Extractive rectification device and waste liquid recovery method

Abstract

The invention relates to an extractive distillation device and a waste liquid recovery method. The extractive distillation device comprises an evaporator, a primary tower, an impurity removal tower, an extractive distillation tower and a product recovery tower which are sequentially communicated through pipelines; the evaporator is provided with a raw material inlet, a first liquid phase inlet, a first liquid phase outlet, a first gas phase outlet, a first steam inlet and a first steam condensate outlet, and the primary distillation tower is provided with a primary distillation gas phase inlet and a primary distillation liquid phase outlet; the first gas phase outlet is communicated with the primary distillation gas phase inlet through a pipeline, the first liquid phase inlet is communicated with the primary distillation liquid phase outlet through a pipeline, and the first liquid phase outlet is used for flowing out impurities. According to the device and the recovery method, MDG and NMF in the waste liquid are further separated by adopting the extraction agent, MDG and NMF products can be respectively recovered, and thus the industrial utilization value of the MDG and NMF mixture is expanded.

Description

Technical Field

[0001] The present invention relates to the field of waste liquid recovery, and particularly to an extractive distillation device and a waste liquid recovery method. Background Art

[0002] In the lithography process of thin film transistor liquid crystal displays (TFT-LCDs) and semiconductor integrated circuits, a stripping solution is required to remove the residual photoresist on the mask. A large amount of waste stripping solution is generated during the photoresist stripping process. The main components of the waste stripping solution are organic solvents, resins, photosensitizers, etc. The organic solvents therein have high recycling value. Traditional harmless treatment processes such as incineration and pyrolysis cannot recycle the organic solvents in the waste stripping solution. Organic solvent-based waste stripping solutions containing high-value substances are usually recovered by distillation processes to obtain high-purity solvent products. The main active components of the stripping solution commonly used in the lithography process of semiconductor enterprises are methyl diglycol (MDG) and N-methylformamide (NMF). The boiling points of MDG and NMF are close. The mixture of MDG and NMF with relatively high purity obtained by traditional distillation processes has limited application scope. For the further separation of mixtures with close boiling points, using traditional distillation methods, the required theoretical number of plates of the distillation column is very high, the equipment manufacturing cost is large, and the economic benefits are limited. Therefore, it is necessary to develop a new process for efficiently recovering MDG and NMF from waste stripping solution by distillation. Summary of the Invention

[0003] Based on this, it is necessary to provide an extractive distillation device and a waste liquid recovery method.

[0004] In a first aspect, the present application provides an extractive distillation device, including an evaporator, a pre-distillation column, an impurity removal column, an extractive distillation column, and a product recovery column connected in sequence through pipelines;

[0005] The evaporator has a raw material inlet, a first liquid phase inlet, a first liquid phase outlet, a first gas phase outlet, a first steam inlet, and a first steam condensate outlet. The pre-distillation column has a pre-distillation gas phase inlet and a pre-distillation liquid phase outlet;

[0006] The first gas phase outlet is connected to the pre-distillation gas phase inlet through a pipeline. The first liquid phase inlet is connected to the pre-distillation liquid phase outlet through a pipeline. The first liquid phase outlet is used to flow out impurities.

[0007] In another aspect, the present application also provides a waste liquid recovery method, using the above extractive distillation device, including the following steps:

[0008] Waste liquid is introduced into the evaporator through the raw material inlet, and the waste liquid is separated into a first gas phase and a first liquid phase.

[0009] The first gas phase is introduced into the prefractionation column through the first gas phase outlet and the prefractionation gas phase inlet, and the first gas phase is separated into a prefractionation intermediate material and a second liquid phase.

[0010] The prefractionation intermediate material is introduced into the impurity removal column, and the prefractionation intermediate material is separated into an impurity removal intermediate material and a first impurity.

[0011] The impurity removal intermediate material is introduced into the extractive distillation column, and the impurity removal intermediate material is separated into a distillation intermediate material and a first product, and the first product is collected.

[0012] The distillation intermediate material is introduced into the product recovery column, and the distillation intermediate material is separated into a second product and a third liquid phase, and the second product is collected.

[0013] In this application, by configuring an evaporator, a prefractionation column, an impurity removal column, an extractive distillation column, and a product recovery column, the raw material waste stripping liquid separates evaporation residues in the evaporator, and then recovers the prefractionation product in the prefractionation column. The low-boiling impurities in the prefractionation product are removed in the impurity removal column. In the extractive distillation column, an extractant is used to separate MDG and NMF from the waste liquid after impurity removal. The MDG product is taken out from the top of the extractive distillation column. The mixture of the extractant and NMF enters the product recovery column, and the NMF product is recovered from the top of the NMF product recovery column. The extractant taken out from the bottom of the product recovery column is recycled and returned to the extractive distillation column together with the supplementary extractant. The separated evaporation residues are further treated by incineration, and the separated low-boiling impurities are further treated by biochemical or incineration processes. By using an extractant to further separate MDG and NMF in the waste liquid, the device and production process can respectively recover MDG and NMF products, thus broadening the industrial utilization value of the MDG and NMF mixture. Description of the Drawings

[0014] Figure 1 It is a schematic structural diagram of an extractive distillation device for an embodiment.

[0015] The descriptions of the reference numerals are as follows:

[0016] 1. Evaporator; 2. Prefractionation column; 3. Prefractionation column condenser; 4. Impurity removal column; 5. Impurity removal column reboiler; 6. Impurity removal column condenser; 7. Extractive distillation column; 8. Extractive distillation column reboiler; 9. Extractive distillation column condenser; 10. Product recovery column; 11. Product recovery column reboiler; 12. Product recovery column condenser. Detailed Embodiments

[0017] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used herein in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0019] As Figure 1 shown, in a first aspect, the present embodiment provides an extractive distillation device, which includes an evaporator 1, a preliminary distillation column 2, an impurity removal column 4, an extractive distillation column 7, and a product recovery column 10 that are connected in sequence through pipelines;

[0020] The evaporator 1 has a raw material inlet, a first liquid phase inlet, a first liquid phase outlet, a first gas phase outlet, a first steam inlet, and a first steam condensate outlet, and the preliminary distillation column 2 has a preliminary distillation gas phase inlet and a preliminary distillation liquid phase outlet;

[0021] The first gas phase outlet is connected to the preliminary distillation gas phase inlet through a pipeline, the first liquid phase inlet is connected to the preliminary distillation liquid phase outlet through a pipeline, and the first liquid phase outlet is used to flow out impurities.

[0022] In one embodiment, it further includes a preliminary distillation column condenser 3, and the preliminary distillation column condenser 3 includes a second gas phase inlet and a second liquid phase outlet;

[0023] The preliminary distillation column 2 further has a preliminary distillation reflux port and a preliminary distillation gas phase outlet provided at its top, and the preliminary distillation gas phase outlet is connected to the second gas phase inlet through a pipeline; the second liquid phase outlet is connected to the preliminary distillation reflux port and the impurity removal column 4 respectively through pipelines.

[0024] Optionally, the preliminary distillation column 2, the impurity removal column 4, the extractive distillation column 7, and the product recovery column 10 can be either plate columns or packed columns.

[0025] In one embodiment, the preliminary distillation liquid phase outlet is provided at the bottom of the preliminary distillation column 2.

[0026] In one embodiment, the evaporator 1 is one of a scraping evaporator, a thin film evaporator, and a tubular evaporator.

[0027] In one embodiment, it further includes an impurity removal tower condenser 6, and the impurity removal tower condenser 6 includes a third gas phase inlet and a third liquid phase outlet;

[0028] The impurity removal tower 4 further has an impurity removal reflux port and an impurity removal gas phase outlet provided at its top. The impurity removal gas phase outlet is communicated with the third gas phase inlet through a pipeline; the third liquid phase outlet is communicated with the impurity removal tower reflux port through a pipeline, and an impurity extraction outlet is further provided at the third liquid phase outlet.

[0029] In one embodiment, the extractive distillation device further includes an impurity removal tower reboiler 5; wherein, the impurity removal tower 4 is circularly communicated with the impurity removal tower reboiler 5 through a pipeline, and the impurity removal tower reboiler 5 further has a second steam inlet and a second steam condensate outlet;

[0030] An impurity removal liquid phase outlet is further provided at the bottom of the impurity removal tower 4, and the impurity removal liquid phase outlet is communicated with the extractive distillation tower 7 through a pipeline.

[0031] In one embodiment, the extractive distillation device further includes an extractive distillation tower condenser 9 and an extractive distillation tower reboiler 8. The extractive distillation tower condenser 9 includes a fourth gas phase inlet and a fourth liquid phase outlet; wherein,

[0032] The extractive distillation tower 7 further has an extractive distillation reflux port and an extractive distillation gas phase outlet provided at its top. The extractive distillation gas phase outlet is communicated with the fourth gas phase inlet through a pipeline, the fourth liquid phase outlet is communicated with the extractive distillation reflux port, and a first product extraction outlet is further provided at the fourth liquid phase outlet;

[0033] The extractive distillation tower 7 is circularly communicated with the extractive distillation tower reboiler 8 through a pipeline, and the extractive distillation tower reboiler 8 is further communicated with a third steam inlet and a third steam condensate outlet;

[0034] An extractive distillation liquid phase outlet is further provided at the bottom of the extractive distillation tower 7, and the extractive distillation liquid phase outlet is communicated with the product recovery tower 10 through a pipeline.

[0035] In one embodiment, the extractive distillation device further includes a product recovery tower condenser 12 and a product recovery tower reboiler 11. The product recovery tower condenser 12 includes a fifth gas phase inlet and a fifth liquid phase outlet; wherein,

[0036] The product recovery tower 10 further has a product recovery reflux port and a product recovery gas phase outlet provided at its top,

[0037] The product recovery gas phase outlet is communicated with the fifth gas phase inlet through a pipeline, the fifth condenser liquid phase outlet is communicated with the product recovery reflux port, and a second product extraction outlet is further provided at the fifth liquid phase outlet;

[0038] The product recovery column 10 and the product recovery column reboiler 11 are connected in a circulating pipeline, and the product recovery column reboiler 11 is also connected with a fourth steam inlet and a fourth steam condensate outlet;

[0039] The bottom of the product recovery column 10 is also provided with a product recovery liquid phase outlet, and the extractive distillation column 7 is also provided with a main extractant inlet, and the product recovery liquid phase outlet is communicated with the main extractant inlet;

[0040] The main extractant inlet is also provided with a supplementary extractant inlet.

[0041] As Figure 1 shown, in a second aspect, the present embodiment provides a waste liquid recovery method, which adopts the above extractive distillation device and includes the following steps:

[0042] Waste liquid is introduced into the evaporator 1, and the waste liquid is separated into a first gas phase and a first liquid phase;

[0043] The first gas phase is introduced into the prefractionating column 2, and the first gas phase is separated into a prefractionation intermediate material and a second liquid phase;

[0044] The prefractionation intermediate material is introduced into the impurity removal column 4, and the prefractionation intermediate material is separated into an impurity removal intermediate material and a first impurity;

[0045] The impurity removal intermediate material is introduced into the extractive distillation column 7, and the impurity removal intermediate material is separated into a rectification intermediate material and a first product, and the first product is collected;

[0046] The rectification intermediate material is introduced into the product recovery column 10, and the rectification intermediate material is separated into a second product and a third liquid phase, and the second product is collected.

[0047] In one embodiment, at least one of the prefractionating column 2, the impurity removal column 4, the extractive distillation column 7, and the product recovery column 10 is under negative pressure.

[0048] In one embodiment, the first liquid phase flows out through the first liquid phase outlet.

[0049] It can be understood that the first liquid phase is the non-volatile evaporation residue in the evaporator 1.

[0050] In one embodiment, at least part of the second liquid phase is introduced into the evaporator 1 through the prefractionation liquid phase outlet and the first liquid phase inlet.

[0051] In one embodiment, the extractive distillation device further includes a prefractionating column condenser 3 connected to the prefractionating column 2, and the step of separating the first gas phase into a prefractionation intermediate material and a second liquid phase includes:

[0052] The first gas phase is separated in the debutanizer 2 to form a first intermediate gas phase and a first intermediate liquid phase;

[0053] The first intermediate gas phase enters the debutanizer condenser 3, and at least part of the first intermediate gas phase is separated to form an intermediate material in the debutanizer, and the remaining first intermediate gas phase forms the second liquid phase and returns to the debutanizer 2.

[0054] It can be understood that the first intermediate gas phase enters the debutanizer condenser 3 through the debutanizer gas phase outlet of the debutanizer 2 and the second gas phase inlet of the debutanizer condenser 3. A part of the liquid phase condensed from the first intermediate gas phase forms an intermediate material in the debutanizer and enters the debutanizer 2 through the second liquid phase outlet, and enters the purification column 4 through the debutanizer liquid phase outlet, and the other part forms the second liquid phase and enters the debutanizer 2 through the second liquid phase outlet and the debutanizer reflux port.

[0055] In one embodiment, the extractive distillation device further includes a purification column condenser 6 communicated with the purification column 4. The intermediate material in the debutanizer enters the purification column 4. The steps of separating the intermediate material in the debutanizer into a purified intermediate material and a first impurity include:

[0056] The intermediate material in the debutanizer enters the purification column 4 through the debutanizer liquid phase outlet;

[0057] The intermediate material in the debutanizer is separated in the purification column 4 into a second intermediate gas phase and a second intermediate liquid phase;

[0058] The second intermediate gas phase enters the purification column condenser 6, and at least part of the second intermediate gas phase is separated to form a purified intermediate material and returns to the purification column 4, and the remaining second intermediate gas phase forms the first impurity.

[0059] It can be understood that the second intermediate gas phase enters the purification column condenser 6 through the purification column gas phase outlet of the purification column 4 and the third gas phase inlet of the purification column condenser 6. A part of the liquid phase condensed from the second intermediate gas phase forms a purified intermediate material and enters the purification column 4 through the third liquid phase outlet and the purification column reflux port, and the other part is the first impurity with a low boiling point, which is discharged through the second liquid phase outlet and the impurity extraction port.

[0060] Furthermore, the purification column 4 is further provided with a purification column reboiler 5. The purification column 4 is circularly communicated with the purification column reboiler 5 through a pipeline. The purification column reboiler 5 further has a second steam inlet and a second steam condensate outlet. The purification column 4 uses steam to provide heat load through the purification column reboiler 5.

[0061] In one embodiment, the extractive distillation device further includes an extractive distillation column condenser 9 connected to the extractive distillation column 7. A liquid outlet is further provided at the bottom of the impurity removal column 4. The step of separating the impurity removal intermediate material into a rectification intermediate material and a first product includes:

[0062] The impurity removal intermediate material is introduced into the extractive distillation column 7 through the liquid outlet of the impurity removal column;

[0063] The impurity removal intermediate material forms a third intermediate gas phase in the extractive distillation column 7;

[0064] The third intermediate gas phase is introduced into the extractive distillation column condenser 9. At least part of the third intermediate gas phase is separated to form a rectification intermediate material and is refluxed into the extractive distillation column 7, and the remaining third intermediate gas phase forms the first product.

[0065] It can be understood that the third intermediate gas phase enters the extractive distillation column condenser 9 through the extractive distillation gas outlet of the extractive distillation column 7 and the fourth gas inlet of the extractive distillation column condenser 9. Part of the liquid phase condensed from the third intermediate gas phase forms a rectification intermediate material, enters the extractive distillation column 7 through the fourth liquid outlet and the extractive distillation reflux port, and is introduced into the product recovery column 10 through the extractive distillation liquid outlet. The other part of the liquid phase is taken out as the first product (such as: diethylene glycol monomethyl ether MDG).

[0066] Furthermore, the extractive distillation column 7 is further provided with an extractive distillation column reboiler 8. The extractive distillation column 7 and the extractive distillation column reboiler 8 are connected in a circulating pipeline. The extractive distillation column reboiler 8 further has a third steam inlet and a third steam condensate outlet. The extractive distillation column 7 uses steam to provide heat load through the extractive distillation column reboiler 8.

[0067] In one embodiment, the extractive distillation device further includes a product recovery column condenser 12 connected to the product recovery column 10. A liquid outlet is further provided at the bottom of the extractive distillation column 7. The step of separating the rectification intermediate material into a second product includes:

[0068] The rectification intermediate material is introduced into the product recovery column 10 through the extractive distillation liquid outlet;

[0069] The rectification intermediate material forms a fourth intermediate gas phase in the product recovery column 10;

[0070] The fourth intermediate gas phase is introduced into the product recovery column condenser 12. At least part of the fourth intermediate gas phase forms the second product, and the remaining fourth intermediate gas phase forms a third liquid phase and is refluxed into the product recovery column 10.

[0071] It is understandable that the fourth intermediate gas phase enters the product recovery condenser 12 through the product recovery gas phase outlet of the product recovery column 10 and the fifth gas phase inlet of the product recovery condenser 12. A part of the liquid phase condensed from the fourth intermediate gas phase forms a second product (e.g., N-methylformamide NMF), which is withdrawn through the fifth liquid phase outlet and the second product withdrawal port; another part of the liquid phase is the third liquid phase, which enters the product recovery column 10 through the fifth liquid phase outlet and the product recovery reflux port.

[0072] Furthermore, the product recovery column 10 is also provided with a product recovery column reboiler 11. The product recovery column 10 and the product recovery column reboiler 11 are connected in a circulating manner through a pipeline. The product recovery column reboiler 11 also has a fourth steam inlet and a fourth steam condensate outlet. The product recovery column 10 uses steam to provide heat load through the product recovery column reboiler 11.

[0073] In one embodiment, the step of introducing the impurity removal intermediate material into the extractive distillation column 7 further includes: providing an extraction material to the impurity removal intermediate material.

[0074] Furthermore, the step of providing an extraction material to the impurity removal intermediate material includes: introducing a supplementary extractant into the extractive distillation column 7; and / or

[0075] introducing the third liquid phase in the product recovery column 10 into the extractive distillation column 7.

[0076] Optionally, the supplementary extractant is at least one of benzene, toluene, heptanoic acid, 1,3-propanediol, 1,4-butanediol, triethylene glycol, NMP, sulfolane, and glycerol.

[0077] It is understandable that the third liquid phase contains the extractant added to the extractive distillation column in the foregoing steps, and enters the extractive distillation column 7 through the product recovery liquid phase outlet and the main extractant inlet; the main extractant inlet is also provided with a supplementary extractant inlet, and the supplementary extractant enters the extractive distillation column 7 through the supplementary extractant inlet and the main extractant inlet; preferably, the supplementary extractant is glycerol.

[0078] In one embodiment, the top operating pressure of the prefractionator 2 is -10 to 100 kPa, the top temperature is 135 to 180 °C, and the bottom temperature is 150 to 215 °C.

[0079] In one embodiment, the top operating pressure of the impurity removal column 4 is -10 to 100 kPa, the top temperature is 40 to 75 °C, and the bottom temperature is 135 to 185 °C.

[0080] In one embodiment, the top operating pressure of the extractive distillation column 7 is -10 to 100 kPa, the top temperature is 50 to 155 °C, and the bottom temperature is 115 to 165 °C.

[0081] In one embodiment, the top operating pressure of the product recovery column 10 is -10 to 100 kPa, the top temperature is 140 to 165 °C, and the bottom temperature is 220 to 265 °C.

[0082] In the extractive distillation device and waste liquid recovery method of this embodiment, by configuring an evaporator 1, a pre-distillation column 2, an impurity removal column 4, an extractive distillation column 7, and a product recovery column 10, the raw material waste liquid separates out evaporation residues in the evaporator 1, and then the pre-distillation products are recovered in the pre-distillation column 2. The low-boiling impurities in the pre-distillation products are removed in the impurity removal column 4. The waste stripping liquid after impurity removal is separated from MDG and NMF by an extractant in the extractive distillation column 7. The MDG product is taken out from the top of the extractive distillation column 7. The mixture of the extractant and NMF enters the product recovery column 10, and the NMF product is recovered from the top of the product recovery column 10. The extractant taken out from the bottom of the product recovery column 10 is recycled and returned to the extractive distillation column 7 together with the supplementary extractant. The separated evaporation residues are further treated by incineration, and the separated low-boiling impurities are further treated by biochemical or incineration processes. By using an extractant to further separate MDG and NMF in the waste stripping liquid, the device and production process can respectively recover MDG and NMF products, thus broadening the industrial utilization value of the MDG and NMF mixture.

[0083] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0084] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. An extractive distillation device, characterized in that: It includes an evaporator, a primary distillation tower, an impurity removal tower, an extractive distillation tower and a product recovery tower which are sequentially connected through pipelines; The evaporator has a raw material inlet, a first liquid phase inlet, a first liquid phase outlet, a first gas phase outlet, a first steam inlet and a first steam condensate outlet, and the primary distillation tower has a primary distillation gas phase inlet and a primary distillation liquid phase outlet; The first gas phase outlet is connected to the primary distillation gas phase inlet through a pipeline, the first liquid phase inlet is connected to the primary distillation liquid phase outlet through a pipeline, and the first liquid phase outlet is used to flow out impurities.

2. The extractive distillation device according to claim 1, characterized in that: Also included is a primary distillation tower condenser, the primary distillation tower condenser comprising a second gas phase inlet and a second liquid phase outlet; The primary distillation tower also has a primary distillation reflux port and a primary distillation gas phase outlet disposed at the top thereof, wherein the primary distillation gas phase outlet is connected to the second gas phase inlet via a pipeline; the second liquid phase outlet is connected to the primary distillation reflux port and the impurity removal tower via pipelines respectively; and / or The initial distillation liquid phase outlet is arranged at the bottom of the initial distillation tower; and / or The evaporator is one of a scraper evaporator, a thin film evaporator and a tubular evaporator.

3. The extractive distillation device according to claim 1, characterized in that: Also included is a impurity removal tower condenser, the impurity removal tower condenser comprising a third gas phase inlet and a third liquid phase outlet; The impurity removal tower also has an impurity removal reflux port and an impurity removal gas phase outlet arranged at the top thereof, and the impurity removal gas phase outlet is connected to the third gas phase inlet through a pipeline; the third liquid phase outlet is connected to the impurity removal tower reflux port through a pipeline, and the third liquid phase outlet is also provided with an impurity collection port.

4. The extractive distillation device according to claim 3, characterized in that: It also includes a reboiler for an impurity removal tower; wherein the impurity removal tower is in circular communication with the reboiler for the impurity removal tower through a pipeline, and the reboiler for the impurity removal tower also has a second steam inlet and a second steam condensate outlet; The bottom of the impurity removal tower is also provided with an impurity removal liquid phase outlet, and the impurity removal liquid phase outlet is connected to the extractive distillation tower through a pipeline.

5. The extractive distillation device according to claim 1, characterized in that: It also includes an extractive distillation tower condenser and / or an extractive distillation tower reboiler, wherein the extractive distillation tower condenser includes a fourth gas phase inlet and a fourth liquid phase outlet; wherein, The extractive distillation tower also has an extractive distillation reflux port and an extractive distillation gas phase outlet provided at the top thereof, the extractive distillation gas phase outlet is connected to the fourth gas phase inlet through a pipeline, the fourth liquid phase outlet is connected to the extractive distillation reflux port, and the fourth liquid phase outlet is also provided with a first product production port; The extractive distillation tower is cyclically connected to the extractive distillation tower reboiler through a pipeline, and the extractive distillation tower reboiler is also connected to a third steam inlet and a third steam condensate outlet; An extraction and rectification liquid phase outlet is also provided at the bottom of the extraction and rectification tower, and the extraction and rectification liquid phase outlet is connected with the product recovery tower through a pipeline.

6. The extractive distillation device according to claim 5, characterized in that: It also includes a product recovery tower condenser and / or a product recovery tower reboiler, wherein the product recovery tower condenser includes a fifth gas phase inlet and a fifth liquid phase outlet; wherein, The product recovery tower also has a product recovery reflux port and a product recovery gas phase outlet at the top thereof. The product recovery gas phase outlet is connected to the fifth gas phase inlet through a pipeline, the fifth condenser liquid phase outlet is connected to the product recovery reflux port, and the fifth liquid phase outlet is also provided with a second product extraction port; The product recovery tower is cyclically connected to the product recovery tower reboiler through a pipeline, and the product recovery tower reboiler is also connected to a fourth steam inlet and a fourth steam condensate outlet; and / or The bottom of the product recovery tower is also provided with a product recovery liquid phase outlet, and the extractive distillation tower is also provided with a main extractant inlet, and the product recovery liquid phase outlet is connected to the main extractant inlet; The main extractant inlet is also provided with a supplementary extractant inlet.

7. A waste liquid recovery method, characterized in that: The extractive distillation device according to any one of claims 1 to 6 comprises the following steps: The waste liquid is introduced into the evaporator through the raw material inlet, and the waste liquid is separated into a first gas phase and a first liquid phase; The first gas phase is introduced into the primary distillation tower through the first gas phase outlet and the primary distillation gas phase inlet, and the first gas phase is separated to form a primary distillation intermediate material and a second liquid phase; The initially distilled intermediate material is passed into the impurity removal tower, and the initially distilled intermediate material is separated into impurity-removed intermediate material and first impurities; The impurity-removed intermediate material is passed into the extractive distillation tower, the impurity-removed intermediate material is separated into a distillation intermediate material and a first product, and the first product is collected; The distillation intermediate material is introduced into the product recovery tower, the distillation intermediate material is separated to form a second product and a third liquid phase, and the second product is collected.

8. The waste liquid recovery method according to claim 7, characterized in that: The method includes at least one of the following features: (1) At least one of the primary distillation tower, the impurity removal tower, the extractive distillation tower and the product recovery tower is under negative pressure; (2) the first liquid phase flows out through the first liquid phase outlet; (3) at least a portion of the second liquid phase is introduced into the evaporator through the initial liquid phase outlet and the first liquid phase inlet; (4) The extractive distillation device further comprises a primary distillation tower condenser connected to the primary distillation tower, and the step of separating the first gas phase to form a primary distillation intermediate material and a second liquid phase comprises: The first gas phase is separated in the primary distillation tower to form a first intermediate gas phase and a first intermediate liquid phase; The first intermediate gas phase is introduced into the condenser of the primary distillation tower, at least a portion of the first intermediate gas phase is separated to form a primary distillation intermediate material, and the rest of the first intermediate gas phase is formed into the second liquid phase and refluxed into the primary distillation tower; (5) The extractive distillation device further comprises a decontamination tower condenser connected to the decontamination tower, the initial distillation intermediate material is introduced into the extractive distillation tower, and the step of separating the initial distillation intermediate material into the decontamination intermediate material and the first impurity comprises: The intermediate material of the primary distillation is introduced into the impurity removal tower through the primary distillation liquid phase outlet; The first distillation intermediate material is separated into a second intermediate gas phase and a second intermediate liquid phase in the impurity removal tower; The second intermediate gas phase is introduced into the impurity removal tower condenser, at least a portion of the second intermediate gas phase is separated to form an impurity removal intermediate material which is refluxed into the impurity removal tower, and the rest of the second intermediate gas phase forms the first impurity; (6) The extractive distillation device further comprises an extractive distillation tower condenser connected to the extractive distillation tower, and the bottom of the impurity removal tower is further provided with an impurity removal liquid phase outlet, and the impurity removal intermediate material is introduced into the extractive distillation tower, and the step of separating the impurity removal intermediate material into a distillation intermediate material and a first product comprises: The impurity-removed intermediate material is introduced into the extractive distillation tower through the impurity-removed liquid phase outlet; The impurity-removed intermediate material forms a third intermediate gas phase in the extractive distillation tower; The third intermediate gas phase is introduced into the condenser of the extractive distillation column, at least a part of the third intermediate gas phase is separated to form a distillation intermediate material which is refluxed into the extractive distillation column, and the rest of the third intermediate gas phase forms the first product; (7) The extractive distillation device further comprises a product recovery tower condenser connected to the product recovery tower, and the bottom of the extractive distillation tower is further provided with an extractive distillation liquid phase outlet, and the step of separating the distillation intermediate material to form the second product comprises: The distillation intermediate material is introduced into the product recovery tower through the extractive distillation liquid phase outlet; The distillation intermediate material forms a fourth intermediate gas phase in the product recovery tower; The fourth intermediate gas phase is introduced into the condenser of the product recovery tower, at least a portion of the fourth intermediate gas phase forms the second product, and the rest of the fourth intermediate gas phase forms the third liquid phase and refluxes into the product recovery tower.

9. The waste liquid recovery method according to claim 8, characterized in that: The method comprises at least one of the following features: (1) The step of introducing the impurity-removed intermediate material into the extractive distillation tower further comprises: providing extraction material to the impurity-removed intermediate material; (2) The operating pressure of the top of the primary distillation tower is -10 to 100 kPa, the top temperature is 135 to 180° C., and the bottom temperature is 150 to 215° C.; (3) The top operating pressure of the impurity removal tower is -10 to 100 kPa, the top temperature is 40 to 75° C., and the bottom temperature is 135 to 185° C.; (4) The top operating pressure of the extractive distillation tower is -10 to 100 kPa, the top temperature is 50 to 155° C., and the bottom temperature is 115 to 165° C.; (5) The top operating pressure of the NMF product recovery tower is -10 to 100 kPa, the top temperature is 140 to 165° C., and the bottom temperature is 220 to 265° C.; (6) The impurity removal tower condenser is also provided with an impurity extraction port, and the first impurity is discharged through the impurity extraction port.

10. The waste liquid recovery method according to claim 9, characterized in that: The step of providing the extraction material to the impurity-removed intermediate material comprises: introducing a supplementary extractant into the extractive distillation tower; and / or Passing the third liquid phase in the product recovery tower into the extractive distillation tower; Optionally, the supplementary extractant is at least one of benzene, toluene, heptanoic acid, 1,3-propylene glycol, 1,4-butanediol, triethylene glycol, NMP, cyclopentane sulfone and glycerol.

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