Carbon dioxide recovery cascade refrigeration system

Abstract

This invention provides a carbon dioxide recovery cascade refrigeration system, including a circulation loop and a first heat exchanger, a compressor, a condenser, and a first oil drain pipe disposed on the circulation loop. The circulation loop is used for the flow of carbon dioxide heat exchange medium. The first heat exchanger has independent first and second heat exchange channels. The first heat exchange channel has a first inlet and a first outlet. The second heat exchange channel has a second inlet and a second outlet respectively connected to the circulation loop. The carbon dioxide heat exchange medium in the second heat exchange channel is used to reduce the temperature of the medium in the first heat exchange channel. An oil drain port is provided at the bottom of the first heat exchange channel. The gas inlet of the compressor is connected to the second outlet of the first heat exchanger. The condenser is located downstream of the compressor and is used to condense the carbon dioxide heat exchange medium after compression by the compressor. The oil drain port is connected to the inlet of the compressor through the first oil drain pipe. This system uses carbon dioxide as the heat exchange medium, resulting in low cost.

Description

Technical Field

[0001] This utility model relates to the field of refrigeration system technology, and more specifically, to a carbon dioxide recovery cascade refrigeration system. Background Technology

[0002] Carbon dioxide is a key component of beer, giving it its characteristic bubbles and smooth texture. Furthermore, carbon dioxide effectively reduces dissolved oxygen in beer, preventing oxidation and extending its shelf life. Because liquid carbon dioxide has a higher density and storage efficiency, making it easy to transport and store, recovered gaseous carbon dioxide is typically liquefied using a refrigeration system and stored in high-pressure tanks during beer production.

[0003] Typically, breweries use Freon as a refrigerant in their refrigeration systems for carbon dioxide recovery. However, Freon's manufacturing process is relatively complex and its manufacturing cost is high. Furthermore, Freon refrigeration systems have a large leakage rate, resulting in significant carbon emissions. Utility Model Content

[0004] This invention provides a carbon dioxide recovery cascade refrigeration system to solve the problem that existing brewery refrigeration systems use Freon as a refrigerant, which is costly.

[0005] This invention provides a carbon dioxide recovery cascade refrigeration system. The system includes a circulation loop and a first heat exchanger, a compressor, a condenser, and a first oil drain pipe disposed on the circulation loop. The circulation loop is used for the flow of carbon dioxide heat exchange medium. The first heat exchanger has independent first and second heat exchange channels. The first heat exchange channel has a first inlet and a first outlet, and the second heat exchange channel has a second inlet and a second outlet. The second inlet and the second outlet are respectively connected to the circulation loop. The carbon dioxide heat exchange medium in the second heat exchange channel is used for heat exchange with the medium in the first heat exchange channel to reduce the temperature of the medium in the first heat exchange channel. An oil drain port is also provided at the bottom of the first heat exchange channel. The compressor is located downstream of the first heat exchanger, and the gas inlet of the compressor is connected to the second outlet of the first heat exchanger. The condenser is located downstream of the compressor and is used to condense the carbon dioxide heat exchange medium after compression by the compressor. One end of the first oil drain pipe is connected to the oil drain port, and the other end is connected to the gas inlet of the compressor, so that the oil in the first heat exchange channel is discharged into the compressor.

[0006] Furthermore, the carbon dioxide recovery cascade refrigeration system also includes: a second heat exchanger, located downstream of the condenser section, the second heat exchanger having independent third and fourth heat exchange channels, the third heat exchange channel having a third inlet and a third outlet, and the fourth heat exchange channel having a fourth inlet and a fourth outlet; the third inlet is connected to the circulation loop so that the condensed carbon dioxide heat exchange medium flows through the third inlet into the third heat exchange channel, and the third outlet is connected to the second inlet; the first oil drain pipe is connected to the gas inlet of the compressor through the fourth heat exchange channel; wherein, the carbon dioxide heat exchange medium in the third heat exchange channel exchanges heat with the oil in the fourth heat exchange channel to reduce the temperature of the oil in the fourth heat exchange channel.

[0007] Furthermore, the circulation loop includes: a first branch and a second branch, the first branch and the second branch are connected in parallel, one end of the first branch and the second branch are both connected to the third outlet, and the other end of the first branch and the second branch are both connected to the second inlet; a first shut-off valve is provided on the first branch; a second shut-off valve and a switch are both provided on the second branch.

[0008] Furthermore, the carbon dioxide recovery cascade refrigeration system also includes an oil-gas separation section, which is located on the circulation loop. The oil-gas separation section is located downstream of the compressor and upstream of the condenser section. The exhaust port of the compressor is connected to the inlet of the oil-gas separation section, and the exhaust port of the oil-gas separation section is connected to the circulation loop.

[0009] Furthermore, the oil-gas separator has an oil outlet, and the compressor has an oil return port. The oil outlet and the oil return port are connected so that the oil separated by the oil-gas separator flows into the compressor through the oil return port.

[0010] Furthermore, the condenser section has a fifth heat exchange channel and a sixth heat exchange channel that are independent of each other. The fifth heat exchange channel has a fifth inlet and a fifth outlet, and is used for refrigerant circulation. The sixth heat exchange channel has a sixth inlet and a sixth outlet. The sixth inlet is connected to the exhaust port of the oil-gas separation section, and the sixth outlet is connected to the third inlet. The refrigerant in the fifth heat exchange channel exchanges heat with the carbon dioxide heat exchange medium in the sixth heat exchange channel to condense the carbon dioxide heat exchange medium in the sixth heat exchange channel.

[0011] Furthermore, the carbon dioxide recovery cascade refrigeration system also includes: a liquid storage section located downstream of the condenser section, the liquid storage section having a seventh inlet and a seventh outlet, the seventh inlet being connected to the sixth outlet, and the seventh outlet being connected to the third inlet.

[0012] Furthermore, the carbon dioxide recovery cascade refrigeration system also includes a throttling device, which is installed on the circulation loop. The throttling device is located downstream of the condenser and upstream of the second heat exchanger. The throttling device is used to throttle the carbon dioxide heat exchange medium after passing through the condenser.

[0013] Furthermore, the first heat exchanger includes: a shell, a second inlet, a second outlet, and an oil drain outlet, all of which are disposed on the shell and communicate with the internal space of the shell respectively. The oil drain outlet is disposed at the bottom of the shell so that the oil is discharged from the oil drain outlet under the action of gravity; and a heat exchange tube, which is inserted into the shell. The heat exchange tube has a first inlet, a first heat exchange channel, and a first outlet. The space between the heat exchange tube and the shell forms a second heat exchange channel.

[0014] Furthermore, multiple compressors are provided, and these compressors are connected in parallel.

[0015] The present invention utilizes carbon dioxide as the heat exchange medium in a carbon dioxide recovery cascade refrigeration system, which is less expensive than the traditional method using Freon. Furthermore, this design avoids the problems associated with Freon-based refrigerants, such as large leaks and high carbon emissions.

[0016] Specifically, the gaseous carbon dioxide produced by the brewery is refrigerated by a carbon dioxide recovery cascade refrigeration system, transformed into liquid carbon dioxide, and then stored in a storage tank. Specifically, the gaseous carbon dioxide produced by the brewery enters the first heat exchange channel of the first heat exchanger through the first inlet. The carbon dioxide heat exchange medium in the carbon dioxide recovery cascade refrigeration system circulates in a loop. After being condensed by the condenser, the carbon dioxide heat exchange medium enters the second heat exchange channel of the first heat exchanger and exchanges heat with the gaseous carbon dioxide in the first heat exchange channel, causing the gaseous carbon dioxide in the first heat exchange channel to be converted into liquid carbon dioxide, which is then stored in the storage tank through the first outlet.

[0017] In a carbon dioxide recovery cascade refrigeration system, during the refrigeration process, oil in the compressor may flow along with the carbon dioxide heat exchange medium into the circulation loop and the second heat exchange channel of the first heat exchanger. Under gravity, the oil in the second heat exchange channel of the first heat exchanger will accumulate at the bottom. In this design, the oil accumulated in the second heat exchange channel is diverted to the gas inlet of the compressor via a first oil drain pipe. This reduces the impact of the oil on the heat exchange efficiency of the first heat exchanger, improves the refrigeration efficiency of the carbon dioxide recovery cascade refrigeration system, reduces its energy consumption, and lowers its operating costs. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0019] Figure 1A schematic diagram of the refrigeration system provided by this utility model is shown.

[0020] The above figures include the following reference numerals:

[0021] 10. First heat exchanger; 101. First inlet; 102. First outlet; 103. Second inlet; 104. Second outlet; 105. Oil drain port;

[0022] 20. Compressor;

[0023] 30. Condensation section; 301. Fifth inlet; 302. Fifth outlet; 303. Sixth inlet; 304. Sixth outlet;

[0024] 40. First row of oil pipes;

[0025] 50. Second heat exchanger; 501. Third inlet; 502. Third outlet; 503. Fourth inlet; 504. Fourth outlet;

[0026] 61. First branch; 611. First shut-off valve;

[0027] 62. Second branch; 621. Second shut-off valve; 622. Switch;

[0028] 70. Oil-gas separation unit; 71. Second oil drain pipe;

[0029] 80. Liquid storage part;

[0030] 90. Throttling components. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0032] like Figure 1As shown, this utility model embodiment provides a carbon dioxide recovery cascade refrigeration system. The carbon dioxide recovery cascade refrigeration system includes a circulation loop and a first heat exchanger 10, a compressor 20, a condenser 30, and a first oil drain pipe 40 disposed on the circulation loop. The circulation loop is used for the flow of carbon dioxide heat exchange medium. The first heat exchanger 10 has a first heat exchange channel and a second heat exchange channel that are independent of each other. The first heat exchange channel has a first inlet 101 and a first outlet 102, and the second heat exchange channel has a second inlet 103 and a second outlet 104. The second inlet 103 and the second outlet 104 are respectively connected to the circulation loop. The second heat exchange channel contains... Carbon dioxide heat exchange medium is used for heat exchange with the medium in the first heat exchange channel to reduce the temperature of the medium in the first heat exchange channel. An oil drain port 105 is also provided at the bottom of the first heat exchange channel. The compressor 20 is located downstream of the first heat exchanger 10, and the gas inlet of the compressor 20 is connected to the second outlet 104 of the first heat exchanger 10. A condenser section 30 is located downstream of the compressor 20 and is used to condense the carbon dioxide heat exchange medium after compression by the compressor 20. One end of the first oil drain pipe 40 is connected to the oil drain port 105, and the other end is connected to the gas inlet of the compressor 20, so that the oil in the first heat exchange channel is discharged into the compressor 20. Figure 1 The arrows in the diagram indicate the direction of fluid flow.

[0033] The present invention utilizes carbon dioxide as the heat exchange medium in a carbon dioxide recovery cascade refrigeration system, which is less expensive than the traditional method using Freon. Furthermore, this design avoids the problems associated with Freon-based refrigerants, such as large leaks and high carbon emissions.

[0034] Specifically, the gaseous carbon dioxide produced by the brewery is refrigerated by a carbon dioxide recovery cascade refrigeration system, transformed into liquid carbon dioxide, and then stored in a storage tank. Specifically, the gaseous carbon dioxide produced by the brewery enters the first heat exchange channel of the first heat exchanger 10 through the first inlet. The carbon dioxide heat exchange medium in the carbon dioxide recovery cascade refrigeration system circulates in a loop. After being condensed by the condenser 30, the carbon dioxide heat exchange medium enters the second heat exchange channel of the first heat exchanger 10 and exchanges heat with the gaseous carbon dioxide in the first heat exchange channel, causing the gaseous carbon dioxide in the first heat exchange channel to be converted into liquid carbon dioxide and stored in the storage tank through the first outlet.

[0035] In the carbon dioxide recovery cascade refrigeration system, during the refrigeration process, the oil inside the compressor 20 may flow along with the carbon dioxide heat exchange medium into the circulation loop and the second heat exchange channel of the first heat exchanger 10. Under the influence of gravity, the oil in the second heat exchange channel of the first heat exchanger 10 will accumulate at the bottom. In this design, the oil accumulated in the second heat exchange channel is diverted to the gas inlet of the compressor 20 via the first oil drain pipe 40. This reduces the impact of the oil on the heat exchange efficiency of the first heat exchanger 10, improves the refrigeration efficiency of the carbon dioxide recovery cascade refrigeration system, reduces its energy consumption, and lowers its operating costs.

[0036] Furthermore, the carbon dioxide recovery cascade refrigeration system also includes a second heat exchanger 50, which is located downstream of the condenser section 30. The second heat exchanger 50 has a third heat exchange channel and a fourth heat exchange channel that are independent of each other. The third heat exchange channel has a third inlet 501 and a third outlet 502, and the fourth heat exchange channel has a fourth inlet 503 and a fourth outlet 504. The third inlet 501 is connected to the circulation loop so that the condensed carbon dioxide heat exchange medium flows through the third inlet 501 into the third heat exchange channel. The third outlet 502 is connected to the second inlet 103. The first oil drain pipe 40 is connected to the gas inlet of the compressor 20 through the fourth heat exchange channel. The carbon dioxide heat exchange medium in the third heat exchange channel exchanges heat with the oil in the fourth heat exchange channel to reduce the temperature of the oil in the fourth heat exchange channel. The carbon dioxide heat exchange medium in the third heat exchange channel exchanges heat with the oil in the fourth heat exchange channel, allowing the cooled oil to enter the gas inlet of the compressor 20. By reducing the oil temperature, friction and heat accumulation inside the compressor 20 can be reduced, thereby improving the compressor's operating efficiency. Furthermore, by reducing the oil temperature, thermal damage to compressor components caused by high temperatures is reduced, extending the compressor's service life.

[0037] It is understandable that the heat exchange process described above has a low impact on the temperature of the carbon dioxide heat exchange medium in the third heat exchange channel, which is sufficient to ensure that the carbon dioxide heat exchange medium in the third heat exchange channel enters the first heat exchange channel of the first heat exchanger 10 and condenses the gaseous carbon dioxide in the first heat exchange channel.

[0038] In this embodiment, the circulation loop includes a first branch 61, a second branch 62, a first shut-off valve 611, a second shut-off valve 621, and a switch 622. The first branch 61 and the second branch 62 are connected in parallel, with one end of each branch connected to the third outlet 502 and the other end connected to the second inlet 103. The first shut-off valve 611 is located on the first branch 61; the second shut-off valve 621 and the switch 622 are both located on the second branch 62. This configuration enhances the flexibility of the solution, allowing the first branch 61 and the second branch 62 to operate simultaneously, or for only one of them to be operational. Furthermore, when the first branch 61 malfunctions, the first shut-off valve 611 can be closed, the switch 622 activated, and the second shut-off valve 621 adjusted.

[0039] Furthermore, the carbon dioxide recovery cascade refrigeration system also includes an oil-gas separator 70, which is located on the circulation loop, downstream of the compressor 20 and upstream of the condenser 30. The exhaust port of the compressor 20 is connected to the inlet of the oil-gas separator 70, and the exhaust port of the oil-gas separator 70 is connected to the circulation loop. Located downstream of the compressor 20, the oil-gas separator 70 can separate the oil from the oil-gas mixture discharged from the compressor, reducing the amount of oil entering the circulation loop and participating in the circulation. This reduces the possibility of blockage in the carbon dioxide recovery cascade refrigeration system, improves its stability, extends its service life, reduces its power consumption, and improves its refrigeration efficiency.

[0040] Furthermore, the oil-gas separator 70 has an oil outlet, and the compressor 20 has an oil return port. The oil outlet and the oil return port are connected so that the oil separated by the oil-gas separator 70 flows into the compressor 20 through the oil return port. By separating the oil from the oil-gas mixture and returning the oil to the compressor 20 through the oil return port, the oil-gas separator 70 ensures that the compressor 20 is always in a good lubricated state, improving the stability and smoothness of the compressor 20's operation.

[0041] Specifically, the carbon dioxide recovery cascade refrigeration system also includes a second oil drain pipe 71, one end of which is connected to the oil return port of the compressor 20, and the other end is connected to the oil outlet of the oil-gas separation unit 70.

[0042] In this embodiment, the condenser 30 has a fifth heat exchange channel and a sixth heat exchange channel that are independent of each other. The fifth heat exchange channel has a fifth inlet 301 and a fifth outlet 302, and is used for refrigerant circulation. The sixth heat exchange channel has a sixth inlet 303 and a sixth outlet 304. The sixth inlet 303 is connected to the exhaust port of the oil-gas separation section 70, and the sixth outlet 304 is connected to the third inlet 501. The refrigerant in the fifth heat exchange channel exchanges heat with the carbon dioxide heat exchange medium in the sixth heat exchange channel to condense the carbon dioxide heat exchange medium in the sixth heat exchange channel. This configuration is simple in structure and facilitates the condensation of the carbon dioxide heat exchange medium in the sixth heat exchange channel.

[0043] Ethylene glycol can be introduced into the fifth heat exchange channel of the condenser section 30. Ethylene glycol has excellent thermal conductivity and a low freezing point, enabling it to operate stably over a wide temperature range. By introducing ethylene glycol into the fifth heat exchange channel, the heat released by the carbon dioxide heat exchange medium in the sixth heat exchange channel can be effectively absorbed, thus achieving a highly efficient condensation process. Furthermore, ethylene glycol is an environmentally friendly refrigerant with minimal environmental impact.

[0044] The condenser section 30 can be a high-pressure heat exchanger, specifically a shell-and-tube condenser. This design makes the condenser section 30 suitable for high-pressure and high-heat-exchange-efficiency applications.

[0045] In some embodiments of this solution, an independent gas-liquid separation device is configured on the evaporation side of the condenser 30, that is, on the side where the fifth heat exchange channel of the condenser 30 is located, in order to avoid the risk of liquid slugging.

[0046] Furthermore, the carbon dioxide recovery cascade refrigeration system also includes a liquid storage section 80, located downstream of the condenser section 30. The liquid storage section 80 has a seventh inlet and a seventh outlet; the seventh inlet is connected to the sixth outlet 304, and the seventh outlet is connected to the third inlet 501. By providing the liquid storage section 80, liquid carbon dioxide condensed by the condenser section 30 can be stored. When the system load changes, the liquid storage section 80 can store excess liquid refrigerant. The introduction of the liquid storage section 80 into the carbon dioxide recovery cascade refrigeration system provides the system with liquid storage, buffering, and stable liquid supply functions. In other words, by compensating for load changes, reducing liquid level fluctuations in the condenser section 30, and optimizing system operation, the liquid storage section 80 significantly improves the stability and operating efficiency of the carbon dioxide recovery cascade refrigeration system.

[0047] Specifically, the liquid refrigerant flows out from the sixth outlet 304 of the condenser 30 and enters the seventh inlet of the liquid storage section 80. In the liquid storage section 80, the refrigerant is stored and buffered, and then flows through the seventh outlet to the third inlet 501 of the second heat exchanger 50.

[0048] Furthermore, the carbon dioxide recovery cascade refrigeration system also includes a throttling element 90, which is located in the circulation loop, downstream of the condenser section 30 and upstream of the second heat exchanger 50. The throttling element 90 is used to throttle the carbon dioxide heat exchange medium after passing through the condenser section 30. By optimizing the throttling process, the throttling element 90 can reduce ineffective energy consumption in the system. Precise control of flow rate and pressure can prevent excessive circulation of the carbon dioxide heat exchange medium, thereby reducing the load on the compressor 20, improving the overall energy efficiency ratio of the system, and reducing operating costs.

[0049] In this embodiment, the first heat exchanger 10 includes a shell and heat exchange tubes. The second inlet 103, the second outlet 104, and the oil drain 105 are all disposed on the shell and communicate with the internal space of the shell. The oil drain 105 is disposed at the bottom of the shell so that the oil is discharged from the oil drain 105 under the action of gravity. The heat exchange tubes are inserted into the shell and have a first inlet 101, a first heat exchange channel, and a first outlet 102. The space between the heat exchange tubes and the shell forms a second heat exchange channel.

[0050] Furthermore, multiple compressors 20 are configured and connected in parallel. Parallel operation of multiple compressors 20 significantly improves system reliability. Even if one compressor 20 fails, the others can continue operating, ensuring the carbon dioxide recovery cascade refrigeration system does not completely shut down. Moreover, the parallel operation of multiple compressors 20 allows for selection of the optimal operating combination based on actual needs, thereby optimizing the overall energy efficiency ratio of the system.

[0051] In summary, the carbon dioxide recovery cascade refrigeration system of this scheme is used to condense gaseous carbon dioxide produced by the brewery. Specifically, the gaseous carbon dioxide produced by the brewery is transported to the storage tank through the first heat exchange channel of the first heat exchanger 10. The carbon dioxide recovery cascade refrigeration system uses carbon dioxide as the heat exchange medium. The gaseous carbon dioxide in the first heat exchange channel is in a low-temperature gas-liquid mixed state in the second heat exchange channel of the first heat exchanger 10, and the gaseous carbon dioxide in the first heat exchange channel is converted into liquid carbon dioxide.

[0052] When the carbon dioxide heat exchange medium circulates in the loop, the low-temperature carbon dioxide heat exchange medium in the second heat exchange channel, which is in a gas-liquid mixed state, exchanges heat with the gaseous carbon dioxide in the first heat exchange channel, so as to condense the gaseous carbon dioxide in the first heat exchange channel into liquid carbon dioxide for storage in the storage tank.

[0053] The second heat exchange channel outputs gaseous carbon dioxide heat exchange medium, which flows to the compressor 20 through the circulation loop. After being compressed by the compressor 20, the pressure and temperature of the carbon dioxide heat exchange medium increase significantly, transforming into a high temperature and high pressure state.

[0054] The compressed carbon dioxide heat exchange medium enters the oil-gas separation section 70. The function of the oil-gas separation section 70 is to separate the oil from the oil-gas mixture discharged from the compressor 20. The separated oil returns to the compressor 20 through the second oil drain pipe 71, while the pure carbon dioxide heat exchange medium continues to flow to the condenser section 30. This process ensures that the carbon dioxide entering the condenser section 30 does not contain oil, thereby avoiding the influence of oil on the heat exchange efficiency. The separated carbon dioxide heat exchange medium enters the sixth heat exchange channel of the condenser section 30. During this process, the carbon dioxide heat exchange medium in the sixth heat exchange channel exchanges heat with the refrigerant in the fifth heat exchange channel of the condenser section 30, so that the carbon dioxide heat exchange medium changes from a high-temperature and high-pressure supercritical state to a high-pressure liquid state.

[0055] After the liquid carbon dioxide flows out of the condenser 30, it enters the liquid storage section 80. The liquid storage section 80 stores the condensed liquid carbon dioxide heat exchange medium to compensate for the demand of refrigerant circulation due to changes in system load, and further optimizes the operating efficiency of the system.

[0056] After the liquid carbon dioxide flows out from the liquid storage section 80, it enters the throttling device 90. The throttling device 90 reduces the pressure and temperature of the high-pressure liquid carbon dioxide through the throttling effect.

[0057] The gas-liquid mixed carbon dioxide heat exchange medium, after being throttled, enters the third heat exchange channel of the second heat exchanger 50 through the third inlet. The oil discharged from the second heat exchange channel of the first heat exchanger 10 flows into the fourth heat exchange channel of the second heat exchanger 50. At this time, the oil in the fourth heat exchange channel, after being cooled, flows into the compressor 20. The gas-liquid mixed carbon dioxide heat exchange medium in the third heat exchange channel flows into the second heat exchange channel of the first heat exchanger 10.

[0058] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0059] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as exemplary only and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0060] In the description of this utility model, it should be understood that the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this utility model. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0061] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0062] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this utility model.

[0063] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A carbon dioxide recovery cascade refrigeration system, characterized in that, The carbon dioxide recovery cascade refrigeration system includes a circulation loop and a first heat exchanger (10), a compressor (20), a condenser (30), and a first oil drain pipe (40) disposed on the circulation loop. The circulation loop is used for the flow of carbon dioxide heat exchange medium. The first heat exchanger (10) has a first heat exchange channel and a second heat exchange channel that are independent of each other. The first heat exchange channel has a first inlet (101) and a first outlet (102), and the second heat exchange channel has a second inlet (103) and a second outlet (104). The second inlet (103) and the second outlet (104) are respectively connected to the circulation loop. The carbon dioxide heat exchange medium in the second heat exchange channel is used to exchange heat with the medium in the first heat exchange channel to reduce the temperature of the medium in the first heat exchange channel. An oil drain (105) is also provided at the bottom of the first heat exchange channel. The compressor (20) is located downstream of the first heat exchanger (10), and the gas inlet of the compressor (20) is connected to the second outlet (104) of the first heat exchanger (10). The condenser (30) is located downstream of the compressor (20), and the condenser (30) is used to condense the carbon dioxide heat exchange medium after it has been compressed by the compressor (20). One end of the first oil drain pipe (40) is connected to the oil drain port (105), and the other end is connected to the gas inlet of the compressor (20) so that the oil in the first heat exchange channel is discharged into the compressor (20).

2. The carbon dioxide recovery cascade refrigeration system according to claim 1, characterized in that, The carbon dioxide recovery cascade refrigeration system also includes: The second heat exchanger (50) is located downstream of the condenser section (30). The second heat exchanger (50) has a third heat exchange channel and a fourth heat exchange channel that are independent of each other. The third heat exchange channel has a third inlet (501) and a third outlet (502), and the fourth heat exchange channel has a fourth inlet (503) and a fourth outlet (504). The third inlet (501) is connected to the circulation loop so that the condensed carbon dioxide heat exchange medium flows through the third inlet (501) into the third heat exchange channel. The third outlet (502) is connected to the second inlet (103). The first oil drain pipe (40) is connected to the gas inlet of the compressor (20) through the fourth heat exchange channel. In this process, the carbon dioxide heat exchange medium in the third heat exchange channel exchanges heat with the oil in the fourth heat exchange channel to reduce the temperature of the oil in the fourth heat exchange channel.

3. The carbon dioxide recovery cascade refrigeration system according to claim 2, characterized in that, The loop includes: The first branch (61) and the second branch (62) are connected in parallel. One end of the first branch (61) and the second branch (62) are connected to the third outlet (502), and the other end of the first branch (61) and the second branch (62) are connected to the second inlet (103). The first shut-off valve (611) is installed on the first branch (61); The second shut-off valve (621) and the switch (622) are both installed on the second branch (62).

4. The carbon dioxide recovery cascade refrigeration system according to claim 2, characterized in that, The carbon dioxide recovery cascade refrigeration system also includes: An oil-gas separator (70) is provided on the circulation loop. The oil-gas separator (70) is located downstream of the compressor (20) and upstream of the condenser (30). The exhaust port of the compressor (20) is connected to the air inlet of the oil-gas separator (70), and the exhaust port of the oil-gas separator (70) is connected to the circulation loop.

5. The carbon dioxide recovery cascade refrigeration system according to claim 4, characterized in that, The oil-gas separator (70) has an oil outlet, and the compressor (20) has an oil return port. The oil outlet is connected to the oil return port so that the oil separated by the oil-gas separator (70) flows into the compressor (20) through the oil return port.

6. The carbon dioxide recovery cascade refrigeration system according to claim 4, characterized in that, The condenser (30) has a fifth heat exchange channel and a sixth heat exchange channel that are independent of each other. The fifth heat exchange channel has a fifth inlet (301) and a fifth outlet (302) and is used for refrigerant circulation. The sixth heat exchange channel has a sixth inlet (303) and a sixth outlet (304). The sixth inlet (303) is connected to the exhaust port of the oil-gas separator (70), and the sixth outlet (304) is connected to the third inlet (501). The refrigerant in the fifth heat exchange channel exchanges heat with the carbon dioxide heat exchange medium in the sixth heat exchange channel to condense the carbon dioxide heat exchange medium in the sixth heat exchange channel.

7. The carbon dioxide recovery cascade refrigeration system according to claim 6, characterized in that, The carbon dioxide recovery cascade refrigeration system also includes: The liquid storage section (80) is located downstream of the condenser section (30). The liquid storage section (80) has a seventh inlet and a seventh outlet. The seventh inlet is connected to the sixth outlet (304), and the seventh outlet is connected to the third inlet (501).

8. The carbon dioxide recovery cascade refrigeration system according to claim 2, characterized in that, The carbon dioxide recovery cascade refrigeration system also includes: A throttling element (90) is provided on the circulation loop. The throttling element (90) is located downstream of the condenser (30) and upstream of the second heat exchanger (50). The throttling element (90) is used to throttle the carbon dioxide heat exchange medium after passing through the condenser (30).

9. The carbon dioxide recovery cascade refrigeration system according to claim 1, characterized in that, The first heat exchanger (10) includes: The housing, the second inlet (103), the second outlet (104) and the oil drain (105) are all provided on the housing and communicate with the internal space of the housing respectively. The oil drain (105) is provided at the bottom of the housing so that the oil is discharged from the oil drain (105) under the action of gravity. A heat exchange tube is inserted into the housing. The heat exchange tube has a first inlet (101), a first heat exchange channel and a first outlet (102). The space between the heat exchange tube and the housing forms a second heat exchange channel.

10. The carbon dioxide recovery cascade refrigeration system according to claim 1, characterized in that, Multiple compressors (20) are provided, and the multiple compressors (20) are connected in parallel.

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