Liquid nitrogen and liquid carbon dioxide mixing device

Abstract

The invention discloses a liquid nitrogen and liquid carbon dioxide mixing device which comprises a tank body, a liquid carbon dioxide injection assembly, a nitrogen injection assembly, a liquid nitrogen injection pipe and a monitoring assembly, and the output end of the liquid carbon dioxide injection assembly and the output end of the nitrogen injection assembly are both inserted into the top of the tank body; the liquid carbon dioxide injection assembly is used for evenly injecting liquid carbon dioxide liquid drops into the tank body, the liquid nitrogen injection pipe is assembled on the lower side of the outer surface of the tank body in an inserted mode, the monitoring assembly is assembled on the outer surface of the tank body, an adjusting valve is assembled at the lower end of the tank body, and an output pipe is assembled at the lower end of the adjusting valve. The temperature difference between the upper part and the lower part is realized and a certain pressure is kept in the tank body, and liquid carbon dioxide is injected by adopting a dot-matrix thin tube, so that the carbon dioxide in the tank body is injected from the top in a raining manner and is frozen into granular, powdery or snowflake-shaped dry ice at the lower part of the tank body, and the liquid carbon dioxide is prevented from being frozen and blocked at an inlet of the tank body.

Description

Technical Field

[0001] The invention belongs to the technical field of coal production, and in particular provides a device for mixing liquid nitrogen and liquid carbon dioxide. Background Art

[0002] Spontaneous combustion of coal is one of the major disasters in my country's mines. Mines threatened by spontaneous combustion account for about 70% of the total number of mines. Coal mine fire accidents not only produce a large amount of toxic and harmful gases, seriously threatening the lives of underground workers, but also secondary disasters such as coal dust and gas explosions caused by fire are even more serious.

[0003] Inert gas fire prevention and extinguishing is one of the main means of fire prevention and extinguishing. Low-temperature inert gas not only has a suffocating effect, but also produces a good cooling and fire prevention and extinguishing effect.

[0004] Existing inert gas fire prevention and extinguishing mainly uses low-temperature carbon dioxide, nitrogen and other inert gases. The inert gas is injected into the high-temperature area of ​​the goaf. Within the diffusion range of the inert gas, it can isolate oxygen and reduce the temperature of the fire area, thereby achieving the purpose of fire extinguishing.

[0005] Due to the limitations of the conditions at the fire-fighting site, the conditions for preparing low-temperature inert gas are generally not available on site. Liquid carbon dioxide or liquid nitrogen can only be purchased from power plants, coal chemical companies and other enterprises, and then transported to the fire-fighting site by tank trucks or tank trucks, vaporized into low-temperature gas and injected into the goaf.

[0006] Problems with existing technologies:

[0007] (1) After the liquid inert gas is vaporized, its cooling capacity for the fire area is greatly reduced, and its fire extinguishing capacity is weakened. Since the liquid inert gas is directly injected into the goaf, the liquid inert gas will expand rapidly from liquid to gas due to the sharp drop in pressure at the release port. The temperature at the release port drops sharply due to the work of expansion, and it is easy to freeze the liquid carbon dioxide at the release port into dry ice, or freeze the liquid nitrogen, causing the release port to be blocked. Therefore, the process method of vaporization first and then injection is generally adopted, and the latent heat of vaporization cannot be used to extinguish the fire.

[0008] (2) A large amount of electrical energy is wasted. The preparation of liquid carbon dioxide and nitrogen requires the use of cryogenic technology, which requires a large amount of electricity. To convert the liquid into gas, electric heating is required for vaporization, which also consumes a lot of electrical energy. Summary of the invention

[0009] In order to solve the above problems, the present invention provides a liquid nitrogen and liquid carbon dioxide mixing device, which vaporizes liquid nitrogen into nitrogen gas, and uses the heat absorbed by the liquid nitrogen during vaporization to convert liquid carbon dioxide into granular or snowflake-shaped dry ice, and uses the vaporized nitrogen to transport the dry ice to the high-temperature point in the goaf. The dry ice is heated and vaporized in the goaf, which fully utilizes the latent heat of phase change to extinguish the high-temperature point while reducing power consumption.

[0010] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a liquid nitrogen and liquid carbon dioxide mixing device, comprising a tank body, a liquid carbon dioxide injection component, a nitrogen injection component, a liquid nitrogen injection pipe and a monitoring component, the output ends of the liquid carbon dioxide injection component and the nitrogen injection component are both plugged into the top of the tank body, the liquid carbon dioxide injection component is used to uniformly inject liquid carbon dioxide droplets into the tank body, the liquid nitrogen injection pipe is plugged and assembled on the lower side of the outer surface of the tank body, the monitoring component is assembled on the outer surface of the tank body, and the monitoring component is used to monitor the temperature and pressure in the tank body, the lower end of the tank body is equipped with a regulating valve, and the lower end of the regulating valve is equipped with an output pipe.

[0011] Furthermore, the top of the tank body is an arc cover structure, the middle part is a barrel-shaped structure, the bottom is a V-shaped structure, and the outer surface of the tank body is provided with a heat-insulating layer.

[0012] Furthermore, the liquid carbon dioxide injection assembly includes a liquid carbon dioxide delivery main pipeline, a liquid carbon dioxide delivery branch pipeline and a liquid carbon dioxide injection pipe. A plurality of the liquid carbon dioxide delivery branch pipelines are symmetrically installed on the front and rear sides of the liquid carbon dioxide delivery main pipeline. The liquid carbon dioxide injection pipe is evenly installed on the lower side of the outer surface of the liquid carbon dioxide delivery main pipeline and the liquid carbon dioxide delivery branch pipeline, and the liquid carbon dioxide injection pipe passes through the top of the tank body.

[0013] Furthermore, the diameter of the injection end of the liquid carbon dioxide delivery main pipeline is larger than the diameter of the tail end.

[0014] Furthermore, the liquid carbon dioxide injection tubes are thin tubes, and the liquid carbon dioxide injection tubes are evenly distributed in a square lattice.

[0015] Furthermore, the nitrogen injection assembly includes a nitrogen delivery pipeline and a nitrogen injection pipe, a plurality of the nitrogen injection pipes are evenly arranged on the lower side of the outer surface of the nitrogen delivery pipeline, and the nitrogen injection pipes penetrate the top of the tank body, and the nitrogen injection pipes and the liquid carbon dioxide injection pipes are staggered.

[0016] Furthermore, the monitoring component includes a first temperature sensor, a pressure sensor and a second temperature sensor, the first temperature sensor and the pressure sensor are both arranged on the upper side of the outer surface of the tank body, the second temperature sensor is arranged on the lower side of the outer surface of the tank body, the first temperature sensor is used to monitor the temperature of the upper area inside the tank body, the pressure sensor is used to monitor the pressure inside the tank body, and the second temperature sensor is used to monitor the temperature of the lower area inside the tank body.

[0017] Furthermore, an exhaust valve and a safety valve are provided on the top of the tank body.

[0018] The beneficial effects of using the present invention are:

[0019] 1. A temperature difference of high at the top and low at the bottom is achieved in the tank body, and a certain pressure is maintained. Liquid carbon dioxide is injected into the tank body by a dot matrix capillary tube, so that the carbon dioxide in the tank body is injected from the top in a rainy manner and frozen into granular, powdery or snowflake-like dry ice at the bottom of the tank body, and the freezing and blockage of liquid carbon dioxide at the entrance of the tank body is avoided.

[0020] 2. The temperature of the liquid nitrogen injection point in the lower part of the tank is low, which effectively prevents the liquid nitrogen from freezing and clogging at the tank entrance, and uses the low temperature of liquid nitrogen to quickly freeze the liquid carbon dioxide.

[0021] 3. Strong cooling capacity for goaf. The phase change heat absorption in liquid nitrogen and liquid carbon dioxide is fully retained, and a mixture of nitrogen and dry ice is injected into the goaf. Dry ice absorbs a large amount of heat when it vaporizes in the goaf, thus avoiding the loss of cold energy when it is injected into the goaf after vaporization.

[0022] 4. The gas has a better effect of suffocating fire in the goaf. After the nitrogen and dry ice mixture enters the goaf, the carbon dioxide has a high density and diffuses to the lower part of the goaf, while the nitrogen has a low density and diffuses to the higher part of the goaf, thus forming a three-dimensional diffusion in the goaf, overcoming the problem of limited diffusion direction of a single gas.

[0023] 5. Save a lot of heating and vaporization electricity. In the goaf, dry ice is heated and vaporized, making full use of the latent heat of phase change to extinguish the high-temperature points. Compared with the traditional method of vaporizing liquid carbon dioxide and liquid nitrogen by electric heating, it greatly reduces the consumption of electricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a front cross-sectional view of the mixing device of the present invention.

[0025] Figure 2 This is a bottom view of the liquid carbon dioxide injection assembly of the present invention.

[0026] The accompanying drawings include: 1. tank body, 2. liquid carbon dioxide injection assembly, 201. liquid carbon dioxide delivery main pipeline, 202. liquid carbon dioxide delivery branch pipeline, 203. liquid carbon dioxide injection pipe, 3. nitrogen injection assembly, 301. nitrogen delivery pipeline, 302. nitrogen injection pipe, 4. liquid nitrogen injection pipe, 5. regulating valve, 6. output pipe, 7. insulation layer, 8. exhaust valve, 9. safety valve, 10. first temperature sensor, 11. pressure sensor, 12. second temperature sensor. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Reference Figure 1 and Figure 2 A liquid nitrogen and liquid carbon dioxide mixing device comprises a tank body 1, a liquid carbon dioxide injection component 2, a nitrogen injection component 3, a liquid nitrogen injection pipe 4 and a monitoring component. The output ends of the liquid carbon dioxide injection component 2 and the nitrogen injection component 3 are both plugged into the top of the tank body 1. The liquid carbon dioxide injection component 2 is used to uniformly inject liquid carbon dioxide droplets into the tank body 1. The liquid nitrogen injection pipe 4 is plugged and assembled on the lower side of the outer surface of the tank body 1. The monitoring component is assembled on the outer surface of the tank body 1, and the monitoring component is used to monitor the temperature and pressure in the tank body. The lower end of the tank body 1 is equipped with a regulating valve 5, and the lower end of the regulating valve 5 is equipped with an output pipe 6.

[0029] Liquid carbon dioxide and liquid nitrogen undergo heat exchange and phase change in the tank body 1, and are eventually output and collected from the output pipe 6 in the form of a nitrogen and dry ice mixture, which is used to cool and extinguish fires at high-temperature points in the goaf.

[0030] The temperature and pressure information monitored by the monitoring component is used to control the injection amount of the nitrogen injection component 3 and the liquid nitrogen injection pipe 4 and the opening of the regulating valve 5 to ensure that the nitrogen and dry ice mixture is collected.

[0031] The output pipe 6 is used to transport the nitrogen and dry ice mixture out of the tank body 1, and the regulating valve 5 is used to control the pressure in the tank body 1 within a certain range. If the pressure in the tank body 1 is too low, the liquid nitrogen will freeze at the pipe mouth of the liquid nitrogen injection pipe 4, thereby causing insufficient delivery pressure. If the pressure is too high, it is easy to cause an accident.

[0032] Specifically, if Figure 1As shown, the top of the tank body 1 is an arc cover structure, the middle part is a barrel-shaped structure, the bottom is a V-shaped structure, and the outer surface of the tank body 1 is provided with a heat-insulating layer 7.

[0033] The arc cover structure on the top of the tank body 1 can effectively disperse the pressure and reduce local stress concentration, and the V-shaped structure at the bottom can effectively guide the dry ice and realize the smooth export of the nitrogen and dry ice mixture.

[0034] The thermal insulation layer 7 is made of thermal insulation material, and rock wool or polyurethane foam can be selected. Rock wool has good thermal insulation performance, and the thermal conductivity is 0.042-0.064W / m·K. It has good high temperature resistance and fire resistance, high chemical stability, is not easily affected by environmental factors and aged or damaged, has a long service life, and is suitable for the thermal insulation of carbon dioxide tanks under various working conditions;

[0035] Polyurethane foam has a closed-cell structure, good insulation effect, light weight, high specific strength, and easy construction. Polyurethane foam has a low thermal conductivity, which can effectively prevent the transfer of heat and keep the carbon dioxide tank at a stable temperature. In addition, it also has the characteristics of sound insulation, shock resistance, electrical insulation, heat resistance, cold resistance, and solvent resistance, and is suitable for tank insulation in a variety of temperature ranges.

[0036] Specifically, if Figure 2 As shown, the liquid carbon dioxide injection assembly 2 includes a liquid carbon dioxide delivery main pipeline 201, a liquid carbon dioxide delivery branch pipeline 202 and a liquid carbon dioxide injection pipe 203. A plurality of liquid carbon dioxide delivery branch pipelines 202 are symmetrically assembled on the front and rear sides of the liquid carbon dioxide delivery main pipeline 201. The liquid carbon dioxide injection pipe 203 is evenly assembled on the lower side of the outer surface of the liquid carbon dioxide delivery main pipeline 201 and the liquid carbon dioxide delivery branch pipeline 202, and the liquid carbon dioxide injection pipe 203 passes through the top of the tank body 1.

[0037] The portion of the liquid carbon dioxide delivery branch pipe 202 on the liquid carbon dioxide delivery main pipe 201 is in an arc shape corresponding to the arc cover structure of the tank body 1, and the liquid carbon dioxide delivery branch pipe 202 is also in an arc shape corresponding to the arc cover structure of the tank body 1, so that it can be matched and installed with the tank body 1 more smoothly.

[0038] Specifically, the diameter of the injection end of the liquid carbon dioxide delivery main pipeline 201 is larger than the diameter of the tail end, which improves the stability of the flow of liquid carbon dioxide in the liquid carbon dioxide delivery main pipeline 201 and the liquid carbon dioxide delivery branch pipeline 202, and ensures that each liquid carbon dioxide injection pipe 203 can stably and evenly flow out liquid carbon dioxide.

[0039] Specifically, if Figure 2As shown, the liquid carbon dioxide injection pipes 203 are thin tubes, and the liquid carbon dioxide injection pipes 203 are evenly distributed in a square lattice.

[0040] The liquid carbon dioxide injection pipe 203 is configured as a thin tube, and its specific diameter is set according to actual conditions, in order to allow the liquid carbon dioxide to flow out in the form of a thin stream. Under the acceleration of gravity, the thin stream will break into droplets in the tank body 1 and fall into the lower area of ​​the tank body 1.

[0041] The square dot matrix distribution allows the liquid carbon dioxide to fall in the form of rain, allowing it to be evenly cooled and eventually frozen into granular, powdery or snowflake-like dry ice.

[0042] Regarding the design of the liquid carbon dioxide injection assembly 2, the liquid carbon dioxide delivery branch pipeline 202 may also be set as a circular pipeline to form a plurality of concentric circular liquid carbon dioxide delivery branch pipelines 202, and a liquid carbon dioxide injection pipe 203 may be evenly arranged on each liquid carbon dioxide delivery branch pipeline 202 to achieve uniform injection of liquid carbon dioxide;

[0043] In addition, the liquid carbon dioxide delivery main pipeline 201 can be set in a spiral shape, the liquid carbon dioxide delivery branch pipeline 202 can be eliminated, and the liquid carbon dioxide injection pipe 203 can be evenly set on the lower side of the outer surface of the liquid carbon dioxide delivery main pipeline 201 to achieve uniform injection of liquid carbon dioxide.

[0044] Specifically, if Figure 1 As shown, the nitrogen injection assembly 3 includes a nitrogen delivery pipeline 301 and a nitrogen injection pipe 302. A plurality of nitrogen injection pipes 302 are evenly arranged on the lower side of the outer surface of the nitrogen delivery pipeline 301, and the nitrogen injection pipes 302 pass through the top of the tank body 1. The nitrogen injection pipes 302 and the liquid carbon dioxide injection pipes 203 are staggered.

[0045] The design of the position of the nitrogen injection pipe 302 allows it to evenly enter the upper space in the tank body 1, ensuring the temperature balance of each part of the upper space in the tank body 1.

[0046] The nitrogen gas source of the nitrogen injection assembly 3 can come from a liquid nitrogen tanker, and the liquid nitrogen can be gasified and heated to a desired temperature by electric heating means.

[0047] Specifically, if Figure 1 As shown, the monitoring component includes a first temperature sensor 10, a pressure sensor 11 and a second temperature sensor 12. The first temperature sensor 10 and the pressure sensor 11 are both arranged on the upper side of the outer surface of the tank body 1, and the second temperature sensor 12 is arranged on the lower side of the outer surface of the tank body 1. The first temperature sensor 10 is used to monitor the temperature of the upper area inside the tank body 1, the pressure sensor 11 is used to monitor the pressure inside the tank body 1, and the second temperature sensor 12 is used to monitor the temperature of the lower area inside the tank body.

[0048] The first temperature sensor 10 monitors the temperature of the upper area inside the tank body 1 , and then controls the control valve of the nitrogen injection assembly 3 to maintain the temperature of the upper area inside the tank body 1 .

[0049] The pressure sensor 11 monitors the pressure in the tank body 1, and then controls the opening of the regulating valve 5 to control the pressure in the tank body 1 within a certain range, so as to prevent the hydraulic carbon dioxide from vaporizing in the tank body 1 when the pressure is too low, and to prevent the liquid nitrogen from vaporizing and freezing the liquid nitrogen injection pipe 4 at the inlet when the liquid nitrogen enters the tank body 1.

[0050] The second temperature sensor 12 monitors the temperature of the lower area in the tank body 1, and then controls and adjusts the injection amount of liquid nitrogen to maintain the temperature of the lower area in the tank body 1 within a reasonable range. If the temperature in the lower area is too high, it will affect the freezing speed of carbon dioxide droplets and may even cause an ice layer to form at the bottom of the tank. If the temperature is too low, the liquid nitrogen may not vaporize normally.

[0051] Specifically, if Figure 1 As shown, an exhaust valve 8 and a safety valve 9 are provided on the top of the tank body 1 .

[0052] The exhaust valve 8 and the safety valve 9 are used to release the gas in the tank body 1 or to discharge the gas in the tank body 1 to prevent accidents.

[0053] The working principle of the liquid nitrogen and liquid carbon dioxide mixing device is:

[0054] Liquid carbon dioxide flows into the tank body 1 through the liquid carbon dioxide injection assembly 2, and flows out of the liquid carbon dioxide injection pipe 203 in the form of a thin stream. Under the acceleration of gravity, the thin stream will gradually break into droplets and fall into the lower area of ​​the tank body 1;

[0055] In the upper area of ​​the tank body 1, nitrogen is injected through the nitrogen injection assembly 3. Since the temperature in the upper area of ​​the tank body 1 is too low, carbon dioxide may freeze and block the liquid carbon dioxide injection pipe 203, and the temperature is too high, liquid carbon dioxide may gasify. Therefore, the temperature of the injected nitrogen is required to be lower than the critical temperature of liquid carbon dioxide, which is 31.2°C, and the corresponding critical pressure is 7.38MPa, and higher than the critical temperature of solid carbon dioxide, which is -78.5°C. In addition, the critical temperature of liquid carbon dioxide is 31.2°C, and the corresponding critical pressure is 7.38MPa, and the liquefaction pressure decreases with the decrease of temperature. Due to the pressure bearing capacity of the tank body, the temperature of the injected nitrogen needs to be closer to -78.5°C.

[0056] Since nitrogen is lighter and has a higher temperature than carbon dioxide, the temperature of the upper area of ​​the tank body 1 can be maintained at a higher level;

[0057] In the lower area of ​​the tank body 1, liquid nitrogen is injected and vaporized into nitrogen gas, so that a low-temperature zone is formed here. After the carbon dioxide droplets fall into the low-temperature zone, they are quickly transformed into hail-like or snowflake-like dry ice, and then fall to the bottom of the tank, and release heat to vaporize the liquid nitrogen, thereby forming a mixture of nitrogen gas and granular dry ice at the bottom of the tank body 1. Since the temperature of liquid nitrogen is between -196.56°C and -209°C, which is much lower than the temperature of liquid carbon dioxide, the liquid carbon dioxide in the droplet state will quickly transform into dry ice particles;

[0058] Since the heat released by converting a unit mass of liquid carbon dioxide into dry ice is basically the same as the heat absorbed by vaporizing a unit mass of liquid nitrogen, the ratio of the injection amount of liquid nitrogen to the injection amount of liquid carbon dioxide is basically 1:1;

[0059] Finally, a mixture of nitrogen and dry ice is formed at the bottom of the tank 1 and is output and collected through the output pipe 6;

[0060] When cooling the high-temperature points in the goaf, a mixture of nitrogen and dry ice is released. The dry ice vaporizes and absorbs heat, which can effectively achieve cooling. At the same time, the density of nitrogen is relatively small, so it diffuses to the high places in the goaf, while the density of carbon dioxide is relatively large, so it diffuses to the low places in the goaf, forming a three-dimensional diffusion, which can overcome the problem of limited diffusion direction of a single gas. In addition, since the production process of the nitrogen and dry ice mixture does not require electric heating for vaporization, the energy consumption is very low.

[0061] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scopes based on the ideas of the present invention. As long as these changes do not deviate from the concept of the present invention, they all belong to the protection scope of the present invention.

Claims

1. A device for mixing liquid nitrogen and liquid carbon dioxide, characterized in that: It comprises a tank body, a liquid carbon dioxide injection component, a nitrogen injection component, a liquid nitrogen injection pipe and a monitoring component. The output ends of the liquid carbon dioxide injection component and the nitrogen injection component are both plugged into the top of the tank body. The liquid carbon dioxide injection component is used to uniformly inject liquid carbon dioxide droplets into the tank body. The liquid nitrogen injection pipe is plugged and assembled on the lower side of the outer surface of the tank body. The monitoring component is assembled on the outer surface of the tank body, and the monitoring component is used to monitor the temperature and pressure in the tank body. The lower end of the tank body is equipped with a regulating valve, and the lower end of the regulating valve is equipped with an output pipe.

2. A liquid nitrogen and liquid carbon dioxide mixing device according to claim 1, characterized in that: The top of the tank body is an arc cover structure, the middle part is a barrel-shaped structure, the bottom is a V-shaped structure, and the outer surface of the tank body is provided with a heat-insulating layer.

3. A liquid nitrogen and liquid carbon dioxide mixing device according to claim 1, characterized in that: The liquid carbon dioxide injection assembly includes a liquid carbon dioxide delivery main pipeline, a liquid carbon dioxide delivery branch pipeline and a liquid carbon dioxide injection pipe. A plurality of the liquid carbon dioxide delivery branch pipelines are symmetrically installed on the front and rear sides of the liquid carbon dioxide delivery main pipeline. The liquid carbon dioxide injection pipe is evenly installed on the lower side of the outer surface of the liquid carbon dioxide delivery main pipeline and the liquid carbon dioxide delivery branch pipeline, and the liquid carbon dioxide injection pipe passes through the top of the tank body.

4. A liquid nitrogen and liquid carbon dioxide mixing device according to claim 3, characterized in that: The diameter of the injection end of the liquid carbon dioxide delivery main pipeline is larger than the diameter of the tail end.

5. A liquid nitrogen and liquid carbon dioxide mixing device according to claim 3, characterized in that: The liquid carbon dioxide injection tubes are thin tubes, and the liquid carbon dioxide injection tubes are evenly distributed in a square lattice.

6. A liquid nitrogen and liquid carbon dioxide mixing device according to claim 1, characterized in that: The nitrogen injection assembly includes a nitrogen delivery pipeline and a nitrogen injection pipe. A plurality of nitrogen injection pipes are evenly arranged on the lower side of the outer surface of the nitrogen delivery pipeline, and the nitrogen injection pipes penetrate the top of the tank body. The nitrogen injection pipes and the liquid carbon dioxide injection pipes are staggered.

7. A liquid nitrogen and liquid carbon dioxide mixing device according to claim 1, characterized in that: The monitoring component includes a first temperature sensor, a pressure sensor and a second temperature sensor. The first temperature sensor and the pressure sensor are both arranged on the upper side of the outer surface of the tank body, and the second temperature sensor is arranged on the lower side of the outer surface of the tank body. The first temperature sensor is used to monitor the temperature of the upper area inside the tank body, the pressure sensor is used to monitor the pressure inside the tank body, and the second temperature sensor is used to monitor the temperature of the lower area inside the tank body.

8. A liquid nitrogen and liquid carbon dioxide mixing device according to claim 1, characterized in that: An exhaust valve and a safety valve are arranged on the top of the tank body.

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