A downhole mobile carbon dioxide transcritical refrigeration dehumidification device

Abstract

The application discloses a downhole mobile carbon dioxide transcritical refrigeration dehumidification device and belongs to the technical field of mine cooling and dehumidification. The device comprises at least one compressor, the compressor is provided with an air inlet and a high-temperature and high-pressure gas outlet, a high-temperature and high-pressure oil-gas separator is in communication with the high-temperature and high-pressure gas outlet of the compressor, an air-cooling exchange unit is connected with the high-temperature and high-pressure gas output end of the high-temperature and high-pressure oil-gas separator, a first pressure reduction unit is in communication with the gas output end of the air-cooling exchange unit after temperature reduction, an air-cooling exchange unit is connected with the gas output end of the first pressure reduction unit after pressure reduction, a low-temperature and low-pressure oil-gas separator is in communication with the output end of the air-cooling exchange unit after heat exchange, and the output end of the low-temperature and low-pressure oil-gas separator is in communication with the air inlet of the compressor. The application uses the characteristics and principles that a large amount of heat can be absorbed during the phase change process from liquid to gas, uses transcritical carbon dioxide to replace freon refrigerant, and has higher heat exchange efficiency.

Description

Technical Field

[0001] This invention belongs to the field of mine cooling and dehumidification technology, specifically relating to an underground mobile transcritical carbon dioxide refrigeration and dehumidification device. Background Technology

[0002] As mining depths continue to increase in my country, the heat hazards from high temperatures in mines are becoming increasingly severe. According to incomplete statistics, there are over 1200 high-temperature faces in both high-temperature and non-high-temperature mines in my country's mining industry, posing a significant heat hazard problem. In some mining faces, the airflow temperature exceeds 30℃, and in some mines it even exceeds 40℃, far exceeding the standard of "no more than 26℃ for air at the mining face" stipulated in the "Coal Mine Safety Regulations".

[0003] Of the proven coal reserves, those at depths of 1000m-2000m account for 53.2% of the total reserves. Currently, the mining depth of coal mines in my country is increasing at a rate of 8m-12m per year, and it is estimated that many coal mines will reach mining depths of 1000m-1500m within the next 20 years. Based on the theoretical calculation that the rock temperature increases by approximately 3℃ for every 100m of deepening mining, the future maximum mining depth will, in a sense, depend on the level of heat hazard control in the mine. Therefore, the relevant theories and technologies for high-temperature heat hazard control in mines have become one of the key technologies for deep mining.

[0004] From the perspective of occupational hazards, heat hazard has seriously affected the health of underground workers. Like coal dust hazard, it is one of the main occupational hazard factors in my country's coal mine production. Carrying out heat hazard prevention and control work is also an important part of occupational health work in coal mines, and it is of great significance to improving the level of occupational health in coal mines!

[0005] The primary cooling technology used in existing mine working faces is artificial refrigeration. Based on thermodynamic characteristics, this can be categorized into centralized air conditioning cooling, ice-cooling cooling, air-cooling cooling, combined heat, power, and cooling systems (CHP), and HEMS cooling. However, overall, artificial refrigeration technology still suffers from problems such as expensive refrigeration equipment, significant losses during long-distance refrigerant (water) transportation, high requirements for pipeline insulation, high power consumption, large size, high equipment operation and maintenance costs, and low operating efficiency. Furthermore, my country's mine cooling systems are mainly centralized, which has relatively poor adaptability to localized high-temperature areas in non-high-temperature mines, failing to meet the actual needs of underground mines. Therefore, finding a new, efficient cooling technology is crucial.

[0006] Currently, most underground mobile local cooling technologies use Freon as the medium, and the cooling efficiency of the units is generally below 3.0. The low cooling efficiency and high operating costs are the main factors restricting the management of the thermal environment in mines. The use of Freon is also not in line with the current "dual carbon" goal. Summary of the Invention

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] A downhole mobile transcritical carbon dioxide refrigeration and dehumidification device includes:

[0009] At least one compressor, wherein the compressor is a semi-hermetic reciprocating compressor, and the working medium of the compressor is carbon dioxide; the compressor has an air inlet, a high-temperature and high-pressure gas outlet, and a lubricating and cooling oil inlet.

[0010] A high-temperature and high-pressure oil-gas separator is connected to the high-temperature and high-pressure gas outlet of the compressor and is used to separate the high-temperature and high-pressure oil-gas mixture generated by the compressor into gas and liquid components.

[0011] An air-cooling exchange unit is provided, the input end of which is connected to the high-temperature and high-pressure gas output end of the high-temperature and high-pressure oil-gas separator, for cooling the high-temperature and high-pressure gas output from the high-temperature and high-pressure oil-gas separator.

[0012] The first pressure reduction unit is connected to the gas output terminal of the gas-cooled exchange unit after cooling, and is used to reduce the pressure of the gas after cooling by the gas-cooled exchange unit.

[0013] An air-cooled exchange unit is located downhole and is connected to the gas output terminal of the first depressurization unit after depressurization. The air-cooled exchange unit is used to exchange heat with the downhole to reduce the temperature and humidity downhole and output a low-pressure, low-temperature oil-gas mixture.

[0014] A low-temperature, low-pressure oil-gas separator is provided. The input end of the low-temperature, low-pressure oil-gas separator is connected to the output end of the air-cooled heat exchange unit after heat exchange. The output end of the low-temperature, low-pressure oil-gas separator is connected to the air inlet of the compressor. The low-temperature, low-pressure oil-gas separator is used to separate the low-pressure, low-temperature oil-gas mixture output from the air-cooled heat exchange unit into gas and liquid. The separated carbon dioxide gas is then delivered to the compressor.

[0015] Furthermore, there are two compressors, and the parameters of the compressors are as follows:

[0016] The exhaust volume is 45.34m³. 3 / h; cooling capacity is 225kW; power is 55kW; speed is 1450r / min; maximum working pressure is 15MPa; static pressure is 10MPa; voltage rating is 380V, 3-phase, 50HZ; maximum working current is 148A, stall current is 584A; continuous operating current is 115A; maximum working temperature is 160℃; ambient temperature is -20℃~60℃.

[0017] Furthermore, the high-temperature and high-pressure oil-gas separator is a centrifugal separator; the high-temperature and high-pressure oil-gas separator has a high-temperature and high-pressure gas-liquid separation inlet, a high-temperature and high-pressure gas separation outlet, and a high-temperature and high-pressure liquid separation outlet. The high-temperature and high-pressure gas-liquid separation inlet is connected to the high-temperature and high-pressure gas outlet, and the high-temperature and high-pressure gas separation outlet is connected to the input end of the gas-cooling exchange unit; the high-temperature and high-pressure liquid separation outlet is connected to the first oil inlet of the low-temperature and low-pressure oil-gas separator through a second pressure reducing unit.

[0018] Furthermore, the low-temperature and low-pressure oil-gas separator is a centrifugal separator, and the low-temperature and low-pressure oil-gas separator has a low-temperature and low-pressure gas-liquid separation inlet, a low-temperature and low-pressure gas separation outlet and a low-temperature and low-pressure liquid separation outlet. The low-temperature and low-pressure gas-liquid separation inlet is connected to the gas output end after pressure reduction by the first pressure reducing unit.

[0019] The low-temperature, low-pressure gas separation outlet is connected to the air inlet of the compressor; the low-temperature, low-pressure liquid separation outlet is connected to the input end of the oil pump through a first connecting pipe, and the output end of the oil pump is connected to the lubricating and cooling oil inlet of the compressor through a second connecting pipe; a connecting branch is connected to the second connecting pipe, and the other end of the connecting branch is connected to the second oil inlet of the low-temperature, low-pressure oil-gas separator; a manual valve is provided on the connecting branch.

[0020] Furthermore, the air-cooled exchange unit is an air cooler, which has a gas inlet, a gas outlet, a cold water inlet, and a hot water outlet; the total heat exchange power of the air cooler is 600kW, the maximum working pressure is 10.5MPa, the maximum working pressure is 16MPa, the test pressure is 20MPa, and the working temperature is ≤200℃.

[0021] Furthermore, the air-cooled exchange unit is an air cooler.

[0022] Furthermore, the first pressure reducing unit includes multiple sets of first pressure reducing coils arranged in parallel. The first pressure reducing coil is a high-pressure resistant heat-insulating capillary tube. The first end of the first pressure reducing coil is connected to the gas outlet of the air cooler, and the second end is connected to the air inlet of the air cooler. A control valve is provided between the first end of each of the multiple first pressure reducing coils and the gas outlet of the air cooler.

[0023] The second pressure reducing unit is a set of second pressure reducing coils, which are high-pressure resistant heat-insulating capillary tubes. The first end of the second pressure reducing coil is connected to the high-temperature and high-pressure liquid separation outlet, and the second end of the second pressure reducing coil is connected to the first oil inlet of the low-temperature and low-pressure oil-gas separator. A control valve is provided between the second end of the second pressure reducing coil and the first oil inlet of the low-temperature and low-pressure oil-gas separator.

[0024] Furthermore, the first pressure reducing coil has 3 turns of 260mm; the second pressure reducing coil has 2 turns of 260mm.

[0025] The beneficial effects of this invention are:

[0026] The mobile transcritical carbon dioxide refrigeration and dehumidification device provided by this invention utilizes the characteristic and principle that carbon dioxide can absorb a large amount of heat during the phase change process from liquid to gaseous under high pressure and high temperature supercritical and low pressure and low temperature subcritical states. Through the control of carbon dioxide transcritical and phase change states, safety protection under high pressure, and related supporting equipment, it meets the requirements for underground application and has higher heat exchange efficiency.

[0027] This invention utilizes transcritical CO2 to replace traditional Freon refrigerants, reducing ozone layer depletion; it provides a new paradigm for heat hazard management in deep mining, protects miners' occupational health and safety, improves mine production efficiency and quality, and promotes the sustainable development of the coal industry. Attached Figure Description

[0028] Figure 1 A schematic diagram of the overall structure of the downhole mobile transcritical carbon dioxide refrigeration and dehumidification device provided by the present invention.

[0029] The components include: 1. Compressor; 2. High-temperature and high-pressure oil-gas separator; 3. Air-cooling exchange unit; 4. Oil pump; 5. First pressure reducing unit; 6. Low-temperature and low-pressure oil-gas separator; 7. Air-cooling exchange unit; 8. Second pressure reducing unit; 9. Second control valve; 10. First control valve; 11. Manual valve; 12. Solenoid valve. Detailed Implementation

[0030] This invention provides a downhole mobile transcritical carbon dioxide refrigeration and dehumidification device. The technical solution of this invention will be described in detail below with reference to the accompanying drawings to make it easier to understand and master.

[0031] Example 1

[0032] refer to Figure 1 A mobile downhole transcritical carbon dioxide refrigeration and dehumidification device, comprising:

[0033] At least one compressor 1, compressor 1 is a semi-hermetic reciprocating compressor, the working medium is carbon dioxide; compressor 1 has an air inlet, a high temperature and high pressure gas outlet and a lubricating and cooling oil inlet;

[0034] High-temperature and high-pressure oil-gas separator 2 is connected to the high-temperature and high-pressure gas outlet of compressor 1 and is used to separate the high-temperature and high-pressure oil-gas mixture generated by compressor 1 into gas and liquid components.

[0035] The input end of the air-cooling exchange unit 3 is connected to the high-temperature and high-pressure gas output end of the high-temperature and high-pressure oil-gas separator 2, and is used to cool down the high-temperature and high-pressure gas output from the high-temperature and high-pressure oil-gas separator 2.

[0036] The first pressure reduction unit 5 is connected to the gas output terminal of the gas-cooled exchange unit 3 after cooling, and is used to reduce the pressure of the gas after cooling by the gas-cooled exchange unit 3.

[0037] Air-cooled exchange unit 7 is located downhole and is connected to the gas output end of the first depressurization unit 5 after depressurization. Air-cooled exchange unit 7 is used to exchange heat with downhole to reduce downhole temperature and humidity and output low-pressure low-temperature oil and gas mixture.

[0038] The low-temperature and low-pressure oil-gas separator 6 has its input end connected to the output end of the air-cooled exchange unit 7 after heat exchange, and its output end connected to the air inlet of the compressor 1. The low-temperature and low-pressure oil-gas separator 6 is used to separate the low-pressure and low-temperature oil-gas mixture output from the air-cooled exchange unit 7. The separated carbon dioxide gas is then transported to the compressor 1.

[0039] In this embodiment, although the transcritical cycle carbon dioxide refrigeration system has advantages such as being able to start and operate normally at extremely low ambient temperatures, the operating pressure within the system is extremely high (5 to 10 times that of a typical Freon system). Therefore, a dedicated compressor with a high-strength mechanical structure is required. Based on the downhole requirement of 400kW cooling capacity, two 200kW transcritical carbon dioxide compressors were selected. Because the manufacturing process of the carbon dioxide compressor fully considers various factors such as pressure resistance, efficiency, size, and safety, a semi-hermetic structure is adopted.

[0040] Therefore, this embodiment selects two CD6-801-45H compressors. Compressor 1 is a semi-hermetic reciprocating compressor with a lubricating and cooling oil inlet. The parameters of compressor 1 are as follows: discharge capacity of 45.34 m3 / h; cooling capacity of 225 kW; power of 55 kW; speed of 1450 r / min; maximum working pressure of 15 MPa; static pressure of 10 MPa; voltage rating of 380V, 3-phase, 50 Hz; maximum working current of 148 A; locked rotor current of 584 A; continuous operating current of 115 A; maximum working temperature of 160℃; and ambient temperature of -20℃ to 60℃.

[0041] In this embodiment, the high-temperature and high-pressure oil-gas separator 2 is a centrifugal separator; the high-temperature and high-pressure oil-gas separator 2 has a high-temperature and high-pressure gas-liquid separation inlet, a high-temperature and high-pressure gas separation outlet and a high-temperature and high-pressure liquid separation outlet. The high-temperature and high-pressure gas-liquid separation inlet is connected to the high-temperature and high-pressure gas outlet, and the high-temperature and high-pressure gas separation outlet is connected to the input end of the gas-cooling exchange unit 3; the high-temperature and high-pressure liquid separation outlet is connected to the first oil inlet of the low-temperature and low-pressure oil-gas separator 6 through the second pressure reducing unit 8.

[0042] In this embodiment, the low-temperature and low-pressure oil-gas separator 6 is a centrifugal separator. The low-temperature and low-pressure oil-gas separator 6 has a low-temperature and low-pressure gas-liquid separation inlet, a low-temperature and low-pressure gas separation outlet and a low-temperature and low-pressure liquid separation outlet. The low-temperature and low-pressure gas-liquid separation inlet is connected to the gas output end after pressure reduction by the first pressure reducing unit 5.

[0043] The low-temperature, low-pressure gas separation outlet is connected to the air inlet of the compressor 1; the low-temperature, low-pressure liquid separation outlet is connected to the input end of the oil pump 4 through the first connecting pipe, and the output end of the oil pump 4 is connected to the lubricating and cooling oil inlet of the compressor 1 through the second connecting pipe; a connecting branch is connected to the second connecting pipe, and the other end of the connecting branch is connected to the second oil inlet of the low-temperature, low-pressure oil-gas separator 6; a manual valve 11 is provided on the connecting branch, and a solenoid valve 12 is provided on the first connecting pipe between the connecting branch and the first connecting pipe and the compressor 1.

[0044] Because the carbon dioxide compressor 1 is a semi-hermetic reciprocating compressor, it requires specialized oil for lubrication and cooling. Therefore, a low-temperature, low-pressure oil-gas separator 6 is installed at the inlet, and a high-temperature, high-pressure oil-gas separator 2 is installed at the outlet to recover and circulate the oil. Both the low-temperature, low-pressure oil-gas separator 6 and the high-temperature, high-pressure oil-gas separator 2 are centrifugal separators that separate oil-containing gases from the gas in the unit. The oil content after separation is less than 1%, based on a single compressor discharge capacity of 45.34 m³ / h. 3 The gas processing capacity of the low-temperature, low-pressure oil-gas separator 6 and the high-temperature, high-pressure oil-gas separator 2 is 90.68 m³ / h. 3 / h, of which the maximum working pressure of the high temperature and high pressure oil-gas separator 2 can reach 16MPa, and the maximum working pressure of the low temperature and low pressure oil-gas separator 6 can reach 10MPa.

[0045] In this embodiment, the air-cooling exchange unit 3 is an air cooler, which has a gas inlet, a gas outlet, a cold water inlet, and a hot water outlet.

[0046] Because the transcritical carbon dioxide cycle system operates at high pressures, and carbon dioxide has excellent heat transfer characteristics and volumetric refrigeration capacity, the gas cooler and evaporator need to be designed to be more compact and efficient. According to the device design requirements, the outlet temperature of compressor 1 can reach over 100℃, which is reduced to below 30℃ after heat exchange, and the inlet water temperature should not exceed 25℃. Based on these conditions, the gas cooler is selected.

[0047] Based on the compressor 1's cooling power of 450kW and electrical power of 113kW, the maximum heat generated under full-load power conversion is 563kW. In existing technology, the maximum single-unit carbon dioxide air cooler can be selected at 150kW; therefore, four 150kW air coolers are chosen, for a total heat exchange power of 600kW. The maximum operating pressure of the downhole mobile transcritical carbon dioxide refrigeration and dehumidification device is 10.5MPa. Therefore, the maximum operating pressure of the air cooler is 16MPa, the test pressure is 20MPa, and the operating temperature is no greater than 200℃, meeting the pressure requirements of the downhole mobile transcritical carbon dioxide refrigeration and dehumidification device.

[0048] In this embodiment, the air-cooled exchange unit 7 is an air cooler.

[0049] In this embodiment, the first pressure reducing unit 5 includes three sets of first pressure reducing coils arranged in parallel. The first pressure reducing coils are high-pressure resistant heat-insulating capillary tubes. The first end of the first pressure reducing coil is connected to the gas outlet of the air cooler, and the second end is connected to the air inlet of the air cooler. A first control valve 10 is provided between the first end of each of the multiple first pressure reducing coils and the gas outlet of the air cooler.

[0050] The system employs high-pressure resistant insulated capillary tubes (pressure reducing coils) to reduce pressure, reaching the critical pressure for carbon dioxide gas-liquid phase change. The first pressure reducing unit 5 is designed with three sets of insulated capillary tubes (two in use and one as a backup), with a single set having a pressure reducing capacity of 4.5-5 MPa.

[0051] The second pressure reducing unit 8 is a set of second pressure reducing coils. The second pressure reducing coils are high-pressure resistant heat-insulating capillary tubes. The first end of the second pressure reducing coil is connected to the high-temperature and high-pressure liquid separation outlet, and the second end of the second pressure reducing coil is connected to the first oil inlet of the low-temperature and low-pressure oil-gas separator 6. A second control valve 9 is provided between the second end of the second pressure reducing coil and the first oil inlet of the low-temperature and low-pressure oil-gas separator 6.

[0052] Specifically, the first pressure reducing coil has 3 turns of 260mm; the second pressure reducing coil has 2 turns of 260mm.

[0053] The downhole mobile transcritical carbon dioxide refrigeration and dehumidification device provided in this embodiment is equipped with an automatic control system. The control core components collect parameters such as pressure, temperature, and oil level of the system. It has functions such as display, analysis and control, setting, alarm, and emergency stop. It can display the operating status and various parameters in real time, and data records and alarm records can be viewed at any time.

[0054] The working principle of the downhole mobile transcritical carbon dioxide refrigeration and dehumidification device provided in this embodiment is as follows:

[0055] The compressor 1 in the device continuously draws in CO2 vapor from the evaporator outlet, compresses the CO2 vapor to a high temperature and high pressure state, and then enters the gas cooler. After being cooled in the gas cooler, the CO2 passes through the throttling valve to produce a throttling effect. The low-pressure CO2 after throttling evaporates in the evaporator to produce a refrigeration effect, thus completing the refrigeration cycle.

[0056] The device implements closed-loop control of carbon dioxide, which circulates internally after being filled. It is continuously pressurized by compressor 1, then transported through a high-temperature, high-pressure oil separator, heat exchange components (air cooler), and pressure reducing coil to the air cooler for heat exchange with the air. The carbon dioxide, after absorbing heat and vaporizing, returns to the compressor unit via a low-temperature, low-pressure oil-gas separator 6.

[0057] This device utilizes the characteristic and principle that carbon dioxide can absorb a large amount of heat during the phase change process from liquid to gaseous under supercritical and subcritical conditions of high pressure and high temperature, and low pressure and low temperature. Through the control of carbon dioxide transcritical and phase change states, safety protection under high pressure, and the design and selection of related supporting equipment, it is made suitable for downhole applications.

[0058] By analyzing the cooling capacity, carbon dioxide circulation rate, and safe carbon dioxide leakage release rate of the underground mobile transcritical carbon dioxide refrigeration and dehumidification device, a reasonable parameter matching can be identified. Protective measures and control points can be added to weak links to ensure the safety of the unit equipment when used underground.

[0059] The successful application of this device has greatly improved the comfort of workers at the working face, improved the underground working environment, protected the occupational health of employees, increased production efficiency, reduced operating costs, and contributed significantly to energy conservation and emission reduction. It has significant demonstrative value and widespread application potential in the mining industry, contributing to my country's "dual carbon" utilization. It will also bring huge benefits to the company, promoting its growth into a leading enterprise in domestic coal mine refrigeration technology.

[0060] According to incomplete statistics, there are approximately 1,200 high-temperature mining faces in China, and the stock of special explosion-proof refrigeration devices for mining exceeds 1,200 units, which can generate economic benefits of over 6 billion yuan.

[0061] The technical solutions of the present invention have been fully described above. It should be noted that the specific embodiments of the present invention are not limited to the above description. All technical solutions formed by those skilled in the art based on the spirit and essence of the present invention through equivalent or equivalent transformations in structure, method or function are within the protection scope of the present invention.

Claims

1. A mobile downhole transcritical carbon dioxide refrigeration and dehumidification device, characterized in that, include: At least one compressor, wherein the compressor is a semi-hermetic reciprocating compressor, and the working medium of the compressor is carbon dioxide; the compressor has an air inlet, a high-temperature and high-pressure gas outlet, and a lubricating and cooling oil inlet. A high-temperature and high-pressure oil-gas separator is connected to the high-temperature and high-pressure gas outlet of the compressor and is used to separate the high-temperature and high-pressure oil-gas mixture generated by the compressor into gas and liquid components. An air-cooling exchange unit is provided, the input end of which is connected to the high-temperature and high-pressure gas output end of the high-temperature and high-pressure oil-gas separator, for cooling the high-temperature and high-pressure gas output from the high-temperature and high-pressure oil-gas separator. The first pressure reduction unit is connected to the gas output terminal of the gas-cooled exchange unit after cooling, and is used to reduce the pressure of the gas after cooling by the gas-cooled exchange unit. An air-cooled exchange unit is located downhole and is connected to the gas output terminal of the first depressurization unit after depressurization. The air-cooled exchange unit is used to exchange heat with the downhole to reduce the temperature and humidity downhole and output a low-pressure, low-temperature oil-gas mixture. A low-temperature, low-pressure oil-gas separator is provided. The input end of the low-temperature, low-pressure oil-gas separator is connected to the output end of the air-cooled heat exchange unit after heat exchange. The output end of the low-temperature, low-pressure oil-gas separator is connected to the air inlet of the compressor. The low-temperature, low-pressure oil-gas separator is used to separate the low-pressure, low-temperature oil-gas mixture output from the air-cooled heat exchange unit into gas and liquid. The separated carbon dioxide gas is then delivered to the compressor. The high-temperature and high-pressure oil-gas separator is a centrifugal separator; the high-temperature and high-pressure oil-gas separator has a high-temperature and high-pressure gas-liquid separation inlet, a high-temperature and high-pressure gas separation outlet, and a high-temperature and high-pressure liquid separation outlet. The high-temperature and high-pressure gas-liquid separation inlet is connected to the high-temperature and high-pressure gas outlet, and the high-temperature and high-pressure gas separation outlet is connected to the input end of the gas-cooling exchange unit; the high-temperature and high-pressure liquid separation outlet is connected to the first oil inlet of the low-temperature and low-pressure oil-gas separator through a second pressure reducing unit. The low-temperature and low-pressure oil-gas separator is a centrifugal separator. The low-temperature and low-pressure oil-gas separator has a low-temperature and low-pressure gas-liquid separation inlet, a low-temperature and low-pressure gas separation outlet and a low-temperature and low-pressure liquid separation outlet. The low-temperature and low-pressure gas-liquid separation inlet is connected to the gas output end of the first pressure reducing unit after pressure reduction. The low-temperature, low-pressure gas separation outlet is connected to the air inlet of the compressor; the low-temperature, low-pressure liquid separation outlet is connected to the input end of the oil pump through a first connecting pipe, and the output end of the oil pump is connected to the lubricating and cooling oil inlet of the compressor through a second connecting pipe; a connecting branch is connected to the second connecting pipe, and the other end of the connecting branch is connected to the second oil inlet of the low-temperature, low-pressure oil-gas separator; a manual valve is provided on the connecting branch.

2. The downhole mobile transcritical carbon dioxide refrigeration and dehumidification device according to claim 1, characterized in that, There are two compressors, and the parameters of the compressors are as follows: The exhaust volume is 45.34m³. 3 / h; cooling capacity is 225kW; power is 55kW; speed is 1450r / min; maximum working pressure is 15MPa; static pressure is 10MPa; voltage rating is 380V, 3-phase, 50HZ; maximum working current is 148A, stall current is 584A; continuous operating current is 115A; maximum working temperature is 160℃; ambient temperature is -20℃~60℃.

3. The downhole mobile transcritical carbon dioxide refrigeration and dehumidification device according to claim 1, characterized in that, The air-cooled exchange unit is an air cooler, which has a gas inlet, a gas outlet, a cold water inlet, and a hot water outlet; the total heat exchange power of the air cooler is 600kW, the maximum working pressure is 10.5MPa, the maximum working pressure is 16MPa, the test pressure is 20MPa, and the working temperature is ≤200℃.

4. The downhole mobile transcritical carbon dioxide refrigeration and dehumidification device according to claim 3, characterized in that, The air-cooled exchange unit is an air cooler.

5. The downhole mobile transcritical carbon dioxide refrigeration and dehumidification device according to claim 4, characterized in that, The first pressure reducing unit includes multiple sets of first pressure reducing coils arranged in parallel. The first pressure reducing coil is a high-pressure resistant heat-insulating capillary tube. The first end of the first pressure reducing coil is connected to the gas outlet of the air cooler, and the second end is connected to the air inlet of the air cooler. A control valve is provided between the first end of each of the multiple first pressure reducing coils and the gas outlet of the air cooler. The second pressure reducing unit is a set of second pressure reducing coils, which are high-pressure resistant heat-insulating capillary tubes. The first end of the second pressure reducing coil is connected to the high-temperature and high-pressure liquid separation outlet, and the second end of the second pressure reducing coil is connected to the first oil inlet of the low-temperature and low-pressure oil-gas separator. A control valve is provided between the second end of the second pressure reducing coil and the first oil inlet of the low-temperature and low-pressure oil-gas separator.

6. The downhole mobile transcritical carbon dioxide refrigeration and dehumidification device according to claim 5, characterized in that, The first pressure reducing coil has 3 turns of 260mm; the second pressure reducing coil has 2 turns of 260mm.

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