A NMP recovery system and recovery method for positive electrode coating machine

Abstract

The present application relates to the technical field of waste gas treatment, and specifically discloses a NMP recovery system and recovery method for a positive electrode coating machine, which includes a heat exchange unit, the tail gas inlet end of the heat exchange unit is used to connect with the outlet end of the oven, and the purified gas outlet end of the heat exchange unit is used to connect with the inlet end of the oven; a water washing unit, including a recovery tower and a water washing device arranged in the recovery tower, the inlet end of the recovery tower is connected with the tail gas outlet end of the heat exchange unit; a gas-liquid separation condensation unit, connected with the outlet end of the recovery tower, the gas-liquid separation condensation unit includes a liquid recovery device and a gas recovery pipeline, the liquid recovery device is used to liquefy and recover NMP, and the gas recovery pipeline is used to recover the tail gas after condensation and liquefaction treatment; wherein, the gas recovery pipeline is connected to the purified gas inlet end of the heat exchange unit after passing through the inside of the recovery tower. The present application can enhance the recovery effect of NMP in the tail gas.

Description

Technical Field

[0001] The present application relates to the technical field of waste gas treatment, and in particular to an NMP recovery system and a recovery method for a positive electrode coating machine. Background Art

[0002] In lithium-ion batteries, the positive electrode is made by coating a slurry made of a mixture of conductive materials, binders and conductive additives on aluminum foil or other conductive substrates. The positive electrode coater is one of the key equipment used to manufacture the positive electrode of lithium-ion batteries. The function of the positive electrode coater is to evenly coat the positive electrode slurry on the conductive substrate of the battery positive electrode.

[0003] The positive electrode coating machine includes a slurry supply device, a coating device, a drying device and a winding device. When the positive electrode coating machine is working, the slurry supply device can first mix the required slurry, then the coating device coats the slurry on the conductive substrate, then the conductive substrate is dried by the drying device, and finally the dried conductive substrate is wound into a roll for subsequent processing.

[0004] The slurry used to coat the conductive substrate usually contains NMP, which is N-methylpyrrolidone. It is an organic solvent. It is a colorless and transparent liquid with high solubility and strong polarity. It can be used to dissolve and carry positive electrode materials. However, NMP has certain volatility and toxicity. When the positive electrode coating machine is drying the conductive substrate, some NMP will be discharged with the exhaust gas.

[0005] If the NMP in the tail gas is not recovered, it will result in a waste of raw materials and will also have an impact on the environment and the health of workers.

[0006] In this regard, the Chinese patent with publication number CN110252089A discloses an organic gas recovery system for the upper oven of a coating machine, and its technical key points are: including a first exhaust fan, an air-to-air heat exchanger, a recovery tower, a second exhaust fan, a first circulation device, a second circulation device, a first heat exchanger, and a second heat exchanger. The recovery tower includes a first recovery device and a second recovery device located above the first recovery device; a first receiving chamber and a first adsorption device are provided in the first recovery device; a second receiving chamber and a second adsorption device are provided in the second recovery device. The first circulation device is respectively connected to the first receiving chamber and the space located above the first adsorption device in the first recovery device; the second circulation device is respectively connected to the second receiving chamber and the space located above the second adsorption device in the second recovery device.

[0007] In the above device, the NMP in the tail gas is adsorbed by the water in the recovery tower, thereby realizing the recovery of NMP. Since the first receiving chamber and the second receiving chamber in the recovery tower are in a connected state, the tail gas is in a state of continuous flow during the recovery process, and the tail gas stays in the recovery tower for a short time, so the tail gas and the water in the recovery tower are in contact for a short time, making it difficult for the tail gas to fully contact with the water, thereby easily reducing the recovery effect of the NMP in the tail gas. Summary of the invention

[0008] In order to enhance the recovery effect of NMP in tail gas, the present application provides an NMP recovery system and a recovery method for a cathode coating machine.

[0009] The present application provides an NMP recovery system and recovery method for a positive electrode coating machine using the following technical solutions:

[0010] In the first aspect, the present application provides an NMP recovery system for a positive electrode coating machine, which adopts the following technical solution:

[0011] An NMP recovery system for a cathode coating machine, comprising:

[0012] A heat exchange unit, wherein the tail gas inlet end of the heat exchange unit is used to be connected to the gas outlet end of the oven, and the purified gas outlet end of the heat exchange unit is used to be connected to the gas inlet end of the oven;

[0013] A water washing unit, comprising a recovery tower and a water washing device disposed in the recovery tower, wherein the air inlet end of the recovery tower is connected to the tail gas outlet end of the heat exchange unit, and the water washing device is used to absorb NMP in the tail gas;

[0014] A gas-liquid separation and condensing unit is connected to the gas outlet end of the recovery tower, and the gas-liquid separation and condensing unit includes a liquid recovery device and a gas recovery pipeline. The liquid recovery device is used to liquefy and recover NMP, and the gas recovery pipeline is used to recover the tail gas after condensation and liquefaction treatment; wherein the gas recovery pipeline is connected to the purified gas inlet end of the heat exchange unit after passing through the inside of the recovery tower.

[0015] By adopting the above technical solution, the tail gas discharged from the oven first enters the water washing unit, the water washing unit preliminarily absorbs NMP in the tail gas, and then the tail gas enters the gas-liquid separation condensation unit, the gas-liquid separation condensation unit liquefies the NMP in the tail gas, and then separates the NMP in the tail gas again, which helps to improve the recovery rate of NMP in the tail gas, so as to better recycle and utilize NMP; since a part of the gas recovery pipeline is located inside the recovery tower, when the tail gas with a lower temperature after condensation enters the gas recovery pipeline located in the recovery tower, it can exchange heat with the high-temperature tail gas that has just entered the recovery tower, on the one hand, the condensed tail gas is preliminarily heated up, and the heat utilization rate is improved, and on the other hand, the high-temperature tail gas that has just entered the recovery tower can be cooled down, so that part of the NMP in it is liquefied, and then the liquefied NMP falls to the bottom of the recovery tower, thereby improving the recovery rate of NMP.

[0016] Optionally, the water washing device includes a spray mechanism, which includes a pump body, a connecting pipe, a spray pipe and a nozzle. The pump body is arranged on a recovery tower, the water inlet end of the pump body is connected to the interior of the recovery tower, the water outlet end of the pump body is connected to the connecting pipe, the end of the connecting pipe away from the pump body is located at the top of the recovery tower and is connected to the spray pipe. The nozzle is arranged on the spray pipe, and the nozzle is connected to the interior of the spray pipe.

[0017] By adopting the above technical solution, water is arranged at the bottom of the recovery tower. After the pump body draws the water into the connecting pipe and the spray pipe, the water is sprayed out from the nozzle. The sprayed water contacts the rising tail gas in the recovery tower, thereby absorbing NMP in the tail gas, thereby realizing the recovery of NMP in the tail gas.

[0018] Optionally, the spray pipe includes a main pipe and a branch pipe, the main pipe and the connecting pipe are rotatably connected, the branch pipe is arranged on the main pipe, the branch pipe is communicated with the main pipe, a plurality of branch pipes are provided, and the branch pipes are arranged along the height direction of the recovery tower, a plurality of nozzles are provided, and are arranged on the branch pipes at intervals along the length direction of the branch pipes, and a driving mechanism is also provided in the recovery tower, the driving mechanism includes a rotating power member, a driving gear and a driven gear, the rotating power member is arranged on the recovery tower, the driving gear and the output end of the rotating power member are coaxially connected, the driven gear is arranged on the main pipe, the driven gear and the rotation axis of the main pipe are coaxially arranged, and the driving gear and the driven gear are meshed.

[0019] By adopting the above technical solution, after the rotating power part is started, the main pipe can be driven to rotate with the cooperation of the driving gear and the driven gear. When the main pipe rotates, the branch pipe is driven to rotate, and the branch pipe drives the nozzle to rotate. The nozzle sprays water while rotating, thereby expanding the spray range and the contact area between the sprayed water mist and the exhaust gas, so that the exhaust gas can fully contact with the water, which helps to improve the recovery rate of NMP in the exhaust gas; in addition, dynamic spraying can avoid dead angles or blind spots that may exist in static spraying, so the coverage effect of water mist is better.

[0020] Optionally, a support plate is provided in the recovery tower, and a plurality of the support plates are provided. The plurality of support plates are spaced apart along the height direction of the recovery tower, a plurality of water storage tanks are provided on one side of the support plate close to the top of the recovery tower, and a plurality of drainage holes are provided on the support plate.

[0021] By adopting the above technical solution, the support plate can slow down the rising speed of the exhaust gas in the recovery tower, so that the exhaust gas can have more time to contact with the sprayed water mist, thereby improving the recovery rate of NMP in the exhaust gas; the setting of the water storage tank allows water to be stored on the support plates at different heights in the recovery tower, so that in addition to contacting with the sprayed water mist during the rising process of the gas, it can also contact with the water in the water storage tank, thereby enhancing the absorption effect of NMP in the exhaust gas; the setting of the drainage hole facilitates the upward flow of the exhaust gas on the one hand, and facilitates the downward flow of the water in the water storage tank on the other hand, thereby further enhancing the absorption effect of NMP in the exhaust gas.

[0022] Optionally, the portion of the gas recovery pipeline located in the recovery tower is located on the side of the branch pipe close to the top of the recovery tower, and the portion of the gas recovery pipeline located in the recovery tower is in a serpentine tube shape.

[0023] By adopting the above technical solution, the serpentine tubular structure can expand the contact area between the condensed exhaust gas and the exhaust gas in the recovery tower, thereby enhancing the heat exchange effect and saving more energy.

[0024] Optionally, an electromagnetic one-way valve is provided at the gas outlet end of the recovery tower, and the electromagnetic one-way valve is used to allow the tail gas in the recovery tower to enter the gas-liquid separation condensation unit in one direction. An air pressure sensor and a controller are provided in the recovery tower, and the controller is electrically connected to the air pressure sensor and the electromagnetic one-way valve respectively.

[0025] By adopting the above technical solution, after the electromagnetic one-way valve is closed, the exhaust gas discharged from the oven can be continuously accumulated after entering the recovery tower. When the air pressure sensor detects that the air pressure in the recovery tower reaches a preset value, the electromagnetic one-way valve is opened again, so that the treated exhaust gas is discharged into the gas-liquid separation condensation unit; thus, the exhaust gas in the recovery tower and the sprayed water mist can have a more sufficient contact time, thereby enhancing the recovery effect of NMP in the exhaust gas; since the electromagnetic one-way valve is provided, the recovery tower can have a good recovery effect even if it is only provided with one layer structure, and there is no need to provide the recovery tower with a multi-layer structure, which can reduce the space occupied by the recovery tower.

[0026] Optionally, a storage box is arranged between the exhaust gas outlet end of the heat exchange unit and the air inlet end of the recovery tower, and a power telescopic part is arranged at the outlet of the storage box. The power telescopic part is electrically connected to the controller, and a baffle is arranged at the movable end of the power telescopic part, and the baffle is used to control the opening and closing of the storage box outlet.

[0027] By adopting the above technical solution, after the electromagnetic one-way valve is closed, the exhaust gas discharged from the oven continuously enters the recovery tower. When the air pressure sensor detects that the air pressure in the recovery tower reaches the preset value, the power telescopic part drives the baffle to slide, so that the baffle blocks the outlet of the storage box. At this time, the exhaust gas entering the recovery tower can be isolated inside the recovery tower, so that the exhaust gas just entering the recovery tower can have a more sufficient purification time, thereby enhancing the recovery effect.

[0028] Optionally, a mixing device is provided in the recovery tower, and the mixing device includes a plurality of fans arranged in the recovery tower, and the fans are electrically connected to a controller.

[0029] By adopting the above technical solution, when the electromagnetic one-way valve is in a closed state and the baffle closes the outlet of the storage box, the fan is turned on, thereby increasing the air flow rate in the recovery tower and allowing the air in the recovery tower to circulate. Therefore, the exhaust gas in the recovery tower and the sprayed water mist can be more fully in contact, thereby enhancing the recovery effect.

[0030] Optionally, an activated carbon adsorption plate is provided at the gas outlet end of the recovery tower.

[0031] By adopting the above technical solution, the activated carbon adsorption plate can adsorb moisture in the exhaust gas, thereby drying the exhaust gas, which is convenient for ensuring the subsequent use effect of the oven.

[0032] In a second aspect, the present application provides a recycling method, which adopts the following technical solution:

[0033] A recycling method, using any of the above-mentioned NMP recycling systems for positive electrode coating machines, comprises the following steps:

[0034] a. The tail gas discharged from the outlet of the oven passes through the heat exchange unit and then enters the recovery tower;

[0035] b. The water washing device in the recovery tower absorbs NMP in the tail gas. After passing through the water washing device, the tail gas is discharged from the recovery tower to the gas-liquid separation condensation unit;

[0036] c. The gas-liquid separation condensation unit cools down the tail gas, liquefies the NMP in the tail gas, and the liquefied NMP enters the liquid recovery device, and the rest of the tail gas enters the gas recovery pipeline;

[0037] d. The tail gas flows into the gas recovery pipeline in the recovery tower, and the tail gas in the gas recovery pipeline and the tail gas in the recovery tower are preliminarily heat exchanged, so that the tail gas in the gas recovery pipeline is heated up, and the tail gas in the recovery tower is cooled down, and then part of the NMP in the tail gas in the recovery tower is liquefied and flows to the bottom of the recovery tower;

[0038] f. The tail gas in the gas recovery pipeline flows into the heat exchange unit and exchanges heat with the tail gas discharged from the oven again. The tail gas after heat exchange flows into the oven through the air inlet end of the oven.

[0039] By adopting the above technical solution, after the tail gas in the oven is discharged, it first enters the recovery tower, and the water in the recovery tower can preliminarily absorb the NMP in the tail gas. Then the tail gas flows into the gas-liquid separation condensation unit, the tail gas is cooled, and the NMP in the tail gas is liquefied and then separated, thereby improving the recovery effect of NMP in the tail gas.

[0040] In summary, the present application includes at least one of the following beneficial technical effects:

[0041] 1. The combination of water absorption and condensation separation helps to improve the recovery rate of NMP in the tail gas, facilitates the reuse of the recovered NMP, and reduces production costs.

[0042] 2. A portion of the gas recovery pipeline is located in the recovery tower, so that the condensed tail gas in the gas recovery pipeline can exchange heat with the tail gas in the recovery tower, thereby preliminarily heating the tail gas in the gas recovery pipeline, which helps to reduce energy consumption and can also liquefy part of the NMP in the tail gas in the recovery tower, thereby further improving the separation effect of NMP in the tail gas.

[0043] 3. The combination of electromagnetic one-way valve, air pressure sensor, power telescopic parts and baffle can prolong the residence time of tail gas in the recovery tower, so that the tail gas can contact with water more fully, thereby improving the recovery rate of NMP in the tail gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the structural principle of an embodiment of the present application;

[0045] Figure 2 It is a schematic structural diagram of the recovery tower of the embodiment of the present application;

[0046] Figure 3 This is a schematic diagram of an embodiment of the present application for showing the structure of a gas recovery pipeline located inside a recovery tower;

[0047] Figure 4 is a cross-sectional view of the first viewing angle of the embodiment of the present application;

[0048] Figure 5 It is a cross-sectional view from a second viewing angle of the embodiment of the present application.

[0049] Figure numerals: 1. oven; 2. gas-to-gas heat exchanger; 3. recovery tower; 4. spray mechanism; 41. pump body; 42. connecting pipe; 43. spray pipe; 431. main pipe; 432. branch pipe; 44. nozzle; 5. driving mechanism; 51. rotating power part; 52. driving gear; 53. driven gear; 6. gas-liquid separation condensation unit; 61. separation main device; 62. liquid recovery device; 63. gas recovery pipeline; 7. support plate; 71. water storage tank; 72. drain hole; 8. electromagnetic one-way valve; 9. air pressure sensor; 10. storage box; 11. power telescopic part; 12. baffle; 13. fan; 14. activated carbon adsorption plate; 15. first exhaust fan; 16. second exhaust fan; 17. guide pipe; 18. valve; 19. collection box. DETAILED DESCRIPTION

[0050] The following is combined with Figure 1-5 This application is described in further detail.

[0051] The present application discloses an NMP recovery system and a recovery method for a positive electrode coating machine. Figure 1 The NMP recovery system for the positive electrode coating machine is arranged on one side of the oven 1, and the recovery system includes a heat exchange unit, a water washing unit and a gas-liquid separation condensation unit 6. The first exhaust fan 15 is arranged at both the air outlet and the air inlet of the oven 1, and the air outlet of the oven 1 is connected to the air inlet of the corresponding first exhaust fan 15, and the air inlet of the oven 1 is connected to the air outlet of the corresponding first exhaust fan 15. The tail gas discharged from the oven 1 is 98°C. After the tail gas in the oven 1 is discharged, it flows into the heat exchange unit, the water washing unit and the gas-liquid separation condensation unit 6 in sequence, and then flows into the other end of the heat exchange unit, and then flows into the oven 1 to participate in the hot air circulation in the oven 1.

[0052] The heat exchange unit includes an air-to-air heat exchanger 2, which is also called an air heat exchanger or a heat exchanger. The air-to-air heat exchanger 2 can transfer heat from one gas to another gas. The outlet of the oven 1 is connected to the exhaust gas inlet of the air-to-air heat exchanger 2, and the exhaust gas outlet of the air-to-air heat exchanger 2 is connected to the water washing unit. Therefore, the exhaust gas discharged from the oven 1 is initially cooled to 73°C after passing through the air-to-air heat exchanger 2, and then flows into the water washing unit.

[0053] Reference Figure 1 and Figure 2 The water washing unit includes a recovery tower 3 and a water washing device arranged in the recovery tower 3. The recovery tower 3 is arranged between the gas-to-gas heat exchanger 2 and the gas-liquid separation condensation unit 6, and the height direction of the recovery tower 3 is arranged vertically; the bottom of the recovery tower 3 is filled with water, and the bottom of the recovery tower 3 is provided with an air inlet; the air inlet is located above the water surface in the recovery tower 3, and the air inlet is connected to the tail gas outlet of the gas-to-gas heat exchanger 2. The top of the recovery tower 3 is provided with an air outlet, and the air outlet of the recovery tower 3 is connected to the second exhaust fan 16, the air outlet of the recovery tower 3 is connected to the air inlet of the second exhaust fan 16, and the air outlet of the second exhaust fan 16 is connected to the air inlet of the gas-liquid separation condensation unit 6. Therefore, after the tail gas is passed into the recovery tower 3, the water in the recovery tower 3 can preliminarily absorb the NMP in the tail gas. The water washing device is arranged above the water surface in the recovery tower 3, and the water washing device can further process the tail gas, thereby absorbing the NMP in the tail gas.

[0054] Reference Figure 2 and Figure 3 , the gas-liquid separation condensation unit 6 comprises a separation main device 61, a liquid recovery device 62 and a gas recovery pipeline 63. The separation main device 61 is a condenser, which can realize the separation of gas phase and liquid phase, and is a prior art, and the specific structure is not repeated here. The air inlet end of the separation main device 61 is connected to the air outlet end of the recovery tower 3, and the air outlet end of the separation main device 61 is connected to the gas recovery pipeline 63. Therefore, the tail gas entering the separation main device 61 can be cooled, so that the NMP in the tail gas is cooled to below the saturation temperature, and the NMP in the tail gas condenses into liquid, thereby realizing gas-liquid separation. The liquid recovery device 62 is connected to the separation main device 61, so that the condensed NMP can enter the liquid recovery device 62 for the collection of NMP.

[0055] The end of the gas recovery pipe 63 away from the separation main device 61 penetrates into the recovery tower 3, and then passes out from the other side of the recovery tower 3. The part that passes out is connected to the purified gas inlet end of the gas-to-gas heat exchanger 2, and the purified gas outlet end of the gas-to-gas heat exchanger 2 is connected to the inlet end of the oven 1. Therefore, the tail gas after condensation and separation first enters the part of the gas recovery pipe 63 located in the recovery tower 3. At this time, the condensed tail gas with a lower temperature and the tail gas with a higher temperature that has just entered the recovery tower 3 are preliminarily heat-exchanged, so that the tail gas in the gas recovery pipe 63 is preliminarily heated to 35°C; then the tail gas in the gas recovery pipe 63 flows into the gas-to-gas heat exchanger 2 again, and exchanges heat with the 98°C tail gas discharged from the oven 1, and is heated again to 79°C; the heated tail gas is discharged into the oven 1, and then partially circulated with fresh air introduced from the outside, which reduces energy consumption while ensuring uniform temperature in the oven 1 and dries the conductive substrate in the oven 1. Furthermore, the portion of the gas recovery pipe 63 located in the recovery tower 3 is configured as a serpentine tube, thereby helping to expand the heat exchange area, enhance the heat exchange effect, and thus reduce energy consumption.

[0056] Reference Figure 4 The water washing device includes a spray mechanism 4, which includes a pump body 41, a connecting pipe 42, a spray pipe 43 and a nozzle 44. The pump body 41 is a water pump, which is fixedly connected to the outer wall at the bottom of the recovery tower 3, the water inlet end of the pump body 41 is connected to the bottom of the recovery tower 3, and the water outlet end of the pump body 41 is connected to the connecting pipe 42. The end of the connecting pipe 42 away from the pump body 41 extends to the top of the recovery tower 3, the end of the connecting pipe 42 passes through the top wall of the recovery tower 3, and the end of the connecting pipe 42 located in the recovery tower 3 is arranged in the vertical direction. The spray pipe 43 is arranged at the end of the connecting pipe 42 away from the pump body 41, and the spray pipe 43 is connected to the inside of the connecting pipe 42. The nozzle 44 is an atomizing nozzle, which is arranged on the spray pipe 43, and the nozzle 44 is connected to the inside of the spray pipe 43. Therefore, after the pump body 41 is started, the water in the recovery tower 3 can be pumped into the connecting pipe 42 and the spray pipe 43, and then the water is sprayed out from the nozzle 44 on the spray pipe 43, thereby forming water mist, so that the rising tail gas in the recovery tower 3 contacts the water mist, thereby enhancing the recovery rate of NMP in the tail gas.

[0057] Furthermore, the spray pipe 43 includes a main pipe 431 and a branch pipe 432. The main pipe 431 is in a T-shaped tube shape, and is provided with three openings, one of which is sleeved on the outside of one end of the connecting pipe 42 located in the recovery tower 3, and is rotatably connected to the connecting pipe 42; a rotating seal is provided between this opening and the connecting pipe 42. There are two branch pipes 432; the other two symmetrically arranged openings of the main pipe 431 are arranged in the horizontal direction, and the two openings are respectively fixedly connected to a branch pipe 432. The branch pipe 432 is arranged in the vertical direction, and the branch pipe 432 is connected to the main pipe 431; there are multiple nozzles 44, and they are spaced apart along the length direction of the branch pipe 432. Therefore, after the main pipe 431 rotates, it can drive the branch pipe 432 and the nozzle 44 to rotate, so that the nozzle 44 can rotate while spraying water, thereby expanding the spray range and enhancing the absorption effect of NMP in the tail gas.

[0058] The washing device also includes a driving mechanism 5, which includes a rotating power member 51, a driving gear 52 and a driven gear 53. The rotating power member 51 is a motor, which is fixedly connected to the top wall of the recovery tower 3 by bolts, and the output shaft of the rotating power member 51 is vertically downward, and the output shaft of the rotating power member 51 penetrates into the interior of the recovery tower 3. The driving gear 52 is coaxially fixedly connected to the output shaft of the rotating power member 51, and the driving gear 52 is located inside the recovery tower 3. The driven gear 53 is fixedly arranged on the outer wall of the main pipe 431, and the rotation axis of the driven gear 53 and the main pipe 431 is coaxially arranged; the driven gear 53 and the driving gear 52 are meshed. Therefore, after the rotating power member 51 is started, the driving gear 52 can be driven to rotate, the driving gear 52 drives the driven gear 53 to rotate, and the driven gear 53 drives the main pipe 431 to rotate, thereby driving the branch pipe 432 and the corresponding nozzle 44 to rotate, and realizing dynamic spraying.

[0059] Reference Figure 3 and Figure 5 It should be noted that the portion of the gas recovery pipe 63 located in the recovery tower 3 is at the top of the recovery tower 3, and the gas recovery pipe 63 is located above the driving gear 52 and the driven gear 53. Therefore, when the driving mechanism 5 drives the main pipe 431 and the branch pipe 432 to rotate, there will be no interference with the gas recovery pipe 63.

[0060] When the water washing device is working, the water and the tail gas can be fully contacted to absorb the NMP in the tail gas; after working for a period of time, the concentration of NMP in the water reaches the required level. In order to facilitate the removal of the NMP solution in the recovery tower 3, refer to Figure 4, the connecting pipe 42 is also connected to the guide pipe 17, and the guide pipe 17 is in communication with the connecting pipe 42. The guide pipe 17 is provided with a valve 18, and the end of the guide pipe 17 away from the connecting pipe 42 is connected to the collecting box 19. When the valve 18 is closed, the water in the recovery tower 3 can circulate continuously between the recovery tower 3 and the connecting pipe 42; when the valve 18 is opened, the pump body 41 can pump the NMP aqueous solution in the recovery tower 3 into the collecting box 19, thereby recycling the NMP aqueous solution in the collecting box 19 and reducing the production cost.

[0061] In order to extend the time that the tail gas stays in the recovery tower 3 and enhance the absorption effect of NMP in the tail gas, a support plate 7 is provided in the recovery tower 3. The support plate 7 is fixedly connected to the bottom wall of the recovery tower 3, and a plurality of support plates 7 are provided, and are evenly spaced and distributed in the vertical direction. The plate surface of the support plate 7 is arranged horizontally, and the support plate 7 is located between the two branch pipes 432. Therefore, a plurality of support plates 7 can block the tail gas flowing upward and slow down the flow rate of the tail gas. A water storage tank 71 is provided on the top surface of the support plate 7, and a plurality of water storage tanks 71 are provided, and water is stored in the water storage tank 71; the water in the water storage tank 71 can also absorb NMP in the tail gas, thereby further enhancing the absorption effect of NMP in the tail gas. The support plate 7 is also provided with a drainage hole 72, which is a through hole. A plurality of drainage holes 72 are provided, and the drainage holes 72 and the water storage tank 71 are staggered. Therefore, with the spraying of the nozzle 44, when the water in the water storage tank 71 is full, the water in the water storage tank 71 can flow down through the drainage hole 72, thereby forming multiple water columns in the recovery tower 3, increasing the contact area with the tail gas, thereby enhancing the absorption effect of NMP.

[0062] In order to further extend the time that the tail gas stays in the recovery tower 3, refer to Figure 5 , a controller is provided on the recovery tower 3, and an electromagnetic one-way valve 8 is provided at the gas outlet end of the recovery tower 3, and the electromagnetic one-way valve 8 is electrically connected to the controller; the electromagnetic one-way valve 8 allows the tail gas in the recovery tower 3 to enter the gas-liquid separation condensation unit 6 only from the recovery tower 3. A pressure sensor 9 is also provided in the recovery tower 3, and the pressure sensor 9 can be used to detect the air pressure in the recovery tower 3, and the pressure sensor 9 is electrically connected to the controller. During the tail gas treatment, the electromagnetic one-way valve 8 is first in a closed state, and then the tail gas discharged from the oven 1 continuously enters the recovery tower 3 after heat exchange, so that the air pressure in the recovery tower 3 gradually increases; when the air pressure in the recovery tower 3 increases to a preset value, the pressure sensor 9 causes the controller to operate, and the controller causes the electromagnetic one-way valve 8 to open, so that the tail gas in the recovery tower 3 enters the gas separation condensation unit for subsequent treatment; therefore, the setting of the electromagnetic one-way valve 8 allows the tail gas in the recovery tower 3 to have more sufficient purification time.

[0063] After the electromagnetic one-way valve 8 is opened, the tail gas in the recovery tower 3 can be discharged from the recovery tower 3, but at this time, the tail gas newly generated by the oven 1 still enters the recovery tower 3. This part of the newly entered tail gas may be directly discharged from the recovery tower 3 after the electromagnetic one-way valve 8 is opened, which is easy to affect the recovery effect of NMP in the tail gas. In order to reduce this effect, refer to Figure 1 and Figure 4 A storage box 10 is provided between the tail gas outlet end of the gas-to-gas heat exchanger 2 and the gas inlet end of the recovery tower 3 .

[0064] The inlet of the storage box 10 is connected to the exhaust gas outlet of the gas-to-gas heat exchanger 2, and the outlet of the storage box 10 is connected to the air inlet of the recovery tower 3. A power telescopic member 11 is fixedly connected to the outlet of the storage box 10. The power telescopic member 11 is a cylinder, and the power telescopic member 11 is electrically connected to the controller. The piston rod of the power telescopic member 11 is vertically arranged downward, and a baffle 12 is fixedly connected to the end of the piston rod of the power telescopic member 11. The area of ​​the baffle 12 is slightly larger than the outlet of the storage box 10, so that the baffle 12 can block the outlet of the storage box 10.

[0065] During tail gas treatment, the electromagnetic one-way valve 8 is closed first, and then as the tail gas continues to flow in, the air pressure in the recovery tower 3 increases; when the air pressure increases to a preset value, the piston rod of the power telescopic member 11 extends, so that the baffle 12 moves down, and the baffle 12 blocks the outlet of the storage box 10, and the tail gas discharged from the oven 1 enters the storage box 10 for temporary storage; at this time, the tail gas in the recovery tower 3 can fully contact with water, thereby absorbing NMP in the tail gas. After a period of time, the controller drives the electromagnetic one-way valve 8 to open again, and the purified tail gas in the recovery tower 3 flows out; then the electromagnetic one-way valve 8 is closed again, and the piston rod of the power telescopic member 11 is retracted, so that the baffle 12 moves up, the outlet of the storage box 10 is opened, and the tail gas discharged from the oven 1 continues to enter the recovery tower 3 for treatment. Therefore, the setting of the storage box 10 allows the tail gas that enters the recovery tower 3 successively to have a relatively sufficient time to contact with the water in the recovery tower 3, thereby enhancing the recovery effect of NMP in the tail gas.

[0066] Further, refer to Figure 4 and Figure 5 A mixing device is also provided in the recovery tower 3, and the mixing device includes a plurality of fans 13 fixedly connected to the inner wall of the recovery tower 3, and the fans 13 are electrically connected to the controller. The fans 13 are arranged at the top of the recovery tower 3, and the blowing direction of the fans 13 is tilted downward. Therefore, when the electromagnetic one-way valve 8 is in a closed state, and the baffle 12 closes the outlet of the storage box 10, the fan 13 is turned on, so that the tail gas in the recovery tower 3 circulates, accelerates the mixing of the tail gas and the water mist sprayed by the nozzle 44, and enhances the recovery effect of NMP in the tail gas.

[0067] Reference Figure 5The outlet end of the recovery tower 3 is also provided with an activated carbon adsorption plate 14, which includes a frame and an activated carbon layer installed in the frame; therefore, the activated carbon adsorption plate 14 can adsorb moisture in the purified exhaust gas, thereby ensuring the subsequent working effect of the oven 1.

[0068] The implementation principle of the NMP recovery system for a positive electrode coating machine in the embodiment of the present application is as follows: in the initial state, the electromagnetic one-way valve 8 is in a closed state; the exhaust gas discharged from the oven 1 enters the gas-to-gas heat exchanger 2, the storage box 10 and the recovery tower 3 in sequence; the pump body 41 and the rotating power part 51 are started, and the pump body 41 draws the water in the recovery tower 3 into the nozzle 44, and then sprays water mist from the nozzle 44; after the rotating power part 51 is started, with the cooperation of the driving gear 52 and the driven gear 53, the main pipe 431 and the branch pipe 432 are driven to rotate, and the branch pipe 432 drives the nozzle 44 to rotate, so that the nozzle 44 sprays water while rotating, thereby expanding the contact area between the water mist and the exhaust gas and fully absorbing the NMP in the exhaust gas.

[0069] As the tail gas continues to enter the recovery tower 3, the air pressure in the recovery tower 3 gradually increases. When the air pressure in the recovery tower 3 reaches a preset value, the air pressure sensor 9 causes the controller to operate, and the controller causes the piston rod of the power telescopic member 11 to extend, and the baffle 12 to move down, and the baffle 12 blocks the outlet of the storage box 10; at this time, the air inlet and outlet ends of the recovery tower 3 are closed, and the fan 13 starts to work. After the fan 13 is started, the tail gas in the recovery tower 3 can be circulated, thereby further enhancing the absorption effect of NMP in the tail gas.

[0070] After the tail gas in the recovery tower 3 is treated for a period of time, the electromagnetic one-way valve 8 is opened, and the treated tail gas is discharged from the recovery tower 3 to the separation main device 61; then the electromagnetic one-way valve 8 is closed, and at the same time, the power telescopic part 11 drives the baffle 12 to move upward, so that the outlet of the storage box 10 is opened; the tail gas in the oven 1 can continue to flow into the recovery tower 3 for treatment.

[0071] The tail gas entering the separation main device 61 is cooled during the flow, and the NMP in the tail gas is liquefied, and then the liquefied NMP flows into the liquid recovery device 62.

[0072] Then, the tail gas after condensation treatment flows into the gas recovery pipe 63. When the tail gas flows into the serpentine part of the gas recovery pipe 63, the tail gas with a lower temperature in the gas recovery pipe 63 and the tail gas with a higher temperature in the recovery tower 3 exchange heat, so that the tail gas in the recovery tower 3 is cooled, and part of the NMP is separated after liquefaction, and the liquefied NMP falls into the bottom of the recovery tower 3; at the same time, the tail gas in the gas recovery pipe 63 is initially heated. Then the tail gas flows into the gas-to-gas heat exchanger 2, and the purified tail gas exchanges heat with the tail gas just flowing out of the oven 1, so that the purified tail gas is heated again; then the purified tail gas flows into the oven 1 and participates in the circulation inside the oven 1.

[0073] The present application also discloses a recycling method, comprising the following steps:

[0074] Step a. The exhaust gas discharged from the oven 1 enters the gas-to-gas heat exchanger 2, the storage box 10 and the recovery tower 3 in sequence, and then gathers in the recovery tower 3.

[0075] Step b. The pump body 41 pumps the water in the recovery tower 3 into the connecting pipe 42 and the spray pipe 43, and the water is sprayed out from the nozzle 44. The sprayed water mist contacts the exhaust gas and absorbs the NMP in the exhaust gas; the rotating power part 51 is started, so that the spray pipe 43 and the nozzle 44 rotate, and the nozzle 44 sprays while rotating.

[0076] Step c. As the exhaust gas gathers in the recovery tower 3, the air pressure in the recovery tower 3 gradually increases. When the air pressure reaches a preset value, the piston rod of the power telescopic member 11 extends, causing the baffle 12 to move downward, blocking the outlet of the storage box 10, so that the air inlet and outlet ends of the recovery tower 3 are both closed.

[0077] Step d. After the exhaust gas and water in the recovery tower 3 have been in contact for a period of time, the electromagnetic one-way valve 8 is opened, and the exhaust gas in the recovery tower 3 is discharged into the separation main device 61; after a period of time, the electromagnetic one-way valve 8 is closed, and the piston rod of the power telescopic part 11 is retracted, so that the baffle 12 moves up, and the outlet of the storage box 10 is opened, and the exhaust gas discharged from the oven 1 continues to flow into the recovery tower 3 for treatment.

[0078] Step e. The tail gas in the separation main device 61 is cooled, and the NMP in the tail gas is condensed and liquefied. The liquefied NMP flows into the liquid recovery device 62, and the condensed tail gas flows into the gas recovery pipeline 63.

[0079] Step f. When the tail gas flows into the serpentine tubular part, the low-temperature tail gas in the gas recovery pipe 63 and the high-temperature tail gas in the recovery tower 3 are initially heat exchanged, and the tail gas in the gas recovery pipe 63 is heated; the tail gas in the recovery tower 3 is cooled, and part of the NMP is liquefied, and the liquefied NMP falls to the bottom of the recovery tower 3.

[0080] Step g. The tail gas in the gas recovery pipe 63 flows into the gas-to-gas heat exchanger 2 and exchanges heat with the tail gas exhausted from the oven 1, so that the purified tail gas is heated again.

[0081] Step h. The purified tail gas flows into the oven 1.

[0082] The above are optional embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A NMP recovery system for a positive electrode coating machine, characterized in that: include: A heat exchange unit, wherein the tail gas inlet end of the heat exchange unit is used to be connected to the gas outlet end of the oven (1), and the purified gas outlet end of the heat exchange unit is used to be connected to the gas inlet end of the oven (1); A water washing unit, comprising a recovery tower (3) and a water washing device arranged in the recovery tower (3), wherein the air inlet end of the recovery tower (3) is connected to the tail gas outlet end of the heat exchange unit, and the water washing device is used to absorb NMP in the tail gas; A gas-liquid separation condensation unit (6) is connected to the gas outlet end of the recovery tower (3), the gas-liquid separation condensation unit (6) comprising a liquid recovery device (62) and a gas recovery pipeline (63), the liquid recovery device (62) being used to liquefy and recover NMP, and the gas recovery pipeline (63) being used to recover tail gas after condensation and liquefaction treatment; wherein the gas recovery pipeline (63) is connected to the purified gas inlet end of the heat exchange unit after passing through the recovery tower (3); The water washing device comprises a spray mechanism (4), the spray mechanism (4) comprising a pump body (41), a connecting pipe (42), a spray pipe (43) and a spray head (44), the spray pipe (43) comprising a main pipe (431) and a branch pipe (432), the portion of the gas recovery pipe (63) located in the recovery tower (3) being located on a side of the branch pipe (432) close to the top of the recovery tower (3), and the portion of the gas recovery pipe (63) located in the recovery tower (3) being in the shape of a serpentine pipe.

2. The NMP recovery system for a positive electrode coating machine according to claim 1, characterized in that: The pump body (41) is arranged on the recovery tower (3); the water inlet end of the pump body (41) is connected to the interior of the recovery tower (3); the water outlet end of the pump body (41) is connected to a connecting pipe (42); an end of the connecting pipe (42) away from the pump body (41) is located at the top of the recovery tower (3) and is connected to the spray pipe (43); the spray head (44) is arranged on the spray pipe (43); and the spray head (44) is connected to the interior of the spray pipe (43).

3. The NMP recovery system for a positive electrode coating machine according to claim 2, characterized in that: The main pipe (431) and the connecting pipe (42) are rotatably connected, the branch pipe (432) is arranged on the main pipe (431), the branch pipe (432) and the main pipe (431) are connected, a plurality of branch pipes (432) are provided, and the branch pipes (432) are arranged along the height direction of the recovery tower (3), a plurality of nozzles (44) are provided, and are arranged on the branch pipe (432) at intervals along the length direction of the branch pipe (432), and a driving mechanism (44) is also provided in the recovery tower (3). 5), the driving mechanism (5) comprises a rotating power member (51), a driving gear (52) and a driven gear (53), the rotating power member (51) is arranged on the recovery tower (3), the driving gear (52) and the output end of the rotating power member (51) are coaxially connected, the driven gear (53) is arranged on the main pipe (431), the rotation axis of the driven gear (53) and the main pipe (431) are coaxially arranged, and the driving gear (52) and the driven gear (53) are meshed with each other.

4. The NMP recovery system for a positive electrode coating machine according to claim 3, characterized in that: A support plate (7) is provided in the recovery tower (3), and a plurality of the support plates (7) are provided. The plurality of support plates (7) are spaced apart along the height direction of the recovery tower (3), and a plurality of water storage tanks (71) are provided on one side of the support plate (7) close to the top of the recovery tower (3), and a plurality of drainage holes (72) are provided on the support plate (7).

5. The NMP recovery system for a positive electrode coating machine according to claim 1, characterized in that: The gas outlet end of the recovery tower (3) is provided with an electromagnetic one-way valve (8), and the electromagnetic one-way valve (8) is used to allow the tail gas in the recovery tower (3) to enter the gas-liquid separation condensation unit (6) in one direction. The recovery tower (3) is provided with an air pressure sensor (9) and a controller, and the controller is electrically connected to the air pressure sensor (9) and the electromagnetic one-way valve (8), respectively.

6. The NMP recovery system for a cathode coating machine according to claim 5, characterized in that: A storage box (10) is arranged between the tail gas outlet end of the heat exchange unit and the air inlet end of the recovery tower (3); a power telescopic member (11) is arranged at the outlet of the storage box (10); the power telescopic member (11) is electrically connected to a controller; a baffle (12) is arranged at the movable end of the power telescopic member (11); the baffle (12) is used to control the opening and closing of the outlet of the storage box (10).

7. The NMP recovery system for a positive electrode coating machine according to claim 6, characterized in that: A mixing device is arranged in the recovery tower (3), and the mixing device comprises a plurality of fans (13) arranged in the recovery tower (3), and the fans (13) are electrically connected to a controller.

8. The NMP recovery system for a cathode coating machine according to claim 1, characterized in that: An activated carbon adsorption plate (14) is provided at the gas outlet end of the recovery tower (3).

9. A recycling method using the NMP recycling system for a positive electrode coating machine according to any one of claims 1 to 8, characterized in that: The recovery method comprises the following steps: a. The tail gas discharged from the outlet of the oven (1) passes through a heat exchange unit and then enters a recovery tower (3); b. The water washing device in the recovery tower (3) absorbs NMP in the tail gas. After passing through the water washing device, the tail gas is discharged from the recovery tower (3) to the gas-liquid separation condensation unit (6); c. The gas-liquid separation condensation unit (6) cools the tail gas, liquefies the NMP in the tail gas, and the liquefied NMP enters the liquid recovery device (62), and the remaining tail gas enters the gas recovery pipeline (63); d. the tail gas flows into the gas recovery pipe (63) in the recovery tower (3), and the tail gas in the gas recovery pipe (63) and the tail gas in the recovery tower (3) are initially heat exchanged, so that the tail gas in the gas recovery pipe (63) is heated up and the tail gas in the recovery tower (3) is cooled down, and then part of the NMP in the tail gas in the recovery tower (3) is liquefied and flows to the bottom of the recovery tower (3); f. The tail gas in the gas recovery pipe (63) flows into the heat exchange unit and exchanges heat with the tail gas discharged from the oven (1) again. The tail gas after the heat exchange flows into the oven (1) through the air inlet end of the oven (1).

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