A cryogenic liquid storage tank

Abstract

This invention relates to a cryogenic liquid storage tank, comprising a refrigeration unit (1) and a storage tank (2). The storage tank (2) includes an inner shell (21), a radiant screen (22), and an outer shell (23). The refrigeration unit (1) includes a radiant cooling head (11) and a condensing cooling head (12), wherein the radiant cooling head is connected to the radiant screen (22). Steam in the inner shell (21) carries the cooling energy of the radiant cooling head to the radiant screen (22). After being condensed by the condensing cooling head, the steam returns to the cryogenic liquid in the inner shell (21) via a liquid guide pipe (36). Compared with the prior art, this invention utilizes the liquid guide pipe to drive the steam flow to cool the radiant screen, solving the problem of uneven temperature caused by insufficient heat conduction of the radiant screen, and at the same time preventing tumbling within the cryogenic liquid container.

Description

Technical Field

[0001] This invention relates to cryogenic liquid storage tanks, and more particularly to a cryogenic liquid storage tank. Background Technology

[0002] Cryogenic liquids such as liquid helium, liquid hydrogen, liquid nitrogen, and liquefied natural gas need to be stored in cryogenic containers. Due to heat leakage, the liquid will evaporate, but the evaporated liquid can be condensed again using a refrigeration unit, thus ensuring that there is no storage loss.

[0003] Early refrigerators used GM refrigerators, which had very low cooling efficiency and were rarely used except for liquid helium storage tanks. The latest pulse tube refrigerators have significantly improved cooling efficiency compared to GM refrigerators, but the efficiency is still too low. The amount of gas released due to evaporation is still small compared to the electricity cost of the pulse tube refrigerator. However, the evaporated gas is still a loss.

[0004] Patent CN201410006565.0 discloses a cryogenic liquid storage tank, including a tank cover and a pulse tube refrigerator. The pulse tube refrigerator is mounted on the tank cover and includes a cryogenic section and a room temperature section. The cryogenic section includes a cooler, a regenerator, a heat exchanger, and a pulse tube connected in sequence. The cooler and the pulse tube are respectively connected to the room temperature section. The room temperature section compresses gas to generate a pressure wave, and the gas expands and cools at the bottom of the pulse tube. The expansion work is recovered by the expansion work recovery device in the room temperature section. The vapor condenses into liquid on the heat exchanger and flows back to the cryogenic liquid storage tank. This pulse tube refrigerator is equipped with an expansion work recovery device, which improves efficiency and makes the recondensation of evaporated gas profitable. It can be applied to cryogenic liquid storage tanks that are already widely used. However, this technology can only be used in small cryogenic containers. In large cryogenic containers, it poses a huge safety hazard and is prone to tipping over. The rollover phenomenon occurs when the liquid at the bottom of a large cryogenic container does not evaporate immediately after being heated. Evaporation occurs from the surface. Due to the limited heat conduction from the lower layer to the upper layer, the lower layer overheats. When it encounters a disturbance, it evaporates suddenly, causing a sharp increase in the pressure of the cryogenic container, which may even lead to an explosion.

[0005] In large cryogenic liquid storage tanks, especially liquid hydrogen and liquid helium storage tanks, radiation screens are required to reduce heat leakage. Radiation screens are often very large. Relying on the heat conduction of the radiation screen to transfer the cooling capacity of the refrigerator to the entire radiation screen will generate a large temperature difference on the radiation screen. As a result, the overall average temperature of the radiation screen is higher than the cooling temperature of the refrigerator, which in turn increases the heat leakage from the radiation screen to the cryogenic liquid. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art and provide a cryogenic liquid storage tank that can solve the problem of insufficient heat conduction of the radiation screen, while preventing rollover.

[0007] The objective of this invention can be achieved through the following technical solution: a cryogenic liquid storage tank, comprising a refrigeration unit and a storage tank, wherein the storage tank comprises an inner shell, a radiant screen and an outer shell, the refrigeration unit comprises a radiant cold head and a condensing cold head, wherein the radiant cold head is connected to the radiant screen, characterized in that steam in the inner shell carries the cooling energy of the radiant cold head to the radiant screen, and the steam is condensed by the condensing cold head and then returned to the cryogenic liquid in the inner shell through a liquid guide pipe.

[0008] Furthermore, the steam enters and exits the storage tank via a heat exchanger. The steam in the inner shell is discharged through a gas guide pipe, reheated by the heat exchanger, and then flows through a radiant screen for cooling. After being cooled by the radiant cold head, it is recooled by the heat exchanger and then flows through a condenser cold head to be condensed into liquid.

[0009] Alternatively, the steam, after being reheated by a heat exchanger, first flows through a radiant cold head for cooling, then flows through a radiant screen for further cooling, and finally flows through a condenser cold head after being recooled by a heat exchanger, where it is condensed into a liquid. Further, the refrigerator includes a radiant cold head and a condenser cold head, wherein the radiant cold head cools the radiant screen, and the condenser cold head cools the low-temperature liquid in the inner shell.

[0010] Furthermore, the radiant cold head is provided with a radiant cold head heat exchange channel, and the condensing cold head is provided with a condensing cold head heat exchange channel. One end of the gas guide pipe is inserted into the inner shell, and the bottom of the gas guide pipe is located above the liquid surface of the cryogenic liquid. The other end passes through the heat exchanger and is connected to the radiant tube or the radiant cold head heat exchange channel. The radiant tube is attached to the radiant screen. One end of the liquid guide pipe is connected to the condensing cold head heat exchange channel, and the other end is inserted below the liquid surface of the cryogenic liquid.

[0011] The vapor evaporated from the surface of the cryogenic liquid is reheated by the heat exchanger to a temperature lower than that of the radiant screen, and then flows through the radiant tubes laid along the radiant screen to cool the radiant screen. After being cooled by the radiant cold head, it is recooled by the heat exchanger to a temperature close to that of the condensing cold head. After being condensed into liquid by the condensing cold head, it flows into the liquid guide pipe and then into the bottom of the cryogenic liquid storage tank.

[0012] Furthermore, the pressure difference generated by the liquid column above the cryogenic liquid level within the liquid guide tube serves as the driving force for the steam flow. The advantage of this design is that it utilizes the self-generated pressure difference to drive the steam flow, thereby cooling the radiant screen and ensuring the screen's temperature is as uniform as possible.

[0013] Furthermore, the liquid guiding tube is a vacuum tube or a pipe made of a low thermal conductivity material to prevent rollover. Low thermal conductivity materials include polytetrafluoroethylene tubes, fiberglass, or carbon fiber reinforced plastics, etc.

[0014] The liquid delivery pipe can be integrated with the storage tank or be a separate component.

[0015] The liquid guide pipe can also be inserted into the bottom of the storage tank, with a liquid outlet channel at the bottom. The liquid guide pipe is suspended from the top of the storage tank, or it can be suspended from the top flange of the refrigeration unit's cold head via a bracket. The top flange is at room temperature, and the bracket can be made of a low thermal conductivity material, such as stainless steel wire, fiberglass rod, or nylon. If the refrigeration unit is a two-stage unit, the bracket can also be attached to the radiant cold head flange, thereby reducing heat loss.

[0016] The described refrigerator is a push-piston pulse tube refrigerator. The push-piston controls the phase and recovers the expansion work, which is then used to compress the gas in the compression chamber for reuse. The push-piston pulse tube refrigerator includes a drive unit and a cold head. The drive unit includes a compression piston and a push-piston. The compression chamber between the compression piston and the push-piston is connected to the radiator of the cold head. The front chamber formed between the push-piston and the compressor housing is connected to the pulse tube of the cold head. The reciprocating motion of the compression piston generates pressure waves, inputting work. After the gas is cooled by the radiator, it enters the regenerator, passes through the cold energy heat exchanger, expands in the pulse tube, and then returns to the cold energy heat exchanger to absorb heat, outputting cooling capacity.

[0017] The cold head is installed inside the storage tank and fixed by its top flange. To reduce vibration, the drive units can be arranged in pairs symmetrically, or counterweights can be used to reduce vibration.

[0018] Furthermore, in order to further homogenize the temperature of the radiation screen, the radiation tubes intermittently contact the radiation screen, that is, they contact the screen in areas of high temperature and do not contact it in areas of low temperature, thereby maximizing the uniformity of the temperature of the radiation screen.

[0019] Furthermore, the radiant cold head heat exchange channel is disposed on the radiant cold head, and the condensing cold head heat exchange channel is disposed on the condensing cold head.

[0020] Furthermore, if the radiant screen requires a large amount of cooling, an auxiliary radiant tube is added between the radiant cooling head heat exchange channel and the condensing cooling head heat exchange channel, and an auxiliary radiant cooling head heat exchange channel is added to the radiant cooling head. The radiant cooling head heat exchange channel is connected to the auxiliary radiant cooling head heat exchange channel via the auxiliary radiant tube, and the auxiliary radiant cooling head heat exchange channel is connected to the condensing cooling head heat exchange channel via a heat exchanger. Even further, multiple auxiliary heat exchange tubes and auxiliary heat exchange channels can be provided.

[0021] Furthermore, the auxiliary radiant tubes intermittently contact the radiant screen, that is, they contact the screen in areas of high temperature and do not contact it in areas of low temperature, thereby maximizing the temperature uniformity of the radiant screen.

[0022] Furthermore, to increase the liquid column height and thus the force driving the steam flow, the storage tank is equipped with a diameter that increases the installation height of the refrigeration unit, thereby increasing the liquid column height in the liquid guide pipe. Compared with the prior art, the present invention has the following advantages:

[0023] 1. This invention allows evaporated cryogenic liquid vapor to be reheated in a heat exchanger and then flow through a channel laid along the radiant screen to cool it. After being cooled by the radiant cold head, it is recooled by the heat exchanger to a temperature close to that of the condenser cold head, condenses into liquid at the condenser cold head, and flows into a liquid guide pipe. From there, it flows into the bottom of the cryogenic liquid storage tank. Alternatively, the vapor is reheated by the heat exchanger, flows through the radiant cold head, transfers its cooling capacity to the radiant screen, and then recools by the heat exchanger to a temperature close to that of the condenser cold head. After being condensed into liquid at the condenser cold head, it flows into a liquid guide pipe, and then flows into the bottom of the cryogenic liquid storage tank. This utilizes the pressure difference generated by the portion of the liquid column in the liquid guide pipe that is higher than the cryogenic liquid surface to drive the vapor flow, thereby transferring the cooling capacity of the refrigerator to the radiant screen, making the temperature of the radiant screen as uniform as possible.

[0024] 2. The liquid guiding tube of this invention uses a vacuum tube or a tube with very low thermal conductivity, which reduces the possibility of the condensed liquid being heated by the liquid in the storage tank as it flows downwards within the guiding tube, thereby maintaining a basically constant temperature. Therefore, the condensed liquid flows out from the bottom of the cryogenic container, causing the coldest liquid to sink to the bottom. This results in a temperature distribution from low to high temperature within the cryogenic container, thus preventing rollover. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the cryogenic liquid storage tank in Embodiment 1 of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the cryogenic liquid storage tank in Embodiment 2 of the present invention;

[0027] Figure 3 This is an overall assembly outline drawing of Embodiment 3 of the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of the two-stage stepped piston pulse tube refrigerator of Embodiment 1 of the present invention;

[0029] Figure 5 for Figure 4 Overall assembly outline drawing;

[0030] Figure 6 This is a schematic diagram of the structure of the compressor and the push piston assembly arranged in pairs according to Embodiment 2 of the present invention.

[0031] In the diagram: Refrigeration unit 1, radiant cooling head 11, condensing cooling head 12;

[0032] Storage tank 2, inner shell 21, radiation screen 22, outer shell 23, cryogenic liquid level 24, tank diameter 25;

[0033] 31. Gas guide pipe, 32. Heat exchanger, 33. Radiant tube, 34. Radiant cold head heat exchange channel, 35. Condensing cold head heat exchange channel, 36. Liquid guide pipe, 37. Auxiliary radiant tube, 38. Radiant cold head auxiliary heat exchange channel.

[0034] 10-Drive Unit

[0035] 111-Compression chamber, 113-Compression piston, 123-Stepped push piston, 121-Push piston first front chamber, 122-Push piston second front chamber;

[0036] 20-Cold Head

[0037] 211-Radiator, 212-First regenerator, 214-First pulse tube, 222-Second regenerator, 224-Second pulse tube;

[0038] 2111-Top flange, 2121-Regenerator shell, 2131-Radiation cold head flange, 2221-Second stage regenerator shell, 2231-Second stage cold exchanger outer fins. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0040] This invention primarily utilizes steam to transfer the cooling energy of the refrigeration unit to the radiant screen, resulting in a more uniform temperature distribution on the screen. The steam flow originates from the pressure difference between the liquid condensed by the refrigeration unit and the liquid level in the storage tank. Simultaneously, the condensed liquid flows out from the bottom of the storage tank, thus preventing rollover.

[0041] The following detailed explanation will be provided through specific examples.

[0042] Example 1

[0043] like Figure 1 As shown, a cryogenic liquid storage tank includes a refrigeration unit 1 and a storage tank 2. The storage tank 2 includes an inner shell 21, a radiation shield 22, and an outer shell 23. The inner shell 21 stores cryogenic liquids such as liquid hydrogen. The space between the inner shell 21 and the outer shell 23 is a vacuum. Generally, the space between the inner shell 21, the radiation shield 22, and the outer shell 23 contains multiple layers of insulation material, such as multiple layers of aluminized polyester foil film, with yarn separating each layer.

[0044] The refrigerator 1 is a two-stage stepped piston pulse tube refrigerator, including a radiant cold head 11 (or a first-stage cold head) and a condensing cold head 12 (or a second-stage cold head), wherein the radiant cold head 11 cools the radiant screen 22, and the condensing cold head 12 cools the cryogenic liquid in the inner shell 21.

[0045] The steam in the inner shell 21 flows through the heat exchange channel and cools the radiation screen 22. After being condensed into liquid, it returns to the low-temperature liquid in the inner shell 21.

[0046] Specifically, the heat exchange channel includes a gas guide pipe 31, a heat exchanger 32, a radiant tube 33, a radiant cold head heat exchange channel 34, a condenser cold head heat exchange channel 35, and a liquid guide pipe 36 connected in sequence. One end of the gas guide pipe 31 communicates with the interior of the inner shell 21, and the bottom of the gas guide pipe 31 is located above the surface of the cryogenic liquid. The other end passes through the heat exchanger 32 and connects to the radiant tube 33, which is attached to the radiant screen 22. One end of the liquid guide pipe 36 is connected to the condenser cold head heat exchange channel 35, and the other end is inserted below the surface 24 of the cryogenic liquid. The radiant cold head heat exchange channel 34 is located on the radiant cold head 11, and the condenser cold head heat exchange channel 35 is located on the condenser cold head 12.

[0047] The vapor above the low-temperature liquid surface 24 (if it is liquid hydrogen, the temperature is generally 20K) enters the heat exchanger 32 from the gas guide pipe 31, is reheated, flows into the radiant tube 33, the temperature rises, and then flows into the radiant cold head heat exchange channel 34 for cooling. After being recooled, it enters the condenser cold head heat exchange channel 35 and condenses into liquid, then enters the liquid guide pipe 36.

[0048] The radiant tube 33 is attached to the radiant screen 22, and there is good thermal conductivity between them, which cools the radiant screen. The steam heated by the radiant screen enters the heat exchange channel 34 of the radiant cold head and is cooled, thereby transferring the cold energy of the radiant cold head 11 away.

[0049] The pressure difference generated by the liquid column above the cryogenic liquid level within the liquid guide tube 36 is the driving force for steam to enter the gas guide tube 31. The liquid guide tube 36 is a vacuum tube to prevent tipping. It can also be a tube made of a material with very poor thermal conductivity.

[0050] The above design allows steam to flow and thus cool the radiation screen, making the temperature of the radiation screen as uniform as possible.

[0051] To further homogenize the temperature of the radiation screen 22, the radiation tube 33 can intermittently contact the radiation screen 22, that is, it contacts the area with high temperature and does not contact the area with low temperature, thereby maximizing the uniformity of the temperature of the radiation screen.

[0052] Since the temperature of the radiant screen is higher than that of the steam inside the tank, directly returning the steam to the storage tank would significantly increase the heat load on the condenser head. The function of heat exchanger 32 is to thermally insulate the radiant screen from the steam inside the storage tank. Steam flows through the heat exchanger, exits the tank via the heat exchanger, and returns via the same route. When the returning steam enters the condenser head heat exchange channel 35 through heat exchanger 32, it is cooled by the outflowing steam, so its temperature is essentially the same as when it left. Ideally, the temperatures would be equal, with no temperature difference. This way, the steam flow would not transfer heat from the radiant screen to the condenser head. In reality, heat exchange requires a temperature difference; therefore, the steam will transfer heat from the radiant screen to the condenser head. The greater the temperature difference, the greater the heat transferred. Therefore, heat exchanger 32 needs sufficient heat exchange efficiency to minimize the temperature difference.

[0053] The aforementioned refrigerator 1 is a two-stage stepped piston pulse tube refrigerator, and its structure is as follows: Figure 4 As shown, it includes a drive unit 10 and a cold head 20. The drive unit 10 includes a compressor and a push piston assembly. The compressor includes a compression piston 113 and a stepped push piston 123. A compression chamber 111 is formed between the compression piston 113 and the stepped push piston 123. A first push piston front chamber 121 and a second push piston front chamber 122 are formed between the stepped push piston 123 and the compressor housing.

[0054] The cold head 20 includes a radiator 211, a first regenerator 212, a radiant cold head 11, a first pulse tube 214, a second regenerator 222, a condenser cold head 12, and a second pulse tube 224. The compression chamber 111 is connected to the radiator 211, the first front chamber 121 of the push piston is connected to the first pulse tube 214, and the second front chamber 122 of the push piston is connected to the second pulse tube 224.

[0055] The reciprocating motion of the compression piston 113 generates pressure waves, inputting work. After the gas dissipates heat through the radiator 211, it enters the regenerator 212. Part of it passes through the radiant cold head 11 (or the first-stage cold head or the first-stage heat exchanger) and enters the first pulse tube 214, expands, and then returns to the radiant cold head 11 (or the second-stage cold head or the second-stage heat exchanger) to absorb heat and output cooling capacity. Another part passes through the second regenerator 222 and the condensing cold head 12, enters the second pulse tube 224, expands, and then returns to the condensing cold head 12 to absorb heat and output cooling capacity.

[0056] The piston is pushed to control the phase and recover the expansion work, and the recovered expansion work is used to compress the gas in the compression chamber 111 for reuse, so that the theoretical efficiency of the refrigeration machine reaches the Carnot efficiency.

[0057] Because the piston has a large phase adjustment capability and can recover expansion work, this type of pulse tube refrigerator is currently the most efficient pulse tube refrigerator.

[0058] When using, such as Figure 5 and 1 As shown, the drive unit 10 can be integrated into one unit. The top flange 2111 of the refrigeration cold head 20 is provided for installing and fixing the cold head onto the shell 23 of the cryogenic liquid storage tank. 2121 is the shell of the regenerator, 2131 is the flange of the radiant cold head, which is used to conduct the cooling capacity of the radiant cold head (or the first stage cooling capacity) and to fix it to the radiant screen 22. 2221 is the shell of the second stage regenerator, and 2231 is the outer fin of the condensing cold head (or the second stage cooling capacity heat exchanger), which is used to condense gas and can be called the condensing surface.

[0059] The first and second front chambers of the pusher piston are formed by a stepped pusher piston and a stepped cylinder. The chamber connected to the first pulse canal is called the first front chamber of the pusher piston, and the chamber connected to the second pulse canal is called the second front chamber of the pusher piston. In the diagram, the chamber on the left, connected to the first pulse canal, is called the first front chamber of the pusher piston. If the chamber on the right is connected to the first pulse canal, then the chamber on the right is called the first front chamber of the pusher piston.

[0060] The radiant cold head 11 can be called the pre-stage cold head, radiant screen cold head, or first-stage cold head, and the condensing cold head 12 can be called the final-stage cold head, condensing cold head, or second-stage cold head.

[0061] Because steam can carry cooling energy to the radiant screen further away from the pre-cooling head, the pre-cooling head's cooling of the radiant screen relies not only on the radiant screen's heat conduction, resulting in a more uniform temperature distribution on the radiant screen. Alternatively, with good temperature uniformity, the radiant screen can be thinned further.

[0062] Example 2

[0063] like Figure 2 As shown, if the radiant screen requires a large amount of cooling, an auxiliary radiant tube 37 is added after the radiant cold head heat exchange channel 34. An auxiliary radiant cold head heat exchange channel 38 is added to the radiant cold head 11. The radiant cold head heat exchange channel 34 is connected to the auxiliary radiant cold head heat exchange channel 38 through the auxiliary radiant tube 37. The auxiliary radiant cold head heat exchange channel 38 is connected to the condensing cold head heat exchange channel 35 through the heat exchanger 32.

[0064] The auxiliary radiant tube 37 and the radiant screen 22 have good thermal conductivity. After being cooled in the radiant cold head heat exchange channel 34, the steam enters the auxiliary radiant tube 37, is heated, enters the radiant cold head auxiliary heat exchange channel 38, is cooled, and enters the heat exchanger 32. After being recooled, it is condensed into liquid and flows into the liquid guide pipe 36.

[0065] To further homogenize the temperature of the radiation screen, the auxiliary radiation tube 37 can intermittently contact the radiation screen 22, that is, it contacts the area with high temperature and does not contact the area with low temperature, thereby maximizing the uniformity of the temperature of the radiation screen 22.

[0066] Of course, multiple auxiliary heat exchange tubes and auxiliary heat exchange channels can be set as needed.

[0067] The structure of the refrigeration unit is as follows Figure 6 As shown, in order to reduce vibration, the compressor and the push piston assembly are arranged in pairs opposite each other, otherwise the same as in Embodiment 1.

[0068] Example 3

[0069] like Figure 3 As shown, in order to increase the height of the liquid column in the liquid guide pipe 36 and thus increase the force driving the steam flow, a tank diameter of 25 can be added to the storage tank 2 to increase the installation height of the refrigeration unit and thus increase the height of the liquid column.

[0070] If there are multiple radiant screens, the method described in this case can employ a multi-stage refrigerator and multiple radiant tubes to cool all the screens. Alternatively, at least one radiant screen can be cooled using radiant tubes, while the others can be directly cooled by refrigerator cold heads. The refrigerator can be any type of pulse tube refrigerator, GM refrigerator, Stirling refrigerator, or other refrigerator type. The push-piston pulse tube refrigerator is currently the most efficient and a better choice. The push-piston controls the phase and recovers the expansion work, which is then reused to compress the gas in the compression chamber, thus enabling the refrigerator to achieve a theoretical efficiency comparable to Carnot efficiency.

[0071] The refrigeration unit can be a two-stage or multi-stage refrigeration unit. It can also consist of two single-stage refrigeration units, one for cooling the radiant screen and the other for condensing the steam.

[0072] Heat exchangers can be plate-fin, shell-and-tube, or plate types.

[0073] One end of the air guide tube 31 can be inserted into the inner shell 21 or embedded in the wall of the inner shell 21. The wall of the inner shell 21 has holes that communicate with the air guide tube 31.

[0074] Example 4

[0075] See Figure 1 The steam in the inner shell 21 is discharged through the gas guide pipe 31, reheated by the heat exchanger 32, and then flows through the radiant cold head heat exchange channel 34 to be cooled by the radiant cold head 11. It then enters the radiant tube 3 to cool the radiant screen 22, and after being recooled by the heat exchanger 32, it flows into the condenser cold head heat exchange channel 35, and is condensed into liquid by the radiant cold head 11. The rest is the same as in Example 1.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Any changes, substitutions, modifications, or simplifications made by those skilled in the art within the scope of the present invention are equivalent transformations and do not depart from the spirit of the present invention, and should also fall within the protection scope of the claims of the present invention.

Claims

1. A cryogenic liquid storage tank comprising a refrigerator (1) and a storage tank (2), said storage tank (2) comprising an inner shell (21), a radiation shield (22) and an outer shell (23), said refrigerator (1) comprising a radiation cold head (11) and a condenser cold head (12), wherein the radiation cold head (11) is connected to the radiation shield (22), characterized in that, The steam in the inner shell (21) brings the cold of the radiation cold head (11) to the radiation screen (22), and the steam is condensed by the condensing cold head (12) and returned to the low-temperature liquid in the inner shell (21) through the liquid guide pipe (36); The radiation cold head (11) is provided with a radiation cold head heat exchange channel (34), and the condensing cold head (12) is provided with a condensing cold head heat exchange channel (35); wherein one end of the gas guide pipe (31) is inserted into the inner shell (21), and the bottom of the gas guide pipe (31) is located above the liquid level of the low-temperature liquid, and the other end is connected with the radiation pipe (33) and the radiation cold head heat exchange channel (34) or the radiation cold head heat exchange channel (34) and the radiation pipe (33) after passing through the heat exchanger (32); the radiation pipe (33) is attached to the radiation screen (22).

2. A cryogenic liquid storage tank as claimed in claim 1, wherein The steam enters and exits the storage tank through the heat exchanger (32), the steam in the inner shell (21) is guided out through the gas guide pipe (31), reheated by the heat exchanger (32), flows through the radiation screen (22) to cool it, and then flows through the radiation cold head (11) to be cooled, and then flows through the condensing cold head (12) after being re-cooled by the heat exchanger (32), and is condensed into liquid; Or the steam reheated by the heat exchanger (32) first flows through the radiation cold head (11) to be cooled, then flows through the radiation screen (22) to cool it, and then flows through the condensing cold head (12) after being re-cooled by the heat exchanger (32), and is condensed into liquid.

3. A cryogenic liquid storage tank as defined in claim 1, wherein One end of the liquid guide pipe (36) is connected to the condensing cold head heat exchange channel (35), and the other end is inserted into the low-temperature liquid.

4. A cryogenic liquid storage tank as defined in claim 1, wherein The pressure difference generated by the liquid column in the liquid guide pipe (36) higher than the liquid level of the low-temperature liquid is the driving force for the flow of steam.

5. A cryogenic liquid storage tank as defined in claim 1, wherein The liquid guide pipe (36) is a vacuum pipe or a pipe with low thermal conductivity.

6. A cryogenic liquid storage tank as defined in claim 1, wherein The radiation pipe (33) intermittently contacts the radiation screen (22), that is, it contacts at high temperature and does not contact at low temperature.

7. A cryogenic liquid storage tank as defined in claim 1, wherein An auxiliary radiation pipe (37) is additionally arranged between the radiation cold head heat exchange channel (34) and the condensing cold head heat exchange channel (35), and a radiation cold head auxiliary heat exchange channel (38) is additionally arranged on the radiation cold head (11); the radiation cold head heat exchange channel (34) is connected to the radiation cold head auxiliary heat exchange channel (38) through the auxiliary radiation pipe (37), and the radiation cold head auxiliary heat exchange channel (38) is connected to the condensing cold head heat exchange channel (35) through the heat exchanger (32).

8. A cryogenic liquid storage tank as claimed in claim 7, wherein, The auxiliary radiation pipe (37) intermittently contacts the radiation screen (22).

9. A cryogenic liquid storage tank as defined in claim 1, wherein, The storage tank (2) is provided with a tank diameter (25) for increasing the installation height of the refrigerator.

10. A cryogenic liquid storage tank as defined in claim 1, wherein The refrigerator is a multi-stage push-piston pulse tube refrigerator, the push-piston controls the phase and recovers the expansion work, and the recovered expansion work is used for recycling the gas compressed in the compression chamber.

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