DMF (Dimethyl Formamide) wastewater recycling method
By separating DMF and water through evaporation drying, gas-liquid separation and condensation systems, and combining the removal of salt materials by spiral blade scrapers, the problems of poor quality in DMF wastewater treatment and large footprint and serious odor in biochemical treatment have been solved, achieving efficient and stable DMF recovery.
Patent Information
- Application Number
- CN202511756268.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-03-06
AI Technical Summary
Among existing DMF wastewater treatment technologies, the quality of DMF products is affected by salt content, and biological treatment requires a large area, produces severe odors, and is unstable in operation.
The system employs an evaporation drying system, a defoaming system, a condensation storage and conveying system, and a separation system. It achieves the separation of DMF and water through evaporation, gas-liquid separation, and condensation, and uses spiral blade scrapers to remove solid salt materials, ensuring stable system operation.
It improved the quality of DMF recycling, reduced the floor space required, eliminated odors, and achieved stable operation and efficient DMF recycling.
Smart Images
Figure CN121609386A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for recycling and disposing of DMF wastewater. Background Technology
[0002] In chemical production processes, DMF wastewater contains not only DMF (dimethylformamide) and water, but also a large amount of sodium salts. Existing DMF wastewater treatment technologies often employ a salt recrystallization-DMF wastewater distillation process. Salt recrystallization removes the salts from the wastewater, and then DMF is obtained from the bottom of a DMF wastewater distillation column, while the top of the column yields wastewater containing a small amount of DMF. Because salt recrystallization cannot completely remove the salts from the DMF wastewater, the DMF obtained using this technology still contains a certain amount of salt, affecting the quality of the DMF product.
[0003] Some treatment technologies employ salt recrystallization—DMF wastewater pretreatment hydrolysis acidification + A20 biological treatment process. This technology requires a large area for the biological treatment process, the biological bacteria are difficult to decompose, have low shock resistance, and produce a serious on-site odor, making it impossible to recover high-value DMF. Summary of the Invention
[0004] This invention provides a method for the recovery and disposal of DMF wastewater, which solves the problems of poor DMF recovery quality, large footprint of biochemical treatment, serious odor, and unstable operation in existing technologies. It improves the quality of DMF recovery, has a small footprint, no odor, and stable operation.
[0005] This invention is achieved through the following technical solution: A method for recycling and disposing of DMF wastewater includes the following steps: S10. Prepare an evaporation and drying system, a defoaming system, a condensation, storage and conveying system and a separation system, wherein the separation system includes a distillation separation column; S20. The DMF wastewater is transported to the evaporation and drying system for continuous evaporation. The evaporation temperature in the evaporation and drying system is designed to be 80℃-90℃, so that the salt substances in the DMF wastewater are separated in solid form. The DMF and water in the DMF wastewater enter the defoaming system in gaseous form. S30, gaseous DMF and moisture are separated into gas-liquid substances by the defoaming system. S40. The gaseous material separated by the defoaming system in step S30 enters the condensation storage and conveying system to be condensed into liquid material and stored. The condensation temperature of the condensation storage and conveying system is designed to be 40℃-50℃. Liquid materials are fed into the separation system stably and continuously via a transfer pump; S50, the liquid phase material is separated from DMF and water in the distillation separation column in the separation system.
[0006] Furthermore, in step S20, the evaporation temperature in the evaporation drying system is designed to be 85°C.
[0007] Furthermore, in step 40, the condensation temperature of the condensation storage and conveying system is designed to be 45°C. Furthermore, the operating temperature of the distillation separation column is 100℃-120℃.
[0008] Furthermore, the evaporation and drying system includes a housing, and the housing has transversely distributed processing chambers with a circular cross-section. A rotating shaft is installed in the processing chamber, and the outer wall of the rotating shaft is connected to a spiral blade via a support rod. The outer edge of the spiral blade is provided with a flexible scraper along the spiral direction. The scraper is used to scrape off the salt solid material on the inner wall of the processing chamber. The outer wall of the processing chamber is provided with a heating coil, which is used to circulate heating steam. The equipment housing has a salt discharge port at the bottom near the front end, and a solid unloader is installed inside the salt discharge port; In step S20, the rotating shaft drives the spiral blades to rotate, the scraper scrapes off the solid salt material on the inner wall of the processing chamber, and pushes the solid salt material to the salt discharge port position, and discharges it through the solid unloader.
[0009] Furthermore, the scraper is made of heat-resistant rubber material, and the heat resistance temperature of the scraper is 100℃-200℃.
[0010] Furthermore, the demisting system is a demister, which has a demisting area inside. The demisting area has multiple demisting plates from bottom to top. The top of the demister has a nozzle. The demister is equipped with a differential pressure detector. The two detection ends of the differential pressure detector are respectively located at the upper and lower ends of the demisting area. In step S30, when the differential pressure detector detects a differential pressure exceeding the range of 500 Pa to 800 Pa, the nozzle rinses the demister plate in the demister area.
[0011] Furthermore, the condensate storage and delivery system includes a condensate storage tank, which is equipped with a condenser, and a condensate delivery pump is installed at the bottom of the condensate storage tank.
[0012] The beneficial effects achieved by this invention compared to existing technologies are as follows: 1. The DMF wastewater recycling and disposal method provided by the present invention processes DMF wastewater sequentially through an evaporation and drying system, a defoaming system, a condensation storage and conveying system, and a separation system. In the evaporation and drying system, DMF and water evaporate and enter the defoaming system, thereby separating the salts in the evaporation and drying system. After defoaming, DMF and water are condensed into liquid phase and then enter a distillation separation tower to separate DMF and water, thereby recovering high-quality DMF. 2. The evaporation drying system, defoaming system, condensation storage and conveying system and separation system used in this invention occupy a small area, and the entire process is odorless and operates stably. 3. The outer edge of the spiral blade is provided with a flexible scraper along the spiral direction. The scraper is used to scrape off the solid salt material on the inner wall of the processing chamber. The spiral blade is driven to rotate by the rotating shaft. The scraper scrapes off the solid salt material on the inner wall of the processing chamber and pushes the solid salt material to the salt discharge port. After discharge, it is collected and transported, which facilitates the collection of solid salt material. 4. This invention requires minimal investment, has a simple process, and is highly automated. Attached Figure Description
[0013] Figure 1 This is a schematic diagram of the DMF wastewater recycling and treatment system described in this invention; Figure 2 This is a schematic diagram of the evaporation and drying system described in this invention; Figure 3 This is a schematic diagram of the defoaming system described in this invention; Figure 4 This is a schematic diagram showing the connection between the scraper and the spiral blades described in this invention; In the diagram: 1. Evaporation and drying system; 11. Rotating shaft; 12. Spiral blades; 13. Scraper; 14. Heating coil; 2. Demister system; 21. Demister plate; 22. Nozzle; 3. Condensation, storage, and conveying system; 4. Separation system. Detailed Implementation The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0014] In the description of the invention, it should be understood that the terms "front", "rear", "up", "down", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention.
[0015] like Figure 1-4 As shown, this invention discloses a DMF wastewater recycling and disposal system, which includes an evaporation and drying system 1, a defoaming system 2, a condensation, storage, and conveying system 3, and a separation system 4. The evaporation and drying system 1 includes a housing with laterally distributed processing chambers machined within it. Each processing chamber has a circular cross-section. A rotating shaft 11 is swivelly installed within the processing chambers. The front and rear ends of the rotating shaft 11 are swivelly mounted on the front and rear side walls of the housing via bearing assemblies. A drive motor is installed at the rear end of the housing, driving the rotating shaft 11 to rotate. A spiral blade 12 is fixedly connected to the outer wall of the rotating shaft 11 via a support rod. A flexible scraper 13 is bolted to the outer edge of the spiral blade 12 along the spiral direction. The scraper 13 is used to scrape off solid salt materials from the inner wall of the processing chambers. The scraper 13 is made of heat-resistant rubber material with a heat resistance temperature of 100℃-200℃.
[0016] The outer wall of the processing chamber is also equipped with a heating coil 14, which is used to circulate heating steam to heat the processing chamber. A salt discharge port is machined at the bottom of the equipment shell near the front end, and a solid unloader is installed in the salt discharge port. A conventional rotary valve can be used as the solid unloader.
[0017] The defoaming system 2 is a demister, which contains a defoaming zone with multiple defoaming plates 21 arranged from bottom to top. A nozzle 22 is installed at the top of the demister and is connected to an external water pipe. A differential pressure detector is also installed inside the demister. The two detection ends of the differential pressure detector are located at the upper and lower ends of the defoaming zone, respectively, to detect the pressure difference between the upper and lower positions of the touch area.
[0018] The condensate storage and conveying system 3 includes a condensate storage tank, which contains a condenser, and a condensate conveying pump is located at the bottom of the tank. The function of the condensate storage and conveying system 3 is to condense gaseous materials into condensate, and then collect a certain amount of the condensate for conveying. Since this is conventional equipment, it will not be described in detail here.
[0019] The separation system 4 consists of a distillation separation column, a column top condensation and collection system, and a column bottom collection system. Its function is to carry out distillation separation. Since it is conventional equipment, it will not be described in detail here.
[0020] Example 1 Company A generates a batch of DMF wastewater with an analysis showing a salt content of 22%, a DMF content of 29%, and a water content of 49%. Taking the treatment of this batch of DMF wastewater as an example, this embodiment discloses a method for the recovery and disposal of DMF wastewater. S10. Prepare the evaporation drying system 1, the defoaming system 2, the condensation storage and conveying system 3, and the separation system 4, and connect them sequentially according to the processing technology; S20. DMF wastewater is transported to the treatment chamber of the evaporation drying system 1. The system pressure is set to 110 kPa. Steam is introduced into the heating coil to heat and evaporate the wastewater in the treatment chamber. The evaporation temperature in the evaporation drying system 1 is designed to be 80℃. The rotating shaft 11 drives the spiral blades 12 to rotate at a speed of 10 r / min. With the stirring of the spiral blades 12, the evaporation can be accelerated. Through continuous evaporation, the salts in the DMF wastewater are separated in solid form. The DMF and water in the DMF wastewater are then introduced into the defoaming system 2 in gaseous form through the exhaust port and pipes. In this step, the rotating shaft 11 drives the spiral blade 12 to rotate, the scraper 13 scrapes off the solid salt material on the inner wall of the treatment chamber, and pushes the solid salt material to the salt discharge port position, and discharges it through the solid unloader. Finally, the salt in the DMF wastewater is bagged and transported out in solid form through the solid unloader. S30, gaseous DMF and moisture are separated into gas-liquid substances by the defoaming system 2. In this embodiment, the demister plate 21 can be set to two layers, and the pressure difference is set to 500pa delayed rinsing. When the pressure difference detector detects that the pressure difference exceeds 500pa, the nozzle 22 rinses the demister plate 21 in the demister area to avoid clogging of the demister plate and ensure the gas-liquid separation effect. S40. The condensation temperature of the condensation storage and conveying system 3 is designed to be 40℃. The gaseous material separated by the defoaming system 2 in step S30 enters the condensation storage and conveying system 3 for condensation to form liquid material and storage. Then, it enters the separation system 4 stably and continuously through the condensate conveying pump. S50, the liquid material is separated into DMF and water in the distillation separation tower in the separation system 4. High-purity DMF is recovered at the bottom and wastewater containing trace amounts of DMF is collected at the top.
[0021] Analysis showed that the DMF product composition was 99.9%, the solid salt output was stable and the particle size was obvious, thus enabling the recovery of high-quality DMF.
[0022] Example 2 Company B generates a batch of DMF wastewater with an analysis showing a salt content of 28%, a DMF content of 33%, and a water content of 39%. Taking the treatment of this batch of DMF wastewater as an example, this embodiment discloses a method for the recovery and disposal of DMF wastewater. S10. Prepare the evaporation drying system 1, the defoaming system 2, the condensation storage and conveying system 3, and the separation system 4, and connect them sequentially according to the processing technology; S20. DMF wastewater is transported to the treatment chamber of the evaporation drying system 1. The system pressure is set to 110 kPa. Steam is introduced into the heating coil to heat and evaporate the wastewater in the treatment chamber. The evaporation temperature in the evaporation drying system 1 is designed to be 90℃. The rotating shaft 11 drives the spiral blades 12 to rotate at a speed of 8 r / min. With the stirring of the spiral blades 12, the evaporation can be accelerated. Through continuous evaporation, the salts in the DMF wastewater are separated in solid form. The DMF and water in the DMF wastewater are then introduced into the defoaming system 2 in gaseous form through the exhaust port and pipes. In this step, the rotating shaft 11 drives the spiral blade 12 to rotate, the scraper 13 scrapes off the solid salt material on the inner wall of the treatment chamber, and pushes the solid salt material to the salt discharge port position, and discharges it through the solid unloader. Finally, the salt in the DMF wastewater is bagged and transported out in solid form through the solid unloader. S30, gaseous DMF and moisture are separated into gas-liquid substances by the defoaming system 2. In this embodiment, the demister plate 21 can be set to three layers, and the pressure difference is set to 800pa delayed rinsing. When the pressure difference detector detects that the pressure difference exceeds 800pa, the nozzle 22 rinses the demister plate 21 in the demister area to avoid clogging of the demister plate and ensure the gas-liquid separation effect. S40. The condensation temperature of the condensation storage and conveying system 3 is designed to be 40℃. The gaseous material separated by the defoaming system 2 in step S30 enters the condensation storage and conveying system 3 for condensation to form liquid material and storage. Then, it enters the separation system 4 stably and continuously through the condensate conveying pump. S50, the liquid material is separated into DMF and water in the distillation separation tower in the separation system 4. High-purity DMF is recovered at the bottom and wastewater containing trace amounts of DMF is collected at the top.
[0023] Analysis showed that the DMF product composition was 99.9%, the solid salt output was stable and the particle size was obvious, thus enabling the recovery of high-quality DMF.
Claims
1. A DMF wastewater recovery disposal method, characterized by, The method comprises the following steps: S10, prepare the evaporation drying system (1), the defoaming system (2), the condensation storage and conveying system (3) and the separation system (4), wherein the separation system (4) comprises a rectification separation tower; S20, the DMF wastewater is continuously evaporated in the evaporation drying system (1), the evaporation temperature in the evaporation drying system (1) is designed to be 80-90 DEG C, so that the salt in the DMF wastewater is separated out in the form of solid salt, and the DMF and water in the DMF wastewater enter the defoaming system (2) in the form of gas; S30, the gaseous DMF and water are separated into gas phase materials in the defoaming system (2); S40, the gas phase materials separated by the defoaming system (2) in step S30 enter the condensation storage and conveying system (3) to be condensed into liquid phase materials and stored, and the condensation temperature of the condensation storage and conveying system (3) is designed to be 40-50 DEG C; The liquid phase materials are stably and continuously conveyed into the separation system (4) by a conveying pump; S50, the DMF and water are separated in the rectification separation tower in the separation system (4).
2. The DMF wastewater recovery disposal method according to claim 1, wherein, In step S20, the evaporation temperature in the evaporation drying system (1) is designed to be 85 DEG C.
3. The DMF wastewater recovery disposal method according to claim 1, wherein, In step 40, the condensation temperature of the condensation storage and conveying system (3) is designed to be 45 DEG C.
4. The DMF wastewater recovery disposal method of claim 1, wherein, The working temperature of the rectification separation tower is 100-120 DEG C.
5. The DMF wastewater recovery disposal method according to claim 1, wherein, The evaporation drying system (1) comprises a device shell, a processing cavity is transversely arranged in the device shell, the processing cavity has a circular cross section, a rotating shaft (11) is rotatably arranged in the processing cavity, a spiral blade (12) is connected to the outer wall of the rotating shaft (11) through a support rod, a flexible scraper (13) is arranged on the outer edge of the spiral blade (12) in a spiral direction, and the scraper (13) is used for scraping the salt solid material on the inner wall of the processing cavity; A heating coil (14) is arranged on the outer wall of the processing cavity, and the heating coil (14) is used for circulating heating steam; A salt discharge port is arranged on the bottom of the device shell near the front end, and a solid discharger is arranged in the salt discharge port. In step S20, the rotating shaft (11) drives the spiral blade (12) to rotate, the scraper (13) scrapes the salt solid material on the inner wall of the processing cavity, and the salt solid material is pushed to the salt discharge port position and discharged through the solid discharger.
6. The DMF wastewater recovery disposal method according to claim 5, wherein, The scraper (13) is made of heat-resistant rubber material, and the heat-resistant temperature of the scraper (13) is 100-200 DEG C.
7. The DMF wastewater recovery disposal method according to claim 5, wherein, The defoaming system (2) is a defoamer, a defoaming area is arranged in the defoamer, a plurality of defoaming plates (21) are arranged in the defoaming area from bottom to top, a spray head (22) is arranged on the top of the defoamer, a differential pressure detector is arranged in the defoamer, and the two detection ends of the differential pressure detector are arranged at the upper end and the lower end of the defoaming area respectively; In step S30, when the differential pressure detector detects that the differential pressure exceeds 500-800 pa, the spray head (22) washes the defoaming plates (21) in the defoaming area.
8. The DMF wastewater recovery disposal method according to any one of claims 1-7, characterized in that, The condensate storage conveying system (3) comprises a condensate storage tank, a condenser is arranged in the condensate storage tank, and a condensate conveying pump is arranged at the bottom of the condensate storage tank.