Double-sided coating and drying oven integrated NMP (N-Methyl Pyrrolidone) recovery system and working method

Abstract

The invention provides a double-side coating and drying oven integrated NMP recovery system which comprises an oven system used for drying a lithium battery pole piece base material, a first tuyere mechanism and a second tuyere mechanism are arranged in the oven system, and the oven system is provided with an exhaust port. Waste gas exhausted by the exhaust port is exhausted after passing through an exhaust fan and a heat pump circulating system, the drying oven system is further provided with a circulating air opening, and the circulating air opening is connected with the first air nozzle mechanism and the second air nozzle mechanism through a circulating fan and an air pipe. Waste gas of the circulating air port is conveyed to the first air nozzle mechanism and the second air nozzle mechanism through the circulating fan. Through technical innovation, the double-face coating equipment and the heat pump NMP recovery system all-in-one machine achieve comprehensive breakthrough in the aspects of energy conservation, environmental protection, cost control and process flexibility; the method becomes a key innovative scheme in the field of lithium battery manufacturing.

Description

Technical Field

[0001] This invention relates to the field of NMP exhaust gas treatment equipment design technology for lithium battery coating machines, and in particular to an integrated NMP recovery system and its working method that combines double-sided coating and drying oven. Background Technology

[0002] Current wet-process coating technology involves coating a copper-aluminum foil substrate with a slurry using a coating machine equipped with a slit extrusion die to produce the positive and negative electrode sheets for batteries. A high-temperature hot air drying process evaporates the solvent. Since the positive electrode typically uses NMP (N-methylpyrrolidone) as a solvent, which is corrosive and toxic to humans, strict and effective recovery is necessary to meet emission standards. In traditional lithium-ion battery coating processes, the coating equipment and the NMP (N-methylpyrrolidone) recovery system operate independently, transporting the NMP through extensive pipelines. This results in large equipment footprints, complex piping, and secondary condensation of coating exhaust gas to remove NMP, leading to a high risk of solvent leakage and high energy consumption. Furthermore, the waste heat from the coating drying process (temperature range 40-80℃) is not effectively utilized; heating of circulating air and fresh air relies on electric heaters or steam heating, accounting for 30%-50% of the total energy consumption in lithium-ion battery production. Simultaneously, NMP condensation and recovery require an additional cooling source (such as a chilled water system), significantly increasing operating costs. Existing heat pump systems are mostly designed for single scenarios. High-temperature heat pump units lack a dynamic linkage mechanism with coating equipment, making them unable to adapt to the changing operating conditions of the coating process (such as coating speed, airflow fluctuations, and segmented temperature differences). Targeted adjustments and improvements are needed. Existing solvent drying and waste gas separation treatment methods for coating machines suffer from problems such as numerous pipelines, large engineering workload, and high energy consumption, requiring further improvement. Summary of the Invention

[0003] To address the shortcomings of the prior art, this invention provides an integrated NMP recycling system and its operating method that combines double-sided coating and hot air drying oven, effectively improving energy utilization, protecting lithium battery coating substrates, and consuming low energy.

[0004] The technical solution adopted by the present invention to solve the above problems is as follows: This invention provides an integrated NMP recovery system combining double-sided coating and drying oven. This includes an oven system for drying lithium battery electrode substrates, the oven system comprising a first air nozzle mechanism and a second air nozzle mechanism. The oven system is equipped with an exhaust port, and the exhaust gas emitted from the exhaust port is discharged after passing through an exhaust fan and a heat pump circulation system. The oven system is also equipped with a circulating air vent, which is connected to the first air nozzle mechanism and the second air nozzle mechanism via a circulating fan and air duct. The exhaust gas from the circulating air inlet is respectively transported by the circulating fan to the first air nozzle mechanism and the second air nozzle mechanism.

[0005] It also includes a fresh air inlet, which is connected to the circulating fan via a duct.

[0006] Furthermore, the air duct connected to the fresh air outlet merges with the air outlet connected to the circulating air outlet after passing through the heat pump circulation system, and then connects to the circulating fan. The air duct between the circulating fan and the first and second air nozzle mechanisms is equipped with a heating pack and a temperature sensor for secondary heating.

[0007] Furthermore, the duct connected to the fresh air inlet merges with the duct connected to the circulating air inlet and then connects to the circulating fan. The duct between the circulating fan and the first and second air nozzle mechanisms is heated by the heat pump circulation system and the heating pack. The duct between the circulating fan and the first and second air nozzle mechanisms is also equipped with a temperature sensor.

[0008] Furthermore, both the first and second air nozzle mechanisms consist of multiple air outlet structures. The first nozzle mechanism and the second nozzle mechanism are respectively located on both sides of the lithium battery electrode substrate.

[0009] The multiple air outlet structures of the first or second air outlet mechanism are connected by air ducts.

[0010] Furthermore, the heat pump cycle system consists of a compressor, a heat exchanger, an expansion valve, and an evaporator. The compressor, heat exchanger, expansion valve, and evaporator are connected by refrigerant pipelines and form a refrigerant circulation loop.

[0011] Furthermore, the exhaust port is connected to the evaporator of the heat pump cycle system via a duct and an exhaust fan. The evaporator of the heat pump cycle system is used to cool the exhaust gas discharged from the exhaust port. The heat exchanger of the heat pump circulation system is used to heat the exhaust gas discharged from the circulating air outlet or fresh air outlet.

[0012] Furthermore, the exhaust fan is connected to an NMP condensation and precipitation system via a duct and after passing through the evaporator, for the purpose of precipitating NMP waste gas. The NMP condensation and precipitation system is connected to an NMP secondary recovery system via a duct. The NMP waste gas passes through the NMP secondary recovery system and is then discharged to high altitude via the exhaust duct.

[0013] A method for operating a double-sided coating and drying oven integrated NMP recovery system, characterized by comprising the following steps: S1: The exhaust gas from the oven system is cooled by a heat pump circulation system through air ducts. S2: The cooled exhaust gas is discharged through an exhaust fan. S3: The exhaust gas discharged from the circulating air vent or fresh air vent of the oven system is heated by the heat pump circulation system through the air duct and then enters the oven by the circulating fan. S4: The exhaust gas, after being heated, enters the first and second air nozzle mechanisms of the oven system.

[0014] Furthermore, S1: The exhaust gas emitted from the exhaust port of the oven system is cooled through the air duct and heat pump circulation system, specifically, the exhaust gas is cooled from about 40°C to below 15°C after the gas-to-gas heat exchanger.

[0015] S2: After being cooled, the exhaust gas is discharged through the exhaust fan, then passes through the NMP condensation and precipitation system and the NMP secondary recovery system, and finally is discharged into the high atmosphere through the exhaust duct.

[0016] Furthermore, the heat pump cycle system consists of a compressor, a heat exchanger, an expansion valve, and an evaporator. The compressor, heat exchanger, expansion valve, and evaporator are connected by refrigerant pipelines to form a refrigerant circulation loop. The refrigerant is heated and absorbs heat to evaporate in the evaporator, cooling the passing exhaust gas. Then, the gaseous refrigerant is pressurized by the compressor of the heat pump system, increasing its temperature and pressure. The high-temperature and high-pressure refrigerant gas enters the condenser, where it heats the circulating return air to above 120°C, raising the temperature of the passing exhaust gas.

[0017] The beneficial effects of this invention are as follows: The high-temperature cascade NMP waste gas treatment heat pump system provided by this invention integrates double-sided coating and hot air drying oven, effectively improving energy utilization, protecting lithium battery coating substrates, and reducing energy consumption. This application utilizes a cascade heat pump system (high-temperature circulation + low-temperature circulation) to preheat fresh and circulating air using condensation heat release and condense NMP waste gas using evaporator cooling capacity, reducing overall energy consumption by 30% through heat pump combined cooling and heating technology. Simultaneously, the integrated layout and compact design of the coating machine and recovery system reduce pipeline losses and floor space, saving lithium battery manufacturers significant equipment investment and shortening the time from equipment installation to commissioning. Finally, through technological innovation, the integrated double-sided coating equipment and heat pump NMP recovery system achieve comprehensive breakthroughs in energy saving, environmental protection, cost control, and process flexibility, becoming a key innovative solution in the lithium battery manufacturing field. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the principle structure of Embodiment 1 of the NMP recovery system integrating double-sided coating and drying oven of the present invention; Figure 2 This is a flowchart of the workflow of Embodiment 1 of the NMP recovery system integrating double-sided coating and drying oven of the present invention; Figure 3 This is a schematic diagram of the principle structure of Embodiment 2 of the NMP recovery system integrating double-sided coating and drying oven of the present invention. Detailed Implementation

[0019] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The drawings are for reference and illustration only and do not constitute a limitation on the scope of protection of the present invention. Example 1

[0020] This invention provides an integrated NMP recovery system combining double-sided coating and drying oven. The system includes an oven system 1 for drying lithium battery electrode substrate 100, wherein the oven system 1 is provided with a first air nozzle mechanism 2 and a second air nozzle mechanism 3. The oven system 1 is equipped with an exhaust port 4. The exhaust gas emitted from the exhaust port 4 is discharged after passing through an exhaust fan 5 and a heat pump circulation system 6. The oven system 1 is also equipped with a circulating air outlet 7, which is connected to the first air nozzle mechanism 2 and the second air nozzle mechanism 3 via a circulating fan 8 and an air duct 200. The exhaust gas from the circulating air inlet 7 is transported by the circulating fan 8 to the first air nozzle mechanism 2 and the second air nozzle mechanism 3 respectively.

[0021] It also includes a fresh air vent 9, which is connected to the circulating fan 8 via a duct 200.

[0022] In this embodiment, the air duct 200 connected to the fresh air vent 9 passes through the heat pump circulation system 6 and merges with the air vent connected to the circulation vent 7, and then connects to the circulation fan 8. The air duct 200 between the circulation fan 8 and the first air nozzle mechanism 2 and the second air nozzle mechanism 3 is provided with a heating pack 10 and a temperature sensor 11 for secondary heating.

[0023] In this embodiment, the first air nozzle mechanism 2 and the second air nozzle mechanism 3 are composed of multiple air outlet structures 200. The first nozzle mechanism 2 and the second nozzle mechanism 3 are respectively disposed on both sides of the lithium battery electrode substrate 100.

[0024] Multiple air outlet structures 200 of the first air outlet mechanism 2 or the second air outlet mechanism 3 are connected by air ducts 200.

[0025] In this embodiment, the heat pump circulation system 6 consists of a compressor 601, a heat exchanger 602, an expansion valve 603, and an evaporator 604. The compressor 601, heat exchanger 602, expansion valve 603, and evaporator 604 are connected by a refrigerant pipeline 300 and form a refrigerant circulation loop.

[0026] In this embodiment, the exhaust port 4 is connected to the evaporator 604 of the heat pump circulation system 6 via a duct 200 and an exhaust fan 5. The evaporator 604 of the heat pump cycle system 6 is used to cool the exhaust gas discharged from the exhaust port 4. The heat exchanger 602 of the heat pump circulation system 6 is used to heat up the exhaust gas discharged from the circulating air outlet 7 or the fresh air outlet 9.

[0027] In this embodiment, the exhaust fan 5 is connected to an NMP condensation and precipitation system 12 via a duct 200 and an evaporator 604 to precipitate NMP waste gas. The NMP condensation and precipitation system 12 is connected to an NMP secondary recovery system 13 via a duct 200. The NMP waste gas passes through the NMP secondary recovery system 13 and is then discharged to the upper atmosphere via an exhaust duct 14.

[0028] A method for operating an integrated NMP recovery system combining double-sided coating and drying oven includes the following steps: S1: The exhaust gas emitted from the exhaust port 4 of the oven system 1 is cooled by the heat pump circulation system 6 through the air duct 200. S2: The cooled exhaust gas is discharged through exhaust fan 5. S3: The exhaust gas discharged from the circulating air outlet 7 or fresh air outlet 9 of the oven system 1 is heated by the heat pump circulation system 6 through the air duct 200 and then enters the oven by the circulating fan 8. S4: The exhaust gas after being heated enters the first air nozzle mechanism 2 and the second air nozzle mechanism 3 of the oven system 1.

[0029] In this embodiment, S1: The exhaust gas emitted from the exhaust port 4 of the oven system is cooled by the heat pump circulation system 6 through the air duct 200. Specifically, the exhaust gas is cooled from about 40°C to below 15°C after the gas-to-gas heat exchanger.

[0030] S2: After being cooled, the exhaust gas is discharged through the exhaust fan 5, and then passes through the NMP condensation and precipitation system 12 and the NMP secondary recovery system 13, before being discharged into the high atmosphere through the exhaust duct 200.

[0031] In this embodiment, the heat pump circulation system 6 consists of a compressor 601, a heat exchanger 602, an expansion valve 603, and an evaporator 604. The compressor 601, heat exchanger 602, expansion valve 603, and evaporator 604 are connected by a refrigerant pipeline 300 to form a refrigerant circulation loop. The refrigerant is heated and absorbs heat to evaporate in the evaporator 604, which cools the passing exhaust gas. Then, the gaseous refrigerant is pressurized by the heat pump system compressor 601, and its temperature and pressure increase. The high-temperature and high-pressure refrigerant gas enters the condenser, where it heats the circulating return air to above 120°C, thus warming the passing exhaust gas.

[0032] In this embodiment, the evaporator 604 replaces the refrigerant in the existing NMP recovery process, directly cooling the coating machine exhaust from approximately 40°C to below 15°C after passing through the gas-to-gas heat exchanger 602. Meanwhile, the refrigerant is heated and evaporates in the evaporator 6004, absorbing heat. The gaseous refrigerant is then pressurized by the heat pump system compressor 601, increasing its temperature and pressure. The high-temperature, high-pressure refrigerant gas enters the heat exchanger 602, where it heats the circulating return air to above 95°C in the condenser. The heat pump system heat exchanger 602 replaces the original NMP recovery system, and the return air enters the heater before the coating machine oven. Through the heat pump recovery system, the heat released from cooling the low-temperature gas is converted into high-temperature heat to heat the high-temperature return air. Thus, the low-temperature end largely no longer uses low-temperature refrigerant, and the high-temperature end largely no longer requires additional energy for heating, thereby reducing the energy consumption of the device.

[0033] Example 2 The difference between this embodiment and the previous embodiment is that: In this embodiment, the duct 200 connected to the fresh air inlet 9 merges with the duct 200 connected to the circulating air inlet 7 and then connects to the circulating fan 8. The duct 200 between the circulating fan 8 and the first air nozzle mechanism 2 and the second air nozzle mechanism 3 is heated by the heat pump circulation system 6 and the heating pack 10. The duct 200 between the circulating fan 8 and the first air nozzle mechanism 2 and the second air nozzle mechanism 3 is also equipped with a temperature sensor 11.

[0034] In this embodiment, the evaporator 604 replaces the refrigerator in the existing NMP recovery process, directly cooling the coating machine exhaust from approximately 40°C to below 15°C after the gas-to-gas heat exchanger. The refrigerant is heated and absorbs heat to evaporate in the evaporator 604. The gaseous refrigerant is pressurized by the heat pump system compressor 601, increasing its temperature and pressure. The high-temperature, high-pressure refrigerant gas enters the heat exchanger 602, where the circulating return air is heated to above 125°C. An auxiliary heater is installed inside to adjust the temperature of the outlet air. The heat pump system condenser replaces the original heater before the return air enters the coating machine oven, thereby reducing the energy consumption of the device.

[0035] The high-temperature cascade NMP waste gas treatment heat pump system provided by this invention integrates double-sided coating and hot air drying oven, effectively improving energy utilization, protecting lithium battery coating substrates, and reducing energy consumption. This application utilizes a cascade heat pump system (high-temperature circulation + low-temperature circulation) to preheat fresh and circulating air using condensation heat release, and condenses NMP waste gas using the cooling capacity of the evaporator 604. This heat pump combined cooling and heating technology reduces overall energy consumption by 30%. Simultaneously, the integrated layout and compact design of the coating machine and recovery system reduce pipeline losses and floor space, saving lithium battery manufacturers significant equipment investment and shortening the time from equipment installation to commissioning. Finally, through technological innovation, the integrated double-sided coating equipment and heat pump NMP recovery system achieve comprehensive breakthroughs in energy saving, environmental protection, cost control, and process flexibility, becoming a key innovative solution in the lithium battery manufacturing field.

[0036] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A double-sided coating and drying oven integrated NMP recovery system, characterized in that: it comprises an oven system for drying lithium battery pole piece substrates, and a first air nozzle mechanism and a second air nozzle mechanism are arranged in the oven system; the oven system is provided with an exhaust port, and exhaust gas discharged from the exhaust port is discharged after being circulated by an exhaust fan and a heat pump circulation system; the oven system is also provided with a circulating air port, and the circulating air port is connected to the first air nozzle mechanism and the second air nozzle mechanism through a circulating fan and an air pipe; the exhaust gas of the circulating air port is respectively delivered to the first air nozzle mechanism and the second air nozzle mechanism by the circulating fan; and the system further comprises a fresh air port, and the fresh air port is connected to the circulating fan through an air pipe.

2. The double-sided coating and drying oven integrated NMP recovery system according to claim 1, characterized in that: the air pipe connected to the fresh air port passes through the heat pump circulation system and is connected to the air port connected to the circulating air port, and then is connected to the circulating fan; and the air pipe between the circulating fan and the first air nozzle mechanism and the second air nozzle mechanism is provided with a heating bag for secondary heating and a temperature sensor.

3. The double-sided coating and drying oven integrated NMP recovery system according to claim 1, characterized in that: the air pipe connected to the fresh air port is connected to the air pipe connected to the circulating air port, and then is connected to the circulating fan; the air pipe between the circulating fan and the first air nozzle mechanism and the second air nozzle mechanism passes through the heat pump circulation system and the heating bag for temperature rising; and the air pipe between the circulating fan and the first air nozzle mechanism and the second air nozzle mechanism is also provided with a temperature sensor.

4. The double-sided coating and drying oven integrated NMP recovery system according to claim 1, characterized in that: the first air nozzle mechanism and the second air nozzle mechanism are composed of multiple air outlet nozzle structures; the first air nozzle mechanism and the second air nozzle mechanism are respectively arranged on two sides of the lithium battery pole piece substrate; and the multiple air outlet nozzle structures of the first air nozzle mechanism or the second air nozzle mechanism are connected by air pipes.

5. The double-sided coating and drying oven integrated NMP recovery system according to claim 1, characterized in that: the heat pump circulation system is composed of a compressor, a heat exchanger, an expansion valve and an evaporator, and the compressor, the heat exchanger, the expansion valve and the evaporator are connected by a refrigerant pipeline and form a refrigerant circulation loop.

6. The double-sided coating and drying oven integrated NMP recovery system according to claim 1, characterized in that: the exhaust port is connected to the evaporator of the heat pump circulation system through an air pipe and an exhaust fan; the evaporator of the heat pump circulation system is used for cooling treatment of exhaust gas discharged from the exhaust port; and the heat exchanger of the heat pump circulation system is used for temperature rising treatment of exhaust gas discharged from the circulating air port or the fresh air port.

7. The double-sided coating and drying oven integrated NMP recovery system according to claim 1, characterized in that: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The exhaust fan is connected with the NMP condensation and precipitation system through the air pipe and after the evaporator, which is used for precipitating NMP waste gas.

8. A working method of a two-sided coating and drying oven integrated NMP recovery system, characterized in that, The method comprises the following steps: S1: the exhaust gas discharged from the exhaust port of the oven system is cooled by the heat pump circulation system through the air pipe, S2: the exhaust gas is discharged by the exhaust fan, S3: the exhaust gas discharged from the circulating air port or fresh air port of the oven system is heated by the heat pump circulation system through the air pipe, and then enters the oven by the circulating fan, S4: the exhaust gas is introduced into the first air nozzle mechanism and the second air nozzle mechanism of the oven system.

9. The working method of the double-sided coating and drying oven integrated NMP recovery system according to claim 7, wherein: S1: the exhaust gas discharged from the exhaust port of the oven system is cooled by the heat pump circulation system through the air pipe, and specifically, the exhaust gas is cooled from about 40 DEG C to below 15 DEG C after the gas-gas heat exchanger, S2: the exhaust gas is discharged by the exhaust fan, and then passes through the NMP condensation and precipitation system and the NMP secondary recovery system, and is discharged to the high altitude through the exhaust air pipe.

10. The working method of the double-sided coating and drying oven integrated NMP recovery system according to claim 7, wherein: The heat pump circulation system is composed of a compressor, a heat exchanger, an expansion valve and an evaporator, the compressor, the heat exchanger, the expansion valve and the evaporator are connected through a refrigerant pipeline and form a refrigerant circulation loop, the refrigerant is heated and absorbs heat in the evaporator to evaporate, the passing exhaust gas is cooled, then the gaseous refrigerant is pressurized by the heat pump system compressor, the temperature and pressure are increased, the high-temperature and high-pressure refrigerant gas enters the condenser, the circulating air is heated to above 120 DEG C in the condenser, and the passing exhaust gas is heated.

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