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CN-122006473-A - Device and method for recycling polyester glycol alcoholysis liquid

CN122006473ACN 122006473 ACN122006473 ACN 122006473ACN-122006473-A

Abstract

The invention relates to the technical field of recycling of polyester ethylene glycol alcoholysis liquid, and discloses a device and a method for recycling the polyester ethylene glycol alcoholysis liquid, wherein the device comprises a raw material tank V1, a preheater E1, a membrane separator X1, a middle tank V3, a dehydration tower T1 and a recovered ethylene glycol tank V4 which are sequentially connected; and a recovery water tank V2 connected with the bottom of the membrane separator X1. The method can effectively recycle ethylene glycol and water, and can reduce the consumption of ethylene glycol and water.

Inventors

  • SUN RULIU
  • GUO LIANG
  • LI CHUNFANG
  • WEI JIANGPENG
  • LI YULONG
  • QIU XINYAN
  • CHEN GUANYU

Assignees

  • 中国石油化工股份有限公司
  • 中石化(北京)化工研究院有限公司

Dates

Publication Date
20260512
Application Date
20241112

Claims (11)

  1. 1. A device for recycling polyester glycol alcoholysis liquid is characterized by comprising a raw material tank (V1), a preheater (E1), a membrane separator (X1), a middle tank (V3), a dehydration tower (T1) and a recovered glycol tank (V4) which are sequentially connected, and a recovered water tank (V2) connected with the bottom of the membrane separator (X1).
  2. 2. The apparatus according to claim 1, wherein the apparatus further 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 column (T1) and a recovered glycol tank (V4) which are sequentially connected, and a second cooler (E3) and a recovered water tank (V2) which are sequentially connected to the bottom of the membrane separator (X1).
  3. 3. The apparatus according to claim 1 or 2, wherein the preheater (E1) is arranged in connection with the lower part of the membrane separator (X1), the upper part of the membrane separator (X1) being arranged in connection with the upper part of the intermediate tank (V3) via the first cooler (E2).
  4. 4. The device according to claim 1 or 2, wherein the bottom of the intermediate tank (V3) is connected to the preheater (E1) by a transfer pump (P3) and is connected to the bottom of the dehydration column (T1), the top of the dehydration column (T1) is connected to the top of the recovered glycol tank (V4), and the bottom of the recovered glycol tank (V4) is connected to the recovered glycol pump (P4).
  5. 5. The apparatus according to claim 1 or 2, wherein a second cooler (E3) is provided in connection with the upper part of the recovery water tank (V2).
  6. 6. The device according to claim 1 or 2, wherein the top of the recovery water tank (V2) is connected to the evacuation device, and the bottom of the recovery water tank (V2) is connected to the recovery water pump P2.
  7. 7. The apparatus according to any one of claims 1-6, wherein within the membrane separator (X1) is a permselective membrane and/or a permselective membrane module; preferably, the selectively permeable membrane is an A-type molecular sieve membrane pervaporation membrane; and/or, the dehydrating tower (T1) is filled with molecular sieve; Preferably, the molecular sieve is a 4A molecular sieve and/or a 3A molecular sieve.
  8. 8. A method for recycling a polyester ethylene glycol alcoholysis liquid by using the device of any one of claims 1-7, comprising the steps of: (1) Preheating the alcoholysis solution S2 of the polyester glycol in the raw material tank (V1) after passing through a feed pump (P1) by a preheater (E1), and introducing the preheated alcoholysis solution S3 into a membrane separator (X1) for membrane separation; (2) The permeate S4 after membrane separation enters a middle tank (V3) through a permeate S5 cooled by a first cooler (E2), and then the permeate S6 after passing through a delivery pump (P3) is introduced into a dehydration tower (T1) for dehydration treatment, and the recovered glycol S7 after dehydration treatment enters a recovered glycol tank (V4) for recycling; (3) The recovered water S9 after the membrane separation enters a recovered water tank (V2) for recycling after the recovered water S10 is cooled by a second cooler (E3).
  9. 9. The method according to claim 8, wherein in step (1), the preheated alcoholysis liquid S3 is introduced into the membrane separator (X1) from the lower part of the membrane separator (X1) to perform membrane separation; And/or, in the step (2), the permeate S4 after the membrane separation passes through the first cooler (E2) to be cooled, the permeate S5 passes through the upper part of the intermediate tank (V3) to enter the intermediate tank (V3), and the permeate S6 after passing through the delivery pump (P3) is introduced into the dehydration tower (T1) from the bottom of the dehydration tower (T1) to be dehydrated; And/or, in the step (3), the recovered water S9 after the membrane separation is cooled by the second cooler (E3), and the recovered water S10 after the membrane separation enters the recovered water tank (V2) from the upper part of the recovered water tank (V2) for recycling.
  10. 10. The method according to claim 8 or 9, wherein the polyester ethylene glycol alcoholysis liquid S1 contains ethylene glycol and water; preferably, the content of ethylene glycol is 20-45 wt%, preferably 25-35 wt%, and the content of water is 55-80 wt%, based on the total weight of the polyester ethylene glycol alcoholysis solution S1; preferably, the pH value of the polyester glycol alcoholysis solution S1 is 6-8.5; And/or the water content in the glycol in the intermediate tank (V3) is less than or equal to 0-1.5%; and/or the purity of the recovered ethylene glycol S7 is greater than 99%, preferably greater than 99.5%.
  11. 11. The process according to claim 8, wherein in the step (1), the conditions for membrane separation include a pressure of 0.5 to 0.2Mpa and a temperature of 85 to 100 ℃; and/or, in the step (2), the dehydration treatment conditions include a pressure of 0.1-0.4Mpa and a temperature of 20-35 ℃; preferably, the dehydration treatment in the dehydration column (T1) is followed by an activation treatment; preferably, the conditions of the activation treatment include a pressure of 0.01 to 0.05Mpa and a temperature of 350 to 450 ℃.

Description

Device and method for recycling polyester glycol alcoholysis liquid Technical Field The invention relates to the technical field of recycling of polyester ethylene glycol alcoholysis liquid, in particular to a device and a method for recycling the polyester ethylene glycol alcoholysis liquid. Background Polyester PET is the polyester material with the largest world consumption, and the excellent physical and chemical properties of PET lead to the wide application of the PET in single-purpose or multi-purpose products such as food and beverage containers, and brings great environmental protection pressure, and a large amount of waste PET needs to be recycled. In the chemical degradation method of PET, the degradation and recovery of PET by an alcoholysis method is more mature than other chemical recovery processes, and the alcoholysis process is gradually improved through continuous geographic analysis and practice for many years, so that a plurality of companies have industrialized devices. The industrial alcoholysis method is mainly divided into methanolysis and glycolysis. The methanolysis means that ester bonds in PET are broken in a reaction atmosphere of methanol to generate dimethyl terephthalate (DMT), and the DMT can be used as a polymerization monomer of PET and PBT to be polymerized again. The glycol alcoholysis method has the advantages of simple reaction route, no harsh requirements on temperature and pressure, simple experimental design and implementation, higher safety coefficient of reaction, suitability for industrial mass production, and maximized improvement of economic benefit, and besides, the glycol alcoholysis route does not contain corrosive substances, so that the pollution emission is reduced, and meanwhile, the maintenance cost of equipment is also reduced. From a practical standpoint, the monomer ethylene terephthalate (BHET) produced by this route can be directly fed to the polymerization route and incorporated into conventional PET production facilities without pretreatment and without the production of other by-products. Aiming at the problems of low depolymerization efficiency and incomplete depolymerization in the existing waste PET chemical method recovery process, a novel green efficient depolymerization technology is developed, but the consumption of glycol and water in the recrystallization process is large, and the development of a recycling technology of glycol alcoholysis liquid is urgently needed to realize recycling. Disclosure of Invention The invention aims to overcome the problems of low depolymerization efficiency and incomplete depolymerization in the existing chemical method recovery process of waste PET and the defect of large consumption of glycol and water in the recrystallization process in the depolymerization technology, and provides a device and a method for recycling polyester glycol alcoholysis liquid. In order to achieve the aim, the first aspect of the invention provides a device for recycling a polyester glycol alcoholysis liquid, wherein the device comprises a raw material tank V1, a preheater E1, a membrane separator X1, an intermediate tank V3, a dehydration tower T1 and a recovered glycol tank V4 which are sequentially connected, and a recovered water tank V2 connected with the bottom of the membrane separator X1. The second aspect of the invention provides a method for recycling a polyester glycol alcoholysis liquid by adopting the device, wherein the method comprises the following steps: (1) The method comprises the steps of preheating an alcoholysis solution S2 of polyester glycol in a raw material tank V1 through a preheater E1 after the alcoholysis solution S1 passes through a feed pump P1, and introducing a preheated alcoholysis solution S3 into a membrane separator X1 for membrane separation; (2) The permeate S4 after membrane separation enters a middle tank V3 through a permeate S5 cooled by a first cooler E2, and then the permeate S6 after passing through a delivery pump P3 is introduced into a dehydration tower T1 for dehydration treatment, and the recovered glycol S7 after dehydration treatment enters a recovered glycol tank V4 for recycling; (3) The recovered water S9 after the membrane separation enters the recovered water tank V2 for recycling through the recovered water S10 after the cooling of the second cooler E3. Through the technical scheme, the method can effectively recycle glycol and water, and the treated glycol and water meet the recycling requirement, so that the recycling of raw materials is realized, and the wastewater discharge is greatly reduced. Drawings FIG. 1 is a schematic diagram of recycling of the polyester ethylene glycol alcoholysis liquid of the present invention. Description of the reference numerals 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 pumping device, P3 tr