Evaporative cooling type nitrogen cooling device for underground coal mine

Abstract

The application discloses an evaporative cooling type nitrogen cooling device for underground coal mine, and belongs to the technical field of cooling devices. A cooling system, an air flow and a spraying system are arranged in a device shell. The cooling system comprises an evaporative condenser, a screw refrigeration compressor, an oil separator, a liquid accumulator, a tube-shell evaporator and a three-phase asynchronous motor. The three-phase asynchronous motor is connected with the screw refrigeration compressor, the screw refrigeration compressor is connected with the oil separator, the oil separator is connected with the evaporative condenser, the evaporative condenser is connected with the liquid accumulator, the liquid accumulator is connected with the tube-shell evaporator, and the tube-shell evaporator is connected with the screw refrigeration compressor. The air flow and the spraying system comprise a mine fan, a mine water pump, a spraying water tank and a spraying pipe. The spraying water tank is connected with the mine water pump, the mine water pump is connected with the spraying pipe, and the blowing opening of the mine fan is aligned with the evaporative condenser. The application solves the shortcomings of independent air and water flow heat dissipation, realizes coupled sufficient heat exchange, and guarantees stable operation of the unit.

Description

Technical Field

[0001] This invention belongs to the technical field of cooling devices, and in particular relates to a nitrogen cooling device for heat dissipation using evaporative cooling in underground coal mines, specifically an evaporative cooling nitrogen cooling device for underground coal mines. Background Technology

[0002] Nitrogen cooling devices are nitrogen refrigeration equipment that applies refrigeration technology to underground coal mines, changing the complex and outdated process of supplying low-temperature nitrogen with liquid nitrogen. However, existing nitrogen cooling devices have two types of heat dissipation methods: water cooling and air cooling. The heat dissipation of water-cooled condensers is limited by the underground water source, water volume, and water quality. Although the initial heat dissipation effect is good, the water-cooled condenser needs to be descaled regularly in the later stages. Air-cooled condensers are easy to move and are not limited by the underground water source, but they require a large air volume, and heat accumulation in the vicinity of the unit after heat exchange is easy to cause, making them unsuitable for some high-temperature mines. Therefore, there is an urgent need to develop an evaporative cooling nitrogen cooling device for underground coal mines, which can achieve sufficient heat exchange through airflow, internal circulating water, and Freon, improve unit stability, reduce the airflow temperature in the vicinity of the unit, and continuously reduce the ambient temperature nitrogen to about -30°C before injecting it into the goaf, further improving the prevention of spontaneous combustion of coal in the goaf. Summary of the Invention

[0003] The present invention addresses the above-mentioned problems and overcomes the shortcomings of the prior art by providing an evaporative cooling nitrogen cooling device for underground coal mines.

[0004] To achieve the above objectives, the present invention adopts the following technical solution.

[0005] An evaporative cooling nitrogen cooling device for underground coal mines includes a housing. The housing houses a cooling system and an airflow and spray system, which work in conjunction with the cooling system. The cooling system includes an evaporative condenser, a screw compressor, an oil separator, a liquid receiver, a shell-and-tube evaporator, and a three-phase asynchronous motor. The power output of the three-phase asynchronous motor is connected to the screw compressor, which is connected to the oil separator. The oil separator is connected to the evaporative condenser, and the evaporative condenser is connected to the liquid receiver. The liquid storage tank is connected to the shell-and-tube evaporator, which is connected to the screw refrigeration compressor. The airflow and spray system includes a mine fan, a mine water pump, a spray water tank, and spray pipes. The airflow and spray system is used to cool the high-pressure refrigerant vapor entering the evaporative condenser through airflow and spray. One end of the mine water pump is connected to the spray water tank, and the other end is connected to the spray pipe. The spray pipe is equipped with nozzles located above the evaporative condenser, and the air outlet of the mine fan is directed towards the evaporative condenser.

[0006] As a preferred embodiment of the present invention, the device housing is further provided with a dual-circuit vacuum electromagnetic starter and a programmable control box. The dual-circuit vacuum electromagnetic starter is electrically connected to the mine fan and the mine water pump respectively. The mine fan and the mine water pump are also electrically connected to the programmable control box respectively. The dual-circuit vacuum electromagnetic starter and the programmable control box are used to control the starting and operation of the mine fan and the mine water pump.

[0007] As another preferred embodiment of the present invention, the screw refrigeration compressor is provided with a first energy regulating valve and a second energy regulating valve, both of which are electrically connected to a programmable control box.

[0008] As another preferred embodiment of the present invention, the screw refrigeration compressor is connected to an oil supply pipeline, and an oil supply solenoid valve is provided on the oil supply pipeline. The oil supply solenoid valve is electrically connected to the programmable control box.

[0009] As another preferred embodiment of the present invention, the liquid storage tank is a liquid storage tank with a built-in siphon function, an economizer solenoid valve is installed on the liquid storage tank, and a liquid supply solenoid valve is provided on the pipeline connecting the liquid storage tank and the shell-and-tube evaporator. Both the economizer solenoid valve and the liquid supply solenoid valve are electrically connected to the programmable control box.

[0010] As another preferred embodiment of the present invention, the spray water tank is equipped with a float level gauge and a mining electromagnetic water supply valve is installed on the spray water tank. The mining electromagnetic water supply valve is connected to an external water supply source, and both the float level gauge and the mining electromagnetic water supply valve are electrically connected to a programmable control box.

[0011] As another preferred embodiment of the present invention, the dual-circuit vacuum electromagnetic starter is a mining explosion-proof and intrinsically safe dual-circuit vacuum electromagnetic starter, the three-phase asynchronous motor is a coal mine explosion-proof three-phase asynchronous motor, the screw refrigeration compressor is a coal mine explosion-proof screw refrigeration compressor, and the programmable control box is a mining explosion-proof and intrinsically safe programmable control box.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] The evaporative cooling nitrogen cooling device for underground coal mines provided by this invention has the following significant advantages:

[0014] 1. The evaporative cooling nitrogen cooling device for underground coal mines provided by this invention solves the shortcomings of independent heat dissipation of air and water, realizes coupled and sufficient heat exchange, and ensures stable operation of the unit.

[0015] 2. The evaporative cooling nitrogen cooling device for underground coal mines provided by this invention has high heat transfer efficiency, good cooling effect, small heat transfer area of ​​the evaporative condenser, compact structure, and is convenient for underground movement and transportation.

[0016] 3. The evaporative cooling nitrogen cooling device for underground coal mines provided by this invention eliminates the need for a separate circulating water cooling system, effectively reducing one-time investment costs.

[0017] 4. The evaporative cooling nitrogen cooling device for underground coal mines provided by this invention offers high operational flexibility and good operability. The evaporative condenser primarily relies on the evaporation of the water film outside the tubes rather than on the rise in air temperature to remove heat from the tubes, making it insensitive to the air inlet temperature. Furthermore, the heat from the hot fluid inside the tubes is transferred to the water film through the tube wall, increasing the water film's temperature. Combined with the negative pressure created by the mine fan within the tube bundle, this further enhances the evaporation efficiency of the water film outside the tubes. Therefore, fluctuations in ambient temperature and humidity, as well as seasonal changes, have minimal impact on the cooling effect of the evaporative condenser. It is applicable to a wide range of regions and is not limited by underground water sources or air temperature. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the main structure of an evaporative cooling nitrogen cooling device for underground coal mines according to the present invention.

[0019] Figure 2 This is a top view schematic diagram of an evaporative cooling nitrogen cooling device for underground coal mines according to the present invention.

[0020] The markings in the diagram are as follows: 1 is a dual-circuit vacuum electromagnetic starter, 2 is a three-phase asynchronous motor, 3 is a screw refrigeration compressor, 4 is the first energy regulating valve, 5 is the second energy regulating valve, 6 is a programmable control box, 7 is an oil separator, 8 is an evaporative condenser, 9 is a spray pipe, 10 is a mining fan, 11 is a mining water pump, 12 is a float level gauge, 13 is a mining electromagnetic water supply valve, 14 is a spray water tank, 15 is an oil supply solenoid valve, 16 is a shell-and-tube evaporator, 17 is an economizer solenoid valve, 18 is a liquid receiver, and 19 is a liquid supply solenoid valve. Detailed Implementation

[0021] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0022] Please see Figure 1 and Figure 2This invention provides an evaporative cooling nitrogen cooling device for underground coal mines, comprising a housing, a cooling system, an airflow and spray system housed within the housing, the airflow and spray system working in conjunction with the cooling system; the cooling system includes an evaporative condenser 8, a screw compressor 3, an oil separator 7, a liquid receiver 18, a shell-and-tube evaporator 16, and a three-phase asynchronous motor 2, the power output of which is connected to the screw compressor 3, the screw compressor 3 connected to the oil separator 7, the oil separator 7 connected to the evaporative condenser 8, and the evaporative condenser 8 connected to the liquid receiver 18. The liquid receiver 18 is connected to the shell-and-tube evaporator 16, which is connected to the screw compressor 3. The airflow and spray system includes a mine fan 10, a mine water pump 11, a spray water tank 14, and a spray pipe 9. The airflow and spray system is used to cool the high-pressure refrigerant vapor entering the evaporative condenser 8 by airflow and spray. One end of the mine water pump 11 is connected to the spray water tank 14, and the other end is connected to the spray pipe 9. Nozzles are arranged on the spray pipe 9, and the nozzles are located above the evaporative condenser 8. The air outlet of the mine fan 10 is directed towards the evaporative condenser 8. The refrigerant absorbs heat from the secondary refrigerant (nitrogen) in the shell-and-tube evaporator 16 and is vaporized into low-temperature, low-pressure vapor. This vapor is drawn into the screw compressor 3, compressed, and heated and pressurized. The high-temperature, high-pressure gas then enters the evaporative condenser 8, where it transfers heat to the airflow and circulating water, condensing into a liquid. After cooling and depressurization, the liquid refrigerant re-enters the shell-and-tube evaporator 16 to continue absorbing heat from the secondary refrigerant (nitrogen), thus achieving nitrogen cooling.

[0023] Specifically, the device housing also includes a dual-circuit vacuum electromagnetic starter 1 and a programmable control box 6. The dual-circuit vacuum electromagnetic starter 1 is electrically connected to the mine fan 10 and the mine water pump 11, respectively. The mine fan 10 and the mine water pump 11 are also electrically connected to the programmable control box 6. The dual-circuit vacuum electromagnetic starter 1 and the programmable control box 6 are used to control the starting and operation of the mine fan 10 and the mine water pump 11. The screw refrigeration compressor 3 is equipped with a first energy regulating valve 4 and a second energy regulating valve 5, both of which are electrically connected to the programmable control box 6. The screw refrigeration compressor 3 is connected to an oil supply pipeline. An oil supply solenoid valve 15 is installed on the oil supply pipeline, and the oil supply solenoid valve 15 is electrically connected to the programmable control box 6; the liquid storage tank 18 is a liquid storage tank with a self-siphon function, and an economizer solenoid valve 17 is installed on the liquid storage tank 18. A liquid supply solenoid valve 19 is installed on the pipeline connecting the liquid storage tank 18 and the shell-and-tube evaporator 16. Both the economizer solenoid valve 17 and the liquid supply solenoid valve 19 are electrically connected to the programmable control box 6; a float level gauge 12 is installed in the spray water tank 14, and a mining electromagnetic water supply valve 13 is installed on the spray water tank 14. The mining electromagnetic water supply valve 13 is connected to an external water supply source. Both the float level gauge 12 and the mining electromagnetic water supply valve 13 are electrically connected to the programmable control box 6.

[0024] As a preferred embodiment of the present invention, the dual-circuit vacuum electromagnetic starter 1 is a mining explosion-proof and intrinsically safe dual-circuit vacuum electromagnetic starter, the three-phase asynchronous motor 2 is a coal mine underground explosion-proof three-phase asynchronous motor, the screw refrigeration compressor 3 is a coal mine underground explosion-proof screw refrigeration compressor, and the programmable control box 6 is a mining explosion-proof and intrinsically safe programmable control box.

[0025] The following describes the three operating modes of this invention in conjunction with the technical solution and accompanying drawings:

[0026] The first operating mode: When the nitrogen flow reaches 100% of the rated cooling flow, the screw refrigeration compressor 3 and the power output end of the three-phase asynchronous motor 2 are connected through a concentric shaft. The screw refrigeration compressor 3 is connected to the oil separator 7 through a connecting pipe. The oil separator 7 is connected to the evaporative condenser 8 through a connecting pipe. The evaporative condenser 8 is connected to the liquid receiver 18. The liquid receiver 18 is connected to the shell-and-tube evaporator 16. The shell-and-tube evaporator 16 is connected to the screw refrigeration compressor 3, forming a Freon circulation system in the cooling system. Room temperature nitrogen enters the shell-and-tube evaporator 16 to achieve continuous nitrogen cooling. In the cooling system, the screw compressor 3, driven by the three-phase asynchronous motor 2, compresses the refrigerant. The high-pressure refrigerant vapor compressed by the screw compressor 3 enters the oil separator 7 to achieve oil-gas separation and then enters the evaporative condenser 8. In the evaporative condenser 8, the refrigerant vapor is cooled by airflow and spray water, and condenses into high-pressure liquid refrigerant, which enters the liquid receiver 18. Then, the pressure is reduced by the throttling of the cooling system, and the pressure drops rapidly. It then enters the shell-and-tube evaporator 16 of the cooling system. The liquid refrigerant evaporates in the shell-and-tube evaporator 16 of the cooling system and absorbs heat from the room-temperature nitrogen gas through the tube wall, rapidly evaporating into gas and entering the screw compressor 3. The cycle continues. Under the continuous operation of the cooling system, the room-temperature nitrogen gas is cooled to about -30°C.

[0027] Under 100% operating conditions, and with the intelligent control of the dual-circuit vacuum electromagnetic starter 1 and the programmable control box 6, the mine fan 10 and the mine water pump 11 are first turned on to ensure that the airflow and the spray pipes 9 of the spray system can achieve normal operation of the heat dissipation system of the evaporative condenser 8. During this period, the float level gauge 12 in the spray water tank 14 monitors the water level. When the water level reaches the minimum level of the internal water circulation, the mine electromagnetic water supply valve 13 is opened to replenish water. After the heat dissipation system is running normally, the oil supply solenoid valve 15 is opened to supply oil to the screw refrigeration compressor 3. Driven by the three-phase asynchronous motor 2, the screw refrigeration compressor 3 is turned on, and the liquid supply solenoid valve 19, the first energy regulating valve 4, the economizer solenoid valve 17, and the second energy regulating valve 5 are opened in sequence. The unit reaches full load and runs continuously, continuously cooling the room temperature nitrogen to -30℃.

[0028] The second operating mode: When the nitrogen flow rate is 75% of the rated cooling flow rate, the screw refrigeration compressor 3 is connected to the three-phase asynchronous motor 2 through a concentric shaft. The screw refrigeration compressor 3 is connected to the oil separator 7 through a connecting pipe. The oil separator 7 is connected to the evaporative condenser 8 through a connecting pipe. The evaporative condenser 8 is connected to the liquid receiver 18. The liquid receiver 18 is connected to the shell-and-tube evaporator 16. The shell-and-tube evaporator 16 is connected to the screw refrigeration compressor 3, forming a Freon circulation system in the cooling system. Room temperature nitrogen enters the shell-and-tube evaporator 16 to achieve continuous nitrogen cooling. In the cooling system, the screw compressor 3, driven by the three-phase asynchronous motor 2, compresses the refrigerant. The high-pressure refrigerant vapor compressed by the screw compressor 3 enters the oil separator 7 to achieve oil-gas separation and then enters the evaporative condenser 8. In the evaporative condenser 8, the refrigerant vapor is cooled by airflow and spray water, and condenses into high-pressure liquid refrigerant, which enters the liquid receiver 18. Then, the pressure is reduced by the throttling of the cooling system, and the pressure drops rapidly. It then enters the plate-type shell-and-tube evaporator 16 of the cooling system. The liquid refrigerant evaporates in the shell-and-tube evaporator 16 and absorbs heat from the room-temperature nitrogen through the tube wall, rapidly evaporating into gas and entering the screw compressor 3. The cycle continues. Under the continuous operation of the cooling system, the room-temperature nitrogen is cooled to about -30°C.

[0029] Under 100% operating conditions, and with the intelligent control of the dual-circuit vacuum electromagnetic starter 1 and programmable control box 6, the mine fan 10 and mine water pump 11 are first turned on to ensure that the airflow and spray system can achieve normal operation of the heat dissipation system of the evaporative condenser 8. During this period, the float level gauge 12 in the spray water tank 14 monitors the water level. When the internal water circulation reaches the minimum water level, the mine electromagnetic water supply valve 13 is opened to replenish water. After the heat dissipation system is running normally, the oil supply solenoid valve 15 is opened to supply oil to the refrigeration compressor. Driven by the three-phase asynchronous motor 2, the screw refrigeration compressor 3 is turned on. The liquid supply solenoid valve 19, the first energy regulating valve 4, and the economizer solenoid valve 17 are opened in sequence. The unit reaches 75% load and runs continuously, continuously cooling the room temperature nitrogen to -30℃.

[0030] The third operating mode: When the internal circulating water cannot be replenished (when the heat exhaust system is only cooled by airflow), the nitrogen cooling device operates at 50% load. The screw refrigeration compressor 3 is connected to the three-phase asynchronous motor 2 through a concentric shaft. The screw refrigeration compressor 3 is connected to the oil separator 7 through a connecting pipe. The oil separator 7 is connected to the evaporative condenser 8 through a connecting pipe. The evaporative condenser 8 is connected to the liquid receiver 18. The liquid receiver 18 is connected to the shell-and-tube evaporator 16. The shell-and-tube evaporator 16 is connected to the screw refrigeration compressor 3, forming the Freon circulation system in the cooling system. Room temperature nitrogen enters the shell-and-tube evaporator 16 to achieve continuous nitrogen cooling. In the cooling system, the screw compressor 3, driven by the three-phase asynchronous motor 2, compresses the refrigerant. The high-pressure refrigerant vapor compressed by the screw compressor 3 enters the oil separator 7 to achieve oil-gas separation and then enters the evaporative condenser 8. In the evaporative condenser 8, the refrigerant vapor is cooled by airflow and spray water, and condenses into high-pressure liquid refrigerant, which enters the liquid receiver 18. Then, the pressure is reduced by the throttling of the cooling system, and the pressure drops rapidly. It then enters the plate-type shell-and-tube evaporator 16 of the cooling system. The liquid refrigerant evaporates in the shell-and-tube evaporator 16 and absorbs heat from the room-temperature nitrogen through the tube wall, rapidly evaporating into gas and entering the screw compressor 3. The cycle continues. Under the continuous operation of the cooling system, the room-temperature nitrogen is cooled to a low-temperature state.

[0031] Under the condition of severe internal circulating water shortage, the device, under the intelligent control of the dual-circuit vacuum electromagnetic starter 1 and programmable control box 6, first starts the mine fan 10 to ensure the airflow to achieve normal operation of the heat dissipation system of the evaporative condenser 8; after the heat dissipation system is running normally, the oil supply solenoid valve 15 is opened to supply oil to the refrigeration compressor. Driven by the three-phase asynchronous motor 2, the screw refrigeration compressor 3 is started and the liquid supply solenoid valve 19 is opened. The unit can achieve continuous operation at 50% load. The unit operation problem is completely solved by airflow heat dissipation alone, and the room temperature nitrogen can be continuously cooled to a low temperature condition.

[0032] This invention relates to an evaporative cooling nitrogen cooling device for underground coal mines. Through its evaporative cooling configuration, it not only ensures continuous operation of the unit while maintaining heat dissipation through coupled airflow and internal circulating water, continuously producing nitrogen at -30°C, but also guarantees low-load operation and stability even in cases of severe water shortage (no internal circulating water). The screw compressor 3, along with the first and second energy regulating valves 4 and 5, allows for energy regulation at 50%, 75%, and 100% to meet various underground operating conditions. Furthermore, the combination of a mine fan 10 and an evaporative condenser 8... Based on the sufficient heat exchange between the airflow and the Freon in the evaporative condenser 8, the internal circulating water system provides auxiliary cooling by spraying water onto the top of the evaporative condenser 8. This utilizes water to provide sufficient auxiliary heat exchange for the Freon in the evaporative condenser 8, ensuring that the exhaust temperature remains within the stable operating range of the unit. Through the configuration of the spray water tank 14, spray pipe 9, float level gauge 12, and mining electromagnetic water supply valve 13, water is replenished by opening the mining electromagnetic water supply valve 13 when the internal circulating water reaches the minimum level, improving system stability. The liquid receiver 18 is equipped with a built-in siphon function, which can realize the function of the refrigeration oil pump, eliminating the need for a separate oil pump.

[0033] In summary, the evaporative cooling nitrogen cooling device for underground coal mines provided by this invention overcomes the shortcomings of independent air and water flow, achieving coupled and sufficient heat exchange to ensure stable unit operation. This evaporative cooling nitrogen cooling device for underground coal mines also features high heat transfer efficiency, good cooling effect, a small heat transfer area in the evaporative condenser 8, and a compact structure, facilitating underground movement and transportation. Furthermore, this evaporative cooling nitrogen cooling device for underground coal mines eliminates the need for a separate circulating water cooling system, effectively reducing initial investment costs. This type of evaporative cooling nitrogen cooling device for underground coal mines offers high operational flexibility and ease of use. The evaporative condenser 8 primarily relies on the evaporation of the water film outside the tubes rather than the rise in air temperature to remove heat from the tubes, making it insensitive to air inlet temperature. Furthermore, the heat from the hot fluid inside the tubes is transferred to the water film through the tube wall, increasing the water film's temperature. Additionally, the negative pressure created by the mine fan 10 within the tube bundle further enhances the evaporation efficiency of the water film outside the tubes. Therefore, fluctuations in ambient temperature and humidity, as well as seasonal changes, have minimal impact on the cooling effect of the evaporative condenser. It is applicable to a wide range of regions and is not limited by underground water sources or air temperature.

[0034] It is understood that, although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An evaporative cooling nitrogen cooling device for underground coal mines, characterized in that, The device includes a housing, within which a cooling system and an airflow and spray system are installed. The airflow and spray system works in conjunction with the cooling system. The cooling system includes an evaporative condenser, a screw compressor, an oil separator, a liquid receiver, a shell-and-tube evaporator, and a three-phase asynchronous motor. The power output of the three-phase asynchronous motor is connected to the screw compressor, which is connected to the oil separator. The oil separator is connected to the evaporative condenser, which is connected to the liquid receiver. The liquid receiver is connected to... A shell-and-tube evaporator is connected to a screw refrigeration compressor. The airflow and spray system includes a mining fan, a mining water pump, a spray water tank, and spray pipes. The airflow and spray system is used to cool the high-pressure refrigerant vapor entering the evaporative condenser through airflow and spray. One end of the mining water pump is connected to the spray water tank, and the other end of the mining water pump is connected to the spray pipes. Nozzles are arranged on the spray pipes, and the nozzles are located above the evaporative condenser. The air outlet of the mining fan is directed towards the evaporative condenser. In the cooling system, the screw compressor, driven by a three-phase asynchronous motor, compresses the refrigerant. The high-pressure refrigerant vapor compressed by the screw compressor enters the oil separator for oil-gas separation and then enters the evaporative condenser. In the evaporative condenser, the refrigerant vapor is cooled by airflow and spray water, condensing into high-pressure liquid refrigerant which enters the receiver. The liquid refrigerant then passes through the cooling system for throttling and pressure reduction, causing the pressure to drop rapidly. It then enters the shell-and-tube evaporator of the cooling system. The liquid refrigerant evaporates in the shell-and-tube evaporator and rapidly evaporates into gas by absorbing heat from the room-temperature nitrogen through the tube wall. It then enters the screw compressor and continues to circulate. Under the continuous circulation of the cooling system, the room-temperature nitrogen is cooled to -30°C. When the nitrogen flow reaches 100% of the rated cooling flow, under the intelligent control of the dual-circuit vacuum electromagnetic starter and programmable control box, the mine fan and mine water pump are first turned on to ensure that the airflow and the spray pipes of the spray system can achieve normal operation of the heat dissipation system of the evaporative condenser. During this period, the float level gauge in the spray water tank monitors the water level. When the water level reaches the minimum level of the internal water circulation, the mine electromagnetic water supply valve is opened to replenish water. After the heat dissipation system is running normally, the oil supply solenoid valve is opened to supply oil to the screw refrigeration compressor. Driven by the three-phase asynchronous motor, the screw refrigeration compressor is turned on, and the liquid supply solenoid valve, the first energy regulating valve, the economizer solenoid valve, and the second energy regulating valve are opened in sequence. The unit reaches full load and runs continuously, continuously cooling the room temperature nitrogen to -30℃. When the nitrogen flow rate is 75% of the rated cooling flow rate, under the intelligent control of the dual-circuit vacuum electromagnetic starter and programmable control box, the mine fan and mine water pump are first turned on to ensure that the airflow and spray system can achieve normal operation of the heat dissipation system of the evaporative condenser. During this period, the float level gauge in the spray water tank monitors the water level. When the internal water circulation reaches the minimum water level, the mine electromagnetic water replenishment valve is opened to replenish water. After the heat dissipation system is running normally, the oil supply solenoid valve is opened to supply oil to the refrigeration compressor. Driven by the three-phase asynchronous motor, the screw refrigeration compressor is turned on. The liquid supply solenoid valve, the first energy regulating valve, and the economizer solenoid valve are opened in sequence. The unit reaches 75% load and runs continuously, continuously cooling the room temperature nitrogen to -30℃. When the internal circulating water cannot be replenished, the nitrogen cooling device operates at 50% load. Under the intelligent control of the dual-circuit vacuum electromagnetic starter and programmable control box, the mine fan is first turned on to ensure that the airflow can achieve normal operation of the heat dissipation system of the evaporative condenser. After the heat dissipation system is running normally, the oil supply solenoid valve is turned on to supply oil to the refrigeration compressor. Driven by the three-phase asynchronous motor, the screw refrigeration compressor is turned on and the liquid supply solenoid valve is turned on. The unit achieves continuous operation at 50% load. The unit operation problem is completely solved by airflow heat dissipation alone, and the ambient temperature nitrogen is continuously cooled to a low temperature condition.

2. The evaporative cooling nitrogen cooling device for underground coal mines according to claim 1, characterized in that, The device housing also includes a dual-circuit vacuum electromagnetic starter and a programmable control box. The dual-circuit vacuum electromagnetic starter is electrically connected to the mine fan and the mine water pump, respectively. The mine fan and the mine water pump are also electrically connected to the programmable control box. The dual-circuit vacuum electromagnetic starter and the programmable control box are used to control the start-up and operation of the mine fan and the mine water pump.

3. The evaporative cooling nitrogen cooling device for underground coal mines according to claim 2, characterized in that, The screw-type refrigeration compressor is equipped with a first energy regulating valve and a second energy regulating valve, both of which are electrically connected to the programmable control box.

4. The evaporative cooling nitrogen cooling device for underground coal mines according to claim 2, characterized in that, The screw refrigeration compressor is connected to an oil supply line, and an oil supply solenoid valve is installed on the oil supply line. The oil supply solenoid valve is electrically connected to the programmable control box.

5. The evaporative cooling nitrogen cooling device for underground coal mines according to claim 2, characterized in that, The liquid receiver is a liquid receiver with a built-in siphon function. An economizer solenoid valve is installed on the liquid receiver. A liquid supply solenoid valve is installed on the pipeline connecting the liquid receiver to the shell-and-tube evaporator. Both the economizer solenoid valve and the liquid supply solenoid valve are electrically connected to the programmable control box.

6. The evaporative cooling nitrogen cooling device for underground coal mines according to claim 2, characterized in that, The spray tank is equipped with a float level gauge and a mining electromagnetic water supply valve. The mining electromagnetic water supply valve is connected to an external water supply source. Both the float level gauge and the mining electromagnetic water supply valve are electrically connected to the programmable control box.

7. The evaporative cooling nitrogen cooling device for underground coal mines according to claim 2, characterized in that, The dual-circuit vacuum electromagnetic starter is a mining-grade explosion-proof and intrinsically safe dual-circuit vacuum electromagnetic starter; the three-phase asynchronous motor is a coal mine-grade explosion-proof three-phase asynchronous motor; the screw refrigeration compressor is a coal mine-grade explosion-proof screw refrigeration compressor; and the programmable control box is a mining-grade explosion-proof and intrinsically safe programmable control box.

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