Cold and heat combined supply system for coating and drying nmp recovery in power battery factory

Abstract

This invention discloses a combined cooling and heating system for NMP recovery during coating and drying in a power battery factory. It includes an exhaust duct connected to a coating machine. NMP exhaust gas in the exhaust duct serves as a heat source gas, sequentially entering a first heat pipe heat exchanger, a second heat pipe heat exchanger, and the evaporator of a heat pump unit. A return air duct and a circulating air duct are connected in parallel at the evaporator outlet. NMP exhaust gas in the return air duct serves as a cold source gas, sequentially entering the second heat pipe heat exchanger, the first heat pipe heat exchanger, and the condenser of the heat pump unit. The return air duct at the condenser outlet is connected to the coating machine's inlet air duct. NMP exhaust gas in the circulating air duct, after passing through a rotary adsorption unit, partially enters the exhaust duct, and the remaining portion enters the external discharge duct. NMP recovery pipes are installed on both the second heat pipe heat exchanger and the evaporator. This invention has an ingenious structure, is easy to use, and can significantly reduce energy consumption in the coating and drying process of lithium-ion battery production.

Description

Technical Field

[0001] This invention relates to the field of lithium battery production technology, and in particular to a combined cooling and heating system for coating, drying, NMP recovery, and power supply in power battery factories. Background Technology

[0002] In recent years, with the widespread adoption and promotion of new energy vehicles, electrochemical energy storage, and mobile phones, the lithium battery industry has experienced rapid development. Wet coating of positive and negative electrode sheets for lithium-ion batteries is one of the mainstream core processes in current cell manufacturing. According to surveys, energy consumption during lithium battery production accounts for approximately 66% of the total energy consumption, and of that, 38% is used for the drying process. This is because the humid air discharged during coating and drying has a high NMP content. NMP, as an important auxiliary coating material for the positive electrode of lithium batteries, is expensive. If it is not effectively recycled, it not only wastes important material resources but also has adverse environmental impacts. Therefore, condensation and recovery are necessary, resulting in high energy consumption. Currently, coating drying generally uses steam heating at temperatures above 160℃ to bring the intake air of the coating machine to 130-150℃ for drying; the exhaust air from the coating machine first passes through a heat recovery heat exchanger, then is cooled by cooling circulating water, and finally condenses through chilled circulating water. The aforementioned drying steam generally comes from gas-fired steam boilers, which have high fuel costs, but not all steam condensate can be recovered, resulting in low overall energy efficiency. Heat recovery heat exchangers are mostly shell-and-tube type, with large heat exchange areas, but low gas-to-gas heat exchange efficiency. Cooling circulating water dissipates heat into the air through a cooling tower; this process consumes a lot of electricity for the circulating water pump and wastes low-grade heat energy in the exhaust air. Chilled circulating water is obtained through a refrigeration unit, which requires a large amount of electricity to operate. Therefore, adopting effective technical means to achieve energy saving and consumption reduction in the coating and drying process will significantly reduce the production cost of lithium battery manufacturing. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a combined cooling and heating system for NMP (Non-Mechanical Processing) recycling in power battery factories, specifically employing the following technical solution:

[0004] The present invention discloses a combined cooling and heating system for NMP recovery during coating and drying in a power battery factory. The system includes an exhaust duct connected to a coating machine. NMP exhaust gas in the exhaust duct serves as a heat source gas, sequentially entering a first heat pipe heat exchanger, a second heat pipe heat exchanger, and the evaporator of a heat pump unit. A return air duct and a circulating air duct are connected in parallel at the evaporator outlet. NMP exhaust gas in the return air duct serves as a cold source gas, sequentially entering the second heat pipe heat exchanger, the first heat pipe heat exchanger, and the condenser of the heat pump unit. The return air duct at the condenser outlet is connected to the coating machine's inlet air duct. After passing through a rotary adsorption unit, a portion of the NMP exhaust gas in the circulating air duct enters the exhaust duct, and the remaining portion enters the external exhaust duct. NMP recovery pipes are installed on both the second heat pipe heat exchanger and the evaporator.

[0005] The heat pump unit includes an evaporator, a compressor, a condenser, and a pressure reducing valve arranged sequentially on a circulation pipeline. The heat exchange medium in the circulation pipeline circulates along the evaporator, the compressor, the condenser, and the pressure reducing valve.

[0006] The rotary adsorption unit includes an adsorption rotor, which is disposed in a rotor housing divided into an adsorption zone, a regeneration zone, and a cooling zone. The circulating air duct is disposed at the inlet end of the adsorption zone, and a recovery pipe and the exhaust pipe are disposed in parallel at the outlet end of the adsorption zone. The recovery pipe passes through the cooling zone, the recovery heater, and the regeneration zone in sequence before being connected to the exhaust pipe.

[0007] An exhaust fan is installed on the exhaust duct on the inlet side of the first heat pipe heat exchanger, a return air fan and an inlet air heater are installed on the return air duct on the outlet side of the condenser, a circulating fan and a regulating valve are installed on the circulating air duct on the inlet side of the adsorption zone, an external exhaust fan is installed at the outlet of the adsorption zone, and a regeneration fan is installed on the recovery duct on the outlet side of the regeneration zone.

[0008] Both the recovery heater and the air inlet heater are steam / electric heaters.

[0009] The NMP exhaust gas in the exhaust duct has a temperature of 125~135℃ at the exhaust fan outlet, 75~85℃ at the outlet of the first heat pipe heat exchanger, 35~45℃ at the outlet of the second heat pipe heat exchanger, and 12~17℃ at the evaporator outlet; the NMP exhaust gas in the return air duct has a temperature of 45~55℃ at the outlet of the second heat pipe heat exchanger, 85~95℃ at the outlet of the first heat pipe heat exchanger, 115~125℃ at the condenser outlet, and 130~150℃ at the outlet of the inlet air heater.

[0010] The NMP exhaust gas volume ratio entering the return air duct and the circulating air duct from the evaporator outlet is 95:5, and the NMP exhaust gas volume ratio entering the recovery pipe and the exhaust pipe from the exhaust fan outlet is 4:1.

[0011] This invention provides a combined cooling and heating system for NMP recovery in the coating and drying process of a power battery factory. First, it employs a two-stage heat pipe heat exchanger to recover heat from the coating machine's exhaust air. The heat pipe heat exchanger features high heat transfer efficiency, compact structure, and low pressure loss. Specifically, the first heat pipe heat exchanger recovers the higher-temperature heat from the coating machine's exhaust air and transfers it to the medium-temperature return air. The second heat pipe heat exchanger recovers the medium-temperature heat from the coating machine's exhaust air and transfers it to the lower-temperature return air, causing partial condensation of the NMP in the exhaust air. Second, it utilizes a large temperature difference heat pump technology to achieve combined cooling and heating. The heat pump evaporator recovers the lower-temperature heat from the coating machine's exhaust air and causes most of the remaining NMP in the exhaust air to condense. The heat recovered by the heat pump evaporator is pumped to the condenser after being upgraded by a compressor. The condenser then transfers the heat recovered by the evaporator to the coating machine's return air. Through these measures, both the condensation of the coating machine's exhaust air and the heating of the return air are simultaneously achieved.

[0012] This invention features a clever structure and is easy to use, significantly reducing energy consumption in the coating and drying process of lithium-ion battery production. Compared with existing technologies, the advantages of this invention are as follows:

[0013] 1) Utilize a two-stage heat pipe heat exchanger to recover the high-temperature and medium-temperature exhaust air from the coating machine and then transfer it to the medium-temperature and low-temperature return air from the coating machine to achieve natural heat exchange.

[0014] 2) It adopts a two-stage heat pipe heat exchanger, which has high heat transfer efficiency, compact structure and low pressure loss;

[0015] 3) The use of large temperature difference heat pump technology can realize the simultaneous supply of cooling and heating, saving the electricity consumed in producing chilled water and some of the energy consumed in producing high temperature steam in traditional processes. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0017] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific working processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0018] like Figure 1As shown, the NMP recovery and combined cooling and heating system for coating and drying in a power battery factory according to the present invention includes an exhaust pipe 1 connected to the coating machine. NMP exhaust gas in the exhaust pipe 1 serves as a heat source gas and sequentially enters the first heat pipe heat exchanger 2, the second heat pipe heat exchanger 3, and the evaporator 41 of the heat pump unit. A return air pipe 5 and a circulating air pipe 6 are connected in parallel at the outlet of the evaporator 41. NMP exhaust gas in the return air pipe 5 serves as a cold source gas and sequentially enters the second heat pipe heat exchanger 3, the first heat pipe heat exchanger 2, and the condenser 42 of the heat pump unit. The return air pipe 5 at the outlet of the condenser 42 is connected to the inlet air pipe of the coating machine. The heat pump unit includes an evaporator 41, a compressor 43, a condenser 42, and a pressure reducing valve 44 sequentially arranged in the circulating pipeline. The heat exchange medium in the circulating pipeline circulates along the evaporator 41, compressor 43, condenser 42, and pressure reducing valve 44. NMP recovery pipes are provided on both the second heat pipe heat exchanger 3 and the evaporator 41.

[0019] Under normal circumstances, the temperature of NMP exhaust gas in exhaust duct 1 is 125~135℃ at the inlet of the first heat pipe heat exchanger 2, 75~85℃ at the outlet of the first heat pipe heat exchanger 2, 35~45℃ at the outlet of the second heat pipe heat exchanger 3, and 12~17℃ at the outlet of the evaporator 41; the temperature of NMP exhaust gas in return air duct 5 is 45~55℃ at the outlet of the second heat pipe heat exchanger 3, 85~95℃ at the outlet of the first heat pipe heat exchanger 2, and 115~125℃ at the outlet of the condenser 42.

[0020] As can be seen, the first heat pipe heat exchanger 2 is used to recover the higher-temperature heat in the coating machine exhaust air and transfer it to the medium-temperature coating machine return air. The second heat pipe heat exchanger 3 is used to recover the medium-temperature heat in the coating machine exhaust air and transfer it to the lower-temperature coating machine return air, while simultaneously condensing some of the NMP in the coating machine exhaust air. Secondly, a large temperature difference heat pump technology is used to achieve combined cooling and heating. Specifically, the heat pump evaporator 41 recovers the lower-temperature heat in the coating machine exhaust air and condenses most of the remaining NMP in the exhaust air. The heat recovered by the heat pump evaporator 41 is pumped to the condenser 42 after the compressor 43 improves the heat energy quality. The condenser 42 then transfers the heat recovered by the evaporator 41 to the coating machine return air. Through these measures, the condensation of the coating machine exhaust air and the heating of the return air are achieved simultaneously.

[0021] The evaporator 41 described above has a return air duct 5 and a circulating air duct 6 connected in parallel at its outlet. Under normal circumstances, the volume ratio of NMP exhaust gas entering the return air duct 5 and the circulating air duct 6 is usually maintained at 95:5. After passing through the rotary adsorption unit, part of the NMP exhaust gas entering the circulating air duct 6 enters the exhaust duct 1, and the other part enters the external exhaust duct 7.

[0022] Specifically, the rotary adsorption unit includes an adsorption rotor, which is installed in a rotor housing divided into an adsorption zone, a regeneration zone, and a cooling zone. A circulating air duct 6 is installed at the inlet end of the adsorption zone, and a recovery pipe 8 and an exhaust pipe 7 are connected in parallel at the outlet end of the adsorption zone. The recovery pipe 8 passes through the cooling zone, the recovery heater 9, and the regeneration zone in sequence before being connected to the exhaust pipe 1.

[0023] The working process of the rotary adsorption unit is as follows: The adsorption rotor rotates continuously, sequentially moving to the adsorption zone, regeneration zone, and cooling zone, repeating this sequence continuously. When the NMP exhaust gas in the circulating air duct 6 enters the adsorption zone, the effective components of the gas are adsorbed by the adsorption rotor and can be discharged as purified exhaust gas. The adsorption rotor then rotates to the regeneration zone, where hot air is introduced, causing the adsorbed NMP to desorb and be sent to the exhaust duct 1 via the recovery pipe 8 for heat exchange and condensation recovery. Then, the adsorption rotor rotates to the cooling zone, where it exchanges heat with the low-temperature purified exhaust gas entering the recovery pipe 8. After the adsorption rotor temperature drops to the adsorption temperature, it rotates again to enter the adsorption zone for NMP adsorption. The low-temperature purified exhaust gas in the recovery pipe 8 experiences a temperature increase after heat exchange and enters the recovery heater 9 for use as regenerated air, achieving energy saving.

[0024] The volume ratio of NMP exhaust gas entering the recovery pipe 8 and the discharge pipe 7 is typically 4:1.

[0025] Preferably, an exhaust fan 10 is installed on the exhaust duct 1 at the inlet side of the first heat pipe heat exchanger 2, a return air fan 11 and an inlet air heater 12 are installed on the return air duct 5 at the outlet side of the condenser 42, a circulating fan 13 and a regulating valve 14 are installed on the circulating air duct 6 at the inlet side of the adsorption zone, an external exhaust fan 15 is installed at the outlet of the adsorption zone, and a regeneration fan 16 is installed on the recovery pipe 8 at the outlet side of the regeneration zone. Both the recovery heater 9 and the inlet air heater 12 are steam / electric heaters, and the temperature at the outlet of the inlet air heater 12 is 130~150℃.

[0026] It should be noted that in the description of this invention, terms such as "front," "rear," "left," "right," "vertical," "horizontal," "inner," and "outer" indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

Claims

1. A cold and heat combined supply system for power battery factory coating drying NMP recovery, characterized in that: The exhaust pipe connected with the coating machine, the NMP exhaust gas in the exhaust pipe enters the first heat pipe heat exchanger, the second heat pipe heat exchanger and the evaporator of the heat pump unit in sequence as the heat source gas; the outlet of the evaporator is connected with the return air pipe and the circulating air pipe, the NMP exhaust gas in the return air pipe enters the second heat pipe heat exchanger, the first heat pipe heat exchanger and the condenser of the heat pump unit in sequence as the cold source gas, the outlet of the condenser is connected with the air inlet pipe of the coating machine; the NMP exhaust gas in the circulating air pipe passes through the rotary adsorption unit, part of which enters the exhaust pipe and the other part enters the exhaust pipe; the NMP recovery pipe is arranged on the second heat pipe heat exchanger and the evaporator; The rotary adsorption unit comprises an adsorption wheel, the adsorption wheel is arranged in a rotary wheel shell which is divided into an adsorption zone, a regeneration zone and a cooling zone, the circulating air pipe is arranged at the inlet end of the adsorption zone, the outlet end of the adsorption zone is connected with the recovery pipe and the exhaust pipe, the recovery pipe passes through the cooling zone, the recovery heater and the regeneration zone in sequence and is connected with the exhaust pipe; The exhaust fan is arranged on the exhaust pipe at the inlet side of the first heat pipe heat exchanger, the return fan and the air inlet heater are arranged on the return air pipe at the outlet side of the condenser, the circulating fan and the adjusting valve are arranged on the circulating air pipe at the inlet side of the adsorption zone, the exhaust fan is arranged at the outlet of the adsorption zone, and the regeneration fan is arranged on the recovery pipe at the outlet side of the regeneration zone; The temperature of the NMP exhaust gas in the exhaust pipe is 125-135℃ at the outlet of the exhaust fan, 75-85℃ at the outlet of the first heat pipe heat exchanger, 35-45℃ at the outlet of the second heat pipe heat exchanger and 12-17℃ at the outlet of the evaporator; the temperature of the NMP exhaust gas in the return air pipe is 45-55℃ at the outlet of the second heat pipe heat exchanger, 85-95℃ at the outlet of the first heat pipe heat exchanger, 115-125℃ at the outlet of the condenser and 130-150℃ at the outlet of the air inlet heater; The volume ratio of the NMP exhaust gas entering the return air pipe and the circulating air pipe at the outlet of the evaporator is 95:5, and the volume ratio of the NMP exhaust gas entering the recovery pipe and the exhaust pipe at the outlet of the exhaust fan is 4:

1.

2. The combined cooling and heating system for NMP recovery in a power battery factory coating and drying according to claim 1, characterized in that: The heat pump unit comprises the evaporator, the compressor, the condenser and the pressure reducing valve arranged in sequence on the circulating pipeline, and the heat exchange medium in the circulating pipeline circulates along the evaporator, the compressor, the condenser and the pressure reducing valve.

3. The combined cooling and heating system for NMP recovery in a power battery factory coating and drying according to claim 1, characterized in that: The recovery heater and the air inlet heater are steam / electric heaters.

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