Nitrogen circulation refrigeration system, nitrogen low-temperature pulverization treatment equipment and nitrogen treatment method

Abstract

The application belongs to the technical field of industrial refrigeration and gas treatment, and discloses a nitrogen circulation refrigeration system, a nitrogen low-temperature pulverizing treatment equipment and a nitrogen treatment method. The system comprises a nitrogen side supply module, a refrigeration side circulation flow module and a defrosting control module. The cascade dehumidification refrigeration module of the nitrogen side supply module comprises a first-stage water removal refrigerating machine and a second-stage water removal refrigerating machine set, the second-stage water removal refrigerating machine set comprises second-stage water removal refrigerating machines arranged in parallel and selectively communicated with the first-stage water removal refrigerating machine; a liquid supply end and a gas return end of a refrigerant flow pipeline are respectively connected with refrigerant channels of the first-stage water removal refrigerating machine and the second-stage water removal refrigerating machine; refrigerant channels of each second-stage water removal refrigerating machine are selectively communicated with the refrigerant flow pipeline or a defrosting bypass pipeline, and when the second-stage water removal refrigerating machine is communicated with the defrosting bypass pipeline, the corresponding nitrogen on-off valve is closed. The system has the advantages of compact structure, anti-icing, continuous operation, high safety and corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of industrial refrigeration and gas treatment technology, and in particular to a nitrogen circulation refrigeration system, a nitrogen cryogenic pulverizing treatment device, and a nitrogen treatment method. Background Technology

[0002] In the cryogenic pulverization process of rubber, thermoplastics, and special alloys, it is necessary to continuously circulate dry, cold nitrogen gas at -30°C into the pulverizing chamber to counteract the frictional heat of pulverization and prevent material oxidation. However, existing engineering solutions typically suffer from the following technical drawbacks: Equipment dispersion and cold energy loss: Traditional systems separate the refrigeration unit from the terminal evaporator, or connect the dust removal and dehumidification equipment through external pipelines. This not only takes up space, but also causes cold energy to be lost during long-distance transportation, making it difficult to ensure that the nitrogen entering the pulverizer is stably maintained at -30℃. Ice blockage problem under cryogenic conditions: The nitrogen gas (>20℃) returning from the crusher contains trace amounts of moisture. If it enters the evaporator at -30℃ directly, the water vapor will instantly condense into ice and adhere to the heat exchange fins, resulting in a sharp increase in wind resistance, inability to output cooling capacity, and forced frequent system shutdowns for defrosting. Poor safety and continuity of defrosting: Commonly used electric defrosting has high energy consumption and poses safety hazards in flammable and explosive dust environments. In addition, the single evaporator design requires production to be interrupted during defrosting. Corrosion risk: The condensate that precipitates at low temperatures is corrosive, and ordinary carbon steel or aluminum heat exchangers are prone to rusting, contaminating high-purity materials.

[0003] In summary, there is an urgent need to design a nitrogen circulation refrigeration system, a nitrogen cryogenic pulverization treatment device, and a nitrogen treatment method to improve the shortcomings of existing engineering solutions. Summary of the Invention

[0004] One objective of this invention is to provide a nitrogen circulation refrigeration system that addresses the technical problems in existing related technologies, such as low equipment integration, easy evaporator icing and blockage, the need for shutdown during defrosting which poses safety hazards, and easy equipment corrosion.

[0005] To achieve this objective, the present invention adopts the following technical solution: Nitrogen cycle refrigeration system, including: A nitrogen supply module includes a housing, a nitrogen flow pipeline, and a cascade dehumidification and refrigeration module disposed within the housing. The cascade dehumidification and refrigeration module includes a primary dehumidification chiller and a secondary dehumidification chiller unit arranged sequentially along the nitrogen flow direction on the nitrogen flow pipeline. The primary dehumidification chiller is used to perform primary condensation and dehumidification on the return nitrogen. The secondary dehumidification chiller unit includes at least two secondary dehumidification chillers arranged in parallel. Each of the secondary dehumidification chillers is selectively connected to the primary dehumidification chiller to perform secondary condensation and dehumidification on the intermediate nitrogen after primary condensation and dehumidification. The refrigeration-side circulating flow module includes a refrigerant flow pipeline, and a compressor and a condenser sequentially arranged along the refrigerant flow pipeline. The liquid supply end and gas return end of the refrigerant flow pipeline are respectively connected to the refrigerant channel of the first-stage dehydration chiller and the refrigerant channel of the second-stage dehydration chiller. Refrigerant circulates within the refrigerant flow pipeline and is used to condense the return nitrogen and the intermediate nitrogen. The defrosting control module includes a defrosting bypass pipeline and a nitrogen on / off valve. The inlet of the defrosting bypass pipeline is connected to the refrigerant flow pipeline located between the exhaust port of the compressor and the condenser. The outlet of the defrosting bypass pipeline is connected to the refrigerant channel inlet of each of the secondary dehydration chillers. The nitrogen on / off valve is set one-to-one with each of the secondary dehydration chillers. The refrigerant channel inlet of each of the two-stage dehydration chillers can be selectively connected to the refrigerant circulation pipeline or the defrost bypass pipeline, and when the two-stage dehydration chiller is connected to the defrost bypass pipeline, the corresponding nitrogen on / off valve is closed.

[0006] Preferably, the defrosting bypass pipeline includes a defrosting bypass main pipe, at least two defrosting bypass branch pipes, and at least two bypass control valves. One end of the defrosting bypass main pipe forms the inlet of the defrosting bypass pipeline, and the other end of the defrosting bypass main pipe is connected to each of the defrosting bypass branch pipes. The defrosting bypass branch pipes are connected one-to-one with the refrigerant channel inlet of each of the secondary water removal chillers, and each of the defrosting bypass branch pipes is provided with a bypass control valve.

[0007] Preferably, the defrosting control module further includes a central control unit and a monitoring unit. The central control unit is communicatively connected to the monitoring unit, the bypass control valve, and the nitrogen on / off valve. The monitoring unit is used to monitor the operating status of each of the secondary dewatering chillers and transmit the monitoring signal to the central control unit. The central control unit controls the opening and closing of the bypass control valve and the nitrogen on / off valve according to the monitoring signal.

[0008] Preferably, the monitoring unit includes a dew point sensor, a differential pressure sensor, and a temperature sensor. The dew point sensor is used to monitor the humidity of the nitrogen gas output by each of the secondary dehumidification chillers. The differential pressure sensor is used to monitor the pressure difference between the nitrogen gas flow pipeline section located before the primary dehumidification chiller and the nitrogen gas flow pipeline section located after each of the secondary dehumidification chillers. The temperature sensor is used to monitor the surface temperature of the condensation dehumidification coil of each of the secondary dehumidification chillers. When the humidity exceeds a first preset threshold, and / or the pressure difference exceeds a second preset threshold, and / or the surface temperature exceeds a third preset threshold, the central control unit controls the corresponding bypass control valve to open and the corresponding nitrogen on / off valve to close.

[0009] Preferably, the refrigerant flow pipeline includes a liquid supply main pipe, a liquid supply branch pipe, a return gas main pipe, a return gas branch pipe, and a refrigerant control valve; one end of the liquid supply main pipe is connected to the liquid outlet of the condenser, and the other end of the liquid supply main pipe is connected to each of the liquid supply branch pipes; the liquid supply branch pipes are connected one-to-one with the primary dehydration chiller and each of the secondary dehydration chillers, and each of the liquid supply branch pipes is equipped with the refrigerant control valve; one end of the return gas main pipe is connected to the gas inlet of the condenser, and the other end of the return gas main pipe is connected to each of the return gas branch pipes via the compressor; the return gas branch pipes are connected one-to-one with the refrigerant channel outlets of each of the secondary dehydration chillers; The central control unit is also communicatively connected to each of the refrigerant control valves; when the bypass control valve is open and the nitrogen on / off valve is closed, the central control unit controls the corresponding refrigerant control valve to close.

[0010] Preferably, the primary dehumidification chiller is used to cool the reflux nitrogen gas to 5°C to 10°C for primary condensation dehumidification; the secondary dehumidification chiller is used to cool the intermediate nitrogen gas to -30°C for secondary condensation dehumidification.

[0011] Preferably, the system also includes a condensate collection module, which includes a storage tank, multiple condensate delivery pipelines, and multiple condensate control valves. The inlet of the storage tank is connected to the multiple condensate delivery pipelines, and the multiple condensate delivery pipelines are respectively connected to the drain outlets of the primary dehydration chiller and the drain outlets of each of the secondary dehydration chillers. Each condensate delivery pipeline is equipped with a condensate control valve.

[0012] Preferably, the storage tank is provided with a visible liquid level window; and / or, the condensate collection module further includes a liquid level gauge, which is located in the storage tank; and / or, the condensate collection module further includes a drain pump, which is connected to the storage tank and has a drain control valve between it and the storage tank; and / or, the condensate control valve and the drain control valve are pneumatic angle seat valves.

[0013] Preferably, both the primary dehydration chiller and the secondary dehydration chiller employ finned heat exchangers; and / or, the nitrogen on / off valve is a pneumatic butterfly valve; and / or, the bypass control valve is an electronic expansion valve; and / or, the refrigerant control valve is an electronic expansion valve.

[0014] Another objective of this invention is to provide a nitrogen cryogenic pulverizing treatment device that can reduce maintenance frequency and cost, save space, ensure continuous and uninterrupted operation of gas-using terminal equipment, and has lower energy consumption and higher safety during defrosting.

[0015] To achieve this objective, the present invention adopts the following technical solution: A nitrogen cryogenic pulverizing and processing device includes a pulverizer and the aforementioned nitrogen circulation refrigeration system. The nitrogen circulation refrigeration system includes a nitrogen-side supply module, which includes a nitrogen flow pipeline. The nitrogen flow pipeline is circulatedly connected to the pulverizer.

[0016] Another objective of this invention is to provide a nitrogen treatment method that can mitigate the increase in wind resistance, reduce maintenance frequency, cost, and cooling loss, and consume less energy during defrosting, while ensuring continuous and uninterrupted operation of the nitrogen refrigeration process, thus achieving a safe, stable, and reliable nitrogen treatment process.

[0017] To achieve this objective, the present invention adopts the following technical solution: The nitrogen treatment method utilizes the aforementioned cryogenic nitrogen pulverization equipment and specifically includes the following operational steps: The nitrogen flow line receives the return nitrogen from the pulverizer. The reflux nitrogen gas is passed into a primary dehumidification chiller for primary condensation and dehumidification to form intermediate nitrogen gas. The selected secondary dehumidification chiller is switched to working mode, and the intermediate nitrogen gas is introduced into the selected secondary dehumidification chiller for secondary condensation and dehumidification to obtain dry nitrogen gas. The dry nitrogen gas is discharged from the nitrogen gas flow pipeline and flows into the pulverizer; When one of the selected secondary dehumidification chillers switches from the working mode to the defrosting mode, the refrigerant channel inlet of the selected secondary dehumidification chiller is connected to the defrosting bypass pipeline, and the corresponding nitrogen on / off valve is closed. At the same time, another secondary dehumidification chiller is selected and switched to the working mode to continue to receive and perform secondary condensation and dehumidification of the intermediate nitrogen.

[0018] Beneficial effects: The nitrogen circulation refrigeration system provided in this application, by incorporating a tiered dehumidification refrigeration module, prevents moisture-containing return nitrogen from directly entering the secondary dehumidification chiller used for deep refrigeration. This prevents ice buildup on the heat exchange tube walls of the secondary dehumidification chiller, mitigating the dramatic increase in air resistance and reducing maintenance frequency and costs. Furthermore, since both the primary and secondary dehumidification chillers are integrated within the casing, space is saved, and nitrogen cooling loss within the nitrogen flow pipeline is reduced, ensuring that the dry nitrogen entering the end-use equipment is stably maintained at the target temperature. In addition, by incorporating a defrosting control module, continuous, uninterrupted system operation can be achieved by selecting different secondary dehumidification chillers. Moreover, for secondary dehumidification chillers disconnected from the nitrogen flow pipeline and requiring defrosting, high-temperature refrigerant vapor discharged from the compressor's exhaust port can be used for defrosting. Compared to commonly used electric heating defrosting methods, this approach consumes less energy, is safer, and avoids the need for system shutdown during defrosting.

[0019] The nitrogen cryogenic pulverizing equipment provided in this application incorporates the aforementioned nitrogen circulation refrigeration system. This allows the return nitrogen output from the end-user equipment to enter the nitrogen flow pipeline for condensation and dehumidification, while the dried nitrogen discharged from the pipeline re-enters the end-user equipment, thus achieving nitrogen recycling between the end-user equipment and the nitrogen circulation refrigeration system. This reduces maintenance frequency and costs, saves space, ensures continuous and uninterrupted operation of the end-user equipment, and provides lower energy consumption and higher safety during defrosting.

[0020] The nitrogen treatment method provided in this application can prevent backflow nitrogen containing moisture from directly entering the secondary dehydration chiller used for deep refrigeration, effectively reducing the increase in wind resistance, reducing maintenance frequency and costs, reducing cooling loss, and ensuring that the dry nitrogen entering the gas-using terminal equipment can be stably maintained at the target temperature. Moreover, by utilizing the defrosting control module, defrosting of the secondary dehydration chiller that requires defrosting can be performed, resulting in lower energy consumption, while ensuring continuous and uninterrupted operation of the nitrogen refrigeration process, thereby achieving a safe, stable, and reliable nitrogen treatment process. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the nitrogen cycle refrigeration system provided in the embodiments of the invention; Figure 2 This is a schematic diagram of the structure of the nitrogen cycle refrigeration system provided in this embodiment of the invention, in which the secondary water removal refrigeration unit A is in defrost mode and the secondary water removal refrigeration unit B is in working mode. Figure 3 This is a schematic diagram of the structure of the nitrogen cycle refrigeration system provided in this embodiment of the invention, with the secondary water removal refrigeration unit A in working mode and the secondary water removal refrigeration unit B in defrosting mode.

[0022] In the picture: 1. Nitrogen supply module; 11. Nitrogen flow pipeline; 121. Primary dehydration chiller; 1221. Secondary dehydration chiller; 2. Refrigeration side circulation module; 21. Refrigerant circulation pipeline; 211. Liquid supply end main circulation pipe; 212. Liquid supply end branch circulation pipe; 213. Gas return end main circulation pipe; 214. Gas return end branch circulation pipe; 215. Refrigerant control valve; 216. Dryer filter; 22. Compressor; 23. Condenser; 231. Safety valve; 3. Defrosting control module; 31. Defrosting bypass pipeline; 311. Defrosting bypass main pipe; 312. Defrosting bypass branch pipe; 313. Bypass control valve; 32. Nitrogen on / off valve; 331. Dew point sensor; 332. Differential pressure sensor; 333. Temperature sensor; 4. Cooling water heat exchange channel; 41. Cooling water inlet temperature sensor; 42. Cooling water outlet temperature sensor; 43. Flow switch; 5. Condensate collection module; 51. Storage tank; 511. Visual level window; 52. Condensate delivery pipeline; 53. Condensate control valve; 54. Level gauge; 55. Drain pipe; 56. Drain control valve; 57. Drain pump. Detailed Implementation

[0023] To make the technical problems solved by this invention, the technical solutions adopted, and the technical effects achieved clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to this invention, not the entire structure.

[0024] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0026] In the description of this embodiment, the terms "upper," "lower," "right," and "left," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, 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. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0027] The technical solution provided by the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Combination Figures 1 to 3 As shown, this application provides a nitrogen circulation refrigeration system, including a nitrogen supply module 1, a refrigeration circulation module 2, and a defrosting control module 3.

[0029] The nitrogen supply module 1 includes a housing, a nitrogen flow pipeline 11, and a cascade dehumidification and refrigeration module disposed within the housing. The cascade dehumidification and refrigeration module includes a primary dehumidification chiller 121 and a secondary dehumidification chiller unit sequentially arranged along the nitrogen flow direction on the nitrogen flow pipeline 11. The primary dehumidification chiller 121 is used for primary condensation and dehumidification of the returning nitrogen. The secondary dehumidification chiller unit includes at least two secondary dehumidification chillers 1221 arranged in parallel. One of the secondary dehumidification chillers 1221 is selectively connected to the primary dehumidification chiller 121 to perform secondary condensation and dehumidification on the intermediate nitrogen formed after primary condensation and dehumidification through the selected secondary dehumidification chiller 1221. It should be noted that in this embodiment, the dry nitrogen obtained after secondary condensation and dehumidification can basically meet the dryness and temperature requirements and can be directly discharged from the nitrogen flow pipeline 11 and flow to the end-use equipment for use.

[0030] The refrigeration-side circulating flow module 2 includes a refrigerant flow pipeline 21, and a compressor 22 and a condenser 23 arranged sequentially along the refrigerant flow direction on the refrigerant flow pipeline 21. The liquid supply end and the gas return end of the refrigerant flow pipeline 21 are respectively connected to the refrigerant passage of the first-stage dehydration chiller 121 and the refrigerant passage of the second-stage dehydration chiller 1221. Refrigerant circulates in the refrigerant flow pipeline 21 and is used to condense the return nitrogen and intermediate nitrogen.

[0031] The defrosting control module 3 includes a defrosting bypass pipe 31 and a nitrogen on / off valve 32. The inlet of the defrosting bypass pipe 31 is connected to the refrigerant flow pipe 21 between the exhaust port of the compressor 22 and the condenser 23. The outlet of the defrosting bypass pipe 31 is connected to the refrigerant channel inlet of each secondary dehydration chiller 1221. The nitrogen on / off valve 32 is set one-to-one with the secondary dehydration chiller 1221.

[0032] The refrigerant passage inlet of each secondary dehydration chiller 1221 can be selectively connected to the refrigerant circulation pipeline 21 or the defrost bypass pipeline 31, and when the secondary dehydration chiller 1221 is connected to the defrost bypass pipeline 31, the corresponding nitrogen on / off valve 32 is closed.

[0033] With the above configuration, the return nitrogen from the gas-consuming terminal equipment can first enter the primary dehumidification chiller 121 inside the casing, where most of the water vapor is condensed and precipitated through preliminary cooling. Then, it enters a selected secondary dehumidification chiller 1221 in the secondary dehumidification chiller unit for deep condensation and cooling, allowing the nitrogen to be cooled to the target temperature in one step. The resulting dry nitrogen can be directly discharged from the casing and re-enter the gas-consuming terminal equipment (not shown in the figure). By setting up a tiered dehumidification and cooling module, it is possible to prevent return nitrogen containing moisture from directly entering the secondary dehumidification chiller 1221 used for deep cooling, thereby preventing ice buildup on the heat exchange tube walls of the secondary dehumidification chiller 1221, mitigating the dramatic increase in wind resistance, and reducing maintenance frequency and costs. Furthermore, since both the primary and secondary dehumidification chillers 121 and 1221 are integrated into the casing, space is saved, and the cooling loss of nitrogen in the nitrogen flow pipeline 11 is reduced, ensuring that the dry nitrogen entering the gas-consuming terminal equipment can be stably maintained at the target temperature.

[0034] In addition, by setting up a defrosting control module 3, this embodiment can achieve continuous and uninterrupted operation of the system by selecting different secondary dehydration chillers 1221. On the other hand, for secondary dehydration chillers 1221 that are disconnected from the nitrogen flow pipeline 11 and need to be defrosted, the high-temperature refrigerant vapor discharged from the exhaust port of the compressor 22 can be used to defrost them. Compared with the commonly used electric heating defrosting method, it has lower energy consumption, higher safety, and can also avoid the situation where the system must stop production during defrosting.

[0035] refer to Figure 1As shown, in this embodiment, the secondary dehydration refrigeration unit includes two parallel-connected secondary dehydration refrigeration units 1221. Each secondary dehydration refrigeration unit 1221 has a working mode and a defrosting mode. In the working mode, the refrigerant channel inlet of the secondary dehydration refrigeration unit 1221 is connected to the refrigerant flow pipeline 21, and the corresponding nitrogen on / off valve 32 is opened. In the defrosting mode, the refrigerant channel inlet of the secondary dehydration refrigeration unit 1221 is connected to the defrosting bypass pipeline 31, and the corresponding nitrogen on / off valve 32 is closed. In practical use, the primary dehumidifying chiller 121 selects one of the secondary dehumidifying chillers 1221 for connection. At this time, the selected secondary dehumidifying chiller 1221 switches to working mode, allowing intermediate nitrogen to enter only this secondary dehumidifying chiller 1221 for secondary condensation and dehumidification. After a period of use, when the secondary dehumidifying chiller 1221 needs defrosting, the defrosting control module 3 controls the defrosting bypass pipe 31 to connect with the refrigerant channel of the secondary dehumidifying chiller 1221, while disconnecting the refrigerant flow pipe 21 from the refrigerant channel inlet and closing the corresponding nitrogen on / off valve 32, causing the secondary dehumidifying chiller 1221 to enter defrosting mode. At the same time, another parallel secondary dehumidifying chiller 1221 switches to working mode and controls the corresponding nitrogen on / off valve 32 to open, restoring the connection of the nitrogen flow pipe 11, allowing intermediate nitrogen to enter the other secondary dehumidifying chiller 1221 for continued secondary condensation and dehumidification. Therefore, through automatic switching between "one in use and one on standby," the system can operate under certain airflow conditions (e.g., 2000m³ / h). 3 It can run continuously and uninterruptedly ( / h) while effectively controlling system configuration costs.

[0036] For ease of explanation, in the following text, "one of the two secondary dehydration chillers 1221" will be defined as "two secondary dehydration chiller 1221A", and "the other two secondary dehydration chiller 1221" will be defined as "two secondary dehydration chiller 1221B".

[0037] In this embodiment, both the primary dehumidification chiller 121 and the secondary dehumidification chiller 1221 adopt finned heat exchangers. With this configuration, the maximum heat exchange area can be obtained within a unit volume, so that the cascade dehumidification and refrigeration module can achieve the required cooling and dehydration capacity with a small space occupation, and the overall structure is more compact.

[0038] In this embodiment, the primary dehydration chiller 121 is used to cool the reflux nitrogen to 5°C to 10°C. At this temperature, most of the water vapor in the intermediate nitrogen will condense into liquid water and be discharged. This step effectively reduces the workload of the subsequent secondary dehydration chiller 1221. The secondary dehydration chiller unit is used to cool the intermediate nitrogen to -30°C, so that the residual moisture can precipitate out in the form of frost and adhere to the fins of the secondary dehydration chiller 1221. This step can ensure that the obtained dry nitrogen is in an extremely dry state to meet the system's requirements for nitrogen dryness.

[0039] Combination Figure 2 , Figure 3 As shown, specifically in this embodiment, the defrosting bypass pipeline 31 includes a defrosting bypass main pipe 311, two defrosting bypass branch pipes 312, and two bypass control valves 313. One end of the defrosting bypass main pipe 311 is connected to the refrigerant flow pipeline 21 located between the exhaust port of the compressor 22 and the condenser 23, and the other end of the defrosting bypass main pipe 311 is connected to each defrosting bypass branch pipe 312. The defrosting bypass branch pipes 312 are connected one-to-one with the refrigerant channel inlet of each secondary water removal chiller 1221, and a bypass control valve 313 is provided on each defrosting bypass branch pipe 312. With the above settings, the high-temperature refrigerant vapor output from the exhaust port of compressor 22 enters the defrost bypass main pipe 311 and can only flow back into the refrigerant channel inlet along the defrost bypass branch pipe 312 corresponding to the secondary dewatering chiller 1221 in defrost mode. Defrosting of the secondary dewatering chiller 1221 is completed in the refrigerant channel, and the defrosting process of each secondary dewatering chiller 1221 can be independently controlled by the defrost control valve, achieving precise defrosting.

[0040] Furthermore, in this embodiment, the bypass control valve 313 is an electronic expansion valve, which enables the bypass control valve 313 to automatically open or close according to the control command sent by the defrost control module 3, thereby improving the timeliness of response. It can also precisely adjust the defrost process and efficiency by controlling the valve opening, which avoids the waste of high-temperature refrigerant vapor and ensures the defrost quality of the secondary dewatering refrigeration unit.

[0041] Furthermore, in this embodiment, the defrosting control module 3 also includes a central control unit and a monitoring unit. The central control unit is communicatively connected to the monitoring unit, the bypass control valve 313, and the nitrogen on / off valve 32. The monitoring unit is used to monitor the working status of each secondary dewatering chiller 1221 and transmit the monitoring signal to the central control unit. The central control unit controls the opening and closing of the bypass control valve 313 and the nitrogen on / off valve 32 according to the monitoring signal.

[0042] Thus, combined Figures 2 to 3As shown, the monitoring unit monitors the operating status of each secondary dehumidification chiller 1221 in real time and transmits the monitoring signals to the central control unit. The central control unit receives the signals and compares them with the preset frosting judgment threshold. When it determines that the frosting on the pipe wall surface of the secondary dehumidification chiller 1221A has reached the set level, it automatically issues a control command, simultaneously opening the bypass control valve 313 and closing the nitrogen on / off valve 32. Specifically, after the bypass control valve 313 opens, it guides high-temperature refrigerant vapor into the secondary dehumidification chiller 1221A for thermal defrosting. After the nitrogen on / off valve 32 closes, the intermediate nitrogen is diverted to the secondary dehumidification chiller 1221B in operating mode for continued secondary condensation and dehumidification. When the monitoring signal returns to the normal range, the central control unit automatically closes the bypass control valve 313, stopping the continued supply of high-temperature refrigerant vapor to the defrosting bypass pipeline 31. While waiting for the secondary dehumidification chiller 1221B to switch to defrost mode, the central control unit controls the secondary dehumidification chiller 1221A to switch to operating mode, and connects the primary dehumidification chiller 121 to the secondary dehumidification chiller 1221A to continue secondary condensation dehumidification. This achieves precise defrosting on demand, avoids energy waste, and significantly improves the operational stability and automation of the entire system.

[0043] refer to Figure 1 As shown, specifically, the monitoring unit includes a dew point sensor 331, a differential pressure sensor 332, and a temperature sensor 333. The dew point sensor 331 can be installed on the nitrogen flow line 11 and is used to monitor the humidity of the nitrogen output by each secondary dehumidification chiller 1221. The differential pressure sensor 332 can be installed on the nitrogen flow line 11 and is used to monitor the pressure difference between the section of the nitrogen flow line 11 before the primary dehumidification chiller 121 and the section of the nitrogen flow line 11 after each secondary dehumidification chiller 1221. The temperature sensor 333 can be installed on the nitrogen flow line 11 and is used to monitor the surface temperature of the condensation dehumidification pipe wall of each secondary dehumidification chiller 1221.

[0044] Taking the secondary dehumidification chiller 1221A as an example, when the dew point sensor 331 detects that the humidity of the dry nitrogen output by it exceeds the first preset threshold, it is determined that the dehumidification performance of the secondary dehumidification chiller 1221A has decreased due to frosting. When the differential pressure sensor 332 detects that the pressure difference exceeds the second preset threshold, it is determined that the condenser dehumidification pipe wall of the secondary dehumidification chiller 1221A has become blocked due to excessive pipe resistance caused by frosting. When the temperature sensor 333 detects that the surface temperature of the condenser dehumidification pipe wall exceeds the third preset threshold, it is determined that the heat exchange efficiency between the intermediate nitrogen and refrigerant in the secondary dehumidification chiller 1221A is insufficient due to frosting, and the temperature of the obtained dry nitrogen cannot reach the target temperature. When any of the above situations occur, it is determined that the secondary dehumidification chiller 1221A needs to be defrosted. Subsequently, the central control unit controls the corresponding bypass control valve 313 to open and the corresponding nitrogen on / off valve 32 to close, so as to defrost the secondary dehumidification chiller 1221A. This further enhances the accuracy and timeliness of the defrosting control module 3's judgment on the secondary dewatering chiller 1221, effectively avoiding invalid defrosting or defrosting leakage caused by misjudgment or failure of a single sensor, and improving the operational reliability of the system.

[0045] Specifically, in this embodiment, the refrigerant flow pipeline 21 further includes a liquid supply end flow main pipe 211, a liquid supply end flow branch pipe 212, a gas return end flow main pipe 213, a gas return end flow branch pipe 214, and a refrigerant control valve 215. One end of the liquid supply main pipe 211 is connected to the liquid outlet of the condenser 23, and the other end of the liquid supply main pipe 211 is connected to each liquid supply branch pipe 212. Each liquid supply branch pipe 212 is connected to the primary dehydration chiller 121 and each secondary dehydration chiller 1221, and each liquid supply branch pipe 212 is equipped with a refrigerant control valve 215. One end of the return gas main pipe 213 is connected to the gas inlet of the condenser 23, and the other end of the return gas main pipe 213 is connected to each return gas branch pipe 214 via the compressor 22. Each return gas branch pipe 214 is connected to the refrigerant channel outlet of each secondary dehydration chiller 1221. The central control unit is also in communication with each refrigerant control valve 215. When the bypass control valve 313 is open and the nitrogen on / off valve 32 is closed, the central control unit controls the corresponding refrigerant control valve 215 to close.

[0046] For example, in this embodiment, the refrigerant control valve 215 is installed on each liquid supply end flow branch pipe 212. In this configuration, each liquid supply end flow branch pipe 212 is connected to each dehydration chiller via an independent refrigerant control valve 215. The central control unit can independently control the refrigerant supply of the corresponding branch according to the frosting status of each secondary dehydration chiller 1221. When the secondary dehydration chiller 1221 in the working mode reaches the defrosting condition, the central control unit controls the refrigerant control valve 215 on its liquid supply end flow branch pipe 212 to close, while simultaneously opening its corresponding bypass control valve 313 and closing its corresponding nitrogen on / off valve 32. In this way, the high-temperature refrigerant vapor enters the secondary dewatering chiller 1221 to be defrosted directly through the defrosting bypass main pipe 311 and the defrosting bypass branch pipe 312 for thermal defrosting. Meanwhile, the liquid supply cut-off prevents the low-temperature liquid refrigerant from mixing into the high-temperature refrigerant vapor, and the nitrogen cut-off prevents the low-temperature nitrogen from continuously purging and carrying away heat. The three work together to form a "closed centralized defrosting" state, thereby greatly improving the defrosting speed and thermal efficiency.

[0047] Preferably, the nitrogen on / off valve 32 is a pneumatic switch butterfly valve; the bypass control valve 313 and the refrigerant control valve 215 are both electronic expansion valves.

[0048] In some embodiments, a dryer filter 216 is also provided on the liquid supply end flow main pipe 211. The dryer filter 216 is filled with a desiccant (such as molecular sieve, activated alumina or silica gel) and a filter screen assembly to filter solid impurities in the refrigerant, prevent pipeline blockage, and avoid a decrease in the heat exchange efficiency of return nitrogen or intermediate nitrogen. At the same time, it can also absorb trace amounts of moisture in the refrigerant to prevent moisture from reacting with the refrigerant to form acidic substances that corrode the pipeline and other components.

[0049] In this embodiment, a cooling water heat exchange channel 4 is also provided inside the condenser 23. The cooling water heat exchange channel 4 exchanges heat with the high-temperature refrigerant vapor in the condenser 23, so that the high-temperature refrigerant vapor cools down and condenses to form a liquid low-temperature refrigerant. The obtained liquid low-temperature refrigerant then flows through the liquid supply end flow main pipe 211 and the liquid supply end flow branch pipe 212 into the primary dehumidification chiller 121 and the selected secondary dehumidification chiller 1221, so as to condense and dehumidify the return nitrogen and intermediate nitrogen respectively.

[0050] In some embodiments, the cooling water heat exchange channel 4 is also equipped with a cooling water inlet temperature sensor 41, a cooling water outlet temperature sensor 42, and a flow switch 43. The cooling water inlet temperature and cooling water outlet temperature are detected by the cooling water inlet temperature sensor 41 and the cooling water outlet temperature sensor 42, respectively, to obtain the cooling water inlet and outlet temperature difference. The cooling water inlet and outlet temperature difference is used to determine whether the cooling degree of the refrigerant meets the standard based on whether the cooling water inlet and outlet temperature difference exceeds the cooling water temperature safety threshold. The cooling water inlet temperature sensor 41, the cooling water outlet temperature sensor 42, and the flow switch 43 can all be communicatively connected to the central control unit. When the cooling water inlet and outlet temperature difference is detected to exceed the cooling water temperature safety threshold, the monitoring signal is transmitted to the central control unit. The central control unit sends a control command to the flow switch 43 to adjust the opening of the flow switch 43, thereby adjusting the cooling water flow rate and velocity to adjust the cooling water cooling effect on the refrigerant so that the cooling water inlet and outlet temperature difference is restored to within the cooling water temperature safety threshold.

[0051] In some embodiments, a safety valve 231 is also provided on the condenser 23 so that when the internal pressure of the condenser 23 exceeds a preset safety threshold, the safety valve 231 can automatically open to release pressure, thereby protecting the condenser 23 and improving the safety of use.

[0052] Optionally, in this embodiment, the nitrogen circulation refrigeration system further includes a condensate collection module 5. The condensate collection module 5 includes a storage tank 51, two condensate delivery pipelines 52, and two condensate control valves 53. The inlet of the storage tank 51 is connected to both condensate delivery pipelines 52. The two condensate delivery pipelines 52 are respectively connected to the drain outlet of the primary dehydration chiller 121 and the drain outlet of each secondary dehydration chiller 1221. Each condensate delivery pipeline 52 is equipped with a condensate control valve 53.

[0053] This configuration enables the condensate collection module 5 to centrally collect the condensate generated by the primary dewatering chiller 121 during the cooling and dewatering process, and by the secondary dewatering chiller 1221 during the cooling, dewatering, and defrosting processes, so as to facilitate unified treatment or recycling and thus meet environmental emission requirements.

[0054] In some embodiments, a visible liquid level window 511 is provided on the storage tank 51, through which the liquid level information inside the storage tank 51 can be observed, thereby facilitating observation by the staff.

[0055] In some embodiments, the condensate collection module 5 further includes a level gauge 54, a drain pipe 55, and a drain control valve 56. The level gauge 54 is mounted on the storage tank 51 to detect the liquid level in the storage tank 51. The drain pipe 55 is connected to the drain port of the storage tank 51. The drain control valve 56 is mounted on the drain pipe 55 and is communicatively connected to the level gauge 54. Furthermore, the level gauge 54 can communicate with a central control unit, enabling it to send the detected liquid level information to the central control unit. The central control unit then controls the opening of the drain control valve 56 to automatically drain the collected liquid.

[0056] In some embodiments, the condensate collection module 5 also includes a drain pump 57 connected to the storage tank 51 to provide sufficient power for the discharge of the collected liquid, so that a large amount of defrost water can be discharged quickly, avoiding the risk of overflow caused by the liquid level rising in the storage tank 51.

[0057] In addition, the liquid level gauge 54 installed in the liquid storage tank 51 can monitor the liquid level in real time and transmit the signal to the central control unit. When the liquid level exceeds the preset threshold, it will automatically start the liquid drainage or issue an alarm, realizing fully automated management of condensate collection and discharge, and further improving the stability, safety and maintenance convenience of the nitrogen circulation refrigeration system in long-term operation.

[0058] This application also provides a nitrogen cryogenic pulverizing device, including a gas-using terminal device and the nitrogen circulation refrigeration system provided in the above embodiment. The nitrogen flow pipeline 11 in this system is cyclically connected to the gas-using terminal device, which can be a pulverizer. Through this arrangement, the return nitrogen output from the pulverizer can enter the nitrogen flow pipeline 11 for condensation and dehumidification, and the dry nitrogen discharged from the nitrogen flow pipeline 11 re-enters the pulverizer, thus realizing the recycling of nitrogen between the pulverizer and the nitrogen circulation refrigeration system. This embodiment, by configuring the aforementioned nitrogen circulation refrigeration system within the equipment, reduces maintenance frequency and costs, saves space, ensures continuous and uninterrupted operation of the pulverizer, and achieves lower energy consumption and higher safety during defrosting.

[0059] This application also provides a nitrogen treatment method, implemented using the nitrogen circulation refrigeration system provided in the above embodiments, and specifically includes the following operation steps: S1. Receive reflux nitrogen from the gas-consuming terminal equipment through nitrogen flow pipeline 11; Specifically, in this embodiment, the system is designed to handle an air volume of 2000 m³ / h. 3 / h, the target temperature for dry nitrogen is -30℃. Return nitrogen (temperature above 20℃ and containing trace amounts of moisture) from the end-use equipment enters the nitrogen flow line 11 through the return air inlet on the casing.

[0060] S2. Pass the reflux nitrogen gas into the first-stage dehumidification chiller 121 for primary condensation and dehumidification to form intermediate nitrogen gas. Specifically, in this embodiment, the reflux nitrogen enters the primary dehydration chiller 121 along the nitrogen flow pipeline 11. In the primary dehydration chiller 121, the reflux nitrogen is cooled to about 5°C to 10°C to form intermediate nitrogen. At this temperature, most of the water vapor in the reflux nitrogen can condense into liquid water and enter the storage tank 51 along the corresponding condensate conveying pipeline 52 for storage and collection.

[0061] S3. Switch one of the selected secondary dehumidification chillers 1221 to the working mode, and introduce intermediate nitrogen into the selected secondary dehumidification chiller 1221 for secondary condensation and dehumidification to obtain dry nitrogen. Specifically, in this embodiment, the intermediate nitrogen discharged from the primary dehumidification chiller 121 enters the selected secondary dehumidification chiller 1221 along the nitrogen flow pipeline 11, while another unselected secondary dehumidification chiller 1221 is in standby mode. The intermediate nitrogen is deeply cooled to -30°C in the selected secondary dehumidification chiller 1221, and the remaining moisture precipitates out in the form of frost and adheres to the condensation dehumidification coil. At this time, the intermediate nitrogen forms dry nitrogen and is in an extremely dry state.

[0062] S4. Drain the dry nitrogen from the nitrogen flow line 11 and let it flow back into the end-use equipment. Specifically, in this embodiment, the cooled -30°C dry nitrogen gas is directly drawn out from the air outlet of the casing at a speed of 2000m. 3 An air volume of / h is supplied to the gas-consuming terminal equipment to provide the necessary medium for its continued operation.

[0063] S5. When one of the selected secondary dehumidification chillers 1221 switches from the working mode to the defrosting mode, the refrigerant channel inlet of the selected secondary dehumidification chiller 1221 is connected to the defrosting bypass pipeline 31, and the corresponding nitrogen gas on / off valve 32 is closed. Then, another secondary dehumidification chiller 1221 is selected and switched to the working mode to continue to receive and perform secondary condensation and dehumidification of intermediate nitrogen gas.

[0064] Specifically, in this embodiment, the central control unit (e.g., a PLC) monitors parameters in real time across three dimensions: dew point, differential pressure, and temperature via a dew point sensor 331, a differential pressure sensor 332, and a temperature sensor 333. When any of the following conditions are met: the dew point sensor 331 detects that the humidity of the dry nitrogen it outputs exceeds a first preset threshold (e.g., <-25°C); the differential pressure sensor 332 detects that the pressure difference exceeds a second preset threshold (e.g., >800 Pa); or the temperature sensor 333 detects that the surface temperature of the condensation dehumidification pipe wall exceeds a third preset threshold (e.g., <-28°C), the central control unit determines that the secondary dehumidification chiller 1221A needs defrosting. At this time, the central control unit controls the nitrogen on / off valve 32 corresponding to the secondary dehumidification chiller 1221A to close, and controls the nitrogen on / off valve 32 corresponding to the secondary dehumidification chiller 1221B to open. The intermediate nitrogen flow direction is instantly switched to another secondary dehumidification chiller 1221 for deep cooling, and the system airflow is maintained at 2000 m³ / h. 3 The process continues uninterrupted. Subsequently, the central control unit opens the bypass control valve 313 connected to the secondary dehumidification chiller 1221A, allowing high-temperature refrigerant vapor (approximately 80℃-100℃) discharged from the compressor 22's exhaust port to flow into the refrigerant passage of the secondary dehumidification chiller 1221A. The high-temperature refrigerant vapor condenses and releases heat within the refrigerant passage, transferring the heat to the frost accumulation on the condensing dehumidification coil, causing it to melt rapidly. When the temperature sensor 333 detects that the temperature of the condensing dehumidification coil of the secondary dehumidification chiller 1221A has risen back to 15℃ and maintained for the set time, the bypass control valve 313 is closed, at which point the secondary dehumidification chiller 1221A enters standby mode. While waiting for the secondary dehumidification chiller 1221B to switch to defrosting mode, the secondary dehumidification chiller 1221A is switched back to operating mode and connected to the primary dehumidification chiller 121.

[0065] In summary, the nitrogen treatment method provided in this application can prevent backflow nitrogen containing moisture from directly entering the secondary dehydration chiller 1221 used for deep refrigeration, effectively reducing the increase in wind resistance, reducing maintenance frequency and costs, reducing cooling loss, and ensuring that the dry nitrogen entering the gas-using terminal equipment can be stably maintained at the target temperature. Moreover, by utilizing the defrosting control module 3, the secondary dehydration chiller 1221 that requires defrosting can be defrosted, resulting in lower energy consumption, while ensuring continuous and uninterrupted operation of the nitrogen refrigeration process, thereby achieving a safe, stable, and reliable nitrogen treatment process.

[0066] In the description of this specification, the terms "some embodiments," "other embodiments," "an embodiment," "example," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity, and those skilled in the art should consider the specification as a whole. The technical solutions in the various embodiments can also be appropriately combined to form other embodiments understood by those skilled in the art.

[0067] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A nitrogen-cycle refrigeration system, characterized in that, include: The nitrogen supply module (1) includes a housing, a nitrogen flow pipeline (11) and a cascade dehumidification and refrigeration module disposed within the housing; the cascade dehumidification and refrigeration module includes a primary dehumidification chiller (121) and a secondary dehumidification chiller unit disposed sequentially along the nitrogen flow direction on the nitrogen flow pipeline (11). The primary dehumidification chiller (121) is used to perform primary condensation and dehumidification on the return nitrogen. The secondary dehumidification chiller unit includes at least two secondary dehumidification chillers (1221) disposed in parallel. Each of the secondary dehumidification chillers (1221) is selectively connected to the primary dehumidification chiller (121) to perform secondary condensation and dehumidification on the intermediate nitrogen after primary condensation and dehumidification. The refrigeration-side circulating flow module (2) includes a refrigerant flow pipeline (21), and a compressor (22) and a condenser (23) sequentially arranged on the refrigerant flow pipeline (21) along the refrigerant flow direction. The liquid supply end and the gas return end of the refrigerant flow pipeline (21) are respectively connected to the refrigerant channel of the first-stage dehydration chiller (121) and the refrigerant channel of the second-stage dehydration chiller (1221). Refrigerant circulates in the refrigerant flow pipeline (21), and the refrigerant is used to condense the return nitrogen and the intermediate nitrogen. The defrosting control module (3) includes a defrosting bypass pipeline (31) and a nitrogen on / off valve (32). The inlet of the defrosting bypass pipeline (31) is connected to the refrigerant flow pipeline (21) located between the exhaust port of the compressor (22) and the condenser (23). The outlet of the defrosting bypass pipeline (31) is connected to the refrigerant channel inlet of each of the secondary dehydration chillers (1221). The nitrogen on / off valve (32) is set one-to-one with each of the secondary dehydration chillers (1221). The refrigerant channel inlet of each of the secondary dehydration chillers (1221) can be selectively connected to the refrigerant circulation pipeline (21) or the defrost bypass pipeline (31), and when the secondary dehydration chiller (1221) is connected to the defrost bypass pipeline (31), the corresponding nitrogen on / off valve (32) is closed.

2. The nitrogen cycle refrigeration system according to claim 1, characterized in that, The defrosting bypass pipeline (31) includes a defrosting bypass main pipe (311), at least two defrosting bypass branch pipes (312), and at least two bypass control valves (313). One end of the defrosting bypass main pipe (311) forms the inlet of the defrosting bypass pipeline (31), and the other end of the defrosting bypass main pipe (311) is connected to each of the defrosting bypass branch pipes (312). The defrosting bypass branch pipes (312) are connected one-to-one with the refrigerant channel inlet of each of the secondary water removal chillers (1221), and each of the defrosting bypass branch pipes (312) is provided with a bypass control valve (313).

3. The nitrogen cycle refrigeration system according to claim 2, characterized in that, The defrosting control module (3) also includes a central control unit and a monitoring unit. The central control unit is communicatively connected to the monitoring unit, the bypass control valve (313), and the nitrogen on / off valve (32). The monitoring unit is used to monitor the working status of each of the secondary dewatering chillers (1221) and transmit the monitoring signal to the central control unit. The central control unit controls the opening and closing of the bypass control valve (313) and the nitrogen on / off valve (32) according to the monitoring signal.

4. The nitrogen cycle refrigeration system according to claim 3, characterized in that, The monitoring unit includes a dew point sensor (331), a differential pressure sensor (332), and a temperature sensor (333). The dew point sensor (331) is used to monitor the humidity of the nitrogen output by each of the secondary dehydration chillers (1221). The differential pressure sensor (332) is used to monitor the pressure difference between the nitrogen flow pipeline (11) section before the primary dehydration chiller (121) and the nitrogen flow pipeline (11) section after each of the secondary dehydration chillers (1221). The temperature sensor (333) is used to monitor the surface temperature of the condensation dehumidification coil of each of the secondary dehydration chillers (1221). When the humidity exceeds the first preset threshold, and / or the pressure difference exceeds the second preset threshold, and / or the surface temperature exceeds the third preset threshold, the central control unit controls the corresponding bypass control valve (313) to open and the corresponding nitrogen on / off valve (32) to close.

5. The nitrogen cycle refrigeration system according to claim 4, characterized in that, The refrigerant flow pipeline (21) includes a liquid supply main pipe (211), a liquid supply branch pipe (212), a return gas main pipe (213), a return gas branch pipe (214), and a refrigerant control valve (215); one end of the liquid supply main pipe (211) is connected to the liquid outlet of the condenser (23), and the other end of the liquid supply main pipe (211) is connected to each of the liquid supply branch pipes (212); the liquid supply branch pipes (212) are connected to the first-stage dewatering chiller (121) and each of the refrigerant control valves (215). Each of the two-stage dehydration chillers (1221) is connected in a corresponding manner, and each of the liquid supply end flow branch pipes (212) is equipped with a refrigerant control valve (215); one end of the return gas end flow main pipe (213) is connected to the air inlet of the condenser (23), and the other end of the return gas end flow main pipe (213) is connected to each of the return gas end flow branch pipes (214) via the compressor (22); the return gas end flow branch pipes (214) are connected in a corresponding manner to the refrigerant channel outlet of each of the two-stage dehydration chillers (1221); The central control unit is also in communication with each of the refrigerant control valves (215); when the bypass control valve (313) is open and the nitrogen on / off valve (32) is closed, the central control unit controls the corresponding refrigerant control valve (215) to close.

6. The nitrogen cycle refrigeration system according to claim 1, characterized in that, The primary dehumidification chiller (121) is used to cool the reflux nitrogen to 5°C to 10°C for primary condensation dehumidification; the secondary dehumidification chiller (1221) is used to cool the intermediate nitrogen to -30°C for secondary condensation dehumidification.

7. The nitrogen cycle refrigeration system according to claim 1, characterized in that, It also includes a condensate collection module (5), which includes a storage tank (51), multiple condensate delivery pipelines (52) and multiple condensate control valves (53). The inlet of the storage tank (51) is connected to multiple condensate delivery pipelines (52), and the multiple condensate delivery pipelines (52) are respectively connected to the drain outlet of the primary water removal chiller (121) and the drain outlet of each secondary water removal chiller (1221); and each condensate delivery pipeline (52) is equipped with a condensate control valve (53).

8. The nitrogen cycle refrigeration system according to claim 7, characterized in that, The storage tank (51) is provided with a visible liquid level window (511); and / or, the condensate collection module (5) further includes a liquid level gauge (54), which is located on the storage tank (51); and / or, the condensate collection module (5) further includes a drain pump (57), which is connected to the storage tank (51) and is provided with a drain control valve (56) between it and the storage tank (51); and / or, the condensate control valve (53) and the drain control valve (56) are pneumatic angle seat valves.

9. The nitrogen cycle refrigeration system according to claim 5, characterized in that, Both the primary dehydration chiller (121) and the secondary dehydration chiller (1221) employ finned heat exchangers; and / or, the nitrogen on / off valve (32) is a pneumatic switch butterfly valve; and / or, the bypass control valve (313) is an electronic expansion valve; and / or, the refrigerant control valve (215) is an electronic expansion valve.

10. A nitrogen cryogenic pulverizing treatment device, characterized in that, The invention includes a pulverizer and a nitrogen circulation refrigeration system according to any one of claims 1-9, wherein the nitrogen circulation refrigeration system includes a nitrogen-side supply module (1), the nitrogen-side supply module (1) includes a nitrogen flow pipeline (11), and the nitrogen flow pipeline (11) is circulatedly connected to the pulverizer.

11. A nitrogen treatment method, characterized in that, The process is carried out using the nitrogen cryogenic pulverization equipment described in claim 10, and specifically includes the following operational steps: The nitrogen flow line (11) receives the return nitrogen from the crusher. The reflux nitrogen gas is passed into the first-stage dehumidification chiller (121) for one-time condensation and dehumidification to form intermediate nitrogen gas; The selected secondary dehumidification chiller (1221) is switched to working mode, and the intermediate nitrogen gas is introduced into the selected secondary dehumidification chiller (1221) for secondary condensation and dehumidification to obtain dry nitrogen gas; The dry nitrogen gas is discharged from the nitrogen gas flow pipeline (11) and flows into the pulverizer; When one of the selected secondary dehydration chillers (1221) switches from the working mode to the defrosting mode, the refrigerant channel inlet of the selected secondary dehydration chiller (1221) is connected to the defrosting bypass pipeline (31), and the corresponding nitrogen on / off valve (32) is closed. Then, another secondary dehydration chiller (1221) is selected and switched to the working mode to continue to receive and condense the intermediate nitrogen for secondary dehumidification.

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