Cold energy recovery subsystem

Abstract

The utility model discloses a cooling capacity recovery subsystem, which is used for a polycrystalline silicon waste gas cryogenic recovery system and comprises a dust removal leaching tower, a cooling capacity recovery subsystem, a cooling capacity recovery subsystem and a cooling capacity recovery subsystem, and is characterized in that the dust removal leaching tower is used for condensing silicon powder and chlorosilane in waste gas and discharging low-temperature gas; the primary compressor is used for compressing the low-temperature gas and discharging high-temperature gas; and the cold energy recovery device is arranged between the dust removal leaching tower of the cold energy recovery device and the first-stage compressor of the cold energy recovery device so as to exchange heat with the low-temperature gas. The cooling capacity recovery device is arranged between the dust removal leaching tower and the first-stage compressor, so that heat exchange with low-temperature gas discharged from the dust removal leaching tower is achieved, the temperature of the low-temperature gas is increased, and the temperature of an inlet of the first-stage compressor is increased.

Description

Technical Field

[0001] The utility model relates to the technical field of deep cold recovery of polysilicon waste gas, in particular to a cold recovery subsystem. Background Art

[0002] At present, in the deep cold recovery system for polysilicon processing, the waste gas passes through the dust removal and leaching tower to condense the silicon powder and part of the chlorosilane. The waste gas discharged from the dust removal and leaching tower passes through the inlet buffer tank of the first-stage compressor and the first-stage compressor in turn. After being compressed by the first-stage compressor, it enters the back-end compression group.

[0003] However, the temperature of the exhaust gas discharged from the dust removal and leaching tower is relatively low, usually around -25°C. It is understandable that too low an inlet temperature will affect the service life of the first-stage compressor, and the material of the gas transporting pipeline also needs to meet higher low-temperature resistance requirements.

[0004] In the related art, in order to increase the inlet temperature of the first-stage compressor, the opening of the return valve of the first-stage compressor is controlled at about 15%, so that a small amount of compressed high-temperature gas can return to the inlet and mix with the exhaust gas discharged from the dust removal and leaching tower, which is beneficial to increase the inlet temperature. However, opening the return valve will cause the first-stage compressor to be unable to operate at full load, thereby affecting the working efficiency of the polysilicon processing deep cold recovery system. Utility Model Content

[0005] One purpose of the utility model is to provide a cold recovery subsystem, which can increase the inlet temperature of a first-stage compressor on the basis of making the first-stage compressor run at full load.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is: a cold recovery subsystem, used for a polysilicon waste gas deep cold recovery system, including: a dust removal and leaching tower, used to condense silicon powder and chlorosilane in the waste gas and discharge low-temperature gas; a first-stage compressor, used to compress the low-temperature gas and discharge high-temperature gas; a cold recovery device, arranged between the dust removal and leaching tower and the first-stage compressor, so as to exchange heat with the low-temperature gas.

[0007] Preferably, the cold recovery device comprises a first heat exchanger, which has a first heat exchange tube side and a first heat exchange shell side, one of the first heat exchange tube side and the first heat exchange shell side is connected to the outlet of the dust removal and leaching tower and the inlet of the first-stage compressor, and the other of the first heat exchange tube side and the first heat exchange shell side is connected to the outlet of the first-stage compressor.

[0008] Preferably, the cold energy recovery subsystem further comprises a delivery pipeline, an air inlet pipeline and an air outlet pipeline, wherein the delivery pipeline is used to connect the air outlet of the dust removal and elution tower and the first heat exchange shell side of the first heat exchanger, the air inlet pipeline is used to connect the first heat exchange shell side and the inlet of the first-stage compressor, so that the low-temperature gas enters the first-stage compressor after passing through the first heat exchange shell side, and the air outlet pipeline connects the outlet of the first-stage compressor and the first heat exchange tube side of the first heat exchanger, so as to enable heat exchange with the low-temperature gas in the first heat exchange shell side.

[0009] Preferably, the first heat exchanger is placed vertically so that the low-temperature gas passes through the first heat exchange shell from bottom to top, and the high-temperature gas passes through the first heat exchange tube from top to bottom.

[0010] Preferably, the cold recovery device comprises a first jacket pipe, an air inlet pipe and an air outlet pipe, the air inlet pipe is used to connect the air outlet of the dust removal and elution tower and the inlet of the first-stage compressor, the air outlet pipe is connected to the outlet of the first-stage compressor, the first jacket pipe is arranged on the outer peripheral side of the air inlet pipe, so that jacket water can be filled between the first jacket pipe and the air inlet pipe, and the jacket water can exchange heat with the low-temperature gas.

[0011] As a preference, the cold recovery device also includes a second jacket pipe, which is arranged on the outer peripheral side of the gas outlet pipe so that jacket water can be filled between the second jacket pipe and the gas outlet pipe; the first jacket pipe has a high-temperature liquid inlet and a low-temperature liquid outlet, and the second jacket pipe has a low-temperature liquid inlet and a high-temperature liquid outlet, wherein the high-temperature liquid inlet and the high-temperature liquid outlet are connected via a high-temperature return water branch, and the low-temperature liquid outlet and the low-temperature liquid inlet are connected via a low-temperature return water branch.

[0012] Preferably, the cold recovery device further includes a second heat exchanger, the second heat exchanger having a second heat exchange tube side and a second heat exchange shell side, the first jacketed tube having a high-temperature liquid inlet and a low-temperature liquid outlet, wherein one of the second heat exchange tube side and the second heat exchange shell side is connected to the high-temperature liquid inlet and the low-temperature liquid outlet, and the other of the second heat exchange tube side and the second heat exchange shell side is connected to the outlet of the first-stage compressor through the outlet pipe.

[0013] Preferably, the cold energy recovery subsystem further comprises a rear-end compression group, which is connected to the first-stage compressor or the cold energy recovery device and is used for cooling and compressing the high-temperature gas discharged from the first-stage compressor.

[0014] Preferably, the rear-end compression group comprises a third heat exchanger and a secondary compressor in sequence, the third heat exchanger is connected to the primary compressor or the cold recovery device to recover and utilize waste heat of the high-temperature gas, and the secondary compressor is connected to the third heat exchanger to compress the high-temperature gas.

[0015] Preferably, the rear-end compression group further includes an air cooler, which is connected between the third heat exchanger and the first-stage compressor, or between the third heat exchanger and the cold recovery device, and is used to cool the high-temperature gas.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] By setting a cold recovery device between the dust removal and elution tower and the first-stage compressor, heat exchange can be achieved with the low-temperature gas discharged from the dust removal and elution tower to increase the temperature of the low-temperature gas, thereby increasing the inlet temperature of the first-stage compressor. This is beneficial to avoid increasing the inlet temperature by opening a return valve, thereby enabling the first-stage compressor to operate at full load, and by recovering the cold of the low-temperature gas for use as a cooling medium for other processes, energy consumption can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of a cold recovery subsystem according to some embodiments of the present application.

[0019] Figure 2 is a schematic diagram of a cold recovery subsystem according to some other embodiments of the present application.

[0020] Figure 3 is a schematic diagram of a cold recovery subsystem according to some other embodiments of the present application.

[0021] In the figure: 10, dust removal and elution tower; 11, conveying pipeline; 20, primary compressor; 21, air inlet pipeline; 22, air outlet pipeline; 30, cold recovery device; 40, first heat exchanger; 41, first heat exchange tube pass; 42, first heat exchange shell pass; 50, first jacketed pipe; 51, high-temperature liquid inlet; 52, low-temperature liquid outlet; 60, second jacketed pipe; 61, low-temperature liquid inlet; 611, low-temperature return water branch; 62, high-temperature liquid outlet; 621, high-temperature return water branch; 70, second heat exchanger; 71, second heat exchange tube pass; 72, second heat exchange shell pass; 80, rear-end compression group; 81, third heat exchanger; 82, secondary compressor; 83, air cooler. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0023] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific protection scope of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0025] A cold recovery subsystem, used in a polysilicon waste gas cryogenic recovery system, comprises: a dust removal and leaching tower 10, a primary compressor 20 and a cold recovery device 30. The dust removal and leaching tower 10 is used to condense silicon powder and chlorosilane in the waste gas and discharge low-temperature gas; the primary compressor 20 is used to compress the low-temperature gas and discharge the high-temperature gas; the cold recovery device 30 is arranged between the dust removal and leaching tower 10 and the primary compressor 20, so as to exchange heat with the low-temperature gas.

[0026] It is understandable that in the related art, by controlling the opening of the return valve of the primary compressor 20 to about 15%, a small amount of compressed high-temperature gas returns to the inlet of the primary compressor 20 through the return valve, and then mixes with the low-temperature gas discharged from the dust removal and washing tower 10, so as to increase the inlet temperature of the primary compressor 20. However, due to the opening of the return valve, the primary compressor 20 cannot operate at full load, thereby affecting the working efficiency of the polysilicon processing cryogenic recovery system.

[0027] In this embodiment, by setting a cold recovery device 30 between the dust removal and leaching tower 10 and the primary compressor 20, the cold recovery device 30 can achieve heat exchange with the low-temperature gas discharged from the dust removal and leaching tower 10 to increase the temperature of the low-temperature gas, thereby increasing the inlet temperature of the primary compressor 20, which is beneficial to avoid increasing the inlet temperature by opening the one-return valve, thereby enabling the primary compressor 20 to operate at full load. In other words, the one-return valve of the primary compressor 20 can be closed, and then the inlet temperature is increased on the basis of the full-load operation of the primary compressor 20, which is beneficial to extend the service life of the primary compressor 20. It is worth mentioning that by recovering the cold of the low-temperature gas and using it as a cooling medium for other processes, energy consumption can be reduced.

[0028] In some embodiments, the cold recovery device 30 includes a first heat exchanger 40, which has a first heat exchange tube side 41 and a first heat exchange shell side 42. One of the first heat exchange tube side 41 and the first heat exchange shell side 42 is connected to the outlet of the dust removal and elution tower 10 and the inlet of the first-stage compressor 20, and the other of the first heat exchange tube side 41 and the first heat exchange shell side 42 is connected to the outlet of the first-stage compressor 20.

[0029] That is to say, through the first heat exchanger 40, the low-temperature gas discharged from the dust removal and leaching tower 10 can be heat exchanged with the high-temperature gas discharged from the first-stage compressor 20, thereby increasing the temperature of the low-temperature gas, increasing the inlet temperature of the first-stage compressor 20, and reducing the temperature of the high-temperature gas. It can be understood that through the heat exchange between the high-temperature gas and the low-temperature gas, it is beneficial to make the waste heat of the high-temperature gas and the coldness of the low-temperature gas be more fully recycled, thereby reducing the additional heating device for heating the low-temperature gas and the additional cooling device for cooling the high-temperature gas, thereby reducing energy consumption and reducing production costs. In a specific embodiment, the temperature of the high-temperature gas discharged from the first-stage compressor 20 is 80°C to 100°C. Through the heat exchange between the high-temperature gas and the low-temperature gas by the first heat exchanger 40, the inlet temperature of the first-stage compressor 20 can be increased to about 0°C, so that the compressor can operate under better working conditions.

[0030] In a specific embodiment, the cold energy recovery subsystem further includes a delivery pipeline 11, an air inlet pipeline 21 and an air outlet pipeline 22. The delivery pipeline 11 is used to connect the air outlet of the dust removal and elution tower 10 and the first heat exchange shell 42 of the first heat exchanger 40. The air inlet pipeline 21 is used to connect the first heat exchange shell 42 and the inlet of the first-stage compressor 20, so that the low-temperature gas enters the first-stage compressor 20 after passing through the first heat exchange shell 42. The air outlet pipeline 22 connects the outlet of the first-stage compressor 20 and the first heat exchange tube 41 of the first heat exchanger 40, so that the high-temperature gas passes through the first heat exchange tube 41, thereby realizing heat exchange between the high-temperature gas and the low-temperature gas in the first heat exchange shell 42.

[0031] That is, the low-temperature gas discharged from the dust removal and leaching tower 10 enters the primary compressor 20 through the delivery pipeline 11, the first heat exchange shell 42 and the air inlet pipeline 21 in sequence, and the high-temperature gas discharged from the primary compressor 20 passes through the outlet pipeline 22 and the first heat exchange tube 41 in sequence, so that the low-temperature gas and the high-temperature gas achieve heat exchange in the first heat exchanger 40. It can be understood that the low-temperature gas passes through the first heat exchange shell 42 of the first heat exchanger 40, and the high-temperature gas passes through the first heat exchange tube 41, which is conducive to reducing the waste heat of the high-temperature gas from being dissipated to the external environment, so that the waste heat of the high-temperature gas is absorbed by the low-temperature gas as much as possible, which is conducive to increasing the temperature of the low-temperature gas and reducing the waste heat of the high-temperature gas.

[0032] Furthermore, the first heat exchanger 40 is placed vertically, so that the low-temperature gas passes through the first heat exchange shell 42 from bottom to top, and the high-temperature gas passes through the first heat exchange tube 41 from top to bottom, which is conducive to more complete heat exchange between the high-temperature gas and the low-temperature gas.

[0033] It is understandable that the low-temperature gas can also pass through the first heat exchange tube 41 of the first heat exchanger 40, and the high-temperature gas can pass through the first heat exchange shell 42, so that part of the waste heat of the high-temperature gas is used to increase the temperature of the low-temperature gas, and part of the waste heat of the high-temperature gas is dissipated from the shell of the first heat exchanger 40 to the external environment, which is conducive to faster reduction of the temperature of the high-temperature gas. This application does not make specific restrictions on this.

[0034] In other embodiments, the cold recovery device 30 includes a first jacket pipe 50, an air inlet pipe 21 and an air outlet pipe 22, the air inlet pipe 21 is used to connect the air outlet of the dust removal and elution tower 10 and the inlet of the first-stage compressor 20, the air outlet pipe 22 is connected to the outlet of the first-stage compressor 20, the first jacket pipe 50 is arranged on the outer peripheral side of the air inlet pipe 21, and jacket water can be filled between the first jacket pipe 50 and the air inlet pipe 21, and the jacket water can exchange heat with the low-temperature gas.

[0035] That is, the low-temperature gas discharged from the dust removal and washing tower 10 enters the primary compressor 20 through the air inlet pipe 21, and the compressed high-temperature gas is discharged from the primary compressor 20 through the air outlet pipe 22. It can be understood that by filling the jacket water between the first jacket pipe 50 and the air inlet pipe 21, and the temperature of the jacket water is higher than the temperature of the low-temperature gas, heat exchange is achieved between the jacket water and the low-temperature gas, so that the temperature of the low-temperature gas is increased, thereby increasing the inlet temperature of the primary compressor 20.

[0036] It can be understood that the jacket water can recover the cold energy of the low-temperature gas and can be used as a cooling medium in the cold energy recovery subsystem or other processes of the polysilicon waste gas deep cold recovery system, which is beneficial to reducing energy consumption.

[0037] It is worth mentioning that the temperature of the low-temperature gas discharged from the dust removal and washing tower 10 is about -25°C. In the related art, the pipeline between the dust removal and washing tower 10 and the primary compressor 20 is required to have good low-temperature resistance. In this embodiment, by arranging a jacket pipe and jacket water on the periphery of the air intake pipeline 21, the temperature of the low-temperature gas can be increased, which is conducive to reducing the low-temperature resistance requirements for the air intake pipeline 21, and even ordinary pipelines can be used.

[0038] In at least one embodiment, the cold recovery device 30 also includes a second jacket tube 60, which is arranged on the outer peripheral side of the gas outlet pipe 22, so that jacket water can be filled between the second jacket tube 60 and the gas outlet pipe 22; the first jacket tube 50 has a high-temperature liquid inlet 51 and a low-temperature liquid outlet 52, and the second jacket tube 60 has a low-temperature liquid inlet 61 and a high-temperature liquid outlet 62, wherein the high-temperature liquid inlet 51 and the high-temperature liquid outlet 62 are connected by a high-temperature return water branch 621, and the low-temperature liquid outlet 52 and the low-temperature liquid inlet 61 are connected by a low-temperature return water branch 611.

[0039] That is, the low-temperature gas discharged from the dust removal and leaching tower 10 enters the primary compressor 20 through the air inlet pipe 21, and the compressed high-temperature gas is discharged from the primary compressor 20 through the air outlet pipe 22. Further, a first jacket pipe 50 is provided on the periphery of the air inlet pipe 21, and a second jacket pipe 60 is provided on the periphery of the air outlet pipe 22, and the high-temperature liquid inlet 51 of the first jacket pipe 50 is connected with the high-temperature liquid outlet 62 of the second jacket pipe 60, and the low-temperature liquid outlet 52 of the first jacket pipe 50 is connected with the low-temperature liquid inlet 61 of the second jacket pipe 60, so that the jacket water can flow between the first jacket pipe 50 and the second jacket pipe 60, and then the heat exchange between the low-temperature gas and the high-temperature gas can be realized through the jacket water, which is conducive to the more sufficient recovery and utilization of the waste heat of the high-temperature gas and the coldness of the low-temperature gas, and then it is conducive to reducing the additional heating device and cooling device, reducing energy consumption and reducing production costs.

[0040] In at least one embodiment, the cold recovery device 30 further includes a second heat exchanger 70, the second heat exchanger 70 has a second heat exchange tube side 71 and a second heat exchange shell side 72, and the first jacket tube 50 has a high-temperature liquid inlet 51 and a low-temperature liquid outlet 52, wherein one of the second heat exchange tube side 71 and the second heat exchange shell side 72 is connected to the high-temperature liquid inlet 51 and the low-temperature liquid outlet 52, and the other of the second heat exchange tube side 71 and the second heat exchange shell side 72 is connected to the outlet of the first-stage compressor 20 through the outlet pipe 22.

[0041] That is, the low-temperature gas discharged from the dust removal and washing tower 10 enters the primary compressor 20 through the air inlet pipe 21, and the high-temperature gas discharged from the primary compressor 20 passes through the air outlet pipe 22 and the second heat exchanger 70 in sequence. Further, a first jacket pipe 50 is provided on the outer periphery of the air inlet pipe 21, and the high-temperature liquid inlet 51 and the low-temperature liquid outlet 52 of the first jacket pipe 50 are connected through the second heat exchanger 70, so that the jacket water can flow between the first jacket pipe 50 and the second heat exchanger 70, and then the heat exchange between the low-temperature gas and the high-temperature gas can be realized through the jacket water, which is conducive to the more sufficient recovery and utilization of the waste heat of the high-temperature gas and the coldness of the low-temperature gas.

[0042] In some embodiments, the cold recovery subsystem further includes a rear compression group 80, which is connected to the primary compressor 20 or the cold recovery device 30 and is used to cool and compress the high-temperature gas discharged from the primary compressor 20. In other words, the high-temperature gas discharged from the primary compressor 20 is further cooled and compressed by the rear compression group 80, so as to increase the gas pressure of the high-temperature gas.

[0043] Specifically, when the first heat exchanger 40 or the second heat exchanger 70 is provided, the rear compression group 80 is connected to the first heat exchanger 40 or the second heat exchanger 70, so that the high-temperature gas discharged from the primary compressor 20 passes through the first heat exchanger 40 or the second heat exchanger 70 and enters the rear compression group 80. When the second jacket pipe 60 is provided, the rear compression group 80 is connected to the primary compressor 20 through the gas outlet pipe 22.

[0044] Further, the rear compression group 80 includes a third heat exchanger 81 and a secondary compressor 82 in sequence. The third heat exchanger 81 is connected to the primary compressor 20 or the cold recovery device 30 to recover the waste heat of the high-temperature gas. The secondary compressor 82 is connected to the third heat exchanger 81 to compress the high-temperature gas. It can be understood that by setting the third heat exchanger 81, the waste heat of the high-temperature gas discharged from the primary compressor 20 can be further recovered, which is conducive to reducing the temperature of the high-temperature gas, thereby reducing the inlet temperature of the secondary compressor 82, and is conducive to extending the service life of the secondary compressor 82. At the same time, the waste heat recovered by the third heat exchanger 81 can be used in other processes of the cold recovery subsystem or the polysilicon waste gas deep cold recovery system, which is conducive to reducing energy consumption.

[0045] In some embodiments, the rear compression group 80 further includes an air cooler 83, which is connected between the third heat exchanger 81 and the first compressor 20, or between the third heat exchanger 81 and the cold recovery device 30, and is used to cool the high-temperature gas. It is understandable that in the case where the first heat exchanger 40, the second heat exchanger 70, or the second jacket pipe 60 is provided, the high-temperature gas can achieve heat exchange with the low-temperature gas, thereby preliminarily reducing the temperature of the high-temperature gas. Compared with directly transporting the high-temperature gas to the air cooler 83 for cooling, in this embodiment, the temperature of the high-temperature gas after heat exchange with the low-temperature gas is preliminarily reduced, which is conducive to reducing the number of fans running in the air cooler 83, thereby reducing energy consumption and reducing costs.

[0046] The above describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and the specification only describe the principles of the utility model. The utility model may be subject to various changes and improvements without departing from the spirit and scope of the utility model. These changes and improvements fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

Claims

1. A cold recovery subsystem for a polysilicon waste gas cryogenic recovery system, characterized in that: include: Dust removal and leaching tower, used to condense silicon powder and chlorosilane in the exhaust gas and discharge low-temperature gas; A first-stage compressor, used for compressing the low-temperature gas and discharging the high-temperature gas; The cold recovery device is arranged between the dust removal and leaching tower and the first-stage compressor, and is capable of exchanging heat with the low-temperature gas.

2. The cold recovery subsystem according to claim 1, characterized in that: The cold recovery device includes a first heat exchanger, which has a first heat exchange tube side and a first heat exchange shell side. One of the first heat exchange tube side and the first heat exchange shell side is connected to the outlet of the dust removal and leaching tower and the inlet of the first-stage compressor, and the other of the first heat exchange tube side and the first heat exchange shell side is connected to the outlet of the first-stage compressor.

3. The cold recovery subsystem according to claim 2, characterized in that: It further includes a conveying pipeline, an air inlet pipeline and an air outlet pipeline, wherein the conveying pipeline is used to connect the air outlet of the dust removal and elution tower and the first heat exchange shell side of the first heat exchanger, the air inlet pipeline is used to connect the first heat exchange shell side and the inlet of the first-stage compressor, so that the low-temperature gas enters the first-stage compressor after passing through the first heat exchange shell side, and the air outlet pipeline connects the outlet of the first-stage compressor and the first heat exchange tube side of the first heat exchanger, so as to exchange heat with the low-temperature gas in the first heat exchange shell side.

4. The cold recovery subsystem according to claim 2, characterized in that: The first heat exchanger is placed vertically so that the low-temperature gas passes through the first heat exchange shell from bottom to top, and the high-temperature gas passes through the first heat exchange tube from top to bottom.

5. The cold energy recovery subsystem according to claim 1, characterized in that: The cold recovery device includes a first jacket pipe, an air inlet pipe and an air outlet pipe, the air inlet pipe is used to connect the air outlet of the dust removal and elution tower and the inlet of the first-stage compressor, the air outlet pipe is connected to the outlet of the first-stage compressor, the first jacket pipe is arranged on the outer peripheral side of the air inlet pipe, and jacket water can be filled between the first jacket pipe and the air inlet pipe, and the jacket water can exchange heat with the low-temperature gas.

6. The cold energy recovery subsystem according to claim 5, characterized in that: The cold recovery device also includes a second jacket pipe, which is arranged on the outer peripheral side of the gas outlet pipe so that jacket water can be filled between the second jacket pipe and the gas outlet pipe; the first jacket pipe has a high-temperature liquid inlet and a low-temperature liquid outlet, and the second jacket pipe has a low-temperature liquid inlet and a high-temperature liquid outlet, wherein the high-temperature liquid inlet and the high-temperature liquid outlet are connected through a high-temperature return water branch, and the low-temperature liquid outlet and the low-temperature liquid inlet are connected through a low-temperature return water branch.

7. The cold energy recovery subsystem according to claim 5, characterized in that: The cold recovery device further includes a second heat exchanger, the second heat exchanger has a second heat exchange tube side and a second heat exchange shell side, the first jacketed pipe has a high-temperature liquid inlet and a low-temperature liquid outlet, wherein one of the second heat exchange tube side and the second heat exchange shell side is connected to the high-temperature liquid inlet and the low-temperature liquid outlet, and the other of the second heat exchange tube side and the second heat exchange shell side is connected to the outlet of the first-stage compressor through the outlet pipe.

8. The cold energy recovery subsystem according to any one of claims 1 to 7, characterized in that: It also includes a rear-end compression group, which is connected to the first-stage compressor or the cold recovery device and is used to cool and compress the high-temperature gas discharged from the first-stage compressor.

9. The cold energy recovery subsystem according to claim 8, characterized in that: The rear-end compression group includes a third heat exchanger and a secondary compressor in sequence. The third heat exchanger is connected to the primary compressor or the cold recovery device to recover and utilize the waste heat of the high-temperature gas. The secondary compressor is connected to the third heat exchanger to compress the high-temperature gas.

10. The cold energy recovery subsystem according to claim 9, characterized in that: The rear-end compression group also includes an air cooler, which is connected between the third heat exchanger and the first-stage compressor, or between the third heat exchanger and the cold recovery device, and is used to cool high-temperature gas.

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