Device and method for recycling polyester glycol alcoholysis solution

Abstract

The invention relates to the technical field of cyclic utilization of a polyester glycol alcoholysis solution, and discloses a device and a method for cyclic utilization of a polyester glycol alcoholysis solution, the device comprises a raw material tank V1, a preheater E1, a membrane separator X1, an intermediate tank V3, a dehydrating tower T1 and an ethylene glycol recovery tank V4 which are connected in sequence; and the recovery water tank V2 is connected with the bottom of the membrane separator X1. According to the method, ethylene glycol and water can be effectively recycled, and consumption of ethylene glycol and water can be reduced.

Description

Technical Field

[0001] This invention relates to the technical field of recycling polyester glycol alcoholysis solution, specifically to an apparatus and method for recycling polyester glycol alcoholysis solution. Background Technology

[0002] PET (Polyester Petroleum) is the world's most widely used polyester material. Its excellent physical and chemical properties lead to its widespread use in single-purpose or multi-purpose products such as food and beverage containers, resulting in significant environmental pressure and a large amount of waste PET urgently needing recycling. Among the chemical degradation methods for PET, alcoholysis is a more mature process compared to other chemical recycling methods. Through years of continuous theoretical analysis and practice, the alcoholysis process has been gradually improved, and several companies now have industrial-scale facilities. Industrially, alcoholysis is mainly divided into methanol alcoholysis and ethylene glycol alcoholysis. Methanol alcoholysis refers to the breaking of ester bonds in PET in a methanol reaction atmosphere, producing dimethyl terephthalate (DMT). DMT can be used as a monomer for the repolymerization of PET and PBT.

[0003] The ethylene glycol alcoholysis process has a simple reaction route, is not demanding in terms of temperature and pressure, and is relatively easy to design and implement. It also offers a higher safety factor, making it suitable for industrial-scale production and maximizing economic benefits. Furthermore, the ethylene glycol alcoholysis route does not contain corrosive substances, reducing pollution emissions and lowering equipment maintenance costs. From a practical perspective, the monomer ethylene glycol terephthalate (BHET) produced by this route can be directly fed into the polymerization process and integrated into conventional PET production facilities without pretreatment or the generation of other byproducts.

[0004] To address the issues of low depolymerization efficiency and incomplete depolymerization in existing chemical recycling processes for waste PET, a novel green and efficient depolymerization technology has been developed. However, the recrystallization process consumes a large amount of ethylene glycol and water, making it urgent to develop a technology for recycling ethylene glycol hydrolysate to achieve circular utilization. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low depolymerization efficiency and incomplete depolymerization in existing chemical recycling processes for waste PET, as well as the large amount of ethylene glycol and water consumed in the recrystallization process of depolymerization technology. This invention provides an apparatus and method for recycling polyester ethylene glycol alcoholysis solution. This method can effectively recover and recycle ethylene glycol and water, and can reduce the consumption of ethylene glycol and water.

[0006] To achieve the above objectives, the first aspect of the present invention provides an apparatus for recycling polyester glycol alcoholysis solution, wherein the apparatus comprises: a raw material tank V1, a preheater E1, a membrane separator X1, an intermediate tank V3, a dehydration tower T1, and a recovery glycol tank V4 connected in sequence; and a recovery water tank V2 connected to the bottom of the membrane separator X1.

[0007] A second aspect of the present invention provides a method for recycling polyester glycol alcoholysis solution using the aforementioned apparatus, wherein the method comprises:

[0008] (1) The polyester glycol alcoholysis solution S1 in the raw material tank V1 is preheated by the preheater E1 after passing through the feed pump P1 and the alcoholysis solution S2. The preheated alcoholysis solution S3 is then introduced into the membrane separator X1 for membrane separation.

[0009] (2) The permeate S4 after membrane separation is cooled by the first cooler E2 and then the permeate S5 enters the intermediate tank V3. The permeate S6 after passing through the transfer pump P3 is introduced into the dehydration tower T1 for dehydration treatment, and the recovered ethylene glycol S7 after the dehydration treatment is recycled into the ethylene glycol recovery tank V4.

[0010] (3) The recycled water S9 after membrane separation is cooled by the second cooler E3 and then recycled water S10 enters the recycled water tank V2 for recycling.

[0011] Through the above technical solution, the method of the present invention can effectively recycle ethylene glycol and water. The treated ethylene glycol and water meet the reuse requirements while realizing the recycling of raw materials and significantly reducing wastewater discharge. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the recycling of polyester glycol alcoholysis solution according to the present invention.

[0013] Explanation of reference numerals in the attached figures

[0014] V1 Raw material tank; P1 Feed pump; E1 Preheater; X1 Membrane separator; E2 First cooler; V3 Intermediate tank; E3 Second cooler; V2 Recycled water tank; P2 Recycled water pump; C1 Vacuum device; P3 Transfer pump; T1 Dehydration tower; V4 Recycled ethylene glycol tank; P4 Recycled ethylene glycol pump;

[0015] S1, S2, and S3 polyester glycol alcoholysis solutions;

[0016] S4, S5, and S6 permeate;

[0017] S7 and S8 recover ethylene glycol;

[0018] S9, S10, and S11 are recycled water. Detailed Implementation

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] As mentioned above, in order to achieve the above objectives, the first aspect of the present invention provides an apparatus for recycling polyester glycol alcoholysis liquid, wherein the apparatus comprises: a raw material tank V1, a preheater E1, a membrane separator X1, an intermediate tank V3, a dehydration tower T1 and a recovery glycol tank V4 connected in sequence; and a recovery water tank V2 connected to the bottom of the membrane separator X1.

[0021] The inventors of this invention have discovered that by using membrane separator X1 and dehydration tower T1 together, ethylene glycol and water can be effectively recycled and reused, and the consumption of ethylene glycol and water can be reduced. The recycled ethylene glycol and water can meet the requirements for reuse.

[0022] According to the present invention, in a preferred embodiment, the apparatus comprises: a raw material tank V1, a feed pump P1, a preheater E1, a membrane separator X1, a first cooler E2, an intermediate tank V3, a transfer pump P3, a dehydration tower T1, and a recovered ethylene glycol tank V4, which are connected in sequence; and a second cooler E3 and a recovered water tank V2, which are connected in sequence to the bottom of the membrane separator X1.

[0023] According to the present invention, in a preferred embodiment, the preheater E1 is connected to the lower inlet of the membrane separator X1, and the upper part of the membrane separator X1 is connected to the upper part of the intermediate tank V3 through the first cooler E2.

[0024] According to the present invention, the membrane separator is filled with a membrane. The inlet and outlet of the membrane separator are determined by the length of the membrane. Generally, the inlet and outlet are located at the upper and lower parts, or the top and bottom of the membrane separator. In the present invention, there is no special definition for the upper and lower parts, which is known to those skilled in the art.

[0025] According to the present invention, in a preferred embodiment, the lower part of the membrane separator X1 is 5 / 8 to 7 / 8 of the membrane separator X1;

[0026] According to the present invention, in a preferred embodiment, the upper part of the membrane separator X1 is 1 / 8 to 3 / 8 of the membrane separator X1.

[0027] According to the present invention, in a preferred embodiment, the upper part of the intermediate tank V3 is 1 / 8 to 3 / 8 of the size of the intermediate tank V3.

[0028] According to the present invention, the bottom pipeline of the intermediate tank V3 is connected to the preheater E1 via the transfer pump P3, and is also connected to the bottom of the dehydration tower T1; the top of the dehydration tower T1 is connected to the top of the ethylene glycol recovery tank V4, and the bottom of the ethylene glycol recovery tank V4 is connected to the ethylene glycol recovery pump P4.

[0029] According to the present invention, the top of the water recovery tank V2 is connected to the vacuum pump C1, and the bottom of the water recovery tank V2 is connected to the water recovery pump P2.

[0030] According to the present invention, the second cooler E3 is connected to the upper part of the recovery water tank V2.

[0031] According to the present invention, the upper part of the water recycling tank V2 is 1 / 8 to 3 / 8 of the length of the water recycling tank V2.

[0032] According to the present invention, the membrane separator X1 contains a selectively permeable membrane and / or a component of selectively permeable membranes; the number of membrane components and the membrane area are determined according to the amount and composition of the ethylene glycol alcoholysis feedstock. Preferably, the selectively permeable membrane is a type A molecular sieve membrane or a pervaporation membrane.

[0033] According to the present invention, in a preferred embodiment, a separation membrane layer (selective permeable membrane and / or a component of selective permeable membrane) is deposited on the outer layer of the ceramic support.

[0034] According to the present invention, the dehydration tower T1 is filled with molecular sieves; preferably, the molecular sieves are 4A molecular sieves and / or 3A molecular sieves.

[0035] A second aspect of the present invention provides a method for recycling polyester glycol alcoholysis solution using the aforementioned apparatus, wherein the method comprises:

[0036] (1) The polyester glycol alcoholysis solution S1 in the raw material tank V1 is preheated by the preheater E1 after passing through the feed pump P1 and the alcoholysis solution S2. The preheated alcoholysis solution S3 is then introduced into the membrane separator X1 for membrane separation.

[0037] (2) The permeate S4 after membrane separation is cooled by the first cooler E2 and then the permeate S5 enters the intermediate tank V3. The permeate S6 after passing through the transfer pump P3 is introduced into the dehydration tower T1 for dehydration treatment, and the recovered ethylene glycol S7 after the dehydration treatment is recycled into the ethylene glycol recovery tank V4.

[0038] (3) The recycled water S9 after membrane separation is cooled by the second cooler E3 and then recycled water S10 enters the recycled water tank V2 for recycling.

[0039] According to the present invention, in step (1), the preheated alcoholysis solution S3 is introduced into the membrane separator X1 from the lower part of the membrane separator X1 for membrane separation;

[0040] According to the present invention, in step (2), the permeate S4 after membrane separation is cooled by the first cooler E2 and then the permeate S5 enters the intermediate tank V3 from the upper part of the intermediate tank V3. Then, the permeate S6 after passing through the transfer pump P3 is introduced into the dehydration tower T1 from the bottom for dehydration treatment.

[0041] According to the present invention, in step (3), the recycled water S9 after membrane separation is cooled by the second cooler E3 and then recycled water S10 enters the recycled water tank V2 from the top of the recycled water tank V2 for recycling.

[0042] According to the present invention, the polyester glycol alcoholysis solution S1 contains ethylene glycol and water; preferably, based on the total weight of the polyester glycol alcoholysis solution S1, the content of ethylene glycol is 20-45% by weight, more preferably 25-35% by weight; and the content of water is 55-80% by weight.

[0043] According to the present invention, the polyester glycol alcoholysis solution S1 further contains one or more of diethylene glycol, ethylene terephthalate (BHET), and dimers, and does not contain salts, sugars, solid particles, strong acidic or alkaline components.

[0044] According to the present invention, the pH value of the polyester glycol alcoholysis solution S1 is 6.0-8.5.

[0045] According to the present invention, the water content in the ethylene glycol in the intermediate tank (V3) is ≤0-1.5%.

[0046] According to the present invention, in step (1), the conditions for membrane separation include: a pressure of 0.5-0.2 MPa (G) and a temperature of 85-100°C.

[0047] According to the present invention, in step (2), the conditions for the dehydration treatment include: a pressure of 0.1-0.4 MPa (G) and a temperature of 20-35°C.

[0048] According to the present invention, after dehydration treatment in the dehydration tower (T1), activation treatment is also performed.

[0049] According to the present invention, the activation treatment conditions include: a pressure of 0.01-0.05 MPa (G) and a temperature of 350-450 °C.

[0050] According to the present invention, no additional components such as catalysts are introduced into the method.

[0051] According to the present invention, the purity of the recovered ethylene glycol S7 is greater than 99%, preferably greater than 99.5%.

[0052] According to a particularly preferred embodiment of the present invention, a method for recycling polyester glycol alcoholysis solution using the aforementioned apparatus includes:

[0053] (1) The polyester glycol alcoholysis solution S1 is fed into the raw material tank V1; the alcoholysis solution S2 after passing through the feed pump P1 is preheated by the preheater E1, and the preheated alcoholysis solution S3 is introduced into the membrane separator X1 for membrane separation; the membrane separator X1 is filled with a selective permeable membrane and membrane module.

[0054] (2) The permeate S4 after membrane separation is cooled by the first cooler E2 and then the permeate S5 enters the intermediate tank V3. The permeate S6 after passing through the transfer pump P3 is introduced into the dehydration tower T1 for dehydration treatment. The recovered ethylene glycol S7 after the dehydration treatment enters the recovered ethylene glycol tank V4. The recovered ethylene glycol S8 after passing through the recovered ethylene glycol pump P4 is recycled.

[0055] The membrane separator X1 operates at a pressure of 0.5-0.2 MPa (G) and a temperature of 85-100℃; the water content of ethylene glycol in the intermediate tank is ≤0-1.5%.

[0056] (3) The recycled water S9 after membrane separation is cooled by the second cooler E3 and then the recycled water S10 enters the recycled water tank V2 for recycling.

[0057] The dehydration tower is filled with molecular sieves, and the operating pressure is atmospheric pressure -0.4 MPa (G), and the operating temperature is room temperature.

[0058] The present invention will be described in detail below through embodiments.

[0059] Example 1

[0060] like Figure 1 As shown, according to Figure 1 The polyester glycol alcoholysis recycling device shown recycles the polyester glycol alcoholysis solution.

[0061] The device includes: V1 raw material tank, P1 feed pump, E1 preheater, X1 membrane separator, E2 first cooler, V3 intermediate tank, E3 second cooler, V2 recovery water tank, P2 recovery water pump, C1 vacuum device, P3 transfer pump, T1 dehydration tower, V4 recovery glycol tank, and P4 recovery glycol pump.

[0062] The feed line is connected to the raw material tank V1, and the bottom of the raw material tank V1 is connected to the feed pump P1; the feed pump P1 is connected to the preheater E1; the preheater E1 is connected to the lower part (6 / 8 of the membrane separator X1) inlet, and the upper part (1 / 8 of the membrane separator X1) is connected to the upper part (1 / 4 of the intermediate tank V3) through the first cooler E2.

[0063] The bottom pipeline of intermediate tank V3 is connected to the bottom of dehydration tower T1 via transfer pump P3. The top of dehydration tower T1 is connected to the top of recovery glycol tank V4, and the bottom of recovery glycol tank V4 is connected to recovery glycol pump P4. The recovered glycol is returned to the depolymerization unit for recycling.

[0064] The bottom of membrane separator X1 is connected to the second cooler E3, which is connected to the upper part of the recovery water tank V2 (1 / 4 of the recovery water tank V2). Recovery water S10 enters the recovery water tank V2. The top of the recovery water tank V2 is connected to the vacuum device C1, and the bottom of the recovery water tank V2 is connected to the recovery water pump P2. The recovery water is returned to the depolymerization unit for recycling.

[0065] The membrane separator contains a selectively permeable membrane and a membrane module (specifically, a type A molecular sieve membrane or a pervaporation membrane).

[0066] The membrane separator operates at a pressure of 0.4 MPa (G).

[0067] Membrane separator operating temperature: 90℃

[0068] The dehydration tower is filled with molecular sieves (specifically 4A molecular sieves);

[0069] The operating pressure of the dehydration tower is 0.2 MPa (G).

[0070] Dehydration tower operating temperature: 25℃ (normal temperature)

[0071] Methods for recycling polyester glycol alcoholysis solution using membrane separation include:

[0072] (1) Polyester glycol depolymerization solution S1 (ethylene glycol content is 25% by weight, water content is 75% by weight) from the depolymerization unit, pressure 0.01 MPa (g), temperature 25℃, mass flow rate 1000 kg / hr enters the raw material tank V1; the bottom of the raw material tank V1 is fed by the feed pump P1, the alcoholysis solution S2 is preheated by the preheater E1, and the alcoholysis solution S3 enters from the bottom of the membrane separator X1;

[0073] (2) The permeate S4 from the upper part of membrane separator X1, after being cooled by 40°C by the first cooler E2, enters intermediate tank V3 from the upper part. The permeate S12 in intermediate tank V3 is returned to preheater E1 via transfer pump P3. After circulating dehydration for a certain period of time, the water content of ethylene glycol in intermediate tank V3 is ≤1%.

[0074] (3) The permeate S6 in the intermediate tank V3 enters the bottom of the dehydration tower TI via the transfer pump P3. The recovered ethylene glycol S7, which is further refined in the dehydration tower, enters the recovery ethylene glycol tank V4 from the top of the dehydration tower T1. The recovered ethylene glycol S7 is pumped by the recovery ethylene glycol pump P4 to obtain recovered ethylene glycol S8, which is returned to the depolymerization unit for recycling.

[0075] (4) The recycled water S9 at the bottom of the membrane separator X1 is cooled to 30°C by the second cooler E3. The cooled recycled water S10 enters the recycled water tank V2 from the top and is then pumped by the recycled water pump P2. The recycled water S11 is then returned to the depolymerization unit for recycling.

[0076] The quality composition of each major logistics item is shown in Table 1.

[0077] Table 1

[0078]

[0079] Example 2

[0080] like Figure 1 As shown, according to Figure 1 The polyester glycol alcoholysis recycling device shown recycles the polyester glycol alcoholysis solution.

[0081] The device includes: V1 raw material tank, P1 feed pump, E1 preheater, X1 membrane separator, E2 first cooler, V3 intermediate tank, E3 second cooler, V2 recovery water tank, P2 recovery water pump, C1 vacuum device, P3 transfer pump, T1 dehydration tower, V4 recovery glycol tank, and P4 recovery glycol pump.

[0082] The feed line is connected to the raw material tank V1, and the bottom of the raw material tank V1 is connected to the feed pump P1; the feed pump P1 is connected to the preheater E1; the preheater E1 is connected to the lower part (7 / 8) inlet of the membrane separator X1, and the upper part (1 / 8) of the membrane separator X1 is connected to the upper part (1 / 4) of the intermediate tank V3 through the first cooler E2.

[0083] The bottom pipeline of intermediate tank V3 is connected to the bottom of dehydration tower T1 via transfer pump P3. The top of dehydration tower T1 is connected to the top of recovery glycol tank V4, and the bottom of recovery glycol tank V4 is connected to recovery glycol pump P4. The recovered glycol is returned to the depolymerization unit for recycling.

[0084] The bottom of membrane separator X1 is connected to the second cooler E3, which is connected to the upper part of the recovery water tank V2 (1 / 4 of the recovery water tank V2). Recovery water S10 enters the recovery water tank V2. The top of the recovery water tank V2 is connected to the vacuum device C1, and the bottom of the recovery water tank V2 is connected to the recovery water pump P2. The recovery water is returned to the depolymerization unit for recycling.

[0085] The membrane separator contains a selectively permeable membrane and a membrane module (specifically, a type A molecular sieve membrane or a pervaporation membrane).

[0086] The membrane separator operates at a pressure of 0.3 MPa (G).

[0087] Membrane separator operating temperature: 95℃

[0088] The dehydration tower is filled with molecular sieves (specifically 4A molecular sieves);

[0089] The operating pressure of the dehydration tower is 0.25 MPa (G).

[0090] Dehydration tower operating temperature: 30℃ (normal temperature);

[0091] Methods for recycling polyester glycol alcoholysis solution using membrane separation include:

[0092] (1) Polyester glycol depolymerization solution S1 (ethylene glycol content is 30% by weight, water content is 70%) from the depolymerization unit, pressure 0.01 MPa (g), temperature 30℃, mass flow rate 1000 kg / hr enters the raw material tank V1; the bottom of the raw material tank V1 is fed by the feed pump P1, the alcoholysis solution S2 is preheated by the preheater E1, and the alcoholysis solution S3 enters from the lower part (3 / 4 of the membrane separator X1);

[0093] (2) The permeate S4 from the upper part (1 / 8 of membrane separator X1) is cooled by 40°C by the first cooler E2, and then the permeate S5 enters the intermediate tank V3 from the upper part (1 / 4 of intermediate tank V3). The permeate S12 in intermediate tank V3 is returned to the preheater E1 via the transfer pump P3. After circulating dehydration for a certain period of time, the water content of ethylene glycol in intermediate tank V3 is ≤1%.

[0094] (3) The permeate S6 in the intermediate tank V3 enters the bottom of the dehydration tower TI via the transfer pump P3. The recovered ethylene glycol S7, which is further refined in the dehydration tower, enters the recovery ethylene glycol tank V4 from the top of the dehydration tower T1. The recovered ethylene glycol S7 is pumped by the recovery ethylene glycol pump P4 to obtain recovered ethylene glycol S8, which is returned to the depolymerization unit for recycling.

[0095] (4) The recycled water S9 at the bottom of the membrane separator X1 is cooled to 30°C by the second cooler E3. The cooled recycled water S10 enters the recycled water tank V2 from the upper part (1 / 4 of the recycled water tank V2). After passing through the recycled water pump P2, the recycled water S11 returns to the depolymerization unit for recycling.

[0096] The quality composition of each major logistics item is shown in Table 2.

[0097] Table 2

[0098]

[0099] Example 3

[0100] like Figure 1 As shown, a membrane separation system for recycling polyester glycol alcoholysis solution is described.

[0101] The system includes: V1 raw material tank, P1 feed pump, E1 preheater, X1 membrane separator, E2 first cooler, V3 intermediate tank, E3 second cooler, V2 recovery water tank, P2 recovery water pump, C1 vacuum device, P3 transfer pump, T1 dehydration tower, V4 recovery glycol tank, and P4 recovery glycol pump.

[0102] The feed line is connected to the raw material tank V1, and the bottom of the raw material tank V1 is connected to the feed pump P1; the feed pump P1 is connected to the preheater E1; the preheater E1 is connected to the bottom inlet of the membrane separator X1, and the top of the membrane separator X1 is connected to the intermediate tank V3 through the first cooler E2.

[0103] The bottom pipeline of intermediate tank V3 is connected to the bottom of dehydration tower T1 via transfer pump P3. The top of dehydration tower T1 is connected to the top of recovery glycol tank V4. The bottom of recovery glycol tank V4 is connected to recovery glycol pump P4. The recovered glycol is returned to the depolymerization unit for recycling.

[0104] The bottom of membrane separator X1 is connected to the second cooler E3, which is connected to the recycled water tank S10. The top of the recycled water tank V2 is connected to the vacuum device C1, and the bottom of the recycled water tank V2 is connected to the recycled water pump P2. The recycled water is returned to the depolymerization unit for recycling.

[0105] The membrane separator contains a selectively permeable membrane and a membrane module.

[0106] The membrane separator operates at a pressure of 0.35 MPa (G).

[0107] Membrane separator operating temperature: 92℃

[0108] The dehydration tower is filled with molecular sieves, specifically 3A molecular sieves;

[0109] The operating pressure of the dehydration tower is 0.2 MPa (G).

[0110] Dehydration tower operating temperature: 35℃

[0111] Methods for recycling polyester glycol alcoholysis solution using membrane separation include:

[0112] (1) Ethylene glycol depolymerization solution S1 (ethylene glycol content 35% by weight, water content 65% by weight), pressure 0.01 MPa (g), temperature 30℃, mass flow rate 2000 kg / hr from the depolymerization unit enters the raw material tank V1. The bottom of the raw material tank V1 is fed by the feed pump P1, the alcoholysis solution S2 is preheated by the preheater E1, and the alcoholysis solution S3 enters from the bottom of the membrane separator X1;

[0113] (2) The permeate S4 from the top of membrane separator X1 is cooled to 40°C by the first cooler E2, and then transferred to intermediate tank V3 as permeate S5. The permeate S6 in intermediate tank V3 is returned to preheater E1 via transfer pump P3. After circulating dehydration for a certain period of time, the water content of ethylene glycol in the intermediate tank is ≤1%.

[0114] (3) The permeate S6 in the intermediate tank V3 enters the bottom of the dehydration tower TI via the transfer pump P3. The recovered ethylene glycol S7, which is further refined in the dehydration tower, enters the ethylene glycol recovery tank V4. The recovered ethylene glycol is pumped through the ethylene glycol recovery pump P4 to obtain recovered ethylene glycol S8, which is returned to the depolymerization unit for recycling.

[0115] (4) The recycled water S9 at the bottom of the membrane separator X1 is cooled to 30°C by the second cooler E3. The cooled recycled water S10 enters the recycled water tank V2 from the upper part (1 / 4 of the recycled water tank V2), and is returned to the depolymerization unit for recycling via the recycled water pump P2.

[0116] The quality composition of each major logistics item is shown in Table 3.

[0117] Table 3

[0118]

[0119]

[0120] The results above show that the method of the present invention can effectively recycle ethylene glycol and water, and can reduce the consumption of ethylene glycol and water.

[0121] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A device for recycling polyester glycol alcoholysis solution, characterized in that, The device includes: a raw material tank (V1), a preheater (E1), a membrane separator (X1), an intermediate tank (V3), a dehydration tower (T1), and a recovered ethylene glycol tank (V4) connected in sequence; and a recovered water tank (V2) connected to the bottom of the membrane separator (X1).

2. The apparatus according to claim 1, wherein, The device further includes: a raw material tank (V1), a feed pump (P1), a preheater (E1), a membrane separator (X1), a first cooler (E2), an intermediate tank (V3), a transfer pump (P3), a dehydration tower (T1), and a recovered ethylene glycol tank (V4) connected in sequence; and a second cooler (E3) and a recovered water tank (V2) connected in sequence to the bottom of the membrane separator (X1).

3. The apparatus according to claim 1 or 2, wherein, The preheater (E1) is connected to the lower part of the membrane separator (X1), and the upper part of the membrane separator (X1) is connected to the upper part of the intermediate tank (V3) through the first cooler (E2).

4. The apparatus according to claim 1 or 2, wherein, The bottom of the intermediate tank (V3) is connected to the preheater (E1) via a transfer pump (P3) and is also connected to the bottom of the dehydration tower (T1); the top of the dehydration tower (T1) is connected to the top of the recovery glycol tank (V4), and the bottom of the recovery glycol tank (V4) is connected to the recovery glycol pump (P4).

5. The apparatus according to claim 1 or 2, wherein, The second cooler (E3) is connected to the upper part of the recovery water tank (V2).

6. The apparatus according to claim 1 or 2, wherein, The top of the water recovery tank (V2) is connected to a vacuum pump, and the bottom of the water recovery tank (V2) is connected to a water recovery pump (P2).

7. The apparatus according to any one of claims 1-6, wherein, The membrane separator (X1) contains a component of selectively permeable membranes and / or selectively permeable membranes; Preferably, the selectively permeable membrane is a type A molecular sieve membrane or a pervaporation membrane; And / or, the dehydration tower (T1) is filled with molecular sieves; Preferably, the molecular sieve is a 4A molecular sieve and / or a 3A molecular sieve.

8. A method for recycling polyester glycol alcoholysis solution using the apparatus according to any one of claims 1-7, characterized in that, The method includes: (1) The polyester glycol alcoholysis solution S1 in the raw material tank (V1) is preheated by the alcoholysis solution S2 after passing through the feed pump (P1) and the preheated alcoholysis solution S3 is introduced into the membrane separator (X1) for membrane separation. (2) The permeate S4 after membrane separation is cooled by the first cooler (E2) and then the permeate S5 enters the intermediate tank (V3). The permeate S6 after passing through the transfer pump (P3) is introduced into the dehydration tower (T1) for dehydration treatment, and the recovered ethylene glycol S7 after the dehydration treatment is entered into the recovered ethylene glycol tank (V4) for recycling. (3) The recycled water S9 after membrane separation is cooled by the second cooler (E3) and then recycled water S10 enters the recycled water tank (V2) for recycling.

9. The method according to claim 8, wherein, In step (1), the preheated alcoholysis solution S3 is introduced into the membrane separator (X1) from the bottom for membrane separation; And / or, in step (2), the permeate S4 after membrane separation is cooled by the first cooler (E2) and then the permeate S5 enters the intermediate tank (V3) from the top of the intermediate tank (V3), and the permeate S6 after passing through the transfer pump (P3) is introduced into the dehydration tower (T1) from the bottom for dehydration treatment; And / or, in step (3), the recycled water S9 after membrane separation is cooled by the second cooler (E3) and then recycled water S10 enters the recycled water tank (V2) from the top of the recycled water tank (V2) for recycling.

10. The method according to claim 8 or 9, wherein, The polyester glycol alcoholysis solution S1 contains ethylene glycol and water; Preferably, based on the total weight of the polyester glycol alcoholysis solution S1, the ethylene glycol content is 20-45% by weight, preferably 25-35% by weight; and the water content is 55-80% by weight. Preferably, the pH value of the polyester glycol alcoholysis solution S1 is 6-8.5; And / or, the water content in the ethylene glycol in the intermediate tank (V3) is ≤0-1.5%; And / or, the purity of the recovered ethylene glycol S7 is greater than 99%, preferably greater than 99.5%.

11. The method according to claim 8, wherein, In step (1), the membrane separation conditions include: pressure of 0.5-0.2 MPa and temperature of 85-100℃; And / or, in step (2), the conditions for the dehydration treatment include: a pressure of 0.1-0.4 MPa and a temperature of 20-35°C; Preferably, after dehydration in the dehydration tower (T1), activation treatment is also performed; Preferably, the activation treatment conditions include: a pressure of 0.01-0.05 MPa and a temperature of 350-450°C.

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