Air purification pre-treatment system and method with liquid refrigerant

Abstract

This invention relates to an air purification pretreatment system and method with liquid refrigeration; a primary filtration chamber is connected to a molecular sieve purification adsorption tower via a pipeline, the molecular sieve purification adsorption tower is connected to a refrigeration tank via a pipeline, the refrigeration tank contains refrigerant and refrigeration pipes, the bottom of the refrigeration pipes is connected to an output pipe located on the outside of the refrigeration tank, the inner cavity of the refrigeration tank is connected to a gas output pipe, the gas output pipe is connected to the compressor inlet, the compressor outlet is connected to a heat exchanger via a pipeline, the heat exchanger is connected to an expansion valve via a pipeline, and the expansion valve is connected to the inner cavity of the refrigeration tank via a liquid inlet pipe; this invention reduces the problems of large footprint and complex piping caused by the independent arrangement of multiple units in traditional pretreatment equipment, and is especially suitable for use with small and medium-sized air separation equipment with high space requirements.

Description

Technical Field

[0001] This invention relates to the field of air purification pretreatment technology, specifically to an air purification pretreatment system and method with liquid cooling, which is applied at the front end of an air separation system and integrates air purification and liquid cooling. Background Technology

[0002] During the operation of air separation equipment, impurities such as dust, moisture, carbon dioxide, and hydrocarbons contained in the feed air are prone to freezing and crystallization, clogging pipelines and towers after entering the cryogenic distillation system, which seriously affects the operational stability and service life of the air separation equipment. At the same time, if the feed air is not pre-cooled, it will significantly increase the cooling load of the downstream air separation system and increase the overall operating energy consumption.

[0003] Existing air separation pretreatment equipment mostly has only a single filtration or adsorption purification function, lacks an integrated low-temperature liquid refrigeration structure, and has separate purification and cooling sections, resulting in defects such as large equipment footprint, complex pipeline connections, poor pretreatment effect, and high energy consumption; some pretreatment devices with refrigeration functions have complex structures and are difficult to maintain, and cannot meet the matching needs of small and medium-sized air separation equipment.

[0004] Therefore, developing a compact, highly integrated air purification and liquid cooling system and method that can simultaneously purify and cool air, and is suitable for use as a pretreatment step in air separation systems, has significant engineering application value. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an air purification pretreatment system and method with liquid cooling that is simple in structure, easy to operate, has strong continuous production capacity, effectively improves production efficiency, meets the needs of large-scale production, has a high degree of integration, and simultaneously completes air purification and liquid cooling. It is suitable for use as a pretreatment in air separation systems and is simple and easy to operate, thus overcoming the deficiencies in existing technologies.

[0006] The technical solution of this invention is implemented as follows: An air purification pretreatment system with liquid refrigeration includes an air inlet, which is connected to a primary filter chamber via a pipe. The primary filter chamber is connected to a molecular sieve purification adsorption tower via a pipe. The molecular sieve purification adsorption tower is connected to a refrigeration tank via a pipe. The refrigeration tank contains refrigerant and a refrigeration pipe. The bottom of the refrigeration pipe is connected to an output pipe located on the outside of the refrigeration tank. The inner cavity of the refrigeration tank is connected to a gas output pipe. The gas output pipe is connected to the air inlet of a compressor. The outlet of the compressor is connected to a heat exchanger via a pipe. The heat exchanger is connected to an expansion valve via a pipe. The expansion valve is connected to the inner cavity of the refrigeration tank via a liquid inlet pipe.

[0007] Furthermore, the air inlet has a funnel-shaped structure, and a filter screen is provided at the inner end of the air inlet. The air inlet is connected to one side of the top of the primary filter chamber through an air inlet pipe, and an induced draft fan is installed on the air inlet pipe.

[0008] Furthermore, the primary filtration chamber is provided with at least one longitudinally arranged air filter screen, the top of the primary filtration chamber is provided with a sealed and closable maintenance cover, and one side of the bottom of the primary filtration chamber is connected to the bottom of the molecular sieve purification and adsorption tower through an air output pipe.

[0009] Furthermore, the molecular sieve purification adsorption tower is provided with a bottom support net and an upper support net, and adsorbent particles are filled between the bottom support net and the upper support net.

[0010] Furthermore, the molecular sieve purification and adsorption tower is connected to the top of the refrigeration tank via a clean air delivery pipeline, and a first solenoid valve is installed on the clean air delivery pipeline.

[0011] Furthermore, the refrigeration pipe is arranged in an S-shape inside the refrigeration tank from top to bottom, and the top of the refrigeration pipe is connected to the clean air delivery pipe. A second solenoid valve is installed on the output pipe.

[0012] Furthermore, a third solenoid valve is installed on the gas output pipe, and a bracket is provided on the outside of the compressor and heat exchanger.

[0013] Furthermore, a thermometer connected to the inner cavity of the refrigeration tank is installed on the top of the tank.

[0014] Furthermore, the bottom of the refrigeration pipe is connected to the drain pipe via a three-way valve, and the drain pipe is connected to the drain port located at the bottom of the refrigeration tank. A fourth solenoid valve is installed on the drain pipe.

[0015] An air purification and pretreatment method for an air purification and pretreatment system with liquid cooling as described in any of the above claims, the method comprising the following steps: S1. Ambient air enters through the air inlet, and after passing through the filter screen to initially intercept large particles of impurities, it is then transported to the primary filter chamber through the air intake pipe under the suction of the induced draft fan. It undergoes multi-stage physical filtration through the air filter screen to remove dust and particulate matter. S2. The air that has passed through the primary filter enters the molecular sieve purification and adsorption tower from the bottom of the primary filter chamber through the air output pipe. The air passes through the adsorbent particle layer fixed by the bottom support net and the upper support net from bottom to top, adsorbing moisture, CO2 and some organic impurities to obtain high-cleanliness air. S3. High-purity air enters the top of the refrigeration tank through a clean air delivery pipeline and the flow rate is controlled by the first solenoid valve. The air flows from top to bottom along the refrigeration pipe and exchanges heat efficiently with the refrigerant surrounding the tank, achieving rapid cooling and reducing the gas temperature to near the dew point, thus promoting the condensation and precipitation of residual water vapor. S4. During the refrigeration process, the condensed liquid water and impurities are discharged through the drain pipe and drain port after the fourth solenoid valve is opened. The cooled and purified gas flows out from the outlet of the refrigeration pipe through the output pipe and is controlled by the second solenoid valve. S5. The temperature of the refrigerant is monitored by a thermometer. When the temperature of the refrigerant rises, the third solenoid valve is opened. The refrigerant enters the compressor through the gas output pipe for pressurization. The high-temperature and high-pressure gas after compression enters the heat exchanger for heat dissipation. The cooled gas is throttled and depressurized through the expansion valve and then reinjected into the inner cavity of the refrigeration tank through the liquid inlet pipe to replenish or maintain the circulation of the refrigerant.

[0016] The present invention has the following positive effects: 1. The present invention has a compact structure and a high degree of integration. The system integrates multiple functional modules such as primary air filtration, molecular sieve adsorption and purification, liquid cooling and condensate drainage into one unit. It is efficiently connected through pipes and valves, reducing the problems of large footprint and complex piping caused by the independent arrangement of multiple units in traditional pretreatment equipment. It is especially suitable for use with small and medium-sized air separation equipment with high space requirements.

[0017] 2. This invention features high pretreatment efficiency and synergistic purification and cooling, achieving continuous and integrated air purification and deep cooling. Through a synergistic process of filtration, adsorption, and liquid cooling, it effectively removes dust, moisture, CO2, and organic impurities from the air, preventing icing and blockage in the subsequent low-temperature distillation system. Furthermore, the liquid cooling module rapidly cools the gas to near its dew point, removing residual moisture and lowering the gas temperature in advance, significantly reducing the cooling load on the downstream air separation system.

[0018] 3. The system operates stably and reliably, and is easy to maintain. Four solenoid valves are installed to precisely control the flow and on / off state of gas / liquid at each stage, achieving automated operation. A thermometer is installed on the top of the refrigeration tank to monitor the refrigerant temperature in real time, providing a basis for starting and stopping the refrigeration cycle. The primary filter chamber has a sealed, openable inspection cover for easy replacement or cleaning of the filter screen. A drain port is located at the bottom of the refrigeration tank, and a controllable drain channel is formed through a three-way valve, drain pipe, and a fourth solenoid valve, facilitating the periodic removal of condensate and impurities to maintain the cleanliness of the system.

[0019] 4. This invention offers significant energy savings and recycles resources. It establishes a closed-loop refrigeration system for the refrigerant through a compressor, heat exchanger, expansion valve, and inlet pipe. When the refrigerant temperature rises, the system automatically initiates the cycle, pressurizing, cooling, and throttling the refrigerant before re-injecting it into the refrigeration tank to replenish or maintain its cooling capacity. This achieves energy recovery and reuse, reducing overall operating energy consumption.

[0020] 5. The method of this invention is simple and easy to operate, with strong continuous production capacity. The system design ensures continuous operation from air introduction to high-purity, low-temperature gas output. Each link is closely connected, which can meet the stability and continuity requirements of large-scale industrial production and effectively improve production efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention.

[0022] Figure 2 This is a schematic diagram of the internal structure of the present invention.

[0023] Figure 3 This is a schematic diagram of the internal structure of the molecular sieve purification and adsorption tower of the present invention.

[0024] Figure 4 This is a schematic diagram of the internal structure of the refrigeration tank of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the following description of the invention, it should be noted that the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, 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. The term "connection" simply indicates a connection between devices and has no special meaning.

[0027] like Figure 1 , 2As shown in Figures 3 and 4, an air purification pretreatment system with liquid refrigeration includes an air inlet 1. The air inlet 1 is connected to a primary filter chamber 4 via a pipe. The primary filter chamber 4 is connected to a molecular sieve purification adsorption tower 5 via a pipe. The molecular sieve purification adsorption tower 5 is connected to a refrigeration tank 8 via a pipe. The refrigeration tank 8 contains a refrigerant 27 and a refrigeration pipe 26. The bottom of the refrigeration pipe 26 is connected to an output pipe 9 located on the outside of the refrigeration tank 8. The inner cavity of the refrigeration tank 8 is connected to a gas output pipe 12. The gas output pipe 12 is connected to the air inlet of a compressor 19. The outlet of the compressor 19 is connected to a heat exchanger 20 via a pipe. The heat exchanger 20 is connected to an expansion valve 21 via a pipe. The expansion valve 21 is connected to the inner cavity of the refrigeration tank 8 via a liquid inlet pipe 13.

[0028] The air inlet 1 has a funnel-shaped structure, and a filter screen 15 is installed at the inner end of the air inlet 1. The air inlet 1 is connected to one side of the top of the primary filter chamber 4 through the air inlet pipe 2, and an induced draft fan 3 is installed on the air inlet pipe 2. The primary filter chamber 4 is equipped with at least one longitudinally arranged air filter screen 17. The top of the primary filter chamber 4 is equipped with a sealed and closable maintenance cover 16. One side of the bottom of the primary filter chamber 4 is connected to the bottom of the molecular sieve purification adsorption tower 5 through an air outlet pipe 22. The molecular sieve purification adsorption tower 5 is equipped with a bottom support net 24 and an upper support net 23, and adsorbent particles 25 are filled between the bottom support net 24 and the upper support net 23.

[0029] The molecular sieve purification adsorption tower 5 is connected to the top of the refrigeration tank 8 via a clean air delivery pipe 7, and a first solenoid valve 6 is installed on the clean air delivery pipe 7. The refrigeration pipe 26 is S-shaped and installed from top to bottom inside the refrigeration tank 8. The top of the refrigeration pipe 26 is connected to the clean air delivery pipe 7, and a second solenoid valve 10 is installed on the output pipe 9. A third solenoid valve 18 is installed on the gas output pipe 12. A bracket 14 is installed on the outside of the compressor 19 and the heat exchanger 20. A thermometer 28 is installed on the top of the refrigeration tank 8 and communicates with its inner cavity. The bottom of the refrigeration pipe 26 is connected to the drain pipe 30 via a three-way valve 29. The drain pipe 30 is connected to the drain port 11 located at the bottom of the refrigeration tank 8, and a fourth solenoid valve 31 is installed on the drain pipe 30.

[0030] An air purification and pretreatment method with an air purification and pretreatment system incorporating liquid cooling includes the following steps: S1. Ambient air enters through the air inlet 1, and after passing through the filter screen 15, large particles of impurities are initially intercepted. Then, under the suction of the induced draft fan 3, it is transported to the primary filter chamber 4 through the air intake pipe 2, and undergoes multi-stage physical filtration through the air filter screen plate 17 to remove dust and particulate matter. S2. The air that has passed through the primary filter enters the molecular sieve purification adsorption tower 5 from the bottom of the primary filter chamber 4 through the air output pipe 22. The air passes through the adsorbent particles 25 layer fixed by the bottom support net 24 and the upper support net 23 from bottom to top, adsorbing moisture, CO2 and some organic impurities to obtain high-cleanliness air. S3. High-purity air enters the top of the refrigeration tank 8 through the clean air delivery pipe 7 and the flow rate is controlled by the first solenoid valve 6. The air flows from top to bottom along the refrigeration pipe 26 and exchanges heat efficiently with the refrigerant 27 surrounding the tank, achieving rapid cooling, reducing the gas temperature to near the dew point, and promoting the condensation and precipitation of residual water vapor. S4. During the refrigeration process, the condensed liquid water and impurities are discharged through the drain pipe 30 and drain port 11 after the fourth solenoid valve 31 is opened. The cooled and purified gas flows out from the outlet of the refrigeration pipe through the output pipe 9 and is controlled by the second solenoid valve 10. S5. Temperature monitoring of refrigerant 27 is performed by thermometer 28. When the temperature of refrigerant 27 rises, the third solenoid valve 18 is opened. Refrigerant 27 enters compressor 19 through gas output pipe 12 for pressurization. The high-temperature and high-pressure gas after compression enters heat exchanger 20 for heat dissipation. The cooled gas is throttled and depressurized by expansion valve 21 and re-injected into the inner cavity of refrigeration tank 8 through liquid inlet pipe 13 to replenish or maintain the circulation volume of refrigerant 27.

[0031] In actual operation, the air inlet 1 is designed in a funnel shape, with a filter screen 15 installed at its inner end. The air inlet is connected to the top of the primary filtration chamber 4 via the air inlet pipe 2, and an induced draft fan 3 is installed on the air inlet pipe to provide power to draw ambient air into the system. The primary filtration chamber 4 is equipped with at least one longitudinally arranged air filter screen 17 for multi-stage physical filtration of the incoming air. A sealed and closable maintenance cover 16 is installed on the top of the chamber to facilitate replacement or cleaning of the screens. One side of the bottom of the chamber is connected to the bottom of the molecular sieve purification adsorption tower 5 via an air outlet pipe 22.

[0032] The molecular sieve purification adsorption tower 5 is equipped with a bottom support net 24 and an upper support net 23, and adsorbent particles 25 are filled between the two support nets. The top of the tower is connected to the top of the refrigeration tank 8 through a clean air delivery pipe 7, and a first solenoid valve 6 is installed on the pipe to control the flow rate of air entering the refrigeration tank.

[0033] The refrigeration tank 8 is the core of this unit. First, an S-shaped refrigeration pipe 26 is installed inside the refrigeration tank from top to bottom. The top of the refrigeration pipe 26 is connected to the clean air delivery pipe 7. Second, an output pipe 9 is installed on the outside of the refrigeration tank 8, which is connected to the bottom of the refrigeration pipe 26, and a second solenoid valve 10 is installed on the pipe. In addition, the refrigeration tank 8 is pre-filled with refrigerant 27. The inner cavity of the refrigeration tank 8 is connected to the air inlet of the compressor 19 through a gas output pipe 12, and a third solenoid valve 18 is installed on this pipe. The outlet of the compressor 19 is connected to the heat exchanger 20 and the expansion valve 21 in sequence. The expansion valve 21 returns the treated refrigerant to the inner cavity of the refrigeration tank 8 through the liquid inlet pipe 13. The compressor and the heat exchanger need to be fixed on the bracket 14. A thermometer 28 is installed on the top of the refrigeration tank and connected to its inner cavity for real-time monitoring of the refrigerant temperature.

[0034] The bottom of the refrigeration tank 8 is provided with a drain port 11. The bottom of the refrigeration pipe 26 is connected to a drain pipe 30 through a three-way valve 29. The drain pipe leads to the drain port 11, and a fourth solenoid valve 31 is installed on the drain pipe.

[0035] During operation, ambient air is drawn in by the induced draft fan 3 and enters through the funnel-shaped air inlet 1. First, most large particles are intercepted by the filter screen 15 at its inner end. Then, the air is sent through the air intake pipe 2 into the primary filter chamber 4, and sequentially passes through the longitudinally arranged multi-layer air filter screens 17 to further remove dust and fine particulate matter from the air.

[0036] Clean air, after primary filtration, flows out from the bottom of the primary filter chamber 4 and is sent to the bottom of the molecular sieve purification adsorption tower 5 via the air output pipe 22. The air flows upwards through the bed of adsorbent particles 25 fixed by the bottom support net 24 and the upper support net 23. During this process, moisture, carbon dioxide, and some organic impurities in the air are efficiently adsorbed, resulting in highly clean air.

[0037] High-purity air, under airflow control, is regulated by the first solenoid valve 6 and then enters the refrigeration tank 8 through the clean air delivery pipe 7. The air flows downwards within the S-shaped refrigeration pipe 26, undergoing thorough and efficient heat exchange with the refrigerant 27 surrounding the pipe. The gas temperature is rapidly reduced to near its dew point, and residual water vapor condenses. The cooled gas flows out from the end of the refrigeration pipe 26 and is directed to the subsequent application end through the output pipe 9; its flow rate is controlled by the second solenoid valve 10. When the fourth solenoid valve 31 is opened, the liquid condensate accumulated at the inlet of the drain pipe 30 is discharged from the system through the drain pipe 30 and drain port 11 under the influence of gravity or system pressure difference, ensuring the cleanliness and operational efficiency of the system.

[0038] The temperature of the refrigerant 27 is continuously monitored by a thermometer 28 installed on top of the refrigeration tank. When the system has been running for a period of time, and the temperature of the refrigerant rises above a set threshold due to absorbing heat from the air, the refrigerant regeneration circulation system is activated: the third solenoid valve 18 is opened, and the refrigerant or the phase-change gaseous refrigerant enters the compressor 19 under pressure through the gas output pipe 12. The compressor pressurizes the refrigerant, making it a high-temperature, high-pressure gas. This high-temperature, high-pressure gas then enters the heat exchanger 20 for heat dissipation and cooling. The cooled high-pressure fluid is then throttled and depressurized by the expansion valve 21, and finally reinjected into the inner cavity of the refrigeration tank 8 through the liquid inlet pipe 13. This circulation process replenishes the refrigerant in the refrigeration tank and restores the refrigerant to a low-temperature state, thereby maintaining the system's continuous cooling capacity.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art 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 air purification and pretreatment system with liquid cooling, comprising an air inlet (1), characterized in that: The air inlet (1) is connected to the primary filter chamber (4) through a pipe. The primary filter chamber (4) is connected to the molecular sieve purification and adsorption tower (5) through a pipe. The molecular sieve purification and adsorption tower (5) is connected to the refrigeration tank (8) through a pipe. The refrigeration tank (8) is equipped with a refrigerant (27) and a refrigeration pipe (26). The bottom of the refrigeration pipe (26) is connected to the output pipe (9) located on the outside of the refrigeration tank (8). The inner cavity of the refrigeration tank (8) is connected to the gas output pipe (12). The gas output pipe (12) is connected to the air inlet of the compressor (19). The outlet of the compressor (19) is connected to the heat exchanger (20) through a pipe. The heat exchanger (20) is connected to the expansion valve (21) through a pipe. The expansion valve (21) is connected to the inner cavity of the refrigeration tank (8) through the liquid inlet pipe (13).

2. The air purification and pretreatment system with liquid cooling according to claim 1, characterized in that: The air inlet (1) is a funnel-shaped structure. A filter screen (15) is provided at the inner end of the air inlet (1). The air inlet (1) is connected to the top side of the primary filter chamber (4) through the air inlet pipe (2). An induced draft fan (3) is installed on the air inlet pipe (2).

3. The air purification and pretreatment system with liquid cooling according to claim 1, characterized in that: The primary filter chamber (4) is provided with at least one longitudinally arranged air filter screen (17), and the top of the primary filter chamber (4) is provided with a sealed opening and closing maintenance cover (16). The bottom side of the primary filter chamber (4) is connected to the bottom of the molecular sieve purification adsorption tower (5) through an air output pipe (22).

4. The air purification and pretreatment system with liquid cooling according to claim 1, characterized in that: The molecular sieve purification adsorption tower (5) is provided with a bottom support net (24) and an upper support net (23), and adsorbent particles (25) are filled between the bottom support net (24) and the upper support net (23).

5. The air purification and pretreatment system with liquid cooling according to claim 1, characterized in that: The molecular sieve purification adsorption tower (5) is connected to the top of the refrigeration tank (8) through a clean air delivery pipe (7), and a first solenoid valve (6) is installed on the clean air delivery pipe (7).

6. The air purification and pretreatment system with liquid cooling according to claim 5, characterized in that: The refrigeration pipe (26) is arranged in an S-shape inside the refrigeration tank (8) from top to bottom. The top of the refrigeration pipe (26) is connected to the clean air delivery pipe (7), and a second solenoid valve (10) is provided on the output pipe (9).

7. The air purification and pretreatment system with liquid cooling according to claim 1, characterized in that: A third solenoid valve (18) is installed on the gas output pipe (12), and a bracket (14) is provided on the outside of the compressor (19) and the heat exchanger (20).

8. The air purification and pretreatment system with liquid cooling according to claim 1, characterized in that: The top of the refrigeration tank (8) is equipped with a thermometer (28) that communicates with its inner cavity.

9. The air purification and pretreatment system with liquid cooling according to claim 1, characterized in that: The bottom of the refrigeration pipe (26) is connected to the drain pipe (30) via a three-way valve (29). The drain pipe (30) is connected to the drain port (11) located at the bottom of the refrigeration tank (8). A fourth solenoid valve (31) is installed on the drain pipe (30).

10. An air purification and pretreatment method for an air purification and pretreatment system with liquid cooling as described in any one of claims 1-7, characterized in that, The method includes the following steps: S1. Ambient air enters through the air inlet (1), and after being initially intercepted by the filter screen (15), large particles of impurities are then transported to the primary filter chamber (4) through the air inlet pipe (2) under the suction action of the induced draft fan (3). The air is then subjected to multi-stage physical filtration through the air filter screen plate (17) to remove dust and particulate matter. S2. After primary filtration, the air enters the molecular sieve purification adsorption tower (5) from the bottom of the primary filtration chamber (4) through the air output pipe (22). The air passes through the adsorbent particle (25) layer fixed by the bottom support net (24) and the upper support net (23) from bottom to top, adsorbing moisture, CO2 and some organic impurities to obtain high-cleanliness air. S3. High-purity air enters the top of the refrigeration tank (8) through the clean air delivery pipe (7) and the flow rate is controlled by the first solenoid valve (6). The air flows from top to bottom along the refrigeration pipe (26) and exchanges heat efficiently with the refrigerant (27) surrounding the tank, achieving rapid cooling, reducing the gas temperature to near the dew point, and promoting the condensation and precipitation of residual water vapor. S4. During the refrigeration process, the condensed liquid water and impurities are discharged through the drain pipe (30) and drain port (11) after the fourth solenoid valve (31) is opened. The cooled and purified gas flows out from the outlet of the refrigeration pipe through the output pipe (9) and is controlled by the second solenoid valve (10). S5. Temperature monitoring of refrigerant (27) is performed by thermometer (28). When the temperature of refrigerant (27) rises, the third solenoid valve (18) is opened. Refrigerant (27) enters compressor (19) through gas output pipe (12) for pressurization. The high temperature and high pressure gas after compression enters heat exchanger (20) for heat dissipation. The cooled gas is throttled and depressurized through expansion valve (21) and re-injected into the inner cavity of refrigeration tank (8) through liquid inlet pipe (13) to replenish or maintain the circulation volume of refrigerant (27).

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