DMAC solvent wastewater heat pump rectification system

Abstract

The utility model provides a DMAC solvent wastewater heat pump rectification system, which is applied to the technical field of heat pump rectification, suitable raw materials comprise DMAC wastewater, DMF wastewater and DMSO wastewater, the raw materials are conveyed to a rectification module for three-stage rectification after being heated for three times by a feeding module, a steam compressor module collects steam in the rectification module for temperature and pressure increasing, and the steam in the rectification module is conveyed to a rectification module for three-stage rectification. Transmitting to the rectification module as a heat source; the feeding module comprises a product preheater used for carrying out heat exchange on qualified products generated by the rectification module and raw materials, a distilled water preheater used for carrying out heat exchange on distilled water generated by the rectification module and the raw materials, and a non-condensed steam preheater used for carrying out heat exchange on non-condensed steam generated by the rectification module and the raw materials; the steam compressor module comprises a first-stage steam compressor and a second-stage steam compressor which are connected in series. According to the DMAC solvent wastewater heat pump rectification system, the working efficiency can be improved, and the electric energy loss and the steam consumption can be reduced.

Description

Technical Field

[0001] This utility model belongs to the field of heat pump distillation technology, specifically relating to a DMAC-type solvent wastewater heat pump distillation system. Background Technology

[0002] DMAC, or N,N-dimethylacetamide, is a commonly used organic solvent widely applied in the chemical, textile, and pharmaceutical industries. Separation is achieved by utilizing the difference in boiling points between DMAC and water (DMAC 164-166℃, water 100℃), enabling the recovery of DMAC from high-concentration, low-impurity wastewater. In the chemical industry, DMAC can be directly recovered by distillation, achieving a recovery rate of over 90%, with purity meeting process reuse requirements. In the textile industry, pretreatment is required to remove suspended solids and dyes before distillation to recover DMAC; the residue can be further processed.

[0003] Because DMAC solvent wastewater requires a high-vacuum distillation environment and also demands high purity of recycled water, many technical considerations must be taken into account during the technical design. Furthermore, conventional distillation techniques consume a significant amount of steam and require large quantities of chilled water at the top of the column to meet the system's distillation requirements, resulting in very high operating costs. Utility Model Content

[0004] In view of the above-mentioned problems in the prior art, the purpose of this utility model is to provide a DMAC-type solvent wastewater heat pump distillation system that can improve working efficiency and reduce power consumption and steam consumption.

[0005] A DMAC-type solvent wastewater heat pump distillation system includes a feed module, a distillation module, and a steam compressor module. The raw material is heated three times by the feed module and then transferred to the first-stage distillation unit, the second-stage distillation unit, and the third-stage distillation unit of the distillation module for three-stage distillation. During the distillation process, the steam compressor module collects the steam in the distillation module, heats and pressurizes it, and then transfers the heated and pressurized steam to the distillation module as a heat source.

[0006] The feeding module includes a product preheater, a distilled water preheater, and a non-condensable vapor preheater. The product preheater is used to exchange heat between the qualified product produced by the distillation module and the raw material, achieving the first heating of the raw material. The distilled water preheater is used to exchange heat between the distilled water produced by the distillation module and the raw material, achieving the second heating of the raw material. The non-condensable vapor preheater is used to exchange heat between the non-condensable vapor produced by the distillation module and the raw material, achieving the third heating of the raw material.

[0007] The steam compressor module includes a primary steam compressor and a secondary steam compressor connected in series, with the outlet of the secondary steam compressor connected to the inlet of the primary steam compressor.

[0008] Preferably, the feeding module further includes a feeding buffer tank and a feeding pump. The feeding buffer tank is connected to the product preheater via the feeding pump. The product preheater is connected to the distilled water preheater. The distilled water preheater is connected to the non-condensable steam preheater. The non-condensable steam preheater is used to transfer the preheated raw material to the distillation module.

[0009] Preferably, the primary distillation unit includes a primary falling film evaporator, a primary MVR distillation column, and a primary falling film circulating pump. The material circulation pipeline of the primary falling film evaporator is connected to the raw material outlet of the non-condensable steam preheater. The material circulation pipeline of the primary falling film evaporator is equipped with a primary falling film circulating pump. The primary falling film evaporator is connected to the primary MVR distillation column, and the vapor phase outlet of the primary MVR distillation column is connected to the inlet of the primary steam compressor.

[0010] Preferably, the secondary distillation unit includes a secondary falling film evaporator, a secondary MVR distillation column, and a secondary falling film circulating pump. The material circulation line of the secondary falling film evaporator is connected to the material circulation line of the primary falling film evaporator and the product distillation column, respectively. A secondary falling film circulating pump is configured on the material circulation line of the secondary falling film evaporator. The secondary falling film evaporator is connected to the secondary MVR distillation column, and the vapor phase outlet of the secondary MVR distillation column is connected to the inlet of the secondary vapor compressor.

[0011] Preferably, the three-stage distillation unit includes a product falling film evaporator, a product distillation column, and a product falling film circulating pump. The product falling film evaporator is equipped with a product falling film circulating pump on its material circulation pipeline. The product falling film evaporator is connected to the product distillation column. The vapor phase outlet of the product distillation column is connected to the condenser inlet. The condenser outlet is connected to a reflux tank. The reflux tank is connected to the product distillation column via a reflux pump. A circulation loop is formed between the product distillation column, condenser, reflux tank, and reflux pump. The reflux pump branch is connected to the feed buffer tank.

[0012] Preferably, the top vapor of the secondary MVR distillation column in the distillation module is transferred to the secondary steam compressor for heating and pressurization, and then combined with the top vapor of the primary MVR distillation column for heating and pressurization. The outlet of the primary steam compressor is connected to the primary falling film evaporator, the secondary falling film evaporator, and the product falling film evaporator, respectively. The outlet temperature of the secondary steam compressor is the same as the inlet temperature of the primary steam compressor.

[0013] Preferably, the product preheater is connected to the product falling film evaporator of the distillation module via a product pump, and the product preheater is also connected to a product buffer tank, which is equipped with a product delivery pump.

[0014] Preferably, the hot-side inlet of the distilled water preheater is connected to the condensate tank via a distilled water pump, the condensate tank inlet is connected to the hot-side outlet of the first-stage falling film evaporator and the second-stage falling film evaporator, and the hot-side outlet of the distilled water preheater is connected to the distilled water buffer tank.

[0015] Preferably, the distilled water buffer tank is connected to the reflux port of the first-stage MVR distillation column and the reflux port of the second-stage MVR distillation column via a reflux spray pump, and the distilled water buffer tank is also connected to a distilled water delivery pump.

[0016] Preferably, the inlet of the non-condensable steam preheater is connected to the first-stage falling film evaporator, the second-stage falling film evaporator, and the product falling film evaporator. The outlet of the non-condensable steam preheater is connected to the condensate tank and the non-condensable steam cooler respectively through a gas-liquid separator. The non-condensable steam cooler is connected to the condensate tank.

[0017] The beneficial effects of this utility model are: the DMAC solvent wastewater heat pump distillation system uses the corresponding products in the distillation module to heat the raw materials in sequence through the product preheater, distilled water preheater and non-condensable vapor preheater, thereby realizing three-stage preheating of the raw materials. This can make full use of the energy resources of the entire system. Moreover, the raw materials are distilled through the distillation module after reaching the threshold through three-stage preheating, which can effectively improve the working efficiency.

[0018] The distilled water produced in the product distillation column is partially returned to the product distillation column through the cooperation of a condenser, reflux tank, and reflux pump, while the other part is transferred to the feed buffer tank for further purification and separation. This ensures that the distilled water at the top of the product distillation column meets the standards, and also reduces the packing height of the product distillation column, thereby reducing the overall column pressure drop and preventing the bottom temperature from exceeding the limit.

[0019] By connecting a primary steam compressor and a secondary steam compressor in series, the steam at the top of the primary and secondary MVR distillation columns is heated and pressurized in stages. The heated and pressurized gas is then used as the heat source for the primary falling film evaporator, the secondary falling film evaporator, and the product falling film evaporator. This reduces steam consumption by more than 90%. Furthermore, by setting the outlet temperature of the secondary steam compressor to be the same as the inlet temperature of the primary steam compressor in a series configuration, the power consumption of the steam compressor can be significantly reduced, saving more than 30% of electricity. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0021] Figure 1 This is a structural block diagram of the present invention.

[0022] The following pumps are labeled in the diagram: 1. Reflux spray pump; 2. Distilled water delivery pump; 3. Feed pump; 4. First-stage falling film circulation pump; 5. Distilled water pump; 6. Second-stage falling film circulation pump; 7. Product delivery pump; 8. Product pump; 9. Distillation falling film circulation pump; 10. Reflux pump; 11. Water ring vacuum pump; 12. Screw vacuum pump; 13. First-stage steam compressor; 14. Second-stage steam compressor; 15. Distilled water buffer tank; 16. Feed buffer tank. ; 17. Condensate tank; 18. Product buffer tank; 19. Reflux tank; 20. Gas-liquid separator; 21. Distilled water preheater; 22. Product preheater; 23. Non-condensable vapor preheater; 24. First-stage falling film evaporator; 25. Second-stage falling film evaporator; 26. Non-condensable vapor cooler; 27. Product falling film evaporator; 28. Condenser; 29. ​​First-stage MVR distillation column; 30. Second-stage MVR distillation column; 31. Product distillation column. Detailed Implementation

[0023] Example 1

[0024] like Figure 1 As shown, a heat pump distillation system for DMAC solvent wastewater includes a feed module, a distillation module, and a steam compressor module. The feed module is used for feeding and preheating DMAC solvent wastewater. The distillation module includes a primary distillation unit, a secondary distillation unit, and a tertiary distillation unit, used to perform three distillations on the preheated DMAC solvent wastewater to form a product that meets the requirements. The steam compressor module is used to fully utilize the latent heat of secondary steam for falling film evaporation during the distillation process, thereby reducing the system's energy consumption.

[0025] It should be noted that solvents similar to DMAC include DMF, DMSO, etc., and this system is applicable to the treatment of such wastewater.

[0026] like Figure 1 As shown, the feeding module includes a feeding buffer tank 16, a feeding pump 3, a product preheater 22, a distilled water preheater 21, and a non-condensable steam preheater 23.

[0027] The feed buffer tank 16 stores DMAC wastewater at 30℃, atmospheric pressure, and a concentration of 4% with a flow rate of 25t / h. The DMAC wastewater is preheated in three stages by the feed pump 3 through the product preheater 22, the distilled water preheater 21, and the non-condensable steam preheater 23. After being heated to 75℃, it enters the distillation module for three distillations.

[0028] The feed buffer tank 16 is connected to the product preheater 22 via the feed pump 3 to transfer DMAC wastewater to the product preheater 22. The product preheater 22 is connected to the distilled water preheater 21. The distilled water preheater 21 is connected to the non-condensable steam preheater 23. The non-condensable steam preheater 22 is connected to the circulation pipeline of the first-stage falling film circulation pump 4 on the tube side of the first-stage falling film evaporator 24 in the distillation module.

[0029] In addition, the product preheater 22 is connected to the product falling film evaporator 27 of the distillation module via the product pump 8. The product preheater 22 is also connected to the product buffer tank 18, which is equipped with a product delivery pump 7. The product pump 8 transfers the qualified product formed in the product falling film evaporator 27 to the product preheater 22, where it exchanges heat with the DMAC solvent wastewater. This process preheats the DMAC solvent wastewater while simultaneously cooling the product. The cooled product is then discharged via the product delivery pump 7.

[0030] like Figure 1 As shown, the first-stage distillation unit includes a first-stage falling film evaporator 24, a first-stage MVR distillation column 29, and a first-stage falling film circulating pump 4.

[0031] A primary falling film evaporator 24 is equipped with a primary falling film circulation pump 4 on its material circulation pipeline. The steam port on the tube side of the primary falling film evaporator 24 is connected to the inlet of the primary MVR distillation column 29. The vapor phase outlet of the primary MVR distillation column 29 is connected to the inlet of the primary steam compressor 13 of the steam compressor module. The liquid phase outlet of the primary MVR distillation column 29 is connected to the inlet pipeline of the primary falling film circulation pump 4. The reflux pipeline of the primary MVR distillation column 29 is connected to the reflux port.

[0032] The bottom temperature of the first-stage MVR distillation column 29 is 80℃, the top temperature is 75℃, the reflux ratio of the first-stage MVR distillation column 29 is 0.18, and the concentration of the concentrated DMAC wastewater is 20%.

[0033] like Figure 1 As shown, the secondary distillation unit includes a secondary falling film evaporator 25, a secondary MVR distillation column 30, and a secondary falling film circulation pump 6.

[0034] A secondary falling film evaporator 25 is equipped with a secondary falling film circulation pump 6 on its material circulation pipeline. The steam port on the tube side of the secondary falling film evaporator 25 is connected to the gas inlet of the secondary MVR distillation column 30. The vapor phase outlet of the secondary MVR distillation column 30 is connected to the inlet of the secondary steam compressor 14 of the steam compressor module. The liquid phase outlet of the secondary MVR distillation column 30 is connected to the inlet pipeline of the secondary falling film circulation pump 6. The reflux pipeline of the secondary MVR distillation column 30 is connected to the reflux port.

[0035] The bottom temperature of the secondary MVR distillation column 30 is 75℃, the top temperature is 68℃, the reflux ratio of the secondary MVR distillation column 30 is 0.3, and the concentration of the concentrated DMAC wastewater is 60%.

[0036] like Figure 1 As shown, the three-stage distillation unit includes a product falling film evaporator 27, a product distillation column 31, and a product falling film circulation pump 9.

[0037] The product falling film evaporator 27 is equipped with a product falling film circulation pump 9 on its material circulation pipeline. The vapor port on the tube side of the product falling film evaporator 27 is connected to the gas inlet of the product distillation column 31. The vapor outlet of the product distillation column 31 is connected to the hot-side inlet of the condenser 28. The cold-side inlet and outlet of the condenser 28 are connected to chilled water pipelines. The hot-side liquid outlet of the condenser 28 is connected to the reflux tank 19 and the reflux pump 10. The outlet of the reflux pump 10 is connected to the product distillation column 31. A branch of the reflux pump 10 is connected to the feed buffer tank 16 for further purification and separation. The hot-side gas outlet of the condenser 28 is connected to the inlet of the screw vacuum pump 12, and the outlet of the screw vacuum pump 12 is connected to atmospheric venting.

[0038] The liquid outlet of the product distillation column 31 is connected to the inlet pipeline of the product falling film circulation pump 9, the reflux pipeline of the product distillation column 31 is connected to the reflux port, the material outlet on the tube side of the product falling film evaporator 27 is connected to the inlet of the product pump 8, and the outlet of the product pump 8 is connected to the product preheater 22.

[0039] The bottom temperature of product distillation column 31 is 110℃, the top temperature is 53℃, the reflux ratio of product distillation column 31 is 0.9, and the concentration of DMAC after concentration is 99.9%.

[0040] The material circulation pipeline of the first-stage falling film evaporator 24 is connected to the material circulation pipeline of the second-stage falling film evaporator 25, and the material circulation pipeline of the second-stage falling film evaporator 25 is also connected to the product distillation column 31, forming a three-stage distillation structure.

[0041] like Figure 1 As shown, the primary steam compressor 13 and the secondary steam compressor 14 constitute a steam compressor module. The inlet of the secondary steam compressor 14 is connected to the secondary MVR distillation column 30, and the outlet of the secondary steam compressor 14 is connected to the inlet of the primary steam compressor 13. The inlet of the primary steam compressor 13 is also connected to the primary MVR distillation column 29. The outlet of the primary steam compressor 13 is connected to the shell-side inlet of the primary falling film evaporator 24, the shell-side inlet of the secondary falling film evaporator 25, and the shell-side inlet of the product falling film evaporator 27, respectively. The shell-side inlet of the product falling film evaporator 27 is also connected to external steam.

[0042] The top steam of the secondary MVR distillation column 30 is transferred to the secondary steam compressor 14 for heating and pressurization, and then combined with the top steam of the primary MVR distillation column 29 for heating and pressurization. The heated and pressurized steam is used as the heat source for the primary falling film evaporator 24, the secondary falling film evaporator 25, and the product falling film evaporator 27, which can effectively reduce steam consumption.

[0043] Specifically, the inlet temperature of the secondary steam compressor 14 is 68℃ and the outlet temperature is 75℃, the inlet temperature of the primary steam compressor 13 is 75℃ and the outlet temperature is 93℃, and the steam at 93℃ meets the steam inlet requirements of the primary falling film evaporator 24, the secondary falling film evaporator 25 and the product falling film evaporator 27.

[0044] In addition, the hot-side outlets of the first-stage falling film evaporator 24 and the second-stage falling film evaporator 25 are connected to the condensate tank 17. The condensate tank 17 is connected to the hot-side inlet of the distillate preheater 21 via the distillate pump 5. The hot-side outlet of the distillate preheater 21 is connected to the distillate buffer tank 15. The outlet of the distillate buffer tank 15 is connected to the inlet of the reflux spray pump 1. The outlet of the reflux spray pump 1 is connected to the reflux port of the first-stage MVR distillation column 29, the reflux port of the second-stage MVR distillation column 30, the spray port of the first-stage steam compressor 13, and the spray port of the second-stage steam compressor 14, respectively. The distillate buffer tank 15 is also connected to the distillate external pump 2.

[0045] The qualified distilled water output from the first-stage falling film evaporator 24 and the second-stage falling film evaporator 25 is reheated by the distilled water preheater 21 to the DMAC solvent wastewater. Part of the water is then supplied to the first-stage MVR distillation column 29, the second-stage MVR distillation column 30, the first-stage steam compressor 13, and the second-stage steam compressor 14 via the reflux spray pump 1, while the rest is discharged via the distilled water external pump 2.

[0046] Non-condensable steam from the primary falling film evaporator 24, the secondary falling film evaporator 25, and the product falling film evaporator 27 is transferred to the non-condensable steam preheater 23. The non-condensable steam preheater 23 is connected to the condensate tank 17 and the non-condensable steam cooler 26 via a gas-liquid separator 20. Gas enters the non-condensable steam cooler 26, and liquid enters the condensate tank 17. The hot-side liquid outlet of the non-condensable steam cooler 26 is connected to the inlet of the condensate tank 17, forming a condensate circulation collection pipeline. The hot-side inlet of the non-condensable steam cooler 26 is connected to the inlet of the water ring vacuum pump 11, and the cold-side inlet and outlet of the non-condensable steam cooler 26 are connected to the circulating cooling water pipeline. The outlet of the water ring vacuum pump 11 is discharged to the atmosphere.

[0047] Working principle: DMAC wastewater at 30℃, atmospheric pressure, and a concentration of 4% with a flow rate of 25t / h is preheated in three stages: product preheater 22, distilled water preheater 21, and non-condensable steam preheater 23. After being heated to 75℃, it enters the first-stage distillation unit, the second-stage distillation unit, and the third-stage distillation unit for three distillation treatments.

[0048] The primary, secondary, and tertiary distillation units employ MVR distillation technology. During the distillation process, the overhead vapors from the primary MVR distillation column 29 and the secondary MVR distillation column 30 enter the primary steam compressor 13 and the secondary steam compressor 14 connected in series, respectively. Through two-stage steam compression operations, the steam provides a heat source for the primary falling film evaporator 24, the secondary falling film evaporator 25, and the product falling film evaporator 27, thereby reducing steam consumption and the electrical energy consumption of the steam engine.

[0049] After three distillations, the qualified product is transferred to the product preheater 22 for heat transfer with the DMAC solvent wastewater. This process achieves the first heating of the DMAC solvent wastewater and cools the product. The cooled product is then output through the product delivery pump 7.

[0050] The distilled water produced by the first-stage MVR distillation column 29 and the second-stage MVR distillation column 30 is collected in the condensate tank 15 through the first-stage falling film evaporator 24 and the second-stage falling film evaporator 25, and then transferred to the distillate water preheater 21 by the distillate water pump 5. It exchanges heat with the DMAC solvent wastewater, which achieves a second heating of the DMAC solvent wastewater and cools the distillate water. The cooled distillate water is transferred to the distillate water buffer tank 15. Part of it is returned to the first-stage MVR distillation column 29 and the second-stage MVR distillation column 30 by the reflux spray pump 1, and the other part is output. In addition, the distilled water produced by the product distillation column 31 is partially returned to the product distillation column 31 through the cooperation of the condenser 28, the reflux tank 19, and the reflux pump 10, and the other part is transferred to the feed buffer tank 16 for further purification and separation.

[0051] The non-condensable vapors generated by the primary falling film evaporator 24, the secondary falling film evaporator 25, and the product falling film evaporator 27 are transferred to the non-condensable vapor preheater 23 for heat exchange with DMAC solvent wastewater, achieving the third heating of the DMAC solvent wastewater. The gas and liquid are separated by the gas-liquid separator 20, and the liquid is transferred to the condensate tank 17. The gas is transferred to the condensate tank 17 after passing through the non-condensable vapor cooler 26 to form condensate, thus forming the recycling of non-condensable vapors.

[0052] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A DMAC-based solvent wastewater heat pump rectification system, characterized in that, It includes a feeding module, a distillation module, and a steam compressor module. After being heated three times by the feeding module, the raw material is transferred to the first-stage distillation unit, the second-stage distillation unit, and the third-stage distillation unit of the distillation module for three-stage distillation. During the distillation process, the steam compressor module collects the steam in the distillation module, heats and pressurizes it, and then transfers the heated and pressurized steam to the distillation module as a heat source. The feeding module includes a product preheater, a distilled water preheater, and a non-condensable vapor preheater. The product preheater is used to exchange heat between the qualified product produced by the distillation module and the raw material, achieving the first heating of the raw material. The distilled water preheater is used to exchange heat between the distilled water produced by the distillation module and the raw material, achieving the second heating of the raw material. The non-condensable vapor preheater is used to exchange heat between the non-condensable vapor produced by the distillation module and the raw material, achieving the third heating of the raw material. The steam compressor module includes a primary steam compressor and a secondary steam compressor connected in series, with the outlet of the secondary steam compressor connected to the inlet of the primary steam compressor.

2. The DMAC-based solvent wastewater heat pump rectification system according to claim 1, characterized in that, The feeding module also includes a feeding buffer tank and a feeding pump. The feeding buffer tank is connected to the product preheater via the feeding pump. The product preheater is connected to the distilled water preheater. The distilled water preheater is connected to the non-condensable steam preheater. The non-condensable steam preheater is used to transfer the preheated raw material to the distillation module.

3. The DMAC-based solvent wastewater heat pump rectification system according to claim 1, characterized in that, The primary distillation unit includes a primary falling film evaporator, a primary MVR distillation column, and a primary falling film circulating pump. The material circulation pipeline of the primary falling film evaporator is connected to the raw material outlet of the non-condensable steam preheater. The material circulation pipeline of the first-stage falling film evaporator is equipped with a first-stage falling film circulation pump. The first-stage falling film evaporator is connected to the first-stage MVR distillation column, and the vapor phase outlet of the first-stage MVR distillation column is connected to the inlet of the first-stage steam compressor.

4. The DMAC-based solvent wastewater heat pump rectification system according to claim 1, characterized in that, The secondary distillation unit includes a secondary falling film evaporator, a secondary MVR distillation column, and a secondary falling film circulation pump. The material circulation pipeline of the secondary falling film evaporator is connected to the material circulation pipeline of the primary falling film evaporator and the product distillation column, respectively. The material circulation pipeline of the secondary falling film evaporator is equipped with a secondary falling film circulation pump. The secondary falling film evaporator is connected to the secondary MVR distillation column, and the vapor phase outlet of the secondary MVR distillation column is connected to the inlet of the secondary steam compressor.

5. The DMAC-based solvent wastewater heat pump rectification system according to claim 1, characterized in that, The three-stage distillation unit includes a product falling film evaporator, a product distillation column, and a product falling film circulation pump. The product falling film evaporator is equipped with a product falling film circulation pump on its material circulation pipeline. The product falling film evaporator is connected to the product distillation column. The vapor phase outlet of the product distillation column is connected to the condenser inlet. The condenser outlet is connected to a reflux tank. The reflux tank is connected to the product distillation column via a reflux pump. A circulation loop is formed between the product distillation column, condenser, reflux tank, and reflux pump. The reflux pump branch is connected to the feed buffer tank.

6. The DMAC-based solvent wastewater heat pump rectification system according to claim 1, wherein, In the distillation module, the top vapor from the secondary MVR distillation column is transferred to the secondary steam compressor for heating and pressurization, and then combined with the top vapor from the primary MVR distillation column for heating and pressurization. The outlet of the primary steam compressor is connected to the primary falling film evaporator, the secondary falling film evaporator, and the product falling film evaporator, respectively. The outlet temperature of the secondary steam compressor is the same as the inlet temperature of the primary steam compressor.

7. The DMAC-based solvent wastewater heat pump rectification system according to claim 1, characterized in that, The product preheater is connected to the product falling film evaporator of the distillation module via a product pump. The product preheater is also connected to a product buffer tank, which is equipped with a product delivery pump.

8. The DMAC-based solvent wastewater heat pump rectification system according to claim 1, characterized in that, The hot-side inlet of the distilled water preheater is connected to the condensate tank via a distilled water pump. The condensate tank inlet is connected to the hot-side outlet of the first-stage falling film evaporator and the second-stage falling film evaporator. The hot-side outlet of the distilled water preheater is connected to the distilled water buffer tank.

9. The DMAC-based solvent wastewater heat pump rectification system according to claim 8, characterized in that, The distilled water buffer tank is connected to the reflux port of the first-stage MVR distillation column and the reflux port of the second-stage MVR distillation column via a reflux spray pump. The distilled water buffer tank is also connected to a distilled water external delivery pump.

10. The DMAC-based solvent wastewater heat pump rectification system according to claim 1, characterized in that, The inlet of the non-condensable steam preheater is connected to the first-stage falling film evaporator, the second-stage falling film evaporator, and the product falling film evaporator. The outlet of the non-condensable steam preheater is connected to the condensate tank and the non-condensable steam cooler respectively through a gas-liquid separator. The non-condensable steam cooler is connected to the condensate tank.

Images