An NMP recycling device

Abstract

NMP recycling device for recycling and regenerating high-temperature NMP exhaust gas from a coating plant, characterized in that it comprises an NMP exhaust gas liquefaction recovery system (1), a storage and transport system (2) and an NMP waste liquid regeneration system (3) which are connected sequentially via a line; The NMP exhaust gas liquefaction system (1) comprises a heat recovery unit (11) and an absorption unit (12) to at least liquefy the high-temperature NMP exhaust gas and / or treat it by absorption by an absorbent to obtain an NMP waste liquid; The storage and transport system (2) serves at least to receive the NMP waste liquid obtained through the NMP exhaust gas liquefaction system (1) and to transfer it to the NMP waste liquid regeneration system (3); The system for regenerating NMP waste liquid (3) comprises a dewatering unit (31) and a refining unit (32), at least for dewatering, purifying and regenerating the NMP waste liquid transferred through the storage and transport system (2).

Description

Technical area

[0001] The utility model belongs to the technical field of lithium-ion battery manufacturing and relates in particular to an NMP recycling device. Background technology

[0002] NMP (N-methylpyrrolidone) is a highly polar, non-protic solvent with excellent performance and a number of advantages, such as chemical stability, high temperature resistance, high solubility, low volatility, high safety, and low toxicity. Therefore, it is frequently used in lithium-ion battery production as a solvent for the PVDF binder. During the coating of lithium-ion batteries, NMP is emitted from the coating plant in the form of high-temperature exhaust gases. If the NMP in the exhaust gases is not recycled and is released directly into the environment, this leads to both environmental pollution and a significant waste of resources. Therefore, there is a great need for the recovery and utilization of NMP from the exhaust gas.

[0003] Existing NMP solvent recycling methods utilize absorption, condensation, and rotor adsorption to liquefy the NMP in the exhaust gas to produce NMP waste liquid. The waste NMP liquid is then packaged and transferred to a special solvent processing plant for purification and regeneration to produce NMP products. The finished NMP products are then packaged and transported to the lithium-ion battery factory. The high operating costs and long cycle time of this method require improvements to the existing NMP recycling method. Content of the utility model

[0004] To solve the above problems, the utility model provides an NMP recycling device that realizes in-situ recycling of NMP solvents by combining an NMP off-gas liquefaction and recovery system, a storage and discharge system, and an NMP waste liquid regeneration system, thereby solving the problems of high operating cost and long cycle time in existing NMP recycling. The technical solutions used in this utility model are:

[0005] NMP recycling device for recycling and regenerating high-temperature NMP exhaust gas from a coating plant, comprising an NMP exhaust gas liquefaction and recovery system, a storage and delivery system and an NMP waste liquid regeneration system, which are connected sequentially by a pipeline;

[0006] The NMP exhaust gas liquefaction system comprises a heat recovery unit and an absorption unit for at least liquefying the high-temperature NMP exhaust gas and / or treating it by absorption by an absorbent to obtain an NMP waste liquid;

[0007] The storage and conveying system for receiving at least the NMP waste liquid obtained from the NMP off-gas liquefaction system and for transferring it to the NMP waste liquid regeneration system;

[0008] The described NMP waste liquid regeneration system comprises a dewatering unit and a refining unit for at least the gas-liquid separation, purification and regeneration of the NMP waste liquid transferred through the storage and transportation system.

[0009] Preferably, the heat recovery unit comprises a heat recovery unit and a multi-stage surface cooler, wherein the hot medium inlet of the heat recovery unit is connected to the high-temperature NMP exhaust gas outlet of the coating system, the hot medium outlet of the heat recovery unit is connected in one direction to the gas inlet of the multi-stage surface cooler and in the other direction to the gas inlet of the absorption unit; the cold medium inlet of the heat recovery unit is connected to the gas outlet of the multi-stage surface cooler, the cold medium outlet of the heat recovery unit is connected to the gas outlet of the multi-stage surface cooler, the cold medium outlet of the heat recovery unit is connected to the gas inlet of the coating system, and the liquid outlet of the multi-stage surface cooler is connected to the liquid inlet of the storage and transport system.

[0010] Preferably, the heat recovery unit further comprises an induced draft fan and a return fan, wherein the induced draft fan is connected to the hot media inlet of the heat recovery unit to direct high-temperature NMP exhaust gases from the coating system into the heat recovery section, and the return fan is connected to the cold medium outlet of the multi-stage surface cooler and serves to transport the heated cold medium from the multi-stage surface cooler to the coating device.

[0011] Preferably, the heat recovery unit is a gas-to-gas heat exchanger; the multi-stage surface cooler is a gas-to-liquid heat exchanger and comprises a cooling water condensation section and a cold water condensation section.

[0012] Preferably, the absorption unit comprises an absorption tower and an absorption reflux pump, wherein the gas inlet of the absorption tower is connected to a heat recoverer, the liquid outlet is fully connected to the liquid inlet of the storage and discharge system and the other path is connected via the absorption reflux pump to the reflux port of the absorption tower, and the absorber inlet of the absorption tower is connected to a dewatering unit.

[0013] Preferably, the absorption tower is provided with a corrugated packing of stainless steel wire mesh to ensure adequate contact of the NMP exhaust gases with the absorbent.

[0014] Preferably, the storage and transportation system comprises an NMP recycling storage tank, wherein the liquid inlet of the NMP recycling storage tank is connected to an absorption unit and a heat recovery unit, and the liquid outlet is connected to a dehydration unit for storing the NMP waste liquid and transporting it to the dehydration unit for gas-liquid separation treatment.

[0015] Preferably, the storage and transportation system further comprises a wastewater storage tank and an NMP finished product storage tank, wherein the wastewater storage tank is connected to a dehydration unit and an absorption unit, respectively, for receiving the light fraction separated by the dehydration unit and transferring it to the absorption unit for reuse as an absorbent, and wherein the inlet of the NMP finished product storage tank is connected to an outlet of the light fraction of the refining unit.

[0016] In particular, the liquid inlet of the wastewater storage tank is connected to the light component outlet of the dewatering unit, and the liquid outlet is connected to the absorption unit to receive the light component separated by the dewatering unit and transfer it to the absorption unit for reuse as an absorbent.

[0017] Preferably, the storage and conveying system further comprises an automatic control unit, wherein the storage and conveying system is equipped with a magnetic flap level sensor for controlling the height of the liquid level and an ultrasonic level sensor for controlling the excess level in the storage tank of the storage and conveying system, and the automatic control unit is electrically connected to both the magnetic flap level sensor and the ultrasonic level sensor.

[0018] Preferably, the dewatering unit comprises a dewatering tower, an upper condenser of the dewatering tower, a gas-liquid separator of the dewatering tower, a distillate tank of the dewatering tower, and an evaporator of the dewatering tower, wherein the liquid inlet of the dewatering tower is connected to the storage and conveying system, wherein the outlet forms a recirculation loop with the evaporator of the dewatering tower and the outlet is connected to a refining unit, and wherein the outlet of the light fraction of the dewatering tower is connected to the upper condenser of the dewatering tower and the gas-liquid separator of the dewatering tower. The outlet of the light component of the dewatering tower is connected to the upper condenser of the dewatering tower, the gas-liquid separator of the dewatering tower, and the distillate tank of the dewatering tower.and the outlet of the distillate tank of the dehydration tower is connected to the dehydration tower, and the outlet of the distillate tank of the dehydration tower reboiler, and the outlet is connected to the refining unit.

[0019] Preferably, the refining unit comprises a refining tower, a refining tower top cooler, a refining tower gas-liquid separator, a refining tower distillate tank, and a refining tower reboiler, wherein the refining tower inlet is connected to the heavy fraction outlet of the dewatering tower, and the outlet forms a recirculation loop with the refining tower reboiler, the light fraction outlet of the refining tower is in turn connected to the refining tower top cooler, the refining tower gas-liquid separator, and the refining tower distillate tank, and the refining tower distillate tank outlet is connected to the refining tower by one path and to the storage and conveying system by another path.The outlet of the distillate tank of the refinery tower is connected to the refinery tower by one path, and the other path is connected to the storage and conveying system.

[0020] Compared to existing technology, this utility model combines an NMP exhaust gas liquefaction recovery system, a storage and delivery system, and an NMP waste liquid regeneration system. This system takes high-temperature NMP exhaust gas from the coating plant and directly converts it into a finished NMP product that fully meets the quality requirements of the coating process. This finished product can then be delivered directly for use in the coating process, thus enabling in-situ recycling of NMP solvents. This eliminates the waste liquid and finished product packaging, transportation, and other associated costs associated with the NMP recycling process, effectively solving the high operating costs and lengthy cycle problems of existing NMP recycling methods. Illustrations

[0021] Fig. shows a structural diagram of an NMP recycling device as provided in an embodiment of the utility model;

[0022] Fig. shows the schematic structure of an NMP recycling device as provided in an embodiment of the utility model.

[0023] In the figure: 1: NMP flue gas liquefaction system; 11: Heat recovery unit: 111; Heat recovery unit: 112: Multi-stage surface cooler;

[0024] 12: Absorption unit; 121: Absorption tower; 122: Absorption return pump; 2: Storage and conveying system; 21: NMP recycling storage tank; 22: Waste water tank; 23: NMP finished product storage tank; 3: NMP waste liquid regeneration system; 31: Dewatering unit; 311: Dewatering tower; 312: Dewatering tower top cooler; 313: Dewatering tower gas-liquid separator; 314: Dewatering tower distillate tank; 315: Dewatering tower evaporator; 32: Refining unit; 321: Refining tower; 322: Refining tower top cooler; 323: Refining tower gas-liquid separator; 324: Distillate vessel of the refining tower; 325: Evaporator of the refining tower. A practical way of doing something. To better understand the purpose, technical solutions, and advantages of the present utility model, the accompanying drawings and embodiments are summarized below to explain the present utility model in detail.It goes without saying that the specific embodiments described herein serve only to explain the utility model and not to restrict it.

[0025] The present embodiment provides an NMP recycling device for the recycling of high-temperature NMP exhaust gas from a coating plant for recovery and regeneration, as described in Fig. shown, comprising an NMP exhaust gas liquefaction and recovery system 1, a storage and conveying system 2, and an NMP waste liquid regeneration system 3, which are connected sequentially via pipes; The described NMP exhaust gas liquefaction system 1 comprises a heat recovery unit 11 and an absorption unit 12 for at least the high temperature. The NMP exhaust gas is liquefied and / or treated by absorption through an absorbent to obtain the NMP waste liquid;

[0026] The storage and conveying system 2 for receiving at least the NMP waste liquid obtained by the NMP exhaust gas liquefaction system 1 and for conveying it to the NMP waste liquid regeneration system 3; The described system for processing NMP waste liquid 3 comprises a dewatering unit 31 and a refining unit 32 for at least one of the storage and conveying systems 2. Transferred NMP waste solution is dewatered, purified and regenerated.

[0027] In this way, the high-temperature NMP exhaust gas emitted by the coating system passes through the heat recovery unit 11, and after the high-temperature NMP exhaust gas has been heat recovered, the temperature of the exhaust gas is significantly reduced, which on the one hand promotes the absorption of the NMP in the exhaust gas; on the other hand, the temperature of the exhaust gas enters the coating system after it has been heat exchanged by the heat recovery unit 11, which significantly increases the temperature of the exhaust gas and significantly reduces the energy consumption of the coating system.

[0028] Then, the NMP exhaust gas cooled after heat recovery enters the absorption unit 12, that is, it is in reverse contact with the absorber in the absorption tower 121; the absorption tower 121 is provided with a plurality of absorption units, which may be three or more, and as the NMP exhaust gas passes through the three-stage absorption unit step by step, the concentration of the NMP exhaust gas is gradually reduced, and the concentration of the NMP exhaust gas in the finally obtained exhaust gas can reach 10 mg / m 3 or less. The NMP exhaust gas concentration in the final exhaust gas can be below 10 mg / m 3 which is far below environmental protection requirements;

[0029] The NMP waste liquid obtained by the NMP off-gas liquefaction system 1 enters the storage and conveying system 2 for storage and is transported to the NMP waste liquid regeneration system, where the gas-liquid separation, purification and regeneration of the NMP waste liquid are completed by the dehydration unit 31 and the refining unit 32.

[0030] As in Fig. As shown, the heat recovery unit 11 comprises a heat recovery unit 111 and a multi-stage surface cooler 112, wherein the inlet of the heat recovery unit 111 is connected to the outlet of the high-temperature NMP exhaust gas of the coating system, the outlet of the hot medium of the heat recovery unit 111 is connected in one direction to the gas inlet of the multi-stage surface cooler 112 and in the other direction to the gas inlet of the absorption unit 12; the inlet of the cold medium of the heat recovery unit 111 is connected to the gas outlet of the multi-stage surface cooler 112, and the outlet of the cold medium is connected to the gas inlet of the coating system. The liquid outlet of the multi-stage surface cooler 112 is connected to the liquid inlet of the storage and transport system 2.

[0031] In particular embodiments, the heat recovery unit 11 further comprises an induced draft fan and a return fan, wherein the induced draft fan is connected to the hot medium inlet of the heat recovery unit 111 to direct high-temperature NMP exhaust gases from the coating system into the heat recovery unit 111, and the return fan is connected to the cold medium outlet of the multi-stage surface cooler 112 to convey heated cold medium from the multi-stage surface cooler 112 to the coating system.

[0032] In particular embodiments, the heat recovery unit 111 is a gas-gas heat exchanger, i.e., the medium of both the hot and cold pipelines is a gas, and the heat recovery unit 111 is preferably a gas-gas plate heat exchanger, which may be a gas-gas plate heat exchanger made of stainless steel 304;

[0033] The multi-stage surface cooler 112 is a gas-liquid heat exchanger for gradually cooling the exhaust gas after heat recovery, which may be a finned-tube gas-liquid heat exchanger; the multi-stage surface cooler 112 includes a cooling water condensation section and a chilled water condensation section, i.e., cooling water in the cooling water section and chilled water in the chilled water section are used as cooling media to achieve cooling of the exhaust gas and condensation, respectively. wherein the cooling medium of the cooling water condensing section is circulating cooling water having a temperature of not more than 32°C and the cooling medium of the cold water condensing section is chilled circulating water having a temperature of not more than 7°C.

[0034] In the specific implementation, the high-temperature NMP exhaust gas from the coating system enters the heat recovery unit 111 through the induced draft fan, which has a temperature of 90 to 120°C, and serves as the hot medium in the heat recovery unit 111, and the NMP exhaust gas after condensation by the multi-stage surface cooler 112 is used as the cold medium, and the high-temperature NMP exhaust gas of 90 to 120°C exchanges heat with the multi-stage surface cooler 112 in the heat recovery unit 111, and part of the cooled NMP exhaust gas enters the multi-stage surface cooler 112 after condensation.Condensed NMP exhaust gas heat exchange, high temperature NMP exhaust gas from 90 - 120 °C down to 45 - 55 °C, cooling NMP exhaust gas part of the condensation section in the multi-stage surface cooler 112 cold water and cold water for heat exchange, the other part of the blower into the absorption unit 12; through the multi-stage surface cooler 112 cold water condensation section of the cooled NMP exhaust gas temperature of 45 - 55 °C down to about 15 °C, the temperature is reduced to about 15 °C.

[0035] As in Fig. As shown, the absorption unit 12 comprises an absorption tower 121 and an absorption reflux pump 122, wherein the gas inlet of the absorption tower 121 is connected to a heat recovery unit 111, the liquid outlet is fully connected to the liquid inlet of the storage and conveying system 2, and the other path via the absorption reflux pump 122 is connected to the reflux opening of the absorption tower 121, and the absorber inlet of the absorption tower 121 is connected to a dehydration unit 31.

[0036] To enhance the absorption effect, a corrugated packing made of stainless steel wire mesh is provided in the absorption tower 121.

[0037] Specifically, the absorption tower 121 adopts a regular packing tower, and the built-in packing adopts a corrugated packing made of stainless steel wire mesh, which can be a corrugated packing made of stainless steel wire mesh CY700, and this packing is the current packing with the highest gas-liquid contact mass transfer and heat transfer efficiency. The absorption tower 121 is provided with a plurality of absorption units, which can be three or more, and the concentration of the NMP off-gas gradually decreases after being gradually absorbed by the three-stage absorption unit. As the NMP off-gas is gradually absorbed by the three-stage absorption unit, the concentration of the NMP off-gas is gradually reduced, and the concentration of the NMP off-gas in the final off-gas can be less than 10 mg / m 3 This achieves a level far below environmental protection requirements.

[0038] After cooling through the heat recovery unit 111, the NMP exhaust gas enters the absorption tower 121. The gas inlet of the absorption tower 121 is located at its base, and the absorbent inlet is at its top. The NMP exhaust gas enters the absorption tower 121 after moving upwards, and the absorbent enters the absorption tower 121 from the absorbent inlet after moving downwards. Both are in reverse contact, so that the NMP exhaust gas is absorbed by the absorbent. The aqueous NMP solution obtained after absorption is pumped from the base of the absorption tower 121 to the storage system. The absorber absorbs the NMP exhaust gas, and the aqueous NMP solution obtained after absorption is pumped from the base of the absorption tower 121 to the storage and transport system 2.

[0039] In order to realize the direct utilization of the NMP recycling process, the storage and transportation system 2 comprises an NMP recycling storage tank 21, wherein the liquid inlet of the NMP recycling storage tank 21 is connected to the absorption unit 12 and the heat recovery unit 11, and the liquid outlet is connected to the dehydration unit 31 to store the NMP waste liquids and transport them to the dehydration unit 31 for gas-liquid separation treatment.

[0040] To realize the recycling of waste products in the NMP recovery process, the storage and conveying system 2 further comprises a wastewater storage tank 22 and an NMP finished product storage tank 23, wherein the wastewater storage tank 22 is connected to the dewatering unit 31 or the absorption unit 12 to receive the light component separated by the dewatering unit 31 and transfer it to the absorption unit 12 for reuse as an absorbent, and the NMP finished product storage tank 23 The inlet of the NMP product storage tank 23 is connected to the outlet of the light fraction of the refining unit 32.

[0041] In this way, the wastewater storage tank 22 serves to store the light component, i.e., the wastewater containing a low concentration of NMP, after separation by the dewatering unit 31, and to supply the wastewater to the absorption tower 121 for reuse as an absorbent.

[0042] In certain embodiments, the NMP finished product storage tank 23 is stored with a nitrogen seal, and the nitrogen pressure (overpressure) of the gas phase air in the tank is maintained between 0.5 and 1.2 kPa.

[0043] To implement the automatic control of the device, the storage and conveying system 2 further comprises an automatic control unit, wherein the storage and conveying system 2 is equipped with a magnetic flap level sensor for controlling the height of the liquid level and an ultrasonic level sensor for controlling the overflow level in the storage tanks of the storage and conveying system 2, and the automatic control unit is electrically connected to both the magnetic flap level sensor and the ultrasonic level sensor.

[0044] In certain embodiments, the automatic control unit may be an automatic PLC control system.

[0045] The dewatering unit 31 comprises a dewatering tower 311, an upper dewatering tower cooler 312, a dewatering tower gas-liquid separator 313, a dewatering tower distillate tank 314, and a dewatering tower boiler 315, wherein the dewatering tower 311 has a liquid inlet connected to the storage and dispensing system 2, an outlet forming a recirculation loop with the dewatering tower boiler 315, and the outlet is connected to a refining unit 32, as shown in Fig.shown. The outlet of the light component of the dewatering tower 311 is in turn connected to a dewatering tower upper cooler 312, a dewatering tower gas-liquid separator 313 and a dewatering tower distillate tank 314, and the outlet of the dewatering tower distillate tank 314 is connected to the dewatering tower 311 all the way, and the other way goes through the storage and transport system 2 to the absorption unit 12.

[0046] The refining unit 32 comprises a refining tower 321, an upper condenser 322 of the refining tower, a gas-liquid separator 323 of the refining tower, a distillate tank 324 of the refining tower and a reboiler 325 of the refining tower, wherein the inlet of the refining tower 321 is connected to the outlet of the heavy fraction of the dehydration tower 311 and the outlet to the reboiler 325 of the refining tower to form a recirculation loop. The outlet of the light fraction of the refining tower 321 is in turn connected to the upper cooler 322, the gas-liquid separator 323 of the refining tower and the distillate tank 324 of the refining tower, and the outlet of the distillate tank 324 of the refining tower is connected in one direction to the refining tower 321 and in the other direction to the storage and transport system 2.

[0047] In certain embodiments, both the dewatering tower 311 and the refining tower 321 are regular packing towers, with the dewatering tower 311 using a corrugated packing of BX500 stainless steel wire mesh and the refining tower 321 using a corrugated packing of CY700 stainless steel wire mesh.

[0048] The NMP recovery liquid in the NMP recycling storage tank 21 is transported by a pump to the dewatering tower 311 in the dewatering unit 31 and enters the dewatering tower 311 from the center of the dewatering tower 311 under the operating conditions of a peak pressure (gauge pressure) of -0.086 MPa, a peak temperature of 51-55°C, and a reflux ratio of 4:1, so that the water in the recovered liquid is separated from the NMP, and the water is discharged from the top of the dewatering tower and pumped into the wastewater storage tank 22 for storage. NMP and recombinant impurities are discharged at the bottom of the dewatering tower and pumped into the refining tower 321.

[0049] NMP and recombinant impurities enter the refining tower 321 from the central position of the refining tower 321, and under the operating conditions of peak pressure (gauge pressure) -0.097 MPa, peak temperature 110 to 115°C, and reflux ratio 2:1, the NMP components are separated from the recombinant impurities, and the NMP components are discharged from the upper part of the refining tower 321 and transported by a pump to storage in the NMP finished product storage tank 23, and the recombinant impurities are discharged from the lower part of the refining tower 321 and pumped to storage in the NMP finished product storage tank 23. The NMP components are drained from the top of the refining tower 321 and pumped into the NMP finished product storage tank 23 for storage, while the recombinant impurities are drained from the bottom of the refining tower, collected, and combined with the coating waste.

[0050] In special embodiments, the connecting lines of the existing devices or units or individual components are equipped with control valves and pumps as required; the control valves can be driven or controlled by other control methods, and the pumps serve to convey substances.

[0051] Working principle: The high-temperature NMP exhaust gas of the coating plant enters the heat recovery apparatus 111 through the induced draft fan, the temperature of the exhaust gas is 90-120 °C, in the heat recovery apparatus 111 as the hot medium, and the NMP exhaust gas after condensation by the multi-stage surface cooler 112 as the cold medium, the high-temperature NMP exhaust gas of 90-120 °C is heat exchanged with the NMP exhaust gas after condensation by the multi-stage table cooler 112 in the heat recovery apparatus 111, and the high-temperature NMP exhaust gas is reduced to 45-55 °C after cooling from 90-120 °C. The NMP exhaust gas, which is hot at 90 to 120 °C, is exchanged with the NMP exhaust gas that is condensed in the multi-stage surface cooler 112 in the heat recovery device 111, and the temperature of the NMP exhaust gas is reduced from 90 to 120 °C to 45 to 55 °C.A portion of the lowered NMP exhaust gas enters the chilled water condensing section of the multi-stage surface cooler 112 to exchange heat with the chilled water, and the other portion enters the absorption unit 12 via a fan;.

[0052] After cooling by the multi-stage surface cooler 112 in the cold water condensation range, the temperature of the NMP exhaust gas is reduced from 45 to 55 °C to about 15 °C and then enters the heat recovery unit 111 for heat exchange with the high-temperature NMP exhaust gas, where the temperature is increased from 15 °C to 60 to 75 °C, and is returned to the coating system for use by the return fan;

[0053] After cooling through the heat recovery unit 111, the NMP exhaust gas enters the absorption tower 121. The gas inlet of the absorption tower 121 is located at its base, and the absorbent inlet is located at its top. The NMP exhaust gas enters the absorption tower 121 and moves upwards, while the absorbent enters the absorption tower 121 from the absorbent inlet and moves downwards. The two are in reverse contact, and the NMP exhaust gas is absorbed by the absorbent. The aqueous NMP solution obtained after absorption is pumped out at the base of the absorption tower 121 and transported to the storage system. The storage and conveying system 2 is then installed.

[0054] The NMP recovery liquid in the NMP recycling storage tank 21 is transported by a pump to the dewatering tower 311 in the dewatering unit 31 and enters the dewatering tower 311 from the center of the dewatering tower 311 under the operating conditions of a peak pressure (gauge pressure) of -0.086 MPa, a peak temperature of 51-55°C, and a reflux ratio of 4:1, so that the water in the recovered liquid is separated from the NMP, and the water is discharged from the top of the dewatering tower and pumped into the wastewater storage tank 22 for storage. NMP and recombinant impurities are discharged at the bottom of the dewatering tower and pumped into the refining tower 321.

[0055] NMP and recombinant impurities enter the refining tower 321 from the central position of the refining tower 321, and under the operating conditions of peak pressure (gauge pressure) -0.097 MPa, peak temperature 110 to 115°C, reflux ratio 2:1, the NMP components are separated from the recombinant impurities, and the NMP components are discharged from the upper part of the refining tower 321 and transported by pumps to the NMP finished product storage tank 23 for storage, and the recombinant impurities are discharged from the lower part of the refining tower and collected and combined with the coating waste. The NMP components are discharged from the upper part of the refining tower 321 and pumped into the NMP finished product storage tank 23 for storage, while the recombinant impurities are discharged from the lower part of the refining tower and collected and combined with the coating waste.

[0056] In this embodiment, by combining the NMP exhaust gas liquefaction and recovery system, the storage and conveying system, and the NMP liquid regeneration system, the high-temperature NMP exhaust gas emitted by the coating system is passed through the present device and then directly meets the fully compliant quality requirements of the coating process.

[0057] NMP finished products can be fed directly into the coating process, thereby realizing the local recycling of NMP solvents, eliminating the packaging and transport of the waste liquid and the finished product in the NMP recycling process, and effectively solving the problems of high operating costs and long cycle time in existing NMP recycling.

[0058] The foregoing is only a better specific embodiment of the utility model; however, the scope of protection of the utility model is not limited thereto, and all modifications or replacements that any person skilled in the art could readily imagine within the technical field disclosed by the utility model fall within the scope of protection of the utility model. Therefore, the scope of protection of the utility model should be determined by the scope of protection of the claims.

Claims

[1] NMP recycling device for recycling and regenerating high-temperature NMP exhaust gas from a coating plant, characterized by that it comprises an NMP off-gas liquefaction recovery system (1), a storage and transportation system (2), and an NMP waste liquid regeneration system (3), which are sequentially connected via a conduit; the NMP off-gas liquefaction system (1) comprises a heat recovery unit (11) and an absorption unit (12) for at least liquefying the high-temperature NMP off-gas and / or treating it by absorption by an absorbent to obtain an NMP waste liquid; The storage and transport system (2) serves at least to receive the NMP waste liquid obtained by the NMP exhaust gas liquefaction system (1) and to transfer it to the NMP waste liquid regeneration system (3); The NMP waste liquid regeneration system (3) comprises a dewatering unit (31) and a refining unit (32), at least for dewatering, purifying and regenerating the NMP waste liquid transferred through the storage and transportation system (2). [2] NMP recycling device according to claim 1, characterized byin that the heat recovery unit (11) comprises a heat recovery unit (111) and a multi-stage surface cooler (112), wherein the heat carrier inlet of the heat recovery unit (111) is connected to the high-temperature NMP exhaust gas outlet of the coating device, and the heat medium outlet of the heat recovery unit (111) is connected to the gas inlet of the multi-stage surface cooler (112) in one way and to the gas inlet of the absorption unit (12) in the other way. The cold medium inlet of the heat recovery unit (111) is connected to the gas outlet of the multi-stage surface cooler (112), and the cold medium outlet is connected to the gas inlet of the coating device. The liquid outlet of the multi-stage surface cooler (112) is connected to the liquid inlet of the storage and conveying system (2). [3] NMP recycling device according to claim 2, characterized bythat the heat recovery unit (111) is a gas-to-gas heat exchanger; and the multi-stage surface cooler (112) is a gas-to-liquid heat exchanger and comprises a cooling water condensation section and a cold water condensation section. [4] NMP recycling unit according to claim 2, characterized by in that the absorption unit (12) comprises an absorption tower (121) and an absorption reflux pump (122), wherein the gas inlet of the absorption tower (121) is connected to a heat recovery unit (111), the liquid outlet is fully connected to the liquid inlet of the storage and discharge system (2), and the other path is connected via the absorption reflux pump (122) to the return inlet of the absorption tower (121), wherein the absorber inlet of the absorption tower (121) is connected to the dehydration unit (31). [5] NMP recycling device according to claim 4, characterized bythat the absorption tower (121) is provided with a corrugated packing made of stainless steel wire mesh. [6] NMP recycling device according to claim 1, characterized by in that the storage and conveying system (2) comprises an NMP recycling storage tank (21), wherein the liquid inlet of the NMP recycling storage tank (21) is connected to an absorption unit (12) and a heat recovery unit (11), and the liquid outlet is connected to a dewatering unit (31) for storing the NMP waste liquid and transporting it to the dewatering unit (31) for gas-liquid separation. The liquid outlet is connected to the dewatering unit (31) for storing the NMP waste liquid and transporting it to the dewatering unit (31) for gas-liquid separation. [7] NMP recycling device according to claim 6, characterized byin that the storage and conveying system (2) further comprises a wastewater storage tank (22) and an NMP finished product storage tank (23), wherein the wastewater storage tank (22) is connected to a dewatering unit (31) and an absorption unit (12), respectively, in order to receive the light fraction separated by the dewatering unit (31) and transfer it to the absorption unit (12) for use as NMP finished product. The inlet of the NMP finished product storage tank (23) is connected to the light fraction outlet of the refining unit (32). [8] NMP recycling device according to claim 6 or 7, characterized bythat the storage and conveying system (2) is further provided with an automatic control unit, wherein the storage tank of the storage and conveying system (2) is provided with a magnetic flap level gauge for controlling the height of the liquid level and an ultrasonic level gauge for controlling the excess level, wherein the automatic control unit is electrically connected to both the magnetic flap level gauge and the ultrasonic level gauge. [9] NMP recycling unit according to claim 1, characterized bythat the dewatering unit (31) comprises a dewatering tower (311), an upper cooler (312) of the dewatering tower, a gas-liquid separator (313) of the dewatering tower, a distillate tank (314) of the dewatering tower and a reboiler (315) of the dewatering tower, wherein a liquid inlet of the dewatering tower (311) is connected to the storage and conveying system (2), the outlet is connected to the reboiler (315) of the dewatering tower to form a recirculation circuit, the outlet of the light component of the dewatering tower (311) is connected to the upper cooler (312) of the dewatering tower, the dewatering tower, the gas-liquid separator (313) and the distillate tank of the dewatering tower (314) are in turn connected to each other, and the outlet of the Distillate tank of the dewatering tower (314) is fully connected to the dewatering tower (311),and the other route leads via the storage and transport system (2) to the absorption unit (12). [10] NMP recycling unit according to claim 9, characterized byin that the refining unit (32) comprises a refining tower (321), an upper cooler (322) of the refining tower, a gas-liquid separator (323) of the refining tower, a distillate tank (324) of the refining tower and a reboiler (325) of the refining tower, wherein the inlet of the refining tower (321) is connected to the outlet of the heavy fraction of a dewatering tower (311).The inlet of the refining tower (321) is connected to the recombination outlet of the dewatering tower (311), the outlet of which is connected to the refining tower reboiler (325) to form a recirculation circuit, and the outlet of the light component of the refining tower (321) is connected to the upper cooler (322) of the refining tower, the gas-liquid separator (323) of the refining tower and the distillate tank (324) of the refining tower in this order, and the outlet of the distillate tank (324) of the refining tower is connected to the refining tower (321) all the way, and the other way is connected to the storage and conveying system (2).

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