NMP recovery cold and heat combined supply system for coating and drying of power battery factory

Abstract

The invention discloses an NMP (N-Methyl Pyrrolidone) recycling cold and heat combined supply system for coating and drying in a power battery factory, which comprises an exhaust pipe connected with a coating machine, and NMP waste gas in the exhaust pipe sequentially enters a first heat pipe heat exchanger, a second heat pipe heat exchanger and an evaporator of a heat pump unit as heat source gas; an air return pipe and a circulating air pipe are arranged at an outlet of the evaporator in parallel, NMP waste gas in the air return pipe serves as cold source gas to sequentially enter the second heat pipe heat exchanger, the first heat pipe heat exchanger and a condenser of the heat pump unit, and the air return pipe at an outlet of the condenser is connected with the coating machine air inlet pipe. After the NMP waste gas in the circulating air pipe passes through the rotating wheel adsorption unit, one part of the NMP waste gas enters the exhaust pipe, and the other part of the NMP waste gas enters the discharge pipe; nMP recovery pipes are arranged on the second heat pipe exchanger and the evaporator. The coating and drying device is ingenious in structure and convenient to use, and energy consumption of the coating and drying process in lithium ion battery production can be greatly saved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery production, and in particular to a cold and hot combined supply system for coating and drying NMP recovery in a power battery factory. Background Art

[0002] In recent years, with the popularization and promotion of new energy vehicles, electrochemical energy storage, and mobile phones, the lithium battery industry has achieved great development. Wet coating of positive and negative electrodes of ion batteries is one of the mainstream core processes in the current battery manufacturing field. According to surveys, the energy consumption in the production process of lithium batteries accounts for about 66% of the total energy consumption of production and manufacturing, and 38% of the energy consumption in the production process is used for drying. This is because the NMP content in the wet air discharged from the coating and drying is very high. NMP is an important auxiliary coating material for the positive electrode of lithium batteries. The price is relatively high. If it is not effectively recycled, it will not only cause a waste of important material resources, but also have an adverse impact on the environment. Therefore, condensation recovery is required, resulting in higher energy consumption. At present, the coating and drying generally use steam above 160°C to heat the coater air intake to 130~150°C for drying and coating; and the coater exhaust first passes through a heat recovery heat exchanger, then uses cooling circulating water for cooling, and finally condenses through refrigerated circulating water. The above-mentioned drying steam generally comes from a gas-fired steam boiler, which has a high fuel cost, but the steam condensate cannot be fully recovered, and the overall energy utilization efficiency is low; the heat recovery heat exchanger is mostly a shell and tube heat exchanger, which has a large heat exchange area, but the gas-to-gas heat exchange efficiency is low; the cooling circulating water dissipates heat into the air through the cooling tower. In this process, the circulating water pump consumes a lot of electricity and wastes the low-grade heat energy in the exhaust air; the refrigerated circulating water is extracted by a refrigerator, and the operation of the refrigerator consumes a lot of electricity. It can be seen that if effective technical means are adopted to achieve energy saving and consumption reduction in the coating and drying process, the production cost of lithium battery manufacturing will be greatly reduced. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a cold and hot cogeneration system for NMP recovery in coating and drying in a power battery factory, which can specifically adopt the following technical solutions: The NMP recovery and cooling combined supply system for coating and drying in a power battery factory described in the present invention comprises an exhaust duct connected to a coater, wherein the NMP waste gas in the exhaust duct sequentially enters a first heat pipe heat exchanger, a second heat pipe heat exchanger and an evaporator of a heat pump unit as a heat source gas; a return air duct and a circulating air duct are arranged in parallel at the outlet of the evaporator, and the NMP waste gas in the return air duct sequentially enters the second heat pipe heat exchanger, the first heat pipe heat exchanger and the condenser of the heat pump unit as a cold source gas, and the return air duct at the outlet of the condenser is connected to the air inlet duct of the coater; after the NMP waste gas in the circulating air duct passes through a rotary adsorption unit, a part of it enters the exhaust duct and the other part enters the external exhaust pipe; an NMP recovery pipe is arranged on both the second heat pipe heat exchanger and the evaporator.

[0004] The heat pump unit includes the evaporator, the compressor, the condenser and the pressure reducing valve which are sequentially arranged on the circulation pipeline, and the heat exchange medium in the circulation pipeline circulates along the evaporator, the compressor, the condenser and the pressure reducing valve.

[0005] The rotary adsorption unit includes an adsorption rotary wheel, which is arranged in a rotary shell divided into an adsorption zone, a regeneration zone and a cooling zone. The circulating air duct is arranged at the inlet end of the adsorption zone, and a recovery pipe and the external exhaust pipe are arranged 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 and is connected to the exhaust pipe.

[0006] An exhaust fan is arranged on the exhaust duct on the inlet side of the first heat pipe heat exchanger, a return fan and an inlet air heater are arranged on the return air duct on the outlet side of the condenser, a circulation fan and a regulating valve are arranged on the circulation air duct on the inlet side of the adsorption zone, an external exhaust fan is arranged at the outlet of the adsorption zone, and a regeneration fan is arranged on the recovery pipe on the outlet side of the regeneration zone.

[0007] The recovery heater and the air inlet heater are both steam / electric heaters.

[0008] The temperature of the NMP waste gas in the exhaust duct at the outlet of the exhaust fan is 125-135°C, the temperature at the outlet of the first heat pipe heat exchanger is 75-85°C, the temperature at the outlet of the second heat pipe heat exchanger is 35-45°C, and the temperature at the outlet of the evaporator is 12-17°C; the temperature of the NMP waste gas in the return air duct at the outlet of the second heat pipe heat exchanger is 45-55°C, the temperature at the outlet of the first heat pipe heat exchanger is 85-95°C, the temperature at the outlet of the condenser is 115-125°C, and the temperature at the outlet of the air inlet heater is 130-150°C.

[0009] The volume ratio of NMP waste gas entering the return air duct and the circulation air duct from the evaporator outlet is 95:5, and the volume ratio of NMP waste gas entering the recovery pipe and the external exhaust pipe from the external exhaust fan outlet is 4:1.

[0010] The present invention provides a combined heat and cold supply system for NMP recovery in coating and drying in a power battery factory. First, a two-stage heat pipe heat exchanger is used to recover the heat in the exhaust air of the coater. The heat pipe heat exchanger has the characteristics of high heat transfer efficiency, compact structure, and small pressure loss. Among them, the first heat pipe heat exchanger recovers the heat at a higher temperature in the exhaust air of the coater and transfers it to the return air of the coater at a medium temperature. The second heat pipe heat exchanger recovers the heat at a medium temperature in the exhaust air of the coater and transfers it to the return air of the coater at a lower temperature, and partially condenses the NMP in the exhaust air of the coater. Secondly, a large temperature difference heat pump technology is used to achieve combined heat and cold supply. The heat pump evaporator recovers the heat at a lower temperature in the exhaust air of the coater, and condenses most of the remaining NMP in the exhaust air of the coater. The heat recovered by the heat pump evaporator is pumped to the condenser after the compressor improves the heat energy grade, and the condenser transfers the heat recovered by the evaporator to the return air of the coater. Through the above measures, the condensation of the exhaust air of the coater and the heating of the return air are achieved at the same time.

[0011] The present invention has an ingenious structure and is easy to use, and can greatly save energy consumption in the coating and drying process in the production of lithium-ion batteries. Compared with the prior art, the advantages of the present invention are as follows: 1) Use a two-stage heat pipe heat exchanger to recover the high-temperature and medium-temperature coating machine exhaust air respectively and then transfer it to the medium-temperature and low-temperature coating machine return air to achieve natural heat exchange; 2) Adopt two-stage heat pipe heat exchanger with high heat transfer efficiency, compact structure and small pressure loss; 3) The large temperature difference heat pump technology can realize the combined supply of cooling and heating, saving the electricity consumed by the traditional process of producing chilled water and part of the energy consumed by producing high-temperature steam. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0013] The following is a detailed description of an embodiment of the present invention in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific working process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0014] like Figure 1As shown, the NMP recovery and cooling combined supply system for coating and drying in a power battery factory of the present invention comprises an exhaust pipe 1 connected to a coating machine, and the NMP waste gas in the exhaust pipe 1 enters the first heat pipe heat exchanger 2, the second heat pipe heat exchanger 3 and the evaporator 41 of the heat pump unit in sequence as a heat source gas; the outlet of the evaporator 41 is provided with a return air pipe 5 and a circulating air pipe 6 in parallel, and the NMP waste gas in the return air pipe 5 enters the second heat pipe heat exchanger 3, the first heat pipe heat exchanger 2 and the condenser 42 of the heat pump unit in sequence as a cold source gas, and the return air pipe 5 at the outlet of the condenser 42 is connected to the air inlet pipe of the coating machine; the above-mentioned heat pump unit comprises an evaporator 41, a compressor 43, a condenser 42 and a pressure reducing valve 44 arranged in sequence on the circulation pipeline, and the heat exchange medium in the circulation pipeline circulates along the evaporator 41, the compressor 43, the condenser 42 and the pressure reducing valve 44. The above-mentioned second heat pipe heat exchanger 3 and the evaporator 41 are both provided with an NMP recovery pipe.

[0015] Normally, the temperature of the NMP waste gas in the exhaust duct 1 at the inlet of the first heat pipe heat exchanger 2 is 125~135°C, the temperature at the outlet of the first heat pipe heat exchanger 2 is 75~85°C, the temperature at the outlet of the second heat pipe heat exchanger 3 is 35~45°C, and the temperature at the outlet of the evaporator 41 is 12~17°C; the temperature of the NMP waste gas in the return air duct 5 at the outlet of the second heat pipe heat exchanger 3 is 45~55°C, the temperature at the outlet of the first heat pipe heat exchanger 2 is 85~95°C, and the temperature at the outlet of the condenser 42 is 115~125°C.

[0016] It can be seen that the first heat pipe heat exchanger 2 is used to recover the heat at a higher temperature in the coater exhaust and transfer it to the coater return air at a medium temperature, and the second heat pipe heat exchanger 3 is used to recover the heat at a medium temperature in the coater exhaust and transfer it to the coater return air at a lower temperature, while condensing part of the NMP in the coater exhaust. Secondly, a large temperature difference heat pump technology is used to realize the combined supply of cold and heat, that is, the heat pump evaporator 41 recovers the heat at a lower temperature in the coater exhaust and condenses most of the remaining NMP in the coater exhaust. The heat recovered by the heat pump evaporator 41 is pumped to the condenser 42 after the compressor 43 improves the heat energy grade, and the condenser 42 transfers the heat recovered by the evaporator 41 to the coater return air. Through the above measures, the condensation of the coater exhaust and the heating of the return air are achieved at the same time.

[0017] The outlet of the evaporator 41 is provided with a return air duct 5 and a circulation air duct 6 in parallel. Under normal circumstances, the volume ratio of the NMP waste gas entering the return air duct 5 and the circulation air duct 6 is usually maintained at 95:5. After the NMP waste gas entering the circulation air duct 6 passes through the rotor adsorption unit, a part of it enters the exhaust duct 1, and the other part enters the external exhaust duct 7.

[0018] Specifically, the wheel adsorption unit includes an adsorption wheel, which is arranged in a wheel shell divided into an adsorption zone, a regeneration zone and a cooling zone. The circulating air duct 6 is arranged at the inlet end of the adsorption zone, and a recovery pipe 8 and an external exhaust pipe 7 are arranged 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 and is connected to the exhaust pipe 1.

[0019] The working process of the rotary adsorption unit is as follows: the adsorption wheel rotates continuously, and turns to the adsorption zone, regeneration zone and cooling zone in turn, and repeats in this order; when the NMP waste gas in the circulating air duct 6 enters the adsorption zone, the effective components of the gas are adsorbed by the adsorption wheel and can be discharged as purified tail gas; the adsorption wheel then turns to the regeneration zone, and due to the introduction of hot air into the regeneration zone, the adsorbed NMP will be desorbed and sent to the exhaust pipe 1 through the recovery pipe 8 for heat exchange condensation recovery; then the adsorption wheel turns to the cooling zone, and heat exchanges with the low-temperature purified tail gas entering the recovery pipe 8. After the temperature of the adsorption wheel drops to the adsorption temperature, it rotates again to enter the adsorption zone for NMP adsorption. After the heat exchange, the temperature of the low-temperature purified tail gas in the above-mentioned recovery pipe 8 increases to a certain extent, and enters the recovery heater 9 for use as regeneration air, achieving the purpose of energy saving.

[0020] The volume ratio of the NMP waste gas entering the recovery pipe 8 and the external exhaust pipe 7 is usually 4:1.

[0021] Preferably, an exhaust fan 10 is provided on the exhaust duct 1 at the inlet side of the first heat pipe heat exchanger 2, a return fan 11 and an inlet air heater 12 are provided on the return duct 5 at the outlet side of the condenser 42, a circulation fan 13 and a regulating valve 14 are provided on the circulation duct 6 at the inlet side of the adsorption zone, an external exhaust fan 15 is provided at the outlet of the adsorption zone, and a regeneration fan 16 is provided on the recovery pipe 8 at the outlet side of the regeneration zone. The above-mentioned recovery heater 9 and inlet air heater 12 are both steam / electric heaters, and the temperature at the outlet of the inlet air heater 12 is 130-150°C.

[0022] It should be noted that, in the description of the present invention, terms indicating orientation or positional relationships, such as "front", "rear", "left", "right", "vertical", "horizontal", "inside", "outside", etc., are based on the orientation or positional relationships shown in the drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

Claims

1. A combined cooling and heating system for NMP recovery in coating and drying in power battery factories, characterized by: The invention comprises an exhaust duct connected to the coating machine, wherein the NMP waste gas in the exhaust duct sequentially enters the first heat pipe heat exchanger, the second heat pipe heat exchanger and the evaporator of the heat pump unit as a heat source gas; the outlet of the evaporator is provided with a return air duct and a circulation air duct in parallel, and the NMP waste gas in the return air duct sequentially enters the second heat pipe heat exchanger, the first heat pipe heat exchanger and the condenser of the heat pump unit as a cold source gas, and the return air duct at the outlet of the condenser is connected to the air inlet duct of the coating machine; after the NMP waste gas in the circulation air duct passes through the rotary adsorption unit, a part of it enters the exhaust duct, and the other part enters the external exhaust pipe; the second heat pipe heat exchanger and the evaporator are both provided with an NMP recovery pipe.

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

3. The NMP recovery and cooling and heating system for coating and drying in a power battery factory according to claim 1 is characterized in that: The rotary adsorption unit includes an adsorption rotary wheel, which is arranged in a rotary shell divided into an adsorption zone, a regeneration zone and a cooling zone. The circulating air duct is arranged at the inlet end of the adsorption zone, and a recovery pipe and the external exhaust pipe are arranged 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 and is connected to the exhaust pipe.

4. The NMP recovery and cooling and heating system for coating and drying in a power battery factory according to claim 3 is characterized in that: An exhaust fan is arranged on the exhaust duct on the inlet side of the first heat pipe heat exchanger, a return fan and an inlet air heater are arranged on the return air duct on the outlet side of the condenser, a circulation fan and a regulating valve are arranged on the circulation air duct on the inlet side of the adsorption zone, an external exhaust fan is arranged at the outlet of the adsorption zone, and a regeneration fan is arranged on the recovery pipe on the outlet side of the regeneration zone.

5. The NMP recovery and cooling and heating system for coating and drying in a power battery factory according to claim 4 is characterized in that: The recovery heater and the air inlet heater are both steam / electric heaters.

6. The NMP recovery and cooling and heating system for coating and drying in a power battery factory according to claim 4 is characterized in that: The temperature of the NMP waste gas in the exhaust duct at the outlet of the exhaust fan is 125-135°C, the temperature at the outlet of the first heat pipe heat exchanger is 75-85°C, the temperature at the outlet of the second heat pipe heat exchanger is 35-45°C, and the temperature at the outlet of the evaporator is 12-17°C; the temperature of the NMP waste gas in the return air duct at the outlet of the second heat pipe heat exchanger is 45-55°C, the temperature at the outlet of the first heat pipe heat exchanger is 85-95°C, the temperature at the outlet of the condenser is 115-125°C, and the temperature at the outlet of the air inlet heater is 130-150°C.

7. The NMP recovery and cooling and heating system for coating and drying in a power battery factory according to claim 4 is characterized in that: The volume ratio of NMP waste gas entering the return air duct and the circulation air duct from the evaporator outlet is 95:5, and the volume ratio of NMP waste gas entering the recovery pipe and the external exhaust pipe from the external exhaust fan outlet is 4:1.

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