System for recycling chloroform in wastewater
By designing a chloroform recycling and reuse system in wastewater, the problem of difficulty in recycling chloroform in wastewater during aramid synthesis is solved, and efficient chloroform recycling and reuse is achieved, achieving environmental protection and energy-saving effects.
Patent Information
- Application Number
- CN202421862717.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-02
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2034-08-02
AI Technical Summary
During the aramid synthesis process, the wastewater generated during the NMP solvent recycling process contains a small amount of chloroform, which is difficult to effectively recycle and treat in the prior art, resulting in environmental pollution.
A chloroform recycling and reuse system in wastewater was designed, including NMP aqueous solution storage tank, extraction tower, stripping tower, condenser, chloroform collection tank and chloroform recycling storage tank. Through stripping devices and coalescers and other equipment, efficient recycling and reuse of chloroform is achieved.
The recovery rate of chloroform is improved, the chloroform content in wastewater is significantly reduced, and the goal of energy saving and environmental protection is achieved.
Smart Images
Figure CN223047301U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of wastewater treatment in the production process of aramid, and particularly relates to a chloroform recovery and reuse system in wastewater. Background Art
[0002] As an organic chloride, chloroform is difficult to biodegrade, highly toxic, and chemically stable, and can exist stably in the natural environment for a long time, so it may cause long-term harm to the environment. The state has formulated strict environmental quality standards and discharge standards, so wastewater containing chloroform needs to be strictly controlled. During the synthesis process of para-aramid, chloroform is used as an extraction agent for the recovery of N-methylpyrrolidone (NMP) as a solvent, and it can efficiently extract NMP from the aqueous solution. However, there will still be a small amount of chloroform in the aqueous phase that needs to be recovered through a stripping device. To prevent the stripping effect from not completely recovering all the chloroform in the aqueous phase, it is necessary to set up an environmentally friendly and effective treatment measure to treat the small amount of chloroform in the wastewater. Summary of the Utility Model
[0003] In order to overcome the problem of a small amount of chloroform in the wastewater generated during the recovery process of NMP solvent, the utility model provides a chloroform recovery and reuse system in wastewater to achieve environmental protection and energy-saving effects.
[0004] Based on the above purpose, the technical solution adopted by the utility model is as follows:
[0005] A chloroform recovery and reuse system in wastewater, comprising an NMP aqueous solution storage tank, an extraction tower, a stripping tower, a condenser, a first chloroform collection tank, a second chloroform collection tank, and a chloroform recovery storage tank connected in sequence. The gas-phase outlet at the top of the stripping tower is connected to the condenser through a pipeline, the outlet of the condenser is connected to the inlet of the first chloroform collection tank through a pipeline, the liquid-phase outlet at the bottom of the stripping tower is connected to the inlet of the second chloroform collection tank through a pipeline. The bottoms of the first chloroform collection tank and the second chloroform collection tank are both convex downwardly with chloroform collection tanks. One side of the chloroform collection tank is provided with a coalescer, and the other side is provided with an overflow baffle, so as to form an aqueous phase collection tank on the side of the overflow baffle away from the coalescer. The bottoms of the chloroform collection tanks of the first chloroform collection tank and the second chloroform collection tank are connected to the chloroform recovery storage tank through a pipeline. The outlet of the chloroform recovery storage tank is connected to the reflux port at the upper part of the extraction tower through a pipeline. The outlet of the aqueous phase collection tank of the first chloroform collection tank is connected to the reflux port at the top of the stripping tower to regulate the temperature at the top of the tower.
[0006] Furthermore, delivery pumps are provided on the pipeline between the NMP aqueous solution storage tank and the extraction tower, on the pipeline between the stripping tower and the second chloroform collection tank, on the pipeline between the chloroform collection tank of the second chloroform collection tank and the chloroform recovery storage tank, and on the pipeline between the chloroform recovery storage tank and the extraction tower.
[0007] Furthermore, the first chloroform collecting tank and the second chloroform collecting tank are both horizontal tanks, the inlets of the first chloroform collecting tank and the second chloroform collecting tank are located at the top, and the inlets of the first chloroform collecting tank and the second chloroform collecting tank are located on the side of the coalescer away from the overflow baffle.
[0008] Furthermore, the outlet of the water phase collecting tank of the second chloroform collecting tank is connected to a sewage treatment system.
[0009] NMP recovery usually involves countercurrent feeding of aqueous NMP solution and chloroform at a certain extraction ratio in an extraction tower. The extract phase produced after chloroform and NMP are mutually dissolved will be sent out through the bottom of the extraction tower due to its high density, while the raffinate phase with a lower density will be sent out through the top of the tower. Usually, the raffinate phase at the top of the tower mainly consists of water, chloride salts and a small amount of chloroform. In order to increase the recovery rate of chloroform, the chloroform in the raffinate phase is recovered through a stripping device, and the waste liquid at the bottom of the tower is sent out for sewage treatment. In order to prevent the presence of unrecovered chloroform in the waste liquid at the bottom of the tower, a chloroform collection tank is set up to recover the chloroform in the waste liquid. The recovery tank needs to be provided with a pocket-shaped chloroform collection tank at the bottom of the tank body, and a coalescer is provided on one side of the two sides of the collection tank, and an overflow baffle is provided on the other side. Chloroform has a relatively large density, and the wastewater collects the chloroform in the waste liquid through the coalescer, and is collected by gravity into the pocket-shaped chloroform collection tank at the bottom. The wastewater overflows through the overflow baffle to the other side of the baffle and is then sent to sewage treatment. The chloroform in the collection tank is regularly transported to the chloroform recovery tank. Through this treatment measure, the chloroform in the wastewater can be effectively recovered and reused.
[0010] The utility model has a simple structure and is easy to operate. In view of the different densities of chloroform and water, the chloroform in the wastewater is recovered by arranging the recovery device, which improves the chloroform recovery rate and greatly reduces the chloroform content in the wastewater, thereby realizing the concept of energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 It is a structural schematic diagram of the utility model;
[0012] In the figure: 1. NMP aqueous solution storage tank, 2. aqueous solution storage tank delivery pump, 3. extraction tower, 4. stripping tower, 5. stripping tower bottom delivery pump, 6. second chloroform collecting tank, 7. second coalescer, 8. second overflow baffle, 9. second chloroform collecting tank, 10. second chloroform collecting tank delivery pump, 11. chloroform recovery tank, 12. first chloroform collecting tank, 13. first coalescer, 14. first overflow baffle, 15. first chloroform collecting tank, 16. condenser, 17. chloroform recovery tank delivery pump. DETAILED DESCRIPTION
[0013] In order to clearly illustrate the technical features of the present invention, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.
[0014] A chloroform recovery and reuse system for wastewater, as Figure 1 shown, which includes an NMP aqueous solution storage tank 1, an extraction column 3, a stripping column 4, a condenser 16, a first chloroform collection tank 12, a second chloroform collection tank 6, and a chloroform recovery storage tank 11 connected in sequence. The gas-phase outlet at the top of the stripping column 4 is connected to the condenser 16 through a pipeline, the outlet of the condenser 16 is connected to the inlet of the first chloroform collection tank 12 through a pipeline, the liquid-phase outlet at the bottom of the stripping column 4 is connected to the inlet of the second chloroform collection tank 6 through a pipeline. The bottoms of the first chloroform collection tank 12 and the second chloroform collection tank 6 are respectively provided with a first chloroform collection groove 15 and a second chloroform collection groove 9 protruding downward. One side of the first chloroform collection groove 15 is provided with a first coalescer 13, and the other side is provided with a first overflow baffle 14, so as to form a first aqueous phase collection groove on the side of the first overflow baffle 14 away from the first coalescer 13. One side of the second chloroform collection groove 9 is provided with a second coalescer 7, and the other side is provided with a second overflow baffle 8, so as to form a second aqueous phase collection groove on the side of the second overflow baffle 8 away from the second coalescer 7. The bottom of the first chloroform collection groove 15 is connected to the chloroform recovery storage tank 11 through a pipeline, and the bottom of the second chloroform collection groove 9 is connected to the chloroform recovery storage tank 11 through a pipeline and a second chloroform collection groove transfer pump 10 provided on the pipeline. The outlet of the chloroform recovery storage tank 11 is connected to the reflux port at the upper part of the extraction column 3 through a pipeline and a chloroform recovery storage tank transfer pump 17 provided on the pipeline. The outlet of the first aqueous phase collection groove is connected to the reflux port at the top of the stripping column 4 to regulate the top temperature. The outlet of the second aqueous phase collection groove is connected to the sewage treatment system.
[0015] An aqueous solution storage tank transfer pump 2 is provided on the pipeline between the NMP aqueous solution storage tank 1 and the extraction column 3, and a stripping column bottom transfer pump 5 is provided on the pipeline between the stripping column 4 and the second chloroform collection tank 6 in a straight line.
[0016] Among them, both the first chloroform collection tank 12 and the second chloroform collection tank 6 are horizontal tanks. The inlets of the first chloroform collection tank 12 and the second chloroform collection tank 6 are located at the top, and the inlets of the first chloroform collection tank 12 are respectively located on the side of the first coalescer 13 away from the first overflow baffle 14, and the inlets of the second chloroform collection tank 6 are respectively located on the side of the second coalescer 7 away from the second overflow baffle 8.
[0017] In use, the NMP solution in the NMP aqueous solution storage tank 1 is transported to the extraction column 3 by the aqueous solution storage tank transfer pump 2. At the same time, chloroform in the chloroform recovery storage tank 11 enters from the upper part of the extraction column 3 in proportion. The chloroform and the NMP aqueous solution perform countercurrent extraction. After the chloroform is miscible with the NMP in the NMP aqueous solution, an extraction phase is formed. The density of the extraction phase is relatively large and is sent out of the extraction column 3 to the subsequent process for the recovery of NMP and chloroform. The recovered chloroform enters the chloroform recovery tank 11 for recycling. The raffinate phase (water, chloroform, calcium chloride) with a relatively small density at the top mainly enters the stripping column 4 by overflow. The stripping column 4 recovers the chloroform in the raffinate phase through the action of steam. The gas phase at the top of the stripping column 4 recovers the chloroform to the first chloroform collection tank 12 by setting a condenser 16. For the wastewater at the bottom of the stripping column 4, there is still a small amount of chloroform. Therefore, before the wastewater at the bottom of the stripping column 4 is discharged, the chloroform is collected by setting a second chloroform collection tank 6 and then the wastewater is sent out to reduce the content of chloroform in the wastewater. Currently, by setting the first chloroform collection tank 12 and the second chloroform collection tank 6, efficient recovery of chloroform and reduction of the discharge of pollution sources are achieved. A first coalescer 13 and a first overflow baffle 14 are arranged in the first chloroform collection tank 12, and a second coalescer 7 and a second overflow baffle 8 are arranged in the second chloroform collection tank 6. The overhead condensate is collected in the first chloroform collection tank 12. By setting this collection tank, the water in the chloroform recovered at the top of the tower overflows through the first baffle 14 to the other side of the baffle and returns to the top of the stripping column 4 to regulate the top temperature. The chloroform in the first chloroform collection tank 12 at the bottom of the first chloroform collection tank 15 is transported to the chloroform recovery storage tank 11 for recycling. Similarly, the bottom effluent first enters the set second chloroform collection tank 6. The chloroform is aggregated by the second coalescer 7 and then settles in the second chloroform collection tank 9 at the bottom of the second chloroform collection tank 6 in a funnel shape. The chloroform in the funnel-shaped collection tank is regularly transported to the chloroform recovery storage tank 11 for recycling by the second chloroform collection tank transfer pump 10, and the water overflowing to the other side of the baffle is sent to the sewage treatment.
[0018] The above specific embodiments cannot be used as a limitation on the protection scope of the present invention. For those skilled in the art of this technology, any alternative improvement or transformation made to the embodiments of the present invention falls within the protection scope of the present invention.
[0019] Where the present invention is not described in detail, it is all well-known technology to those skilled in the art of this technology.
Claims
1. A system for recycling chloroform in wastewater, characterized in that: The invention comprises an NMP aqueous solution storage tank, an extraction tower, a stripping tower, a condenser, a first chloroform collecting tank, a second chloroform collecting tank and a chloroform recovery storage tank which are connected in sequence. The gas phase outlet at the top of the stripping tower is connected to the condenser through a pipeline, the outlet of the condenser is connected to the inlet of the first chloroform collecting tank through a pipeline, the liquid phase outlet at the bottom of the stripping tower is connected to the inlet of the second chloroform collecting tank through a pipeline, the bottoms of the first chloroform collecting tank and the second chloroform collecting tank are both protruding downwards and provided with a chloroform collecting tank, a coalescer is provided on one side of the chloroform collecting tank and an overflow baffle is provided on the other side so as to form a water phase collecting tank on the side of the overflow baffle away from the coalescer, the bottoms of the chloroform collecting tanks of the first chloroform collecting tank and the second chloroform collecting tank are connected to the chloroform recovery storage tank through a pipeline, the outlet of the chloroform recovery storage tank is connected to the reflux port on the upper part of the extraction tower through a pipeline, and the outlet of the water phase collecting tank of the first chloroform collecting tank is connected to the reflux port on the top of the stripping tower so as to be used for regulating the tower top temperature.
2. The system for recycling chloroform in wastewater according to claim 1, characterized in that: Delivery pumps are provided on the pipeline between the NMP aqueous solution storage tank and the extraction tower, on the pipeline between the stripping tower and the second chloroform collecting tank, on the pipeline between the second chloroform collecting tank chloroform collecting tank and the chloroform recovery storage tank, and on the pipeline between the chloroform recovery storage tank and the extraction tower.
3. The system for recycling chloroform in wastewater according to claim 1, characterized in that: The first chloroform collecting tank and the second chloroform collecting tank are both horizontal tanks, the inlets of which are located at the top, and the inlets of which are located at the side of the coalescer away from the overflow baffle.
4. The system for recycling chloroform in wastewater according to claim 1, characterized in that: The outlet of the water phase collecting tank of the second chloroform collecting tank is connected to the sewage treatment system.