Reactor, and monomer manufacturing system

Abstract

To suppress reduction of yield of monomers.SOLUTION: Polyester and reaction solvent which reacts with polyester are introduced into a reactor to depolymerize polyester, and the reactor has reaction part including: a circulation part having a plurality of first flow channels which extends from an introduction port into which reaction solvent, from which first depolymerized polyester being depolymerized polyester is extracted, is introduced, and to a lead-out port from which reaction solvent, from which second depolymerized polyester being further depolymerized first depolymerized polyester is extracted, is lead-out; and a resistor which is provided at a position of covering the outlet port of the circulation part, and in which a second flow channel allowing reaction solvent to circulate in the first flow channel is formed, where the resistor has higher pressure loss than the circulation part.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a reactor and a monomer production system.

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 reaction vessel having a first reaction section for reacting a polyester raw material with a reaction solvent, and a second reaction section for further reacting the low-molecular-weight polyester obtained in the first reaction section with the reaction solvent from which the monomer has been extracted to monomerize it. In Patent Document 1, it is described that by providing rectifying means for rectifying the reaction solvent in the second reaction section, the uneven flow of the reaction solvent can be suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the second reaction section, due to the uneven temperature distribution of the reaction solvent, convection may occur, and the residence time of the reaction solvent may be shortened, which may reduce the monomer yield.

[0005] An object of the present disclosure is to provide a reactor and a monomer production system capable of suppressing a decrease in monomer yield.

Means for Solving the Problems

[0006] The reactor according to the present disclosure is a reactor into which a polyester and a reaction solvent that reacts with the polyester are introduced to depolymerize the polyester, and from an inlet into which the reaction solvent from which a first depolymerized polyester, which is the depolymerized polyester, has been extracted is introduced, to an outlet from which the reaction solvent from which a second depolymerized polyester, which is the further depolymerized first depolymerized polyester, has been extracted is led out, a circulation section having a plurality of first flow paths; and a resistor provided at a position closing the outlet of the circulation section, the resistor forming a second flow path through which the reaction solvent flowing through the first flow path circulates, and having a reaction section including the resistor, the resistor having a higher pressure loss than the circulation section.

[0007] The monomer production system according to the present disclosure includes the reactor and a separation section connected to the reactor for separating the reaction solvent in which the second depolymerized polyester is dissolved into the reaction solvent, a monomer derived from a carboxylic acid contained in the second depolymerized polyester, and a monomer of an alcohol component contained in the second depolymerized polyester.

Advantages of the Invention

[0008] According to the present disclosure, a decrease in the yield of the monomer can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present disclosure will be described in detail. Note that the present disclosure is not limited by this embodiment, and when there are multiple embodiments, those configured by combining each embodiment are also included.

[0011] (Recycling process) Figure 1 is a schematic diagram of the polyester recycling process in this embodiment. In this embodiment, a process of recycling (reproducing) the polyester raw material Pm is performed by depolymerizing the polyester raw material Pm into monomers and then repolymerizing the monomers. Specifically, as shown in Figure 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 generate a polyester solution (step S101), foreign substances are removed from the polyester solution (step S102), the polyester solution from which foreign substances have been removed is mixed with the reaction solvent M and depolymerized (step S103), the monomers of the depolymerized polyester are purified (separated) to generate 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), and the polyester raw material Pm is reproduced. Note that the recycling process adopting the monomer production system 1 of this embodiment may omit the flaking in step S100, or may only perform the process of recovering the monomers D, E shown in step S102, step S104, and the monomer F shown in step S106 without performing the repolymerization process as in step S108.

[0012] (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 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.

[0013] (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.

[0014] (Monomer derived from carboxylic acid) The monomer D derived from carboxylic acid is a monomer having a carboxyl group, which is produced by the depolymerization reaction of polyester. The monomer D may be, for example, dimethyl carboxylate or diethyl carboxylate. Furthermore, the monomer D is preferably a monomer of terephthalic acid, and may be, for example, dimethyl terephthalate (DMT).

[0015] (Monomer of alcohol component) The monomer E of the alcohol component is a monomer of the alcohol component, which is produced by the depolymerization reaction of polyester. The monomer E may be, for example, a dihydroxy compound (dihydric alcohol), and furthermore, may be ethylene glycol (EG).

[0016] 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.

[0017] (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 generate 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 reactor 16, a separation unit 18, and a control unit 19.

[0018] (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.

[0019] (Dissolution unit) The dissolution section 12 is a tank 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 the polyester contained in the polyester raw material Pm is dissolved in the monomer D within the dissolution section 12, thereby generating 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 to the reactor 16. Furthermore, the residue R described later is also supplied to the dissolution section 12, and within 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, thereby generating the polyester solution P. That is to say, 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 the entire amount 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.

[0020] Note that the polyester solution P is not limited to being 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 the polyester contained in the polyester raw material Pm is dissolved in the monomer E within the dissolution section 12, thereby generating the polyester solution P.

[0021] The dissolution section 12 is connected to a first reaction section 16A, which will be described later, via an introduction pipe 12a. The polyester solution P in the dissolution section 12 is supplied to the first reaction section 16A through the introduction pipe 12a. Further, a supply section 12b and a heating section 12c are provided in the introduction pipe 12a. The supply section 12b is a mechanism for supplying the polyester solution P in the dissolution section 12 to the first reaction section 16A, and is a pump in this embodiment. The heating section 12c is a mechanism for heating the polyester solution P.

[0022] (Solvent storage section) The solvent storage section 14 is a tank into which a reaction solvent M is introduced and stored. The solvent storage section 14 is connected to the reactor 16 via an introduction pipe 14a. The reaction solvent M in the solvent storage section 14 is supplied to the reactor 16 through the introduction pipe 14a. More specifically, a heating and pressure increasing section 14b for pressurizing and heating the reaction solvent M is provided in the introduction pipe 14a. The heating and pressure increasing section 14b makes the reaction solvent M into a supercritical state or a subcritical state (pressurized gas or pressurized liquid) by pressurizing and heating the reaction solvent M. The reactor 16 is supplied with the reaction solvent M in a supercritical state or a subcritical state (pressurized gas or pressurized liquid).

[0023] (Reactor) The reactor 16 is a mechanism for introducing a polyester and a reaction solvent M that reacts with the polyester and depolymerizing the polyester. Specifically, the reactor 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 reactor 16 includes a first reaction section 16A as a pre-reaction section and a second reaction section 16B as a reaction section. Hereinafter, in the reactor 16, the direction from the first reaction section 16A to the second reaction section 16B is defined as direction Y1, and the direction opposite to direction Y1 (the direction from the second reaction section 16B to the first reaction section 16A) is defined as direction Y2. In this embodiment, direction Y2 is the gravitational direction (vertically downward).

[0024] (First reaction section) The first reaction section 16A is formed within the reactor 16. In the present embodiment, the first reaction section 16A can be said to be the portion filled with the packing material within the reactor 16. As the packing agent for the first reaction section 16A, known ones used in gas-liquid or liquid-liquid contact devices can be used. For example, the same packing material as that used in a contact device for contacting heavy oil and water to extract the active ingredient can be used. Specific examples of the packing material include pipes made of SUS or the like, Raschig rings, Berl saddles, teralettes, and the like.

[0025] 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 the present embodiment, the inlet 16C that opens 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 that opens facing the Y2 side may be connected on the Y1 side of the surface 16A1 of the first reaction section 16A within the reactor 16.

[0026] An introduction pipe 14a is connected to the reactor 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 reactor 16. The inlet 16D is connected on the Y2 side of the surface 16A2 on the Y2 side of the first reaction section 16A. The introduction pipe 14a is connected on the Y2 side of the surface 16A2 such that the inlet 16D opens facing the Y1 side or from the side surface toward the center side. Thus, in the present embodiment, the inlet 16D that opens facing the Y1 side or from the side surface toward the center side is connected on 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.

[0027] Thus, in this embodiment, the inlet 16C into which the polyester solution P is introduced opens facing the direction Y2, and the inlet 16D into which the reaction solvent M is introduced faces the direction Y1 or opens facing the center from the side surface. Therefore, in the first reaction section 16A, the polyester solution P and the reaction solvent M are introduced in directions facing each other.

[0028] The polyester solution P introduced from the inlet 16C into the first reaction section 16A moves on the surface of the filler in the first reaction section 16A in the direction 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 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.

[0029] Note that the first depolymerized polyester P1 includes monomers D and E generated by depolymerizing the polyester in the polyester solution P, monomer D originally mixed in the polyester solution P, and oligomers generated by depolymerizing the polyester. Here, the oligomers refer to oligomers of carboxylic acids or alcohols that have not been monomerized but have been depolymerized from the polyester (oligomers of carboxylic acids or alcohols with a molecular weight smaller than that of the polyester). Also, the oligomers contained in the residual substance R in the polyester solution P are also 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 and depolymerized from the residual substance R, and monomers D, E, etc. generated by depolymerizing the oligomers contained in the residual substance R.

[0030] (Second reaction section) The second reaction section 16B is provided in the reactor 16 and is provided at the 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.

[0031] 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 (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.

[0032] The second depolymerized polyester P2 contains monomers D and E generated by depolymerizing the oligomers in the first depolymerized polyester P1, and oligomers generated by depolymerizing the first depolymerized polyester P1.

[0033] Details of the structure of the second reaction section 16B will be described later.

[0034] A discharge pipe 16b is connected to the bottom of the reactor 16 (the bottom surface on the Y2 side). More specifically, a discharge port 16F, which is an opening through which non-extracted substances in the reactor 16 are discharged, of the discharge pipe 16b is connected to the bottom of the reactor 16. From the discharge pipe 16b, non-extracted substances are discharged, including impurities such as metal compounds that were not extracted into the reaction solvent M and residues of undepolymerized polyester that were not extracted into the reaction solvent M. That is, the non-extracted substances at the bottom of the reactor 16 are discharged from the discharge port 16F through the discharge pipe 16b to the outside of the reactor 16. The non-extracted substances discharged from the discharge pipe 16b can be said to be the 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 M containing the second depolymerized polyester P2) in the polyester solution P.

[0035] Further, the reactor 16 may be provided with a heating section for heating the inside of the reactor 16 and a pressurizing section for maintaining the pressure inside the reactor 16 at a predetermined value or more. The temperature inside the reactor 16 is preferably set to 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 reactor 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 19.

[0036] (Separation section) The separation unit 18 has the second solvent M2 containing the second depolymerized polyester P2 introduced therein, and separates the second solvent M2 into the reaction solvent M, the monomer D derived from the carboxylic acid contained in the second depolymerized polyester P2, the monomer E of the alcohol component contained in the second depolymerized polyester P2, and the 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 unit 18 includes a first separation unit 18A, a second separation unit 18B, and a third separation unit 18C.

[0038] The first separation unit 18A is a separation column 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 to a predetermined temperature, and the component that has become a gas may be defined as the low-boiling component, and the liquid component may be defined 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 column 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. Note that 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.

[0040] The third separation unit 18C is a separation column connected to the first separation unit 18A via a 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 further high-boiling residue R, low-boiling components containing the reaction solvent M and the monomer E, and the monomer D. Lead-out pipes 18Ca, 18Cb, and 18Cc are connected to the third separation unit 18C. The lead-out pipe 18Ca is connected to the second separation unit 18B. The low-boiling components separated within the third separation unit 18C are 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.

[0041] An introduction pipe 18Cd is connected to the third separation unit 18C. 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 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 the present 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. Further, 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.

[0042] A introducing pipe 18Cf is connected to the third separation unit 18C. The introducing pipe 18Cf is also connected to the dissolving unit 12, and introduces the residual substance R derived from the third separation unit 18C into the dissolving unit 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 unit 18Cg for adjusting the amount of the residual substance R supplied from the third separation unit 18C to the dissolving unit 12. The adjusting unit 18Cg is, for example, an on-off valve. In the open state, the residual substance R is supplied to the dissolving unit 12, and in the closed state, the supply of the residual substance R to the dissolving unit 12 is stopped. However, the adjusting unit 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 unit 12. In the present embodiment, the adjusting unit 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 unit 18C.

[0043] Note that, for example, a storage unit (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 unit. Further, a filter for collecting foreign matters in the residual substance R while allowing oligomers in the residual substance R to pass therethrough may be provided in the introducing pipe 18Cf.

[0044] In the example of FIG. 2, the introducing pipe 10a, the introducing pipe 18Cd, and the introducing pipe 18Cf connected to the dissolving unit 12 are not connected to each other and are directly connected to the dissolving unit 12. 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 unit 12.

[0045] In this embodiment, since the polyester solution P is a solution in which the polyester is dissolved in monomer D, monomer D is introduced into the dissolution section 12 through the introduction pipe 18Cd. However, when the polyester solution P is a solution in which the polyester is dissolved in monomer E, the introduction pipe 18Cd may be connected to the second separation section 18B and the dissolution section 12. That is, in this case, monomer E separated in the second separation section 18B is introduced into the dissolution section 12 through the introduction pipe 18Cd. A storage section (tank) for storing monomer E may be provided, and the introduction pipe 18Cd may be connected to the storage section.

[0046] (Control Unit) The control unit 19 is a control device that controls the monomer production system 1. The control unit 19 controls the adjustment unit 10b to control the amount of the polyester raw material Pm supplied from the raw material storage section 10 to the dissolution section 12. The control unit 19 controls the supply unit 12b to control the amount of the polyester solution P supplied from the dissolution section 12 to the first reaction section 16A. The control unit 19 controls the heating section 12c to control the degree of heating of the polyester solution P. The control unit 19 controls the heating and pressurizing section 14b to bring the reaction solvent M into a supercritical state or a subcritical state (pressurized gas or pressurized liquid), and controls the supply amount of the reaction solvent M in the supercritical state or the subcritical state (pressurized gas or pressurized liquid) to the reactor 16. The control unit 19 controls the adjustment unit 18Ce to control the supply amount of monomer D to the dissolution section 12. The control unit 19 controls the adjustment unit 18Cg to control the supply amount of the residual substance R to the dissolution section 12.

[0047] In this embodiment, the control unit 19 is a computer and includes a processor including an arithmetic circuit such as a CPU (Central Processing Unit), and a storage section that stores various information such as the calculation content and programs by the processor. The control unit 19 executes the control of the monomer production system 1 by reading a program from the storage section.

[0048] However, the monomer production system 1 is not limited to being automatically controlled by the control unit 19, and for example, at least some of the processes may be controlled by the operation of an operator.

[0049] (Operation of monomer production system) Next, the operation of the monomer production system 1 will be described. The control unit 19 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 19 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.

[0050] (Configuration of second reaction unit) Next, the configuration of the second reaction unit 16B will be described. FIG. 3 is a schematic diagram of the second reaction unit. As shown in FIG. 3, the second reaction unit 16B has a flow-through section 20 and a resistor 30.

[0051] (Flow-through section) The flow-through part 20 is a member having a plurality of first flow paths 22 extending from the inlet 22a to the outlet 22b. The inlet 22a is an opening on the Y2-direction side of the first flow path 22, and the outlet 22b is an opening on the Y1-direction side of the first flow path 22. The first flow path 22 is a flow path that communicates the inlet 22a and the outlet 22b. In the present embodiment, it extends along the Y1 direction from the inlet 22a to the outlet 22b. That is, the flow-through part 20 extends along the Y1 direction. Each of the first flow paths 22 is provided side by side in a direction orthogonal to the Y1 direction (Y2 direction). That is, it can be said that the inlet 20a, which is the opening on the Y1-direction side of the flow-through part 20, is constituted by the inlets 22a of the respective first flow paths 22, and the outlet 20b, which is the opening on the Y2-direction side of the flow-through part 20, is constituted by the outlets 22b of the respective first flow paths 22. Note that the number and size of the first flow paths 22 may be arbitrary.

[0052] FIG. 4 is a schematic top view of the flow-through part. As shown in FIG. 4, in the present embodiment, the flow-through part 20 has an outer tube 24 and a plurality of inner tubes 26. The outer tube 24 is a tubular member extending in the Y1 direction. In the present embodiment, the side wall of the reactor 16 constitutes the outer tube 24, but the outer tube 24 may be provided inside the side wall of the reactor 16. Further, the inner tube 26 is provided inside the outer tube 24 and is a tubular member extending in the Y1 direction. Each of the inner tubes 26 is provided side by side in a direction orthogonal to the Y1 direction (Y2 direction). In the present embodiment, the space inside each of the inner tubes 26 and the space surrounded by the inner wall of the outer tube 24 and the outer walls of the inner tubes 26 form the first flow path 22. Note that the number and arrangement of the inner tubes 26 are not limited to the example of FIG. 4 and may be arbitrary.

[0053] The first solvent M1 containing the first depolymerized polyester P1 derived from the first reaction section 16A is introduced into each first flow path 22 from the inlet 20a of the flow-through section 20 (the inlet 22a of each first flow path 22). While the first solvent M1 introduced into the first flow path 22 flows toward the outlet 20b of the flow-through section 20 (the outlet 22b of each first flow path 22), the first depolymerized polyester P1 contained in the first solvent M1 is further depolymerized by the reaction solvent M, and is derived as a second solvent M2 containing a second depolymerized polyester P2 from the outlet 20b (the outlet 22b of each first flow path 22).

[0054] (Resistor) The resistor 30 allows the second solvent M2 flowing through the flow-through section 20 (the first flow path 22) to pass through, and is a member having a higher pressure loss than the flow-through section 20. Having a high pressure loss means that when a fluid of the same flow rate is passed, the pressure loss of the fluid becomes higher than that of the comparison target. That is, it can be said that the pressure loss of the fluid when the fluid is introduced from the end face 30a of the resistor 30 and the fluid is derived from the end face 30b is higher than the pressure loss when the same amount of fluid is introduced from the inlet 20a of the flow-through section 20 and the fluid is derived from the outlet 20b. Note that it is preferable that the resistor 30 has a higher pressure loss than the first reaction section 16A.

[0055] The resistor 30 is provided at a position that closes the outlet 20b of the flow-through section 20. The position that closes the outlet 20b refers to a position between the inlet 20a and the outlet 20b in the flow-through section 20, or a position that covers the outlet 20b that opens to the Y1 side. The resistor 30 may be provided at any position that closes the outlet 20b of the flow-through section 20, but in the present embodiment, it is provided at a position facing the outlet 20b of the flow-through section 20 (a position that covers the outlet 20b). That is, the resistor 30 is placed on the end face of the flow-through section 20 in the Y1 direction (in this example, the end portions of the inner tube 26 and the outer tube 24 in the Y1 direction) and contacts the end face of the flow-through section 20 in the Y1 direction. However, it is not limited thereto, and the resistor 30 may be provided inside the first flow path 22 of the flow-through section 20.

[0056] Further, it is preferable that the resistor 30 closes the outlets 22b of all the first flow paths 22 in the flow-through portion 20. That is, it is preferable that the resistor 30 is provided so as to close the entire area of the outlet 20b of the flow-through portion 20 (the entire area of the outlets 22b of all the first flow paths 22).

[0057] A second flow path 32 through which a second solvent M2 flowing through the first flow path 22 flows is formed in the resistor 30. That is, by forming the second flow path 32 in the resistor 30, while the second solvent M2 flows, the pressure loss of the second solvent M2 is increased. The second flow path 32 is a flow path that communicates the end face 30a on the Y2 direction side of the resistor 30 and the end face 30b on the Y1 direction side of the resistor 30. A plurality of second flow paths 32 are provided in the resistor 30.

[0058] The second flow path 32 may have any shape that increases the pressure loss of the second solvent M2 to be higher than that of the flow-through portion 20 while communicating the end face 30a and the end face 30b. For example, it is preferable that the second flow path 32 extends so as not to be along the Y1 direction from the opening on the end face 30b side to the opening on the end face 30a side. For example, assuming that the length in the Y1 direction from the end face 30b to the end face 30a is the length L, the flow path length of the second flow path 32 from the opening on the end face 30b side to the opening on the end face 30a side is preferably longer than the length of the first flow path 22 in the section of the length L in the Y1 direction. Thereby, the pressure loss of the resistor 30 can be appropriately increased.

[0059] Note that the resistor 30 may be any structure in which the second flow path 32 is formed. For example, it may be a porous body, a mesh structure, etc., and a sintered filter is preferably used.

[0060] The pressure loss of the resistor 30 is preferably 50 Pa or more, more preferably 75 Pa or more and 125 Pa or less. Further, the ratio of the pressure loss of the resistor 30 to the pressure loss of the flow passage portion 20 is preferably 110% or more, more preferably 200% or more. By setting the pressure loss of the resistor 30 within this range, the acceleration of the flow of the first solvent M1 and the second solvent M2 can be appropriately suppressed, and the decrease in the monomer yield can be appropriately suppressed. The pressure loss of the resistor 30 can be measured by measuring the difference between the pressure of the fluid at the end face 30a (the inlet of the second flow path 32) and the pressure of the fluid at the end face 30b (the outlet of the second flow path 32) when air in the standard state as a fluid is introduced into the resistor 30 from the end face 30a at a linear velocity of 2.3 mm / sec.

[0061] The ratio of the length of the resistor 30 in the Y1 direction (the length in the Y1 direction from the end face 30a to the end face 30b) to the length of the flow passage portion 20 in the Y1 direction (the length in the Y1 direction from the inlet 20a to the outlet 20b) is preferably 0.0005% or more, more preferably 0.005% or more. Further, the ratio of the length of the second reaction portion 16B in the Y1 direction to the length of the first reaction portion 16A in the Y1 direction is preferably 50% or more and 200% or less, more preferably 100% or more and 150% or less. By setting the lengths (heights) of the resistor 30 and the second reaction portion 16B in the Y1 direction within this range, depolymerization can be appropriately performed, and the decrease in the monomer yield can be appropriately suppressed.

[0062] (Effect) The reactor 16 according to the first aspect of the present disclosure is for depolymerizing a polyester by introducing the polyester and a reaction solvent M that reacts with the polyester, and has a reaction section (second reaction section 16B) including a flow-through section 20 and a resistor 30. The flow-through section 20 extends from an inlet 20a into which a reaction solvent (first solvent M1) from which a first depolymerized polyester P1, which is a depolymerized polyester, is extracted is introduced, to an outlet 20b from which a reaction solvent (second solvent M2) from which a second depolymerized polyester P2, which is the first depolymerized polyester P1 further depolymerized, is extracted, and has a plurality of first flow paths 22. The resistor 30 is provided at a position closing the outlet 20b of the flow-through section 20, and a second flow path 32 through which the reaction solvent (second solvent M2) flowing through the first flow path 22 flows is formed. The resistor 30 has a higher pressure loss than the flow-through section 20.

[0063] The reactor 16 of the present disclosure has a structure in which the second reaction section 16B has a flow-through section 20 in which a plurality of first flow paths 22 are formed, so that the first solvent M1 flowing through the second reaction section 16B can be rectified and the polyester can be appropriately depolymerized, and thus a decrease in the monomer yield can be suppressed. Furthermore, as a result of intensive research, the present inventor has found that due to the occurrence of convection of the first solvent M1 in the flow-through section 20, the flow of the first solvent M1 is locally accelerated and the residence time of a part of the first solvent M1 becomes short. When the residence time of the first solvent M1 becomes short, sufficient time for depolymerization cannot be ensured, and the monomer yield decreases. On the other hand, in the present disclosure, by providing the resistor 30 at a position closing the outlet 20b of the flow-through section 20, acceleration of the first solvent M1 can be suppressed and a decrease in the residence time can be suppressed. Therefore, according to the present disclosure, a decrease in the monomer yield can be appropriately suppressed.

[0064] The reactor 16 according to the second aspect of the present disclosure is the reactor 16 according to the first aspect, and it is preferable that the resistor 30 closes the outlets 22b of all the first flow paths 22 in the flow-through portion 20. Here, the position where the convection of the first solvent M1 occurs and is accelerated in the flow-through portion 20 may vary depending on the external environment or the like. On the other hand, by providing the resistor 30 at a position that closes the outlets 22b of all the first flow paths 22, even when the position where the first solvent M1 is accelerated varies, the acceleration can be appropriately suppressed, and a decrease in the monomer yield can be appropriately suppressed.

[0065] The reactor 16 according to the third aspect of the present disclosure is the reactor 16 according to the first aspect or the second aspect, and it is preferable that the resistor 30 is provided at a position facing the outlet 20b of the flow-through portion 20. By providing the resistor 30 at such a position, it is not necessary to insert the resistor 30 inside the first flow path 22, and the structure and assembly work of the resistor 30 can be simplified. Further, by not inserting the resistor 30 inside the first flow path 22, appropriate rectification can be achieved, and a decrease in the monomer yield can be suppressed.

[0066] The reactor 16 according to the fourth aspect of the present disclosure is the reactor 16 according to any one of the first aspect to the third aspect, and preferably further has a pre-reaction portion (first reaction portion 16A). In the first reaction portion 16A, a polyester solution P in which polyester is dissolved and a reaction solvent M are introduced, the polyester solution P and the reaction solvent M are brought into contact with each other to depolymerize the polyester in the polyester solution P, and the first depolymerized polyester P1 containing the depolymerized polyester is extracted into the reaction solvent M. Thereby, the polyester can be appropriately depolymerized, and a decrease in the monomer yield can be suppressed.

[0067] The reactor 16 according to the fifth aspect of the present disclosure is the reactor 16 according to the fourth aspect, and it is preferable that the resistor 30 has a higher pressure loss than the first reaction portion 16A. Thereby, a decrease in the monomer yield can be appropriately suppressed.

[0068] The reactor 16 according to the sixth aspect of the present disclosure is the reactor 16 according to any one of the first to fifth aspects, wherein the polyester is preferably polyethylene terephthalate and the reaction solvent M is preferably methanol. According to the present disclosure, PET can be appropriately monomerized.

[0069] The monomer production system 1 according to the seventh aspect of the present disclosure includes a reactor 16 according to any one of the first to sixth aspects, and a reaction solvent (second solvent M2) in which the second depolymerized polyester P2 is dissolved, which is connected to the reactor 16, and is separated into the reaction solvent M, the monomer D derived from the carboxylic acid contained in the second depolymerized polyester, and the monomer C of the alcohol component contained in the second depolymerized polyester. And a separation unit 18. According to the present disclosure, a decrease in the monomer yield can be appropriately suppressed.

[0070] As described above, the embodiments of the present disclosure have been described, but the embodiments are not limited by the contents of these embodiments. In addition, the above-described components include those that can be easily assumed by those skilled in the art, those that are substantially the same, 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

[0071] 10 Storage unit 12 Dissolution unit 14 Solvent storage unit 16 Reactor 16A First reaction unit (pre-reaction unit) 16B Second reaction unit (reaction unit) 18 Separation unit D, E Monomer M Reaction solvent M1 First solvent M2 Second solvent P Polyester solution Pm Polyester raw material P1 First depolymerized polyester P2 Second depolymerized polyester

Claims

1. A reactor into which a polyester and a reaction solvent that reacts with the polyester are introduced to depolymerize the polyester, a flow-through section having a plurality of first flow paths extending from an inlet through which the reaction solvent from which a first depolymerized polyester, which is the depolymerized polyester, has been extracted is introduced to an outlet through which the reaction solvent from which a second depolymerized polyester, which is the further depolymerized first depolymerized polyester, has been extracted is led out; a resistor provided at a position closing the outlet of the flow-through section, the resistor forming a second flow path through which the reaction solvent flowing through the first flow path flows; The reactor has a reaction section including these components. The resistor has a higher pressure loss than the flow-through section. Reactor.

2. The resistor closes the outlets of all the first flow paths of the flow-through section. The reactor according to Claim 1.

3. The resistor is provided at a position facing the outlet of the flow-through section. The reactor according to Claim 1 or Claim 2.

4. The reactor further has a pre-reaction section into which a polyester solution in which the polyester is dissolved and the reaction solvent are introduced, the polyester solution and the reaction solvent are brought into contact with each other to depolymerize the polyester in the polyester solution, and the first depolymerized polyester containing the depolymerized polyester is extracted into the reaction solvent. The reactor according to Claim 1 or Claim 2.

5. The resistor has a higher pressure loss than the pre-reaction section. The reactor according to Claim 4.

6. The polyester is polyethylene terephthalate and the reaction solvent is methanol. The reactor according to Claim 1 or Claim 2.

7. The reactor according to Claim 1 or Claim 2, and a separation section connected to the reactor to separate the reaction solvent in which the second depolymerized polyester is dissolved into the reaction solvent, a monomer derived from a carboxylic acid contained in the second depolymerized polyester, and a monomer of an alcohol component contained in the second depolymerized polyester. Monomer production system.

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