Nitrogen closed circulating material crushing system

Abstract

The utility model relates to a nitrogen closed circulating material crushing system, which is characterized in that a nitrogen supplementing source, a dust removal device, a nitrogen compression device and a crushing device are connected into a system, so that nitrogen can circulate in the system and is used for crushing materials, a cooler and a refrigerated dryer are arranged in the nitrogen compression device, and the cooler is used for reducing the temperature of the nitrogen and reducing the temperature of the refrigerated dryer. The refrigeration type drying machine is used for reducing the humidity of nitrogen, low-temperature and low-humidity nitrogen is adopted for smashing when materials are smashed, the materials are prevented from being agglomerated, meanwhile, the dust removal device is provided with an exhaust channel and an exhaust valve, the nitrogen supplementing valve and the exhaust valve are opened, air is exhausted through the exhaust channel, and the air is replaced out of the exhaust valve through closed circulation. The concentration of nitrogen is high enough, and dust explosion is prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of material crushing systems, and particularly relates to a nitrogen closed-loop material crushing system. Background Art

[0002] In recent years, in the material crushing system, nitrogen, as an inert gas, is often used to replace air for fluid crushing, so it is not flammable or explosive and has high safety in use. The prior art, such as a nitrogen cycle air flow material crushing system and its working process disclosed in CN111604148A, includes a nitrogen source workstation, an air compressor, a gas storage tank, a filtering device, a material crushing main machine, a dust removal and collection device, a dust filter and a balance tank, which are connected to the air compressor through a mixing pipeline. An air inlet is provided on the mixing pipeline, and external air enters the air compressor through the air inlet and is mixed with the nitrogen. The material crushing main machine crushes the material with the mixed gas. After filtering the mixed gas, the mixed gas enters the balance tank to form a circulating system, realizing the recycling of nitrogen.

[0003] The following problems exist in the prior art:

[0004] The special binder NEF material for lithium batteries is an organic substance. Nitrogen is used for conveying and crushing to prevent explosion. However, agglomeration occurs when the material temperature is too high. In addition, nitrogen and air are mixed together, and the concentration of nitrogen cannot be guaranteed. Summary of the Utility Model

[0005] In view of the above problems, this application provides a nitrogen closed-loop material crushing system for solving the technical problems of agglomeration when the material temperature is too high and the inability to guarantee the concentration of nitrogen.

[0006] To achieve the above object, in the first aspect, this application provides a nitrogen closed-loop material crushing system, including a nitrogen replenishment source, a dust removal device, a nitrogen compression device and a crushing device. The nitrogen replenishment source is used to provide nitrogen. A first valve is provided on one side of the nitrogen replenishment source, and the first valve is used to start or pause the nitrogen supply of the nitrogen replenishment source. The dust removal device is connected to the nitrogen replenishment source, and the dust removal device includes a primary dust collector and a secondary dust collector 、The return air pipeline of the secondary dust collector, the exhaust pipeline and the exhaust valve. The secondary dust collector is connected to the nitrogen supplement source. The secondary dust collector and the primary dust collector are connected through the return air pipeline of the secondary dust collector. A blanking valve is provided at the bottom of the primary dust collector. The exhaust pipeline is connected to the return air pipeline of the secondary dust collector. The exhaust pipeline is used to discharge air. The exhaust valve is installed on the exhaust pipeline. The nitrogen compression device includes a first air supply pipeline, a centrifugal compressor, a cooler and a refrigerated dryer. One end of the first air supply pipeline is connected to the top of the secondary dust collector, and the other end of the first air supply pipeline is connected to the centrifugal compressor. The centrifugal compressor is connected to the cooler, and the cooler is connected to the refrigerated dryer. The pulverizing device includes a pulverizing pipeline, a blanking container, a jet mill and a discharge pipe. One end of the pulverizing pipeline is connected to the nitrogen compression device, and the other end of the pulverizing pipeline is connected to the jet mill. The bottom of the blanking container is connected to one side of the jet mill. An air classifier wheel is provided on the jet mill. One end of the discharge pipe is connected to the top of the jet mill, and the other end of the discharge pipe is connected to the primary dust collector.

[0007] As an embodiment of the present invention, a pressure sensor is provided on the return air pipeline of the secondary dust collector. The pressure sensor is used to detect the pressure inside the dust removal device.

[0008] As an embodiment of the present invention, a dust concentration detector and an oxygen concentration detector are further provided on the return air pipeline of the secondary dust collector. The dust concentration detector is used to detect the dust concentration inside the dust removal device, and the oxygen concentration detector is used to detect the oxygen concentration inside the dust removal device.

[0009] As an embodiment of the present invention, the nitrogen compression device further includes an air filter. One end of the air filter is connected to the secondary dust collector through the first air supply pipeline, and the other end of the air filter is connected to the centrifugal compressor.

[0010] As an embodiment of the present invention, a differential pressure gauge is provided on the air filter. The differential pressure gauge is used to measure the change in differential pressure when the air flow in the filter passes through.

[0011] As an embodiment of the present invention, the nitrogen compression device further includes a first pipeline filter and a second pipeline filter. The first pipeline filter is installed between the centrifugal compressor and the cooler, and the second pipeline filter is installed and connected to the refrigerated dryer.

[0012] As an embodiment of the present utility model, the nitrogen compression device further includes a second air supply pipeline, one end of the second air supply pipeline is connected to the second pipeline filter, and the other end of the second air supply pipeline is connected to the pulverizing pipeline.

[0013] As an embodiment of the present utility model, a temperature sensor, a dew point detector, and an oxygen concentration detector are provided on the second air supply pipeline. The temperature sensor is used to detect the gas temperature of the second air supply pipeline, the dew point detector is used to detect the gas dew point humidity of the second air supply pipeline, and the oxygen concentration detector is used to detect the gas oxygen concentration of the second air supply pipeline.

[0014] As an embodiment of the present utility model, the nitrogen compression device further includes a nitrogen return pipeline, one end of the nitrogen return pipeline is connected to the first air supply pipeline, and the other end of the nitrogen return pipeline is connected to the second air supply pipeline.

[0015] As an embodiment of the present utility model, a third air supply pipeline is provided on one side of the nitrogen replenishment source. The third air supply pipeline is used to connect the nitrogen replenishment source and the secondary dust collector, and a flow meter is provided on the third air supply pipeline.

[0016] Different from the prior art, the technical solution of the present application connects the nitrogen replenishment source, the dust removal device, the nitrogen compression device, and the pulverizing device into a system, so that nitrogen can circulate in the system and be used to pulverize materials. A cooler and a refrigerated dryer are provided in the nitrogen compression device. The cooler is used to lower the temperature of nitrogen, and the refrigerated dryer is used to lower the humidity of nitrogen. When pulverizing materials, low-temperature and low-humidity nitrogen is used for pulverization to prevent the materials from agglomerating. At the same time, the dust removal device is provided with an exhaust passage and an exhaust valve. By opening the nitrogen replenishment valve and the exhaust valve, air is discharged through the exhaust passage, and the air is replaced from the exhaust valve through a closed-loop cycle to ensure that the concentration of nitrogen is high enough to prevent dust explosion.

[0017] The above relevant descriptions of the utility model content are only an overview of the technical solution of the present application. In order to enable those of ordinary skill in the art to more clearly understand the technical solution of the present application, and then can be implemented according to the content recorded in the text of the specification and the drawings, and in order to make the above objects, other objects, features, and advantages of the present application more easily understood, the following is described in conjunction with the specific embodiments and drawings of the present application. Description of the Drawings

[0018] The drawings are only used to illustrate the principles, implementation methods, applications, features, and effects of the specific embodiments and other related contents of the present application, and should not be considered as a limitation to the present application.

[0019] In the drawings of the specification:

[0020] Figure 1 This is a schematic structural diagram of a nitrogen closed-loop material crushing system of the present application;

[0021] Figure 2 This is a schematic structural diagram of the dust removal device of a nitrogen closed-loop material crushing system of the present application;

[0022] Figure 3 This is a schematic structural diagram of the nitrogen compression device of a nitrogen closed-loop material crushing system of the present application;

[0023] Figure 4 This is a schematic structural diagram of the crushing device of a nitrogen closed-loop material crushing system of the present application;

[0024] Figure 5 This is a schematic diagram of the nitrogen flow of a nitrogen closed-loop material crushing system of the present application.

[0025] The reference numerals involved in the above-mentioned drawings are explained as follows:

[0026] 1. Nitrogen replenishment source,

[0027] 2. First valve,

[0028] 3. Dust removal device, 31. Primary dust collector, 32. Secondary dust collector, 33. Return air pipeline of the secondary dust collector, 331. Pressure sensor, 332. Dust concentration detector, 333. First oxygen concentration detector, 34. Exhaust pipeline, 35. Exhaust valve,

[0029] 4. Nitrogen compression device, 41. First air supply pipeline, 42. Centrifugal compressor, 43. Cooler, 44. Refrigerated dryer, 45. Air filter, 451. Differential pressure gauge, 46. First pipeline filter, 47. Second pipeline filter, 48. Second air supply pipeline, 49. Temperature sensor, 410. Dew point detector, 411. Second oxygen concentration detector, 412. Nitrogen circuit pipeline,

[0030] 5. Crushing device, 51. Crushing pipeline, 52. Feeding container, 53. Jet mill, 531. Jet mill classifier wheel, 54. Discharge pipe,

[0031] 6. Third air supply pipeline, 61. Flowmeter. Detailed implementation manners

[0032] To describe in detail the possible application scenarios, technical principles, specific implementable solutions, achievable purposes and effects of the present application, the following is described in detail with reference to the specific examples listed and in conjunction with the drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, so they are only examples and cannot be used to limit the protection scope of the present application.

[0033] As used herein, the mention of "embodiment" means that the specific features, structures, or characteristics described in connection with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing at various positions in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or relevance to other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0034] Unless otherwise defined, the meanings of the technical terms used herein are the same as those commonly understood by those skilled in the technical field to which the present application belongs; the use of the relevant terms herein is only for describing specific embodiments and is not intended to limit the present application.

[0035] In the description of the present application, the term "and / or" is an expression used to describe the logical relationship between objects, indicating that there can be three relationships. For example, X and / or Y means: the existence of X, the existence of Y, and the simultaneous existence of X and Y. In addition, the character " / " herein generally represents an "or" logical relationship between the associated objects before and after.

[0036] In the present application, terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantitative, primary-secondary, or sequential relationship between these entities or operations.

[0037] Without further limitation, in the present application, the use of the terms "comprise", "include", "have", or other similar expressions in a statement is intended to cover non-exclusive inclusion. These expressions do not exclude the possibility that there may be additional elements in the process, method, or product including the said elements, such that the process, method, or product including a series of elements may include not only those defined elements, but also other elements not explicitly listed, or elements inherent to such process, method, or product.

[0038] In the present application, expressions such as "greater than", "less than", "exceeding", etc. are understood not to include the number itself; expressions such as "above", "below", "within", etc. are understood to include the number itself. In addition, in the description of the embodiments of the present application, the meaning of "a plurality of" is two or more (including two), and similar expressions related to "many" are understood in the same way, such as "multiple groups", "multiple times", etc., unless otherwise specifically defined.

[0039] In the description of the embodiments of the present application, the spatially related expressions used, such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "perpendicular", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiment or the accompanying drawings. It is only for the convenience of describing the specific embodiments of the present application or facilitating the understanding of the readers, rather than indicating or implying that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of the present application.

[0040] Unless otherwise clearly specified or limited, in the description of the embodiments of the present application, the terms such as "installed", "connected", "joined", "fixed", "set", etc. should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication inside two elements or the interaction relationship between two elements. For those skilled in the art to which the present application pertains, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0041] According to some embodiments of the present application, please refer to Figures 1 to 5 , this embodiment relates to a nitrogen closed-loop material pulverizing system, including a nitrogen replenishing source 1, a dust removal device 3, a nitrogen compression device 4, and a pulverizing device 5. The nitrogen replenishing source 1 is used to provide nitrogen. A first valve 2 is provided on one side of the nitrogen replenishing source 1, and the first valve 2 is used to start or pause the nitrogen supply of the nitrogen replenishing source 1; the dust removal device 3 is connected to the nitrogen replenishing source 1, and the dust removal device 3 includes a primary dust collector 31 and a secondary dust collector 32 、The return air pipeline 33 of the secondary dust collector, the exhaust pipeline 34 and the exhaust valve 35. The secondary dust collector 32 is connected to the nitrogen replenishment source 1. The secondary dust collector 32 and the primary dust collector 31 are connected through the return air pipeline 33 of the secondary dust collector. A discharge valve is provided at the bottom of the primary dust collector 31. The exhaust pipeline 34 is connected to the return air pipeline 33 of the secondary dust collector. The exhaust pipeline 34 is used to discharge air. The exhaust valve 35 is installed on the exhaust pipeline 34; The nitrogen compression device 4 includes a first air supply pipeline 41, a centrifugal compressor 42, a cooler 43 and a refrigerated dryer 44. One end of the first air supply pipeline 41 is connected to the top of the secondary dust collector 32, and the other end of the first air supply pipeline 41 is connected to the centrifugal compressor 42. The centrifugal compressor 42 is connected to the cooler 43, and the cooler 43 is connected to the refrigerated dryer 44; The pulverizing device 5 includes a pulverizing pipeline 51, a feeding container 52, a jet mill 53 and a discharge pipe 54. One end of the pulverizing pipeline 51 is connected to the nitrogen compression device 4, and the other end of the pulverizing pipeline 51 is connected to the jet mill 53. The bottom of the feeding container 52 is connected to one side of the jet mill 53. An air classifier wheel 531 is provided on the jet mill 53. One end of the discharge pipe 54 is connected to the top of the jet mill 53, and the other end of the discharge pipe 54 is connected to the primary dust collector 31.

[0042] During use, the nitrogen replenishment source 1 provides nitrogen. When the first valve 2 is opened, the nitrogen enters the secondary dust collector 32. When the exhaust valve 35 is opened, the nitrogen enters the exhaust passage through the return air pipeline 33 of the secondary dust collector, and the air in the exhaust passage is displaced by the nitrogen. At the same time, the nitrogen passes through the primary dust collector 31 and enters the jet mill 53 for pulverizing materials. When the air is emptied, the first valve 2 is closed. A part of the nitrogen in the secondary dust collector 32 flows to the nitrogen compression device 4. The nitrogen is compressed, cooled and dehumidified, enters the pulverizing pipeline 51, and finally enters the jet mill 53 to pulverize the materials. The pulverized materials are subjected to solid-gas separation through filter bags in the primary dust collector 31. The nitrogen passes through the return air pipeline 33 of the secondary dust collector, the secondary dust collector 32 and the nitrogen compression device 4 and enters the recycling of the gas. In this way, the nitrogen is recycled, saving costs. At the same time, the nitrogen is compressed, cooled and dehumidified, and the obtained nitrogen is in a low-temperature and low-humidity state, which is convenient for pulverizing materials and preventing the materials from agglomerating. It is convenient to empty the air in the nitrogen closed-loop material pulverizing system by using the exhaust valve 35 and the exhaust passage, ensuring that the concentration of nitrogen is high enough to prevent dust explosion.

[0043] According to some embodiments of the present application, optionally, a pressure sensor 331 is provided on the return air pipeline 33 of the secondary dust collector, and the pressure sensor 331 is used to detect the pressure in the dust removal device 3.

[0044] According to some embodiments of the present application, optionally, a dust concentration detector 332 and a first oxygen concentration detector 333 are further provided on the return air pipeline 33 of the secondary dust collector. The dust concentration detector 332 is used to detect the dust concentration in the dust removal device 3, and the first oxygen concentration detector 333 is used to detect the oxygen concentration in the dust removal device 3.

[0045] In this way, when nitrogen enters the interior of the dust removal device 3, it is convenient to monitor the pressure value, dust concentration value, and oxygen concentration value in the return air pipeline 33 of the secondary dust collector. After the pressure value, dust concentration value, and oxygen concentration value reach the set values, the first valve 2 is closed, and the nitrogen in the secondary dust collector 32 can enter the nitrogen compression device 4, facilitating the staff to observe the values in real time, and by closing the first valve 2 and opening the centrifugal compressor 42, the nitrogen enters the nitrogen compression device 4.

[0046] According to some embodiments of the present application, optionally, the nitrogen compression device 4 further includes an air filter 45. One end of the air filter 45 is connected to the secondary dust collector 32 through a first air supply pipeline 41, and the other end of the air filter 45 is connected to the centrifugal compressor 42.

[0047] In this way, the nitrogen in the secondary dust collector 32 enters the air filter 45 through the first air supply pipe, facilitating the filtration of nitrogen by the air filter 45 to reduce the impurities in the nitrogen.

[0048] According to some embodiments of the present application, optionally, a differential pressure gauge 451 is provided on the air filter 45, and the differential pressure gauge 451 is used to measure the change in differential pressure when the air flow in the air filter 45 passes through.

[0049] In this way, it is convenient to monitor the change in differential pressure when the air flow in the air filter 45 passes through in real time. An increase in the differential pressure change of the air filter 45 can reflect an increase in the internal resistance level of the filter and a greater degree of blockage of the filter. The staff can judge whether the air filter 45 needs to be cleaned or replaced in a timely manner based on the differential pressure change to extend the service life of the filter.

[0050] According to some embodiments of the present application, optionally, the nitrogen compression device 4 further includes a first pipeline filter 46 and a second pipeline filter 47. The first pipeline filter 46 is installed between the centrifugal compressor 42 and the cooler 43, and the second pipeline filter 47 is installed and connected to the refrigerated dryer 44.

[0051] In this way, before the nitrogen is cooled and dehumidified, the nitrogen is filtered by the first pipeline filter 46 to reduce impurities. After the nitrogen is cooled and dehumidified, the nitrogen is filtered by the second pipeline filter 47 to further reduce impurities.

[0052] According to some embodiments of the present application, optionally, the nitrogen compression device 4 further includes a second air supply pipeline 48. One end of the second air supply pipeline 48 is connected to the second pipeline filter 47, and the other end of the second air supply pipeline 48 is connected to the pulverizing pipeline 51.

[0053] In this way, it is convenient to transport the compressed, cooled, and dehumidified nitrogen to the pulverizing pipeline 51 through the second air supply pipeline 48.

[0054] According to some embodiments of the present application, optionally, a temperature sensor 49, a dew point detector 410, and a second oxygen concentration detector 411 are provided on the second air supply pipeline 48. The temperature sensor 49 is used to detect the gas temperature of the second air supply pipeline 48, the dew point detector 410 is used to detect the gas dew point humidity of the second air supply pipeline 48, and the second oxygen concentration detector 411 is used to detect the gas oxygen concentration of the second air supply pipeline 48.

[0055] In this way, it is convenient to monitor the gas temperature, dew point humidity, and oxygen concentration in the second air supply pipeline 48 after the nitrogen passes through the centrifugal compressor 42, the cooler 43, and the refrigerated dryer 44. After reaching the set value, it enters the pulverizing device 5 to realize the full - range detection and control of the pipeline.

[0056] According to some embodiments of the present application, optionally, the nitrogen compression device 4 further includes a nitrogen return pipeline 412. One end of the nitrogen return pipeline 412 is connected to the first air supply pipeline 41, and the other end of the nitrogen return pipeline 412 is connected to the second air supply pipeline 48.

[0057] In this way, when the gas temperature, dew point humidity, and oxygen concentration in the second air supply pipeline 48 do not reach the set value after the nitrogen passes through the centrifugal compressor 42, the cooler 43, and the refrigerated dryer 44, the nitrogen passes through the nitrogen return pipeline 412 and enters the first air supply pipeline 41 again for compression, cooling, and dehumidification treatment again to reach the set value.

[0058] According to some embodiments of the present application, optionally, a third air supply pipeline 6 is provided on one side of the nitrogen supply source 1. The third air supply pipeline 6 is used to connect the nitrogen supply source 1 and the secondary dust collector 32, and a flow meter 61 is provided on the third air supply pipeline 6.

[0059] In this way, the nitrogen of the nitrogen supply source 1 is convenient to enter the secondary dust collector 32 through the third air supply pipeline 6, and the nitrogen flow rate level of the third air supply pipeline 6 is monitored through the flow meter 61.

[0060] When the crushing system clicks the start button, the first valve 2 opens, the exhaust valve 35 opens, and the closed-loop system starts to supplement nitrogen. Through the closed-loop circulation, the air is displaced from the exhaust valve 35. The classifier wheel 531 of the jet mill starts, and the protective gas valve of the synchronous classifier wheel 531 of the jet mill opens. When the pressure and oxygen concentration in the system are detected by the pressure sensor 331 and the first oxygen concentration detector 333 and reach the set values, the exhaust valve 35 closes, the centrifugal compressor 42 is started, and nitrogen enters the centrifugal compressor 42 through the air filter 45. The compressed nitrogen is then heat-exchanged through the cooler 43 and reduced to the set temperature, i.e., less than 15 °C, and then enters the refrigerated dryer 44 for dehumidification. After being detected by the temperature sensor 49, the second oxygen concentration detector 411, and the dew point detector 410 and meeting the set values, the feeding butterfly valve of the jet mill opens and starts to feed. The dried compressed nitrogen enters the jet mill 53 to start crushing the material. The crushed material is screened by the classifier wheel 531 of the jet mill and then enters the first dust collector 31, where solid-gas separation is carried out through the internal filter bags. The material enters the downstream through the first dust collection feeding butterfly valve, and the gas passes through the return air pipeline 33 of the second dust collector 32 from the upper part of the first dust collector 31 and then enters the centrifugal compressor 42 to form a closed-loop circulation.

[0061] This system prevents the generation of dust explosion from the source by means of nitrogen circulation and transportation for crushing, and is equipped with a first oxygen concentration detector 333, a second oxygen concentration detector 411, a pressure sensor 331, a temperature sensor 49, a dew point detector 410, and a dust concentration detector 332 in the system to achieve comprehensive detection and control of the pipeline.

[0062] Those skilled in the art can understand that although some embodiments herein include certain features included in other embodiments rather than other features, the combination of the features of different embodiments means that it is within the scope of this application and forms different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered by the scope of the claims and the description of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. This application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A nitrogen closed cycle material crushing system, characterized in that: include: A nitrogen supplement source, the nitrogen supplement source is used to provide nitrogen, a first valve is provided on one side of the nitrogen supplement source, and the first valve is used to start or stop the nitrogen supply of the nitrogen supplement source; A dust removal device, the dust removal device is connected to the nitrogen supplement source, and the dust removal device includes a primary dust collector and a secondary dust collector. 、 A secondary dust collector return air duct, an exhaust duct and an exhaust valve, wherein the secondary dust collector is connected to the nitrogen supplement source, the secondary dust collector is connected to the primary dust collector through the secondary dust collector return air duct, a discharge valve is provided at the bottom of the primary dust collector, the exhaust duct is connected to the secondary dust collector return air duct, the exhaust duct is used to exhaust air, and the exhaust valve is installed on the exhaust duct; A nitrogen compression device, the nitrogen compression device comprising a first air supply pipeline, a centrifugal compressor, a cooler and a refrigerated dryer, one end of the first air supply pipeline is connected to the top of the secondary dust collector, the other end of the first air supply pipeline is connected to the centrifugal compressor, the centrifugal compressor is connected to the cooler, and the cooler is connected to the refrigerated dryer; as well as A pulverizing device, the pulverizing device comprises a pulverizing pipe, a feeding container, an air flow pulverizer and a discharging pipe, one end of the pulverizing pipe is connected to the nitrogen compression device, the other end of the pulverizing pipe is connected to the air flow pulverizer, the bottom of the feeding container is connected to one side of the air flow pulverizer, the air flow pulverizer is provided with an air flow grinding classifying wheel, one end of the discharging pipe is connected to the top of the air flow pulverizer, and the other end of the discharging pipe is connected to the primary dust collector.

2. A nitrogen closed cycle material pulverizing system according to claim 1, characterized in that: A pressure sensor is provided on the return air duct of the secondary dust collector, and the pressure sensor is used to detect the pressure in the dust removal device.

3. A nitrogen closed cycle material pulverizing system according to claim 2, characterized in that: The secondary dust collector return air duct is also provided with a dust concentration detector and an oxygen concentration detector. The dust concentration detector is used to detect the dust concentration in the dust removal device, and the oxygen concentration detector is used to detect the oxygen concentration in the dust removal device.

4. A nitrogen closed cycle material pulverizing system according to claim 1, characterized in that: The nitrogen compression device further comprises an air filter, one end of which is connected to the secondary dust collector via the first air supply pipe, and the other end of which is connected to the centrifugal compressor.

5. A nitrogen closed cycle material pulverizing system according to claim 4, characterized in that: The air filter is provided with a differential pressure gauge, which is used to measure the pressure difference change when the airflow in the filter passes through.

6. The nitrogen closed cycle material pulverizing system according to claim 1, characterized in that: The nitrogen compression device further comprises a first pipeline filter and a second pipeline filter, wherein the first pipeline filter is installed between the centrifugal compressor and the cooler, and the second pipeline filter is installed and connected to the refrigerated dryer.

7. A nitrogen closed cycle material pulverizing system according to claim 6, characterized in that: The nitrogen compression device further comprises a second air supply pipeline, one end of which is connected to the second pipeline filter, and the other end of which is connected to the pulverizing pipeline.

8. A nitrogen closed cycle material pulverizing system according to claim 7, characterized in that: The second air supply pipeline is provided with a temperature sensor, a dew point detector and an oxygen concentration detector. The temperature sensor is used to detect the gas temperature of the second air supply pipeline, the dew point detector is used to detect the dew point humidity of the gas in the second air supply pipeline, and the oxygen concentration detector is used to detect the oxygen concentration of the gas in the second air supply pipeline.

9. A nitrogen closed cycle material pulverizing system according to claim 8, characterized in that: The nitrogen compression device further comprises a nitrogen loop pipeline, one end of which is connected to the first air supply pipeline, and the other end of which is connected to the second air supply pipeline.

10. The nitrogen closed cycle material pulverizing system according to claim 1, characterized in that: A third air supply pipeline is provided on one side of the nitrogen supply source, and the third air supply pipeline is used to connect the nitrogen supply source and the secondary dust collector. A flow meter is provided on the third air supply pipeline.

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