Lithium battery NMP recovery system

Abstract

The invention discloses a lithium battery NMP (N-Methyl Pyrrolidone) recovery system, which belongs to the technical field of waste gas treatment, and comprises an NMP exhaust condensation flow path, an inlet of which is connected with an air outlet of a coating oven and is used for condensing NMP exhaust; an inlet and an outlet of the return air heating flow path are connected with an outlet of the NMP exhaust air condensation flow path and a return air inlet of the coating oven respectively, and heat exchange is carried out between the return air heating flow path and the NMP exhaust air condensation flow path; the working medium circulation loop exchanges heat with the NMP exhaust air condensation flow path and the return air heating flow path; an inlet of the exhaust purification flow path is connected with an outlet of the NMP exhaust condensation flow path, and the exhaust purification flow path is used for purifying the condensed to-be-exhausted gas; an inlet of the NMP recovery flow path is connected with the NMP exhaust condensation flow path and the exhaust purification flow path, and the NMP recovery flow path is used for recovering the NMP solution separated out of the NMP exhaust condensation flow path and the exhaust purification flow path. Through combination of working medium cold and hot circulation and condensation recovery heat exchange, NMP efficient recovery and system energy saving are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of waste gas treatment, and in particular relates to a lithium-ion NMP recovery system. Background Art

[0002] N-methylpyrrolidone (NMP) is a raw material for lithium battery production. It volatilizes in large quantities during the coating and baking process. Because it has certain biological toxicity and the raw material price is relatively expensive, it must be recycled. NMP recovery and processing equipment is a standard equipment for lithium batteries, but the current NMP recovery system mostly adopts the form of heat exchanger + tower spray absorption system, which has many problems: 1. The equipment structure size is too large, which is easy to interfere with other parts and is not conducive to installation; 2. When the spray tower absorbs NMP in the exhaust air of the coater, it is easy to bring moisture into the return air of the coater, affecting the uniformity of the workshop environment and product quality; 3. The energy consumption is large. The water in the spray absorption tower is heated by the hot exhaust gas, and the bottom liquid of the spray absorption tower dissipates heat and cools down, and the return air of the coater still needs to be heated to consume a lot of heat energy; 4. The NMP recovery concentration of the spray absorption tower is low, because the ability of the solution spray absorption is limited by temperature. The higher the temperature, the worse the absorption effect. This form of recovery cannot guarantee the NMP recovery concentration and is greatly affected by the environment. The condensation recovery method can greatly reduce the size of the equipment and avoid the introduction of moisture, thereby improving the quality of the positive electrode coating and the uniformity of product indicators. Therefore, the condensation recovery method of NMP has gradually begun to be promoted.

[0003] Chinese patent application number 2023115524051 discloses a rotary system and recovery method for recovering NMP from the exhaust gas of a lithium battery coating machine. The technical key points are that it includes heat exchange equipment, condensing equipment, a rotary unit, heating equipment and a recovery tank. The exhaust gas from the coating machine enters the heat exchange equipment for cooling and is then sent to the rotary unit through the condensing equipment. A part of the purified exhaust gas output from the adsorption zone is introduced into the fresh air and then heat exchanged with the heat exchange equipment for heating and then sent to the coating machine production line for reuse. The other part of the purified exhaust gas is discharged into the atmosphere. The exhaust gas output from the desorption zone is heated by the heating equipment and then sent to the cooling zone for cooling and then output to the front end of the condensing equipment. The condensing equipment condenses the high-concentration NMP obtained by desorption of the rotary unit and recovers it through the recovery tank.

[0004] Although the above patent adopts the condensation recovery method to achieve the simplification of the NMP recovery system equipment and avoid the introduction of water vapor, it requires external chilled water for cooling and introduces electric heating, which increases energy consumption and has a poor energy-saving effect. Summary of the invention

[0005] The object of the present invention is to provide a lithium-ion battery NMP recovery system, which exchanges heat between the NMP exhaust condensation flow path and the return air heating flow path, and provides the required cooling capacity and heat for the two flow paths through the working fluid circulation loop, greatly reducing the energy consumption in the NMP recovery process and realizing the efficient and energy-saving recovery of NMP.

[0006] To achieve the above object, the present invention is implemented by the following technical solutions: The present invention provides a lithium-ion battery NMP recovery system, including: An NMP exhaust condensation flow path, whose inlet is connected to the outlet of the coating oven, for condensing NMP in the exhaust air of the coating oven; A return air heating flow path, whose inlet and outlet are respectively connected to the outlet of the NMP exhaust condensation flow path and the return air inlet of the coating oven, and exchanges heat with the inlet section of the NMP exhaust condensation flow path; A working fluid circulation loop, which exchanges heat with the NMP exhaust condensation flow path and the return air heating flow path respectively, for providing cooling capacity and heat to the NMP exhaust condensation flow path and the return air heating flow path respectively; An exhaust air purification flow path, whose inlet is connected to the outlet of the NMP exhaust condensation flow path, for purifying the gas to be exhausted after condensation treatment; And an NMP recovery flow path, whose inlet is respectively connected to the NMP exhaust condensation flow path and the exhaust air purification flow path, for recovering the NMP solution precipitated in the NMP exhaust condensation flow path and the exhaust air purification flow path.

[0007] By designing the NMP exhaust condensation flow path and the return air heating flow path to be connected end to end and exchange heat, the NMP exhaust air discharged from the coating oven is fully cooled, the NMP recovery rate is improved, and the return air is heated and then recovered to the coating oven to realize the recycling of energy, greatly improving the NMP recovery efficiency and energy-saving degree. Combined with the heat absorption and refrigeration / cooling absorption and heat supply of the circulating working fluid to exchange heat with the NMP exhaust condensation flow path and the return air heating flow path respectively, the cold and heat can be jointly supplied to the NMP exhaust condensation flow path and the return air heating flow path, further reducing the energy consumption.

[0008] Optionally, the NMP exhaust condensation flow path and the return air heating flow path exchange heat through a heat recovery device; The heat recovery device includes an exhaust air channel and a return air channel that can exchange heat with each other. The air inlet of the exhaust air channel is connected to the outlet of the coating oven, and the air outlet of the return air channel is connected to the return air inlet of the coating oven; The NMP exhaust condensation flow path flows through the exhaust air channel, and the return air heating flow path flows through the return air channel.

[0009] The above technical solution can enable the high-temperature exhaust air in the NMP exhaust air condensation flow path to exchange heat with the low-temperature return air in the return air heating flow path, reducing the temperature of the exhaust air in the NMP exhaust air condensation flow path and the cooling capacity required for condensation recovery, while increasing the temperature of the return air in the return air heating flow path and reducing the heat required for return air heating. This not only improves the energy utilization rate but also reduces the operating cost of the system.

[0010] Optionally, a fan and a condensation recovery device are also connected to the NMP exhaust air condensation flow path; The condensation recovery device is provided with an air inlet, an air outlet, and a water outlet; The air inlet of the condensation recovery device is communicated with the air outlet of the exhaust air channel, the air outlet of the condensation recovery device is communicated with the air inlet of the return air channel, and the water outlet of the condensation recovery device is communicated with the inlet of the NMP recovery flow path; The fan is used to provide power for the flow of the exhaust air from the coating oven in the NMP exhaust air condensation flow path.

[0011] By adding a fan and a condensation recovery device to the NMP exhaust air condensation flow path, the smooth transportation of the gas is ensured, ensuring that the NMP exhaust air can efficiently enter the condensation recovery device for condensation treatment, further improving the efficiency and quality of NMP recovery.

[0012] Optionally, the exhaust air channel is also provided with a water outlet, and the water outlet of the exhaust air channel is communicated with the water inlet of the NMP recovery flow path.

[0013] After the exhaust air in the exhaust air channel exchanges heat with the return air in the return air channel and the temperature decreases, some NMP solution may be precipitated. By providing a water outlet in the exhaust air channel, the NMP recovery rate is further increased.

[0014] Optionally, a return air reheating device is also connected to the return air heating flow path; The return air reheating device is connected between the air outlet of the return air channel and the air inlet of the coating oven, and is used to heat the return air flowing back through the return air channel.

[0015] By reheating the NMP return air heated by the return air channel through the return air reheating device, the demand for additional heat energy by the coating oven is reduced, enabling the NMP return air to meet the process requirements of the coating oven and be reused, realizing the efficient recovery and reuse of heat.

[0016] Optionally, a high-temperature heat pump evaporator and a high-temperature heat pump condenser are provided on the working fluid circulation loop; The high-temperature heat pump evaporator is embedded in the condensation recovery device and is used to exchange heat with the NMP exhaust air condensation flow path; The high-temperature heat pump condenser is embedded in the return air reheating device and is used to exchange heat with the return air heating flow path; A high-temperature heat pump throttle valve is provided on the working medium circulation loop between the outlet of the high-temperature heat pump condenser and the inlet of the high-temperature heat pump evaporator, and a high-temperature heat pump compressor is provided on the working medium circulation loop between the outlet of the high-temperature heat pump evaporator and the inlet of the high-temperature heat pump condenser.

[0017] Through the combined application of the various components of the high-temperature heat pump device, efficient conversion and transfer of cooling capacity and heat are achieved, ensuring the stable operation of the working medium circulation. This not only improves the energy utilization efficiency of the system, reduces the dependence on traditional energy sources, but also lowers the operating cost of the system.

[0018] Optionally, an exhaust gas spraying device is connected to the exhaust gas purification flow path; The exhaust gas spraying device includes a spray tower, a spray circulation pump, and a pure water replenishing device; The air inlet of the spray tower is connected to the air outlet of the condensation recovery device; The spray circulation pump is connected between the water outlet of the first spray tower and the water inlet of the first spray tower; The water outlet of the pure water replenishing device is connected to the water inlet of the second spray tower, and the pure water replenishing device is used to supply water to the spray tower; The height at which the water inlet of the first spray tower is opened is higher than the water outlet of the first spray tower and the water inlet of the second spray tower.

[0019] Through the spray tower, the spray circulation pump, and the pure water replenishing device, the purification treatment of the gas escaping after condensation is achieved, ensuring that it meets the emission standards. This not only meets the environmental protection requirements and avoids pollution to the atmospheric environment, but also further improves the resource utilization rate by recovering NMP in the spray liquid.

[0020] Optionally, the NMP recovery flow path includes a condensation recovery branch and an absorption recovery branch; The condensation recovery branch and the absorption recovery branch carry out NMP solution recovery through an NMP liquid recovery tank; The water inlet of the condensation recovery branch is respectively connected to the water outlet of the exhaust air channel and the water outlet of the condensation recovery device, and the water outlet of the condensation recovery branch is connected to the water inlet of the first NMP liquid recovery tank; The water inlet of the absorption recovery branch is connected to the water outlet of the second spray tower, and the water outlet of the absorption recovery branch is connected to the water inlet of the second NMP liquid recovery tank.

[0021] Through the setting of the two NMP recovery branches, all the cavities in the NMP recovery system where NMP solution may be generated are connected to the NMP liquid recovery tank, greatly improving the recovery rate of NMP.

[0022] Optionally, a condensation NMP liquid transfer pump is further connected to the condensation recovery branch, and the condensation NMP liquid transfer pump is connected between the water outlet of the condensation recovery device and the water inlet of the first NMP liquid recovery tank.

[0023] The setting of the transfer pump ensures the smooth transfer of the NMP solution in the condensate recovery branch, improving the recovery efficiency.

[0024] Optionally, an absorption NMP liquid transfer pump is further connected to the absorption recovery branch. The absorption NMP liquid transfer pump is connected between the water outlet of the second spray tower and the water inlet of the second NMP liquid recovery tank.

[0025] The setting of the transfer pump ensures the smooth transfer of the NMP solution in the absorption recovery branch. Through the precise control of the transfer pump, the flow rate of the NMP solution can also be adjusted.

[0026] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: By making the high-temperature exhaust air in the NMP exhaust air condensation flow path and the low-temperature return air in the return air heating flow path conduct countercurrent heat exchange, while reducing the temperature of the exhaust air in the NMP exhaust air condensation flow path and the cooling capacity required for condensation recovery, the temperature of the return air in the return air heating flow path is increased, the heat required for return air heating is reduced, and the NMP exhaust air discharged from the coating oven can be fully cooled, improving the NMP recovery efficiency and energy-saving degree. Then, through the high-temperature heat pump, the refrigerant is simultaneously refrigerated and heated during the circulation process, thereby providing the cooling capacity required for condensation for the NMP exhaust air condensation flow path and the heat required for evaporation for the return air heating flow path, realizing the efficient utilization of cooling capacity and heat, greatly reducing the dependence of the traditional condensation system on external chilled water and electric heating, further reducing energy consumption, significantly improving the resource utilization rate, and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The structure schematic diagram of a lithium-ion battery NMP recovery system in an embodiment of the present invention is shown.

[0028] In the figure: 1. Coating oven; 2. Heat recovery device; 3. Return air reheating device; 4. Fan; 5. Condensate recovery device; 6-1. Spray circulation pump; 6-2. Pure water replenishing device; 6-3. Spray tower; 7-1. Condensed NMP liquid transfer pump; 7-2. Absorption NMP liquid transfer pump; 7-3. NMP liquid recovery tank; 8-1. High-temperature heat pump compressor; 8-2. High-temperature heat pump throttle valve; 8-3. High-temperature heat pump condenser; 8-4. High-temperature heat pump evaporator. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0030] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "plural" is two or more.

[0031] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0032] Embodiment 1

[0033] This embodiment provides a lithium battery NMP recovery system, including: An NMP exhaust condensation flow path, whose inlet is connected to the air outlet of the coating oven 1, and is used for condensing the NMP in the exhaust air of the coating oven 1. A return air heating flow path, whose inlet and outlet are respectively connected to the outlet of the NMP exhaust condensation flow path and the return air inlet of the coating oven 1, and exchanges heat with the inlet section of the NMP exhaust condensation flow path. A working medium circulation loop, which exchanges heat with the NMP exhaust condensation flow path and the return air heating flow path respectively, and is used to provide cold and heat to the NMP exhaust condensation flow path and the return air heating flow path respectively. An exhaust air purification flow path, whose inlet is connected to the outlet of the NMP exhaust condensation flow path, and is used for purifying the gas to be exhausted after condensation treatment. And an NMP recovery flow path, whose inlet is respectively connected to the NMP exhaust condensation flow path and the exhaust air purification flow path, and is used to recover the NMP solution precipitated in the NMP exhaust condensation flow path and the exhaust air purification flow path.

[0034] By combining the condensation recovery loop with the working fluid circulation loop, the NMP recovery system can efficiently recover NMP with low energy consumption. Among them, the condensation recovery loop is composed of an NMP exhaust air condensation flow path and a return air heating flow path whose outlets and inlets are connected end to end and exchange heat with each other. It can simultaneously reduce the cooling capacity required for condensation of the NMP exhaust air condensation flow path and the heat required for heating of the return air heating flow path, significantly improving the energy utilization rate and reducing the production cost. The working fluid circulation loop can simultaneously produce low-temperature cooling capacity and high-temperature heat, which are used for NMP condensation recovery and return air heating, reducing the dependence of the traditional condensation system on external chilled water supply for cooling and electric heating for heating, and greatly reducing the energy consumption.

[0035] Example 2

[0036] Based on Example 1, the following design is also made in this example.

[0037] The NMP exhaust air condensation flow path includes a coating oven 1, a heat recovery device 2, a fan 4, and a condensation recovery device 5 connected in sequence. The return air heating flow path includes a heat recovery device 2, a return air reheating device 3, and a coating oven 1 connected in sequence. The heat recovery device 2 is a gas-gas countercurrent heat exchange device, in which an exhaust air channel and a return air channel are cross-set. The NMP exhaust air condensation flow path flows through the exhaust air channel, and the return air heating flow path flows through the return air channel. The two flow paths exchange heat by flowing through two air ducts in the heat recovery device 2 respectively. The fan 4 is used to provide the power for transporting the gas containing NMP in the system pipeline, so that the oven exhaust air and return air can circulate in the pipeline loop system. In this example, in order to cope with the corrosiveness of NMP, the impeller and shell of the fan 4 have anti-corrosion characteristics.

[0038] The high-temperature heat pump device uses a high-temperature circulating working fluid. While producing low-temperature cooling capacity, it can produce heat above 90°C. The low-temperature cooling capacity produced can be used for NMP condensation and precipitation, and the high-temperature heat produced can be used to raise the temperature of the return air flowing through the heat recovery device 2 before entering the coating oven 1, saving the cooling capacity consumption of the condensation recovery device 5 and the energy consumption of heating the return air in the coating oven 1. The high-temperature heat pump device includes a high-temperature heat pump condenser 8-3, a high-temperature heat pump evaporator 8-4, a high-temperature heat pump compressor 8-1, and a high-temperature heat pump throttle valve 8-2. The circulating working fluid absorbs heat and refrigerates in the high-temperature heat pump evaporator 8-4, and then is compressed by the high-temperature heat pump compressor 8-1 into high-temperature and high-pressure steam, condenses and releases heat in the high-temperature heat pump condenser 8-3, and then enters the high-temperature heat pump evaporator 8-4 after being depressurized and cooled by the high-temperature heat pump throttle valve 8-2 to complete the working fluid cycle.

[0039] The high-temperature heat pump evaporator 8-4 is embedded in the condensation recovery device 5. The high-temperature heat pump evaporator 8-4 adopts the form of finned tube heat exchange hot gas, and enhances heat exchange by increasing the contact area. The condensation recovery device 5 is a heat exchange device for the oven exhaust air and the high-temperature heat pump evaporator 8-4. The oven exhaust air flowing through the heat recovery device 2 has been cooled to a certain temperature and is further cooled to about 15°C here. The NMP in the air flow is thus condensed and precipitated, and the remaining air flow continues to be transported downstream.

[0040] The high-temperature heat pump condenser 8-3 is embedded in the return air reheating device 3. The high-temperature heat pump condenser 8-3 adopts the form of finned tube heat exchange hot gas, and adopts the countercurrent heat exchange method to improve the heat exchange effect. The return air reheating device 3 is a heat exchange device for the oven return air and the high-temperature heat pump condenser 8-3. The flow direction of the oven return air is opposite to the flow direction of the internal circulating working medium in the high-temperature heat pump condenser 8-3. The oven return air flowing through the heat recovery device 2 has been heated to a certain temperature and is further heated to above 90°C here, meeting the requirements of the coating oven 1 for the hot air temperature and reducing the energy consumption of the oven electric heating.

[0041] The condensation recovery device 5 and the exhaust gas spraying device are successively connected on the exhaust gas purification flow path. The exhaust gas spraying device includes a spraying tower 6-3, a spraying circulation pump 6-1 connected between the water outlet of the first spraying tower and the water inlet of the second spraying tower, and a pure water replenishing device 6-2 for supplying water to the spraying tower 6-3 through the water inlet of the first spraying tower. Among them, the water outlet and the water inlet of the first spraying tower are both opened on the lower side wall of the spraying tower 6-3, and the water inlet of the second spraying tower is opened on the upper side wall of the spraying tower 6-3.

[0042] The exhaust gas spraying device sprays pure water on the NMP exhaust gas entering the spraying tower 6-3 to absorb the NMP in the air flow. The solution at the bottom of the spraying tower 6-3 is transported to the high place of the spraying tower 6-3 by the spraying circulation pump 6-1 and sprays and falls. The low-temperature exhaust gas enters from the lower part of the spraying tower 6-3 and contacts the solution reversely. After the solution droplets fully absorb the NMP in the low-temperature exhaust gas, they fall to the bottom of the spraying tower 6-3. When the solution concentration reaches a certain value, the NMP solution can be recovered.

[0043] In this embodiment, most of the air flow escaping from the condensation recovery device 5 flows to the heat recovery device 2, and then enters the coating oven 1 through the heat recovery device 2 and the return air reheating device 3. A small part enters the exhaust gas spraying device. After spraying and absorption, the NMP concentration in the exhaust gas is reduced to the standard range and then discharged to the atmospheric environment. The air flowing to the spraying absorption device accounts for about 5% - 10% of the oven exhaust air, and the air volume can be controlled by adjusting the proportional regulating air valve. The flow rate of the spraying circulation pump 6-1 can be adjusted according to the NMP concentration in the exhaust gas.

[0044] The NMP recovery flow path respectively includes a condensation recovery branch and an absorption recovery branch. The water outlets of the two branches are both connected to the NMP liquid recovery tank 7-3, that is, the NMP solution flowing through the condensation recovery branch and the absorption recovery branch finally flows into the NMP liquid recovery tank 7-3 for storing the NMP solution recovered by the recovery system. The water inlets of the condensation recovery branch are respectively communicated with the water outlet of the condensation recovery device 5 and the water outlet of the exhaust air channel. A liquid collecting tank is arranged at the water outlet of the exhaust air channel, and the liquid collecting tank passes through the side wall of the heat recovery device 2 and communicates with the water outlet of the condensation recovery device 5; the water inlet of the absorption recovery branch is communicated with the second spray tower water inlet opened on the lower side wall of the spray tower 6-3. When the NMP liquid recovered by the condensation recovery device 5 and the NMP aqueous solution collected by the exhaust air spraying device reach the recoverable concentration, the corresponding condensation NMP liquid transfer pump 7-1 and absorption NMP liquid transfer pump 7-2 on the condensation recovery branch and the absorption recovery branch are respectively started to transfer the NMP solution to the NMP liquid recovery tank 7-3.

[0045] Example 3

[0046] This embodiment provides a lithium-ion battery NMP recovery method, which applies the lithium-ion battery NMP recovery system described in any step of Example 2. The steps of the recovery method are as follows: The oven exhaust air discharged from the coating oven 1 is sent to the exhaust air channel in the heat recovery device 2 through the NMP exhaust air condensation flow path for cooling. Among them, the oven exhaust air contains a high concentration of NMP. After the oven exhaust air is cooled in the heat recovery device 2, it continues to be sent to the condensation recovery device 5 through the NMP exhaust air condensation flow path and is further cooled by the high-temperature heat pump evaporator 8-4. Most of the NMP in the oven exhaust air condenses and precipitates here.

[0047] Most of the low-temperature exhaust air flowing out of the condensation recovery device 5 after condensation is converted into oven return air. The oven return air flows back into the exhaust air channel of the heat recovery device 2 through the return air heating flow path and exchanges heat with the oven exhaust air in the exhaust air channel. The heated oven return air continues to enter the return air reheating device 3 through the return air heating flow path and is further heated by the high-temperature heat pump condenser 8-3 and then sent back to the coating oven 1. Another small part of the low-temperature exhaust air escaping from the condensation recovery device 5 after condensation is sent to the exhaust air spraying device through the exhaust air purification flow path for purification and NMP absorption, and is discharged into the atmospheric environment after reaching the emission standard.

[0048] Finally, through the NMP liquid recovery flow path, the NMP liquids collected in the condensation recovery device 5, the heat recovery device 2 and the exhaust air spraying device are respectively transported to the NMP liquid recovery tank 7-3 through the corresponding condensation recovery branch, absorption recovery branch and the condensation NMP solution transfer pump and absorption NMP solution transfer pump installed thereon, realizing the recovery of NMP from the oven exhaust air.

[0049] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit of the present invention and the scope protected by the claims. All of these fall within the protection scope of the present invention.

Claims

1. A lithium battery NMP recovery system, characterized in that: include: An NMP exhaust condensation flow path, the inlet of which is connected to the coating oven outlet, and is used to condense the NMP in the coating oven exhaust; The return air heating flow path has an inlet and an outlet connected to the outlet of the NMP exhaust condensation flow path and the return air port of the coating oven, respectively, and exchanges heat with the inlet section of the NMP exhaust condensation flow path; A working medium circulation loop, which exchanges heat with the NMP exhaust condensation flow path and the return air heating flow path, respectively, and is used to provide cooling and heating to the NMP exhaust condensation flow path and the return air heating flow path, respectively; An exhaust purification flow path, the inlet of which is connected to the outlet of the NMP exhaust condensation flow path, and is used to purify the gas to be exhausted after condensation treatment; And, an NMP recovery flow path, whose inlet is respectively connected to the NMP exhaust condensation flow path and the exhaust purification flow path, for recovering the NMP solution precipitated in the NMP exhaust condensation flow path and the exhaust purification flow path.

2. The lithium-ion NMP recovery system according to claim 1, wherein: The NMP exhaust condensation flow path and the return air heating flow path exchange heat through a heat recovery device; The heat recovery device includes an exhaust channel and a return channel that can exchange heat with each other, the exhaust channel air inlet is connected to the coating oven air outlet, and the return channel air outlet is connected to the coating oven return air outlet; The NMP exhaust condensation flow path flows through the exhaust passage, and the return air heating flow path flows through the return air passage.

3. The lithium-ion NMP recovery system according to claim 2, wherein: The NMP exhaust condensation flow path is also connected to a condensation recovery device and a fan; The condensation recovery equipment is provided with an air inlet, an air outlet and a water outlet; The air inlet of the condensation recovery device is connected to the air outlet of the exhaust channel, the air outlet of the condensation recovery device is connected to the air inlet of the return air channel, and the water outlet of the condensation recovery device is connected to the inlet of the NMP recovery flow path; The fan is used to provide power to the flow of coating oven exhaust air in the NMP exhaust condensation flow path.

4. The lithium-ion NMP recovery system according to claim 3, wherein: The exhaust channel is also provided with a water outlet, and the water outlet of the exhaust channel is connected to the inlet of the NMP recovery flow path.

5. The lithium-ion NMP recovery system according to claim 3, wherein: The return air heating flow path is also connected to a return air reheating device; The return air reheating device is connected between the return air duct outlet and the coating oven return air duct, and is used for heating the return air flowing back through the return air duct.

6. The lithium-ion NMP recovery system according to claim 5, wherein: The working medium circulation loop is provided with a high-temperature heat pump evaporator and a high-temperature heat pump condenser; The high-temperature heat pump evaporator is embedded in the condensation recovery equipment and is used to exchange heat with the NMP exhaust condensation flow path; The high-temperature heat pump condenser is embedded in the return air reheating device and is used to exchange heat with the return air heating flow path; A high-temperature heat pump throttle valve is provided on the working medium circulation loop between the high-temperature heat pump condenser outlet and the high-temperature heat pump evaporator inlet, and a high-temperature heat pump compressor is provided on the working medium circulation loop between the high-temperature heat pump evaporator outlet and the high-temperature heat pump condenser inlet.

7. The lithium-ion NMP recovery system according to claim 4, wherein: An exhaust spray device is connected to the exhaust purification flow path; The exhaust spray equipment includes a spray tower, a spray circulation pump and a pure water replenishing device; The air inlet of the spray tower is connected to the air outlet of the condensation recovery equipment; The spray circulation pump is connected between the first spray tower water outlet and the first spray tower water inlet; The water outlet of the pure water replenishing device is connected to the water inlet of the second spray tower; The opening height of the first spray tower water inlet is higher than the first spray tower water outlet and the second spray tower water inlet.

8. The lithium-ion NMP recovery system according to claim 7, characterized in that: The NMP recovery flow path includes a condensation recovery branch and an absorption recovery branch; The condensation recovery branch and the absorption recovery branch recover the NMP solution through an NMP liquid recovery tank; The water inlet of the condensation recovery branch is respectively connected to the water outlet of the exhaust channel and the water outlet of the condensation recovery equipment, and the water outlet of the condensation recovery branch is connected to the water inlet of the first NMP liquid recovery tank; The water inlet of the absorption recovery branch is communicated with the water outlet of the second spray tower, and the water outlet of the absorption recovery branch is communicated with the water inlet of the second NMP liquid recovery tank.

9. The lithium-ion NMP recovery system according to claim 8, characterized in that: The condensation recovery branch is also connected to a condensed NMP liquid delivery pump, and the condensed NMP liquid delivery pump is connected between the water outlet of the condensation recovery equipment and the water inlet of the first NMP liquid recovery tank.

10. The lithium-ion NMP recovery system according to claim 8, characterized in that: The absorption recovery branch is also connected with an absorption NMP liquid delivery pump, and the absorption NMP liquid delivery pump is connected between the water outlet of the second spray tower and the water inlet of the second NMP liquid recovery tank.

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