is higher than a predetermined value, when a predetermined time has passed since the stirrer 13 started stirring, the flow control unit 113 controls the flow of the solution so that the solution in the dissolving tank 101 is supplied to the separating device 20. Furthermore, the flow control unit 113 sends the rotation speed command value and the heating temperature command value determined based on the viscosity calculated by the viscosity calculation unit 111 to the separation device 20. This can further stabilize the quality of the foreign matter separation process.

[0051] (3) The foreign matter separation system 1 further includes a degassing device 50 as a first degassing device and an extruder 60 as a second degassing device, which degas the solvent contained in the solution after the foreign matter is separated by the separation device 20. The extruder 60 is connected to the degassing device 50 via a connection portion LN2 as a second connection portion. The degassing device 50 also includes: a degassing tank 501, which is supplied with a solution after foreign matter is separated by the separation device 20; a heating unit 51, which serves as a second heating unit and heats the solution supplied to the degassing tank 501; an agitator 52, which serves as a second agitator and stirs the solution heated by the heating unit 51; a load detection unit 53, which serves as a second load detection unit and detects the load torque acting on the agitator 52; a viscosity calculation unit 511, which serves as a second viscosity calculation unit and calculates the viscosity of the solution in the degassing tank 501 based on the load torque acting on the agitator 52 detected by the load detection unit 53; and a flow control unit 513, which serves as a second flow control unit and controls the flow of the solution stirred in the degassing tank 501 from the degassing device 50 to the extruder 60 via the connection unit LN2. When the viscosity calculated by the viscosity calculation unit 511 is lower than the specified viscosity, the flow control unit 513 controls the flow of the solution so that the solution in the degassing tank 501 is supplied to the extruder 60, and then the speed command value and the heating temperature command value determined based on the viscosity calculated by the viscosity calculation unit 511 are sent to the extruder 60. The extruder 60 is an extruder that extrude the solution supplied from the degassing device 50 while rotating the built-in screw, heats the solution supplied from the degassing device 50 to a temperature that matches the heating temperature command value, and rotates the screw at a speed that matches the speed command value. Through such a two-stage degassing process, contamination can be appropriately removed regardless of the state of the recycled material (the amount of foreign matter mixed in).

[0052] The above-described embodiment can be modified in various forms. Modifications will be described below.

[0053] In the above embodiment, a dissolving device 10 having a single controller 100 is taken as an example ( Figure 2 ), but the dissolving device 10 can also be distributed in a plurality of controllers. In addition, in the above embodiment, the degassing device 50 having a single controller 500 is taken as an example ( Figure 3 ), but similarly, the degassing device 50 can also be distributed among multiple controllers.

[0054] The above description is merely an example, and the above embodiment and modified examples do not limit the present invention unless the features of the present invention are impaired. One or more of the above embodiment and modified examples can be arbitrarily combined, and the modified examples can be combined with each other.

[0055] According to the present invention, efficient operation can be achieved in the foreign matter separation process.

[0056] The present invention has been described above in conjunction with preferred embodiments, but it should be understood by those skilled in the art that various modifications and changes can be made without departing from the scope of the claims.

Claims

1. A dissolving device, which is a dissolving device (10) for dissolving waste resin in a dissolving tank (101) with a solvent, characterized in that: have: a supply unit (11) for supplying the waste resin and the solvent into the dissolution tank (101); a heating unit (12) for heating the waste resin and the solvent supplied to the dissolution tank (101); a stirrer (13) for stirring the waste resin and the solvent heated by the heating unit (12); a load detection unit (14) for detecting a load torque acting on the stirrer (13); a viscosity calculating unit (111) for calculating the viscosity of a solution formed by the waste resin and the solvent based on the load torque detected by the load detecting unit (14); as well as A dissolution control unit (112) controls at least one of the supply unit (11) and the heating unit (12) so that the viscosity calculated by the viscosity calculation unit (111) is lower than a predetermined value.

2. The dissolving device according to claim 1, characterized in that: The dissolution control unit (112) controls the heating unit (12) so as to increase the temperature of the solution when the viscosity calculated by the viscosity calculation unit (111) is equal to or greater than a predetermined value.

3. The dissolving device according to claim 1, characterized in that: The dissolution control unit (112) controls the supply unit (11) so that the supply ratio of the solvent to the waste resin increases to a predetermined ratio when the viscosity calculated by the viscosity calculation unit (111) is equal to or greater than a predetermined value.

4. A foreign matter separation system, comprising the dissolving device according to claim 1 and a separation device (20), wherein the separation device (20) is connected to the dissolving device (10) via a connection portion (LN1), and separates foreign matter contained in the waste resin from the solution. The dissolving device (10) further comprises a flow control unit (113) for controlling the flow of the solution stirred in the dissolving tank (101) from the dissolving device (10) to the separation device (20) via the connection unit (LN1). When the viscosity calculated by the viscosity calculation unit (111) is lower than a specified value, the flow control unit (113) controls the flow of the solution so that the solution in the dissolution tank (101) is supplied to the separation device (20).

5. The foreign matter separation system according to claim 4, characterized in that: The flow control unit (113) controls the flow of the solution so that the solution in the dissolution tank (101) is supplied to the separation device (20) even if the viscosity calculated by the viscosity calculation unit (111) is greater than a specified value and a specified time has passed since the stirrer (13) started stirring, and further sends a rotation speed command value and a heating temperature command value determined according to the viscosity to the separation device (20). The separation device (20) heats the solution supplied from the dissolution tank (101) to a temperature that matches the heating temperature command value, and centrifugally separates the solution at a rotation speed that matches the rotation speed command value.

6. The foreign matter separation system according to claim 5, characterized in that: The heating unit (12) is a first heating unit, the stirrer (13) is a first stirrer, the load detection unit (14) is a first load detection unit, the viscosity calculation unit (111) is a first viscosity calculation unit, the connection unit (LN1) is a first connection unit, the flow control unit (113) is a first flow control unit, the heating temperature instruction value is a first heating temperature instruction value, the rotation speed instruction value is a first rotation speed instruction value, The foreign matter separation system further comprises a first degassing device (50) and a second degassing device (60) for degassing the solvent contained in the solution after the foreign matter is separated by the separation device (20). The second degassing device (60) is connected to the first degassing device (50) via a second connection portion (LN2). The first degassing device (50) comprises: a degassing tank (501) which is supplied with the solution after the foreign matter is separated by the separation device (20); a second heating unit (51) for heating the solution supplied to the degassing tank (501); a second stirrer (52) for stirring the solution heated by the second heating unit (51); a second load detection unit (53) for detecting a load torque acting on the second agitator (52); a second viscosity calculation unit (511) for calculating the viscosity of the solution in the degassing tank (501) based on the load torque acting on the second agitator (52) detected by the second load detection unit (53); as well as a second flow control unit (513) for controlling the flow of the solution stirred in the degassing tank (501) from the first degassing device (50) to the second degassing device (60) via the second connection unit (LN2), When the viscosity calculated by the second viscosity calculating unit (511) reaches a predetermined viscosity, the second flow control unit (513) controls the flow of the solution so that the solution in the degassing tank (501) is supplied to the second degassing device (60), and further sends a second rotation speed instruction value and a second heating temperature instruction value determined based on the viscosity calculated by the second viscosity calculating unit (511) to the second degassing device (60). The second degassing device (60) heats the solution supplied from the first degassing device (50) to a temperature that matches the heating temperature command value, and discharges the solution supplied from the first degassing device (50) while rotating the screw at a rotation speed that matches the rotation speed command value.

7. The foreign matter separation system according to claim 6, characterized in that: The second flow control unit (513) controls the flow of the solution so that the solution in the degassing tank (501) is supplied to the second degassing device (60) even if the viscosity calculated by the second viscosity calculation unit (511) is lower than the specified viscosity and a specified time has passed since the second agitator (52) started stirring, and further sends the second rotation speed command value and the second heating temperature command value to the second degassing device (60).

8. The foreign matter separation system according to claim 6, characterized in that: The first degassing device (50) is a batch evaporator, The second degassing device (60) is an extruder.

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