A coating machine box NMP waste gas recovery system and a control method thereof

Abstract

The application provides a coating oven NMP waste gas recovery system, which comprises a first heat exchanger, a second heat exchanger, a third heat exchanger, a circulating fan and a fourth heat exchanger which are sequentially connected with an exhaust port of a coating oven through air pipes, the fourth heat exchanger is connected with an air return port of the oven through an air pipe, and the first heat exchanger, the second heat exchanger, the third heat exchanger, the circulating fan and the fourth heat exchanger form a waste gas treatment circulating loop. The application has the advantages of stable performance, high reliability, energy saving and the like. Through the unique structure design and the accurate system temperature calculation control method, the system temperature can be ensured to be stable in a reasonable range, the normal operation of each link is ensured, and thus the stability and reliability of the system are ensured.

Description

Technical Field

[0001] This invention relates to the field of NMP exhaust gas treatment equipment design for lithium battery coating machines, and particularly to an NMP exhaust gas recovery system for coating machine chassis and its control method. Background Technology

[0002] The cathode coating process generates a large amount of high-temperature waste gas containing volatile organic compounds (VOCs) such as NMP (methylpyrrolidone). Because NMP is harmful to the environment, the waste gas needs to be recovered. The currently popular NMP recovery system involves: waste heat recovery (gas-to-gas heat exchange) + condensation + 95% return air + 5% rotary turbine treatment before discharge. The condensation section requires 7-12°C low-temperature chilled water, which must be supplied by the refrigeration unit. During operation, the cathode coating machine needs to heat the oven to dry the coated battery electrodes. Oven heating can be achieved through various methods, including electric heating, steam heating, and thermal oil heating. Currently, existing recovery devices have certain shortcomings, such as high energy consumption and unstable system temperature control, requiring further improvement. Summary of the Invention

[0003] This invention addresses the shortcomings of the prior art by providing a stable, reliable, and energy-saving NMP exhaust gas recovery system for coating machines and its control method.

[0004] The technical solution adopted by the present invention to solve the above problems is as follows: This invention provides an NMP exhaust gas recovery system for a coating machine chamber, comprising a first heat exchanger, a second heat exchanger, a third heat exchanger, a circulating fan, and a fourth heat exchanger sequentially connected to the exhaust vent of the coating machine oven via ducts. The fourth heat exchanger is connected to the return air vent of the oven via ducts. The first heat exchanger, the second heat exchanger, the third heat exchanger, the circulating fan, and the fourth heat exchanger form an exhaust gas treatment circulation loop.

[0005] Furthermore, the second heat exchanger is connected to a cooling water tower via a cooling water circuit, and a cooling water pump and a first valve are provided on the circulating water circuit between the cooling water tower and the second heat exchanger.

[0006] Furthermore, the third heat exchanger is connected to a first gas-liquid separator via a refrigerant pipeline, and the first gas-liquid separator is connected to a first compressor. The first compressor is connected to a fifth heat exchanger and a first liquid receiver via refrigerant piping.

[0007] Furthermore, the first liquid receiver is connected to the first compressor via a first economizer, and is connected to a first main expansion valve and a first auxiliary expansion valve via a refrigerant pipeline. The first main expansion valve is connected to the third heat exchanger via a refrigerant pipeline, and the first auxiliary expansion valve is connected to the first economizer via a refrigerant circuit.

[0008] Furthermore, the fourth heat exchanger is connected to a second liquid receiver via a refrigerant pipeline, and the second liquid receiver is connected to a second economizer and a second compressor via a refrigerant pipeline. The second compressor is connected to the fourth heat exchanger. The second economizer is connected to the second main expansion valve and the sixth heat exchanger via a refrigerant circuit. The sixth heat exchanger is connected to the second gas-liquid separator via a refrigerant circuit, and the second gas-liquid separator is connected to the second compressor via a refrigerant circuit.

[0009] Furthermore, the second economizer is also connected to a second auxiliary expansion valve via a refrigerant circuit.

[0010] Furthermore, the sixth heat exchanger is sequentially connected to a buffer water tank, a circulating water pump, a seventh heat exchanger, and the fifth heat exchanger via a circulating water loop. The sixth heat exchanger, the buffer water tank, the circulating water pump, the seventh heat exchanger, and the fifth heat exchanger form a circulating water loop. The seventh heat exchanger is connected to the cooling tower and the second heat exchanger via a cooling water loop.

[0011] A control method for an NMP exhaust gas recovery system for a coating machine chassis, characterized in that: Assume there is Section 1 coating machine drying oven, set the first The return air temperature of the oven in the coating machine drying oven system 1 is: (°C), Total circulating air volume is (m) 3 / h), exhaust air volume is （m 3 / h） The exhaust temperature is (°C), NMP exhaust concentration is (ppm) and fresh air temperature （℃） The condensate return air temperature of the NMP recovery system is (°C), waste heat recovery heat exchange efficiency is The return air ratio is The NMP exhaust gas, after being cooled by cooling tower 7, has a temperature of [temperature value missing]. （℃） The maximum heating return air temperature of the heat pump unit is （℃） The refrigeration COP of the first compressor 11 is The heating COP of the second compressor 19 is When the heat pump unit is connected one-to-one with the coating machine oven 1, the first The heating capacity required for the coating machine drying oven system 1 (kW)and the corresponding heat pump unit heating capacity (kW) and auxiliary heating capacity (kW) And the cooling capacity required for the NMP recovery system (kW) and the corresponding cooling capacity of the heat pump unit (kW) and the heat dissipation of cooling tower 7 The calculation process for (kW) is as follows: Coating machine drying oven system 1: ； ； ； in, ； ； ； ； ； NMP recycling system: ； ； ； In this embodiment, ； ； ； in, 、 and The first Taiwan coating NMP recycling integrated machine NMP from Condensation 、 from Condensation and from Condensation The latent heat of condensation released during the process, therefore, Total heating capacity required for coating machine drying oven system 1 (kW) and the total heating capacity of the corresponding heat pump units (kW) Total heating capacity of auxiliary heating (kW) and the total cooling capacity required for the NMP recovery system. (kW) and the corresponding total cooling capacity of the heat pump unit (kW) Total heat dissipation of cooling tower 7 (kW) The calculation process is as follows: ； ； ； ； ； 。

[0012] In this embodiment, the power of each circulating fan 55 in the coating machine oven 1 system is set to... (kW) The NMP recycling system has a power of 55 for each circulating fan. (kW) Auxiliary heating can be electric heating, steam, or other heating methods such as heat transfer oil. Taking electric heating as an example, let the electrothermal efficiency be... Assume the heat dissipation COP of cooling tower 7 is... The power consumption of the entire coating NMP recycling integrated system is then determined. (kW) and its corresponding fan power (kW) Compressor power (kW) Auxiliary heating power (kW) and cooling tower 7 heat dissipation power (kW) The calculation process is as follows: ； ； ； ； 。

[0013] The beneficial effects of this invention are as follows: The NMP exhaust gas recovery system for coating machine provided by this invention has the advantages of stable performance, high reliability, and energy saving. Through unique structural design and precise system temperature calculation and control method, this application can ensure that the system temperature is stable within a reasonable range, guarantee the normal operation of each link, and thus ensure the stability and reliability of the system. Attached Figure Description

[0014] Figure 1 This is a structural diagram of an NMP exhaust gas recovery system for a coating machine chassis according to the present invention. Detailed Implementation

[0015] 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.

[0016] like Figure 1 As shown, the present invention provides an NMP exhaust gas recovery system for a coating machine chamber, comprising a first heat exchanger 2, a second heat exchanger 3, a third heat exchanger 4, a circulating fan 5, and a fourth heat exchanger 6 connected sequentially to the exhaust vent of the coating machine oven 1 via ducts. The fourth heat exchanger 6 is connected to the return air vent of the oven via ducts. The first heat exchanger 2, the second heat exchanger 3, the third heat exchanger 4, the circulating fan 5, and the fourth heat exchanger 6 form an exhaust gas treatment circulation loop.

[0017] In this embodiment, the second heat exchanger 3 is connected to a cooling water tower 7 via a cooling water circuit, and a cooling water pump 8 and a first valve 9 are provided on the circulating water circuit between the cooling water tower 7 and the second heat exchanger 3.

[0018] In this embodiment, the third heat exchanger 4 is connected to the first gas-liquid separator 10 via a refrigerant pipeline, and the first gas-liquid separator 10 is connected to the first compressor 11. The first compressor 11 is connected to the fifth heat exchanger 12 and the first liquid receiver 13 via refrigerant pipelines.

[0019] In this embodiment, the first liquid receiver 13 is connected to the first compressor 11 through the first economizer 14, and is connected to the first main expansion valve 15 and the first auxiliary expansion valve 16 through the refrigerant pipeline. The first main expansion valve 15 is connected to the third heat exchanger 4 through the refrigerant pipeline, and the first auxiliary expansion valve 16 is connected to the first economizer 14 through the refrigerant circuit.

[0020] In this embodiment, the fourth heat exchanger 6 is connected to a second liquid receiver 17 via a refrigerant pipeline. The second liquid receiver 17 is connected to a second economizer 18 and a second compressor 19 via a refrigerant pipeline. The second compressor 19 is connected to the fourth heat exchanger 6. The second economizer 18 is connected to the second main expansion valve 20 and the sixth heat exchanger 21 via a refrigerant circuit. The sixth heat exchanger 21 is connected to the second gas-liquid separator 22 via a refrigerant circuit. The second gas-liquid separator 22 is connected to the second compressor 19 via a refrigerant circuit.

[0021] In this embodiment, the second economizer 18 is also connected to a second auxiliary expansion valve 23 via a refrigerant circuit.

[0022] In this embodiment, the sixth heat exchanger 21 is sequentially connected to the buffer water tank 24, the circulating water pump 25, the seventh heat exchanger 26, and the fifth heat exchanger 12 via a circulating water loop. The sixth heat exchanger 21, the buffer water tank 24, the circulating water pump 25, the seventh heat exchanger 26, and the fifth heat exchanger 12 form a circulating water loop. The seventh heat exchanger 26 is connected to the cooling tower 7 and the second heat exchanger 3 via a cooling water loop. The seventh heat exchanger 26 is connected to the second heat exchanger 3 via a second valve 27 and a first valve 9.

[0023] The specific process flow of this application is as follows: (1) NMP recovery side The high-temperature NMP exhaust gas (110-130℃) is discharged from the coating machine oven and undergoes cooling treatment sequentially through the first heat exchanger 2, the second heat exchanger 3, and the third heat exchanger 4. First, it is cooled to 40-50℃ in the first heat exchanger 2, then further cooled to 30-35℃ in the second heat exchanger 3, and finally cooled to below 15℃ in the third heat exchanger 4, achieving efficient recovery of NMP condensate. After treatment, 5-10% of the exhaust gas enters the tail gas treatment system and is discharged after meeting standards; 90-95% of the exhaust gas is used as recirculated return air, first heated to 100-110℃ in the second heat exchanger 3, then heated to above 150℃ in the fourth heat exchanger 6, and finally returned to the coating machine oven.

[0024] (2) First refrigerant side The first refrigerant, a low-temperature, low-pressure gas-liquid two-phase medium at 5-10℃, absorbs heat from the NMP waste gas in the third heat exchanger 4, completely vaporizing into a low-temperature, low-pressure refrigerant at 15-20℃. It is then separated by the first gas-liquid separator 10 and enters the first compressor 11 for pressurization, increasing its temperature to a high-temperature, high-pressure gas-phase refrigerant at 90-100℃. Afterwards, it releases heat to the circulating water in the fifth heat exchanger 12, completely liquefying into a medium-temperature, high-pressure liquid-phase refrigerant at 40-50℃. The refrigerant then flows through the first liquid receiver 13 and the first economizer 14. Part of the refrigerant is throttled and cooled to a low temperature and low pressure of 30~40℃ by the first auxiliary expansion valve 16. It then returns to the first economizer 14 to exchange heat with the medium temperature and high pressure liquid phase refrigerant of 40~50℃, and is completely vaporized into a medium temperature and high pressure gas phase refrigerant of 35~45℃, before returning to the first compressor 11. The remaining refrigerant is throttled and cooled by the first main expansion valve 15, becoming a low temperature and low pressure gas-liquid two-phase refrigerant of 5~10℃, and returns to the third heat exchanger 4 to complete the cycle.

[0025] (3) Second refrigerant side The 40-50℃ low-temperature, low-pressure gas-liquid two-phase refrigerant absorbs heat from the circulating water in the sixth heat exchanger 21, completely vaporizing into a 50-60℃ low-temperature, low-pressure gas-phase second refrigerant. After being separated by the second gas-liquid separator 22, it enters the second compressor 19 for pressurization and temperature increase to a high-temperature, high-pressure gas-phase second refrigerant above 150℃. Subsequently, it releases heat to the NMP waste gas in the fourth heat exchanger 6, completely liquefying into a 110-120℃ medium-temperature, high-pressure liquid-phase second refrigerant. The refrigerant then flows through the second liquid receiver 17 and the second economizer 18. Part of the refrigerant is throttled and cooled to a low-temperature, low-pressure liquid phase refrigerant of 100~110℃ by the second auxiliary expansion valve 23. It then returns to the second economizer 18 and exchanges heat with the medium-temperature, high-pressure liquid phase second refrigerant of 110~120℃. After that, it is completely vaporized into a low-temperature, low-pressure gas phase refrigerant of 105~115℃ and returns to the second compressor 19. The remaining part of the refrigerant is throttled and cooled by the second main expansion valve 20, becoming a low-temperature, low-pressure gas-liquid two-phase refrigerant of 40~50℃. It then returns to the sixth heat exchanger 21 to complete the cycle.

[0026] (4) Circulating water side After the first refrigerant releases heat to the circulating water in the fifth heat exchanger 12, part of the heat carried by the circulating water is released to the second refrigerant in the sixth heat exchanger 21, and another part is released to the cooling water in the seventh heat exchanger 26. It is also equipped with a buffer water tank (electric auxiliary heating device) to complete the pre-production, storage, distribution and transfer of heat.

[0027] (5) Cooling water side Cooling water at 25-32℃ flows out from cooling tower 7. Part of it is regulated by first valve 9 and flows through second heat exchanger 3 to cool NMP exhaust gas; the other part is regulated by second valve 27 and flows through seventh heat exchanger 26 to cool circulating water, ensuring that the system temperature is stable within a reasonable range and guaranteeing the normal operation of each component.

[0028] A control method for an NMP exhaust gas recovery system for a coating machine chassis, characterized in that: Assume there is Section 1 coating machine drying oven, set the first The return air temperature of the oven in the coating machine drying oven system 1 is: (°C), Total circulating air volume is (m) 3 / h), exhaust air volume is （m 3 / h） The exhaust temperature is (°C), NMP exhaust concentration is (ppm) and fresh air temperature （℃） The condensate return air temperature of the NMP recovery system is (°C), waste heat recovery heat exchange efficiency is The return air ratio is The NMP exhaust gas, after being cooled by cooling tower 7, has a temperature of [temperature value missing]. （℃） The maximum heating return air temperature of the heat pump unit is （℃） The refrigeration COP of the first compressor 11 is The heating COP of the second compressor 19 is When the heat pump unit is connected one-to-one with the coating machine oven 1, the first The heating capacity required for the coating machine drying oven system 1 (kW) and the corresponding heat pump unit heating capacity (kW) and auxiliary heating capacity (kW) And the cooling capacity required for the NMP recovery system (kW) and the corresponding cooling capacity of the heat pump unit (kW) and the heat dissipation of cooling tower 7 The calculation process for (kW) is as follows: Coating machine drying oven system 1: ； ； ； in, ； ； ； ； ； NMP recycling system: ； ； ； In this embodiment, ； ； ； in, 、 and The first Taiwan coating NMP recycling integrated machine NMP from Condensation 、 from Condensation and from Condensation The latent heat of condensation released during the process, therefore, Total heating capacity required for coating machine drying oven system 1 (kW) and the total heating capacity of the corresponding heat pump units (kW) Total heating capacity of auxiliary heating (kW) and the total cooling capacity required for the NMP recovery system. (kW) and the corresponding total cooling capacity of the heat pump unit (kW) Total heat dissipation of cooling tower 7 (kW) The calculation process is as follows: ； ； ； ； ； 。

[0029] In this embodiment, the power of each circulating fan 55 in the coating machine oven 1 system is set to... (kW) The NMP recycling system has a power of 55 for each circulating fan. (kW) Auxiliary heating can be electric heating, steam, or other heating methods such as heat transfer oil. Taking electric heating as an example, let the electrothermal efficiency be... Assume the heat dissipation COP of cooling tower 7 is... The power consumption of the entire coating NMP recycling integrated system is then determined. (kW) and its corresponding fan power (kW) Compressor power (kW) Auxiliary heating power (kW) and cooling tower 7 heat dissipation power (kW) The calculation process is as follows: ； ； ； ； 。

[0030] The NMP exhaust gas recovery system for coating machine provided by this invention has the advantages of stable performance, high reliability, and energy saving. Through unique structural design and precise system temperature calculation and control method, this application can ensure that the system temperature is stable within a reasonable range, guarantee the normal operation of each link, and thus ensure the stability and reliability of the system.

[0031] 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 coating machine chassis NMP exhaust gas recovery system, characterized in that: The system includes a first heat exchanger, a second heat exchanger, a third heat exchanger, a circulating fan, and a fourth heat exchanger, which are sequentially connected to the exhaust vent of the coating machine oven via ducts. The fourth heat exchanger is connected to the return air vent of the oven via ducts. The first heat exchanger, the second heat exchanger, the third heat exchanger, the circulating fan, and the fourth heat exchanger form a waste gas treatment circulation loop.

2. The NMP exhaust gas recovery system for a coating machine chassis according to claim 1, characterized in that: The second heat exchanger is connected to a cooling water tower via a cooling water circuit, and a cooling water pump and a first valve are provided on the circulating water circuit between the cooling water tower and the second heat exchanger.

3. The NMP exhaust gas recovery system for a coating machine chassis according to claim 1, characterized in that: The third heat exchanger is connected to the first gas-liquid separator via a refrigerant pipeline, and the first gas-liquid separator is connected to the first compressor. The first compressor is connected to a fifth heat exchanger and a first liquid receiver via refrigerant piping.

4. The NMP exhaust gas recovery system for a coating machine chassis according to claim 1, characterized in that: The first liquid receiver is connected to the first compressor via a first economizer, and is connected to a first main expansion valve and a first auxiliary expansion valve via a refrigerant pipeline. The first main expansion valve is connected to the third heat exchanger via a refrigerant pipeline, and the first auxiliary expansion valve is connected to the first economizer via a refrigerant circuit.

5. The NMP exhaust gas recovery system for a coating machine chassis according to claim 3, characterized in that: The fourth heat exchanger is connected to a second liquid receiver via refrigerant piping. The second liquid receiver is connected to a second economizer and a second compressor via refrigerant piping. The second compressor is connected to the fourth heat exchanger. The second economizer is connected to the second main expansion valve and the sixth heat exchanger via a refrigerant circuit. The sixth heat exchanger is connected to the second gas-liquid separator via a refrigerant circuit, and the second gas-liquid separator is connected to the second compressor via a refrigerant circuit.

6. The NMP exhaust gas recovery system for a coating machine chassis according to claim 1, characterized in that: The second economizer is also connected to a second auxiliary expansion valve via a refrigerant circuit.

7. The NMP exhaust gas recovery system for a coating machine chassis according to claim 5, characterized in that: The sixth heat exchanger is sequentially connected to a buffer water tank, a circulating water pump, a seventh heat exchanger, and the fifth heat exchanger via a circulating water loop. The sixth heat exchanger, the buffer water tank, the circulating water pump, the seventh heat exchanger, and the fifth heat exchanger form a circulating water loop. The seventh heat exchanger is connected to the cooling tower and the second heat exchanger via a cooling water loop.

8. A control method for an NMP exhaust gas recovery system for a coating machine chassis, characterized in that: Assume there is Section coating machine drying oven, set the first The return air temperature of the drying oven system of the coating machine is （℃） Total circulating air volume is （m 3 / h） The exhaust air volume is （m 3 / h） The exhaust temperature is （℃） NMP exhaust concentration is (ppm) and fresh air temperature （℃） The condensate return air temperature of the NMP recovery system is （℃） The waste heat recovery heat exchange efficiency is The return air ratio is The temperature of the NMP exhaust gas after being cooled by the cooling tower is （℃） The maximum heating return air temperature of the heat pump unit is （℃） The refrigeration COP of the first compressor is The heating COP of the second compressor is When the heat pump unit is connected one-to-one with the coating machine oven, the first The heating capacity required for the coating machine drying oven system (kW) and the corresponding heat pump unit heating capacity (kW) and auxiliary heating capacity (kW) and the cooling capacity required for the NMP recovery system. (kW) and the corresponding cooling capacity of the heat pump unit (kW) and the heat dissipation of cooling towers (kW) The calculation process is as follows: Coating machine drying oven system: ； ； ； in, ； ； ； ； ； NMP recycling system: ； ； 。 9. The control method for a coating machine chassis NMP exhaust gas recovery system according to claim 8, characterized in that: ； ； ； in, 、 and The first Taiwan coating NMP recycling integrated machine NMP from Condensation ,from Condensation and from Condensation The latent heat of condensation released during the process, therefore, Total heating capacity required for coating machine drying oven system (kW) and the total heating capacity of the corresponding heat pump units (kW) Total heating capacity of auxiliary heating (kW) and the total cooling capacity required for the NMP recovery system. (kW) and the corresponding total cooling capacity of the heat pump unit (kW) Total heat dissipation of cooling tower (kW) The calculation process is as follows: ； ； ； ； ； 。 10. The control method of claim 8, wherein: Assume the power of each circulating fan in the coating machine drying oven system is... (kW) The power of each circulating fan in the NMP recycling system is... (kW) Auxiliary heating can be electric heating, steam, or other heating methods such as heat transfer oil. Taking electric heating as an example, let the electrothermal efficiency be... Assume the heat dissipation COP of the cooling tower is... The power consumption of the entire coating NMP recycling integrated system is then determined. (kW) and its corresponding fan power (kW) Compressor power (kW) Auxiliary heating power (kW) and cooling tower heat dissipation power (kW) The calculation process is as follows: ； ； ； ； 。

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