System for producing monomer, control method, and program

Abstract

To produce a monomer adequately.SOLUTION: A system for producing a monomer includes: a dissolving part for storing a polyester solution dissolved with a polyester by introducing a polyester raw material including the polyester; a reaction part for introducing the polyester solution, and a reaction solvent for reacting with the polyester, and depolymerizing the polyester in the polyester solution to generate a reaction solvent dissolved with a depolymerized polyester; a separating part for separating the reaction solvent obtained by dissolving the polyester subjected to depolymerization into a monomer and the reaction solvent; a detection part for detecting a parameter concerning a concentration of the monomer contained in the reaction solvent dissolved with the depolymerized polyester; and a control part for controlling an introducing amount of the polyester raw material to the dissolving part according to the parameter.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a monomer production system, a control method, and a program.

Background Art

[0002] In the recycling of polyester, a technique for monomerizing polyester by depolymerization (reverse reaction of polymerization) is known. Patent Document 1 describes a dissolution part in which a polyester solution is stored, a first reaction part and a second reaction part into which the polyester solution and a reaction solvent are introduced to depolymerize the polyester in the polyester solution, and a separation part for separating the reaction solvent in which the depolymerized polyester is dissolved into a reaction solvent, a monomer, and a residue containing an oligomer, and a pipe for returning the monomer and the oligomer to the dissolution part. A monomer production system is described.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a monomer production system, it is required to appropriately produce monomers.

[0005] An object of the present disclosure is to provide a monomer production system, a control method, and a program capable of appropriately producing monomers.

Means for Solving the Problems

[0006] The monomer production system according to the present disclosure includes a dissolution unit into which a polyester raw material containing polyester is introduced and a polyester solution in which the polyester is dissolved is stored, a reaction unit into which the polyester solution and a reaction solvent that reacts with the polyester are introduced to depolymerize the polyester in the polyester solution and generate a reaction solvent in which the depolymerized polyester is dissolved, a separation unit that separates the reaction solvent in which the depolymerized polyester is dissolved into a monomer and a reaction solvent, a detection unit that detects a parameter related to the concentration of the monomer contained in the reaction solvent in which the depolymerized polyester is dissolved, and a control unit that controls the introduction amount of the polyester raw material into the dissolution unit based on the parameter.

[0007] The control method according to the present disclosure is a control method for a monomer production system including a dissolution unit into which a polyester raw material containing polyester is introduced and a polyester solution in which the polyester is dissolved is stored, a reaction unit into which the polyester solution and a reaction solvent that reacts with the polyester are introduced to depolymerize the polyester in the polyester solution and generate a reaction solvent in which the depolymerized polyester is dissolved, and a separation unit that separates the reaction solvent in which the depolymerized polyester is dissolved into a monomer and a reaction solvent, the method including: detecting a parameter related to the concentration of the monomer contained in the reaction solvent in which the depolymerized polyester is dissolved; and controlling the introduction amount of the polyester raw material into the dissolution unit based on the parameter.

[0008] A program according to the present disclosure causes a computer to execute a control method for a monomer production system having a dissolution unit in which a polyester solution in which a polyester raw material containing polyester is introduced and the polyester is dissolved is stored, a reaction unit in which the polyester solution and a reaction solvent that reacts with the polyester are introduced to depolymerize the polyester in the polyester solution and generate a reaction solvent in which the depolymerized polyester is dissolved, and a separation unit that separates the reaction solvent in which the depolymerized polyester is dissolved into a monomer and a reaction solvent, the program causing the computer to execute steps of detecting a parameter related to the concentration of the monomer contained in the reaction solvent in which the depolymerized polyester is dissolved and controlling the introduction amount of the polyester raw material into the dissolution unit based on the parameter.

Effects of the Invention

[0009] According to the present disclosure, monomers can be appropriately produced.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that the present disclosure is not limited by this embodiment, and when there are a plurality of embodiments, those configured by combining each embodiment are also included.

[0012] (Recycling Process) FIG. 1 is a schematic diagram of a polyester recycling process according to the present embodiment. In the present embodiment, a process of recycling (reproducing) the polyester raw material Pm is performed by depolymerizing the polyester raw material Pm to monomerize it and then repolymerizing the monomers. Specifically, as shown in FIG. 1, the polyester raw material Pm is flaked (step S100), the flaked polyester raw material Pm is dissolved in the monomer D derived from carboxylic acid to produce a polyester solution, foreign substances are removed from the polyester solution, the polyester solution from which the foreign substances have been removed is mixed with the reaction solvent M and depolymerized (step S102), the monomers of the depolymerized polyester are purified (separated) to purify the monomer D derived from carboxylic acid and the monomer E of the alcohol component (step S104), the monomer D is hydrolyzed to separate the reaction solvent M (step S106), the monomer F generated by the hydrolysis of the monomer D and the monomer E are polymerized (step S108) to reproduce the polyester raw material Pm. Note that the recycling process employing the monomer production system 1 of the present embodiment may omit the flaking in step S100, or may perform only the process of recovering the monomers D, E shown in steps S102, S104, and the monomer F shown in step S106 without performing the repolymerization process as in step S108.

[0013] (Polyester raw material) In this embodiment, the polyester raw material Pm to be depolymerized is a substance containing polyester. The polyester raw material Pm is not particularly limited, and examples thereof include waste products such as polyethylene terephthalate (PET), polyethylene butylene terephthalate (PEBT), polybutylene terephthalate (PBT), polycyclohexane dimethyl terephthalate (PCT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), and polycarbonate (PC). The polyester raw material Pm is not limited to those containing only polyester components, and may also contain components (impurities) other than the polyester component. Examples of components other than polyester contained in the polyester raw material Pm include plastics other than polyester such as polyethylene, polystyrene, polypropylene, and polyvinyl chloride, metals, dyes, pigments, and polymerization catalysts. Examples of the polyester raw material Pm also include clothes in which polyester and other components are woven in a fibrous form.

[0014] (Reaction solvent) The reaction solvent M is a solvent that reacts with polyester to depolymerize the polyester. The reaction solvent M may be, for example, at least one of methanol, ethanol, water, and ethylene glycol.

[0015] (Monomer derived from carboxylic acid) The monomer D derived from carboxylic acid is a monomer having a carboxyl group generated by the depolymerization reaction of polyester. The monomer D may be, for example, dimethyl carboxylate or diethyl carboxylate. Further, the monomer D is preferably a monomer of terephthalic acid, and may be, for example, dimethyl terephthalate (DMT).

[0016] (Monomer of alcohol component) The monomer E of the alcohol component is a monomer of the alcohol component generated by the depolymerization reaction of polyester. The monomer E may be, for example, a dihydroxy compound (dihydric alcohol), and further may be ethylene glycol (EG).

[0017] Hereinafter, a case where the polyester is PET, the reaction solvent M is methanol, the monomer D is DMT, and the monomer E is EG will be described as an example.

[0018] (Monomer production system) FIG. 2 is a schematic diagram of the monomer production system according to the present embodiment. The monomer production system 1 according to the present embodiment is a system that monomerizes the polyester contained in the polyester raw material Pm to produce the monomers D and E. As shown in FIG. 2, the monomer production system 1 includes a raw material storage unit 10, a dissolution unit 12, a solvent storage unit 14, a reaction unit 16, a separation unit 18, and a control unit 20.

[0019] (Raw material storage unit) The raw material storage unit 10 is a tank into which the polyester raw material Pm is introduced and in which the polyester raw material Pm is stored. In the present embodiment, the flaked polyester raw material Pm is stored in the raw material storage unit 10, but the shape and size of the polyester raw material Pm may be arbitrary. The raw material storage unit 10 is connected to the dissolution unit 12 via an introduction pipe 10a. The polyester raw material Pm in the raw material storage unit 10 is supplied to the dissolution unit 12 through the introduction pipe 10a. The introduction pipe 10a is provided with an adjustment unit 10b for adjusting the amount of the polyester raw material Pm supplied from the raw material storage unit 10 to the dissolution unit 12. The adjustment unit 10b is, for example, an on-off valve. In the open state, the polyester raw material Pm in the raw material storage unit 10 is supplied to the dissolution unit 12, and in the closed state, the supply of the polyester raw material Pm in the raw material storage unit 10 to the dissolution unit 12 is stopped. However, the adjustment unit 10b is not limited to an on-off valve and may be any mechanism capable of adjusting the supply of the polyester raw material Pm to the dissolution unit 12. Further, the polyester raw material Pm may be directly supplied to the dissolution unit 12 without passing through the raw material storage unit 10, the introduction pipe 10a, and the adjustment unit 10b.

[0020] (Dissolution unit) The dissolution section 12 is a tank into which the polyester raw material Pm is introduced and in which the polyester solution P is stored. The polyester solution P is a solution in which the polyester contained in the polyester raw material Pm is dissolved in the monomer D. It is a solution formed by mixing the polyester raw material Pm and the monomer D. The monomer D and the polyester raw material Pm are supplied to the dissolution section 12, and in the dissolution section 12, the polyester contained in the polyester raw material Pm is dissolved in the monomer D to produce the polyester solution P. By dissolving the polyester in the monomer D in this way, the viscosity can be reduced and the fluidity can be improved, and the polyester can be easily led out to the reaction section 16. Furthermore, the residue R described later is also supplied to the dissolution section 12, and in the dissolution section 12, the polyester contained in the polyester raw material Pm is dissolved in the oligomers contained in the monomer D and the residue R to produce the polyester solution P. That is, the polyester solution P can be said to be a solution in which the polyester is dissolved in the monomer D and the residue R. However, the polyester solution P is not limited to the case where all of the polyester is dissolved in the monomer D and the residue R, and at least a part of the polyester may be in a state of not being dissolved in the monomer D and the residue R. Also, the polyester raw material Pm may contain impurities which are substances other than polyester. In this case, it can be said that the polyester solution P contains the monomer D, the dissolved polyester, and the impurities.

[0021] Note that the polyester solution P is not limited to a solution in which the polyester is dissolved in the monomer D, and may be a solution in which the polyester is dissolved in the monomer E. In this case, the monomer E and the polyester raw material Pm are supplied to the dissolution section 12, and in the dissolution section 12, the polyester contained in the polyester raw material Pm is dissolved in the monomer E to produce the polyester solution P.

[0022] The dissolution unit 12 is connected to a first reaction unit 16A, which will be described later, via an introduction pipe 12a. The polyester solution P in the dissolution unit 12 is supplied to the first reaction unit 16A through the introduction pipe 12a. Further, a supply unit 12b and a heating unit 12c are provided in the introduction pipe 12a. The supply unit 12b is a mechanism for supplying the polyester solution P in the dissolution unit 12 to the first reaction unit 16A, and is a pump in this embodiment. The heating unit 12c is a mechanism for heating the polyester solution P.

[0023] (Solvent storage section) The solvent storage unit 14 is a tank into which a reaction solvent M is introduced and stored. The solvent storage unit 14 is connected to the reaction unit 16 via an introduction pipe 14a. The reaction solvent M in the solvent storage unit 14 is supplied to the reaction unit 16 through the introduction pipe 14a. More specifically, a heating and pressurizing unit 14b and an adjustment unit 14c are provided in the introduction pipe 14a. The adjustment unit 14c is a mechanism for supplying the reaction solvent M in the solvent storage unit 14 to the first reaction unit 16A, and is a pump in this embodiment. The heating and pressurizing unit 14b is a mechanism for pressurizing and heating the reaction solvent M. By pressurizing and heating the reaction solvent M, the heating and pressurizing unit 14b brings the reaction solvent M into a supercritical state or a subcritical state (pressurized gas or pressurized liquid). The reaction unit 16 is supplied with the reaction solvent M in a supercritical state or a subcritical state (pressurized gas or pressurized liquid).

[0024] (Reaction section) The reaction unit 16 is a mechanism into which a polyester and a reaction solvent M that reacts with the polyester are introduced, and which depolymerizes the polyester to produce a reaction solvent in which the depolymerized polyester is dissolved. Specifically, the reaction unit 16 is a container into which a polyester solution P and a reaction solvent M are supplied, and the supplied reaction solvent M depolymerizes the polyester in the polyester solution P. The reaction unit 16 includes a first reaction unit 16A and a second reaction unit 16B. Hereinafter, in the reaction unit 16, the direction from the first reaction unit 16A to the second reaction unit 16B is defined as direction Y1, and the direction opposite to direction Y1 (the direction from the second reaction unit 16B to the first reaction unit 16A) is defined as direction Y2.

[0025] (First reaction section) The first reaction section 16A is formed within the reaction section 16. In this embodiment, the first reaction section 16A can be said to be the location within the reaction section 16 where the filler is filled. For the first reaction section 16A, a known filler used in a gas-liquid or liquid-liquid contact device can be used as the filling agent. For example, a filler similar to that used in a contact device for contacting heavy oil and water to extract the active ingredient can be used. Specific examples of the filler include pipes made of SUS, etc., Raschig rings, Berl saddles, Telarets, etc.

[0026] An introduction pipe 12a is connected to the first reaction section 16A. More specifically, an inlet 16C, which is an opening through which the polyester solution P from the dissolution section 12 is introduced into the introduction pipe 12a, is connected to the first reaction section 16A. The inlet 16C is connected to the surface 16A1 on the Y1 side of the first reaction section 16A. The introduction pipe 12a is connected to the surface 16A1 such that the inlet 16C opens facing the Y2 side. Thus, in this embodiment, the inlet 16C opening facing the Y2 side is connected to the surface 16A1 of the first reaction section 16A, but it is not limited thereto. For example, the inlet 16C may not be directly connected to the first reaction section 16A, and the inlet 16C opening facing the Y2 side may be connected to the Y1 side of the surface 16A1 of the first reaction section 16A within the reaction section 16.

[0027] The introduction pipe 14a is connected to the reaction section 16. More specifically, an inlet 16D, which is an opening through which the reaction solvent M from the solvent storage section 14 is introduced into the introduction pipe 14a, is connected to the reaction section 16. The inlet 16D is connected to the Y2 side of the surface 16A2 on the Y2 side of the first reaction section 16A. The introduction pipe 14a is connected to the Y2 side of the surface 16A2 such that the inlet 16D opens facing the Y1 side or facing the center from the side surface. Thus, in this embodiment, the inlet 16D that opens facing the Y1 side or facing the center from the side surface is connected to the Y2 side of the surface 16A2 of the first reaction section 16A, but it is not limited thereto. For example, the inlet 16D may be directly connected to the first reaction section 16A or may be connected to the surface 16A2 of the first reaction section 16A.

[0028] Thus, in this embodiment, the inlet 16C through which the polyester solution P is introduced opens facing the Y2 direction, and the inlet 16D through which the reaction solvent M is introduced opens facing the Y1 direction or facing the center from the side surface. Therefore, the polyester solution P and the reaction solvent M are introduced into the first reaction section 16A in directions facing each other.

[0029] The polyester solution P introduced from the inlet 16C into the first reaction section 16A moves on the surface of the packing material in the first reaction section 16A in the direction of Y2. On the other hand, the reaction solvent M in the supercritical state or subcritical state (pressurized gas or pressurized liquid) introduced from the inlet 16D moves in the first reaction section 16A in the direction of Y1. In the first reaction section 16A, the reaction solvent M in the supercritical state or subcritical state (pressurized gas or pressurized liquid) contacts the polyester solution P. The polyester in the polyester solution P is depolymerized (molecular weight reduced) by the reaction solvent M, and the depolymerized polyester is extracted by the reaction solvent M in the supercritical state or subcritical state (pressurized gas or pressurized liquid). Hereinafter, the polyester depolymerized in the first reaction section 16A is referred to as the first depolymerized polyester P1, and the mixture of the first depolymerized polyester P1 and the reaction solvent M (the reaction solvent M from which the first depolymerized polyester P1 has been extracted) is referred to as the first solvent M1. The first solvent M1 containing the first depolymerized polyester P1 advances in the first reaction section 16A toward the Y1 side and is led out to the Y1 side of the first reaction section 16A.

[0030] Note that the first depolymerized polyester P1 includes monomers D and E generated by depolymerization of the polyester in the polyester solution P, monomer D originally mixed in the polyester solution P, and oligomers generated by depolymerization of the polyester. The oligomers here refer to oligomers of carboxylic acids or alcohols that have not been monomerized but have been depolymerized from polyester (oligomers of carboxylic acids or alcohols with a molecular weight smaller than that of polyester). Also, the oligomers contained in the residual substance R in the polyester solution P are depolymerized by the reaction solvent M. Therefore, the first depolymerized polyester P1 also includes the depolymerized residual substance R. The depolymerized residual substance R refers to oligomers contained in the residual substance R that have been depolymerized, and monomers D, E, etc. generated by depolymerization of the oligomers contained in the residual substance R.

[0031] (Second reaction section) The second reaction section 16B is provided within the reaction section 16, and is provided at a location where the first solvent M1 is derived from the first reaction section 16A. In the present embodiment, the second reaction section 16B is provided on the first direction D1 side of the first reaction section 16A.

[0032] In the second reaction section 16B, the first depolymerized polyester P1 contained in the first solvent M1 is further depolymerized (molecular weight reduced) by the reaction solvent M contained in the first solvent M1. Hereinafter, the first depolymerized polyester P1 further depolymerized in the second reaction section 16B is referred to as the second depolymerized polyester P2, and a mixture of the second depolymerized polyester P2 and the reaction solvent M (the reaction solvent M containing the second depolymerized polyester PE) is referred to as the second solvent M2. A lead-out pipe 16a is connected to the second reaction section 16B. More specifically, a lead-out port 16E, which is an opening from which the second solvent M2 from the second reaction section 16B is led out, of the lead-out pipe 16a is connected to the second reaction section 16B. The second solvent M2 containing the second depolymerized polyester P2 in the second reaction section 16B is led out to the outside of the second reaction section 16B through the lead-out pipe 16a from the lead-out port 16E.

[0033] Note that the second depolymerized polyester P2 contains monomers D and E generated by depolymerization of oligomers in the first depolymerized polyester P1, and oligomers generated by depolymerization of the first depolymerized polyester P1.

[0034] A discharge pipe 16b is connected to the bottom of the reaction section 16 (the bottom surface on the Y2 direction side). More specifically, a discharge port 16F, which is an opening of the discharge pipe 16b through which non-extracted substances in the reaction section 16 are discharged, is connected to the bottom of the reaction section 16. From the discharge pipe 16b, non-extracted substances are discharged, including impurities such as metal compounds not extracted by the reaction solvent M and residues of undecomposed polyester not extracted by the reaction solvent M. That is, the non-extracted substances at the bottom of the reaction section 16 are discharged from the discharge port 16F through the discharge pipe 16b to the outside of the reaction section 16. The non-extracted substances discharged from the discharge pipe 16b can be regarded as components remaining in the first reaction section 16A and the second reaction section 16B without being led to the separation section 18 as the second solvent M2 (the reaction solvent containing the second depolymerized polyester P2) in the polyester solution P.

[0035] Further, the reaction section 16 may be provided with a heating section for heating the inside of the reaction section 16 and a pressurizing section for maintaining the pressure inside the reaction section 16 at a predetermined value or more. The temperature inside the reaction section 16 is preferably set to be 250°C or higher and 400°C or lower, and more preferably 250°C or higher and 350°C or lower. Also, the pressure inside the reaction section 16 is preferably 1 MPa or higher and 30 MPa or lower, and more preferably 6 MPa or higher and 25 MPa or lower. The pressurizing section and the heating section may be controlled by the control section 20.

[0036] (Separation section) The separation section 18 is introduced with a second solvent M2 containing the second depolymerized polyester P2 (a reaction solvent in which the depolymerized polyester is dissolved), and separates the second solvent M2 into the reaction solvent M and monomers. More specifically, the separation section 18 separates the second solvent M2 into the reaction solvent M, a monomer D derived from a carboxylic acid contained in the second depolymerized polyester P2, a monomer E of an alcohol component contained in the second depolymerized polyester P2, and a residual substance R. The residual substance R is a component other than the reaction solvent M, the monomer D, and the monomer E in the second solvent M2 and contains oligomers.

[0037] In the present embodiment, the separation section 18 includes a first separation section 18A, a second separation section 18B, and a third separation section 18C.

[0038] The first separation unit 18A is a separation tower connected to the lead-out pipe 16a. The second solvent M2 containing the second depolymerized polyester P2 is introduced into the first separation unit 18A via the lead-out pipe 16a. The first separation unit 18A separates the second solvent M2 into a low-boiling component and a high-boiling component having a boiling point higher than that of the low-boiling component. For example, in the first separation unit 18A, the second solvent M2 may be set at a predetermined temperature, and the component that has become a gas may be regarded as the low-boiling component, and the liquid component may be regarded as the high-boiling component. The lead-out pipes 18Aa and 18Ab are connected to the first separation unit 18A. The low-boiling component is led out from the lead-out pipe 18Aa, and the high-boiling component is led out from the lead-out pipe 18Ab.

[0039] The second separation unit 18B is a separation tower connected to the first separation unit 18A via the lead-out pipe 18Aa. The low-boiling component is introduced into the second separation unit 18B via the lead-out pipe 18Aa. The second separation unit 18B separates the low-boiling component into the reaction solvent M and the monomer E. The lead-out pipes 18Ba and 18Bb are connected to the second separation unit 18B. The reaction solvent M is led out from the lead-out pipe 18Ba, and the monomer E is led out from the lead-out pipe 18Bb.

[0040] The lead-out pipe 18Ba is connected to the second separation unit 18B and the solvent storage unit 14. Therefore, the reaction solvent M led out from the second separation unit 18B is returned to the solvent storage unit 14 and reused for the monomerization of the polyester. Further, an adjustment unit 18Bb is provided in the lead-out pipe 18Ba. The adjustment unit 18Bb is a mechanism for supplying the reaction solvent M led out from the second separation unit 18B to the solvent storage unit 14, and is a pump in the present embodiment.

[0041] The third separation unit 18C is a separation tower connected to the first separation unit 18A via the lead-out pipe 18Ab. High-boiling components are introduced into the third separation unit 18C via the lead-out pipe 18Ab. The third separation unit 18C separates the high-boiling components into a residue R with an even higher boiling point, a low-boiling component containing the reaction solvent M and the monomer E, and the monomer D. The third separation unit 18C is connected to lead-out pipes 18Ca, 18Cb, and 18Cc. The lead-out pipe 18Ca is connected to the second separation unit 18B. The low-boiling component separated within the third separation unit 18C is led out to the second separation unit 18B via the lead-out pipe 18Ca. Also, the monomer D separated within the third separation unit 18C is led out from the lead-out pipe 18Cb, and the residue R separated within the third separation unit 18C is led out from the lead-out pipe 18Cc.

[0042] The third separation unit 18C is connected to an introduction pipe 18Cd. The introduction pipe 18Cd is also connected to the dissolution unit 12 and introduces the monomer D led out from the third separation unit 18C into the dissolution unit 12. In the example of FIG. 2, the introduction pipe 18Cd branches off from the lead-out pipe 18Cb. The introduction pipe 18Cd is provided with an adjustment unit 18Ce for adjusting the amount of the monomer D supplied from the third separation unit 18C to the dissolution unit 12. The adjustment unit 18Ce is, for example, an on-off valve. In the open state, the monomer D is supplied to the dissolution unit 12, and in the closed state, the supply of the monomer D to the dissolution unit 12 is stopped. However, the adjustment unit 18Ce is not limited to being an on-off valve and may be any mechanism capable of adjusting the supply of the monomer D to the dissolution unit 12. In this embodiment, the adjustment unit 18Ce is provided at the branching point of the introduction pipe 18Cd from the lead-out pipe 18Cb, but the position where it is provided is not limited thereto and may be arbitrary. Also, the introduction pipe 18Cd may not be connected to the lead-out pipe 18Cb and may be directly connected to the third separation unit 18C. Also, for example, a storage unit (tank) for storing the monomer D may be provided in the lead-out pipe 18Cb, and the introduction pipe 18Cd may be connected to the storage unit.

[0043] A introducing pipe 18Cf is connected to the third separation part 18C. The introducing pipe 18Cf is also connected to the dissolving part 12, and introduces the residual substance R derived from the third separation part 18C into the dissolving part 12. In the example of FIG. 2, the introducing pipe 18Cf branches from the leading-out pipe 18Cc. The introducing pipe 18Cf is provided with an adjusting part 18Cg for adjusting the amount of the residual substance R supplied from the third separation part 18C to the dissolving part 12. The adjusting part 18Cg is, for example, an on-off valve. In the open state, the residual substance R is supplied to the dissolving part 12, and in the closed state, the supply of the residual substance R to the dissolving part 12 is stopped. However, the adjusting part 18Cg is not limited to being an on-off valve, and may be any mechanism capable of adjusting the supply of the residual substance R to the dissolving part 12. In the present embodiment, the adjusting part 18Cg is provided at the branching position of the introducing pipe 18Cf from the leading-out pipe 18Cc, but the position where it is provided is not limited thereto and may be arbitrary. Further, the introducing pipe 18Cf may not be connected to the leading-out pipe 18Cc and may be directly connected to the third separation part 18C.

[0044] Note that, for example, a storage part (tank) for storing the residual substance R may be provided in the leading-out pipe 18Cc, and the introducing pipe 18Cf may be connected to the storage part. Further, a filter for collecting foreign matters in the residual substance R while allowing oligomers in the residual substance R to pass through may be provided in the introducing pipe 18Cf.

[0045] In the example of FIG. 2, the introducing pipe 10a, the introducing pipe 18Cd, and the introducing pipe 18Cf connected to the dissolving part 12 are directly connected to the dissolving part 12 without being connected to each other. However, at least two of the introducing pipe 10a, the introducing pipe 18Cd, and the introducing pipe 18Cf may be connected (merged), and the connected pipe may be connected to the dissolving part 12.

[0046] In this embodiment, since the polyester solution P is a solution in which the polyester is dissolved in the monomer D, the monomer D is introduced into the dissolution part 12 through the introduction pipe 18Cd. However, when the polyester solution P is a solution in which the polyester is dissolved in the monomer E, the introduction pipe 18Cd may be connected to the second separation part 18B and the dissolution part 12. That is, in this case, the monomer E separated in the second separation part 18B is introduced into the dissolution part 12 through the introduction pipe 18Cd. A storage part (tank) for storing the monomer E may be provided, and the introduction pipe 18Cd may be connected to the storage part.

[0047] (Detection unit) The detection unit 19 is a sensor that detects a parameter related to the concentration of the monomer contained in the second solvent M2 (reaction solvent in which the depolymerized polyester is dissolved) containing the second depolymerized polyester P2. The parameter here refers to a parameter related to the concentration of the monomer contained in the second solvent M2. The detection unit 19 is provided at a position where this parameter can be detected. Here, the monomer contained in the second solvent M2 is the monomer D in this example, but when the polyester solution P is generated with the monomer E, it may refer to the monomer E.

[0048] In this embodiment, the parameter detected by the detection unit 19 is the temperature of the separation unit 18. When the concentration of the monomer contained in the second solvent M2 increases, the temperature of the separation unit 18 increases. Therefore, the temperature of the separation unit 18 can be said to be a parameter related to the concentration of the monomer contained in the second solvent M2. In this case, the detection unit 19 is a temperature sensor and is provided at a position where the temperature of the separation unit 18 can be detected. The temperature of the separation unit 18 here may be the temperature of the outer wall of the separation unit 18 or the temperature inside the separation unit 18. It is preferable that the parameter detected by the detection unit 19 is the temperature of the first separation unit 18A. By detecting the temperature of the first separation unit 18A into which the second solvent M2 is introduced from the reaction unit 16, a change in the concentration of the monomer contained in the second solvent M2 can be detected promptly. Furthermore, it is more preferable that it is the temperature of the lower part of the first separation unit 18A (a position below the center of the first separation unit 18A). By detecting the temperature of the lower part of the first separation unit 18A, the concentration of the monomer contained in the second solvent M2 can be detected more suitably.

[0049] Note that the parameter detected by the detection unit 19 may be the concentration of the monomer itself contained in the second solvent M2 derived from the reaction unit 16. In this case, the detection unit 19 is a concentration detection sensor and is provided in the lead-out pipe 16a.

[0050] (Operation of the monomer production system) Next, the operation of the monomer production system 1 will be described. The control unit 20 causes the polyester raw material Pm, the monomer D, and the residual substance R to be introduced into the dissolution unit 12 to generate a polyester solution P. Then, the control unit 20 introduces the polyester solution P and the reaction solvent M into the first reaction unit 16A for depolymerization, and extracts the first depolymerized polyester P1 into the reaction solvent M. Then, the first solvent M1 from which the first depolymerized polyester P1 has been extracted is introduced into the second reaction unit 16B, and the first depolymerized polyester P1 is further depolymerized in the second reaction unit 16B to generate a second depolymerized polyester P2. Then, in the separation unit 18, the second solvent M2 in which the second depolymerized polyester P2 is dissolved is separated into the reaction solvent M, the monomer D, the monomer E, and the residual substance R.

[0051] (Control Unit) Figure 3 is a schematic block diagram of the control unit. The control unit 20 is a control device that controls the monomer manufacturing system 1 and is a computer in this embodiment. As shown in Figure 3, the control unit 20 includes an input unit 30, an output unit 32, a communication unit 34, a storage unit 36, and a processing unit 38.

[0052] The input unit 30 is a device that receives the user's operation and may be, for example, a mouse, a keyboard, a touch panel, etc. The output unit 32 is a device that outputs information and may be, for example, a display that displays an image. Note that the input unit 30 and the output unit 32 are not essential components. The communication unit 34 is a module that communicates with external devices, etc., and may include, for example, an antenna. The communication method by the communication unit 34 is wireless communication in this embodiment, but the communication method may be arbitrary. Note that the control unit 20 may be configured as a single device, may be configured integrally with other devices, or may be configured as a system combining various devices such as an arithmetic device and a data server, and is not particularly limited.

[0053] The storage unit 36 is a memory that stores various information such as the calculation content and programs of the processing unit 38, and includes, for example, at least one of a main storage device such as a RAM (Random Access Memory), a ROM (Read Only Memory), and an external storage device such as an HDD (Hard Disk Drive). The program for the processing unit 38 stored by the storage unit 36 may be stored in a recording medium readable by the control unit 20.

[0054] The processing unit 38 is an arithmetic unit and includes an arithmetic circuit such as a CPU (Central Processing Unit). The processing unit 38 includes a detection control unit 40, an information acquisition unit 42, and a system control unit 44. The processing unit 38 reads a program (software) from the storage unit 36 and executes it to realize the detection control unit 40, the information acquisition unit 42, and the system control unit 44, and execute their processes. Note that the processing unit 38 may execute these processes by one CPU, or may include a plurality of CPUs and execute the processes with these plurality of CPUs. Further, at least a part of the detection control unit 40, the information acquisition unit 42, and the system control unit 44 may be realized by hardware.

[0055] The detection control unit 40 controls the detection unit 19 to cause the detection unit 19 to detect a parameter and acquire the detection result. The information acquisition unit 42 acquires information on the amount of polyester in the polyester raw material Pm introduced into the melting unit 12 (or the raw material storage unit 10). The system control unit 44 controls each mechanism of the monomer production system 1. For example, the system control unit 44 controls the adjustment unit 10b to control the amount of the polyester raw material Pm supplied from the raw material storage unit 10 to the melting unit 12. The system control unit 44 controls the supply unit 12b to control the amount of the polyester solution P supplied from the melting unit 12 to the first reaction unit 16A. The system control unit 44 controls the heating unit 12c to control the degree of heating of the polyester solution P. The system control unit 44 controls the adjustment unit 14c to control the amount of the reaction solvent M supplied from the solvent storage unit 14 to the first reaction unit 16A. The system control unit 44 controls the heating and pressurizing unit 14b to bring the reaction solvent M into a supercritical state or a subcritical state (pressurized gas or pressurized liquid). The system control unit 44 controls the adjustment unit 18Ce to control the supply amount of the monomer D to the melting unit 12. The system control unit 44 controls the adjustment unit 18Cg to control the supply amount of the residual substance R to the melting unit 12. The system control unit 44 controls the adjustment unit 18Bb to control the supply amount of the reaction solvent M to the solvent storage unit 14.

[0056] (Processing of the control unit) In this embodiment, the control unit 20 controls the monomer production system 1 based on at least one of the parameters detected by the detection control unit 40 and the amount of polyester in the polyester raw material Pm acquired by the information acquisition unit 42. It is preferable that the control unit 20 controls the monomer production system 1 based on both the parameters and the amount of polyester.

[0057] Hereinafter, the specific processing content of the control unit 20 will be described. Note that the control unit 20 only needs to perform at least one of the various controls described below. However, it is preferable that the control unit 20 performs control by combining two or more of the various controls described below, and it is more preferable that the control unit 20 performs all of the various controls described below. That is, it can be said that the control unit 20 preferably performs any two controls, any three controls, any four controls, any five controls, any six controls, any seven controls, or all eight controls among the first control to the eighth control described later in combination.

[0058] (Control of the introduction amount of the polyester raw material Pm) (First control) The detection control unit 40 causes the detection unit 19 to detect a parameter (a parameter related to the concentration of the monomer contained in the second solvent M2). The system control unit 44 controls the introduction amount of the polyester raw material Pm into the dissolution unit 12 based on the parameter detected by the detection unit 19. That is, the system control unit 44 determines the introduction amount of the polyester raw material Pm into the dissolution unit 12 based on the parameter detected by the detection unit 19, and controls the adjustment unit 10b to supply the polyester raw material Pm to the dissolution unit 12 so that the determined introduction amount is achieved. Note that the system control unit 44 may determine the introduction amount of the polyester raw material Pm by any method based on the parameter. For example, when the parameter indicates that the concentration of the monomer contained in the second solvent M2 is higher than a predetermined threshold, the system control unit 44 may reduce the introduction amount of the polyester raw material Pm assuming that more monomers are generated than expected. Note that the case where the parameter indicates that the concentration of the monomer is higher than a predetermined threshold refers to, for example, that the detected temperature of the separation unit 18 is higher than a predetermined threshold or that the detected concentration of the monomer itself is higher than a predetermined threshold. On the other hand, when the parameter indicates that the concentration of the monomer contained in the second solvent M2 is less than a predetermined threshold, the system control unit 44 may increase the introduction amount of the polyester raw material Pm assuming that the amount of monomer generated is less than expected.

[0059] In this way, by controlling the introduction amount of the polyester raw material Pm into the dissolution unit 12 based on the parameter related to the concentration of the monomer contained in the second solvent M2, it is possible to suppress the deviation of the monomer generation amount from the assumption, and the monomer can be appropriately manufactured. For example, the amount of monomer generated in the reaction in the reaction unit 16 (the amount of monomer in the second solvent M2) may vary depending on the polyester purity in the polyester raw material Pm and the reaction state in the reaction unit 16. On the other hand, by controlling the introduction amount of the polyester raw material Pm based on the amount of monomer contained in the second solvent M2, the introduction amount of the polyester raw material Pm can be adjusted according to the monomer generation state, so that the monomer can be appropriately manufactured.

[0060] (Second Control) The information acquisition unit 42 acquires information on the amount of polyester in the polyester raw material Pm. The amount of polyester in the polyester raw material Pm refers to the amount of polyester contained in the polyester raw material Pm (the amount of contained polyester relative to the weight of the polyester raw material Pm), but may also refer to the amount of impurities contained in the polyester raw material Pm (the amount of contained impurities relative to the weight of the polyester raw material Pm). The information acquisition unit 42 may acquire the amount of polyester by any method. For example, the amount of polyester in the polyester raw material Pm is estimated based on the type of the supplied polyester raw material Pm, and the information acquisition unit 42 may acquire the estimated amount of polyester in the polyester raw material Pm. Further, the information acquisition unit 42 may calculate the amount of polyester in the polyester raw material Pm based on the type of the supplied polyester raw material Pm. In this case, for example, the correspondence relationship between the type of the polyester raw material Pm and the amount of polyester is preset, and the information acquisition unit 42 may calculate the amount of polyester in the polyester raw material Pm based on the correspondence relationship and the type of the supplied polyester raw material Pm. The system control unit 44 may control the introduction amount of the polyester raw material Pm into the melting unit 12 based on the amount of polyester in the polyester raw material Pm. That is, the system control unit 44 determines the introduction amount of the polyester raw material Pm into the melting unit 12 based on the amount of polyester in the polyester raw material Pm, and controls the adjustment unit 10b to supply the polyester raw material Pm to the melting unit 12 so as to obtain the determined introduction amount. Note that the system control unit 44 may determine the introduction amount of the polyester raw material Pm by any method based on the amount of polyester in the polyester raw material Pm. For example, when the amount of polyester is higher than a predetermined threshold, the system control unit 44 may reduce the introduction amount of the polyester raw material Pm assuming that the purity of the polyester is higher than expected. On the other hand, when the amount of polyester is lower than a predetermined threshold, the system control unit 44 may increase the introduction amount of the polyester raw material Pm assuming that the purity of the polyester is lower than expected.

[0061] In this way, by controlling the introduction amount of the polyester raw material Pm into the dissolution unit 12 based on the amount of polyester in the polyester raw material Pm, it is possible to suppress the deviation of the monomer production amount from the assumption, and the monomer can be appropriately produced. The amount of polyester in the polyester raw material Pm, that is, the purity of the polyester, may vary depending on the type of the polyester raw material Pm, etc. The amount of monomer produced varies depending on the purity of the polyester, and there is a risk that the monomer cannot be produced in the assumed amount. On the other hand, by controlling the introduction amount of the polyester raw material Pm based on the purity of the polyester, the introduction amount of the polyester raw material Pm can be adjusted according to the purity of the polyester, so that the monomer can be appropriately produced.

[0062] (Control of the introduction amount of residual substances) (Third control) The system control unit 44 controls the supply amount of the residual substance R to the dissolution unit 12 based on the parameters detected by the detection unit 19. That is, the system control unit 44 determines the supply amount of the residual substance R to the dissolution unit 12 based on the parameters detected by the detection unit 19, and controls the adjustment unit 18Cg to supply the residual substance R to the dissolution unit 12 so as to obtain the determined supply amount. The system control unit 44 may determine the introduction amount of the supply amount of the residual substance R by any method based on the parameters. For example, when the parameter indicates that the concentration of the monomer contained in the second solvent M2 is higher than a predetermined threshold, the system control unit 44 may reduce the supply amount of the residual substance R assuming that more monomers are produced than expected. On the other hand, when the parameter indicates that the concentration of the monomer contained in the second solvent M2 is less than a predetermined threshold, the system control unit 44 may increase the supply amount of the residual substance R assuming that the production amount of the monomer is less than expected. Since the residual substance R is a monomer production source, the production amount of the monomer can be appropriately controlled by such control.

[0063] In this way, by controlling the supply amount of the residual substance R to the dissolution unit 12 based on the parameter related to the concentration of the monomer contained in the second solvent M2, it is possible to suppress the deviation of the production amount of the monomer from the assumption, and the monomer can be appropriately produced. In particular, in the case of a system in which the residual substance R is returned to the dissolution unit 12 on the upper stage side, the deviation of the control on the upper stage side is amplified, and there is a risk that the deviation of the production of the monomer from the assumption becomes large. On the other hand, by controlling the amount of the residual substance R to be returned based on the amount of the monomer contained in the second solvent M2, the amplification of the control deviation can be suppressed, and the monomer can be appropriately produced.

[0064] (Fourth Control) The system control unit 44 may control the supply amount of the residual substance R to the dissolution unit 12 based on the amount of polyester in the polyester raw material Pm. That is, the system control unit 44 determines the supply amount of the residual substance R to the dissolution unit 12 based on the amount of polyester in the polyester raw material Pm, and controls the adjustment unit 18Cg to supply the residual substance R to the dissolution unit 12 so as to have the determined introduction amount. The system control unit 44 may determine the supply amount of the residual substance R by an arbitrary method based on the amount of polyester in the polyester raw material Pm. For example, when the amount of polyester is higher than a predetermined threshold, the system control unit 44 may reduce the supply amount of the residual substance R assuming that the purity of the polyester is higher than expected. On the other hand, when the amount of polyester is lower than a predetermined threshold, the system control unit 44 may increase the supply amount of the residual substance R assuming that the purity of the polyester is lower than expected.

[0065] In this way, by controlling the amount of the residual substance R to be returned based on the amount of polyester in the polyester raw material Pm, it is possible to adjust the amount of the residual substance R to be returned according to the purity of the polyester, suppress the amplification of the control deviation, and appropriately produce the monomer.

[0066] (Control of the Supply Amount of the Reaction Solvent) (Fifth Control) The system control unit 44 controls the supply amount of the reaction solvent M to the reaction unit 16 (the first reaction unit 16A) based on the parameters detected by the detection unit 19. That is, the system control unit 44 determines the supply amount of the reaction solvent M to the reaction unit 16 based on the parameters detected by the detection unit 19, and controls the adjustment unit 14c to supply the reaction solvent M to the reaction unit 16 so as to obtain the determined supply amount. Note that the system control unit 44 may determine the supply amount of the reaction solvent M by any method based on the parameters. For example, when the parameter indicates that the concentration of the monomer contained in the second solvent M2 is less than a predetermined threshold value, the system control unit 44 may increase the supply amount of the reaction solvent M assuming that the production amount of the monomer is less than expected.

[0067] In this way, by controlling the supply amount of the reaction solvent M based on the parameter related to the concentration of the monomer contained in the second solvent M2, it is possible to suppress the deviation of the production amount of the monomer from the assumption, and the monomer can be appropriately produced.

[0068] (Sixth control) The system control unit 44 may control the supply amount of the reaction solvent M to the reaction unit 16 (the first reaction unit 16A) based on the amount of polyester in the polyester raw material Pm. That is, the system control unit 44 determines the supply amount of the reaction solvent M to the reaction unit 16 based on the amount of polyester in the polyester raw material Pm, and controls the adjustment unit 14c to supply the reaction solvent M to the reaction unit 16 so as to obtain the determined supply amount. Note that the system control unit 44 may determine the supply amount of the reaction solvent M by any method based on the amount of polyester in the polyester raw material Pm. For example, when the amount of polyester is higher than a predetermined threshold value, the system control unit 44 may increase the supply amount of the reaction solvent M assuming that the purity of the polyester is higher than expected. On the other hand, when the amount of polyester is lower than a predetermined threshold value, the system control unit 44 may decrease the supply amount of the reaction solvent M assuming that the purity of the polyester is lower than expected.

[0069] In this way, by controlling the supply amount of the reaction solvent M based on the amount of polyester in the polyester raw material Pm, it is possible to suppress the deviation of the monomer production amount from the assumption, and the monomer can be appropriately produced.

[0070] (Control of the introduction amount of the reaction solvent) (Seventh control) The system control unit 44 controls the introduction amount of the reaction solvent M from the separation unit 18 (second separation unit 18B) to the solvent storage unit 14 based on the parameters detected by the detection unit 19. That is, the system control unit 44 determines the introduction amount of the reaction solvent M to the solvent storage unit 14 based on the parameters detected by the detection unit 19, and controls the adjustment unit 18Bb to supply the reaction solvent M to the solvent storage unit 14 so as to reach the determined introduction amount. Note that the system control unit 44 may determine the introduction amount of the reaction solvent M by any method based on the parameters. For example, when the parameter indicates that the concentration of the monomer contained in the second solvent M2 is less than a predetermined threshold value, the system control unit 44 may increase the introduction amount of the reaction solvent M assuming that the monomer production amount is less than expected.

[0071] In this way, by controlling the amount of the reaction solvent M returned based on the parameter related to the concentration of the monomer contained in the second solvent M2, the amplification of the control deviation can be suppressed, and the monomer can be appropriately produced.

[0072] (Eighth control) The system control unit 44 may control the introduction amount of the reaction solvent M from the separation unit 18 (the second separation unit 18B) to the solvent storage unit 14 based on the amount of polyester in the polyester raw material Pm. That is, the system control unit 44 determines the introduction amount of the reaction solvent M to the solvent storage unit 14 based on the amount of polyester in the polyester raw material Pm, and controls the adjustment unit 14c to supply the reaction solvent M to the solvent storage unit 14 so as to obtain the determined supply amount. Note that the system control unit 44 may determine the supply amount of the reaction solvent M by an arbitrary method based on the amount of polyester in the polyester raw material Pm. For example, when the amount of polyester is higher than a predetermined threshold, the system control unit 44 may increase the introduction amount of the reaction solvent M assuming that the purity of polyester is higher than expected. On the other hand, when the amount of polyester is lower than a predetermined threshold, the system control unit 44 may decrease the introduction amount of the reaction solvent M assuming that the purity of polyester is lower than expected.

[0073] In this way, by controlling the amount of the reaction solvent M returned based on the amount of polyester in the polyester raw material Pm, the amplification of the control deviation can be suppressed, and the monomer can be appropriately manufactured.

[0074] Note that the control unit 20 may perform at least one of the first to eighth controls described above as long as it performs at least one of them. For example, the control unit 20 preferably performs at least the fourth control (supply of the residual substance R) among the second, fourth, sixth, and eighth controls based on the amount of polyester in the polyester raw material Pm, and more preferably performs at least one of the sixth and eighth controls (supply of the reaction solvent M) in addition to the fourth control. Further, for example, the control unit 20 preferably performs at least the first control (supply of the polyester raw material Pm) among the first, third, fifth, and sixth controls based on the parameter detected by the detection unit 19, more preferably performs the third control (supply of the residual substance R) in addition to the fourth control, and still more preferably performs at least one of the sixth and eighth controls (supply of the reaction solvent M) in addition to the fourth control and the third control.

[0075] (Temperature and pressure of the reaction section) In addition, even when the parameters detected by the detection unit 19 or the amount of polyester in the polyester raw material Pm fluctuates, the system control unit 44 preferably does not perform control to vary the temperature and pressure inside the reaction unit 16, but keeps the temperature and pressure inside the reaction unit 16 within a certain range. Thereby, the reaction in the reaction unit 16 can be stably performed.

[0076] (Control by Machine Learning) In addition, each control described above may be executed using a model learned by a machine learning method. That is, the system control unit 44 may input an input value to a model that has learned the correspondence between input and output by a machine learning method to obtain an output value, and perform control based on the output value. Thereby, control can be performed with high precision, and monomers can be appropriately manufactured. As the model here, any machine learning model such as a CNN (Convolutional Neural Network) model may be used.

[0077] For example, in the case of the first control described above, the system control unit 44 inputs the parameters detected by the detection unit 19 to a model that has learned the correspondence between the parameters (input) and the introduction amount (output) of the polyester raw material Pm as the output, thereby determining the supply amount of the polyester raw material Pm. In this case, it is preferable that the system control unit 44 uses the variation pattern of the parameters (the variation pattern of the parameters in the time series) as the input value. In this case, the system control unit 44 inputs the parameters detected by the detection unit 19 to a model that has learned the correspondence between the variation pattern of the parameters and the introduction amount of the polyester raw material Pm, thereby determining the supply amount of the polyester raw material Pm. Using the variation pattern of the parameters as the input may also be adopted in other controls.

[0078] For example, in the case of the above-described second control, the system control unit 44 inputs the amount of polyester acquired by the information acquisition unit 42 into a model that has learned the correspondence between the amount of polyester (input) in the polyester raw material Pm and the introduction amount of the polyester raw material Pm (output), thereby determining the supply amount of the polyester raw material Pm.

[0079] For example, in the case of the above-described third control, the system control unit 44 inputs the parameter detected by the detection unit 19 into a model that has learned the correspondence between the parameter (input) and the supply amount of the residual substance R (output), thereby determining the supply amount of the residual substance R.

[0080] For example, in the case of the above-described fourth control, the system control unit 44 inputs the amount of polyester acquired by the information acquisition unit 42 into a model that has learned the correspondence between the amount of polyester (input) in the polyester raw material Pm and the supply amount of the residual substance R (output), thereby determining the supply amount of the residual substance R.

[0081] For example, in the case of the above-described fifth control, the system control unit 44 inputs the parameter detected by the detection unit 19 into a model that has learned the correspondence between the parameter (input) and the supply amount of the reaction solvent M (output), thereby determining the supply amount of the reaction solvent M.

[0082] For example, in the case of the above-described sixth control, the system control unit 44 inputs the amount of polyester acquired by the information acquisition unit 42 into a model that has learned the correspondence between the amount of polyester (input) in the polyester raw material Pm and the supply amount of the reaction solvent M (output), thereby determining the supply amount of the reaction solvent M.

[0083] For example, in the case of the above-described seventh control, the system control unit 44 inputs the parameter detected by the detection unit 19 into a model that has learned the correspondence between the parameter (input) and the introduction amount of the reaction solvent M (output), thereby determining the introduction amount of the reaction solvent M.

[0084] For example, in the case of the above-described eighth control, the system control unit 44 inputs the amount of polyester in the polyester raw material Pm (input) into a model that has learned the correspondence relationship between the amount of polyester and the introduction amount of the reaction solvent M (output), and thereby determines the introduction amount of the reaction solvent M.

[0085] (Control Flow) The control flow of the control unit 20 described above will be described. FIG. 4 is a flowchart for explaining the control flow of the control unit. As shown in FIG. 4, the control unit 20 causes the detection unit 19 to detect a parameter by the detection control unit 40 (step S10), acquires information on the amount of polyester in the polyester raw material Pm by the information acquisition unit 42 (step S12), and controls the monomer production system 1 based on at least one of the parameter and the amount of polyester by the system control unit 44 (step S14). The control content by the system control unit 44 is as described above, so the description thereof is omitted.

[0086] (Effect) As described above, the monomer production system 1 according to the first aspect of the present disclosure includes a dissolution unit 12 into which a polyester raw material Pm containing polyester is introduced and in which a polyester solution P in which the polyester is dissolved is stored, a polyester solution P, and a reaction solvent M that reacts with the polyester, and depolymerizes the polyester in the polyester solution P to generate a reaction solvent M (second solvent M2) in which the depolymerized polyester is dissolved. A separation unit 18 that separates the reaction solvent (second solvent M2) in which the depolymerized polyester is dissolved into a monomer and the reaction solvent M, a detection unit 19 that detects a parameter related to the concentration of the monomer contained in the reaction solvent M (second solvent M2) in which the depolymerized polyester is dissolved, and a control unit 20 that controls the introduction amount of the polyester raw material Pm into the dissolution unit 12 based on the parameter. According to the present disclosure, by controlling the introduction amount of the polyester raw material Pm based on the amount of the monomer contained in the second solvent M2, the introduction amount of the polyester raw material Pm can be adjusted according to the production state of the monomer, so that the monomer can be appropriately produced.

[0087] The monomer production system 1 according to the second aspect of the present disclosure is the monomer production system 1 according to the first aspect, wherein the detection unit 19 detects, as a parameter, the concentration of the monomer contained in the reaction solvent M (second solvent M2) in which the depolymerized polyester is dissolved. According to the present disclosure, since the introduction amount of the polyester raw material Pm can be adjusted according to the production state of the monomer, the monomer can be appropriately produced.

[0088] The monomer production system 1 according to the third aspect of the present disclosure is the monomer production system 1 according to the first aspect, wherein the detection unit 19 detects, as a parameter, the temperature of the separation unit 18. According to the present disclosure, by adjusting the introduction amount of the polyester raw material Pm according to the temperature of the separation unit 18, the monomer can be appropriately produced.

[0089] The monomer production system 1 according to the fourth aspect of the present disclosure is the monomer production system 1 according to any one of the first to third aspects, wherein the separation unit 18 further has an adjustment unit 18Cg that separates the second solvent M2 into a monomer, a reaction solvent M, and a residual substance R that is an oligomer different from the monomer and the reaction solvent M, and supplies the residual substance R separated by the separation unit 18 to the dissolution unit 12, and the control unit 20 controls the supply amount of the residual substance R to the dissolution unit 12 by the adjustment unit 18Cg based on the parameter. By controlling the amount of the residual substance R returned based on the amount of the monomer contained in the second solvent M2, the amplification of the control deviation can be suppressed, and the monomer can be appropriately produced.

[0090] The monomer production system 1 according to the fifth aspect of the present disclosure is the monomer production system 1 according to any one of the first to fourth aspects, further having an adjustment unit 14c that supplies the reaction solvent M to the reaction unit 16, and the control unit 20 controls the supply amount of the reaction solvent M to the reaction unit 16 by the adjustment unit 14c based on the parameter. According to the present disclosure, by controlling the supply amount of the reaction solvent M based on a parameter related to the concentration of the monomer contained in the second solvent M2, it is possible to suppress the production amount of the monomer from deviating from the assumption, and the monomer can be appropriately produced.

[0091] The monomer production system 1 according to the sixth aspect of the present disclosure is the monomer production system 1 according to any one of the first to fifth aspects, and it is preferable that the control unit 20 executes control based on the amount of polyester contained in the polyester raw material. By performing control based on the parameter related to the concentration of the monomer contained in the second solvent M2 and the amount of polyester contained in the polyester raw material, the monomer can be appropriately produced.

[0092] The monomer production system 1 according to the seventh aspect of the present disclosure is the monomer production system 1 according to any one of the first to sixth aspects, and the control unit 20 inputs the parameter detected by the detection unit 19 into a model that has learned the correspondence relationship between the parameter and the introduction amount of the polyester raw material Pm, thereby determining the introduction amount of the polyester raw material Pm into the dissolution unit 12. By using the machine-learned model, control can be performed with high precision, and the monomer can be appropriately produced.

[0093] The control method according to the eighth aspect of the present disclosure controls a monomer production system 1 having a dissolution unit 12 into which a polyester raw material Pm containing polyester is introduced and a polyester solution P in which the polyester is dissolved is stored, a polyester solution P, and a reaction solvent M that reacts with the polyester, and that depolymerizes the polyester in the polyester solution P to generate a reaction solvent M (second solvent M2) in which the depolymerized polyester is dissolved, and a separation unit 18 that separates the reaction solvent (second solvent M2) in which the depolymerized polyester is dissolved into a monomer and the reaction solvent M. This control method includes a step of detecting a parameter related to the concentration of the monomer contained in the reaction solvent M (second solvent M2) in which the depolymerized polyester is dissolved, and a step of controlling the introduction amount of the polyester raw material Pm into the dissolution unit 12 based on the parameter. According to the present disclosure, by controlling the introduction amount of the polyester raw material Pm based on the amount of the monomer contained in the second solvent M2, the introduction amount of the polyester raw material Pm can be adjusted according to the production state of the monomer, so that the monomer can be appropriately produced.

[0094] The program according to the ninth aspect of the present disclosure causes a computer to execute control of a monomer production system 1 having a dissolution unit 12 in which a polyester solution P in which a polyester is dissolved is stored by introducing a polyester raw material Pm containing a polyester, a reaction unit 16 in which the polyester solution P and a reaction solvent M that reacts with the polyester are introduced to depolymerize the polyester in the polyester solution P and generate a reaction solvent M (second solvent M2) in which the depolymerized polyester is dissolved, and a separation unit 18 that separates the reaction solvent (second solvent M2) in which the depolymerized polyester is dissolved into a monomer and the reaction solvent M. This program causes the computer to execute a step of detecting a parameter regarding the concentration of the monomer contained in the reaction solvent M (second solvent M2) in which the depolymerized polyester is dissolved, and a step of controlling the introduction amount of the polyester raw material Pm into the dissolution unit 12 based on the parameter. According to the present disclosure, by controlling the introduction amount of the polyester raw material Pm based on the amount of the monomer contained in the second solvent M2, the introduction amount of the polyester raw material Pm can be adjusted according to the production state of the monomer, so that the monomer can be appropriately produced.

[0095] As described above, the embodiments of the present disclosure have been described, but the embodiments are not limited by the content of this embodiment. Further, the components described above include those that can be easily assumed by those skilled in the art, substantially the same components, and those within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or changes of the components can be made without departing from the gist of the above-described embodiments.

Explanation of Reference Numerals

[0096] 10 Storage unit 12 Dissolution unit 14 Solvent storage unit 16 Reaction unit 16A First reaction unit 16B Second reaction unit 18 Separation unit 20 Control unit D, E Monomer M Reaction solvent M1 First solvent Solvent M2, the second solvent Solution P, polyester solution Polyester raw material Pm Depolymerized polyester P1, the first depolymerized polyester Depolymerized polyester P2, the second depolymerized polyester

Claims

1. A dissolution section where a polyester raw material containing polyester is introduced and a polyester solution in which the polyester is dissolved is stored; A reaction section where the polyester solution and a reaction solvent that reacts with the polyester are introduced to depolymerize the polyester in the polyester solution and generate a reaction solvent in which the depolymerized polyester is dissolved; A separation section that separates the reaction solvent in which the depolymerized polyester is dissolved into a monomer and a reaction solvent; A detection section that detects a parameter related to the concentration of the monomer contained in the reaction solvent in which the depolymerized polyester is dissolved; A control section that controls the introduction amount of the polyester raw material into the dissolution section based on the parameter; having a monomer production system.

2. The detection section detects the concentration of the monomer contained in the reaction solvent in which the depolymerized polyester is dissolved as the parameter, The monomer production system according to Claim 1.

3. The detection section detects the temperature of the separation section as the parameter, The monomer production system according to Claim 1.

4. The separation section separates the reaction solvent in which the depolymerized polyester is dissolved into a monomer, a reaction solvent, and a residual substance that is an oligomer different from the monomer and the reaction solvent, further having an adjustment section that supplies the residual substance separated by the separation section to the dissolution section, The control section controls the supply amount of the residual substance to the dissolution section by the adjustment section based on the parameter, The monomer production system according to any one of Claims 1 to 3.

5. further having an adjustment section that supplies the reaction solvent to the reaction section, The control section controls the supply amount of the reaction solvent to the reaction section by the adjustment section based on the parameter, The monomer production system according to any one of Claims 1 to 3.

6. The control section executes control based also on the amount of the polyester contained in the polyester raw material, The monomer production system according to any one of Claims 1 to 3.

7. The control section determines the introduction amount of the polyester raw material into the dissolution section by inputting the parameter detected by the detection section into a model that has learned the correspondence between the parameter and the introduction amount of the polyester raw material. The monomer production system according to any one of claims 1 to 3.

8. A dissolution unit into which a polyester raw material containing polyester is introduced and a polyester solution in which the polyester is dissolved is stored, A reaction unit into which the polyester solution and a reaction solvent that reacts with the polyester are introduced to depolymerize the polyester in the polyester solution and generate a reaction solvent in which the depolymerized polyester is dissolved, A separation unit that separates the reaction solvent in which the depolymerized polyester is dissolved into a monomer and a reaction solvent, A control method for a monomer production system having: A step of detecting a parameter related to the concentration of the monomer contained in the reaction solvent in which the depolymerized polyester is dissolved, A step of controlling the introduction amount of the polyester raw material into the dissolution unit based on the parameter, Including, Control method.

9. A dissolution unit into which a polyester raw material containing polyester is introduced and a polyester solution in which the polyester is dissolved is stored, A reaction unit into which the polyester solution and a reaction solvent that reacts with the polyester are introduced to depolymerize the polyester in the polyester solution and generate a reaction solvent in which the depolymerized polyester is dissolved, A separation unit that separates the reaction solvent in which the depolymerized polyester is dissolved into a monomer and a reaction solvent, A program for causing a computer to execute a control method for a monomer production system having: A step of detecting a parameter related to the concentration of the monomer contained in the reaction solvent in which the depolymerized polyester is dissolved, A step of controlling the introduction amount of the polyester raw material into the dissolution unit based on the parameter, To be executed by a computer, Program.

Images