Recovery system and recovery process thereof

Abstract

The invention relates to a recovery system and a recovery process thereof. The recovery system comprises an evaporator, a primary tower, an azeotropic rectifying tower and a finished product recovery tower which are sequentially communicated from upstream to downstream, wherein the evaporator is used for converting the waste diluent into the waste diluent steam, and the waste diluent steam comprises gas-state PGMEA and gas-state PGME; the primary distillation tower is used for carrying out primary distillation treatment on the waste diluent steam so as to remove low-boiling-point impurities and obtain primary distillation products, and the primary distillation products comprise PGMEA and PGME; the azeotropic rectification tower is used for carrying out rectification treatment on the primary distillation product so as to carry out dehydration and obtain a rectified product, and the rectified product comprises PGMEA and PGME; and the finished product recovery tower is used for separating and recovering the rectified product to obtain a PGMEA finished product and a PGME finished product. According to the recovery device, the recovery rate of PGMEA and PGME in the waste diluent is improved, and the economic benefits of enterprise production are further improved.

Description

Technical Field

[0001] The present invention relates to the field of waste diluent recovery, and in particular to a recovery system and a recovery process. Background Art

[0002] Propylene glycol methyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are widely used in the electronics industry due to their strong solvency, excellent environmental performance, and low toxicity. PGMEA and PGME are representative diluent and cleaning agent components in the electronics industry, and are often mixed in a specific ratio to enhance their stability. In the photolithography process for panels and semiconductors, electronic-grade PGMEA / PGME mixed solvents are primarily used as diluents and cleaning agents. The dilution and cleaning processes generate large amounts of waste diluent containing PGMEA, PGME, and water. Recovering PGMEA and PGME from this waste diluent offers both economic and environmental benefits. Both PGMEA and PGME form binary minimum azeotropes with water. When recycling the waste diluent using conventional distillation processes, water entrains some PGMEA and PGME products. The higher the water content in the feedstock, the greater the amount of PGMEA and PGME entrained, reducing the recovery rate of the active ingredients, PGMEA and PGME. For the PGMEA / water and PGME / water azeotropic systems, it is necessary to optimize the traditional conventional distillation process and find a new process to improve the recovery rate of PGMEA and PGME in the waste diluent. Summary of the Invention

[0003] Based on this, it is necessary to provide a recycling system and recycling process.

[0004] A recovery system comprises an evaporator, a primary distillation tower, an azeotropic distillation tower, and a finished product recovery tower which are sequentially connected from upstream to downstream; wherein:

[0005] The evaporator is used to convert the waste diluent into the waste diluent steam, wherein the waste diluent steam includes gaseous PGMEA and gaseous PGME;

[0006] The primary distillation tower is used to perform primary distillation treatment on the waste diluent steam to remove low-boiling point impurities and obtain a primary distillation product, wherein the primary distillation product includes PGMEA and PGME;

[0007] The azeotropic distillation tower is used to perform distillation treatment on the primary distillation product to dehydrate it to obtain a distillation product, wherein the distillation product includes PGMEA and PGME;

[0008] The finished product recovery tower is used to separate and recover the distillation product to obtain PGMEA finished products and PGME finished products.

[0009] In one embodiment, the raw material inlet of the evaporator is the waste diluent inlet, the gas phase outlet of the evaporator is connected to the gas phase inlet of the primary distillation tower, the liquid phase inlet of the evaporator is connected to the liquid phase outlet at the bottom of the primary distillation tower, and the liquid phase outlet of the evaporator is the distillation residue outlet; the evaporator is also provided with a steam inlet and a steam condensate outlet; the evaporator is one of a scraper evaporator, a thin film evaporator, a tubular evaporator, etc.

[0010] In one embodiment, the recovery system further includes a primary distillation tower first-stage condenser, a primary distillation tower second-stage condenser, a low-boiling-point impurity collection tank, and a primary distillation product collection tank; the primary distillation tower, the primary distillation tower first-stage condenser, the primary distillation tower second-stage condenser, and the low-boiling-point impurity collection tank are connected in sequence through pipelines; the outlet of the low-boiling-point impurity collection tank is a low-boiling-point impurity extraction outlet; the primary distillation tower first-stage condenser is connected to the reflux port of the primary distillation tower through a pipeline, and the primary distillation tower first-stage condenser is also connected to the inlet of the primary distillation product collection tank and the secondary condenser of the primary distillation tower through pipelines respectively; the outlet of the primary distillation product collection tank is connected to the azeotropic distillation tower through a pipeline.

[0011] In one embodiment, the recovery system further comprises an azeotropic distillation tower condenser, an entrainer cooler, and an entrainer separator; wherein,

[0012] The gas phase outlet of the azeotropic distillation tower is connected to the gas phase inlet of the azeotropic distillation tower condenser through a pipeline, and the liquid phase outlet of the azeotropic distillation tower condenser is connected to the reflux port of the azeotropic distillation tower and the inlet of the entrainer cooler respectively;

[0013] The outlet of the entrainer cooler is connected to the inlet of the entrainer separator through a pipeline; the entrainer outlet of the entrainer separator is connected to the entrainer inlet of the azeotropic distillation tower, and the entrainer separator is also provided with a wastewater outlet; the entrainer inlet of the azeotropic distillation tower is also provided with a supplementary entrainer inlet; the entrainer is one of benzene, toluene, n-propanol, diisopropyl ether, n-pentane and cyclohexane, etc. Preferably, the entrainer is cyclohexane.

[0014] In one embodiment, the recovery system further comprises an azeotropic distillation column reboiler; wherein,

[0015] The water outlet of the azeotropic distillation tower is connected to the azeotropic distillation tower reboiler, and the steam condensed water outlet of the azeotropic distillation tower reboiler is also connected to the azeotropic distillation tower, and the azeotropic distillation tower reboiler is also connected to a steam inlet;

[0016] The azeotropic distillation tower is further provided with a liquid phase outlet, and the liquid phase outlet of the azeotropic distillation tower is communicated with the finished product recovery tower.

[0017] In one embodiment, the recovery system further comprises a finished product recovery tower condenser; wherein,

[0018] The gas phase outlet of the finished product recovery tower is connected to the gas phase inlet of the finished product recovery tower condenser through a pipeline; the liquid phase outlet of the finished product recovery tower condenser is connected to the reflux port of the finished product recovery tower, and the outlet of the finished product recovery tower condenser is also provided with a PGME finished product collection outlet.

[0019] In one embodiment, the recovery system further comprises a finished product recovery tower reboiler; wherein,

[0020] The water outlet of the finished product recovery tower is connected to the finished product recovery tower reboiler, and the finished product recovery tower is also connected to the steam condensate outlet of the finished product recovery tower reboiler, and the finished product recovery tower reboiler is also connected to a steam inlet;

[0021] The finished product recovery tower is also provided with a liquid phase outlet, and the liquid phase outlet of the finished product recovery tower is the PGMEA finished product collection outlet.

[0022] A production process for recovering PGMEA and PGME by azeotropic distillation, which uses the azeotropic distillation device for recovering PGMEA and PGME from the waste diluent as claimed in any one of claims 1 to 6 for production.

[0023] In one embodiment, the recovery process comprises the following steps:

[0024] The waste diluent is allowed to enter the evaporator, and the evaporator uses steam to provide heat load. The volatile components in the waste diluent are volatilized into gas phase and enter the primary distillation tower. The high-boiling-point material at the bottom of the primary distillation tower is returned to the evaporator, and the non-volatile distillation residue is extracted through the liquid phase outlet of the evaporator; the outlet gas at the top of the primary distillation tower is condensed in the first-level condenser and the second-level condenser of the primary distillation tower, and the liquid condensed in the second-level condenser of the primary distillation tower is extracted as a low-boiling-point impurity; a part of the liquid condensed in the first-level condenser of the primary distillation tower is returned to the primary distillation tower as reflux, and a part is extracted as a primary distillation product and enters the azeotropic distillation tower; the outlet gas at the top of the azeotropic distillation tower is condensed in the azeotropic distillation tower condenser, and a part of the liquid condensed in the azeotropic distillation tower condenser is returned to the azeotropic distillation tower as reflux, and a part is extracted as a primary distillation product and enters the azeotropic distillation tower. The condensate is cooled by the entrainer cooler, and the cooled condensate enters the entrainer separator. The upper oil phase of the entrainer separator is extracted and recycled, and enters the azeotropic distillation tower together with the supplementary entrainer, and the lower water phase of the entrainer separator is extracted as wastewater; the azeotropic distillation tower uses steam to provide heat load through the azeotropic distillation tower reboiler, and the liquid phase at the bottom outlet of the azeotropic distillation tower enters the finished product recovery tower; the gas at the top outlet of the finished product recovery tower is condensed in the finished product recovery tower condenser, and part of the liquid condensed in the finished product recovery tower condenser is returned to the finished product recovery tower as reflux, and part is extracted as PGME finished product; the finished product recovery tower uses steam to provide heat load through the finished product recovery tower reboiler, and the liquid phase at the bottom outlet of the finished product recovery tower is extracted as PGMEA finished product.

[0025] In one embodiment, the tops of the primary distillation tower, the azeotropic distillation tower, and the finished product recovery tower are all operated under negative pressure.

[0026] In one embodiment, the operating pressure of the top of the primary distillation tower is -10 to 100 kPa, the top temperature is 80 to 125° C., and the bottom temperature is 85 to 135° C.;

[0027] The azeotropic distillation tower has a top operating pressure of -10 to 100 kPa, a top temperature of 20 to 90° C., and a bottom temperature of 85 to 140° C.

[0028] The top operating pressure of the finished product recovery tower is -10 to 100 kPa, the top temperature is 70 to 115° C., and the bottom temperature is 135 to 165° C.

[0029] The azeotropic distillation device and production process for recovering PGMEA and PGME from the above-mentioned waste diluent are configured with an evaporator, a primary distillation tower, an azeotropic distillation tower, and a finished product recovery tower. The raw waste diluent is separated into a distillation residue in the evaporator, and then the low-boiling point impurities are separated in the primary distillation tower and the primary distillation product is recovered. The primary distillation product is dehydrated with an entrainer in the azeotropic distillation tower, and the dehydrated waste diluent is used to recover PGMEA and PGME products in the finished product recovery tower. The separated distillation residue is further treated by incineration, and the separated low-boiling point impurities and wastewater are further treated by biochemical or incineration processes. The device and production process use an entrainer to dehydrate the waste diluent, destroying the composition of the PGMEA / water and PGME / water azeotropic systems, thereby improving the recovery rate of PGMEA and PGME in the waste diluent and further improving the economic benefits of the enterprise's production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the structure of an azeotropic distillation device for recovering PGMEA and PGME from waste diluent in one embodiment, wherein arrows in the figure indicate the flow direction of liquid and / or steam.

[0031] The following are the descriptions of the reference numerals:

[0032] 1: Evaporator; 2: Primary distillation tower; 3: Primary distillation tower first-stage condenser; 4: Primary distillation tower second-stage condenser; 5: Low-boiling-point impurity collection tank; 6: Primary distillation product collection tank; 7: Azeotropic distillation tower; 8: Azeotropic distillation tower reboiler; 9: Azeotropic distillation tower condenser; 10: Entrainer cooler; 11: Entrainer separator; 12: Finished product recovery tower; 13: Finished product recovery tower reboiler; 14: Finished product recovery tower condenser. DETAILED DESCRIPTION

[0033] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] The recovery system of one embodiment includes an evaporator 1, a primary distillation tower 2, an azeotropic distillation tower 7, and a finished product recovery tower 12, which are sequentially connected from upstream to downstream; wherein,

[0036] The evaporator 1 is used to convert the waste diluent into the waste diluent steam, wherein the waste diluent steam includes gaseous PGMEA and gaseous PGME;

[0037] The primary distillation tower 2 is used to perform primary distillation treatment on the waste diluent steam to remove low-boiling point impurities and obtain primary distillation products, wherein the primary distillation products include PGMEA and PGME;

[0038] The azeotropic distillation tower 7 is used to perform distillation treatment on the primary distillation product to dehydrate it to obtain a distillation product, which includes PGMEA and PGME;

[0039] The finished product recovery tower 12 is used to separate and recover the distillation product to obtain PGMEA finished products and PGME finished products.

[0040] In one embodiment, specifically, Figure 1 As shown, the recovery system includes an evaporator 1, a primary distillation tower 2, a primary distillation tower primary condenser 3, a primary distillation tower secondary condenser 4, a low-boiling-point impurity collection tank 5, a primary distillation product collection tank 6, an azeotropic distillation tower 7, an azeotropic distillation tower reboiler 8, an azeotropic distillation tower condenser 9, an entrainer cooler 10, an entrainer separator 11, a finished product recovery tower 12, a finished product recovery tower reboiler 13, and a finished product recovery tower condenser 14. The corresponding equipment of the azeotropic distillation device for recovering PGMEA and PGME from the waste diluent of this embodiment is connected by connecting mechanisms such as pipelines.

[0041] Specifically, in this embodiment, the raw material inlet of the evaporator 1 is the waste diluent inlet, the gas phase outlet of the evaporator 1 is connected to the gas phase inlet of the primary distillation tower 2, the liquid phase inlet of the evaporator 1 is connected to the liquid phase outlet at the bottom of the primary distillation tower 2, and the liquid phase outlet of the evaporator 1 is the distillation residue outlet; the evaporator 1 is also provided with a steam inlet and a steam condensate outlet; the evaporator 1 is one of a scraper evaporator, a thin film evaporator, a tubular evaporator, etc.

[0042] Specifically, the primary distillation tower 2, the primary distillation tower first-stage condenser 3, the primary distillation tower second-stage condenser 4, and the low-boiling-point impurity collecting tank 5 are connected in sequence through pipelines; the outlet of the low-boiling-point impurity collecting tank 5 is the low-boiling-point impurity extraction outlet; the primary distillation tower first-stage condenser 4 is connected to the reflux port of the primary distillation tower 2 and the inlet of the primary distillation product collecting tank 6 through pipelines respectively; the outlet of the primary distillation product collecting tank 6 is connected to the azeotropic distillation tower 7 through a pipeline.

[0043] Specifically, the gas phase outlet at the top of the azeotropic distillation tower 7 is connected to the gas phase inlet of the azeotropic distillation tower condenser 9 through a pipeline, and the liquid phase outlet of the azeotropic distillation tower condenser 9 is connected to the reflux port of the azeotropic distillation tower 7 and the inlet of the entrainer cooler 10 respectively;

[0044] The outlet of the entrainer cooler 10 is connected to the inlet of the entrainer separator 11 through a pipeline; the entrainer outlet of the entrainer separator 11 is connected to the entrainer inlet of the azeotropic distillation tower 7, and the entrainer separator 11 is also provided with a wastewater outlet; the entrainer inlet of the azeotropic distillation tower 7 is also provided with a supplementary entrainer inlet; the entrainer is one of benzene, toluene, n-propanol, diisopropyl ether, n-pentane and cyclohexane, etc., and the preferred entrainer is cyclohexane.

[0045] The azeotropic distillation tower 7 is connected to the azeotropic distillation tower reboiler 8 through a pipeline loop, and the azeotropic distillation tower reboiler 8 is also connected to a steam inlet and a steam condensate outlet;

[0046] A liquid phase outlet is further provided at the bottom of the azeotropic distillation tower 7 , and the liquid phase outlet at the bottom of the azeotropic distillation tower 7 is communicated with the finished product recovery tower 12 .

[0047] Specifically, the gas phase outlet at the top of the finished product recovery tower 12 is connected to the gas phase inlet of the finished product recovery tower condenser 14 through a pipeline; the liquid phase outlet of the finished product recovery tower condenser 14 is connected to the reflux port of the finished product recovery tower 12, and the outlet of the finished product recovery tower condenser 14 is also provided with a propylene glycol methyl ether (PGME) finished product collection outlet.

[0048] The finished product recovery tower 12 is connected to the finished product recovery tower reboiler 13 through a pipeline loop, and the finished product recovery tower reboiler 13 is also connected to a steam inlet and a steam condensate outlet;

[0049] A liquid phase outlet is also provided at the bottom of the finished product recovery tower 12, and the liquid phase outlet at the bottom of the finished product recovery tower 12 is a finished product collection outlet for propylene glycol methyl ether acetate (PGMEA).

[0050] This embodiment also provides a production process for recovering PGMEA and PGME using the above-mentioned waste diluent azeotropic distillation device. The production process specifically includes the following steps during operation:

[0051] The waste diluent from the raw material tank area enters the evaporator 1 through a conveying device such as a pump and a pipeline. The evaporator 1 uses steam to provide a heat load. The volatile components in the waste diluent evaporate into a gas phase and enter the primary distillation tower 2. The high-boiling-point material at the bottom of the primary distillation tower 2 returns to the evaporator 1, and the non-volatile distillation residue in the evaporator 1 is extracted through the liquid phase outlet. The outlet gas at the top of the primary distillation tower 2 is condensed in the primary distillation tower primary condenser 3 and the primary distillation tower secondary condenser 4. The liquid condensed in the primary distillation tower secondary condenser 4 is extracted as a low-boiling-point impurity. A portion of the liquid condensed in the primary distillation tower primary condenser 3 is returned to the primary distillation tower 2 as reflux, and a portion is extracted as a primary distillation product and enters the azeotropic distillation tower 7. The gas at the top outlet of the azeotropic distillation tower 7 is condensed in the azeotropic distillation tower condenser 9. A portion of the liquid condensed in the azeotropic distillation tower condenser 9 is returned to the azeotropic distillation tower 7 as reflux, and a portion is cooled by the entrainer cooler 10. The cooled condensate enters the entrainer separator 11. The upper oil phase of the entrainer separator 11 is extracted and recycled, and enters the azeotropic distillation tower 7 together with the supplementary entrainer. The lower water phase of the entrainer separator 11 is extracted as wastewater. The azeotropic distillation tower 7 uses steam to provide a heat load through the azeotropic distillation tower reboiler 8. The liquid phase at the bottom outlet of the azeotropic distillation tower 7 enters the finished product recovery tower 12. The gas at the top outlet of the finished product recovery tower 12 is condensed in the finished product recovery tower condenser 14. A portion of the liquid condensed in the finished product recovery tower condenser 14 is returned to the finished product recovery tower 12 as reflux, and a portion is extracted as the propylene glycol methyl ether (PGME) finished product. The finished product recovery tower 12 uses steam to provide heat load through the finished product recovery tower reboiler 13, and the liquid phase at the bottom outlet of the finished product recovery tower 12 is withdrawn as propylene glycol methyl ether acetate (PGMEA) finished product.

[0052] In this embodiment, the tops of the primary distillation tower 2, the azeotropic distillation tower 7, and the finished product recovery tower 12 are all operated under negative pressure. The primary distillation tower 2, the azeotropic distillation tower 7, and the finished product recovery tower 12 can be either plate towers or packed towers.

[0053] Specifically, the evaporator 1, azeotropic distillation tower 7, and finished product recovery tower 12 all use primary steam from the boiler to provide heat loads. The top operating pressure of the primary distillation tower 2 is -10 to 100 kPa, the top temperature is 80 to 125°C, and the bottom temperature is 85 to 135°C. The top operating pressure of the azeotropic distillation tower 7 is -10 to 100 kPa, the top temperature is 20 to 90°C, and the bottom temperature is 85 to 140°C. The top operating pressure of the finished product recovery tower 12 is -10 to 100 kPa, the top temperature is 70 to 115°C, and the bottom temperature is 135 to 165°C.

[0054] The PGMEA and PGME azeotropic distillation device of the present embodiment and its production process are configured by evaporator 1, primary distillation tower 2, azeotropic distillation tower 7, finished product recovery tower 12, the raw material waste diluent is separated into distillation residue in evaporator 1, and then low-boiling impurities are separated in primary distillation tower 2 and the recovery of the primary distillation product is carried out, the primary distillation product is dehydrated in azeotropic distillation tower 7 using an entrainer, and the dehydrated waste diluent reclaims PGMEA and PGME products in finished product recovery tower 12. The separated distillation residue is further processed by incineration, and the separated low-boiling impurities and wastewater are further processed by biochemical or incineration process. The device and production process are dehydrated by using an entrainer to destroy the composition of PGMEA / water and PGME / water azeotropic system, thereby improving the recovery rate of PGMEA and PGME in the waste diluent, further improving the economic benefit of enterprise production.

[0055] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A recycling system, characterized in that: It includes an evaporator, a primary distillation tower, an azeotropic distillation tower, and a finished product recovery tower which are sequentially connected from upstream to downstream; wherein, The evaporator is used to convert the waste diluent into the waste diluent steam, wherein the waste diluent steam includes gaseous PGMEA and gaseous PGME; The primary distillation tower is used to perform primary distillation treatment on the waste diluent steam to remove low-boiling point impurities and obtain a primary distillation product, wherein the primary distillation product includes PGMEA and PGME; The azeotropic distillation tower is used to perform distillation treatment on the primary distillation product to dehydrate it to obtain a distillation product, wherein the distillation product includes PGMEA and PGME; The finished product recovery tower is used to separate and recover the distillation product to obtain PGMEA finished products and PGME finished products.

2. The recycling system according to claim 1, wherein: The raw material inlet of the evaporator is the waste diluent inlet, the gas phase outlet of the evaporator is connected to the gas phase inlet of the primary distillation tower, the liquid phase inlet of the evaporator is connected to the liquid phase outlet of the primary distillation tower, and the liquid phase outlet of the evaporator is the distillation residue outlet; the evaporator is also provided with a steam inlet and a steam condensate outlet; the evaporator is one of a scraper evaporator, a thin film evaporator, a tubular evaporator, etc.

3. The recycling system according to claim 1, wherein: It also includes a primary distillation tower first-stage condenser, a primary distillation tower second-stage condenser, a low-boiling-point impurity collection tank, and a primary distillation product collection tank; the primary distillation tower, the primary distillation tower first-stage condenser, the primary distillation tower second-stage condenser, and the low-boiling-point impurity collection tank are connected in sequence through pipelines; the outlet of the low-boiling-point impurity collection tank is a low-boiling-point impurity extraction outlet; the primary distillation tower first-stage condenser is connected to the reflux port of the primary distillation tower through a pipeline, and the primary distillation tower first-stage condenser is also connected to the inlet of the primary distillation product collection tank and the secondary condenser of the primary distillation tower through pipelines respectively; the outlet of the primary distillation product collection tank is connected to the azeotropic distillation tower through a pipeline.

4. The recycling system according to claim 1, wherein: It also includes an azeotropic distillation tower condenser, an entrainer cooler, and an entrainer separator; wherein, The gas phase outlet of the azeotropic distillation tower is connected to the gas phase inlet of the azeotropic distillation tower condenser through a pipeline, and the liquid phase outlet of the azeotropic distillation tower condenser is connected to the reflux port of the azeotropic distillation tower and the inlet of the entrainer cooler respectively; The outlet of the entrainer cooler is connected to the inlet of the entrainer separator through a pipeline; the entrainer outlet of the entrainer separator is connected to the entrainer inlet of the azeotropic distillation tower, and the entrainer separator is also provided with a wastewater outlet; the entrainer inlet of the azeotropic distillation tower is also provided with a supplementary entrainer inlet; the entrainer is one of benzene, toluene, n-propanol, diisopropyl ether, n-pentane and cyclohexane, etc. Preferably, the entrainer is cyclohexane.

5. The azeotropic distillation device for recovering PGMEA and PGME from waste diluent according to claim 1, characterized in that Also includes an azeotropic distillation column reboiler; wherein, The water outlet of the azeotropic distillation tower is connected to the azeotropic distillation tower reboiler, and the steam condensed water outlet of the azeotropic distillation tower reboiler is also connected to the azeotropic distillation tower. The azeotropic distillation tower reboiler is also connected to a steam inlet; The azeotropic distillation tower is further provided with a liquid phase outlet, and the liquid phase outlet of the azeotropic distillation tower is communicated with the finished product recovery tower.

6. The recycling system according to claim 1, wherein: It also includes a finished product recovery tower condenser and a finished product recovery tower reboiler; wherein, The gas phase outlet of the finished product recovery tower is connected to the gas phase inlet of the finished product recovery tower condenser through a pipeline; the liquid phase outlet of the finished product recovery tower condenser is connected to the reflux port of the finished product recovery tower, and the finished product recovery tower condenser is also provided with a PGME finished product collection outlet.

7. The recycling system according to claim 1, wherein: It also includes a finished product recovery tower reboiler; wherein, The water outlet of the finished product recovery tower is connected to the finished product recovery tower reboiler, and the finished product recovery tower is also connected to the steam condensate outlet of the finished product recovery tower reboiler, and the finished product recovery tower reboiler is also connected to a steam inlet; The finished product recovery tower is also provided with a liquid phase outlet, and the liquid phase outlet of the finished product recovery tower is the PGMEA finished product collection outlet.

8. A recycling process, characterized in that: The specific steps include: The waste diluent is allowed to enter the evaporator, and the evaporator uses steam to provide heat load. The volatile components in the waste diluent are volatilized into gas phase and enter the primary distillation tower. The high-boiling-point material at the bottom of the primary distillation tower is returned to the evaporator, and the non-volatile distillation residue is extracted through the liquid phase outlet of the evaporator; the outlet gas at the top of the primary distillation tower is condensed in the first-level condenser and the second-level condenser of the primary distillation tower, and the liquid condensed in the second-level condenser of the primary distillation tower is extracted as a low-boiling-point impurity; a part of the liquid condensed in the first-level condenser of the primary distillation tower is returned to the primary distillation tower as reflux, and a part is extracted as a primary distillation product and enters the azeotropic distillation tower; the outlet gas at the top of the azeotropic distillation tower is condensed in the azeotropic distillation tower condenser, and a part of the liquid condensed in the azeotropic distillation tower condenser is returned to the azeotropic distillation tower as reflux, and a part is extracted as a primary distillation product and enters the azeotropic distillation tower. The condensate is cooled by the entrainer cooler, and the cooled condensate enters the entrainer separator. The upper oil phase of the entrainer separator is extracted and recycled, and enters the azeotropic distillation tower together with the supplementary entrainer, and the lower water phase of the entrainer separator is extracted as wastewater; the azeotropic distillation tower uses steam to provide heat load through the azeotropic distillation tower reboiler, and the liquid phase at the bottom outlet of the azeotropic distillation tower enters the finished product recovery tower; the gas at the top outlet of the finished product recovery tower is condensed in the finished product recovery tower condenser, and part of the liquid condensed in the finished product recovery tower condenser is returned to the finished product recovery tower as reflux, and part is extracted as PGME finished product; the finished product recovery tower uses steam to provide heat load through the finished product recovery tower reboiler, and the liquid phase at the bottom outlet of the finished product recovery tower is extracted as PGMEA finished product.

9. The recycling process according to claim 8, wherein: The tops of the primary distillation tower, the azeotropic distillation tower and the finished product recovery tower are all operated under negative pressure.

10. The recycling process according to claim 8, wherein: The operating pressure of the top of the primary distillation tower is -10 to 100 kPa, the top temperature of the primary distillation tower is 80 to 125° C., and the bottom temperature of the primary distillation tower is 85 to 135° C.; The top operating pressure of the azeotropic distillation tower is -10 to 100 kPa, the top temperature of the azeotropic distillation tower is 20 to 90° C., and the bottom temperature of the azeotropic distillation tower is 85 to 140° C.; The top operating pressure of the finished product recovery tower is -10 to 100 kPa, the top temperature of the finished product recovery tower is 70 to 115° C., and the bottom temperature of the finished product recovery tower is 135 to 165° C.

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