Energy-saving DMAC (dimethylacetamide) refining system

Abstract

The utility model provides an energy-saving DMAC (dimethylacetamide) refining system which comprises a dehydration system and a rectification system which are connected in series, and the dehydration system is used for removing light components in a prepared DMAC solution; the rectification system is used for removing heavy components in the prepared DMAC solution; the heat exchanger is provided with a first inlet and a first outlet which are communicated, and a second inlet and a second outlet which are communicated; the first inlet is used for introducing a prepared DMAC solution, and the first outlet is used for introducing the prepared DMAC solution into the dehydration system; the second inlet is used for introducing DMAC steam separated from the top of the rectification system into the heat exchanger, and the second outlet is used for discharging liquid after heat exchange and condensation of the DMAC steam through the heat exchanger. The heat exchange between the prepared DMAC solution and the DMAC steam separated from the rectification system can be realized through the heat exchanger, additional heating equipment and refrigerating equipment are not needed, and the DMAC refining cost and energy consumption can be obviously reduced.

Description

Technical Field

[0001] The present application relates to the technical field of DMAC refining, and in particular to an energy-saving DMAC refining system. Background Art

[0002] N-Dimethylacetamide (DMAC) is an organic compound mainly used as a solvent for synthetic fiber (acrylonitrile) and polyurethane spinning and synthetic polyamide resin.

[0003] In spandex production, DMAC is used as a solvent to dissolve prepolymers and disperse auxiliary materials in the polymerization stage. In the dry spinning process, DMAC evaporates at high temperatures and is collected and refined to remove impurities such as water, amines, and acetic acid in the solvent DMAC. It is then used as a solvent in spandex production.

[0004] The existing DMAC solvent recovery and refining system consists of two tower systems. The first tower is a dehydration tower, which is mainly used to remove light components such as water and amines in the DMAC solvent. The second tower is a distillation tower, which is mainly used to remove heavy components such as acetic acid and acetic acid compounds in the DMAC solvent, and finally the qualified DMAC solvent is extracted from the middle and upper side lines of the distillation tower.

[0005] The current DMAC refining process is to heat the DMAC solution collected after spandex production to 60-70°C in a storage tank through a coil in the storage tank with low-pressure steam, and send it to a dehydration tower. Light components such as water and amines are removed from the top of the tower, and the bottom liquid is sent to a distillation tower. The high-temperature gaseous DMAC at the top of the distillation tower passes through a condenser and is cooled by cooling water to turn it into a liquid state. The heat taken away by the cooling water requires professional refrigeration equipment to consume electricity for cooling, and the heat and electricity losses are very large. Utility Model Content

[0006] The purpose of the present application is to provide an energy-saving DMAC refining system to solve the problem of high energy consumption in the prior art when the high-temperature gaseous DMAC at the top of the distillation tower needs professional refrigeration equipment for cooling and condensing.

[0007] In order to achieve the above-mentioned purpose, the present application provides an energy-saving DMAC refining system, which includes a dehydration system and a distillation system connected in series, the dehydration system is used to remove light components in the prepared DMAC solution; the distillation system is used to remove heavy components in the prepared DMAC solution; and also includes a heat exchanger, the heat exchanger has a first inlet and a first outlet that are connected, and a second inlet and a second outlet that are connected; the first inlet is used to pass the prepared DMAC solution, and the first outlet is used to pass the prepared DMAC solution into the dehydration system; the second inlet is used to pass the DMAC vapor separated at the top of the distillation system into the heat exchanger, and the second outlet is used to discharge the liquid after the DMAC vapor is condensed by heat exchange through the heat exchanger.

[0008] Through this scheme, the channel formed by the connection of the first inlet and the first outlet is used to pass the DMAC solution prepared after recovery from each spandex production process, and the channel formed by the second inlet and the second outlet is used to pass the DMAC steam separated from the distillation system. The heat exchange between the DMAC solution prepared after recovery and the DMAC steam separated from the distillation system can be realized through the heat exchanger, so that there is no need to use a special heating device to heat the DMAC solution prepared after recovery before passing it into the dehydration system, saving heating steam, and there is no need to use a special refrigeration device to cool the DMAC steam separated from the distillation system, saving cooling water. Through this energy-saving DMAC refining system, the DMAC steam separated by the distillation system and the DMAC solution prepared after recovery are exchanged for heat, which can significantly reduce the DMAC refining cost and energy consumption, and has significant economic and environmental benefits.

[0009] As an option of the dehydration system of the present application, the dehydration system includes: a dehydration tower; a DMAC feed port located in the middle of the dehydration tower; a dehydration tower bottom reboiler connected to the bottom of the dehydration tower to form a bottom material loop; a dehydration tower top cooler connected to the light component outlet at the top of the dehydration tower; a first condensate tank connected to the dehydration tower top cooler; and a heavy component discharge port located at the bottom of the dehydration tower, the heavy component discharge port being connected to the distillation system.

[0010] As an option of the distillation system of the present application, the distillation system includes: a distillation tower; a feed inlet located in the middle of the distillation tower; a reboiler at the bottom of the distillation tower connected to the bottom of the distillation tower to form a bottom material loop; a heavy component outlet located at the bottom of the distillation tower, used to discharge the heavy component impurities separated by distillation; a DMAC steam outlet located at the top of the distillation tower, the DMAC steam outlet is connected to the second inlet of the heat exchanger; a refined DMAC discharge port located above the feed inlet of the distillation tower; and a second condensate tank connected to the second outlet.

[0011] As an option of the present application, a dehydration tower bottom liquid buffer tank is connected between the dehydration system and the distillation system.

[0012] As an option of the present application, a DMAC feed tank is connected between the heat exchanger and the dehydration system.

[0013] As an option of the present application, a DMAC solution recovery buffer tank area and a DMAC mixing tank are set in front of the heat exchanger; the DMAC solution recovery buffer tank area has a number of DMAC tanks for collecting DMAC solutions discharged or recovered from various spandex production processes; each tank in the DMAC solution recovery buffer tank area is connected to the DMAC mixing tank, and the DMAC mixing tank is connected to the DMAC refining system heat exchanger.

[0014] As an improvement of the dehydration system of the present application, the dehydration system further comprises: a dehydration tower top reflux tank connected to the dehydration tower top cooler, the other end of the dehydration tower top reflux tank being connected to the top of the dehydration tower.

[0015] As an improvement of the dehydration system of the present application, the dehydration system also includes: a first cyclone separator connected to the top cooler of the dehydration tower, the bottom of the first cyclone separator is connected to the first condensate tank, and the upper outlet of the first cyclone separator is connected to the first delivery pump.

[0016] As an improvement of the distillation system of the present application, the distillation system further includes: a distillation tower top reflux tank connected to the second outlet, and the other end of the distillation tower top reflux tank is connected to the top of the distillation tower.

[0017] As an improvement of the distillation system of the present application, the distillation system also includes: a second cyclone separator connected to the second outlet, the bottom of the second cyclone separator is connected to the second condensate tank, and the upper outlet of the second cyclone separator is connected to the second delivery pump.

[0018] As an improvement of the distillation system of the present application, the bottom of the reflux tank at the top of the distillation tower is also connected to a first recovery port and a second recovery port. The first recovery port is used to connect to a recovery buffer tank for recovering the DMAC solution before the DMAC refining system and is used for DMAC solution preparation; the second recovery port is used to connect to a pipeline returning to the dehydration tower.

[0019] The beneficial effects of this application are:

[0020] The present application is provided with a heat exchanger, which is used to pass the DMAC solution prepared after recovery and the DMAC steam separated from the top of the distillation system. The heat exchanger can realize the heat exchange between the DMAC solution prepared after recovery and the DMAC steam separated from the distillation system, so that there is no need to use a special heating device to heat the DMAC solution prepared after recovery before passing into the dehydration system, saving heating steam, and there is no need to use a special refrigeration device to cool the DMAC steam separated from the distillation system, saving cooling water. Through this energy-saving DMAC refining system, the DMAC steam separated by the distillation system and the DMAC solution prepared after recovery are heat exchanged, which can significantly reduce the DMAC refining cost and energy consumption, and has significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of an energy-saving DMAC refining system;

[0022] Figure 2 for Figure 1 The enlarged image at a in the middle;

[0023] Description of reference numerals:

[0024] 1. DMAC feed tank; 2. dehydration tower; 3. dehydration tower bottom reboiler; 4. dehydration tower top cooler; 5. dehydration tower top reflux tank; 6. dehydration tower top reflux pump; 7. dehydration tower bottom pump; 8. first condensate tank; 9. first cyclone separator; 10. dehydration tower bottom liquid buffer tank; 11. buffer liquid delivery pump; 12. first condensate pump; 13. first delivery pump; 14. distillation tower; 15. distillation tower top reflux tank; 16. distillation tower bottom reboiler; 18. distillation tower top reflux pump; 19. distillation tower bottom discharge pump; 20. second condensate tank; 21. second condensate pump; 22. second cyclone separator; 23. second delivery pump; 24. heat exchanger; 25. discharge port; 26. first recovery port; 27. second recovery port; 28. DMAC blending tank. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] The inventor of this application proposes an energy-saving DMAC refining system, referring to Figure 1-Figure 2 , Figure 1The schematic diagram of the energy-saving DMAC refining system structure provided in the embodiment of the present application is as follows: Figure 2 The schematic diagram of the connection between the heat exchanger 24 of the energy-saving DMAC refining system and the dehydration system and the distillation system is illustrated. An embodiment of the energy-saving DMAC refining system provided by the present application includes a dehydration system and a distillation system connected in series, the dehydration system is used to remove light components in the prepared DMAC solution; the distillation system is used to remove heavy components in the prepared DMAC solution; and also includes a heat exchanger 24, the heat exchanger 24 has a first inlet 241 and a first outlet 242 that are connected, and a second inlet 243 and a second outlet 244 that are connected; the first inlet 241 is used to pass the prepared DMAC solution, and the first outlet 242 is used to pass the heated prepared DMAC solution into the dehydration system; the second inlet 243 is used to pass the DMAC vapor separated at the top of the distillation system into the heat exchanger 24, and the second outlet 244 is used to discharge the liquid after the DMAC vapor passes through the heat exchanger 24 and is condensed.

[0027] The dehydration system is mainly used to remove light components in the prepared DMAC solution, such as water and amines, etc. The distillation system is used to further remove heavy components in the DMAC solution, such as acetic acid and its compounds.

[0028] like Figure 2 This embodiment does not limit the specific type of heat exchanger 24, and those skilled in the art can choose plate type, plate and shell type, shell and tube type heat exchanger, etc. The heat exchanger has two independent circulation channels, wherein the channel formed by the connection of the first inlet 241 and the first outlet 242 is used to pass the DMAC solution prepared after being discharged and recovered from each spandex production process, and the channel formed by the second inlet 243 and the second outlet 244 is used to pass the DMAC steam separated from the distillation system. The heat exchanger 24 can realize the heat exchange between the prepared DMAC solution and the DMAC steam separated from the distillation system. Specifically, the temperature of the prepared DMAC solution is 20°C-40°C, and the temperature of the DMAC steam just separated from the distillation system is ≥80°C. After the prepared DMAC solution and the DMAC steam separated from the distillation system are both introduced into the heat exchanger 24 for heat exchange, the temperature of the prepared DMAC solution can be raised to 60°C-70°C, and the temperature of the DMAC steam separated from the distillation system is reduced and condensed into liquid, so that there is no need to use a special heating device to heat the prepared DMAC solution before entering the dehydration system, saving heating steam, and there is no need to use a special refrigeration device to cool the DMAC steam separated from the distillation system, saving cooling water. The energy-saving DMAC refining system provided in this embodiment, by introducing a heat exchanger, realizes heat exchange between the DMAC steam separated from the distillation system and the prepared DMAC solution, which can significantly reduce the DMAC refining cost and energy consumption, and has significant economic and environmental benefits.

[0029] Continue to refer to Figure 1 The dehydration system provided in the embodiment of the present application includes: a dehydration tower 2; a DMAC feed port located in the middle of the dehydration tower 2; a dehydration tower bottom reboiler 3 connected to the bottom of the dehydration tower 2 to form a bottom material loop; a dehydration tower top cooler 4 connected to the light component outlet at the top of the dehydration tower 2; a first condensate tank 8 connected to the dehydration tower top cooler 4; and a heavy component discharge port located at the bottom of the dehydration tower 2, and the heavy component discharge port is connected to the distillation system.

[0030] The dehydration tower 2 is used to remove light components in the DMAC solution, such as water and amines. The DMAC feed port is located in the middle of the dehydration tower 2, and is used to receive the DMAC solution prepared after heat exchange by the heat exchanger 24. The dehydration tower bottom reboiler 3 is connected to the bottom of the dehydration tower 2 to form a material loop, heat and gasify the material discharged from the bottom of the dehydration tower 2, provide the heat required for removing the light components, and evaporate the light component substances such as water and amines from the solution to achieve separation. The dehydration tower top cooler 4 is connected to the light component outlet at the top of the dehydration tower 2, and is used to preliminarily cool the light component gas discharged from the top of the tower, reduce its temperature and condense. The first condensate tank 8 is connected to the dehydration tower top cooler 4, and is used to collect and store the light component condensate after cooling and condensation. The heavy component discharge port is located at the bottom of the dehydration tower 2, connected to the distillation system, and is used to transport the material containing the heavy component to the distillation system for further processing. The distillation system is used to remove the heavy components in the DMAC solution, such as acetic acid and its compounds, and finally obtain a high-quality refined DMAC product.

[0031] Specifically, the prepared DMAC solution with a temperature of 60°C-70°C after heat exchange in the heat exchanger 24 enters the middle of the dehydration tower 2 from the DMAC feed port, and the reboiler 3 at the bottom of the dehydration tower heats the DMAC solution to 100°C-105°C, recovers the water and light components such as amines in the DMAC solution and separates them from the DMAC solution, and the light components such as water and amines are passed from the light component outlet at the top of the dehydration tower 2 into the dehydration tower top cooler 4 for condensation, and the condensed product obtained after condensation can reach the first condensate tank 8. The DMAC solution containing heavy components is passed into the distillation system from the heavy component outlet to further remove heavy component impurities such as acetic acid and its compounds in the DMAC solution.

[0032] In an optional embodiment, a DMAC feed tank 1 is connected between the heat exchanger 24 and the dehydration system. The DMAC feed tank 1 is used to cache the DMAC solution entering the dehydration tower 2. In addition, the DMAC feed tank 1 can fine-tune the temperature of the DMAC solution heated by the heat exchanger to meet the requirements of the dehydration system.

[0033] Continue to refer to Figure 1 In an optional embodiment, a recovery buffer tank area of ​​DMAC solution is set before the heat exchanger 24 ( Figure 1The DMAC solution recovery and buffer tank area has several DMAC tanks for collecting the DMAC solution discharged or recovered from each spandex production process. Each DMAC tank can be equipped with monitoring equipment such as a level gauge, a thermometer, and a pressure gauge to grasp the status of the DMAC in the tank in real time. Each tank in the DMAC solution recovery and buffer tank area is connected to the DMAC blending tank, which is connected to the DMAC refining system heat exchanger.

[0034] Continue to refer to Figure 1 The dehydration system further includes: a dehydration tower top reflux tank 5 connected to the dehydration tower top cooler 4, and the other end of the dehydration tower top reflux tank 5 is connected to the top of the dehydration tower 2. The dehydration tower top reflux tank 5 is used to collect the condensate flowing out of the dehydration tower top cooler 4, which is mainly a mixture of light components such as DMAC, water, and amines. By controlling the flow rate of the dehydration tower top reflux pump 6, part of the condensate is refluxed to the top of the dehydration tower 2. The refluxed condensate can keep the temperature in the dehydration tower stable and improve the dehydration effect.

[0035] Continue to refer to Figure 1 The dehydration system also includes: a first cyclone separator 9 connected to the dehydration tower top cooler 4, the bottom of the first cyclone separator 9 is connected to the first condensate tank 8, and the upper outlet of the first cyclone separator 9 is connected to the first delivery pump 13.

[0036] The cyclone separator is a common gas-solid separation device used to separate solid particles or liquid droplets from the gas. In the dehydration part of the DMAC refining system, the first cyclone separator 9 separates solid particles or condensed liquid droplets from the gas. When the cooled gas enters the first cyclone separator 9, due to the special structure inside the cyclone separator, the gas forms a rotating flow field in the separator. During the rotation process, the solid particles, amines, and water formed by condensation are thrown to the inner wall of the cyclone separator due to inertia, and slide down along the inner wall under the action of gravity, and finally fall to the bottom of the separator, and finally enter the first condensate tank 8, while the gas is discharged from the upper outlet of the cyclone separator under the action of the first delivery pump 13.

[0037] Continue to refer to Figure 1 The distillation system includes: a distillation tower 14; a feed inlet located in the middle of the distillation tower 14; a distillation tower bottom reboiler 16 connected to the bottom of the distillation tower 14 to form a bottom material loop; a heavy component outlet located at the bottom of the distillation tower 14, used to discharge the heavy component impurities separated by distillation; a DMAC steam outlet located at the top of the distillation tower 14, the DMAC steam outlet is connected to the second inlet 243 of the heat exchanger 24; a refined DMAC discharge port 25 located above the feed inlet of the distillation tower 14; and a second condensate tank 20 connected to the second outlet 244.

[0038] The distillation tower 14 has multiple sections of fillers or trays to provide sufficient vapor-liquid contact area and mass transfer and heat transfer conditions. The feed port is located in the middle of the distillation tower 14 to receive the DMAC solution transported from the dehydration system. The bottom reboiler 16 of the distillation tower is connected to the bottom of the distillation tower 14 to form a material loop, and the bottom material is heated by the bottom reboiler 16 of the distillation tower to evaporate the heavy components in the DMAC solution. The heavy component outlet at the bottom of the distillation tower 14 is used to discharge the heavy component impurities such as acetic acid and acetic acid compounds separated by distillation, and these heavy component impurities are discharged to the outside of the distillation tower 14 through the bottom discharge pump 19 of the distillation tower. The DMAC steam outlet is located at the top of the distillation tower 14 to discharge the DMAC steam generated during the distillation process. The outlet is connected to the second inlet 243 of the heat exchanger 24 to realize the recovery of heat. The refined DMAC discharge port 25 is located at an appropriate position above the feed port of the distillation tower 14 to collect and output the high-quality DMAC product after distillation treatment. The second condensate tank 20 is connected to the second outlet 244 of the heat exchanger 24 for collecting and storing the condensed DMAC liquid, which can be further processed or directly reused.

[0039] Specifically, the temperature of the DMAC solution after dehydration treatment from the dehydration system reaches above 100° C., and the DMAC solution enters the distillation tower 14 from the feed port in the middle of the distillation tower 14. The distillation tower bottom reboiler 16 at the bottom of the distillation tower 14 further heats the DMAC solution, and through the multiple sections of fillers or trays in the distillation tower 14, sufficient vapor-liquid contact area and mass transfer and heat transfer conditions are provided, so that the heavy component impurities such as acetic acid and acetic acid compounds in the dehydrated DMAC solution are distilled and separated, and the heavy component impurities such as acetic acid and acetic acid compounds after distillation and separation are discharged through the heavy component outlet at the bottom of the distillation tower 14 using the distillation tower bottom discharge pump 19. The refined DMAC solution from which heavy components such as acetic acid and acetic acid compounds are removed is discharged from the refined DMAC discharge port 25, and the DMAC vapor vaporized in the distillation tower 14 enters the heat exchanger 24 through the DMAC vapor outlet at the top of the distillation tower 14. In the heat exchanger 24, the high-temperature DMAC vapor exchanges heat with the low-temperature DMAC solution, and then the high-temperature DMAC vapor is condensed into liquid and enters the second condensate tank 20, thereby realizing the recovery of the DMAC condensate.

[0040] Continue to refer to Figure 1 The distillation system further comprises: a reflux tank 15 at the top of the distillation tower connected to the second outlet 244, and the other end of the reflux tank 15 at the top of the distillation tower is connected to the top of the distillation tower 14. The reflux tank 15 at the top of the distillation tower is used for the DMAC condensate formed after heat exchange, and part or all of it is refluxed to the top of the distillation tower as needed. The temperature of the tower top can be controlled by the reflux liquid. The reflux pipe can be equipped with a flow meter, a control valve and a reflux pump 18 at the top of the distillation tower to accurately control the reflux amount.

[0041] Continue to refer to Figure 1 The bottom of the reflux tank 15 at the top of the distillation tower is also connected to a first recovery port 26 and a second recovery port 27. The first recovery port is used to connect to a recovery buffer tank for recovering the DMAC solution before the DMAC refining system and is used for preparing the DMAC solution; the second recovery port 27 is used to connect to a pipeline returning to the dehydration tower 2.

[0042] Continue to refer to Figure 1 The distillation system further includes: a second cyclone separator 22 connected to the second outlet 244 , the bottom of the second cyclone separator 22 is connected to the second condensate tank 20 , and the upper outlet of the second cyclone separator 22 is connected to the second delivery pump 23 .

[0043] The second cyclone separator 22 is used to separate the DMAC droplets entrained in the gas discharged after condensation by the heat exchanger. When the gas enters the cyclone separator, it rotates due to the centrifugal force generated by the cyclone, and the heavier DMAC droplets will be thrown to the wall of the device, and then fall along the wall into the second condensate tank 20, while the lighter gas will be discharged from the upper outlet under the action of the second delivery pump 23.

[0044] Reference Figure 1 A dehydration tower bottom liquid buffer tank 10 is connected between the dehydration system and the distillation system. The dehydration tower bottom liquid buffer tank 10 is used to collect and store the DMAC solution discharged from the bottom of the dehydration tower 2 of the dehydration system to remove water, amines and other light components. The dehydration tower bottom liquid buffer tank 10 provides a buffer area for the liquid flow between the dehydration tower and the distillation tower, which helps to stabilize the liquid flow and prevent the distillation system from being adversely affected by flow fluctuations. The buffer tank can also be equipped with monitoring equipment such as a level meter and a thermometer so that the operator can monitor the state and properties of the liquid in real time and adjust and control it as needed.

[0045] Unless otherwise defined, the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions. Reference to "embodiments" herein means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application, and the appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0046] In the description of the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "top" and "bottom" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present application and simplifying the description. They do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0047] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "set", "connected", "connection" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the utility model.

Claims

1. An energy-saving DMAC refining system, comprising a dehydration system and a distillation system connected in series, characterized in that: The dehydration system is used to remove light components in the prepared DMAC solution; The distillation system is used to remove heavy components in the prepared DMAC solution; The heat exchanger (24) further comprises a heat exchanger (24), wherein the heat exchanger (24) has a first inlet (241) and a first outlet (242) communicating with each other, and a second inlet (243) and a second outlet (244) communicating with each other; The first inlet (241) is used to introduce the prepared DMAC solution, and the first outlet (242) is used to introduce the prepared DMAC solution into the dehydration system; The second inlet (243) is used to pass the DMAC vapor separated at the top of the distillation system into the heat exchanger (24), and the second outlet (244) is used to discharge the liquid after the DMAC vapor is condensed through heat exchange in the heat exchanger (24).

2. The energy-saving DMAC refining system according to claim 1, characterized in that: The dehydration system comprises: a dehydration tower (2); a DMAC feed port located in the middle of the dehydration tower (2); a dehydration tower bottom reboiler (3) connected to the bottom of the dehydration tower (2) to form a tower bottom material loop; a dehydration tower top cooler (4) connected to the light component outlet at the top of the dehydration tower (2); a first condensate tank (8) connected to the dehydration tower top cooler (4); and a heavy component discharge port located at the bottom of the dehydration tower (2), wherein the heavy component discharge port is connected to the distillation system.

3. The energy-saving DMAC refining system according to any one of claims 1 or 2, characterized in that: The distillation system comprises: a distillation tower (14); a feed inlet located in the middle of the distillation tower (14); a distillation tower bottom reboiler (16) connected to the bottom of the distillation tower (14) to form a bottom material loop; a heavy component outlet located at the bottom of the distillation tower (14) for discharging heavy component impurities separated by distillation; a DMAC steam outlet located at the top of the distillation tower (14), the DMAC steam outlet being connected to a second inlet (243) of the heat exchanger (24); a refined DMAC discharge port (25) located above the feed inlet of the distillation tower (14); and a second condensate tank (20) connected to the second outlet (244).

4. The energy-saving DMAC refining system according to claim 1, characterized in that: A dehydration tower bottom liquid buffer tank (10) is connected between the dehydration system and the distillation system.

5. The energy-saving DMAC refining system according to claim 1 or 2, characterized in that: A DMAC blending tank (28) is provided in front of the refining system; The DMAC blending tank (28) is used to recover and blend the DMAC solution discharged from the spandex production process and recovered from the spinning tunnel; The DMAC preparation tank (28) is connected to the heat exchanger (24).

6. The energy-saving DMAC refining system according to claim 2, characterized in that: The dehydration system further comprises: a dehydration tower top reflux tank (5) connected to the dehydration tower top cooler (4), and the other end of the dehydration tower top reflux tank (5) is connected to the top of the dehydration tower (2).

7. The energy-saving DMAC refining system according to claim 2, characterized in that: The dehydration system further comprises: a first cyclone separator (9) connected to the dehydration tower top cooler (4), the bottom of the first cyclone separator (9) being connected to a first condensate tank (8), and the upper outlet of the first cyclone separator (9) being connected to a first delivery pump (13).

8. The energy-saving DMAC refining system according to claim 3, characterized in that: The distillation system further comprises: a distillation tower top reflux tank (15) connected to the second outlet (244), and the other end of the distillation tower top reflux tank (15) is connected to the top of the distillation tower (14).

9. The energy-saving DMAC refining system according to claim 3, characterized in that: The distillation system further comprises: a second cyclone separator (22) connected to the second outlet (244), the bottom of the second cyclone separator (22) is connected to the second condensate tank (20), and the upper outlet of the second cyclone separator (22) is connected to a second delivery pump (23).

10. The energy-saving DMAC refining system according to claim 8, characterized in that: The bottom of the reflux tank (15) at the top of the distillation tower is also connected to a first recovery port (26) and a second recovery port (27). The first recovery port (26) is used to connect to a recovery buffer tank for recovering DMAC solution before the DMAC refining system and is used for preparing the DMAC solution; the second recovery port (27) is used to connect to a pipeline returning to the dehydration tower (2).

Images