Energy-saving device of NMP recovery system

Abstract

The utility model discloses an energy-saving device of an NMP (N-Methyl Pyrrolidone) recovery system, and belongs to the technical field of NMP recovery systems. The device comprises a heat exchange module, the heat exchange module is connected with a coating machine and used for conducting heat exchange on high-temperature NMP tail gas exhausted by the coating machine, and the heat exchange module is connected with an NMP spraying absorption tower. The NMP spraying absorption tower is used for carrying out absorption treatment on the cooled NMP tail gas and inputting the tail gas subjected to absorption treatment into the coating machine for heating after heat exchange through the heat exchange module; the combined cooling and heating main machine is used for circularly heating the input end of the coating machine and circularly cooling the NMP tail gas between the heat exchange module and the NMP spraying absorption tower at the same time; according to the utility model, the operation energy consumption of equipment is reduced through the CO2 cold and heat combined supply unit.

Description

Technical Field

[0001] This utility model relates to an energy-saving device for an NMP recycling system, belonging to the technical field of NMP recycling systems. Background Technology

[0002] NMP (N-methylpyrrolidone) recovery equipment is a common device in lithium battery factories used to recover NMP generated during the coating process of lithium battery production. The equipment cools the hot air discharged from the coating oven through a heat exchanger, then recovers the NMP in the hot air by spraying it through a spray tower. The hot air then exchanges heat with the hot air discharged from the coating oven in a heat exchanger to raise its temperature. Finally, the hot air is heated to the required temperature of the coating oven by electric heating or steam heating before entering the coating oven.

[0003] In existing processes, the hot air discharged during coating is generally around 100℃. After passing through a heat exchanger, its temperature drops to around 70-80℃, and then it enters a spray tower. After spraying, the hot air temperature drops to 30-40℃, and after passing through another heat exchanger, it is heated to 70-80℃ again. Finally, it is heated to around 100℃ by a heating device and sent to the coating oven. Therefore, during equipment operation, the hot air needs to be continuously cooled and heated. The hot air discharged during coating is still above 70℃ after passing through the heat exchanger. During the spraying process, the temperature drops to 30-40℃, and a large amount of heat in this process needs to be dissipated through a cooling tower. In this process, a large amount of energy is released into the air, and a large amount of cooling water is evaporated. Although some heat energy is recovered through the heat exchanger during the cooling process, a large amount of heat is still lost.

[0004] Although existing NMP recovery systems recover some heat by exchanging heat between the inlet and outlet air through heat exchangers, a large portion of the heat is still lost after cooling through cooling towers. This process not only wastes a lot of thermal energy but also places high demands on the cooling tower load configuration. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide an energy-saving device for an NMP recovery system. The device generates heat and cold energy through a combined cooling and heating unit. The cold energy further cools the hot air after it has been cooled by the heat exchanger, thereby reducing the energy consumption of the equipment and the loss of moisture, as well as significantly reducing the amount of heat energy released into the air.

[0006] To achieve the above objectives / to solve the above technical problems, this utility model adopts the following technical solution:

[0007] An energy-saving device for an NMP recovery system includes:

[0008] The heat exchange module is connected to the coating machine and is used to exchange heat with the high-temperature NMP exhaust gas discharged from the coating machine. The heat exchange module is connected to an NMP spray absorption tower, which is used to absorb and treat the cooled NMP exhaust gas and to input the absorbed exhaust gas into the coating machine for heating after heat exchange through the heat exchange module.

[0009] A combined cooling and heating unit is used to circulate and heat the input end of the coating machine and simultaneously circulate and cool the NMP exhaust gas between the heat exchange module and the NMP spray absorption tower.

[0010] The above technical solution, through the CO2 combined cooling and heating unit, can reduce the cooling tower load and configuration. In this process, it reduces the operating energy consumption of the equipment and reduces the loss of moisture, and also greatly reduces the heat energy dissipated into the air. The temperature reduction is conducive to the dissolution of NMP and can increase the water solubility of NMP. The heat energy is used to heat the hot air after it has been heated by the heat exchanger, reducing the system's energy consumption for heating the hot air.

[0011] Optionally, the NMP spray absorption tower includes a primary circulation treatment device and a secondary circulation treatment device. The primary circulation treatment device is connected to an NMP waste liquid collection tank, and the secondary circulation treatment device further absorbs NMP tail gas and cools it down.

[0012] The above technical solution, through a two-stage circulation, can fully dissolve NMP exhaust gas in water on the one hand, and reuse the treated exhaust gas on the other hand, thus saving energy.

[0013] Optionally, the primary circulation treatment equipment includes a closed cooling tower, a primary circulation spray head, and a primary circulation pump. The primary circulation pump circulates the solution in the NMP spray absorption tower through the closed cooling tower to the primary circulation spray head for circulating collection of NMP waste liquid to the NMP waste liquid collection tank.

[0014] The above technical solution increases the water solubility of NMP by adding a cooling tower for circulating cooling.

[0015] Optionally, the secondary circulation treatment equipment includes a secondary circulation spray head and a secondary circulation pump. The secondary circulation pump circulates the solution in the NMP spray absorption tower through the secondary circulation spray head, and discharges part of the NMP exhaust gas from the top, while the other part is fed into the coating machine for heating after heat exchange through the heat exchange module.

[0016] The above technical solution adopts a two-stage circulating spray system, in which the exhaust gas further absorbs NMP and cools down through the two-stage spray circulation, resulting in more complete dissolution.

[0017] Optionally, the secondary circulation treatment equipment is equipped with a pure water tank for water replenishment.

[0018] The above technical solution involves replenishing water from a pure water tank for spraying after the liquid level drops to a certain level, thus ensuring the water solubility of NMP for secondary circulation spraying.

[0019] Optionally, a circulating fan is provided between the heat exchange module and the coating machine.

[0020] The above technical solution, which uses a circulating fan, can improve the efficiency of NMP exhaust gas transmission.

[0021] Optionally, the heating end of the combined cooling and heating main unit circulates and heats the exhaust gas after absorption treatment output from the heat exchange module through gas-water heat exchanger II and water pump II.

[0022] In the above technical solution, both the chilled water and hot water of the gas-water heat exchanger are supplied by a CO2 combined cooling and heating unit. The chilled water further cools the exhaust gas that has been cooled by the gas-gas heat exchanger, and the hot water further heats the exhaust gas that has been heated by the gas-gas heat exchanger. Cooling the exhaust gas reduces the temperature rise of the spray water, which is beneficial for NMP absorption and reduces the load and configuration requirements of the cooling tower.

[0023] Optionally, the cooling end of the combined cooling and heating unit circulates through a gas-water heat exchanger and a water pump to cool the NMP exhaust gas output from the heat exchange module.

[0024] The above technical solution reduces the load and configuration of electric heating by circulating and cooling through a gas-water heat exchanger and a water pump, thereby saving energy.

[0025] Optionally, the combined cooling and heating unit uses CO2 as the cooling medium to simultaneously produce cold water and hot water. Gaseous CO2 is compressed into liquid by an internal compressor and releases heat. The liquid CO2 in the condenser enters the evaporator through an electronic expansion valve to cool the cold water on the evaporator side.

[0026] The above technical solution uses a CO2 combined cooling and heating unit with a high energy efficiency ratio, which reduces the operating energy consumption of system equipment and the need for electric heating configuration.

[0027] Optionally, the heat exchange module uses a gas-to-gas heat exchanger.

[0028] The above technical solution, which uses a gas-to-gas heat exchanger, can reduce the operating energy consumption of the equipment.

[0029] Compared with the prior art, the beneficial effects achieved by this utility model are as follows:

[0030] This invention utilizes a combined cooling and heating unit to generate both heat and cold energy. The cold energy further cools the hot air after it has been cooled by the heat exchanger. This reduces the load and configuration of the cooling tower, thereby reducing the energy consumption of the equipment, minimizing moisture loss, and significantly reducing heat loss into the air. Furthermore, the lower temperature promotes the dissolution of NMP, increasing its water solubility. The heat energy further warms the hot air after it has been heated by the heat exchanger, reducing the system's energy consumption for heating the hot air and thus lowering the overall energy consumption of the equipment. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of an energy-saving device for an NMP recovery system according to the present invention;

[0032] In the diagram: 1-Coating machine, 2-Gas-to-gas heat exchanger, 3-NMP spray absorption tower, 4-Primary circulating pump, 5-Closed cooling tower, 6-Secondary circulating pump, 7-NMP waste liquid collection tank, 8-Pure water tank, 9-Gas-to-water heat exchanger I, 10-Combined cooling and heating main unit, 11-Water pump II, 12-Water pump I, 13-Circulating fan, 14-Gas-to-water heat exchanger II, 15-Primary circulating spray head, 16-Secondary circulating spray head. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0034] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more. Example

[0035] like Figure 1 As shown, an energy-saving device for an NMP recovery system is disclosed, comprising:

[0036] A heat exchange module is connected to the coating machine 1 and is used to exchange heat with the high-temperature NMP exhaust gas discharged from the coating machine 1. The heat exchange module is connected to an NMP spray absorption tower 3, which is used to absorb and treat the cooled NMP exhaust gas and to input the treated exhaust gas into the coating machine 1 for heating after heat exchange through the heat exchange module. Further, the heat exchange module adopts a gas-to-gas heat exchanger 2. The air inlet end of the gas-to-gas heat exchanger 2 is connected to a circulating fan 13, and the output end enters the first-stage circulation of the NMP spray absorption tower 3 after heat exchange through a gas-to-water heat exchanger 9 and a water pump 12.

[0037] The combined cooling and heating unit 10 is used to circulate and heat the input end of the coating machine 1 and simultaneously circulate and cool the NMP exhaust gas between the heat exchange module and the NMP spray absorption tower 3.

[0038] The above technical solution uses a CO2 combined cooling and heating unit, which can reduce the cooling tower's cooling load and configuration. In this process, it reduces the equipment's operating energy consumption and moisture loss, and also greatly reduces the heat energy dissipated into the air. The temperature reduction is conducive to the dissolution of NMP and can increase the water solubility of NMP. The heat energy is used to heat the hot air after it has been heated by the heat exchanger, reducing the system's energy consumption for heating the hot air.

[0039] In this embodiment, the NMP spray absorption tower 3 includes a primary circulation treatment device and a secondary circulation treatment device. The primary circulation treatment device is connected to an NMP waste liquid collection tank 7, and the secondary circulation treatment device further absorbs NMP tail gas and cools it down.

[0040] The above technical solution, through a two-stage circulation, can fully dissolve NMP exhaust gas in water on the one hand, and reuse the treated exhaust gas on the other hand, thus saving energy.

[0041] In this embodiment, the primary circulation treatment equipment includes a closed cooling tower 5, a primary circulation spray head 15, and a primary circulation pump 4. The primary circulation pump 4 circulates the solution in the NMP spray absorption tower 3 through the closed cooling tower 5 to the primary circulation spray head 15 for circulating collection of NMP waste liquid to the NMP waste liquid collection tank 7.

[0042] The above technical solution increases the water solubility of NMP by adding a cooling tower for circulating cooling.

[0043] In this embodiment, the secondary circulation treatment equipment includes a secondary circulation spray head 16 and a secondary circulation pump 6. The secondary circulation pump 6 circulates the solution in the NMP spray absorption tower 3 through the secondary circulation spray head 16, and discharges part of the NMP exhaust gas from the top, while the other part is fed into the coating machine for heating after heat exchange through the heat exchange module.

[0044] The above technical solution adopts a two-stage circulating spray system, in which the exhaust gas further absorbs NMP and cools down through the two-stage spray circulation, resulting in more complete dissolution.

[0045] In this embodiment, the secondary circulation treatment equipment is equipped with a pure water tank 8 for water replenishment.

[0046] The above technical solution involves replenishing water from the pure water tank 8 for spraying after the liquid level drops to a certain level, thus ensuring the water solubility of NMP for secondary circulation spraying.

[0047] In this embodiment, a circulating fan 13 is provided between the heat exchange module and the coating machine 1.

[0048] The above technical solution, by using a circulating fan 13, can improve the efficiency of NMP exhaust gas transmission.

[0049] In this embodiment, the heating end of the combined cooling and heating unit 10 circulates and heats the exhaust gas after absorption treatment output by the heat exchange module through the gas-water heat exchanger 2 14 and the water pump 2 11.

[0050] In the above technical solution, both the chilled water and hot water of the gas-water heat exchanger 214 are supplied by the CO2 combined cooling and heating unit. The chilled water further cools the exhaust gas that has been cooled by the gas-gas heat exchanger 214, and the hot water further heats the exhaust gas that has been heated by the gas-gas heat exchanger. Cooling the exhaust gas reduces the temperature rise of the spray water, which is beneficial to the absorption of NMP and reduces the load and configuration requirements of the cooling tower.

[0051] In this embodiment, during the specific implementation process, the cooling end of the combined cooling and heating unit 10 cools the NMP exhaust gas output from the heat exchange module through the gas-water heat exchanger 9 and the water pump 12.

[0052] The above technical solution reduces the load and configuration of electric heating by circulating and cooling through the gas-water heat exchanger-9 and water pump-12, thereby saving energy.

[0053] In this embodiment, the combined cooling and heating unit 10 uses CO2 as the cooling medium to simultaneously generate cold water and hot water. The gaseous CO2 is compressed into liquid by the internal compressor and releases heat. The liquid CO2 in the condenser enters the evaporator through the electronic expansion valve to cool the cold water on the evaporator side.

[0054] The above technical solution uses a CO2 combined cooling and heating unit with a high energy efficiency ratio, which reduces the operating energy consumption of system equipment and the need for electric heating configuration.

[0055] In this embodiment, the heat exchange module uses a gas-to-gas heat exchanger.

[0056] The above technical solution, which uses a gas-to-gas heat exchanger, can reduce the operating energy consumption of the equipment. Example

[0057] Based on Example 1, the CO2-based combined cooling and heating unit 10 is replaced with a conventional combined cooling and heating unit, and the gas-water heat exchanger can be replaced with a gas-gas heat exchanger.

[0058] The specific working principle is as follows:

[0059] This device adds a CO2-based combined cooling and heating unit 10 to a traditional NMP recovery system, further saving energy consumption. High-temperature exhaust gas containing a certain concentration of NMP is discharged from the coating machine 1. This gas is cooled by the gas-to-gas heat exchanger 2 via the circulating fan 13 of the NMP recovery system, reducing its temperature from approximately 100°C to approximately 70°C. Then, chilled water supplied by the combined cooling and heating unit 10 further cools the exhaust gas through the gas-to-gas heat exchanger 2, passing it through the gas-to-water heat exchanger 9 to approximately 50°C before it enters the NMP spray absorption tower 3. Inside the NMP spray absorption tower 3, the gas first undergoes a primary circulating spray process, continuously circulated by a primary circulating pump 4. The system consists of a closed-loop cooling tower 5 for solution cooling and a primary circulating spray head 15. The exhaust gas, after being partially cooled by the spray water from the primary circulating spray head 15, enters the secondary circulating spray in the upper part of the spray absorption tower 3. The spray water is continuously circulated by the primary circulating pump 4 until a certain concentration is reached, at which point it is sent to the NMP waste collection tank 7. The exhaust gas then enters the secondary circulating spray, which consists of a secondary circulating pump 6 and secondary spray heads 16. The internal solution is continuously circulated and sprayed by the secondary circulating pump 6. When the liquid level drops to a certain level, pure water tank 8 replenishes the spray. The exhaust gas further absorbs NMP and cools down through the secondary spray circulation, reducing the temperature to 35°C. The exhaust gas is discharged from the top of the spray absorption tower 3, with a small portion released into the air. The majority of the treated exhaust gas is heated to approximately 65°C by the heat recovery section of the gas-to-gas heat exchanger 2, where it recovers heat from the exhaust gas discharged from the coating machine 1. The temperature is further increased by the air-water heat exchanger 14 to about 95°C. Finally, the temperature is raised to the required temperature by the air intake heating at the equipment end of the coating machine 1 before entering the coating machine 1.

[0060] In this device, the exhaust gas is discharged from the coating machine 1, transported by the circulating fan 13, and first passes through the gas-to-gas heat exchanger 2 to exchange heat with the treated exhaust gas and cool it down. At the same time, some of the heat is recovered for reuse. Then, it passes through the gas-water heat exchanger 9 for further condensation and cooling before entering the NMP spray absorption tower 3. In the NMP spray absorption tower 3, it passes through two stages of spraying. The spray water fully absorbs the NMP medium in the exhaust gas and further cools the exhaust gas. The spray water is then cooled by the closed cooling tower 5 to maintain temperature balance, while the exhaust gas is discharged from the top of the NMP spray absorption tower 3. A small amount of gas, about 5%, is discharged, and the rest is heated by the gas-to-gas heat exchanger 2 to recover the heat from the exhaust gas cooling. Then, it passes through the gas-water heat exchanger 14 for further heating to about 95°C before entering the coating machine equipment.

[0061] The CO2 combined cooling and heating unit 10 is a device that can simultaneously produce chilled and hot water. Due to CO2's good chemical stability, excellent flow and heat transfer characteristics, and large latent heat, CO2 is used as the cooling medium. The CO2 medium continuously circulates within the CO2 combined cooling and heating unit 10. Gaseous CO2 is compressed into liquid form by an internal compressor, releasing heat, which heats the hot water on the condenser side to the required temperature. The liquid CO2 in the condenser enters the evaporator through an electronic expansion valve. Due to the pressure drop in the container, the CO2 vaporizes, absorbing heat and cooling the chilled water on the evaporator side to the required temperature.

[0062] In this implementation scheme, the CO2 combined cooling and heating unit has a cooling COP ≥ 2.5 and a heating COP ≥ 3.5. This means that an input of 1 kW of electrical power can generate 3.5 kW of heat, which is 3.5 times the heat generated by electric heating with the same input power. This heat is utilized by the system equipment, resulting in significant energy savings. Simultaneously, it generates 2.5 kW of cooling capacity for cooling the system medium, reducing the energy consumption and configuration requirements of cooling equipment in the system. In this embodiment, the cold water and hot water of the gas-water heat exchangers 9 and 14 are both supplied by the CO2 combined cooling and heating unit 10. The cold water is circulated by water pump 212, and the hot water is circulated by water pump 111. The cold water further cools the exhaust gas that has been cooled by the gas-to-gas heat exchanger 2, and the hot water further heats the exhaust gas that has been heated by the gas-to-gas heat exchanger 2. Cooling the exhaust gas reduces the temperature rise of the spray water, which is beneficial for NMP absorption and reduces the load and configuration requirements of the cooling tower. This process also reduces equipment operating energy consumption and cooling water makeup. Heating the exhaust gas reduces the load and configuration of electric heating, saving energy.

[0063] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0064] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. An energy-saving device of an NMP recovery system, characterized in that it comprises: a heat exchange module connected with a coating machine for heat exchange of high-temperature NMP tail gas discharged by the coating machine, the heat exchange module being connected with an NMP spray absorption tower for absorption treatment of the cooled NMP tail gas and input of the absorption-treated tail gas into the coating machine after heat exchange by the heat exchange module for temperature rise; and a combined cooling and heating host for cyclic heating of an input end of the coating machine and cyclic cooling of NMP tail gas between the heat exchange module and the NMP spray absorption tower. The NMP spray absorption tower comprises a primary cyclic treatment device and a secondary cyclic treatment device, the primary cyclic treatment device being connected with an NMP waste liquid collection tank, and the secondary cyclic treatment device further absorbing NMP tail gas and cooling. The primary cyclic treatment device comprises a closed cooling tower, a primary cyclic spray head and a primary cyclic pump, the primary cyclic pump cyclically delivering the solution in the NMP spray absorption tower to the primary cyclic spray head through the closed cooling tower to collect NMP waste liquid into the NMP waste liquid collection tank.

2. The energy saving device for NMP recovery system according to claim 1, wherein The secondary cyclic treatment device comprises a secondary cyclic spray head and a secondary cyclic pump, the secondary cyclic pump cyclically spraying the solution in the NMP spray absorption tower through the secondary cyclic spray head, discharging a part of the NMP tail gas from the top and inputting the other part of the NMP tail gas into the coating machine after heat exchange by the heat exchange module for temperature rise.

3. The energy saving device for NMP recovery system according to claim 2, wherein, The secondary cyclic treatment device is provided with a pure water tank for water replenishment.

4. The energy saving device for NMP recovery system according to claim 2, wherein A circulating fan is arranged between the heat exchange module and the coating machine.

5. The energy saving device for NMP recovery system according to claim 4, wherein The absorption-treated tail gas output by the heat exchange module is cyclically heated by a heating end of the combined cooling and heating host through a gas-water heat exchanger II and a water pump II.

6. The energy saving device for NMP recovery system according to claim 1, wherein, The NMP tail gas output by the heat exchange module is cooled by a cooling end of the combined cooling and heating host through a gas-water heat exchanger I and a water pump I.

7. The energy saving device for NMP recovery system according to claim 1, wherein, The combined cooling and heating host can simultaneously generate cold water and hot water by taking CO2 as a refrigerant medium, gaseous CO2 is compressed into liquid by an internal compressor to release heat, liquid CO2 in a condenser is introduced into an evaporator by an electronic expansion valve to cool the cold water on the side of the evaporator.

8. The energy saving device for NMP recovery system according to claim 1, wherein, The heat exchange module adopts a gas-gas heat exchanger.

9. The energy saving device for NMP recovery system according to claim 1, wherein, ​ 10. The energy saving device for NMP recovery system according to claim 1, wherein, ​

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