Five-cycle DMF (Dimethyl Formamide) waste gas recovery equipment and recovery process

Abstract

The invention relates to the technical field of waste gas recovery and treatment, and discloses five-cycle DMF waste gas recovery equipment which comprises a spray tower body, five stages of spray chambers are arranged in the spray tower body, spray pipes are arranged in the spray chambers, five stages of collection boxes in one-to-one correspondence with the spray pipes are arranged below the spray tower body, and the collection boxes are connected with the spray tower body. The first-stage collecting box is provided with a collecting port, and the fifth-stage collecting box is communicated with a water inlet. According to the five-cycle DMF waste gas recovery equipment and the recovery process, a traditional interstage pumping valve control mode is abandoned, an interstage liquid distribution mechanism for controlling displacement of the flexible flow guide pipe based on rotation of a single driving source is created for the first time, and on the premise that a moving part does not make direct contact with a corrosive medium, the flow guide pipe can be flexibly distributed; accurate countercurrent replacement and dynamic mixing are carried out on the five-stage absorption liquid, and the problems that a pump valve is scaled and blocked and the concentration gradient is out of control due to the high-viscosity DMF waste liquid are thoroughly solved.

Description

A five-cycle DMF waste gas recovery device and recovery process Technical Field

[0001] This application relates to the field of waste gas recovery and treatment technology, and in particular to a five-cycle DMF waste gas recovery device and recovery process. Background Technology

[0002] In the production of synthetic leather, a large amount of volatile organic solvents (such as DMF, ethyl acetate, toluene, methyl ethyl ketone, etc.) are used. Due to the volatility of DMF, a large amount of volatile process waste gas containing DMF is generated during the coating stage and six-roll process. All of it evaporates into the atmosphere, causing certain pollution to the environment and also causing certain waste to enterprises.

[0003] Given DMF's highly soluble nature in water, a five-stage series water washing absorption process is commonly used in industry for waste gas treatment and solvent recovery. The core principle of this process is to utilize five absorption towers (or circulating water tanks) connected in series to create a concentration gradient field from low to high concentration: the fifth stage introduces an absorbent close to clean water to capture trace amounts of residual DMF in the waste gas, ensuring that the exhaust gas meets emission standards; the first stage contacts high-concentration waste gas, and the absorbent concentration gradually approaches saturation. The system employs a counter-current displacement mode of "each stage replenishing the previous stage," meaning that when the absorbent in the first stage approaches saturation, it is collected and sent to the distillation section, then the second stage replenishes the first stage, the third stage replenishes the second stage, and so on, until the fifth stage replenishes with fresh water. Through this multi-stage series connection, the system naturally forms a stepped concentration distribution from the fifth stage (low concentration) to the first stage (high concentration), maximizing the driving force of gas-liquid mass transfer.

[0004] However, both existing mainstream technologies have significant technical bottlenecks in specific interstage liquid transport and control methods: the first is the gravity overflow scheme. This scheme arranges five water tanks in a terraced pattern (stage 5 is the highest, stage 1 is the lowest), utilizing the liquid level difference to achieve automatic liquid overflow. Its drawbacks are: firstly, to achieve sufficient static pressure head to overcome pipeline resistance and maintain stable overflow, a huge vertical installation height and massive steel structure support are required, resulting in a large footprint and high civil engineering costs; secondly, due to reliance on gravity-driven natural overflow, the fluid dynamics are poor, and newly added low-concentration solutions easily flow directly to the next stage outlet along the path of least resistance, forming a "hydraulic short circuit," leading to insufficiently mixed "dead water zones" within the tanks, disrupting the ideal concentration gradient, and causing the actual absorption efficiency to be far lower than the theoretical value; furthermore, during load fluctuations, the liquid level at the overflow weir is difficult to control precisely, easily leading to liquid seal failure causing gas leakage, or excessively high liquid levels causing tower flooding.

[0005] The second type is the pump cascade scheme. This scheme forces liquid transfer by configuring transfer pumps and regulating valves between each stage of the water tank. Its drawbacks are as follows: First, each stage needs to be independently equipped with a corrosion-resistant pump, flow meter, level gauge, and complex automatic control valve group, resulting in high initial investment and a complex electrical control system; Second, synthetic leather exhaust gas often contains viscous polyurethane prepolymer, resin particles, and dust impurities. After these substances accumulate in the circulating liquid, they are very easy to scale, adhere, or even block in the pump impeller, mechanical seal, valve core, and small pipelines, leading to a high equipment failure rate; Most seriously, if the transfer pump in an intermediate stage becomes stuck due to scaling or the valve malfunctions, the inter-stage flow will be interrupted. If there is a problem with the water outlet, the liquid level in this stage will be too high, causing flooding of the tower or even liquid backflow into the exhaust gas pipeline; if there is a problem with the water inlet or the liquid supply from the previous stage is interrupted, the liquid level in this stage will be too low, damaging the liquid seal at the bottom of the packing layer, causing high-concentration exhaust gas to "short-circuit" directly through the water tank without absorption, resulting in excessive emissions of tail gas. In addition, the long-term continuous operation of multiple pumps also leads to high energy consumption. Summary of the Invention

[0006] This application proposes a five-cycle DMF waste gas recovery device and recovery process, which abandons the traditional interstage pumping valve control mode and pioneers an interstage liquid distribution mechanism based on single-drive source rotation control of flexible guide tube displacement. This enables precise countercurrent replacement and dynamic mixing of the five-stage absorbent without direct contact between moving parts and corrosive media, completely solving the problems of pump and valve scaling and blockage and concentration gradient loss caused by high-viscosity DMF waste liquid.

[0007] To achieve the above objectives, this application adopts the following technical solution: a five-cycle DMF waste gas recovery device, comprising a spray tower body, the spray tower body having five spray chambers, each spray chamber having a spray pipe, and five collection boxes corresponding to the spray pipes respectively located below the spray tower body, the first collection box having an outlet, the fifth collection box having a water inlet, and a reflux assembly between the spray tower body and the collection boxes, the reflux assembly being positioned higher than the collection boxes and lower than the spray tower body, the reflux assembly including a reflux box and an adjusting cover, the reflux box having five reflux chambers arranged sequentially along the circumference, the adjusting cover having a reflux pipe, one end of the reflux pipe being connected to the corresponding spray chamber, and the other end being an outlet facing the corresponding reflux chamber, the adjusting cover also having a driving component, the driving component driving the outlet of the reflux pipe to move, causing the liquid inside to flow into the adjacent lower-level reflux chamber.

[0008] Furthermore, the reflux pipe is connected to a suspended replenishment hose, and the drive unit is connected to a drive arm. The drive arm rotates to move the replenishment hose, replenishing the adjacent lower-level reflux chamber.

[0009] Furthermore, the drive arm is a magnetic arm, and a magnet is provided at the end of the magnetic arm. The minimum gap between the magnetic arm and the fluid replenishment hose is 1-5mm, and the magnetic arm can drive the fluid replenishment hose to move through magnetic force.

[0010] Furthermore, the drive arm is a toggle arm, which bends in the opposite direction of rotation to the position of the replenishment hose, and the toggle arm can contact the replenishment hose.

[0011] Furthermore, an adjustment chamber is provided on one side of the reflux chambers of the second to fifth stages. The adjustment chamber is located on the side of the rotation direction of the drive component, and the bottom of the adjustment chamber is connected to the previous stage reflux chamber through an adjustment channel. The initial position of the actuating arm is located at the position corresponding to the first or second stage reflux chamber. This ensures that the sequence of liquid replenishment actions matches the rotational step sequence of the drive component.

[0012] Furthermore, to prevent damage to the fluid replenishment hose, a protective sleeve is provided on the fluid replenishment hose corresponding to the position of the lever arm, and the protective sleeve contacts the adjustment cap through a braided tube.

[0013] Furthermore, the replenishing hose is located in the middle of the reflux chamber, which is equipped with a high-flow outlet and a low-flow outlet. When the replenishing hose is fully extended, it can contact the solution. When the replenishing hose detaches, its end can be submerged in the solution, utilizing water resistance to reduce the loss of kinetic energy from the replenishing hose.

[0014] Furthermore, the return pipe is also connected to an inlet pipe, which is unaffected by the drive arm. This reduces the flow rate of the replenishment hose, making it easier for the hose to oscillate.

[0015] A five-cycle DMF waste gas recovery process is provided, which uses the aforementioned five-cycle DMF waste gas recovery equipment to recover DMF-containing waste gas.

[0016] The beneficial effects of this invention are as follows: The five-cycle DMF waste gas recovery equipment and recovery process provided in this application eliminate the traditional interstage transfer pump, regulating valve and complex pipeline. The only moving part (drive arm / magnetic arm) is located above the liquid surface or driven in a non-contact manner, which avoids the scaling and jamming of viscous polymer and resin particles inside the pump valve, and significantly improves the reliability of the equipment under harsh working conditions.

[0017] It does not require a large difference in civil engineering elevation (compared to the overflow method) or multiple high-power delivery pumps (compared to the pumping method). Only a small-power drive motor is needed to complete the flow control between all stages, which greatly reduces the footprint and operating energy consumption.

[0018] By using a single-axis sequential drive for the replenishment hose, precise timed and quantitative interstage liquid replacement is achieved. The replenishment path is clearly defined, replacing the traditional multi-valve control method, further simplifying the structure and improving the reliability of the equipment. At the same time, since the replenishment hose is suspended, its tilt angle during replenishment is also smaller, improving the reliability of the replenishment process. Even if the hose is damaged, most of the solution can still flow along the hose wall to the predetermined position. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort: Figure 1 is a schematic diagram of the structure of Embodiment 1 of the present invention; Figure 2 is a front view of the recirculation component in Embodiment 1 of the present invention; Figure 3 is a schematic diagram of the recirculation box in Embodiment 1 of the present invention; Figure 4 is a perspective view of the recirculation component in Embodiment 1 of the present invention; Figure 5 is an exploded view of the recirculation component in Embodiment 1 of the present invention; Figure 6 is a front view of the adjustment cover in Embodiment 1 of the present invention; Figure 7 is a bottom view of the adjustment cover in Embodiment 1 of the present invention; Figure 8 is a bottom view of the adjustment cover in Embodiment 2 of the present invention.

[0020] In the diagram: 1. Spray tower body; 2. Air inlet; 3. Exhaust outlet; 4. Spray chamber; 5. Spray pipe; 6. Defoamer; 7. Collection box; 8. Reflux assembly; 801. Reflux box; 802. Adjustment cover; 803. Reflux pipe; 804. Liquid outlet; 805. Drive component; 806. Reflux chamber; 807. Baffle plate; 808. Liquid replenishment hose; 809. Actuating arm; 810. Sensor; 811. Liquid inlet pipe; 812. Adjustment chamber; 813. Adjustment channel; 814. Step; 815. Low flow outlet; 816. High flow outlet; 817. Protective sleeve; 818. Braided hose; 819. Magnetic arm; 820. U-shaped tube; 9. Spray pump; 10. Water inlet; 11. Sampling outlet. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1, please refer to Figure 1, a five-cycle DMF waste gas recovery device, taking a horizontal type as an example, includes a horizontally arranged spray tower body 1, which has five spray chambers 4. The five spray chambers 4 are connected in series along the horizontal direction to achieve five-stage rinsing. A Z-shaped baffle is provided between two adjacent sets of spray chambers 4 to remove the solution carried in the airflow by using inertia. The tail end of the spray tower body 1 is provided with a defoamer 6 and an exhaust port 3. The airflow is discharged from the exhaust port 3 after being defoamed by the defoamer 6. The spray chambers 4 are provided with packing material. Spray pipes 5 are provided on both sides of the packing material. The spray pipes 5 spray solution onto the packing material to wet the packing material and form a liquid film to increase the absorption area. The front end of the spray tower body 1 is provided with an air inlet 2, which is connected to a fan.

[0023] Below the spray tower body 1, there are five collection tanks 7, which correspond one-to-one with the spray chambers 4. The first-stage spray chamber 4 corresponds to the first-stage collection tank 7, the second-stage spray chamber 4 corresponds to the second-stage collection tank 7, and so on. "Below" refers to the position below the height of the spray tower body 1. When the spray tower body 1 is on the ground, the collection tank 7 is located in the pit. The spray liquid in the spray tower body 1 can flow back to the collection tank 7 by gravity. The first-stage collection tank 7 is equipped with a sampling outlet 11, which is equipped with a concentration monitoring device. When the concentration of the first stage reaches the set concentration, the solution in the first-stage collection tank 7 is sampled out through the sampling outlet 11. The fifth-stage collection tank 7 is connected to a water inlet 10, through which clean water is added to the fifth-stage collection tank 7. Each collection tank 7 is connected to the corresponding spray pipe 5 through a spray pump.

[0024] A reflux assembly 8 is provided between the spray tower body 1 and the collection box 7. The reflux assembly 8 is positioned higher than the collection box 7 but lower than the spray tower body 1. The liquid can flow from the spray tower body 1 to the reflux assembly 8 by its own gravity, and then from the reflux assembly 8 to the collection box 7. (See Figures 2-7). The reflux assembly 8 includes a reflux box 801 and an adjusting cover 802. The reflux box 801 is provided with a partition 807, which divides the reflux box 801 into five reflux chambers 806. Each reflux chamber 806 is fan-shaped, and the reflux chambers 806 are connected to the collection boxes 7 at each stage. Corresponding to the spray chamber 4, the adjusting cover 802 is provided with a return pipe 803. One end of the return pipe 803 is connected to the corresponding spray chamber 4, and the outlet of the other end is located inside the adjusting cover 802 and is directly opposite the corresponding return chamber 806. The solution in each spray chamber 4 flows back to the corresponding collection box 7 through the corresponding return chamber 806. The adjusting cover 802 is also provided with a driving component 805. The driving component 805 drives the outlet of the return pipe 803 to move, so that the liquid inside flows to the adjacent return chamber 806, realizing interstage flow.

[0025] When treating exhaust gas, each spray pipe 5 draws solution from the corresponding collection tank 7 and sprays it out. The solution flows back to the corresponding return chamber 806 and finally back to the corresponding collection tank 7. When the concentration of the first stage reaches the set value and is collected, the level gauge detects that the liquid level has dropped and liquid needs to be replenished. The drive unit 805 drives the outlet of the second-stage return pipe 803 to move, so that the liquid inside flows to the adjacent first-stage return chamber 806 to replenish the first-stage collection tank 7. As the replenishment continues, the liquid level of each collection tank 7 decreases in turn, and the outlet of the adjacent higher-level return pipe 803 moves in turn to replenish it.

[0026] The return pipe 803 is connected to a suspended replenishment hose 808, the end of which is the outlet. The drive unit 805 is connected to a toggle arm 809. The toggle arm 809 rotates to move the replenishment hose 808, so that the end of the replenishment hose 808 passes over the partition 807 to replenish the adjacent return chamber 806.

[0027] An adjustment chamber 812 is provided on one side of the second to fifth stage reflux chambers 806. The adjustment chamber 812 is located on the side of the rotation direction of the drive component 805. The bottom of the adjustment chamber 812 is connected to the previous stage reflux chamber 806 through the adjustment channel 813. The initial position of the toggle arm 809 is located at the position corresponding to the first or second stage reflux chamber 806. When the toggle arm 809 rotates, it moves the replenishment hose 808 onto the adjustment chamber 812. The solution flows through the bottom of the adjustment channel 813 to the lower stage reflux chamber 806, so that the sequence of replenishment actions matches the rotation step sequence of the drive component. No additional control of the stop position and action process is required, reducing the control and drive structure and improving stability and reliability. The drive component 805 is a stepper motor, which can rotate a specific angle each time. In order to improve reliability, a sensor 810 is provided on the adjustment cover 802. The sensor 810 provides feedback on the stop position of the toggle arm 809 to ensure reliable movement each time. The sensor 810 can be a proximity switch or other sensing device.

[0028] The actuating arm 809 bends in the opposite direction of rotation to the position of the replenishing hose 808. When the replenishing hose 808 contacts the partition 807, it stops moving. At this time, if the actuating arm 809 continues to rotate, the bent part of the actuating arm 809 causes the replenishing hose 808 to move radially and eventually slide off the end of the actuating arm 809.

[0029] Because the replenishing hose 808 is squeezed at a specific position by the actuating arm 809, a protective sleeve 817 is provided on the replenishing hose 808 corresponding to the position of the actuating arm 809 to prevent the replenishing hose 808 from being damaged. The protective sleeve 817 contacts the adjusting cover 802 through the braided tube 818. The actuating arm 809 moves the replenishing hose 808 through the protective sleeve 817. When the replenishing hose 808 is squeezed onto the partition 807, the protective sleeve 817 can prevent the replenishing hose 808 from being deformed by pressure. The replenishing hose 808 is made of a soft material, which is convenient for swinging.

[0030] The replenishing hose 808 is located in the middle of the reflux chamber 806. The reflux chamber 806 has a high step 816 and two sets of outlets connected to the outlet 804, namely a high outlet 814 and a low outlet 815. The discharge from the low outlet 815 is slower, which allows for more contact in the reflux chamber 806. When the replenishing hose 808 is fully drooping, it can contact the solution. When the replenishing hose 808 falls off, the end of the replenishing hose 808 can be submerged in the solution. The resistance of the water buffers the swinging kinetic energy of the replenishing hose 808, making it stop quickly and avoiding repeated swinging of the replenishing hose 808. The replenishing hose 808 is far enough away from the adjustment chamber 812 so that the bottom can be raised enough during swinging and pass over the side wall of the adjustment chamber 812.

[0031] The return pipe 803 is also connected to the inlet pipe 811. The inlet pipe 811 is located outside the replenishment hose 808 and upstream of the replenishment hose 808, away from the actuating arm 809, and is not affected by the actuating arm 809. Most of the solution flows back from the inlet pipe 811 to the return chamber 806, reducing the flow rate of the replenishment hose 808 and making the replenishment hose 808 easier to swing.

[0032] A U-shaped pipe 820 is provided between the return pipe 803 and the spray chamber 4. The U-shaped pipe 820 seals the gas in the spray chamber 4 to prevent the gas from flowing directly from the return component 8 to the lower spray chamber 4 and to prevent short-circuiting.

[0033] In Example 2, in Example 1, the pressure exerted on the replenishment hose 808 by the actuating arm 809 may cause it to break. Furthermore, when replenishment is needed at a certain stage, each replenishment hose 808 still needs to be actuated sequentially; it cannot be moved directly. Therefore, as shown in Figure 8, in Example 2, a magnetic arm 819 replaces the actuating arm 809. The end of the magnetic arm 819 is equipped with a magnet. The minimum force between the magnetic arm 819 and the replenishment hose 808... The gap is 1-5mm. The protective sleeve 817 is made of magnetic material. When the magnetic arm 819 rotates, it approaches the replenishment hose 808 and magnetically attracts the protective sleeve 817, driving the replenishment hose 808 to move. When the intermediate collection tank 7 needs replenishment, the protective sleeve 817 rotates in the opposite direction to the position of the replenishment hose 808 of the previous stage, and then rotates in the forward direction to drive the replenishment hose 808 to replenish the liquid. Although the reverse rotation of the protective sleeve 817 will also cause the replenishment hose 808 to move, it will not cause a change in the liquid level of the collection tank 7.

[0034] Example 3: A five-cycle DMF waste gas recovery process. The DMF-containing waste gas generated by each oven and coating station in the production line is transported to the main pipeline through branch pipelines. The DMF waste gas in the main pipeline is filtered to remove the fluffy material generated in the oven, and then sent to the spray tower body 1 for treatment by a pressurized fan.

[0035] The exhaust gas passes through each stage of the spray chamber 4 sequentially. The spray pipes 5 in each stage of the spray chamber 4 spray the gas onto the packing material, forming a liquid film to absorb DMF from the exhaust gas. The solution concentrations in the first-stage collection tank 7 to the fifth-stage collection tank 7 are respectively: 30%–35%, 7%–10%, 1%–3%, 0.2%–0.8%, and 0%. When the solution concentration in the first-stage collection tank 7 exceeds 35%, the solution is extracted through the extraction outlet 11. The level gauge in the extraction outlet 11 detects a drop in the liquid level to a1, triggering the drive component 805 to move from its initial position one to position two. The actuating arm 809 actuates the second-stage replenishment hose 808, causing the replenishment hose 808 to... The solution reaches the upper part of the adjustment chamber 812 at the end of the flow path. The solution flows into the upper-level return chamber 806 through the adjustment chamber 812 and the adjustment channel 813. When the level gauge of the first-stage collection tank 7 detects that the liquid level has returned to A1, the drive component 805 rotates 72 degrees and moves from position two to position three, so that the third-stage return chamber 806 replenishes the second-stage collection tank 7 until the liquid level detected by the second-stage level gauge returns to A2. The drive component 805 then performs the set action until the fifth-stage return chamber 806 completes the replenishment of the fourth-stage collection tank 7, restoring its liquid level to A4. Finally, the inlet 10 is opened to replenish the fifth-stage collection tank 7 until its liquid level returns to A5.

[0036] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A five-cycle DMF waste gas recovery device, comprising a spray tower body (1), the spray tower body (1) having five spray chambers (4), each spray chamber (4) having a spray pipe (5), and five collection boxes (7) corresponding one-to-one with each spray pipe (5) being provided below the spray tower body (1), the first collection box (7) having an outlet (11), and the fifth collection box (7) being connected to a water inlet (10), characterized in that: A reflux assembly (8) is provided between the spray tower body (1) and the collection box (7). The reflux assembly (8) is positioned higher than the collection box (7) and lower than the spray tower body (1). The reflux assembly (8) includes a reflux box (801) and an adjusting cover (802). Five reflux chambers (806) are arranged sequentially along the circumference inside the reflux box (801). A reflux pipe (803) is provided on the adjusting cover (802). One end of the reflux pipe (803) is connected to the corresponding spray chamber (4), and the other end is the outlet, which faces the corresponding reflux chamber (806). A driving component (805) is also provided on the adjusting cover (802). The driving component (805) drives the outlet of the reflux pipe (803) to move, so that the liquid inside flows into the adjacent lower-level reflux chamber (806).

2. The five-cycle DMF waste gas recovery device according to claim 1, characterized in that, The return pipe (803) is connected to a suspended replenishment hose (808), and the drive unit (805) is connected to a drive arm. The drive arm rotates to move the replenishment hose (808) to replenish the adjacent lower-level return chamber (806).

3. The five-cycle DMF waste gas recovery device according to claim 2, characterized in that, The drive arm is a magnetic arm (819), and the end of the magnetic arm (819) is provided with a magnet. The minimum gap between the magnetic arm (819) and the fluid replenishment hose (808) is 1-5mm. The magnetic arm (819) can drive the fluid replenishment hose (808) to move by magnetic force.

4. The five-cycle DMF waste gas recovery device according to claim 2, characterized in that, The drive arm is a lever arm (809). The lever arm (809) bends in the opposite direction of rotation to the position of the replenishment hose (808), and the lever arm (809) can contact the replenishment hose (808).

5. A five-cycle DMF waste gas recovery device according to claim 3 or 4, characterized in that, On the reflux box (801), an adjustment cavity (812) is provided on one side of the second to fifth stage reflux cavities (806). The adjustment cavity (812) is located on one side of the rotation direction of the drive (805). The bottom of the adjustment cavity (812) is connected to the previous stage reflux cavity (806) through the adjustment channel (813). The initial position of the toggle arm (809) is located at the position corresponding to the first or second stage reflux cavity (806).

6. The five-cycle DMF waste gas recovery device according to claim 5, characterized in that, The fluid replenishment hose (808) is provided with a protective sleeve (817) corresponding to the position of the lever arm (809). The protective sleeve (817) contacts the adjustment cap (802) through the braided tube (818).

7. The five-cycle DMF waste gas recovery device according to claim 5, characterized in that, The replenishment hose (808) is located in the middle of the reflux chamber (806). The reflux chamber (806) is provided with a high flow outlet (814) and a low flow outlet (815). The replenishment hose (808) can contact the solution when it is fully lowered.

8. The five-cycle DMF waste gas recovery device according to claim 5, characterized in that, The return pipe (803) is also connected to the inlet pipe (811), which does not move with the drive arm.

9. A five-cycle DMF waste gas recovery process, characterized in that, The five-cycle DMF waste gas recovery device described in claim 3 or 4 is used to recover DMF-containing waste gas.

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